Development of SiC Nanoparticles and Second Phases Synergistically Reinforced Mg-Based Composites Processed by Multi-Pass Forging with Varying Temperatures

PubMed Central

Nie, Kaibo; Guo, Yachao; Deng, Kunkun; Wang, Xiaojun; Wu, Kun

2018-01-01

In this study, SiC nanoparticles were added into matrix alloy through a combination of semisolid stirring and ultrasonic vibration while dynamic precipitation of second phases was obtained through multi-pass forging with varying temperatures. During single-pass forging of the present composite, as the deformation temperature increased, the extent of recrystallization increased, and grains were refined due to the inhibition effect of the increasing amount of dispersed SiC nanoparticles. A small amount of twins within the SiC nanoparticle dense zone could be found while the precipitated phases of Mg17Al12 in long strips and deformation bands with high density dislocations were formed in the particle sparse zone after single-pass forging at 350 °C. This indicated that the particle sparse zone was mainly deformed by dislocation slip while the nanoparticle dense zone may have been deformed by twinning. The yield strength and ultimate tensile strength of the composites were gradually enhanced through increasing the single-pass forging temperature from 300 °C to 400 °C, which demonstrated that initial high forging temperature contributed to the improvement of the mechanical properties. During multi-pass forging with varying temperatures, the grain size of the composite was gradually decreased while the grain size distribution tended to be uniform with reducing the deformation temperature and extending the forging passes. In addition, the amount of precipitated second phases was significantly increased compared with that after multi-pass forging under a constant temperature. The improvement in the yield strength of the developed composite was related to grain refinement strengthening and Orowan strengthening resulting from synergistical effect of the externally applied SiC nanoparticles and internally precipitated second phases. PMID:29342883

Development of SiC Nanoparticles and Second Phases Synergistically Reinforced Mg-Based Composites Processed by Multi-Pass Forging with Varying Temperatures.

PubMed

Nie, Kaibo; Guo, Yachao; Deng, Kunkun; Wang, Xiaojun; Wu, Kun

2018-01-13

In this study, SiC nanoparticles were added into matrix alloy through a combination of semisolid stirring and ultrasonic vibration while dynamic precipitation of second phases was obtained through multi-pass forging with varying temperatures. During single-pass forging of the present composite, as the deformation temperature increased, the extent of recrystallization increased, and grains were refined due to the inhibition effect of the increasing amount of dispersed SiC nanoparticles. A small amount of twins within the SiC nanoparticle dense zone could be found while the precipitated phases of Mg 17 Al 12 in long strips and deformation bands with high density dislocations were formed in the particle sparse zone after single-pass forging at 350 °C. This indicated that the particle sparse zone was mainly deformed by dislocation slip while the nanoparticle dense zone may have been deformed by twinning. The yield strength and ultimate tensile strength of the composites were gradually enhanced through increasing the single-pass forging temperature from 300 °C to 400 °C, which demonstrated that initial high forging temperature contributed to the improvement of the mechanical properties. During multi-pass forging with varying temperatures, the grain size of the composite was gradually decreased while the grain size distribution tended to be uniform with reducing the deformation temperature and extending the forging passes. In addition, the amount of precipitated second phases was significantly increased compared with that after multi-pass forging under a constant temperature. The improvement in the yield strength of the developed composite was related to grain refinement strengthening and Orowan strengthening resulting from synergistical effect of the externally applied SiC nanoparticles and internally precipitated second phases.

Microstructural and mechanical responses to various rolling speeds determined in multi-pass break-down rolling of AZ31B alloy

NASA Astrophysics Data System (ADS)

Jia, Weitao; Tang, Yan; Ning, Fangkun; Le, Qichi; Cui, Jianzhong

2018-04-01

Different rolling operations of as-cast AZ31B alloy were performed under different rolling speed (18 ∼ 72 m min‑1) and rolling pass conditions at 400 °C. Microstructural studies, tensile testing and formability evaluation relevant to each rolling operation were investigated. For 1-pass rolling, coarse average grain size (CAGS) region gradually approached the center layer as the rolling speed increased. Moreover, twins, shear bands and coarse-grain structures were the dominant components in the microstructure of plates rolled at 18, 48 and 72 m min‑1, respectively, indicating the severe deformation inhomogeneity under the high reduction per pass condition. For 2-pass rolling and 4-pass rolling, dynamic recrystallization was observed to be well and CAGS region has substantially disappeared, indicating the significant improvement in deformation uniformity and further the grain homogenization under the conditions. Microstructure uniformity degree of 2-pass rolled plates did not vary much as the rolling speed varied. On this basis, shear band distribution dominated the deformation behavior during the uniaxial tension of the 2-pass rolled plates. However, microstructure uniformity accompanied by twin distribution played a leading role in stretching the 4-pass rolled plates.

Effect of Various SPD Techniques on Structure and Superplastic Deformation of Two Phase MgLiAl Alloy

NASA Astrophysics Data System (ADS)

Dutkiewicz, Jan; Bobrowski, Piotr; Rusz, Stanislav; Hilser, Ondrej; Tański, Tomasz A.; Borek, Wojciech; Łagoda, Marek; Ostachowski, Paweł; Pałka, Paweł; Boczkal, Grzegorz; Kuc, Dariusz; Mikuszewski, Tomasz

2018-03-01

MgLiAl alloy containing 9 wt% Li and 1.5% Al composed of hexagonal α and bcc β phases was cast under protecting atmosphere and hot extruded. Various methods of severe plastic deformation were applied to study their effect on structure and grain refinement. Rods were subjected to 1-3 passes of Twist Channel Angular Pressing TCAP (with helical component), cyclic compression to total strain ɛ = 5 using MAXStrain Gleeble equipment, both performed at temperature interval 160-200 °C and, as third SPD method, KOBO type extrusion at RT. The TCAP pass resulted in grain refinement of α phase from 30 μm down to about 2 μm and that of β phase from 12 to 5 μm. Maxstrain cycling 10 × up to ɛ = 5 led to much finer grain size of 300 nm. KOBO method performed at RT caused average grain size refinement of α and β phases down to about 1 μm. Hardness of alloy decreased slightly with increasing number of TCAP passes due to increase of small void density. It was higher after MAXStrain cycling and after KOBO extrusion. TEM studies after TCAP passes showed higher dislocation density in the β region than in the α phase. Crystallographic relationship (001) α|| (110) β indicated parallel positioning of slip planes of both phases. Electron diffraction technique confirmed increase of grain misorientation with number of TCAP passes. Stress/strain curves recorded at temperature 200 °C showed superplastic forming after 1st and 3rd TCAP passes with better superplastic properties due to higher elongation with increasing number of passes. Values of strain rate sensitivity coefficient m were calculated at 0.29 after 3rd TCAP pass for strain rate range 10-5 to 5 × 10-3 s-1. Deformation by MAXStrain cycling caused much more effective grain refinement with fine microtwins in α phase. Superplastic deformation was also observed in alloy deformed by KOBO method, however the value of m = 0.21 was obtained at lower temperature of deformation equal to 160 °C and deformation rate in the range 10-5 to 5 × 10-3. Tensile samples deformed superplastically showed grain growth and void formation caused by grain boundary slip. Summarizing, all methods applied resulted in sufficient grain refinement to obtain the effect of superplastic deformation for alloys of two phase α + β structure.

Numerical simulation of the pairwise interaction of deformable cells during migration in a microchannel

NASA Astrophysics Data System (ADS)

Lan, Hongzhi; Khismatullin, Damir B.

2014-07-01

Leukocytes and other circulating cells deform and move relatively to the channel flow in the lateral and translational directions. Their migratory property is important in immune response, hemostasis, cancer progression, delivery of nutrients, and microfluidic technologies such as cell separation and enrichment, and flow cytometry. Using our three-dimensional computational algorithm for multiphase viscoelastic flow, we have investigated the effect of pairwise interaction on the lateral and translational migration of circulating cells in a microchannel. The numerical simulation data show that when two cells with the same size and small separation distance interact, repulsive interaction take place until they reach the same lateral equilibrium position. During this process, they undergo swapping or passing, depending on the initial separation distance between each other. The threshold value of this distance increases with cell deformation, indicating that the cells experiencing larger deformation are more likely to swap. When a series of closely spaced cells with the same size are considered, they generally undergo damped oscillation in both lateral and translational directions until they reach equilibrium positions where they become evenly distributed in the flow direction (self-assembly phenomenon). A series of cells with a large lateral separation distance could collide repeatedly with each other, eventually crossing the centerline and entering the other side of the channel. For a series of cells with different deformability, more deformable cells, upon impact with less deformable cells, move to an equilibrium position closer to the centerline. The results of our study show that the bulk deformation of circulating cells plays a key role in their migration in a microchannel.

Rapid, Repeat-sample Monitoring of Crustal Deformations and Environmental Phenomena with the Uninhabited Aerial Vehicle Synthetic Aperture Radar

NASA Technical Reports Server (NTRS)

Smith, Robert C.

2006-01-01

The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR) mission being developed by the Jet Propulsion Laboratory and the Dryden Flight Research Center in support of NASA s Science Mission Directorate. UAVSAR's unique ability to fly a repeatable flight path, along with an electronically steerable array, allows interferometric data to be obtained with accuracies measured in millimeters. Deploying the radar on an airborne platform will also allow for radar images to be collected and compared with images from the same area taken hours or even years later - providing for long-term trending and near real-time notification of changes and deformations. UAVSAR s data processing algorithms will provide for near-real time data reduction providing disaster planning and response teams with highly accurate data to aid in the prediction of, and response to, natural phenomena. UAVSAR data can be applied to increasing our understanding of the processes behind solid earth, cryosphere, carbon cycle and other areas of interest in earth science. Technologies developed for UAVSAR may also be applicable to a future earth-orbiting InSAR mission and possibly for missions to the Moon or Mars. The UAVSAR is expected to fly on a Gulfstream III aircraft this winter, followed by a flight test program lasting until the second half of 2007. Following radar calibration and data reduction activities, the platform will be ready for science users in the summer of 2008.

Deformation Behavior and Microstructure Evolution of As-Cast 42CrMo Alloy in Isothermal and Non-isothermal Compression

NASA Astrophysics Data System (ADS)

Qin, Fangcheng; Li, Yongtang; Qi, Huiping; Lv, Zhenhua

2016-11-01

The isothermal and non-isothermal multi-pass compression tests of centrifugal casting 42CrMo steel were conducted on a Gleeble-3500 thermal simulation machine. The effects of compression passes and finishing temperatures on deformation behavior and microstructure evolution were investigated. It is found that the microstructure is homogeneous with equiaxed grains, and the flow stress does not show significant change with the increase in passes, while the peak softening coefficient increases first and then decreases during inter-pass. Moreover, the dominant mechanisms of controlled temperature and accumulated static recrystallization for grain refinement and its homogeneous distribution are found after 5 passes deformation. As the finishing temperature increases, the flow stress decreases gradually, but the dynamic recrystallization accelerates and softening effect increases, resulting in the larger grain size and homogeneous microstructure. The microhardness decreases sharply because the sufficient softening occurs in microstructure. When the finishing temperature is 890 °C, the carbide particles are precipitated in the vicinity of the grain boundaries, thus inhibiting the dislocation motion. Thus, the higher finishing temperature (≥970 °C) for centrifugal casting 42CrMo alloy should be avoided in non-isothermal multi-pass deformation, which is beneficial to grain refinement and properties improvement.

Accumulative Roll Bonding and Post-Deformation Annealing of Cu-Al-Mn Shape Memory Alloy

NASA Astrophysics Data System (ADS)

Moghaddam, Ahmad Ostovari; Ketabchi, Mostafa; Afrasiabi, Yaser

2014-12-01

Accumulative roll bonding is a severe plastic deformation process used for Cu-Al-Mn shape memory alloy. The main purpose of this study is to investigate the possibility of grain refinement of Cu-9.5Al-8.2Mn (in wt.%) shape memory alloy using accumulative roll bonding and post-deformation annealing. The alloy was successfully subjected to 5 passes of accumulative roll bonding at 600 °C. The microstructure, properties as well as post-deformation annealing of this alloy were investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, differential scanning calorimeter, and bend and tensile testing. The results showed that after 5 passes of ARB at 600 °C, specimens possessed α + β microstructure with the refined grains, but martensite phases and consequently shape memory effect completely disappeared. Post-deformation annealing was carried out at 700 °C, and the martensite phase with the smallest grain size (less than 40 μm) was obtained after 150 s of annealing at 700 °C. It was found that after 5 passes of ARB and post-deformation annealing, the stability of SME during thermal cycling improved. Also, tensile properties of alloys significantly improved after post-deformation annealing.

Effect of deformation path on microstructure, microhardness and texture evolution of interstitial free steel fabricated by differential speed rolling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamad, Kotiba; Chung, Bong Kwon; Ko, Young Gun, E-mail: younggun@ynu.ac.kr

2014-08-15

This paper reports the effect of the deformation path on the microstructure, microhardness, and texture evolution of interstitial free (IF) steel processed by differential speed rolling (DSR) method. For this purpose, total height reductions of 50% and 75% were imposed on the samples by a series of differential speed rolling operations with various height reductions per pass (deformation levels) ranging from 10 to 50% under a fixed roll speed ratio of 1:4 for the upper and lower rolls, respectively. Microstructural observations using transmission electron microscopy and electron backscattered diffraction measurements showed that the samples rolled at deformation level of 50%more » had the finest mean grain size (∼ 0.5 μm) compared to the other counterparts; also the samples rolled at deformation level of 50% showed a more uniform microstructure. Based on the microhardness measurements along the thickness direction of the deformed samples, gradual evolution of the microhardness value and its homogeneity was observed with the increase of the deformation level per pass. Texture analysis showed that, as the deformation level per pass increased, the fraction of alpha fiber and gamma fiber in the deformed samples increased. The textures obtained by the differential speed rolling process under the lubricated condition would be equivalent to those obtained by the conventional rolling. - Highlights: • Effect of DSR deformation path on microstructure of IF steel is significant. • IF steel rolled at deformation level of 50% has the ultrafine grains of ∼ 0.5 μm. • Rolling texture components are pronounced with increasing deformation level.« less

Three-dimensional flow characteristics of aluminum alloy in multi-pass equal channel angular pressing

NASA Astrophysics Data System (ADS)

Jin, Young-Gwan; Son, Il-Heon; Im, Yong-Taek

2010-06-01

Experiments with a square specimen made of commercially pure aluminum alloy (AA1050) were conducted to investigate deformation behaviour during a multi-pass Equal Channel Angular Pressing (ECAP) for routes A, Bc, and C up to four passes. Three-dimensional finite element numerical simulations of the multi-pass ECAP were carried out in order to evaluate the influence of processing routes and number of passes on local flow behaviour by applying a simplified saturation model of flow stress under an isothermal condition. Simulation results were investigated by comparing them with the experimentally measured data in terms of load variations and microhardness distributions. Also, transmission electron microscopy analysis was employed to investigate the microstructural changes. The present work clearly shows that the three-dimensional flow characteristics of the deformed specimen were dependent on the strain path changes due to the processing routes and number of passes that occurred during the multi-pass ECAP.

Observations and Mitigation of RFI in ALOS PALSAR SAR Data; Implications for the Desdyni Mission

NASA Technical Reports Server (NTRS)

Rosen, Paul A.; Hensley, Scott; Le, Charles

2008-01-01

Initial examination of ALOS PALSAR synthetic aperture radar (SAR) data has indicated significant radio frequency interference (RFI) in several geographic locations around the world. RFI causes significant reduction in image contrast, introduces periodic and quasi-periodic image artifacts, and introduces significant phase noise in repeat pass interferometric data reduction. The US National Research Council Decadal Survey of Earth Science has recommended DESDynI, a Deformation, Ecosystems, and Dynamics of Ice satellite mission comprising an L-band polarimetric radar configured for repeat pass interferometry. There is considerable interest internationally in other future L-band and lower frequency systems as well. Therefore the issues of prevalence and possibilities of mitigation of RFI in these crowded frequency bands is of considerable interest. RFI is observed in ALOS PALSAR in California, USA, and in southern Egypt in data examined to date. Application of several techniques for removing it from the data prior to SAR image formation, ranging from straightforward spectral normalization to time-domain, multi-phase filtering techniques are considered. Considerable experience has been gained from the removal of RFI from P-band acquired by the GeoSAR system. These techniques applied to the PALSAR data are most successful when the bandwidth of any particular spectral component of the RFI is narrow. Performance impacts for SAR imagery and interferograms are considered in the context of DESDynI measurement requirements.

Equal Channel Angular Pressing (ECAP) and Its Application to Grain Refinement of Al-Zn-Mg-Cu Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tekeli, Sueleyman; Gueral, Ahmet

Microstructure of a metal can be considerably changed by severe plastic deformation techniques such as high pressure torsion, extrusion and equal-channel angular pressing (ECAP). Among these methods, ECAP is particularly attractive because it has a potential for introducing significant grain refinement and homogeneous microstructure into bulk materials. Typically, it reduces the grain size to the submicrometer level or even nanometer range and thus produces materials that are capable of exhibiting unusual mechanical properties. In the present study, a test unites for equal channel angular pressing was constructed and this system was used for Al-Zn-Mg-Cu alloy. After the optimization tests, itmore » was seen that the most effective lubricant for the dies was MoS{sub 2}, the pressing pressure was around 25-35 ton and the pressing speed was 2 mm/s. By using these parameters, the Al-Zn-Mg-Cu alloy was successfully ECAPed up to 14 passes at 200 deg. C using route C. After ECAP tests, the specimens were characterized by transmission electron microscope (TEM), hardness and macrostructural investigations. It was seen that the plastic deformation in the ECAPed specimens occurred from edge to the centre like whirlpool. In addition, the deformation intensity increased with increasing pass number. The grain size of the specimens effectively also decreased with increasing pass number. That is, while the grain size of unECAPed specimen was 10 {mu}m, this value decreased to 300 nm after 14 passes. At the beginning, while there was a banding tendency in the grains toward deformation direction, homogeneous and equiaxed grains were formed with increasing pass number. This grain refinement was as a result of an interaction between shear strain and thermal recovery during ECAP processing. Hardness measurements showed that the hardness values increased up to 4 passes, decreased effectively at 6th pass, again increased at 8th pass and after this pass, the hardness again decreased due to dynamic recrystallization.« less

Applicability Assessment of Uavsar Data in Wetland Monitoring: a Case Study of Louisiana Wetland

NASA Astrophysics Data System (ADS)

Zhao, J.; Niu, Y.; Lu, Z.; Yang, J.; Li, P.; Liu, W.

2018-04-01

Wetlands are highly productive and support a wide variety of ecosystem goods and services. Monitoring wetland is essential and potential. Because of the repeat-pass nature of satellite orbit and airborne, time-series of remote sensing data can be obtained to monitor wetland. UAVSAR is a NASA L-band synthetic aperture radar (SAR) sensor compact pod-mounted polarimetric instrument for interferometric repeat-track observations. Moreover, UAVSAR images can accurately map crustal deformations associated with natural hazards, such as volcanoes and earthquakes. And its polarization agility facilitates terrain and land-use classification and change detection. In this paper, the multi-temporal UAVSAR data are applied for monitoring the wetland change. Using the multi-temporal polarimetric SAR (PolSAR) data, the change detection maps are obtained by unsupervised and supervised method. And the coherence is extracted from the interfometric SAR (InSAR) data to verify the accuracy of change detection map. The experimental results show that the multi-temporal UAVSAR data is fit for wetland monitor.

UAVSAR for the Management of Natural Disasters

NASA Astrophysics Data System (ADS)

Lou, Y.; Hensley, S.; Jones, C. E.

2014-12-01

The unique capabilities of imaging radar to penetrate cloud cover and collect data in darkness over large areas at high resolution makes it a key information provider for the management and mitigation of natural and human-induced disasters such as earthquakes, volcanoes, landslides, floods, and wildfires. Researchers have demonstrated the use of UAVSAR's fully polarimetric data to determine flood extent, forest fire extent, lava flow, and landslide. The ability for UAVSAR to provide high accuracy repeated flight tracks and precise imaging geometry for measuring surface deformation to a few centimeter accuracy using InSAR techniques. In fact, UAVSAR's repeat-pass interferometry capability unleashed new potential approaches to manage the risk of natural disasters prior to the occurrence of these events by modeling and monitoring volcano inflation, earthquake fault movements, landslide rate and extent, and sink hole precursory movement. In this talk we will present examples of applications of UAVSAR for natural disaster management. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

An electron back-scattered diffraction study on the microstructure evolution of severely deformed aluminum AI6061 alloy

NASA Astrophysics Data System (ADS)

Vaseghi, M.; Karimi Taheri, A.; Kim, H. S.

2014-08-01

In this paper dynamic strain ageing behavior in an Al-Mg-Si alloy related to equal channel angular pressing (ECAP) was investigated. In order to examine the combined plastic deformation and ageing effects on microstructure evolutions and strengthening characteristics, the Al6061 alloy were subjected to phi=90° ECAP die for up to 4 passes via route Bc at high temperatures. For investigating the effects of ageing temperature and strain rate in ECAP, Vickers hardness tests were performed. The combination of the ECAP process with dynamic ageing at higher temperatures resulted in a significant increase in hardness. The microstructural evolution of the samples was studied using electron back-scattering diffraction (EBSD). The grains of Al6061 aluminum alloy were refined significantly at 100 and 150 °C with greater pass numbers and the distributions of grain size tended to be more uniform with pass number increasing. Frequency of sub-boundaries and low angle grain boundaries (LAGBs) increased at initial stage of deformation, and sub-boundaries and LAGBs evolved into highangle grain boundaries (HAGBs) with further deformation, which resulted in the high frequency of HAGBs in the alloy after ECAP 4 passes.

Pore pressure may control rupture propagation of the 2001 Mw=7.8 Kokoxili earthquake from the Kunlun fault to the Kunlun Pass fault

NASA Astrophysics Data System (ADS)

Xiao, J.; Wang, W.; He, J.

2016-12-01

The 2001 Mw=7.8 Kokoxili earthquake nucleated on the west-east tending Kunlun strike-slip fault in center of the Tibetan plateau. When the rupture propagated eastward near the Xidatan segment of the Kunlun fault, this earthquake jumped to the Kunlun Pass fault, a less matured fault that, due to the geometric orientation, was obviously clamped by the coseismic deformation before its rupture. To investigate the possible mechanism for the rupture jump, we updated the coseismic rupture model from a joint inversion of the geological, geodetic and seismic wave data. Constrained with the rupture process, a three-dimensional finite element model was developed to calculate the failure stress from elastic and poroelastic deformation of the crust during the rupture propagation. Results show that just before the rupture reached the conjunction of the Xidatan segment and the Kunlun Pass fault, the failure stress induced by elastic deformation is indeed larger on Xidatan segment of the Kunlun fault than on the Kunlun Pass fault. However, if the pore pressure resulted from undrained poroelastic deformation was invoked, the failure stress is significantly increased on the Kunlun Pass fault. Given a reasonable bound on fault friction and on poroelastic parameters, it can be seen that the poroelastic failure stress is 0.3-0.9 Mpa greater on the Kunlun Pass fault than on Xidatan segment of the Kunlun fault. We therefore argue that during the rupture process of the 2001 Mw=7.8 Kokoxili earthquake, pore pressure may play an important role on controlling the rupture propagation from the Kunlun fault to the Kunlun Pass fault.

Mission design for NISAR repeat-pass Interferometric SAR

NASA Astrophysics Data System (ADS)

Alvarez-Salazar, Oscar; Hatch, Sara; Rocca, Jennifer; Rosen, Paul; Shaffer, Scott; Shen, Yuhsyen; Sweetser, Theodore; Xaypraseuth, Peter

2014-10-01

The proposed spaceborne NASA-ISRO SAR (NISAR) mission would use the repeat-pass interferometric Synthetic Aperture Radar (InSAR) technique to measure the changing shape of Earth's surface at the centimeter scale in support of investigations in solid Earth and cryospheric sciences. Repeat-pass InSAR relies on multiple SAR observations acquired from nearly identical positions of the spacecraft as seen from the ground. Consequently, there are tight constraints on the repeatability of the orbit, and given the narrow field of view of the radar antenna beam, on the repeatability of the beam pointing. The quality and accuracy of the InSAR data depend on highly precise control of both orbital position and observatory pointing throughout the science observation life of the mission. This paper describes preliminary NISAR requirements and rationale for orbit repeatability and attitude control in order to meet science requirements. A preliminary error budget allocation and an implementation approach to meet these allocations are also discussed.

High-Intensity Small-Sided Games versus Repeated Sprint Training in Junior Soccer Players.

PubMed

Eniseler, Niyazi; Şahan, Çağatay; Özcan, Ilker; Dinler, Kıvanç

2017-12-01

The aim of this study was to compare the effects of high-intensity small-sided games training (SSGT) versus repeated-sprint training (RST) on repeated-sprint ability (RSA), soccer specific endurance performance and short passing ability among junior soccer players. The junior soccer players were recruited from of a professional team (age 16.9 ± 1.1 years). The tests included the repeated-shuttle-sprint ability test (RSSAT), Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1) and Loughborough Soccer Passing Test (LSPT). Nineteen participants were randomly assigned to either the small-sided games training (SSGTG) (n = 10) or repeated-sprint training group (RSTG) (n = 9). Small-sided games or repeated-sprint training were added to the regular training sessions for two days of the regular practice week. The Wilcoxon signed-rank and Mann-Whitney U tests were used to examine differences in groups and training effects. A time x training group effect was found in the improvement of short-passing ability for the smallsided games training group which showed significantly better scores than the repeated-sprint training group (p ≤ 0.05). Both groups showed similar improvements in RSAdecrement (p < 0.05). Only the repeated-sprint training group improved in the Yo-Yo IR1 (p < 0.05). This study clearly shows that high-intensity small-sided games training can be used as an effective training mode to enhance both repeated sprint ability and short-passing ability.

High-Intensity Small-Sided Games versus Repeated Sprint Training in Junior Soccer Players

PubMed Central

Şahan, Çağatay; Özcan, Ilker; Dinler, Kıvanç

2017-01-01

Abstract The aim of this study was to compare the effects of high-intensity small-sided games training (SSGT) versus repeated-sprint training (RST) on repeated-sprint ability (RSA), soccer specific endurance performance and short passing ability among junior soccer players. The junior soccer players were recruited from of a professional team (age 16.9 ± 1.1 years). The tests included the repeated-shuttle-sprint ability test (RSSAT), Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1) and Loughborough Soccer Passing Test (LSPT). Nineteen participants were randomly assigned to either the small-sided games training (SSGTG) (n = 10) or repeated-sprint training group (RSTG) (n = 9). Small-sided games or repeated-sprint training were added to the regular training sessions for two days of the regular practice week. The Wilcoxon signed-rank and Mann-Whitney U tests were used to examine differences in groups and training effects. A time x training group effect was found in the improvement of short-passing ability for the smallsided games training group which showed significantly better scores than the repeated-sprint training group (p ≤ 0.05). Both groups showed similar improvements in RSAdecrement (p < 0.05). Only the repeated-sprint training group improved in the Yo-Yo IR1 (p < 0.05). This study clearly shows that high-intensity small-sided games training can be used as an effective training mode to enhance both repeated sprint ability and short-passing ability. PMID:29339990

Monitoring Seawall Deformation With Repeat-Track Space-Borne SAR Images

NASA Astrophysics Data System (ADS)

Pei, Yuanyuan; Wan, Qing; Wei, Lianhuan; Fang, Zhilei; Liao, Mingsheng

2010-10-01

Seawalls are constructed to protect coastal cities from typhoon, flood and sea tide. It is necessary to monitor the deformation of seawalls in real time. Repeat-track space-borne SAR images are useful for environment monitoring, especially ground deformation monitoring. Shanghai sits on the Yangtze River Delta on China's eastern coast. Each year, the city is hit by typhoons from Pacific Ocean and threatened by the flood of the Yangtze River. PS-InSAR technique is carried out to monitor the deformation of the seawalls. Experiment exhibits that the seawalls around Pudong airport and Lingang town suffered serious deformation.

Status of a UAVSAR designed for repeat pass interferometry for deformation measurements

NASA Technical Reports Server (NTRS)

Hensley, Scott; Wheeler, Kevin; Sadowy, Greg; Miller, Tim; Shaffer, Scott; Muellerschoen, Ron; Jones, Cathleen; Zebker, Howard; Madsen, Soren; Paul, Rose

2005-01-01

NASA's Jet Propulsion Laboratory is currently implementing a reconfigurable polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track interferometric (RTI) SAR data, also known as differential interferometric measurements. Differential interferometry can provide key deformation measurements, important for the scientific studies of Earthquakes and volcanoes. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly predefined paths with great precision. The expected performance of the flight control system will constrain the flight path to be within a 10 m diameter tube about the desired flight track. The radar wilI be designed to operate on a UAV (Unpiloted Aria1 Vehicle) but will initially be demonstrated on a minimally piloted vehicle (MPV), such as the Proteus buitt by Scaled Composites or on a NASA Gulfstream III. The radar design is a fully polarimetric with an 80 MHz bandwidth (2 m range resolution) and 16 km range swath. The antenna is an electronically steered along track to assure that the actual antenna pointing can be controlled independent of the wind direction and speed. Other features supported by the antenna include an elevation monopulse option and a pulse-to-pulse resteering capability that will enable some novel modes of operation. The system will nominally operate at 45,000 ft (13800 m). The program began out as an Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).

The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

NASA Astrophysics Data System (ADS)

Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

2006-09-01

This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

Repeat GED[R] Tests Examinees: Who Persists and Who Passes? GED Testing Service [R]Research Studies, 2010-2

ERIC Educational Resources Information Center

Zhang, Jizhi; Patterson, Margaret Becker

2010-01-01

Like most high-stakes testing programs, the GED[R] testing program allows examinees who do not pass on the first attempt to retake the GED Tests. Studies and reports have described GED Tests candidates' characteristics and testing performance, but no study has targeted repeat examinees. A series of questions related to repeat examinees remains…

The distribution of deformation in parallel fault-related folds with migrating axial surfaces: comparison between fault-propagation and fault-bend folding

NASA Astrophysics Data System (ADS)

Salvini, Francesco; Storti, Fabrizio

2001-01-01

In fault-related folds that form by axial surface migration, rocks undergo deformation as they pass through axial surfaces. The distribution and intensity of deformation in these structures has been impacted by the history of axial surface migration. Upon fold initiation, unique dip panels develop, each with a characteristic deformation intensity, depending on their history. During fold growth, rocks that pass through axial surfaces are transported between dip panels and accumulate additional deformation. By tracking the pattern of axial surface migration in model folds, we predict the distribution of relative deformation intensity in simple-step, parallel fault-bend and fault-propagation anticlines. In both cases the deformation is partitioned into unique domains we call deformation panels. For a given rheology of the folded multilayer, deformation intensity will be homogeneously distributed in each deformation panel. Fold limbs are always deformed. The flat crests of fault-propagation anticlines are always undeformed. Two asymmetric deformation panels develop in fault-propagation folds above ramp angles exceeding 29°. For lower ramp angles, an additional, more intensely-deformed panel develops at the transition between the crest and the forelimb. Deformation in the flat crests of fault-bend anticlines occurs when fault displacement exceeds the length of the footwall ramp, but is never found immediately hinterland of the crest to forelimb transition. In environments dominated by brittle deformation, our models may serve as a first-order approximation of the distribution of fractures in fault-related folds.

Repeatability of the Oxford Foot Model in children with foot deformity.

PubMed

McCahill, Jennifer; Stebbins, Julie; Koning, Bart; Harlaar, Jaap; Theologis, Tim

2018-03-01

The Oxford Foot Model (OFM) is a multi-segment, kinematic model developed to assess foot motion. It has previously been assessed for repeatability in healthy populations. To determine the OFM's reliability for detecting foot deformity, it is important to know repeatability in pathological conditions. The aim of the study was to assess the repeatability of the OFM in children with foot deformity. Intra-tester repeatability was assessed for 45 children (15 typically developing, 15 hemiplegic, 15 clubfoot). Inter-tester repeatability was assessed in the clubfoot population. The mean absolute differences between testers (clubfoot) and sessions (clubfoot and hemiplegic) were calculated for each of 15 clinically relevant, kinematic variables and compared to typically developing children. Children with clubfoot showed a mean difference between visits of 2.9° and a mean difference between raters of 3.6° Mean absolute differences were within one degree for the intra and inter-rater reliability in 12/15 variables. Hindfoot rotation, forefoot/tibia abduction and forefoot supination were the most variable between testers. Overall the clubfoot data were less variable than the typically developing population. Children with hemiplegia demonstrated slightly higher differences between sessions (mean 4.1°), with the most reliable data in the sagittal plane, and largest differences in the transverse plane. The OFM was designed to measure different types of foot deformity. The results of this study show that it provides repeatable results in children with foot deformity. To be distinguished from measurement artifact, changes in foot kinematics as a result of intervention or natural progression over time must be greater than the repeatability reported here. Copyright © 2018 Elsevier B.V. All rights reserved.

Monitoring of urban subsidence with SAR interferometric point target analysis: A case study in Suzhou, China

NASA Astrophysics Data System (ADS)

Zhang, Yonghong; Zhang, Jixian; Wu, Hongan; Lu, Zhong; Guangtong, Sun

2011-10-01

Ground subsidence, mainly caused by over exploitation of groundwater and other underground resources, such as oil, gas and coal, occurs in many cities in China. The annual direct loss associated with subsidence across the country is estimated to exceed 100 million US dollar. Interferometric SAR (InSAR) is a powerful tool to map ground deformation at an unprecedented level of spatial detail. It has been widely used to investigate the deformation resulting from earthquakes, volcanoes and subsidence. Repeat-pass InSAR, however, may fail due to impacts of spatial decorrelation, temporal decorrelation and heterogeneous refractivity of atmosphere. In urban areas, a large amount of natural stable radar reflectors exists, such as buildings and engineering structures, at which radar signals can remain coherent during a long time interval. Interferometric point target analysis (IPTA) technique, also known as persistent scatterers (PS) InSAR is based on these reflectors. It overcomes the shortfalls in conventional InSAR. This paper presents a procedure for urban subsidence monitoring with IPTA. Calculation of linear deformation rate and height residual, and the non-linear deformation estimate, respectively, are discussed in detail. Especially, the former is highlighted by a novel and easily implemented 2-dimensional spatial search algorithm. Practically useful solutions that can significantly improve the robustness of IPTA, are recommended. Finally, the proposed procedure is applied to mapping the ground subsidence in Suzhou city, Jiangsu province, China. Thirty-four ERS-1/2 SAR scenes are analyzed, and the deformation information over 38,881 point targets between 1992 and 2000 are generated. The IPTA-derived deformation estimates correspond well with leveling measurements, demonstrating the potential of the proposed subsidence monitoring procedure based on IPTA technique. Two shortcomings of the IPTA-based procedure, e.g., the requirement of large number of SAR images and assumed linear plus non-linear deformation model, are discussed as the topics of further research.

Neurocognitive assessment in patients with a minor traumatic brain injury and an abnormal initial CT scan: Can cognitive evaluation assist in identifying patients who require surveillance CT brain imaging?

PubMed

Clements, Thomas W; Dunham, Michael; Kirkpatrick, Andrew; Rajakumar, Ruphus; Gratton, Carolyn; Lall, Rohan; McBeth, Paul; Ball, Chad G

2018-05-01

Evidence for repeat computed tomography (CT) in minor traumatic brain injury (mTBI) patients with intracranial pathology is scarce. The aim of this study was to investigate the utility of clinical cognitive assessment (COG) in defining the need for repeat imaging. COG performance was compared with findings on subsequent CT, and need for neurosurgery in mTBI patients (GCS 13-15 and positive CT findings). Of 152 patients, 65.8% received a COG (53.0% passed). Patients with passed COG underwent fewer repeat CT (43.4% vs. 78.7%; p = .001) and had shorter LOS (8.7 vs. 19.5; p < .05). Only 1 patient required neurosurgery after a passed COG. The negative predictive value of a normal COG was 90.6% (95%CI = 81.8%-95.4%). mTBI patients with an abnormal index CT who pass COG are less likely to undergo repeat CT head, and rarely require neurosurgery. The COG warrants further investigation to determine its role in omitting repeat head CT. Copyright © 2018 Elsevier Inc. All rights reserved.

Near-Field Deformation Associated with the South Napa Earthquake (M 6.0) Using Differential Airborne LiDAR

NASA Astrophysics Data System (ADS)

Hudnut, K. W.; Glennie, C. L.; Brooks, B. A.; Hauser, D. L.; Ericksen, T.; Boatwright, J.; Rosinski, A.; Dawson, T. E.; Mccrink, T. P.; Mardock, D. K.; Hoirup, D. F., Jr.; Bray, J.

2014-12-01

Pre-earthquake airborne LiDAR coverage exists for the area impacted by the M 6.0 South Napa earthquake. The Napa watershed data set was acquired in 2003, and data sets were acquired in other portions of the impacted area in 2007, 2010 and 2014. The pre-earthquake data are being assessed and are of variable quality and point density. Following the earthquake, a coalition was formed to enable rapid acquisition of post-earthquake LiDAR. Coordination of this coalition took place through the California Earthquake Clearinghouse; consequently, a commercial contract was organized by Department of Water Resources that allowed for the main fault rupture and damaged Browns Valley area to be covered 16 days after the earthquake at a density of 20 points per square meter over a 20 square kilometer area. Along with the airborne LiDAR, aerial imagery was acquired and will be processed to form an orthomosaic using the LiDAR-derived DEM. The 'Phase I' airborne data were acquired using an Optech Orion M300 scanner, an Applanix 200 GPS-IMU, and a DiMac ultralight medium format camera by Towill. These new data, once delivered, will be differenced against the pre-earthquake data sets using a newly developed algorithm for point cloud matching, which is improved over prior methods by accounting for scan geometry error sources. Proposed additional 'Phase II' coverage would allow repeat-pass, post-earthquake coverage of the same area of interest as in Phase I, as well as an addition of up to 4,150 square kilometers that would potentially allow for differential LiDAR assessment of levee and bridge impacts at a greater distance from the earthquake source. Levee damage was reported up to 30 km away from the epicenter, and proposed LiDAR coverage would extend up to 50 km away and cover important critical lifeline infrastructure in the western Sacramento River delta, as well as providing full post-earthquake repeat-pass coverage of the Napa watershed to study transient deformation.

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-07-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Multi-channel Spiral Twist Extrusion (MCSTE): A Novel Severe Plastic Deformation Technique for Grain Refinement

NASA Astrophysics Data System (ADS)

El-Garaihy, W. H.; Fouad, D. M.; Salem, H. G.

2018-04-01

Multi-channel Spiral Twist Extrusion (MCSTE) is introduced as a novel severe plastic deformation (SPD) technique for producing superior mechanical properties associated with ultrafine grained structure in bulk metals and alloys. The MCSTE design is based on inserting a uniform square cross-sectioned billet within stacked disks that guarantee shear strain accumulation. In an attempt to validate the technique and evaluate its plastic deformation characteristics, a series of experiments were conducted. The influence of the number of MCSTE passes on the mechanical properties and microstructural evolution of AA1100 alloy were investigated. Four passes of MCSTE, at a relatively low twisting angle of 30 deg, resulted in increasing the strength and hardness coupled with retention of ductility. Metallographic observations indicated a significant grain size reduction of 72 pct after 4 passes of MCSTE compared with the as-received (AR) condition. Moreover, the structural uniformity increased with the number of passes, which was reflected in the hardness distribution from the peripheries to the center of the extrudates. The current study showed that the MCSTE technique could be an effective, adaptable SPD die design with a promising potential for industrial applications compared to its counterparts.

Static Recrystallization Behavior of Z12CN13 Martensite Stainless Steel

NASA Astrophysics Data System (ADS)

Luo, Min; Zhou, Bing; Li, Rong-bin; Xu, Chun; Guo, Yan-hui

2017-09-01

In order to increase the hot workability and provide proper hot forming parameters of forging Z12CN13 martensite stainless steel for the simulation and production, the static recrystallization behavior has been studied by double-pass hot compression tests. The effects of deformation temperature, strain rate and inter-pass time on the static recrystallization fraction by the 2% offset method are extensively studied. The results indicate that increasing the inter-pass time and the deformation temperature as well as strain rate appropriately can increase the fraction of static recrystallization. At the temperature of 1050-1150 °C, inter-pass time of 30-100 s and strain rate of 0.1-5 s-1, the static recrystallization behavior is obvious. In addition, the kinetics of static recrystallization behavior of Z12CN13 steel has been established and the activation energy of static recrystallization is 173.030 kJ/mol. The substructure and precipitates have been studied by TEM. The results reveal that the nucleation mode is bulging at grain boundary. Undissolved precipitates such as MoNi3 and Fe3C have a retarding effect on the recrystallization kinetics. The effect is weaker than the accelerating effect of deformation temperature.

Deformational Features and Microstructure Evolution of Copper Fabricated by a Single Pass of the Elliptical Cross-Section Spiral Equal-Channel Extrusion (ECSEE) Process

NASA Astrophysics Data System (ADS)

Wang, Chengpeng; Li, Fuguo; Liu, Juncheng

2018-04-01

The objectives of this work are to study the deformational feature, textures, microstructures, and dislocation configurations of ultrafine-grained copper processed by the process of elliptical cross-section spiral equal-channel extrusion (ECSEE). The deformation patterns of simple shear and pure shear in the ECSEE process were evaluated with the analytical method of geometric strain. The influence of the main technical parameters of ECSEE die on the effective strain distribution on the surface of ECSEE-fabricated samples was examined by the finite element simulation. The high friction factor could improve the effective strain accumulation of material deformation. Moreover, the pure copper sample fabricated by ECSEE ion shows a strong rotated cube shear texture. The refining mechanism of the dislocation deformation is dominant in copper processed by a single pass of ECSEE. The inhomogeneity of the micro-hardness distribution on the longitudinal section of the ECSEE-fabricated sample is consistent with the strain and microstructure distribution features.

Evaluation of surface deformability of lipid nanocapsules by drop tensiometer technique, and its experimental assessment by dialysis and tangential flow filtration.

PubMed

Hirsjärvi, Samuli; Bastiat, Guillaume; Saulnier, Patrick; Benoît, Jean-Pierre

2012-09-15

Deformability of nanoparticles might affect their behaviour at biological interfaces. Lipid nanocapsules (LNCs) are semi-solid particles resembling a hybrid of polymer nanoparticles and liposomes. Deformability of LNCs of different sizes was modelled by drop tensiometer technique. Two purification methods, dialysis and tangential flow filtration (TFF), were applied to study experimental behaviour and deformability of LNCs in order to evaluate if these properties contributed to membrane passing. Rheological parameters obtained from the drop tensiometer analysis suggested decreasing surface deformability of LNCs with increase in diameter. Dialysis results showed that up to 10% of LNCs can be lost during the process (e.g. membrane accumulation) but no clear evidence of the membrane passing was observed. Instead, LNCs with initial size and size distribution could be found in the TFF filtrate although molecular weight cut-off (MWCO) of the membrane used was smaller than the LNC diameter. Copyright © 2012 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Zhiqian; Yamamoto, Yukinori

The processability of a Mo-containing FeCrAl alloy (Fe-13Cr-5.2Al-2Mo base, in wt%), developed for accident-tolerant nuclear fuel claddings, was evaluated through a stepwise rolling process at 400 °C under two different inter-pass annealing conditions (i.e., 650 °C for 1 h and at 870 °C for 30 min). The inter-pass annealing at 870 °C easily softened the FeCrAl alloy; however, it led to the formation of coarse grains of ~200 µm. On the other hand, the FeCrAl alloy maintained elongated, deformed grains with the inter-pass annealing at 650 °C, but the annealed samples showed relatively high deformation resistance and strong texture. Importantmore » aspects concerning the processability and microstructural control of FeCrAl alloys, such as deformation inhomogeneity, texture development, and grain coarsening, were discussed. Optimized processing conditions were recommended, based on the results, to achieve desirable microstructures with balanced processability and mechanical properties.« less

Estimating Tunnel Strain in the Weak and Schistose Rock Mass Influenced by Stress Anisotropy: An Evaluation Based on Three Tunnel Cases from Nepal

NASA Astrophysics Data System (ADS)

Panthi, Krishna Kanta; Shrestha, Pawan Kumar

2018-06-01

Total plastic deformation in tunnels passing through weak and schistose rock mass consists of both time-independent and time-dependent deformations. The extent of this total deformation is heavily influenced by the rock mass deformability properties and in situ stress condition prevailing in the area. If in situ stress is not isotropic, the deformation magnitude is not only different along the longitudinal alignment but also along the periphery of the tunnel wall. This manuscript first evaluates the long-term plastic deformation records of three tunnel projects from the Nepal Himalaya and identifies interlink between the time-independent and time-dependent deformations using the convergence law proposed by Sulem et al. (Int J Rock Mech Min Sci Geomech 24(3):145-154, 1987a, Int J Rock Mech Min Sci Geomech 24(3):155-164, 1987b). Secondly, the manuscript attempts to establish a correlation between plastic deformations (tunnel strain) and rock mass deformable properties, support pressure and in situ stress conditions. Finally, patterns of time-independent and time-dependent plastic deformations are also evaluated and discussed. The long-term plastic deformation records of 24 tunnel sections representing four different rock types of three different headrace tunnel cases from Nepal Himalaya are extensively used in this endeavor. The authors believe that the proposed findings will be a step further in analysis of plastic deformations in tunnels passing through weak and schistose rock mass and along the anisotropic stress conditions.

Plastic Deformation as a Means to Achieve Stretchable Polymer Semiconductors

NASA Astrophysics Data System (ADS)

O'Connor, Brendan

Developing intrinsically stretchable semiconductors will seamlessly transition traditional devices into a stretchable platform. Polymer semiconductors are inherently soft materials due to the weak van der Waal intermolecular bonding allowing for flexible devices. However, these materials are not typically stretchable and when large strains are applied they either crack or plastically deform. Here, we study the use of repeated plastic deformation as a means of achieving stretchable films. In this talk, critical aspects of polymer semiconductor material selection, morphology and interface properties will be discussed that enable this approach of achieving stretchable films. We show that one can employ high performance donor-acceptor polymer semiconductors that are typically brittle through proper polymer blending to significantly increase ductility to achieve stretchable films. We demonstrate a polymer blend film that can be repeatedly deformed over 65%, while maintaining charge mobility consistently above 0.15 cm2/Vs. During the stretching process we show that the films follow a well-controlled repeated deformation pattern for over 100 stretching cycles.

Influence of Accumulative Roll Bonding on the Texture and Tensile Properties of an AZ31 Magnesium Alloy Sheets

PubMed Central

Džugan, Ján; Németh, Gergely; Lukáč, Pavel; Bohlen, Jan

2018-01-01

Deformation behaviour of rolled AZ31 sheets that were subjected to the accumulative roll bonding was investigated. Substantially refined microstructure of samples was achieved after the first and second pass through the rolling mill. Sheets texture was investigated using an X-ray diffractometer. Samples for tensile tests were cut either parallel or perpendicular to the rolling direction. Tensile tests were performed at temperatures ranging from room temperature up to 300 °C. Tensile plastic anisotropy, different from the anisotropy observed in AZ31 sheets by other authors, was observed. This anisotropy decreases with an increasing number of rolling passes and increasing deformation temperature. Grain refinement and texture are the crucial factors influencing the deformation behaviour. PMID:29303975

Static-transmission-error vibratory-excitation contributions from plastically deformed gear teeth caused by tooth bending-fatigue damage

NASA Astrophysics Data System (ADS)

Mark, W. D.; Reagor, C. P.

2007-02-01

To assess gear health and detect gear-tooth damage, the vibratory response from meshing gear-pair excitations is commonly monitored by accelerometers. In an earlier paper, strong evidence was presented suggesting that, in the case of tooth bending-fatigue damage, the principal source of detectable damage is whole-tooth plastic deformation; i.e. yielding, rather than changes in tooth stiffness caused by tooth-root cracks. Such plastic deformations are geometric deviation contributions to the "static-transmission-error" (STE) vibratory excitation caused by meshing gear pairs. The STE contributions caused by two likely occurring forms of such plastic deformations on a single tooth are derived, and displayed in the time domain as a function of involute "roll distance." Example calculations are provided for transverse contact ratios of Qt=1.4 and 1.8, for spur gears and for helical-gear axial contact ratios ranging from Qa=1.2 to Qa=3.6. Low-pass- and band-pass-filtered versions of these same STE contributions also are computed and displayed in the time domain. Several calculations, consisting of superposition of the computed STE tooth-meshing fundamental harmonic contribution and the band-pass STE contribution caused by a plastically deformed tooth, exhibit the amplitude and frequency or phase modulation character commonly observed in accelerometer-response waveforms caused by damaged teeth. General formulas are provided that enable computation of these STE vibratory-excitation contributions for any form of plastic deformation on any number of teeth for spur and helical gears with any contact ratios.

Calculating the mounting parameters for Taylor Spatial Frame correction using computed tomography.

PubMed

Kucukkaya, Metin; Karakoyun, Ozgur; Armagan, Raffi; Kuzgun, Unal

2011-07-01

The Taylor Spatial Frame uses a computer program-based six-axis deformity analysis. However, there is often a residual deformity after the initial correction, especially in deformities with a rotational component. This problem can be resolved by recalculating the parameters and inputting all new deformity and mounting parameters. However, this may necessitate repeated x-rays and delay treatment. We believe that error in the mounting parameters is the main reason for most residual deformities. To prevent these problems, we describe a new calculation technique for determining the mounting parameters that uses computed tomography. This technique is especially advantageous for deformities with a rotational component. Using this technique, exact calculation of the mounting parameters is possible and the residual deformity and number of repeated x-rays can be minimized. This new technique is an alternative method to accurately calculating the mounting parameters.

Measuring fire spread rates from repeat pass airborne thermal infrared imagery

Treesearch

Douglas A. Stow; Philip J. Riggan; Emanual A. Storey; Lloyd L. Coulter

2014-01-01

The objective is to evaluate procedures for direct measurement of fire spread rates (FSRs) based on archived repeat pass airborne thermal infrared (ATIR) imagery and to identify requirements for more refined measurements of FSR and environmental factors that influence FSR. Flaming front positions are delineated on sequential FireMapper ATIR images captured at...

2017 Rapid Retreat Of Thwaites Glacier

NASA Astrophysics Data System (ADS)

Milillo, P.; Rignot, E. J.; Mouginot, J.; Scheuchl, B.

2017-12-01

We employ data from the second generation of SAR systems e.g. the Italian COSMO- SkyMed (CSK) constellation and the German TanDEM-X (TDX) formation to monitor grounding line retreat using short repeat-time interferometry and accurate InSAR DEM on Thwaites glacier in the Amundsen Sea Embayment (ASE), West Antarctica. The ASE is a marine-based ice sheet with a retrograde bed containing enough ice to raise global sea level by 120 cm. Several studies have inferred the mechanical properties of portions of ASE using observationally constrained numerical models, but these studies offer only temporal snapshots of basal mechanics owing to a dearth of observational time series. Prior attempts of grounding lines mapping have been limited because few space-borne SAR missions offer the short-term repeat pass capability required to map the differential vertical displacement of floating ice at tidal frequencies with sufficient detail to resolve grounding line boundaries in areas of fast ice deformation. Using 1-day CSK repeat pass data and TDX DEMs, we collected frequent, high-resolution grounding line measurements of Thwaites glaciers spanning 2015-2017. We compare the results with ERS data spanning 1996-2011, and Sentinel-1a 2014-2015 data. Between 2011 and 2017 we observe a maximum retreat of 5-7 km across the main Thwaites glacier tongue and Thwaites Eastern ice shelf (TEIS) corresponding to an increased retreat rate of 0.5 km/yr. Grounding line retreat has been fueled by the enhanced intrusion of warm, salty, subsurface ocean water of circumpolar deep water origin onto the continental shelf, beneath the floating ice shelf, to reach the glacier grounding zone and melt it from below at rates varying from 50 to 150 m/yr. The retreat rate varies depending on the magnitude of ice melt by the ocean, the rate of ice thinning and the shape of the glacier surface and bed topography.

Processability evaluation of a Mo-containing FeCrAl alloy for seamless thin-wall tube fabrication

DOE PAGES

Sun, Zhiqian; Yamamoto, Yukinori

2017-06-10

The processability of a Mo-containing FeCrAl alloy (Fe-13Cr-5.2Al-2Mo base, in wt%), developed for accident-tolerant nuclear fuel claddings, was evaluated through a stepwise rolling process at 400 °C under two different inter-pass annealing conditions (i.e., 650 °C for 1 h and at 870 °C for 30 min). The inter-pass annealing at 870 °C easily softened the FeCrAl alloy; however, it led to the formation of coarse grains of ~200 µm. On the other hand, the FeCrAl alloy maintained elongated, deformed grains with the inter-pass annealing at 650 °C, but the annealed samples showed relatively high deformation resistance and strong texture. Importantmore » aspects concerning the processability and microstructural control of FeCrAl alloys, such as deformation inhomogeneity, texture development, and grain coarsening, were discussed. Optimized processing conditions were recommended, based on the results, to achieve desirable microstructures with balanced processability and mechanical properties.« less

Quantifying the short- and long-term controls exerted by the basal and lateral boundaries of the Slumgullion Landslide from creepmeters and 3-D surface deformation

NASA Astrophysics Data System (ADS)

Delbridge, B. G.; Bilham, R. G.; Wang, T.; Fielding, E. J.; Burgmann, R.

2017-12-01

The Slumgullion landslide is 3.9 km long, moves persistently with peak rates of up to 2 cm/day, and exhibits daily, seasonal, and decadal accelerations. In this study, we provide geodetic observations needed to test whether the short- and long-term variations are governed by the same physical mechanisms. Specific focus is placed on disentangling the roles played by the lateral and basal landslide surfaces. In order to provide surface geodetic measurements with dense spatial resolution (pixel spacing < 10 m) spanning timescales from weeks to years, we utilize the unique capabilities of the NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne repeat-pass radar interferometry system for the characterization of 3-D surface deformation. To better understand the seasonal variation in the velocity observed at the landslide, we have collected UAVSAR acquisitions in approximately week-long pairs along four look directions during three key phases of the landslide's seasonal cycle: (1) during the slow season (fall or winter), (2) during the acceleration phase (spring), and (3) during the deceleration phase (summer). First, we process the UAVSAR data using conventional 2-pass SAR interferometry techniques, which permit the highest resolution images. However, due to the rapid deformation rates, the analysis of image pairs with temporal baselines longer than 20 days is difficult because the change in phase from one pixel to the next exceeds half the radar wavelength ( 24 cm) at the landslide margins. In order to measure year-round using the pairs of UAVSAR and satellite SAR images with temporal baselines on the order of several months to years, we use the pixel offsets measured between two SAR amplitude images. Pixel offsets provide surface displacement measurements perpendicular to- (range) and parallel to- (azimuth) the along-track direction of flight. To examine deformation rates spanning minutes to days we have installed a surface creepmeter, similar to those currently monitoring actively creeping faults such as the Hayward Fault. A tensioned flexible wire is fastened obliquely across the lateral bounding fault and wrapped around a 100 mm wheel wheel whose angular position is monitored by a Hall effect sensor, resulting in resolution of 8 microns and with a 5 m range.

Strengthening of biomedical Ni-free Co-Cr-Mo alloy by multipass "low-strain-per-pass" thermomechanical processing.

PubMed

Mori, Manami; Yamanaka, Kenta; Sato, Shigeo; Tsubaki, Shinki; Satoh, Kozue; Kumagai, Masayoshi; Imafuku, Muneyuki; Shobu, Takahisa; Chiba, Akihiko

2015-12-01

Further strengthening of biomedical Co-Cr-Mo alloys is desired, owing to the demand for improvements to their durability in applications such as artificial hip joints, spinal rods, bone plates, and screws. Here, we present a strategy-multipass "low-strain-per-pass" thermomechanical processing-for achieving high-strength biomedical Co-Cr-Mo alloys with sufficient ductility. The process primarily consists of multipass hot deformation, which involves repeated introduction of relatively small amounts of strain to the alloy at elevated temperatures. The concept was verified by performing hot rolling of a Co-28 Cr-6 Mo-0.13N (mass%) alloy and its strengthening mechanisms were examined. Strength increased monotonically with hot-rolling reduction, eventually reaching 1,400 MPa in 0.2% proof stress, an exceptionally high value. Synchrotron X-ray diffraction (XRD) line-profile analysis revealed a drastic increase in the dislocation density with an increase in hot-rolling reduction and proposed that the significant strengthening was primarily driven by the increased dislocation density, while the contributions of grain refinement were minor. In addition, extra strengthening, which originates from contributions of planar defects (stacking faults/deformation twins), became apparent for greater hot-rolling reductions. The results obtained in this work help in reconsidering the existing strengthening strategy for the alloys, and thus, a novel feasible manufacturing route using conventional hot deformation processing, such as forging, rolling, swaging, and drawing, is realized. The results obtained in this work suggested a novel microstructural design concept/feasible manufacturing route of high-strength Co-Cr-Mo alloys using conventional hot deformation processing. The present strategy focuses on the strengthening due to the introduction of a high density of lattice defects rather than grain refinement using dynamic recrystallization (DRX). The hot-rolled samples obtained by our process exhibited exceptional strength, which is comparable to the highest strength reported for biomedical Co-Cr-Mo alloys. It was also found that the acceptable ductility can be obtained even in such highly distorted Co-Cr-Mo alloys. We described the strengthening mechanisms in detail; this will be helpful for further investigations or industrial realization of the proposed strategy. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Analysis and Modeling of Process of Residual Deformations Accumulation in Soils and Granular Materials

NASA Astrophysics Data System (ADS)

Aleksandrov, A. S.; Dolgih, G. V.; Kalinin, A. L.

2017-11-01

It is established that under the influence of repeated loads the process of plastic deformation in soils and discrete materials is hereditary. To perform the mathematical modeling of plastic deformation, the authors applied the integral equation by solution of which they manage to obtain the power and logarithmic dependencies connecting plastic deformation with the number of repeated loads, the parameters of the material and components of the stress tensor in the principal axes. It is shown that these dependences generalize a number of models proposed earlier in Russia and abroad. Based on the analysis of the experimental data obtained during material testing in the dynamic devices of triaxial compression at different values of the stress deviator, the coefficients in the proposed models of deformation are determined. The authors determined the application domain for logarithmic and degree dependences.

Analysing surface deformation in Surabaya from sentinel-1A data using DInSAR method

NASA Astrophysics Data System (ADS)

Anjasmara, Ira Mutiara; Yusfania, Meiriska; Kurniawan, Akbar; Resmi, Awalina L. C.; Kurniawan, Roni

2017-07-01

The rapid population growth and increasing industrial space in the urban area of Surabaya have caused an excessive ground water use and load of infrastructures. This condition triggers surface deformation, especially the vertical deformation (subsidence or uplift), in Surabaya and its surroundings. The presence of dynamic processes of the Earth and geological form of Surabaya area can also fasten the rate of the surface deformation. In this research, Differential Interferometry Synthetic Aperture Radar (DInSAR) method is chosen to infer the surface deformation over Surabaya area. The DInSAR processing utilized Sentinel 1A satellite images from May 2015 to September 2016 using two-pass interferometric. Two-pass interferometric method is a method that uses two SAR imageries and Digital Elevation Model (DEM). The results from four pairs of DInSAR processing indicate the occurrence of surface deformation in the form of land subsidence and uplift based on the displacement Line of Sight (LOS) in Surabaya. The average rate of surface deformation from May 2015 to September 2016 varies from -3.52 mm/4months to +2.35 mm/4months. The subsidence mostly occurs along the coastal area. However, the result still contains errors from the processing of displacement, due to the value of coherence between the image, noise, geometric distortion of a radar signal and large baseline on image pair.

Modeling of the static recrystallization for 7055 aluminum alloy by cellular automaton

NASA Astrophysics Data System (ADS)

Zhang, Tao; Lu, Shi-hong; Zhang, Jia-bin; Li, Zheng-fang; Chen, Peng; Gong, Hai; Wu, Yun-xin

2017-09-01

In order to simulate the flow behavior and microstructure evolution during the pass interval period of the multi-pass deformation process, models of static recovery (SR) and static recrystallization (SRX) by the cellular automaton (CA) method for the 7055 aluminum alloy were established. Double-pass hot compression tests were conducted to acquire flow stress and microstructure variation during the pass interval period. With the basis of the material constants obtained from the compression tests, models of the SR, incubation period, nucleation rate and grain growth were fitted by least square method. A model of the grain topology and a statistical computation of the CA results were also introduced. The effects of the pass interval time, temperature, strain, strain rate and initial grain size on the microstructure variation for the SRX of the 7055 aluminum alloy were studied. The results show that a long pass interval time, large strain, high temperature and large strain rate are beneficial for finer grains during the pass interval period. The stable size of the static recrystallized grain is not concerned with the initial grain size, but mainly depends on the strain rate and temperature. The SRX plays a vital role in grain refinement, while the SR has no effect on the variation of microstructure morphology. Using flow stress and microstructure comparisons of the simulated and experimental CA results, the established CA models can accurately predict the flow stress and microstructure evolution during the pass interval period, and provide guidance for the selection of optimized parameters for the multi-pass deformation process.

Repeatability of a dynamic rollover test system.

PubMed

Seppi, Jeremy; Toczyski, Jacek; Crandall, Jeff R; Kerrigan, Jason

2016-08-17

The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces, and vehicle deformation. Four rollover crash tests were performed on 2 pairs of replicate vehicles (2 sedan tests and 2 compact multipurpose van [MPV] tests), instrumented with a custom inertial measurement unit to measure vehicle and global kinematics and string potentiometers to measure pillar deformation time histories. The road was instrumented with load cells to measure reaction loads and an optical encoder to measure road velocity. Laser scans of pre- and posttest vehicles were taken to provide detailed deformation maps. Initial conditions were found to be repeatable, with the largest difference seen in drop height of 20 mm; roll rate, roll angle, pitch angle, road velocity, drop velocity, mass, and moment of inertia were all 7% different or less. Vehicle kinematics (roll rate, road speed, roll and pitch angle, global Z' acceleration, and global Z' velocity) were similar throughout the impact; however, differences were seen in the sedan tests because of a vehicle fixation problem and differences were seen in the MPV tests due to an increase in reaction forces during leading side impact likely caused by disparities in roll angle (3° difference) and mass properties (2.2% in moment of inertia [MOI], 53.5 mm difference in center of gravity [CG] location). Despite those issues, kinetic and deformation measures showed a high degree of repeatability, which is necessary for assessing injury risk in rollover because roof strength positively correlates with injury risk (Brumbelow 2009). Improvements of the test equipment and matching mass properties will ensure highly repeatable initial conditions, vehicle kinematics, kinetics, and deformations.

Real-time volume rendering of 4D image using 3D texture mapping

NASA Astrophysics Data System (ADS)

Hwang, Jinwoo; Kim, June-Sic; Kim, Jae Seok; Kim, In Young; Kim, Sun Il

2001-05-01

Four dimensional image is 3D volume data that varies with time. It is used to express deforming or moving object in virtual surgery of 4D ultrasound. It is difficult to render 4D image by conventional ray-casting or shear-warp factorization methods because of their time-consuming rendering time or pre-processing stage whenever the volume data are changed. Even 3D texture mapping is used, repeated volume loading is also time-consuming in 4D image rendering. In this study, we propose a method to reduce data loading time using coherence between currently loaded volume and previously loaded volume in order to achieve real time rendering based on 3D texture mapping. Volume data are divided into small bricks and each brick being loaded is tested for similarity to one which was already loaded in memory. If the brick passed the test, it is defined as 3D texture by OpenGL functions. Later, the texture slices of the brick are mapped into polygons and blended by OpenGL blending functions. All bricks undergo this test. Continuously deforming fifty volumes are rendered in interactive time with SGI ONYX. Real-time volume rendering based on 3D texture mapping is currently available on PC.

DEM, tide and velocity over sulzberger ice shelf, West Antarctica

USGS Publications Warehouse

Baek, S.; Shum, C.K.; Lee, H.; Yi, Y.; Kwoun, Oh-Ig; Lu, Z.; Braun, Andreas

2005-01-01

Arctic and Antarctic ice sheets preserve more than 77% of the global fresh water and could raise global sea level by several meters if completely melted. Ocean tides near and under ice shelves shifts the grounding line position significantly and are one of current limitations to study glacier dynamics and mass balance. The Sulzberger ice shelf is an area of ice mass flux change in West Antarctica and has not yet been well studied. In this study, we use repeat-pass synthetic aperture radar (SAR) interferometry data from the ERS-1 and ERS-2 tandem missions for generation of a high-resolution (60-m) Digital Elevation Model (DEM) including tidal deformation detection and ice stream velocity of the Sulzberger Ice Shelf. Other satellite data such as laser altimeter measurements with fine foot-prints (70-m) from NASA's ICESat are used for validation and analyses. The resulting DEM has an accuracy of-0.57??5.88 m and is demonstrated to be useful for grounding line detection and ice mass balance studies. The deformation observed by InSAR is found to be primarily due to ocean tides and atmospheric pressure. The 2-D ice stream velocities computed agree qualitatively with previous methods on part of the Ice Shelf from passive microwave remote-sensing data (i.e., LANDSAT). ?? 2005 IEEE.

DARIS (Deformation Analysis Using Recursive Interferometric Systems) A New Algorithm for Displacement Measurements Though SAR Interferometry

NASA Astrophysics Data System (ADS)

Redavid, Antonio; Bovenga, Fabio

2010-03-01

In the present work we describe a new and alternative repeat-pass interferometry algorithm designed and developed with the aim to: i) increase the robustness wrt to noise by increasing the number of differential interferograms and consequently the information redundancy; ii) guarantee high performances in the detection of non linear deformation without the need of specifying in input a particular cinematic model.The starting point is a previous paper [4] dedicated to the optimization of the InSAR coregistration by finding an ad hoc path between the images which minimizes the expected total decorrelation as in the SABS-like approaches [3]. The main difference wrt the PS-like algorithms [1],[2] is the use of couples of images which potentially can show high spatial coherence and, which are neglected by the standard PSI processing.The present work presents a detailed description of the algorithm processing steps as well as the results obtained by processing simulated InSAR data with the aim to evaluate the algorithm performances. Moreover, the algorithm has been also applied on a real test case in Poland, to study the subsidence affecting the Wieliczka Salt Mine. A cross validation wrt SPINUA PSI-like algorithm [5] has been carried out by comparing the resultant displacement fields.

Numerical analysis of back pressure equal channel angular pressing of an Al-Mg alloy

NASA Astrophysics Data System (ADS)

Comăneci, R.

2017-08-01

Ultrafine grain size provides enhanced mechanical and/or physical properties such as strength and high ductility, superplasticity at relatively low temperatures and high strain rate and better corrosion resistance. Well-known as one of the most promising and effective structure refining method among other severe plastic deformation (SPD) techniques, equal channel angular pressing (ECAP) has been intensively investigated due to spectacular improvements in structure and therefore properties of bulk ultrafine grained/nanostructured materials. A successful ECAP requires surpassing two obstacles: the necessary load level which directly affects tools and a favourable stress distribution so the material withstanding the accumulated strain of repeated deformation. Materials could withstand more passes if a back pressure (BP) is applied. In traditional ECAP, tensile stress along the contact surface between the work piece and the upper wall of the outlet channel leads to crack initiation, while in the presence of BP, a negative (compressive) stress appears during the process balancing the tensile stress. In this study a comparative tridimensional finite element analysis (FEA) is performed to evaluate the flow of an Al-Mg alloy depending on different BP levels and process parameters. The results in terms of load level and strain distribution show the influence of BP on the material behaviour, opening opportunities for industrial applications.

A time series deformation estimation in the NW Himalayas using SBAS InSAR technique

NASA Astrophysics Data System (ADS)

Kumar, V.; Venkataraman, G.

2012-12-01

A time series land deformation studies in north western Himalayan region has been presented in this study. Synthetic aperture radar (SAR) interferometry (InSAR) is an important tool for measuring the land displacement caused by different geological processes [1]. Frequent spatial and temporal decorrelation in the Himalayan region is a strong impediment in precise deformation estimation using conventional interferometric SAR approach. In such cases, advanced DInSAR approaches PSInSAR as well as Small base line subset (SBAS) can be used to estimate earth surface deformation. The SBAS technique [2] is a DInSAR approach which uses a twelve or more number of repeat SAR acquisitions in different combinations of a properly chosen data (subsets) for generation of DInSAR interferograms using two pass interferometric approach. Finally it leads to the generation of mean deformation velocity maps and displacement time series. Herein, SBAS algorithm has been used for time series deformation estimation in the NW Himalayan region. ENVISAT ASAR IS2 swath data from 2003 to 2008 have been used for quantifying slow deformation. Himalayan region is a very active tectonic belt and active orogeny play a significant role in land deformation process [3]. Geomorphology in the region is unique and reacts to the climate change adversely bringing with land slides and subsidence. Settlements on the hill slopes are prone to land slides, landslips, rockslides and soil creep. These hazardous features have hampered the over all progress of the region as they obstruct the roads and flow of traffic, break communication, block flowing water in stream and create temporary reservoirs and also bring down lot of soil cover and thus add enormous silt and gravel to the streams. It has been observed that average deformation varies from -30.0 mm/year to 10 mm/year in the NW Himalayan region . References [1] Massonnet, D., Feigl, K.L.,Rossi, M. and Adragna, F. (1994) Radar interferometry mapping of deformation in the year after the Landers earthquake. Nature 1994, 369, 227-230. [2] Berardino, P., Fornaro, G., Lanari, R., Sansosti, E. (2002). A new algorithm for surface deformation Monitoring based on Small Baseline Differential SAR Interferograms. IEEE Transactions on Geoscience and Remote Sensing, 40 (11), 2375-2383. [3] GEOLOGICAL SURVEY OF INDIA (GSI), (1999) Inventory of the Himalayan glaciers. Special publication, vol. 34, pp. 165-168. [4] Chen, C.W., and Zebker, H. A., (2000). Network approaches to two-dimensional phase unwrapping: intractability and two new algorithms. Journal of the Optical Society of America, A, 17, 401-414.

Analysis of Microstructure Refinement During Single-Pass and Multi-Pass Friction Stir Processing of Nial Propeller Bronze

DTIC Science & Technology

2010-09-01

on an Optical Micrograph of the Transverse View of Single-Pass NAB. After [5]............................................... 6 Figure 4 . Vertical...deformed and 6 elongated but does not see the same refinement that is seen inside the SZ [ 4 ]. The grain structure right outside the TMAZ will also...including grinding, polishing, and electropolishing . The first step was to grind the surface using a Buehler ECOMET 4 Variable Speed Grinder

Effect of Plate Hardening Behavior on the Deformation of Stainless Steel Metal Bellows

NASA Astrophysics Data System (ADS)

Hao, Zengliang; Luo, Shuyi; Zhao, He; Zhang, Chunxiang; Luo, Junting

2017-11-01

Tensile tests of original plate samples from three types of stainless steel metal bellows were performed at room temperature. The constitutive equations for the three hardening curves were obtained and fitted. The analysis results of the microstructure and fracture morphology of the tensile specimens show that the grain size of the plate with a high logarithmic-exponential hardening rate is uneven and the dimple of the shear fracture is elongated into an ellipse. By contrast, the grain size of the plate with a relatively low linear hardening rate is even and the dimple of the fracture is uniformly equiaxial. Finite element simulations of the hydraulic bulging and repeated limit bending deformation of the metal bellows of the three types of materials were also conducted. The repeated limit bending deformation process was tested experimentally. Although the effect of the hardening exponent on the residual stress of the metal bellows after hydraulic bulging is minimal, this exponent considerably influences the repeated limit bending deformation of the metal bellows after subsequent use. The trough hardening phenomenon is serious in the repeated limit bending process. Moreover, when the hardening exponent of the original plate is high, the resistance to bending fracture at the trough area is poor.

Development of a REBCO HTS magnet for Maglev - repeated bending tests of HTS pancake coils -

NASA Astrophysics Data System (ADS)

Sugino, Motohikoa; Mizuno, Katsutoshi; Tanaka, Minoru; Ogata, Masafumi

2018-01-01

In the past study, two manufacturing methods were developed that can manufacture pancake coils by using REBCO coated conductors. It was confirmed that the conductors have no electric degradation that caused by the manufacturing method. The durability evaluation tests of the pancake coils were conducted as the final evaluation of the coil manufacturing method in this study. The repeated bending deformation was applied to manufactured pancake coils in the tests. As the results of these tests, it was confirmed that the pancake coils that were manufactured by two methods had the durability for the repeated bending deformation and the coils maintained the appropriate mechanical performance and electric performance. We adopted the fusion bonding method as the coil manufacturing method of the HTS magnet Furthermore, using the prototype pancake coil that was manufactured by the fusion bonding method as a test sample, the repeated bending test under the exited condition was conducted. Thus it was confirmed that the coil manufactured by the fusion bonding method has no degradation of the electricity performance and the mechanical properties even if the repeated bending deformation was applied under the exited condition.

Finite element simulation and comparison of a shear strain and equivalent strain during ECAP and asymmetric rolling

NASA Astrophysics Data System (ADS)

Pesin, A.; Pustovoytov, D.; Shveyova, T.; Vafin, R.

2017-12-01

The level of a shear strain and equivalent strain plays a key role in terms of the possibility of using the asymmetric rolling process as a method of severe plastic deformation. Strain mode (pure shear or simple shear) can affect very strongly on the equivalent strain and the grain refinement of the material. This paper presents the results of FEM simulations and comparison of the equivalent strain in the aluminium alloy 5083 processed by a single-pass equal channel angular pressing (simple shear), symmetric rolling (pure shear) and asymmetric rolling (simultaneous pure and simple shear). The nonlinear effect of rolls speed ratio on the deformation characteristics during asymmetric rolling was found. Extremely high equivalent strain up to e=4.2 was reached during a single-pass asymmetric rolling. The influence of the shear strain on the level of equivalent strain is discussed. Finite element analysis of the deformation characteristics, presented in this study, can be used for optimization of the asymmetric rolling process as a method of severe plastic deformation.

The Effects of Repeaters on Test Equating.

ERIC Educational Resources Information Center

Andrulis, Richard S.; And Others

1978-01-01

The effects of repeaters (testees included in both administrations of two forms of a test) on the test equating process are examined. It is shown that repeaters do effect test equating and tend to lower the cutoff point for passing the test. (JKS)

Three-dimensional surface deformation derived from airborne interferometric UAVSAR: Application to the Slumgullion Landslide

USGS Publications Warehouse

Delbridge, Brent G.; Burgmann, Roland; Fielding, Eric; Hensley, Scott; Schulz, William

2016-01-01

In order to provide surface geodetic measurements with “landslide-wide” spatial coverage, we develop and validate a method for the characterization of 3-D surface deformation using the unique capabilities of the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) airborne repeat-pass radar interferometry system. We apply our method at the well-studied Slumgullion Landslide, which is 3.9 km long and moves persistently at rates up to ∼2 cm/day. A comparison with concurrent GPS measurements validates this method and shows that it provides reliable and accurate 3-D surface deformation measurements. The UAVSAR-derived vector velocity field measurements accurately capture the sharp boundaries defining previously identified kinematic units and geomorphic domains within the landslide. We acquired data across the landslide during spring and summer and identify that the landslide moves more slowly during summer except at its head, presumably in response to spatiotemporal variations in snowmelt infiltration. In order to constrain the mechanics controlling landslide motion from surface velocity measurements, we present an inversion framework for the extraction of slide thickness and basal geometry from dense 3-D surface velocity fields. We find that the average depth of the Slumgullion Landslide is 7.5 m, several meters less than previous depth estimates. We show that by considering a viscoplastic rheology, we can derive tighter theoretical bounds on the rheological parameter relating mean horizontal flow rate to surface velocity. Using inclinometer data for slow-moving, clay-rich landslides across the globe, we find a consistent value for the rheological parameter of 0.85 ± 0.08.

