Ultrasonic Wall Thickness Monitoring at High Temperatures (>500 °C)

NASA Astrophysics Data System (ADS)

Cegla, F. B.; Allin, J.; Davies, J. O.; Collins, P.; Cawley, P.

2011-06-01

Corrosion and erosion shorten the life of components that are used in the petrochemical industry. In order to mitigate the safety and financial risks posed by the degradation mechanisms, plant operators monitor wall thicknesses at regular inspection intervals. In high temperature locations inspections have to be carried out at plant shut downs because conventional ultrasonic sensors cannot withstand the high operating temperatures. The authors have developed a waveguide based high temperature thickness gauge for monitoring of wall thicknesses in high temperature areas. The waveguide allows the use of conventional transduction systems (max temp. 60 °C) at one end and guides ultrasonic waves into the high temperature region where the inspection is to be carried out. Slender stainless steel waveguides allow a temperature drop of ˜500-600 °C per 200 mm length to be sustained simply by natural convection cooling. This paper describes the technical challenges that had to be overcome (dispersion and source/receiver characteristics) in order to implement this "acoustic cable". A range of experimental results of thickness measurements on components of different thickness, and furnace tests at different temperatures are presented. An accelerated corrosion test that demonstrates the effectiveness of the monitoring for corrosion is also presented.

Normal reference values for bladder wall thickness on CT in a healthy population.

PubMed

Fananapazir, Ghaneh; Kitich, Aleksandar; Lamba, Ramit; Stewart, Susan L; Corwin, Michael T

2018-02-01

To determine normal bladder wall thickness on CT in patients without bladder disease. Four hundred and nineteen patients presenting for trauma with normal CTs of the abdomen and pelvis were included in our retrospective study. Bladder wall thickness was assessed, and bladder volume was measured using both the ellipsoid formula and an automated technique. Patient age, gender, and body mass index were recorded. Linear regression models were created to account for bladder volume, age, gender, and body mass index, and the multiple correlation coefficient with bladder wall thickness was computed. Bladder volume and bladder wall thickness were log-transformed to achieve approximate normality and homogeneity of variance. Variables that did not contribute substantively to the model were excluded, and a parsimonious model was created and the multiple correlation coefficient was calculated. Expected bladder wall thickness was estimated for different bladder volumes, and 1.96 standard deviation above expected provided the upper limit of normal on the log scale. Age, gender, and bladder volume were associated with bladder wall thickness (p = 0.049, 0.024, and < 0.001, respectively). The linear regression model had an R 2 of 0.52. Age and gender were negligible in contribution to the model, and a parsimonious model using only volume was created for both the ellipsoid and automated volumes (R 2  = 0.52 and 0.51, respectively). Bladder wall thickness correlates with bladder wall volume. The study provides reference bladder wall thicknesses on CT utilizing both the ellipsoid formula and automated bladder volumes.

Gas turbine bucket wall thickness control

DOEpatents

Stathopoulos, Dimitrios; Xu, Liming; Lewis, Doyle C.

2002-01-01

A core for use in casting a turbine bucket including serpentine cooling passages is divided into two pieces including a leading edge core section and a trailing edge core section. Wall thicknesses at the leading edge and the trailing edge of the turbine bucket can be controlled independent of each other by separately positioning the leading edge core section and the trailing edge core section in the casting die. The controlled leading and trailing edge thicknesses can thus be optimized for efficient cooling, resulting in more efficient turbine operation.

Evolution of thick domain walls in de Sitter universe

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

Dolgov, A.D.; Godunov, S.I.; Rudenko, A.S., E-mail: dolgov@fe.infn.it, E-mail: sgodunov@itep.ru, E-mail: a.s.rudenko@inp.nsk.su

We consider thick domain walls in a de Sitter universe following paper by Basu and Vilenkin. However, we are interested not only in stationary solutions found therein, but also investigate the general case of domain wall evolution with time. When the wall thickness parameter, δ{sub 0}, is smaller than H {sup −1}/√2, where H is the Hubble parameter in de Sitter space-time, then the stationary solutions exist, and initial field configurations tend with time to the stationary ones. However, there are no stationary solutions for δ{sub 0} ≥ H {sup −1}/√2. We have calculated numerically the rate of the wallmore » expansion in this case and have found that the width of the wall grows exponentially fast for δ{sub 0} >> H {sup −1}. An explanation for the critical value δ{sub 0} {sub c} = H {sup −1}/√2 is also proposed.« less

The Bulging Behavior of Thick-Walled 6063 Aluminum Alloy Tubes Under Double-Sided Pressures

NASA Astrophysics Data System (ADS)

Cui, Xiao-Lei; Wang, Xiao-Song; Yuan, Shi-Jian

2015-05-01

To make further exploration on the deformation behavior of tube under double-sided pressures, the thick-walled 6063 aluminum alloy tubes with an outer diameter of 65 mm and an average thickness of 7.86 mm have been used to be bulged under the combined action of internal and external pressures. In the experiment, two ends of the thick-walled tubes were fixed using the tooth and groove match. Three levels of external pressure (0 MPa, 40 MPa, and 80 MPa), in conjunction with the internal pressure, were applied on the tube outside and inside simultaneously. The effect of external pressure on the bulging behavior of the thick-walled tubes, such as the limiting expansion ratio, the bulging zone profile, and the thickness distribution, has been investigated. It is shown that the limiting expansion ratio, the bulging zone profile, and the thickness distribution in the homogeneous bulging area are all insensitive to the external pressure. However, the external pressure can make the thick-walled tube achieve a thinner wall at the fracture area. It reveals that the external pressure can only improve the fracture limit of the thick-walled 6063 tubes, but it has very little effect on their homogeneous bulging behavior. It might be because the external pressure can only increase the magnitude of the hydrostatic pressure for the tube but has no effect on the Lode parameter.

Influence of the internal wall thickness of electrical capacitance tomography sensors on image quality

NASA Astrophysics Data System (ADS)

Liang, Shiguo; Ye, Jiamin; Wang, Haigang; Wu, Meng; Yang, Wuqiang

2018-03-01

In the design of electrical capacitance tomography (ECT) sensors, the internal wall thickness can vary with specific applications, and it is a key factor that influences the sensitivity distribution and image quality. This paper will discuss the effect of the wall thickness of ECT sensors on image quality. Three flow patterns are simulated for wall thicknesses of 2.5 mm to 15 mm on eight-electrode ECT sensors. The sensitivity distributions and potential distributions are compared for different wall thicknesses. Linear back-projection and Landweber iteration algorithms are used for image reconstruction. Relative image error and correlation coefficients are used for image evaluation using both simulation and experimental data.

Enhancing cell-free layer thickness by bypass channels in a wall.

PubMed

Saadatmand, M; Shimogonya, Y; Yamaguchi, T; Ishikawa, T

2016-07-26

When blood flows near a wall, red blood cells (RBCs) drift away from the wall and a cell-free layer (CFL) is formed adjacent to the wall. Controlling the CFL thickness is important for preventing adhesion of cells in the design of biomedical devices. In this study, a novel wall configuration with stenoses and bypass channels is proposed to increase the CFL thickness. We found that the presence of bypass channels modified the spatial distribution of cells and substantially increased the CFL downstream of the stenosis. A single-bypass geometry with 5% hematocrit (Hct) blood flow showed a 1.7μm increase in CFL thickness compared to without the bypass. In the case of three bypass channels, a 3μm increase in CFL thickness was observed. The CFL enhancement was observed up to 10% Hct, but no significant enhancement of CFL was indicated for 20% Hct blood flow. The mechanism of the CFL enhancement was investigated using a numerical simulation of the flow field. The results showed that the distance between each streamline and the corner of the stenosis compared with size of RBC was important parameter in regulating CFL thickness. These results show the potential of the proposed mechanism to prevent adhesion of cells to biomedical devices. Copyright © 2015 Elsevier Ltd. All rights reserved.

SU-C-BRA-04: Use of Esophageal Wall Thickness in Evaluation of the Response to Chemoradiation Therapy for Esophageal Cancer

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

Wang, J; Kligerman, S; Lu, W

2015-06-15

Purpose: To quantitatively evaluate the esophageal cancer response to chemoradiation therapy (CRT) by measuring the esophageal wall thickness in CT. Method: Two datasets were used in this study. The first dataset is composed of CT scans of 15 esophageal cancer patients and 15 normal controls. The second dataset is composed of 20 esophageal cancer patients who underwent PET/CT scans before (Pre-CRT) and after CRT (Post-CRT). We first segmented the esophagus using a multi-atlas-based algorithm. The esophageal wall thickness was then computed, on each slice, as the equivalent circle radius of the segmented esophagus excluding the lumen. To evaluate the changesmore » of wall thickness, we computed the standard deviation (SD), coefficient of variation (COV, SD/Mean), and flatness [(Max–Min)/Mean] of wall thickness along the entire esophagus. Results: For the first dataset, the mean wall thickness of cancer patients and normal controls were 6.35 mm and 6.03 mm, respectively. The mean SD, COV, and flatness of the wall thickness were 2.59, 0.21, and 1.27 for the cancer patients and 1.99, 0.16, and 1.13 for normal controls. Statistically significant differences (p < 0.05) were identified in SD and flatness. For the second dataset, the mean wall thickness of pre-CRT and post-CRT patients was 7.13 mm and 6.84 mm, respectively. The mean SD, COV, and flatness were 1.81, 0.26, and 1.06 for pre-CRT and 1.69, 0.26, and 1.06 for post-CRT. Statistically significant difference was not identified for these measurements. Current results are based on the entire esophagus. We believe significant differences between pre- and post-CRT scans could be obtained, if we conduct the measurements at tumor sites. Conclusion: Results show thicker wall thickness in pre-CRT scans and differences in wall thickness changes between normal and abnormal esophagus. This demonstrated the potential of esophageal wall thickness as a marker in the tumor CRT response evaluation. This work was supported in

On thick domain walls in general relativity

NASA Technical Reports Server (NTRS)

Goetz, Guenter; Noetzold, Dirk

1989-01-01

Planar scalar field configurations in general relativity differ considerably from those in flat space. It is shown that static domain walls of finite thickness in curved space-time do not possess a reflection symmetry. At infinity, the space-time tends to the Taub vacuum on one side of the wall and to the Minkowski vacuum (Rindler space-time) on the other. Massive test particles are always accelerated towards the Minkowski side, i.e., domain walls are attractive on the Taub side, but repulsive on the Minkowski side (Taub-vacuum cleaner). It is also proved that the pressure in all directions is always negative. Finally, a brief comment is made concerning the possibility of infinite, i.e., bigger than horizon size, domain walls in our universe. All of the results are independent of the form of the potential V(phi) greater than or equal to 0 of the scalar field phi.

Incidence of non-pulmonary cancer and lung cancer by amount of emphysema and airway wall thickness: a community-based cohort.

PubMed

Aamli Gagnat, Ane; Gjerdevik, Miriam; Gallefoss, Frode; Coxson, Harvey O; Gulsvik, Amund; Bakke, Per

2017-05-01

There is limited knowledge about the prognostic value of quantitative computed tomography (CT) measures of emphysema and airway wall thickness in cancer.The aim of this study was to investigate if using CT to quantitatively assess the amount of emphysema and airway wall thickness independently predicts the subsequent incidence of non-pulmonary cancer and lung cancer.In the GenKOLS study of 2003-2005, 947 ever-smokers performed spirometry and underwent CT examination. The main predictors were the amount of emphysema measured by the percentage of low attenuation areas (%LAA) on CT and standardised measures of airway wall thickness (AWT-PI10). Cancer data from 2003-2013 were obtained from the Norwegian Cancer Register. The hazard ratio associated with emphysema and airway wall thickness was assessed using Cox proportional hazards regression for cancer diagnoses.During 10 years of follow-up, non-pulmonary cancer was diagnosed in 11% of the subjects with LAA <3%, in 19% of subjects with LAA 3-10%, and in 17% of subjects with LAA ≥10%. Corresponding numbers for lung cancer were 2%, 3% and 11%, respectively. After adjustment, the baseline amount of emphysema remained a significant predictor of the incidence of non-pulmonary cancer and lung cancer. Airway wall thickness did not predict cancer independently.This study offers a strong argument that emphysema is an independent risk factor for both non-pulmonary cancer and lung cancer. Copyright ©ERS 2017.

Sex, race, and age distributions of mean aortic wall thickness in a multiethnic population-based sample.

PubMed

Rosero, Eric B; Peshock, Ronald M; Khera, Amit; Clagett, Patrick; Lo, Hao; Timaran, Carlos H

2011-04-01

Reference values and age-related changes of the wall thickness of the abdominal aorta have not been described in the general population. We characterized age-, race-, and gender-specific distributions, and yearly rates of change of mean aortic wall thickness (MAWT), and associations between MAWT and cardiovascular risk factors in a multi-ethnic population-based probability sample. Magnetic resonance imaging measurements of MAWT were performed on 2466 free-living white, black, and Hispanic adult subjects. MAWT race/ethnicity- and gender-specific percentile values across age were estimated using regression analyses. MAWT was greater in men than in women and increased linearly with age in all the groups and across all the percentiles. Hispanic women had the thinnest and black men the thickest aortas. Black men had the highest and white women the lowest age-related MAWT increase. Age, gender, ethnicity, smoking status, systolic blood pressure, low-density lipoprotein-cholesterol levels, high-density lipoprotein-cholesterol levels, and fasting glucose levels were independent predictors of MAWT. Age, gender, and racial/ethnic differences in MAWT distributions exist in the general population. Such differences should be considered in future investigations assessing aortic atherosclerosis and the effects of anti-atherosclerotic therapies. Published by Mosby, Inc.

A Probabilistic Method for Estimation of Bowel Wall Thickness in MR Colonography

PubMed Central

Menys, Alex; Jaffer, Asif; Bhatnagar, Gauraang; Punwani, Shonit; Atkinson, David; Halligan, Steve; Hawkes, David J.; Taylor, Stuart A.

2017-01-01

MRI has recently been applied as a tool to quantitatively evaluate the response to therapy in patients with Crohn’s disease, and is the preferred choice for repeated imaging. Bowel wall thickness on MRI is an important biomarker of underlying inflammatory activity, being abnormally increased in the acute phase and reducing in response to successful therapy; however, a poor level of interobserver agreement of measured thickness is reported and therefore a system for accurate, robust and reproducible measurements is desirable. We propose a novel method for estimating bowel wall-thickness to improve the poor interobserver agreement of the manual procedure. We show that the variability of wall thickness measurement between the algorithm and observer measurements (0.25mm ± 0.81mm) has differences which are similar to observer variability (0.16mm ± 0.64mm). PMID:28072831

Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines

PubMed Central

He, Cunfu; Yan, Lyu; Zhang, Haijun

2018-01-01

It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the −3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ−3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth. PMID:29498636

Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines.

PubMed

Zhao, Huamin; He, Cunfu; Yan, Lyu; Zhang, Haijun

2018-03-02

It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the -3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ -3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth.

Post-cast EDM method for reducing the thickness of a turbine nozzle wall

DOEpatents

Jones, Raymond Joseph; Bojappa, Parvangada Ganapathy; Kirkpatrick, Francis Lawrence; Schotsch, Margaret Jones; Rajan, Rajiv; Wei, Bin

2002-01-01

A post-cast EDM process is used to remove material from the interior surface of a nozzle vane cavity of a turbine. A thin electrode is passed through the cavity between opposite ends of the nozzle vane and displaced along the interior nozzle wall to remove the material along a predetermined path, thus reducing the thickness of the wall between the cavity and the external surface of the nozzle. In another form, an EDM process employing a profile as an electrode is disposed in the cavity and advanced against the wall to remove material from the wall until the final wall thickness is achieved, with the interior wall surface being complementary to the profile surface.

Terahertz inline wall thickness monitoring system for plastic pipe extrusion

NASA Astrophysics Data System (ADS)

Hauck, J.; Stich, D.; Heidemeyer, P.; Bastian, M.; Hochrein, T.

2014-05-01

Conventional and commercially available inline wall thickness monitoring systems for pipe extrusion are usually based on ultrasonic or x-ray technology. Disadvantages of ultrasonic systems are the usual need of water as a coupling media and the high damping in thick walled or foamed pipes. For x-ray systems special safety requirements have to be taken into account because of the ionizing radiation. The terahertz (THz) technology offers a novel approach to solve these problems. THz waves have many properties which are suitable for the non-destructive testing of plastics. The absorption of electrical isolators is typically very low and the radiation is non-ionizing in comparison to x-rays. Through the electromagnetic origin of the THz waves they can be used for contact free measurements. Foams show a much lower absorption in contrast to acoustic waves. The developed system uses THz pulses which are generated by stimulating photoconductive switches with femtosecond laser pulses. The time of flight of THz pulses can be determined with a resolution in the magnitude of several ten femtoseconds. Hence the thickness of an object like plastic pipes can be determined with a high accuracy by measuring the time delay between two reflections on materials interfaces e.g. at the pipe's inner and outer surface, similar to the ultrasonic technique. Knowing the refractive index of the sample the absolute layer thickness from the transit time difference can be calculated easily. This method in principle also allows the measurement of multilayer systems and the characterization of foamed pipes.

Automatic Thickness and Volume Estimation of Sprayed Concrete on Anchored Retaining Walls from Terrestrial LIDAR Data

NASA Astrophysics Data System (ADS)

Martínez-Sánchez, J.; Puente, I.; GonzálezJorge, H.; Riveiro, B.; Arias, P.

2016-06-01

When ground conditions are weak, particularly in free formed tunnel linings or retaining walls, sprayed concrete can be applied on the exposed surfaces immediately after excavation for shotcreting rock outcrops. In these situations, shotcrete is normally applied conjointly with rock bolts and mesh, thereby supporting the loose material that causes many of the small ground falls. On the other hand, contractors want to determine the thickness and volume of sprayed concrete for both technical and economic reasons: to guarantee their structural strength but also, to not deliver excess material that they will not be paid for. In this paper, we first introduce a terrestrial LiDAR-based method for the automatic detection of rock bolts, as typically used in anchored retaining walls. These ground support elements are segmented based on their geometry and they will serve as control points for the co-registration of two successive scans, before and after shotcreting. Then we compare both point clouds to estimate the sprayed concrete thickness and the expending volume on the wall. This novel methodology is demonstrated on repeated scan data from a retaining wall in the city of Vigo (Spain), resulting in a rock bolts detection rate of 91%, that permits to obtain a detailed information of the thickness and calculate a total volume of 3597 litres of concrete. These results have verified the effectiveness of the developed approach by increasing productivity and improving previous empirical proposals for real time thickness estimation.

Inverse Transient Analysis for Classification of Wall Thickness Variations in Pipelines

PubMed Central

Tuck, Jeffrey; Lee, Pedro

2013-01-01

Analysis of transient fluid pressure signals has been investigated as an alternative method of fault detection in pipeline systems and has shown promise in both laboratory and field trials. The advantage of the method is that it can potentially provide a fast and cost effective means of locating faults such as leaks, blockages and pipeline wall degradation within a pipeline while the system remains fully operational. The only requirement is that high speed pressure sensors are placed in contact with the fluid. Further development of the method requires detailed numerical models and enhanced understanding of transient flow within a pipeline where variations in pipeline condition and geometry occur. One such variation commonly encountered is the degradation or thinning of pipe walls, which can increase the susceptible of a pipeline to leak development. This paper aims to improve transient-based fault detection methods by investigating how changes in pipe wall thickness will affect the transient behaviour of a system; this is done through the analysis of laboratory experiments. The laboratory experiments are carried out on a stainless steel pipeline of constant outside diameter, into which a pipe section of variable wall thickness is inserted. In order to detect the location and severity of these changes in wall conditions within the laboratory system an inverse transient analysis procedure is employed which considers independent variations in wavespeed and diameter. Inverse transient analyses are carried out using a genetic algorithm optimisation routine to match the response from a one-dimensional method of characteristics transient model to the experimental time domain pressure responses. The accuracy of the detection technique is evaluated and benefits associated with various simplifying assumptions and simulation run times are investigated. It is found that for the case investigated, changes in the wavespeed and nominal diameter of the pipeline are both important

Local and systemic effects of leg cycling training on arterial wall thickness in healthy humans.

PubMed

Thijssen, Dick H J; Dawson, Ellen A; van den Munckhof, Inge C L; Birk, Gurpreet K; Timothy Cable, N; Green, Daniel J

2013-08-01

Exercise training is associated with direct effects on conduit artery function and structure. Cross-sectional studies suggest the presence of systemic changes in wall thickness as a result of exercise in healthy subjects, but no previous study has examined this question in humans undertaking exercise training. To examine the change in superficial femoral (SFA, i.e. local effect) and carotid (CA, i.e. systemic effect) artery wall thickness across 8 weeks of lower limb cycle training in healthy young men. Fourteen healthy young male subjects were assigned to an 8-week training study of cycling exercise (n = 9) or a control period (n = 5). Before, during (2, 4 and 6 weeks) and after training, SFA and CA wall thickness was examined using automated edge-detection of high resolution ultrasound images. We also measured resting diameter and calculated the wall:lumen(W:L)-ratio. Exercise training did not alter CA or SFA baseline diameter (P = 0.14), but was associated with gradual, consistent and significant decreases in wall thickness and W:L-ratio in both the CA and SFA (P < 0.001 and 0.002, respectively). Two-way ANOVA revealed a comparable magnitude of decrease in wall thickness and W:L-ratio in both arteries across the 8-week period (interaction-effect; P = 0.29 and 0.12, respectively). No changes in artery diameter, wall thickness or W:L-ratio were apparent in controls (0.82, 0.38 and 0.52, respectively). We found that cycle exercise training in healthy young individuals is associated with modest, but significant, decreases in wall thickness in the superficial femoral and carotid arteries. These findings suggest that exercise training causes systemic adaptation of the arterial wall in healthy young subjects. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

49 CFR 179.500-4 - Thickness of wall.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.500-4 Thickness of wall...

Prevalence and histopathological finding of thin-walled and thick-walled Sarcocysts in slaughtered cattle of Karaj abattoir, Iran.

PubMed

Nourollahi-Fard, Saeid R; Kheirandish, Reza; Sattari, Saeid

2015-06-01

Sarcocystosis is a zoonotic disease caused by Sarcocystis spp. with obligatory two host life cycle generally alternating between an herbivorous intermediate host and a carnivorous definitive host. Some species of this coccidian parasite can cause considerable morbidity and mortality in cattle. The present study was set to investigate the prevalence of Sarcocystis spp. and type of cyst wall in slaughtered cattle of Karaj abattoir, Iran. For this purpose 125 cattle (88 males and 37 females) were investigated for the presence of macroscopic and microscopic Sarcocystis cysts in muscular tissues. No macroscopic Sarcocystis cysts were found in any of the samples. In light microscopy, 121 out of 125 cattle (96.8 %) had thin-walled cysts of Sarcocystis cruzi, while 43 out of them (34.4 %) had thick-walled Sarcocystis cyst. In this survey, the most infected tissue was esophagus and heart and the less was diaphragm. Thin-walled cysts (S. cruzi) mostly found in heart and skeletal muscle showed the less. However, thick-walled cyst (S. hominis or S. hirsuta) mostly were detected in diaphragm, heart muscle showed no thick-walled cyst. No significant relation was observed between age and sex and the rate of infection. The results showed that Sarcocystis cyst is prevalent in cattle in the North part of Iran and the evaluation of infection potential can be useful when considering control programs.

Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

DOEpatents

Steinman, D.A.

1980-05-30

Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

DOEpatents

Steinman, David A.

1982-01-01

Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

Multimodal optical measurement in vitro of surface deformations and wall thickness of the pressurized aortic arch

NASA Astrophysics Data System (ADS)

Genovese, Katia; Humphrey, Jay D.

2015-04-01

Computational modeling of arterial mechanics continues to progress, even to the point of allowing the study of complex regions such as the aortic arch. Nevertheless, most prior studies assign homogeneous and isotropic material properties and constant wall thickness even when implementing patient-specific luminal geometries obtained from medical imaging. These assumptions are not due to computational limitations, but rather to the lack of spatially dense sets of experimental data that describe regional variations in mechanical properties and wall thickness in such complex arterial regions. In this work, we addressed technical challenges associated with in vitro measurement of overall geometry, full-field surface deformations, and regional wall thickness of the porcine aortic arch in its native anatomical configuration. Specifically, we combined two digital image correlation-based approaches, standard and panoramic, to track surface geometry and finite deformations during pressurization, with a 360-deg fringe projection system to contour the outer and inner geometry. The latter provided, for the first time, information on heterogeneous distributions of wall thickness of the arch and associated branches in the unloaded state. Results showed that mechanical responses vary significantly with orientation and location (e.g., less extensible in the circumferential direction and with increasing distance from the heart) and that the arch exhibits a nearly linear increase in pressure-induced strain up to 40%, consistent with other findings on proximal porcine aortas. Thickness measurements revealed strong regional differences, thus emphasizing the need to include nonuniform thicknesses in theoretical and computational studies of complex arterial geometries.

Comparison of Maximal Wall Thickness in Hypertrophic Cardiomyopathy Differs Between Magnetic Resonance Imaging and Transthoracic Echocardiography.

PubMed

Bois, John P; Geske, Jeffrey B; Foley, Thomas A; Ommen, Steve R; Pellikka, Patricia A

2017-02-15

Left ventricular (LV) wall thickness is a prognostic marker in hypertrophic cardiomyopathy (HC). LV wall thickness ≥30 mm (massive hypertrophy) is independently associated with sudden cardiac death. Presence of massive hypertrophy is used to guide decision making for cardiac defibrillator implantation. We sought to determine whether measurements of maximal LV wall thickness differ between cardiac magnetic resonance imaging (MRI) and transthoracic echocardiography (TTE). Consecutive patients were studied who had HC without previous septal ablation or myectomy and underwent both cardiac MRI and TTE at a single tertiary referral center. Reported maximal LV wall thickness was compared between the imaging techniques. Patients with ≥1 technique reporting massive hypertrophy received subset analysis. In total, 618 patients were evaluated from January 1, 2003, to December 21, 2012 (mean [SD] age, 53 [15] years; 381 men [62%]). In 75 patients (12%), reported maximal LV wall thickness was identical between MRI and TTE. Median difference in reported maximal LV wall thickness between the techniques was 3 mm (maximum difference, 17 mm). Of the 63 patients with ≥1 technique measuring maximal LV wall thickness ≥30 mm, 44 patients (70%) had discrepant classification regarding massive hypertrophy. MRI identified 52 patients (83%) with massive hypertrophy; TTE, 30 patients (48%). Although guidelines recommend MRI or TTE imaging to assess cardiac anatomy in HC, this study shows discrepancy between the techniques for maximal reported LV wall thickness assessment. In conclusion, because this measure clinically affects prognosis and therapeutic decision making, efforts to resolve these discrepancies are critical. Copyright © 2016 Elsevier Inc. All rights reserved.

Gastric full-thickness suturing during EMR and for treatment of gastric-wall defects (with video).

PubMed

von Renteln, Daniel; Schmidt, Arthur; Riecken, Bettina; Caca, Karel

2008-04-01

The endoscopic full-thickness Plicator device was initially developed to provide an endoscopic treatment option for patients with GERD. Because the endoscopic full-thickness Plicator enables rapid and easy placement of transmural sutures, comparable with surgical sutures, we used the Plicator device for endoscopic treatment or prevention of GI-wall defects. To describe the outcomes and complications of endoscopic full-thickness suturing during EMR and for the treatment of gastric-wall defects. A report of 4 cases treated with the endoscopic full-thickness suturing between June 2006 and April 2007. A large tertiary-referral center. Four subjects received endoscopic full-thickness suturing. The subjects were women, with a mean age of 67 years. Of the 4 subjects, 3 received endoscopic full-thickness suturing during or after an EMR. One subject received endoscopic full-thickness suturing for treatment of a fistula. Primary outcome measurements were clinical procedural success and procedure-related adverse events. The mean time for endoscopic full-thickness suturing was 15 minutes. In all cases, GI-wall patency was restored or ensured, and no procedure-related complications occurred. All subjects responded well to endoscopic full-thickness suturing. The resection of one GI stromal tumor was incomplete. Because of the Plicator's 60F distal-end diameter, endoscopic full-thickness suturing could only be performed with the patient under midazolam and propofol sedation. The durable Plicator suture might compromise the endoscopic follow-up after EMR. The endoscopic full-thickness Plicator permits rapid and easy placement of transmural sutures and seems to be a safe and effective alternative to surgical intervention to restore GI-wall defects or to ensure GI-wall patency during EMR procedures.

Quantification of common carotid artery and descending aorta vessel wall thickness from MR vessel wall imaging using a fully automated processing pipeline.

PubMed

Gao, Shan; van 't Klooster, Ronald; Brandts, Anne; Roes, Stijntje D; Alizadeh Dehnavi, Reza; de Roos, Albert; Westenberg, Jos J M; van der Geest, Rob J

2017-01-01

To develop and evaluate a method that can fully automatically identify the vessel wall boundaries and quantify the wall thickness for both common carotid artery (CCA) and descending aorta (DAO) from axial magnetic resonance (MR) images. 3T MRI data acquired with T 1 -weighted gradient-echo black-blood imaging sequence from carotid (39 subjects) and aorta (39 subjects) were used to develop and test the algorithm. The vessel wall segmentation was achieved by respectively fitting a 3D cylindrical B-spline surface to the boundaries of lumen and outer wall. The tube-fitting was based on the edge detection performed on the signal intensity (SI) profile along the surface normal. To achieve a fully automated process, Hough Transform (HT) was developed to estimate the lumen centerline and radii for the target vessel. Using the outputs of HT, a tube model for lumen segmentation was initialized and deformed to fit the image data. Finally, lumen segmentation was dilated to initiate the adaptation procedure of outer wall tube. The algorithm was validated by determining: 1) its performance against manual tracing; 2) its interscan reproducibility in quantifying vessel wall thickness (VWT); 3) its capability of detecting VWT difference in hypertensive patients compared with healthy controls. Statistical analysis including Bland-Altman analysis, t-test, and sample size calculation were performed for the purpose of algorithm evaluation. The mean distance between the manual and automatically detected lumen/outer wall contours was 0.00 ± 0.23/0.09 ± 0.21 mm for CCA and 0.12 ± 0.24/0.14 ± 0.35 mm for DAO. No significant difference was observed between the interscan VWT assessment using automated segmentation for both CCA (P = 0.19) and DAO (P = 0.94). Both manual and automated segmentation detected significantly higher carotid (P = 0.016 and P = 0.005) and aortic (P < 0.001 and P = 0.021) wall thickness in the hypertensive patients. A reliable and reproducible pipeline for fully

Analysis of thermoelastic characteristics in a thick walled FGM cylinder

NASA Astrophysics Data System (ADS)

Tanvir, A. N. M.; Islam, Md. Didarul; Ahmed, Faisal

2017-12-01

This study is concerned with the behavior of stress and strain in a thick walled functionally graded material (FGM) cylinder under internal pressure. The incompatible eigenstrain and equivalent eigenstrain developed in the cylinder, are taken into account. As a demonstration, a TiC/Al2O3 FGM cylinder is considered and different components of stress and strain are presented in order to study the effects of internal pressure, temperature difference (between room and sintering temperature), cylinder wall thickness and material distribution. The numerical result presented here shows that the thermoelastic characteristic like stress and strain of an FGM cylinder is significantly influenced by some of the above-mentioned parameters and can be controlled by properly controlling these parameters.

Three-dimensional atrial wall thickness maps to inform catheter ablation procedures for atrial fibrillation.

PubMed

Bishop, Martin; Rajani, Ronak; Plank, Gernot; Gaddum, Nicholas; Carr-White, Gerry; Wright, Matt; O'Neill, Mark; Niederer, Steven

2016-03-01

Transmural lesion formation is critical to success in atrial fibrillation ablation and is dependent on left atrial wall thickness (LAWT). Pre- and peri-procedural planning may benefit from LAWT measurements. To calculate the LAWT, the Laplace equation was solved over a finite element mesh of the left atrium derived from the segmented computed tomographic angiography (CTA) dataset. Local LAWT was then calculated from the length of field lines derived from the Laplace solution that spanned the wall from the endocardium or epicardium. The method was validated on an atrium phantom and retrospectively applied to 10 patients who underwent routine coronary CTA for standard clinical indications at our institute. The Laplace wall thickness algorithm was validated on the left atrium phantom. Wall thickness measurements had errors of <0.2 mm for thicknesses of 0.5-5.0 mm that are attributed to image resolution and segmentation artefacts. Left atrial wall thickness measurements were performed on 10 patients. Successful comprehensive LAWT maps were generated in all patients from the coronary CTA images. Mean LAWT measurements ranged from 0.6 to 1.0 mm and showed significant inter and intra patient variability. Left atrial wall thickness can be measured robustly and efficiently across the whole left atrium using a solution of the Laplace equation over a finite element mesh of the left atrium. Further studies are indicated to determine whether the integration of LAWT maps into pre-existing 3D anatomical mapping systems may provide important anatomical information for guiding radiofrequency ablation. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Dynamic film thickness between bubbles and wall in a narrow channel

NASA Astrophysics Data System (ADS)

Ito, Daisuke; Damsohn, Manuel; Prasser, Horst-Michael; Aritomi, Masanori

2011-09-01

The present paper describes a novel technique to characterize the behavior of the liquid film between gas bubbles and the wall in a narrow channel. The method is based on the electrical conductance. Two liquid film sensors are installed on both opposite walls in a narrow rectangular channel. The liquid film thickness underneath the gas bubbles is recorded by the first sensor, while the void fraction information is obtained by measuring the conductance between the pair of opposite sensors. Both measurements are taken on a large two-dimensional domain and with a high speed. This makes it possible to obtain the two-dimensional distribution of the dynamic liquid film between the bubbles and the wall. In this study, this method was applied to an air-water flow ranging from bubbly to churn regimes in the narrow channel with a gap width of 1.5 mm.

Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

NASA Astrophysics Data System (ADS)

Schonberg, William P.

1993-04-01

Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

[The cutaneous groin flap for coverage of a full-thickness abdominal wall defect].

PubMed

Doebler, O; Spierer, R

2010-08-01

A full-thickness defect of the abdominal wall is rare and may occur as a complication of extended abdominal surgery procedures. We report about a 69-year-old patient who was presented to our department with a full-thickness abdominal wall defect and a fully exposed collagen-mesh for reconstructive wound closure. 13 operations with resections of necrotic parts of the abdominal wall were performed following a complicated intraabdominal infection. After debridement and mesh explantation, closure of the remaining defect of the lower abdominal region was achieved by a cutaneous groin flap. Georg Thieme Verlag KG Stuttgart New York.

Riser Difference Uncertainty Methodology Based on Tank AY-101 Wall Thickness Measurements with Application to Tank AN-107

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

Weier, Dennis R.; Anderson, Kevin K.; Berman, Herbert S.

2005-03-10

The DST Integrity Plan (RPP-7574, 2003, Double-Shell Tank Integrity Program Plan, Rev. 1A, CH2M HILL Hanford Group, Inc., Richland, Washington.) requires the ultrasonic wall thickness measurement of two vertical scans of the tank primary wall while using a single riser location. The resulting measurements are then used in extreme value methodology to predict the minimum wall thickness expected for the entire tank. The representativeness of using a single riser in this manner to draw conclusions about the entire circumference of a tank has been questioned. The only data available with which to address the representativeness question comes from Tank AY-101more » since only for that tank have multiple risers been used for such inspection. The purpose of this report is to (1) further characterize AY-101 riser differences (relative to prior work); (2) propose a methodology for incorporating a ''riser difference'' uncertainty for subsequent tanks for which only a single riser is used, and (3) specifically apply the methodology to measurements made from a single riser in Tank AN-107.« less

Wood formation from the base to the crown in Pinus radiata: gradients of tracheid wall thickness, wood density, radial growth rate and gene expression

Treesearch

Sheree Cato; Lisa McMillan; Lloyd Donaldson; Thomas Richardson; Craig Echt; Richard Gardner

2006-01-01

Wood formation was investigated at five heights along the bole for two unrelated trees of Pinus radiataBoth trees showed clear gradients in wood properties from the base to the crown. Cambial cells at the base of the tree were dividing 3.3-fold slower than those at the crown, while the average thickness of cell walls in wood was highest at the base....

New research perspectives from a novel approach to quantify tracheid wall thickness.

PubMed

Prendin, Angela Luisa; Petit, Giai; Carrer, Marco; Fonti, Patrick; Björklund, Jesper; von Arx, Georg

2017-07-01

The analysis of xylem cell anatomical features in dated tree rings provides insights into xylem functional responses and past growth conditions at intra-annual resolution. So far, special focus has been given to the lumen of the water-conducting cells, whereas the equally relevant cell wall thickness (CWT) has been less investigated due to methodological limitations. Here we present a novel approach to measure tracheid CWT in high-resolution images of wood cross-sections that is implemented within the specialized image-analysis tool 'ROXAS'. Compared with the traditional manual line measurements along a selection of few radial files, this novel image-analysis tool can: (i) measure CWT of all tracheids in a tree-ring cross-section, thus increasing the number of individual tracheid measurements by a factor of ~10-20; (ii) measure the tangential and radial walls separately; and (iii) laterally integrate the measurements in a customizable way from only the thinnest central part of the cell walls up to the thickest part of the tracheids at the corners. Cell wall thickness measurements performed with our novel approach and the traditional manual approach showed comparable accuracy for several image resolutions, with an optimal accuracy-efficiency balance at 100× magnification. The configurable settings intended to underscore different cell wall properties indeed changed the absolute levels and intra- and inter-annual patterns of CWT. This versatility, together with the high data production capacity, allows to tailor the measurements of CWT to the specific goal of each study, which opens new research perspectives, e.g., for investigating structure-function relationships, tree stress responses and carbon allocation patterns, and for reconstructing climate based on intra- and inter-annual variability of anatomical wood density. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A film-based wall shear stress sensor for wall-bounded turbulent flows

NASA Astrophysics Data System (ADS)

Amili, Omid; Soria, Julio

2011-07-01

In wall-bounded turbulent flows, determination of wall shear stress is an important task. The main objective of the present work is to develop a sensor which is capable of measuring surface shear stress over an extended region applicable to wall-bounded turbulent flows. This sensor, as a direct method for measuring wall shear stress, consists of mounting a thin flexible film on the solid surface. The sensor is made of a homogeneous, isotropic, and incompressible material. The geometry and mechanical properties of the film are measured, and particles with the nominal size of 11 μm in diameter are embedded on the film's surface to act as markers. An optical technique is used to measure the film deformation caused by the flow. The film has typically deflection of less than 2% of the material thickness under maximum loading. The sensor sensitivity can be adjusted by changing the thickness of the layer or the shear modulus of the film's material. The paper reports the sensor fabrication, static and dynamic calibration procedure, and its application to a fully developed turbulent channel flow at Reynolds numbers in the range of 90,000-130,000 based on the bulk velocity and channel full height. The results are compared to alternative wall shear stress measurement methods.

An exact solution for a thick domain wall in general relativity

NASA Technical Reports Server (NTRS)

Goetz, Guenter; Noetzold, Dirk

1989-01-01

An exact solution of the Einstein equations for a static, planar domain wall with finite thickness is presented. At infinity, density and pressure vanish and the space-time tends to the Minkowski vacuum on one side of the wall and to the Taub vacuum on the other side. A surprising feature of this solution is that the density and pressure distribution are symmetric about the central plane of the wall whereas the space-time metric and therefore also the gravitational field experienced by a test particle is asymmetric.

The implications of different lateral wall thicknesses on surgical access to the maxillary sinus.

PubMed

Lim, Ee Lian; Ngeow, Wei Cheong; Lim, Daniel

2017-11-27

The objective of this study was to measure the topographic thickness of the lateral wall of the maxillary sinus in selected Asian populations. Measurements were made on the lateral walls of maxillary sinuses recorded using CBCT in a convenient sample of patients attending an Asian teaching hospital. The points of measurement were the intersections between the axes along the apices of the canine, first premolar, and second premolar and along the mesiobuccal and distobuccal apices of the first and second molars and horizontal planes 10 mm, 20 mm, 30 mm and 40 mm beneath the orbital floor. The CBCT images of 109 patients were reviewed. The mean age of the patients was 33.0 (SD 14.8) years. Almost three quarters (71.8%) of the patients were male. The mean bone thickness decreased beginning at the 10-mm level and continuing to 40 mm below the orbital floor. Few canine regions showed encroachment of the maxillary sinus. The thickness of the buccal wall gradually increased from the canine region (where sinus encroachment of the canine region was present) to the first molar region, after which it decreased to the thickness observed at the canine region. The buccal wall of the maxillary sinus became thicker anteroposteriorly, except in the region of the second molar, and thinner superoinferiorly. These changes will affect the approach used to osteotomize the lateral sinus wall for oral surgery and for the sinus lift procedure.

Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient

PubMed Central

Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F

2017-01-01

The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness. PMID:28761667

Correlation between capillary oxygen saturation and small intestinal wall thickness in the equine colic patient.

PubMed

Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F

2017-01-01

The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness.

Effects of finite wall thickness and sinusoidal heating on convection in nanofluid-saturated local thermal non-equilibrium porous cavity

NASA Astrophysics Data System (ADS)

Alsabery, A. I.; Chamkha, A. J.; Saleh, H.; Hashim, I.; Chanane, B.

2017-03-01

The effects of finite wall thickness and sinusoidal heating on convection in a nanofluid-saturated local thermal non-equilibrium (LTNE) porous cavity are studied numerically using the finite difference method. The finite thickness vertical wall of the cavity is maintained at a constant temperature and the right wall is heated sinusoidally. The horizontal insulated walls allow no heat transfer to the surrounding. The Darcy law is used along with the Boussinesq approximation for the flow. Water-based nanofluids with Cu nanoparticles are chosen for investigation. The results of this study are obtained for various parameters such as the Rayleigh number, periodicity parameter, nanoparticles volume fraction, thermal conductivity ratio, ratio of wall thickness to its height and the modified conductivity ratio. Explanation for the influence of the various above-mentioned parameters on the streamlines, isotherms, local Nusselt number and the weighted average heat transfer is provided with regards to the thermal conductivities of nanoparticles suspended in the pure fluid and the porous medium. It is shown that the overall heat transfer is significantly increased with the relative non-uniform heating. Further, the convection heat transfer is shown to be inhibited by the presence of the solid wall. The results have possible applications in the heat-storage fluid-saturated porous systems and the applications of the high power heat transfer.

New portable pipe wall thickness measuring technique

NASA Astrophysics Data System (ADS)

Pascente, Joseph E.

1998-03-01

One of the biggest inspection challenges facing many of the process industries; namely the petrochemical, refining, fossil power, and pulp and paper industries is: How to effectively examine their insulated piping? While there are a number of failure mechanisms involved in various process piping systems, piping degradation through corrosion and erosion are by far the most prevalent. This degradation can be in the form of external corrosion under insulation, internal corrosion through a variety of mechanisms, and internal erosion caused by the flow of the product through the pipe. Refineries, chemical plants and electrical power plants have MANY thousands of miles of pipe that are insulated to prevent heat loss or heat absorption. This insulation is often made up of several materials, with calcium based material being the most dense. The insulating material is usually wrapped with an aluminum or stainless steel outer wrap. Verification of wall thickness of these pipes can be accomplished by removing the insulation and doing an ultrasound inspection or by taking x- rays at a tangent to the edge of the pipe through the insulation. Both of these processes are slow and expensive. The time required to obtain data is measured in hours per meter. The ultrasound method requires that the insulation be plugged after the inspection. The surface needs to be cleaned or the resulting data will not be accurate. The tangent x-ray only shows two thicknesses and requires that the area be roped off because of radiation safety.

Cross-Sectional Elasticity Imaging of Arterial Wall by Comparing Measured Change in Thickness with Model Waveform

NASA Astrophysics Data System (ADS)

Tang, Jiang; Hasegawa, Hideyuki; Kanai, Hiroshi

2005-06-01

For the assessment of the elasticity of the arterial wall, we have developed the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791] for measuring the minute change in thickness due to heartbeats and the elasticity of the arterial wall with transcutaneous ultrasound. For various reasons, for example, an extremely small deformation of the wall, the minute change in wall thickness during one heartbeat is largely influenced by noise in these cases and the reliability of the elasticity distribution obtained from the maximum change in thickness deteriorates because the maximum value estimation is largely influenced by noise. To obtain a more reliable cross-sectional image of the elasticity of the arterial wall, in this paper, a matching method is proposed to evaluate the waveform of the measured change in wall thickness by comparing the measured waveform with a template waveform. The maximum deformation, which is used in the calculation of elasticity, was determined from the amplitude of the matched model waveform to reduce the influence of noise. The matched model waveform was obtained by minimizing the difference between the measured and template waveforms. Furthermore, a random error, which was obtained from the reproducibility among the heartbeats of the measured waveform, was considered useful for the evaluation of the reliability of the measured waveform.

Measurement of thickness of film deposited on the plasma-facing wall in the QUEST tokamak by colorimetry.

PubMed

Wang, Z; Hanada, K; Yoshida, N; Shimoji, T; Miyamoto, M; Oya, Y; Zushi, H; Idei, H; Nakamura, K; Fujisawa, A; Nagashima, Y; Hasegawa, M; Kawasaki, S; Higashijima, A; Nakashima, H; Nagata, T; Kawaguchi, A; Fujiwara, T; Araki, K; Mitarai, O; Fukuyama, A; Takase, Y; Matsumoto, K

2017-09-01

After several experimental campaigns in the Kyushu University Experiment with Steady-state Spherical Tokamak (QUEST), the originally stainless steel plasma-facing wall (PFW) becomes completely covered with a deposited film composed of mixture materials, such as iron, chromium, carbon, and tungsten. In this work, an innovative colorimetry-based method was developed to measure the thickness of the deposited film on the actual QUEST wall. Because the optical constants of the deposited film on the PFW were position-dependent and the extinction coefficient k 1 was about 1.0-2.0, which made the probing light not penetrate through some thick deposited films, the colorimetry method developed can only provide a rough value range of thickness of the metal-containing film deposited on the actual PFW in QUEST. However, the use of colorimetry is of great benefit to large-area inspections and to radioactive materials in future fusion devices that will be strictly prohibited from being taken out of the limited area.

Fine-tuning the Wall Thickness of Ordered Mesoporous Graphene by Exploiting Ligand Exchange of Colloidal Nanocrystals

NASA Astrophysics Data System (ADS)

Han, Dandan; Yan, Yancui; Wei, Jishi; Wang, Biwei; Li, Tongtao; Guo, Guannan; Yang, Dong; Xie, Songhai; Dong, Angang

2017-12-01

Because of their unique physical properties, three-dimensional (3D) graphene has attracted enormous attention over the past years. However, it is still a challenge to precisely control the layer thickness of 3D graphene. Here, we report a novel strategy to rationally adjust the wall thickness of ordered mesoporous graphene (OMG). By taking advantage of ligand exchange capability of colloidal Fe3O4 nanocrystals, we are able to fine-tune the wall thickness of OMG from 2 to 6 layers of graphene by tailoring the hydrocarbon ligands attached to the nanocrystal surface. When evaluated as electrocatalyst for oxygen reduction reaction upon S and N doping, the 4-layer OMG is found to show better catalytic performance compared with its 2- and 6-layer counterparts, which we attribute to the enhanced exposure of active sites resulting from its ultrathin wall thickness and high surface area.

Echocardiographic Manifestations of Glycogen Storage Disease III: Increase in Wall Thickness and Left Ventricular Mass over Time

PubMed Central

Vertilus, Shawyntee M.; Austin, Stephanie L.; Foster, Kimberly S.; Boyette, Keri E.; Bali, Deeksha; Li, Jennifer S.; Kishnani, Priya S.; Wechsler, Stephanie Burns

2013-01-01

Purpose Glycogen Storage Disease (GSD) type III, glycogen debranching enzyme deficiency, causes accumulation of glycogen in liver, skeletal, and cardiac muscle. Some patients develop increased left ventricular (LV) thickness by echocardiography, but the rate of increase and its significance remain unclear. Methods We evaluated 33 patients with GSD type III, 23 with IIIa and 10 with IIIb, ages 1 month – 55.5 yrs, by echocardiography for wall thickness, LV mass, shortening and ejection fractions, at 1 time point (n = 33) and at 2 time points in patients with more than 1 echocardiogram (13 of the 33). Results Of 23 cross-sectional patients with type IIIa, 12 had elevated LV mass, 11 had elevated wall thickness. One type IIIb patient had elevated LV mass but 4 had elevated wall thickness. For those with multiple observations, 9 of 10 with type IIIa developed increased LV mass over time, with 3 already increased at first measurement. Shortening and ejection fractions were generally normal. Conclusion Elevated LV mass and wall thickness is more common in patients with type IIIa but develops rarely in type IIIb, though ventricular systolic function is preserved. This suggests serial echocardiograms with attention to LV thickness and mass are important for care of these patients. PMID:20526204

Quantitative evaluation of the relationship between dorsal wall length, sole thickness, and rotation of the distal phalanx in the bovine claw using computed tomography.

PubMed

Tsuka, T; Murahata, Y; Azuma, K; Osaki, T; Ito, N; Okamoto, Y; Imagawa, T

2014-10-01

Computed tomography (CT) was performed on 800 untrimmed claws (400 inner claws and 400 outer claws) of 200 pairs of bovine hindlimbs to investigate the relationships between dorsal wall length and sole thickness, and between dorsal wall length and the relative rotation angle of distal phalanx-to-sole surface (S-D angle). Sole thickness was 3.8 and 4.0 mm at the apex of the inner claws and outer claws, respectively, with dorsal wall lengths <70 mm. These sole thickness values were less than the critical limit of 5 mm, which is associated with a softer surface following thinning of the soles. A sole thickness of 5 mm at the apex was estimated to correlate with dorsal wall lengths of 72.1 and 72.7 mm for the inner and outer claws, respectively. Sole thickness was 6.1 and 6.4 mm at the apex of the inner and outer claws, respectively, with dorsal wall lengths of 75 mm. These sole thickness values were less than the recommended sole thickness of 7 mm based on the protective function of the soles. A sole thickness >7 mm at the apex was estimated to correlate with a dorsal wall length of 79.8 and 78.4mm for the inner and outer claws, respectively. The S-D angles were recorded as anteversions of 2.9° and 4.7° for the inner and outer claws, respectively, with a dorsal wall length of 75 mm. These values indicate that the distal phalanx is likely to have rotated naturally forward toward the sole surface. The distal phalanx rotated backward to the sole surface at 3.2° and 7.6° for inner claws with dorsal wall lengths of 90-99 and ≥100 mm, respectively; and at 3.5° for outer claws with a dorsal wall length ≥100 mm. Dorsal wall lengths of 85.7 and 97.2 mm were estimated to correlate with a parallel positional relationship of the distal phalanx to the sole surface in the inner and outer claws, respectively. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Impact of emphysema and airway wall thickness on quality of life in smoking-related COPD.

PubMed

Gietema, Hester A; Edwards, Lisa D; Coxson, Harvey O; Bakke, Per S

2013-08-01

Limited data are available as to the relationship between computed tomography (CT) derived data on emphysema and airway wall thickness, and quality of life in subjects with chronic obstructive pulmonary disease (COPD). Such data may work to clarify the clinical correlate of the CT findings. We included 1778 COPD subjects aged 40-75 years with a smoking history of at least 10 pack-years. They were examined with St George's Respiratory Questionnaire (SGRQ-C) and high-resolution chest CT. Level of emphysema was assessed as percent low-attenuation areas less than -950 Hounsfield units (%LAA). Airway wall thickness was estimated by calculating the square root of wall area of an imaginary airway with an internal perimeter of 10 mm (Pi10). In both men and women, the mean total score and most of the subscores of SGRQ-C increased with increasing level of emphysema and increasing level of airway wall thickness, after adjusting for age, smoking status, pack years, body mass index and FEV1. The highest gradient was seen in the relationship between the activity score and the emphysema level. The activity score increased by 35% from the lowest to the highest emphysema tertile. The relationship between level of emphysema and the total SGRQ-C score became weaker with increasing GOLD (Global initiative for Chronic Obstructive Lung Disease) stages (p < 0.001), while the impact of gender was limited. In subjects with COPD, increasing levels of emphysema and airway wall thickness are independently related to impaired quality of life. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ultrasonic guided wave tomography for wall thickness mapping in pipes

NASA Astrophysics Data System (ADS)

Willey, Carson L.

Corrosion and erosion damage pose fundamental challenges to operation of oil and gas infrastructure. In order to manage the life of critical assets, plant operators must implement inspection programs aimed at assessing the severity of wall thickness loss (WTL) in pipelines, vessels, and other structures. Maximum defect depth determines the residual life of these structures and therefore represents one of the key parameters for robust damage mitigation strategies. In this context, continuous monitoring with permanently installed sensors has attracted significant interest and currently is the subject of extensive research worldwide. Among the different monitoring approaches being considered, significant promise is offered by the combination of guided ultrasonic wave technology with the principles of model based inversion under the paradigm of what is now referred to as guided wave tomography (GWT). Guided waves are attractive because they propagate inside the wall of a structure over a large distance. This can yield significant advantages over conventional pulse-echo thickness gage sensors that provide insufficient area coverage -- typically limited to the sensor footprint. While significant progress has been made in the application of GWT to plate-like structures, extension of these methods to pipes poses a number of fundamental challenges that have prevented the development of sensitive GWT methods. This thesis focuses on these challenges to address the complex guided wave propagation in pipes and to account for parametric uncertainties that are known to affect model based inversion and which are unavoidable in real field applications. The main contribution of this work is the first demonstration of a sensitive GWT method for accurately mapping the depth of defects in pipes. This is achieved by introducing a novel forward model that can extract information related to damage from the complex waveforms measured by pairs of guided wave transducers mounted on the pipe

Optimization of Surface Roughness and Wall Thickness in Dieless Incremental Forming Of Aluminum Sheet Using Taguchi

NASA Astrophysics Data System (ADS)

Hamedon, Zamzuri; Kuang, Shea Cheng; Jaafar, Hasnulhadi; Azhari, Azmir

2018-03-01

Incremental sheet forming is a versatile sheet metal forming process where a sheet metal is formed into its final shape by a series of localized deformation without a specialised die. However, it still has many shortcomings that need to be overcome such as geometric accuracy, surface roughness, formability, forming speed, and so on. This project focus on minimising the surface roughness of aluminium sheet and improving its thickness uniformity in incremental sheet forming via optimisation of wall angle, feed rate, and step size. Besides, the effect of wall angle, feed rate, and step size to the surface roughness and thickness uniformity of aluminium sheet was investigated in this project. From the results, it was observed that surface roughness and thickness uniformity were inversely varied due to the formation of surface waviness. Increase in feed rate and decrease in step size will produce a lower surface roughness, while uniform thickness reduction was obtained by reducing the wall angle and step size. By using Taguchi analysis, the optimum parameters for minimum surface roughness and uniform thickness reduction of aluminium sheet were determined. The finding of this project helps to reduce the time in optimising the surface roughness and thickness uniformity in incremental sheet forming.

A tale of two neglected systems-structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves.

PubMed

Botha, C E J

2013-01-01

There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5-7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer.