TU-AB-202-06: Quantitative Evaluation of Deformable Image Registration in MRI-Guided Adaptive Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mooney, K; Zhao, T; Green, O

Purpose: To assess the performance of the deformable image registration algorithm used for MRI-guided adaptive radiation therapy using image feature analysis. Methods: MR images were collected from five patients treated on the MRIdian (ViewRay, Inc., Oakwood Village, OH), a three head Cobalt-60 therapy machine with an 0.35 T MR system. The images were acquired immediately prior to treatment with a uniform 1.5 mm resolution. Treatment sites were as follows: head/neck, lung, breast, stomach, and bladder. Deformable image registration was performed using the ViewRay software between the first fraction MRI and the final fraction MRI, and the DICE similarity coefficient (DSC)more » for the skin contours was reported. The SIFT and Harris feature detection and matching algorithms identified point features in each image separately, then found matching features in the other image. The target registration error (TRE) was defined as the vector distance between matched features on the two image sets. Each deformation was evaluated based on comparison of average TRE and DSC. Results: Image feature analysis produced between 2000–9500 points for evaluation on the patient images. The average (± standard deviation) TRE for all patients was 3.3 mm (±3.1 mm), and the passing rate of TRE<3 mm was 60% on the images. The head/neck patient had the best average TRE (1.9 mm±2.3 mm) and the best passing rate (80%). The lung patient had the worst average TRE (4.8 mm±3.3 mm) and the worst passing rate (37.2%). DSC was not significantly correlated with either TRE (p=0.63) or passing rate (p=0.55). Conclusions: Feature matching provides a quantitative assessment of deformable image registration, with a large number of data points for analysis. The TRE of matched features can be used to evaluate the registration of many objects throughout the volume, whereas DSC mainly provides a measure of gross overlap. We have a research agreement with ViewRay Inc.« less

UAVSAR Active Electronically-Scanned Array

NASA Technical Reports Server (NTRS)

Sadowy, Gregory; Brown, Kyle; Chamberlain, Neil; Figueroa, Harry; Fisher, Charlie; Grando, Maurio; Hamilton, Gary; Vorperian, Vatche; Zawadzki, Mark

2010-01-01

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) L-band (1.2-1.3 GHz) repeat pass, interferometric synthetic aperture radar (InSAR) used for Earth science applications. Using complex radar images collected during separate passes on time scales of hours to years, changes in surface topography can be measured. The repeat-pass InSAR technique requires that the radar look angle be approximately the same on successive passes. Due to variations in aircraft attitude between passes, antenna beam steering is required to replicate the radar look angle. This paper describes an active, electronically steered array (AESA) that provides beam steering capability in the antenna azimuth plane. The array contains 24 transmit/receive modules generating 2800 W of radiated power and is capable of pulse-to-pulse beam steering and polarization agility. Designed for high reliability as well as serviceability, all array electronics are contained in single 178cm x 62cm x 12 cm air-cooled panel suitable for operation up 60,000 ft altitude.

Anisotropy of mechanical and thermal properties of AZ31 sheets prepared using the ARB technique

NASA Astrophysics Data System (ADS)

Halmešová, K.; Trojanová, Z.; Džugan, J.; Drozd, Z.; Minárik, P.; Knapek, M.

2017-07-01

In the accumulative roll bonding (ARB) technique, repeated stacking of material followed by conventional roll-bonding is carried out. For this process the surfaces are cleaned with ethanol and then joined together by rolling. The rolled material is then cut into two halves, again surface treated and roll-bonded. This process may be repeated several times. For the magnesium alloy AZ31 (Mg-3Al-1Zn) rolling at an elevated temperature of 400 °C is necessary for ARB because of the low plasticity of hexagonal magnesium alloys at lower temperatures. Samples for this study were prepared using 1 to 3 ARB passes through the rolling mill. It was found that the ARB substantially refined the grain size of sheets to the micrometer scale. The microstructure and texture of the deformed samples were studied by light and electron microscopy. The mechanical properties of the ARB samples were explored using tensile test-pieces cut from the sheets with the tensile axis taken either parallel or perpendicular to the rolling direction, where a significant anisotropy in both mechanical properties and Young’s modulus was found. Anisotropy is explained on the basis of the specific microstructure and texture formed during the ARB process.

Improving hydro-formability of stainless steel tubes by tube channel pressing

NASA Astrophysics Data System (ADS)

Kitano, Y.; Yuasa, M.; Miyamoto, H.; Farshidi, M. H.; Bagherpour, E.

2017-05-01

Tube channel pressing (TCP), which is one of the severe plastic deformation (SPD) technologies to refine grain size into submicron size for tubular materials, have been applied to ferritic stainless steel tubes for one pass, in order to alleviate ridging and enhance the hydro-formability. It was found that grain-scale shear bands were introduced by one-pass TCP, and texture and microstructure was successfully modified by promoting recrystallization of deformation microstructure, which is otherwise hard-to-recrystallize, in the post-TCP annealing. Elongation to failure, strain-hardening exponent (n-value) and Lankford values of both longitudinal and circumferential directions increased in comparison to with the tube fabricated by conventional process.

Forest canopy height estimation using double-frequency repeat pass interferometry

NASA Astrophysics Data System (ADS)

Karamvasis, Kleanthis; Karathanassi, Vassilia

2015-06-01

In recent years, many efforts have been made in order to assess forest stand parameters from remote sensing data, as a mean to estimate the above-ground carbon stock of forests in the context of the Kyoto protocol. Synthetic aperture radar interferometry (InSAR) techniques have gained traction in last decade as a viable technology for vegetation parameter estimation. Many works have shown that forest canopy height, which is a critical parameter for quantifying the terrestrial carbon cycle, can be estimated with InSAR. However, research is still needed to understand further the interaction of SAR signals with forest canopy and to develop an operational method for forestry applications. This work discusses the use of repeat pass interferometry with ALOS PALSAR (L band) HH polarized and COSMO Skymed (X band) HH polarized acquisitions over the Taxiarchis forest (Chalkidiki, Greece), in order to produce accurate digital elevation models (DEMs) and estimate canopy height with interferometric processing. The effect of wavelength-dependent penetration depth into the canopy is known to be strong, and could potentially lead to forest canopy height mapping using dual-wavelength SAR interferometry at X- and L-band. The method is based on scattering phase center separation at different wavelengths. It involves the generation of a terrain elevation model underneath the forest canopy from repeat-pass L-band InSAR data as well as the generation of a canopy surface elevation model from repeat pass X-band InSAR data. The terrain model is then used to remove the terrain component from the repeat pass interferometric X-band elevation model, so as to enable the forest canopy height estimation. The canopy height results were compared to a field survey with 6.9 m root mean square error (RMSE). The effects of vegetation characteristics, SAR incidence angle and view geometry, and terrain slope on the accuracy of the results have also been studied in this work.

Repeatability study of replicate crash tests: A signal analysis approach.

PubMed

Seppi, Jeremy; Toczyski, Jacek; Crandall, Jeff R; Kerrigan, Jason

2017-10-03

To provide an objective basis on which to evaluate the repeatability of vehicle crash test methods, a recently developed signal analysis method was used to evaluate correlation of sensor time history data between replicate vehicle crash tests. The goal of this study was to evaluate the repeatability of rollover crash tests performed with the Dynamic Rollover Test System (DRoTS) relative to other vehicle crash test methods. Test data from DRoTS tests, deceleration rollover sled (DRS) tests, frontal crash tests, frontal offset crash tests, small overlap crash tests, small overlap impact (SOI) crash tests, and oblique crash tests were obtained from the literature and publicly available databases (the NHTSA vehicle database and the Insurance Institute for Highway Safety TechData) to examine crash test repeatability. Signal analysis of the DRoTS tests showed that force and deformation time histories had good to excellent repeatability, whereas vehicle kinematics showed only fair repeatability due to the vehicle mounting method for one pair of tests and slightly dissimilar mass properties (2.2%) in a second pair of tests. Relative to the DRS, the DRoTS tests showed very similar or higher levels of repeatability in nearly all vehicle kinematic data signals with the exception of global X' (road direction of travel) velocity and displacement due to the functionality of the DRoTS fixture. Based on the average overall scoring metric of the dominant acceleration, DRoTS was found to be as repeatable as all other crash tests analyzed. Vertical force measures showed good repeatability and were on par with frontal crash barrier forces. Dynamic deformation measures showed good to excellent repeatability as opposed to poor repeatability seen in SOI and oblique deformation measures. Using the signal analysis method as outlined in this article, the DRoTS was shown to have the same or better repeatability of crash test methods used in government regulatory and consumer evaluation test protocols.

Study of Retreat and Movement of Himalayan Glaciers Using Spaceborne Repeat Pass SAR Data

NASA Astrophysics Data System (ADS)

Kumar, V.; Venkataraman, G.; Rao, Y. S.

2008-12-01

In this study retreat and movement of Himalayan glaciers using Spaceborne SAR data have been attempted. Gangotri, Siachen, Bara Shigri and Patsio are major glaciers in the Himalayan region which are showing retreat and their respective tributary glaciers are completely disconnected from main body of glaciers. Glacier retreat study will be done using time series coregistered multi temporal SAR data. Simultaneously InSAR coherence thresholding will be applied for tracking snout of Gangotri glacier. Information about dynamism of glaciated terrain can be retrieved by differential interferograms. In this study, movement of Himalayan glaciers will be deciphered using Spaceborne InSAR technique. ERS-1/2 tandem observations showed high correlation on glacier area and hence movement of Siachen and Gangotri glacier are measured for year 1996. Displacement of Gangotri glacier in the radar look direction has been observed as 8.4 cm per day whereas Siachen glacier exhibits a displacement of 22 cm per day (Venkataraman et al. 2005). ERS-1/2 tandem data over all these glaciers show highest correlation over glacier areas but ENVISAT ASAR data shows coherence loss over glacier area due to decorrelation (Vijay et al. 2008). Coherence loss is usual phenomena in glaciated terrain as repeativity of sensor is high (35 days for ENVISAT). A tandem pair of ERS- 1&2 acquired on April 1 and 2, 1996 in descending pass over Siachen shows high coherence than the ascending pair acquired on May 2 and 3, 1996. It is due to change in climate between two acquisitions at glacier locations. Due to the X-band frequency TerraSAR-X interferometry will be more sensitive to orbit errors than current SAR sensors that operate in C-band or L-band (Eineder et al. 2003). A single frequency GPS receiver plus an additional dual-frequency GPS flown as an experimental payload will deliver an orbit accuracy in the order of centimeters. TerraSAR-X will supplement and enhance the InSAR based observations using other satellite data sets because of its high phase to deformation sensitivity, high spatial resolution (1 meter in High Resolution Spot Light Mode) and short (11 day) repeativity.

Numerical simulation of bubble deformation in magnetic fluids by finite volume method

NASA Astrophysics Data System (ADS)

Yamasaki, Haruhiko; Yamaguchi, Hiroshi

2017-06-01

Bubble deformation in magnetic fluids under magnetic field is investigated numerically by an interface capturing method. The numerical method consists of a coupled level-set and VOF (Volume of Fluid) method, combined with conservation CIP (Constrained Interpolation Profile) method with the self-correcting procedure. In the present study considering actual physical properties of magnetic fluid, bubble deformation under given uniform magnetic field is analyzed for internal magnetic field passing through a magnetic gaseous and liquid phase interface. The numerical results explain the mechanism of bubble deformation under presence of given magnetic field.

Characterization of ultra-fine grained aluminum produced by accumulative back extrusion (ABE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alihosseini, H., E-mail: hamid.alihossieni@gmail.com; Materials Science and Engineering Department, Engineering School, Amirkabir University, Tehran; Faraji, G.

2012-06-15

In the present work, the microstructural evolutions and microhardness of AA1050 subjected to one, two and three passes of accumulative back extrusion (ABE) were investigated. The microstructural evolutions were characterized using transmission electron microscopy. The results revealed that applying three passes of accumulative back extrusion led to significant grain refinement. The initial grain size of 47 {mu}m was refined to the grains of 500 nm after three passes of ABE. Increasing the number of passes resulted in more decrease in grain size, better microstructure homogeneity and increase in the microhardness. The cross-section of ABEed specimen consisted of two different zones:more » (i) shear deformation zone, and (ii) normal deformation zone. The microhardness measurements indicated that the hardness increased from the initial value of 31 Hv to 67 Hv, verifying the significant microstructural refinement via accumulative back extrusion. - Highlights: Black-Right-Pointing-Pointer A significant grain refinement can be achieved in AA1050, Al alloy by applying ABE. Black-Right-Pointing-Pointer Microstructural homogeneity of ABEed samples increased by increasing the number of ABE cycles. Black-Right-Pointing-Pointer A substantial increase in the hardness, from 31 Hv to 67 Hv, was recorded.« less

Perinuclear Arp2/3-driven actin polymerization enables nuclear deformation to facilitate cell migration through complex environments

PubMed Central

Thiam, Hawa-Racine; Vargas, Pablo; Carpi, Nicolas; Crespo, Carolina Lage; Raab, Matthew; Terriac, Emmanuel; King, Megan C.; Jacobelli, Jordan; Alberts, Arthur S.; Stradal, Theresia; Lennon-Dumenil, Ana-Maria; Piel, Matthieu

2016-01-01

Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions. This mechanism is based on a rapid Arp2/3-dependent actin nucleation around the nucleus that disrupts the nuclear lamina, the main structure limiting nuclear deformability. The cells' requirement for Arp2/3 to pass through constrictions can be relieved when nuclear stiffness is decreased by suppressing lamin A/C expression. We propose a new role for Arp2/3 in three-dimensional cell migration, allowing fast-moving cells such as leukocytes to rapidly and efficiently migrate through narrow gaps, a process probably important for their function. PMID:26975831

Fiber optic system design for vehicle detection and analysis

NASA Astrophysics Data System (ADS)

Nedoma, Jan; Zboril, Ondrej; Fajkus, Marcel; Zavodny, Petr; Kepak, Stanislav; Bednarek, Lukas; Martinek, Radek; Vasinek, Vladimir

2016-04-01

Fiber optic interferometers belong to a group of highly sensitive and precise devices enabling to measure small changes in the deformation shapes, changes in pressure, temperature, vibration and so on. The basis of their activity is to evaluate the number of fringes over time, not changes in the intensity of the optical signal. The methodology described in the article is based on using the interferometer to monitor traffic density. The base of the solution is a Mach-Zehnder interferometer operating with single-mode G.652 optical fiber at the wavelength of 1550 nm excited by a DFB laser. The power distribution of the laser light into the individual arms of the interferometer is in the ratio 1:1. Realized measuring scheme was terminated by an optical receiver including InGaAs PIN photodiode. Registered signal from the photodetector was through 8 Hz high pass filter fed to the measuring card that captures the analog input voltage using an application written in LabView development environment. The interferometer was stored in a waterproof box and placed at the side of the road. Here panned individual transit of cars in his environs. Vertically across the road was placed in contact removable belt simulating a retarder, which was used when passing cars to create sufficient vibration response detecting interferometer. The results demonstrated that the individual vehicles passing around boxing showed characteristic amplitude spectra, which was unique for each object, and had sufficient value signal to noise ratio (SNR). The signal was processed by applications developed for the amplitude-frequency spectrum. Evaluated was the maximum amplitude of the signal and compared to the noise. The results were verified by repeated transit of the different types of cars.

Using UAVSAR to Estimate Creep Along the Superstition Hills Fault, Southern California

NASA Astrophysics Data System (ADS)

Donnellan, A.; Parker, J. W.; Pierce, M.; Wang, J.

2012-12-01

UAVSAR data were first acquired over the Salton Trough region, just north of the Mexican border in October 2009. Second passes of data were acquired on 12 and 13 April 2010, about one week following the 5 April 2010 M 7.2 El Mayor - Cucapah earthquake. The earthquake resulted in creep on several faults north of the main rupture, including the Yuha, Imperial, and Superstition Hills faults. The UAVSAR platform acquires data about every six meters in swaths about 15 km wide. Tropospheric effects and residual aircraft motion contribute to error in the estimation of surface deformation in the Repeat Pass Interferometry products. The Superstition Hills fault shows clearly in the associated radar interferogram; however, error in the data product makes it difficult to infer deformation from long profiles that cross the fault. Using the QuakeSim InSAR Profile tool we extracted line of site profiles on either side of the fault delineated in the interferogram. We were able to remove much of the correlated error by differencing profiles 250 m on either side of the fault. The result shows right-lateral creep of 1.5±.4 mm along the northern 7 km of the fault in the interferogram. The amount of creep abruptly changes to 8.4±.4 mm of right lateral creep along at least 9 km of the fault covered in the image to the south. The transition occurs within less than 100 m along the fault. We also extracted 2 km long line of site profiles perpendicular to this section of the fault. Averaging these profiles shows a step across the fault of 14.9±.3 mm with greater creep on the order of 20 mm on the northern two profiles and lower creep of about 10 mm on the southern two profiles. Nearby GPS stations P503 and P493 are consistent with this result. They also confirm that the creep event occurred at the time of the El Mayor - Cucapah earthquake. By removing regional deformation resulting from the main rupture we were able to invert for the depth of creep from the surface. Results indicate that the slip occurred from the surface to 10-20 km, not shallowly, as previously suggested.

Repeating Earthquake and Nonvolcanic Tremor Observations of Aseismic Deep Fault Transients in Central California.

NASA Astrophysics Data System (ADS)

Nadeau, R. M.; Traer, M.; Guilhem, A.

2005-12-01

Seismic indicators of fault zone deformation can complement geodetic measurements by providing information on aseismic transient deformation: 1) from deep within the fault zone, 2) on a regional scale, 3) with intermediate temporal resolution (weeks to months) and 4) that spans over 2 decades (1984 to early 2005), including pre- GPS and INSAR coverage. Along the San Andreas Fault (SAF) in central California, two types of seismic indicators are proving to be particularly useful for providing information on deep fault zone deformation. The first, characteristically repeating microearthquakes, provide long-term coverage (decades) on the evolution of aseismic fault slip rates at seismogenic depths along a large (~175 km) stretch of the SAF between the rupture zones of the ~M8 1906 San Francisco and 1857 Fort Tejon earthquakes. In Cascadia and Japan the second type of seismic indicator, nonvolcanic tremors, have shown a remarkable correlation between their activity rates and GPS and tiltmeter measurements of transient deformation in the deep (sub-seismogenic) fault zone. This correlation suggests that tremor rate changes and deep transient deformation are intimately related and that deformation associated with the tremor activity may be stressing the seismogenic zone in both areas. Along the SAF, nonvolcanic tremors have only recently been discovered (i.e., in the Parkfield-Cholame area), and knowledge of their full spatial extent is still relatively limited. Nonetheless the observed temporal correlation between earthquake and tremor activity in this area is consistent with a model in which sub-seismogenic deformation and seismogenic zone stress changes are closely related. We present observations of deep aseismic transient deformation associated with the 28 September 2004, M6 Parkfield earthquake from both repeating earthquake and nonvolcanic tremor data. Also presented are updated deep fault slip rate estimates from prepeating quakes in the San Juan Bautista area with an assessment of their significance to previously reported quasi-periodic slip rate pulses and small to moderate magnitude (> M3.5) earthquake occurrence in the area.

Atmospheric Phase Delay in Sentinel SAR Interferometry

NASA Astrophysics Data System (ADS)

Krishnakumar, V.; Monserrat, O.; Crosetto, M.; Crippa, B.

2018-04-01

The repeat-pass Synthetic Aperture Radio Detection and Ranging (RADAR) Interferometry (InSAR) has been a widely used geodetic technique for observing the Earth's surface, especially for mapping the Earth's topography and deformations. However, InSAR measurements are prone to atmospheric errors. RADAR waves traverse the Earth's atmosphere twice and experience a delay due to atmospheric refraction. The two major layers of the atmosphere (troposphere and ionosphere) are mainly responsible for this delay in the propagating RADAR wave. Previous studies have shown that water vapour and clouds present in the troposphere and the Total Electron Content (TEC) of the ionosphere are responsible for the additional path delay in the RADAR wave. The tropospheric refractivity is mainly dependent on pressure, temperature and partial pressure of water vapour. The tropospheric refractivity leads to an increase in the observed range. These induced propagation delays affect the quality of phase measurement and introduce errors in the topography and deformation fields. The effect of this delay was studied on a differential interferogram (DInSAR). To calculate the amount of tropospheric delay occurred, the meteorological data collected from the Spanish Agencia Estatal de Meteorología (AEMET) and MODIS were used. The interferograms generated from Sentinel-1 carrying C-band Synthetic Aperture RADAR Single Look Complex (SLC) images acquired on the study area are used. The study area consists of different types of scatterers exhibiting different coherence. The existing Saastamoinen model was used to perform a quantitative evaluation of the phase changes caused by pressure, temperature and humidity of the troposphere during the study. Unless the phase values due to atmospheric disturbances are not corrected, it is difficult to obtain accurate measurements. Thus, the atmospheric error correction is essential for all practical applications of DInSAR to avoid inaccurate height and deformation measurements.

Evidence for post-1620 Ma Proterozoic regional deformation, Lucy Gray Range, southern Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duebendorfer, E.M.; Christensen, C.H.; Shafiqullah, M.

1993-04-01

Major mylonite zones in the northern Lucy Gray Range, Nevada, deform and are spatially associated with the 1,425 Ma Beer Bottle Pass pluton, Mylonitic granite yielded a K-Ar biotite date of 1,400 [+-] 30 Ma and is overlain nonconformably by the Cambrian Tapeats Sandstone, thus constraining deformation to the Proterozoic. The mylonites may therefore represent an unrecognized period of Proterozoic deformation in the Southwest. Field and microstructural studies were undertaken to evaluate between 3 possible models for the apparent spatial association of granite and mylonites: (1) deformation directly related to pluton emplacement (ballooning); (2) synkinematic pluton emplacement; or (3) post-emplacementmore » deformation. Mylonite zones up to 50 meters thick strike north to northeast, dip moderately to steeply northwest, and contain a remarkably consistent west-plunging mineral lineation. Mylonites are present locally at the granite-wall rock contact; however, less than 30% of the exposed contact is mylonitic. The authors reject a pluton-emplacement origin for the mylonites because (1) mylonite zones within wall rocks locally strike at high angles to an undeformed pluton-wall rock contact, (2) the consistent (pluton-side-down) shear sense is more compatible with a uniform-sense simple shear zone than a ballooning pluton, (3) plane strain fabrics dominate over flattening fabrics, and (4) mylonites adjacent to pluton contacts lack annealing textures predicted by the ballooning model. If so, the conventional interpretation of 1,400 Ga granitoids as anorogenic may need to be re-evaluated. The authors cannot, however, rule out the possibility that the mylonites completely postdate intrusion of the Beer Bottle Pass pluton. Future work is planned to delimit the regional extent of this previously unrecognized Proterozoic deformational event.« less

Validation of a deformable image registration technique for cone beam CT-based dose verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moteabbed, M., E-mail: mmoteabbed@partners.org; Sharp, G. C.; Wang, Y.

2015-01-15

Purpose: As radiation therapy evolves toward more adaptive techniques, image guidance plays an increasingly important role, not only in patient setup but also in monitoring the delivered dose and adapting the treatment to patient changes. This study aimed to validate a method for evaluation of delivered intensity modulated radiotherapy (IMRT) dose based on multimodal deformable image registration (DIR) for prostate treatments. Methods: A pelvic phantom was scanned with CT and cone-beam computed tomography (CBCT). Both images were digitally deformed using two realistic patient-based deformation fields. The original CT was then registered to the deformed CBCT resulting in a secondary deformedmore » CT. The registration quality was assessed as the ability of the DIR method to recover the artificially induced deformations. The primary and secondary deformed CT images as well as vector fields were compared to evaluate the efficacy of the registration method and it’s suitability to be used for dose calculation. PLASTIMATCH, a free and open source software was used for deformable image registration. A B-spline algorithm with optimized parameters was used to achieve the best registration quality. Geometric image evaluation was performed through voxel-based Hounsfield unit (HU) and vector field comparison. For dosimetric evaluation, IMRT treatment plans were created and optimized on the original CT image and recomputed on the two warped images to be compared. The dose volume histograms were compared for the warped structures that were identical in both warped images. This procedure was repeated for the phantom with full, half full, and empty bladder. Results: The results indicated mean HU differences of up to 120 between registered and ground-truth deformed CT images. However, when the CBCT intensities were calibrated using a region of interest (ROI)-based calibration curve, these differences were reduced by up to 60%. Similarly, the mean differences in average vector field lengths decreased from 10.1 to 2.5 mm when CBCT was calibrated prior to registration. The results showed no dependence on the level of bladder filling. In comparison with the dose calculated on the primary deformed CT, differences in mean dose averaged over all organs were 0.2% and 3.9% for dose calculated on the secondary deformed CT with and without CBCT calibration, respectively, and 0.5% for dose calculated directly on the calibrated CBCT, for the full-bladder scenario. Gamma analysis for the distance to agreement of 2 mm and 2% of prescribed dose indicated a pass rate of 100% for both cases involving calibrated CBCT and on average 86% without CBCT calibration. Conclusions: Using deformable registration on the planning CT images to evaluate the IMRT dose based on daily CBCTs was found feasible. The proposed method will provide an accurate dose distribution using planning CT and pretreatment CBCT data, avoiding the additional uncertainties introduced by CBCT inhomogeneity and artifacts. This is a necessary initial step toward future image-guided adaptive radiotherapy of the prostate.« less

Satellite Geodetic Constraints On Earthquake Processes: Implications of the 1999 Turkish Earthquakes for Fault Mechanics and Seismic Hazards on the San Andreas Fault

NASA Technical Reports Server (NTRS)

Reilinger, Robert

2005-01-01

Our principal activities during the initial phase of this project include: 1) Continued monitoring of postseismic deformation for the 1999 Izmit and Duzce, Turkey earthquakes from repeated GPS survey measurements and expansion of the Marmara Continuous GPS Network (MAGNET), 2) Establishing three North Anatolian fault crossing profiles (10 sitedprofile) at locations that experienced major surface-fault earthquakes at different times in the past to examine strain accumulation as a function of time in the earthquake cycle (2004), 3) Repeat observations of selected sites in the fault-crossing profiles (2005), 4) Repeat surveys of the Marmara GPS network to continue to monitor postseismic deformation, 5) Refining block models for the Marmara Sea seismic gap area to better understand earthquake hazards in the Greater Istanbul area, 6) Continuing development of models for afterslip and distributed viscoelastic deformation for the earthquake cycle. We are keeping close contact with MIT colleagues (Brad Hager, and Eric Hetland) who are developing models for S. California and for the earthquake cycle in general (Hetland, 2006). In addition, our Turkish partners at the Marmara Research Center have undertaken repeat, micro-gravity measurements at the MAGNET sites and have provided us estimates of gravity change during the period 2003 - 2005.

Deconvolution of continuous paleomagnetic data from pass-through magnetometer: A new algorithm to restore geomagnetic and environmental information based on realistic optimization

NASA Astrophysics Data System (ADS)

Oda, Hirokuni; Xuan, Chuang

2014-10-01

development of pass-through superconducting rock magnetometers (SRM) has greatly promoted collection of paleomagnetic data from continuous long-core samples. The output of pass-through measurement is smoothed and distorted due to convolution of magnetization with the magnetometer sensor response. Although several studies could restore high-resolution paleomagnetic signal through deconvolution of pass-through measurement, difficulties in accurately measuring the magnetometer sensor response have hindered the application of deconvolution. We acquired reliable sensor response of an SRM at the Oregon State University based on repeated measurements of a precisely fabricated magnetic point source. In addition, we present an improved deconvolution algorithm based on Akaike's Bayesian Information Criterion (ABIC) minimization, incorporating new parameters to account for errors in sample measurement position and length. The new algorithm was tested using synthetic data constructed by convolving "true" paleomagnetic signal containing an "excursion" with the sensor response. Realistic noise was added to the synthetic measurement using Monte Carlo method based on measurement noise distribution acquired from 200 repeated measurements of a u-channel sample. Deconvolution of 1000 synthetic measurements with realistic noise closely resembles the "true" magnetization, and successfully restored fine-scale magnetization variations including the "excursion." Our analyses show that inaccuracy in sample measurement position and length significantly affects deconvolution estimation, and can be resolved using the new deconvolution algorithm. Optimized deconvolution of 20 repeated measurements of a u-channel sample yielded highly consistent deconvolution results and estimates of error in sample measurement position and length, demonstrating the reliability of the new deconvolution algorithm for real pass-through measurements.

Could ionizing radiation forestall cauliflower ear?

PubMed

Hwang, K; Kim, C W; Lee, S I; Park, I S; Kim, W C; Loh, J J

2001-02-01

Repeated trauma to the ear very often results in "cauliflower ear." Many methods have been suggested to prevent an injured ear from demonstrating a cauliflowerlike deformity. The principles of treatment are evacuation of the hematoma, control of the reaccumulation of fluid, and maintenance of the cartilage contour. The authors studied the effect of ionizing radiation on deformed rabbit ears induced by repeated trauma. Twenty ears (10 rabbits) were used in the experiment. The animals were divided into four groups (control, preradiation, low dose, and high dose). Hematoma was produced by pounding the lateral side of the auricle 10 times with a 50-g weight at a height of 15 cm. The thickness of the injured and uninjured sites was measured, and histological analysis was performed for each group. The thickness of the ears of the irradiated groups was significantly less than the control group. The authors think that radiation treatment of repeatedly injured ears could prevent ear deformity, and could possibly be an adjunctive form of management of cauliflower ear in addition to hematoma evacuation and compression therapy.

Comparison of distortions of complex aluminium sections formed in single-step and incremental roll bending

NASA Astrophysics Data System (ADS)

Farstad, Jan Magnus Granheim; Netland, Øyvind; Welo, Torgeir

2017-10-01

This paper presents the results from a second series of experiments made to study local plastic deformations of a complex, hollow aluminium extrusion formed in roll bending. The first experimental series utilizing a single step roll bending sequence has been presented at the ESAFORM 2016 conference by Farstad et. al. In this recent experimental series, the same aluminium extrusion was formed in incremental steps. The objective was to investigate local distortions of the deformed cross section as a result of different number of steps employed to arrive at the final global shape of the extrusion. Moreover, the results between the two experimental series are compared, focusing on identifying differences in both the desired and the undesired deformations taking place as a result of bending and contact stresses. The profiles formed through multiple passes had less undesirable local distortions of the cross-section than the profiles that were formed in a single pass. However, the springback effect was more pronounced, meaning that the released radii of the profiles were higher.

Genome Therapy of Myotonic Dystrophy Type 1 iPS Cells for Development of Autologous Stem Cell Therapy.

PubMed

Gao, Yuanzheng; Guo, Xiuming; Santostefano, Katherine; Wang, Yanlin; Reid, Tammy; Zeng, Desmond; Terada, Naohiro; Ashizawa, Tetsuo; Xia, Guangbin

2016-08-01

Myotonic dystrophy type 1 (DM1) is caused by expanded Cytosine-Thymine-Guanine (CTG) repeats in the 3'-untranslated region (3' UTR) of the Dystrophia myotonica protein kinase (DMPK) gene, for which there is no effective therapy. The objective of this study is to develop genome therapy in human DM1 induced pluripotent stem (iPS) cells to eliminate mutant transcripts and reverse the phenotypes for developing autologous stem cell therapy. The general approach involves targeted insertion of polyA signals (PASs) upstream of DMPK CTG repeats, which will lead to premature termination of transcription and elimination of toxic mutant transcripts. Insertion of PASs was mediated by homologous recombination triggered by site-specific transcription activator-like effector nuclease (TALEN)-induced double-strand break. We found genome-treated DM1 iPS cells continue to maintain pluripotency. The insertion of PASs led to elimination of mutant transcripts and complete disappearance of nuclear RNA foci and reversal of aberrant splicing in linear-differentiated neural stem cells, cardiomyocytes, and teratoma tissues. In conclusion, genome therapy by insertion of PASs upstream of the expanded DMPK CTG repeats prevented the production of toxic mutant transcripts and reversal of phenotypes in DM1 iPS cells and their progeny. These genetically-treated iPS cells will have broad clinical application in developing autologous stem cell therapy for DM1.

The Role of Negative and Positive Feedback in the Second Language Acquisition of the "Passe Compose" and the "Imparfait."

ERIC Educational Resources Information Center

Ayoun, Dalila

2001-01-01

Tests the effectiveness of written recasts versus models in the acquisition of the aspectual distinction between two past tenses in French, the "passe compose" and the "imparfait" with a pretest, repeated exposure, and posttest design. (Author/VWL)

Adaptive multiphoton endomicroscopy through a dynamically deformed multicore optical fiber using proximal detection.

PubMed

Warren, Sean C; Kim, Youngchan; Stone, James M; Mitchell, Claire; Knight, Jonathan C; Neil, Mark A A; Paterson, Carl; French, Paul M W; Dunsby, Chris

2016-09-19

This paper demonstrates multiphoton excited fluorescence imaging through a polarisation maintaining multicore fiber (PM-MCF) while the fiber is dynamically deformed using all-proximal detection. Single-shot proximal measurement of the relative optical path lengths of all the cores of the PM-MCF in double pass is achieved using a Mach-Zehnder interferometer read out by a scientific CMOS camera operating at 416 Hz. A non-linear least squares fitting procedure is then employed to determine the deformation-induced lateral shift of the excitation spot at the distal tip of the PM-MCF. An experimental validation of this approach is presented that compares the proximally measured deformation-induced lateral shift in focal spot position to an independent distally measured ground truth. The proximal measurement of deformation-induced shift in focal spot position is applied to correct for deformation-induced shifts in focal spot position during raster-scanning multiphoton excited fluorescence imaging.

First GPS baseline results from the North Andes

NASA Technical Reports Server (NTRS)

Kellogg, James N.; Freymueller, Jeffrey T.; Dixon, Timothy H.; Neilan, Ruth E.; Ropain, Clemente

1990-01-01

The CASA Uno GPS experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 10 to the 8th for short baselines (100-1000 km), and better than 3 parts in 10 to the 8th for long baselines (greater than 1000 km). Vertical repeatabilities are typically 4-6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8cm/yr, which should be detectable by the repeat experiment planned for 1991. Expected deformation rates within the North Andes are of the order of 1 cm/yr, which may be detectable with the 1991 experiment.

A Novel Method for Quantifying Human In Situ Whole Brain Deformation under Rotational Loading Using Sonomicrometry.

PubMed

Alshareef, Ahmed; Giudice, J Sebastian; Forman, Jason; Salzar, Robert S; Panzer, Matthew B

2018-03-01

Traumatic brain injuries (TBI) are one of the least understood injuries to the body. Finite element (FE) models of the brain have been crucial for understanding concussion and for developing injury mitigation systems; however, the experimental brain deformation data currently used to validate these models are limited. The objective of this study was to develop a methodology for the investigation of in situ three-dimensional brain deformation during pure rotational loading of the head, using sonomicrometry. Sonomicrometry uses ultrasonic pulses to measure the dynamic distances between piezoelectric crystals implanted in any sound-transmitting media. A human cadaveric head-neck specimen was acquired 14 h postmortem and was instrumented with an array of 32 small sonomicrometry crystals embedded in the head: 24 crystals were implanted in the brain, and 8 were fixed to the inner skull. A dynamic rotation was then applied to the head using a closed-loop controlled test device. Four pulses with different severity levels were applied around three orthogonal anatomical axes of rotation. A repeated test of the highest severity rotation was conducted in each axis to assess repeatability. All tests were completed within 56 h postmortem. Overall, the combined experimental and sonomicrometry methods were demonstrated to reliably and repeatedly capture three-dimensional dynamic deformation of an intact human brain. These methods provide a framework for using sonomicrometry to acquire multidimensional experimental data required for FE model development and validation, and will lend insight into the deformations sustained by the brain during impact.

3D surface flow kinematics derived from airborne UAVSAR interferometric synthetic aperture radar to constrain the physical mechanisms controlling landslide motion

NASA Astrophysics Data System (ADS)

Delbridge, B. G.; Burgmann, R.; Fielding, E. J.; Hensley, S.; Schulz, W. H.

2013-12-01

This project focuses on improving our understanding of the physical mechanisms controlling landslide motion by studying the landslide-wide kinematics of the Slumgullion landslide in southwestern Colorado using interferometric synthetic aperture radar (InSAR) and GPS. The NASA/JPL UAVSAR airborne repeat-pass SAR interferometry system imaged the Slumgullion landslide from 4 look directions on eight flights in 2011 and 2012. Combining the four look directions allows us to extract the full 3-D velocity field of the surface. Observing the full 3-dimensional flow field allows us to extract the full strain tensor (assuming free surface boundary conditions and incompressible flow) since we have both the spatial resolution to take spatial derivates and full deformation information. COSMO-SkyMed(CSK) high-resolution Spotlight data was also acquired during time intervals overlapping with the UAVSAR one-week pairs, with intervals as short as one day. These observations allow for the quantitative testing of the deformation magnitude and estimated formal errors in the UAVSAR derived deformation field. We also test the agreement of the deformation at 20 GPS monitoring sites concurrently acquired by the USGS. We also utilize the temporal resolution of real-time GPS acquired by the UC Berkeley Active Tectonics Group during a temporary deployment from July 22nd - August 2nd. By combining this data with the kinematic data we hope to elucidate the response of the landslide to environmental changes such as rainfall, snowmelt, and atmospheric pressure, and consequently the mechanisms controlling the dynamics of the landslide system. To constrain the longer temporal dynamics, interferograms made from pairs of CSK images acquired in 2010, 2011, 2012 and 2013 reveal the slide deformation on a longer timescale by allowing us to measure meters of motion and see the average rates over year long intervals using pixel offset tracking of the high-resolution SAR amplitude images. The results of this study will also allow us to test the agreement and commensurability of UAVSAR- derived deformation with real-time GPS observations and traditional satellite-based SAR interferometry from the COSMOSkyMed system. We will not only help mitigate the hazards associated with large landslides, but also provide information on the limitations of current geodetic imaging techniques. This unique opportunity to compare several concurrent geodetic observations of the same deformation will provide constraints and recommendations for the design and implementation of future geodetic systems for the monitoring of Earth surface processes.

A mechano-acoustic indentor system for in vivo measurement of nonlinear elastic properties of soft tissue.

PubMed

Koo, Terry K; Cohen, Jeffrey H; Zheng, Yongping

2011-11-01

Soft tissue exhibits nonlinear stress-strain behavior under compression. Characterizing its nonlinear elasticity may aid detection, diagnosis, and treatment of soft tissue abnormality. The purposes of this study were to develop a rate-controlled Mechano-Acoustic Indentor System and a corresponding finite element optimization method to extract nonlinear elastic parameters of soft tissue and evaluate its test-retest reliability. An indentor system using a linear actuator to drive a force-sensitive probe with a tip-mounted ultrasound transducer was developed. Twenty independent sites at the upper lateral quadrant of the buttock from 11 asymptomatic subjects (7 men and 4 women from a chiropractic college) were indented at 6% per second for 3 sessions, each consisting of 5 trials. Tissue thickness, force at 25% deformation, and area under the load-deformation curve from 0% to 25% deformation were calculated. Optimized hyperelastic parameters of the soft tissue were calculated with a finite element model using a first-order Ogden material model. Load-deformation response on a standardized block was then simulated, and the corresponding area and force parameters were calculated. Between-trials repeatability and test-retest reliability of each parameter were evaluated using coefficients of variation and intraclass correlation coefficients, respectively. Load-deformation responses were highly reproducible under repeated measurements. Coefficients of variation of tissue thickness, area under the load-deformation curve from 0% to 25% deformation, and force at 25% deformation averaged 0.51%, 2.31%, and 2.23%, respectively. Intraclass correlation coefficients ranged between 0.959 and 0.999, indicating excellent test-retest reliability. The automated Mechano-Acoustic Indentor System and its corresponding optimization technique offers a viable technology to make in vivo measurement of the nonlinear elastic properties of soft tissue. This technology showed excellent between-trials repeatability and test-retest reliability with potential to quantify the effects of a wide variety of manual therapy techniques on the soft tissue elastic properties. Copyright © 2011 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

Redefinition of the helical rim in cauliflower-ear surgery.

PubMed

Schonauer, F; La Rusca, I; Pereira, J A; Molea, G

2002-01-01

Cauliflower ear is a serious deformity of the auricle induced by single or repeated injury to the external ear. Few papers deal with surgical techniques for correcting this deformity. We describe the use of ipsilateral excess cartilage to restore the helical rim. Copyright 2002 The British Association of Plastic Surgeons.

Refinement of Ferrite Grain Size near the Ultrafine Range by Multipass, Thermomechanical Compression

NASA Astrophysics Data System (ADS)

Patra, S.; Neogy, S.; Kumar, Vinod; Chakrabarti, D.; Haldar, A.

2012-11-01

Plane-strain compression testing was carried out on a Nb-Ti-V microalloyed steel, in a GLEEBLE3500 simulator using a different amount of roughing, intermediate, and finishing deformation over the temperature range of 1373 K to 1073 K (1100 °C to 800 °C). A decrease in soaking temperature from 1473 K to 1273 K (1200 °C to 1000 °C) offered marginal refinement in the ferrite ( α) grain size from 7.8 to 6.6 μm. Heavy deformation using multiple passes between A e3 and A r3 with true strain of 0.8 to 1.2 effectively refined the α grain size (4.1 to 3.2 μm) close to the ultrafine size by dynamic-strain-induced austenite ( γ) → ferrite ( α) transformation (DSIT). The intensities of microstructural banding, pearlite fraction in the microstructure (13 pct), and fraction of the harmful "cube" texture component (5 pct) were reduced with the increase in finishing deformation. Simultaneously, the fractions of high-angle (>15 deg misorientation) boundaries (75 to 80 pct), beneficial gamma-fiber (ND//<111>) texture components, along with {332}<133> and {554}<225> components were increased. Grain refinement and the formation of small Fe3C particles (50- to 600-nm size) increased the hardness of the deformed samples (184 to 192 HV). For the same deformation temperature [1103 K (830 °C)], the difference in α-grain sizes obtained after single-pass (2.7 μm) and multipass compression (3.2 μm) can be explained in view of the static- and dynamic-strain-induced γ → α transformation, strain partitioning between γ and α, dynamic recovery and dynamic recrystallization of the deformed α, and α-grain growth during interpass intervals.

Extracting Tree Height from Repeat-Pass PolInSAR Data : Experiments with JPL and ESA Airborne Systems

NASA Technical Reports Server (NTRS)

Lavalle, Marco; Ahmed, Razi; Neumann, Maxim; Hensley, Scott

2013-01-01

In this paper we present our latest developments and experiments with the random-motion-over-ground (RMoG) model used to extract canopy height and other important forest parameters from repeat-pass polarimetricinterferometric SAR (Pol-InSAR) data. More specifically, we summarize the key features of the RMoG model in contrast with the random-volume-over-ground (RVoG) model, describe in detail a possible inversion scheme for the RMoG model and illustrate the results of the RMoG inversion using airborne data collected by the Jet Propulsion Laboratory (JPL) and the European Space Agency (ESA).

Repeat ridge jumps associated with plume-ridge interaction, melt transport, and ridge migration

NASA Astrophysics Data System (ADS)

Mittelstaedt, Eric; Ito, Garrett; van Hunen, Jeroen

2011-01-01

Repeated shifts, or jumps, of mid-ocean ridge segments toward nearby hot spots can produce large, long-term changes to the geometry and location of the tectonic plate boundaries. Ridge jumps associated with hot spot-ridge interaction are likely caused by several processes including shear on the base of the plate due to expanding plume material as well as reheating of lithosphere as magma passes through it to feed off-axis volcanism. To study how these processes influence ridge jumps, we use numerical models to simulate 2-D (in cross section) viscous flow of the mantle, viscoplastic deformation of the lithosphere, and melt migration upward from the asthenospheric melting zone, laterally along the base of the lithosphere, and vertically through the lithosphere. The locations and rates that magma penetrates and heats the lithosphere are controlled by the time-varying accumulation of melt beneath the plate and the depth-averaged lithospheric porosity. We examine the effect of four key parameters: magmatic heating rate of the lithosphere, plate spreading rate, age of the seafloor overlying the plume, and the plume-ridge migration rate. Results indicate that the minimum value of the magmatic heating rate needed to initiate a ridge jump increases with plate age and spreading rate. The time required to complete a ridge jump decreases with larger values of magmatic heating rate, younger plate age, and faster spreading rate. For cases with migrating ridges, models predict a range of behaviors including repeating ridge jumps, much like those exhibited on Earth. Repeating ridge jumps occur at moderate magmatic heating rates and are the result of changes in the hot spot magma flux in response to magma migration along the base of an evolving lithosphere. The tendency of slow spreading to promote ridge jumps could help explain the observed clustering of hot spots near the Mid-Atlantic Ridge. Model results also suggest that magmatic heating may significantly thin the lithosphere, as has been suggested at Hawaii and other hot spots.

Electron backscatter diffraction study of deformation and recrystallization textures of individual phases in a cross-rolled duplex steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaid, Md; Bhattacharjee, P.P., E-mail: pinakib@iith.ac.in

2014-10-15

The evolution of microstructure and texture during cross-rolling and annealing was investigated by electron backscatter diffraction in a ferritic–austenitic duplex stainless steel. For this purpose an alloy with nearly equal volume fraction of the two phases was deformed by multi-pass cross-rolling process up to 90% reduction in thickness. The rolling and transverse directions were mutually interchanged in each pass by rotating the sample by 90° around the normal direction. In order to avoid deformation induced phase transformation and dynamic strain aging, the rolling was carried out at an optimized temperature of 898 K (625 °C) at the warm-deformation range. Themore » microstructure after cross warm-rolling revealed a lamellar structure with alternate arrangement of the bands of two phases. Strong brass and rotated brass components were observed in austenite in the steel after processing by cross warm-rolling. The ferrite in the cross warm-rolling processed steel showed remarkably strong RD-fiber (RD//< 011 >) component (001)< 011 >. The development of texture in the two phases after processing by cross warm-rolling could be explained by the stability of the texture components. During isothermal annealing of the 90% cross warm-rolling processed material the lamellar morphology was retained before collapse of the lamellar structure to the mutual interpenetration of the phase bands. Ferrite showed recovery resulting in annealing texture similar to the deformation texture. In contrast, the austenite showed primary recrystallization without preferential orientation selection leading to the retention of deformation texture. The evolution of deformation and annealing texture in the two phases of the steel was independent of one another. - Highlights: • Effect of cross warm-rolling on texture formation is studied in duplex steel. • Brass texture in austenite and (001)<110 > in ferrite are developed. • Ferrite shows recovery during annealing retaining the (001)<110 > component. • Austenite shows recrystallization during annealing retaining the deformation texture. • The deformation of recrystallization of two phases is independent of one other.« less

Multi-band filter design with less total film thickness for short-wave infrared

NASA Astrophysics Data System (ADS)

Yan, Yung-Jhe; Chien, I.-Pen; Chen, Po-Han; Chen, Sheng-Hui; Tsai, Yi-Chun; Ou-Yang, Mang

2017-08-01

A multi-band pass filter array was proposed and designed for short wave infrared applications. The central wavelength of the multi-band pass filters are located about 905 nm, 950 nm, 1055 nm and 1550 nm. In the simulation of an optical interference band pass filter, high spectrum performance (high transmittance ratio between the pass band and stop band) relies on (1) the index gap between the selected high/low-index film materials, with a larger gap correlated to higher performance, and (2) sufficient repeated periods of high/low-index thin-film layers. When determining high and low refractive index materials, spectrum performance was improved by increasing repeated periods. Consequently, the total film thickness increases rapidly. In some cases, a thick total film thickness is difficult to process in practice, especially when incorporating photolithography liftoff. Actually the maximal thickness of the photoresist being able to liftoff will bound the total film thickness of the band pass filter. For the application of the short wave infrared with the wavelength range from 900nm to 1700nm, silicone was chosen as a high refractive index material. Different from other dielectric materials used in the visible range, silicone has a higher absorptance in the visible range opposite to higher transmission in the short wave infrared. In other words, designing band pass filters based on silicone as a high refractive index material film could not obtain a better spectrum performance than conventional high index materials like TiO2 or Ta2O5, but also its material cost would reduce about half compared to the total film thickness with the conventional material TiO2. Through the simulation and several experimental trials, the total film thickness below 4 um was practicable and reasonable. The fabrication of the filters was employed a dual electric gun deposition system with ion assisted deposition after the lithography process. Repeating four times of lithography and deposition process and black matrix coating, the optical device processes were completed.

Thermal behavior of copper processed by ECAP at elevated temperatures

NASA Astrophysics Data System (ADS)

Gonda, Viktor

2018-05-01

Large amount of strengthening can be achieved by equal channel angular pressing (ECAP), by the applied severe plastic deformation during the processing. For pure metals, this high strength is accompanied with low thermal stability due to the large activation energy for recrystallization. In the present paper, the chosen technological route was elevated temperature single pass ECAP processing of copper, and its effect on the thermal behavior during the restoration processes of the deformed samples was studied.

Design of micro bending deformer for optical fiber weight sensor

NASA Astrophysics Data System (ADS)

Ula, R. K.; Hanto, D.; Waluyo, T. B.; Adinanta, H.; Widiyatmoko, B.

2017-04-01

The road damage due to excessive load is one of the causes of accidents on the road. A device to measure weight of the passing vehicles needs to be planted in the road structure. Thus, a weight sensor for the passing vehicles is required. In this study, we designed a weight sensor for a static load based on a power loss due to a micro bending on the optical fiber flanked on a board. The following main components are used i.e. LED 1310 nm as a light source, a multimode fiber optic as a transmission media and a power meter for measuring power loss. This works focuses on obtaining a suitable deformer design for weight sensor. Experimental results show that deformer design with 1.5 mm single side has level of accuracy as 4.32% while the design with 1.5 mm double side has level of accuracy as 98.77%. Increasing deformer length to 2.5 mm gives 71.18% level of accuracy for single side, and 76.94% level of accuracy for double side. Micro bending design with 1.5 mm double side has a high sensitivity and it is also capable of measuring load up to 100 kg. The sensor designed has been tested for measuring the weight of motor cycle, and it can be upgraded for measuring heavy vehicles.

Changes in the state of heat-resistant steel induced by repeated hot deformation

NASA Astrophysics Data System (ADS)

Lyubimova, Lyudmila L.; Fisenko, Roman N.; Tashlykov, Alexander A.; Tabakaev, Roman B.

2018-01-01

This work deals with the problems of structural regeneration by thermal restoration treatment (TRT). These include the lack of a structural sign showing that TRT is possible, a consensus on TRT modes, the data on the necessary relaxation depth of residual stresses, or criteria of structural restoration. Performing a TRT without solving these problems may deteriorate the properties of steel or even accelerate its destruction. With this in view, the purpose of this work is to determine experimentally how the residual stress state changes under thermal and mechanical loads in order to specify the signs of the restoration of structure and structural stability. The object of this research is unused 12Cr1MoV steel that has been aged naturally for 13 years. Using X-ray dosimetry with X-ray spectral analysis, we study the distribution of internal residual stresses of the first kind during the repeated hot deformation. After repeated thermal deformation, the sample under study transforms from a viscoelastic Maxwell material into a Kelvin-Voigt material, which facilitates structural stabilization. A sign of this is the relaxation limit increase, prevention of continuous decay of an α-solid solution of iron and restoration of the lattice parameter.

Energetic Particle Sounding of the Magnetopause Deformed by Hot Flow Anomaly

NASA Astrophysics Data System (ADS)

Zhao, L.; Zong, Q.; Zhang, H.

2017-12-01

Hot flow anomalies (HFAs), which are frequently observed near Earth's bow shock, are phenomena resulting from the interaction between interplanetary discontinuities and Earth's bow shock. Such transient phenomena upstream the bow shock can cause significant deformation of the bow shock and the magnetosphere, generating traveling convection vortices, field-aligned currents, and ULF waves in the Earth's magnetosphere. A large HFA was observed by MMS on November 19, 2015, lasting about 16 minutes. In this study, energetic particle sounding method with high time resolution (150 ms) Fast Plasma Investigation (FPI) data is used to determine the deformed magnetopause distances, orientations, and structures in the interval when MMS pass through the deformed magnetopause. The energetic particle sounding result from single MMS satellite for every moment in the interval when the distance from the magnetopause to the satellite is less than two proton gyro radii shows the profile of the deformed magnetopause.

Surgical correction of pectus excavatum and carinatum.

PubMed Central

Singh, S V

1980-01-01

This paper contains an analysis of the long-term results in 85 patients who had pectus excavatum or carinatum deformities repaired at the North Middlesex Hospital between 1951 and 1977. Seventy-seven patients had operations for correction of pectus excavatum and eight for pectus carinatum. A variety of surgical techniques was used. In the excavatum deformities the best results were obtained by the extensive resection of all deformed cartilages, the correction of the sternal deformity by a simple transverse wedge osteotomy, and by stabilising the chest with a stainless steel plate. For pectus carinatum, the involved cartilages were resected and an osteotomy of the sternum was performed. We preferred in most cases to stabilise the chest wall with a metal strut in this deformity as well. The best cosmetic results were achieved by the use of a stainless steel plate passed beneath the sternum and left for not more than six months. PMID:7444843

Reliability of corneal dynamic scheimpflug analyser measurements in virgin and post-PRK eyes.

PubMed

Chen, Xiangjun; Stojanovic, Aleksandar; Hua, Yanjun; Eidet, Jon Roger; Hu, Di; Wang, Jingting; Utheim, Tor Paaske

2014-01-01

To determine the measurement reliability of CorVis ST, a dynamic Scheimpflug analyser, in virgin and post-photorefractive keratectomy (PRK) eyes and compare the results between these two groups. Forty virgin eyes and 42 post-PRK eyes underwent CorVis ST measurements performed by two technicians. Repeatability was evaluated by comparing three consecutive measurements by technician A. Reproducibility was determined by comparing the first measurement by technician A with one performed by technician B. Intraobserver and interobserver intraclass correlation coefficients (ICCs) were calculated. Univariate analysis of covariance (ANCOVA) was used to compare measured parameters between virgin and post-PRK eyes. The intraocular pressure (IOP), central corneal thickness (CCT) and 1st applanation time demonstrated good intraobserver repeatability and interobserver reproducibility (ICC ≧ 0.90) in virgin and post-PRK eyes. The deformation amplitude showed a good or close to good repeatability and reproducibility in both groups (ICC ≧ 0.88). The CCT correlated positively with 1st applanation time (r = 0.437 and 0.483, respectively, p<0.05) and negatively with deformation amplitude (r = -0.384 and -0.375, respectively, p<0.05) in both groups. Compared to post-PRK eyes, virgin eyes showed longer 1st applanation time (7.29 ± 0.21 vs. 6.96 ± 0.17 ms, p<0.05) and lower deformation amplitude (1.06 ± 0.07 vs. 1.17 ± 0.08 mm, p < 0.05). CorVis ST demonstrated reliable measurements for CCT, IOP, and 1st applanation time, as well as relatively reliable measurement for deformation amplitude in both virgin and post-PRK eyes. There were differences in 1st applanation time and deformation amplitude between virgin and post-PRK eyes, which may reflect corneal biomechanical changes occurring after the surgery in the latter.

SU-F-J-151: Evaluation of a Magnetic Resonance Image Gated Radiotherapy System Using a Motion Phantom and Radiochromic Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamb, J; Ginn, J; O’Connell, D

Purpose: Magnetic resonance image (MRI) guided radiotherapy enables gating directly on target position for soft-tissue targets in the lung and abdomen. We present a dosimetric evaluation of a commercially-available FDA-approved MRI-guided radiotherapy system’s gating performance using a MRI-compatible respiratory motion phantom and radiochromic film. Methods: The MRI-compatible phantom was capable of one-dimensional motion. The phantom consisted of a target rod containing high-contrast target inserts which moved inside a body structure containing background contrast material. The target rod was equipped with a radiochromic film insert. Treatment plans were generated for a 3 cm diameter spherical target, and delivered to the phantommore » at rest and in motion with and without gating. Both sinusoidal and actual tumor trajectories (two free-breathing trajectories and one repeated-breath hold) were used. Gamma comparison at 5%/3mm was used to measure fidelity to the static target dose distribution. Results: Without gating, gamma pass rates were 24–47% depending on motion trajectory. Using our clinical standard of repeated breath holds and a gating window of 3 mm with 10% of the target allowed outside the gating boundary, the gamma pass rate was 99.6%. Relaxing the gating window to 5 mm resulted in gamma pass rate of 98.6% with repeated breath holds. For all motion trajectories gated with 3 mm margin and 10% allowed out, gamma pass rates were between 64–100% (mean:87.5%). For a 5 mm margin and 10% allowed out, gamma pass rates were between 57–98% (mean: 82.49%), significantly lower than for 3 mm by paired t-test (p=0.01). Conclusion: We validated the performance of respiratory gating based on real-time cine MRI images with the only FDA-approved MRI-guided radiotherapy system. Our results suggest that repeated breath hold gating should be used when possible for best accuracy. A 3 mm gating margin is statistically significantly more accurate than a 5 mm gating margin.« less

Residual stresses and plastic deformation in GTA-welded steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brand, P.C.; Keijser, T.H. de; Ouden, G. den

1993-03-01

Residual stresses and plastic deformation in single pass GTA welded low-carbon steel were studied by means of x-ray diffraction in combination with optical microscopy and hardness measurements. The residual stresses and the amount of plastic deformation (microstrain) were obtained from x-ray diffraction line positions and line broading. Since the plates were polished before welding, it was possible to observe in the optical microscope two types of Lueders bands. During heating curved Lueders bands and during cooling straight Lueders bands perpendicular to the weld are formed. The curved Lueders bands extend over a larger distance from the weld than the straightmore » Lueders bands. The amount of plastic deformation as obtained from the x-ray diffraction analysis is in agreement with these observations. An explanation is offered for the stresses measured in combination with plastic deformations observed. It is concluded that in the present experiments plastic deformation is the main cause of the residual stresses.« less

In situ-measurement of ice deformation from repeated borehole logging of the EPICA Dronning Maud Land (EDML) ice core, East Antarctica.

NASA Astrophysics Data System (ADS)

Jansen, Daniela; Weikusat, Ilka; Kleiner, Thomas; Wilhelms, Frank; Dahl-Jensen, Dorthe; Frenzel, Andreas; Binder, Tobias; Eichler, Jan; Faria, Sergio H.; Sheldon, Simon; Panton, Christian; Kipfstuhl, Sepp; Miller, Heinrich

2017-04-01

The European Project for Ice Coring in Antarctica (EPICA) ice core was drilled between 2001 and 2006 at the Kohnen Station, Antarctica. During the drilling process the borehole was logged repeatedly. Repeated logging of the borehole shape is a means of directly measuring the deformation of the ice sheet not only on the surface but also with depth, and to derive shear strain rates for the lower part, which control the volume of ice transported from the inner continent towards the ocean. The logging system continuously recorded the tilt of the borehole with respect to the vertical (inclination) as well as the heading of the borehole with respect to magnetic north (azimuth) by means of a compass. This dataset provides the basis for a 3-D reconstruction of the borehole shape, which is changing over time according to the predominant deformation modes with depth. The information gained from this analysis can then be evaluated in combination with lattice preferred orientation, grain size and grain shape derived by microstructural analysis of samples from the deep ice core. Additionally, the diameter of the borehole, which was originally circular with a diameter of 10 cm, was measured. As the ice flow velocity at the position of the EDML core is relatively slow (about 0.75 m/a), the changes of borehole shape between the logs during the drilling period were very small and thus difficult to interpret. Thus, the site has been revisited in the Antarctic summer season 2016 and logged again using the same measurement system. The change of the borehole inclination during the time period of 10 years clearly reveals the transition from a pure shear dominated deformation in the upper part of the ice sheet to shear deformation at the base. We will present a detailed analysis of the borehole parameters and the deduced shear strain rates in the lower part of the ice sheet. The results are discussed with respect to ice microstructural data derived from the EDML ice core. Microstructural data directly reflect the deformation conditions, as the ice polycrystal performs the deformation which leads e.g. to characteristic lattice orientation distributions and grain size and shape appearance. Though overprinted by recrystallization (due to the hot environment for the ice) and the slow deformation, analysis of statistically significant grain numbers reveals indications typical for the changing deformation regimes with depth. Additionally we compare our results with strain rates derived from a simulation with a model for large scale ice deformation, the Parallel Ice Sheet Model (PISM).

Evaluation of a Post-Processing Approach for Multiscale Analysis of Biphasic Mechanics of Chondrocytes

PubMed Central

Sibole, Scott C.; Maas, Steve; Halloran, Jason P.; Weiss, Jeffrey A.; Erdemir, Ahmet

2014-01-01

Understanding the mechanical behavior of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue level deformations drive cell level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of 1st and 2nd order data passing to predict chondrocyte mechanics by analyzing cartilage deformations obtained for varying complexity of loading scenarios. A tissue scale model with a sub-region incorporating representation of chondron size and distribution served as control. The postprocessing approach first required solution of a homogeneous tissue level model, results of which were used to drive a separate cell level model (same characteristics as the subregion of control model). The 1st data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, e.g., change in aspect ratio. The 2nd order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries were considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, e.g., mass exchange rate. Nonetheless, employing higher-order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation. PMID:23809004

Improved Method Being Developed for Surface Enhancement of Metallic Materials

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Kantzos, Peter T.

2001-01-01

Surface enhancement methods induce a layer of beneficial residual compressive stress to improve the impact (FOD) resistance and fatigue life of metallic materials. A traditional method of surface enhancement often used is shot peening, in which small steel spheres are repeatedly impinged on metallic surfaces. Shot peening is inexpensive and widely used, but the plastic deformation of 20 to 40 percent imparted by the impacts can be harmful. This plastic deformation can damage the microstructure, severely limiting the ductility and durability of the material near the surface. It has also been shown to promote accelerated relaxation of the beneficial compressive residual stresses at elevated temperatures. Low-plasticity burnishing (LPB) is being developed as an improved method for the surface enhancement of metallic materials. LPB is being investigated as a rapid, inexpensive surface enhancement method under NASA Small Business Innovation Research contracts NAS3-98034 and NAS3-99116, with supporting characterization work at NASA. Previously, roller burnishing had been employed to refine surface finish. This concept was adopted and then optimized as a means of producing a layer of compressive stress of high magnitude and depth, with minimal plastic deformation (ref. 1). A simplified diagram of the developed process is given in the following figure. A single pass of a smooth, free-rolling spherical ball under a normal force deforms the surface of the material in tension, creating a compressive layer of residual stress. The ball is supported in a fluid with sufficient pressure to lift the ball off the surface of the retaining spherical socket. The ball is only in mechanical contact with the surface of the material being burnished and is free to roll on the surface. This apparatus is designed to be mounted in the conventional lathes and vertical mills currently used to machine parts. The process has been successfully applied to nickel-base superalloys by a team from the NASA Glenn Research Center, Lambda Research, and METCUT Research, as supported by the NASA Small Business Innovation Research Phase I and II programs, the Ultra Safe program, and the Ultra- Efficient Engine Technology (UEET) Program.

Effects of varying material properties on the load deformation characteristics of heel cushions.

PubMed

Sun, Pi-Chang; Wei, Hung-Wen; Chen, Chien-Hua; Wu, Chun-Hao; Kao, Hung-Chan; Cheng, Cheng-Kung

2008-07-01

Various insole materials were used in attenuation of heel-strike impact. This study presented a compression test to investigate the deformation characteristics of common heel cushions. There were two materials (thermoplastic elastomer "TPE" and silicone) with three hardness and six thickness being analyzed. They underwent consecutive loading-unloading cycles with a load control mode. The displacement of material thickness was recorded during cyclic compression being applied and released from 0 to 1050 N. The energy input, return and dissipation were evaluated based on the load deformation curves when new and after repeated compression. The TPE recovered more deformed energy and thickness than the silicone after the first loading cycle. The silicone would preserve more strain energy with increasing its hardness for the elastic recovery in the unloading process. The deformed energy was decreased as the original thickness did not completely recover under cyclic tests. The reduction in hysteresis area was gradually converged within 20 cycles. The silicone attenuated more impact energy in the initial cycles, but its energy dissipation was reduced after repeated loading. To increase hardness or thickness should be considered to improve resilience or accommodate persistent compression without flattening. The careful selection of cushion materials is imperative to meet individual functional demands.

Mechanical properties of a nitrogen-bearing austenitic steel during static and cycle deformation

NASA Astrophysics Data System (ADS)

Blinov, E. V.; Terent'ev, V. F.; Prosvirnin, D. V.

2016-09-01

The mechanical properties of a nitrogen-bearing corrosion-resistant austenitic steel containing 0.311% nitrogen have been studied during static and cyclic deformation. It is found that the steel having an ultimate strength of 930 MPa exhibits a plasticity of 33%. The endurance limit under repeated tension at 106 loading cycles is 400 MPa. The propagation of a fatigue crack at low and high amplitudes of cyclic deformation follows a ductile fracture mechanism with the presence of fatigue grooves.

Seismology: tectonic strain in plate interiors?

PubMed

Calais, E; Mattioli, G; DeMets, C; Nocquet, J-M; Stein, S; Newman, A; Rydelek, P

2005-12-15

It is not fully understood how or why the inner areas of tectonic plates deform, leading to large, although infrequent, earthquakes. Smalley et al. offer a potential breakthrough by suggesting that surface deformation in the central United States accumulates at rates comparable to those across plate boundaries. However, we find no statistically significant deformation in three independent analyses of the data set used by Smalley et al., and conclude therefore that only the upper bounds of magnitude and repeat time for large earthquakes can be inferred at present.

Effects of deformability of RBCs on their dynamics and blood flow passing through a stenosed microvessel: an immersed boundary-lattice Boltzmann approach

NASA Astrophysics Data System (ADS)

Alizadeh, As'ad; Dadvand, Abdolrahman

2018-02-01

In this paper, the motion of high deformable (healthy) and low deformable (sick) red blood cells in a microvessel with and without stenosis is simulated using a combined lattice Boltzmann-immersed boundary method. The RBC is considered as neo-Hookean elastic membrane with bending resistance. The motion and deformation of the RBC under different values of the Reynolds number are evaluated. In addition, the variations of blood flow resistance and time-averaged pressure due to the motion and deformation of the RBC are assessed. It was found that a healthy RBC moves faster than a sick one. The apparent viscosity and blood flow resistance are greater for the case involving the sick RBC. Blood pressure at the presence of stenosis and low deformable RBC increases, which is thought of as the reason of many serious diseases including cardiovascular diseases. As the Re number increases, the RBC deforms further and moves easier and faster through the stenosis. The results of this study were compared to the available experimental and numerical results, and good agreements were observed.

Low-cycle fatigue of Fe-20%Cr alloy processed by equal- channel angular pressing

NASA Astrophysics Data System (ADS)

Kaneko, Yoshihisa; Tomita, Ryuji; Vinogradov, Alexei

2014-08-01

Low-cycle fatigue properties were investigated on Fe-20%Cr ferritic stainless steel processed by equal channel angular pressing (ECAP). The Fe-20%Cr alloy bullets were processed for one to four passes via Route-Bc. The ECAPed samples were cyclically deformed at the constant plastic strain amplitude ɛpl of 5x10-4 at room temperature in air. After the 1-pass ECAP, low-angle grain boundaries were dominantly formed. During the low-cycle fatigue test, the 1-pass sample revealed the rapid softening which continued until fatigue fracture. Fatigue life of the 1-pass sample was shorter than that of a coarse-grained sample. After the 4-pass ECAP, the average grain size reduced down to about 1.5 μm. At initial stage of the low-cycle fatigue tests, the stress amplitude increased with increasing ECAP passes. At the samples processed for more than 2 passes, the cyclic softening was relatively moderate. It was found that fatigue life of the ECAPed Fe-20%Cr alloy excepting the 1-pass sample was improved as compared to the coarse-grained sample, even under the strain controlled fatigue condition.

Properties of axially loaded implant-abutment assemblies using digital holographic interferometry analysis.

PubMed

Brozović, Juraj; Demoli, Nazif; Farkaš, Nina; Sušić, Mato; Alar, Zeljko; Gabrić Pandurić, Dragana

2014-03-01

The aim of this study was to (i) obtain the force-related interferometric patterns of loaded dental implant-abutment assemblies differing in diameter and brand using digital holographic interferometry (DHI) and (ii) determine the influence of implant diameter on the extent of load-induced implant deformation by quantifying and comparing the obtained interferometric data. Experiments included five implant brands (Ankylos, Astra Tech, blueSKY, MIS and Straumann), each represented by a narrow and a wide diameter implant connected to a corresponding abutment. A quasi-Fourier setup with a 25mW helium-neon laser was used for interferometric measurements in the cervical 5mm of the implants. Holograms were recorded in two conditions per measurement: a 10N preloaded and a measuring-force loaded assembly, resulting with an interferogram. This procedure was repeated throughout the whole process of incremental axial loading, from 20N to 120N. Each measurement series was repeated three times for each assembly, with complete dismantling of the implant-loading device in between. Additional software analyses calculated deformation data. Deformations were presented as mean values±standard deviations. Statistical analysis was performed using linear mixed effects modeling in R's lme4 package. Implants exhibited linear deformation patterns. The wide diameter group had lower mean deformation values than the narrow diameter group. The diameter significantly affected the deformation throughout loading sessions. This study gained in vitro implant performance data, compared the deformations in implant bodies and numerically stated the biomechanical benefits of wider diameter implants. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Repeatability of a 3D multi-segment foot model protocol in presence of foot deformities.

PubMed

Deschamps, Kevin; Staes, Filip; Bruyninckx, Herman; Busschots, Ellen; Matricali, Giovanni A; Spaepen, Pieter; Meyer, Christophe; Desloovere, Kaat

2012-07-01

Repeatability studies on 3D multi-segment foot models (3DMFMs) have mainly considered healthy participants which contrasts with the widespread application of these models to evaluate foot pathologies. The current study aimed at establishing the repeatability of the 3DMFM described by Leardini et al. in presence of foot deformities. Foot kinematics of eight adult participants were analyzed using a repeated-measures design including two therapists with different levels of experience. The inter-trial variability was higher compared to the kinematics of healthy subjects. Consideration of relative angles resulted in the lowest inter-session variability. The absolute 3D rotations between the Sha-Cal and Cal-Met seem to have the lowest variability in both therapists. A general trend towards higher σ(sess)/σ(trial) ratios was observed when the midfoot was involved. The current study indicates that not only relative 3D rotations and planar angles can be measured consistently in patients, also a number of absolute parameters can be consistently measured serving as basis for the decision making process. Copyright © 2012 Elsevier B.V. All rights reserved.

TU-A-12A-01: Consistency of Lung Expansion and Contraction During Respiration: Implications for Quantitative Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, T; Du, K; Bayouth, J

Purpose: Four-dimensional computed tomography (4DCT) can be used to evaluate longitudinal changes in pulmonary function. The sensitivity of such measurements to identify function change may be improved with reproducible breathing patterns. The purpose of this study was to determine if inhale was more consistent than exhale, i.e., lung expansion during inhalation compared to lung contraction during exhalation. Methods: Repeat 4DCT image data acquired within a short time interval from 8 patients. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. Equivalent lungmore » volumes (ELV) were used for 5 subjects and equivalent title volumes (ETV) for the 3 subjects who experienced a baseline shift between scans. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2mm distance-to-agreement and 5% ventilation difference. The gamma pass rates were then compared using paired t-test to determine if there was a significant difference. Results: Inhalation was more reproducible than exhalation. In the 5 ELV subjects 78.5% of the lung voxels met the gamma criteria for expansion during inhalation when comparing the two scans, while significantly fewer (70.9% of the lung voxels) met the gamma criteria for contraction during exhalation (p = .027). In the 8 total subjects analyzed the average gamma pass rate for expansion during inhalation was 75.2% while for contraction during exhalation it was 70.3%; which trended towards significant (p = .064). Conclusion: This work implies inhalation is more reproducible than exhalation, when equivalent respiratory volumes are considered. The reason for this difference is unknown. Longitudinal investigation of pulmonary function change based on inhalation images appears appropriate for Jacobian-based measure of lung tissue expansion. NIH Grant: R01 CA166703.« less

Dynamic deformable models for 3D MRI heart segmentation

NASA Astrophysics Data System (ADS)

Zhukov, Leonid; Bao, Zhaosheng; Gusikov, Igor; Wood, John; Breen, David E.

2002-05-01

Automated or semiautomated segmentation of medical images decreases interstudy variation, observer bias, and postprocessing time as well as providing clincally-relevant quantitative data. In this paper we present a new dynamic deformable modeling approach to 3D segmentation. It utilizes recently developed dynamic remeshing techniques and curvature estimation methods to produce high-quality meshes. The approach has been implemented in an interactive environment that allows a user to specify an initial model and identify key features in the data. These features act as hard constraints that the model must not pass through as it deforms. We have employed the method to perform semi-automatic segmentation of heart structures from cine MRI data.

Plastic deformation at surface during unlubricated sliding

NASA Technical Reports Server (NTRS)

Yamamoto, T.; Buckley, D. H.

1982-01-01

The plastic deformation and wear of 304 stainless-steel surface slid against an aluminum oxide rider were observed by using a scanning electron microscope and an optical microscope. Experiments were conducted in a vacuum of 0.000001 Pa and in an environment of 0.0005 Pa chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step-shaped protuberances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. These observations result from both adhesion and an adhesive wear mechanism.

Microfluidics separation reveals the stem-cell-like deformability of tumor-initiating cells.

PubMed

Zhang, Weijia; Kai, Kazuharu; Choi, Dong Soon; Iwamoto, Takayuki; Nguyen, Yen H; Wong, Helen; Landis, Melissa D; Ueno, Naoto T; Chang, Jenny; Qin, Lidong

2012-11-13

Here we report a microfluidics method to enrich physically deformable cells by mechanical manipulation through artificial microbarriers. Driven by hydrodynamic forces, flexible cells or cells with high metastatic propensity change shape to pass through the microbarriers and exit the separation device, whereas stiff cells remain trapped. We demonstrate the separation of (i) a mixture of two breast cancer cell types (MDA-MB-436 and MCF-7) with distinct deformabilities and metastatic potentials, and (ii) a heterogeneous breast cancer cell line (SUM149), into enriched flexible and stiff subpopulations. We show that the flexible phenotype is associated with overexpression of multiple genes involved in cancer cell motility and metastasis, and greater mammosphere formation efficiency. Our observations support the relationship between tumor-initiating capacity and cell deformability, and demonstrate that tumor-initiating cells are less differentiated in terms of cell biomechanics.

The Dependence of Portevin-Le Châtelier Effect on the γ' Precipitates in a Wrought Ni-Base Superalloy

NASA Astrophysics Data System (ADS)

Wang, Xinguang; Han, Guoming; Cui, Chuanyong; Guan, Shuai; Jin, Tao; Sun, Xiaofeng; Hu, Zhuangqi

2016-12-01

The dependence of Portevin-Le Châtelier (PLC) effect on the γ' precipitates of the Nimonic 263 alloy in different microstructural conditions has been studied by analyzing the parameters of the tensile curves and the deformation mechanisms. It is shown that the γ' precipitates with different sizes, edge-to-edge interprecipitate distance, and areal number density are obtained by altering the aging time. It is demonstrated that when the mean size of the γ' precipitates is less than 28 nm (aging less than 25 hours), the deformation mechanisms are dominated by APB-coupled a/2<101> dislocations shearing the small γ' precipitates and the slip bands continuously cutting the γ and γ' phases. When the γ' size is between 28 and 45 nm (aging time between 25 and 50 hours), the deformation mechanism is controlled by the APB-coupled a/2<101> dislocations shearing the small γ' precipitates, the a/6<112> Shockley partial dislocation continuously shearing the γ and γ' phases combined with matrix dislocations by-passing the γ' precipitates; If the γ' size over 45 nm (aging time more than 50 hours), Orowan by-passing becomes the main deformation mechanism. Moreover, with increasing the aging time, the critical plastic strain for the onset of the PLC effect increases and reaches a maximum after aging for 50 hours, and then gradually decreases. At last, the dependence of critical plastic strain on the deformation mechanisms is well explained by the elementary incremental strain (γ). The precipitation process of the γ' phase can directly influence the PLC effect by changing the interactions among solutes atoms, mobile dislocations, and forest dislocations.

Monitoring The Stability Of Levees With Time-Series ENVISAT ASAR Images

NASA Astrophysics Data System (ADS)

Pei, Yuanyuan; Liao, Mingsheng; Wang, Teng; Zhang, Lu

2012-01-01

Levees are constructed to protect coastal cities from typhoon, flood, and sea tide. Since the stability of levees is important, it is necessary to monitor their deformation regularly. Repeat-track space-borne SAR images are useful for environment monitoring, especially for ground deformation monitoring. Shanghai resides on the Yangtze River Delta on China’s eastern coast. Each year, the city is hit by typhoons from the Pacific Ocean and threatened by the flood of the Yangtze River. We used Persistent Scatterer Interferometry to monitor the deformation of the levees. Our experiments show that the levees around Pudong airport and Lingang town suffer from serious deformation.

Effect of reduction of area on microstructure and mechanical properties of twinning-induced plasticity steel during wire drawing

NASA Astrophysics Data System (ADS)

Hwang, Joong-Ki; Son, Il-Heon; Yoo, Jang-Yong; Zargaran, A.; Kim, Nack J.

2015-09-01

The effect of reduction of area (RA), 10%, 20%, and 30%, during wire drawing on the inhomogeneities in microstructure and mechanical properties along the radial direction of Fe-Mn-Al-C twinning-induced plasticity steel has been investigated. After wire drawing, the deformation texture developed into the major <111> and minor <100> duplex fiber texture. However, the <111> texture became more pronounced in both center and surface areas as the RA per pass increased. It also shows that a larger RA per pass resulted in a higher yield strength and smaller elongation than a smaller RA per pass at all strain levels. Although inhomogeneities in microstructure and mechanical properties along the radial direction decreased with increasing RA per pass, there existed an optimum RA per pass for maximum drawing limit. Insufficient penetration of strain from surface to center at small RA per pass (e.g., 10%) and high friction and unsound metal flow at large RA per pass (e.g., 30%) all resulted in heterogeneous microstructure and mechanical properties along the radial direction of drawn wire. On the other hand, 20% RA per pass improved the drawing limit by about 30% as compared to the 10% and 30% RAs per pass.

Toward an MRI-based method to measure non-uniform cartilage deformation: an MRI-cyclic loading apparatus system and steady-state cyclic displacement of articular cartilage under compressive loading.

PubMed

Neu, C P; Hull, M L

2003-04-01

Recent magnetic resonance imaging (MRI) techniques have shown potential for measuring non-uniform deformations throughout the volume (i.e. three-dimensional (3D) deformations) in small orthopedic tissues such as articular cartilage. However, to analyze cartilage deformation using MRI techniques, a system is required which can construct images from multiple acquisitions of MRI signals from the cartilage in both the underformed and deformed states. The objectives of the work reported in this article were to 1) design an apparatus that could apply highly repeatable cyclic compressive loads of 400 N and operate in the bore of an MRI scanner, 2) demonstrate that the apparatus and MRI scanner can be successfully integrated to observe 3D deformations in a phantom material, 3) use the apparatus to determine the load cycle necessary to achieve a steady-state deformation response in normal bovine articular cartilage samples using a flat-surfaced and nonporous indentor in unconfined compression. Composed of electronic and pneumatic components, the apparatus regulated pressure to a double-acting pneumatic cylinder so that (1) load-controlled compression cycles were applied to cartilage samples immersed in a saline bath, (2) loading and recovery periods within a cycle varied in time duration, and (3) load magnitude varied so that the stress applied to cartilage samples was within typical physiological ranges. In addition the apparatus allowed gating for MR image acquisition, and operation within the bore of an MRI scanner without creating image artifacts. The apparatus demonstrated high repeatability in load application with a standard deviation of 1.8% of the mean 400 N load applied. When the apparatus was integrated with an MRI scanner programmed with appropriate pulse sequences, images of a phantom material in both the underformed and deformed states were constructed by assembling data acquired through multiple signal acquisitions. Additionally, the number of cycles to reach a steady-state response in normal bovine articular cartilage was 49 for a total cycle duration of 5 seconds, but decreased to 33 and 27 for increasing total cycle durations of 10 and 15 seconds, respectively. Once the steady-state response was achieved, 95% of all displacements were within +/- 7.42 microns of the mean displacement, indicating that the displacement response to the cyclic loads was highly repeatable. With this performance, the MRI-loading apparatus system meets the requirements to create images of articular cartilage from which 3D deformation can be determined.

Hurricane impacts on coastal wetlands: A half-century record of storm-generated features from Southern Louisiana

USGS Publications Warehouse

Morton, R.A.; Barras, J.A.

2011-01-01

Temporally and spatially repeated patterns of wetland erosion, deformation, and deposition are observed on remotely sensed images and in the field after hurricanes cross the coast of Louisiana. The diagnostic morphological wetland features are products of the coupling of high-velocity wind and storm-surge water and their interaction with the underlying, variably resistant, wetland vegetation and soils. Erosional signatures include construction of orthogonal-elongate ponds and amorphous ponds, pond expansion, plucked marsh, marsh denudation, and shoreline erosion. Post-storm gravity reflux of floodwater draining from the wetlands forms dendritic incisions around the pond margins and locally integrates drainage pathways forming braided channels. Depositional signatures include emplacement of broad zones of organic wrack on topographic highs and inorganic deposits of variable thicknesses and lateral extents in the form of shore-parallel sandy washover terraces and interior-marsh mud blankets. Deformational signatures primarily involve laterally compressed marsh and displaced marsh mats and balls. Prolonged water impoundment and marsh salinization also are common impacts associated with wetland flooding by extreme storms. Many of the wetland features become legacies that record prior storm impacts and locally influence subsequent storm-induced morphological changes. Wetland losses caused by hurricane impacts depend directly on impact duration, which is controlled by the diameter of hurricane-force winds, forward speed of the storm, and wetland distance over which the storm passes. Distinguishing between wetland losses caused by storm impacts and losses associated with long-term delta-plain processes is critical for accurate modeling and prediction of future conversion of land to open water. ?? Coastal Education & Research Foundation 2011.

Hurricane impacts on coastal wetlands: a half-century record of storm-generated features from southern Louisiana

USGS Publications Warehouse

Morton, Robert A.; Barras, John A.

2011-01-01

Temporally and spatially repeated patterns of wetland erosion, deformation, and deposition are observed on remotely sensed images and in the field after hurricanes cross the coast of Louisiana. The diagnostic morphological wetland features are products of the coupling of high-velocity wind and storm-surge water and their interaction with the underlying, variably resistant, wetland vegetation and soils. Erosional signatures include construction of orthogonal-elongate ponds and amorphous ponds, pond expansion, plucked marsh, marsh denudation, and shoreline erosion. Post-storm gravity reflux of floodwater draining from the wetlands forms dendritic incisions around the pond margins and locally integrates drainage pathways forming braided channels. Depositional signatures include emplacement of broad zones of organic wrack on topographic highs and inorganic deposits of variable thicknesses and lateral extents in the form of shore-parallel sandy washover terraces and interior-marsh mud blankets. Deformational signatures primarily involve laterally compressed marsh and displaced marsh mats and balls. Prolonged water impoundment and marsh salinization also are common impacts associated with wetland flooding by extreme storms. Many of the wetland features become legacies that record prior storm impacts and locally influence subsequent storm-induced morphological changes. Wetland losses caused by hurricane impacts depend directly on impact duration, which is controlled by the diameter of hurricane-force winds, forward speed of the storm, and wetland distance over which the storm passes. Distinguishing between wetland losses caused by storm impacts and losses associated with long-term delta-plain processes is critical for accurate modeling and prediction of future conversion of land to open water.

Thermally-assisted Magma Emplacement Explains Restless Calderas

NASA Astrophysics Data System (ADS)

Amoruso, A.; Crescentini, L.; D'Antonio, M.; Acocella, V.

2017-12-01

Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei, Italy, which is the best-known, yet most dangerous calderas, lying to the west of Naples and restless since the 1950s at least.Our elaboration of the geodetic data indicates that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust.Our thermal models show that the repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth 3 ka before the last eruption and, in turn, contributed to maintain the thermal anomaly itself. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks.Available information at other calderas highlights similarities to Campi Flegrei, in the pattern and cause of unrest. All monitored restless calderas have either geodetically (Yellowstone, Aira Iwo-Jima, Askja, Fernandina and, partly, Long Valley) or geophysically (Rabaul, Okmok) detected sill-like intrusions inducing repeated unrest. Some calderas (Yellowstone, Long Valley) also show stable deformation pattern, where inflation insists on and mimics the resurgence uplift. The common existence of sill-like sources, also responsible for stable deformation patterns, in restless calderas suggests close similarities to Campi Flegrei. This suggests a wider applicability of our model of thermally-assisted sill emplacement, to be tested by future studies to better understand not only the dynamics of restless calderas and their eruptive potential but also the growth and assemblage of igneous intrusions and plutons.

UAVSAR Active Electronically Scanned Array

NASA Technical Reports Server (NTRS)

Sadowy, Gregory, A.; Chamberlain, Neil F.; Zawadzki, Mark S.; Brown, Kyle M.; Fisher, Charles D.; Figueroa, Harry S.; Hamilton, Gary A.; Jones, Cathleen E.; Vorperian, Vatche; Grando, Maurio B.

2011-01-01

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronically scanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uchida, Y; Tachibana, H

Purpose: For head and neck VMAT (HN-VMAT), variations of position and deformation of patient’s shoulders is a concern to affect inaccuracy of dose distribution. It has been reported that the setup error of the shoulders was variable from 5 mm – 1 cm. The beams of the HN-VMAT pass through the shoulders. We assessed the impact of shoulder deformation to dose distribution for HN-VMAT. Methods: One HN-VMAT plan was generated using a patient’s CT. The patient’s CT was deformed using ImSimQA (Oncology Systems Limited, Shrewsbury, Shropshire, UK) to generate several patterns of the shoulders’ deformations when the right and leftmore » humeral heads were shifted with 3, 6, and 15 mm in the superior and inferior directions (SI), 3, 5, and 15 mm in the anterior and posterior directions (AP), and 5 and 15 mm in the right or left direction (LR). DVH comparison was performed in the different deformation patterns. The dosimetric parameters of D95% for CTV70Gy, CTV60Gy and CTV54Gy and dmax for Spinal cord were also measured. Gamma index evaluation (Criteria: 3%/2mm) was performed to exhibit clinically tolerable area in the comparison. Results: DVH comparison shows similar for all structures. As the comparison for the dosimetric parameters, the variations of D95% in the LR and AP were within 1%. There were larger variations in the SI than those in the other directions, however were within 1.5%. In gamma index evaluation, the small spots with higher gamma index values were appeared when the shift was 6 mm, however the pass ratio was 99.13%. Conclusion: HN-VMAT should be robust for shoulder deformation and geometric accuracy within 6 mm from patient’s setup and image-guided radiotherapy may be clinically acceptable for target dose coverage or normal tissue dose sparing.« less

Analysis of Factors Causing Poor Passing Rates and High Dropout Rates among Primary School Girls in Malawi

ERIC Educational Resources Information Center

Mzuza, Maureen Kapute; Yudong, Yang; Kapute, Fanuel

2014-01-01

Factors that cause poor examination passing rates and high dropout rates among primary school girls in Malawi were analysed. First hand data was collected by conducting a survey in all the three regions of Malawi. The respondents to the questionnaire were girls (402) who are repeating the last class in primary schools (Standard 8), primary school…

The growth of geological structures by repeated earthquakes: 2, Field examples of continental dip-slip faults

USGS Publications Warehouse

Stein, R.S.; King, G.C.P.; Rundle, J.B.

1988-01-01

A strong test of our understanding of the earthquake cycle is the ability to reproduce extant faultbounded geological structures, such as basins and ranges, which are built by repeated cycles of deformation. Three examples are considered for which the structure and fault geometry are well known: the White Wolf reverse fault in California, site of the 1952 Kern County M=7.3 earthquake, the Lost River normal fault in Idaho, site of the 1983 Borah Peak M=7.0 earthquake, and the Cricket Mountain normal fault in Utah, site of Quaternary slip events. Basin stratigraphy and seismic reflection records are used to profile the structure, and coseismic deformation measured by leveling surveys is used to estimate the fault geometry. To reproduce these structures, we add the deformation associated with the earthquake cycle (the coseismic slip and postseismic relaxation) to the flexure caused by the observed sediment load, treating the crust as a thin elastic plate overlying a fluid substrate. -from Authors

A flexible strain sensor based on a Conductive Polymer Composite for in situ measurement of parachute canopy deformation.

PubMed

Cochrane, Cédric; Lewandowski, Maryline; Koncar, Vladan

2010-01-01

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%.

A Flexible Strain Sensor Based on a Conductive Polymer Composite for in situ Measurement of Parachute Canopy Deformation

PubMed Central

Cochrane, Cédric; Lewandowski, Maryline; Koncar, Vladan

2010-01-01

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%. PMID:22163654

Triggering of repeating earthquakes in central California

USGS Publications Warehouse

Wu, Chunquan; Gomberg, Joan; Ben-Naim, Eli; Johnson, Paul

2014-01-01

Dynamic stresses carried by transient seismic waves have been found capable of triggering earthquakes instantly in various tectonic settings. Delayed triggering may be even more common, but the mechanisms are not well understood. Catalogs of repeating earthquakes, earthquakes that recur repeatedly at the same location, provide ideal data sets to test the effects of transient dynamic perturbations on the timing of earthquake occurrence. Here we employ a catalog of 165 families containing ~2500 total repeating earthquakes to test whether dynamic perturbations from local, regional, and teleseismic earthquakes change recurrence intervals. The distance to the earthquake generating the perturbing waves is a proxy for the relative potential contributions of static and dynamic deformations, because static deformations decay more rapidly with distance. Clear changes followed the nearby 2004 Mw6 Parkfield earthquake, so we study only repeaters prior to its origin time. We apply a Monte Carlo approach to compare the observed number of shortened recurrence intervals following dynamic perturbations with the distribution of this number estimated for randomized perturbation times. We examine the comparison for a series of dynamic stress peak amplitude and distance thresholds. The results suggest a weak correlation between dynamic perturbations in excess of ~20 kPa and shortened recurrence intervals, for both nearby and remote perturbations.

The role of red blood cell deformability and Na,K-ATPase function in selected risk factors of cardiovascular diseases in humans: focus on hypertension, diabetes mellitus and hypercholesterolemia.

PubMed

Radosinska, J; Vrbjar, N

2016-09-19

Deformability of red blood cells (RBC) is the ability of RBC to change their shape in order to pass through narrow capillaries in circulation. Deterioration in deformability of RBC contributes to alterations in microcirculatory blood flow and delivery of oxygen to tissues. Several factors are responsible for maintenance of RBC deformability. One of them is the Na,K-ATPase known as crucial enzyme in maintenance of intracellular ionic homeostasis affecting thus regulation of cellular volume and consequently RBC deformability. Decreased deformability of RBC has been found to be the marker of adverse outcomes in cardiovascular diseases (CVD) and the presence of cardiovascular risk factors influences rheological properties of the blood. This review summarizes knowledge concerning the RBC deformability in connection with selected risk factors of CVD, including hypertension, hyperlipidemia, and diabetes mellitus, based exclusively on papers from human studies. We attempted to provide an update on important issues regarding the role of Na,K-ATPase in RBC deformability. In patients suffering from hypertension as well as diabetes mellitus the Na,K-ATPase appears to be responsible for the changes leading to alterations in RBC deformability. The triggering factor for changes of RBC deformability during hypercholesterolemia seems to be the increased content of cholesterol in erythrocyte membranes.

Method and apparatus for corrugating strips

DOEpatents

Day, Jack R.; Curtis, Charles H.

1983-01-01

The invention relates to a method and a machine for transversely corrugating a continuous strip of metallic foil. The product foil comprises a succession of alternately disposed corrugations, each defining in cross section, a major segment of a circle. The foil to be corrugated is positioned to extend within a vertical passage in the machine. The walls of the passage are heated to promote the desired deformation of the foil. Foil-deforming rollers are alternately passed obliquely across the passage to respectively engage transverse sections of the foil. The rollers and their respective section of deformed foil comprise a stacked assembly which is moved incrementally through the heated passageway. As the assembly emerges from the passageway, the rollers spill from the corrugated foil and are recovered for re-use.

Synchrotron X-ray microbeam diffraction measurements of full elastic long range internal strain and stress tensors in commercial-purity aluminum processed by multiple passes of equal-channel angular pressing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phan, Thien Q.; Levine, Lyle E.; Lee, I-Fang

Synchrotron X-ray microbeam diffraction was used to measure the full elastic long range internal strain and stress tensors of low dislocation density regions within the submicrometer grain/subgrain structure of equal-channel angular pressed (ECAP) aluminum alloy AA1050 after 1, 2, and 8 passes using route B C. This is the first time that full tensors were measured in plastically deformed metals at this length scale. The maximum (most tensile or least compressive) principal elastic strain directions for the unloaded 1 pass sample for the grain/subgrain interiors align well with the pressing direction, and are more random for the 2 and 8more » pass samples. The measurements reported here indicate that the local stresses and strains become increasingly isotropic (homogenized) with increasing ECAP passes using route BC. The average maximum (in magnitude) LRISs are -0.43 σ a for 1 pass, -0.44 σ a for 2 pass, and 0.14 σ a for the 8 pass sample. Furthermore, these LRISs are larger than those reported previously because those earlier measurements were unable to measure the full stress tensor. Significantly, the measured stresses are inconsistent with the two-component composite model.« less

Synchrotron X-ray microbeam diffraction measurements of full elastic long range internal strain and stress tensors in commercial-purity aluminum processed by multiple passes of equal-channel angular pressing

DOE PAGES

Phan, Thien Q.; Levine, Lyle E.; Lee, I-Fang; ...

2016-04-23

Synchrotron X-ray microbeam diffraction was used to measure the full elastic long range internal strain and stress tensors of low dislocation density regions within the submicrometer grain/subgrain structure of equal-channel angular pressed (ECAP) aluminum alloy AA1050 after 1, 2, and 8 passes using route B C. This is the first time that full tensors were measured in plastically deformed metals at this length scale. The maximum (most tensile or least compressive) principal elastic strain directions for the unloaded 1 pass sample for the grain/subgrain interiors align well with the pressing direction, and are more random for the 2 and 8more » pass samples. The measurements reported here indicate that the local stresses and strains become increasingly isotropic (homogenized) with increasing ECAP passes using route BC. The average maximum (in magnitude) LRISs are -0.43 σ a for 1 pass, -0.44 σ a for 2 pass, and 0.14 σ a for the 8 pass sample. Furthermore, these LRISs are larger than those reported previously because those earlier measurements were unable to measure the full stress tensor. Significantly, the measured stresses are inconsistent with the two-component composite model.« less

Non-cycloplegic spherical equivalent refraction in adults: comparison of the double-pass system, retinoscopy, subjective refraction and a table-mounted autorefractor.

PubMed

Vilaseca, Meritxell; Arjona, Montserrat; Pujol, Jaume; Peris, Elvira; Martínez, Vanessa

2013-01-01

To evaluate the accuracy of spherical equivalent (SE) estimates of a double-pass system and to compare it with retinoscopy, subjective refraction and a table-mounted autorefractor. Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults (age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy, subjective refraction, autorefraction (Auto kerato-refractometer TOPCON KR-8100, Japan) and a double-pass system (Optical Quality Analysis System, OQAS, Visiometrics S.L., Spain). Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability. To evaluate the trueness of the OQAS instrument, the SE laboratory bias between the double-pass system and the other techniques was calculated. The SE mean coefficient of repeatability obtained was 0.22D. Significant correlations could be established between the OQAS and the SE obtained with retinoscopy (r=0.956, P<0.001), subjective refraction (r=0.955, P<0.001) and autorefraction (r=0.957, P<0.001). The differences in SE between the double-pass system and the other techniques were significant (P<0.001), but lacked clinical relevance except for retinoscopy; Retinoscopy gave more hyperopic values than the double-pass system -0.51±0.50D as well as the subjective refraction -0.23±0.50D; More myopic values were achieved by means of autorefraction 0.24±0.49D. The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies. This technique can determine the correct focus position to assess the ocular optical quality. However, it has a relatively small measuring range in comparison with autorefractors (-8.00 to +5.00D), and requires prior information on the refractive state of the patient.

Non-cycloplegic spherical equivalent refraction in adults: comparison of the double-pass system, retinoscopy, subjective refraction and a table-mounted autorefractor

PubMed Central

Vilaseca, Meritxell; Arjona, Montserrat; Pujol, Jaume; Peris, Elvira; Martínez, Vanessa

2013-01-01

AIM To evaluate the accuracy of spherical equivalent (SE) estimates of a double-pass system and to compare it with retinoscopy, subjective refraction and a table-mounted autorefractor. METHODS Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults (age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy, subjective refraction, autorefraction (Auto kerato-refractometer TOPCON KR-8100, Japan) and a double-pass system (Optical Quality Analysis System, OQAS, Visiometrics S.L., Spain). Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability. To evaluate the trueness of the OQAS instrument, the SE laboratory bias between the double-pass system and the other techniques was calculated. RESULTS The SE mean coefficient of repeatability obtained was 0.22D. Significant correlations could be established between the OQAS and the SE obtained with retinoscopy (r=0.956, P<0.001), subjective refraction (r=0.955, P<0.001) and autorefraction (r=0.957, P<0.001). The differences in SE between the double-pass system and the other techniques were significant (P<0.001), but lacked clinical relevance except for retinoscopy; Retinoscopy gave more hyperopic values than the double-pass system -0.51±0.50D as well as the subjective refraction -0.23±0.50D; More myopic values were achieved by means of autorefraction 0.24±0.49D. CONCLUSION The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies. This technique can determine the correct focus position to assess the ocular optical quality. However, it has a relatively small measuring range in comparison with autorefractors (-8.00 to +5.00D), and requires prior information on the refractive state of the patient. PMID:24195036

Microstructure heterogeneity after the ECAP process and its influence on recrystallization in aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wronski, S., E-mail: wronski@fis.agh.edu.pl; Tarasiuk, J., E-mail: tarasiuk@ftj.agh.edu.pl; Bacroix, B., E-mail: brigitte.bacroix@univ-paris13.fr

The main purpose of the present work is to describe the qualitative and quantitative behaviours of aluminium during high strain plastic deformation and the effect of deformation on the subsequent recrystallization process. An Electron Backscatter Diffraction analysis of aluminium after the Equal channel angular pressing (ECAP) and recrystallization process is presented. In order to do this, several topological maps are measured for samples processed by 4 and 8 passes and recrystallized. The processing was conducted with route C. For all samples, distributions of grain size, misorientation, image quality factor (IQ) and texture were preceded and then analysed in some detail.more » - Highlights: ► Describe the microstructure fragmentation in aluminum. ► High strain plastic deformation and effect of deformation on recrystallization. ► The microstructure fragmentation and its influence on recrystallization. ► Image quality factor and misorientation characteristics are examined using EBSD.« less

Changes in the physical and mechanical properties of Al-Mg alloy processed by severe plastic deformation

NASA Astrophysics Data System (ADS)

Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.; Moskvichev, E. N.; Borodulin, D. A.

2017-12-01

This paper presents the results of studies into the effect of severe plastic deformation on the microstructure, physical and mechanical properties of coarse-grained Al-Mg alloy 1560 in the as-received state with an average grain size of 50 µm. Severe plastic deformation is performed by four-pass equal channel angular pressing (ECAP), which results in the formation of an ultrafine-grained structure with an average grain size of 3 µm in the alloy. Analysis of experimental data revealed that the physical and mechanical properties change significantly after severe plastic deformation. The microhardness of the ECAPed alloy increases by 50%, tensile yield strength by 80%, and ultimate strength by 44% in comparison with these parameters in the as-received state. The constants of approximating functions have been determined for the experimental stress-strain curves of the alloy specimens in the as-received and ECAPed states.

Control of thermal deformation in dielectric mirrors using mechanical design and atomic layer deposition.

PubMed

Gabriel, Nicholas T; Kim, Sangho S; Talghader, Joseph J

2009-07-01

A mechanical design technique for optical coatings that simultaneously controls thermal deformation and optical reflectivity is reported. The method requires measurement of the refractive index and thermal stress of single films prior to the design. Atomic layer deposition was used for deposition because of the high repeatability of the film constants. An Al2O3/HfO2 distributed Bragg reflector was deposited with a predicted peak reflectivity of 87.9% at 542.4 nm and predicted edge deformation of -360 nm/K on a 10 cm silicon substrate. The measured peak reflectivity was 85.7% at 541.7 nm with an edge deformation of -346 nm/K.

Reliability of Corneal Dynamic Scheimpflug Analyser Measurements in Virgin and Post-PRK Eyes

PubMed Central

Chen, Xiangjun; Stojanovic, Aleksandar; Hua, Yanjun; Eidet, Jon Roger; Hu, Di; Wang, Jingting; Utheim, Tor Paaske

2014-01-01

Purpose To determine the measurement reliability of CorVis ST, a dynamic Scheimpflug analyser, in virgin and post-photorefractive keratectomy (PRK) eyes and compare the results between these two groups. Methods Forty virgin eyes and 42 post-PRK eyes underwent CorVis ST measurements performed by two technicians. Repeatability was evaluated by comparing three consecutive measurements by technician A. Reproducibility was determined by comparing the first measurement by technician A with one performed by technician B. Intraobserver and interobserver intraclass correlation coefficients (ICCs) were calculated. Univariate analysis of covariance (ANCOVA) was used to compare measured parameters between virgin and post-PRK eyes. Results The intraocular pressure (IOP), central corneal thickness (CCT) and 1st applanation time demonstrated good intraobserver repeatability and interobserver reproducibility (ICC≧0.90) in virgin and post-PRK eyes. The deformation amplitude showed a good or close to good repeatability and reproducibility in both groups (ICC≧0.88). The CCT correlated positively with 1st applanation time (r = 0.437 and 0.483, respectively, p<0.05) and negatively with deformation amplitude (r = −0.384 and −0.375, respectively, p<0.05) in both groups. Compared to post-PRK eyes, virgin eyes showed longer 1st applanation time (7.29±0.21 vs. 6.96±0.17 ms, p<0.05) and lower deformation amplitude (1.06±0.07 vs. 1.17±0.08 mm, p<0.05). Conclusions CorVis ST demonstrated reliable measurements for CCT, IOP, and 1st applanation time, as well as relatively reliable measurement for deformation amplitude in both virgin and post-PRK eyes. There were differences in 1st applanation time and deformation amplitude between virgin and post-PRK eyes, which may reflect corneal biomechanical changes occurring after the surgery in the latter. PMID:25302580

An analytic algorithm for global coverage of the revisiting orbit and its application to the CFOSAT satellite

NASA Astrophysics Data System (ADS)

Xu, Ming; Huang, Li

2014-08-01

This paper addresses a new analytic algorithm for global coverage of the revisiting orbit and its application to the mission revisiting the Earth within long periods of time, such as Chinese-French Oceanic Satellite (abbr., CFOSAT). In the first, it is presented that the traditional design methodology of the revisiting orbit for some imaging satellites only on the single (ascending or descending) pass, and the repeating orbit is employed to perform the global coverage within short periods of time. However, the selection of the repeating orbit is essentially to yield the suboptimum from the rare measure of rational numbers of passes per day, which will lose lots of available revisiting orbits. Thus, an innovative design scheme is proposed to check both rational and irrational passes per day to acquire the relationship between the coverage percentage and the altitude. To improve the traditional imaging only on the single pass, the proposed algorithm is mapping every pass into its ascending and descending nodes on the specified latitude circle, and then is accumulating the projected width on the circle by the field of view of the satellite. The ergodic geometry of coverage percentage produced from the algorithm is affecting the final scheme, such as the optimal one owning the largest percentage, and the balance one possessing the less gradient in its vicinity, and is guiding to heuristic design for the station-keeping control strategies. The application of CFOSAT validates the feasibility of the algorithm.

Advances in modelling subglacial lakes and their interaction with the Antarctic ice sheet.

PubMed

Pattyn, Frank; Carter, Sasha P; Thoma, Malte

2016-01-28

Subglacial lakes have long been considered hydraulically isolated water bodies underneath ice sheets. This view changed radically with the advent of repeat-pass satellite altimetry and the discovery of multiple lake discharges and water infill, associated with water transfer over distances of more than 200 km. The presence of subglacial lakes also influences ice dynamics, leading to glacier acceleration. Furthermore, subglacial melting under the Antarctic ice sheet is more widespread than previously thought, and subglacial melt rates may explain the availability for water storage in subglacial lakes and water transport. Modelling of subglacial water discharge in subglacial lakes essentially follows hydraulics of subglacial channels on a hard bed, where ice sheet surface slope is a major control on triggering subglacial lake discharge. Recent evidence also points to the development of channels in deformable sediment in West Antarctica, with significant water exchanges between till and ice. Most active lakes drain over short time scales and respond rapidly to upstream variations. Several Antarctic subglacial lakes exhibit complex interactions with the ice sheet due to water circulation. Subglacial lakes can therefore-from a modelling point of view-be seen as confined small oceans underneath an imbedded ice shelf. © 2015 The Author(s).

USGS Imagery Applications During Disaster Response After Recent Earthquakes

NASA Astrophysics Data System (ADS)

Hudnut, K. W.; Brooks, B. A.; Glennie, C. L.; Finnegan, D. C.

2015-12-01

It is not only important to rapidly characterize surface fault rupture and related ground deformation after an earthquake, but also to repeatedly make observations following an event to forecast fault afterslip. These data may also be used by other agencies to monitor progress on damage repairs and restoration efforts by emergency responders and the public. Related requirements include repeatedly obtaining reference or baseline imagery before a major disaster occurs, as well as maintaining careful geodetic control on all imagery in a time series so that absolute georeferencing may be applied to the image stack through time. In addition, repeated post-event imagery acquisition is required, generally at a higher repetition rate soon after the event, then scaled back to less frequent acquisitions with time, to capture phenomena (such as fault afterslip) that are known to have rates that decrease rapidly with time. For example, lidar observations acquired before and after the South Napa earthquake of 2014, used in our extensive post-processing work that was funded primarily by FEMA, aided in the accurate forecasting of fault afterslip. Lidar was used to independently validate and verify the official USGS afterslip forecast. In order to keep pace with rapidly evolving technology, a development pipeline must be established and maintained to continually test and incorporate new sensors, while adapting these new components to the existing platform and linking them to the existing base software system, and then sequentially testing the system as it evolves. Improvements in system performance by incremental upgrades of system components and software are essential. Improving calibration parameters and thereby progressively eliminating artifacts requires ongoing testing, research and development. To improve the system, we have formed an interdisciplinary team with common interests and diverse sources of support. We share expertise and leverage funding while effectively and rapidly improving our system, which includes the sensor package and software for all steps in acquiring, processing and differencing repeat-pass lidar and electro-optical imagery, and the GRiD metadata and point cloud database standard, already used during disaster response surge events by other agencies (e.g., during Hurricane Sandy in 2012).

Migratory behavior of adult sea lamprey and cumulative passage performance through four fishways

USGS Publications Warehouse

Castro-Santos, Theodore R.; Shi, Xiaotao; Haro, Alexander

2017-01-01

This article describes a study of PIT-tagged sea lamprey (Petromyzon marinus) ascending four fishways comprising three designs at two dams on the Connecticut River, USA. Migration between dams was rapid (median migration rate = 23 km·day−1). Movement through the fishways was much slower, however (median = 0.02–0.33 km·day−1). Overall delay at dams was substantial (median = 13.6–14.6 days); many fish failed to pass (percent passage ranged from 29% to 55%, depending on fishway), and repeated passage attempts compounded delay for both passers and failers. Cox regression revealed that fishway entry rates were influenced by flow, temperature, and diel cycle, with most lampreys entering at night and at elevated flows, but with no apparent effect of sex or length. Overall delay was influenced by slow movement through the fishways, but repeated failures were the primary factor determining delay. These data suggest that although some lamprey were able to pass fishways, they did so with difficulty, and delays incurred as they attempted to pass may act to limit their distribution within their native range.

The Ontario Veterinary College Hip Certification Program -- assessing inter- and intra-observer repeatability and comparison of findings to those of the Orthopedic Foundation for Animals.

PubMed

Chalmers, Heather J; Nykamp, Stephanie; Lerer, Assaf

2013-01-01

In Canada, the Ontario Veterinary College (OVC) has offered radiographic screening for hip dysplasia for many years, but there are other options for this service including the Orthopedic Foundation for Animals (OFA). There are some differences between the OFA and the OVC methods, and this study compares the OVC and OFA hip certification results in 37 dogs. There was good agreement between the two programs but in some instances there was a difference in the pass/fail status of a dog. Neither the OFA nor the OVC was more likely to fail or pass a given dog. The repeatability of the OVC results was assessed by both inter- and intra-observer comparisons in 100 dogs. There was at least 86% agreement among and within radiologists, but in 5 cases the disagreement resulted in a difference in the pass/fail status of the dog. These results illustrate the inherent variation in radiographic hip evaluation and highlight the importance of consensus grading practices to improve the accuracy of hip evaluation.

Investigation on Insar Time Series Deformation Model Considering Rheological Parameters for Soft Clay Subgrade Monitoring

NASA Astrophysics Data System (ADS)

Xing, X.; Yuan, Z.; Chen, L. F.; Yu, X. Y.; Xiao, L.

2018-04-01

The stability control is one of the major technical difficulties in the field of highway subgrade construction engineering. Building deformation model is a crucial step for InSAR time series deformation monitoring. Most of the InSAR deformation models for deformation monitoring are pure empirical mathematical models, without considering the physical mechanism of the monitored object. In this study, we take rheology into consideration, inducing rheological parameters into traditional InSAR deformation models. To assess the feasibility and accuracy for our new model, both simulation and real deformation data over Lungui highway (a typical highway built on soft clay subgrade in Guangdong province, China) are investigated with TerraSAR-X satellite imagery. In order to solve the unknows of the non-linear rheological model, three algorithms: Gauss-Newton (GN), Levenberg-Marquarat (LM), and Genetic Algorithm (GA), are utilized and compared to estimate the unknown parameters. Considering both the calculation efficiency and accuracy, GA is chosen as the final choice for the new model in our case study. Preliminary real data experiment is conducted with use of 17 TerraSAR-X Stripmap images (with a 3-m resolution). With the new deformation model and GA aforementioned, the unknown rheological parameters over all the high coherence points are obtained and the LOS deformation (the low-pass component) sequences are generated.

The Pre-Blast Concept for use on Armour Materials

DTIC Science & Technology

2016-02-01

to improve blast resistance Repeated blast test results (up to 7 times) of candidate armour materials showed that the greatest deformation...may be used to increase blast resistance of steels. To test this, the ‘pre-blast’ concept test program includes hardening of materials by sheet charge...steels with hardness 450 HV or higher (up to 650 HV). In general, the improvement in deformation resistance is associated with increases in

49 CFR 178.815 - Stacking test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... for transportation, and no loss of contents. (2) For fiberboard and wooden IBCs, there may be no loss... unsafe for transportation, and no loss of contents. (4) For the dynamic compression test, a container passes the test if, after application of the required load, there is no permanent deformation to the IBC...

Method and apparatus for corrugating strips

DOEpatents

Day, J.R.; Curtis, C.H.

1981-10-27

The invention relates to a method and a machine for transversely corrugating a continuous strip of metallic foil. The product foil comprises a succession of alternately disposed corrugations, each defining in a cross section, a major segment of a circle. The foil to be corrugated is positioned to extend within a vertical passage in the machine. The walls of the passage are heated to promote the desired deformation of the foil. Foil-deforming rollers are alternately passed obliquely across the passage to respectively engage transverse sections of the foil. The rollers and their respective section of deformed foil comprise a stacked assembly which is moved incrementally through the heated passageway. As the assembly emerges from the passageway, the rollers spill from the corrugated foil and are recovered for re-use.

Hydrodynamic interaction of two deformable drops in confined shear flow.

PubMed

Chen, Yongping; Wang, Chengyao

2014-09-01

We investigate hydrodynamic interaction between two neutrally buoyant circular drops in a confined shear flow based on a computational fluid dynamics simulation using the volume-of-fluid method. The rheological behaviors of interactive drops and the flow regimes are explored with a focus on elucidation of underlying physical mechanisms. We find that two types of drop behaviors during interaction occur, including passing-over motion and reversing motion, which are governed by the competition between the drag of passing flow and the entrainment of reversing flow in matrix fluid. With the increasing confinement, the drop behavior transits from the passing-over motion to reversing motion, because the entrainment of the reversing-flow matrix fluid turns to play the dominant role. The drag of the ambient passing flow is increased by enlarging the initial lateral separation due to the departure of the drop from the reversing flow in matrix fluid, resulting in the emergence of passing-over motion. In particular, a corresponding phase diagram is plotted to quantitatively illustrate the dependence of drop morphologies during interaction on confinement and initial lateral separation.

A study of red blood cell deformability in diabetic retinopathy using optical tweezers

NASA Astrophysics Data System (ADS)

Smart, Thomas J.; Richards, Christopher J.; Bhatnagar, Rhythm; Pavesio, Carlos; Agrawal, Rupesh; Jones, Philip H.

2015-08-01

Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus (DM) in which high blood sugar levels cause swelling, leaking and occlusions in the blood vessels of the retina, often resulting in a loss of sight. The microvascular system requires red blood cells (RBCs) to undergo significant cellular deformation in order to pass through vessels whose diameters are significantly smaller than their own. There is evidence to suggest that DM impairs the deformability of RBCs, and this loss of deformability has been associated with diabetic kidney disease (or nephropathy) - another microvascular complication of DM. However, it remains unclear whether reduced deformability of RBCs correlates with the presence of DR. Here we present an investigation into the deformability of RBCs in patients with diabetic retinopathy using optical tweezers. To extract a value for the deformability of RBCs we use a dual-trap optical tweezers set-up to stretch individual RBCs. RBCs are trapped directly (i.e. without micro-bead handles), so rotate to assume a `side-on' orientation. Video microscopy is used to record the deformation events, and shape analysis software is used to determine parameters such as initial and maximum RBC length, allowing us to calculate the deformability for each RBC. A small decrease in deformability of diabetes cells subject to this stretching protocol is observed when compared to control cells. We also report on initial results on three dimensional imaging of individual RBCs using defocussing microscopy.

The level of detail required in a deformable phantom to accurately perform quality assurance of deformable image registration

NASA Astrophysics Data System (ADS)

Saenz, Daniel L.; Kim, Hojin; Chen, Josephine; Stathakis, Sotirios; Kirby, Neil

2016-09-01

The primary purpose of the study was to determine how detailed deformable image registration (DIR) phantoms need to adequately simulate human anatomy and accurately assess the quality of DIR algorithms. In particular, how many distinct tissues are required in a phantom to simulate complex human anatomy? Pelvis and head-and-neck patient CT images were used for this study as virtual phantoms. Two data sets from each site were analyzed. The virtual phantoms were warped to create two pairs consisting of undeformed and deformed images. Otsu’s method was employed to create additional segmented image pairs of n distinct soft tissue CT number ranges (fat, muscle, etc). A realistic noise image was added to each image. Deformations were applied in MIM Software (MIM) and Velocity deformable multi-pass (DMP) and compared with the known warping. Images with more simulated tissue levels exhibit more contrast, enabling more accurate results. Deformation error (magnitude of the vector difference between known and predicted deformation) was used as a metric to evaluate how many CT number gray levels are needed for a phantom to serve as a realistic patient proxy. Stabilization of the mean deformation error was reached by three soft tissue levels for Velocity DMP and MIM, though MIM exhibited a persisting difference in accuracy between the discrete images and the unprocessed image pair. A minimum detail of three levels allows a realistic patient proxy for use with Velocity and MIM deformation algorithms.

Workability Limits of Magnesium Alloy AZ31B Subjected to Equal Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Arun, M. S.; Chakkingal, Uday

2018-03-01

Equal channel angular pressing (ECAP) is an important severe plastic deformation process to produce ultrafine grained microstructures in metals and alloys. Magnesium and its alloys generally possess poor workability at temperatures below 250 °C. This investigation examines the influence of different passes and processing routes of ECAP on improving the workability of Mg alloy AZ31B. ECAP was carried out for three passes using a die of angle 120° using processing routes Bc and C. The operating temperature was 523 K for the first pass and 423 K for the subsequent two passes. The resultant microstructure and mechanical properties were determined. Workability of the alloy at 423 K (150 °C) was determined using upsetting experiments on cylindrical specimens machined from the annealed and ECAPed samples. Workability limit diagrams have been constructed for the various processed conditions. The workability data generated were also analyzed using five different workability criteria (also referred to as ductile fracture models) and the material constants for these five models were evaluated. Specimens processed by two passes through route C (pass 2C) exhibits better workability compared to other passes since the workability limit line after this pass shows maximum safe working area and lies above the other workability lines. Among the five different workability criteria investigated, the Freudenthal workability criterion is more suitable for prediction of failure in this alloy.

Numerical simulations of elastic capsules with nucleus in shear flow

NASA Astrophysics Data System (ADS)

Alizad Banaei, Arash; Loiseau, Jean-Christophe; Lashgari, Iman; Brandt, Luca

2017-03-01

The shear-induced deformation of a capsule with a stiff nucleus, a model of eukaryotic cells, is studied numerically. The membrane of the cell and of its nucleus are modelled as a thin elastic material obeying a Neo-Hookean constitutive law. The fluid-structure coupling is obtained using an immersed boundary method. The variations induced by the presence of the nucleus on the cell deformation are investigated when varying the viscosity ratio between the inner and outer fluids, the membrane elasticity and its bending stiffness. The deformation of the eukaryotic cell is smaller than that of the prokaryotic one. The reduction in deformation increases for larger values of the capillary number. The eukaryotic cell remains thicker in its middle part compared to the prokaryotic one, thus making it less flexible to pass through narrow capillaries. For a viscosity ratio of 5, the deformation of the cell is smaller than in the case of uniform viscosity. In addition, for non-zero bending stiffness of the membrane, the deformation decreases and the shape is closer to an ellipsoid. Finally, we compare the results obtained modelling the nucleus as an inner stiffer membrane with those obtained using a rigid particle.

3-Dimensional Microstructure of Al-Al3Ti Alloy Severely Deformed by ECAP

NASA Astrophysics Data System (ADS)

Sato, Hisashi; Hishikawa, Takahisa; Makino, Yuuki; Kunimine, Takahiro; Watanabe, Yoshimi

Microstructure of Al-Al3Ti alloy deformed by Equal-Channel-Angular Pressing (ECAP) is 3-dimensionally investigated. Especially, distribution of Al3Ti particles is focused in this study. The Al-Al3Ti alloy has coarse Al3Ti platelet particles in α-Al matrix. When the Al-Al3Ti alloy is deformed by ECAP under route A, fine Al3Ti platelet particles are observed. These Al3Ti platelet particles are aligned along to deformation axis, and its plane normal is perpendicular to the deformation axis. On the other hand, Al-Al3Ti alloy ECAPed under route Bc forms several groups consisted of fine Al3Ti platelet particles. Moreover, longitudinal size of the Al3Ti particle groups is close to that of initial Al3Ti particles with 4-pass ECAP specimen. These distribution behaviors of the Al3Ti particle can be explained by plastic flow of α-Al matrix. Finally, it is concluded that distribution of Al3Ti particle in Al-Al3Ti alloy by ECAP is controlled by plastic deformation of α-Al matrix.

Enhancement of Strength and Ductility of Mg96Zn2Y2 Rolled Sheet by Controlling Structure and Plastic Deformation

NASA Astrophysics Data System (ADS)

Noda, Masafumi; Kawamura, Yoshihito; Sakurai, Hiroshi; Funami, Kunio

Mg-Zn-Y alloys are well known to possess greatly enhanced strength during plastic deformation because of the presence of kink bands in the LPSO phase and refinement of the grains of the alpha Mg phase. On the other hand, Mg-rare earth (RE) and Mg-Zn-RE alloys with a long period stacking order (LPSO) phase show a high tensile yield strength when subjected to an extrusion process but it is not known whether the LPSO and alpha Mg phases develop during plastic deformation. We examined the effect of the finely dispersed LPSO phase and the alpha Mg phase on the development of high strength in sheets of Mg96Zn2Y2 subjected to a few passes of rolling. The mechanical properties and thermal stability of the alloy were also investigated. The tensile yield strength of rolled sheets of Mg96Zn2Y2 was 360 MPa and its elongation was 5% when the material was subjected to thermomechanically controlled processing at 673 K with a four-pass rolling schedule. However, the tensile yield strength decreased and the elongation increased at annealing temperature of 623 K or above, because of the presence of grain growth in the alpha Mg phase and the restoration of kink bands in the LPSO phase.

Monitoring of landslide deformation based on the coherent targets of high resolution InSAR data

NASA Astrophysics Data System (ADS)

Fan, Jinghui; Xia, Ye; Zhao, Hongli; Li, Man; Wang, Yi; Guo, Xiaofang; Tu, Pengfei; Liu, Guang; Lin, Hao

2014-05-01

Landslides are a kind of typical natural disaster in China, which pose serious threats to civil lives, property and living environment. Therefore, the identification, monitoring and prevention of landslides have been considered as a long-term geological work for the public welfare. In this article, 8 TerraSAR-X high resolution strip-map mode images, acquired in the period from January to March 2012 and covering Fanjinping landslide in Zigui county, Hubei province, were used to test the usability in monitoring the deformation of single landslide. The results of two-pass DInSAR sketched the region and the shape of the deformation field of Fanjiaping landslide. Corner reflectors' linear deformation rate using CRInSAR method could be approximately validated by the in-situ GPS measurements. From the coherent pixels' linear deformation rate map, it was inferred that the deformation could be more obvious in the tail of the Muyubao landslide while the lowest frontier of this landslide might prevent the slide. Due to its shorter revisiting period and high bandwidth,,the high resolution TerraSAR-X images can keep better coherence than previous satellite SAR data in the test area and provide basic guarantee to monitor the deformation of single landslides.

Dynamic Deformation of ETNA Volcano Observed by GPS and SAR Interferometry

NASA Technical Reports Server (NTRS)

Lundgren, P.; Rosen, P.; Webb, F.; Tesauro, M.; Lanari, R.; Sansosi, E.; Puglisi, G.; Bonforte, A.; Coltelli, M.

1999-01-01

Synthetic aperture radar (SAR) interferometry and GPS have shown that during the quiescent period from 1993-1995 Mt. Etna volcano, Italy, inflated. Since the initiation of eruptive activity since late 1995 the deformation has been more contentious. We will explore the detailed deformation during the period from 1995-1996 spanning the late stages of inflation and the beginning of eruptive activity. We use SAR interferometry and GPS data to measure the volcano deformation. We invert the observed deformation for both simple point source. le crack elastic sources or if warranted for a spheroidal pressure So In particular, we will examine the evolution of the inflation and the transition to a lesser deflation observed at the end of 1995. We use ERS-1/2 SAR data from both ascending and descending passes to allow for dense temporal 'sampling of the deformation and to allow us to critically assess atmospheric noise. Preliminary results from interferometry suggest that the inflation rate accelerated prior to resumption of activity in 1995, while GPS data suggest a more steady inflation with some fluctuation following the start of activity. This study will compare and contrast the interferometric SAR and GPS results and will address the strengths and weaknesses of each technique towards volcano deformation studies.

Respiratory effort correction strategies to improve the reproducibility of lung expansion measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Kaifang; Reinhardt, Joseph M.; Christensen, Gary E.

2013-12-15

Purpose: Four-dimensional computed tomography (4DCT) can be used to make measurements of pulmonary function longitudinally. The sensitivity of such measurements to identify change depends on measurement uncertainty. Previously, intrasubject reproducibility of Jacobian-based measures of lung tissue expansion was studied in two repeat prior-RT 4DCT human acquisitions. Difference in respiratory effort such as breathing amplitude and frequency may affect longitudinal function assessment. In this study, the authors present normalization schemes that correct ventilation images for variations in respiratory effort and assess the reproducibility improvement after effort correction.Methods: Repeat 4DCT image data acquired within a short time interval from 24 patients priormore » to radiation therapy (RT) were used for this analysis. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. In addition to computing the ventilation maps from end expiration to end inspiration, the authors investigated the effort normalization strategies using other intermediated inspiration phases upon the principles of equivalent tidal volume (ETV) and equivalent lung volume (ELV). Scatter plots and mean square error of the repeat ventilation maps and the Jacobian ratio map were generated for four conditions: no effort correction, global normalization, ETV, and ELV. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2 mm distance-to-agreement and 5% ventilation difference.Results: The pattern of regional pulmonary ventilation changes as lung volume changes. All effort correction strategies improved reproducibility when changes in respiratory effort were greater than 150 cc (p < 0.005 with regard to the gamma pass rate). Improvement of reproducibility was correlated with respiratory effort difference (R = 0.744 for ELV in the cohort with tidal volume difference greater than 100 cc). In general for all subjects, global normalization, ETV and ELV significantly improved reproducibility compared to no effort correction (p = 0.009, 0.002, 0.005 respectively). When tidal volume difference was small (less than 100 cc), none of the three effort correction strategies improved reproducibility significantly (p = 0.52, 0.46, 0.46 respectively). For the cohort (N = 13) with tidal volume difference greater than 100 cc, the average gamma pass rate improves from 57.3% before correction to 66.3% after global normalization, and 76.3% after ELV. ELV was found to be significantly better than global normalization (p = 0.04 for all subjects, and p = 0.003 for the cohort with tidal volume difference greater than 100 cc).Conclusions: All effort correction strategies improve the reproducibility of the authors' pulmonary ventilation measures, and the improvement of reproducibility is highly correlated with the changes in respiratory effort. ELV gives better results as effort difference increase, followed by ETV, then global. However, based on the spatial and temporal heterogeneity in the lung expansion rate, a single scaling factor (e.g., global normalization) appears to be less accurate to correct the ventilation map when changes in respiratory effort are large.« less

cAMP-Signalling Regulates Gametocyte-Infected Erythrocyte Deformability Required for Malaria Parasite Transmission

PubMed Central

Thompson, Eloise; Breil, Florence; Lorthiois, Audrey; Dupuy, Florian; Cummings, Ross; Duffier, Yoann; Corbett, Yolanda; Mercereau-Puijalon, Odile; Vernick, Kenneth; Taramelli, Donatella; Baker, David A.; Langsley, Gordon; Lavazec, Catherine

2015-01-01

Blocking Plasmodium falciparum transmission to mosquitoes has been designated a strategic objective in the global agenda of malaria elimination. Transmission is ensured by gametocyte-infected erythrocytes (GIE) that sequester in the bone marrow and at maturation are released into peripheral blood from where they are taken up during a mosquito blood meal. Release into the blood circulation is accompanied by an increase in GIE deformability that allows them to pass through the spleen. Here, we used a microsphere matrix to mimic splenic filtration and investigated the role of cAMP-signalling in regulating GIE deformability. We demonstrated that mature GIE deformability is dependent on reduced cAMP-signalling and on increased phosphodiesterase expression in stage V gametocytes, and that parasite cAMP-dependent kinase activity contributes to the stiffness of immature gametocytes. Importantly, pharmacological agents that raise cAMP levels in transmissible stage V gametocytes render them less deformable and hence less likely to circulate through the spleen. Therefore, phosphodiesterase inhibitors that raise cAMP levels in P. falciparum infected erythrocytes, such as sildenafil, represent new candidate drugs to block transmission of malaria parasites. PMID:25951195

Monitoring on Xi'an ground fissures deformation with TerraSAR-X data

USGS Publications Warehouse

Zhao, C.; Zhang, Q.; Zhu, W.; Lu, Z.

2012-01-01

Owing to the fine resolution of TerraSAR-X data provided since 2007, this paper applied 6 TerraSAR data (strip mode) during 3rd Dec. 2009 to 23rd Mar. 2010 to detect and monitor the active fissures over Xi'an region. Three themes have been designed for high precision detection and monitoring of Xi'an-Chang'an fissures, as small baseline subsets (SBAS) to test the atmospheric effects of differential interferograms pair stepwise, 2-pass differential interferogram with very short baseline perpendicular to generate the whole deformation map with 44 days interval, and finally, corner reflector (CR) technique was used to closely monitor the relative deformation time series between two CRs settled crossing two ground fissures. Results showed that TerraSAR data are a good choice for small-scale ground fissures detection and monitoring, while special considerations should be taken for their great temporal and baseline decorrelation. Secondly, ground fissures in Xi'an were mostly detected at the joint section of stable and deformable regions. Lastly, CR-InSAR had potential ability to monitor relative deformation crossing fissures with millimeter precision.

Controls of repeating earthquakes' location from a- and b- values imaging

NASA Astrophysics Data System (ADS)

Chen, K. H.; Kawamura, M.

2017-12-01

The locations where creeping and locked fault areas abut have commonly found to be delineated by the foci of small repeating earthquakes (REs). REs not only represent the finer structure of high creep-rate location, they also function as fault slip-rate indicators. Knowledge of the expected location of REs therefore, is crucial for fault deformation monitoring and assessment of earthquake potential. However, a precise description of factors determining REs locations is lacking. To explore where earthquakes tend to recur, we statistically investigated repeating earthquake catalogs and background seismicity from different regions including six fault segments in California and Taiwan. We show that the location of repeating earthquakes can be mapped using the spatial distribution of the seismic a- and b-values obtained from the background seismicity. Molchan's error diagram statistically confirmed that repeating earthquakes occur within areas with high a-values (2.8-3.8) and high b-values (0.9-1.1) on both strike-slip and thrust fault segments. However, no significant association held true for fault segments with more complicated geometry or for wider areas with a complex fault network. The productivity of small earthquakes responsible for high a- and b-values may thus be the most important factor controlling the location of repeating earthquakes. We hypothesize that, given that the deformation conditions within a fault zone are suitable for a planar fault plane, the location of repeating earthquakes can be best described by a-value 3 and b-value 1. This feature of a- and b-values may be useful for foresee the location of REs for measuring creep rate at depth. Further investigation of REs-rich areas may allow testing of this hypothesis.

Thermally-assisted Magma Emplacement Explains Restless Calderas.

PubMed

Amoruso, Antonella; Crescentini, Luca; D'Antonio, Massimo; Acocella, Valerio

2017-08-11

Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei caldera, Italy. Campi Flegrei experienced at least 4 major unrest episodes in the last decades. Our results indicate that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust. Our thermal models show that this repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth ~3 ka before the last eruption. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks. Our model of thermally-assisted unrest may have a wider applicability, possibly explaining also the dynamics of other restless calderas.

Microstructural evolution of bainitic steel severely deformed by equal channel angular pressing.

PubMed

Nili-Ahmadabadi, M; Haji Akbari, F; Rad, F; Karimi, Z; Iranpour, M; Poorganji, B; Furuhara, T

2010-09-01

High Si bainitic steel has been received much of interest because of combined ultra high strength, good ductility along with high wear resistance. In this study a high Si bainitic steel (Fe-0.22C-2.0Si-3.0Mn) was used with a proper microstructure which could endure severe plastic deformation. In order to study the effect of severe plastic deformation on the microstructure and properties of bainitic steel, Equal Channel Angular Pressing was performed in two passes at room temperature. Optical, SEM and TEM microscopies were used to examine the microstructure of specimens before and after Equal Channel Angular Pressing processing. X-ray diffraction was used to measure retained austenite after austempering and Equal Channel Angular Pressing processing. It can be seen that retained austenite picks had removed after Equal Channel Angular Pressing which could attributed to the transformation of austenite to martensite during severe plastic deformation. Enhancement of hardness values by number of Equal Channel Angular Pressing confirms this idea.

Electrical-assisted double side incremental forming and processes thereof

DOEpatents

Roth, John; Cao, Jian

2014-06-03

A process for forming a sheet metal component using an electric current passing through the component is provided. The process can include providing a double side incremental forming machine, the machine operable to perform a plurality of double side incremental deformations on the sheet metal component and also apply an electric direct current to the sheet metal component during at least part of the forming. The direct current can be applied before or after the forming has started and/or be terminated before or after the forming has stopped. The direct current can be applied to any portion of the sheet metal. The electrical assistance can reduce the magnitude of force required to produce a given amount of deformation, increase the amount of deformation exhibited before failure and/or reduce any springback typically exhibited by the sheet metal component.

Sumatra-Andaman Megathrust Earthquake Slip: Insights From Mechanical Modeling of ICESat Surface Deformation Measurements

NASA Astrophysics Data System (ADS)

Harding, D. J.; Miuller, J. R.

2005-12-01

Modeling the kinematics of the 2004 Great Sumatra-Andaman earthquake is limited in the northern two-thirds of the rupture zone by a scarcity of near-rupture geodetic deformation measurements. Precisely repeated Ice, Cloud, and Land Elevation Satellite (ICESat) profiles across the Andaman and Nicobar Islands provide a means to more fully document the spatial pattern of surface vertical displacements and thus better constrain geomechanical modeling of the slip distribution. ICESat profiles that total ~45 km in length cross Car Nicobar, Kamorta, and Katchall in the Nicobar chain. Within the Andamans, the coverage includes ~350 km on North, Central, and South Andaman Islands along two NNE and NNW-trending profiles that provide elevations on both the east and west coasts of the island chain. Two profiles totaling ~80 km in length cross South Sentinel Island, and one profile ~10 km long crosses North Sentinel Island. With an average laser footprint spacing of 175 m, the total coverage provides over 2700 georeferenced surface elevations measurements for each operations period. Laser backscatter waveforms recorded for each footprint enable detection of forest canopy top and underlying ground elevations with decimeter vertical precision. Surface elevation change is determined from elevation profiles, acquired before and after the earthquake, that are repeated with a cross-track separation of less than 100 m by precision pointing of the ICESat spacecraft. Apparent elevation changes associated with cross-track offsets are corrected according to local slopes calculated from multiple post-earthquake repeated profiles. The surface deformation measurements recorded by ICESat are generally consistent with the spatial distribution of uplift predicted by a preliminary slip distribution model. To predict co-seismic surface deformation, we apply a slip distribution, derived from the released energy distribution computed by Ishii et al. (2005), as the displacement discontinuity boundary condition on the Sumatra-Andaman subduction interface fault. The direction of slip on the fault surface is derived from the slip directions computed by Tsai et al. (in review) for centroid moment tensor focal mechanisms spatially distributed along the rupture. The slip model will be refined to better correspond to the observed surface deformation as additional results from the ICESat profiles become available.

UAVSAR Instrument: Current Operations and Planned Upgrades

NASA Technical Reports Server (NTRS)

Lou, Yunling; Hensley, Scott; Chao, Roger; Chapin, Elaine; Heavy, Brandon; Jones, Cathleen; Miller, Timothy; Naftel, Chris; Fratello, David

2011-01-01

The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) instrument is a pod-based Lband polarimetric synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. This instrument is currently installed on the NASA Gulfstream- III (G-III) aircraft with precision real-time Global Positioning System (GPS) and a sensor-controlled flight management system for precision repeat-pass data acquisitions. UAVSAR has conducted engineering and preliminary science data flights since October 2007 on the G-III. We are porting the radar to the Global Hawk Unmanned Airborne Vehicle (UAV) to enable long duration/long range data campaigns. We plan to install two radar pods (each with its own active array antenna) under the wings of the Global Hawk to enable the generation of precision topographic maps and single pass polarimetric-interferometry (SPI) providing vertical structure of ice and vegetation. Global Hawk's range of 8000 nm will enable regional surveys with far fewer sorties as well as measurements of remote locations without the need for long and complicated deployments. We are also developing P-band polarimetry and Ka-band single-pass interferometry capabilities on UAVSAR by replacing the radar antenna and front-end electronics to operate at these

System and method for chromatography and electrophoresis using circular optical scanning

DOEpatents

Balch, Joseph W.; Brewer, Laurence R.; Davidson, James C.; Kimbrough, Joseph R.

2001-01-01

A system and method is disclosed for chromatography and electrophoresis using circular optical scanning. One or more rectangular microchannel plates or radial microchannel plates has a set of analysis channels for insertion of molecular samples. One or more scanning devices repeatedly pass over the analysis channels in one direction at a predetermined rotational velocity and with a predetermined rotational radius. The rotational radius may be dynamically varied so as to monitor the molecular sample at various positions along a analysis channel. Sample loading robots may also be used to input molecular samples into the analysis channels. Radial microchannel plates are built from a substrate whose analysis channels are disposed at a non-parallel angle with respect to each other. A first step in the method accesses either a rectangular or radial microchannel plate, having a set of analysis channels, and second step passes a scanning device repeatedly in one direction over the analysis channels. As a third step, the scanning device is passed over the analysis channels at dynamically varying distances from a centerpoint of the scanning device. As a fourth step, molecular samples are loaded into the analysis channels with a robot.

Dose coverage calculation using a statistical shape model—applied to cervical cancer radiotherapy

NASA Astrophysics Data System (ADS)

Tilly, David; van de Schoot, Agustinus J. A. J.; Grusell, Erik; Bel, Arjan; Ahnesjö, Anders

2017-05-01

A comprehensive methodology for treatment simulation and evaluation of dose coverage probabilities is presented where a population based statistical shape model (SSM) provide samples of fraction specific patient geometry deformations. The learning data consists of vector fields from deformable image registration of repeated imaging giving intra-patient deformations which are mapped to an average patient serving as a common frame of reference. The SSM is created by extracting the most dominating eigenmodes through principal component analysis of the deformations from all patients. The sampling of a deformation is thus reduced to sampling weights for enough of the most dominating eigenmodes that describe the deformations. For the cervical cancer patient datasets in this work, we found seven eigenmodes to be sufficient to capture 90% of the variance in the deformations of the, and only three eigenmodes for stability in the simulated dose coverage probabilities. The normality assumption of the eigenmode weights was tested and found relevant for the 20 most dominating eigenmodes except for the first. Individualization of the SSM is demonstrated to be improved using two deformation samples from a new patient. The probabilistic evaluation provided additional information about the trade-offs compared to the conventional single dataset treatment planning.

QuakeSim 2.0

NASA Technical Reports Server (NTRS)

Donnellan, Andrea; Parker, Jay W.; Lyzenga, Gregory A.; Granat, Robert A.; Norton, Charles D.; Rundle, John B.; Pierce, Marlon E.; Fox, Geoffrey C.; McLeod, Dennis; Ludwig, Lisa Grant

2012-01-01

QuakeSim 2.0 improves understanding of earthquake processes by providing modeling tools and integrating model applications and various heterogeneous data sources within a Web services environment. QuakeSim is a multisource, synergistic, data-intensive environment for modeling the behavior of earthquake faults individually, and as part of complex interacting systems. Remotely sensed geodetic data products may be explored, compared with faults and landscape features, mined by pattern analysis applications, and integrated with models and pattern analysis applications in a rich Web-based and visualization environment. Integration of heterogeneous data products with pattern informatics tools enables efficient development of models. Federated database components and visualization tools allow rapid exploration of large datasets, while pattern informatics enables identification of subtle, but important, features in large data sets. QuakeSim is valuable for earthquake investigations and modeling in its current state, and also serves as a prototype and nucleus for broader systems under development. The framework provides access to physics-based simulation tools that model the earthquake cycle and related crustal deformation. Spaceborne GPS and Inter ferometric Synthetic Aperture (InSAR) data provide information on near-term crustal deformation, while paleoseismic geologic data provide longerterm information on earthquake fault processes. These data sources are integrated into QuakeSim's QuakeTables database system, and are accessible by users or various model applications. UAVSAR repeat pass interferometry data products are added to the QuakeTables database, and are available through a browseable map interface or Representational State Transfer (REST) interfaces. Model applications can retrieve data from Quake Tables, or from third-party GPS velocity data services; alternatively, users can manually input parameters into the models. Pattern analysis of GPS and seismicity data has proved useful for mid-term forecasting of earthquakes, and for detecting subtle changes in crustal deformation. The GPS time series analysis has also proved useful as a data-quality tool, enabling the discovery of station anomalies and data processing and distribution errors. Improved visualization tools enable more efficient data exploration and understanding. Tools provide flexibility to science users for exploring data in new ways through download links, but also facilitate standard, intuitive, and routine uses for science users and end users such as emergency responders.

Experimental and numerical investigation on laser-assisted bending of pre-loaded metal plate

NASA Astrophysics Data System (ADS)

Nowak, Zdzisław; Nowak, Marcin; Widłaszewski, Jacek; Kurp, Piotr

2018-01-01

The laser forming technique has an important disadvantage, which is the limitation of plastic deformation generated by a single laser beam pass. To increase the plastic deformation it is possible to apply external forces in the laser forming process. In this paper, we investigate the influence of external pre-loads on the laser bending of steel plate. The pre-loads investigated generate bending towards the laser beam. The thermal, elastic-plastic analysis is performed using the commercial nonlinear finite element analysis package ABAQUS. The focus of the paper is to identify how this pattern of the pre-load influence the final bend angle of the plate.

Generation of large-scale forest height and disturbance maps through the fusion of NISAR and GEDI along with TanDEM-X/L

NASA Astrophysics Data System (ADS)

Lei, Y.; Treuhaft, R. N.; Siqueira, P.; Torbick, N.; Lucas, R.; Keller, M. M.; Schmidt, M.; Ducey, M. J.; Salas, W.

2017-12-01

Large-scale products of forest height and disturbance are essential for understanding the global carbon distribution as well as its changes in response to natural events and human activities. Regarding this scientific need, both NASA's GEDI and NASA-ISRO's NISAR are going to be launched in the 2018-2021 timeframe in parallel with DLR's current TanDEM-X and/or the proposed TanDEM-L, which provides a lot of potential for global ecosystem mapping. A new simple and efficient method of forest height mapping has been developed for combining spaceborne repeat-pass InSAR and lidar missions (e.g. NISAR and GEDI) which estimates temporal decorrelation parameters of repeat-pass InSAR and uses the lidar data as training samples. An open-access Python-based software has been developed for automated processing. As a result, a mosaic of forest height was generated for US states of Maine and New Hampshire (11.6 million ha) using JAXA's ALOS-1 and ALOS-2 HV-pol InSAR data and a small piece of lidar training samples (44,000 ha) with the height estimates validated against airborne lidar and field inventory data over both flat and mountainous areas. In addition, through estimating and correcting for the temporal decorrelation effects in the spaceborne repeat-pass InSAR coherence data and also utilizing the spaceborne single-pass InSAR phase data, forest disturbance such as selective logging is not only detected but also quantified in subtropical forests of Australia using ALOS-1 HH-pol InSAR data (validated against NASA's Landsat), as well as in tropics of Brazil using TanDEM-X and ALOS-2 HH-pol InSAR data (validated against field inventory data). The operational simplicity and efficiency make these methods a potential observing/processing prototype for the fusion of NISAR, GEDI and TanDEM-X/L.

Binary classification of items of interest in a repeatable process

DOEpatents

Abell, Jeffrey A; Spicer, John Patrick; Wincek, Michael Anthony; Wang, Hui; Chakraborty, Debejyo

2015-01-06

A system includes host and learning machines. Each machine has a processor in electrical communication with at least one sensor. Instructions for predicting a binary quality status of an item of interest during a repeatable process are recorded in memory. The binary quality status includes passing and failing binary classes. The learning machine receives signals from the at least one sensor and identifies candidate features. Features are extracted from the candidate features, each more predictive of the binary quality status. The extracted features are mapped to a dimensional space having a number of dimensions proportional to the number of extracted features. The dimensional space includes most of the passing class and excludes at least 90 percent of the failing class. Received signals are compared to the boundaries of the recorded dimensional space to predict, in real time, the binary quality status of a subsequent item of interest.

Introduction of a deformable x-ray CT polymer gel dosimetry system

NASA Astrophysics Data System (ADS)

Maynard, E.; Heath, E.; Hilts, M.; Jirasek, A.

2018-04-01

This study introduces the first 3D deformable dosimetry system based on x-ray computed tomography (CT) polymer gel dosimetry and establishes the setup reproducibility, deformation characteristics and dose response of the system. A N-isopropylacrylamide (NIPAM)-based gel formulation optimized for x-ray CT gel dosimetry was used, with a latex balloon serving as the deformable container and low-density polyethylene and polyvinyl alcohol providing additional oxygen barrier. Deformable gels were irradiated with a 6 MV calibration pattern to determine dosimetric response and a dosimetrically uniform plan to determine the spatial uniformity of the response. Wax beads were added to each gel as fiducial markers to track the deformation and setup of the gel dosimeters. From positions of the beads on CT images the setup reproducibility and the limits and reproducibility of gel deformation were determined. Comparison of gel measurements with Monte Carlo dose calculations found excellent dosimetric accuracy, comparable to that of an established non-deformable dosimetry system, with a mean dose discrepancy of 1.5% in the low-dose gradient region and a gamma pass rate of 97.9% using a 3%/3 mm criterion. The deformable dosimeter also showed good overall spatial dose uniformity throughout the dosimeter with some discrepancies within 20 mm of the edge of the container. Tracking of the beads within the dosimeter found that sub-millimetre setup accuracy is achievable with this system. The dosimeter was able to deform and relax when externally compressed by up to 30 mm without sustaining any permanent damage. Internal deformations in 3D produced average marker movements of up to 12 mm along the direction of compression. These deformations were also shown to be reproducible over 100 consecutive deformations. This work has established several important characteristics of a new deformable dosimetry system which shows promise for future clinical applications, including the validation of deformable dose accumulation algorithms.

Structurally controlled 'teleconnection' of large-scale mass wasting (Eastern Alps)

NASA Astrophysics Data System (ADS)

Ostermann, Marc; Sanders, Diethard

2015-04-01

In the Brenner Pass area (Eastern Alps) , closely ahead of the most northward outlier ('nose') of the Southern-Alpine continental indenter, abundant deep-seated gravitational slope deformations and a cluster of five post-glacial rockslides are present. The indenter of roughly triangular shape formed during Neogene collision of the Southern-Alpine basement with the Eastern-Alpine nappe stack. Compression by the indenter activated a N-S striking, roughly W-E extensional fault northward of the nose of the indenter (Brenner-normal fault; BNF), and lengthened the Eastern-Alpine edifice along a set of major strike-slip faults. These fault zones display high seismicity, and are the preferred locus of catastrophic rapid slope failures (rockslides, rock avalanches) and deep-seated gravitational slope deformations. The seismotectonic stress field, earthquake activity, and structural data all indicate that the South-Alpine indenter still - or again - exerts compression; in consequence, the northward adjacent Eastern Alps are subject mainly to extension and strike-slip. For the rockslides in the Brenner Pass area, and for the deep-seated gravitational slope deformations, the fault zones combined with high seismic activity predispose massive slope failures. Structural data and earthquakes mainly record ~W-E extension within an Eastern Alpine basement block (Oetztal-Stubai basement complex) in the hangingwall of the BNF. In the Northern Calcareous Alps NW of the Oetztal-Stubai basement complex, dextral faults provide defacement scars for large rockfalls and rockslides. Towards the West, these dextral faults merge into a NNW-SSE striking sinistral fault zone that, in turn, displays high seismic activity and is the locus of another rockslide cluster (Fern Pass cluster; Prager et al., 2008). By its kinematics dictated by the South-Alpine indenter, the relatively rigid Oetztal-Stubai basement block relays faulting and associated mass-wasting over a N-S distance of more than 60 kilometers - from the Brenner Pass area located along the crestline of the Alps to mount Zugspitze near the northern fringe of the Northern Calcareous Alps. Major fault zones and intercalated rigid blocks thus can 'teleconnect' zones of preferred mass-wasting over large lateral distances in orogens. Reference: Prager, C., Zangerl, C., Patzelt, G., Brandner, R., 2008. Age distribution of fossil landslides in the Tyrol (Austria) and its surrounding areas. Natural Hazards and Earth System Science 8, 377-407.

Post Deformation at Room and Cryogenic Temperature Cooling Media on Severely Deformed 1050-Aluminum

NASA Astrophysics Data System (ADS)

Khorrami, M. Sarkari; Kazeminezhad, M.

2018-03-01

The annealed 1050-aluminum sheets were initially subjected to the severe plastic deformation through two passes of constrained groove pressing (CGP) process. The obtained specimens were post-deformed by friction stir processing at room and cryogenic temperature cooling media. The microstructure evolutions during mentioned processes in terms of grain structure, misorientation distribution, and grain orientation spread (GOS) were characterized using electron backscattered diffraction. The annealed sample contained a large number of "recrystallized" grains and relatively large fraction (78%) of high-angle grain boundaries (HAGBs). When CGP process was applied on the annealed specimen, the elongated grains with interior substructure were developed, which was responsible for the formation of 80% low-angle grain boundaries. The GOS map of the severely deformed specimen manifested the formation of 43% "distorted" and 51% "substructured" grains. The post deformation of severely deformed aluminum at room temperature led to the increase in the fraction of HAGBs from 20 to 60%. Also, it gave rise to the formation of "recrystallized" grains with the average size of 13 μm, which were coarser than the grains predicted by Zener-Hollomon parameter. This was attributed to the occurrence of appreciable grain growth during post deformation. In the case of post deformation at cryogenic temperature cooling medium, the grain size was decreased, which was in well agreement with the predicted grain size. The cumulative distribution of misorientation was the same for both processing routes. Mechanical properties characterizations in terms of nano-indentation and tensile tests revealed that the post deformation process led to the reduction in hardness, yield stress, and ultimate tensile strength of the severely deformed aluminum.

Characteristics of surface modified Ti-6Al-4V alloy by a series of YAG laser irradiation

NASA Astrophysics Data System (ADS)

Zeng, Xian; Wang, Wenqin; Yamaguchi, Tomiko; Nishio, Kazumasa

2018-01-01

In this study, a double-layer Ti (C, N) film was successfully prepared on Ti-6Al-4V alloy by a series of YAG laser irradiation in nitrogen atmosphere, aiming at improving the wear resistance. The effects of laser irradiation pass upon surface chemical composition, microstructures and hardness were investigated. The results showed that the surface chemicals were independent from laser irradiation pass, which the up layer of film was a mixture of TiN and TiC0.3N0.7, and the down layer was nitrogen-rich α-Ti. Both the surface roughness and hardness increased as raising the irradiation passes. However, surface deformation and cracks happened in the case above 3 passes' irradiation. The wear resistance of laser modified sample by 3 passes was improved approximately by 37 times compared to the as received substrate. Moreover, the cytotoxic V ion released from laser modified sample was less than that of as received Ti-6Al-4V alloy in SBF, suggesting the potentiality of a new try to modify the sliding part of Ti-based hard tissue implants in future biomedical application.

49 CFR 178.811 - Bottom lift test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... passing the test. For all IBC design types designed to be lifted from the base, there may be no permanent deformation which renders the IBC unsafe for transportation and no loss of contents. [Amdt. 178-103, 59 FR... bottom lift test. The IBC must be loaded to 1.25 times its maximum permissible gross mass, the load being...

Finite Element Modeling of Dieless Tube Drawing of Strain Rate Sensitive Material with Coupled Thermo-Mechanical Analysis

NASA Astrophysics Data System (ADS)

Furushima, Tsuyoshi; Sakai, Takashi; Manabe, Ken-ichi

2004-06-01

Dieless drawing is a unique deformation process without conventional dies, which can achieve a great reduction of wire and tube metals in single pass by means of local heating and cooling approach. In this study, for microtube forming, the dieless drawing process applying superplastic behavior was analyzed by finite element method (FEM) in order to clarify the effect of dieless tube drawing conditions such as tensile speed, moving speed of heating and cooling system, and material properties on deformation behavior of the tube. In the calculation, the material properties were dealt in a special subroutine, whose constitutive equation was defined as σ = Kɛnɛ˙m, and was linked to the solver. A coupled thermo-mechanical analysis was performed for the dieless tube drawing using the FEM. In the thermal analysis of dieless tube drawing, heat transfer was introduced to calculate the heat flux between heating coil and tube surface, and heat conduction in a tube. The influence of dieless tube drawing conditions on deformation behavior was clarified. As a result, for the strain rate sensitive material, the maximum reduction of area and the minimum outer diameter in single pass attain to 90.9% and 2.56mm, respectively. From the result, it is concluded that the dieless tube drawing is essential to produce an extrafine microtube by reason of keeping cylindrical tube diameter ratio constant with extremely high reduction.