The Effects of Modified Wall Squat Exercises on Average Adults’ Deep Abdominal Muscle Thickness and Lumbar Stability

PubMed Central

Cho, Misuk

2013-01-01

[Purpose] The purpose of this study was to compare the effects of bridge exercises applying the abdominal drawing-in method and modified wall squat exercises on deep abdominal muscle thickness and lumbar stability. [Subjects] A total of 30 subjects were equally divided into an experimental group and a control group. [Methods] The experimental group completed modified wall squat exercises, and the control group performed bridge exercises. Both did so for 30 minutes three times per week over a six-week period. Both groups’ transversus abdominis (Tra), internal oblique (IO), and multifidus muscle thickness were measured using ultrasonography, while their static lumbar stability and dynamic lumbar stability were measured using a pressure biofeedback unit. [Results] A comparison of the pre-intervention and post-intervention measures of the experimental group and the control group was made; the Tra and IO thicknesses were significantly different in both groups. [Conclusion] The modified wall squat exercise and bridge exercise affected the thicknesses of the Tra and the IO muscles. While the bridge exercise requirs space and a mattress to lie on, the modified wall squat exercise can be conveniently performed anytime. PMID:24259831

Effect of the Coronal Wall Thickness of Dental Implants on the Screw Joint Stability in the Internal Implant-Abutment Connection.

PubMed

Lee, Ji-Hye; Huh, Yoon-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

2016-01-01

To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P < .05). These implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P < .05). Greater vertical load and thinner coronal wall thickness significantly increased coronal diameter expansion of the implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P < .05). Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

Collapse Pressure Analysis of Transversely Isotropic Thick-Walled Cylinder Using Lebesgue Strain Measure and Transition Theory

PubMed Central

Aggarwal, A. K.; Sharma, Richa; Sharma, Sanjeev

2014-01-01

The objective of this paper is to provide guidance for the design of the thick-walled cylinder made up of transversely isotropic material so that collapse of cylinder due to influence of internal and external pressure can be avoided. The concept of transition theory based on Lebesgue strain measure has been used to simplify the constitutive equations. Results have been analyzed theoretically and discussed numerically. From this analysis, it has been concluded that, under the influence of internal and external pressure, circular cylinder made up of transversely isotropic material (beryl) is on the safer side of the design as compared to the cylinders made up of isotropic material (steel). This is because of the reason that percentage increase in effective pressure required for initial yielding to become fully plastic is high for beryl as compared to steel which leads to the idea of “stress saving” that reduces the possibility of collapse of thick-walled cylinder due to internal and external pressure. PMID:24523632

Effect of multi-layer thermal insulation thickness and location on the hypervelocity impact response of dual-wall structures

NASA Astrophysics Data System (ADS)

Schonberg, William P.

Traditional perforation-resistant wall design for long-duration spacecraft consists of a "bumper" that is placed a small distance away from the main "pressure wall" of a spacecraft compartment or module. This concept has been studied extensively as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall system is employed on an earth-orbiting spacecraft, then a blanket of multi-layer insulation (MLI) will typically be included within the dual-wall system for thermal protection purposes. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions to study the effect of MLI thickness and location on perforation resistance. The results presented consist of test-by-test comparisons of the damage sustained by similar dual-wall systems with blanket MLI of various thicknesses and at various locations within the dual-wall systems under similar impact loading conditions. The analyses performed revealed that the placement of the MLI had a significant effect on the ballistic limit of the dual-wall structures considered while reducing the thickness of the MLI by as much as 1/3 did not.

The development and structure of thick-walled, multicellular, aerial spores in Diheterospora chlamydosporia (=Verticillium chlamydosporium).

PubMed

Cambell, W P; Griffiths, D A

1975-07-01

The aerial, thick-walled spores in Diheterospara chlamydosporia arose as terminal swellings on erect hyphae. Repeated septation of the continuously swelling spore resulted in a multicellular structure. Immediately after the onset of septation secondary wall material was laid down between the two-layered primary wall and the plasmalemma. The presence of secondary wall material indicates that the multicellular spore is a dictyochlamydospore and not an aleuriospore. The relationship between chlamydospores and aleuriospores in other fungi is discussed.

Comparative physical and chemical analyses of cotton fibers from two near isogenic upland lines differing in fiber wall thickness

USDA-ARS?s Scientific Manuscript database

The thickness of cotton fiber cell walls is an important property that partially determines the economic value of cotton. To better understand the physical and chemical manifestations of the genetic variations that regulate the degree of fiber wall thickness, we used a comprehensive set of methods t...

A tale of two neglected systems—structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves

PubMed Central

Botha, C. E. J.

2013-01-01

There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer. PMID:23964280

Photoelastic Analysis of Cracked Thick Walled Cylinders

NASA Astrophysics Data System (ADS)

Pastramă, Ştefan Dan

2017-12-01

In this paper, the experimental determination of the stress intensity factor in thick walled cylinders subject to uniform internal pressure and having longitudinal non-penetrating cracks is presented. Photoelastic measurements were used together with the expressions of the stress field near the crack tip for Mode I crack extension and a specific methodology for stress intensity factor determination. Two types of longitudinal cracks - internal and external - were considered. Four plane models were manufactured and analyzed in a plane polariscope at different values of the applied internal pressure. The values of the normalized stress intensity factor were calculated and the results were compared to those reported by other authors. A good accuracy was noticed, showing the reliability of the experimental procedure.

High levels of thyroid-stimulating hormone are associated with aortic wall thickness in the general population.

PubMed

Ittermann, Till; Lorbeer, Roberto; Dörr, Marcus; Schneider, Tobias; Quadrat, Alexander; Heßelbarth, Lydia; Wenzel, Michael; Lehmphul, Ina; Köhrle, Josef; Mensel, Birger; Völzke, Henry

2016-12-01

Our aim was to investigate the association of thyroid function defined by serum concentrations of thyroid-stimulating hormone (TSH) with thoracic aortic wall thickness (AWT) as a marker of atherosclerotic processes. We pooled data of 2,679 individuals from two independent population-based surveys of the Study of Health in Pomerania. Aortic diameter and AWT measurements were performed on a 1.5-T MRI scanner at the concentration of the right pulmonary artery displaying the ascending and the descending aorta. TSH, treated as continuous variable, was significantly associated with descending AWT (β = 0.11; 95 % confidence interval (CI) 0.02-0.21), while the association with ascending AWT was not statistically significant (β = 0.20; 95 % CI -0.01-0.21). High TSH (>3.29 mIU/L) was significantly associated with ascending (β = 0.12; 95 % CI 0.02-0.23) but not with descending AWT (β = 0.06; 95 % CI -0.04-0.16). There was no consistent association between TSH and aortic diameters. Our study demonstrated that AWT values increase with increasing serum TSH concentrations. Thus, a hypothyroid state may be indicative for aortic atherosclerosis. These results fit very well to the findings of previous studies pointing towards increased atherosclerotic risk in the hypothyroid state. • Serum TSH concentrations are positively associated with aortic wall thickness. • Serum TSH concentrations are not associated with the aortic diameters. • Serum 3,5-diiodothyronine concentrations may be positively associated with aortic wall thickness.

Assessment of bronchial wall thickness and lumen diameter in human adults using multi-detector computed tomography: comparison with theoretical models

PubMed Central

Montaudon, M; Desbarats, P; Berger, P; de Dietrich, G; Marthan, R; Laurent, F

2007-01-01

A thickened bronchial wall is the morphological substratum of most diseases of the airway. Theoretical and clinical models of bronchial morphometry have so far focused on bronchial lumen diameter, and bronchial length and angles, mainly assessed from bronchial casts. However, these models do not provide information on bronchial wall thickness. This paper reports in vivo values of cross-sectional wall area, lumen area, wall thickness and lumen diameter in ten healthy subjects as assessed by multi-detector computed tomography. A validated dedicated software package was used to measure these morphometric parameters up to the 14th bronchial generation, with respect to Weibel's model of bronchial morphometry, and up to the 12th according to Boyden's classification. Measured lumen diameters and homothety ratios were compared with theoretical values obtained from previously published studies, and no difference was found when considering dichotomic division of the bronchial tree. Mean wall area, lumen area, wall thickness and lumen diameter were then provided according to bronchial generation order, and mean homothety ratios were computed for wall area, lumen area and wall thickness as well as equations giving the mean value of each parameter for a given bronchial generation with respect to its value in generation 0 (trachea). Multi-detector computed tomography measurements of bronchial morphometric parameters may help to improve our knowledge of bronchial anatomy in vivo, our understanding of the pathophysiology of bronchial diseases and the evaluation of pharmacological effects on the bronchial wall. PMID:17919291

Vertical regolith shield wall construction for lunar base applications

NASA Technical Reports Server (NTRS)

Kaplicky, Jan; Nixon, David; Wernick, Jane

1992-01-01

Lunar bases located on the lunar surface will require permanent protection from radiation and launch ejecta. This paper outlines a method of providing physical protection using lunar regolith that is constructed in situ as a modular vertical wall using specially devised methods of containment and construction. Deployable compartments, reinforced with corner struts, are elevated and filled by a moving gantry. The compartments interlock to form a stable wall. Different wall heights, thicknesses, and plan configurations are achieved by varying the geometry of the individual compartments, which are made from woven carbon fibers. Conventional terrestrial structural engineering techniques can be modified and used to establish the structural integrity and performance of the wall assembly.

Ultrasonographic wall thickness measurement of the upper and lower uterine segments in the prediction of the progress of preterm labour.

PubMed

Sayed Ahmed, W A; Madny, E H; Habash, Y H; Ibrahim, Z M; Morsy, A G K; Said, M E

2015-01-01

To assess the role of ultrasonographic measurement of the upper and lower uterine segments wall thickness in predicting the progress of preterm labour in patients presenting with preterm labour pains. Fifty pregnant women presenting at Obstetrics Department - Suez Canal University, Egypt with regular lower abdominal pains and diagnosed as having preterm labour were enrolled in the study. Measurements of the upper and lower uterine segments wall thickness by transabdominal ultrasonography in-between contractions and with full bladder were taken. The upper/lower uterine wall thickness ratio was calculated and correlated to the progress of the preterm labour and to the response to tocolytics. The ultrasonographic upper/lower uterine wall thickness ratio was directly related to the progress of preterm delivery (PTD). The change in this ratio is correlated inversely with the response to tocolysis. Using the ROC curve, when the upper/lower uterine wall thickness ratio was ≤ 1.26 the sensitivity was 94.74 and the specificity was 100.00, and when the ratio was ≤ 1.52 the sensitivity was 100.00 and the specificity was 83.33. These data may serve as a baseline ultrasonographic reference values for further studies in prediction the progress of preterm labour in patients presenting with preterm labour pains.

Relationship between Pipeline Wall Thickness (Gr. X60) and Water Depth towards Avoiding Failure during Installation

NASA Astrophysics Data System (ADS)

Razak, K. Abdul; Othman, M. I. H.; Mat Yusuf, S.; Fuad, M. F. I. Ahmad; yahaya, Effah

2018-05-01

Oil and gas today being developed at different water depth characterized as shallow, deep and ultra-deep waters. Among the major components involved during the offshore installation is pipelines. Pipelines are a transportation method of material through a pipe. In oil and gas industry, pipeline come from a bunch of line pipe that welded together to become a long pipeline and can be divided into two which is gas pipeline and oil pipeline. In order to perform pipeline installation, we need pipe laying barge or pipe laying vessel. However, pipe laying vessel can be divided into two types: S-lay vessel and J-lay vessel. The function of pipe lay vessel is not only to perform pipeline installation. It also performed installation of umbilical or electrical cables. In the simple words, pipe lay vessel is performing the installation of subsea in all the connecting infrastructures. Besides that, the installation processes of pipelines require special focus to make the installation succeed. For instance, the heavy pipelines may exceed the lay vessel’s tension capacities in certain kind of water depth. Pipeline have their own characteristic and we can group it or differentiate it by certain parameters such as grade of material, type of material, size of diameter, size of wall thickness and the strength. For instances, wall thickness parameter studies indicate that if use the higher steel grade of the pipelines will have a significant contribution in pipeline wall thickness reduction. When running the process of pipe lay, water depth is the most critical thing that we need to monitor and concern about because of course we cannot control the water depth but we can control the characteristic of the pipe like apply line pipe that have wall thickness suitable with current water depth in order to avoid failure during the installation. This research will analyse whether the pipeline parameter meet the requirements limit and minimum yield stress. It will overlook to simulate pipe

Method of controlling the side wall thickness of a turbine nozzle segment for improved cooling

DOEpatents

Burdgick, Steven Sebastian

2002-01-01

A gas turbine nozzle segment has outer and inner bands and a vane extending therebetween. Each band has a side wall, a cover and an impingement plate between the cover and nozzle wall defining two cavities on opposite sides of the impingement plate. Cooling steam is supplied to one cavity for flow through apertures of the impingement plate to cool the nozzle wall. The side wall of the band has an inturned flange defining with the nozzle wall an undercut region. The outer surface of the side wall is provided with a step prior to welding the cover to the side wall. A thermal barrier coating is applied in the step and, after the cover is welded to the side wall, the side wall is finally machined to a controlled thickness removing all, some or none of the coating.

Comparison between Carotid Artery Wall Thickness Measured by Multidetector Row Computed Tomography Angiography and Intimae-Media Thickness Measured by Sonography

PubMed Central

Savić, Živorad N.; Soldatović, Ivan I.; Brajović, Milan D.; Pavlović, Aleksandra M.; Mladenović, Dušan R.; Škodrić-Trifunović, Vesna D.

2011-01-01

The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA) in measuring carotid artery wall thickness (CAWT) and color Doppler ultrasound (CD-US) in measuring intimae-media thickness (IMT). Eighty-nine patients (aged 35–81) were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data were described as the mean value ± standard deviation, and were compared using the Mann–Whitney U test. A p value <0.05 was considered significant. Bland–Altman statistics were employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.62 to 1.60 mm, with a mean value of 1.09 mm. IMT ranged from 0.60 to 1.55 mm, with a mean value of 1.06 mm. We observed an excellent agreement between CD-US and MDCTA in the evaluation of the common carotid artery thickness, with a bias between methods of 0.029 mm (which is a highly statistically important difference of absolute values [t = 43.289; p < 0.01] obtained by paired T test), and limits of agreement from 0.04 to 0.104. Pearson correlation coefficient was 0.9997 (95% CI 0.9996–0.9998; p < 0.01). We conclude that there is an excellent correlation between CAWT and IMT measurements obtained with the MDCTA and CD-US. PMID:22224072

Risk Assessment of Abdominal Wall Thickness Measured on Pre-Operative Computerized Tomography for Incisional Surgical Site Infection after Abdominal Surgery.

PubMed

Tongyoo, Assanee; Chatthamrak, Putipan; Sriussadaporn, Ekkapak; Limpavitayaporn, Palin; Mingmalairak, Chatchai

2015-07-01

The surgical site infection (SSI) is a common complication of abdominal operation. It relates to increased hospital stay, increased healthcare cost, and decreased patient's quality of life. Obesity, usually defined by BMI, is known as one of the risks of SSI. However, the thickness of subcutaneous layers of abdominal wall might be an important local factor affecting the rate of SSI after the abdominal operations. The objective of this study is to assess the importance of the abdominal wall thickness on incisional SSI rate. The subjects of the present study were patients who had undergone major abdominal operations at Thammasat University Hospital between June 2013 and May 2014, and had been investigated with CT scans before their operations. The demographic data and clinical information of these patients were recorded. The thickness ofsubcutaneous fatty tissue from skin down to the most superficial layer of abdominal wall muscle at the surgical site was measured on CT images. The wound infectious complication was reviewed and categorized as superficial and deep incisional SSIfollowing the definition from Centersfor Disease Control and Prevention (CDC) guidelines. The significance ofeach potentialfactors on SSI rates was determined separately with student t-test for quantitative data and χ2-test for categorical data. Then all factors, which had p < 0.10, were included into the multivariate logistic regression analysis and were analyzed with significance at p < 0.05. One hundred and thirty-nine patients were included in this study. They all underwent major abdominal surgery and had had pre-operative CTscans. Post-operative SSI was 25.2% (35/139), superficial and deep types in 27 and 8 patients, respectively. The comparison of abdominal wall thickness between patients with and without infection was significantly different (20.0 ± 8.4 mm and 16.0 ± 7.2 mm, respectively). When the thickness at 20 mm was used as the cut-off value, 43 of 139 patients had abdominal wall

A thermoelastic transversely isotropic thick walled cylinder/disk application: An analytical solution and study

NASA Technical Reports Server (NTRS)

Arnold, S. M.

1989-01-01

A continuum theory is utilized to represent the thermoelastic behavior of a thick walled composite cylinder that can be idealized as transversely isotropic. A multiaxial statement of the constitutive theory employed is presented, as well as the out of the plane of isotropy, plane stress, and plane strain reductions. The derived analytical solution presented is valid for a cylindrical tube or thin disk with a concentric hole, subjected to internal and/or external pressure and a general radial temperature distribution. A specific problem examined is that of a thick walled cylinder subjected to an internal and external pressure loading and a linear radial temperature distribution. The results are expressed in nondimensional form and the effects on the response behavior are examined for various material properties, fiber orientation and types of loadings.

Thickness-dependent domain wall reorientation in 70/30 lead magnesium niobate- lead titanate thin films

DOE PAGES

Keech, Ryan; Morandi, Carl; Wallace, Margeaux; ...

2017-04-11

Continued reduction in length scales associated with many ferroelectric film-based technologies is contingent on retaining the functional properties as the film thickness is reduced. Epitaxial and polycrystalline lead magnesium niobate - lead titanate (70PMN-30PT) thin films were studied over the thickness range of 100-350 nm for the relative contributions to property thickness dependence from interfacial and grain boundary low permittivity layers. Epitaxial PMN-PT films were grown on SrRuO 3 /(001)SrTiO 3, while polycrystalline films with {001}-Lotgering factors >0.96 were grown on Pt/TiO 2/SiO 2/Si substrates via chemical solution deposition. Both film types exhibited similar relative permittivities of ~300 at highmore » fields at all measured thicknesses with highly crystalline electrode/dielectric interfaces. These results, with the DC-biased and temperature dependent dielectric characterization, suggest irreversible domain wall mobility is the major contributor to the overall dielectric response and its thickness dependence. In epitaxial films, the irreversible Rayleigh coefficients reduced 85% upon decreasing thickness from 350 to 100 nm. The temperature at which a peak in the relative permittivity is observed was the only measured small signal quantity which was more thickness dependent in polycrystalline than epitaxial films. This is attributed to the relaxor nature present in the films, potentially stabilized by defect concentrations, and/or chemical inhomogeneity. Finally, the effective interfacial layers are found to contribute to the measured thickness dependence in the longitudinal piezoelectric coefficient.« less

Noninvasive evaluation of gastric emptying and gastric wall thickness in SLE patients.

PubMed

Shen, Hao-Lin; Yang, Shu-Ping; Wang, Kang-Jian; Huang, Bei-Lei; Huang, Wen-Bao; Wu, Jin-Zhi; Lyu, Guo-Rong

2017-04-01

The objective of this study is to evaluate the gastric emptying in patients with systemic lupus erythematosus (SLE) with gastrointestinal involvement using three-dimensional (3D) ultrasonography. The gastric emptying times at 25% (T1), 50% (T2), and 75% (T3) of SLE patients with gastrointestinal involvement (n = 40) and healthy controls (n = 80) were evaluated and compared. In addition, the correlations among the gastric wall thickness, SLE disease activity index (SLEDAI), and upper gastrointestinal symptoms were calculated. The gastric wall thickness was correlated with the SLEDAI (r = 0.928, p < 0.001) and the upper gastrointestinal symptom index (r = 0.848, p < 0.001). The emptying times T1, T2, and T3 of the SLE patients were 17.08 ± 2.65 min (mean ± standard deviation), 39.85 ± 6.54 min, and 83.58 ± 7.12 min, respectively. For healthy controls, they were 19.65 ± 5.39 min, 41.08 ± 7.51 min, and 70.34 ± 8.03 min. The T1 of the SLE patients was shorter (p < 0.01), while the T3 was longer (p < 0.001). Moreover, T3 in the SLE group had the best correlation with the upper gastrointestinal symptom index (r = 0.553, p < 0.001). T1 in the SLE group was anti-correlated with early satiety (r = -0.366, p < 0.05). Combining the emptying times T1 and T3, as well as the gastric wall thickness, the SLEDAI and the upper gastrointestinal symptoms index can provide accurate clinical diagnosis of SLE with gastric involvement.

The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis.

PubMed

Goebel, Paul; Kluess, Daniel; Wieding, Jan; Souffrant, Robert; Heyer, Horst; Sander, Manuela; Bader, Rainer

2013-03-01

To increase the range of motion of total hip endoprostheses, prosthetic heads need to be enlarged, which implies that the cup and/or liner thickness must decrease. This may have negative effects on the wear rate, because the acetabular cups and liners could deform during press-fit implantation and hip joint loading. We compared the metal cup and polyethylene liner deformations that occurred when different wall thicknesses were used in order to evaluate the resulting changes in the clearance of the articulating region. A parametric finite element model utilized three cup and liner wall thicknesses to analyze cup and liner deformations after press-fit implantation into the pelvic bone. The resultant hip joint force during heel strike was applied while the femur was fixed, accounting for physiological muscle forces. The deformation behavior of the liner under joint loading was therefore assessed as a function of the head diameter and the resulting clearance. Press-fit implantation showed diametral cup deformations of 0.096, 0.034, and 0.014 mm for cup wall thicknesses of 3, 5, and 7 mm, respectively. The largest deformations (average 0.084 ± 0.003 mm) of liners with thicknesses of 4, 6, and 8 mm occurred with the smallest cup wall thickness (3 mm). The smallest liner deformation (0.011 mm) was obtained with largest cup and liner wall thicknesses. Under joint loading, liner deformations in thin-walled acetabular cups (3 mm) reduced the initial clearance by about 50 %. Acetabular press-fit cups with wall thicknesses of ≤5 mm should only be used in combination with polyethylene liners >6 mm thick in order to minimize the reduction in clearance.

Thinner regions of intracranial aneurysm wall correlate with regions of higher wall shear stress: a 7.0 tesla MRI

PubMed Central

Blankena, Roos; Kleinloog, Rachel; Verweij, Bon H.; van Ooij, Pim; ten Haken, Bennie; Luijten, Peter R.; Rinkel, Gabriel J.E.; Zwanenburg, Jaco J.M.

2016-01-01

Purpose To develop a method for semi-quantitative wall thickness assessment on in vivo 7.0 tesla (7T) MRI images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress. Materials and Methods Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients, who underwent 7T MRI with a TSE based vessel wall sequence (0.8 mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to signal of nearby brain tissue and were used as measure for apparent wall thickness (AWT). Spatial wall thickness variation was determined as the interquartile range in AWT (the middle 50% of the AWT range). Wall shear stress was determined using phase contrast MRI (0.5 mm isotropic resolution). We performed visual and statistical comparisons (Pearson’s correlation) to study the relation between wall thickness and wall shear stress. Results 3D colored AWT maps of the aneurysms showed spatial AWT variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of one voxel (0.8mm)). In all aneurysms, AWT was inversely related to WSS (mean correlation coefficient −0.35, P<0.05). Conclusions A method was developed to measure the wall thickness semi-quantitatively, using 7T MRI. An inverse correlation between wall shear stress and AWT was determined. In future studies, this non-invasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and –rupture. PMID:26892986

Clinical efficiency of Piezo-ICSI using micropipettes with a wall thickness of 0.625 μm.

PubMed

Hiraoka, Kenichiro; Kitamura, Seiji

2015-12-01

The purposes of the present study are to assess the clinical efficiency of Piezo-intracytoplasmic sperm injection (ICSI) and to improve the Piezo-ICSI method for human oocytes. We examined three ICSI methods to determine their clinical efficiency by comparing the survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates. The three ICSI methods tested were conventional ICSI (CI) (using beveled spiked micropipettes with a wall thickness of 1 μm), conventional Piezo-ICSI (CPI) (using flat-tipped micropipettes with a wall thickness of 0.925 μm), and improved Piezo-ICSI (IPI) (using flat-tipped micropipettes with a wall thickness of 0.625 μm). We collectively investigated 2020 mature oocytes retrieved from 437 patients between October 2010 and January 2014. The survival rates after CI, CPI, and IPI were 90, 95, and 99 %, respectively. The fertilization rates after CI, CPI, and IPI were 68, 75, and 89 %, respectively. The good-quality day-3 embryo rates after CI, CPI, and IPI were 37, 43, and 55 %, respectively. The pregnancy rates after the transfer of good-quality day-3 embryo of CI, CPI, and IPI were 19, 21, and 31 %, respectively. The live birth rates of CI, CPI, and IPI were 15, 16, and 25 %, respectively. Significantly higher survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates were obtained using IPI. When comparing the IPI to the CI and CPI, the results revealed that the Piezo-ICSI using flat-tipped micropipettes with a wall thickness of 0.625 μm significantly improves survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates.

Sarcocystis sinensis is the most prevalent thick-walled Sarcocystis species in beef on sale for consumers in Germany.

PubMed

Moré, G; Pantchev, A; Skuballa, J; Langenmayer, M C; Maksimov, P; Conraths, F J; Venturini, M C; Schares, G

2014-06-01

Bovines are intermediate hosts of Sarcocystis cruzi, Sarcocystis hirsuta, and Sarcocystis hominis, which use canids, felids, or primates as definitive hosts, respectively. Cattle represent also intermediate hosts of Sarcocystis sinensis, but the definitive hosts of this parasite are not yet known. Sarcocystosis in cattle is frequently asymptomatic. The infection is characterized by the presence of thin-walled (S. cruzi) or thick-walled muscle cysts or sarcocysts (S. hominis, S. sinensis, and S. hirsuta). Recent reports suggest high prevalence of the zoonotic S. hominis in beef in Europe. We therefore aimed at differentiating Sarcocystis spp. in beef offered to consumers in Germany using molecular and microscopical methods, focusing on those species producing thick-walled sarcocysts. A total of 257 beef samples were obtained from different butcheries and supermarkets in Germany and processed by conventional and multiplex real-time PCR. In addition, 130 of these samples were processed by light microscopy and in 24.6% thick-walled cysts were detected. Transmission electron microscopical analysis of six of these samples revealed an ultrastructural cyst wall pattern compatible with S. sinensis in five samples and with S. hominis in one sample. PCR-amplified 18S ribosomal DNA (rDNA) fragments of 28 individual thick-walled cysts were sequenced, and sequence identities of ≥98% with S. sinensis (n = 22), S. hominis (n = 5) and S. hirsuta (n = 1) were observed. Moreover, nine Sarcocystis sp. 18S rDNA full length gene sequences were obtained, five of S. sinensis, three of S. hominis, and one of S. hirsuta. Out of all samples (n = 257), 174 (67.7%) tested positive by conventional PCR and 179 (69.6%) by multiplex real-time PCR for Sarcocystis spp. Regarding individual species, 134 (52%), 95 (37%), 17 (6.6%), and 16 (6.2%) were positive for S. cruzi, S. sinensis, S. hirsuta, and S. hominis, respectively. In conclusion, S. sinensis is the most prevalent thick-walled

Charged magnetic domain walls as observed in nanostructured thin films: dependence on both film thickness and anisotropy.

PubMed

Favieres, C; Vergara, J; Madurga, V

2013-02-13

The magnetic domain configurations of soft magnetic, nanostructured, pulsed laser-deposited Co films were investigated. Their dependence on both the thickness t (20 nm ≤ t ≤ 200 nm) and the anisotropy was studied. Charged zigzag walls, with a characteristic saw-tooth vertex angle θ, were observed. θ changed with t from θ ≈ 17° to ≈25°, presenting an intermediate sharp maximum that has not been described before. The reduced length of the zigzag walls also exhibited a peak at t ≈ 70 nm. The relationship between the total reduced length and the density energy of the magnetic wall allowed us to establish a change from a Néel-type to a Bloch-type core of the zigzag walls at this thickness, t ≈ 70 nm. We also accounted for the magnetic energy arising from the surface roughness of the thinner films after imaging the film surface morphologies. Moreover, this distinctive behaviour of the zigzag walls of these low-anisotropy films was compared to that of high-anisotropy films.

Tissue factor levels and the fibrinolytic system in thin and thick intraluminal thrombus and underlying walls of abdominal aortic aneurysms.

PubMed

Siennicka, Aldona; Zuchowski, Marta; Kaczmarczyk, Mariusz; Cnotliwy, Miłosław; Clark, Jeremy Simon; Jastrzębska, Maria

2018-03-20

The hemostatic system cooperates with proteolytic degradation in processes allowing abdominal aortic aneurysm (AAA) formation. In previous studies, it has been suggested that aneurysm rupture depends on intraluminal thrombus (ILT) thickness, which varies across each individual aneurysm. We hypothesized that hemostatic components differentially accumulate in AAA tissue in relation to ILT thickness. Thick (A1) and thin (B1) segments of ILTs and aneurysm wall sections A (adjacent to A1) and B (adjacent to B1) from one aneurysm sac were taken from 35 patients undergoing elective repair. Factor levels were measured using enzyme-linked immunosorbent assay of protein extract. Tissue factor (TF) activities were significantly higher in thinner segments of AAA (B1 vs A1, P = .003; B vs A, P < .001; B vs A1, P < .001; B vs B1, P = .001). Significantly higher tissue plasminogen activator was found in thick thrombus-covered wall segments (A) than in B, A1, and B1 (P = .015, P < .001, and P < .001, respectively). Plasminogen concentrations were highest in ILT. Concentrations of α 2 -antiplasmin in thin ILT adjacent walls (B) were higher compared with wall (A) adjacent to thick ILT (P = .021) and thick ILT (A1; P < .001). Significant correlations between levels of different factors were mostly found in thick ILT (A1). However, no correlations were found at B sites, except for a correlation between plasmin and TF activities (r = 0.55; P = .004). These results suggest that higher TF activities are present in thinner AAA regions. These parameters and local fibrinolysis may be part of the processes leading to destruction of the aneurysm wall. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

CMR assessment of the left ventricle apical morphology in subjects with unexplainable giant T-wave inversion and without apical wall thickness ≥15 mm.

PubMed

Wu, Bailin; Lu, Minjie; Zhang, Yan; Song, Bo; Ling, Jian; Huang, Jinghan; Yin, Gang; Lan, Tian; Dai, Linlin; Song, Lei; Jiang, Yong; Wang, Hao; He, Zuoxiang; Lee, Jongmin; Yong, Hwan Seok; Patel, Mehul B; Zhao, Shihua

2017-02-01

Patients with unexplainable giant T-wave inversion in the precordial leads and apical wall thickness <15 mm have been reported. These patients cannot be diagnosed as apical hypertrophic cardiomyopathy (AHCM) according to the current criteria. The objective of this study was to evaluate the apical morphological features of this type of patients using cardiac magnetic resonance. Institutional ethics approval and written informed consent were obtained. A total of 60 subjects with unexplainable giant T-wave inversion and 76 healthy volunteers were prospectively enrolled in the study. The segmented left ventricular (LV) wall thickness was measured according to the American Heart Association 17-segmented model. The apical angle (apA) as well as the regional variations in LV wall thickness was analysed. Considerable variation in LV wall thickness in normals was observed with progressive thinning from the base to apex (male and female, P < 0.01). The apical thickness of subjects with giant T-wave inversion was 8.10 ± 1.67 mm in male, which is thicker than that of controls (4.14 ± 1.17 mm, P < 0.01). In female, the apical thickness was also significantly different from controls (5.85 ± 2.16 vs. 2.99 ± 0.65 mm, P < 0.01). Compared with normals, the apA decreased significantly in male (87.44 ± 13.86 vs.115.03 ± 9.90°, P < 0.01) and female (90.69 ± 8.84 vs. 110.07 ± 13.58°, P < 0.01) subjects, respectively. Although the absolute thickness of apical wall was below the current diagnostic criteria of AHCM, the apical morphological features of subjects with unexplainable giant T-wave inversion were significantly different from normals. Whether these subjects should be included into a preclinical scope of AHCM needs further investigations. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Measurement of three-dimensional normal vectors, principal curvatures, and wall thickness of the heart using cine-MRI

NASA Astrophysics Data System (ADS)

Coghlan, Leslie; Singleton, H. R.; Dell'Italia, L. J.; Linderholm, C. E.; Pohost, G. M.

1995-05-01

We have developed a method for measuring the detailed in vivo three dimensional geometry of the left and right ventricles using cine-magnetic resonance imaging. From data in the form of digitized short axis outlines, the normal vectors, principal curvatures and directions, and wall thickness were computed. The method was evaluated on simulated ellipsoids and on human MRI data. Measurements of normal vectors and of wall thickness were very accurate in simulated data and appeared appropriate in patient data. On simulated data, measurements of the principal curvature k1 (corresponding approximately to the short axis direction of the left ventricle) and of principal directions were quite accurate, but measurements of the other principal curvature (k2) were less accurate. The reasons behind this are considered. We expect improvements in the accuracy with thinner slices and improved representation of the surface data. Gradient echo images were acquired from 8 dogs with a 1.5T system (Philips Gyroscan) at baseline and four months after closed chest experimentally produced mitral regurgitation (MR). The product (k1 + k2) X wall thickness averaged over all slices at end-diastole was significantly lower after surgery (n equals 8, p < 0.005). These geometry changes were consistent with the expected increase in wall stress after MR.

Effects of thickness, insulation, and surface color on the net heat loss through an adobe wall

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

Herman, R.W.

1980-01-01

A finite difference computer program was written and run to study the net thermal losses through a large variety of adobe walls. Fifty-four different combinations of surface color, wall thickness, and insulation position and R value were modeled over a typical two week winter period for locations similar to Albuquerque, New Mexico. A transient analysis of the heat loss from the room to the interior wall surface was compared to both conventional U value and steady-state calculations.

SU-E-T-571: Prostate IMRT QA: Prediction of the Range of Rectal NTCP Using a 2D Field Approach Based on Variations of the Rectal Wall Motion and Thickness.

PubMed

Grigorov, G; Chow, J; Foster, K

2012-06-01

The aims of this study is to (1) introduce a 2D field of possible rectal normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) plan, so that based on a given prescribed dose the rectal NTCP is merely a function of the rectal wall thickness and rectal motion; and (2) separate the 2D field of rectal NTCP into area of low risk and area of high risk for rectal toxicity < Grade II, based on the threshold rectal NTCP. The 2D field of NTCP model was developed using ten randomly selected prostate IMRT plans. The clinical rectal geometry was initially represented by the cylindrical contour in the treatment planning system. Different combinations of rectal motions, rectal wall thicknesses, planning target volume margins and prescribed doses were used to determine the NTCP in prostate IMRT plans. It was found that the functions bordering the 2D field for the given AP, LR and SI direction can be described as exponential, quadratic and linear equations, respectively. A ratio of the area of 2D field containing data of the low risk NTCP to the entire area of the field was introduced and calculated. Although our method is based on the Kutcher's dose response model and published tissue parameters, other mathematical models can be used in our approach. The 2D field of rectal NTCP is useful to estimate the rectal NTCP range in the prostate pre-treatment and treatment QA. Our method can determine the patient's threshold immobilization for a given rectal wall thickness so that prescribed dose can be delivered to the prostate to avoid rectal complication. Our method is also applicable to multi-phase prostate IMRT, and can be adapted to any treatment planning systems. © 2012 American Association of Physicists in Medicine.

Huge domain-wall speed variation with respect to ferromagnetic layer thickness in ferromagnetic Pt/Co/TiO2/Pt films

NASA Astrophysics Data System (ADS)

Kim, Dae-Yun; Park, Min-Ho; Park, Yong-Keun; Yu, Ji-Sung; Kim, Joo-Sung; Kim, Duck-Ho; Min, Byoung-Chul; Choe, Sug-Bong

2018-02-01

In this study, we investigate the influence of the ferromagnetic layer thickness on the magnetization process. A series of ultrathin Pt/Co/TiO2/Pt films exhibits domain-wall (DW) speed variation of over 100,000 times even under the same magnetic field, depending on the ferromagnetic layer thickness. From the creep-scaling analysis, such significant variation is found to be mainly attributable to the thickness-dependence of the creep-scaling constant in accordance with the creep-scaling theory of the linear proportionality between the creep-scaling constant and the ferromagnetic layer thickness. Therefore, a thinner film shows a faster DW speed. The DW roughness also exhibits sensitive dependence on the ferromagnetic layer thickness: a thinner film shows smoother DW. The present observation provided a guide for an optimal design rule of the ferromagnetic layer thickness for better performance of DW-based devices.

Ceramic inlays and partial ceramic crowns: influence of remaining cusp wall thickness on the marginal integrity and enamel crack formation in vitro.

PubMed

Krifka, Stephanie; Anthofer, Thomas; Fritzsch, Marcus; Hiller, Karl-Anton; Schmalz, Gottfried; Federlin, Marianne

2009-01-01

No information is currently available about what the critical cavity wall thickness is and its influence upon 1) the marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and 2) the crack formation of dental tissues. This in vitro study of CI and PCC tested the effects of different remaining cusp wall thicknesses on marginal integrity and enamel crack formation. CI (n = 25) and PCC (n = 26) preparations were performed in extracted human molars. Functional cusps of CI and PCC were adjusted to a 2.5 mm thickness; for PCC, the functional cusps were reduced to a thickness of 2.0 mm. Non-functional cusps were adjusted to wall thicknesses of 1) 1.0 mm and 2) 2.0 mm. Ceramic restorations (Vita Mark II, Cerec3 System) were fabricated and adhesively luted to the cavities with Excite/Variolink II. The specimens were exposed to thermocycling and central mechanical loading (TCML: 5000 x 5 degrees C-55 degrees C; 30 seconds/cycle; 500000 x 72.5N, 1.6Hz). Marginal integrity was assessed by evaluating a) dye penetration (fuchsin) on multiple sections after TCML and by using b) quantitative margin analysis in the scanning electron microscope (SEM) before and after TCML. Ceramic- and tooth-luting agent interfaces (LA) were evaluated separately. Enamel cracks were documented under a reflective light microscope. The data were statistically analyzed with the Mann Whitney U-test (alpha = 0.05) and the Error Rates Method (ERM). Crack formation was analyzed with the Chi-Square-test (alpha = 0.05) and ERM. In general, the remaining cusp wall thickness, interface, cavity design and TCML had no statistically significant influence on marginal integrity for both CI and PCC (ERM). Single pairwise comparisons showed that the CI and PCC of Group 2 had a tendency towards less microleakage along the dentin/LA interface than Group 1. Cavity design and location had no statistically significant influence on crack formation, but the specimens with 1.0 mm of remaining wall

Analysis of the effects of gravity and wall thickness in a model of blood flow through axisymmetric vessels.

PubMed

Payne, S J

2004-11-01

The effects of gravitational forces and wall thickness on the behaviour of a model of blood flow through axisymmetric vessels were studied. The governing fluid dynamic equations were derived from the Navier-Stokes equations for an incompressible fluid and linked to a simple model of the vessel wall. A closed form of the hyperbolic partial differential equations was found, including a significant source term from the gravitational forces. The inclination of the vessel is modelled using a slope parameter that varied between -1 and 1. The wave speed was shown to be related to the wall thickness, and the time to first shock formation was shown to be directly proportional to this thickness. Two non-dimensional parameters were derived for the ratio of gravitational forces to viscous and momentum forces, respectively, and their values were calculated for the different types of vessel found in the human vasculature, showing that gravitational forces were significant in comparison with either viscous or momentum forces for every type of vessel. The steady-state solution of the governing equations showed that gravitational forces cause an increase in area of approximately 5% per metre per unit slope. Numerical simulations of the flow field in the aorta showed that a positive slope causes a velocity pulse to change in amplitude approximately linearly with distance: -4% per metre and +5% per metre for vessels inclined vertically upwards and downwards, respectively, in comparison with only +0.5% for a horizontal vessel. These simulations also showed that the change relative to the zero slope condition in the maximum rate of change of area with distance, which was taken to be a measure of the rate of shock formation, is proportional to both the slope and the wall thickness-to-inner radius ratio, with a constant of proportionality of 1.2. At a ratio of 0.25, typical of that found in human arteries, the distance to shock formation is thus decreased and increased by 30% for vessels

Stress intensity factors in a reinforced thick-walled cylinder

NASA Technical Reports Server (NTRS)

Tang, R.; Erdogan, F.

1984-01-01

An elastic thick-walled cylinder containing a radial crack is considered. It is assumed that the cylinder is reinforced by an elastic membrane on its inner surface. The model is intended to simulate pressure vessels with cladding. The formulation of the problem is reduced to a singular integral equation. Various special cases including that of a crack terminating at the cylinder-reinforcement interface are investigated and numerical examples are given. Results indicate that in the case of the crack touching the interface the crack surface displacement derivative is finite and consequently the stress state around the corresponding crack tip is bounded; and generally, for realistic values of the stiffness parameter, the effect of the reinforcement is not very significant.

Ultrasound Thickness of Bladder Wall in Continent and Incontinent Women and Its Correlation with Cystometry

PubMed Central

Otsuki, Edney Norio; Oliveira, Emerson; Sartori, Marair Gracio Ferreira; Girão, Manoel João Batista Castelo; Jármy-Di Bella, Zsuzsanna Ilona Katalin

2014-01-01

Objective. To compare bladder wall thickness in two kinds of urinary incontinent women—stress urinary incontinence (SUI) and overactive bladder (OAB) with urodynamic detrusor overactivity (DO), and to compare them with continent patients by ultrasound, also, correlate with cystometric results in incontinent women. Methods. 91 women were divided into the following groups: continent (n = 31), SUI (n = 30), and DO (n = 30) groups after clinical evaluation and urodynamic test (only in incontinent women). Transvaginal ultrasound was performed to the bladder wall thickness (BWT) measurement. The mean of BWT was calculated and data were analyzed with ANOVA and Turkey's multiple comparison tests. Pearson's correlation coefficient (r) was used to compare two variables. Receiver operating characteristic (ROC) curve was performed to study BWT as a diagnostic parameter. Results. BWT in DO group was significantly higher than that in the other groups (P < 0.005). A moderate positive correlation was found between BWT and maximum bladder pressure during involuntary bladder contraction. There was no difference in BWT between SUI and continent groups. DO group had lower first desire to void and cystometric capacity. Maximum bladder pressure at detrusor contraction had a moderate positive correlation with BWT. The ROC revealed an area under the curve of 0.962 (95% CI, 0.90–1.01). Conclusions. DO patients have increased bladder wall thickness, lower first desire to void, and lower cystometric capacity. There was a moderate correlation between BWT and maximum bladder pressure during involuntary bladder contraction. PMID:25538959

Fracture resistance of welded thick-walled high-pressure vessels in power plants. Report No. 2. Approach to evaluating static strength

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

Gorynin, I.V.; Filatov, V.M.; Ignatov, V.A.

1986-07-01

The authors examine data on the effect of defects on the fracture resistance of high-pressure vessels and their models obtained within the framework of the HSST program. Results of internal-pressure tests of two types of vessels with a wall thickness of 152 mm made from forgings of steels SA508 and SA533, as well as small vessels with a wall thickness of 11.5 and 23mm made of steel SA533 are shown. The authors state that testing thick-walled welded high-pressure vessels and thin-walled vessels with surface defects of different sizes has demonstrated that there are substantial static-strength reserves in structures designed bymore » existing domestic and foreign standards on the strength of power-plant equipment. A correction was proposed for the presently used method of calculating the resistance of highpressure vessels to brittle fracture that allows for the dimensions of the defects in relation to the type of vessel, the manufacturing technology, and the method of inspection.« less

The effect of fig wall thickness in Ficus erecta var. beecheyana on parasitism

NASA Astrophysics Data System (ADS)

Tzeng, Hsy-Yu; Ou, Chern-Hsiung; Lu, Fu-Yuan; Bain, Anthony; Chou, Lien-Siang; Kjellberg, Finn

2014-05-01

Fig wasp communities constitute a model system to analyse determinants of community complexity and to investigate how biological interaction networks are maintained. It has been suggested for monoecious figs, that fig pollinating wasps avoid ovipositing in flowers located close to the fig wall because of strong parasitic pressure by wasps ovipositing through the fig wall. This behaviour could help explain why mainly seeds are produced in flowers located close to the fig wall, thus stabilizing the fig-pollinating wasp mutualism. In this contribution we explore, for dioecious figs, whether ovipositor length of parasitic species may really be limiting. In dioecious figs, functionally male figs produce pollinating wasps and pollen while female figs produce only seeds, facilitating selection of traits favouring pollinator reproduction in male figs. We show in Ficus erecta that fig walls are thicker in male figs than in female figs. Male figs presenting thick walls, thicker than the length of the parasites' ovipositors, went unparasitized while male figs presenting thinner walls were systematically parasitized. Hence, in F. erecta, ovipositor length of the parasites is limiting access to some figs. However, we also show that in another dioecious species, Ficus formosana, presenting thin walled male figs, no fig is protected against oviposition by its two parasites. Hence in dioecious as well as in monoecious figs, in some Ficus species, ovipositors of the parasites are limiting access to ovules, while in other Ficus species all ovules are exposed to parasitism.

Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

NASA Astrophysics Data System (ADS)

Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

2018-05-01

A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

Impact of Age and Aerobic Exercise Training on Conduit Artery Wall Thickness: Role of the Shear Pattern.

PubMed

Tanahashi, Koichiro; Kosaki, Keisei; Sawano, Yuriko; Yoshikawa, Toru; Tagawa, Kaname; Kumagai, Hiroshi; Akazawa, Nobuhiko; Maeda, Seiji

2017-01-01

Hemodynamic shear stress is the frictional force of blood on the arterial wall. The shear pattern in the conduit artery affects the endothelium and may participate in the development and progression of atherosclerosis. We investigated the role of the shear pattern in age- and aerobic exercise-induced changes in conduit artery wall thickness via cross-sectional and interventional studies. In a cross-sectional study, we found that brachial shear rate patterns and brachial artery intima-media thickness (IMT) correlated with age. Additionally, brachial artery shear rate patterns were associated with brachial artery IMT in 102 middle-aged and older individuals. In an interventional study, 39 middle-aged and older subjects were divided into 2 groups: control and exercise. The exercise group completed 12 weeks of aerobic exercise training. Aerobic exercise training significantly increased the antegrade shear rate and decreased the retrograde shear rate and brachial artery IMT. Moreover, changes in the brachial artery antegrade shear rate and the retrograde shear rate correlated with the change in brachial artery IMT. The results of the present study indicate that changes in brachial artery shear rate patterns may contribute to age- and aerobic exercise training-induced changes in brachial artery wall thickness. © 2017 S. Karger AG, Basel.

Diffusion capacity and CT measures of emphysema and airway wall thickness - relation to arterial oxygen tension in COPD patients.

PubMed

Saure, Eirunn Waatevik; Bakke, Per Sigvald; Lind Eagan, Tomas Mikal; Aanerud, Marianne; Jensen, Robert Leroy; Grydeland, Thomas Blix; Johannessen, Ane; Nilsen, Roy Miodini; Thorsen, Einar; Hardie, Jon Andrew

2016-01-01

Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness. To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry. The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas<-950 Hounsfield units (%LAA), and airway wall thickness as standardised measure at an internal perimeter of 10 mm (AWT-Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, AWT-Pi10, DLCO and carbon monoxide transfer coefficient (KCO) as main explanatory variables. The models were adjusted for sex, age, smoking status, and haemoglobin concentration, as well as forced expiratory volume in one second (FEV1). Sixty two per cent of the subjects were men, mean (SD) age was 64 (7) years, mean (SD) FEV1 in percent predicted was 50 (15)%, and mean PaO2 (SD) was 9.3 (1.1) kPa. The adjusted regression coefficient (CI) for PaO2 was -0.32 (-0.04-(-0.019)) per 10% increase in %LAA (p<0.01). When diffusion capacity and FEV1 were added to the model, respectively, the association lost its statistical significance. No relationship between airway wall thickness and PaO2 was found. CT assessment of airway wall thickness is not associated with arterial oxygen tension in COPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia.

Modeling thermal performance of exterior walls retrofitted from insulation and modified laterite based bricks materials

NASA Astrophysics Data System (ADS)

Wati, Elvis; Meukam, Pierre; Damfeu, Jean Claude

2017-12-01

Uninsulated concrete block walls commonly found in tropical region have to be retrofitted to save energy. The thickness of insulation layer used can be reduced with the help of modified laterite based bricks layer (with the considerably lower thermal conductivity than that of concrete block layer) during the retrofit building fabrics. The aim of this study is to determine the optimum location and distribution of different materials. The investigation is carried out under steady periodic conditions under the climatic conditions of Garoua in Cameroon using a Simulink model constructed from H-Tools (the library of Simulink models). Results showed that for the continuous air-conditioned space, the best wall configuration from the maximum time lag, minimum decrement factor and peak cooling transmission load perspective, is dividing the insulation layer into two layers and placing one at the exterior surface and the other layer between the two different massive layers with the modified laterite based bricks layer at the interior surface. For intermittent cooling space, the best wall configuration from the minimum energy consumption depends on total insulation thickness. For the total insulation thickness less than 8 cm approximately, the best wall configuration is placing the half layer of insulation material at the interior surface and the other half between the two different massive layers with the modified earthen material at the exterior surface. Results also showed that, the optimum insulation thickness calculated from the yearly cooling transmission (estimated only during the occupied period) and some economic considerations slightly depends on the location of that insulation.

Enhanced washout of 99mTc-tetrofosmin in hypertrophic cardiomyopathy: quantitative comparisons with regional 123I-BMIPP uptake and wall thickness determined by MRI.

PubMed

Thet-Thet-Lwin; Takeda, Tohoru; Wu, Jin; Fumikura, Yuko; Iida, Keiji; Kawano, Satoru; Yamaguchi, Iwao; Itai, Yuji

2003-07-01

The diagnostic value of technetium-99m tetrofosmin (TF) washout in hypertrophic cardiomyopathy (HCM) was examined by investigating its relation to the metabolic abnormality depicted by iodine-123 beta-methyl- p-iodophenylpentadecanoic acid (BMIPP) uptake and the left ventricular (LV) myocardial wall thickness as measured by magnetic resonance imaging (MRI). TF washout was evaluated in 31 patients with HCM and 23 normal control subjects using 30-min (early) and 3-h (delayed) TF single-photon emission tomography images. The LV myocardial wall was divided into 19 segments and the percentage TF washout, regional BMIPP uptake and LV wall thickness were measured in each segment. Mean TF washout in the patients with HCM was significantly faster than that in normal control subjects (23.7+/-5.7 vs 13.4+/-4.1, P<0.0001). In the patients with HCM, TF washout showed an excellent correlation with MRI wall thickness ( r=0.82, P<0.0001) and a good inverse correlation with regional BMIPP uptake ( r=-0.72, P<0.0001). In addition, a good linear correlation was observed between TF uptake and MRI wall thickness in the 19 regional segments. In conclusion, the degree of TF washout corresponds well with the severity of myocardial wall thickness and the degree of metabolic abnormality in patients with HCM. These results suggest that enhanced TF washout might provide additional clinical information regarding metabolic alterations in HCM.

The effect of wall thickness distribution on mechanical reliability and strength in unidirectional porous ceramics.

PubMed

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J

2016-01-01

Macroporous ceramics exhibit an intrinsic strength variability caused by the random distribution of defects in their structure. However, the precise role of microstructural features, other than pore volume, on reliability is still unknown. Here, we analyze the applicability of the Weibull analysis to unidirectional macroporous yttria-stabilized-zirconia (YSZ) prepared by ice-templating. First, we performed crush tests on samples with controlled microstructural features with the loading direction parallel to the porosity. The compressive strength data were fitted using two different fitting techniques, ordinary least squares and Bayesian Markov Chain Monte Carlo, to evaluate whether Weibull statistics are an adequate descriptor of the strength distribution. The statistical descriptors indicated that the strength data are well described by the Weibull statistical approach, for both fitting methods used. Furthermore, we assess the effect of different microstructural features (volume, size, densification of the walls, and morphology) on Weibull modulus and strength. We found that the key microstructural parameter controlling reliability is wall thickness. In contrast, pore volume is the main parameter controlling the strength. The highest Weibull modulus ([Formula: see text]) and mean strength (198.2 MPa) were obtained for the samples with the smallest and narrowest wall thickness distribution (3.1 [Formula: see text]m) and lower pore volume (54.5%).

The effect of wall thickness distribution on mechanical reliability and strength in unidirectional porous ceramics

NASA Astrophysics Data System (ADS)

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

2016-01-01

Macroporous ceramics exhibit an intrinsic strength variability caused by the random distribution of defects in their structure. However, the precise role of microstructural features, other than pore volume, on reliability is still unknown. Here, we analyze the applicability of the Weibull analysis to unidirectional macroporous yttria-stabilized-zirconia (YSZ) prepared by ice-templating. First, we performed crush tests on samples with controlled microstructural features with the loading direction parallel to the porosity. The compressive strength data were fitted using two different fitting techniques, ordinary least squares and Bayesian Markov Chain Monte Carlo, to evaluate whether Weibull statistics are an adequate descriptor of the strength distribution. The statistical descriptors indicated that the strength data are well described by the Weibull statistical approach, for both fitting methods used. Furthermore, we assess the effect of different microstructural features (volume, size, densification of the walls, and morphology) on Weibull modulus and strength. We found that the key microstructural parameter controlling reliability is wall thickness. In contrast, pore volume is the main parameter controlling the strength. The highest Weibull modulus (?) and mean strength (198.2 MPa) were obtained for the samples with the smallest and narrowest wall thickness distribution (3.1 ?m) and lower pore volume (54.5%).

Agreement between methods of measurement of mean aortic wall thickness by MRI.

PubMed

Rosero, Eric B; Peshock, Ronald M; Khera, Amit; Clagett, G Patrick; Lo, Hao; Timaran, Carlos

2009-03-01

To assess the agreement between three methods of calculation of mean aortic wall thickness (MAWT) using magnetic resonance imaging (MRI). High-resolution MRI of the infrarenal abdominal aorta was performed on 70 subjects with a history of coronary artery disease who were part of a multi-ethnic population-based sample. MAWT was calculated as the mean distance between the adventitial and luminal aortic boundaries using three different methods: average distance at four standard positions (AWT-4P), average distance at 100 automated positions (AWT-100P), and using a mathematical computation derived from the total vessel and luminal areas (AWT-VA). Bland-Altman plots and Passing-Bablok regression analyses were used to assess agreement between methods. Bland-Altman analyses demonstrated a positive bias of 3.02+/-7.31% between the AWT-VA and the AWT-4P methods, and of 1.76+/-6.82% between the AWT-100P and the AWT-4P methods. Passing-Bablok regression analyses demonstrated constant bias between the AWT-4P method and the other two methods. Proportional bias was, however, not evident among the three methods. MRI methods of measurement of MAWT using a limited number of positions of the aortic wall systematically underestimate the MAWT value compared with the method that calculates MAWT from the vessel areas. Copyright (c) 2009 Wiley-Liss, Inc.

Airway wall thickness of allergic asthma caused by weed pollen or house dust mite assessed by computed tomography.

PubMed

Liu, Liping; Li, Guangrun; Sun, Yuemei; Li, Jian; Tang, Ningbo; Dong, Liang

2015-03-01

Little was known about Airway wall thickness of asthma patients with different allergen allergy. So we explored the possible difference of Airway wall thickness of asthma patients mono-sensitized to weed pollen or HDM using high-resolution computed tomography. 85 severe asthma patients were divided into weed pollen group and HDM group according to relevant allergen. 20 healthy donors served as controls. Airway wall area, percentage wall area and luminal area at the trunk of the apical bronchus of the right upper lobe were quantified using HRCT and compared. The values of pulmonary function were assessed as well. There were differences between HDM group and weed pollen group in WA/BSA,WA% and FEF25-75% pred, and no significant difference in FEV1%pred, FEV1/FVC and LA/BSA. In weed pollen group, WA/BSA was observed to correlate with the duration of rhinitis, whereas in HDM group, WA/BSA and LA/BSA was observed to correlate with the duration of asthma. In weed pollen group, FEV1/FVC showed a weak but significant negative correlation with WA%, but in HDM group FEV1/FVC showed a significant positive correlation with WA% and a statistical negative correlation with LA/BSA. FEV1/FVC and FEF25-75% pred were higher and WA/BSA and LA/BSA were lower in healthy control group than asthma group. FEV1%pred and WA% was no significant difference between asthma patients and healthy subjects. There are differences between HDM mono-sensitized subjects and weed pollen mono-sensitized subjects, not only in airway wall thickness, but also small airway obstruction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Extremely thick cell walls and low mesophyll conductance: welcome to the world of ancient living!