Observations of the Sea Ice Cover Using Satellite Radar Interferometry

NASA Technical Reports Server (NTRS)

Kwok, Ronald

1995-01-01

The fringes observed in repeat pass interferograms are expressions of surface relief and relative displacements. The limiting condition in the application of spaceborne radar interferometry to the remote sensing of the sea ice cover is the large magnitude of motion between repeat passes. The translation and rotation of ice floes tend to decorrelate the observations rendering radar interferometry ineffective. In our study, we have located three images in the high Arctic during a period when there was negligible motion between repeat observations. The fringes obtained from these images show a wealth of information about the sea ice cover which is important in atmosphere-ice interactions and sea ice mechanics. These measurements provide the first detailed remote sensing view of the sea ice cover. Ridges can be observed and their heights estimated if the interferometric baseline allows. We have observed ridges with heights greater than 4m. The variability in the phase measurements over an area provides an indication of the large scale roughness. Relative centimetric displacements between rigid ice floes have been observed. We illustrate these observations with examples extracted from the interferograms formed from this set of ERS-1 SAR images.

An evaluation of processing InSAR Sentinel-1A/B data for correlation of mining subsidence with mining induced tremors in the Upper Silesian Coal Basin (Poland)

NASA Astrophysics Data System (ADS)

Krawczyk, Artur; Grzybek, Radosław

2018-01-01

The Satellite Radar Interferometry is one of the common methods that allow to measure the land subsidence caused by the underground black coal excavation. The interferometry images processed from the repeat-pass Synthetic Aperture Radar (SAR) systems give the spatial image of the terrain subjected to the surface subsidence over mining areas. Until now, the InSAR methods using data from the SAR Systems like ERS-1/ERS-2 and Envisat-1 were limited to a repeat-pass cycle of 35-day only. Recently, the ESA launched Sentinel-1A and 1B, and together they can provide the InSAR coverage in a 6-day repeat cycle. The studied area was the Upper Silesian Coal Basin in Poland, where the underground coal mining causes continuous subsidence of terrain surface and mining tremors (mine-induced seismicity). The main problem was with overlapping the subsidence caused by the mining exploitation with the epicentre tremors. Based on the Sentinel SAR images, research was done in regard to the correlation between the short term ground subsidence range border and the mine-induced seismicity epicentres localisation.

Microfluidics-based, time-resolved mechanical phenotyping of cells using high-speed imaging

NASA Astrophysics Data System (ADS)

Belotti, Yuri; Conneely, Michael; Huang, Tianjun; McKenna, Stephen; Nabi, Ghulam; McGloin, David

2017-07-01

We demonstrate a single channel hydrodynamic stretching microfluidic device that relies on high-speed imaging to allow repeated dynamic cell deformation measurements. Experiments on prostate cancer cells suggest richer data than current approaches.

Deformation Monitoring of Waste-Rock-Backfilled Mining Gob for Ground Control

PubMed Central

Zhao, Tongbin; Zhang, Yubao; Zhang, Zhenyu; Li, Zhanhai; Ma, Shuqi

2017-01-01

Backfill mining is an effective option to mitigate ground subsidence, especially for mining under surface infrastructure, such as buildings, dams, rivers and railways. To evaluate its performance, continual long-term field monitoring of the deformation of backfilled gob is important to satisfy strict public scrutiny. Based on industrial Ethernet, a real-time monitoring system was established to monitor the deformation of waste-rock-backfilled gob at −700 m depth in the Tangshan coal mine, Hebei Province, China. The designed deformation sensors, based on a resistance transducer mechanism, were placed vertically between the roof and floor. Stress sensors were installed above square steel plates that were anchored to the floor strata. Meanwhile, data cables were protected by steel tubes in case of damage. The developed system continually harvested field data for three months. The results show that industrial Ethernet technology can be reliably used for long-term data transmission in complicated underground mining conditions. The monitoring reveals that the roof subsidence of the backfilled gob area can be categorized into four phases. The bearing load of the backfill developed gradually and simultaneously with the deformation of the roof strata, and started to be almost invariable when the mining face passed 97 m. PMID:28475168

Deformation Monitoring of Waste-Rock-Backfilled Mining Gob for Ground Control.

PubMed

Zhao, Tongbin; Zhang, Yubao; Zhang, Zhenyu; Li, Zhanhai; Ma, Shuqi

2017-05-05

Backfill mining is an effective option to mitigate ground subsidence, especially for mining under surface infrastructure, such as buildings, dams, rivers and railways. To evaluate its performance, continual long-term field monitoring of the deformation of backfilled gob is important to satisfy strict public scrutiny. Based on industrial Ethernet, a real-time monitoring system was established to monitor the deformation of waste-rock-backfilled gob at -700 m depth in the Tangshan coal mine, Hebei Province, China. The designed deformation sensors, based on a resistance transducer mechanism, were placed vertically between the roof and floor. Stress sensors were installed above square steel plates that were anchored to the floor strata. Meanwhile, data cables were protected by steel tubes in case of damage. The developed system continually harvested field data for three months. The results show that industrial Ethernet technology can be reliably used for long-term data transmission in complicated underground mining conditions. The monitoring reveals that the roof subsidence of the backfilled gob area can be categorized into four phases. The bearing load of the backfill developed gradually and simultaneously with the deformation of the roof strata, and started to be almost invariable when the mining face passed 97 m.

A cross-shear deformation for optimizing the strength and ductility of AZ31 magnesium alloys

PubMed Central

Hamad, Kotiba; Ko, Young Gun

2016-01-01

Magnesium alloys have recently attracted great interest due their lightweight and high specific strength. However, because of their hexagonal close-packed structure, they have few active slip systems, resulting in poor ductility and high mechanical anisotropy at room temperature. In the present work, we used a cross-shear deformation imposed by a differential speed rolling (DSR) technique to improve the room temperature strength and ductility of AZ31 magnesium alloy sheets. To introduce the cross-shear deformation, the sheets were rotated 180° around their longitudinal axis between the adjacent passes of DSR. The sheets of the AZ31 alloy subjected to the cross-shear deformation showed a uniform fine microstructure (1.2 ± 0.1 μm) with weak basal textures. The fabricated sheets showed a simultaneous high ultimate tensile strength and elongation-to-failure, i.e., ~333 MPa and ~21%, respectively. These were explained based on the structural features evolved due to the cross-shear deformation by DSR. The high strength was attributed to the uniform fine microstructure, whereas the high ductility was explained based on the basal texture weakening. PMID:27406685

Estimating lava volume by precision combination of multiple baseline spaceborne and airborne interferometric synthetic aperture radar: The 1997 eruption of Okmok Volcano, Alaska

USGS Publications Warehouse

Lu, Z.; Fielding, E.; Patrick, M.R.; Trautwein, C.M.

2003-01-01

Interferometric synthetic aperture radar (InSAR) techniques are used to calculate the volume of extrusion at Okmok volcano, Alaska by constructing precise digital elevation models (DEMs) that represent volcano topography before and after the 1997 eruption. The posteruption DEM is generated using airborne topographic synthetic aperture radar (TOPSAR) data where a three-dimensional affine transformation is used to account for the misalignments between different DEM patches. The preeruption DEM is produced using repeat-pass European Remote Sensing satellite data; multiple interferograms are combined to reduce errors due to atmospheric variations, and deformation rates are estimated independently and removed from the interferograms used for DEM generation. The extrusive flow volume associated with the 1997 eruption of Okmok volcano is 0.154 ?? 0.025 km3. The thickest portion is approximately 50 m, although field measurements of the flow margin's height do not exceed 20 m. The in situ measurements at lava edges are not representative of the total thickness, and precise DEM data are absolutely essential to calculate eruption volume based on lava thickness estimations. This study is an example that demonstrates how InSAR will play a significant role in studying volcanoes in remote areas.

Atmospheric Effects on InSAR Measurements and Their Mitigation

PubMed Central

Ding, Xiao-li; Li, Zhi-wei; Zhu, Jian-jun; Feng, Guang-cai; Long, Jiang-ping

2008-01-01

Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given. PMID:27873822

Atmospheric Effects on InSAR Measurements and Their Mitigation.

PubMed

Ding, Xiao-Li; Li, Zhi-Wei; Zhu, Jian-Jun; Feng, Guang-Cai; Long, Jiang-Ping

2008-09-03

Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given.

Crustal deformation in Great California Earthquake cycles

NASA Technical Reports Server (NTRS)

Li, Victor C.; Rice, James R.

1987-01-01

A model in which coupling is described approximately through a generalized Elsasser model is proposed for computation of the periodic crustal deformation associated with repeated strike-slip earthquakes. The model is found to provide a more realistic physical description of tectonic loading than do simpler kinematic models. Parameters are chosen to model the 1857 and 1906 San Andreas ruptures, and predictions are found to be consistent with data on variations of contemporary surface strain and displacement rates as a function of distance from the 1857 and 1906 rupture traces. Results indicate that the asthenosphere appropriate to describe crustal deformation on the earthquake cycle time scale lies in the lower crust and perhaps the crust-mantle transition zone.

Transient Reactivation of a Deep-Seated Landslide by Undrained Loading Captured With Repeat Airborne and Terrestrial Lidar

NASA Astrophysics Data System (ADS)

Booth, Adam M.; McCarley, Justin; Hinkle, Jason; Shaw, Susan; Ampuero, Jean-Paul; Lamb, Michael P.

2018-05-01

Landslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three-dimensional, 1-m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide's head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by a negative dilatancy-pore pressure feedback as material deformed around basal roughness elements. Thus, landslide motion can be decoupled from external environmental forcing in cases, motivating the need to better understand internal perturbations to the stress field to predict hazards and sediment fluxes as landscapes evolve.

Dome growth at Mount Cleveland, Aleutian Arc, quantified by time-series TerraSAR-X imagery

USGS Publications Warehouse

Wang, Teng; Poland, Michael; Lu, Zhong

2016-01-01

Synthetic aperture radar imagery is widely used to study surface deformation induced by volcanic activity; however, it is rarely applied to quantify the evolution of lava domes, which is important for understanding hazards and magmatic system characteristics. We studied dome formation associated with eruptive activity at Mount Cleveland, Aleutian Volcanic Arc, in 2011–2012 using TerraSAR-X imagery. Interferometry and offset tracking show no consistent deformation and only motion of the crater rim, suggesting that ascending magma may pass through a preexisting conduit system without causing appreciable surface deformation. Amplitude imagery has proven useful for quantifying rates of vertical and areal growth of the lava dome within the crater from formation to removal by explosive activity to rebirth. We expect that this approach can be applied at other volcanoes that host growing lava domes and where hazards are highly dependent on dome geometry and growth rates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

St.John, C.M.

The SHAFT code incorporates equations to compute stresses in a shaft liner when the rock through which a shaft passes is subject to known three-dimensional states of stress or strain. The deformation modes considered are hoop deformation, axial deformation, and shear on a plane normal to the shaft axis. Interaction between the liner and the soil and rock is considered, and it is assumed that the liner is in place before loading is applied. This code is intended to be used interactively but creates a permanent record complete with necessary quality assurance information. The code has been carefully verified formore » the case of generalized plane strain, in which an arbitrary axial strain can be defined. It may also be used for plane stress analysis. Output is given in the form of stresses at selected sample points in the linear and the rock and a simple graphical representation of the distribution of stress through the liner. 12 figs., 13 tabs.« less

Effect of the tiger stripes on the deformation of Saturn's moon Enceladus

NASA Astrophysics Data System (ADS)

Souček, Ondřej; Hron, Jaroslav; Běhounková, Marie; Čadek, Ondřej

2016-07-01

Enceladus is a small icy moon of Saturn with active jets of water emanating from fractures around the south pole, informally called tiger stripes, which might be connected to a subsurface water ocean. The effect of these features on periodic tidal deformation of the moon has so far been neglected because of the difficulties associated with implementation of faults in continuum mechanics models. Here we estimate the maximum possible impact of the tiger stripes on tidal deformation and heat production within Enceladus's ice shell by representing them as narrow zones with negligible frictional and bulk resistance passing vertically through the whole ice shell. Assuming a uniform ice shell thickness of 25 km, consistent with the recent estimate of libration, we demonstrate that the faults can dramatically change the distribution of stress and strain in Enceladus's south polar region, leading to a significant increase of the heat production in this area.

Lowermost mantle anisotropy and deformation along the boundary of the African LLSVP

NASA Astrophysics Data System (ADS)

Lynner, Colton; Long, Maureen D.

2014-05-01

Shear wave splitting of SK(K)S phases is often used to examine upper mantle anisotropy. In specific cases, however, splitting of these phases may reflect anisotropy in the lowermost mantle. Here we present SKS and SKKS splitting measurements for 233 event-station pairs at 34 seismic stations that sample D″ beneath Africa. Of these, 36 pairs show significantly different splitting between the two phases, which likely reflects a contribution from lowermost mantle anisotropy. The vast majority of discrepant pairs sample the boundary of the African large low shear velocity province (LLSVP), which dominates the lower mantle structure beneath this region. In general, we observe little or no splitting of phases that have passed through the LLSVP itself and significant splitting for phases that have sampled the boundary of the LLSVP. We infer that the D″ region just outside the LLSVP boundary is strongly deformed, while its interior remains undeformed (or weakly deformed).

Plastic deformation and wear process at a surface during unlubricated sliding

NASA Technical Reports Server (NTRS)

Yamamoto, T.; Buckley, D. H.

1982-01-01

The plastic deformation and wear of a 304 stainless steel surface sliding against an aluminum oxide rider with a spherical surface (the radius of curvature: 1.3 cm) were observed by using scanning electron and optical microscopes. Experiments were conducted in a vacuum of one million Pa and in an environment of fifty thousandth Pa of chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step shaped proturbances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. The mechanism for tearing away of the surface layer from the contact area and sliding track contour is explained assuming the simplified process of material removal based on the adhesion theory for the wear of materials.

Formation mechanism of fivefold deformation twins in a face-centered cubic alloy.

PubMed

Zhang, Zhenyu; Huang, Siling; Chen, Leilei; Zhu, Zhanwei; Guo, Dongming

2017-03-28

The formation mechanism considers fivefold deformation twins originating from the grain boundaries in a nanocrystalline material, resulting in that fivefold deformation twins derived from a single crystal have not been reported by molecular dynamics simulations. In this study, fivefold deformation twins are observed in a single crystal of face-centered cubic (fcc) alloy. A new formation mechanism is proposed for fivefold deformation twins in a single crystal. A partial dislocation is emitted from the incoherent twin boundaries (ITBs) with high energy, generating a stacking fault along {111} plane, and resulting in the nucleating and growing of a twin by the successive emission of partials. A node is fixed at the intersecting center of the four different slip {111} planes. With increasing stress under the indentation, ITBs come into being close to the node, leading to the emission of a partial from the node. This generates a stacking fault along a {111} plane, nucleating and growing a twin by the continuous emission of the partials. This process repeats until the formation of fivefold deformation twins.

Formation mechanism of fivefold deformation twins in a face-centered cubic alloy

NASA Astrophysics Data System (ADS)

Zhang, Zhenyu; Huang, Siling; Chen, Leilei; Zhu, Zhanwei; Guo, Dongming

2017-03-01

The formation mechanism considers fivefold deformation twins originating from the grain boundaries in a nanocrystalline material, resulting in that fivefold deformation twins derived from a single crystal have not been reported by molecular dynamics simulations. In this study, fivefold deformation twins are observed in a single crystal of face-centered cubic (fcc) alloy. A new formation mechanism is proposed for fivefold deformation twins in a single crystal. A partial dislocation is emitted from the incoherent twin boundaries (ITBs) with high energy, generating a stacking fault along {111} plane, and resulting in the nucleating and growing of a twin by the successive emission of partials. A node is fixed at the intersecting center of the four different slip {111} planes. With increasing stress under the indentation, ITBs come into being close to the node, leading to the emission of a partial from the node. This generates a stacking fault along a {111} plane, nucleating and growing a twin by the continuous emission of the partials. This process repeats until the formation of fivefold deformation twins.

Three-dimensional deformation of orthodontic brackets

PubMed Central

Melenka, Garrett W; Nobes, David S; Major, Paul W

2013-01-01

Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire–bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are collected using a stereo microscope and two charge-coupled device cameras, and deformation of orthodontic brackets is measured using a three-dimensional digital image correlation technique. The three-dimensional deformation of orthodontic brackets will be evaluated. The repeatability of the three-dimensional digital image correlation measurement method was evaluated by performing 30 archwire rotation tests using the same bracket and archwire. Finally, five Damon 3MX and five In-Ovation R self-ligating brackets will be compared using this technique to demonstrate the effect of archwire rotation on bracket design. PMID:23762201

Three-dimensional deformation of orthodontic brackets.

PubMed

Melenka, Garrett W; Nobes, David S; Major, Paul W; Carey, Jason P

2013-01-01

Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire-bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are collected using a stereo microscope and two charge-coupled device cameras, and deformation of orthodontic brackets is measured using a three-dimensional digital image correlation technique. The three-dimensional deformation of orthodontic brackets will be evaluated. The repeatability of the three-dimensional digital image correlation measurement method was evaluated by performing 30 archwire rotation tests using the same bracket and archwire. Finally, five Damon 3MX and five In-Ovation R self-ligating brackets will be compared using this technique to demonstrate the effect of archwire rotation on bracket design.

Eight Years of Surface Deformation in the Asal-Ghoubbet Rift (Afar Depression) Observed With SAR Data

NASA Astrophysics Data System (ADS)

Doubre, C.; Peltzer, G.; Manighetti, I.; Jacques, E.

2005-12-01

The volcano-tectonic Asal-Ghoubbet rift (Djibouti) is the youngest spreading segment of the Aden oceanic ridge propagating inland into the Afar Depression. The deformation in the rift is characterized by magmatic inflation and dilatation (dyking), distributed extension, fissure opening, and normal faulting, contributing to a far field opening velocity of ~1.5 cm/yr. We use radar interferometry data acquired by the Canadian satellite Radarsat on 24-day repeat, descending passes to measure the surface deformation in a 100 km wide region centered on the rift. The data set defines 87 epochs of acquisitions distributed between 1997 and 2005. We combined the SAR data into 354 full-resolution interferograms and solved for incremental displacements between epochs using a least-square approach [Berardino et al., 2002]. The resulting line of sight displacement map time series shows the following features: - A 40 km-wide zone centered on the rift is uplifted as a dome at a steady rate. - The central rift is subsiding with respect to the north and south shoulders. The velocity field shows a marked asymmetry with faster rates occurring along the northern edge of the rift. The mean velocity of the relative movement of the subsiding inner floor with respect to the northern up-lifting shoulder reaches 7 mm/yr. - Subsidence is faster in the north half of the inner floor of the rift and is associated with episodic creep events on normal faults. These includes a slip of 16 mm on the north-dipping δ fault in 2003 and an episode of accelerated creep of 10 mm occurring in 2000 on the γ fault, which is creeping at a steady rate of 3.5 mm/yr. A northern-dipping normal fault is slipping with a mean rate of 1.4 mm/yr and accommodates also the subsidence of the northern part of the inner floor. Unlike other active faults, this one does not coincide with a topographic scarp but shows evidence of surface creep in the velocity field. - The southeastern part of F fault system is the only fault clearly active on the south side of the rift axis and shows a creep event of 9 mm in 2002. We investigate the spatial and temporal relationship between deformation events observed in the SAR data and the catalog of seismicity collected by the Djibouti Observatory and during field campaign in the winter 2000/2001. We observe that creep events are generally associated with bursts of micro-seismicity distributed in the vicinity of the fault, or with swarms of small events concentrated below the fault. These observations suggest that while the overall region is deforming in response to the steady inflation of a magmatic chamber below the central rift, the faults and dykes that accommodate the deformation at the surface are sensitive and respond rapidly to small stress changes occurring episodically within the rift.

A 3D Analysis of Rock Block Deformation and Failure Mechanics Using Terrestrial Laser Scanning

NASA Astrophysics Data System (ADS)

Rowe, Emily; Hutchinson, D. Jean; Kromer, Ryan A.; Edwards, Tom

2017-04-01

Many natural geological hazards are present along the Thompson River corridor in British Columbia, Canada, including one particularly hazardous rocky slope known as the White Canyon. Railway tracks used by Canadian National (CN) and Canadian Pacific (CP) Railway companies pass through this area at the base of the Canyon slope. The geologically complex and weathered rock face exposed at White Canyon is prone to rockfalls. With a limited ditch capacity, these falling rocks have the potential to land on the tracks and therefore increase the risk of train derailment. Since 2012, terrestrial laser scanning (TLS) data has been collected at this site on a regular basis to enable researchers at Queen's University to study these rockfalls in greater detail. In this paper, the authors present a summary of an analysis of these TLS datasets including an examination of the pre-failure deformation patterns exhibited by failed rock blocks as well as an investigation into the influence of structural constraints on the pre-failure behavior of these blocks. Aligning rockfall source zones in an early point cloud dataset to a later dataset generates a transformation matrix describing the movement of the block from one scan to the next. This process was repeated such that the motion of the block over the entire TLS data coverage period was measured. A 3D roto-translation algorithm was then used to resolve the motion into translation and rotation components (Oppikofer et al. 2009; Kromer et al. 2015). Structural information was plotted on a stereonet for further analysis. A total of 111 rockfall events exceeding a volume of 1 m3 were analyzed using this approach. The study reveals that although some rockfall source blocks blocks do not exhibit detectable levels of deformation prior to failure, others do experience cm-level translation and rotation on the order of 1 to 6 degrees before detaching from the slope. Moreover, these movements may, in some cases, be related to the discontinuity planes on the slope that were confining the block. It is concluded that rock blocks in White Canyon may be classified as one of five main failure mechanisms based on their pre-failure deformation and structure: planar slide, topple, rotation, wedge, and overhang, with overhang failures representing a large portion of rockfalls in this area. Overhang rockfalls in the White Canyon are characterized by blocks that (a) are not supported by an underlying discontinuity plane, and (b) generally do not exhibit pre-failure deformation. Though overhanging rock blocks are a structural subset of toppling failure, their behavior suggests a different mechanism of detachment. Future work will further populate the present database of rockfalls in White Canyon and will expand the study to include other sites along this corridor. The ultimate goal of this research is to establish warning thresholds based on deformation magnitudes for rockfalls in White Canyon to assist Canadian railways in better understanding and managing these slopes.

An outline of tectonic, igneous, and metamorphic events in the Goshute-Toano Range between Silver Zone Pass and White Horse Pass, Elko County, Nevada; a history of superposed contractional and extensional deformation

USGS Publications Warehouse

Ketner, Keith Brindley; Day, Warren C.; Elrick, Maya; Vaag, Myra K.; Zimmerman, Robert A.; Snee, Lawrence W.; Saltus, Richard W.; Repetski, John E.; Wardlaw, Bruce R.; Taylor, Michael E.; Harris, Anita G.

1998-01-01

Seven kinds of fault-bounded tracts are described. One of the tracts provides a good example of Mesozoic contractional folding and faulting; six exemplify various aspects of Miocene extensional faulting. Massive landslide deposits resulting from Tertiary faulting are described. Mesozoic intrusive rocks and extensive exposures of Miocene volcanic rocks are described and dated. The age ranges of stratigraphic units were based on numerous conodont collections, and ages of igneous rocks were determined by argon/argon and fission-track methods. The geologic complexity of the Goshute-Toano Range provides opportunities for many additional productive structural studies.

Environment Impact Analysis of Shield Passing Alongside Bridge Pile Platform Using Three Dimensional Numerical Simulation

NASA Astrophysics Data System (ADS)

Shang, Yanliang; Shi, Wenjun; Han, Tongyin; Qin, Zhichao; Du, Shouji

2017-10-01

The shield method has many advantages in the construction of urban subway, and has become the preferred method for the construction of urban subway tunnel. Taking Shijiazhuang metro line 3 (administrative center station - garden park station interval) Passing alongside bridge as the engineering background, double shield crossing the bridge pile foundation model was set up. The deformation and internal force of the pile foundation during the construction of the shield were analyzed. Pile stress caused by shield construction increases, but the maximum stress is less than the design strength; the maximum surface settlement caused by the construction of 10.2 mm, the results meet the requirements of construction.

Modeling of Red Blood Cells and Related Spleen Function

NASA Astrophysics Data System (ADS)

Peng, Zhangli; Pivkin, Igor; Dao, Ming

2011-11-01

A key function of the spleen is to clear red blood cells (RBCs) with abnormal mechanical properties from the circulation. These abnormal mechanical properties may be due to RBC aging or RBC diseases, e.g., malaria and sickle cell anemia. Specifically, 10% of RBCs passing through the spleen are forced to squeeze into the narrow slits between the endothelial cells, and stiffer cells which get stuck are killed and digested by macrophages. To investigate this important physiological process, we employ three different approaches to study RBCs passage through these small slits, including analytical theory, Dissipative Particle Dynamics (DPD) simulation and Multiscale Finite Element Method (MS-FEM). By applying the analytical theory, we estimate the critical limiting geometries RBCs can pass. By using the DPD method, we study the full fluid-structure interaction problem, and compute RBC deformation under different pressure gradients. By employing the MS-FEM approach, we model the lipid bilayer and the cytoskeleton as two distinct layers, and focus on the cytoskeleton deformation and the bilayer-skeleton interaction force at the molecular level. Finally the results of these three approaches are compared to each other and correlated to the experimental observations.

Network of Porosity Formed in Ultrafine-Grained Copper Produced by Equal Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Ribbe, Jens; Baither, Dietmar; Schmitz, Guido; Divinski, Sergiy V.

2009-04-01

Radiotracer experiments on diffusion of Ni63 and Rb86 in severely deformed commercially pure copper (8 passes of equal channel angular pressing) reveal unambiguously the existence of ultrafast transport paths. A fraction of these paths remains in the material even after complete recrystallization. Scanning electron microscopy and focused ion beam techniques are applied. Deep grooves are found which are related to original high-energy interfaces. In-depth sectioning near corresponding triple junctions reveals clearly multiple microvoids or microcracks caused by the severe deformation. Long-range tracer penetration over tens of micrometers proves that these submicrometer-large defects are connected by highly diffusive paths and that they appear with significant frequency.

Optimum periodicity of repeated contractile actions applied in mass transport

NASA Astrophysics Data System (ADS)

Ahn, Sungsook; Lee, Sang Joon

2015-01-01

Dynamically repeated periodic patterns are abundant in natural and artificial systems, such as tides, heart beats, stock prices, and the like. The characteristic repeatability and periodicity are expected to be optimized in effective system-specific functions. In this study, such optimum periodicity is experimentally evaluated in terms of effective mass transport using one-valve and multi-valve systems working in contractile fluid flows. A set of nanoscale gating functions is utilized, operating in nanocomposite networks through which permeates selectively pass under characteristic contractile actions. Optimized contractile periodicity exists for effective energy impartment to flow in a one-valve system. In the sequential contractile actions for a multi-valve system, synchronization with the fluid flow is critical for effective mass transport. This study provides fundamental understanding on the various repeated periodic patterns and dynamic repeatability occurring in nature and mechanical systems, which are useful for broad applications.

MO-A-BRD-05: Evaluation of Composed Lung Ventilation with 4DCT and Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, K; Bayouth, J; Reinhardt, J

Purpose: Regional pulmonary function can be derived using fourdimensional computed tomography (4DCT) combined with deformable image registration. However, only peak inhale and exhale phases have been used thus far while the lung ventilation during intermediate phases is not considered. In our previous work, we have investigated the spatiotemporal heterogeneity of lung ventilation and its dependence on respiration effort. In this study, composed ventilation is introduced using all inspiration phases and compared to direct ventilation. Both methods are evaluated against Xe-CT derived ventilation. Methods: Using an in-house tissue volume preserving deformable image registration, unlike the direct ventilation method, which computes frommore » end expiration to end inspiration, Jacobian ventilation maps were computed from one inhale phase to the next and then composed from all inspiration steps. The two methods were compared in both patients prior to RT and mechanically ventilated sheep subjects. In addition, they wereassessed for the correlation with Xe-CT derived ventilation in sheep subjects. Annotated lung landmarks were used to evaluate the accuracy of original and composed deformation field. Results: After registration, the landmark distance for composed deformation field was always higher than that for direct deformation field (0IN to 100IN average in human: 1.03 vs 1.53, p=0.001, and in sheep: 0.80 vs0.94, p=0.009), and both increased with longer phase interval. Direct and composed ventilation maps were similar in both sheep (gamma pass rate 87.6) and human subjects (gamma pass rate 71.9),and showed consistent pattern from ventral to dorsal when compared to Xe-CT derived ventilation. Correlation coefficient between Xe-CT and composed ventilation was slightly better than the direct method but not significant (average 0.89 vs 0.85, p=0.135). Conclusion: More strict breathing control in sheep subjects may explain higher similarity between direct and composed ventilation. When compared to Xe-CT ventilation, no significant difference was found for the composed method. NIH Grant: R01 CA166703.« less

Deformation relief evolution during sliding friction of Hadfield steel single crystal

NASA Astrophysics Data System (ADS)

Lychagin, D. V.; Filippov, A. V.; Novitskaya, O. S.; Kolubaev, A. V.; Sizova, O. V.

2017-12-01

The paper deals with the evolution of the deformation relief formed on lateral faces of single crystals of Hadfield steel during dry sliding friction. The use of single crystals with the predetermined orientation enables to analyze the development of shear systems subject to the duration of tribological tests. As the test duration increases, slip bands are curved and thicken in the near-surface region. After 24 hours of friction, single crystals of Hadfield steel demonstrate the maximum hardening. Afterwards, the wear process begins, which is followed by the repeated strain hardening of the specimens. After 48 hours of friction, the height of the deformation relief nearly halves on all of the three faces, as compared to that observed after 24 hours of friction. Differences in the propagation height of slip bands on the faces occur due to the uneven running-in as well as the complex involvement pattern of shear systems into the deformation process.

Horizontal ground deformation patterns and magma storage during the Puu Oo eruption of Kilauea volcano, Hawaii: episodes 22-42

USGS Publications Warehouse

Hoffmann, J.P.; Ulrich, G.E.; Garcia, M.O.

1990-01-01

Horizontal ground deformation measurements were made repeatedly with an electronic distance meter near the Puu Oo eruption site approximately perpendicular to Kilauea's east rift zone (ERZ) before and after eruptive episodes 22-42. Line lengths gradually extended during repose periods and rapidly contracted about the same amount following eruptions. The repeated extension and contraction of the measured lines are best explained by the elastic response of the country rock to the addition and subsequent eruption of magma from a local reservoir. The deformation patterns are modeled to constrain the geometry and location of the local reservoir near Puu Oo. The observed deformation is consistent with deformation patterns that would be produced by the expansion of a shallow, steeply dipping dike just uprift of Puu Oo striking parallel to the trend of the ERZ. The modeled dike is centered about 800 m uprift of Puu Oo. Its top is at a depth of 0.4 km, its bottom at about 2.9 km, and the length is about 1.6 km; the dike strikes N65?? E and dips at about 87??SE. The model indicates that the dike expanded by 11 cm during repose periods, for an average volumetric expansion of nearly 500 000 m3. The volume of magma added to the dike during repose periods was variable but correlates positively with the volume of erupted lava of the subsequent eruption and represents about 8% of the new lava extruded. Dike geometry and expansion values are used to estimate the pressure increase near the eruption site due to the accumulation of magma during repose periods. On average, vent pressures increased by about 0.38 MPa during the repose periods, one-third of the pressure increase at the summit. The model indicates that the dikelike body below Puu Oo grew in volume from 3 million cubic meters (Mm3) to about 10-12 Mm3 during the series of eruptions. The width of this body was probably about 2.5-3.0 m. No net long-term deformation was detected along the measured deformation lines. ?? 1990 Springer-Verlag.

Baba Yaga and the Mushrooms

USDA-ARS?s Scientific Manuscript database

Nineteenth and early twentieth century artists portray the Russian witch Baba Yaga with mushrooms, especially with Amanita muscaria, the fly agaric. Fairy tales about Baba Yaga, as well as other Slavic folktales, repeatedly contain passing reference to mushrooms, but mushrooms are not integral to st...

The Afar rift zone deformation dynamics retrieved through phase and amplitude SAR data

NASA Astrophysics Data System (ADS)

Casu, F.; Pagli, C.; Paglia, L.; Wang, H.; Wright, T. J.; Lanari, R.

2011-12-01

The Dabbahu rift segment of the Afar depression has been active since 2005 when a 2.5 km3 dyke intrusion and hundreds of earthquakes marked the onset a rifting episode which continues to date. Since 2003, the Afar depression has been repeatedly imaged by the ENVISAT satellite, generating a large SAR archive which allow us to study the ongoing deformation processes and the dynamics of magma movements. We combine sets of small baseline interferograms through the advanced DInSAR algorithm referred to as Small BAseline Subset (SBAS), and we generate both ground deformation maps and time series along the satellite Line-Of-Sight (LOS), with accuracies on the order of 5 mm. The main limitation of DInSAR applications is that large and rapid deformations, such as those caused by dyke intrusions and eruptions in Afar, cannot be fully measured. The phase information often degrades and some areas of the interferograms are affected by high fringe rates, leading to difficulties in the phase unwrapping, and/or to complete loss of coherence due to significant misregistration errors. This limitation can be overcome by exploiting the SAR image amplitude information instead of the phase, and by calculating the Pixel-Offset (PO) field of a given SAR image pair, for both range and azimuth directions. Moreover, after computing the POs for each image pair, it is possible to combine them, following the same rationale of the SBAS technique, to finally retrieve the offset-based deformation time series. Such technique, named PO-SBAS, permits to retrieve the deformation field in areas affected by very large displacements at an accuracy that, for ENVISAT data, correspond to 30cm and 15 cm for the range and azimuth, respectively. In this work, we study the Afar rift region deformations by using both the phase and amplitude information of several sets of SAR images acquired from ascending and descending ENVISAT tracks. In particular, we use the phase information to construct dense and accurate deformation maps and time series in areas not affected by large displacements. While in areas where the deformation gradient causes loss of coherence, we retrieve the displacement field through the amplitude information. This approach allows us to obtain a spatially detailed deformation map of the study area. In addition, by combining ascending and descending data we reconstruct the vertical and East-West components of deformation field. Furthermore, in areas affected by large deformations, we can also retrieve the full 3D deformation field, by using the North-South displacement component obtained from the azimuth PO information. Distinct sources of deformations interact in Afar. Fault movements and magma chamber deflation have accompanied dyke intrusions but quantifying each contribution to the total deformation has been challenging, also due to loss of coherence in the central part of the rift. Here we combined the phase and amplitude information in order to retrieve the full deformation field of repeated intrusions. This allows us to better constrain the fault movements that occur as the dyke propagates as well as the magma movements from individual magma chambers.

Contribution of Deformation to Sea Ice Mass Balance: A Case Study From an N-ICE2015 Storm

NASA Astrophysics Data System (ADS)

Itkin, Polona; Spreen, Gunnar; Hvidegaard, Sine Munk; Skourup, Henriette; Wilkinson, Jeremy; Gerland, Sebastian; Granskog, Mats A.

2018-01-01

The fastest and most efficient process of gaining sea ice volume is through the mechanical redistribution of mass as a consequence of deformation events. During the ice growth season divergent motion produces leads where new ice grows thermodynamically, while convergent motion fractures the ice and either piles the resultant ice blocks into ridges or rafts one floe under the other. Here we present an exceptionally detailed airborne data set from a 9 km2 area of first year and second year ice in the Transpolar Drift north of Svalbard that allowed us to estimate the redistribution of mass from an observed deformation event. To achieve this level of detail we analyzed changes in sea ice freeboard acquired from two airborne laser scanner surveys just before and right after a deformation event brought on by a passing low-pressure system. A linear regression model based on divergence during this storm can explain 64% of freeboard variability. Over the survey region we estimated that about 1.3% of level sea ice volume was pressed together into deformed ice and the new ice formed in leads in a week after the deformation event would increase the sea ice volume by 0.5%. As the region is impacted by about 15 storms each winter, a simple linear extrapolation would result in about 7% volume increase and 20% deformed ice fraction at the end of the season.

Self-healing effect of spallation damageability

NASA Astrophysics Data System (ADS)

Buravova, S. N.

2017-10-01

The self-healing effect has been found in a study of the microstructure of the bands of localized deformation. It has been shown that interstitial elements (O, C) and the particles of a doping phase migrate to the zone of growing spallation damageability from the matrix material. When considering the wave pattern of the process of localization, it has been ascertained that the formation of bands of localized deformation is accompanied by the process of reverberation which is characterized by the formation of periodically repeated compression-extension cycles. A weak attenuation of the reverberation has led to an increase in the duration of the deformation pulse of the sample by two to three orders of magnitude compared with the time of the initial compression pulse.

Crustal deformations in the Central Mediterranean derived from the WHAT A CAT GPS project.

NASA Astrophysics Data System (ADS)

Kaniuth, K.; Drewes, H.; Stuber, K.; Tremel, H.; Kahler, H.-G.; Peter, Y.; Zerbini, S.; Tonti, G.; Veis, G.; Fagard, H.

1999-03-01

The West Hellenic Arc Tectonics and Calabrian Arc Tectonics (WHAT A CAT) project aimes at monitoring crustal deformations in the Central Mediterranean by repeated GPS campaigns. The data set acquired so far is rather heterogeneous in terms of availability of GPS satellites, performance of the involved receiver systems and quality of the satellites' orbits. The paper presents the velocity estimates achieved using a modified version of the Bernese GPS software. Main characteristic of the solution strategy is the definition of station velocity parameters already on theobservation equation level.

In-situ scanning electron microscope studies of crack growth in an aluminum metal-matrix composite

NASA Technical Reports Server (NTRS)

Manoharan, M.; Lewandowski, J. J.

1990-01-01

Edge-notched specimens of a cast and extruded Al alloy-based, alumina particulate-reinforced composite in the annealed condition were tested in situ in a SEM apparatus equipped with a deformation stage permitting the direct observation of crack growth phenomena. Fracture in this composite is seen to proceed by initiation of microcracks ahead of the macrocrack; as deformation proceeds, the microcracks lengthen, and crack propagation occurs when the region of intense plastic straining becomes comparable to the macrocrack-microcrack distance. The sequence is then repeated.

Microstructural Evolution and Local Mechanical Properties of Friction Stir Processed Mg-3Gd-1Zn Cast Alloy

NASA Astrophysics Data System (ADS)

Sabbaghian, M.; Mahmudi, R.

2016-05-01

Microstructural evolution, hardness, and shear strength of the cast plates of GZ31 magnesium alloy were investigated after friction stir processing (FSP). Due to severe plastic deformation and dynamic recrystallization, FSP breaks the dendrites and results in a fine homogenous structure in the stirred zone (SZ) having average grain sizes of about 4.0 and 2.5 μm in the one and two-pass FSPed plates, respectively. As a novel approach, strength of the processed plates was examined by shear punch testing in three regions of the SZ on the surface layer, namely, center line (CL), retreating side (RS), and advancing side (AS). FSP showed great potential in the enhancement of SZ ultimate shear strength from 114 to about 152 and 155 MPa in the one and two-pass FSPed materials, respectively. The same trend was observed in hardness values of the SZ, where the average hardness of the base material increased from 41 to 60 and 68 Vickers after one and two passes of FSP, respectively. The variations in the shear strength of the CL, RS, and AS zones of the SZ were about 5% for the first pass of FSP, the effect which was decreased to less than 2% after two passes of FSP.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poplawski, L; Li, T; Chino, J

Purpose: In brachytherapy, structures surrounding the target have the potential to move between treatments and receive unknown dose. Deformable image registration could overcome challenges through dose accumulation. This study uses two possible deformable dose summation techniques and compares the results to point dose summation currently performed in clinic. Methods: Data for ten patients treated with a Syed template was imported into the MIM software (Cleveland, OH). The deformable registration was applied to structures by masking other image data to a single intensity. The registration flow consisted of the following steps: 1) mask CTs so that each of the structures-of-interest hadmore » one unique intensity; 2) perform applicator — based rigid registration; 3) Perform deformable registration; 4) Refine registration by changing local alignments manually; 5) Repeat steps 1 to 3 until desired structure adequately deformed; 5) Transfer each deformed contours to the first CT. The deformed structure accuracy was determined by a dice similarity coefficient (DSC) comparison with the first fraction. Two dose summation techniques were investigated: a deformation and recalculation on the structure; and a dose deformation and accumulation method. Point doses were used as a comparison value. Results: The Syed deformations have DSC ranging from 0.53 to 0.97 and 0.75 and 0.95 for the bladder and rectum, respectively. For the bladder, contour deformation addition ranged from −34.8% to 0.98% and dose deformation accumulation ranged from −35% to 29.3% difference from clinical calculations. For the rectum, contour deformation addition ranged from −5.2% to 16.9% and the dose deformation accumulation ranged from −29.1% to 15.3% change. Conclusion: Deforming dose for summation leads to different volumetric doses than when dose is recalculated on deformed structures, raising concerns about the accuracy of the deformed dose. DSC alone cannot be used to establish the accuracy of a deformation for brachy dose summation purpose.« less

Reconciling short recurrence intervals with minor deformation in the New Madrid seismic zone

USGS Publications Warehouse

Schweig, E.S.; Ellis, M.A.

1994-01-01

At least three great earthquakes occurred in the New Madrid seismic zone in 1811 and 1812. Estimates of present-day strain rates suggest that such events may have a repeat time of 1000 years or less. Paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years. However, pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed. This suggests that the seismic zone is a young feature, possibly as young as several tens of thousands of years old and no more than a few million years old.At least three great earthquakes occurred in the New Madrid seismic zone in 1811 and 1812. Estimates of present-day strain rates suggest that such events may have a repeat time of 1000 years or less. Paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years. However, pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed. This suggests that the seismic zone is a young feature, possibly as young as several tens of thousands of years old and no more than a few million years old.

Quaternary Landscape Evolution and the Surface Expression of Plume-Lithosphere Interactions in the Greater Yellowstone Area.

NASA Astrophysics Data System (ADS)

Guerrero, E.; Meigs, A.; Kirby, E.

2016-12-01

Numerous investigations demonstrate that mantle convective processes such as upwelling affect the surface topography of the overriding plate and propagates through the plate accompanying its lateral motion. This deformation signal is known as transient topography and is thought to occur in the North American plate as it passes over the Yellowstone hotspot. This work explores the sensitivity of the surface of Western North America by testing the hypothesis that advection of a transient topographic wave through the North American plate is driving post-Pliocene landscape evolution of the greater Yellowstone region as the plate passes over the mantle plume. Analysis of digital elevation data reveals an asymmetric topographic swell that has an amplitude of 400-1200 m and a wavelength of 600 km which was disentangled from overlapping signals preserved in the topography. A maximum uplift rate of 0.17 mm yr-1 leads the apex of the transient topography swell by nearly 100 km. This means that presently, the western edge of the Bighorn Basin is experiencing a surface uplift rate between 0.166 and 0.302 mm yr-1 which indicates 400-800m of surface uplift in the western edge of the basin since 3 Ma and a tilt of 0.3° and 0.5° away from Yellowstone. We reinterpret the drainage evolution and erosional story of the Bighorn Basin preserved by sequences of fluvial terraces in the Bighorn Basin based on this new deformation model. We integrate this new deformation model with mapping, dating, and paleoflow data into the post-Pliocene erosional story in the basin. The change from a northward drainage to an eastward drainage through stream capture, the lateral migration of the Bighorn river away from Yellowstone, and differential incision in the basin coincides with transient topography-forced deformation.

Themes of Suicide in the Kalevala.

ERIC Educational Resources Information Center

Achte, Kalle; And Others

1988-01-01

The Kalevala, Finland's national epic, is a crucial element of Finnish cultural identity and important to Finnish culture. Violence, death, and suicide are often repeated themes in Finnish folklore. The Kalevala provides insight into past attitudes toward death. Traditions passed through generations have influenced people's attitudes toward…

Evaluation of Airborne l- Band Multi-Baseline Pol-Insar for dem Extraction Beneath Forest Canopy

NASA Astrophysics Data System (ADS)

Li, W. M.; Chen, E. X.; Li, Z. Y.; Jiang, C.; Jia, Y.

2018-04-01

DEM beneath forest canopy is difficult to extract with optical stereo pairs, InSAR and Pol-InSAR techniques. Tomographic SAR (TomoSAR) based on different penetration and view angles could reflect vertical structure and ground structure. This paper aims at evaluating the possibility of TomoSAR for underlying DEM extraction. Airborne L-band repeat-pass Pol-InSAR collected in BioSAR 2008 campaign was applied to reconstruct the 3D structure of forest. And sum of kronecker product and algebraic synthesis algorithm were used to extract ground structure, and phase linking algorithm was applied to estimate ground phase. Then Goldstein cut-branch approach was used to unwrap the phases and then estimated underlying DEM. The average difference between the extracted underlying DEM and Lidar DEM is about 3.39 m in our test site. And the result indicates that it is possible for underlying DEM estimation with airborne L-band repeat-pass TomoSAR technique.

High energy forming facility

NASA Technical Reports Server (NTRS)

Ciurlionis, B.

1967-01-01

Watertight, high-explosive forming facility, 25 feet in diameter and 15 feet deep, withstands repeated explosions of 10 pounds of TNT equivalent. The shell is fabricated of high strength steel and allows various structural elements to deform or move elastically and independently while retaining structural integrity.

Endoscopic electrosurgical papillotomy and manometry in biliary tract disease.

PubMed

Geenen, J E; Hogan, W J; Shaffer, R D; Stewart, E T; Dodds, W J; Arndorfer, R C

1977-05-09

Endoscopic papillotomy was performed in 13 patients after cholecystectomy for retained or recurrent common bile duct calculi (11 patients) and a clinical picture suggesting papillary stenosis (two patients). Following endoscopic papillotomy, ten of the 11 patients spontaneously passed common bile duct (CBD) stones verified on repeated endoscopic retrograde cholangiopancreatography (ERCP) study. One patient failed to pass a large CBD calculus; one patient experienced cholangitis three months after in inadequate papillotomy and required operative intervention. Endoscopic papillotomy substantially decreased the pressure gradient existing between the CBD and the duodenum in all five patients studied with ERCP manometry. Endoscopic papillotomy is a relatively safe and effective procedure for postcholecystectomy patients with retained or recurrent CBD stones. The majority of CBD stones will pass spontaneously if the papillotomy is adequate.

Single-stranded DNA-binding Protein in Vitro Eliminates the Orientation-dependent Impediment to Polymerase Passage on CAG/CTG Repeats*

PubMed Central

Delagoutte, Emmanuelle; Goellner, Geoffrey M.; Guo, Jie; Baldacci, Giuseppe; McMurray, Cynthia T.

2008-01-01

Small insertions and deletions of trinucleotide repeats (TNRs) can occur by polymerase slippage and hairpin formation on either template or newly synthesized strands during replication. Although not predicted by a slippage model, deletions occur preferentially when 5′-CTG is in the lagging strand template and are highly favored over insertion events in rapidly replicating cells. The mechanism for the deletion bias and the orientation dependence of TNR instability is poorly understood. We report here that there is an orientation-dependent impediment to polymerase progression on 5′-CAG and 5′-CTG repeats that can be relieved by the binding of single-stranded DNA-binding protein. The block depends on the primary sequence of the TNR but does not correlate with the thermodynamic stability of hairpins. The orientation-dependent block of polymerase passage is the strongest when 5′-CAG is the template. We propose a “template-push” model in which the slow speed of DNA polymerase across the 5′-CAG leading strand template creates a threat to helicase-polymerase coupling. To prevent uncoupling, the TNR template is pushed out and by-passed. Hairpins do not cause the block, but appear to occur as a consequence of polymerase pass-over. PMID:18263578

Repeating Marmara Sea earthquakes: indication for fault creep

NASA Astrophysics Data System (ADS)

Bohnhoff, Marco; Wollin, Christopher; Domigall, Dorina; Küperkoch, Ludger; Martínez-Garzón, Patricia; Kwiatek, Grzegorz; Dresen, Georg; Malin, Peter E.

2017-07-01

Discriminating between a creeping and a locked status of active faults is of central relevance to characterize potential rupture scenarios of future earthquakes and the associated seismic hazard for nearby population centres. In this respect, highly similar earthquakes that repeatedly activate the same patch of an active fault portion are an important diagnostic tool to identify and possibly even quantify the amount of fault creep. Here, we present a refined hypocentre catalogue for the Marmara region in northwestern Turkey, where a magnitude M up to 7.4 earthquake is expected in the near future. Based on waveform cross-correlation for selected spatial seismicity clusters, we identify two magnitude M ∼ 2.8 repeater pairs. These repeaters were identified as being indicative of fault creep based on the selection criteria applied to the waveforms. They are located below the western part of the Marmara section of the North Anatolian Fault Zone and are the largest reported repeaters for the larger Marmara region. While the eastern portion of the Marmara seismic gap has been identified to be locked, only sparse information on the deformation status has been reported for its western part. Our findings indicate that the western Marmara section deforms aseismically to a substantial extent, which reduces the probability for this region to host a nucleation point for the pending Marmara earthquake. This is of relevance, since a nucleation of the Marmara event in the west and subsequent eastward rupture propagation towards the Istanbul metropolitan region would result in a substantially higher seismic hazard and resulting risk than if the earthquake would nucleate in the east and thus propagate westward away from the population centre Istanbul.

Vertical deformation of the Axial Seamount summit from repeated 1-m scale bathymetry surveys using AUVs

NASA Astrophysics Data System (ADS)

Caress, D. W.; Clague, D. A.; Paduan, J. B.; Thomas, H. J.; Chadwick, W. W., Jr.; Nooner, S. L.; Yoerger, D.

2016-12-01

Axial Seamount is an intensely studied submarine hotspot volcano on the Juan de Fuca Ridge that erupted in 1998, 2011, and 2015. MBARI Mapping AUV surveys during 2006-2009 obtained nearly complete 1 m resolution topographic coverage of the Axial Seamount summit, including the caldera, the caldera rim, and the south rift zone. Surveys following both recent eruptions mapped new lava flows and extended coverage of the caldera rim and the north and south rifts. These include 2011 (post-eruption), 2014, and 2016 MBARI Mapping AUV surveys and 2015 (post-eruption) WHOI AUV Sentry surveys. These AUVs use 200 kHz or 400 kHz multibeam sonars operated from 50 m to 75 m altitudes to achieve 1 m lateral resolution and 0.1 m vertical precision. Differencing repeat surveys allows detection of topographic change > 0.2 m, a capability used to map the extent, morphology and volume of lava flows emplaced by the 2011 and 2015 eruptions. In situ pressure observations show the uplift and subsidence of the caldera center associated with pre-eruption inflation and co-eruption deflation of the sub-caldera magma chamber has a 2.5-3.5 m magnitude, and thus can be observed by repeat AUV surveys. A survey pattern crossing the caldera interior both E-W and N-S and extending 8 km down the south rift was established in 2011 that has been repeated in 2014, 2015, and 2016. The 2015 surveys established a larger, asterisk-shaped survey pattern extending about 4 km outside the caldera walls along seven lines that has now been repeated in 2016. Repeat survey comparison reveals the vertical deformation pattern of the eruption cycle. Between 2011 and 2014 the uplift has a maximum of 1.8 m near the caldera center, and diminishes steadily away from this site. Between 2014 and 2015 there is a 1.0 m subsidence of the caldera center associated with the April 2015 eruption. The comparison of the 2011 and 2015 surveys shows that the caldera floor is slightly uplifted four months after the 2015 eruption relative to four months after the 2011 eruption. Results incorporating the new 2016 surveys will be presented. These results are consistent with 1 cm precision pressure benchmark observations on the caldera and south rift by Chadwick and Nooner. Our AUV mapping method is less precise than pressure benchmark data but measures the deformation pattern over a larger, spatially continuous area.

Geologic map of the Snoqualmie Pass 30 x 60 minute quadrangle, Washington

USGS Publications Warehouse

Tabor, R.W.; Frizzell, V.A.; Booth, D.B.; Waitt, R.B.

2000-01-01

The Snoqualmie Pass quadrangle lies at the north edge of a Tertiary volcanic and sedimentary cover, where the regional structural uplift to the north elevated the older rocks to erosional levels. Much of the quadrangle is underlain by folded Eocene volcanic rocks and fluvial deposts of an extensional event, and these rocks are overlain by Cascade arc volcanic rocks: mildly deformed Oligocene-Miocene rocks and undeformed younger volcanic rocks. Melanges of Paleozoic and Mesozoic rocks are exposed in structural highs in the northern part of the quadrangle. The quadrangle is traversed north to south by the Straight Creek Fault, and the probably partially coincident Darringon-Devils Mountain Fault. A rich Quaternary stratigraphy reveals events of the Frazer glaciation.

Aseismic Transform Fault Slip at the Mendocino Triple Junction From Characteristically Repeating Earthquakes

NASA Astrophysics Data System (ADS)

Materna, Kathryn; Taira, Taka'aki; Bürgmann, Roland

2018-01-01

The Mendocino Triple Junction (MTJ), at the northern terminus of the San Andreas Fault system, is an actively deforming plate boundary region with poorly constrained estimates of seismic coupling on most offshore fault surfaces. Characteristically repeating earthquakes provide spatial and temporal descriptions of aseismic creep at the MTJ, including on the oceanic transform Mendocino Fault Zone (MFZ) as it subducts beneath North America. Using a dataset of earthquakes from 2008 to 2017, we find that the easternmost segment of the MFZ displays creep during this period at about 65% of the long-term slip rate. We also find creep at slower rates on the shallower strike-slip interface between the Pacific plate and the North American accretionary wedge, as well as on a fault that accommodates Gorda subplate internal deformation. After a nearby M5.7 earthquake in 2015, we observe a possible decrease in aseismic slip on the near-shore MFZ that lasts from 2015 to at least early 2017.

Long-term follow-up of early cleft maxillary distraction.

PubMed

Park, Young-Wook; Kwon, Kwang-Jun; Kim, Min-Keun

2016-12-01

Most of cleft lip and palate patients have the esthetic and functional problems of midfacial deficiencies due to innate developmental tendency and scar tissues from repeated operations. In these cases, maxillary protraction is required for the harmonious facial esthetics and functional occlusion. A 7-year old boy had been diagnosed as severe maxillary constriction due to unilateral complete cleft lip and palate. The author tried to correct the secondary deformity by early distraction osteogenesis with the aim of avoiding marked psychological impact from peers of elementary school. From 1999 to 2006, repeated treatments, which consisted of Le Fort I osteotomy and face mask distraction, and complementary maxillary protraction using miniplates were performed including orthodontics. But, final facial profile was not satisfactory, which needs compromising surgery. The result of this study suggests that if early distraction treatment is performed before facial skeletal growth is completed, an orthognathic surgery or additional distraction may be needed later. Maxillofacial plastic and reconstructive surgeons should notify this point when they plan early distraction treatment for cleft maxillary deformity.

Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

DOEpatents

Vincent, Paul

2005-06-28

A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

A Correction to the Stress-Strain Curve During Multistage Hot Deformation of 7150 Aluminum Alloy Using Instantaneous Friction Factors

NASA Astrophysics Data System (ADS)

Jiang, Fulin; Tang, Jie; Fu, Dinfa; Huang, Jianping; Zhang, Hui

2018-04-01

Multistage stress-strain curve correction based on an instantaneous friction factor was studied for axisymmetric uniaxial hot compression of 7150 aluminum alloy. Experimental friction factors were calculated based on continuous isothermal axisymmetric uniaxial compression tests at various deformation parameters. Then, an instantaneous friction factor equation was fitted by mathematic analysis. After verification by comparing single-pass flow stress correction with traditional average friction factor correction, the instantaneous friction factor equation was applied to correct multistage stress-strain curves. The corrected results were reasonable and validated by multistage relative softening calculations. This research provides a broad potential for implementing axisymmetric uniaxial compression in multistage physical simulations and friction optimization in finite element analysis.

Metadynamic and static recrystallization softening behavior of a bainite steel

NASA Astrophysics Data System (ADS)

Li, Lixin; Zheng, Liangyu; Ye, Ben; Tong, Zeqiong

2018-01-01

The metadynamic recrystallization (MDRX) and static recrystallization (SRX) softening behavior of a bainite steel was investigated by two-pass isothermal compression experiments at temperatures of 1173, 1273, 1373, and 1473 K and strain rates of 0.01, 0.1, 1, and 10 s-1 with inter-pass times of 1, 5, 10, and 30 s on a Gleeble-1500 thermo-mechanical simulator. Kinetic equations were developed to evaluate the softening fractions caused by MDRX and SRX. A comparison between the experimental and predicted softening fractions showed that the proposed kinetic equations can provide a precise estimation of the MDRX and SRX behavior of the studied steel. The results based on the kinetic equations indicated that the MDRX and SRX softening fraction increases with the increase in strain rate, deformation temperature, inter-pass time, and pre-strain; the activation energy of MDRX is much smaller than that of SRX; and the no-recrystallization temperature of the investigated steel is 1179.4 K.

The use of baseline measurements and geophysical models for the estimation of crustal deformations and the terrestrial reference system. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Bock, Y.

1982-01-01

Four possible estimators are investigated for the monitoring of crustal deformations from a combination of repeated baseline length measurements and adopted geophysical models, particularly an absolute motion plate model. The first estimator is an extension of the familiar free adjustment. The next two are Bayesian type estimators, one weak and one strong. Finally, a weighted constraint estimator is presented. The properties of these four estimators are outlined and their physical interpretations discussed. A series of simulations are performed to test the four estimators and to determine whether or not to incorporate a plate model for the monitoring of deformations. The application of these estimations to the maintenance of a new conventional terrestrial reference system is discussed.

Applications of Radar Interferometric Techniques to Assess Natural Hazards and their Controlling Factors

NASA Astrophysics Data System (ADS)

Sultan, M.; Becker, R.; Gebremichael, E.; Othman, A.; Emil, M.; Ahmed, M.; Elkadiri, R.; Pankratz, H. G.; Chouinard, K.

2015-12-01

Radar interferometric techniques including Persistent Scatterer (PS), Small BAseline Subset (SBAS), and two and three pass (differential interferometry) methods were applied to Synthetic Aperture Radar (SAR) datasets. These include the European Space Agency (ESA) ERS-1, ERS-2, Environmental satellite (Envisat), and Phased Array type L-band Synthetic Aperture Radar (PALSAR) to conduct the following: (1) map the spatial distribution of land deformation associated with a wide range of geologic settings, (2) quantify the rates of the observed land deformation, and (3) identify the factors controlling the observed deformation. The research topics/areas include: (1) subsidence associated with sediment compaction in a Delta setting (Nile Delta, Egypt), (2) deformation in a rifting setting (Red Sea rifting along the Red Sea coastal zone and proximal basement outcrops in Egypt and Saudi Arabia), (3) deformation associated with salt dome intrusion and the dissolution of sabkha deposits (Jazan area in Saudi Arabia), (4) mass transport associated with debris flows (Jazan area in Saudi Arabia), and (5) deformation preceding, contemporaneous with, or following large earthquakes (in Nepal; magnitude: 7.8; date: April, 25, 2015) and medium earthquakes (in Harrat Lunayyir volcanic field, central Saudi Arabia; magnitude: 5.7; date: May 19, 2009). The identification of the factor(s) controlling the observed deformation was attained through spatial correlation of extracted radar velocities with relevant temporal and static ground based and remotely sensed geological and cultural data sets (e.g., lithology, structure, precipitation, land use, and earthquake location, magnitude, and focal mechanism) in a Geographical Information System (GIS) environment.

Novel silicon microchannels device for use in red blood cell deformability studies

NASA Astrophysics Data System (ADS)

Zheng, Xiao-Lin; Liao, Yan-Jian; Zhang, Wen-Xian

2001-10-01

Currently, a number of techniques are used to access cell deformability. We study a novel silicon microchannels device for use in red blood cell deformability. The channels are produced in silicon substrate using microengineering technology. The microgrooves formed in the surface of a single-crystal silicon substrate. They were converted to channels by tightly covering them with an optical flat glass plate. An array of flow channels (number 950 in parallel) have typical dimensions of 5 micrometers width X 5.5 Xm depth, and 30 micrometers length. There the RBC's are forced to pass through channels. Thus, the microchannels are used to simulate human blood capillaries. It provides a specific measurement of individual cell in terms of both flow velocity profile and an index of cell volume while the cell flow through the channels. It dominates the complex cellular flow behavior, such as, the viscosity of whole blood is a nonlinear function of shear rate, index of filtration, etc.

Numerical Simulations of the Motion and Deformation of Three RBCs during Poiseuille Flow through a Constricted Vessel Using IB-LBM.

PubMed

Wang, Rongyang; Wei, Yikun; Wu, Chuanyu; Sun, Liang; Zheng, Wenguang

2018-01-01

The immersed boundary-lattice Boltzmann method (IB-LBM) was used to examine the motion and deformation of three elastic red blood cells (RBCs) during Poiseuille flow through constricted microchannels. The objective was to determine the effects of the degree of constriction and the Reynolds (Re) number of the flow on the physical characteristics of the RBCs. It was found that, with decreasing constriction ratio, the RBCs experienced greater forced deformation as they squeezed through the constriction area compared to at other parts of the microchannel. It was also observed that a longer time was required for the RBCs to squeeze through a narrower constriction. The RBCs subsequently regained a stable shape and gradually migrated toward the centerline of the flow beyond the constriction area. However, a sick RBC was observed to be incapable of passing through a constricted vessel with a constriction ratio ≤1/3 for Re numbers below 0.40.

Numerical Simulations of the Motion and Deformation of Three RBCs during Poiseuille Flow through a Constricted Vessel Using IB-LBM

PubMed Central

Sun, Liang; Zheng, Wenguang

2018-01-01

The immersed boundary-lattice Boltzmann method (IB-LBM) was used to examine the motion and deformation of three elastic red blood cells (RBCs) during Poiseuille flow through constricted microchannels. The objective was to determine the effects of the degree of constriction and the Reynolds (Re) number of the flow on the physical characteristics of the RBCs. It was found that, with decreasing constriction ratio, the RBCs experienced greater forced deformation as they squeezed through the constriction area compared to at other parts of the microchannel. It was also observed that a longer time was required for the RBCs to squeeze through a narrower constriction. The RBCs subsequently regained a stable shape and gradually migrated toward the centerline of the flow beyond the constriction area. However, a sick RBC was observed to be incapable of passing through a constricted vessel with a constriction ratio ≤1/3 for Re numbers below 0.40. PMID:29681999

Determining the tensile response of materials at high temperature using DIC and the Virtual Fields Method

NASA Astrophysics Data System (ADS)

Valeri, Guillermo; Koohbor, Behrad; Kidane, Addis; Sutton, Michael A.

2017-04-01

An experimental approach based on Digital Image Correlation (DIC) is successfully applied to predict the uniaxial stress-strain response of 304 stainless steel specimens subjected to nominally uniform temperatures ranging from room temperature to 900 °C. A portable induction heating device equipped with custom made water-cooled copper coils is used to heat the specimen. The induction heater is used in conjunction with a conventional tensile frame to enable high temperature tension experiments. A stereovision camera system equipped with appropriate band pass filters is employed to facilitate the study of full-field deformation response of the material at elevated temperatures. Using the temperature and load histories along with the full-field strain data, a Virtual Fields Method (VFM) based approach is implemented to identify constitutive parameters governing the plastic deformation of the material at high temperature conditions. Results from these experiments confirm that the proposed method can be used to measure the full field deformation of materials subjected to thermo-mechanical loading.

Plastic deformation and wear process at a surface during unlubricated sliding

NASA Technical Reports Server (NTRS)

Yamamoto, T.; Buckley, D. H.

1983-01-01

The plastic deformation and wear of a 304 stainless steel surface sliding against an aluminum oxide rider with a spherical surface (the radius of curvature: 1.3 cm) were observed by using scanning electron and optical microscopes. Experiments were conducted in a vacuum of one million Pa and in an environment of fifty thousandth Pa of chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step shaped proturbances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. The mechanism for tearing away of the surface layer from the contact area and sliding track contour is explained assuming the simplified process of material removal based on the adhesion theory for the wear of materials. Previously announced in STAR as N82-32735

Freeform correction polishing for optics with semi-kinematic mounting

NASA Astrophysics Data System (ADS)

Huang, Chien-Yao; Kuo, Ching-Hsiang; Peng, Wei-Jei; Yu, Zong-Ru; Ho, Cheng-Fang; Hsu, Ming-Ying; Hsu, Wei-Yao

2015-10-01

Several mounting configurations could be applied to opto-mechanical design for achieving high precise optical system. The retaining ring mounting is simple and cost effective. However, it would deform the optics due to its unpredictable over-constraint forces. The retaining ring can be modified to three small contact areas becoming a semi-kinematic mounting. The semi-kinematic mounting can give a fully constrained in lens assembly and avoid the unpredictable surface deformation. However, there would be still a deformation due to self-weight in large optics especially in vertical setup applications. The self-weight deformation with a semi-kinematic mounting is a stable, repeatable and predictable combination of power and trefoil aberrations. This predictable deformation can be pre-compensated onto the design surface and be corrected by using CNC polisher. Thus it is a freeform surface before mounting to the lens cell. In this study, the freeform correction polishing is demonstrated in a Φ150 lens with semi-kinematic mounting. The clear aperture of the lens is Φ143 mm. We utilize ANSYS simulation software to analyze the lens deformation due to selfweight deformation with semi-kinematic mounting. The simulation results of the self-weight deformation are compared with the measurement results of the assembled lens cell using QED aspheric stitching interferometer (ASI). Then, a freeform surface of a lens with semi-kinematic mounting due to self-weight deformation is verified. This deformation would be corrected by using QED Magnetorheological Finishing (MRF® ) Q-flex 300 polishing machine. The final surface form error of the assembled lens cell after MRF figuring is 0.042 λ in peak to valley (PV).

Automated dynamic feature tracking of RSLs on the Martian surface through HiRISE super-resolution restoration and 3D reconstruction techniques

NASA Astrophysics Data System (ADS)

Tao, Y.; Muller, J.-P.

2017-09-01

In this paper, we demonstrate novel Super-resolution restoration and 3D reconstruction tools developed within the EU FP7 projects and their applications to advanced dynamic feature tracking through HiRISE repeat stereo. We show an example with one of the RSL sites in the Palikir Crater took 8 repeat-pass 25cm HiRISE images from which a 5cm RSL-free SRR image is generated using GPT-SRR. Together with repeat 3D modelling of the same area, it allows us to overlay tracked dynamic features onto the reconstructed "original" surface, providing a much more comprehensive interpretation of the surface formation processes in 3D.

3D displacement time series in the Afar rift zone computed from SAR phase and amplitude information

NASA Astrophysics Data System (ADS)

Casu, Francesco; Manconi, Andrea

2013-04-01

Large and rapid deformations, such as those caused by earthquakes, eruptions, and landslides cannot be fully measured by using standard DInSAR applications. Indeed, the phase information often degrades and some areas of the interferograms are affected by high fringe rates, leading to difficulties in the phase unwrapping, and/or to complete loss of coherence due to significant misregistration errors. This limitation can be overcome by exploiting the SAR image amplitude information instead of the phase, and by calculating the Pixel-Offset (PO) field SAR image pairs, for both range and azimuth directions. Moreover, it is possible to combine the PO results by following the same rationale of the SBAS technique, to finally retrieve the offset-based deformation time series. Such technique, named PO-SBAS, permits to retrieve the deformation field in areas affected by very large displacements at an accuracy that, for ENVISAT data, correspond to 30 cm and 15 cm for the range and azimuth, respectively [1]. Moreover, the combination of SBAS and PO-SBAS time series can help to better study and model deformation phenomena characterized by spatial and temporal heterogeneities [2]. The Dabbahu rift segment of the Afar depression has been active since 2005 when a 2.5 km3 dyke intrusion and hundreds of earthquakes marked the onset a rifting episode which continues to date. The ENVISAT satellite has repeatedly imaged the Afar depression since 2003, generating a large SAR archive. In this work, we study the Afar rift region deformations by using both the phase and amplitude information of several sets of SAR images acquired from ascending and descending ENVISAT tracks. We combined sets of small baseline interferograms through the SBAS algorithm, and we generate both ground deformation maps and time series along the satellite Line-Of-Sight (LOS). In areas where the deformation gradient causes loss of coherence, we retrieve the displacement field through the amplitude information. Furthermore, we could also retrieve the full 3D deformation field, by considering the North-South displacement component obtained from the azimuth PO information. The combination of SBAS and PO-SBAS information permits to better retrieve and constrain the full deformation field due to repeated intrusions, fault movements, as well as the magma movements from individual magma chambers. [1] Casu, F., A. Manconi, A. Pepe and R. Lanari, 2011. Deformation time-series generation in areas characterized by large displacement dynamics: the SAR amplitude Pixel-Offset SBAS technique, IEEE Transaction on Geosciences and Remote Sensing. [2] Manconi, A. and F. Casu, 2012. Joint analysis of displacement time series retrieved from SAR phase and amplitude: impact on the estimation of volcanic source parameters, Geophysical Research Letters, doi:10.1029/2012GL052202.

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape

PubMed Central

Zhang, Lin; Sánchez del Río, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I.; Glatzel, Pieter

2013-01-01

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results. PMID:23765298

Shock wave absorber having a deformable liner

DOEpatents

Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

1983-08-26

This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

Technical and physical determinants of soccer match-play performance in elite youth soccer players.

PubMed

Rowat, Owain; Fenner, Jonathan; Unnithan, Viswanath

2017-04-01

The aim of this study was to evaluate whether physical performance characteristics could be a better predictor than technical skills in determining the technical level of county soccer players in a match situation. With institutional ethics approval, 25 male youth soccer players aged 16-18.5 years from a professional soccer academy in South East Asia were selected and height and body mass were recorded. Players were tested for sexual maturity (pubertal development scale [PDS] self-assessment), aerobic capacity (yo-yo intermittent recovery test level 1 [YYIR1]), repeated sprint ability (7 x 35 m sprints) acceleration (15 m sprint) and four soccer skills tests (dribble with pass, dribbling speed, passing and shooting accuracy). Players' technical ability during match play was assessed in small-sided games of soccer (5 v 5) using a novel game technical scoring chart (scoring chart completed by coaches to assess technical performance in a match situation) developed from criteria (e.g., first touch, dribbling and two footedness) used by youth soccer coaches for talent identification. A Spearman's rank correlation showed the YYIR1 test and 15 m sprint test were limited in predicting technical match performance (r=0.03, P=0.88, r=-0.23, P=0.32 respectively). A Pearson product moment correlation showed that the repeated sprint test was also limited in predicting technical match performance (r=-0.34, P=0.14). A dribbling skill with a pass was found to be the best determinant of a player's technical ability in a match (r=-0.57, P=0.00). Talent identification and selection programs in Asian youth soccer should include a dribbling skill performed with a pass.

Genome-wide detection of CNVs associated with beak deformity in chickens using high-density 600K SNP arrays.

PubMed

Bai, H; Sun, Y; Liu, N; Liu, Y; Xue, F; Li, Y; Xu, S; Ni, A; Ye, J; Chen, Y; Chen, J

2018-06-01

Beak deformity (crossed beaks) is found in several indigenous chicken breeds including Beijing-You studied here. Birds with deformed beaks have reduced feed intake and poor production performance. Recently, copy number variation (CNV) has been examined in many species and is recognized as a source of genetic variation, especially for disease phenotypes. In this study, to unravel the genetic mechanisms underlying beak deformity, we performed genome-wide CNV detection using Affymetrix chicken high-density 600K data on 48 deformed-beak and 48 normal birds using penncnv. As a result, two and eight CNV regions (CNVRs) covering 0.32 and 2.45 Mb respectively on autosomes were identified in deformed-beak and normal birds respectively. Further RT-qPCR studies validated nine of the 10 CNVRs. The ratios of six CNVRs were significantly different between deformed-beak and normal birds (P < 0.01). Within these six regions, three and 21 known genes were identified in deformed-beak and normal birds respectively. Bioinformatics analysis showed that these genes were enriched in six GO terms and one KEGG pathway. Five candidate genes in the CNVRs were further validated using RT-qPCR. The expression of LRIG2 (leucine rich repeats and immunoglobulin like domains 2) was lower in birds with deformed beaks (P < 0.01). Therefore, the LRIG2 gene could be considered a key factor in view of its known functions and its potential roles in beak deformity. Overall, our results will be helpful for future investigations of the genomic structural variations underlying beak deformity in chickens. © 2018 Stichting International Foundation for Animal Genetics.

Habit tic nail deformity - a rare presentation in an 8 year old boy.

PubMed

El-Heis, S; Abadie, Al

2016-11-15

Habit tic nail deformity is a nail dystrophy resulting from habitual, repetitive trauma to the nail. It is usually acquired in adulthood, however, we report a case of habit tic nail deformity in an 8 year old boy. The diagnosis was made clinically with further history revealing that the boy repeatedly rubbed his thumbnails and pushed the cuticles. Emollient cream (Balneum®) was recommended twice daily and both the patient and his mother were educated on the behavioral nature of this condition. There was marked improvement at 6 months of treatment and further improvement at 12 months.We note that habit tic nail deformity is not exclusive to adults. Diagnosis can be made clinically. History and physical examination provide valuable clues and psychosocial links must be explored and addressed. Management is challenging and compliance with treatment is variable. Patient education, barrier methods, and behavioral therapy can be helpful in preventing further trauma to the nails.

Nano-deformation behavior of silicon (100) film studied by depth sensing indentation and nanoscratch technique

NASA Astrophysics Data System (ADS)

Geetha, D.; Pratyank, R.; Kiran, P.

2018-04-01

Silicon being the most important material applied in microelectronic and photovoltaic technology, repeated investigation of the mechanical properties becomes essential. The nanoscale elastic-plastic deformation characteristics of Si (100) film were analyzed using nanoindentation and nanoscratch techniques. The hardness and elastic modulus values of the film obtained from nanoindentation tests were found to be consistent with the reported values. The load-displacement curves showed discontinuities and kinks which confirms the plastic behaviour of Si. The indentation induced plastic deformations were the consequences of the phase transformations. The critical shear stress, tensile strength and plastic zone size, of the Si film when subjected to nanoindentation were determined. The nanoscratch tests were performed to understand the tribological properties of the film. The SPM images of both the nanoindentation and nanoscratch profiles were useful in revealing the plastic character in terms of the piling up of matter in the vicinity of the dents. Conclusions were drawn in quantifying the plastic deformations and phase transformations.

Effect of external digital elevation model on monitoring of mine subsidence by two-pass differential interferometric synthetic aperture radar

NASA Astrophysics Data System (ADS)

Tao, Qiuxiang; Gao, Tengfei; Liu, Guolin; Wang, Zhiwei

2017-04-01

The external digital elevation model (DEM) error is one of the main factors that affect the accuracy of mine subsidence monitored by two-pass differential interferometric synthetic aperture radar (DInSAR), which has been widely used in monitoring mining-induced subsidence. The theoretical relationship between external DEM error and monitored deformation error is derived based on the principles of interferometric synthetic aperture radar (DInSAR) and two-pass DInSAR. Taking the Dongtan and Yangcun mine areas of Jining as test areas, the difference and accuracy of 1:50000, ASTER GDEM V2, and SRTM DEMs are compared and analyzed. Two interferometric pairs of Advanced Land Observing Satellite Phased Array L-band SAR covering the test areas are processed using two-pass DInSAR with three external DEMs to compare and analyze the effect of three external DEMs on monitored mine subsidence in high- and low-coherence subsidence regions. Moreover, the reliability and accuracy of the three DInSAR-monitored results are compared and verified with leveling-measured subsidence values. Results show that the effect of external DEM on mine subsidence monitored by two-pass DInSAR is not only related to radar look angle, perpendicular baseline, slant range, and external DEM error, but also to the ground resolution of DEM, the magnitude of subsidence, and the coherence of test areas.

Asymmetric C7 pedicle subtraction osteotomy for correction of rigid cervical coronal imbalance secondary to post-traumatic heterotopic ossification: a case report, description of a novel surgical technique, and literature review.

PubMed

Theologis, Alexander A; Bellevue, Kate D; Qamirani, Erion; Ames, Christopher P; Deviren, Vedat

2017-05-01

Deformities of the cervical spine are uncommon in the coronal plane. In this report, a unique case of a 31-year-old male with a fixed, 30° left coronal deformity due to heterotopic ossification 3 years status post poly-trauma was treated with an asymmetric C7 pedicle subtraction osteotomy (PSO). Case report. Pre-operatively, the patient had a fixed 45-degree left tilt of his neck and radiographs demonstrated a rigid 30° scoliosis, 7 cm coronal imbalance, and 4 cm negative sagittal balance, diffuse bridging bone between the spinous processes and the facet joints of C5 to T1 bilaterally. An asymmetric C7 PSO with C2-T3 posterior spinal fusion was completed without complication. There was residual 9° coronal deformity, 2.9 cm left coronal imbalance, and 2.3 cm sagittal imbalance. He had a marked improvement in his function, as assessed by the SF-36 physical component score (pre-op 31.1; post-op 44.7) and mental component score (pre-op 46.0; post-op 66.8). Post-operatively, neck disability index scores also improved (pre-op 38; post-op 16). Although the patient passed away from a drug overdose 14 months post-operatively, he did not report neck pain, he had not sought evaluation from another physician for his neck, and he had not undergone a subsequent neck operation before his passing. In this one patient, an asymmetric C7 PSO was performed safely. While it was effective in addressing a fixed cervical coronal imbalance, its efficacy and safety profile should be confirmed in larger cohorts.

Recurrent intraplate tectonism in the New Madrid seismic zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zoback, M.D.; Hamilton, R.M.; Crone, A.J.

1980-08-29

For the first time, New Madrid seismicity can be linked to specific structural features that have been reactivated through geologic time. Extensive seismic reflection profiling reveals major faults coincident with the main earthquake trends in the area and with structural deformation apparently caused by repeated episodes of igneous activity.

Flow number as a discriminating HMA mixture property : [project brief].

DOT National Transportation Integrated Search

2013-02-01

T he flow number test is used to measure the rutting potential of asphalt concrete mixtures. It is a variation of the repeated load, permanent deformation test that has been used by researchers since the 1970s. The flow number is one of three tests t...

Finite element analysis of the cyclic indentation of bilayer enamel

NASA Astrophysics Data System (ADS)

Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

2014-04-01

Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel.

Acute dark chocolate ingestion is beneficial for hemodynamics via enhancement of erythrocyte deformability in healthy humans.

PubMed

Radosinska, Jana; Horvathova, Martina; Frimmel, Karel; Muchova, Jana; Vidosovicova, Maria; Vazan, Rastislav; Bernatova, Iveta

2017-03-01

Erythrocyte deformability is an important property of erythrocytes that considerably affects blood flow and hemodynamics. The high content of polyphenols present in dark chocolate has been reported to play a protective role in functionality of erythrocytes. We hypothesized that chocolate might influence erythrocytes not only after repeated chronic intake, but also immediately after its ingestion. Thus, we determined the acute effect of dark chocolate and milk (with lower content of biologically active substances) chocolate intake on erythrocyte deformability. We also focused on selected factors that may affect erythrocyte deformability, specifically nitric oxide production in erythrocytes and total antioxidant capacity of plasma. We determined posttreatment changes in the mentioned parameters 2hours after consumption of chocolate compared with their levels before consumption of chocolate. In contrast to milk chocolate intake, the dark chocolate led to a significantly higher increase in erythrocyte deformability. Nitric oxide production in erythrocytes was not changed after dark chocolate intake, but significantly decreased after milk chocolate. The plasma total antioxidant capacity remained unaffected after ingestion of both chocolates. We conclude that our hypothesis was confirmed. Single ingestion of dark chocolate improved erythrocyte deformability despite unchanged nitric oxide production and antioxidant capacity of plasma. Increased deformability of erythrocytes may considerably improve rheological properties of blood and thus hemodynamics in humans, resulting in better tissue oxygenation. Copyright © 2017 Elsevier Inc. All rights reserved.

Field evidence for linking Altosid applications with increased amphibian deformities in southern leopard frogs [abstract

USGS Publications Warehouse

Sparling, D.W.

1998-01-01

During the summer of 1997 we repeatedly sprayed Altosid, a formulation of 4% methoprene used for mosquito control, on six constructed macrocosms. Six additional macrocosms were sprayed with Abate4E, containing the organophosphate pesticide temephos, and six were sprayed with water (controls). The wetlands were created on an impermeable foundation for research purposes and averaged 215 m2 in area and 0.5 m deep. Application rates and frequency of Abate4E and Altosid followed label directions and mimicked procedures for mosquito control in National Wildlife Refuges. In early September juvenile frogs and metamorphing tadpoles were collected with dip nets from each pond and examined for deformities. In all, 91 juveniles and metamorph southern leopard frogs (Rana utricularia) were collected from Altosid sprayed wetlands with 14 (15%) demonstrating deformities. Seventyseven juveniles and metamorphs were collected from control wetlands with three (4%) showing deformities. Only six juveniles and metamorphs were collected from Abate4E wetlands and none showed deformities. Deformities included missing or deformed hind limbs (9 of 10 involving only the right hind limb), missing eyes, and abnormal color. The differences in rate of deformities was dependent on treatment (X2=6.44, p< 0.02). The number of leopard frogs caught per unit effort (tadpoles and juveniles) differed among treatments (p=0.032) with Abate4E wetlands producing fewer individuals per capture effort than either Altosid or control wetlands.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katchadjian, Pablo, E-mail: katcha@cnea.gov.ar; Desimone, Carlos, E-mail: katcha@cnea.gov.ar; Garcia, Alejandro, E-mail: katcha@cnea.gov.ar

Embalse Nuclear Power Plant (CNE) (CANDU design) is reaching its end of life and due to elapsed operating time the problem of deformation by accelerated creep occurs in the pressure tubes (PT), leading to a possible contact between calandria tubes (CT), concentric to the PT, and some Liquid Injection Shutdown System (LISS) nozzles that pass underneath them. With determination of CT wear, after the predicted contact occurs, the wear rate of the TC could be determined and thus take less conservative measures over the remaining life of the component. This paper presents the development of an ultrasonic technique for measuringmore » wear in CT, with nominal thickness of 1.34 mm. Because the only access is through the interior of PT, to perform this measurement it is necessary to pass through three different interfaces.« less

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J.; Hugo, Geoffrey

Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), amore » novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter}=0.52±0.25, which was significantly lower than for intrafraction pairs (r{sup -}{sub Intra}=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV{sup -}{sub Inter}|=0.42±0.65 and |ΔV{sup -}{sub Intra}|=0.32±0.53, respectively (p < 10{sup −15}). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. Conclusions: The authors’ data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.« less

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging.

PubMed

Kipritidis, John; Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey; Keall, Paul J

2015-03-01

Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4-6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r̄(Inter)=0.52±0.25, which was significantly lower than for intrafraction pairs (r̄(Intra)=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV̄(Inter)|=0.42±0.65 and |ΔV̄(Intra)|=0.32±0.53, respectively (p < 10(-15)). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. The authors' data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.

Multiplexed fluidic plunger mechanism for the measurement of red blood cell deformability.

PubMed

Myrand-Lapierre, Marie-Eve; Deng, Xiaoyan; Ang, Richard R; Matthews, Kerryn; Santoso, Aline T; Ma, Hongshen

2015-01-07

The extraordinary deformability of red blood cells gives them the ability to repeatedly transit through the microvasculature of the human body. The loss of this capability is part of the pathology of a wide range of diseases including malaria, hemoglobinopathies, and micronutrient deficiencies. We report on a technique for multiplexed measurements of the pressure required to deform individual red blood cell through micrometer-scale constrictions. This measurement is performed by first infusing single red blood cells into a parallel array of ~1.7 μm funnel-shaped constrictions. Next, a saw-tooth pressure waveform is applied across the constrictions to squeeze each cell through its constriction. The threshold deformation pressure is then determined by relating the pressure-time data with the video of the deformation process. Our key innovation is a self-compensating fluidic network that ensures identical pressures are applied to each cell regardless of its position, as well as the presence of cells in neighboring constrictions. These characteristics ensure the consistency of the measurement process and robustness against blockages of the constrictions by rigid cells and debris. We evaluate this technique using in vitro cultures of RBCs infected with P. falciparum, the parasite that causes malaria, to demonstrate the ability to profile the deformability signature of a heterogeneous sample.

Brittle deformation during Alpine basal accretion and the origin of seismicity nests above the subduction interface

NASA Astrophysics Data System (ADS)

Menant, Armel; Angiboust, Samuel; Monié, Patrick; Oncken, Onno; Guigner, Jean-Michel

2018-04-01

Geophysical observations on active subduction zones have evidenced high seismicity clusters at 20-40 km depth in the fore-arc region whose origin remains controversial. We report here field observations of pervasive pseudotachylyte networks (interpreted as evidence for paleo-seismicity) in the now-exhumed Valpelline continental unit (Dent Blanche complex, NW. Alps, Italy), a tectonic sliver accreted to the upper plate at c. 30 km depth during the Paleocene Alpine subduction. Pre-alpine granulite-facies paragneiss from the core of the Valpelline unit are crosscut by widespread, mm to cm-thick pseudotachylyte veins. Co-seismic heating and subsequent cooling led to the formation of Ti-rich garnet rims, ilmenite needles, Ca-rich plagioclase, biotite microliths and hercynite micro-crystals. 39Ar-40Ar dating yields a 51-54 Ma age range for these veins, thus suggesting that frictional melting events occurred near peak burial conditions while the Valpelline unit was already inserted inside the duplex structure. In contrast, the base of the Valpelline unit underwent synchronous ductile and brittle, seismic deformation under water-bearing conditions followed by a re-equilibration at c. 40 Ma (39Ar-40Ar on retrograded pseudotachylyte veins) during exhumation-related deformation. Calculated rheological profiles suggest that pseudotachylyte veins from the dry core of the granulite unit record upper plate micro-seismicity (Mw 2-3) formed under very high differential stresses (>500 MPa) while the sheared base of the unit underwent repeated brittle-ductile deformation at much lower differential stresses (<40 MPa) in a fluid-saturated environment. These results demonstrate that some of the seismicity clusters nested along and above the plate interface may reflect the presence of stiff tectonic slivers rheologically analogous to the Valpelline unit acting as repeatedly breaking asperities in the basal accretion region of active subduction zones.

Water Surface Impact and Ricochet of Deformable Elastomeric Spheres

NASA Astrophysics Data System (ADS)

Hurd, Randy C.

Soft and deformable silicone rubber spheres ricochet from a water surface when rigid spheres and disks (or skipping stones) cannot. This dissertation investigates why these objects are able to skip so successfully. High speed cameras allow us to see that these unique spheres deform significantly as they impact the water surface, flattening into pancake-like shapes with greater area. Though the water entry behavior of deformable spheres deviates from that of rigid spheres, our research shows that if this deformation is accounted for, their behavior can be predicted from previously established methods. Soft spheres skip more easily because they deform significantly when impacting the water surface. We present a diagram which enables the prediction of a ricochet from sphere impact conditions such as speed and angle. Experiments and mathematical representations of the sphere skipping both show that these deformable spheres skip more readily because deformation momentarily increases sphere area and produces an attack angle with the water which is favorable to skipping. Predictions from our mathematical representation of sphere skipping agree strongly with observations from experiments. Even when a sphere was allowed to skip multiple times in the laboratory, the mathematical predictions show good agreement with measured impact conditions through subsequent skipping events. While studying multiple impact events in an outdoor setting, we discovered a previously unidentified means of skipping, which is unique to deformable spheres. This new skipping occurs when a relatively soft sphere first hits the water at a high speed and low impact angle and the sphere begins to rotate very quickly. This quick rotation causes the sphere to stretch into a shape similar to an American football and maintain this shape while it spins. The sphere is observed to move nearly parallel with the water surface with the tips of this "football" dipping into the water as it rotates and the sides passing just over the surface. This sequence of rapid impact events give the impression that the sphere is walking across the water surface.

Everything I Know about Teaching I Learned from Jazz

ERIC Educational Resources Information Center

Luquet, Wade

2015-01-01

The instant availability of information has changed the paradigm of teaching. Whereas at one time teaching and learning was information being passed, memorized, and repeated, students can now find their own knowledge. Learning now consists of using information in creative ways and requires a shift in how students are taught. This is quite similar…

The land-cover cascade: relationships coupling land and water

Treesearch

C.L. Burcher; H.M. Valett; E.F. Benfield

2007-01-01

We introduce the land-cover cascade (LCC) as a conceptual framework to quantify the transfer of land-cover-disturbance effects to stream biota. We hypothesize that disturbance is propagated through multivariate systems through key variables that transform a disturbance and pass a reorganized disturbance effect to the next hierarchical level where the process repeats...

Motivation and English Language Learning in a Multicultural University Context

ERIC Educational Resources Information Center

Bensoussan, Marsha

2015-01-01

Israeli university students who have difficulty reading academic texts in English are required to take reading comprehension courses in English for academic purposes (EAP) in order to complete their BA degree. Whereas most students pass the courses, some repeatedly fail. Since Israel is a multilingual country, there is also a question about…

First 5 Kern Annual Report, Fiscal Year 2011-2012

ERIC Educational Resources Information Center

Wang, Jianjun

2013-01-01

Scientific discoveries repeatedly confirmed the importance of brain growth during the first 5 years of child life. To support early childhood development, California voters passed Proposition 10 in 1998 to collect a 50 cent per pack tax on cigarettes and other tobacco products. Kern County Children and Families Commission (First 5 Kern) was…

Survival of diverse bacillus thuringiensis strains in gypsy moth (Lepidotera: Lymantriidae) is correlated with urease production

USDA-ARS?s Scientific Manuscript database

Bacillus thuringiensis is an entomopathogenic bacterium that can kill a variety of pest insects, but seldom causes epizootics because it replicates poorly in insects. By attempting to repeatedly pass lepidopteran-active B. thuringiensis strains through gypsy moth larvae, we found that only those str...

Direct and Passive Prenatal Nicotine Exposure and the Development of Externalizing Psychopathology

ERIC Educational Resources Information Center

Gatzke-Kopp, Lisa M.; Beauchaine, Theodore P.

2007-01-01

The association between maternal smoking during pregnancy and childhood antisocial outcomes has been demonstrated repeatedly across a variety of outcomes. Yet debate continues as to whether this association reflects a direct programming effect of nicotine on fetal brain development, or a phenotypic indicator of heritable liability passed from…

Results from the Maine 1992 foliage penetration experiment

NASA Astrophysics Data System (ADS)

Toups, Michael F.; Ayasli, Serpil

1993-11-01

In order to investigate the detection of targets which are hidden by foliage, an experiment was designed which utilized a forest region located near Portage, Maine. The experiment was designed to address four issues. First, the properties of the backscatter or clutter which competes with the desired target were investigated. Second, the foliage induced attenuation that is experienced by the radar energy traversing the foliage were measured. Third, the ability of a synthetic aperture radar system to focus on a target obscured by foliage was investigated. Fourth, target signatures of foliage obscured and unobscured targets were measured. The forest region was investigated using two different airborne synthetic aperture radar (SAR) systems. A UHF wide-band SAR operated by SRI International was used as well as a L-, C-, and X-band SAR installed on a P-3 aircraft operated by the U.S. Navy. The SRI system was used to collect data over 16 square kilometers with repeat passes for verification of system performance. The P-3 system was used to collect over 50 square kilometers of data at three different depression angles with several repeat passes.

A Unified Model for Repeating and Non-repeating Fast Radio Bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagchi, Manjari, E-mail: manjari@imsc.res.in

The model that fast radio bursts (FRBs) are caused by plunges of asteroids onto neutron stars can explain both repeating and non-repeating bursts. If a neutron star passes through an asteroid belt around another star, there would be a series of bursts caused by a series of asteroid impacts. Moreover, the neutron star would cross the same belt repetitively if it were in a binary with the star hosting the asteroid belt, leading to a repeated series of bursts. I explore the properties of neutron star binaries that could lead to the only known repeating FRB so far (FRB121102). Inmore » this model, the next two epochs of bursts are expected around 2017 February 27 and 2017 December 18. On the other hand, if the asteroid belt is located around the neutron star itself, then a chance fall of an asteroid from that belt onto the neutron star would lead to a non-repeating burst. Even a neutron star grazing an asteroid belt can lead to a non-repeating burst caused by just one asteroid plunge during the grazing. This is possible even when the neutron star is in a binary with the asteroid-hosting star, if the belt and the neutron star orbit are non-coplanar.« less

Comparative Validity and Reproducibility Study of Various Landmark-Oriented Reference Planes in 3-Dimensional Computed Tomographic Analysis for Patients Receiving Orthognathic Surgery

PubMed Central

Lin, Hsiu-Hsia; Chuang, Ya-Fang; Weng, Jing-Ling; Lo, Lun-Jou

2015-01-01

Background Three-dimensional computed tomographic imaging has become popular in clinical evaluation, treatment planning, surgical simulation, and outcome assessment for maxillofacial intervention. The purposes of this study were to investigate whether there is any correlation among landmark-based horizontal reference planes and to validate the reproducibility and reliability of landmark identification. Materials and Methods Preoperative and postoperative cone-beam computed tomographic images of patients who had undergone orthognathic surgery were collected. Landmark-oriented reference planes including the Frankfort horizontal plane (FHP) and the lateral semicircular canal plane (LSP) were established. Four FHPs were defined by selecting 3 points from the orbitale, porion, or midpoint of paired points. The LSP passed through both the lateral semicircular canal points and nasion. The distances between the maxillary or mandibular teeth and the reference planes were measured, and the differences between the 2 sides were calculated and compared. The precision in locating the landmarks was evaluated by performing repeated tests, and the intraobserver reproducibility and interobserver reliability were assessed. Results A total of 30 patients with facial deformity and malocclusion—10 patients with facial symmetry, 10 patients with facial asymmetry, and 10 patients with cleft lip and palate—were recruited. Comparing the differences among the 5 reference planes showed no statistically significant difference among all patient groups. Regarding intraobserver reproducibility, the mean differences in the 3 coordinates varied from 0 to 0.35 mm, with correlation coefficients between 0.96 and 1.0, showing high correlation between repeated tests. Regarding interobserver reliability, the mean differences among the 3 coordinates varied from 0 to 0.47 mm, with correlation coefficients between 0.88 and 1.0, exhibiting high correlation between the different examiners. Conclusions The 5 horizontal reference planes were reliable and comparable for 3D craniomaxillofacial analysis. These reference planes were useful in standardizing the orientation of 3D skull models. PMID:25668209

Comparative validity and reproducibility study of various landmark-oriented reference planes in 3-dimensional computed tomographic analysis for patients receiving orthognathic surgery.

PubMed

Lin, Hsiu-Hsia; Chuang, Ya-Fang; Weng, Jing-Ling; Lo, Lun-Jou

2015-01-01

Three-dimensional computed tomographic imaging has become popular in clinical evaluation, treatment planning, surgical simulation, and outcome assessment for maxillofacial intervention. The purposes of this study were to investigate whether there is any correlation among landmark-based horizontal reference planes and to validate the reproducibility and reliability of landmark identification. Preoperative and postoperative cone-beam computed tomographic images of patients who had undergone orthognathic surgery were collected. Landmark-oriented reference planes including the Frankfort horizontal plane (FHP) and the lateral semicircular canal plane (LSP) were established. Four FHPs were defined by selecting 3 points from the orbitale, porion, or midpoint of paired points. The LSP passed through both the lateral semicircular canal points and nasion. The distances between the maxillary or mandibular teeth and the reference planes were measured, and the differences between the 2 sides were calculated and compared. The precision in locating the landmarks was evaluated by performing repeated tests, and the intraobserver reproducibility and interobserver reliability were assessed. A total of 30 patients with facial deformity and malocclusion--10 patients with facial symmetry, 10 patients with facial asymmetry, and 10 patients with cleft lip and palate--were recruited. Comparing the differences among the 5 reference planes showed no statistically significant difference among all patient groups. Regarding intraobserver reproducibility, the mean differences in the 3 coordinates varied from 0 to 0.35 mm, with correlation coefficients between 0.96 and 1.0, showing high correlation between repeated tests. Regarding interobserver reliability, the mean differences among the 3 coordinates varied from 0 to 0.47 mm, with correlation coefficients between 0.88 and 1.0, exhibiting high correlation between the different examiners. The 5 horizontal reference planes were reliable and comparable for 3D craniomaxillofacial analysis. These reference planes were useful in standardizing the orientation of 3D skull models.

Link module for a downhole drilling network

DOEpatents

Hall, David R [Provo, UT; Fox, Joe [Provo, UT

2007-05-29

A repeater is disclosed in one embodiment of the present invention as including a cylindrical housing, characterized by a proximal end and a distal end, and having a substantially cylindrical wall, the cylindrical wall defining a central bore passing therethrough. The cylindrical housing is formed to define at least one recess in the cylindrical wall, into which a repeater is inserted. The cylindrical housing also includes an annular recess formed into at least one of the proximal end and the distal end. An annular transmission element, operably connected to the repeater, is located in the annular recess. In selected embodiments, the annular transmission element inductively converts electrical energy to magnetic energy. In other embodiments, the annular transmission element includes an electrical contact to transmit electrical energy directly to another contact.

In situ measurement on TSV-Cu deformation with hotplate system based on sheet resistance

NASA Astrophysics Data System (ADS)

Sun, Yunna; Wang, Bo; Wang, Huiying; Wu, Kaifeng; Yang, Shengyong; Wang, Yan; Ding, Guifu

2017-12-01

The in situ measurement of TSVs deformation at different temperature is meaningful for learning more about the thermal deformation schemes of 3D TSVs in the microelectronic devices. An efficient and smart hotplate based on sheet resistance is designed for offering more heat, producing a uniform temperature distribution, relieving thermal stress and heat concentration issues, and reducing room space, which was optimized by the finite element method (FEM). The fabricated hotplate is efficient and smart (2.5 cm  ×  2.0 cm  ×  0.5 cm) enough to be located in the limited space during measuring. The thermal infrared imager was employed as the temperature sensor for monitoring the temperature distribution of TSVs sample. The 3D profilometry was adopted as the observer for TSVs profiles survey. The in situ 2D top surface profiles and 3D displacement profiles of TSVs sample at the different temperature were measured by 3D profilometer. The in situ average relative deformation and effective plastic deformation of the TSV sample were measured. With optical measurement method, 3D profilometry, the TSV sample can be tested repeatedly.

Multiband product rule and consonant identification.

PubMed

Li, Feipeng; Allen, Jont B

2009-07-01

The multiband product rule, also known as band-independence, is a basic assumption of articulation index and its extension, the speech intelligibility index. Previously Fletcher showed its validity for a balanced mix of 20% consonant-vowel (CV), 20% vowel-consonant (VC), and 60% consonant-vowel-consonant (CVC) sounds. This study repeats Miller and Nicely's version of the hi-/lo-pass experiment with minor changes to study band-independence for the 16 Miller-Nicely consonants. The cut-off frequencies are chosen such that the basilar membrane is evenly divided into 12 segments from 250 to 8000 Hz with the high-pass and low-pass filters sharing the same six cut-off frequencies in the middle. Results show that the multiband product rule is statistically valid for consonants on average. It also applies to subgroups of consonants, such as stops and fricatives, which are characterized by a flat distribution of speech cues along the frequency. It fails for individual consonants.

Demonstration of the feasibility of large-port-count optical switching using a hybrid Mach-Zehnder interferometer-semiconductor optical amplifier switch module in a recirculating loop.

PubMed

Cheng, Q; Wonfor, A; Wei, J L; Penty, R V; White, I H

2014-09-15

For what we believe is the first time, the feasibility of large-port-count nanosecond-reconfiguration-time optical switches is demonstrated using a hybrid approach, where Mach-Zehnder interferometric (MZI) switches provide low-loss, high-speed routing with short semiconductor optical amplifiers (SOAs) being integrated to enhance extinction. By repeatedly passing signals through a monolithic hybrid dilated 2×2 switch module in a recirculating loop, the potential performance of high-port-count switches using the hybrid approach is demonstrated. Experimentally, a single pass switch penalty of only 0.1 dB is demonstrated for the 2×2 module, while even after seven passes through the switch, equivalent to a 128×128 router, a penalty of only 2.4 dB is recorded at a data rate of 10 Gb/s.

Skill execution and sleep deprivation: effects of acute caffeine or creatine supplementation - a randomized placebo-controlled trial

PubMed Central

2011-01-01

Background We investigated the effects of sleep deprivation with or without acute supplementation of caffeine or creatine on the execution of a repeated rugby passing skill. Method Ten elite rugby players completed 10 trials on a simple rugby passing skill test (20 repeats per trial), following a period of familiarisation. The players had between 7-9 h sleep on 5 of these trials and between 3-5 h sleep (deprivation) on the other 5. At a time of 1.5 h before each trial, they undertook administration of either: placebo tablets, 50 or 100 mg/kg creatine, 1 or 5 mg/kg caffeine. Saliva was collected before each trial and assayed for salivary free cortisol and testosterone. Results Sleep deprivation with placebo application resulted in a significant fall in skill performance accuracy on both the dominant and non-dominant passing sides (p < 0.001). No fall in skill performance was seen with caffeine doses of 1 or 5 mg/kg, and the two doses were not significantly different in effect. Similarly, no deficit was seen with creatine administration at 50 or 100 mg/kg and the performance effects were not significantly different. Salivary testosterone was not affected by sleep deprivation, but trended higher with the 100 mg/kg creatine dose, compared to the placebo treatment (p = 0.067). Salivary cortisol was elevated (p = 0.001) with the 5 mg/kg dose of caffeine (vs. placebo). Conclusion Acute sleep deprivation affects performance of a simple repeat skill in elite athletes and this was ameliorated by a single dose of either caffeine or creatine. Acute creatine use may help to alleviate decrements in skill performance in situations of sleep deprivation, such as transmeridian travel, and caffeine at low doses appears as efficacious as higher doses, at alleviating sleep deprivation deficits in athletes with a history of low caffeine use. Both options are without the side effects of higher dose caffeine use. PMID:21324203

Skill execution and sleep deprivation: effects of acute caffeine or creatine supplementation - a randomized placebo-controlled trial.

PubMed

Cook, Christian J; Crewther, Blair T; Kilduff, Liam P; Drawer, Scott; Gaviglio, Chris M

2011-02-16

We investigated the effects of sleep deprivation with or without acute supplementation of caffeine or creatine on the execution of a repeated rugby passing skill. Ten elite rugby players completed 10 trials on a simple rugby passing skill test (20 repeats per trial), following a period of familiarisation. The players had between 7-9 h sleep on 5 of these trials and between 3-5 h sleep (deprivation) on the other 5. At a time of 1.5 h before each trial, they undertook administration of either: placebo tablets, 50 or 100 mg/kg creatine, 1 or 5 mg/kg caffeine. Saliva was collected before each trial and assayed for salivary free cortisol and testosterone. Sleep deprivation with placebo application resulted in a significant fall in skill performance accuracy on both the dominant and non-dominant passing sides (p < 0.001). No fall in skill performance was seen with caffeine doses of 1 or 5 mg/kg, and the two doses were not significantly different in effect. Similarly, no deficit was seen with creatine administration at 50 or 100 mg/kg and the performance effects were not significantly different. Salivary testosterone was not affected by sleep deprivation, but trended higher with the 100 mg/kg creatine dose, compared to the placebo treatment (p = 0.067). Salivary cortisol was elevated (p = 0.001) with the 5 mg/kg dose of caffeine (vs. placebo). Acute sleep deprivation affects performance of a simple repeat skill in elite athletes and this was ameliorated by a single dose of either caffeine or creatine. Acute creatine use may help to alleviate decrements in skill performance in situations of sleep deprivation, such as transmeridian travel, and caffeine at low doses appears as efficacious as higher doses, at alleviating sleep deprivation deficits in athletes with a history of low caffeine use. Both options are without the side effects of higher dose caffeine use.

Reconciling short recurrence intervals with minor deformation in the new madrid seismic zone.

PubMed

Schweig, E S; Ellis, M A

1994-05-27

At least three great earthquakes occurred in the New Madrid seismic zone in 1811 and 1812. Estimates of present-day strain rates suggest that such events may have a repeat time of 1000 years or less. Paleoseismological data also indicate that earthquakes large enough to cause soil liquefaction have occurred several times in the past 5000 years. However, pervasive crustal deformation expected from such a high frequency of large earthquakes is not observed. This suggests that the seismic zone is a young feature, possibly as young as several tens of thousands of years old and no more than a few million years old.

Production of ultrafine grained aluminum by cyclic severe plastic deformation at ambient temperature

NASA Astrophysics Data System (ADS)

Bereczki, P.; Szombathelyi, V.; Krallics, G.

2014-08-01

In the present study the possibilities of grain refinement was investigated by applying large-scale of cyclic plastic deformation to aluminum at ambient temperature. The specimens are processed by multiaxial forging, which is one of the severe plastic deformation techniques. The aim of the experiments with the aluminum alloy 6082M was the determination of the equivalent stress and strain by multiaxial forging and the investigation of evolution of mechanical properties in relation with the accumulated deformation in the specimen. The mechanical properties of raw material was determined by plane strain compression test as well as by hardness measurements. The forming experiments were carried out on Gleeble 3800 physical simulator with MaxStrain System. The mechanical properties of the forged specimens were investigated by micro hardness measurements and tensile tests. A mechanical model, based on the principle of virtual velocities was developed to calculate the flow curves using the measured dimensional changes of the specimen and the measured force. With respect to the evolution of these curves, the cyclic growth of the flow stress can be observed at every characteristic points of the calculated flow curves. In accordance with this tendency, the evolution of the hardness along the middle cross section of the deformed volume has also a nonmonotonous characteristic and the magnitudes of these values are much smaller than by the specimen after plane strain compression test. This difference between the flow stresses respect to the monotonic and non-monotonic deformation can be also observed. The formed microstructure, after a 10-passes multiaxial forging process, consists of mainly equiaxial grains in the submicron grain scale.

Terrestrial-style slow-moving earthflow kinematics in a submarine landslide complex

Treesearch

Joshu J. Mountjoy; Jim McKean; Philip M. Barnes; Jarg R. Pettinga

2009-01-01

Morphometric analysis of Simrad EM300 multibeam bathymetric DEMs reveals details of deformation patterns in a ~145 km2 submarine landslide complex that are commonly associated with slow-moving earthflows in terrestrial settings. This mode of failure, where existing landslide debris is remobilised repeatedly along discrete shear boundaries and is...

[Fractography of the long tubular bones of the lower extremities in trauma by blunt objects].

PubMed

Kriukov, V N; Bakhmet'ev, V I

1991-01-01

New data on micromorphological signs of fracture of long tubular bones in normal distribution and transformation of deforming forces are presented. Fractographic signs of bone for each destructive stage, signs of repeated trauma are singled out. Interrelationship between bone microstructure and conditions of its destruction is stated.

Compensation method for obtaining accurate, sub-micrometer displacement measurements of immersed specimens using electronic speckle interferometry.

PubMed

Fazio, Massimo A; Bruno, Luigi; Reynaud, Juan F; Poggialini, Andrea; Downs, J Crawford

2012-03-01

We proposed and validated a compensation method that accounts for the optical distortion inherent in measuring displacements on specimens immersed in aqueous solution. A spherically-shaped rubber specimen was mounted and pressurized on a custom apparatus, with the resulting surface displacements recorded using electronic speckle pattern interferometry (ESPI). Point-to-point light direction computation is achieved by a ray-tracing strategy coupled with customized B-spline-based analytical representation of the specimen shape. The compensation method reduced the mean magnitude of the displacement error induced by the optical distortion from 35% to 3%, and ESPI displacement measurement repeatability showed a mean variance of 16 nm at the 95% confidence level for immersed specimens. The ESPI interferometer and numerical data analysis procedure presented herein provide reliable, accurate, and repeatable measurement of sub-micrometer deformations obtained from pressurization tests of spherically-shaped specimens immersed in aqueous salt solution. This method can be used to quantify small deformations in biological tissue samples under load, while maintaining the hydration necessary to ensure accurate material property assessment.

Pseudotachylyte as field evidence for lower-crustal earthquakes during the intracontinental Petermann Orogeny (Musgrave Block, Central Australia)

NASA Astrophysics Data System (ADS)

Hawemann, Friedrich; Mancktelow, Neil S.; Wex, Sebastian; Camacho, Alfredo; Pennacchioni, Giorgio

2018-05-01

Geophysical evidence for lower continental crustal earthquakes in almost all collisional orogens is in conflict with the widely accepted notion that rocks, under high grade conditions, should flow rather than fracture. Pseudotachylytes are remnants of frictional melts generated during seismic slip and can therefore be used as an indicator of former seismogenic fault zones. The Fregon Subdomain in Central Australia was deformed under dry sub-eclogitic conditions of 600-700 °C and 1.0-1.2 GPa during the intracontinental Petermann Orogeny (ca. 550 Ma) and contains abundant pseudotachylyte. These pseudotachylytes are commonly foliated, recrystallized, and cross-cut by other pseudotachylytes, reflecting repeated generation during ongoing ductile deformation. This interplay is interpreted as evidence for repeated seismic brittle failure and post- to inter-seismic creep under dry lower-crustal conditions. Thermodynamic modelling of the pseudotachylyte bulk composition gives the same PT conditions of shearing as in surrounding mylonites. We conclude that pseudotachylytes in the Fregon Subdomain are a direct analogue of current seismicity in dry lower continental crust.

Implications of Microstructural Studies of the SAFOD Gouge for the Strength and Deformation Mechanisms in the Creeping Segment of the San Andreas Fault

NASA Astrophysics Data System (ADS)

Hadizadeh, J.; Gratier, J. L.; Mittempergher, S.; Renard, F.; Richard, J.; di Toro, G.; Babaie, H. A.

2010-12-01

The San Andreas Fault zone (SAF) in the vicinity of the San Andreas Fault Observatory at Depth (SAFOD)in central California is characterized by an average 21 mm/year aseismic creep and strain release through repeating M<3 earthquakes. Seismic inversion studies indicate that the ruptures occur on clusters of stationary patches making up 1% or less of the total fault surface area. The existence of these so-called asperity patches, although not critical in determining the fault strength, suggests interaction of different deformation mechanisms. What are the deformation mechanisms, and how do the mechanisms couple and factor into the current strength models for the SAF? The SAFOD provides core samples and geophysical data including cores from two shear zones where the main borehole casing is deforming. The studies so far show a weak fault zone with about 200m of low-permeability damage zone without anomalous temperature or high fluid pressure (Zoback et al. EOS 2010). To answer the above questions, we studied core samples and thin sections ranging in measured depths (MD) from 3059m to 3991m including gouge from borehole casing deformation zones. The methods of study included high resolution scanning and transmission electron microscopy, cathodoluminescence imaging, X-ray fluorescence mapping, and energy dispersive X-ray spectroscopy. The microstructural and analytical data suggest that deformation is by a coupling of cataclastic flow and pressure solution accompanied by widespread alteration of feldspar to clay minerals and other neomineralizations. The clay contents of the gouge and streaks of serpentinite are not uniformly distributed, but weakness of the creeping segment is likely to be due to intrinsically low frictional strength of the fault material. This conclusion, which is based on the overall ratio of clay/non-clay constituents and the presence of talc in the actively deforming zones, is consistent with the 0.3-0.45 coefficient of friction for the drill cuttings tested by others. We also considered weakening by diffusion-accommodated grain boundary sliding. There are two main trends in the microstructural data that provide a basis for explaining the creep rate and seismic activity: 1. Clay content of the gouge including serpentinite and talc increases toward the 1-3m wide borehole casing deformation zones, which are expected to be deforming at above the average creep rate 2. Evidence of pressure solution creep and fracture sealing is more abundant in the siltstone cataclasites than in the shale. Such rocks could act as rigid inclusions that are repeatedly loaded to seismic failure by creep of the surrounding clay gouge. Regular cycles of fracture and restrengthening by fracture sealing in and around the inclusions are thus expected. The inclusions may be viewed as asperity patches (or cluster of patches) that predominantly deform by pressure solution at below the average creep rate.

The Impact of Moderate and High Intensity Total Body Fatigue on Passing Accuracy in Expert and Novice Basketball Players

PubMed Central

Lyons, Mark; Al-Nakeeb, Yahya; Nevill, Alan

2006-01-01

Despite the acknowledged importance of fatigue on performance in sport, ecologically sound studies investigating fatigue and its effects on sport-specific skills are surprisingly rare. The aim of this study was to investigate the effect of moderate and high intensity total body fatigue on passing accuracy in expert and novice basketball players. Ten novice basketball players (age: 23.30 ± 1.05 yrs) and ten expert basketball players (age: 22.50 ± 0.41 yrs) volunteered to participate in the study. Both groups performed the modified AAHPERD Basketball Passing Test under three different testing conditions: rest, moderate intensity and high intensity total body fatigue. Fatigue intensity was established using a percentage of the maximal number of squat thrusts performed by the participant in one minute. ANOVA with repeated measures revealed a significant (F 2,36 = 5.252, p = 0.01) level of fatigue by level of skill interaction. On examination of the mean scores it is clear that following high intensity total body fatigue there is a significant detriment in the passing performance of both novice and expert basketball players when compared to their resting scores. Fundamentally however, the detrimental impact of fatigue on passing performance is not as steep in the expert players compared to the novice players. The results suggest that expert or skilled players are better able to cope with both moderate and high intensity fatigue conditions and maintain a higher level of performance when compared to novice players. The findings of this research therefore, suggest the need for trainers and conditioning coaches in basketball to include moderate, but particularly high intensity exercise into their skills sessions. This specific training may enable players at all levels of the game to better cope with the demands of the game on court and maintain a higher standard of play. Key Points Aim: to investigate the effect of moderate and high intensity total body fatigue on basketball-passing accuracy in expert and novice basketball players. Fatigue intensity was set as a percentage of the maximal number of squat thrusts performed by the participant in one minute. ANOVA with repeated measures revealed a significant level of fatigue by level of skill interaction. Despite a significant detriment in passing-performance in both novice and expert players following high intensity total body fatigue, this detriment was not as steep in the expert players when compared to the novice players PMID:24259994

Linear friction weld process monitoring of fixture cassette deformations using empirical mode decomposition

NASA Astrophysics Data System (ADS)

Bakker, O. J.; Gibson, C.; Wilson, P.; Lohse, N.; Popov, A. A.

2015-10-01

Due to its inherent advantages, linear friction welding is a solid-state joining process of increasing importance to the aerospace, automotive, medical and power generation equipment industries. Tangential oscillations and forge stroke during the burn-off phase of the joining process introduce essential dynamic forces, which can also be detrimental to the welding process. Since burn-off is a critical phase in the manufacturing stage, process monitoring is fundamental for quality and stability control purposes. This study aims to improve workholding stability through the analysis of fixture cassette deformations. Methods and procedures for process monitoring are developed and implemented in a fail-or-pass assessment system for fixture cassette deformations during the burn-off phase. Additionally, the de-noised signals are compared to results from previous production runs. The observed deformations as a consequence of the forces acting on the fixture cassette are measured directly during the welding process. Data on the linear friction-welding machine are acquired and de-noised using empirical mode decomposition, before the burn-off phase is extracted. This approach enables a direct, objective comparison of the signal features with trends from previous successful welds. The capacity of the whole process monitoring system is validated and demonstrated through the analysis of a large number of signals obtained from welding experiments.

Dynamic strength of cylindrical fiber-glass shells and basalt plastic shells under multiple explosive loading

NASA Astrophysics Data System (ADS)

Syrunin, M. A.; Fedorenko, A. G.

2006-08-01

We have shown experimentally that, for cylindrical shells made of oriented fiberglass platic and basalt plastic there exists a critical level of deformations, at which a structure sustains a given number of explosions from the inside. The magnitude of critical deformation for cylindrical fiberglass shells depends linearly on the logarithm of the number of loads that cause failure. For a given type of fiberglass, there is a limiting level of explosive action, at which the number of loads that do not lead to failure can be sufficiently large (more than ˜ 102). This level is attained under loads, which are an order of magnitude lower than the limiting loads under a single explosive action. Basalt plastic shells can be repeatedly used even at the loads, which cause deformation by ˜ 30-50% lower than the safe value ˜ 3.3.5% at single loading.

On-Chip Quantitative Measurement of Mechanical Stresses During Cell Migration with Emulsion Droplets

NASA Astrophysics Data System (ADS)

Molino, D.; Quignard, S.; Gruget, C.; Pincet, F.; Chen, Y.; Piel, M.; Fattaccioli, J.

2016-07-01

The ability of immune cells to migrate within narrow and crowded spaces is a critical feature involved in various physiological processes from immune response to metastasis. Several in-vitro techniques have been developed so far to study the behaviour of migrating cells, the most recent being based on the fabrication of microchannels within which cells move. To address the question of the mechanical stress a cell is able to produce during the encounter of an obstacle while migrating, we developed a hybrid microchip made of parallel PDMS channels in which oil droplets are sparsely distributed and serve as deformable obstacles. We thus show that cells strongly deform droplets while passing them. Then, we show that the microdevice can be used to study the influence of drugs on migration at the population level. Finally, we describe a quantitative analysis method of the droplet deformation that allows measuring in real-time the mechanical stress exerted by a single cell. The method presented herein thus constitutes a powerful analytical tool for cell migration studies under confinement.

Effect of aspect ratio and deformability on nanoparticle extravasation through nanopores.

PubMed

Kersey, Farrell R; Merkel, Timothy J; Perry, Jillian L; Napier, Mary E; DeSimone, Joseph M

2012-06-12

We describe the fabrication of filamentous hydrogel nanoparticles using a unique soft lithography based particle molding process referred to as PRINT (particle replication in nonwetting templates). The nanoparticles possess a constant width of 80 nm, and we varied their lengths ranging from 180 to 5000 nm. In addition to varying the aspect ratio of the particles, the deformability of the particles was tuned by varying the cross-link density within the particle matrix. Size characteristics such as hydrodynamic diameter and persistence length of the particles were analyzed using dynamic light scattering and electron microscopy techniques, respectively, while particle deformability was assessed by atomic force microscopy. Additionally, the ability of the particles to pass through membranes containing 0.2 μm pores was assessed by means of a simple filtration technique, and particle recovery was determined using fluorescence spectroscopy. The results show that particle recovery is mostly independent of aspect ratio at all cross-linker concentrations utilized, with the exception of 96 wt % PEG diacrylate 80 × 5000 nm particles, which showed the lowest percent recovery.

Mathematical Investigations for Supporting Pre-Service Primary Teachers Repeating a Mathematics Education Course

ERIC Educational Resources Information Center

Bailey, Judy

2014-01-01

Preparing to become an effective primary school mathematics teacher is a challenging and complex task; and is influenced by one's past experiences, personal knowledge of, and beliefs and attitudes towards mathematics. This paper examines the experiences of a small group of pre-service teachers who did not pass their first year mathematics…

Energy in a String Wave

ERIC Educational Resources Information Center

Ng, Chiu-king

2010-01-01

When one end of a taut horizontal elastic string is shaken repeatedly up and down, a transverse wave (assume sine waveform) will be produced and travel along it. College students know this type of wave motion well. They know when the wave passes by, each element of the string will perform an oscillating up-down motion, which in mechanics is termed…

Automatic ultrasonic inspection system for wear determination in calandria tubes of Embalse Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Katchadjian, Pablo; Desimone, Carlos; Garcia, Alejandro; Antonaccio, Carlos; Schroeter, Fernando; Molina, Héctor

2015-03-01

Embalse Nuclear Power Plant (CNE) (CANDU design) is reaching its end of life and due to elapsed operating time the problem of deformation by accelerated creep occurs in the pressure tubes (PT), leading to a possible contact between calandria tubes (CT), concentric to the PT, and some Liquid Injection Shutdown System (LISS) nozzles that pass underneath them. With determination of CT wear, after the predicted contact occurs, the wear rate of the TC could be determined and thus take less conservative measures over the remaining life of the component. This paper presents the development of an ultrasonic technique for measuring wear in CT, with nominal thickness of 1.34 mm. Because the only access is through the interior of PT, to perform this measurement it is necessary to pass through three different interfaces.

Adaptive Optics at Lawrence Livermore National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavel, D T

2003-03-10

Adaptive optics enables high resolution imaging through the atmospheric by correcting for the turbulent air's aberrations to the light waves passing through it. The Lawrence Livermore National Laboratory for a number of years has been at the forefront of applying adaptive optics technology to astronomy on the world's largest astronomical telescopes, in particular at the Keck 10-meter telescope on Mauna Kea, Hawaii. The technology includes the development of high-speed electrically driven deformable mirrors, high-speed low-noise CCD sensors, and real-time wavefront reconstruction and control hardware. Adaptive optics finds applications in many other areas where light beams pass through aberrating media andmore » must be corrected to maintain diffraction-limited performance. We describe systems and results in astronomy, medicine (vision science), and horizontal path imaging, all active programs in our group.« less

Simulation-Based Training for Colonoscopy

PubMed Central

Preisler, Louise; Svendsen, Morten Bo Søndergaard; Nerup, Nikolaj; Svendsen, Lars Bo; Konge, Lars

2015-01-01

Abstract The aim of this study was to create simulation-based tests with credible pass/fail standards for 2 different fidelities of colonoscopy models. Only competent practitioners should perform colonoscopy. Reliable and valid simulation-based tests could be used to establish basic competency in colonoscopy before practicing on patients. Twenty-five physicians (10 consultants with endoscopic experience and 15 fellows with very little endoscopic experience) were tested on 2 different simulator models: a virtual-reality simulator and a physical model. Tests were repeated twice on each simulator model. Metrics with discriminatory ability were identified for both modalities and reliability was determined. The contrasting-groups method was used to create pass/fail standards and the consequences of these were explored. The consultants significantly performed faster and scored higher than the fellows on both the models (P < 0.001). Reliability analysis showed Cronbach α = 0.80 and 0.87 for the virtual-reality and the physical model, respectively. The established pass/fail standards failed one of the consultants (virtual-reality simulator) and allowed one fellow to pass (physical model). The 2 tested simulations-based modalities provided reliable and valid assessments of competence in colonoscopy and credible pass/fail standards were established for both the tests. We propose to use these standards in simulation-based training programs before proceeding to supervised training on patients. PMID:25634177

Ultrasound-induced oscillations of gas bubbles in contact with gelatin gel surfaces

NASA Astrophysics Data System (ADS)

Fukui, Sosuke; Ando, Keita

2017-11-01

Ultrasound-induced dynamics of gas bubbles in the vicinity of deformable boundaries are studied experimentally, as a simplified model of sonoporation in medicine. In our experiment, 28-kHz underwater ultrasound was irradiated to a gas bubble nuclei (of radius from 60 μm to 200 μm) sitting at gel surfaces (of gelatin concentration from 6 wt% to 16 wt%) and the bubble dynamics were recorded by a high-speed camera. The repeated deformation of the gel surface was found to be in phase with volumetric oscillation of the bubble. A liquid jet, which can appear toward the collapse phase in the bubble oscillation in volume, produced localized surface deformation, which is an important observation in the context of sonoporation. We characterize the maximum displacement of the gel surface with varying the bubble nuclei radius (in comparison to the resonant radius fixed approximately at 117 μm). We also examine the phase difference between the ultrasound and the bubble dynamics under the influence of the deformable boundary. The Research Grant of Keio Leading-edge Laboratory of Science & Technology.

Improvement of the thermo-mechanical position stability of the beam position monitor in the PLS-II

NASA Astrophysics Data System (ADS)

Ha, Taekyun; Hong, Mansu; Kwon, Hyuckchae; Han, Hongsik; Park, Chongdo

2016-09-01

In the storage ring of the Pohang Light Source-II (PLS-II), we reduced the mechanical displacement of the electron-beam position monitors (e-BPMs) that is caused by heating during e-beam storage. The BPM pickup itself must be kept stable to sub-micrometer precision in order for a stable photon beam to be provided to beamlines because the orbit feedback system is programmed to make the electron beam pass through the center of the BPM. Thermal deformation of the vacuum chambers on which the BPM pickups are mounted is inevitable when the electron beam current is changed by an unintended beam abort. We reduced this deformation by improving the vacuum chamber support and by enhancing the water cooling. We report a thermo-mechanical analysis and displacement measurements for the BPM pickups after improvements.

Correction of large amplitude wavefront aberrations

NASA Astrophysics Data System (ADS)

Cornelissen, S. A.; Bierden, P. A.; Bifano, T. G.; Webb, R. H.; Burns, S.; Pappas, S.

2005-12-01

Recently, a number of research groups around the world have developed ophthalmic instruments capable of in vivo diffraction limited imaging of the human retina. Adaptive optics was used in these systems to compensate for the optical aberrations of the eye and provide high contrast, high resolution images. Such compensation uses a wavefront sensor and a wavefront corrector (usually a deformable mirror) coordinated in a closed- loop control system that continuously works to counteract aberrations. While those experiments produced promising results, the deformable mirrors have had insufficient range of motion to permit full correction of the large amplitude aberrations of the eye expected in a normal population of human subjects. Other retinal imaging systems developed to date with MEMS (micro-electromechanical systems) DMs suffer similar limitations. This paper describes the design, manufacture and testing of a 6um stroke polysilicon surface micromachined deformable mirror that, coupled with an new optical method to double the effective stroke of the MEMS-DM, will permit diffraction-limited retinal imaging through dilated pupils in at least 90% of the human population. A novel optical design using spherical mirrors provides a double pass of the wavefront over the deformable mirror such that a 6um mirror displacement results in 12um of wavefront compensation which could correct for 24um of wavefront error. Details of this design are discussed. Testing of the effective wavefront modification was performed using a commercial wavefront sensor. Results are presented demonstrating improvement in the amplitude of wavefront control using an existing high degree of freedom MEMS deformable mirror.

Optimization of deformation monitoring networks using finite element strain analysis

NASA Astrophysics Data System (ADS)

Alizadeh-Khameneh, M. Amin; Eshagh, Mehdi; Jensen, Anna B. O.

2018-04-01

An optimal design of a geodetic network can fulfill the requested precision and reliability of the network, and decrease the expenses of its execution by removing unnecessary observations. The role of an optimal design is highlighted in deformation monitoring network due to the repeatability of these networks. The core design problem is how to define precision and reliability criteria. This paper proposes a solution, where the precision criterion is defined based on the precision of deformation parameters, i. e. precision of strain and differential rotations. A strain analysis can be performed to obtain some information about the possible deformation of a deformable object. In this study, we split an area into a number of three-dimensional finite elements with the help of the Delaunay triangulation and performed the strain analysis on each element. According to the obtained precision of deformation parameters in each element, the precision criterion of displacement detection at each network point is then determined. The developed criterion is implemented to optimize the observations from the Global Positioning System (GPS) in Skåne monitoring network in Sweden. The network was established in 1989 and straddled the Tornquist zone, which is one of the most active faults in southern Sweden. The numerical results show that 17 out of all 21 possible GPS baseline observations are sufficient to detect minimum 3 mm displacement at each network point.

Mitigation of tropospheric InSAR phase artifacts through differential multisquint processing

NASA Technical Reports Server (NTRS)

Chen, Curtis W.

2004-01-01

We propose a technique for mitigating tropospheric phase errors in repeat-pass interferometric synthetic aperture radar (InSAR). The mitigation technique is based upon the acquisition of multisquint InSAR data. On each satellite pass over a target area, the radar instrument will acquire images from multiple squint (azimuth) angles, from which multiple interferograms can be formed. The diversity of viewing angles associated with the multisquint acquisition can be used to solve for two components of the 3-D surface displacement vector as well as for the differential tropospheric phase. We describe a model for the performance of the multisquint technique, and we present an assessment of the performance expected.

Graph Coarsening for Path Finding in Cybersecurity Graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogan, Emilie A.; Johnson, John R.; Halappanavar, Mahantesh

2013-01-01

n the pass-the-hash attack, hackers repeatedly steal password hashes and move through a computer network with the goal of reaching a computer with high level administrative privileges. In this paper we apply graph coarsening in network graphs for the purpose of detecting hackers using this attack or assessing the risk level of the network's current state. We repeatedly take graph minors, which preserve the existence of paths in the graph, and take powers of the adjacency matrix to count the paths. This allows us to detect the existence of paths as well as find paths that have high risk ofmore » being used by adversaries.« less

Test-retest reliability and minimal detectable change of two simplified 3-point balance measures in patients with stroke.

PubMed

Chen, Yi-Miau; Huang, Yi-Jing; Huang, Chien-Yu; Lin, Gong-Hong; Liaw, Lih-Jiun; Lee, Shih-Chieh; Hsieh, Ching-Lin

2017-10-01

The 3-point Berg Balance Scale (BBS-3P) and 3-point Postural Assessment Scale for Stroke Patients (PASS-3P) were simplified from the BBS and PASS to overcome the complex scoring systems. The BBS-3P and PASS-3P were more feasible in busy clinical practice and showed similarly sound validity and responsiveness to the original measures. However, the reliability of the BBS-3P and PASS-3P is unknown limiting their utility and the interpretability of scores. We aimed to examine the test-retest reliability and minimal detectable change (MDC) of the BBS-3P and PASS-3P in patients with stroke. Cross-sectional study. The rehabilitation departments of a medical center and a community hospital. A total of 51 chronic stroke patients (64.7% male). Both balance measures were administered twice 7 days apart. The test-retest reliability of both the BBS-3P and PASS-3P were examined by intraclass correlation coefficients (ICC). The MDC and its percentage over the total score (MDC%) of each measure was calculated for examining the random measurement errors. The ICC values of the BBS-3P and PASS-3P were 0.99 and 0.97, respectively. The MDC% (MDC) of the BBS-3P and PASS-3P were 9.1% (5.1 points) and 8.4% (3.0 points), respectively, indicating that both measures had small and acceptable random measurement errors. Our results showed that both the BBS-3P and the PASS-3P had good test-retest reliability, with small and acceptable random measurement error. These two simplified 3-level balance measures can provide reliable results over time. Our findings support the repeated administration of the BBS-3P and PASS-3P to monitor the balance of patients with stroke. The MDC values can help clinicians and researchers interpret the change scores more precisely.

Kinematic Model for the Sierra Nevada Frontal Fault Zone, California: Paleomagnetism of the Eureka Valley Tuff

NASA Astrophysics Data System (ADS)

Rood, D. H.; Burbank, D. W.; Luyendyk, B. P.

2005-12-01

We document the geometry, timing, rates, and kinematic style of Late Tertiary deformation between Sonora Pass and Mono Basin, central Sierra Nevada, California. Observed mismatches between geodetic and geologic deformation rates in the western Great Basin may be primarily due to underestimates of true geologic deformation. Relatively little attention has been paid to the role of permanent deformation between faults, i.e. folding or crustal block rotation. Current slip discrepancies may be accounted for if a significant component of off-fault transrotational deformation is present. We use geologic and paleomagnetic data to address the kinematic development of the Sierra Nevada frontal fault zone (SNFFZ), and to quantify both the elastic and inelastic strain accumulated across the Sierra Nevada-Basin and Range transition since ~9 Ma. The complex structure of this transition, between the regions of Sonora Pass and Mono Basin, may be a result of three distinct modes of dextral shear accommodation (transtensional, transpressional, and crustal thinning). The study area is characterized by four important structural elements that lie between the SNFFZ and Walker Lane Belt: (1) N- to NNW-striking normal and oblique faults, dominantly E-dipping, and associated W-tilted fault blocks; (2) NW-striking dextral faults; (3) ENE- to NE-striking left-lateral oblique faults that may accommodate overall dextral shear through clockwise vertical axis rotations of fault blocks; (4) E- to NE-trending folds, which may accommodate N-S shortening at large-scale left steps in the dextral transtensional fault system. Between Bridgeport and Mono Basins, a regional E- to NE-trending fold is present that affects both the Tertiary volcanic strata and a Quaternary glacial outwash surface. To the west, normal faulting rates on the SNFFZ are 1-2 mm/yr (Bursik and Sieh, 1989). This slip decreases to the north, into the folded region of the Bodie Hills. This kinematic relationship suggests that the region may be an accommodation zone between two linking faults, possibly an active fold that accommodates N-S shortening at a large-scale left step in the range front fault system. We collected ~200 paleomagnetic samples from the Late Miocene Eureka Valley Tuff of the Stanislaus Group at 21 sites over a 125-km-long, E-W transect (from the Sierra Nevada foothills to east of Mono Basin). Stepwise AF demagnetization reveals a stable characteristic remnant magnetization. Our preliminary data suggest 20-40 degrees of clockwise rotation adjacent to faults of the SNFFZ. An expanded dataset aims to identify specific structural domains, quantify differential vertical axis block rotations, and test geometric models of transrotation (i.e. block-specific versus gradational) during transtensional lithospheric deformation.

a Research on Monitoring Surface Deformation and Relationships with Surface Parameters in Qinghai Tibetan Plateau Permafrost

NASA Astrophysics Data System (ADS)

Mi, S. J.; Li, Y. T.; Wang, F.; Li, L.; Ge, Y.; Luo, L.; Zhang, C. L.; Chen, J. B.

2017-09-01

The Qinghai Tibetan Plateau permafrost has been the largest permafrost region in middle-low latitude in the world for its high altitude. For the large area permafrost, especially surface deformation brought by it, have serious influence on the road engineering, road maintaining and regional economic development. Consequently, it is essential to monitor the surface deformation and study factors that influent it. We monitored an area named Wudaoliang from July 25, 2015 to June 1, 2016 and 15 Sentinel images were obtained during this time. The area we chose is about 35 kilometers long and 2 kilometers wide, and the national road 109 of China passes through the area. The traditional PS-INSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) method is not suitable because less historical images in the research area and leading to the number of PS (Persistent Scatterer) points is not enough to obtain accurate deformation results. Therefore, in this paper, we used another method which named QUASI-PSInSAR (QUASI Persistent Scatterer Interferometric Synthetic Aperture Radar) to acquire deformation for it has the advantage to weaken or eliminate the effects of spatial and temporal correlation, which has proved by other scholar. After processing 15 images in the SARproz software, we got the conclusions that, 1) the biggest deformation velocity in the whole area was about 127.9mm/year and about 109.3 mm/year in the road; 2) apparent deformation which have surface deformation more than 30mm/year was about 1.7Km in the road. Meanwhile, soil moisture(SM), Land surface temperature (LST) and surface water(SW), which are primary parameters of the land surface over the same time were reversed by using Sentinel data, Landsat data and ZY-3 data, respectively. After analyzing SM, LST , SW and deformation, we obtained that wet areas which had bigger SM, lower LST and more SW, had greater percentage of severe deformation than arid areas; besides, deformation pattern were different in arid areas and wet areas. During the research time, frost heaving firstly accounted for a large proportion both in the arid and wet areas with the decrease of downward radiation from July to December; after December, thaw settlement came into prominence with the increase downward radiation in the arid areas, while in the wet areas, surface put into diverse situations because of water transformation leading to severe deformation. In summary, soil moisture is an important factor that influences the surface deformation. This relationship between deformation process and soil moisture will be researched more in our further work.

The interpretation of crustal dynamics data in terms of plate motions and regional deformation near plate boundaries

NASA Technical Reports Server (NTRS)

Solomon, Sean C.

1989-01-01

A particularly detailed set of observations in the vicinity of an intraplate, thrust earthquake (M 7.4) in Argentina, indicate a cyclic pattern of deformation very similar to that reported previously for interplate earthquakes. This deformation cycle, which may be characteristic of many seismically active areas, consists of: (1) steady strain accumulation, possibly punctuated by strain reversals; (2) coseismic strain release; (3) a period of continued strain release due to afterslip (persisting for perhaps a year or so); and (4) rapid postseismic strain accumulation which decreases exponentially and grades into steady strain accumulation. Deformation associated with three earthquakes in the U.S. (1940, M7.1 Imperial Valley California; 1964, M8.4 Alaska; 1959, M7.5 Hebgen Lake, Montana) are interpreted in light of this general earthquake cycle and are used to investigate the mechanics of strain release for these events. These examples indicate that large postseismic movements can occur for strike-slip, thrust, and normal fault events, and both viscoelastic relaxation and postseismic after-slip must be incorporated in models of earthquake related deformation. The mechanics of the strain release process revealed by these examples has implications for estimating earthquake repeat times from geodetic observations near active faults.

High Resolution Deformation Time Series Estimation for Distributed Scatterers Using Terrasar-X Data

NASA Astrophysics Data System (ADS)

Goel, K.; Adam, N.

2012-07-01

In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs) is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural) areas include the Small Baseline Subset Algorithm (SBAS). However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

Interplate locking derived from seafloor geodetic measurement at the shallow subduction zone of the northernmost Suruga Trough, Japan

NASA Astrophysics Data System (ADS)

Yasuda, K.; Tadokoro, K.; Ikuta, R.; Watanabe, T.; Nagai, S.; Sayanagi, K.

2013-12-01

Observation of seafloor crustal deformation is crucial for megathrust earthquake because most of the focal areas are located below seafloor. Seafloor crustal deformation can be observed GPS/Acoustic technique, and this technique has been carried out at subduction margins in Japan, e.g., Japan Trench, Suruga Trough, and Nankai Trough. At the present, the accuracy of seafloor positioning is one to several centimeters for each epoch. Velocity vectors at seafloor site are estimated through repeated observations. Co- and post- seismic slip distribution and interseismic deformation are estimated from results of seafloor geodetic measurement (e.g., Iinuma et al., 2012; Tadokoro et al., 2012). We repeatedly observed seafloor crustal deformations at two sites across the Suruga Trough from 2005 to investigate interplate locking condition at the focal area of the anticipated megathrust, Tokai, earthquake. We observed 12 and 16 times at an east site of the Suruga Trough (SNE) and at an west site of the Suruga Trough (SNW), respectively. We reinstalled seafloor benchmarks at both sites because of run out of batteries in 2012. We calculated and removed the bias between the old and new seafloor benchmarks. Furthermore, we evaluated two type of analysis. One is Fixed triangular configuration Analysis (FTA). When we determine the seafloor benchmark position, we fix the triangular configuration of seafloor units averaging all the measurements to improve trade-off relation between seafloor benchmark position and sound speed structure. Sound speed structure is assumed to be horizontal layered structure. The other one is Fixed Triangle and Gradient structure of sound speed structure (FTGA). We fixed triangular configuration same as FTA. Sound speed structure is assumed to have gradient structure. Comparing FTA with FTGA, the RMS of horizontal position analyzed through FTA is smaller than that through FTGA at SNE site. On the other hand, the RMS of horizontal position analyzed through FTA is larger than that through FTGA at SNW site. We estimated the displacement velocities with relative to the Amurian plate from the result of repeated observation. The estimated displacement velocity vectors at SNE and SNW are 42×8 mm/y to N94W direction and 46×13 mm/y to N77W direction, respectively. The directions are the same as those measured at the on-land GPS stations. The magnitudes of velocity vector indicate significant shortening by approximately 11 mm/y between SNW and on-land GPS stations at the western part of the Suruga Trough. We also calculated the theoretical surface deformation pattern to depict the interplate locking condition. These results show that the plate interface at the shallow zone of the northernmost Suruga trough is strongly locked.

Paleomagnetism of ~635 Ma "Elatina Rhythmites," Reconsidered

NASA Astrophysics Data System (ADS)

Raub, T. D.; Raub, T. M.

2007-12-01

Extraordinary laminated sand-siltstone of South Australia's synglacial/deglacial Elatina Formation-equivalent at Pichi Richi Pass is an iconic outcrop for paleomagnetists, paleoclimatologists, and astrophysicists. Cyclic- bedded stacks of coarse/fine-grained doublets have been interpreted as rhythmites of semi-diurnal tidal origin in a deep-water delta front environment. Cycle analysis has yielded estimates of Earth's paleorotation and revolution periods and lunar distance. The reported 10 m (interpreted 60 year) record disagrees somewhat with coeval and younger biological "sediment-clocks," and Williams (2000) argues that the sedimentological context and extraordinary preservation of Elatina rhythmites makes that record preferable. A paleomagnetic "synsedimentary fold" test on <8 cm amplitude antiforms from the Pichi Richi Pass rhythmites confirmed low-latitude Neoproterozoic glaciation (Sumner et al., 1987) and inspired the formal "Snowball Earth" hypothesis (Kirschvink, 1989). Repeated study of the Elatina rhythmites (Schmidt and Williams, 1995 and citations therein) has documented NRM essentially equal to ChRM carried by detrital hematite, "locked-in" synchronously with "deformation" of "antiforms" (i.e., within hours to days of deposition). "Synfolding" remanence has been ascribed to superposition of slump-shear and DRM. Anomalously shallow inclination of rhythmites (Sohl et al., 1999) could represent inadequate averaging of ca. 635 Ma geomagnetic secular variation. New measurement of ten stratigraphic sections through rhythmite-bearing facies outside of Pichi Richi Pass supports a distributary environment since rhythmites are expressed in multiple lithologies closely beneath ultimate deglacial, Nuccaleena cap dolostone. At Pichi Richi Pass, a full section of rhythmites approx. 18 meters thick is now documented, supporting a novel magnetostratigraphic collection of 130 samples. It is necessary to re-examine the DRM interpretation of Elatina rhythmite magnetization, however, in light of new observations: The structures previously considered "slump folds" are in fact sedimentary ripple crests. At Pichi Richi Pass, rhythmite facies grade upward from undisturbed, planar lamination into disorganized dunes, then low- wavelength, low-amplitude, linear-crested ripples, increasing steadily in wavelength and amplitude and climbing upward in >50 cm packages to culminate in unambiguous ladderback ripples. This shallowing-upward sequence reflects high sediment supply over 60 years and/or else significant sea level regression during (possibly longer) rhythmite deposition. The exceptional character of climbing-ripple rhythmites can be explained by pervasive microbial binding of sediment, in the anomalous mode characterizing many Ediacaran siliciclastic environments. Detrital magnetization seemingly should not around ripple crests. Either the interval of Snowball Earth deglaciation was characterized by unusually low geomagnetic field strength, biasing magnetization fidelity, or else Elatina rhythmites do not record DRM over a continuous 60-year timescale. This latter alternative may find support in the original studies, which document considerable dispersion, unexpected for a VGP. Kirschvink, 1992. in Schopf, J.W. and Klein, C., eds. The Proterozoic Biosphere, Cambridge University Press, Cambridge, pp. 51-52. Schmidt and Williams, 1995. Earth and Planetary Science Letters, v. 134, pp. 107-124. Sohl, Christie-Blick, and Kent, 1999. Geological Society of America Bulletin, v. 111, pp. 1120-1139. Sumner, Kirschvink, and Runnegar, 1987. EOS, v. 68, pg. 1251. Williams, 2000. Reviews of Geophysics, v. 38, pp. 37-59.

Sediment budget on African passive margins: a record of margin bulges and far field very long wavelength deformations

NASA Astrophysics Data System (ADS)

Guillocheau, Francois; Robin, Cécile; Baby, Guillaume; Simon, Brendan; Rouby, Delphine; Loparev, Artiom

2017-04-01

The post-rift siliciclastic sediment budget of passive margins is a function of (1) the deformation (uplift) of the upstream catchment, of (2) the climate (precipitation) regime and of (3) the oceanic circulation (mainly since Miocene times). The main questions in source to sink studies are (1) to quantify the relative importance of the erosion due to uplifts or to precipitation changes and (2) to characterize the source of the sediments. A source to sink study was carried out in Western, Central and Austral Africa, characterized by anorogenic relief (plains and plateaus) that record long (several 100 km) to very long (several 1000 km) wavelength deformations respectively of lithospheric and mantle origin. The sink measurement was based on seismic lines and wells (industrial - IODP) using the VolumeEstimator software including the calculation of the uncertainties (Guillocheau et al., 2013, Basin Research). The source study was performed using dated stepped planation surfaces (etchplains and pediplains), mappable at catchments-scale (Guillocheau et al., in press, Gondwana Research). Results: (1) Deformation (uplift) is the dominant control of the sediment budget. Climate (precipitation) changes only enhance or inhibit a deformation-controlled flux. (2) The sources of siliciclastic sediments are either closed marginal bulges or far field domes due to mantle dynamics with river by-passing over long-lasting polygenic surfaces located between the bulges and domes. Two main periods of African-scale deformations (contemporaneous with an increase of the sedimentary flux) are confirmed, one during Late Cretaceous (Turonian-Coniacian) and the second around the Eocene-Oligocene boundary with a gap and intense chemical erosion from 75 Ma and mainly from 65 to 40 Ma.

Effect of friction stir processing on tribological properties of Al-Si alloys

NASA Astrophysics Data System (ADS)

Aktarer, S. M.; Sekban, D. M.; Yanar, H.; Purçek, G.

2017-02-01

As-cast Al-12Si alloy was processed by single-pass friction stir processing (FSP), and its effect on mainly friction and wear properties of processed alloy was studied in detail. The needle-shaped eutectic silicon particles were fragmented by intense plastic deformation and dynamic recrystallization during FSP. The fragmented and homogenously distributed Si particles throughout the improve the mechanical properties and wear behavior of Al-12Si alloy. The wear mechanisms for this improvement were examined and the possible reasons were discussed.

Electrowetting-based optics

NASA Astrophysics Data System (ADS)

Kuiper, S.; Hendriks, B. H. W.; Hayes, R. A.; Feenstra, B. J.; Baken, J. M. E.

2005-09-01

Electrowetting is electrostatic manipulation of liquids. It can be used to displace and deform volumes of polar liquids. A very promising application area is optics. The surface of a volume of liquid can be used as a tunable lens and displacement of the liquid can change the refraction, diffraction or transmission of light when passing through the liquid. In this paper we describe a selection of various tunable optical components that make use of electrowetting, ranging from refractive and diffractive lenses to diaphragms and displays.

VACUUM TRAP

DOEpatents

Gordon, H.S.

1959-09-15

An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

Mathematical expressions using fringe projections for transparent objects

NASA Astrophysics Data System (ADS)

Su, Wei-Hung; Cheng, Chau-Jern

2017-08-01

A setup using fringe projection techniques to perform 3D profile measurements for transparent objects is presented. The related mathematical equations are derived as well. A fringe pattern is illuminated onto the transparent object. Fringes passing through the inspected object are then projected onto a screen. A CCD camera is employed to record the transmitted fringes on the screen. Fringe on the screen are deformed by the refractive index and the surface structure, and therefore are desirable to describe the shape of the inspected sample.

Development of the Perception of Object Containment in 9- to 16-Month-Olds

ERIC Educational Resources Information Center

Dejonckheere, Peter J. N.; Smitsman, Ad W.; Deneve, Leni Verhofstadt

2006-01-01

In the present study, 9-, 12- and 16-month-old infants were familiarized to a block that was repeatedly lowered into a container and lifted from that container again. In the subsequent test phase, the block passed through the container opening either without making contact with the container rim or colliding with the rim in three places but…

An Investigation of the effectiveness of the Virginia Habitual Offender Act : a study conducted by the Virginia Transportation Research Council for the Advisory Committee to the Commission on VASAP : final report.

DOT National Transportation Integrated Search

1993-01-01

In 1968, Virginia passed the Habitual Offender Act (the Act), one of the first laws in the United States directed at motorists who repeatedly violate traffic laws. Persons adjudicated as habitual offenders are subject to long-term license revocation,...

Spaced Learning: The Design, Feasibility and Optimisation of SMART Spaces. Evaluation Report and Executive Summary

ERIC Educational Resources Information Center

O'Hare, Liam; Stark, Patrick; McGuinness, Carol; Biggart, Andy; Thurston, Allen

2017-01-01

This report describes the development and pilot evaluation of SMART Spaces. This programme aims to boost GCSE science outcomes by applying the principle that information is more easily learnt when it is repeated multiple times, with time passing between the repetitions. This approach is known as "spaced learning" and is contrasted with a…

Study on the deformations of the lamina cribrosa during glaucoma.

PubMed

Tian, Hanjing; Li, Long; Song, Fan

2017-06-01

The lamina cribrosa is the primary site of optic nerve injury during glaucoma, and its deformations induced by elevated intraocular pressure are associated directly with the optic nerve injury and visual field defect. However, the deformations in a living body have been poorly understood yet so far. It is because that integral observation and precise measurement of the deformations in vivo are now almost impossible in the clinical diagnosis and treatment of glaucoma. In the present study, a new mechanical model of the lamina cribrosa is presented by using Reissner's thin plate theory. This model accurately displays the stress and deformation states in the lamina cribrosa under elevated intraocular pressure, in which the shear deformation is not presented by the previous models, however, is demonstrated to play a key role in the optic nerve injury. Further, the deformations of the structures, involving the optic nerve channels and the laminar sheets in the lamina cribrosa, are first investigated in detail. For example, the dislocation of the laminar sheets reaches 18.6μm under the intraocular pressure of 40mmHg, which is large enough to damage the optic nerve axons. The results here confirm some previously proposed clinical speculations on the deformations of the pore shape in the lamina cribrosa under elevated intraocular pressure during glaucoma. Finally, some essentially clinical questions existed during glaucoma, such as the pathological mechanism of the open-angle glaucoma with normal intraocular pressure, are discussed. The present study is beneficial to deeply understanding the optic nerve injury during glaucoma. The lamina cribrosa is the primary site of the optic nerve injury induced by elevated intraocular pressure during glaucoma. Under high intraocular pressure, the optic nerve channel near to the periphery of the lamina cribrosa (Channel A) is deformed to become into a tortuous elliptical horn from a straight cylinder, while the optic nerve channel near to the center of the lamina cribrosa (Channel B) is deformed to become into a straight horn from a straight cylinder. These deformations cause both the axoplasm flow obstacle in the axon fibers and the blocked blood flow in the capillaries which pass through the channels, and trigger the visual field defect during glaucoma. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Long-term Postseismic Deformation Following the 1964 Alaska Earthquake

NASA Astrophysics Data System (ADS)

Freymueller, J. T.; Cohen, S. C.; Hreinsdöttir, S.; Suito, H.

2003-12-01

Geodetic data provide a rich data set describing the postseismic deformation that followed the 1964 Alaska earthquake (Mw 9.2). This is particularly true for vertical deformation, since tide gauges and leveling surveys provide extensive spatial coverage. Leveling was carried out over all of the major roads of Alaska in 1964-65, and over the last several years we have resurveyed an extensive data set using GPS. Along Turnagain Arm of Cook Inlet, south of Anchorage, a trench-normal profile was surveyed repeatedly over the first decade after the earthquake, and many of these sites have been surveyed with GPS. After using a geoid model to correct for the difference between geometric and orthometric heights, the leveling+GPS surveys reveal up to 1.25 meters of uplift since 1964. The largest uplifts are concentrated in the northern part of the Kenai Peninsula, SW of Turnagain Arm. In some places, steep gradients in the cumulative uplift measurements point to a very shallow source for the deformation. The average 1964-late 1990s uplift rates were substantially higher than the present-day uplift rates, which rarely exceed 10 mm/yr. Both leveling and tide gauge data document a decay in uplift rate over time as the postseismic signal decreases. However, even today the postseismic deformation represents a substantial portion of the total observe deformation signal, illustrating that very long-lived postseismic deformation is an important element of the subduction zone earthquake cycle for the very largest earthquakes. This is in contrast to much smaller events, such as M~8 earthquakes, for which postseismic deformation in many cases decays within a few years. This suggests that the very largest earthquakes may excite different processes than smaller events.

Reconstruction of early phase deformations by integrated magnetic and mesotectonic data evaluation

NASA Astrophysics Data System (ADS)

Sipos, András A.; Márton, Emő; Fodor, László

2018-02-01

Markers of brittle faulting are widely used for recovering past deformation phases. Rocks often have oriented magnetic fabrics, which can be interpreted as connected to ductile deformation before cementation of the sediment. This paper reports a novel statistical procedure for simultaneous evaluation of AMS (Anisotropy of Magnetic Susceptibility) and fault-slip data. The new method analyzes the AMS data, without linearization techniques, so that weak AMS lineation and rotational AMS can be assessed that are beyond the scope of classical methods. This idea is extended to the evaluation of fault-slip data. While the traditional assumptions of stress inversion are not rejected, the method recovers the stress field via statistical hypothesis testing. In addition it provides statistical information needed for the combined evaluation of the AMS and the mesotectonic (0.1 to 10 m) data. In the combined evaluation a statistical test is carried out that helps to decide if the AMS lineation and the mesotectonic markers (in case of repeated deformation of the oldest set of markers) were formed in the same or different deformation phases. If this condition is met, the combined evaluation can improve the precision of the reconstruction. When the two data sets do not have a common solution for the direction of the extension, the deformational origin of the AMS is questionable. In this case the orientation of the stress field responsible for the AMS lineation might be different from that which caused the brittle deformation. Although most of the examples demonstrate the reconstruction of weak deformations in sediments, the new method is readily applicable to investigate the ductile-brittle transition of any rock formation as long as AMS and fault-slip data are available.