PubMed Central

Tosens, Tiina; Laanisto, Lauri; Niinemets, Ülo

2017-01-01

Abstract Mesophyll conductance is thought to be an important photosynthetic limitation in gymnosperms, but they currently constitute the most understudied plant group in regard to the extent to which photosynthesis and intrinsic water use efficiency are limited by mesophyll conductance. A comprehensive analysis of leaf gas exchange, photosynthetic limitations, mesophyll conductance (calculated by three methods previously used for across-species comparisons), and the underlying ultra-anatomical, morphological and chemical traits in 11 gymnosperm species varying in evolutionary history was performed to gain insight into the evolution of structural and physiological controls on photosynthesis at the lower return end of the leaf economics spectrum. Two primitive herbaceous species were included in order to provide greater evolutionary context. Low mesophyll conductance was the main limiting factor of photosynthesis in the majority of species. The strongest sources of limitation were extremely thick mesophyll cell walls, high chloroplast thickness and variation in chloroplast shape and size, and the low exposed surface area of chloroplasts per unit leaf area. In gymnosperms, the negative relationship between net assimilation per mass and leaf mass per area reflected an increased mesophyll cell wall thickness, whereas the easy-to-measure integrative trait of leaf mass per area failed to predict the underlying ultrastructural traits limiting mesophyll conductance. PMID:28419340

Stress-intensity factors for a thick-walled cylinder containing an annular imbedded or external or internal surface crack

NASA Technical Reports Server (NTRS)

Erdol, R.; Erdogan, F.

1976-01-01

The elastostatic axisymmetric problem for a long thick-walled cylinder containing a ring-shaped internal or edge crack is considered. Using the standard transform technique the problem is formulated in terms of an integral equation which has a simple Cauchy kernel for the internal crack and a generalized Cauchy kernel for the edge crack as the dominant part. As examples the uniform axial load and the steady-state thermal stress problems have been solved and the related stress intensity factors have been calculated. Among other findings the results show that in the cylinder under uniform axial stress containing an internal crack the stress intensity factor at the inner tip is always greater than that at the outer tip for equal net ligament thicknesses and in the cylinder with an edge crack which is under a state of thermal stress the stress intensity factor is a decreasing function of the crack depth, tending to zero as the crack depth approaches the wall thickness.

Fabrication of chitosan single-component microcapsules with a micrometer-thick and layered wall structure by stepwise core-mediated precipitation.

PubMed

Han, Yuanyuan; Tong, Weijun; Zhang, Yuying; Gao, Changyou

2012-02-27

Incubation of CaCO(3) microparticles in chitosan (CS) solution at pH 5.2 and following with ethylenediaminetetraacetic acid disodium salt (EDTA) treatment resulted in CS single-component microcapsules with an ultra-thick wall structure. Repeating the incubation caused stepwise increase of wall thickness and finally resulted in CS microcapsules with a layered structure. This unique method is mediated by precipitation of CS on the CaCO(3) particles as a result of pH increase caused by the partial dissolution of CaCO(3) . The obtained CS capsules are stable at neutral pH. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnet Fall inside a Conductive Pipe: Motion and the Role of the Pipe Wall Thickness

ERIC Educational Resources Information Center

Donoso, G.; Ladera, C. L.; Martin, P.

2009-01-01

Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for…

Ultrasound assessment of bladder wall thickness as a screening test for detrusor instability.

PubMed

Abou-Gamrah, Amgad; Fawzy, Mounir; Sammour, Hazem; Tadros, Sherif

2014-05-01

The aim of the current study was to evaluate the diagnostic accuracy of transvaginal ultrasound measurement of bladder wall thickness (BWT) in diagnosis of over active bladder (OAB). The current prospective study was conducted at Ain Shams University Maternity Hospital over 2 years. Patients presented to the urogynecology outpatient clinic with symptoms of urinary frequency, urgency, nocturia and/or urge incontinence were included in this study. The allocated patients were divided into two groups; Group 1(study group): fifty (50) patients with urodynamic diagnosis of detrusor instability (OAB) were included. Group 2 (control): fifty (50) patients with urodynamic diagnosis of stress incontinence were included. Using a transvaginal probe, BWT was measured in three sites at the thickest part of (a) the dome of the bladder (b) the trigone, and (c) the anterior wall of the bladder. An average of the three measurements was considered as the mean bladder thickness. A total of 100 patients with lower urinary symptoms were finally analyzed. There were no statistical significant differences between both groups regarding age, parity and body mass index, while there was statistically longer disease duration in group 2. Excluding urgency, there was statistical significant difference (P < 0.001) regarding lower urinary tract symptoms namely frequency, urgency incontinence, coital incontinence and nocturia. Patients in group 1 were more positive to symptoms of frequency, urgency incontinence, and nocturia, while patients in group 2 were more positive regarding coital incontinence. The thickness of trigon, dome, anterior wall and mean BWT was significantly higher in group 1 when compared to group 2. Receiver operator characteristics curve was constructed for estimating the association between mean BWT and prediction of OAB in patients with lower urinary tract symptoms. Mean BWT at 4.78 mm was considered as best cut-off value for prediction of OAB with sensitivity of 90 % and

Ultrasonic thickness measuring and imaging system and method

DOEpatents

Bylenok, Paul J.; Patmos, William M.; Wagner, Thomas A.; Martin, Francis H.

1992-08-04

An ultrasonic thickness measuring and imaging system uses an ultrasonic fsed beam probe for measuring thickness of an object, such as a wall of a tube, a computer for controlling movement of the probe in a scanning pattern within the tube and processing an analog signal produced by the probe which is proportional to the tube wall thickness in the scanning pattern, and a line scan recorder for producing a record of the tube wall thicknesses measured by the probe in the scanning pattern. The probe is moved in the scanning pattern to sequentially scan circumferentially the interior tube wall at spaced apart adjacent axial locations. The computer processes the analog signal by converting it to a digital signal and then quantifies the digital signal into a multiplicity of thickness points with each falling in one of a plurality of thickness ranges corresponding to one of a plurality of shades of grey. From the multiplicity of quantified thickness points, a line scan recorder connected to the computer generates a pictorial map of tube wall thicknesses with each quantified thickness point thus being obtained from a minute area, e.g. 0.010 inch by 0.010 inch, of tube wall and representing one pixel of the pictorial map. In the pictorial map of tube wall thicknesses, the pixels represent different wall thicknesses having different shades of grey.

Ultrasonic thickness measuring and imaging system and method

DOEpatents

Bylenok, Paul J.; Patmos, William M.; Wagner, Thomas A.; Martin, Francis H.

1992-01-01

An ultrasonic thickness measuring and imaging system uses an ultrasonic fsed beam probe for measuring thickness of an object, such as a wall of a tube, a computer for controlling movement of the probe in a scanning pattern within the tube and processing an analog signal produced by the probe which is proportional to the tube wall thickness in the scanning pattern, and a line scan recorder for producing a record of the tube wall thicknesses measured by the probe in the scanning pattern. The probe is moved in the scanning pattern to sequentially scan circumferentially the interior tube wall at spaced apart adjacent axial locations. The computer processes the analog signal by converting it to a digital signal and then quantifies the digital signal into a multiplicity of thickness points with each falling in one of a plurality of thickness ranges corresponding to one of a plurality of shades of grey. From the multiplicity of quantified thickness points, a line scan recorder connected to the computer generates a pictorial map of tube wall thicknesses with each quantified thickness point thus being obtained from a minute area, e.g. 0.010 inch by 0.010 inch, of tube wall and representing one pixel of the pictorial map. In the pictorial map of tube wall thicknesses, the pixels represent different wall thicknesses having different shades of grey.

High Power Laser Beam Welding of Thick-walled Ferromagnetic Steels with Electromagnetic Weld Pool Support

NASA Astrophysics Data System (ADS)

Fritzsche, André; Avilov, Vjaceslav; Gumenyuk, Andrey; Hilgenberg, Kai; Rethmeier, Michael

The development of modern high power laser systems allows single pass welding of thick-walled components with minimal distortion. Besides the high demands on the joint preparation, the hydrostatic pressure in the melt pool increases with higher plate thicknesses. Reaching or exceeding the Laplace pressure, drop-out or melt sagging are caused. A contactless electromagnetic weld support system was used for laser beam welding of thick ferromagnetic steel plates compensating these effects. An oscillating magnetic field induces eddy currents in the weld pool which generate Lorentz forces counteracting the gravity forces. Hysteresis effects of ferromagnetic steels are considered as well as the loss of magnetization in zones exceeding the Curie temperature. These phenomena reduce the effective Lorentz forces within the weld pool. The successful compensation of the hydrostatic pressure was demonstrated on up to 20 mm thick plates of duplex and mild steel by a variation of the electromagnetic power level and the oscillation frequency.

Contribution of CT quantified emphysema, air trapping and airway wall thickness on pulmonary function in male smokers with and without COPD.

PubMed

Mohamed Hoesein, Firdaus A A; de Jong, Pim A; Lammers, Jan-Willem J; Mali, Willem P Th M; Mets, Onno M; Schmidt, Michael; de Koning, Harry J; Aalst, Carlijn van der; Oudkerk, Matthijs; Vliegenthart, Rozemarijn; Ginneken, Bram van; van Rikxoort, Eva M; Zanen, Pieter

2014-09-01

Emphysema, airway wall thickening and air trapping are associated with chronic obstructive pulmonary disease (COPD). All three can be quantified by computed tomography (CT) of the chest. The goal of the current study is to determine the relative contribution of CT derived parameters on spirometry, lung volume and lung diffusion testing. Emphysema, airway wall thickening and air trapping were quantified automatically on CT in 1,138 male smokers with and without COPD. Emphysema was quantified by the percentage of voxels below -950 Hounsfield Units (HU), airway wall thickness by the square root of wall area for a theoretical airway with 10 mm lumen perimeter (Pi10) and air trapping by the ratio of mean lung density at expiration and inspiration (E/I-ratio). Spirometry, residual volume to total lung capacity (RV/TLC) and diffusion capacity (Kco) were obtained. Standardized regression coefficients (β) were used to analyze the relative contribution of CT changes to pulmonary function measures. The independent contribution of the three CT measures differed per lung function parameter. For the FEV1 airway wall thickness was the most contributing structural lung change (β = -0.46), while for the FEV1/FVC this was emphysema (β = -0.55). For the residual volume (RV) air trapping was most contributing (β = -0.35). Lung diffusion capacity was most influenced by emphysema (β = -0.42). In a cohort of smokers with and without COPD the effect of different CT changes varies per lung function measure and therefore emphysema, airway wall thickness and air trapping need to be taken in account.

Effect of ceramic thickness and composite bases on stress distribution of inlays--a finite element analysis.

PubMed

Durand, Letícia Brandão; Guimarães, Jackeline Coutinho; Monteiro Junior, Sylvio; Baratieri, Luiz Narciso

2015-01-01

The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred.

Ureteral wall thickness at the impacted ureteral stone site: a critical predictor for success rates after SWL.

PubMed

Sarica, Kemal; Kafkasli, Alper; Yazici, Özgür; Çetinel, Ali Cihangir; Demirkol, Mehmet Kutlu; Tuncer, Murat; Şahin, Cahit; Eryildirim, Bilal

2015-02-01

The aim of the study was to determine the possible predictive value of certain patient- and stone-related factors on the stone-free rates and auxiliary procedures after extracorporeal shock wave lithotripsy in patients with impacted proximal ureteral calculi. A total of 111 patients (86 male, 25 females M/F: 3.44/1) with impacted proximal ureteral stones treated with shock wave lithotripsy were evaluated. Cases were retrieved from a departmental shock wave lithotripsy database. Variables analyzed included BMI of the case, diameter of proximal ureter and renal pelvis, stone size and Hounsfield unit, ureteral wall thickness at the impacted stone site. Stone-free status on follow-up imaging at 3 months was considered a successful outcome. All patients had a single impacted proximal ureteral stone. While the mean age of the cases was 46 ± 13 years (range 26-79 years), mean stone size was 8.95 mm (5.3-15.1 mm). Following shock wave lithotripsy although 87 patients (78.4%) were completely stone-free at 3-month follow-up visit, 24 (21.6%) cases had residual fragments requiring further repeat procedures. Prediction of the final outcome of SWL in patients with impacted proximal ureteral stones is a challenging issue and our data did clearly indicate a highly significant relationship between ureteral wall thickness and the success rates of shock wave lithotripsy particularly in cases requiring additional procedures. Of all the evaluated stone- and patient-related factors, only ureteral wall thickness at the impacted stone site independently predicted shock wave lithotripsy success.

Formation of Rhamnogalacturonan II-Borate Dimer in Pectin Determines Cell Wall Thickness of Pumpkin Tissue1

PubMed Central

Ishii, Tadashi; Matsunaga, Toshiro; Hayashi, Noriko

2001-01-01

Boron (B) deficiency results in inhibition of pumpkin (Cucurbia moschata Duchesne) growth that is accompanied by swelling of the cell walls. Monomeric rhamnogalacturonan II (mRG-II) accounted for 80% to 90% of the total RG-II in B-deficient walls, whereas the borate ester cross-linked RG-II dimer (dRG-II-B) accounted for more than 80% of the RG-II in control plants. The results of glycosyl residue and glycosyl linkage composition analyses of the RG-II from control and B-deficient plants were similar. Thus, B deficiency does not alter the primary structure of RG-II. The addition of 10B-enriched boric acid to B-deficient plants resulted within 5 h in the conversion of mRG-II to dRG-II-10B. The wall thickness of the 10B-treated plants and control plants was similar. The formation and possible functions of a borate ester cross-linked RG-II in the cell walls are discussed. PMID:11500567

The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output.

PubMed

Smerup, Morten; Damkjær, Mads; Brøndum, Emil; Baandrup, Ulrik T; Kristiansen, Steen Buus; Nygaard, Hans; Funder, Jonas; Aalkjær, Christian; Sauer, Cathrine; Buchanan, Rasmus; Bertelsen, Mads Frost; Østergaard, Kristine; Grøndahl, Carsten; Candy, Geoffrey; Hasenkam, J Michael; Secher, Niels H; Bie, Peter; Wang, Tobias

2016-02-01

Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521±61 ml and 228±42 ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83±1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output. © 2016. Published by The Company of Biologists Ltd.

Nonlinear fracture mechanics-based analysis of thin wall cylinders

NASA Technical Reports Server (NTRS)

Brust, Frederick W.; Leis, Brian N.; Forte, Thomas P.

1994-01-01

This paper presents a simple analysis technique to predict the crack initiation, growth, and rupture of large-radius, R, to thickness, t, ratio (thin wall) cylinders. The method is formulated to deal both with stable tearing as well as fatigue mechanisms in applications to both surface and through-wall axial cracks, including interacting surface cracks. The method can also account for time-dependent effects. Validation of the model is provided by comparisons of predictions to more than forty full scale experiments of thin wall cylinders pressurized to failure.

Simulation of the development and interaction of instabilities in a relativistic electron beam under variation of the beam wall thickness

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

Badarin, A. A.; Kurkin, S. A.; Koronovskii, A. A.

The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner onmore » the magnitude of the external magnetic field.« less

Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

PubMed

Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

2016-02-02

Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis.

Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.

PubMed

Bandura, A V; Evarestov, R A; Lukyanov, S I

2014-07-28

A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure.

Flow characteristics and scaling past highly porous wall-mounted fences

NASA Astrophysics Data System (ADS)

Rodríguez-López, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

2017-07-01

An extensive characterization of the flow past wall-mounted highly porous fences based on single- and multi-scale geometries has been performed using hot-wire anemometry in a low-speed wind tunnel. Whilst drag properties (estimated from the time-averaged momentum equation) seem to be mostly dependent on the grids' blockage ratio; wakes of different size and orientation bars seem to generate distinct behaviours regarding turbulence properties. Far from the near-grid region, the flow is dominated by the presence of two well-differentiated layers: one close to the wall dominated by the near-wall behaviour and another one corresponding to the grid's wake and shear layer, originating from between this and the freestream. It is proposed that the effective thickness of the wall layer can be inferred from the wall-normal profile of root-mean-square streamwise velocity or, alternatively, from the wall-normal profile of streamwise velocity correlation. Using these definitions of wall-layer thickness enables us to collapse different trends of the turbulence behaviour inside this layer. In particular, the root-mean-square level of the wall shear stress fluctuations, longitudinal integral length scale, and spanwise turbulent structure is shown to display a satisfactory scaling with this thickness rather than with the whole thickness of the grid's wake. Moreover, it is shown that certain grids destroy the spanwise arrangement of large turbulence structures in the logarithmic region, which are then re-formed after a particular streamwise extent. It is finally shown that for fences subject to a boundary layer of thickness comparable to their height, the effective thickness of the wall layer scales with the incoming boundary layer thickness. Analogously, it is hypothesized that the growth rate of the internal layer is also partly dependent on the incoming boundary layer thickness.

Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

NASA Astrophysics Data System (ADS)

Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

2017-01-01

Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1-5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces.

Suprascarpal fat pad thickness may predict venous drainage patterns in abdominal wall flaps.

PubMed

Bast, John; Pitcher, Austin A; Small, Kevin; Otterburn, David M

2016-02-01

Abdominal wall flaps are routinely used in reconstructive procedures. In some patients inadequate venous drainage from the deep vein may cause fat necrosis or flap failure. Occasionally the superficial inferior epigastric vessels (SIEV) are of sufficient size to allow for microvascular revascularization. This study looked at the ratio of the sub- and suprascarpal fat layers, the number of deep system perforators, and SIEV diameter to determine any correlation of the fat topography and SIEV. 50 abdominal/pelvic CT angiograms (100 hemiabdomens) were examined in women aged 34-70 years for number of perforators, SIEV diameter, and fat pad thickness above and below Scarpa's fascia. Data was analyzed using multivariate model. The average suprascarpal and subscarpal layers were 18.6 ± 11.5 mm and 6.2 ± 7.2 mm thick, respectively. The average SIEV diameter was 2.06 ± 0.81 mm and the average number of perforators was 2.09 ± 1.03 per hemiabdomen. Hemiabdomens with suprascarpal thickness>23 mm had greater SIEV diameter [2.69 mm vs. 1.8 mm (P < 0.0001)] The fat layer thickness did not correlate with the number of perforators. Neither subscarpal fat thickness nor suprascarpal-to-subscarpal fat layer thickness correlated significantly with SIEV caliber or number of perforators in multivariate model. Suprascarpal fat pad thicker than 23 mm had larger SIEVs irrespective of the number of deep system perforators. This may indicate a cohort of patients at risk of venous congestion from poor venous drainage if only the deep system is revascularized. We recommend harvesting the SIEV in patients with suprascarpal fat pad >23 mm to aid in superficial drainage. © 2015 Wiley Periodicals, Inc.

Numerical Determination of Natural Frequencies and Modes of the Vibrations of a Thick-Walled Cylindrical Shell

NASA Astrophysics Data System (ADS)

Grigorenko, A. Ya.; Borisenko, M. Yu.; Boichuk, E. V.; Prigoda, A. P.

2018-01-01

The dynamic characteristics of a thick-walled cylindrical shell are determined numerically using the finite-element method implemented with licensed FEMAR software. The natural frequencies and modes are compared with those obtained earlier experimentally by the method of stroboscopic holographic interferometry. Frequency coefficients demonstrating how the natural frequency depends on the physical and mechanical parameters of the material are determined.

Research on wall shear stress considering wall roughness when shear swirling flow vibration cementing

NASA Astrophysics Data System (ADS)

Cui, Zhihua; Ai, Chi; Feng, Fuping

2017-01-01

When shear swirling flow vibration cementing, the casing is revolving periodically and eccentrically, which leads to the annulus fluid in turbulent swirling flow state. The wall shear stress is more than that in laminar flow field when conventional cementing. The paper mainly studied the wall shear stress distribution on the borehole wall when shear swirling flow vibration cementing based on the finite volume method. At the same time, the wall roughness affected and changed the turbulent flow near the borehole wall and the wall shear stress. Based on the wall function method, the paper established boundary conditions considering the wall roughness and derived the formula of the wall shear stress. The results showed that the wall roughness significantly increases the wall shear stress. However, the larger the wall roughness, the greater the thickness of mud cake, which weakening the cementing strength. Considering the effects in a comprehensive way, it is discovered that the particle size of solid phase in drilling fluid is about 0.1 mm to get better cementing quality.

Building and degradation of secondary cell walls: are there common patterns of lamellar assembly of cellulose microfibrils and cell wall delamination?

PubMed

De Micco, Veronica; Ruel, Katia; Joseleau, Jean-Paul; Aronne, Giovanna

2010-08-01

During cell wall formation and degradation, it is possible to detect cellulose microfibrils assembled into thicker and thinner lamellar structures, respectively, following inverse parallel patterns. The aim of this study was to analyse such patterns of microfibril aggregation and cell wall delamination. The thickness of microfibrils and lamellae was measured on digital images of both growing and degrading cell walls viewed by means of transmission electron microscopy. To objectively detect, measure and classify microfibrils and lamellae into thickness classes, a method based on the application of computerized image analysis combined with graphical and statistical methods was developed. The method allowed common classes of microfibrils and lamellae in cell walls to be identified from different origins. During both the formation and degradation of cell walls, a preferential formation of structures with specific thickness was evidenced. The results obtained with the developed method allowed objective analysis of patterns of microfibril aggregation and evidenced a trend of doubling/halving lamellar structures, during cell wall formation/degradation in materials from different origin and which have undergone different treatments.

Myocardial effective transverse relaxation time T2* Correlates with left ventricular wall thickness: A 7.0 T MRI study.

PubMed

Huelnhagen, Till; Hezel, Fabian; Serradas Duarte, Teresa; Pohlmann, Andreas; Oezerdem, Celal; Flemming, Bert; Seeliger, Erdmann; Prothmann, Marcel; Schulz-Menger, Jeanette; Niendorf, Thoralf

2017-06-01

Myocardial effective relaxation time T2* is commonly regarded as a surrogate for myocardial tissue oxygenation. However, it is legitimate to assume that there are multiple factors that influence T2*. To this end, this study investigates the relationship between T2* and cardiac macromorphology given by left ventricular (LV) wall thickness and left ventricular radius, and provides interpretation of the results in the physiological context. High spatio-temporally resolved myocardial CINE T2* mapping was performed in 10 healthy volunteers using a 7.0 Tesla (T) full-body MRI system. Ventricular septal wall thickness, left ventricular inner radius, and T2* were analyzed. Macroscopic magnetic field changes were elucidated using cardiac phase-resolved magnetic field maps. Ventricular septal T2* changes periodically over the cardiac cycle, increasing in systole and decreasing in diastole. Ventricular septal wall thickness and T2* showed a significant positive correlation, whereas the inner LV radius and T2* were negatively correlated. The effect of macroscopic magnetic field gradients on T2* can be considered minor in the ventricular septum. Our findings suggest that myocardial T2* is related to tissue blood volume fraction. Temporally resolved T2* mapping could be beneficial for myocardial tissue characterization and for understanding cardiac (patho)physiology in vivo. Magn Reson Med 77:2381-2389, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Measurement of vascular wall attenuation: comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro.

PubMed

Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

2012-11-01

To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P=0.1606) or among the 3 densities of intravascular contrast material (MBIR, P=0.8185; Detail kernel, P=0.0802). Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

On the Opening of Thick Walled Elastic Tubes: A Fluid-Structure Model for Acid Reflux

NASA Astrophysics Data System (ADS)

Ghosh, Sudip; Kahrilas, Peter

2005-11-01

A coupled fluid-structure mathematical model was developed to quantify rapid opening of thick-walled elastic tubes, a phenomenon underlying biological flows such as gastroesophageal reflux disease (GERD). The wall was modeled using non-linear finite deformation theory to predict space-time radial distention of an axisymmetric tube with luminal fluid flow. Anisotropic azimuthal and longitudinal muscle-induced stresses were incorporated, and interstitial material properties were assumed isotropic and linearly elastic. Fluid flow was modeled using lubrication theory with inertial correction. Opening and flow were driven by a specified inflow pressure and zero pressure gradient was specified at outflow. No-slip and surface force balance were applied at the fluid-wall interface. Viscoelasticity was modeled with ad hoc damping and the evolution of the tube geometry was predicted at mid-layer. A potentially important discovery was made when applied to studies of initiation of opening with GERD: while material stiffness is of minor consequence, small changes in resting lumen distension (˜2 mm diameter) may be a sensitive distinguishing feature of the disease.

Ballistic Limit Equation for Single Wall Titanium

NASA Technical Reports Server (NTRS)

Ratliff, J. M.; Christiansen, Eric L.; Bryant, C.

2009-01-01

Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified.

Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

PubMed Central

Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

2017-01-01

Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1–5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces. PMID:28054589

Visualization of the aneurysm wall: a 7.0-tesla magnetic resonance imaging study.

PubMed

Kleinloog, Rachel; Korkmaz, Emine; Zwanenburg, Jaco J M; Kuijf, Hugo J; Visser, Fredy; Blankena, Roos; Post, Jan A; Ruigrok, Ynte M; Luijten, Peter R; Regli, Luca; Rinkel, Gabriel J E; Verweij, Bon H

2014-12-01

Risk prediction of rupture of intracranial aneurysms is poor and is based mainly on lumen characteristics. However, characteristics of the aneurysm wall may be more informative predictors. The limited resolution of currently available imaging techniques and the thin aneurysm wall make imaging of wall thickness challenging. To introduce a novel protocol for imaging wall thickness variation using ultra--high-resolution 7.0-Tesla (7.0-T) magnetic resonance imaging (MRI). We studied 33 unruptured intracranial aneurysms in 24 patients with a T1-weighted 3-dimensional magnetization-prepared inversion-recovery turbo-spin-echo whole-brain sequence with a resolution of 0.8 × 0.8 × 0.8 mm. We performed a validation study with a wedge phantom and with 2 aneurysm wall biopsies obtained during aneurysm treatment using ex vivo MRI and histological examination and correlating variations in MRI signal intensity with variations in actual thickness of the aneurysm wall. In vivo, the aneurysm wall was visible in 28 of the 33 aneurysms. Variation in signal intensity was observed in all visible aneurysm walls. Ex vivo MRI showed variation in signal intensity across the wall of the biopsies, similar to that observed on the in vivo images. Signal intensity and actual thickness in both biopsies had a linear correlation, with Pearson correlation coefficients of 0.85 and 0.86. Unruptured intracranial aneurysm wall and its variation in thickness can be visualized with 7.0-T MRI. Aneurysm wall thickness variation can now be further studied as a risk factor for rupture in prospective studies.

3D mapping of airway wall thickening in asthma with MSCT: a level set approach

NASA Astrophysics Data System (ADS)

Fetita, Catalin; Brillet, Pierre-Yves; Hartley, Ruth; Grenier, Philippe A.; Brightling, Christopher

2014-03-01

Assessing the airway wall thickness in multi slice computed tomography (MSCT) as image marker for airway disease phenotyping such asthma and COPD is a current trend and challenge for the scientific community working in lung imaging. This paper addresses the same problem from a different point of view: considering the expected wall thickness-to-lumen-radius ratio for a normal subject as known and constant throughout the whole airway tree, the aim is to build up a 3D map of airway wall regions of larger thickness and to define an overall score able to highlight a pathological status. In this respect, the local dimension (caliber) of the previously segmented airway lumen is obtained on each point by exploiting the granulometry morphological operator. A level set function is defined based on this caliber information and on the expected wall thickness ratio, which allows obtaining a good estimate of the airway wall throughout all segmented lumen generations. Next, the vascular (or mediastinal dense tissue) contact regions are automatically detected and excluded from analysis. For the remaining airway wall border points, the real wall thickness is estimated based on the tissue density analysis in the airway radial direction; thick wall points are highlighted on a 3D representation of the airways and several quantification scores are defined. The proposed approach is fully automatic and was evaluated (proof of concept) on a patient selection coming from different databases including mild, severe asthmatics and normal cases. This preliminary evaluation confirms the discriminative power of the proposed approach regarding different phenotypes and is currently extending to larger cohorts.