Local Deformation Precursors of Large Earthquakes Derived from GNSS Observation Data

NASA Astrophysics Data System (ADS)

Kaftan, Vladimir; Melnikov, Andrey

2017-12-01

Research on deformation precursors of earthquakes was of immediate interest from the middle to the end of the previous century. The repeated conventional geodetic measurements, such as precise levelling and linear-angular networks, were used for the study. Many examples of studies referenced to strong seismic events using conventional geodetic techniques are presented in [T. Rikitake, 1976]. One of the first case studies of geodetic earthquake precursors was done by Yu.A. Meshcheryakov [1968]. Rare repetitions, insufficient densities and locations of control geodetic networks made difficult predicting future places and times of earthquakes occurrences. Intensive development of Global Navigation Satellite Systems (GNSS) during the recent decades makes research more effective. The results of GNSS observations in areas of three large earthquakes (Napa M6.1, USA, 2014; El Mayor Cucapah M7.2, USA, 2010; and Parkfield M6.0, USA, 2004) are treated and presented in the paper. The characteristics of land surface deformation before, during, and after earthquakes have been obtained. The results prove the presence of anomalous deformations near their epicentres. The temporal character of dilatation and shear strain changes show existence of spatial heterogeneity of deformation of the Earth’s surface from months to years before the main shock close to it and at some distance from it. The revealed heterogeneities can be considered as deformation precursors of strong earthquakes. According to historical data and proper research values of critical deformations which are offered to be used for seismic danger scale creation based on continuous GNSS observations are received in a reference to the mentioned large earthquakes. It is shown that the approach has restrictions owing to uncertainty of the moment in the beginning of deformation accumulation and the place of expectation of another seismic event. Verification and clarification of the derived conclusions are proposed.

[Results from ten years newborn hearing screening in a secondary hospital].

PubMed

Sequi Canet, José Miguel; Sala Langa, Maria José; Collar Del Castillo, José Ignacio

2016-10-01

A critical analysis is performed on the results of a newborn hearing screening program in a regional hospital. Screening results from 14,247 newborns in our maternity ward from 2002 to 2013. Two step recordings of bilateral otoacoustic emissions (initial and repeat, if failed, at about one month of life). Assessment by clinical brainstem responses. The first step was performed on 14,015 newborns (98.3% of the total) reaching the screening objective. The first step pass figures were 93.7%, which implies a good pass rate with a few patients to repeat. The second step is also good because it has a pass rate of 88.9% of newborns examined (only 0.63% of initial group needed brainstem responses assessment), but 10.6% were lost to follow up, and that is a major problem. In newborns, scheduled for brainstem responses, the loss to follow-up is worse, with a figure of 29.5%, despite the high accuracy of this test given that 69.4% of those assessed showed hearing loss. This figure represents a 0.31% of the initial group, and is a similar to that published for congenital hearing loss. Including patients that were lost to follow up this figure could be greater. Newborn hearing screening is useful but needs stronger control to avoid the follow up loss. In order to achieve this, it is crucial to have a good database and a screening coordinator. Copyright © 2015 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

Sedimentary environment and tectonic deformations of the Neoproterozoic Iron formation at the Wadi El-Dabbah greenstone sequence, Central Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

Kiyokawa, S.; Suzuki, T.; Ikehara, M.; Horie, K.; Takehara, M.; Abd-Elmonem, H.; Dawoud, A. D. M.; El-Hasan, M. M.

2017-12-01

El-Dabbah area Central Eastern Desert of the Nubia Shield preserved Neoproterozoic lower green schist faces volcaniclastics greenstone sequence and covered strike-slip deformation related subaerial sedimentary sequence (Hammamat Group). The volcaniclastics greenstone sequence (El-Dabbah Formation) preserved several iron beds bearing well stratified sequence. Four tectonic deformation identified as this area; thrust deformation (D1), strike-slip deformation with transtension normal fault and strong left-lateral shear (D2), subaerial pull apart sediments basin formed strike-slip deformations (D3), and extensional deformation after the Hammamat Group sedimentation (D4). New age data from intrusions identified about 638 Ma white granite and about 660 Ma quartz porphyry. Based on the detail mapping, we reconstruct more than 5000m thick volcano sedimentary succession. At least, 10 iron rich sections were identified within 3500m thick volcano-sedimentary sequence. There are 14 iron formation sequence identified in this greenstone sequence. Each Iron sequences are bedded with greenish-black shales within massive volcaniclastics and lava flow. Iron formation is formed mostly fine grain magnetite deposited within volcanic mudstone and siltstone with gradual distribution. Timing of this iron sediment is identified within Sturtian glaciation (730-700Ma). However, there is no geological direct support evidence in the Snowball earth event at this greenstone sequence. The volcanic activities at this ocean already produced many Fe2+ to ocean water. Repeated iron precipitation occur during volcanic activity interphase period which produced oxidation of iron and produce oxyhydroxide with mud-silt sediment at bottom of ocean.

Localization in Naturally Deformed Systems - the Default State?

NASA Astrophysics Data System (ADS)

Clancy White, Joseph

2017-04-01

Based on the extensive literature on localized rock deformation, conventional wisdom would interpret it to be a special behaviour within an anticipated background of otherwise uniform deformation. The latter notwithstanding, the rock record is so rife with transient (cyclic), heterogeneous deformation, notably shear localization, as to characterize localization as the anticipated 'normal' behaviour. The corollary is that steady, homogeneous deformation is significantly less common, and if achieved must reflect some special set of conditions that are not representative of the general case. An issue central to natural deformation is then not the existance of localized strain, but rather how the extant deformation processes scale across tectonic phenomena and in turn organize to enable a coherent(?) descripion of Earth deformation. Deformation is fundamentally quantized, discrete (diffusion, glide, crack propagation) and reliant on the defect state of rock-forming minerals. The strain energy distribution that drives thermo-mechanical responses is in the first instance established at the grain-scale where the non-linear interaction of defect-mediated micromechanical processes introduces heterogeneous behaviour described by various gradient theories, and evidenced by the defect microstructures of deformed rocks. Hence, the potential for non-uniform response is embedded within even quasi-uniform, monomineralic materials, seen, for example, in the spatially discrete evolution of dynamic recrystallization. What passes as homogeneous or uniform deformation at various scales is the aggregation of responses at some characteristic dimension at which heterogeneity is not registered or measured. Nevertheless, the aggregate response and associated normalized parameters (strain, strain rate) do not correspond to any condition actually experienced by the deforming material. The more common types of macroscopic heterogeneity promoting localization comprise mechanically contrasting materials typical of most rocks. Such perturbations are of themselves only larger examples of variation in the fundamental defect distribution and response; that is the boundary conditions that induce heterogeneous response are reflections of the microphysical behaviour seen in aggregate as strain accommodating softening or stabilization processes such as grain size reduction and independent grain displacements. Additionally, cyclic interplay between inelastic rupture and subsequent plastic material softening resulting from the concomitant introduction of exogenous material in the form of igneous melts, deformation-induced melts and fluid precipitates (veins). This two-stage process determines the siting and temporary stabilization of the shear phenomena, and indicates that material hardening and non-associated flow over some characteristic time are precursors to any particular instability, with stabilization of localized shear correlated with system softening tied to redistribution of strain energy dissipation within what is effectively a reconstituted material.

Studies on Creep Deformation and Rupture Behavior of 316LN SS Multi-Pass Weld Joints Fabricated with Two Different Electrode Sizes

NASA Astrophysics Data System (ADS)

Vijayanand, V. D.; Kumar, J. Ganesh; Parida, P. K.; Ganesan, V.; Laha, K.

2017-02-01

Effect of electrode size on creep deformation and rupture behavior has been assessed by carrying out creep tests at 923 K (650 °C) over the stress range 140 to 225 MPa on 316LN stainless steel weld joints fabricated employing 2.5 and 4 mm diameter electrodes. The multi-pass welding technique not only changes the morphology of delta ferrite from vermicular to globular in the previous weld bead region near to the weld bead interface, but also subjects the region to thermo-mechanical heat treatment to generate appreciable strength gradient. Electron backscatter diffraction analysis revealed significant localized strain gradients in regions adjoining the weld pass interface for the joint fabricated with large electrode size. Larger electrode diameter joint exhibited higher creep rupture strength than the smaller diameter electrode joint. However, both the joints had lower creep rupture strength than the base metal. Failure in the joints was associated with microstructural instability in the fusion zone, and the vermicular delta ferrite zone was more prone to creep cavitation. Larger electrode diameter joint was found to be more resistant to failure caused by creep cavitation than the smaller diameter electrode joint. This has been attributed to the larger strength gradient between the beads and significant separation between the cavity prone vermicular delta ferrite zones which hindered the cavity growth. Close proximity of cavitated zones in smaller electrode joint facilitated their faster coalescence leading to more reduction in creep rupture strength. Failure location in the joints was found to depend on the electrode size and applied stress. The change in failure location has been assessed on performing finite element analysis of stress distribution across the joint on incorporating tensile and creep strengths of different constituents of joints, estimated by ball indentation and impression creep testing techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wulff, J; Huggins, A

Purpose: The shape of a single beam in proton PBS influences the resulting dose distribution. Spot profiles are modelled as two-dimensional Gaussian (single/ double) distributions in treatment planning systems (TPS). Impact of slight deviations from an ideal Gaussian on resulting dose distributions is typically assumed to be small due to alleviation by multiple Coulomb scattering (MCS) in tissue and superposition of many spots. Quantitative limits are however not clear per se. Methods: A set of 1250 deliberately deformed profiles with sigma=4 mm for a Gaussian fit were constructed. Profiles and fit were normalized to the same area, resembling output calibrationmore » in the TPS. Depth-dependent MCS was considered. The deviation between deformed and ideal profiles was characterized by root-mean-squared deviation (RMSD), skewness/ kurtosis (SK) and full-width at different percentage of maximum (FWxM). The profiles were convolved with different fluence patterns (regular/ random) resulting in hypothetical dose distributions. The resulting deviations were analyzed by applying a gamma-test. Results were compared to measured spot profiles. Results: A clear correlation between pass-rate and profile metrics could be determined. The largest impact occurred for a regular fluence-pattern with increasing distance between single spots, followed by a random distribution of spot weights. The results are strongly dependent on gamma-analysis dose and distance levels. Pass-rates of >95% at 2%/2 mm and 40 mm depth (=70 MeV) could only be achieved for RMSD<10%, deviation in FWxM at 20% and root of quadratic sum of SK <0.8. As expected the results improve for larger depths. The trends were well resembled for measured spot profiles. Conclusion: All measured profiles from ProBeam sites passed the criteria. Given the fact, that beam-line tuning can result shape distortions, the derived criteria represent a useful QA tool for commissioning and design of future beam-line optics.« less

PIV-DCNN: cascaded deep convolutional neural networks for particle image velocimetry

NASA Astrophysics Data System (ADS)

Lee, Yong; Yang, Hua; Yin, Zhouping

2017-12-01

Velocity estimation (extracting the displacement vector information) from the particle image pairs is of critical importance for particle image velocimetry. This problem is mostly transformed into finding the sub-pixel peak in a correlation map. To address the original displacement extraction problem, we propose a different evaluation scheme (PIV-DCNN) with four-level regression deep convolutional neural networks. At each level, the networks are trained to predict a vector from two input image patches. The low-level network is skilled at large displacement estimation and the high- level networks are devoted to improving the accuracy. Outlier replacement and symmetric window offset operation glue the well- functioning networks in a cascaded manner. Through comparison with the standard PIV methods (one-pass cross-correlation method, three-pass window deformation), the practicability of the proposed PIV-DCNN is verified by the application to a diversity of synthetic and experimental PIV images.

Method of texturing a superconductive oxide precursor

DOEpatents

DeMoranville, Kenneth L.; Li, Qi; Antaya, Peter D.; Christopherson, Craig J.; Riley, Jr., Gilbert N.; Seuntjens, Jeffrey M.

1999-01-01

A method of forming a textured superconductor wire includes constraining an elongated superconductor precursor between two constraining elongated members placed in contact therewith on opposite sides of the superconductor precursor, and passing the superconductor precursor with the two constraining members through flat rolls to form the textured superconductor wire. The method includes selecting desired cross-sectional shape and size constraining members to control the width of the formed superconductor wire. A textured superconductor wire formed by the method of the invention has regular-shaped, curved sides and is free of flashing. A rolling assembly for single-pass rolling of the elongated precursor superconductor includes two rolls, two constraining members, and a fixture for feeding the precursor superconductor and the constraining members between the rolls. In alternate embodiments of the invention, the rolls can have machined regions which will contact only the elongated constraining members and affect the lateral deformation and movement of those members during the rolling process.

Method to improve optical parametric oscillator beam quality

DOEpatents

Smith, Arlee V.; Alford, William J.; Bowers, Mark S.

2003-11-11

A method to improving optical parametric oscillator (OPO) beam quality having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

Optical parametric osicllators with improved beam quality

DOEpatents

Smith, Arlee V.; Alford, William J.

2003-11-11

An optical parametric oscillator (OPO) having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

The Diagnostic Validity and Reliability of an Internet-Based Clinical Assessment Program for Mental Disorders

PubMed Central

Klein, Britt; Meyer, Denny; Austin, David William; Abbott, Jo-Anne M

2015-01-01

Background Internet-based assessment has the potential to assist with the diagnosis of mental health disorders and overcome the barriers associated with traditional services (eg, cost, stigma, distance). Further to existing online screening programs available, there is an opportunity to deliver more comprehensive and accurate diagnostic tools to supplement the assessment and treatment of mental health disorders. Objective The aim was to evaluate the diagnostic criterion validity and test-retest reliability of the electronic Psychological Assessment System (e-PASS), an online, self-report, multidisorder, clinical assessment and referral system. Methods Participants were 616 adults residing in Australia, recruited online, and representing prospective e-PASS users. Following e-PASS completion, 158 participants underwent a telephone-administered structured clinical interview and 39 participants repeated the e-PASS within 25 days of initial completion. Results With structured clinical interview results serving as the gold standard, diagnostic agreement with the e-PASS varied considerably from fair (eg, generalized anxiety disorder: κ=.37) to strong (eg, panic disorder: κ=.62). Although the e-PASS’ sensitivity also varied (0.43-0.86) the specificity was generally high (0.68-1.00). The e-PASS sensitivity generally improved when reducing the e-PASS threshold to a subclinical result. Test-retest reliability ranged from moderate (eg, specific phobia: κ=.54) to substantial (eg, bulimia nervosa: κ=.87). Conclusions The e-PASS produces reliable diagnostic results and performs generally well in excluding mental disorders, although at the expense of sensitivity. For screening purposes, the e-PASS subclinical result generally appears better than a clinical result as a diagnostic indicator. Further development and evaluation is needed to support the use of online diagnostic assessment programs for mental disorders. Trial Registration Australian and New Zealand Clinical Trials Registry ACTRN121611000704998; http://www.anzctr.org.au/trial_view.aspx?ID=336143 (Archived by WebCite at http://www.webcitation.org/618r3wvOG). PMID:26392066

Spondylocostal dysostosis associated with right-sided polythelia, right-sided rib deformity and meningocoele: Case report with review of literature.

PubMed

Rai, Narendra; Thakur, Neha; Khan, Naheed Zin; Dwivedi, Akhilesh Dutt

2015-01-01

Spondylocostal dysostosis (SCD) is a rare anomaly of axial skeleton due to flawed embryological development. A newborn baby boy with right-sided polythelia, meningocoele, fan-like configuration of third and fourth rib, fused fifth and sixth rib and third thoracic hemivertebra was delivered to a second gravid mother by elective caesarean section. Baby was active, cried immediately after birth, had normal muscle tone and reflexes. He passed urine and meconium within 24 h of birth. Based on clinical examination and radiological picture, a diagnosis of SCD with meningocele with right-sided polythelia was made. Our case is the first SCD with polythelia and meningocele in newborn. SCD with right-sided polythelia and rib deformity with neural tube defect (NTD) may be due to a genetic defect with the culprit genes missing. Further genetic and embryological studies might find a link between right-sided rib defects, polythelia and NTD.

Combined process "helical rolling-pressing" and its effect on the microstructure of ferrous and non-ferrous materials

NASA Astrophysics Data System (ADS)

Naizabekov, Abdrakhman; Lezhnev, Sergey; Arbuz, Alexandr; Panin, Evgeniy

2018-02-01

Ultrafine-grained materials are one of the most promising structural and functional materials. However, the known methods of obtaining them are not enough powerful and technologically advanced for profitable industrial applications. Development of the combined process "helical rolling-pressing" is an attempt to bring technology to produce ultrafine-grained materials to the industry. The combination of intense processing of the surface by helical rolling and the entire cross section of workpiece in equal channel angular matrix, with intense deformation by torsion between rolls and matrix will increase the degree of deformation per pass and allows to mutually compensate disadvantages of these methods in the case of their separate use. This paper describes the development of a laboratory stand and study of influence of combined process "helical rolling-pressing"on the microstructure of tool steel, technical copper and high alloy stainless high-temperature steel.

Direct Cytoskeleton Forces Cause Membrane Softening in Red Blood Cells

PubMed Central

Rodríguez-García, Ruddi; López-Montero, Iván; Mell, Michael; Egea, Gustavo; Gov, Nir S.; Monroy, Francisco

2015-01-01

Erythrocytes are flexible cells specialized in the systemic transport of oxygen in vertebrates. This physiological function is connected to their outstanding ability to deform in passing through narrow capillaries. In recent years, there has been an influx of experimental evidence of enhanced cell-shape fluctuations related to metabolically driven activity of the erythroid membrane skeleton. However, no direct observation of the active cytoskeleton forces has yet been reported to our knowledge. Here, we show experimental evidence of the presence of temporally correlated forces superposed over the thermal fluctuations of the erythrocyte membrane. These forces are ATP-dependent and drive enhanced flickering motions in human erythrocytes. Theoretical analyses provide support for a direct force exerted on the membrane by the cytoskeleton nodes as pulses of well-defined average duration. In addition, such metabolically regulated active forces cause global membrane softening, a mechanical attribute related to the functional erythroid deformability. PMID:26083919

Magmas near the critical degassing pressure drive volcanic unrest towards a critical state.

PubMed

Chiodini, Giovanni; Paonita, Antonio; Aiuppa, Alessandro; Costa, Antonio; Caliro, Stefano; De Martino, Prospero; Acocella, Valerio; Vandemeulebrouck, Jean

2016-12-20

During the reawaking of a volcano, magmas migrating through the shallow crust have to pass through hydrothermal fluids and rocks. The resulting magma-hydrothermal interactions are still poorly understood, which impairs the ability to interpret volcano monitoring signals and perform hazard assessments. Here we use the results of physical and volatile saturation models to demonstrate that magmatic volatiles released by decompressing magmas at a critical degassing pressure (CDP) can drive volcanic unrest towards a critical state. We show that, at the CDP, the abrupt and voluminous release of H 2 O-rich magmatic gases can heat hydrothermal fluids and rocks, triggering an accelerating deformation that can ultimately culminate in rock failure and eruption. We propose that magma could be approaching the CDP at Campi Flegrei, a volcano in the metropolitan area of Naples, one of the most densely inhabited areas in the world, and where accelerating deformation and heating are currently being observed.

Field guide to the Mesozoic arc and accretionary complex of South-Central Alaska, Indian to Hatcher Pass

USGS Publications Warehouse

Karl, Susan M.; Oswald, P.J.; Hults, Chad P.

2015-01-01

This field trip traverses exposures of a multi-generation Mesozoic magmatic arc and subduction-accretion complex that had a complicated history of magmatic activity and experienced variations in composition and deformational style in response to changes in the tectonic environment. This Mesozoic arc formed at an unknown latitude to the south, was accreted to North America, and was subsequently transported along faults to its present location (Plafker and others, 1989; Hillhouse and Coe, 1994). Some of these faults are still active. Similar tectonic, igneous, and sedimentary processes to those that formed the Mesozoic arc complex persist today in southern Alaska, building on, and deforming the Mesozoic arc. The rocks we will see on this field trip provide insights on the three-dimensional composition of the modern arc, and the processes involved in the evolution of an arc and its companion accretionary complex.

In vivo deformation of thin cartilage layers: Feasibility and applicability of T2* mapping.

PubMed

Van Ginckel, Ans; Witvrouw, Erik E

2016-05-01

The objectives of this study were as follows: (i) to assess segmentation consistency and scan precision of T2* mapping of human tibio-talar cartilage, and (ii) to monitor changes in T2* relaxation times of ankle cartilage immediately following a clinically relevant in vivo exercise and during recovery. Using multi-echo gradient recalled echo sequences, averaged T2* values were calculated for tibio-talar cartilage layers in 10 healthy volunteers. Segmentation consistency and scan precision were determined from two repeated segmentations and two repeated acquisitions with repositioning, respectively. Subsequently, acute in vivo cartilage loading responses were monitored by calculating averaged tibio-talar T2* values at rest, immediately after (i.e., deformation) and at 15 min (i.e., recovery) following a 30-repetition knee bending exercise. Precision errors attained 4-6% with excellent segmentation consistency point estimates (i.e., intra-rater ICC of 0.95) and acceptable limits of confidence. At deformation, T2* values were increased in both layers [+16.1 (10.7)%, p = 0.004 and +17.3 (15.3)%, p = 0.023, for the talus and tibia, respectively] whereas during recovery no significant changes could be established when comparing to baseline [talar cartilage: +5.2 (8.2)%, p = 0.26 and tibial cartilage: +6.6 (10.4)%, p = 0.23]. T2* mapping is a viable method to monitor deformational behavior in thin cartilage layers such as ankle cartilage. Longitudinal changes in T2* can be reliably appraised and require at least 4-6% differences to ascertain statistical significance. The ability to detect considerable change even after non-strenuous loading events, endorses T2* mapping as an innovative method to evaluate the effects of therapeutic exercise on thin cartilage layers. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:771-778, 2016. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Evaluation of the iPhone with an acrylic sleeve versus the Scoliometer for rib hump measurement in scoliosis.

PubMed

Izatt, Maree T; Bateman, Gary R; Adam, Clayton J

2012-07-30

Vertebral rotation found in structural scoliosis contributes to trunkal asymmetry which is commonly measured with a simple Scoliometer device on a patient's thorax in the forward flexed position. The new generation of mobile 'smartphones' have an integrated accelerometer, making accurate angle measurement possible, which provides a potentially useful clinical tool for assessing rib hump deformity. This study aimed to compare rib hump angle measurements performed using a Smartphone and traditional Scoliometer on a set of plaster torsos representing the range of torsional deformities seen in clinical practice. Nine observers measured the rib hump found on eight plaster torsos moulded from scoliosis patients with both a Scoliometer and an Apple iPhone on separate occasions. Each observer repeated the measurements at least a week after the original measurements, and were blinded to previous results. Intra-observer reliability and inter-observer reliability were analysed using the method of Bland and Altman and 95% confidence intervals were calculated. The Intra-Class Correlation Coefficients (ICC) were calculated for repeated measurements of each of the eight plaster torso moulds by the nine observers. Mean absolute difference between pairs of iPhone/Scoliometer measurements was 2.1 degrees, with a small (1 degrees) bias toward higher rib hump angles with the iPhone. 95% confidence intervals for intra-observer variability were +/- 1.8 degrees (Scoliometer) and +/- 3.2 degrees (iPhone). 95% confidence intervals for inter-observer variability were +/- 4.9 degrees (iPhone) and +/- 3.8 degrees (Scoliometer). The measurement errors and confidence intervals found were similar to or better than the range of previously published thoracic rib hump measurement studies. The iPhone is a clinically equivalent rib hump measurement tool to the Scoliometer in spinal deformity patients. The novel use of plaster torsos as rib hump models avoids the variables of patient fatigue and discomfort, inconsistent positioning and deformity progression using human subjects in a single or multiple measurement sessions.

Evaluation of the iPhone with an acrylic sleeve versus the Scoliometer for rib hump measurement in scoliosis

PubMed Central

2012-01-01

Background Vertebral rotation found in structural scoliosis contributes to trunkal asymmetry which is commonly measured with a simple Scoliometer device on a patient's thorax in the forward flexed position. The new generation of mobile 'smartphones' have an integrated accelerometer, making accurate angle measurement possible, which provides a potentially useful clinical tool for assessing rib hump deformity. This study aimed to compare rib hump angle measurements performed using a Smartphone and traditional Scoliometer on a set of plaster torsos representing the range of torsional deformities seen in clinical practice. Methods Nine observers measured the rib hump found on eight plaster torsos moulded from scoliosis patients with both a Scoliometer and an Apple iPhone on separate occasions. Each observer repeated the measurements at least a week after the original measurements, and were blinded to previous results. Intra-observer reliability and inter-observer reliability were analysed using the method of Bland and Altman and 95% confidence intervals were calculated. The Intra-Class Correlation Coefficients (ICC) were calculated for repeated measurements of each of the eight plaster torso moulds by the nine observers. Results Mean absolute difference between pairs of iPhone/Scoliometer measurements was 2.1 degrees, with a small (1 degrees) bias toward higher rib hump angles with the iPhone. 95% confidence intervals for intra-observer variability were +/- 1.8 degrees (Scoliometer) and +/- 3.2 degrees (iPhone). 95% confidence intervals for inter-observer variability were +/- 4.9 degrees (iPhone) and +/- 3.8 degrees (Scoliometer). The measurement errors and confidence intervals found were similar to or better than the range of previously published thoracic rib hump measurement studies. Conclusions The iPhone is a clinically equivalent rib hump measurement tool to the Scoliometer in spinal deformity patients. The novel use of plaster torsos as rib hump models avoids the variables of patient fatigue and discomfort, inconsistent positioning and deformity progression using human subjects in a single or multiple measurement sessions. PMID:22846346

Stretching of red blood cells by optical tweezers quantified by digital holographic microscopy

NASA Astrophysics Data System (ADS)

Cardenas, Nelson; Yu, Lingfeng; Mohanty, Samarendra K.

2011-03-01

Red blood cells (RBC) possess unique viscoelastic characteristics which allow them to pass through capillaries narrower than their size. Measurement of viscoelastic property of cells (e.g. RBC) in low-force regime is of high significance as it represents conditions of membrane fluctuation in response to physiological conditions. Estimation of visco-elastic properties of RBC requires measurement of extent of deformation in RBC subjected to known force. Optical tweezers, being gentle and absolutely sterile, are emerging as the tool of choice for application of localized force on cells. However, stretching of RBC in very low force regime has not been quantified. Further, though deformations in transverse directions have been measured, vertical deformations due to stretching of cells cannot be quantified by classical microscopic images. Here, we report realization of offaxis digital holographic microscopy (DHM) for highly sensitive axial changes in RBC shape due to stretching by optical tweezers without attaching microscopic beads. The RBC was stretched in axial direction with nanometer precision by change of divergence of the trapping beam. The obtained deformation patterns were compared with the axial position of the tweezers focus. Since the pathophysiology of progression of diseases like malaria and cancer is reflected in the biophysical (both mechanical and material) properties of the cells, it is possible to identify the changes by simultaneous measurement of refractive index and elasticity using this approach.

DMA engine for repeating communication patterns

DOEpatents

Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard; Vranas, Pavlos

2010-09-21

A parallel computer system is constructed as a network of interconnected compute nodes to operate a global message-passing application for performing communications across the network. Each of the compute nodes includes one or more individual processors with memories which run local instances of the global message-passing application operating at each compute node to carry out local processing operations independent of processing operations carried out at other compute nodes. Each compute node also includes a DMA engine constructed to interact with the application via Injection FIFO Metadata describing multiple Injection FIFOs where each Injection FIFO may containing an arbitrary number of message descriptors in order to process messages with a fixed processing overhead irrespective of the number of message descriptors included in the Injection FIFO.

Double-pass Mach-Zehnder fiber interferometer pH sensor.

PubMed

Tou, Zhi Qiang; Chan, Chi Chiu; Hong, Jesmond; Png, Shermaine; Eddie, Khay Ming Tan; Tan, Terence Aik Huang

2014-04-01

A biocompatible fiber-optic pH sensor based on a unique double-pass Mach-Zehnder interferometer is proposed. pH responsive poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) hydrogel coating on the fiber swells/deswells in response to local pH, leading to refractive index changes that manifest as shifting of interference dips in the optical spectrum. The pH sensor is tested in spiked phosphate buffer saline and demonstrates high sensitivity of 1.71  nm/pH, pH 0.004 limit of detection with good responsiveness, repeatability, and stability. The proposed sensor has been successfully applied in monitoring the media pH in cell culture experiments to investigate the relationship between pH and cancer cell growth.

Transfer of molybdenum disulfide to various metals

NASA Technical Reports Server (NTRS)

Barton, G. C.; Pepper, S. V.

1977-01-01

Sliding friction experiments were conducted with molybdenum disulfide single crystals in contact with sputter cleaned surfaces of copper, nickel, gold, and 304 stainless steel. Transfer of the molybdenum disulfide to the metals was monitored with Auger electron spectroscopy. Results of the investigation indicate molybdenum disulfide transfers to all clean metal surfaces after a single pass over the metal surface with film thickness observed to increase with repeated passes over the same surfaces. Large particle transfer occurs when the orientation of the crystallites is other than basal. This is frequently accompanied by abrasion of the metal. Adhesion of molybdenum disulfide films occurred readily to copper and nickel, less readily to 304 stainless steel, and even less effectively to the gold, which indicates a chemical effect.

Microscale evidence of liquefaction and its potential triggers during soft-bed deformation within subglacial traction tills

NASA Astrophysics Data System (ADS)

Phillips, Emrys R.; Evans, David J. A.; van der Meer, Jaap J. M.; Lee, Jonathan R.

2018-02-01

Published conceptual models argue that much of the forward motion of modern and ancient glaciers is accommodated by deformation of soft-sediments within the underlying bed. At a microscale this deformation results in the development of a range of ductile and brittle structures in water-saturated sediments as they accommodate the stresses being applied by the overriding glacier. Detailed micromorphological studies of subglacial traction tills reveal that these polydeformed sediments may also contain evidence of having undergone repeated phases of liquefaction followed by solid-state shear deformation. This spatially and temporally restricted liquefaction of subglacial traction tills lowers the shear strength of the sediment and promotes the formation of "transient mobile zones" within the bed, which accommodate the shear imposed by the overriding ice. This process of soft-bed sliding, alternating with bed deformation, facilitates glacier movement by way of 'stick-slip' events. The various controls on the slip events have previously been identified as: (i) the introduction of pressurised meltwater into the bed, a process limited by the porosity and permeability of the till; and (ii) pressurisation of porewater as a result of subglacial deformation; to which we include (iii) episodic liquefaction of water-saturated subglacial traction tills in response to glacier seismic activity (icequakes), which are increasingly being recognized as significant processes in modern glaciers and ice sheets. As liquefaction operates only in materials already at very low values of effective stress, its process-form signatures are likely indicative of glacier sub-marginal tills.

Deformation modeling and constitutive modeling for anisotropic superalloys

NASA Technical Reports Server (NTRS)

Milligan, Walter W.; Antolovich, Stephen D.

1989-01-01

A study of deformation mechanisms in the single crystal superalloy PWA 1480 was conducted. Monotonic and cyclic tests were conducted from 20 to 1093 C. Both (001) and near-(123) crystals were tested, at strain rates of 0.5 and 50 percent/minute. The deformation behavior could be grouped into two temperature regimes: low temperatures, below 760 C; and high temperatures, above 820 to 950 C depending on the strain rate. At low temperatures, the mechanical behavior was very anisotropic. An orientation dependent CRSS, a tension-compression asymmetry, and anisotropic strain hardening were all observed. The material was deformed by planar octahedral slip. The anisotropic properties were correlated with the ease of cube cross-slip, as well as the number of active slip systems. At high temperatures, the material was isotropic, and deformed by homogeneous gamma by-pass. It was found that the temperature dependence of the formation of superlattice-intrinsic stacking faults was responsible for the local minimum in the CRSS of this alloy at 400 C. It was proposed that the cube cross-slip process must be reversible. This was used to explain the reversible tension-compression asymmetry, and was used to study models of cross-slip. As a result, the cross-slip model proposed by Paidar, Pope and Vitek was found to be consistent with the proposed slip reversibility. The results were related to anisotropic viscoplastic constitutive models. The model proposed by Walter and Jordan was found to be capable of modeling all aspects of the material anisotropy. Temperature and strain rate boundaries for the model were proposed, and guidelines for numerical experiments were proposed.

Deformation of phase D and Earth's deep water cycle

NASA Astrophysics Data System (ADS)

Walker, A.; Skelton, R.; Nowacki, A.

2016-12-01

The stability of dense hydrous magnesium silicates such as phase D in subducting slabs provide a potential path for hydrogen transport from the Earth's surface environment into the lower mantle. Recent analysis of source-side shear wave splitting for rays from deep earthquakes around slabs detected a signal of anisotropy that could be attributed to the deformation of phase D [Nowacki et al. 2015; Geochem. Geophys. Geosyst., 16, 764-784]. If this is the case these observations could provide an estimate of the hydrogen flux into the lower mantle at depths beyond shallow recycling through the volcanic arc. However, the processes leading to the deformation of phase D and the generation of seismic anisotropy are not well known and this is a barrier to progress. Here we present initial results of simulations designed to reveal how easily different dislocations move in phase D during deformation and lead to the generation of seismic anisotropy measured by shear wave splitting. In particular, we use atomic scale simulations to calculate the energies of generalised stacking faults in phase D, which are used to parameterise Peierls-Nabarro models of dislocation structures and Peierls stresses at pressures up to 60 GPa. We then use results from these calculations as parameters for models of texture development in polycrystalline aggregates during deformation using the visco-plastic self-consistent approach. In combination with measurement of the distribution of seismic anisotropy around subducting slabs, and an analysis of the strain pattern expected as slabs pass through the transition zone, these results could constrain an important part of Earth's deep water cycle.

Effect of the tiger stripes on the tidal deformation of Enceladus

NASA Astrophysics Data System (ADS)

Soucek, Ondrej; Hron, Jaroslav; Behounkova, Marie; Cadek, Ondrej

2016-10-01

The south polar region of Saturn's moon Enceladus has been subjected to a thorough scientific scrutiny since the Cassini mission discovery of an enigmatic system of fractures informally known as "tiger stripes". This fault system is possibly connected to the internal water ocean and exhibits a striking geological activity manifesting itself in the form of active water geysers on the moon's surface.The effect of the faults on periodic tidal deformation of the moon has so far been neglected because of the difficulties associated with the implementation of fractures in continuum mechanics models. Employing an open source finite element FEniCS package, we provide a numerical estimate of the maximum possible impact of the tiger stripes on the tidal deformation and the heat production in Enceladus's ice shell by representing the faults as narrow zones with negligible frictional and bulk resistance passing vertically through the whole shell.For a uniform ice shell thickness of 25 km, consistent with the recent estimate of libration, and for linear elastic rheology, we demonstrate that the faults can dramatically change the distribution of stress and strain in Enceladus's south polar region, leading to a significant increase of the heat flux and to a complex deformation pattern in this area. We also present preliminary results studying the effects of (i) variable ice-shell thickness, based on the recent topography, gravity and libration inversion model by Čadek et al. (2016) and (ii) Maxwell viscoelastic rheology on the global tidal deformation of the ice shell.O.S. acknowledges support by the Grant Agency of the Czech Republic through the project 15-14263Y.

Changes in Seismic Velocity During the 2004 - 2008 Eruption of Mount St. Helens Volcano

NASA Astrophysics Data System (ADS)

Hotovec-Ellis, A. J.; Vidale, J. E.; Gomberg, J. S.; Moran, S. C.; Thelen, W. A.

2013-12-01

Mount St. Helens (MSH) effusively erupted in late 2004, following an 18-year quiescence. Many swarms of repeating earthquakes accompanied the extrusion and in some cases the waveforms from these earthquakes evolved slowly, possibly reflecting changes in the properties of the volcano that affect seismic wave propagation. We use coda-wave interferometry to quantify these changes in terms of small (usually <1%) changes in seismic velocity structure by determining how relatively condensed or stretched the coda is between two similar earthquakes. We then utilize several hundred distinct families of repeating earthquakes at once to create a continuous function of velocity change observed at any station in the seismic network. The rate of earthquakes allows us to track these changes on a daily or even hourly time scale. Following years of no seismic velocity changes larger than those due to climatic processes (tenths of a percent), we observed decreases in seismic velocity of >1% coincident with the onset of increased earthquake activity beginning September 23, 2004. These changes are largest near the summit of the volcano, and likely related to shallow deformation as magma first worked its way to the surface. Changes in velocity are often attributed to deformation, especially volumetric strain and the opening or closing of cracks, but also with nonlinear responses to ground shaking and fluid intrusion. We compare velocity changes across the eruption with other available observations, such as deformation (e.g., GPS, tilt, photogrammetry), to better constrain the relationships between velocity change and its possible causes.

An incremental analysis of a deep drawing steel’s material behaviour undergoing the predeformation using drawbeads

NASA Astrophysics Data System (ADS)

Schmid, H.; Suttner, S.; Merklein, M.

2017-09-01

Nowadays lightweight design in metal forming processes leads to complex deep drawing geometries, which can cause multiple damages. Therefore, drawbeads are one way to regulate and control material flow during the forming process. Not only in research, but also in industrial practice, it could be determined that material is work hardened passing drawbead geometries. It particularly means when material is pre-deformed with tensile and alternating bending loads. This incident also gives the opportunity to utilize it in a reasonable way if examined properly. To investigate these findings, a process oriented and comprehensive analysis of the material behaviour during these forming operations is needed. In this paper, sheet metal strips are linearly drawn through a drawbead and stopped after passing the drawbead. Within this forming operation, the material undergoes non-linear straining before reaching the in-plane position again. Here, the process will be stopped to investigate a permanent strengthening local along the sheet thickness. Therefore, microhardness measurements are realized before and after passing the drawbead. Because of its common use and its wide known material data, a deep drawing steel DC will be used for these studies. Additionally, the strategy is applied to advanced high strength steel.

Factors Associated with First-Pass Success in Pediatric Intubation in the Emergency Department.

PubMed

Goto, Tadahiro; Gibo, Koichiro; Hagiwara, Yusuke; Okubo, Masashi; Brown, David F M; Brown, Calvin A; Hasegawa, Kohei

2016-03-01

The objective of this study was to investigate the factors associated with first-pass success in pediatric intubation in the emergency department (ED). We analyzed the data from two multicenter prospective studies of ED intubation in 17 EDs between April 2010 and September 2014. The studies prospectively measured patient's age, sex, principal indication for intubation, methods (e.g., rapid sequence intubation [RSI]), devices, and intubator's level of training and specialty. To evaluate independent predictors of first-pass success, we fit logistic regression model with generalized estimating equations. In the sensitivity analysis, we repeated the analysis in children <10 years. A total of 293 children aged ≤18 years who underwent ED intubation were eligible for the analysis. The overall first-pass success rate was 60% (95%CI [54%-66%]). In the multivariable model, age ≥10 years (adjusted odds ratio [aOR], 2.45; 95% CI [1.23-4.87]), use of RSI (aOR, 2.17; 95% CI [1.31-3.57]), and intubation attempt by an emergency physician (aOR, 3.21; 95% CI [1.78-5.83]) were significantly associated with a higher chance of first-pass success. Likewise, in the sensitivity analysis, the use of RSI (aOR, 3.05; 95% CI [1.63-5.70]), and intubation attempt by an emergency physician (aOR, 4.08; 95% CI [1.92-8.63]) were significantly associated with a higher chance of first-pass success. Based on two large multicenter prospective studies of ED airway management, we found that older age, use of RSI, and intubation by emergency physicians were the independent predictors of a higher chance of first-pass success in children. Our findings should facilitate investigations to develop optimal airway management strategies in critically-ill children in the ED.

Timing and nature of tertiary plutonism and extension in the Grouse Creek Mountains, Utah

USGS Publications Warehouse

Egger, A.E.; Dumitru, T.A.; Miller, E.L.; Savage, C.F.I.; Wooden, J.L.

2003-01-01

The Grouse Creek-Albion-Raft River metamorphic core complex in northwestern Utah and southern Idaho is characterized by several Tertiary plutons with a range of ages and crosscutting relations that help constrain the timing of extensional deformation. In the Grouse Creek Mountains, at least three distinct, superimposed, extension-related Tertiary deformational events are bracketed by intrusive rocks, followed by a fourth event: motion on range-bounding faults. The Emigrant Pass plutonic complex was emplaced at depths of less than 10 km into Permianage rocks. SHRIMP U-Pb zircon analysis indicates a three-stage intrusion of the complex at 41.3 ?? 0.3 Ma, 36.1 ?? 0.2 Ma, and 34.3 ?? 0.3 Ma. The two youngest phases represent distinctly younger intrusive event(s) than the oldest phase, separated by more than 5 m.y. The oldest phase cuts several metamorphosed and deformed younger-on-older faults, providing a pre-41 Ma age bracket for oldest extension-related deformation in the region. The youngest phase(s) are interpreted to have been intruded during delelopment of a map-scale. N-S-trending recumbent fold, the Bovine Mountain fold, formed during vertical shortening of roof rocks during intrusion. This second event folded older normal faults that are likely pre-41 Ma. Zircons from the youngest part of the pluton show inheritance from Archean basement (???2.5 Ga) and from its Proterozoic sedimentary cover (???1.65 Ga). The Red Butte pluton, emplaced at 15-20 km depth, intruded highly metamorphosed Archean orthogneiss at 25.3 ?? 0.5 Ma; cores of some zircons yield latest Archean ages of 2.55 Ga. The pluton is interpreted to have been intruded during a third deformational and metamorphic event that resulted in vertical flattening fabrics formed during NW to EW stretching, ultimately leading to thinning of cover and top-to-the west motion on the Ingham Pass fault. The Ingham Pass fault represents an important structure in the Grouse Creek Mountains, as it juxtaposes two parts of the crust that apparently resided as much as 10 km apart (in depth) at times as young as the Miocene. The varied structural, metamorphic, and intrusive relations obsreved in the Grouse Creek Mountains reflect their formation at different levels within the crust. Data from these various levels argue that plutonism has been a key mechanism far transferring heat into the middle and upper crust, and localizing strain during regional extension. Interestingly, events documented here correlate in a broad way with cooling events documented in the Raft River Mountains, although plutons are not exposed there. Major and trace element geochemistry imply a crustal component in all of the studied plutons, indicating significant degrees of crustal melting at depth during extension, and point to mantle heat sources during the timespan of Basin and Range extension as the cause of melting. Basin and Range faulting and final uplift of the range is recorded by apatite fission track ages, averaging 13.4 Ma, and deposition of about 2 km of syn-faulting basin fill deposits along the Grouse Creek fault mapped along the western flank of the range. Similar apatite ages from the Albion Mountains to the north indicate that the western side of the Albion-Raft River-Grouse Creek core complex behaved as a single rigid crustal block at this time.

Coseismic seafloor deformation in the trench region during the Mw8.8 Maule megathrust earthquake.

PubMed

Maksymowicz, A; Chadwell, C D; Ruiz, J; Tréhu, A M; Contreras-Reyes, E; Weinrebe, W; Díaz-Naveas, J; Gibson, J C; Lonsdale, P; Tryon, M D

2017-04-05

The M w 8.8 megathrust earthquake that occurred on 27 February 2010 offshore the Maule region of central Chile triggered a destructive tsunami. Whether the earthquake rupture extended to the shallow part of the plate boundary near the trench remains controversial. The up-dip limit of rupture during large subduction zone earthquakes has important implications for tsunami generation and for the rheological behavior of the sedimentary prism in accretionary margins. However, in general, the slip models derived from tsunami wave modeling and seismological data are poorly constrained by direct seafloor geodetic observations. We difference swath bathymetric data acquired across the trench in 2008, 2011 and 2012 and find ~3-5 m of uplift of the seafloor landward of the deformation front, at the eastern edge of the trench. Modeling suggests this is compatible with slip extending seaward, at least, to within ~6 km of the deformation front. After the M w 9.0 Tohoku-oki earthquake, this result for the Maule earthquake represents only the second time that repeated bathymetric data has been used to detect the deformation following megathrust earthquakes, providing methodological guidelines for this relatively inexpensive way of obtaining seafloor geodetic data across subduction zone.

Cell response to nanocrystallized metallic substrates obtained through severe plastic deformation.

PubMed

Bagherifard, Sara; Ghelichi, Ramin; Khademhosseini, Ali; Guagliano, Mario

2014-06-11

Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief description of the mechanism for each process. The results obtained for each treatment on cell morphology, adhesion, proliferation, and differentiation, as well as the in vivo studies, are discussed. Finally, the advantages and challenges regarding the application of these techniques to produce multifunctional bio-implant materials are addressed.

Varied dose exposures to ultrafine particles in the motorcycle smoke cause kidney cell damages in male mice.

PubMed

Wardoyo, Arinto Y P; Juswono, Unggul P; Noor, Johan A E

2018-01-01

Ultrafine particles (UFPs) are one of motorcycle exhaust emissions which can penetrate the lung alveoli and deposit in the kidney. This study was aimed to investigate mice kidney cell physical damage (deformation) due to motorcycle exhaust emission exposures. The motorcycle exhaust emissions were sucked from the muffler with the rate of 33 cm 3 /s and passed through an ultrafine particle filter system before introduced into the mice exposure chamber. The dose concentration of the exhaust emissions was varied by setting the injected time of the 20s, 40s, 60s, 80s, and 100s. The mice were exposed to the smoke in the chamber for 100 s twice a day. The impact of the ultrafine particles on the kidney was observed by identifying the histological image of the kidney cell deformation using a microscope. The exposure was conducted for 10 days. The kidney observations were carried out on day 11. The results showed that there was a significant linear correlation between the total concentration of ultrafine particles deposited in the kidneys and the physical damage percentages. The increased concentrations of ultrafine particles caused larger cell deformation to the kidneys.

Effect of Intensive Plastic Deformation on Microstructure and Mechanical Properties of Aluminum Alloys

NASA Astrophysics Data System (ADS)

Rakhadilov, Bauyrzhan; Uazyrkhanova, Gulzhaz; Myakinin, Alexandr; Uazyrkhanova, Zhuldyz

2016-08-01

In work it was studied the influence of intensive plastic deformation on structure and mechanical properties of aluminum alloys. Intensive plastic deformation was carried out by using equal-channel angular extrusion. It is shown that the most efficient angle of intersection of the channels is the angle of Φ=120°, which ensures defect-free parts at the highest possible level of accumulated strain (e=8). It is established that the intensive milling grain structures in aluminum alloys AMG6 and AMC occurs at ECAE-12 passes, while the intersection angle of the channels of 120°. After ECAE-12 in aluminum alloys the grain refinement reaches to the size of ∼⃒1.0-1.5 gm. It is determined that as a result of equal channel angular pressing, the microhardness of alloy AMG6 increases almost 4 times in comparison with the initial state, the microhardness of alloy AMC increases by almost 4.5 times in comparison with the initial state. It is shown that ECAE-12 mass loss is reduced to 5.4 and 5.6 mg, which shows an increase in wear-resistance of aluminum alloys AMG6 and AMC 13-14 %.

Effect of severe plastic deformation on microstructure and mechanical properties of magnesium and aluminium alloys in wide range of strain rates

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir; Skripnyak, Evgeniya; Skripnyak, Vladimir; Vaganova, Irina; Skripnyak, Nataliya

2013-06-01

Results of researches testify that a grain size have a strong influence on the mechanical behavior of metals and alloys. Ultrafine grained HCP and FCC metal alloys present higher values of the spall strength than a corresponding coarse grained counterparts. In the present study we investigate the effect of grain size distribution on the flow stress and strength under dynamic compression and tension of aluminium and magnesium alloys. Microstructure and grain size distribution in alloys were varied by carrying out severe plastic deformation during the multiple-pass equal channel angular pressing, cyclic constrained groove pressing, and surface mechanical attrition treatment. Tests were performed using a VHS-Instron servo-hydraulic machine. Ultra high speed camera Phantom V710 was used for photo registration of deformation and fracture of specimens in range of strain rates from 0,01 to 1000 1/s. In dynamic regime UFG alloys exhibit a stronger decrease in ductility compared to the coarse grained material. The plastic flow of UFG alloys with a bimodal grain size distribution was highly localized. Shear bands and shear crack nucleation and growth were recorded using high speed photography.

Structure and thermochronology of the metamorphic core of the Brooks Range, Alaska

NASA Astrophysics Data System (ADS)

Toro, Jaime

1999-11-01

Detailed field studies were undertaken in two key areas of the Central Belt of the Brooks Range: (1) the north flank of Mt. Igikpak in the Survey Pass Quadrangle and (2) in the Shishakshinovik Pass area in the eastern Ambler River Quadrangle. In both areas structural, stratigraphic, petrologic, 40Ar/39Ar, apatite fission-track and U-Pb data were used to constrain the kinematic and thermal history of metamorphic rocks of those areas. North of the Mt. Igikpak massif a crustal section ˜15 km thick is exposed. There are upper greenschist facies rocks in the deeper portions, and very low grade metamorphic rocks at higher structural levels. Two foliations are found: a higher grade relict S1 fabric and a lower grade S 2 fabric that controls the metamorphic layering. 40Ar/ 39Ar analyses from S1 white mica in the low-grade rocks at the northern end of the transect indicate that peak M1 metamorphism occurred before ˜112 Ma. We ascribe M1 to shortening that occurred during collision of an island arc against the Arctic Alaska margin. S 2 involved the retrogression of earlier assemblages. Kinematic indicators on S2 are top-to-the-north. A rapid cooling event from 500 +/- 50°C to 300 +/- 50°C took place between ˜98 and ˜90 Ma. The driving mechanism for ductile deformation during S2, and for rapid cooling documented by our thermochronologic data, was probably the gravitational collapse of the core of the orogen, over-thickened during the preceding collision. At Shishakshinovik Pass there are Mississippian Lisburne Group strata surrounded by metamorphic rocks typical of the Central Belt of the Brooks Range. All the rocks at Shishakshinovik Pass are intensely deformed, so that one cannot distinguish between an autochthonous and an allochthonous sequence. Furthermore the Mississippian rocks, instead of being attached to the underlying basement, are in the hanging wall of a northwest dipping shear zone. Based on the variations in metamorphic grade and the 40Ar/ 39Ar thermochronology, we argue that this shear zone was an extensional structure active during the mid-Cretaceous orogenic collapse of the Brooks Range. A consequence of this structural interpretation is that the Endicott Mountains allochthon need not be restored south of the Shishakshinovik orthogneiss.

Robust Wave-front Correction in a Small Scale Adaptive Optics System Using a Membrane Deformable Mirror

NASA Astrophysics Data System (ADS)

Choi, Y.; Park, S.; Baik, S.; Jung, J.; Lee, S.; Yoo, J.

A small scale laboratory adaptive optics system using a Shack-Hartmann wave-front sensor (WFS) and a membrane deformable mirror (DM) has been built for robust image acquisition. In this study, an adaptive limited control technique is adopted to maintain the long-term correction stability of an adaptive optics system. To prevent the waste of dynamic correction range for correcting small residual wave-front distortions which are inefficient to correct, the built system tries to limit wave-front correction when a similar small difference wave-front pattern is repeatedly generated. Also, the effect of mechanical distortion in an adaptive optics system is studied and a pre-recognition method for the distortion is devised to prevent low-performance system operation. A confirmation process for a balanced work assignment among deformable mirror (DM) actuators is adopted for the pre-recognition. The corrected experimental results obtained by using a built small scale adaptive optics system are described in this paper.

Evaluation of cutting ability and plastic deformation of reciprocating files.

PubMed

Kowalczuck, Alexandre; Sydney, Gilson Blitzkow; Martinez, Elizabeth Ferreira; Cardoso, Rielson José Alves

2016-01-01

This in vitro study evaluated the cutting ability of reciprocating files and the deformations caused by their multiple use. Five Reciproc® R25 files were divided into five groups for 10 simulated root canal preparations each. The resin blocks were weighed and photographed (12.5X and 20X) before and after preparation. The canals were prepared according to the manufacturer's instructions. Enlargement of the root canals was evaluated by comparison of pre- and post-preparation images using a computer software. The preoperative and postoperative weight differences determined the cutting ability of repeatedly used instruments. The data were analyzed using Lilliefors and Friedman statistical tests. The cutting ability and enlargement of the canals gradually decreased after each use, with significant differences observed at the 8th and 9th repetitions, respectively. There was no evidence of file deformation. The cutting ability and enlargement of the simulated canals gradually decreased when a reciprocating file was used up to 10 times.

Deposition of amorphous carbon nitride films on flexible substrates by reactive sputtering for applications in light-driven active devices

NASA Astrophysics Data System (ADS)

Aono, Masami; Harata, Tomo; Odawara, Taku; Asai, Shinnosuke; Orihara, Dai; Nogi, Masaya

2018-01-01

Amorphous carbon nitride (a-CN x ) thin films deposited by reactive sputtering have great potential for driving source applications of light-driven active devices. We demonstrate, for the first time, the photoinduced deformation of a-CN x deposited on flexible substrates, namely, poly(ethylene naphthalate) (PEN) films and transparent cellulose nanopaper. a-CN x films without delamination were obtained on both substrates. By decreasing the thickness of PEN films, the photoinduced deformation became extremely large. A light-driven pump was fabricated using a-CN x -coated PEN films, and then the pumping motion was observed up to 10 Hz. When a He-Ne laser traced the surface of a-CN x films deposited on the nanopaper, the sample moved to the opposite side of the laser spot. The motion involved repeated expansions and contractions similar to the motion of caterpillars occurring owing to the temporary photoinduced deformation of a-CN x films.

SU-F-BRF-13: Investigating the Feasibility of Accurate Dose Measurement in a Deforming Radiochromic Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, T; Adamovics, J; Oldham, M

Purpose: Presage-Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage-Def to validate dose-accumulation algorithms in deforming structures. Methods: Two cylindrical Presage-Def dosimeters (8cm diameter, 4.5cm length) were irradiated in a water-bath with a simple 4-field box treatment. Isocentric dose was 20Gy. One dosimeter served as control (no deformation) while the other was laterally compressed during irradiation by 21%. Both dosimeters were imaged before and after irradiation with a fast (∼10 minutes for 1mm isotropic resolution), broad beam, highmore » resolution optical-CT scanner. Measured dose distributions were compared to corresponding distributions calculated by a commissioned Eclipse planning system. Accuracy in the control was evaluated with 3D gamma (3%/3mm). The dose distribution calculated for the compressed dosimeter in the irradiation geometry cannot be directly compared via profiles or 3D gamma to the measured distribution, which deforms with release from compression. Thus, accuracy under deformation was determined by comparing integral dose within the high dose region of the deformed dosimeter distribution versus calculated dose. Dose profiles were used to study temporal stability of measured dose distributions. Results: Good dose agreement was demonstrated in the control with a 3D gamma passing rate of 96.6%. For the dosimeter irradiated under compression, the measured integral dose in the high dose region (518.0Gy*cm3) was within 6% of the Eclipse-calculated integral dose (549.4Gy*cm3). Elevated signal was noted on the dosimeter edge in the direction of compression. Change in dosimeter signal over 1.5 hours was ≤2.7%, and the relative dose distribution remained stable over this period of time. Conclusion: Presage-Def is promising as a 3D dosimeter capable of accurately measuring dose in a deforming structure, and warrants further study to quantify comprehensive accuracy at different levels of deformation. This work was supported by NIH R01CA100835. John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.« less

Technical Note: The impact of deformable image registration methods on dose warping.

PubMed

Qin, An; Liang, Jian; Han, Xiao; O'Connell, Nicolette; Yan, Di

2018-03-01

The purpose of this study was to investigate the clinical-relevant discrepancy between doses warped by pure image based deformable image registration (IM-DIR) and by biomechanical model based DIR (BM-DIR) on intensity-homogeneous organs. Ten patients (5Head&Neck, 5Prostate) were included. A research DIR tool (ADMRIE_v1.12) was utilized for IM-DIR. After IM-DIR, BM-DIR was carried out for organs (parotids, bladder, and rectum) which often encompass sharp dose gradient. Briefly, high-quality tetrahedron meshes were generated and deformable vector fields (DVF) from IM-DIR were interpolated to the surface nodes of the volume meshes as boundary condition. Then, a FEM solver (ABAQUS_v6.14) was used to simulate the displacement of internal nodes, which were then interpolated to image-voxel grids to get the more physically plausible DVF. Both geometrical and subsequent dose warping discrepancies were quantified between the two DIR methods. Target registration discrepancy(TRD) was evaluated to show the geometry difference. The re-calculated doses on second CT were warped to the pre-treatment CT via two DIR. Clinical-relevant dose parameters and γ passing rate were compared between two types of warped dose. The correlation was evaluated between parotid shrinkage and TRD/dose discrepancy. The parotid shrunk to 75.7% ± 9% of its pre-treatment volume and the percentage of volume with TRD>1.5 mm) was 6.5% ± 4.7%. The normalized mean-dose difference (NMDD) of IM-DIR and BM-DIR was -0.8% ± 1.5%, with range (-4.7% to 1.5%). 2 mm/2% passing rate was 99.0% ± 1.4%. A moderate correlation was found between parotid shrinkage and TRD and NMDD. The bladder had a NMDD of -9.9% ± 9.7%, with BM-DIR warped dose systematically higher. Only minor deviation was observed for rectum NMDD (0.5% ± 1.1%). Impact of DIR method on treatment dose warping is patient and organ-specific. Generally, intensity-homogeneous organs, which undergo larger deformation/shrinkage during treatment and encompass sharp dose gradient, will have greater dose warping uncertainty. For these organs, BM-DIR could be beneficial to the evaluation of DIR/dose-warping uncertainty. © 2018 American Association of Physicists in Medicine.

Basement-driven strike-slip deformation involving a salt-stock canopy system

NASA Astrophysics Data System (ADS)

Dooley, Tim; Jackson, Martin; Hudec, Mike

2016-04-01

NW-striking basement-involved strike-slip zones have been reported or inferred from the northern Gulf of Mexico (GoM). This interpretation is uncertain, because the effects of strike-slip deformation are commonly difficult to recognize in cross sections. Recognition is doubly difficult if the strike-slip zone passes through a diapir field that complicates deformation, and an associated salt canopy that partially decouples shallow deformation from deep deformation. We use physical models to explore the effects of strike-slip deformation above and below a salt-stock canopy system. Canopies of varying maturity grew from a series of 14 feeders/diapirs located on and off the axis of a dextral basement fault. Strike-slip deformation styles in the overburden vary significantly depending on: (1) the location of the diapirs with respect to the basement fault trace, and; (2) the continuity of the canopy system. On-axis diapirs (where the diapirs lie directly above the basement fault) are typically strongly deformed and pinched shut at depth to form sharp S-shapes, whereas their shallow deformation style is that of a open-S-shaped pop-up structure in a restraining bend. The narrow diapir stem acts as a shear zone at depth. Pull-apart structures form between diapirs that are arranged in a right-stepping array tangental to the basement fault trace. These grade along strike into narrow negative flower structures. Off-axis diapirs (diapirs laterally offset from the basement fault but close enough to participate in the deformation) form zones of distributed deformation in the form of arrays of oblique faults (R shears) that converge along strike onto the narrower deformation zones associated with on-axis diapirs. Above an immature, or patchy, canopy system the strike-slip structures closely match sub canopy structures, with the exception of wrench fold formation where the supracanopy roof is thin. In contrast, the surface structures above a mature canopy system consist of a broad zone of PDZ-parallel faults and high-angle wrench folds, strongly decoupled from the subcanopy structure. The exception to this is where there are gaps (windows) in the canopy, allowing coupling to the deeper deformation field. In this mature canopy open-S planforms are muted as deformation is spread over a broader area of coalesced salt sheets, except at the canopy edge and where the supracanopy roof is thin. Supracanopy structures are also influenced by the sutures between the individual salt sheets. Results from this set of analog models are potentially useful as predictive tools to understand the origin and geometry of structures in areas where subsurface data is scarce or data quality is poor.

3D digital image correlation investigation of PLC effect in a new Ni-Co base superalloy

NASA Astrophysics Data System (ADS)

Gao, Y.; Fu, S. H.; Cheng, T.; Huo, X.; Zhang, Q. C.

2013-06-01

Repeated plastic instability accompanying serrated yielding in stress-strain curves and localization of deformation is observed during plastic deformation of many metallic alloys when tensile specimens are deformed under certain experimental conditions of temperature, strain rate, and pre-deformation. This phenomenon is referred to as the Portevin- Le Chatelier (PLC) effect. TMW alloy, a newly developed Ni-Co base superalloy for aircraft engine application, also exhibit PLC effect during tensile test at temperatures ranging from 300 ° to 600 °, which are also the temperature range for engine working. In this paper, a 3D digital image correlation (3D DIC) measurement system was established to observe the localization of deformation (PLC band) in a tensile test performed on TMW alloy specimen at temperature of 400 °. The 3D DIC system, with displacement measurement accuracy up to 0.01 pixels and strain measurement accuracy up to 100 μɛ, has a high performance in displacement field calculation with more than 10000 points every second on a 3.1G Hz CPU computer. The test result shows that, the PLC bands are inclined at an angle of about 60° to the tensile axis. Unlike tensile test performed on aluminums alloy, the widths of PLC bands of TMW alloy specimen, ranging from 4 mm to 4.5 mm, are much greater than the specimen thickness (0.25 mm).

Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and Carbon nanohorns

PubMed Central

Maharaj, Dave; Bhushan, Bharat

2015-01-01

Nano-objects have been investigated for drug delivery, oil detection, contaminant removal, and tribology applications. In some applications, they are subjected to friction and deformation during contact with each other and their surfaces on which they slide. Experimental studies directly comparing local and global deformation are lacking. This research performs nanoindentation (local deformation) and compression tests (global deformation) with a nanoindenter (sharp tip and flat punch, respectively) on molybdenum disulfide (MoS2) multi-walled nanotubes (MWNTs), ~500 nm in diameter. Hardness of the MoS2 nanotube was similar to bulk and does not follow the “smaller is stronger” phenomenon as previously reported for other nano-objects. Tungsten disulfide (WS2) MWNTs, ~300 nm in diameter and carbon nanohorns (CNHs) 80–100 nm in diameter were of interest and also selected for compression studies. These studies aid in understanding the mechanisms involved during global deformation when nano-objects are introduced to reduce friction and wear. For compression, highest loads were required for WS2 nanotubes, then MoS2 nanotubes and CNHs to achieve the same displacement. This was due to the greater number of defects with the MoS2 nanotubes and the flexibility of the CNHs. Repeat compression tests of nano-objects were performed showing a hardening effect for all three nano-objects. PMID:25702922

Effect of Cooling Mode on Microstructure and Mechanical Properties of Pipeline Steel for Strain Based Design and Research on its Deformation Mechanism

NASA Astrophysics Data System (ADS)

Hesong, Zhang; Yonglin, Kang

With the rapid development of oil and gas industry long distance pipelines inevitably pass through regions with complex geological activities. In order to avoid large deformation the pipelines must be designed based on strain criteria. In this paper the alloy system of X80 high deformability pipeline steel was designed which was 0.25%Mo-0.05%C-1.75%Mn. The effect of controlled cooling process on microstructure and mechanical properties of X80 high deformability pipeline steel were systematically investigated. Through the two-stage controlled cooling process the microstructure of the X80 high deformability pipeline steel were ferrite, bainite and M/A island. There were two kinds of ferrite which were polygonal ferrite (PF) and quasi-polygonal ferrite (QF). The bainite was granular bainite ferrite (GF). Along with the decrease of the start cooling temperature, the volume fraction of ferrite and M/A both increased, the yield ratio (Y/T) decreased, the uniform elongation (uEl) increased firstly with the content of ferrite increased but then decreased with the content and size of M/A increased. When the finish cooling temperature decreasing, the size of M/A became finer. As the start cooling temperature was 690 °C and the finish cooling temperature was 450 °C the volume fraction of ferrite was 23%, the size of ferrite grain was 5μm, the size of M/A island was below 1μm and the structure uniformity was the best. The deformation mechanism of X80 high deformability pipeline steel was analyzed. The best way to improve the work hardening rate was reducing the size of M/A islands on the premise of a certain volume fraction. The decreasing path of instantaneous strain hardening index (n*-value) showed three stages in the deformation process. The n*-value kept stable in the second stage, the reason was that the retained austenite transformed into martensite and the phase transition improved the strain hardening ability of the microstructure. This phenomenon was called transformation induced plasticity effect (TRIP).

Ultra Lightweight Mirror Fabrication Technology

DTIC Science & Technology

1983-12-01

supported on-back at three points, 120 degrees apart at the 0.7 radial zone. The surface deformation, produced by a one-g gravity load applied to a...reliable and repeatable simulation of zero- gravity . 16 * ....- • • ~~~~~~. ,. ........ ...... ....... o....... .. -.. . ...... " . - tively... gravity loading. The stability of this mirru, over these environmental conditions is considered to be excellent. The interferometrically measured surface

Law of damage accumulation and fracture criteria in highly filled polymer materials

NASA Astrophysics Data System (ADS)

Bykov, D. L.; Kazakov, A. V.; Konovalov, D. N.; Mel'nikov, V. P.; Milyokhin, Yu. M.; Peleshko, V. A.; Sadovnichii, D. N.

2014-09-01

We present the results of a large series of experiments aimed at the study of laws of damage accumulation and fracture in highly filled polymer materials under loading conditions of various types: monotone, repeated, low- and high-cycle, with varying type of stress state, dynamic (in general, more than 50 programs implemented on specimens from one lot of material). The data obtained in these test allow one to make conclusions about the constitutive role of the attained maximum of strain intensity when estimating the accumulated damage in the process of uniaxial tension by various programs (in particular, an additional cyclic deformation below the preliminary attained strain maximum does not affect the limit values of strain and stress in the subsequent active extension), about the strong influence of the stress state on the deformation and fracture, about the specific features of the nonlinear behavior of the material under the shock loading conditions and its influence on the repeated deformation. All tests are described (with an accuracy acceptable in practical calculations, both with respect to stresses and strains in the process of loading and at the moment of fracture) in the framework of the same model of nonlinear viscoelasticity with the same set of constants. The constants of the proposed model are calculated according to a relatively simple algorithm by using the results of standard uniaxial tension tests with constant values of the strain rate and hydrostatic pressure (each test for 2-3 levels of these parameters chosen from the ranges proposed in applications, each loading lasts until the fracture occurs, and one of the tests contains an intermediate interval of total loading and repeated loading) and one axial shock compression test if there are dynamic problems in the applications. The model is based on the use of the criterion fracture parameter which, in the class of proportional loading processes, is the sum of partial increments of the strain intensity on active segments of the process (where the strain intensity is at its historical maximum) with the form of the stress state and the intensity of strain rates taken into account.

Recent deformation in the Turan and South Kazakh platforms, western central Asia, and its relation to Arabia-Asia and India-Asia collisions

NASA Astrophysics Data System (ADS)

Thomas, Jean-Charles; Grasso, Jean-Robert; Bossu, RéMy; Martinod, Joseph; Nurtaev, Bakhthiar

1999-04-01

In this study, we investigate the recent and active tectonics of the Turan and South Kazakh platforms in western central Asia. This area, which has been considered stable during the Tertiary, was struck in its eastern part (Gazli and Kyzyl-Kum) by three earthquakes of magnitude Ms ˜7.0 between 1976 and 1984. From structural observations we show that in the Kyzyl-Kum, Cenozoic deformation on structures oriented NW-SE is dominated by dextral strike-slip motion on a flower structure involving reactivated Late Paleozoic faults. This deformation is compatible with the stress pattern induced by the Pamir/Tien Shan collision zone. At the scale of the Turan-South Kazakh platform, comparison of repeated leveling measurements gives mean uplift rates of 5 mm yr-1 for most of the area south of the 44° latitude including the Kyzyl-Kum. These observations indicate that the Turan-South Kazakh platform has been actively deforming since recent times (Pleistocene) in response to the collision of both India and Arabia with Asia. Earthquake data also reveal that propagation of deformation from the Kopet Dagh and the Pamir/Tien Shan collision zones into the Turan-South Kazakh platform is accommodated aseismically except in the Kyzyl-Kum. This might reflect differences in the deformation style and nature of the upper crust in the Kyzyl-Kum and north of the Kopet Dagh respectively. We propose that the Gazli earthquakes highlight the northwestward continuation, within the Turan-South Kazakh platform and along reactivated older structures, of the deformation related to the Pamir indentation and to a lesser degree to the Arabia-Asia convergence.

Pre-eruptive ground deformation of Azerbaijan mud volcanoes detected through satellite radar interferometry (DInSAR)

NASA Astrophysics Data System (ADS)

Antonielli, Benedetta; Monserrat, Oriol; Bonini, Marco; Righini, Gaia; Sani, Federico; Luzi, Guido; Feyzullayev, Akper A.; Aliyev, Chingiz S.

2014-12-01

Mud volcanism is a process that leads to the extrusion of subsurface mud, fragments of country rocks, saline waters and gases. This mechanism is typically linked to hydrocarbon traps, and the extrusion of this material builds up a variety of conical edifices with a similar morphology to those of magmatic volcanoes, though smaller in size. The Differential Interferometry Synthetic Aperture Radar (DInSAR) technique has been used to investigate the ground deformation related to the activity of the mud volcanoes of Azerbaijan. The analysis of a set of wrapped and unwrapped interferograms, selected according to their coherence, allowed the detection of significant superficial deformation related to the activity of four mud volcanoes. The ground displacement patterns observed during the period spanning from October 2003 to November 2005 are dominated by uplift, which reach a cumulative value of up to 20 and 10 cm at the Ayaz-Akhtarma and Khara-Zira Island mud volcanoes, respectively. However, some sectors of the mud volcano edifices are affected by subsidence, which might correspond to deflation zones that coexist with the inflation zones characterized by the dominant uplift. Important deformation events, caused by fluid pressure and volume variations, have been observed both (1) in connection with main eruptive events in the form of pre-eruptive uplift, and (2) in the form of short-lived deformation pulses that interrupt a period of quiescence. Both deformation patterns show important similarities to those identified in some magmatic systems. The pre-eruptive uplift has been observed in many magmatic volcanoes as a consequence of magma intrusion or hydrothermal fluid injection. Moreover, discrete short-duration pulses of deformation are also experienced by magmatic volcanoes and are repeated over time as multiple inflation and deflation events.

Use of embedded strain gages for the in-vitro study of proximal tibial cancellous bone deformation during knee flexion-extension movement: development, reproducibility and preliminary results of feasibility after frontal low femoral osteotomy

PubMed Central

2011-01-01

Background This paper reports the development of an in-vitro technique allowing quantification of relative (not absolute) deformations measured at the level of the cancellous bone of the tibial proximal epiphysis (CBTPE) during knee flexion-extension. This method has been developed to allow a future study of the effects of low femoral osteotomies consequence on the CBTPE. Methods Six strain gages were encapsulated in an epoxy resin solution to form, after resin polymerisation, six measurement elements (ME). The latter were inserted into the CBTPE of six unembalmed specimens, just below the tibial plateau. Knee motion data were collected by three-dimensional (3D) electrogoniometry during several cycles of knee flexion-extension. Intra- and inter-observer reproducibility was estimated on one specimen for all MEs. Intra-specimen repeatability was calculated to determine specimen's variability and the error of measurement. A varum and valgum chirurgical procedure was realised on another specimen to observed CBTPE deformation after these kind of procedure. Results Average intra-observer variation of the deformation ranged from 8% to 9% (mean coefficient of variation, MCV) respectively for extension and flexion movement. The coefficient of multiple correlations (CMC) ranged from 0.93 to 0.96 for flexion and extension. No phase shift of maximum strain peaks was observed. Inter-observer MCV averaged 23% and 28% for flexion and extension. The CMC were 0.82 and 0.87 respectively for extension and flexion. For the intra-specimen repeatability, the average of mean RMS difference and the mean ICC were calculated only for flexion movement. The mean RMS variability ranged from 7 to 10% and the mean ICC was 0.98 (0.95 - 0.99). A Pearson's correlation coefficient was calculated showing that RMS was independent of signal intensity. For the chirurgical procedure, valgum and varum deviation seems be in agree with the frontal misalignment theory. Conclusions Results show that the methodology is reproducible within a range of 10%. This method has been developed to allow analysis the indirect reflect of deformation variations in CBTPE before and after distal femoral osteotomies. The first results of the valgum and varum deformation show that our methodology allows this kind of measurement and are encourageant for latter studies. It will therefore allow quantification and enhance the understanding of the effects of this kind of surgery on the CBTPE loading. PMID:21371297

Use of embedded strain gages for the in-vitro study of proximal tibial cancellous bone deformation during knee flexion-extension movement: development, reproducibility and preliminary results of feasibility after frontal low femoral osteotomy.

PubMed

Sobczak, Stéphane; Salvia, Patrick; Dugailly, Pierre-Michel; Lefèvre, Philippe; Feipel, Véronique; Van Sint Jan, Serge; Rooze, Marcel

2011-03-03

This paper reports the development of an in-vitro technique allowing quantification of relative (not absolute) deformations measured at the level of the cancellous bone of the tibial proximal epiphysis (CB(TPE)) during knee flexion-extension. This method has been developed to allow a future study of the effects of low femoral osteotomies consequence on the CB(TPE). Six strain gages were encapsulated in an epoxy resin solution to form, after resin polymerisation, six measurement elements (ME). The latter were inserted into the CB(TPE) of six unembalmed specimens, just below the tibial plateau. Knee motion data were collected by three-dimensional (3D) electrogoniometry during several cycles of knee flexion-extension. Intra- and inter-observer reproducibility was estimated on one specimen for all MEs. Intra-specimen repeatability was calculated to determine specimen's variability and the error of measurement. A varum and valgum chirurgical procedure was realised on another specimen to observed CB(TPE) deformation after these kind of procedure. Average intra-observer variation of the deformation ranged from 8% to 9% (mean coefficient of variation, MCV) respectively for extension and flexion movement. The coefficient of multiple correlations (CMC) ranged from 0.93 to 0.96 for flexion and extension. No phase shift of maximum strain peaks was observed. Inter-observer MCV averaged 23% and 28% for flexion and extension. The CMC were 0.82 and 0.87 respectively for extension and flexion. For the intra-specimen repeatability, the average of mean RMS difference and the mean ICC were calculated only for flexion movement. The mean RMS variability ranged from 7 to 10% and the mean ICC was 0.98 (0.95-0.99). A Pearson's correlation coefficient was calculated showing that RMS was independent of signal intensity. For the chirurgical procedure, valgum and varum deviation seems be in agree with the frontal misalignment theory. Results show that the methodology is reproducible within a range of 10%. This method has been developed to allow analysis the indirect reflect of deformation variations in CB(TPE) before and after distal femoral osteotomies. The first results of the valgum and varum deformation show that our methodology allows this kind of measurement and are encourageant for latter studies. It will therefore allow quantification and enhance the understanding of the effects of this kind of surgery on the CB(TPE) loading.

An Investigation of Physico-Mechanical Properties of Ultrafine-Grained Magnesium Alloys Subjected to Severe Plastic Deformation

NASA Astrophysics Data System (ADS)

Kozulyn, A. A.; Skripnyak, V. A.; Krasnoveikin, V. A.; Skripnyak, V. V.; Karavatskii, A. K.

2015-01-01

The results of investigations of physico-mechanical properties of specimens made from the structural Mg-based alloy (Russian grade Ma2-1) in its coarse-grained and ultrafine-grained states after SPD processing are presented. To form the ultrafine-grained structure, use was made of the method of orthogonal equal-channel angular pressing. After four passes through the die, a simultaneous increase was achieved in microhardness, yield strength, ultimate tensile strength and elongation to failure under conditions of uniaxial tensile loading.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreev, A L; Andreeva, T B; Kompanets, I N

We have studied the method for suppressing speckle noise in patterns produced by a laser based on a fast-response electro-optical cell with a ferroelectric liquid crystal (FLC) in which helicoid is absent, i.e., compensated for. The character of smectic layer deformation in an electric field is considered along with the mechanism of spatially inhomogeneous phase modulation of a laser beam passing through the cell which is accompanied by the destruction of phase relations in the beam. Advantages of a helix-free FLC cell are pointed out as compared to helical crystal cells studied previously. (liquid crystal devices)

Measuring Aseismic Slip through Characteristically Repeating Earthquakes at the Mendocino Triple Junction, Northern California

NASA Astrophysics Data System (ADS)

Materna, K.; Taira, T.; Burgmann, R.

2016-12-01

The Mendocino Triple Junction (MTJ), at the transition point between the San Andreas fault system, the Mendocino Transform Fault, and the Cascadia Subduction Zone, undergoes rapid tectonic deformation and produces more large (M>6.0) earthquakes than any region in California. Most of the active faults of the triple junction are located offshore, making it difficult to characterize both seismic slip and aseismic creep. In this work, we study aseismic creep rates near the MTJ using characteristically repeating earthquakes (CREs) as indicators of creep rate. CREs are generally interpreted as repeated failures of the same seismic patch within an otherwise creeping fault zone; as a consequence, the magnitude and recurrence time of the CREs can be used to determine a fault's creep rate through empirically calibrated scaling relations. Using seismic data from 2010-2016, we identify CREs as recorded by an array of eight 100-Hz PBO borehole seismometers deployed in the Cape Mendocino area. For each event pair with epicenters less than 30 km apart, we compute the cross-spectral coherence of 20 seconds of data starting one second before the P-wave arrival. We then select pairs with high coherence in an appropriate frequency band, which is determined uniquely for each event pair based on event magnitude, station distance, and signal-to-noise ratio. The most similar events (with median coherence above 0.95 at two or more stations) are selected as CREs and then grouped into CRE families, and each family is used to infer a local creep rate. On the Mendocino Transform Fault, we find relatively high creep rates of >5 cm/year that increase closer to the Gorda Ridge. Closer to shore and to the MTJ itself, we find many families of repeaters on and off the transform fault with highly variable creep rates, indicative of the complex deformation that takes place there.

Does an Adolescent’s Accuracy of Recall Improve with a Second 24-h Dietary Recall?

PubMed Central

Kerr, Deborah A.; Wright, Janine L.; Dhaliwal, Satvinder S.; Boushey, Carol J.

2015-01-01

The multiple-pass 24-h dietary recall is used in most national dietary surveys. Our purpose was to assess if adolescents’ accuracy of recall improved when a 5-step multiple-pass 24-h recall was repeated. Participants (n = 24), were Chinese-American youths aged between 11 and 15 years and lived in a supervised environment as part of a metabolic feeding study. The 24-h recalls were conducted on two occasions during the first five days of the study. The four steps (quick list; forgotten foods; time and eating occasion; detailed description of the food/beverage) of the 24-h recall were assessed for matches by category. Differences were observed in the matching for the time and occasion step (p < 0.01), detailed description (p < 0.05) and portion size matching (p < 0.05). Omission rates were higher for the second recall (p < 0.05 quick list; p < 0.01 forgotten foods). The adolescents over-estimated energy intake on the first (11.3% ± 22.5%; p < 0.05) and second recall (10.1% ± 20.8%) compared with the known food and beverage items. These results suggest that the adolescents’ accuracy to recall food items declined with a second 24-h recall when repeated over two non-consecutive days. PMID:25984743

Apparatus and process for the refrigeration, liquefaction and separation of gases with varying levels of purity

DOEpatents

Bingham, Dennis N.; Wilding, Bruce M.; McKellar, Michael G.

2002-01-01

A process for the separation and liquefaction of component gasses from a pressurized mix gas stream is disclosed. The process involves cooling the pressurized mixed gas stream in a heat exchanger so as to condensing one or more of the gas components having the highest condensation point; separating the condensed components from the remaining mixed gas stream in a gas-liquid separator; cooling the separated condensed component stream by passing it through an expander; and passing the cooled component stream back through the heat exchanger such that the cooled component stream functions as the refrigerant for the heat exchanger. The cycle is then repeated for the remaining mixed gas stream so as to draw off the next component gas and further cool the remaining mixed gas stream. The process continues until all of the component gases are separated from the desired gas stream. The final gas stream is then passed through a final heat exchanger and expander. The expander decreases the pressure on the gas stream, thereby cooling the stream and causing a portion of the gas stream to liquify within a tank. The portion of the gas which is hot liquefied is passed back through each of the heat exchanges where it functions as a refrigerant.

Apparatus and process for the refrigeration, liquefaction and separation of gases with varying levels of purity

DOEpatents

Bingham, Dennis N.; Wilding, Bruce M.; McKellar, Michael G.

2000-01-01

A process for the separation and liquefaction of component gasses from a pressurized mix gas stream is disclosed. The process involves cooling the pressurized mixed gas stream in a heat exchanger so as to condense one or more of the gas components having the highest condensation point; separating the condensed components from the remaining mixed gas stream in a gas-liquid separator; cooling the separated condensed component stream by passing it through an expander; and passing the cooled component stream back through the heat exchanger such that the cooled component stream functions as the refrigerant for the heat exchanger. The cycle is then repeated for the remaining mixed gas stream so as to draw off the next component gas and further cool the remaining mixed gas stream. The process continues until all of the component gases are separated from the desired gas stream. The final gas stream is then passed through a final heat exchanger and expander. The expander decreases the pressure on the gas stream, thereby cooling the stream and causing a portion of the gas stream to liquify within a tank. The portion of the gas which is not liquefied is passed back through each of the heat exchanges where it functions as a refrigerant.

Deformable image registration with a featurelet algorithm: implementation as a 3D-slicer extension and validation

NASA Astrophysics Data System (ADS)

Renner, A.; Furtado, H.; Seppenwoolde, Y.; Birkfellner, W.; Georg, D.

2016-03-01

A radiotherapy (RT) treatment can last for several weeks. In that time organ motion and shape changes introduce uncertainty in dose application. Monitoring and quantifying the change can yield a more precise irradiation margin definition and thereby reduce dose delivery to healthy tissue and adjust tumor targeting. Deformable image registration (DIR) has the potential to fulfill this task by calculating a deformation field (DF) between a planning CT and a repeated CT of the altered anatomy. Application of the DF on the original contours yields new contours that can be used for an adapted treatment plan. DIR is a challenging method and therefore needs careful user interaction. Without a proper graphical user interface (GUI) a misregistration cannot be easily detected by visual inspection and the results cannot be fine-tuned by changing registration parameters. To provide a DIR algorithm with such a GUI available for everyone, we created the extension Featurelet-Registration for the open source software platform 3D Slicer. The registration logic is an upgrade of an in-house-developed DIR method, which is a featurelet-based piecewise rigid registration. The so called "featurelets" are equally sized rectangular subvolumes of the moving image which are rigidly registered to rectangular search regions on the fixed image. The output is a deformed image and a deformation field. Both can be visualized directly in 3D Slicer facilitating the interpretation and quantification of the results. For validation of the registration accuracy two deformable phantoms were used. The performance was benchmarked against a demons algorithm with comparable results.

3D reconstruction and analysis of wing deformation in free-flying dragonflies.

PubMed

Koehler, Christopher; Liang, Zongxian; Gaston, Zachary; Wan, Hui; Dong, Haibo

2012-09-01

Insect wings demonstrate elaborate three-dimensional deformations and kinematics. These deformations are key to understanding many aspects of insect flight including aerodynamics, structural dynamics and control. In this paper, we propose a template-based subdivision surface reconstruction method that is capable of reconstructing the wing deformations and kinematics of free-flying insects based on the output of a high-speed camera system. The reconstruction method makes no rigid wing assumptions and allows for an arbitrary arrangement of marker points on the interior and edges of each wing. The resulting wing surfaces are projected back into image space and compared with expert segmentations to validate reconstruction accuracy. A least squares plane is then proposed as a universal reference to aid in making repeatable measurements of the reconstructed wing deformations. Using an Eastern pondhawk (Erythimus simplicicollis) dragonfly for demonstration, we quantify and visualize the wing twist and camber in both the chord-wise and span-wise directions, and discuss the implications of the results. In particular, a detailed analysis of the subtle deformation in the dragonfly's right hindwing suggests that the muscles near the wing root could be used to induce chord-wise camber in the portion of the wing nearest the specimen's body. We conclude by proposing a novel technique for modeling wing corrugation in the reconstructed flapping wings. In this method, displacement mapping is used to combine wing surface details measured from static wings with the reconstructed flapping wings, while not requiring any additional information be tracked in the high speed camera output.

Post-Paleogene Deformation in central Anatolia, South of Ankara (Turkey)

NASA Astrophysics Data System (ADS)

Rojay, Bora

2014-05-01

The closure of the northern Neo-Tethys took place between Eurasia in the north and northern edge of Afro- Arabian plate in the south since the Early Cretaceous is documented in central Anatolia. It is mated by Cretaceous ophiolitic mélanges thrusted over southwards on to the upper Cretaceous-Paleogene fore-arc and foreland sequences along the northern margins of Haymana and Tuzgölü basins, respectively. Two main deformation episodes are recognized in the region. These include post-Cretaceous-pre Miocene compressional regime and Miocene to mid-Pliocene transcurrent regime dominated extensional deformation. The first regime is characterize by NW-SE directed compressional and contractional deformation dominated by south vergent, large wave length, asymmetric to overturned folds and associated thrust/reverse faults. Some of these reverse faults were reactivated as strike-slip faults with reverse components as evidenced by cross-cutting relationships and overprinting slickensides observed extensively in the field. Along these reactivated faults, echelon calcite veins, fault parallel meter thick silica walls with repeated phases of deformation are very common. Following the Miocene, the region is affected by a NNE-SSW to NE-SW directed extension, possibly resulted from the interaction of Tuzgölü Fault with the northwards convex splays of dextral North Anatolian Fault extending into the region. As a conclusion, the Paleogene sequences with ophiolitic mélanges are deformed under NNE-SSW directed compression related to the development of dextral strike slip tectonics during post-Paleogene-pre-Miocene period. Keywords:fault plane slip data, transcurrent regime, post-Paleogene, central Anatolia.

Repeated sharp flux dropouts observed at 6.6 earth radii during a geomagnetic storm

NASA Technical Reports Server (NTRS)

Su, S.-Y.; Fritz, T. A.; Konradi, A.

1976-01-01

A number of repeated rapid flux dropouts have been observed at 6.6 earth radii by the low-energy proton detectors on board the ATS 6 satellite during the July 4-6, 1974, geomagnetic storm period. These rapid flux changes are caused by the fact that the outer boundary of the trapped radiation region moves back and forth past the satellite. Although a tilting field line configuration can cause the boundary to pass the satellite, as has frequently been reported in the literature, the boundary is shown to be distorted by a large surface wave traveling eastward around the earth. The maximum velocity of the wave was observed to be about 40 km/s.

Orthopaedic Disorders in Myotonic Dystrophy Type 1: descriptive clinical study of 21 patients

PubMed Central

2013-01-01

Background Myotonic Dystrophy Type 1 (DM1) is the most common form of hereditary myopathy presenting in adults. This autosomal-dominant systemic disorder is caused by a CTG repeat, demonstrating various symptoms. A mild, classic and congenital form can be distinguished. Often the quality of life is reduced by orthopaedic problems, such as muscle weakness, contractures, foot or spinal deformities, which limit patients’ mobility. The aim of our study was to gather information about the orthopaedic impairments in patients with DM1 in order to improve the medical care of patients, affected by this rare disease. Methods A retrospective clinical study was carried out including 21 patients (11 male and 10 female), all diagnosed with DM1 by genetic testing. All patients were seen during our special consultations for neuromuscular diseases, during which patients were interviewed and examined. We also reviewed surgery reports of our hospitalized patients. Results We observed several orthopaedic impairments: spinal deformities (scoliosis, hyperkyphosis, rigid spine), contractures (of the upper extremities and the lower extremities), foot deformities (equinus deformity, club foot, pes cavus, pes planovalgus, pes cavovarus, claw toes) and fractures. Five patients were affected by pulmonary diseases (obstructive airway diseases, restrictive lung dysfunctions). Twelve patients were affected by cardiac disorders (congenital heart defects, valvular heart defects, conduction disturbances, pulmonary hypertension, cardiomyopathy). Our patients received conservative therapy (physiotherapy, logopaedic therapy, ergotherapy) and we prescribed orthopaedic technical devices (orthopaedic custom-made shoes, insoles, lower and upper leg orthoses, wheelchair, Rehab Buggy). We performed surgery for spinal and foot deformities: the scoliosis of one patient was stabilized and seven patients underwent surgery for correction of foot deformities. Conclusions An orthopaedic involvement in DM1 patients should not be underestimated. The most common orthopaedic impairments are contractures, foot deformities and spinal deformities. Contractures are typically located distally in the lower extremities, but can also occur in the hip or shoulder joints. Foot deformities could be treated with orthopaedic custom-made shoes, orthoses or insoles. Surgery is indicated for severe foot deformities or contractures. PMID:24289806

Plastic mechanism of multi-pass double-roller clamping spinning for arc-shaped surface flange

NASA Astrophysics Data System (ADS)

Fan, Shuqin; Zhao, Shengdun; Zhang, Qi; Li, Yongyi

2013-11-01

Compared with the conventional single-roller spinning process, the double-roller clamping spinning(DRCS) process can effectively prevent the sheet metal surface wrinkling and improve the the production efficiency and the shape precision of final spun part. Based on ABAQUS/Explicit nonlinear finite element software, the finite element model of the multi-pass DRCS for the sheet metal is established, and the material model, the contact definition, the mesh generation, the loading trajectory and other key technical problems are solved. The simulations on the multi-pass DRCS of the ordinary Q235A steel cylindrical part with the arc-shaped surface flange are carried out. The effects of number of spinning passes on the production efficiency, the spinning moment, the shape error of the workpiece, and the wall thickness distribution of the final part are obtained. It is indicated definitely that with the increase of the number of spinning passes the geometrical precision of the spun part increases while the production efficiency reduces. Moreover, the variations of the spinning forces and the distributions of the stresses, strains, wall thickness during the multi-pass DRCS process are revealed. It is indicated that during the DRCS process the radical force is the largest, and the whole deformation area shows the tangential tensile strain and the radial compressive strain, while the thickness strain changes along the generatrix directions from the compressive strain on the outer edge of the flange to the tensile strain on the inner edge of the flange. Based on the G-CNC6135 NC lathe, the three-axis linkage computer-controlled experimental device for DRCS which is driven by the AC servo motor is developed. And then using the experimental device, the Q235A cylindrical parts with the arc-shape surface flange are formed by the DRCS. The simulation results of spun parts have good consistency with the experimental results, which verifies the feasibility of DRCS process and the reliability of the finite element model for DRCS.

Characteristics Buton Natural Asphalt-Rubber (BNA-R) on the Performance Improvement of Warm Mix Asphalt Using Natural Zeolite

NASA Astrophysics Data System (ADS)

Wahjuningsih, Nurul; Pranowo Hadiwardoyo, Sigit; Jachrizal Sumabrata, R.

2018-03-01

The decrease in the ability of service of pavement can be caused by the durability factor in the pavement layer in receiving heavy traffic load and the temperature of the pavement. Permanent deformation is one of the criteria of failure of asphalt mixture. Performance assessment of the asphalt mixture can be observed from the rheological properties of asphalt binder. The use of BNA-R in this study is intended to modify the characteristics of bitumen penetration grade 60 / 70 used in warm mix asphalt. Warm mix asphalt with lower temperatures of mixing and compaction than conventional asphalt mixtures was chosen because it is more environmentally friendly. To reduce the temperature in this warm asphalt technology is achieved by using natural zeolite. Both of these materials are local materials that are widely available in Indonesia. The rheology of asphalt 60/70 modified with BNA-R indicates that the addition of BNA-R in the base asphalt increase the complex modulus value and decrease the phase angle value. These values were related to the performance of mixture in the permanent deformation criteria. Reducing the temperature of mixing and compaction should be balanced with modifying the asphalt binder used. Rutting due to permanent deformation can resulted in inconvenience to the passengers and can lead to high costs of road maintenance. To determine the permanent deformation of asphalt mix with material combinations was performed through the wheel tracking test machine with 3,780 cycles for 3 hours. The results shows that after test track over 7 thousand passes have seen permanent deformation characteristics of asphalt concrete mixture with a variation of the characteristics of bitumen.

Single-camera stereo-digital image correlation with a four-mirror adapter: optimized design and validation

NASA Astrophysics Data System (ADS)

Yu, Liping; Pan, Bing

2016-12-01

A low-cost, easy-to-implement but practical single-camera stereo-digital image correlation (DIC) system using a four-mirror adapter is established for accurate shape and three-dimensional (3D) deformation measurements. The mirrors assisted pseudo-stereo imaging system can convert a single camera into two virtual cameras, which view a specimen from different angles and record the surface images of the test object onto two halves of the camera sensor. To enable deformation measurement in non-laboratory conditions or extreme high temperature environments, an active imaging optical design, combining an actively illuminated monochromatic source with a coupled band-pass optical filter, is compactly integrated to the pseudo-stereo DIC system. The optical design, basic principles and implementation procedures of the established system for 3D profile and deformation measurements are described in detail. The effectiveness and accuracy of the established system are verified by measuring the profile of a regular cylinder surface and displacements of a translated planar plate. As an application example, the established system is used to determine the tensile strains and Poisson's ratio of a composite solid propellant specimen during stress relaxation test. Since the established single-camera stereo-DIC system only needs a single camera and presents strong robustness against variations in ambient light or the thermal radiation of a hot object, it demonstrates great potential in determining transient deformation in non-laboratory or high-temperature environments with the aid of a single high-speed camera.

Characterizing deformability and surface friction of cancer cells

PubMed Central

Byun, Sangwon; Son, Sungmin; Amodei, Dario; Cermak, Nathan; Shaw, Josephine; Kang, Joon Ho; Hecht, Vivian C.; Winslow, Monte M.; Jacks, Tyler; Mallick, Parag; Manalis, Scott R.

2013-01-01

Metastasis requires the penetration of cancer cells through tight spaces, which is mediated by the physical properties of the cells as well as their interactions with the confined environment. Various microfluidic approaches have been devised to mimic traversal in vitro by measuring the time required for cells to pass through a constriction. Although a cell’s passage time is expected to depend on its deformability, measurements from existing approaches are confounded by a cell's size and its frictional properties with the channel wall. Here, we introduce a device that enables the precise measurement of (i) the size of a single cell, given by its buoyant mass, (ii) the velocity of the cell entering a constricted microchannel (entry velocity), and (iii) the velocity of the cell as it transits through the constriction (transit velocity). Changing the deformability of the cell by perturbing its cytoskeleton primarily alters the entry velocity, whereas changing the surface friction by immobilizing positive charges on the constriction's walls primarily alters the transit velocity, indicating that these parameters can give insight into the factors affecting the passage of each cell. When accounting for cell buoyant mass, we find that cells possessing higher metastatic potential exhibit faster entry velocities than cells with lower metastatic potential. We additionally find that some cell types with higher metastatic potential exhibit greater than expected changes in transit velocities, suggesting that not only the increased deformability but reduced friction may be a factor in enabling invasive cancer cells to efficiently squeeze through tight spaces. PMID:23610435

Evolution of Oxide Inclusions in Si-Mn Killed Steels During Hot-Rolling Process

NASA Astrophysics Data System (ADS)

Yang, Wen; Guo, Changbo; Zhang, Lifeng; Ling, Haitao; Li, Chao

2017-10-01

The evolution of oxide inclusions in Si-Mn killed steels refined by slags of different basicity during a four-pass industrial hot-rolling process was investigated using an automated microscopy system. High-basicity refining slag induced the formation of CaO- and Al2O3-containing inclusions, while refining slag with 0.8 basicity induced dominant inclusions of SiO2 and MnO-SiO2. CaO-SiO2-Al2O3 inclusions mainly formed endogenously during solidification and cooling of Ca-containing steels, where Ca originated from slag-steel reactions. However, the larger-sized higher-CaO inclusions originated from slag entrainment. Different inclusions presented different hot-rolling behaviors. The inclusion composition changed by deformation and new phase formation. The dominant oxide types were unchanged under refinement by low-basicity slag; however, they changed under refinement with high-basicity slag. The deformation index of inclusions decreased with increasing accumulated reduction (AR) of the steel. The difference in deformation index between different inclusion types was the largest in the first rolling stage and decreased in subsequent stages. SiO2-CaO and SiO2-MnO-CaO inclusions had larger deformation indices during hot rolling but smaller indices in the last two stages. High-basicity slag increased inclusion complexity; from the perspective of cold-drawing performance, low-basicity refining slag is better for the industrial production of tire-cord steels.

Fixation of the stressed state of glass plates by coating them with thin films using a plasma focus installation

NASA Astrophysics Data System (ADS)

Kolokoltsev, V. N.; Degtiarev, V. F.; Borovitskaya, I. V.; Nikulin, V. Ya.; Peregudova, E. N.; Silin, P. V.; Eriskin, A. A.

2018-01-01

Elastic deformation in transparent mediums is usually studied by the photoelasticity method. For opaque mediums the method of film coating and strain gauge method are used. After the external load was removed, the interference pattern corresponding to elastic deformation of the material disappears. It is found that the elastic deformation state of the thin glass plate under the action of concentrated load can be fixed during the deposition of a thin metal film. Deposition of thin copper films was carried out by passing of plasma through the copper tube installed inside the Plasma Focus installation. After removing of the load, interference pattern on the glass plates was observed in the form of Newton’s rings and isogers in non-monochromatic light on the CCD scanners which uses uorescent lamps with cold cathode. It is supposed that the copper film fixes the relief of the surface of the glass plate at the time of deformation and saves it when the load is removed. In the case of a concentrated load, this relief has the shape of a thin lens of large radius. For this reason, the interference of coherent light rays in a thin air gap between the glass of the scanners atbed and the lens surface has the shape of Newton's rings. In this case, when scanning the back side of the plate, isogyres are observed. The presented method can be used in the analysis of the mechanical stress in a various optical elements.

Using Airborne Laser Altimetry to Detect Topographic Change at Long Valley Caldera, California

NASA Technical Reports Server (NTRS)

Hofton, M. A.; Minster, J.-B.; Ridgway, J. R.; Williams, N. P.; Blair, J.-B.; Rabine, D. L.; Bufton, J. L.

1999-01-01

The topography of the Long Valley caldera, California, was sampled using airborne laser altimetry in 1993, 1995, and 1997 to test the feasibility of using airborne laser altimetry for monitoring deformation of volcanic origin. Results show the laser altimeters are able to resolve subtle topographic features such as a gradual slope and to detect small transient changes in lake elevation. Crossover and repeat pass analyses of laser tracks indicate decimeter-level vertical precision is obtained over flat and low-sloped terrain for altimeter systems performing waveform digitization. Comparisons with complementary, ground-based GPS data at a site close to Bishop airport indicate that the laser and GPS-derived elevations agree to within the error inherent in the measurement and that horizontal locations agree to within the radius of the laser footprint. A comparison of the data at two sites, one where no change and the other where the maximum amount of vertical uplift is expected, indicates approximately 10 cm of relative uplift occurred 1993-1997, in line with predictions from continuous GPS measurements in the region. Extensive terrain mapping flights during the 1995 and 1997 missions demonstrate some of the unique abilities of laser altimetry; the straightforward creation of high resolution, high accuracy digital elevation models of overflown terrain, and the ability to determine ground topography in the presence of significant ground cover such as dense tree canopies. These capabilities make laser altimetry an attractive technique for quantifying topographic change of volcanic origin, especially in forested regions of the world where other remote sensing instruments have difficulty detecting the underlying topography.

Using Airborne Laser Altimetry to Detect Topographic Change at Long Valley Caldera California

NASA Technical Reports Server (NTRS)

Hofton, M. A.; Minster, J.-B.; Ridgway, J. R.; Williams, N. P.; Blair, J. B.; Rabine, D. L.; Bufton, J. L.

2000-01-01

The topography of the Long Valley caldera, California, was sampled using airborne laser altimetry in 1993, 1995, and 1997 to test the feasibility of using airborne laser altimetry for monitoring deformation of volcanic origin. Results show the laser altimeters are able to resolve subtle topographic features such as a gradual slope and to detect small transient changes in lake elevation. Crossover and repeat pass analyses of laser tracks indicate decimeter-level vertical precision is obtained over flat and low-sloped terrain for altimeter systems performing waveform digitization. Comparisons with complementary, ground-based CPS data at a site close to Bishop airport indicate that the laser and GPS-derived elevations agree to within the error inherent in the measurement and that horizontal locations agree to within the radius of the laser footprint. A comparison of the data at two sites, one where no change and the other where the maximum amount of vertical uplift is expected, indicates approximately 10 cm of relative uplift occurred 1993-1997, in line with predictions from continuous CPS measurements in the region. Extensive terrain mapping flights during the 1995 and 1997 missions demonstrate some of the unique abilities of laser altimetry; the straightforward creation of high resolution, high accuracy digital elevation models of overflown terrain, and the ability to determine ground topography in the presence of significant ground cover such as dense tree canopies. These capabilities make laser altimetry an attractive technique for quantifying topographic change of volcanic origin, especially in forested regions of the world where other remote sensing instruments have difficulty detecting the underlying topography.

Lithospheric controls on crustal reactivation and intraplate mountain building in the Gobi Corridor, Central Asia

NASA Astrophysics Data System (ADS)

Cunningham, D.

2017-12-01

This talk will review the Permian-Recent tectonic history of the Gobi Corridor region which includes the actively deforming Gobi Altai-Altai, Eastern Tien Shan, Beishan and North Tibetan foreland. Since terrane amalgamation in the Permian, Gobi Corridor crust has been repeatedly reactivated by Triassic-Jurassic contraction/transpression, Late Cretaceous extension and Late Cenozoic transpression. The tectonic history of the region suggests the following basic principle for intraplate continental regions: non-cratonized continental interior terrane collages are susceptible to repeated intraplate reactivation events, driven by either post-orogenic collapse and/or compressional stresses derived from distant plate boundary convergence. Thus, important related questions are: 1) what lithospheric pre-conditions favor intraplate crustal reactivation in the Gobi Corridor (simple answer: crustal thinning, thermal weakening, strong buttressing cratons), 2) what are the controls on the kinematics of deformation and style of mountain building in the Gobi-Altai-Altai, Beishan and North Tibetan margin (simple answer: many factors, but especially angular relationship between SHmax and `crustal grain'), 3) how does knowledge of the array of Quaternary faults and the historical earthquake record influence our understanding of modern earthquake hazards in continental intraplate regions (answer: extrapolation of derived fault slip rates and recurrence interval determinations are problematic), 4) what important lessons can we learn from the Mesozoic-Cenozoic tectonic history of Central Asia that is applicable to the tectonic evolution of all intraplate continental regions (simple answer: ancient intraplate deformation events may be subtly expressed in the rock record and only revealed by low-temperature thermochronometers, preserved orogen-derived sedimentary sequences, fault zone evidence for younger brittle reactivation, and recognition of a younger class of cross-cutting tectonic structures).

Near-Field Deformation Associated with the M6.0 South Napa Earthquake Surface Rupture

NASA Astrophysics Data System (ADS)

Brooks, B. A.; Hudnut, K. W.; Glennie, C. L.; Ericksen, T.

2014-12-01

We characterize near-field deformation associated with the surface rupture of the M6.0 South Napa earthquake from repeat mobile laser scanning (MLS) surveys. Starting the day after the main shock, we operated, sometime simultaneously, short (~75 m range) and medium (~400m range) range laser scanners on a truck or backpack. We scanned most of the length of the principal and secondary surface ruptures at speeds less than 10 km/hr. Scanning occurred primarily in either suburban subdivisions or cultivated vineyards of varying varietals with differing leaf patterns and stages of maturity. Spot-spacing is dense enough (100s of points/m^2) to permit creation of 10-25cm digital elevation models of much of the surface rupture. Scanned features of the right-lateral rupture include classic mole tracks through a variety of soil types, en echelon cracks, offset vine rows, and myriad types of pavement-related deformation. We estimate coseismic surface displacements ranging from 5 to 45 cm by examining offset cultural features and vine rows and by comparing the MLS data with preexisting airborne laser scans from 2003 using point-cloud and solid-modeling methodologies. Additionally, we conducted repeat MLS scans to measure the magnitude and spatial variation of fault afterslip, exceeding 20 cm in some places, particularly in the southern portion of the rupture zone. We anticipate these data sets, in conjunction with independently collected ground-based alinement arrays and space-based geodetic data will contribute significant insight into topics of current debate including assessing the most appropriate material models for shallow fault zones and how shallow and deeper fault slip relate to one another.

Frequency-Switchable Microfluidic CSRR-Loaded QMSIW Band-Pass Filter Using a Liquid Metal Alloy

PubMed Central

Eom, Seunghyun; Memon, Muhammad Usman; Lim, Sungjoon

2017-01-01

In this paper, we have proposed a frequency-switchable complementary split-ring resonator (CSRR)-loaded quarter-mode substrate-integrated-waveguide (QMSIW) band-pass filter. For frequency switching, a microfluidic channel and liquid metal are used. The liquid metal used is eutectic gallium-indium (EGaIn), consisting of 24.5% indium and 75.5% gallium. The microfluidic channels are built using the elastomer polydimethylsiloxane (PDMS) and three-dimensional-printed microfluidic channel frames. The CSRR-loaded QMSIW band-pass filter is designed to have two states. Before the injection of the liquid metal, the measured center frequency and fractional bandwidths are 2.205 GHz and 6.80%, respectively. After injection, the center frequency shifts from 2.205 GHz to 2.56 GHz. Although the coupling coefficient is practically unchanged, the fractional bandwidth changes from 6.8% to 9.38%, as the CSRR shape changes and the external quality factor decreases. After the removal of the liquid metal, the measured values are similar to the values recorded before the liquid metal was injected. The repeatability of the frequency-switchable mechanism is, therefore, verified. PMID:28350355

Two-Stage Processing of Aesthetic Information in the Human Brain Revealed by Neural Adaptation Paradigm.

PubMed

Iwasaki, Miho; Noguchi, Yasuki; Kakigi, Ryusuke

2018-06-07

Some researchers in aesthetics assume visual features related to aesthetic perception (e.g. golden ratio and symmetry) commonly embedded in masterpieces. If this is true, an intriguing hypothesis is that the human brain has neural circuitry specialized for the processing of visual beauty. We presently tested this hypothesis by combining a neuroimaging technique with the repetition suppression (RS) paradigm. Subjects (non-experts in art) viewed two images of sculptures sequentially presented. Some sculptures obeyed the golden ratio (canonical images), while the golden proportion were impaired in other sculptures (deformed images). We found that the occipito-temporal cortex in the right hemisphere showed the RS when a canonical sculpture (e.g. Venus de Milo) was repeatedly presented, but not when its deformed version was repeated. Furthermore, the right parietal cortex showed the RS to the canonical proportion even when two sculptures had different identities (e.g. Venus de Milo as the first stimulus and David di Michelangelo as the second), indicating that this region encodes the golden ratio as an abstract rule shared by different sculptures. Those results suggest two separate stages of neural processing for aesthetic information (one in the occipito-temporal and another in the parietal regions) that are hierarchically arranged in the human brain.

A 9-year follow-up of a self-management group intervention for persistent neck pain in primary health care: a randomized controlled trial

PubMed Central

Gustavsson, Catharina; von Koch, Lena

2017-01-01

Background and objective In previous short-term and 2-year follow-ups, a pain and stress self-management group intervention (PASS) had better effect on pain-related disability, self-efficacy, catastrophizing, and perceived pain control than individually administered physiotherapy (IAPT) for patients with persistent tension-type neck pain. Studies that have evaluated long-term effects of self-management approaches toward persistent neck pain are sparse. The objective of this study was to compare pain-related disability, self-efficacy for activities of daily living (ADL), catastrophizing, pain, pain control, use of analgesics, and health care utilization in people with persistent tension-type neck pain 9 years after they received the PASS or IAPT. Materials and methods Of 156 people (PASS, n = 77; IAPT, n = 79) originally included in a randomized controlled trial, 129 people (PASS, n = 63; IAPT, n = 66) were eligible and were approached for the 9-year follow-up. They were sent a self-assessment questionnaire, comprising the Neck Disability Index, the Self-Efficacy Scale, the Coping Strategies Questionnaire, and questions regarding pain, analgesics, and health care utilization. Mixed linear models for repeated measures analysis or generalized estimating equations were used to evaluate the differences between groups and within groups over time (baseline, previous follow-ups, and 9-year follow-up) and the interaction effect of “time by group”. Results Ninety-four participants (73%) responded (PASS, n = 48; IAPT, n = 46). At 9 years, PASS participants reported less pain-related disability, pain at worst, and analgesics usage, and a trend toward better self-efficacy compared to IAPT participants. There was a difference between groups in terms of change over time for disability, self-efficacy for ADL, catastrophizing, perceived pain control, and health care visits in favor of PASS. Analyses of simple main effects at 9 years showed that the PASS group had less disability (p = 0.006) and a trend toward better self-efficacy (p = 0.059) than the IAPT group. Conclusion The favorable effects on pain-related disability of PASS were sustained 9 years after the intervention. PMID:28115865

Modeling the Volcanic Source at Long Valley, CA, Using a Genetic Algorithm Technique

NASA Technical Reports Server (NTRS)

Tiampo, Kristy F.

1999-01-01

In this project, we attempted to model the deformation pattern due to the magmatic source at Long Valley caldera using a real-value coded genetic algorithm (GA) inversion similar to that found in Michalewicz, 1992. The project has been both successful and rewarding. The genetic algorithm, coded in the C programming language, performs stable inversions over repeated trials, with varying initial and boundary conditions. The original model used a GA in which the geophysical information was coded into the fitness function through the computation of surface displacements for a Mogi point source in an elastic half-space. The program was designed to invert for a spherical magmatic source - its depth, horizontal location and volume - using the known surface deformations. It also included the capability of inverting for multiple sources.

SU-E-J-92: Validating Dose Uncertainty Estimates Produced by AUTODIRECT, An Automated Program to Evaluate Deformable Image Registration Accuracy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, H; Chen, J; Pouliot, J

2015-06-15

Purpose: Deformable image registration (DIR) is a powerful tool with the potential to deformably map dose from one computed-tomography (CT) image to another. Errors in the DIR, however, will produce errors in the transferred dose distribution. We have proposed a software tool, called AUTODIRECT (automated DIR evaluation of confidence tool), which predicts voxel-specific dose mapping errors on a patient-by-patient basis. This work validates the effectiveness of AUTODIRECT to predict dose mapping errors with virtual and physical phantom datasets. Methods: AUTODIRECT requires 4 inputs: moving and fixed CT images and two noise scans of a water phantom (for noise characterization). Then,more » AUTODIRECT uses algorithms to generate test deformations and applies them to the moving and fixed images (along with processing) to digitally create sets of test images, with known ground-truth deformations that are similar to the actual one. The clinical DIR algorithm is then applied to these test image sets (currently 4) . From these tests, AUTODIRECT generates spatial and dose uncertainty estimates for each image voxel based on a Student’s t distribution. This work compares these uncertainty estimates to the actual errors made by the Velocity Deformable Multi Pass algorithm on 11 virtual and 1 physical phantom datasets. Results: For 11 of the 12 tests, the predicted dose error distributions from AUTODIRECT are well matched to the actual error distributions within 1–6% for 10 virtual phantoms, and 9% for the physical phantom. For one of the cases though, the predictions underestimated the errors in the tail of the distribution. Conclusion: Overall, the AUTODIRECT algorithm performed well on the 12 phantom cases for Velocity and was shown to generate accurate estimates of dose warping uncertainty. AUTODIRECT is able to automatically generate patient-, organ- , and voxel-specific DIR uncertainty estimates. This ability would be useful for patient-specific DIR quality assurance.« less

Stress analysis of ZrO2/SiO2 multilayers deposited on different substrates with different thickness periods

NASA Astrophysics Data System (ADS)

Shao, Shuying; Shao, Jianda; He, Hongbo; Fan, Zhengxiu

2005-08-01

The effects of repeating thickness periods on stress are studied in ZrO2/SiO2 multilayers deposited by electron-beam evaporation on BK7 glass and fused-silica substrates. The results show that the residual stress is compressive and decreases with an increase of the periods of repeating thickness in the ZrO2/SiO2 multilayers. At the same time, the residual stress in multilayers deposited on BK7 glass is less than that of samples deposited on fused silica. The variation of the microstructure examined by x-ray diffraction shows that microscopic deformation does not correspond to macroscopic stress, which may be due to variation of the interface stress.

Application of Differential InSAR to Mining

NASA Astrophysics Data System (ADS)

Eneva, M.; Baker, E.; Xu, H.

2001-12-01

In a NASA funded project we are applying differential InSAR to measure surface deformation associated with mining at depth. Surface displacement can be caused by rockbursts associated with mine collapse or mining-induced stress released on nearby tectonic features. The latter type of rockbursts are similar to tectonic earthquakes, but generally occur at shallower depths than non-induced events of similar size. Thus significant co-seismic surface changes may accompany them. In addition, subsidence of a more gradual type may result from ongoing soft-rock (e.g., coal, potash, salt) mining. While such subsidence can accidentally occur above abandoned mines, it is most often planned as part of the ongoing ore extraction, especially in so-called long-wall mining. Predicting the amount and spatial extent of this subsidence is an aspect of mining engineering. It is important to compare these predictions with measurements of the actual deformation. Although mines use leveling and GPS measurements to monitor subsidence, these are generally performed with much smaller frequency (e.g., annually) and lower spatial resolution than repeat-pass differential InSAR can provide. We are using ERS-1/2 raw SAR data provided by ESA and Eurimage, and the Gamma software for their processing. At present we are focused on the processing and modeling of data from two representative sites. By the end of the project we will have analyzed several more sites of subsidence and M>4.5 rockbursts. As an example of mining subsidence, we are currently analyzing data from the site of a coal mine in Colorado (USA), operating in a relatively flat and arid area. Numerous adjacent long-wall panels of extraction are used, some exceeding 5 km in length. A 600 to 750-m length of panel may be extracted per month, with a maximum subsidence of 1.5 to 1.8 m expected over each panel. The surface deformation can be monitored especially well during the summers of 1995 and 1996, when nine good-quality ERS-1/2 SAR scenes were gathered. Two of these scenes form a tandem pair to be used for topography. We are also making use of a 30-m DEM from USGS, maps of extraction panels, leveling data and microearthquake locations. As an example of rockbursts, we are presently analyzing ERS-2 SAR data from the site of a M5.1 rockburst that occurred on April 22, 1999, in the gold fields of Welkom, South Africa. The event was induced on a fault transecting the mine and had a normal mechanism. Only two good-quality SAR scenes are available from this site, spanning about a year including the event. Thus the topography effect cannot be removed using interferometry. However, since flat surface and urban environment characterize this site, a clear fringe pattern is observed, apparently associated with the rockburst. This pattern suggests up to 9-cm subsidence. Its center is within 5 km from the seismically determined event location. Thus this rockburst represents an example of the capabilities of InSAR to provide ground truth locations for moderate shallow earthquakes. To model the seismic source, we are using the RNGCHN software (Feigl and Dupré, 1999) based on analytic solutions for a homogeneous half-space. In order to model deformation in realistically complex crust, including layered structure and lateral heterogeneities, we are also developing a 3D finite-difference method of estimating deformation in a volume due to displacement on a fault surface. This method will be also used for the modeling of mining subsidence.

Pretraining on Southwestern stations decreases training time and cost for proficiency-based fundamentals of laparoscopic surgery training.

PubMed

Rosenthal, Madelyn E; Castellvi, Antonio O; Goova, Mouza T; Hollett, Lisa A; Dale, Jarrod; Scott, Daniel J

2009-11-01

We previously reported a proficiency-based Fundamentals of Laparoscopic Surgery (FLS) curriculum that uniformly resulted in passing the technical skills certification criteria. We hypothesized that pretraining using the Southwestern (SW) videotrainer stations would decrease costs and training time and maintain benefits. Group I (2nd-year medical student, n = 10) underwent FLS pretesting (Pretest 1), SW station proficiency-based training, repeat FLS testing (Pretest 2), FLS proficiency-based training, and final FLS testing (Posttest). These data were compared with a historic control, group II (2nd-year medical student, n = 10), which underwent FLS pretesting (Pretest 1), proficiency-based training, and final FLS testing (Posttest). During training, group I achieved proficiency (85.4 + or - 26.2 repetitions) for all SW tasks. For both groups, proficiency was achieved for 96% of the FLS tasks, with substantial differences detected for group I and group II repetitions (100.5 + or - 15.9 versus 114 + or - 25.5) and training time (6.0 + or - 1.5 versus 9.2 + or - 2.2 hours), respectively. Per-person material costs were considerably different for groups I and II ($827 + or - 116 versus $1,108 + or - 393). Group I demonstrated significant improvement from Pretest 1 (149 + or - 39; 0% FLS pass rate) to Pretest 2 (293 + or - 83; p < 0.001; 60% FLS pass rate), and to Posttest (444 + or - 60; p < 0.001; 100% FLS pass rate). Group II demonstrated significant improvement from Pretest 1 (158 + or - 78; 0% FLS pass rate) to Posttest (469.7 + or - 12.0; p < 0.001; 100% FLS pass rate). Pretraining on SW stations decreases training time for FLS skill acquisition and maintains educational benefits. This strategy decreases costs associated with using consumable materials for training.

Size effects on plasticity and fatigue microstructure evolution in FCC single crystals

NASA Astrophysics Data System (ADS)

El-Awady, Jaafar Abbas

In aircraft structures and engines, fatigue damage is manifest in the progressive emergence of distributed surface cracks near locations of high stress concentrations. At the present time, reliable methods for prediction of fatigue crack initiation are not available, because the phenomenon starts at the atomic scale. Initiation of fatigue cracks is associated with the formation of Persistent slip bands (PSBs), which start at certain critical conditions inside metals with specific microstructure dimensions. The main objective of this research is to develop predictive computational capabilities for plasticity and fatigue damage evolution in finite volumes. In that attempt, a dislocation dynamics model that incorporates the influence of free and internal interfaces on dislocation motion is presented. The model is based on a self-consistent formulation of 3-D Parametric Dislocation Dynamics (PDD) with the Boundary Element method (BEM) to describe dislocation motion, and hence microscopic plastic flow in finite volumes. The developed computer models are bench-marked by detailed comparisons with the experimental data, developed at the Wright-Patterson Air Force Lab (WP-AFRL), by three dimensional large scale simulations of compression loading on micro-scale samples of FCC single crystals. These simulation results provide an understanding of plastic deformation of micron-size single crystals. The plastic flow characteristics as well as the stress-strain behavior of simulated micropillars are shown to be in general agreement with experimental observations. New size scaling aspects of plastic flow and work-hardening are identified through the use of these simulations. The flow strength versus the diameter of the micropillar follows a power law with an exponent equal to -0.69. A stronger correlation is observed between the flow strength and the average length of activated dislocation sources. This relationship is again a power law, with an exponent -0.85. Simulation results with and without the activation of cross-slip are compared. Discontinuous hardening is observed when cross-slip is included. Experimentally-observed size effects on plastic flow and work- hardening are consistent with a "weakest-link activation mechanism". In addition, the variations and periodicity of dislocation activation are analyzed using the Fast Fourier Transform (FFT). We then present models of localized plastic deformation inside Persistent Slip Band channels. We investigate the interaction between screw dislocations as they pass one another inside channel walls in copper. The model shows the mechanisms of dislocation bowing, dipole formation and binding, and dipole destruction as screw dislocations pass one another. The mechanism of (dipole passing) is assessed and interpreted in terms of the fatigue saturation stress. We also present results for the effects of the wall dipole structure on the dipole passing mechanism. The edge dislocation dipolar walls is seen to have an effect on the passing stress as well. It is shown that the passing stress in the middle of the channel is reduced by 11 to 23% depending on the initial configuration of the screw dislocations with respect to one another. Finally, from large scale simulations of the expansion process of the edge dipoles from the walls in the channel the screw dislocations in the PSB channels may not meet "symmetrically", i.e. precisely in the center of the channel but preferably a little on one or the other side. For this configuration the passing stress will be lowered which is in agreement to experimental observations.

Thermal activation parameters of plastic flow reveal deformation mechanisms in the CrMnFeCoNi high-entropy alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laplanche, Guillaume; Bonneville, J.; Varvenne, C.

To reveal the operating mechanisms of plastic deformation in an FCC high-entropy alloy, the activation volumes in CrMnFeCoNi have been measured as a function of plastic strain and temperature between 77 K and 423 K using repeated load relaxation experiments. At the yield stress, σ y, the activation volume varies from ~60 b3 at 77 K to ~360 b 3 at 293 K and scales inversely with yield stress. With increasing plastic strain, the activation volume decreases and the trends follow the Cottrell-Stokes law, according to which the inverse activation volume should increase linearly with σ - σ y (Haasenmore » plot). This is consistent with the notion that hardening due to an increase in the density of forest dislocations is naturally associated with a decrease in the activation volume because the spacing between dislocations decreases. The values and trends in activation volume agree with theoretical predictions that treat the HEA as a high-concentration solid-solution-strengthened alloy. Lastly, these results demonstrate that this HEA deforms by the mechanisms typical of solute strengthening in FCC alloys, and thus indicate that the high compositional/structural complexity does not introduce any new intrinsic deformation mechanisms.« less

Dual self-organised shear banding behaviours and enhanced ductility in phase separating Zr-based bulk metallic glasses

NASA Astrophysics Data System (ADS)

Zhang, Z. Q.; Song, K. K.; Sun, B. A.; Wang, L.; Cui, W. C.; Qin, Y. S.; Han, X. L.; Xue, Q. S.; Peng, C. X.; Sarac, B.; Spieckermann, F.; Kaban, I.; Eckert, J.

2018-07-01

The multiplication and interaction of self-organised shear bands often transform to a stick-slip behaviour of a major shear band along the primary shear plane, and ultimately the major shear band becomes runaway and terminates the plasticity of bulk metallic glasses (BMGs). Here, we examined the deformation behaviours of the nanoscale phase-separating Zr65-xCu25Al10Fex (x = 5 and 7.5 at.%) BMGs. The formation of multi-step phase separation, being mainly governed by nucleation and growth, results in the microstructural inhomogeneity on a wide range of length-scales and leads to obviously macroscopic and repeatable ductility. The good deformability can be attributed to two mechanisms for stabilizing shear banding process, i.e. the mutual interaction of multiple shear bands away from the major shear band and the delaying slip-to-failure of dense fine shear bands around the major shear band, both of which show a self-organised criticality yet with different power-law exponents. The two mechanisms could come into effect in the intermediate (stable) and later plastic deformation regime, respectively. Our findings provide a possibility to enhance the shear banding stability over the whole plastic deformation through a proper design of microstructure heterogeneities.

Thermal activation parameters of plastic flow reveal deformation mechanisms in the CrMnFeCoNi high-entropy alloy

DOE PAGES

Laplanche, Guillaume; Bonneville, J.; Varvenne, C.; ...

2017-10-06

To reveal the operating mechanisms of plastic deformation in an FCC high-entropy alloy, the activation volumes in CrMnFeCoNi have been measured as a function of plastic strain and temperature between 77 K and 423 K using repeated load relaxation experiments. At the yield stress, σ y, the activation volume varies from ~60 b3 at 77 K to ~360 b 3 at 293 K and scales inversely with yield stress. With increasing plastic strain, the activation volume decreases and the trends follow the Cottrell-Stokes law, according to which the inverse activation volume should increase linearly with σ - σ y (Haasenmore » plot). This is consistent with the notion that hardening due to an increase in the density of forest dislocations is naturally associated with a decrease in the activation volume because the spacing between dislocations decreases. The values and trends in activation volume agree with theoretical predictions that treat the HEA as a high-concentration solid-solution-strengthened alloy. Lastly, these results demonstrate that this HEA deforms by the mechanisms typical of solute strengthening in FCC alloys, and thus indicate that the high compositional/structural complexity does not introduce any new intrinsic deformation mechanisms.« less

Development of a Rolling Process Design Tool for Use in Improving Hot Roll Slab Recovery (Quarterly Report: Q3-FY03)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couch, R; Wang, P

2003-07-31

In this quarter, an FEM simulation has been performed to compare the shape of the deformed slab after the 8th reduction pass with the experimental metrology data provided by Alcoa Technical Center (ATC). Also, a bug in the thermal contact algorithm used in parallel processing have been identified and corrected for consistent thermal solutions between the rollers and the slab. The overall shape of the slab at the end of the 8th pass is shown in Figure 1. Comparison of the sectional views at the center plane along the length of the slab for both experiment and simulation, shows thatmore » the curvature at the slab mouth at the centerline is slightly higher than the experimental result as shown in Figure 2. We are currently focusing on tuning the parameter values used in the simulation and a more complete parametric study for validation is underway. Also, unexpected fracture occurred along the surface of the slab in the 9th pass as shown in Figure 3. We believe that the reason is due to previously noted inadequacies in the fracture model at low strain rates and high stress triaxiality. We are expecting to receive a modified fracture model based on additional experiment shortly from Alcoa.« less

Flow behaviour of magnesium alloy AZ31B processed by equal-channel angular pressing

NASA Astrophysics Data System (ADS)

Arun, M. S.; Chakkingal, U.

2014-08-01

Magnesium alloys are characterised by their low density, high specific strength and stiffness. But, the potential application of Mg is limited by its low room-temperature ductility & formability. Formability can be improved by developing an ultrafine grained (UFG) structure. Equal channel angular pressing (ECAP) is a well known process that can be used to develop an ultrafine grained microstructure. The aim of this study was to investigate the flow behaviour of AZ31B magnesium alloy after ECAP. The specimen was subjected to three passes of ECAP with a die angle of 120° using processing route Bc. The processing temperature was 523 K for the first pass and 423 K for the subsequent two passes. The microstructure characterisation was done. Compression tests of ECAPed and annealed specimens were carried out at strain rates of 0.01 - 1s-1 and deformation temperatures of 200 - 300°C using computer servo-controlled Gleeble-3800 system. The value of activation energy Q and the empirical materials constants of A and n were determined. The equations relating flow stress and Zener-Hollomon parameter were proposed. In the case annealed AZ31, the activation energy was determined to be 154 kJ/mol, which was slightly higher than the activation energy of 144 kJ/mol for ECAPed AZ31.

A spontaneously arising mutation in connexin32 with repeated passage of FRTL-5 cells coincides with increased growth rate and reduced thyroxine release

NASA Technical Reports Server (NTRS)

Green, L. M.; Murray, D. K.; Tran, D. T.; Nelson, G. A.; Shah, M. M.; Luben, R. A.

2001-01-01

In this study we examine changes in the cellular properties of FRTL-5 cells as a function of passage number, with particular emphasis on gap junction expression, karyotype, morphology, growth rate and thyroxine (T(4)) release. Early passage FRTL-5 follicular cells transfer dye through gap junctions from injected cell(s) to third-order neighboring cells and beyond within their respective follicles and have immuno-detectable connexin32 (Cx32) type gap junctional plaques in their lateral contacting plasma membranes. By contrast, FRTL-5 cells established as monolayers, or as follicles from cultures passed more than 15 times, did not transfer microinjected Lucifer Yellow dye to contiguous neighboring cells and did not express any immuno-detectable rat thyroid specific connexins (Cx43, Cx32 or Cx26). Western blots confirmed that total, membrane and cytosolic Cx32 protein was present only in early pass follicular cultures. To better understand the passage-dependent loss of Cx32 expression, RT-PCR primers were made to the most unique sequences of the rat Cx32 molecule, the cytoplasmic and carboxyl-terminal regions. These primers were used to screen FRTL-5 RNA from cultures of various passage numbers. The results revealed that later passage cultures had a single base deletion in the middle of the Cx32 cytoplasmic loop region at nucleotide position 378. This base deletion was in the middle position of the codon for amino acid 116, which is normally a CAC (histidine) but read with the frame shift was a CCC (proline). The four amino acids that followed this deletion were also altered with the fourth one becoming UAA, the ochre translation stop codon. This premature stopping of translation resulted in a truncation of 60% of the protein, which included the remaining cytoplasmic loop, third and fourth transmembrane regions and the carboxyl-terminus. The later passage cultures did not produce a carboxyl-terminal RT-PCR product, indicating that the mRNA was also truncated. These regions of the Cx32 molecule contain the sequences and epitopes to which probes and antibodies are directed, and as such alterations of these regions with repeated passage explains reports by others that FRTL-5 cells do not express Cx32, and implies that cultures used for these assessments were passed more than 15 times. To determine if genetic or epigenetic abnormalities existed in FRTL-5 cells we performed chromosome spreads from various passage cultures. FRTL-5 cells have been reported to be diploid and more recently non-diploid; however, we found them to be fully tetraploid. This tetraploidy appears to be unstable in that later passes are tetraploid plus two or three extra chromosomes. There were no obvious translocations, breaks or large-scale interstitial deletions of any chromosomes in the FRTL-5 cultures tested. As FRTL-5 cells were repeatedly passed their morphology changed. Monolayer areas spread from beneath the follicles, and the follicles became flattened in appearance. These physical changes were coincident with dramatically increased growth rates. Early cultures (passed 3-12 times) divided on average every 49+/-1 h, whereas later passes (passes 20-25) divided every 28+/-3 h. To correlate these changes with a measure of thyroid function we assayed T(4) output. Early passage follicular cultures incubated for 6 h with sodium iodide, released on average 5.27+/- 0.33 ng/ml of T(4)/100 follicles. Later passes, or early passes treated with heptanol to down-regulate Cx32, released an average of 3.84+/-0.50 ng/ml of T(4)/100 follicles. There was a 27% difference in T(4) release between early follicular cultures, that were coupled by Cx32, and late or down-regulated early follicular cultures, that were uncoupled (P<0.0001). Collectively, the physical changes documented in this study were coincident with the loss of functional Cx32. This implies a relationship between the loss of intercellular communication and changes in morphogenic appearance, growth rate and reduced thyroid function and supports the previously postulated, tumor-suppressor role for Cx32. FRTL-5 cultures from low passage numbers are an excellent model of primary thyroid cells. However, many reports in the literature ascribe features to FRTL-5 cells that are mutually inconsistent. These differences may be resolved in the future by addressing the passage number and the conditional differences of the cultures being studied.

Permeation of fingerprints through laboratory gloves.

PubMed

Willinski, G

1980-07-01

Repeated controlled tests have shown that impressions from laboratory gloves will print onto optical components in 20 to 40 min and, in some cases, sooner. Careful testing demonstrated that palmar sweat passed through the glove material; the problem was not that gloves conform to the friction ridges of the fingers and then transfer some contaminant. The problem can be alleviated to a great extent by wearing thin cotton gloves like those commonly used in the film industry.

Coherent Change Detection: Theoretical Description and Experimental Results

DTIC Science & Technology

2006-08-01

Elementary Linear Algebra With Applications. John Wiley and sons, 1987. 49. J. Lee, K. W. Hoppel, and A. R. Miller, “Intensity and phase statistics of...kx, ky, kz = 0). The nature of the image recovered by the PFA may be ascertained by considering a scene consisting of an elementary point scatter...registered image pair estimate any dominant relative linear phase term between the primary image and the resampled repeat pass image and remove this

Deformation of single and multiple laser peened TC6 titanium alloy

NASA Astrophysics Data System (ADS)

Umapathi, A.; Swaroop, S.

2018-03-01

Laser peening without coating (LPwC) was done on the titanium TC6 alloy at a wavelength of 532 nm using an Nd:YAG laser. The laser power densities of 3, 6 and 9 GW cm-2 were used to peen the samples. Samples were also peened multiple times (1, 3 and 5 passes) at 6 GW cm-2. Microhardness showed an overall 23% increase from the baseline value. Further, softening of α phase in the bulk was observed above 6 GW cm-2 in the samples peened once and above 1 pass in multiply peened samples. A similar trend was observed from the residual stress analysis of the samples. The maximum compressive residual stress was -1780 MPa at a depth of 50 μm at 9 GW cm-2. The observed softening of α phase was proposed due to adiabatic heating. Microstructural changes due to adiabatic heating resulting in increased β volume fractions were observed and confirmed by synchrotron radiation measurements.

Nonlinear to Linear Elastic Code Coupling in 2-D Axisymmetric Media.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preston, Leiph

Explosions within the earth nonlinearly deform the local media, but at typical seismological observation distances, the seismic waves can be considered linear. Although nonlinear algorithms can simulate explosions in the very near field well, these codes are computationally expensive and inaccurate at propagating these signals to great distances. A linearized wave propagation code, coupled to a nonlinear code, provides an efficient mechanism to both accurately simulate the explosion itself and to propagate these signals to distant receivers. To this end we have coupled Sandia's nonlinear simulation algorithm CTH to a linearized elastic wave propagation code for 2-D axisymmetric media (axiElasti)more » by passing information from the nonlinear to the linear code via time-varying boundary conditions. In this report, we first develop the 2-D axisymmetric elastic wave equations in cylindrical coordinates. Next we show how we design the time-varying boundary conditions passing information from CTH to axiElasti, and finally we demonstrate the coupling code via a simple study of the elastic radius.« less

DSS 43 antenna gain analysis for Voyager Uranus encounter: 8.45-GHz radio science data correction

NASA Technical Reports Server (NTRS)

Slobin, S. D.; Imbriale, W. A.

1987-01-01

A malfunction of the Deep Space Network (DSN) 64-meter antenna in Australia forced the antenna to operate with a mispositioned subreflector during the Voyager Uranus encounter period (January 24, 1986). Because of changing main reflector shape and quadripod position as a function of elevation angle, the antenna gain and pointing were not as expected, and the 8.45 GHz received signal level changed during the pass. The study described here used the Geometrical Theory of Diffraction (GTD) analysis to determine actual antenna gain and pointing during that period in an attempt to reconstruct the radio science data. It is found that the 1.4 dB of signal variation can be accounted for by antenna geometry changes and pointing error. Suggested modifications to the values measured during the pass are presented. Additionally, an extremely useful tool for the analysis of gravity deformed reflectors was developed for use in future antenna design and analysis projects.

Erythrocyte deformability and aggregation responses to intermittent and continuous artificial gravity exposure

NASA Astrophysics Data System (ADS)

Marijke, Grau; Vera, Abeln; Tobias, Vogt; Wilhelm, Bloch; Stefan, Schneider

2017-02-01

Artificial gravity protocols are used to improve g-tolerance of aviators and discussed as countermeasure during prolonged space flight. Little is known about the impact of artificial gravity on the red blood cells (RBC). The purpose of the study was to test how artificial gravity affects RBC deformability and aggregation, which are important determinants of microcirculation. Nine male subjects were exposed to two hypergravity protocols using a short arm human centrifuge: a continuous (CONT) protocol with constant +2 Gz for 30 min and an intermittent (INTER) protocol with repeated intervals of +2 Gz and rest. Blood was sampled pre and post interventions to measure basal blood parameters, RBC nitrite, RBC deformability, aggregation, and to determine the shear rate balancing aggregation and disaggregation (γ at dIsc min). To test for orthostasis effects, five male subjects were asked to stay for 46 min, corresponding to the length of the centrifuge protocols, with blood sampling pre and post intervention. Artificial gravity programs did not affect basal blood parameters or RBC nitrite levels; a marker for RBC deformability influencing nitric oxide. The INTER program did not affect any of the tested parameters. The CONT program did not remarkably affect RBC deformability or γ at dIsc min but significantly aggravated aggregation. Orthostasis effects were thus excluded. The results indicate that continuous artificial gravity, especially with higher g-forces applied, may negatively affect the RBC system and that for a prolonged space flight intermittent but not continuous artificial gravity might represent an appropriate countermeasure.

Radiology of Cleft Lip and Palate: Imaging for the Prenatal Period and throughout Life.

PubMed

Abramson, Zachary R; Peacock, Zachary S; Cohen, Harris L; Choudhri, Asim F

2015-01-01

Recent advances in prenatal imaging have made possible the in utero diagnosis of cleft lip and palate and associated deformities. Postnatal diagnosis of cleft lip is made clinically, but imaging still plays a role in detection of associated abnormalities, surgical treatment planning, and screening for or surveillance of secondary deformities. This article describes the clinical entities of cleft lip with or without cleft palate (CLP) and isolated cleft palate and documents their prenatal and postnatal appearances at radiography, ultrasonography (US), magnetic resonance (MR) imaging, and computed tomography (CT). Imaging protocols and findings for prenatal screening, detection of associated anomalies, and evaluation of secondary deformities throughout life are described and illustrated. CLP and isolated cleft palate are distinct entities with shared radiologic appearances. Prenatal US and MR imaging can depict clefting of the lip or palate and associated anomalies. While two- and three-dimensional US often can depict cleft lip, visualization of cleft palate is more difficult, and repeat US or fetal MR imaging should be performed if cleft palate is suspected. Postnatal imaging can assist in identifying associated abnormalities and dentofacial deformities. Dentofacial sequelae of cleft lip and palate include missing and supernumerary teeth, oronasal fistulas, velopharyngeal insufficiency, hearing loss, maxillary growth restriction, and airway abnormalities. Secondary deformities can often be found incidentally at imaging performed for other purposes, but detection is necessary because they may have considerable implications for the patient. (©)RSNA, 2015.

Estimating zero strain states of very soft tissue under gravity loading using digital image correlation⋆,⋆⋆,★

PubMed Central

Gao, Zhan; Desai, Jaydev P.

2009-01-01

This paper presents several experimental techniques and concepts in the process of measuring mechanical properties of very soft tissue in an ex vivo tensile test. Gravitational body force on very soft tissue causes pre-compression and results in a non-uniform initial deformation. The global Digital Image Correlation technique is used to measure the full field deformation behavior of liver tissue in uniaxial tension testing. A maximum stretching band is observed in the incremental strain field when a region of tissue passes from compression and enters a state of tension. A new method for estimating the zero strain state is proposed: the zero strain position is close to, but ahead of the position of the maximum stretching band, or in other words, the tangent of a nominal stress-stretch curve reaches minimum at λ ≳ 1. The approach, to identify zero strain by using maximum incremental strain, can be implemented in other types of image-based soft tissue analysis. The experimental results of ten samples from seven porcine livers are presented and material parameters for the Ogden model fit are obtained. The finite element simulation based on the fitted model confirms the effect of gravity on the deformation of very soft tissue and validates our approach. PMID:20015676

High-Efficiency Multiscale Modeling of Cell Deformations in Confined Microenvironments in Microcirculation and Microfluidics

NASA Astrophysics Data System (ADS)

Lu, Huijie; Peng, Zhangli

2017-11-01

We developed a high-efficiency multiscale modeling method to predict the stress and deformation of cells during the interactions with their microenvironments in microcirculation and microfluidics, including red blood cells (RBCs) and circulating tumor cells (CTCs). There are more than 1 billion people in the world suffering from RBC diseases. The mechanical properties of RBCs are changed in these diseases due to molecular structure alternations, which is not only important for understanding the disease pathology but also provides an opportunity for diagnostics. On the other hand, the mechanical properties of cancer cells are also altered compared to healthy cells. This can lead to acquired ability to cross the narrow capillary networks and endothelial gaps, which is crucial for metastasis, the leading cause of cancer mortality. Therefore, it is important to predict the deformation and stress of RBCs and CTCs in microcirculations. We develop a high-efficiency multiscale model of cell-fluid interaction. We pass the information from our molecular scale models to the cell scale to study the effect of molecular mutations. Using our high-efficiency boundary element methods of fluids, we will be able to run 3D simulations using a single CPU within several hours, which will enable us to run extensive parametric studies and optimization.

Time-dependent edge-notch sensitivity of oxide and gamma prime dispersion strengthened sheet materials at 1000 to 1800 F (538 - 982 C)

NASA Technical Reports Server (NTRS)

Wilson, D. J.

1972-01-01

Research was carried out to determine whether an oxide dispersion hardened alloy, TD-Ni, Cr, and low volume fraction gamma prime strengthened nickel-base alloy, Modified Waspaloy, were susceptible to time-dependent edge-notch sensitivity. The results were evaluated in terms of the mechanical characteristics of the alloys and the dislocation motion mechanisms operative. As far as could be determined, the results of the investigation were consistent with the following important concepts developed for Waspaloy and Inconel 718: (1) Time-dependent edge-notch sensitivity occurs when notched specimens are loaded below the approximate 0.2 percent smooth specimen offset yield strength and when data from smooth specimens indicate that small amounts of creep consume large rupture life fractions. (2) When precipitate particles are sheared by dislocations, the deformation is localized and time-dependent notch sensitivity occurs. When dislocations by-pass precipitate particles the deformation is homogeneous. Under these conditions, no time-dependent notch sensitivity has been observed.

Magmas near the critical degassing pressure drive volcanic unrest towards a critical state

PubMed Central

Chiodini, Giovanni; Paonita, Antonio; Aiuppa, Alessandro; Costa, Antonio; Caliro, Stefano; De Martino, Prospero; Acocella, Valerio; Vandemeulebrouck, Jean

2016-01-01

During the reawaking of a volcano, magmas migrating through the shallow crust have to pass through hydrothermal fluids and rocks. The resulting magma–hydrothermal interactions are still poorly understood, which impairs the ability to interpret volcano monitoring signals and perform hazard assessments. Here we use the results of physical and volatile saturation models to demonstrate that magmatic volatiles released by decompressing magmas at a critical degassing pressure (CDP) can drive volcanic unrest towards a critical state. We show that, at the CDP, the abrupt and voluminous release of H2O-rich magmatic gases can heat hydrothermal fluids and rocks, triggering an accelerating deformation that can ultimately culminate in rock failure and eruption. We propose that magma could be approaching the CDP at Campi Flegrei, a volcano in the metropolitan area of Naples, one of the most densely inhabited areas in the world, and where accelerating deformation and heating are currently being observed. PMID:27996976

Spondylocostal dysostosis associated with right-sided polythelia, right-sided rib deformity and meningocoele: Case report with review of literature

PubMed Central

Rai, Narendra; Thakur, Neha; Khan, Naheed Zin; Dwivedi, Akhilesh Dutt

2015-01-01

Spondylocostal dysostosis (SCD) is a rare anomaly of axial skeleton due to flawed embryological development. A newborn baby boy with right-sided polythelia, meningocoele, fan-like configuration of third and fourth rib, fused fifth and sixth rib and third thoracic hemivertebra was delivered to a second gravid mother by elective caesarean section. Baby was active, cried immediately after birth, had normal muscle tone and reflexes. He passed urine and meconium within 24 h of birth. Based on clinical examination and radiological picture, a diagnosis of SCD with meningocele with right-sided polythelia was made. Our case is the first SCD with polythelia and meningocele in newborn. SCD with right-sided polythelia and rib deformity with neural tube defect (NTD) may be due to a genetic defect with the culprit genes missing. Further genetic and embryological studies might find a link between right-sided rib defects, polythelia and NTD. PMID:26962344

Effect of hot rolling on the structure and the mechanical properties of nitrogen-bearing austenitic-martensitic 14Kh15AN4M steel

NASA Astrophysics Data System (ADS)

Bannykh, O. A.; Betsofen, S. Ya.; Lukin, E. I.; Blinov, V. M.; Voznesenskaya, N. M.; Tonysheva, O. A.; Blinov, E. V.

2016-04-01

The effect of the rolling temperature and strain on the structure and the properties of corrosionresistant austenitic-martensitic 14Kh15AN4M steel is studied. The steel is shown to exhibit high ductility: upon rolling in the temperature range 700-1100°C at a reduction per pass up to 80%, wedge steel specimens are uniformly deformed along and across the rolling direction without cracking and other surface defects. Subsequent cold treatment and low-temperature tempering ensure a high hardness of the steel (50-56 HRC). Austenite mainly contributes to the hardening upon rolling in the temperature range 700-800°C at a reduction of 50-70%, and martensite makes the main contribution at higher temperatures and lower strains. Texture does not form under the chosen deformation conditions, which indicates dynamic recrystallization with the nucleation and growth of grains having no preferential orientation.

Microstructure Characterization of Weakly Textured and Fine Grained AZ61 Sheet

NASA Astrophysics Data System (ADS)

Berman, T. D.; Donlon, W.; Hung, C. K.; Milligan, P.; Decker, R.; Pollock, T. M.; Jones, J. W.

Formability in magnesium alloy sheet is strongly limited by a strong basal texture in the as-rolled material, which is difficulty to remove by thermal processing. We introduce a new process to the control of texture by combining Thixomolding and Thermomechanical Processing (TTMP). Plates of AZ61L with a divorced β-Mg17Al12 eutectic are produced by Thixomolding, resulting in a non-textured, fine grained (2.8 µm) precursor. Sheet produced from the plate by single pass warm-rolling exhibits a weaker texture, and more isotropic tensile deformation than generally observed in AZ-series alloy sheet. Recrystallization annealing produces a further reduction in texture and average grain size (2.3 µm) and results in nearly isotropic room temperature deformation, a yield strength of 220 MPa, and an elongation of 23%. Particle stimulated nucleation of new grains by the β-phase during both dynamic and static recrystallization, is critical for achieving the low levels of texture. The influence of β-phase distribution in microstructure development is discussed.

Fabrication of wrist-like SMA-based actuator by double smart soft composite casting

NASA Astrophysics Data System (ADS)

Rodrigue, Hugo; Wei, Wang; Bhandari, Binayak; Ahn, Sung-Hoon

2015-12-01

A new manufacturing method for smart soft composite (SSC) actuators that consists of double casting a SSC actuator to produce an actuator with non-linear shape memory alloy (SMA) wire positioning is proposed. This method is used to manufacture a tube-shaped SSC actuator in which the SMA wires follow the curvature of the tube and is capable of pure-twisting deformations while sustaining a cantilever load. The concept is tested by measuring the maximum twisting angle and a simple control method is proposed to control the twisting angle of the actuator. Then, a soft robotic wrist with a length of 18 cm is built, its load-carrying capability is tested by measuring the cantilever force required for deforming the actuator, and its load-carrying capability during actuation is tested by loading one end with different objects and actuating the actuator. This wrist actuator shows good repeatability, is capable of twisting deformations up to 25° while holding objects weighing 100 g, and can sustain loads above 2 N without undergoing buckling.

Thermal Excitation System for Shearography (TESS)

NASA Technical Reports Server (NTRS)

Lansing, Matthew D.; Bullock, Michael W.

1996-01-01

One of the most convenient and effective methods of stressing a part or structure for shearographic evaluation is thermal excitation. This technique involves heating the part, often convectively with a heat gun, and then monitoring with a shearography device the deformation during cooling. For a composite specimen, unbonds, delaminations, inclusions, or matrix cracking will deform during cooling differently than other more structurally sound regions and thus will appear as anomalies in the deformation field. However, one of the difficulties that cause this inspection to be dependent on the operator experience is the conventional heating process. Fanning the part with a heat gun by hand introduces a wide range of variability from person to person and from one inspection to the next. The goal of this research effort was to conduct research in the methods of thermal excitation for shearography inspection. A computerized heating system was developed for inspection of 0.61 m (24 in.) square panels. The Thermal Excitation System for Shearography (TESS) provides radiant heating with continuous digital measurement of the surface temperature profile to ensure repeatability. The TESS device functions as an accessory to any electronic shearography device.

Rehearsal significantly improves immediate and delayed recall on the Rey Auditory Verbal Learning Test.

PubMed

Hessen, Erik

2011-10-01

A repeated observation during memory assessment with the Rey Auditory Verbal Learning Test (RAVLT) is that patients who spontaneously employ a memory rehearsal strategy by repeating the word list more than once achieve better scores than patients who only repeat the word list once. This observation led to concern about the ability of the standard test procedure of RAVLT and similar tests in eliciting the best possible recall scores. The purpose of the present study was to test the hypothesis that a rehearsal recall strategy of repeating the word list more than once would result in improved scores of recall on the RAVLT. We report on differences in outcome after standard administration and after experimental administration on Immediate and Delayed Recall measures from the RAVLT of 50 patients. The experimental administration resulted in significantly improved scores for all the variables employed. Additionally, it was found that patients who failed effort screening showed significantly poorer improvement on Delayed Recall compared with those who passed the effort screening. The general clear improvement both in raw scores and T-scores demonstrates that recall performance can be significantly influenced by the strategy of the patient or by small variations in instructions by the examiner.

Light beam frequency comb generator

DOEpatents

Priatko, G.J.; Kaskey, J.A.

1992-11-24

A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics. 2 figs.

Light beam frequency comb generator

DOEpatents

Priatko, Gordon J.; Kaskey, Jeffrey A.

1992-01-01

A light beam frequency comb generator uses an acousto-optic modulator to generate a plurality of light beams with frequencies which are uniformly separated and possess common noise and drift characteristics. A well collimated monochromatic input light beam is passed through this modulator to produce a set of both frequency shifted and unshifted optical beams. An optical system directs one or more frequency shifted beams along a path which is parallel to the path of the input light beam such that the frequency shifted beams are made incident on the modulator proximate to but separated from the point of incidence of the input light beam. After the beam is thus returned to and passed through the modulator repeatedly, a plurality of mutually parallel beams are generated which are frequency-shifted different numbers of times and possess common noise and drift characteristics.

Arthroscopic all-inside repair for a tear of posterior root of the medial meniscus: a technical note.

PubMed

Choi, Nam-Hong; Son, Kyung-Mo; Victoroff, Brian N

2008-09-01

This technical note describes a new arthroscopic technique to repair a tear of posterior root of the medial meniscus. Cartilage at the insertion area of the posterior horn of the medial meniscus (PHMM) was removed using a curved curette inserted through an anteromedial portal. A metal anchor loaded with two FiberWires (Arthrex, Naples, FL) was placed at the insertion area of the PHMM through a high posteromedial portal. A PDS suture was passed the PHMM by curved suture hook through the anteromedial portal. Two limbs of the PDS were then used to pass two limbs of the FiberWire through the meniscus. The same procedure was repeated for the second FiberWire suture. The sutures were tied, achieving secure fixation of the posterior meniscal root at the anatomic insertion.

Phase Distribution and Selection of Partially Correlated Persistent Scatterers

NASA Astrophysics Data System (ADS)

Lien, J.; Zebker, H. A.

2012-12-01

Interferometric synthetic aperture radar (InSAR) time-series methods can effectively estimate temporal surface changes induced by geophysical phenomena. However, such methods are susceptible to decorrelation due to spatial and temporal baselines (radar pass separation), changes in orbital geometries, atmosphere, and noise. These effects limit the number of interferograms that can be used for differential analysis and obscure the deformation signal. InSAR decorrelation effects may be ameliorated by exploiting pixels that exhibit phase stability across the stack of interferograms. These so-called persistent scatterer (PS) pixels are dominated by a single point-like scatterer that remains phase-stable over the spatial and temporal baseline. By identifying a network of PS pixels for use in phase unwrapping, reliable deformation measurements may be obtained even in areas of low correlation, where traditional InSAR techniques fail to produce useful observations. Many additional pixels can be added to the PS list if we are able to identify those in which a dominant scatterer exhibits partial, rather than complete, correlation across all radar scenes. In this work, we quantify and exploit the phase stability of partially correlated PS pixels. We present a new system model for producing interferometric pixel values from a complex surface backscatter function characterized by signal-to-clutter ratio (SCR). From this model, we derive the joint probabilistic distribution for PS pixel phases in a stack of interferograms as a function of SCR and spatial baselines. This PS phase distribution generalizes previous results that assume the clutter phase contribution is uncorrelated between radar passes. We verify the analytic distribution through a series of radar scattering simulations. We use the derived joint PS phase distribution with maximum-likelihood SCR estimation to analyze an area of the Hayward Fault Zone in the San Francisco Bay Area. We obtain a series of 38 interferometric images of the area from C-band ERS radar satellite passes between May 1995 and December 2000. We compare the estimated SCRs to those calculated with previously derived PS phase distributions. Finally, we examine the PS network density resulting from varying selection thresholds of SCR and compare to other PS identification techniques.