A hybrid method for airway segmentation and automated measurement of bronchial wall thickness on CT.

PubMed

Xu, Ziyue; Bagci, Ulas; Foster, Brent; Mansoor, Awais; Udupa, Jayaram K; Mollura, Daniel J

2015-08-01

Inflammatory and infectious lung diseases commonly involve bronchial airway structures and morphology, and these abnormalities are often analyzed non-invasively through high resolution computed tomography (CT) scans. Assessing airway wall surfaces and the lumen are of great importance for diagnosing pulmonary diseases. However, obtaining high accuracy from a complete 3-D airway tree structure can be quite challenging. The airway tree structure has spiculated shapes with multiple branches and bifurcation points as opposed to solid single organ or tumor segmentation tasks in other applications, hence, it is complex for manual segmentation as compared with other tasks. For computerized methods, a fundamental challenge in airway tree segmentation is the highly variable intensity levels in the lumen area, which often causes a segmentation method to leak into adjacent lung parenchyma through blurred airway walls or soft boundaries. Moreover, outer wall definition can be difficult due to similar intensities of the airway walls and nearby structures such as vessels. In this paper, we propose a computational framework to accurately quantify airways through (i) a novel hybrid approach for precise segmentation of the lumen, and (ii) two novel methods (a spatially constrained Markov random walk method (pseudo 3-D) and a relative fuzzy connectedness method (3-D)) to estimate the airway wall thickness. We evaluate the performance of our proposed methods in comparison with mostly used algorithms using human chest CT images. Our results demonstrate that, on publicly available data sets and using standard evaluation criteria, the proposed airway segmentation method is accurate and efficient as compared with the state-of-the-art methods, and the airway wall estimation algorithms identified the inner and outer airway surfaces more accurately than the most widely applied methods, namely full width at half maximum and phase congruency. Copyright © 2015. Published by Elsevier B.V.

Microwave background distortions from domain walls

NASA Technical Reports Server (NTRS)

Goetz, Guenter; Noetzold, Dirk

1990-01-01

Domain walls arising in a cosmic phase transition after decoupling were recently proposed as seeds for the formation of large scale structure. The distortion induced in the microwave background radiation is calculated in dependence of the wall thickness, surface density, scalar field potential, cosmic redshift and the velocity of the wall. It was found that the maximal redshift distortion for both spherical and planar walls is of the order pi G sigma H(sup -1)(sub 0), where sigma is the surface energy density and H(sup -1)(sub 0) the Hubble parameter. It was also found that, for a wall thickness smaller than the horizon, walls can be treated as infinitely thin, i.e., the redshift distortion is independent of the wall thickness and the specific form of the scalar potential. For planar walls moving with a Lorentz-factor gamma the redshift distortion is enhanced by gamma cubed.

Method and apparatus to produce and maintain a thick, flowing, liquid lithium first wall for toroidal magnetic confinement DT fusion reactors

DOEpatents

Woolley, Robert D.

2002-01-01

A system for forming a thick flowing liquid metal, in this case lithium, layer on the inside wall of a toroid containing the plasma of a deuterium-tritium fusion reactor. The presence of the liquid metal layer or first wall serves to prevent neutron damage to the walls of the toroid. A poloidal current in the liquid metal layer is oriented so that it flows in the same direction as the current in a series of external magnets used to confine the plasma. This current alignment results in the liquid metal being forced against the wall of the toroid. After the liquid metal exits the toroid it is pumped to a heat extraction and power conversion device prior to being reentering the toroid.

Free and Forced Vibrations of Thick-Walled Anisotropic Cylindrical Shells

NASA Astrophysics Data System (ADS)

Marchuk, A. V.; Gnedash, S. V.; Levkovskii, S. A.

2017-03-01

Two approaches to studying the free and forced axisymmetric vibrations of cylindrical shell are proposed. They are based on the three-dimensional theory of elasticity and division of the original cylindrical shell with concentric cross-sectional circles into several coaxial cylindrical shells. One approach uses linear polynomials to approximate functions defined in plan and across the thickness. The other approach also uses linear polynomials to approximate functions defined in plan, but their variation with thickness is described by the analytical solution of a system of differential equations. Both approaches have approximation and arithmetic errors. When determining the natural frequencies by the semi-analytical finite-element method in combination with the divide and conqure method, it is convenient to find the initial frequencies by the finite-element method. The behavior of the shell during free and forced vibrations is analyzed in the case where the loading area is half the shell thickness

49 CFR 179.400-8 - Thickness of plates.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

49 CFR 179.400-8 - Thickness of plates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

49 CFR 179.400-8 - Thickness of plates.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

49 CFR 179.400-8 - Thickness of plates.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400-8 Thickness of plates... joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of any 3..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

Longwave Stability of Two Liquid Layers Coating Both Sides of a Thick Wall in the Absence of Gravity

NASA Astrophysics Data System (ADS)

Dávalos-Orozco, L. A.

2018-05-01

A system of two coupled nonlinear equations was calculated to describe the thermocapillary evolution of the free surface deformations of two liquid layers coating both sides of a wall of finite thickness and thermal conductivity in the absence of gravity. The equations were obtained under the small wavenumber approximation. A temperature gradient appears perpendicular to the liquid-wall-liquid system due to the temperature difference between the atmospheres outside the free surfaces of both fluid layers. The linear growth rate of the system was investigated with respect to a variety of parameters. Under some conditions, two stationary modes and one oscillatory mode between them were found. The second stationary mode was concluded to be always stable. It was also found that under different conditions only stationary convection is possible. These results depended on the relative thickness of the two fluid films. It is of interest to know if the coupled free surface perturbations presented a nonlinear sinuous or varicose mode. Thus, a two-dimensional numerical analysis was performed to find out which conditions lead to the sinuous or to the varicose mode of instability.

Optimum Material Composition for Minimizing the Stress Intensity Factor of Edge Crack in Thick-Walled FGM Circular Pipes Under Thermomechanical Loading

NASA Astrophysics Data System (ADS)

Sekine, Hideki; Yoshida, Kimiaki

This paper deals with the optimization problem of material composition for minimizing the stress intensity factor of radial edge crack in thick-walled functionally graded material (FGM) circular pipes under steady-state thermomechanical loading. Homogenizing the FGM circular pipes by simulating the inhomogeneity of thermal conductivity by a distribution of equivalent eigentemperature gradient and the inhomogeneity of Young's modulus and Poisson's ratio by a distribution of equivalent eigenstrain, we present an approximation method to obtain the stress intensity factor of radial edge crack in the FGM circular pipes. The optimum material composition for minimizing the stress intensity factor of radial edge crack is determined using a nonlinear mathematical programming method. Numerical results obtained for a thick-walled TiC/Al2O3 FGM circular pipe reveal that it is possible to decrease remarkably the stress intensity factor of radial edge crack by setting the optimum material composition profile.

Use of computed tomography to identify atrial fibrillation associated differences in left atrial wall thickness and density.

PubMed

Dewland, Thomas A; Wintermark, Max; Vaysman, Anna; Smith, Lisa M; Tong, Elizabeth; Vittinghoff, Eric; Marcus, Gregory M

2013-01-01

Left atrial (LA) tissue characteristics may play an important role in atrial fibrillation (AF) induction and perpetuation. Although frequently used in clinical practice, computed tomography (CT) has not been employed to describe differences in LA wall properties between AF patients and controls. We sought to noninvasively characterize AF-associated differences in LA tissue using CT. CT images of the LA were obtained in 98 consecutive patients undergoing AF ablation and in 89 controls. A custom software algorithm was used to measure wall thickness and density in four prespecified regions of the LA. On average, LA walls were thinner (-15.5%, 95% confidence interval [CI] -23.2 to -7.8%, P < 0.001) and demonstrated significantly lower density (-19.7 Hounsfield Units [HU], 95% CI -27.0 to -12.5 HU, P < 0.001) in AF patients compared to controls. In linear mixed models adjusting for demographics, clinical variables, and other CT measurements, the average LA, interatrial septum, LA appendage, and anterior walls remained significantly thinner in AF patients. After adjusting for the same potential confounders, history of AF was associated with reduced density in the LA anterior wall and increased density below the right inferior pulmonary vein and in the LA appendage. Application of an automated measurement algorithm to CT imaging of the atrium identified significant thinning of the LA wall and regional alterations in tissue density in patients with a history of AF. These findings suggest differences in LA tissue composition can be noninvasively identified and quantified using CT. ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.

Hypertensive heart disease versus hypertrophic cardiomyopathy: multi-parametric cardiovascular magnetic resonance discriminators when end-diastolic wall thickness ≥ 15 mm.

PubMed

Rodrigues, Jonathan C L; Rohan, Stephen; Ghosh Dastidar, Amardeep; Harries, Iwan; Lawton, Christopher B; Ratcliffe, Laura E; Burchell, Amy E; Hart, Emma C; Hamilton, Mark C K; Paton, Julian F R; Nightingale, Angus K; Manghat, Nathan E

2017-03-01

European guidelines state left ventricular (LV) end-diastolic wall thickness (EDWT) ≥15mm suggests hypertrophic cardiomyopathy (HCM), but distinguishing from hypertensive heart disease (HHD) is challenging. We identify cardiovascular magnetic resonance (CMR) predictors of HHD over HCM when EDWT ≥15mm. 2481 consecutive clinical CMRs between 2014 and 2015 were reviewed. 464 segments from 29 HCM subjects with EDWT ≥15mm but without other cardiac abnormality, hypertension or renal impairment were analyzed. 432 segments from 27 HHD subjects with EDWT ≥15mm but without concomitant cardiac pathology were analyzed. Magnitude and location of maximal EDWT, presence of late gadolinium enhancement (LGE), LV asymmetry (>1.5-fold opposing segment) and systolic anterior motion of the mitral valve (SAM) were measured. Multivariate logistic regression was performed. Significance was defined as p<0.05. HHD and HCM cohorts were age-/gender-matched. HHD had significantly increased indexed LV mass (110±27g/m 2 vs. 91±31g/m 2 , p=0.016) but no difference in site or magnitude of maximal EDWT. Mid-wall LGE was significantly more prevalent in HCM. Elevated indexed LVM, mid-wall LGE and absence of SAM were significant multivariate predictors of HHD, but LV asymmetry was not. Increased indexed LV mass, absence of mid-wall LGE and absence of SAM are better CMR discriminators of HHD from HCM than EDWT ≥15mm. • Hypertrophic cardiomyopathy (HCM) is often diagnosed with end-diastolic wall thickness ≥15mm. • Hypertensive heart disease (HHD) can be difficult to distinguish from HCM. • Retrospective case-control study showed that location and magnitude of EDWT are poor discriminators. • Increased left ventricular mass and midwall fibrosis are independent predictors of HHD. • Cardiovascular magnetic resonance parameters facilitate a better discrimination between HHD and HCM.

Modeling Periodic Adiabatic Shear Bands Evolution in a 304L Stainless Steel Thick-Walled Cylinder

NASA Astrophysics Data System (ADS)

Liu, Mingtao; Hu, Haibo; Fan, Cheng; Tang, Tiegang

2015-06-01

The self-organization of multiple shear bands in a 304L stainless steel thick-walled cylinder (TWC) was numerically studied. The microstructures of material lead to the non-uniform distribution of local yield stress, which plays a key role in the formation of spontaneous shear localization. We introduced a probability factor satisfied Gauss distribution into the macroscopic constitutive relationship to describe the non-uniformity of local yield stress. Using the probability factor, the initiation and propagation of multiple shear bands in TWC were numerically replicated in our 2D FEM simulation. Experimental results in the literature indicate that the machined surface at the internal boundary of a 304L stainless steel cylinder provides a work-hardened layer (about 20 μm) which has significantly different microstructures from base material. The work-hardened layer leads to the phenomenon that most shear bands are in clockwise or counterclockwise direction. In our simulation, periodic oriented perturbations were applied to describe the grain orientation in the work-hardened layer, and the spiral pattern of shear bands was successfully replicated.

Process stability and morphology optimization of very thick 4H-SiC epitaxial layers grown by chloride-based CVD

NASA Astrophysics Data System (ADS)

Yazdanfar, M.; Stenberg, P.; Booker, I. D.; Ivanov, I. G.; Kordina, O.; Pedersen, H.; Janzén, E.

2013-10-01

The development of a chemical vapor deposition (CVD) process for very thick silicon carbide (SiC) epitaxial layers suitable for high power devices is demonstrated by epitaxial growth of 200 μm thick, low doped 4H-SiC layers with excellent morphology at growth rates exceeding 100 μm/h. The process development was done in a hot wall CVD reactor without rotation using both SiCl4 and SiH4+HCl precursor approaches to chloride based growth chemistry. A C/Si ratio <1 and an optimized in-situ etch are shown to be the key parameters to achieve 200 μm thick, low doped epitaxial layers with excellent morphology.

Effects of increased left ventricular wall thickness on the myocardium in severe aortic stenosis with normal left ventricular ejection fraction: Two- and three-dimensional multilayer speckle tracking echocardiography.

PubMed

Cho, Eun Jeong; Park, Sung-Ji; Kim, Eun Kyoung; Lee, Ga Yeon; Chang, Sung-A; Choi, Jin-Oh; Lee, Sang-Chol; Park, Seung Woo

2017-04-01

The aim of this study was to determine the capability of real time three-dimensional echocardiography (RT3DE) and two-dimensional (2D) multilayer speckle tracking echocardiography (MSTE) for evaluation of early myocardial dysfunction triggered by increased left ventricular (LV) wall thickness in severe aortic stenosis (AS) with normal LV ejection fraction (EF≥55%). Conventional, RT3D STE and 2D MSTE were performed in 45 patients (mean 68.9±9.0 years) with severe AS (aortic valve area <1 cm 2 , aortic velocity Vmax >4 m/s or mean PG >40 mm Hg) and normal left ventricular ejection fraction (LVEF) without overt coronary artery disease and in 18 age-, sex-matched healthy controls. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS), and global radial strain (GRS) were calculated using RT3DE and MSTE. The severe AS group had lower 3D GLS, GRS, GAS and 2D epicardium, and mid-wall and endocardium GLS compared to healthy controls. In MSTE analysis, 2D LS and CS values decreased from the endocardial layer toward the epicardial layer. Severe AS patients with increased LV wall thickness had lower 3D GLS and 2D epicardium, and mid-wall and endocardium GLS compared with severe AS patients without LV wall thickening. GLS on RT3D STE was correlated with GLS on 2D MSTE, left ventricular mass index, LVEF, left atrial volume index, and lnNT-proBNP. RT3DE and 2D MSTE can be used to identify subtle contractile dysfunction triggered by increased LV wall thickness in severe AS with normal LVEF. Therefore, RT3D STE and 2D MSTE may provide additional information that can facilitate decision-making regarding severe AS patients with increased LV wall thickness and normal LV function. © 2017, Wiley Periodicals, Inc.

Ultrasound bladder wall thickness measurement in diagnosis of recurrent urinary tract infections and cystitis cystica in prepubertal girls.

PubMed

Milošević, Danko; Trkulja, Vladimir; Turudić, Daniel; Batinić, Danica; Spajić, Borislav; Tešović, Goran

2013-12-01

To evaluate urinary bladder wall thickness (BWT) assessed by ultrasound as a diagnostic tool for cystitis cystica. This was a 9-year prospective study comprising 120 prepubertal girls. Sixty subjects of whom half underwent cystoscopy represented cases while the other 60 (those with a single urinary tract infection and healthy subjects) represented controls. Based on receiver operating characteristics (ROC) analysis, BWT discriminated very well between cases and controls with area under the ROC curve close to 1.0. At the optimum cut-off defined at 3.9 mm, negative predictive value (NPV) was 100% leaving no probability of cystic cystitis with BWT <3.9 mm. Positive predictive value (PPV) was also very high (95.2%), indicating only around 4.82% probability of no cystic cystitis in patients with BWT values ≥3.9 mm. BWT could also distinguish between healthy subjects and those with a cured single urinary tract infection, although discriminatory properties were moderate (area under ROC 86.7%, PPV 78.8%, NPV 85.2%). Ultrasound mucosal bladder wall measurement is a non-invasive, simple and quite reliable method in diagnosis of cystitis cystica in prepubertal girls with recurrent urinary tract infections. Copyright © 2013 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

A temperature correlation for the radiation resistance of a thick-walled circular duct exhausting a hot gas

NASA Technical Reports Server (NTRS)

Mahan, J. R.; Cline, J. G.; Jones, J. D.

1984-01-01

It is often useful to know the radiation impedance of an unflanged but thick-walled circular duct exhausting a hot gas into relatively cold surroundings. The reactive component is shown to be insensitive to temperature, but the resistive component is shown to be temperature dependent. A temperature correlation is developed permitting prediction of the radiation resistance from a knowledge of the temperature difference between the ambient air and the gas flowing from the duct, and a physical basis for this correlation is presented.

Rotational stabilization of the resistive wall modes in tokamaks with a ferritic wall

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

Pustovitov, V. D.; National Research Nuclear University “MEPhI,” Kashirskoe sh. 31, Moscow 115409; Yanovskiy, V. V.

The dynamics of the rotating resistive wall modes (RWMs) is analyzed in the presence of a uniform ferromagnetic resistive wall with μ{sup ^}≡μ/μ{sub 0}≤4 (μ is the wall magnetic permeability, and μ{sub 0} is the vacuum one). This mimics a possible arrangement in ITER with ferromagnetic steel in test blanket modules or in future experiments in JT-60SA tokamak [Y. Kamada, P. Barabaschi, S. Ishida, the JT-60SA Team, and JT-60SA Research Plan Contributors, Nucl. Fusion 53, 104010 (2013)]. The earlier studies predict that such a wall must provide a destabilizing influence on the plasma by reducing the beta limit and increasingmore » the growth rates, compared to the reference case with μ{sup ^}=1. This is true for the locked modes, but the presented results show that the mode rotation changes the tendency to the opposite. At μ{sup ^}>1, the rotational stabilization related to the energy sink in the wall becomes even stronger than at μ{sup ^}=1, and this “external” effect develops at lower rotation frequency, estimated as several kHz at realistic conditions. The study is based on the cylindrical dispersion relation valid for arbitrary growth rates and frequencies. This relation is solved numerically, and the solutions are compared with analytical dependences obtained for slow (s/d{sub w}≫1) and fast (s/d{sub w}≪1) “ferromagnetic” rotating RWMs, where s is the skin depth and d{sub w} is the wall thickness. It is found that the standard thin-wall modeling becomes progressively less reliable at larger μ{sup ^}, and the wall should be treated as magnetically thick. The analysis is performed assuming only a linear plasma response to external perturbations without constraints on the plasma current and pressure profiles.« less

Steel Shear Walls, Behavior, Modeling and Design

NASA Astrophysics Data System (ADS)

Astaneh-Asl, Abolhassan

2008-07-01

In recent years steel shear walls have become one of the more efficient lateral load resisting systems in tall buildings. The basic steel shear wall system consists of a steel plate welded to boundary steel columns and boundary steel beams. In some cases the boundary columns have been concrete-filled steel tubes. Seismic behavior of steel shear wall systems during actual earthquakes and based on laboratory cyclic tests indicates that the systems are quite ductile and can be designed in an economical way to have sufficient stiffness, strength, ductility and energy dissipation capacity to resist seismic effects of strong earthquakes. This paper, after summarizing the past research, presents the results of two tests of an innovative steel shear wall system where the boundary elements are concrete-filled tubes. Then, a review of currently available analytical models of steel shear walls is provided with a discussion of capabilities and limitations of each model. We have observed that the tension only "strip model", forming the basis of the current AISC seismic design provisions for steel shear walls, is not capable of predicting the behavior of steel shear walls with length-to-thickness ratio less than about 600 which is the range most common in buildings. The main reasons for such shortcomings of the AISC seismic design provisions for steel shear walls is that it ignores the compression field in the shear walls, which can be significant in typical shear walls. The AISC method also is not capable of incorporating stresses in the shear wall due to overturning moments. A more rational seismic design procedure for design of shear walls proposed in 2000 by the author is summarized in the paper. The design method, based on procedures used for design of steel plate girders, takes into account both tension and compression stress fields and is applicable to all values of length-to-thickness ratios of steel shear walls. The method is also capable of including the effect of

Wall-based identification of coherent structures in wall-bounded turbulence

NASA Astrophysics Data System (ADS)

Sanmiguel Vila, C.; Flores, O.

2018-04-01

During the last decades, a number of reduced order models based on coherent structures have been proposed to describe wall-bounded turbulence. Many of these models emphasize the importance of coherent wall-normal velocity eddies (ν-eddies), which drive the generation of the very long streamwise velocity structures observed in the logarithmic and outer region. In order to use these models to improve our ability to control wall-bounded turbulence in realistic applications, these ν-eddies need to be identified from the wall in a non-intrusive way. In this paper, the possibility of using the pressure signal at the wall to identify these ν-eddies is explored, analyzing the cross-correlation between the wall-normal velocity component and the pressure fluctuations at the wall in a DNS of a turbulent channel flow at Reτ = 939. The results show that the cross-correlation has a region of negative correlation upstream, and a region of positive correlation backwards. In the spanwise direction the correlation decays monotonously, except very close to the wall where a change of sign of the correlation coefficient is observed. Moreover, filtering the pressure fluctuations at the wall in space results in an increase of the region where the cross-correlation is strong, both for the positively and the negatively correlated regions. The use of a time filter for the pressure fluctuations at the wall yields different results, displacing the regions of strong correlation without changing much their sizes. The results suggest that space-filtering the pressure at the wall is a feasible way to identify ν-eddies of different sizes, which could be used to trigger turbulent control strategies.

Optimization of wall thickness and lay-up for the shell-like composite structure loaded by non-uniform pressure field

NASA Astrophysics Data System (ADS)

Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

2017-01-01

The glass/carbon fiber composites are widely used in the design of various aircraft and rotorcraft components such as fairings and cowlings, which have predominantly a shell-like geometry and are made of quasi-isotropic laminates. The main requirements to such the composite parts are the specified mechanical stiffness to withstand the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflow-induced vibrations at the constrained weight of the part. The main objective of present study is the optimization of wall thickness and lay-up of composite shell-like cowling. The present approach assumes conversion of the CAD model of the cowling surface to finite element (FE) representation, then its wind tunnel testing simulation at the different orientation of airflow to find the most stressed mode of flight. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. A wall thickness of the shell had to change over its surface to minimize the objective at the constrained weight. We used a parameterization of the problem that assumes an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. Curve that formed by the intersection of the shell with sphere defined boundary of area, which should be reinforced by local thickening the shell wall. To eliminate a local stress concentration this increment was defined as the smooth function defined on the shell surface. As a result of structural optimization we obtained the thickness of shell's wall distribution, which then was used to design the draping and lay-up of composite prepreg layers. The global strain energy in the optimized cowling was reduced in2

High vancomycin MICs within the susceptible range in Staphylococcus aureus bacteraemia isolates are associated with increased cell wall thickness and reduced intracellular killing by human phagocytes.

PubMed

Falcón, Rocío; Martínez, Alba; Albert, Eliseo; Madrid, Silvia; Oltra, Rosa; Giménez, Estela; Soriano, Mario; Vinuesa, Víctor; Gozalbo, Daniel; Gil, María Luisa; Navarro, David

2016-05-01

Vancomycin minimum inhibitory concentrations (MICs) at the upper end of the susceptible range for Staphylococcus aureus have been associated with poor clinical outcomes of bloodstream infections. We tested the hypothesis that high vancomycin MICs in S. aureus bacteraemia isolates are associated with increased cell wall thickness and suboptimal bacterial internalisation or lysis by human phagocytes. In total, 95 isolates were evaluated. Original vancomycin MICs were determined by Etest. The susceptibility of S. aureus isolates to killing by phagocytes was assessed in a human whole blood assay. Internalisation of bacterial cells by phagocytes was investigated by flow cytometry. Cell wall thickness was evaluated by transmission electron microscopy. Genotypic analysis of S. aureus isolates was performed using a DNA microarray system. Vancomycin MICs were significantly higher (P=0.006) in isolates that were killed suboptimally (killing index <60%) compared with those killed efficiently (killing index >70%) and tended to correlate inversely (P=0.08) with the killing indices. Isolates in both killing groups were internalised by human neutrophils and monocytes with comparable efficiency. The cell wall was significantly thicker (P=0.03) in isolates in the low killing group. No genotypic differences were found between the isolates in both killing groups. In summary, high vancomycin MICs in S. aureus bacteraemia isolates were associated with increased cell wall thickness and reduced intracellular killing by phagocytes. Copyright © 2016 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

49 CFR 179.400-8 - Thickness of plates.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Specification for Cryogenic Liquid Tank Car Tanks and Seamless Steel Tanks (Classes DOT-113 and 107A) § 179.400... welded joints, except that for seamless heads, E = 1.0. (b) The minimum wall thickness, after forming, of..., except that for seamless heads, E=1.0. (c) The minimum wall thickness, after forming, of a flanged and...

Corrections to the thin wall approximation in general relativity

NASA Technical Reports Server (NTRS)

Garfinkle, David; Gregory, Ruth

1989-01-01

The question is considered whether the thin wall formalism of Israel applies to the gravitating domain walls of a lambda phi(exp 4) theory. The coupled Einstein-scalar equations that describe the thick gravitating wall are expanded in powers of the thickness of the wall. The solutions of the zeroth order equations reproduce the results of the usual Israel thin wall approximation for domain walls. The solutions of the first order equations provide corrections to the expressions for the stress-energy of the wall and to the Israel thin wall equations. The modified thin wall equations are then used to treat the motion of spherical and planar domain walls.

Process for forming a long gas turbine engine blade having a main wall with a thin portion near a tip

DOEpatents

Campbell, Christian X; Thomaidis, Dimitrios

2014-05-13

A process is provided for forming an airfoil for a gas turbine engine involving: forming a casting of a gas turbine engine airfoil having a main wall and an interior cavity, the main wall having a wall thickness extending from an external surface of the outer wall to the interior cavity, an outer section of the main wall extending from a location between a base and a tip of the airfoil casting to the tip having a wall thickness greater than a final thickness. The process may further involve effecting movement, using a computer system, of a material removal apparatus and the casting relative to one another such that a layer of material is removed from the casting at one or more radial portions along the main wall of the casting.

Study on thickness distribution of thermoformed medical PVC blister

NASA Astrophysics Data System (ADS)

Li, Yiping

2017-08-01

Vacuum forming has many advantages over other plastic forming processes due to its cost effectiveness, time efficiency, higher product precision, and more design flexibility. Nevertheless, when pressures greater than the atmospheric value are required to force the thermo-plastic into more intimate contact with the mold surface, pressure forming is a better choice. This paper studies the process of air-pressure thermoforming of plastic sheet, and focuses on medical blister PVC products. ANSYS POLYFLOW tool is used to simulate the process and analyze the wall thickness distribution of the blister. The influence of mold parameters on the wall thickness distribution of thermoformed part is thus obtained through simulation. Increasing radius between mold and side wall at the bottom of blister and draft prove to improve the wall thickness distribution.

Accuracy Evaluation in the Measurement of a Small Change in the Thickness of Arterial Walls and the Measurement of Elasticity of the Human Carotid Artery

NASA Astrophysics Data System (ADS)

Hasegawa, Hideyuki; Kanai, Hiroshi; Hoshimiya, Nozomu; Chubachi, Noriyoshi; Koiwa, Yoshiro

1998-05-01

For the diagnosis of the early stages of atherosclerosis, it isimportant to evaluate the local acoustic characteristics of thearterial wall. For this purpose, it is necessary to increase thespatial resolution in the axial direction to several millimeters,which corresponds to the size of the macular lesion on the surface ofthe wall. We have proposed a method for measuring small velocitysignals on the intima and adventitia of the arterial wall from theskin surface using pulsive ultrasonic waves. The small change inthickness of the arterial wall is obtained by integrating thedifference between the two velocity signals on the intima andadventitia. The elastic property of the arterial wall is noninvasivelyevaluated from the change in thickness and the arterial innerpressure. In this paper, we evaluate the accuracy of the proposedmethod for measuring the small displacement. Moreover, we applied thismethod to evaluate the elastic property of the arterial wall of 50patients and 8 healthy subjects.

Ellipsometric measurement of liquid film thickness

NASA Technical Reports Server (NTRS)

Chang, Ki Joon; Frazier, D. O.

1989-01-01

The immediate objective of this research is to measure liquid film thickness from the two equilibrium phases of a monotectic system in order to estimate the film pressure of each phase. Thus liquid film thicknesses on the inside walls of the prism cell above the liquid level have been measured elliposmetrically for the monotectic system of succinonitrile and water. The thickness varies with temperature and composition of each plane. The preliminary results from both layers at 60 deg angle of incidence show nearly uniform thickness from about 21 to 23 C. The thickness increases with temperature but near 30 C the film appears foggy and scatters the laser beam. As the temperature of the cell is raised beyond room temperature it becomes increasingly difficult to equalize the temperature inside and outside the cell. The fogging may also be an indication that solution, not pure water, is adsorbed onto the substrate. Nevertheless, preliminary results suggest that ellipsometric measurement is feasible and necessary to measure more accurately and rapidly the film thickness and to improve thermal control of the prism walls.

A unified EM approach to bladder wall segmentation with coupled level-set constraints

PubMed Central

Han, Hao; Li, Lihong; Duan, Chaijie; Zhang, Hao; Zhao, Yang; Liang, Zhengrong

2013-01-01

Magnetic resonance (MR) imaging-based virtual cystoscopy (VCys), as a non-invasive, safe and cost-effective technique, has shown its promising virtue for early diagnosis and recurrence management of bladder carcinoma. One primary goal of VCys is to identify bladder lesions with abnormal bladder wall thickness, and consequently a precise segmentation of the inner and outer borders of the wall is required. In this paper, we propose a unified expectation-maximization (EM) approach to the maximum-a-posteriori (MAP) solution of bladder wall segmentation, by integrating a novel adaptive Markov random field (AMRF) model and the coupled level-set (CLS) information into the prior term. The proposed approach is applied to the segmentation of T1-weighted MR images, where the wall is enhanced while the urine and surrounding soft tissues are suppressed. By introducing scale-adaptive neighborhoods as well as adaptive weights into the conventional MRF model, the AMRF model takes into account the local information more accurately. In order to mitigate the influence of image artifacts adjacent to the bladder wall and to preserve the continuity of the wall surface, we apply geometrical constraints on the wall using our previously developed CLS method. This paper not only evaluates the robustness of the presented approach against the known ground truth of simulated digital phantoms, but further compares its performance with our previous CLS approach via both volunteer and patient studies. Statistical analysis on experts’ scores of the segmented borders from both approaches demonstrates that our new scheme is more effective in extracting the bladder wall. Based on the wall thickness calibrated from the segmented single-layer borders, a three-dimensional virtual bladder model can be constructed and the wall thickness can be mapped on to the model, where the bladder lesions will be eventually detected via experts’ visualization and/or computer-aided detection. PMID:24001932

Compliance of the abdominal wall during laparoscopic insufflation.

PubMed

Becker, Chuck; Plymale, Margaret A; Wennergren, John; Totten, Crystal; Stigall, Kyle; Roth, J Scott

2017-04-01

To provide adequate workspace between the viscera and abdominal wall, insufflation with carbon dioxide is a common practice in laparoscopic surgeries. An insufflation pressure of 15 mmHg is considered to be safe in patients, but all insufflation pressures create perioperative and postoperative physiologic effects. As a composition of viscoelastic materials, the abdominal wall should distend in a predictable manner given the pressure of the pneumoperitoneum. The purpose of this study was to elucidate the relationship between degree of abdominal distention and the insufflation pressure, with the goal of determining factors which impact the compliance of the abdominal wall. A prospective, IRB-approved study was conducted to video record the abdomens of patients undergoing insufflation prior to a laparoscopic surgery. Photo samples were taken every 5 s, and the strain of the patient's abdomen in the sagittal plane was determined, as well as the insufflator pressure (stress) at bedside. Patients were insufflated to 15 mmHg. The relationship between the stress and strain was determined in each sample, and compliance of the patient's abdominal wall was calculated. Subcutaneous fat thickness and rectus abdominus muscle thickness were obtained from computed tomography scans. Correlations between abdominal wall compliances and subcutaneous fat and muscle content were determined. Twenty-five patients were evaluated. An increased fat thickness in the abdominal wall had a direct exponential relationship with abdominal wall compliance (R 2  = 0.59, p < 0.05). There was no correlation between muscle and fat thickness. All insufflation pressures create perioperative and postoperative complications. The compliance of patients' abdominal body walls differs, and subcutaneous fat thickness has a direct exponential relationship with abdominal wall compliance. Thus, insufflation pressures can be better tailored per the patient. Future studies are needed to demonstrate the

A numerical study of multiple adiabatic shear bands evolution in a 304LSS thick-walled cylinder

NASA Astrophysics Data System (ADS)

Liu, Mingtao; Hu, Haibo; Fan, Cheng; Tang, Tiegang

2017-01-01

The self-organization of multiple shear bands in a 304L stainless steel(304LSS) thick-walled cylinder (TWC) was numerically studied. The microstructures of material lead to the non-uniform distribution of the local yield stress, which play a key role in the formation of spontaneous shear localization. We introduced a probability factor satisfied the Gaussian distribution into the macroscopic constitutive relationship to describe the non-uniformity of local yield stress. Using the probability factor, the initiation and propagation of multiple shear bands in TWC were numerically replicated in our 2D FEM simulation. Experimental results in the literature indicated that the machined surface at the internal boundary of a 304L stainless steel cylinder provides a work-hardened layer (about 20˜30μm) which has significantly different microstructures from the base material. The work-hardened layer leads to the phenomenon that most shear bands propagate along a given direction, clockwise or counterclockwise. In our simulation, periodical single direction spiral perturbations were applied to describe the grain orientation in the work-hardened layer, and the single direction spiral pattern of shear bands was successfully replicated.

Mechanosensation Dynamically Coordinates Polar Growth and Cell Wall Assembly to Promote Cell Survival.

PubMed

Davì, Valeria; Tanimoto, Hirokazu; Ershov, Dmitry; Haupt, Armin; De Belly, Henry; Le Borgne, Rémi; Couturier, Etienne; Boudaoud, Arezki; Minc, Nicolas

2018-04-23

How growing cells cope with size expansion while ensuring mechanical integrity is not known. In walled cells, such as those of microbes and plants, growth and viability are both supported by a thin and rigid encasing cell wall (CW). We deciphered the dynamic mechanisms controlling wall surface assembly during cell growth, using a sub-resolution microscopy approach to monitor CW thickness in live rod-shaped fission yeast cells. We found that polar cell growth yielded wall thinning and that thickness negatively influenced growth. Thickness at growing tips exhibited a fluctuating behavior with thickening phases followed by thinning phases, indicative of a delayed feedback promoting thickness homeostasis. This feedback was mediated by mechanosensing through the CW integrity pathway, which probes strain in the wall to adjust synthase localization and activity to surface growth. Mutants defective in thickness homeostasis lysed by rupturing the wall, demonstrating its pivotal role for walled cell survival. Copyright © 2018 Elsevier Inc. All rights reserved.

Myocardium wall thickness transducer and measuring method

NASA Technical Reports Server (NTRS)

Feldstein, C.; Lewis, G. W.; Silver, R. H.; Culler, V. H. (Inventor)

1976-01-01

A miniature transducer for measuring changes of thickness of the myocardium is described. The device is easily implantable without traumatizing the subject, without affecting the normal muscle behavior, and is removable and implantable at a different muscle location. Operating features of the device are described.

Production test IP-544-A, irradiation of 1.6% enriched thick walled single tube elements in KER-1 and 2

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

Kratzer, W.K.; Wise, M.J.

1962-12-12

The objective of this production test is to authorize the irradiation of coextruded Zr-2 jacketed thick walled 1.6% enriched tubular elements in KER loops 1 and 2 to evaluate the swelling behavior of fuel elements at high uranium temperatures Coextruded Zr-2 jacketed 1.6% enriched tubular fuel elements 1.79 inch OD, 0.97 inch ID, and 12 inches long will be irradiated KER loops 1 and 2 to exposures no greater than 2500 MWD/T.

Novel 3D ultrasound image-based biomarkers based on a feature selection from a 2D standardized vessel wall thickness map: a tool for sensitive assessment of therapies for carotid atherosclerosis

NASA Astrophysics Data System (ADS)

Chiu, Bernard; Li, Bing; Chow, Tommy W. S.

2013-09-01

With the advent of new therapies and management strategies for carotid atherosclerosis, there is a parallel need for measurement tools or biomarkers to evaluate the efficacy of these new strategies. 3D ultrasound has been shown to provide reproducible measurements of plaque area/volume and vessel wall volume. However, since carotid atherosclerosis is a focal disease that predominantly occurs at bifurcations, biomarkers based on local plaque change may be more sensitive than global volumetric measurements in demonstrating efficacy of new therapies. The ultimate goal of this paper is to develop a biomarker that is based on the local distribution of vessel-wall-plus-plaque thickness change (VWT-Change) that has occurred during the course of a clinical study. To allow comparison between different treatment groups, the VWT-Change distribution of each subject must first be mapped to a standardized domain. In this study, we developed a technique to map the 3D VWT-Change distribution to a 2D standardized template. We then applied a feature selection technique to identify regions on the 2D standardized map on which subjects in different treatment groups exhibit greater difference in VWT-Change. The proposed algorithm was applied to analyse the VWT-Change of 20 subjects in a placebo-controlled study of the effect of atorvastatin (Lipitor). The average VWT-Change for each subject was computed (i) over all points in the 2D map and (ii) over feature points only. For the average computed over all points, 97 subjects per group would be required to detect an effect size of 25% that of atorvastatin in a six-month study. The sample size is reduced to 25 subjects if the average were computed over feature points only. The introduction of this sensitive quantification technique for carotid atherosclerosis progression/regression would allow many proof-of-principle studies to be performed before a more costly and longer study involving a larger population is held to confirm the treatment

Compound Walls For Vacuum Chambers

NASA Technical Reports Server (NTRS)

Frazer, Robert E.

1988-01-01

Proposed compound-wall configuration enables construction of large high-vacuum chambers without having to use thick layers of expensive material to obtain necessary strength. Walls enclose chambers more than 1 m in diameter and several kilometers long. Compound wall made of strong outer layer of structural-steel culvert pipe welded to thin layer of high-quality, low-outgassing stainless steel.

Measuring Thicknesses of Wastewater Films

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Davenport, R. J.

1987-01-01

Sensor determines when thickness of film of electrically conductive wastewater on rotating evaporator drum exceeds preset value. Sensor simple electrical probe that makes contact with liquid surface. Made of materials resistant to chemicals in liquid. Mounted on shaft in rotating cylinder, liquid-thickness sensor extends toward cylinder wall so tip almost touches. Sensor body accommodates probe measuring temperature of evaporated water in cylinder.

[Endoscopic full-thickness resection].

PubMed

Meier, B; Schmidt, A; Caca, K

2016-08-01

Conventional endoscopic resection techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) are powerful tools for the treatment of gastrointestinal (GI) neoplasms. However, those techniques are limited to the superficial layers of the GI wall (mucosa and submucosa). Lesions without lifting sign (usually arising from deeper layers) or lesions in difficult anatomic positions (appendix, diverticulum) are difficult - if not impossible - to resect using conventional techniques, due to the increased risk of complications. For larger lesions (>2 cm), ESD appears to be superior to the conventional techniques because of the en bloc resection, but the procedure is technically challenging, time consuming, and associated with complications even in experienced hands. Since the development of the over-the-scope clips (OTSC), complications like bleeding or perforation can be endoscopically better managed. In recent years, different endoscopic full-thickness resection techniques came to the focus of interventional endoscopy. Since September 2014, the full-thickness resection device (FTRD) has the CE marking in Europe for full-thickness resection in the lower GI tract. Technically the device is based on the OTSC system and combines OTSC application and snare polypectomy in one step. This study shows all full-thickness resection techniques currently available, but clearly focuses on the experience with the FTRD in the lower GI tract.

Droplet-air collision dynamics: Evolution of the film thickness

NASA Astrophysics Data System (ADS)

Opfer, L.; Roisman, I. V.; Venzmer, J.; Klostermann, M.; Tropea, C.

2014-01-01

This study is devoted to the experimental and theoretical investigation of aerodynamic drop breakup phenomena. We show that the phenomena of drop impact onto a rigid wall, drop binary collisions, and aerodynamic drop deformation are similar if the correct scaling is applied. Then we use observations of the deforming drop to estimate the evolution of the film thickness of the bag, the value that determines the size of the fine child drops produced by bag breakup. This prediction of film thickness, based on film kinematics, is validated for the initial stage by direct drop thickness measurements and at the latest stage by the data obtained from the velocity of hole expansion in the film. It is shown that the film thickness correlates well with the dimensionless position of the bag apex.

Wall Thickness, Pulmonary Hypertension, and Diastolic Filling Abnormalities Predict Response to Postoperative Biventricular Pacing

PubMed Central

Brusen, Robin M.; Hahn, Rebecca; Cabreriza, Santos E.; Cheng, Bin; Wang, Daniel Y.; Truong, Wanda; Spotnitz, Henry M.

2017-01-01

Objective Post-cardiopulmonary bypass biventricular pacing improves hemodynamics but without clearly defined predictors of response. Based on preclinical studies and prior observations, it was suspected that diastolic dysfunction or pulmonary hypertension is predictive of hemodynamic benefit. Design Randomized controlled study of temporary biventricular pacing after cardiopulmonary bypass. Setting Single-center study at university-affiliated tertiary care hospital. Interventions Patients who underwent bypass with pre-operative ejection fraction ≤40% and QRS duration ≥100 ms or double-valve surgery were enrolled. At 3 time points between separation from bypass and postoperative day 1, pacing delays were varied to optimize hemodynamics. Participants Data from 43 patients were analyzed. Measurements and Main Results Cardiac output and arterial pressure were measured under no pacing, atrial pacing, and biventricular pacing. Preoperative echocardiograms and pulmonary artery catheterizations were reviewed, and measures of both systolic and diastolic function were compared to hemodynamic response. Early after separation, improvement in cardiac output was positively correlated with pulmonary vascular resistance (R2 = 0.97, p < 0.001), ventricle wall thickness (R2 = 0.72, p = 0.002)), and E/e′, a measure of abnormal diastolic ventricular filling velocity (R2 = 0.56, p = 0.04). Similar trends were seen with mean arterial pressure. QRS duration and ejection fraction did not correlate significantly with improvements in hemodynamics. Conclusions There may be an effect of biventricular pacing related to amelioration of abnormal diastolic filling patterns rather than electrical resynchronization in the postoperative state. PMID:25998068

Model-based cartilage thickness measurement in the submillimeter range

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

Streekstra, G. J.; Strackee, S. D.; Maas, M.

2007-09-15

Current methods of image-based thickness measurement in thin sheet structures utilize second derivative zero crossings to locate the layer boundaries. It is generally acknowledged that the nonzero width of the point spread function (PSF) limits the accuracy of this measurement procedure. We propose a model-based method that strongly reduces PSF-induced bias by incorporating the PSF into the thickness estimation method. We estimated the bias in thickness measurements in simulated thin sheet images as obtained from second derivative zero crossings. To gain insight into the range of sheet thickness where our method is expected to yield improved results, sheet thickness wasmore » varied between 0.15 and 1.2 mm with an assumed PSF as present in the high-resolution modes of current computed tomography (CT) scanners [full width at half maximum (FWHM) 0.5-0.8 mm]. Our model-based method was evaluated in practice by measuring layer thickness from CT images of a phantom mimicking two parallel cartilage layers in an arthrography procedure. CT arthrography images of cadaver wrists were also evaluated, and thickness estimates were compared to those obtained from high-resolution anatomical sections that served as a reference. The thickness estimates from the simulated images reveal that the method based on second derivative zero crossings shows considerable bias for layers in the submillimeter range. This bias is negligible for sheet thickness larger than 1 mm, where the size of the sheet is more than twice the FWHM of the PSF but can be as large as 0.2 mm for a 0.5 mm sheet. The results of the phantom experiments show that the bias is effectively reduced by our method. The deviations from the true thickness, due to random fluctuations induced by quantum noise in the CT images, are of the order of 3% for a standard wrist imaging protocol. In the wrist the submillimeter thickness estimates from the CT arthrography images correspond within 10% to those estimated from the

Measurement of wall thickness alone does not accurately assess the presence of left ventricular hypertrophy.

PubMed

Leibowitz, David; Planer, David; Ben-Ibgi, Fanny; Rott, David; Weiss, A Teddy; Bursztyn, Michael

2007-02-01

Clinical echocardiographic assessment of left ventricular hypertrophy (LVH) is generally performed by measuring wall thickness alone (WT). The objective of this study was to compare the assessment of LVH using the measurement of WT to that using indexed LV mass. Hypertensive patients underwent echocardiography with the measurement of LV WT and LV mass. For each patient, the presence of LVH was assessed by both methods with WT compared to the gold standard of LV mass index. In all, 92 patients (51M/41F) were entered, and in only 55 patients (60%) were the two methods concordant. There was a tendency for WT to underestimate LVH in females (sensitivity 37%, specificity 79%) and overestimate LVH in males (sensitivity 88%, specificity 56%). The measurement of WT alone overestimates LVH in males and underestimates LVH in females and should not be used as a surrogate marker for increased LV mass.

Integrated thick-film nanostructures based on spinel ceramics

PubMed Central

2014-01-01

Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications. PMID:24670141

Construction of Reference Data for Tissue Characterization of Arterial Wall Based on Elasticity Images

NASA Astrophysics Data System (ADS)

Inagaki, Jun; Hasegawa, Hideyuki; Kanai, Hiroshi; Ichiki, Masataka; Tezuka, Fumiaki

2005-06-01

Previously, we developed the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791] for measuring the minute change in thickness during one heartbeat and the elasticity of the arterial wall. By comparing pathological images with elasticity images measured with ultrasound, elasticity distributions for respective tissues in the arterial wall were determined. We have already measured the elasticity distributions for lipids and fibrous tissues (mixtures of smooth-muscle and collagen fiber) [H. Kanai et al.: Circulation 107 (2003) 3018]. In this study, elasticity distributions were measured for blood clots and calcified tissues. We discuss whether these elasticity distributions, which were measuerd in vitro, can be used as reference data for classifying cross-sectional elasticity images measured in vivo into respective tissues. In addition to the measurement of elasticity distributions, correlations between collagen content and elasticity were investigated with respect to fibrous tissue to estimate the collagen and smooth-muscle content based on elasticity. Collagen and smooth-muscle content may be important factors in determining the stability of the fibrous cap of atherosclerotic plaque. Therefore, correlations between elasticity and elements of the tissue in the arterial wall may provide useful information for the noninvasive diagnosis of plaque vulnerability.

Attenuation of radiation from distributed gamma sources as a function of wall thickness of a concrete blockhouse

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

Schmoke, M. A.; Rexroad, R. E.; Tiller, H. J.

1963-06-15

The experiment described constitutes part of the shielding program conducted by Army Nuclear Defense Laboratory and was designed to experimentally verify theoretical calculations used to predict the amount of radiation protection afforded by above-ground structures in a fallout radiation field. This method requires the knowledge of some physical parameters of a structure such as mass thickness of the walls and the geometric orientation of the detectors within the structure. From this information, a reduction factor for any given structure may be calculated. This Laboratory's experimental program was initially begun by measuring the attenuation of a simple structure with no complicatingmore » internal or external geometries and will proceed to more complex structures with basements, interior partitions, and upper floors. (auth)« less

Chaos Through-Wall Imaging Radar

NASA Astrophysics Data System (ADS)

Xu, Hang; Wang, Bingjie; Zhang, Jianguo; Liu, Li; Li, Ying; Wang, Yuncai; Wang, Anbang

2017-12-01

We experimentally demonstrate a chaos through-wall imaging radar using ultra-wideband chaotic-pulse-position modulation (CPPM) microwave signal. The CPPM signal based on logistic map with 1-ns pulse width and 1-GHz bandwidth is implemented by a field programmable gate array (FPGA) and then up-converted as the radar transmitting signal. Two-dimensional image of human objects behind obstacles is obtained by correlation method and back projection algorithm. Our experiments successfully perform through-wall imaging for single and multiple human objects through 20-cm thick wall. The down-range resolution of the proposed radar is 15 cm. Furthermore, the anti-jamming properties of the proposed radar in CPPM jamming, linear frequency-modulated jamming, and Gaussian noise jamming environments are demonstrated by electromagnetic simulations using the finite-difference time-domain. The simulation results show the CPPM microwave signal possesses excellent jamming immunity to the noise and radio frequency interference, which makes it perform superbly in multiradar environments.

Application of small panel damping measurements to larger walls

NASA Astrophysics Data System (ADS)

Hastings, Mardi C.; Godfrey, Richard; Babcock, G. Madison

1996-05-01

Damping properties of a viscoelastic material were determined using a standard resonant beam technique. The damping material was then applied to 1 by 2 foot gypsum panels in a constrained layer construction. Damping loss factors in panels with and without the constrained layer were determined based on reverberation times after excitation at third-octave band center frequencies. The constrained damping layer had been designed to increase damping by an order of magnitude above that of a single gypsum panel at 2000 Hz; however, relative to a gypsum panel of the same overall thickness as the panel with the constrained layer, loss factors increased only by a factor of three to five. Next modal damping loss factors in 9 by 14 foot gypsum single and double walls were calculated from the experimentally determined quality factor for each modal resonance. Results showed that below 2500 Hz, modes in 1 by 2 foot gypsum panels had nearly the same damping loss factors as modes in a 9 by 14 foot gypsum wall of the same thickness; however, loss factors for the wall were an order of magnitude lower than those of the 1 by 2 foot panels at frequencies above 2500 Hz, the coincidence frequency for 5/8-inch thick gypsum plates. Thus it was inconclusive whether or not damping loss factors measured using small panels could be used to estimate the effect of a constrained damping layer on transmission loss through a 9 by 14 foot wall unless boundary conditions and modal frequencies were the same for each size.

Human Uterine Wall Tension Trajectories and the Onset of Parturition

PubMed Central

Sokolowski, Peter; Saison, Francis; Giles, Warwick; McGrath, Shaun; Smith, David; Smith, Julia; Smith, Roger

2010-01-01

Uterine wall tension is thought to be an important determinant of the onset of labor in pregnant women. We characterize human uterine wall tension using ultrasound from the second trimester of pregnancy until parturition and compare preterm, term and twin pregnancies. A total of 320 pregnant women were followed from first antenatal visit to delivery during the period 2000–2004 at the John Hunter Hospital, NSW, Australia. The uterine wall thickness, length, anterior-posterior diameter and transverse diameter were determined by serial ultrasounds. Subjects were divided into three groups: women with singleton pregnancies and spontaneous labor onset, either preterm or term and women with twin pregnancies. Intrauterine pressure results from the literature were combined with our data to form trajectories for uterine wall thickness, volume and tension for each woman using the prolate ellipsoid method and the groups were compared at 20, 25 and 30 weeks gestation. Uterine wall tension followed an exponential curve, with results increasing throughout pregnancy with the site of maximum tension on the anterior wall. For those delivering preterm, uterine wall thickness was increased compared with term. For twin pregnancies intrauterine volume was increased compared to singletons (), but wall thickness was not. There was no evidence for increased tension in those delivering preterm or those with twin gestations. These data are not consistent with a role for high uterine wall tension as a causal factor in preterm spontaneous labor in singleton or twin gestations. It seems likely that hormonal differences in multiple gestations are responsible for increased rates of preterm birth in this group rather than increased tension. PMID:20585649

Intracranial arterial wall imaging using three-dimensional high isotropic resolution black blood MRI at 3.0 Tesla.

PubMed

Qiao, Ye; Steinman, David A; Qin, Qin; Etesami, Maryam; Schär, Michael; Astor, Brad C; Wasserman, Bruce A

2011-07-01

To develop a high isotropic-resolution sequence to evaluate intracranial vessels at 3.0 Tesla (T). Thirteen healthy volunteers and 4 patients with intracranial stenosis were imaged at 3.0T using 0.5-mm isotropic-resolution three-dimensional (3D) Volumetric ISotropic TSE Acquisition (VISTA; TSE, turbo spin echo), with conventional 2D-TSE for comparison. VISTA was repeated for 6 volunteers and 4 patients at 0.4-mm isotropic-resolution to explore the trade-off between SNR and voxel volume. Wall signal-to-noise-ratio (SNR(wall) ), wall-lumen contrast-to-noise-ratio (CNR(wall-lumen) ), lumen area (LA), wall area (WA), mean wall thickness (MWT), and maximum wall thickness (maxWT) were compared between 3D-VISTA and 2D-TSE sequences, as well as 3D images acquired at both resolutions. Reliability was assessed by intraclass correlations (ICC). Compared with 2D-TSE measurements, 3D-VISTA provided 58% and 74% improvement in SNR(wall) and CNR(wall-lumen) , respectively. LA, WA, MWT and maxWT from 3D and 2D techniques highly correlated (ICCs of 0.96, 0.95, 0.96, and 0.91, respectively). CNR(wall-lumen) using 0.4-mm resolution VISTA decreased by 27%, compared with 0.5-mm VISTA but with reduced partial-volume-based overestimation of wall thickness. Reliability for 3D measurements was good to excellent. The 3D-VISTA provides SNR-efficient, highly reliable measurements of intracranial vessels at high isotropic-resolution, enabling broad coverage in a clinically acceptable time. Copyright © 2011 Wiley-Liss, Inc.

Geomorphically based predictive mapping of soil thickness in upland watersheds

NASA Astrophysics Data System (ADS)

Pelletier, Jon D.; Rasmussen, Craig

2009-09-01

The hydrologic response of upland watersheds is strongly controlled by soil (regolith) thickness. Despite the need to quantify soil thickness for input into hydrologic models, there is currently no widely used, geomorphically based method for doing so. In this paper we describe and illustrate a new method for predictive mapping of soil thicknesses using high-resolution topographic data, numerical modeling, and field-based calibration. The model framework works directly with input digital elevation model data to predict soil thicknesses assuming a long-term balance between soil production and erosion. Erosion rates in the model are quantified using one of three geomorphically based sediment transport models: nonlinear slope-dependent transport, nonlinear area- and slope-dependent transport, and nonlinear depth- and slope-dependent transport. The model balances soil production and erosion locally to predict a family of solutions corresponding to a range of values of two unconstrained model parameters. A small number of field-based soil thickness measurements can then be used to calibrate the local value of those unconstrained parameters, thereby constraining which solution is applicable at a particular study site. As an illustration, the model is used to predictively map soil thicknesses in two small, ˜0.1 km2, drainage basins in the Marshall Gulch watershed, a semiarid drainage basin in the Santa Catalina Mountains of Pima County, Arizona. Field observations and calibration data indicate that the nonlinear depth- and slope-dependent sediment transport model is the most appropriate transport model for this site. The resulting framework provides a generally applicable, geomorphically based tool for predictive mapping of soil thickness using high-resolution topographic data sets.