Development of manufacturing systems for nanocrystalline and ultra-fine grain materials employing indexing equal channel angular pressing

NASA Astrophysics Data System (ADS)

Hester, Michael Wayne

Nanotechnology offers significant opportunities in providing solutions to existing engineering problems as well as breakthroughs in new fields of science and technology. In order to fully realize benefits from such initiatives, nanomanufacturing methods must be developed to integrate enabling constructs into commercial mainstream. Even though significant advances have been made, widespread industrialization in many areas remains limited. Manufacturing methods, therefore, must continually be developed to bridge gaps between nanoscience discovery and commercialization. A promising technology for integration of top-down nanomanufacturing yet to receive full industrialization is equal channel angular pressing, a process transforming metallic materials into nanostructured or ultra-fine grained materials with significantly improved performance characteristics. To bridge the gap between process potential and actual manufacturing output, a prototype top-down nanomanufacturing system identified as indexing equal channel angular pressing (IX-ECAP) was developed. The unit was designed to capitalize on opportunities of transforming spent or scrap engineering elements into key engineering commodities. A manufacturing system was constructed to impose severe plastic deformation via simple shear in an equal channel angular pressing die on 1100 and 4043 aluminum welding rods. 1/4 fraction factorial split-plot experiments assessed significance of five predictors on the response, microhardness, for the 4043 alloy. Predictor variables included temperature, number of passes, pressing speed, back pressure, and vibration. Main effects were studied employing a resolution III design. Multiple linear regression was used for model development. Initial studies were performed using continuous processing followed by contingency designs involving discrete variable length work pieces. IX-ECAP offered a viable solution in severe plastic deformation processing. Discrete variable length work piece pressing proved very successful. With three passes through the system, 4043 processed material experienced an 88.88% increase in microhardness, 203.4% increase in converted yield strength, and a 98.5% reduction in theoretical final grain size to 103 nanometers using the Hall-Petch relation. The process factor, number of passes, was statistically significant at the 95% confidence level; whereas, temperature was significant at the 90% confidence level. Limitations of system components precluded completion of studies involving continuous pressing. Proposed system redesigns, however, will ensure mainstream commercialization of continuous length work piece processing.

Understanding thermally activated plastic deformation behavior of Zircaloy-4

NASA Astrophysics Data System (ADS)

Kumar, N.; Alomari, A.; Murty, K. L.

2018-06-01

Understanding micromechanics of plastic deformation of existing materials is essential for improving their properties further and/or developing advanced materials for much more severe load bearing applications. The objective of the present work was to understand micromechanics of plastic deformation of Zircaloy-4, a zirconium-based alloy used as fuel cladding and channel (in BWRs) material in nuclear reactors. The Zircaloy-4 in recrystallized (at 973 K for 4 h) condition was subjected to uniaxial tensile testing at a constant cross-head velocity at temperatures in the range 293 K-1073 K and repeated stress relaxation tests at 293 K, 573 K, and 773 K. The minimum in the total elongation was indicative of dynamic strain aging phenomenon in this alloy in the intermediate temperature regime. The yield stress of the alloy was separated into effective and athermal components and the transition from thermally activated dislocation glide to athermal regime took place at around 673 K with the athermal stress estimated to be 115 MPa. The activation volume was found to be in the range of 40 b3 to 160 b3. The activation volume values and the data analyses using the solid-solution models in literature indicated dislocation-solute interaction to be a potential deformation mechanism in thermally activated regime. The activation energy calculated at 573 K was very close to that found for diffusivity of oxygen in α-Zr that was suggestive of dislocations-oxygen interaction during plastic deformation. This type of information may be helpful in alloy design in selecting different elements to control the deformation behavior of the material and impart desired mechanical properties in those materials for specific applications.

Repetitive Supra-Physiological Shear Stress Impairs Red Blood Cell Deformability and Induces Hemolysis.

PubMed

Horobin, Jarod T; Sabapathy, Surendran; Simmonds, Michael J

2017-11-01

The supra-physiological shear stress that blood is exposed to while traversing mechanical circulatory assist devices affects the physical properties of red blood cells (RBCs), impairs RBC deformability, and may induce hemolysis. Previous studies exploring RBC damage following exposure to supra-physiological shear stress have employed durations exceeding clinical instrumentation, thus we explored changes in RBC deformability following exposure to shear stress below the reported "hemolytic threshold" using shear exposure durations per minute (i.e., duty-cycles) reflective of that employed by circulatory assist devices. Blood collected from 20 male donors, aged 18-38 years, was suspended in a viscous medium and exposed to an intermittent shear stress protocol of 1 s at 100 Pa, every 60 s for 60 duty-cycles. During the remaining 59 s/min, the cells were left at stasis until the subsequent duty-cycle commenced. At discrete time points (15/30/45/60 duty-cycles), an ektacytometer measured RBC deformability immediately after shear exposure at 100 Pa. Plasma-free hemoglobin, a measurement of hemolysis, was quantified via spectrophotometry. Supra-physiological shear stress impaired RBC properties, as indicated by: (1) decreased maximal elongation of RBCs at infinite shear stress following 15 duty-cycles (P <0.05); (2) increased real-time RBC deformability during application of the supra-physiological shear stress protocol (100 Pa) following exposure to 1 duty-cycle (F (1.891, 32.15) = 12.21, P = 0.0001); and (3) increased plasma-free hemoglobin following 60 duty-cycles (P < 0.01). The present study indicates that exposure of RBCs to short-term, repeated supra-physiological shear stress, impairs RBC deformability, with the extent of impairment exacerbated with each duty-cycle, and ultimately precipitates hemolysis. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Outcome of Conventional Adipose Tissue Grafting for Contour Deformities of Face and Role of Ex Vivo Expanded Adipose Tissue-Derived Stem Cells in Treatment of Such Deformities.

PubMed

Bashir, Muhammad Mustehsan; Sohail, Muhammad; Bashir, Afzaal; Khan, Farid Ahmad; Jan, Sadia Nosheen; Imran, Muhammad; Ahmad, Fridoon Jawad; Choudhery, Mahmood S

2018-02-23

To evaluate the outcomes of conventional fat grafting for facial contour deformities and to describe clinical outcome of a patient with contour deformity of face treated with ex vivo expanded adipose tissue-derived mesenchymal stem cells (ASCs) enriched fat graft. The Department of Plastic Surgery and Tissue Engineering and Regenerative Medicine Laboratory, King Edward Medical University/Mayo Hospital, Lahore, from September 2015 to September 2017. Patients with contour deformities of face requiring soft tissue augmentation were included. Fat was harvested, processed, and injected following a standard protocol. Both subjective and objective assessments were performed and complications were also noted. Twenty-five patients underwent 51 fat-grafting sessions over a period of 24 months. Eighteen (72%) patients underwent multiple fat-grafting sessions. Mean (standard deviation) soft tissue thickness after 72 hours and 6 months of first fat graft session was 18.62 (7.2) and 12.88 (6.21) mm, respectively, which corresponds to 30.77 (13)% reduction of transplanted fat. Physician and patient assessment scores were 3.42 (0.92) and 4 (1.04), respectively. Few minor complications were observed. In the patient undergoing ex vivo expanded ASCs enriched fat graft, there was minimal decrease in soft tissue thickness of treated area (44 mm vs 42 mm) 6 months postoperatively and patient was highly satisfied with the outcome after the single session. Conventional fat grafting is safe for correction of facial contour deformities. However, procedure needs to be repeated multiple times to produce satisfactory results. Beneficial effects of ex vivo expanded ASCs enriched fat grafting have a potential to alter the current treatment paradigm of fat grafting for soft tissue reconstruction.

Expression of Extracellular Signal-regulated Kinase 5 and Ankyrin Repeat Domain 1 in Composite Pheochromocytoma and Ganglioneuroblastoma Detected Incidentally in the Adult Adrenal Gland

PubMed Central

Suenaga, Shinta; Ichiyanagi, Osamu; Ito, Hiromi; Naito, Sei; Kato, Tomoyuki; Nagaoka, Akira; Kato, Tomoya; Yamakawa, Mitsunori; Obara, Yutaro; Tsuchiya, Norihiko

2016-01-01

Composite pheochromocytoma (cPC) is extremely rare, arising in the adrenal medulla as a mixture of PC and other tumors of neural origin. We herein report on a case of adrenal incidentaloma post-operatively diagnosed as cPC with ganglioneuroblastoma (GNBL). The PC component had 7 points on the PASS, a Ki-67 index of 5.1%, a focal absence of sustentacular cells, and no genetic aberrations in succinate dehydrogenase subunit B. The GNBL component exhibited no N-myc amplification. Tumor cells of both components were stained positively for extracellular signal-regulated kinase 5 and ankyrin repeat domain 1. The aberrant activation of growth signaling may play a role in the marginal malignancy of cPC. PMID:27980262

Accuracy and repeatability positioning of high-performancel athe for non-circular turning

NASA Astrophysics Data System (ADS)

Majda, Paweł; Powałka, Bartosz

2017-11-01

This paper presents research on the accuracy and repeatability of CNC axis positioning in an innovative lathe with an additional Xs axis. This axis is used to perform movements synchronized with the angular position of the main drive, i.e. the spindle, and with the axial feed along the Z axis. This enables the one-pass turning of non-circular surfaces, rope and trapezoidal threads, as well as the surfaces of rotary tools such as a gear cutting hob, etc. The paper presents and discusses the interpretation of results and the calibration effects of positioning errors in the lathe's numerical control system. Finally, it shows the geometric characteristics of the rope thread turned at various spindle speeds, including before and after-correction of the positioning error of the Xs axis.

An Alternative Three-Term Decomposition for Single Crystal Deformation Motivated by Non-Linear Elastic Dislocation Solutions

DTIC Science & Technology

2014-04-01

yet fully passed through. This element is free from traction along its external surface , and thus is in a state of self stress. The remainder of...neighbours so that it too is in a state of self stress. External boundaries of the entire slab are also necessarily traction free in this global intermediate...N ⊗ u)dS = 12V0 ∫ [∇u+ (∇u)T]dV0 must vanish in a domain with uniform material properties that is in a state of self stress (that is, a homogeneous

Anomalous Accretionary Margin Topography Formed By Repeated Earthquakes

NASA Astrophysics Data System (ADS)

Furlong, Kevin P.

2014-05-01

It has long been recognized that accretionary margins of major subduction zones undergo substantial deformation. However even with the large amounts of shortening accommodated within the margin, for most subduction zones, there is an extended submarine portion to the accretionary, highly-deformed upper-plate between the trench and the coast. This is a vexing situation since this submarine section typically overlies the actual locked or coupled patch of the plate interface. The result of this is added difficulty in directly observing processes related to the plate interface coupling - such processes as micro-seismicity and the actual patterns of plate coupling. There are a few locations globally in which there are sub-aerially exposed terranes that lie closer to the trench and overlie the inferred coupled or seismogenic portion of the plate interface. Such regions have taken on significance in subduction zone studies as they provide locations to observe the plate interface coupling effects in the near-field. In particular the Pacific coast of Costa Rica provides such a location, and there has been substantial geologic, geophysical, and geodetic research exploiting the positions of these near-trench peninsulas (Nicoya, Osa, and Burica). These sites provide near-field access to plate-interface processes, but whether they represent typical subduction zone behavior remains an open question as the deformational processes or inherited structures that have produced this anomalous topography are not well constrained. Simply put, if the existence of these sub-aerial, near-trench terranes is a result of anomalous behavior on the plate interface (as has been suggested), then their utility in providing high-fidelity near-field insight into the plate interface properties and processes is substantially reduced. Here we propose a new mechanism that could be responsible for the formation of both the Nicoya and Osa Peninsulas in the past, and is currently producing a third peninsula - the Burica Peninsula at the intersection of the Panama fracture zone and the margin. Specifically we propose that the anomalous topography along the Pacific coast of Costa Rica has been produced by repeated, great subduction earthquakes that have ruptured across the boundary separating the Cocos and Nazca plates - the subducted continuation of the Panama fracture zone. The pattern of upper-plate shortening generated by such a process (documented in the 2007 Mw 8.1 Solomon Islands earthquake, which produced co-seismic localized uplift above the subducted transform plate boundary) convolved with the migration history of the Panama triple junction (PTJ) is proposed as the mechanism to produce substantial along-margin, long-lived accretionary margin topography. Specifically we argue that repeated great subduction earthquakes that rupture across fundamental plate boundary structures can produce substantial, long-lived upper plate deformation above the inter-seismically coupled plate interface.

Integration of Space-borne SAR and Ground-Based Radar for 3D Deformation Mapping of the Central Calaveras Fault at Coyote Dam

NASA Astrophysics Data System (ADS)

Werner, C. L.; Baker, B.; Milillo, P.; Magnard, C.; Strozzi, T.; Wegmüller, U.

2017-12-01

The Central Calaveras Fault (CCF) passes directly through Coyote Dam located southeast of Morgan Hill, California. This earthen embankment dam owned and operated by the Santa Clara Valley Water District (District), has experienced over 80 cm of accumulated fault creep since its construction in 1936. The average slip rate is 10 to 15 mm/year as measured using surveying, GPS, and more recently, terrestrial radar interferometry (TRI). The CCF is a right-lateral strike-slip fault that has the potential for a M7.25 earthquake resulting in meter scale displacement. In 2015, the District initiated a geological analysis of the CCF integrating past surveying, GPS data, TRI deformation mapping, paleoseismic trenching, and boreholes. The initial TRI survey included dam measurements from two locations, imaging the upstream and downstream embankments over the period from February to July 2015. The TRI data from the downstream embankment data showed a complex deformation pattern not consistent with a strike-slip fault model. A second measurement campaign was initiated utilizing multiple radar viewpoints with the aim of resolving the 3D deformation field of the downstream embankment. The campaign occurred between May and November 2016 and showed an unexpected strong westward and downward movement exceeding 2 cm/year (see Figure). TRI data were acquired from 4 separate observation points every 2 to 4 weeks during this campaign. Point target analysis methods were used to avoid contamination of the deformation data by vegetation and radar shadow. Deformation uncertainty in the downstream fault zone was relatively high due to the nearly coplanar arrangement of the TRI observation points. To better constrain the vertical deformation, in this report we integrate spaceborne measurements from the Cosmo-SkyMed (CS) radar satellite in the 3D deformation solution. The LOS to the satellite has a large vertical component not present in the TRI measurement geometry that facilitates the inversion. The CS 3-meter resolution data have been acquired every 16 days between 2011 and 2017. These data are used to test the consistency of the TRI results and the long observation period permits identification of periodic hydrologic signals suggested in the TRI measurements.

Active tectonics of the northern Mojave Desert: The 2017 Desert Symposium field trip road log

USGS Publications Warehouse

Miller, David; Reynolds, R.E.; Phelps, Geoffrey; Honke, Jeff; Cyr, Andrew J.; Buesch, David C.; Schmidt, Kevin M.; Losson, G.

2017-01-01

The 2017 Desert Symposium field trip will highlight recent work by the U.S. Geological Survey geologists and geophysicists, who have been mapping young sediment and geomorphology associated with active tectonic features in the least well-known part of the eastern California Shear Zone (ECSZ). This area, stretching from Barstow eastward in a giant arc to end near the Granite Mountains on the south and the Avawatz Mountains on the north (Fig. 1-1), encompasses the two major structural components of the ECSZ—east-striking sinistral faults and northwest-striking dextral faults—as well as reverseoblique and normal-oblique faults that are associated with topographic highs and sags, respectively. In addition, folds and stepovers (both restraining stepovers that form pop-up structures and releasing stepovers that create narrow basins) have been identified. The ECSZ is a segment in the ‘soft’ distributed deformation of the North American plate east of the San Andreas fault (Fig. 1-1), where it takes up approximately 20-25% of plate motion in a broad zone of right-lateral shear (Sauber et al., 1994) The ECSZ (sensu strictu) begins in the Joshua Tree area and passes north through the Mojave Desert, past the Owens Valley-to-Death Valley swath and northward, where it is termed the Walker Lane. It has been defined as the locus of active faulting (Dokka and Travis, 1990), but when the full history from about 10 Ma forward is considered, it lies in a broader zone of right shear that passes westward in the Mojave Desert to the San Andreas fault (Mojave strike-slip province of Miller and Yount, 2002) and passes eastward to the Nevada state line or beyond (Miller, this volume).We will visit several accessible highlights for newly studied faults, signs of young deformation, and packages of syntectonic sediments. These pieces of a complex active tectonic puzzle have yielded some answers to longstanding questions such as: How is fault slip transfer in this area accommodated between northwest-striking dextral faults and eaststriking sinistral faults?How is active deformation on the Ludlow fault transferred northward, presumably to connect to the southern Death Valley fault zone?When were faults in this area of the central Mojave Desert initiated?Are faults in this area more or less active than faults in the ECSZ to the west?What is the role of NNW-striking faults and when did they form?How has fault slip changed over time? Locations and fault names are provided in figure 1-2. Important turns and locations are identified with locations in the projection: UTM, zone 11; datum NAD 83: (578530 3917335).

Study of deformation behavior, structure and mechanical properties of the AlSiMnFe alloy during ECAP-PBP.

PubMed

Naizabekov, A B; Andreyachshenko, V A; Kocich, Radim

2013-01-01

The presented article deals with the effects of equal channel angular pressing (ECAP) with a newly adjusted die geometry on the microstructure and mechanical properties of the Al-Si-Mn-Fe alloy. This alloy was subjected to two modes of heat treatment followed by the ECAP process, which led to partial back pressure (ECAP-PBP). Ultra-fine grained (UFG) structure formed through ECAP-PBP process has been studied by methods of optical as well as electron microscopy. The obtained results indicate that quenched alloys, in comparison to slowly cooled alloys, do not contain large brittle particles which subsequently initiate a premature creation of cracks. It was shown that the mechanical properties of these alloys after such processing depend first and foremost on the selected type of heat treatment and on the number of performed passes. The maximum of ultimate tensile strength (417 MPa) was obtained for quenched alloy after 3 passes. On the other hand, maximum ductility was found in slowly cooled alloy after second pass. Further passes reduced strength due to the brittle behavior of excluded particles. One of the partial findings is that there is only a small dependency of the resulting size of grains on previously applied thermal processing. The minimum grain sizes were obtained after 3 passages, where their size ranged between 0.4 and 0.8 μm. The application of quick cooling after heat processing due to the occurrence of finer precipitates in the matrix seems to produce better results. Copyright © 2012 Elsevier Ltd. All rights reserved.

Triggering of tremors and slow slip event in Guerrero, Mexico, by the 2010 Mw 8.8 Maule, Chile, earthquake

NASA Astrophysics Data System (ADS)

Zigone, Dimitri; Rivet, Diane; Radiguet, Mathilde; Campillo, Michel; Voisin, Christophe; Cotte, Nathalie; Walpersdorf, Andrea; Shapiro, Nikolai M.; Cougoulat, Glenn; Roux, Philippe; Kostoglodov, Vladimir; Husker, Allen; Payero, Juan S.

2012-09-01

We investigate the triggering of seismic tremor and slow slip event in Guerrero (Mexico) by the February 27, 2010 Maule earthquake (Mw 8.8). Triggered tremors start with the arrival of S wave generated by the Maule earthquake, and keep occurring during the passing of ScS, SS, Love and Rayleigh waves. The Rayleigh wave dispersion curve footprints the high frequency energy envelope of the triggered tremor, indicating a strong modulation of the source of tremors by the passing surface wave. This correlation and modulation by the passing waves is progressively lost with time over a few hours. The tremor activity continues during the weeks/months after the earthquake. GPS time series suggest that the second sub-event of the 2009-2010 SSE in Guerrero is actually triggered by the Maule earthquake. The southward displacement of the GPS stations starts coincidently with the earthquake and tremors. The long duration of tremors indicate a continuing deformation process at depth, which we propose to be the second sub-event of the 2009-2010 SSE. We show a quasi-systematic correlation between surface displacement rate measured by GPS and tremor activity, suggesting that the NVT are controlled by the variations in the slip history of the SSE. This study shows that two types of tremors emerge: (1) Those directly triggered by the passing waves and (2) those triggered by the stress variations associated with slow slip. This indicates the prominent role of aseismic creep in the Mexican subduction zone response to a large teleseismic earthquake, possibly leading to large-scale stress redistribution.

Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam

USGS Publications Warehouse

Nyqvist, Daniel; Greenberg, L.; Goerig, E.; Calles, O.; Bergman, E.; Ardren, William R.; Castro-Santos, Theodore R.

2017-01-01

Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migrating fish will use. Passage solutions must address not only the number or percentage of fish that successfully pass a barrier, but also the time it takes to pass. Here, we used radiotelemetry to study the functionality of a fish bypass for downstream-migrating wild-caught and hatchery-released Atlantic salmon smolts. We used time-to-event analysis to model the influence of fish characteristics and environmental variables on the rates of a series of events associated with dam passage. Among the modelled events were approach rate to the bypass entry zone, retention rates in both the forebay and the entry zone and passage rates. Despite repeated attempts, only 65% of the tagged fish present in the forebay passed the dam. Fish passed via the bypass (33%), via spill (18%) and via turbines (15%). Discharge was positively related to approach, passage and retention rates. We did not detect any differences between wild and hatchery fish. Even though individual fish visited the forebay and the entry zone on multiple occasions, most fish passed during the first exposures to these zones. This study underscores the importance of timeliness to passage success and the usefulness of time-to-event analysis for understanding factors governing passage performance.

The Significance of Experiences of Nature for People with Parkinson’s Disease, with Special Focus on Freezing of Gait—The Necessity for a Biophilic Environment. A Multi-Method Single Subject Study

PubMed Central

Ottosson, Johan; Lavesson, Lillian; Pinzke, Stefan; Grahn, Patrik

2015-01-01

Freezing of Gait (FOG) is a common condition in people with Parkinson’s disease (PD). FOG entails suddenly experiencing difficulties moving or feeling that one’s feet are as glued to the ground. It is triggered, e.g., when passing through doorways. Earlier studies suggest that being in natural environments affects FOG in a positive way. Five subjects were recruited to serve as five single subject cases. We used interviews, observations, questionnaires and collected gait pattern data with aid of an accelerometer. A special designed outdoor setting was used, where we investigated whether passing through hedge openings with or without built elements triggered FOG. We found that no one experienced a FOG reaction when they passed through hedge openings without built elements. However, FOG was triggered when a doorframe was inserted into a hedge opening, and/or when peripheral vision was blocked. We interpret the results such that the doorframe triggered a phobic reflex, causing a freezing reaction. Passing through hedge openings does not trigger FOG, which we interpret as a biophilic reaction. Our results, if repeated in future studies, may have significance to everyday lives of PD patients, who could get a simpler life by consciously prioritizing stays in natural surroundings. PMID:26132480

Relations between the single-pass and double-pass transition probabilities in quantum systems with two and three states

NASA Astrophysics Data System (ADS)

Vitanov, Nikolay V.

2018-05-01

In the experimental determination of the population transfer efficiency between discrete states of a coherently driven quantum system it is often inconvenient to measure the population of the target state. Instead, after the interaction that transfers the population from the initial state to the target state, a second interaction is applied which brings the system back to the initial state, the population of which is easy to measure and normalize. If the transition probability is p in the forward process, then classical intuition suggests that the probability to return to the initial state after the backward process should be p2. However, this classical expectation is generally misleading because it neglects interference effects. This paper presents a rigorous theoretical analysis based on the SU(2) and SU(3) symmetries of the propagators describing the evolution of quantum systems with two and three states, resulting in explicit analytic formulas that link the two-step probabilities to the single-step ones. Explicit examples are given with the popular techniques of rapid adiabatic passage and stimulated Raman adiabatic passage. The present results suggest that quantum-mechanical probabilities degrade faster in repeated processes than classical probabilities. Therefore, the actual single-pass efficiencies in various experiments, calculated from double-pass probabilities, might have been greater than the reported values.

Pattern analysis of laser-tattoo interactions for picosecond- and nanosecond-domain 1,064-nm neodymium-doped yttrium-aluminum-garnet lasers in tissue-mimicking phantom.

PubMed

Ahn, Keun Jae; Zheng, Zhenlong; Kwon, Tae Rin; Kim, Beom Joon; Lee, Hye Sun; Cho, Sung Bin

2017-05-08

During laser treatment for tattoo removal, pigment chromophores absorb laser energy, resulting in fragmentation of the ink particles via selective photothermolysis. The present study aimed to outline macroscopic laser-tattoo interactions in tissue-mimicking (TM) phantoms treated with picosecond- and nanosecond-domain lasers. Additionally, high-speed cinematographs were captured to visualize time-dependent tattoo-tissue interactions, from laser irradiation to the formation of photothermal and photoacoustic injury zones (PIZs). In all experimental settings using the nanosecond or picosecond laser, tattoo pigments fragmented into coarse particles after a single laser pulse, and further disintegrated into smaller particles that dispersed toward the boundaries of PIZs after repetitive delivery of laser energy. Particles fractured by picosecond treatment were more evenly dispersed throughout PIZs than those fractured by nanosecond treatment. Additionally, picosecond-then-picosecond laser treatment (5-pass-picosecond treatment + 5-pass-picosecond treatment) induced greater disintegration of tattoo particles within PIZs than picosecond-then-nanosecond laser treatment (5-pass-picosecond treatment + 5-pass-nanosecond treatment). High-speed cinematography recorded the formation of PIZs after repeated reflection and propagation of acoustic waves over hundreds of microseconds to a few milliseconds. The present data may be of use in predicting three-dimensional laser-tattoo interactions and associated reactions in surrounding tissue.

Effect of Temperature on the Storage Life of Polysulfide Sealants

DTIC Science & Technology

1989-01-01

University of Adelaide, South Australia. After two and a half years of experience in Rubber Technology with the Olympic Tyre and Rubber Company, Melbourne...he joined the rubber section of MRL in November 1970. Since 1975 he has been involved in R & D work in the sealant section as an Experimental Officer...repeatedly passing the mixture through a triple roll mill. One set of the calcium carbonate-solvent series was enclosed in a heat sealed wrapping of

Dense pattern multiple pass cells

DOEpatents

Silver, Joel A.; Bomse, David S.

2010-09-21

An optical cell and a method of operating an optical cell comprising employing a first mirror comprising a first hole therein at approximately a center of the first mirror and through which laser light enters the cell, employing a second mirror comprising a second hole therein at approximately a center of the second mirror and through which laser light exits the cell, and forming a Lissajous pattern of spots on the mirrors by repeated reflection of laser light entering the cell.

Repeatable Reverse Engineering with the Platform for Architecture-Neutral Dynamic Analysis

DTIC Science & Technology

2015-09-18

record and replay functionality: on a live execution, the amount of compute resources needed to identify and halt on every memory access and inspect...and iteratively, running a replay of the previously gathered recording over and over to construct a deeper understanding of the important aspects of...system events happen during the replay . A second analysis pass over the replay might focus in on the activity of a particular program or a portion of the

Shear sensing based on a microstrip patch antenna

NASA Astrophysics Data System (ADS)

Mohammad, I.; Huang, H.

2012-10-01

A microstrip patch antenna sensor was studied for shear sensing with a targeted application of measuring plantar shear distribution on a diabetic foot. The antenna shear sensor consists of three components, namely an antenna patch, a soft foam substrate and a slotted ground plane. The resonant frequency of the antenna sensor is sensitive to the overlapping length between the slot in the ground plane and the antenna patch. A shear force applied along the direction of the slot deforms the foam substrate and causes a change in the overlapping length, which can be detected from the antenna frequency shift. The antenna shear sensor was designed based on simulated antenna frequency response and validated by experiments. Experimental results indicated that the antenna sensor exhibits high sensitivity to shear deformation and responds to the applied shear loads with excellent linearity and repeatability.

Resuscitation skills after Helping Babies Breathe training: a comparison of varying practice frequency and impact on retention of skills in different types of providers.

PubMed

Tabangin, M E; Josyula, S; Taylor, K K; Vasquez, J C; Kamath-Rayne, B D

2018-05-01

Helping Babies Breathe (HBB), a basic neonatal resuscitation curriculum, improves early neonatal mortality in low-resource settings. Our goal was to determine retention of resuscitation skills by different cadres of providers using the approved HBB Spanish translation in a rural clinic and community hospital in Honduras. Twelve clinic and 37 hospital providers were trained in 1 d HBB workshops and followed from July 2012 to February 2014. Resuscitation skills were evaluated by objective structured clinical evaluations (OSCEs) at regular intervals. Clinic providers practiced monthly, whereas hospital providers were randomized to monthly practice for 6 months vs three consecutive practices at 3, 5 and 6 months. In the rural clinic, follow-up OSCE assessment showed rapid loss of skills by 1 month after HBB training. For all providers, repeated monthly testing resulted in improvements and maintenance of OSCE performance. In the community hospital, over all time points, the group with monthly OSCEs had 2.9 greater odds of passing compared with the group who practiced less frequently. Physicians were found to have 4.3 times greater odds of passing compared with nurses. Rapid loss of resuscitation skills occurs after an initial training. Repeated practice leads to retention of skills in all types of providers. Further investigation is warranted to determine the clinical correlation of neonatal outcomes after HBB training.

Computed Intranasal Spray Penetration: Comparisons Before and After Nasal Surgery

PubMed Central

Frank, Dennis O.; Kimbell, Julia S.; Cannon, Daniel; Rhee, John S.

2012-01-01

Background Quantitative methods for comparing intranasal drug delivery efficiencies pre- and postoperatively have not been fully utilized. The objective of this study is to use computational fluid dynamics techniques to evaluate aqueous nasal spray penetration efficiencies before and after surgical correction of intranasal anatomic deformities. Methods Ten three-dimensional models of the nasal cavities were created from pre- and postoperative computed tomography scans in five subjects. Spray simulations were conducted using a particle size distribution ranging from 10–110μm, a spray speed of 3m/s, plume angle of 68°, and with steady state, resting inspiratory airflow present. Two different nozzle positions were compared. Statistical analysis was conducted using Student T-test for matched pairs. Results On the obstructed side, posterior particle deposition after surgery increased by 118% and was statistically significant (p-value=0.036), while anterior particle deposition decreased by 13% and was also statistically significant (p-value=0.020). The fraction of particles that by-passed the airways either pre- or post-operatively was less than 5%. Posterior particle deposition differences between obstructed and contralateral sides of the airways were 113% and 30% for pre- and post-surgery, respectively. Results showed that nozzle positions can influence spray delivery. Conclusions Simulations predicted that surgical correction of nasal anatomic deformities can improve spray penetration to areas where medications can have greater effect. Particle deposition patterns between both sides of the airways are more evenly distributed after surgery. These findings suggest that correcting anatomic deformities may improve intranasal medication delivery. For enhanced particle penetration, patients with nasal deformities may explore different nozzle positions. PMID:22927179

The reliability of the pass/fail decision for assessments comprised of multiple components.

PubMed

Möltner, Andreas; Tımbıl, Sevgi; Jünger, Jana

2015-01-01

The decision having the most serious consequences for a student taking an assessment is the one to pass or fail that student. For this reason, the reliability of the pass/fail decision must be determined for high quality assessments, just as the measurement reliability of the point values. Assessments in a particular subject (graded course credit) are often composed of multiple components that must be passed independently of each other. When "conjunctively" combining separate pass/fail decisions, as with other complex decision rules for passing, adequate methods of analysis are necessary for estimating the accuracy and consistency of these classifications. To date, very few papers have addressed this issue; a generally applicable procedure was published by Douglas and Mislevy in 2010. Using the example of an assessment comprised of several parts that must be passed separately, this study analyzes the reliability underlying the decision to pass or fail students and discusses the impact of an improved method for identifying those who do not fulfill the minimum requirements. The accuracy and consistency of the decision to pass or fail an examinee in the subject cluster Internal Medicine/General Medicine/Clinical Chemistry at the University of Heidelberg's Faculty of Medicine was investigated. This cluster requires students to separately pass three components (two written exams and an OSCE), whereby students may reattempt to pass each component twice. Our analysis was carried out using the method described by Douglas and Mislevy. Frequently, when complex logical connections exist between the individual pass/fail decisions in the case of low failure rates, only a very low reliability for the overall decision to grant graded course credit can be achieved, even if high reliabilities exist for the various components. For the example analyzed here, the classification accuracy and consistency when conjunctively combining the three individual parts is relatively low with κ=0.49 or κ=0.47, despite the good reliability of over 0.75 for each of the three components. The option to repeat each component twice leads to a situation in which only about half of the candidates who do not satisfy the minimum requirements would fail the overall assessment, while the other half is able to continue their studies despite having deficient knowledge and skills. The method put forth by Douglas and Mislevy allows the analysis of the decision accuracy and consistency for complex combinations of scores from different components. Even in the case of highly reliable components, it is not necessarily so that a reliable pass/fail decision has been reached - for instance in the case of low failure rates. Assessments must be administered with the explicit goal of identifying examinees that do not fulfill the minimum requirements.

The reliability of the pass/fail decision for assessments comprised of multiple components

PubMed Central

Möltner, Andreas; Tımbıl, Sevgi; Jünger, Jana

2015-01-01

Objective: The decision having the most serious consequences for a student taking an assessment is the one to pass or fail that student. For this reason, the reliability of the pass/fail decision must be determined for high quality assessments, just as the measurement reliability of the point values. Assessments in a particular subject (graded course credit) are often composed of multiple components that must be passed independently of each other. When “conjunctively” combining separate pass/fail decisions, as with other complex decision rules for passing, adequate methods of analysis are necessary for estimating the accuracy and consistency of these classifications. To date, very few papers have addressed this issue; a generally applicable procedure was published by Douglas and Mislevy in 2010. Using the example of an assessment comprised of several parts that must be passed separately, this study analyzes the reliability underlying the decision to pass or fail students and discusses the impact of an improved method for identifying those who do not fulfill the minimum requirements. Method: The accuracy and consistency of the decision to pass or fail an examinee in the subject cluster Internal Medicine/General Medicine/Clinical Chemistry at the University of Heidelberg’s Faculty of Medicine was investigated. This cluster requires students to separately pass three components (two written exams and an OSCE), whereby students may reattempt to pass each component twice. Our analysis was carried out using the method described by Douglas and Mislevy. Results: Frequently, when complex logical connections exist between the individual pass/fail decisions in the case of low failure rates, only a very low reliability for the overall decision to grant graded course credit can be achieved, even if high reliabilities exist for the various components. For the example analyzed here, the classification accuracy and consistency when conjunctively combining the three individual parts is relatively low with κ=0.49 or κ=0.47, despite the good reliability of over 0.75 for each of the three components. The option to repeat each component twice leads to a situation in which only about half of the candidates who do not satisfy the minimum requirements would fail the overall assessment, while the other half is able to continue their studies despite having deficient knowledge and skills. Conclusion: The method put forth by Douglas and Mislevy allows the analysis of the decision accuracy and consistency for complex combinations of scores from different components. Even in the case of highly reliable components, it is not necessarily so that a reliable pass/fail decision has been reached – for instance in the case of low failure rates. Assessments must be administered with the explicit goal of identifying examinees that do not fulfill the minimum requirements. PMID:26483855

Spatiotemporal variation in the postseismic deformation of the 2011 Tohoku-oki earthquake revealed by seafloor geodetic observations

NASA Astrophysics Data System (ADS)

Tomita, F.; Kido, M.; Ohta, Y.; Hino, R.; Iinuma, T.

2016-12-01

Postseismic deformation following the 2011 Tohoku-oki earthquake has been detected by on- and off-shore geodetic observations. GPS/Acoustic (GPS/A) observations [Watanabe et al., 2014, GRL] just above the coseismic primary rupture area (PRA) show significant landward movement in contrast to the trench-ward movement of the on-shore GPS observations, which can be generally explained by viscoelastic relaxation [Sun et al., 2014, Nature]. Furthermore, Tomita et al. [2015, AGU] demonstrated along-trench variation of the postseismic deformation also using GPS/A observations. In this study, we show detailed spatiotemporal characteristics of the postseismic deformation using updated GPS/A measurement results. We employed 20 GPS/A sites located in Tohoku-oki region and had conducted repeated campaign surveys from Sep. 2012 to May 2016. GPS/A positioning was performed using the method of Kido et al. [2006, EPS]. Then, we calculated postseismic displacement rates by applying a weighted robust linear fitting. The updated results of the postseismic displacement rates are consistent with the characteristic revealed by Tomita et al. [2015] but are estimated with better precision ( 2 cm/yr in 1σ). The sites in the north region of PRA show slight trenchward movement (< 5 cm/yr), while the sites in the south region of PRA show significant trenchward movement (5-15 cm/yr) indicating dominance of the afterslip effects. Moreover, the sites above PRA show significant landward movement (10-15 cm/yr) indicating viscoelastic relaxation and interplate relocking effects. Furthermore, the updated results may show temporal decay of afterslip; the temporally decaying displacements have been observed in the south region of PRA. However, such a temporal decay has not been measured in the region where viscoelastic relaxation causes significant deformation. In the presentation, we will discuss detail spatiotemporal evolution of the postseismic deformation processes from the updated results by comparing with other geodetic observations and studies on the postseismic deformation modeling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Y; Turian, J; Templeton, A

Purpose: PET/CT provides important functional information for radiotherapy targeting of cervical cancer. However, repeated PET/CT procedures for external beam and subsequent brachytherapy expose patients to additional radiation and are not cost effective. Our goal is to investigate the possibility of propagating PET-active volumes for brachytherapy procedures through deformable image registration (DIR) of earlier PET/CT and ultimately to minimize the number of PET/CT image sessions required. Methods: Nine cervical cancer patients each received their brachytherapy preplanning PET/CT at the end of EBRT with a Syed template in place. The planning PET/CT was acquired on the day of brachytherapy treatment with themore » actual applicator (Syed or Tandem and Ring) and rigidly registered. The PET/CT images were then deformably registered creating a third (deformed) image set for target prediction. Regions of interest with standardized uptake values (SUV) greater than 65% of maximum SUV were contoured as target volumes in all three sets of PET images. The predictive value of the registered images was evaluated by comparing the preplanning and deformed PET volumes with the planning PET volume using Dice's coefficient (DC) and center-of-mass (COM) displacement. Results: The average DCs were 0.12±0.14 and 0.19±0.16 for rigid and deformable predicted target volumes, respectively. The average COM displacements were 1.9±0.9 cm and 1.7±0.7 cm for rigid and deformable registration, respectively. The DCs were improved by deformable registration, however, both were lower than published data for DIR in other modalities and clinical sites. Anatomical changes caused by different brachytherapy applicators could have posed a challenge to the DIR algorithm. The physiological change from interstitial needle placement may also contribute to lower DC. Conclusion: The clinical use of DIR in PET/CT for cervical cancer brachytherapy appears to be limited by applicator choice and requires further investigation.« less

Interactive deformation registration of endorectal prostate MRI using ITK thin plate splines.

PubMed

Cheung, M Rex; Krishnan, Karthik

2009-03-01

Magnetic resonance imaging with an endorectal coil allows high-resolution imaging of prostate cancer and the surrounding normal organs. These anatomic details can be used to direct radiotherapy. However, organ deformation introduced by the endorectal coil makes it difficult to register magnetic resonance images for treatment planning. In this study, plug-ins for the volume visualization software VolView were implemented on the basis of algorithms from the National Library of Medicine's Insight Segmentation and Registration Toolkit (ITK). Magnetic resonance images of a phantom simulating human pelvic structures were obtained with and without the endorectal coil balloon inflated. The prostate not deformed by the endorectal balloon was registered to the deformed prostate using an ITK thin plate spline (TPS). This plug-in allows the use of crop planes to limit the deformable registration in the region of interest around the prostate. These crop planes restricted the support of the TPS to the area around the prostate, where most of the deformation occurred. The region outside the crop planes was anchored by grid points. The TPS was more accurate in registering the local deformation of the prostate compared with a TPS variant, the elastic body spline. The TPS was also applied to register an in vivo T(2)-weighted endorectal magnetic resonance image. The intraprostatic tumor was accurately registered. This could potentially guide the boosting of intraprostatic targets. The source and target landmarks were placed graphically. This TPS plug-in allows the registration to be undone. The landmarks could be added, removed, and adjusted in real time and in three dimensions between repeated registrations. This interactive TPS plug-in allows a user to obtain a high level of accuracy satisfactory to a specific application efficiently. Because it is open-source software, the imaging community will be able to validate and improve the algorithm.

Retention and wear behaviors of two implant overdenture stud-type attachments at different implant angulations.

PubMed

Choi, Jae-Won; Bae, Ji-Hyeon; Jeong, Chang-Mo; Huh, Jung-Bo

2017-05-01

Implant angulation should be considered when selecting an attachment. Some in vitro studies have investigated the relationship between implant angulation and changes in the retention force of the stud attachment, but few studies have evaluated the effect of cyclic loading and repeated cycles of insertion and removal on the stud attachment. The purpose of this in vitro study was to evaluate the effects of implant angulation on the retentive characteristics of overdentures with 2 different stud attachments, an experimental system and O-rings in red and orange, after cyclic loading and repeated insertion and removal cycles. The canine region of a mandibular experimental model was fitted with 2 implant fixtures with 2 different stud attachment systems at implant angulations of 0, 15, or 30 degrees. A mastication simulator was used to simulate cyclic loading, and a universal testing machine was used to evaluate retentive force changes after repeated insertion and removal cycles. To simulate the numbers of mastication and insertion and removal cycles per annum, 400000 cyclic loadings and 1080 insertion and removal cycles were performed. Wear patterns and attachment surface deformations were evaluated by scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction (α=.05/3=.017), and the paired-sample Student t test (α=.05). When retentive forces before and after testing were compared, O-ring showed significant retention loss at all implant angulations (P<.001). In contrast, the experimental system showed little retention loss in the 0- and 15-degree models (P>.05), whereas the 30-degree model showed a significant increase in retentive force (P=.001). At all implant angulations, retention loss increased significantly for the orange O-ring, followed by the red O-ring, and the experimental system (P<.001). Scanning electron microscopy analysis showed more intense wear in the matrix than the patrix (abutment that matches to matrix) and more severe wear and deformation of the O-ring rubber matrix than of the experimental zirconia ball. Upon completion of the experiment, wear and deformation were found for all attachment systems. Even when implants are not installed in parallel, the experimental system can be used without involving great loss of retention. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Deformation history of Mauna Loa (Hawaii) from 2003 to 2014 through InSAR data: understanding the shorter-term processes

NASA Astrophysics Data System (ADS)

La Marra, Daniele; Poland, Michael P.; Acocella, Valerio; Battaglia, Maurizio; Miklius, Asta

2016-04-01

Geodesy allows detecting the deformation of volcanoes, thus understanding magmatic processes. This becomes particularly efficient when time series are available and volcanoes can be monitored on the mean-term (decades), and not only during a specific event. Here we exploit the SBAS technique, using SAR images from ENVISAT (descending and ascending orbits; 2003 - 2010) and COSMO-SkyMed (descending and ascending orbits; 2012 - 2014), to study a decade of deformation at Mauna Loa (Hawaii). These data are merged time series data from 24 continuously operating GPS stations, which allows us to calibrate the InSAR time series. Our results show a long-term inflation of the volcano from 2003 to 2014, reaching a peak of ~11 cm/yr on the summit area between mid-2004 to mid-2005 and then slowing down. Within this frame, we were able to identify five main periods with approximately linear deformation behavior. The inversion of the deformation data in the first four periods suggests the repeated, though not constant, intrusion of one or more dikes below the summit caldera and the upper Southwest Rift Zone. Moreover, the dike intrusion coincides with minor acceleration of flank slip. Such a behavior is distinctive and, with the exception of the nearby Kilauea, has not been observed at any other volcano on the mean term. It is proposed that continuous, even though not constant flank instability of the SE flank may promote semi-continuous intrusions in a volcano with a ready magma supply.

Large-scale glacitectonic deformation in response to active ice sheet retreat across Dogger Bank (southern central North Sea) during the Last Glacial Maximum

NASA Astrophysics Data System (ADS)

Phillips, Emrys; Cotterill, Carol; Johnson, Kirstin; Crombie, Kirstin; James, Leo; Carr, Simon; Ruiter, Astrid

2018-01-01

High resolution seismic data from the Dogger Bank in the central southern North Sea has revealed that the Dogger Bank Formation records a complex history of sedimentation and penecontemporaneous, large-scale, ice-marginal to proglacial glacitectonic deformation. These processes led to the development of a large thrust-block moraine complex which is buried beneath a thin sequence of Holocene sediments. This buried glacitectonic landsystem comprises a series of elongate, arcuate moraine ridges (200 m up to > 15 km across; over 40-50 km long) separated by low-lying ice marginal to proglacial sedimentary basins and/or meltwater channels, preserving the shape of the margin of this former ice sheet. The moraines are composed of highly deformed (folded and thrust) Dogger Bank Formation with the lower boundary of the deformed sequence (up to 40-50 m thick) being marked by a laterally extensive décollement. The ice-distal parts of the thrust moraine complex are interpreted as a "forward" propagating imbricate thrust stack developed in response to S/SE-directed ice-push. The more complex folding and thrusting within the more ice-proximal parts of the thrust-block moraines record the accretion of thrust slices of highly deformed sediment as the ice repeatedly reoccupied this ice marginal position. Consequently, the internal structure of the Dogger Bank thrust-moraine complexes can be directly related to ice sheet dynamics, recording the former positions of a highly dynamic, oscillating Weichselian ice sheet margin as it retreated northwards at the end of the Last Glacial Maximum.

Lumbar annulus fibrosus biomechanical characterization in healthy children by ultrasound shear wave elastography.

PubMed

Vergari, Claudio; Dubois, Guillaume; Vialle, Raphael; Gennisson, Jean-Luc; Tanter, Mickael; Dubousset, Jean; Rouch, Philippe; Skalli, Wafa

2016-04-01

Intervertebral disc (IVD) is key to spine biomechanics, and it is often involved in the cascade leading to spinal deformities such as idiopathic scoliosis, especially during the growth spurt. Recent progress in elastography techniques allows access to non-invasive measurement of cervical IVD in adults; the aim of this study was to determine the feasibility and reliability of shear wave elastography in healthy children lumbar IVD. Elastography measurements were performed in 31 healthy children (6-17 years old), in the annulus fibrosus and in the transverse plane of L5-S1 or L4-L5 IVD. Reliability was determined by three experienced operators repeating measurements. Average shear wave speed in IVD was 2.9 ± 0.5 m/s; no significant correlations were observed with sex, age or body morphology. Intra-operator repeatability was 5.0 % while inter-operator reproducibility was 6.2 %. Intraclass correlation coefficient was higher than 0.9 for each operator. Feasibility and reliability of IVD shear wave elastography were demonstrated. The measurement protocol is compatible with clinical routine and the results show the method's potential to give an insight into spine deformity progression and early detection. • Intervertebral disc mechanical properties are key to spine biomechanics • Feasibility of shear wave elastography in children lumbar disc was assessed • Measurement was fast and reliable • Elastography could represent a novel biomarker for spine pathologies.

Effect of Multi-Pass Ultrasonic Surface Rolling on the Mechanical and Fatigue Properties of HIP Ti-6Al-4V Alloy

PubMed Central

Li, Gang; Qu, Shengguan; Xie, Mingxin; Ren, Zhaojun; Li, Xiaoqiang

2017-01-01

The main purpose of this paper was to investigate the effect of a surface plastic deformation layer introduced by multi-pass ultrasonic surface rolling (MUSR) on the mechanical and fatigue properties of HIP Ti-6Al-4V alloys. Some microscopic analysis methods (SEM, TEM and XRD) were used to characterize the modified microstructure in the material surface layer. The results indicated that the material surface layer experienced a certain extent plastic deformation, accompanied by some dense dislocations and twin generation. Moreover, surface microhardness, residual stress and roughness values of samples treated by MUSR were also greatly improved compared with that of untreated samples. Surface microhardness and compressive residual stress were increased to 435 HV and −1173 MPa, respectively. The minimum surface roughness was reduced to 0.13 μm. The maximum depth of the surface hardening layer was about 55 μm. However, the practical influence depth was about 450 μm judging from the tensile and fatigue fracture surfaces. The ultimate tensile strength of the MUSR-treated sample increased to 990 MPa from the initial 963 MPa. The fatigue strength of the MUSR-treated sample was increased by about 25% on the base of 107 cycles, and the lifetime was prolonged from two times to two orders of magnitude at the applied stress amplitudes of 650–560 MPa. The improved mechanical and fatigue properties of MUSR-treated samples should be attributed to the combined effects of the increased microhardness and compressive residual stress, low surface roughness, grain refinement and micro-pore healing in the material surface-modified layer. PMID:28772494

Energy harvesting from controlled buckling of piezoelectric beams

NASA Astrophysics Data System (ADS)

Ansari, M. H.; Karami, M. Amin

2015-11-01

A piezoelectric vibration energy harvester is presented that can generate electricity from the weight of passing cars or crowds. The energy harvester consists of a piezoelectric beam, which buckles when the device is stepped on. The energy harvester can have a horizontal or vertical configuration. In the vertical (direct) configuration, the piezoelectric beam is vertical and directly sustains the weight of the vehicles or people. In the horizontal (indirect) configuration, the vertical weight is transferred to a horizontal axial force through a scissor-like mechanism. Buckling of the beam results in significant stresses and, thus, large power production. However, if the beam’s buckling is not controlled, the beam will fracture. To prevent this, the axial deformation is constrained to limit the deformations of the beam. In this paper, the energy harvester is analytically modeled. The considered piezoelectric beam is a general non-uniform beam. The natural frequencies, mode shapes, and the critical buckling force corresponding to each mode shape are calculated. The electro-mechanical coupling and the geometric nonlinearities are included in the model. The design criteria for the device are discussed. It is demonstrated that a device, realized with commonly used piezoelectric patches, can generate tens of milliwatts of power from passing car traffic. The proposed device could also be implemented in the sidewalks or integrated in shoe soles for energy generation. One of the key features of the device is its frequency up-conversion characteristics. The piezoelectric beam undergoes free vibrations each time the weight is applied to or removed from the energy harvester. The frequency of the free vibrations is orders of magnitude larger than the frequency of the load. The device is, thus, both efficient and insensitive to the frequency of the force excitations.

Decorrelation of L-band and C-band interferometry to volcanic risk prevention

NASA Astrophysics Data System (ADS)

Malinverni, E. S.; Sandwell, D.; Tassetti, A. N.; Cappelletti, L.

2013-10-01

SAR has several strong key features: fine spatial resolution/precision and high temporal pass frequency. Moreover, the InSAR technique allows the accurate detection of ground deformations. This high potential technology can be invaluable to study volcanoes: it provides important information on pre-eruption surface deformation, improving the understanding of volcanic processes and the ability to predict eruptions. As a downside, SAR measurements are influenced by artifacts such as atmospheric effects or bad topographic data. Correlation gives a measure of these interferences, quantifying the similarity of the phase of two SAR images. Different approaches exists to reduce these errors but the main concern remain the possibility to correlate images with different acquisition times: snow-covered or heavily-vegetated areas produce seasonal changes on the surface. Minimizing the time between passes partly limits decorrelation. Though, images with a short temporal baseline aren't always available and some artifacts affecting correlation are timeindependent. This work studies correlation of pairs of SAR images focusing on the influence of surface and climate conditions, especially snow coverage and temperature. Furthermore, the effects of the acquisition band on correlation are taken into account, comparing L-band and C-band images. All the chosen images cover most of the Yellowstone caldera (USA) over a span of 4 years, sampling all the seasons. Interferograms and correlation maps are generated. To isolate temporal decorrelation, pairs of images with the shortest baseline are chosen. Correlation maps are analyzed in relation to snow depth and temperature. Results obtained with ENVISAT and ERS satellites (C-band) are compared with the ones from ALOS (L-band). Results show a good performance during winter and a bad attitude towards wet snow (spring and fall). During summer both L-band and C-band maintain a good coherence with L-band performing better over vegetation.

Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

NASA Astrophysics Data System (ADS)

Rahimi, S.; Wynne, B. P.; Baker, T. N.

2017-01-01

The evolution of microstructure and crystallographic texture has been investigated in double-sided friction stir welded microalloyed steel, using electron backscatter diffraction (EBSD). The microstructure analyses show that the center of stirred zone reached a temperature between Ac1 and Ac3 during FSW, resulting in a dual-phase austenitic/ ferritic microstructure. The temperatures in the thermo-mechanically affected zone and the overlapped area between the first and second weld pass did not exceed the Ac1. The shear generated by the rotation probe occurs in austenitic/ferritic phase field where the austenite portion of the microstructure is transformed to a bainitic ferrite, on cooling. Analysis of crystallographic textures with regard to shear flow lines generated by the probe tool shows the dominance of simple shear components across the whole weld. The austenite texture at Ac1 - Ac3 is dominated by the B { {1bar{1}2} }< 110rangle and bar{B} { {bar{1}1bar{2}} }< bar{1}bar{1}0rangle simple shear texture components, where the bainite phase textures formed on cooling were inherited from the shear textures of the austenite phase with relatively strong variant selection. The ferrite portion of the stirred zone and the ferrites in the thermo-mechanically affected zones and the overlapped area underwent shear deformation with textures dominated by the D1 { {bar{1}bar{1}2} }< 111rangle and D2 { {11bar{2}} }< 111rangle simple shear texture components. The formation of ultrafine equiaxed ferrite with submicron grain size has been observed in the overlapped area between the first and second weld pass. This is due to continuous dynamic strain-induced recrystallization as a result of simultaneous severe shear deformation and drastic undercooling.

Low gene copy number shows that arbuscular mycorrhizal fungi inherit genetically different nuclei.

PubMed

Hijri, Mohamed; Sanders, Ian R

2005-01-13

Arbuscular mycorrhizal fungi (AMF) are ancient asexually reproducing organisms that form symbioses with the majority of plant species, improving plant nutrition and promoting plant diversity. Little is known about the evolution or organization of the genomes of any eukaryotic symbiont or ancient asexual organism. Direct evidence shows that one AMF species is heterokaryotic; that is, containing populations of genetically different nuclei. It has been suggested, however, that the genetic variation passed from generation to generation in AMF is simply due to multiple chromosome sets (that is, high ploidy). Here we show that previously documented genetic variation in Pol-like sequences, which are passed from generation to generation, cannot be due to either high ploidy or repeated gene duplications. Our results provide the clearest evidence so far for substantial genetic differences among nuclei in AMF. We also show that even AMF with a very large nuclear DNA content are haploid. An underlying principle of evolutionary theory is that an individual passes on one or half of its genome to each of its progeny. The coexistence of a population of many genomes in AMF and their transfer to subsequent generations, therefore, has far-reaching consequences for understanding genome evolution.

Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

NASA Astrophysics Data System (ADS)

McCann, Ronán; Bagga, Komal; Groarke, Robert; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot

2016-11-01

This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

Comparing Student Performance on the Old vs New Versions of the NAPLEX.

PubMed

Welch, Adam C; Karpen, Samuel C

2018-04-01

Objective. To determine if the new 2016 version of the North American Pharmacy Licensure Examination (NAPLEX) affected scores when controlling for student performance on other measures using data from one institution. Methods. There were 201 records from the classes of 2014-2016. Doubly robust estimation using weighted propensity scores was used to compare NAPLEX scaled scores and pass rates while considering student performance on other measures. Of the potential controllers of student performance: Pharmacy Curricular Outcomes Assessment (PCOA), scaled composite scores from the Pharmacy College Admission Test (PCAT), and P3 Grade Point Average (GPA). Only PCOA and P3 GPA were found to be appropriate for propensity scoring. Results. The weighted NAPLEX scaled scores did not significantly drop from the old (2014-2015) to the new (2016) version of NAPLEX. The change in pass rates between the new and old versions of NAPLEX were also non-significant. Conclusion. Using data from one institution, the new version itself of the NAPLEX did not have a significant effect on NAPLEX scores or first-time pass rates when controlling for student performance on other measures. Colleges are encouraged to repeat this analysis with pooled data and larger sample sizes.

Short pulse free electron laser amplifier

DOEpatents

Schlitt, Leland G.; Szoke, Abraham

1985-01-01

Method and apparatus for amplification of a laser pulse in a free electron laser amplifier where the laser pulse duration may be a small fraction of the electron beam pulse duration used for amplification. An electron beam pulse is passed through a first wiggler magnet and a short laser pulse to be amplified is passed through the same wiggler so that only the energy of the last fraction, f, (f<1) of the electron beam pulse is consumed in amplifying the laser pulse. After suitable delay of the electron beam, the process is repeated in a second wiggler magnet, a third, . . . , where substantially the same fraction f of the remainder of the electron beam pulse is consumed in amplification of the given short laser pulse in each wiggler magnet region until the useful electron beam energy is substantially completely consumed by amplification of the laser pulse.

A new maximum-likelihood change estimator for two-pass SAR coherent change detection

DOE PAGES

Wahl, Daniel E.; Yocky, David A.; Jakowatz, Jr., Charles V.; ...

2016-01-11

In previous research, two-pass repeat-geometry synthetic aperture radar (SAR) coherent change detection (CCD) predominantly utilized the sample degree of coherence as a measure of the temporal change occurring between two complex-valued image collects. Previous coherence-based CCD approaches tend to show temporal change when there is none in areas of the image that have a low clutter-to-noise power ratio. Instead of employing the sample coherence magnitude as a change metric, in this paper, we derive a new maximum-likelihood (ML) temporal change estimate—the complex reflectance change detection (CRCD) metric to be used for SAR coherent temporal change detection. The new CRCD estimatormore » is a surprisingly simple expression, easy to implement, and optimal in the ML sense. As a result, this new estimate produces improved results in the coherent pair collects that we have tested.« less

Porous siliconformation and etching process for use in silicon micromachining

DOEpatents

Guilinger, Terry R.; Kelly, Michael J.; Martin, Jr., Samuel B.; Stevenson, Joel O.; Tsao, Sylvia S.

1991-01-01

A reproducible process for uniformly etching silicon from a series of micromechanical structures used in electrical devices and the like includes providing a micromechanical structure having a silicon layer with defined areas for removal thereon and an electrochemical cell containing an aqueous hydrofluoric acid electrolyte. The micromechanical structure is submerged in the electrochemical cell and the defined areas of the silicon layer thereon are anodically biased by passing a current through the electrochemical cell for a time period sufficient to cause the defined areas of the silicon layer to become porous. The formation of the depth of the porous silicon is regulated by controlling the amount of current passing through the electrochemical cell. The micromechanical structure is then removed from the electrochemical cell and submerged in a hydroxide solution to remove the porous silicon. The process is subsequently repeated for each of the series of micromechanical structures to achieve a reproducibility better than 0.3%.

The GOAL-to-HAL/S translator specification. [for space shuttle

NASA Technical Reports Server (NTRS)

Stanten, S. F.; Flanders, J. H.

1973-01-01

The specification sets forth a technical framework within which to deal with the transfer of specific GOAL features to HAL/S. Key technical features of the translator are described which communicate with the data bank, handle repeat statements, and deal with software interrupts. GOAL programs, databank information, and GOAL system subroutines are integrated into one GOAL in HAL/S. This output is fully compatible HAL/S source ready for insertion into the HAL/S compiler. The Translator uses a PASS1 to establish all the global data needed for the HAL/S output program. Individual GOAL statements are translated in PASS2. The specification document makes extensive use of flowcharts to specify exactly how each variation of each GOAL statement is to be translated. The specification also deals with definitions and assumptions, executive support structure and implementation. An appendix, entitled GOAL-to-HAL Mapping, provides examples of translated GOAL statements.

Gulf Coast Subsidence: Integration of Geodesy, Geophysical Modeling, and Interferometric Synthetic Aperture Radar Observations

NASA Astrophysics Data System (ADS)

Blom, R. G.; Chapman, B. D.; Deese, R.; Dokka, R. K.; Fielding, E. J.; Hawkins, B.; Hensley, S.; Ivins, E. R.; Jones, C. E.; Kent, J. D.; Liu, Z.; Lohman, R.; Zheng, Y.

2012-12-01

The vulnerability of the US Gulf Coast has received increased attention in the years since hurricanes Katrina and Rita. Agencies responsible for the long-term protection of lives and infrastructure require precise estimates of future subsidence and sea level rise. A quantitative, geophysically based methodology can provide such estimates by incorporating geological data, geodetic measurements, geophysical models of non-elastic mechanical behavior at depth, and geographically comprehensive deformation monitoring made possible with measurements from Interferometric Synthetic Aperture Radar (InSAR). To be effective, results must be available to user agencies in a format suitable for integration within existing decision-support processes. Work to date has included analysis of historical and continuing ground-based geodetic measurements. These reveal a surprising degree of complexity, including regions that are subsiding at rates faster than those considered for hurricane protection planning of New Orleans and other coastal communities (http://www.mvn.usace.army.mil/pdf/hps_verticalsettlement.pdf) as well as Louisiana's coastal restoration strategies (http://www.coast2050.gov/2050reports.htm) (Dokka, 2011, J. Geophys. Res., 116, B06403, doi:10.1029/2010JB008008). Traditional geodetic measurements provide precise information at single points, while InSAR observations provide geographically comprehensive measurements of surface deformation at lower vertical precision. Available InSAR data sources include X-, C- and L-band satellite, and NASA/JPL airborne UAVSAR L-band data. The Gulf Coast environment is very challenging for InSAR techniques, especially with systems not designed for interferometry. For example, the shorter wavelength C-band data decorrelates over short time periods requiring more elaborate time-series analysis techniques, with which we've had some success. Meanwhile, preliminary analysis of limited L-Band ALOS/PALSAR satellite data show promise; unfortunately this Japanese satellite system failed in April 2011. We now have multiple airborne UAVSAR repeat pass interferometry data sets under analysis (http://uavsar.jpl.nasa.gov/) . UAVSAR interferogram processing has proven problematic in this environment, and new acquisitions are planned at shorter temporal intervals to yield improved results. Combining the geodetic and InSAR data can constrain geophysical models of crustal behavior, leading to quantitative predictions of future subsidence. Model results to date show good agreement between geodetic measurements and geophysically reasonable parameters including sediment load and ~130 m post-glacial sea level rise. We review work to date and present newly acquired UAVSAR data.

Investigation of Lithospheric Structure in Mongolia: Insights from Insar Observations and Modelling

NASA Astrophysics Data System (ADS)

Jing, Z.; Bihong, F.; Pilong, S.; Qiang, G.

2017-09-01

The western Mongolia is a seismically active intracontinental region, with ongoing tectonic deformation and widespread seismicity related to the far-field effects of India-Eurasia collision. During the 20th century, four earthquakes with the magnitude larger than 8 occurred in the western Mongolia and its surrounding regions, providing a unique opportunity to study the geodynamics of intracontinental tectonic deformations. The 1957 magnitude 8.3 Gobi-Altai earthquake is one of the largest seismic events. The deformation pattern of rupture zone associated with this earthquake is complex, involving left-lateral strike-slip and reverse dip-slip faulting on several distinct geological structures in a 264 × 40 km wide zone. To understand the relationship between the observed postseismic surface deformation and the rheological structure of the upper lithosphere, Interferometric Synthetic Aperture Radar (InSAR) data are used to study the 1957 earthquake. Then we developed a postseismic model in a spherical, radially layered elastic-viscoelastic Earth based on InSAR results, and further analysed the dominant contribution to the surface deformation. This work is important for understanding not only the regional tectonics, but also the structure and dynamics of the lithosphere. SAR data were acquired from the ERS1/2 and Envisat from 1996 to 2010. Using the Repeat Orbit Interferometry Package (ROI_PAC), 124 postseismic interferograms are produced on four adjacent tracks. By stacking these interferograms, the maximum InSAR line-of-sight deformation rate along the Gobi-Altai fault zone is obtained. The main results are as follows: (1) The maximum InSAR line-of-sight deformation velocity along this large fault zone is about 6 mm/yr; (2) The modelled surface deformation suggests that the viscoelastic relaxation is the most reasonable mechanism to explain the observed surface motion; (3) The optimal model cover the Gobi-Altai seismogenic thickness is 10 km; (4) The lower bound of Maxwell viscosity of lower crust and upper mantle is approximately 9 × 1019 Pa s, and the Maxwell relaxation time corresponding to this viscosity is 95.13 years.

Noise in two-color electronic distance meter measurements revisited

USGS Publications Warehouse

Langbein, J.

2004-01-01

Frequent, high-precision geodetic data have temporally correlated errors. Temporal correlations directly affect both the estimate of rate and its standard error; the rate of deformation is a key product from geodetic measurements made in tectonically active areas. Various models of temporally correlated errors are developed and these provide relations between the power spectral density and the data covariance matrix. These relations are applied to two-color electronic distance meter (EDM) measurements made frequently in California over the past 15-20 years. Previous analysis indicated that these data have significant random walk error. Analysis using the noise models developed here indicates that the random walk model is valid for about 30% of the data. A second 30% of the data can be better modeled with power law noise with a spectral index between 1 and 2, while another 30% of the data can be modeled with a combination of band-pass-filtered plus random walk noise. The remaining 10% of the data can be best modeled as a combination of band-pass-filtered plus power law noise. This band-pass-filtered noise is a product of an annual cycle that leaks into adjacent frequency bands. For time spans of more than 1 year these more complex noise models indicate that the precision in rate estimates is better than that inferred by just the simpler, random walk model of noise.

Wear Behavior and Microstructure of Mg-Sn Alloy Processed by Equal Channel Angular Extrusion

PubMed Central

Chen, Jung-Hsuan; Shen, Yen-Chen; Chao, Chuen-Guang; Liu, Tzeng-Feng

2017-01-01

Mg-5wt.% Sn alloy is often used in portable electronic devices and automobiles. In this study, mechanical properties of Mg-5wt.% Sn alloy processed by Equal Channel Angular Extrusion (ECAE) were characterized. More precisely, its hardness and wear behavior were measured using Vickers hardness test and a pin-on-disc wear test. The microstructures of ECAE-processed Mg-Sn alloys were investigated by scanning electron microscope and X-ray diffraction. ECAE process refined the grain sizes of the Mg-Sn alloy from 117.6 μm (as-cast) to 88.0 μm (one pass), 49.5 μm (two passes) and 24.4 μm (four passes), respectively. Meanwhile, the hardness of the alloy improved significantly. The maximum wear resistance achieved in the present work was around 73.77 m/mm3, which was obtained from the Mg-Sn alloy treated with a one-pass ECAE process with a grain size of 88.0 μm. The wear resistance improvement was caused by the grain size refinement and the precipitate of the second phase, Mg2Sn against the oxidation of the processed alloy. The as-cast Mg-Sn alloy with the larger grain size, i.e., 117.6 μm, underwent wear mechanisms, mainly adhesive wear and abrasive wear. In ECAE-processed Mg-Sn alloy, high internal energy occurred due to the high dislocation density and the stress field produced by the plastic deformation, which led to an increased oxidation rate of the processed alloy during sliding. Therefore, the oxidative wear and a three-body abrasive wear in which the oxide debris acted as the three-body abrasive components became the dominant factors in the wear behavior, and as a result, reduced the wear resistance in the multi-pass ECAE-processed alloy. PMID:29144414

Programmable Iterative Optical Image And Data Processing

NASA Technical Reports Server (NTRS)

Jackson, Deborah J.

1995-01-01

Proposed method of iterative optical image and data processing overcomes limitations imposed by loss of optical power after repeated passes through many optical elements - especially, beam splitters. Involves selective, timed combination of optical wavefront phase conjugation and amplification to regenerate images in real time to compensate for losses in optical iteration loops; timing such that amplification turned on to regenerate desired image, then turned off so as not to regenerate other, undesired images or spurious light propagating through loops from unwanted reflections.

Methods and compositions for removing carbon dioxide from a gaseous mixture

DOEpatents

Li, Jing; Wu, Haohan

2014-06-24

Provided is a method for adsorbing or separating carbon dioxide from a mixture of gases by passing the gas mixture through a porous three-dimensional polymeric coordination compound having a plurality of layers of two-dimensional arrays of repeating structural units, which results in a lower carbon dioxide content in the gas mixture. Thus, this invention provides useful compositions and methods for removal of greenhouse gases, in particular CO.sub.2, from industrial flue gases or from the atmosphere.

Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations

USGS Publications Warehouse

Lu, Zhong; Mann, Dörte; Freymueller, Jeffrey T.; Meyer, David

2000-01-01

ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preemptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by ∼18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by ∼10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was ∼5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km3 and the average thickness of the erupted lava to be ∼7.4 m. Copyright 2000 by the American Geophysical Union.

Quantification of L-band InSAR coherence over volcanic areas using LiDAR and in situ measurements

NASA Astrophysics Data System (ADS)

Arab-Sedze, Melanie; Heggy, Essam; Bretard, Frederic; Berveiller, Daniel; Jacquemoud, Stephane

2014-07-01

Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool to monitor large-scale ground deformation at active volcanoes. However, vegetation and pyroclastic deposits degrade the radar coherence and therefore the measurement of 3-D surface displacements. In this article, we explore the complementarity between ALOS - PALSAR coherence images, airborne LiDAR data and in situ measurements acquired over the Piton de La Fournaise volcano (Reunion Island, France) to determine the sources of errors that may affect repeat-pass InSAR measure- ments. We investigate three types of surfaces: terrains covered with vegetation, lava flows (a'a, pahoehoe or slabby pahoehoe lava flows) and pyroclastic deposits (lapilli). To explain the loss of coherence observed over the Dolomieu crater between 2008 and 2009, we first use laser altimetry data to map topographic variations. The LiDAR intensity, which depends on surface reflectance, also provides ancillary information about the potential sources of coherence loss. In addition, surface roughness and rock dielectric properties of each terrain have been determined in situ to better understand how electromagnetic waves interact with such media: rough and porous surfaces, such as the a'a lava flows, produce a higher coherence loss than smoother surfaces, such as the pahoehoe lava flows. Variations in dielectric properties suggest a higher penetration depth in pyroclasts than in lava flows at L-band frequency. Decorrelation over the lapilli is hence mainly caused by volumetric effects. Finally, a map of LAI (Leaf Area Index) produced using SPOT 5 imagery allows us to quantify the effect of vegeta- tion density: radar coherence is negatively correlated with LAI and is unreliable for values higher than 7.5.

Quantum repeaters using continuous-variable teleportation

NASA Astrophysics Data System (ADS)

Dias, Josephine; Ralph, T. C.

2017-02-01

Quantum optical states are fragile and can become corrupted when passed through a lossy communication channel. Unlike for classical signals, optical amplifiers cannot be used to recover quantum signals. Quantum repeaters have been proposed as a way of reducing errors and hence increasing the range of quantum communications. Current protocols target specific discrete encodings, for example quantum bits encoded on the polarization of single photons. We introduce a more general approach that can reduce the effect of loss on any quantum optical encoding, including those based on continuous variables such as the field amplitudes. We show that in principle the protocol incurs a resource cost that scales polynomially with distance. We analyze the simplest implementation and find that while its range is limited it can still achieve useful improvements in the distance over which quantum entanglement of field amplitudes can be distributed.

Cascaded multiplexed optical link on a telecommunication network for frequency dissemination.

PubMed

Lopez, Olivier; Haboucha, Adil; Kéfélian, Fabien; Jiang, Haifeng; Chanteau, Bruno; Roncin, Vincent; Chardonnet, Christian; Amy-Klein, Anne; Santarelli, Giorgio

2010-08-02

We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 x 10(-15) at one second measurement time and 5 x 10(-20) at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network.

[The Quality Analysis of National Supervising Sampling for Rubella Virus IgM Diagnostic Kits in 2014].

PubMed

Yu, Tina; Qu, Shoufang; Zhang, Xiaoyan; Sun, Nan; Gao, Shangxian; Li, Haining; Huang, Jie

2015-07-01

To evaluate the quality status of rubella virus IgM diagnostic kits by national supervising sampling. Using legal inspection combining with exploratory study, the positive and negative coincidence rate, detection limit and repeatability of kits were verified. The results showed that 15 of 16 batches of kits were qualified using legal inspection, and the passing rate was 93.8%. The unqualified item was negative coincidence rate. In exploratory study, only 11 batches (68.8%) complied with industry standard. The unqualified items were negative coincidence rate, detection limit and repeatability. At present, rubella virus IgM diagnostic Kits have some quality problems in the market. It is recommended that we adopt industry standard and national reference panel in the registration inspection for the future, which will prompt enterprises to improve quality.

Expert videotape analysis and critiquing benefit laparoscopic skills training of urologists.

PubMed

Nakada, Stephen Y; Hedican, Sean P; Bishoff, Jay T; Shichman, Steven J; Wolf, J Stuart

2004-01-01

Teaching laparoscopic skills has become the focus of the latest generation of hands-on laparoscopic courses. Thirty-four practicing urologists, ages 31 to 61 years (mean, 46.6 years) with laparoscopic experience (range, 0 to 200, mean, 27.6 cases), 32 of whom had taken prior American Urological Association (AUA) laparoscopy courses, participated in an AUA-sponsored hands-on laparoscopic skills course over a 2-day period in August 2002 or March 2003. They all took a knowledge assessment examination and performed standardized tasks (rope passing, ring placement, and laparoscopic suturing and knot tying) at the beginning and the end of the course with a videotape analysis and critique. Prior to the repeat-skills assessment, each participant was individually critiqued and instructed based on a videotape review of their initial performance. The urologists also participated in a porcine laboratory and a pelvic trainer session totaling 6 hours between skills assessments. None of the participants had performed significant laparoscopic suturing prior to the course. Using Wilcoxon's signed rank test, the participants improved from a mean of 119.32 seconds to 98.36 seconds with the rope pass (P = 0.0001), and with the ring placement from a mean of 9.70/minute to 12.09/minute (P = 0.0001). All participants had significantly fewer false passes (mean, 9.35 compared with 5.21) during repeat skills assessments (P = 0.0001). Participants improved from 0.54 sutures/minute to 1.22 sutures/ minute following the video critique and practice (P = 0.0001). Degree of laparoscopic experience (number of cases), age of the urologist, and precourse knowledge (examination score) had no significant bearing on results in the initial skills assessment or in the improvement of task time (Spearman correlation coefficients). Urologists with some laparoscopic experience (mean 27.6 cases) can improve laparoscopic skills using mentored videotape analysis and experience gained from a 2-day hands-on course. Prior knowledge, degree of experience, and urologist age had no significant bearing on performance in this setting.

Force and time-dependent self-assembly, disruption and recovery of supramolecular peptide amphiphile nanofibers

NASA Astrophysics Data System (ADS)

Begum Dikecoglu, F.; Topal, Ahmet E.; Ozkan, Alper D.; Deniz Tekin, E.; Tekinay, Ayse B.; Guler, Mustafa O.; Dana, Aykutlu

2018-07-01

Biological feedback mechanisms exert precise control over the initiation and termination of molecular self-assembly in response to environmental stimuli, while minimizing the formation and propagation of defects through self-repair processes. Peptide amphiphile (PA) molecules can self-assemble at physiological conditions to form supramolecular nanostructures that structurally and functionally resemble the nanofibrous proteins of the extracellular matrix, and their ability to reconfigure themselves in response to external stimuli is crucial for the design of intelligent biomaterials systems. Here, we investigated real-time self-assembly, deformation, and recovery of PA nanofibers in aqueous solution by using a force-stabilizing double-pass scanning atomic force microscopy imaging method to disrupt the self-assembled peptide nanofibers in a force-dependent manner. We demonstrate that nanofiber damage occurs at tip-sample interaction forces exceeding 1 nN, and the damaged fibers subsequently recover when the tip pressure is reduced. Nanofiber ends occasionally fail to reconnect following breakage and continue to grow as two individual nanofibers. Energy minimization calculations of nanofibers with increasing cross-sectional ellipticity (corresponding to varying levels of tip-induced fiber deformation) support our observations, with high-ellipticity nanofibers exhibiting lower stability compared to their non-deformed counterparts. Consequently, tip-mediated mechanical forces can provide an effective means of altering nanofiber integrity and visualizing the self-recovery of PA assemblies.