Determination of the chest wall thicknesses and needle thoracostomy success rates at second and fifth intercostal spaces: a cadaver-based study.

PubMed

Ozen, Can; Akoglu, Haldun; Ozdemirel, Rifat Ozgur; Omeroglu, Elif; Ozpolat, Cigdem Ulubay; Onur, Ozge; Buyuk, Yalcin; Denizbasi, Arzu

2016-12-01

The purposes of this study were to measure the chest wall thicknesses (CWTs) at second intercostal space (ICS) mid-clavicular line (MCL) and fifth ICS MAL directly, and compare the actual success rates of needle thoracostomies (NTs) by inserting a 5-cm-long syringe needle. Predictive values of weight, body mass index (BMI) and CWT were also analyzed. This study included 199 measurements of 50 adult fresh cadavers from both hemithoraces. Five-centimeter-long syringe needles were inserted and secured. Penetration into the pleural cavity was assessed, and CWTs at 4 locations were measured. Achieved power of this study for the primary aim of CWT comparison from 2 nd and 5 th ICSs was .94. Overall mean CWTs at 2 nd ICS MCL and 5 th ICS MAL were measured as 2.46 ± 0.78 and 2.89 ± 1.09, respectively, and 5 th ICS MAL was found to be statistically thicker (P = .002). The success rate of NT at 2 nd ICS MCL was 87% (95% CI, 80-94), and that at 5 th ICS MAL was 78% (95% CI, 70-86; P = .3570). Only 6 (17.1%) of 35 failed NTs had a CWT greater than 5-cm. Needle thoracostomy has failed in 29 (14.9%) of 194 locations, despite a CWT less than 5-cm. Below a weight of 72 kg, BMI of 23 kg/m 2 , or CWT of 2.4 cm, all NTs were successful. In this report, we present the largest cadaver-based cohort to date to the best of our knowledge, and we observed a statistically nonsignificant 9% more NT success rate at 2 nd ICS at a power of 88% and statistically significant more success rate in males at 5 th ICS was (47.7%). We also observed thinner CWTs and higher success rates than previous imaging-based studies. A BMI of 23 kg/m 2 or less and weight of 72 kg or less seem to accurately rule-out NT failure in cadavers, and they seem to be better predictors at the bedside. Copyright © 2016 Elsevier Inc. All rights reserved.

Mathematical Model of Stress-Strain State of Curved Tube of Non-Circular Cross-Section with Account of Technological Wall Thickness Variation

NASA Astrophysics Data System (ADS)

Pirogov, S. P.; Ustinov, N. N.; Smolin, N. I.

2018-05-01

A mathematical model of the stress-strain state of a curved tube of a non-circular cross-section is presented, taking into account the technological wall thickness variation. On the basis of the semi-membrane shell theory, a system of linear differential equations describing the deformation of a tube under the effect of pressure is obtained. To solve the boundary value problem, the method of shooting is applied. The adequacy of the proposed mathematical model is verified by comparison with the experimental data and the results of the calculation of tubes by the energy method.

Instantaneous Optical Wall-Temperature of Vertical Two-Phase Annular Flow

NASA Astrophysics Data System (ADS)

Fehring, Brian; Livingston-Jha, Simon; Morse, Roman; Chan, Jason; Doherty, James; Brueggeman, Colby; Nellis, Gregory; Dressler, Kristofer; Berson, ArganthaëL.; Multiphase Flow Visualization; Analysis Laboratory at University of Wisconsin-Madison Team

2017-11-01

We present a non-invasive optical technique for measuring the instantaneous temperature at the inner wall of a flow duct. The technique is used to characterize a fully-developed vertical annular flow of R245fa refrigerant. The test section includes transparent heating windows made of glass coated with fluorine-doped tin-oxide. A 15 mW helium-neon laser is directed through a prism mounted on one of the glass windows and reflected off of the interface between the 150-micron-thick liquid film and the inside wall of the testing section window. The intensity of the laser light reflected at the liquid film-window interface depends on the index of refraction of liquid R245fa, which itself depends on the temperature of the fluid. The intensity of the reflected light is measured using a photodiode and calibrated to a light reflectance model based on the Fresnel equations and Snell's law. Instantaneous temperature data is combined with optical liquid film thickness measurements to calculate the local instantaneous heat transfer coefficient at the wall.

RADIOAUTOGRAPHIC STUDY OF CELL WALL DEPOSITION IN GROWING PLANT CELLS

PubMed Central

Ray, Peter M.

1967-01-01

Segments cut from growing oat coleoptiles and pea stems were fed glucose-3H in presence and absence of the growth hormone indoleacetic acid (IAA). By means of electron microscope radioautography it was demonstrated that new cell wall material is deposited both at the wall surface (apposition) and within the preexisting wall structure (internally). Quantitative profiles for the distribution of incorporation with position through the thickness of the wall were obtained for the thick outer wall of epidermal cells. With both oat coleoptile and pea stem epidermal outer walls, it was found that a larger proportion of the newly synthesized wall material appeared to become incorporated within the wall in the presence of IAA. Extraction experiments on coleoptile tissue showed that activity that had been incorporated into the cell wall interior represented noncellulosic constituents, mainly hemicelluloses, whereas cellulose was deposited largely or entirely by apposition. It seems possible that internal incorporation of hemicelluloses plays a role in the cell wall expansion process that is involved in cell growth. PMID:6064369

Effects of spaceflight on polysaccharides of Saccharomyces cerevisiae cell wall.

PubMed

Liu, Hong-Zhi; Wang, Qiang; Liu, Xiao-Yong; Tan, Sze-Sze

2008-12-01

Freeze-dried samples of four Saccharomyces cerevisiae strains, namely, FL01, FL03, 2.0016, and 2.1424, were subjected to spaceflight. After the satellite's landing on Earth, the samples were recovered and changes in yeast cell wall were analyzed. Spaceflight strains of all S. cerevisiae strains showed significant changes in cell wall thickness (P < 0.05). One mutant of S. cerevisiae 2.0016 with increased biomass, cell wall thickness, and cell wall glucan was isolated (P < 0.05). The spaceflight mutant of S. cerevisiae 2.0016 showed 46.7%, 62.6%, and 146.0% increment in biomass, cell wall thickness and beta-glucan content, respectively, when compared to the ground strain. Moreover, growth curve analysis showed spaceflight S. cerevisiae 2.0016 had a faster growth rate, shorter lag phase periods, higher final biomass, and higher content of beta-glucan. Genetic stability analysis showed that prolonged subculturing of spaceflight strain S. cerevisiae 2.0016 did not lead to the appearance of variants, indicating that the genetic stability of S. cerevisiae 2.0016 mutant could be sufficient for its exploitation of beta-glucan production.

Direct measurement of wall slip and slip layer thickness of non-Brownian hard-sphere suspensions in rectangular channel flows

NASA Astrophysics Data System (ADS)

Jesinghausen, Steffen; Weiffen, Rene; Schmid, Hans-Joachim

2016-09-01

Wall slip is a long-known phenomenon in the field of rheology. Nevertheless, the origin and the evolution are not completely clear yet. Regarding suspensions, the effect becomes even more complicated, because different mechanisms like pure slip or slip due to particle migration have to be taken into account. Furthermore, suspensions themselves show many flow anomalies and the isolation of slip is complicated. In order to develop working physical models, further insight is necessary. In this work, we measured experimentally the wall slip velocities of different highly filled suspensions in a rectangular slit die directly with respect to the particle concentration and the particle size. The slip velocities were obtained using a particle image velocimetry (PIV) system. The suspensions consisting of a castor oil-cinnamon oil blend and PMMA particles were matched in terms of refractive indexes to appear transparent. Hereby, possible optical path lengths larger than 15 mm were achieved. The slip velocities were found to be in a quadratic relation to the wall shear stress. Furthermore, the overall flow rate as well as the particle concentration has a direct influence on the slip. Concerning the shear stress, there seem to be two regions of slip with different physical characteristics. Furthermore, we estimated the slip layer thickness directly from the velocity profiles and propose a new interpretation. The PIV technique is used to investigate the viscosity and implicit the concentration profile in the slit die. It is shown that the particle migration process is quite fast.

Behavior of turbulent boundary layers on curved convex walls

NASA Technical Reports Server (NTRS)

Schmidbauer, Hans

1936-01-01

The system of linear differential equations which indicated the approach of separation and the so-called "boundary-layer thickness" by Gruschwitz is extended in this report to include the case where the friction layer is subject to centrifugal forces. Evaluation of the data yields a strong functional dependence of the momentum change and wall drag on the boundary-layer thickness radius of curvature ratio for the wall. It is further shown that the transition from laminar to turbulent flow occurs at somewhat higher Reynolds Numbers at the convex wall than at the flat plate, due to the stabilizing effect of the centrifugal forces.

Graphical determination of wall temperatures for heat transfers through walls of arbitrary shape

NASA Technical Reports Server (NTRS)

Lutz, Otto

1950-01-01

A graphical method is given which permits determining of the temperature distribution during heat transfer in arbitrarily shaped walls. Three examples show the application of the method. The further development of heat engines depends to a great extent on the control of the thermal stresses in the walls. The thermal stresses stem from the nonuniform temperature distribution in heat transfer through walls which are, for structural reasons, of various thicknesses and sometimes complicated shape. Thus, it is important to know the temperature distribution in these structural parts. Following, a method is given which permits solution of this problem.

Concise biomarker for spatial-temporal change in three-dimensional ultrasound measurement of carotid vessel wall and plaque thickness based on a graph-based random walk framework: Towards sensitive evaluation of response to therapy.

PubMed

Chiu, Bernard; Chen, Weifu; Cheng, Jieyu

2016-12-01

Rapid progression in total plaque area and volume measured from ultrasound images has been shown to be associated with an elevated risk of cardiovascular events. Since atherosclerosis is focal and predominantly occurring at the bifurcation, biomarkers that are able to quantify the spatial distribution of vessel-wall-plus-plaque thickness (VWT) change may allow for more sensitive detection of treatment effect. The goal of this paper is to develop simple and sensitive biomarkers to quantify the responsiveness to therapies based on the spatial distribution of VWT-Change on the entire 2D carotid standardized map previously described. Point-wise VWT-Changes computed for each patient were reordered lexicographically to a high-dimensional data node in a graph. A graph-based random walk framework was applied with the novel Weighted Cosine (WCos) similarity function introduced, which was tailored for quantification of responsiveness to therapy. The converging probability of each data node to the VWT regression template in the random walk process served as a scalar descriptor for VWT responsiveness to treatment. The WCos-based biomarker was 14 times more sensitive than the mean VWT-Change in discriminating responsive and unresponsive subjects based on the p-values obtained in T-tests. The proposed framework was extended to quantify where VWT-Change occurred by including multiple VWT-Change distribution templates representing focal changes at different regions. Experimental results show that the framework was effective in classifying carotid arteries with focal VWT-Change at different locations and may facilitate future investigations to correlate risk of cardiovascular events with the location where focal VWT-Change occurs. Copyright © 2016 Elsevier Ltd. All rights reserved.

A model to predict radon exhalation from walls to indoor air based on the exhalation from building material samples.

PubMed

Sahoo, B K; Sapra, B K; Gaware, J J; Kanse, S D; Mayya, Y S

2011-06-01

In recognition of the fact that building materials are an important source of indoor radon, second only to soil, surface radon exhalation fluxes have been extensively measured from the samples of these materials. Based on this flux data, several researchers have attempted to predict the inhalation dose attributable to radon emitted from walls and ceilings made up of these materials. However, an important aspect not considered in this methodology is the enhancement of the radon flux from the wall or the ceiling constructed using the same building material. This enhancement occurs mainly because of the change in the radon diffusion process from the former to the latter configuration. To predict the true radon flux from the wall based on the flux data of building material samples, we now propose a semi-empirical model involving radon diffusion length and the physical dimensions of the samples as well as wall thickness as other input parameters. This model has been established by statistically fitting the ratio of the solution to radon diffusion equations for the cases of three-dimensional cuboidal shaped building materials (such as brick, concrete block) and one dimensional wall system to a simple mathematical function. The model predictions have been validated against the measurements made at a new construction site. This model provides an alternative tool (substitute to conventional 1-D model) to estimate radon flux from a wall without relying on ²²⁶Ra content, radon emanation factor and bulk density of the samples. Moreover, it may be very useful in the context of developing building codes for radon regulation in new buildings. Copyright © 2011 Elsevier B.V. All rights reserved.

Microsurgical Chest Wall Reconstruction After Oncologic Resections

PubMed Central

Sauerbier, Michael; Dittler, S.; Kreutzer, C.

2011-01-01

Defect reconstruction after radical oncologic resection of malignant chest wall tumors requires adequate soft tissue reconstruction with function, stability, integrity, and an aesthetically acceptable result of the chest wall. The purpose of this article is to describe possible reconstructive microsurgical pathways after full-thickness oncologic resections of the chest wall. Several reliable free flaps are described, and morbidity and mortality rates of patients are discussed. PMID:22294944

A MULTI-ELEMENT THICK GAS ELECTRON MULTIPLIER-BASED MICRODOSEMETER FOR MEASUREMENT OF NEUTRONS DOSE-EQUIVALENT: A MONTE CARLO STUDY.

PubMed

Moslehi, A; Raisali, G

2017-11-01

To determine the dose-equivalent of neutrons in an extended energy range, in the present work a multi-element thick gas electron multiplier-based microdosemeter made of PMMA (Perspex) walls of 10 mm in thickness is designed. Each cavity is filled with the propane-based tissue-equivalent (TE) gas simulating 1 µm of tissue. Also, a few weight fractions of 3He are assumed to be added to the TE gas. The dose-equivalents are determined for 11 neutron energies between thermal and 14 MeV using the lineal energy distributions calculated by Geant4 simulation toolkit and also the lineal energy-based quality factors. The results show that by adding 0.04% of 3He to the TE gas in each cavity, an energy-independent dose-equivalent response within 30% uncertainty around a median value of 0.91 in the above energy range is achieved. It is concluded that after its construction, the studied microdosemeter can be used to measure the dose-equivalent of neutrons, favorably. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A thick-walled sphere rotating in a uniform magnetic field: The next step to de-spin a space object

NASA Astrophysics Data System (ADS)

Nurge, Mark A.; Youngquist, Robert C.; Caracciolo, Ryan A.; Peck, Mason; Leve, Frederick A.

2017-08-01

Modeling the interaction between a moving conductor and a static magnetic field is critical to understanding the operation of induction motors, eddy current braking, and the dynamics of satellites moving through Earth's magnetic field. Here, we develop the case of a thick-walled sphere rotating in a uniform magnetic field, which is the simplest, non-trivial, magneto-statics problem that leads to complete closed-form expressions for the resulting potentials, fields, and currents. This solution requires knowledge of all of Maxwell's time independent equations, scalar and vector potential equations, and the Lorentz force law. The paper presents four cases and their associated experimental results, making this topic appropriate for an advanced student lab project.

Automated airway evaluation system for multi-slice computed tomography using airway lumen diameter, airway wall thickness and broncho-arterial ratio

NASA Astrophysics Data System (ADS)

Odry, Benjamin L.; Kiraly, Atilla P.; Novak, Carol L.; Naidich, David P.; Lerallut, Jean-Francois

2006-03-01

Pulmonary diseases such as bronchiectasis, asthma, and emphysema are characterized by abnormalities in airway dimensions. Multi-slice computed tomography (MSCT) has become one of the primary means to depict these abnormalities, as the availability of high-resolution near-isotropic data makes it possible to evaluate airways at oblique angles to the scanner plane. However, currently, clinical evaluation of airways is typically limited to subjective visual inspection only: systematic evaluation of the airways to take advantage of high-resolution data has not proved practical without automation. We present an automated method to quantitatively evaluate airway lumen diameter, wall thickness and broncho-arterial ratios. In addition, our method provides 3D visualization of these values, graphically illustrating the location and extent of disease. Our algorithm begins by automatic airway segmentation to extract paths to the distal airways, and to create a map of airway diameters. Normally, airway diameters decrease as paths progress distally; failure to taper indicates abnormal dilatation. Our approach monitors airway lumen diameters along each airway path in order to detect abnormal profiles, allowing even subtle degrees of pathologic dilatation to be identified. Our method also systematically computes the broncho-arterial ratio at every terminal branch of the tree model, as a ratio above 1 indicates potentially abnormal bronchial dilatation. Finally, the airway wall thickness is computed at corresponding locations. These measurements are used to highlight abnormal branches for closer inspection, and can be summed to compute a quantitative global score for the entire airway tree, allowing reproducible longitudinal assessment of disease severity. Preliminary tests on patients diagnosed with bronchiectasis demonstrated rapid identification of lack of tapering, which also was confirmed by corresponding demonstration of elevated broncho-arterial ratios.

A benchmark study for the crown-type splashing dynamics of one- and two-component droplet wall-film interactions

NASA Astrophysics Data System (ADS)

Geppert, A.; Terzis, A.; Lamanna, G.; Marengo, M.; Weigand, B.

2017-12-01

The present paper investigates experimentally the impact dynamics of crown-type splashing for miscible two- and one-component droplet wall-film interactions over a range of Weber numbers and dimensionless film thicknesses. The splashing outcome is parametrised in terms of a set of quantifiable parameters, such as crown height, top and base diameter, wall inclination, number of fingers, and secondary droplet properties. The results show that the outcome of a splashing event is not affected by the choice of similar or dissimilar fluids, provided the dimensionless film thickness is larger than 0.1. Below this threshold, distinctive features of two-component interactions appear, such as hole formation and crown bottom breakdown. The observation of different crown shapes (e.g. V-shaped, cylindrical, and truncated-cone) confirms that vorticity production induces changes in the crown wall inclination, thus affecting the evolution of the crown height and top diameter. The evolution of the crown base diameter, instead, is mainly dependent on the relative importance of liquid inertia and viscous losses in the wall-film. The maximum number of liquid fingers decreases with increasing wall, film thickness, due to the enhanced attenuation of the effect of surface properties on the fingering process. The formation of secondary droplets is also affected by changes in the crown wall inclination. In particular, for truncated-cone shapes the occurrence of crown rim contraction induces a large scatter in the secondary droplet properties. Consequently, empirical models for the maximum number and mean diameter of the secondary droplets are derived for V-shaped crowns, as observed for the hexadecane-Hyspin interactions.

An ultrasonographic evaluation of skin thickness in breast cancer patients after postmastectomy radiation therapy

PubMed Central

2011-01-01

Background To determine the usefulness of ultrasonography in the assessment of post radiotherapy skin changes in postmastectomy breast cancer patients. Methods Patients treated for postmastectomy radiotherapy in National University Hospital (NUH) and Tan Tock Seng Hospital (TTSH), Singapore between January 2004- December 2005 was recruited retrospectively. Ultrasound scan was performed on these Asian patients who had been treated to a total dose of 46-50 Gy with 1 cm bolus placed on the skin. The ultrasound scans were performed blinded to the RTOG scores, and the skin thickness of the individually marked points on the irradiated chest wall was compared to the corresponding points on the non-irradiated breast. Results The mean total skin thickness inclusive of the epidermis and the dermis of the right irradiated chest wall was 0.1712 mm (± 0.03392 mm) compared with the contra-lateral non-irradiated breast which was 0.1845 mm (± 0.04089 mm; p = 0.007). The left irradiated chest wall had a mean skin thickness of 0.1764 mm (± 0.03184 mm) compared with the right non-irradiated breast which was 0.1835 mm (± 0.02584 mm; p = 0.025). These independent t-tests produced a significant difference of reduced skin thickness on the right irradiated chest wall, p = 0.007 (p < 0.05) and left irradiated chest wall p = 0.025 (p < 0.025) in comparison to the non-irradiated skin thickness investigating chronic skin reactions. Patients with grade 2 acute skin toxicity presented with thinner skin as compared to patients with grade 1 (p = 0.006). Conclusions This study has shown that there is a statistically significant difference between the skin thicknesses of the irradiated chest wall and the contra-lateral non-irradiated breast and a predisposition to chronic reactions was found in patients with acute RTOG scoring of grade1 and grade 2. PMID:21261940

Measurement of defect thickness of the wall thinning defect pipes by lock-in infrared thermography technique

NASA Astrophysics Data System (ADS)

Kim, Kyeongsuk; Kim, Kyungsu; Jung, Hyunchul; Chang, Hosub

2010-03-01

Mostly piping which is using for the nuclear power plants are made up of carbon steel pipes. The wall thinning defects occurs by the effect of the flow accelerated corrosion of fluid that flows in carbon steel pipes. The defects could be found on the welding part and anywhere in the pipes. The infrared thermography technique which is one of the non-destructive testing method has used for detecting the defects of various kinds of materials over the years. There is a limitation for measuring the defect of metals that have a big coefficient of thermal diffusion. However, a technique using lock-in method gets over the difficulty. Consequently, the lock-in infrared thermography technique has been applied to the various industry fields. In this paper, the defect thickness of the straight pipe which has an artificial defect the inside of the pipes was measured by using the lock-in infrared thermography technique and the result could be utilized in detecting defects of carbon steel pipes.

Measure Guideline: Incorporating Thick Layers of Exterior Rigid Insulation on Walls

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

Lstiburek, Joseph; Baker, Peter

This measure guideline provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ inches and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: fundamental building science principles relating to the use of exterior insulation on wall assemblies; design principles for tailoring this use to the specific project goals and requirements; and construction detailing to increase understanding about implementing the various design elements.

Pressure sensor based on pristine multi-walled carbon nanotubes forest

NASA Astrophysics Data System (ADS)

Yasar, M.; Mohamed, N. M.; Hamid, N. H.; Shuaib, M.

2016-11-01

In the course of the most recent decade, carbon nanotubes (CNTs) have been developed as alternate material for many sensing applications because of their interesting properties. Their outstanding electromechanical properties make them suitable for pressure/strain sensing application. Other than in view of their structure and number of walls (i.e. Single-Walled CNTs and MultiWalled CNTs), carbon nanotubes can likewise be classified based on their orientation and combined arrangement. One such classification is vertically aligned Multi-Walled Carbon Nanotubes (VA-MWCNTs), regularly termed as CNTs arrays, foam or forest which is macro scale form of CNTs. Elastic behavior alongside exceptional electromechanical (high gauge factor) make it suitable for pressure sensing applications. This paper presents pressure sensor based on such carbon nanotubes forest in pristine form which enables it to perform over wider temperature range as compared to pressure sensors based on conventional materials such as Silicon.

Quantification of fibrous cap thickness in intracoronary optical coherence tomography with a contour segmentation method based on dynamic programming.

PubMed

Zahnd, Guillaume; Karanasos, Antonios; van Soest, Gijs; Regar, Evelyn; Niessen, Wiro; Gijsen, Frank; van Walsum, Theo

2015-09-01

Fibrous cap thickness is the most critical component of plaque stability. Therefore, in vivo quantification of cap thickness could yield valuable information for estimating the risk of plaque rupture. In the context of preoperative planning and perioperative decision making, intracoronary optical coherence tomography imaging can provide a very detailed characterization of the arterial wall structure. However, visual interpretation of the images is laborious, subject to variability, and therefore not always sufficiently reliable for immediate decision of treatment. A novel semiautomatic segmentation method to quantify coronary fibrous cap thickness in optical coherence tomography is introduced. To cope with the most challenging issue when estimating cap thickness (namely the diffuse appearance of the anatomical abluminal interface to be detected), the proposed method is based on a robust dynamic programming framework using a geometrical a priori. To determine the optimal parameter settings, a training phase was conducted on 10 patients. Validated on a dataset of 179 images from 21 patients, the present framework could successfully extract the fibrous cap contours. When assessing minimal cap thickness, segmentation results from the proposed method were in good agreement with the reference tracings performed by a medical expert (mean absolute error and standard deviation of 22 ± 18 μm) and were similar to inter-observer reproducibility (21 ± 19 μm, R = .74), while being significantly faster and fully reproducible. The proposed framework demonstrated promising performances and could potentially be used for online identification of high-risk plaques.

Lamb mode selection for accurate wall loss estimation via guided wave tomography

NASA Astrophysics Data System (ADS)

Huthwaite, P.; Ribichini, R.; Lowe, M. J. S.; Cawley, P.

2014-02-01

Guided wave tomography offers a method to accurately quantify wall thickness losses in pipes and vessels caused by corrosion. This is achieved using ultrasonic waves transmitted over distances of approximately 1-2m, which are measured by an array of transducers and then used to reconstruct a map of wall thickness throughout the inspected region. To achieve accurate estimations of remnant wall thickness, it is vital that a suitable Lamb mode is chosen. This paper presents a detailed evaluation of the fundamental modes, S0 and A0, which are of primary interest in guided wave tomography thickness estimates since the higher order modes do not exist at all thicknesses, to compare their performance using both numerical and experimental data while considering a range of challenging phenomena. The sensitivity of A0 to thickness variations was shown to be superior to S0, however, the attenuation from A0 when a liquid loading was present was much higher than S0. A0 was less sensitive to the presence of coatings on the surface of than S0.

Analysis of the Effect of Osteon Diameter on the Potential Relationship of Osteocyte Lacuna Density and Osteon Wall Thickness

PubMed Central

Skedros, John G.; Clark, Gunnar C.; Sorenson, Scott M.; Taylor, Kevin W.; Qiu, Shijing

2011-01-01

An important hypothesis is that the degree of infilling of secondary osteons (Haversian systems) is controlled by the inhibitory effect of osteocytes on osteoblasts, which might be mediated by sclerostin (a glycoprotein produced by osteocytes). Consequently, this inhibition could be proportional to cell number: relatively greater repression is exerted by progressively greater osteocyte density (increased osteocytes correlate with thinner osteon walls). This hypothesis has been examined, but only weakly supported, in sheep ulnae. We looked for this inverse relationship between osteon wall thickness (On.W.Th) and osteocyte lacuna density (Ot.Lc.N/B.Ar) in small and large osteons in human ribs, calcanei of sheep, deer, elk, and horses, and radii and third metacarpals of horses. Analyses involved: (1) all osteons, (2) smaller osteons, either ≤150μm diameter or ≤ the mean diameter, and (3) larger osteons (>mean diameter). Significant, but weak, correlations between Ot.Lc.N/B.Ar and On.W.Th/On.Dm (On.Dm = osteon diameter) were found when considering all osteons in limb bones (r values −0.16 to −0.40, p<0.01; resembling previous results in sheep ulnae: r= −0.39, p<0.0001). In larger osteons, these relationships were either not significant (five/seven bone types) or very weak (two/seven bone types). In ribs, a negative relationship was only found in smaller osteons (r= −0.228, p<0.01); this inverse relationship in smaller osteons did not occur in elk calcanei. These results do not provide clear or consistent support for the hypothesized inverse relationship. However, correlation analyses may fail to detect osteocyte-based repression of infilling if the signal is spatially non-uniform (e.g., increased near the central canal). PMID:21809466

Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

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

Kochkin, V.; Wiehagen, J.

2017-06-01

Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

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

Kochkin, V.; Wiehagen, J.

Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

CFD-DEM study of effect of bed thickness for bubbling fluidized beds

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

Tingwen, Li; Gopalakrishnan, Pradeep; Garg, Rahul

2011-10-01

The effect of bed thickness in rectangular fluidized beds is investigated through the CFD–DEM simulations of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and particle kinetic energy. Good two-dimensional (2D) flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional (3D) flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20–40 particle diameters. Comparison ofmore » velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.« less

Ultrasound determination of chest wall thickness: implications for needle thoracostomy.

PubMed

McLean, A Robb; Richards, Michael E; Crandall, Cameron S; Marinaro, Jonathan L

2011-11-01

Computed tomography measurements of chest wall thickness (CWT) suggest that standard-length angiocatheters (4.5 cm) may fail to decompress tension pneumothoraces. We used an alternative modality, ultrasound, to measure CWT. We correlated CWT with body mass index (BMI) and used national data to estimate the percentage of patients with CWT greater than 4.5 cm. This was an observational, cross-sectional study of a convenience sample. We recorded standing height, weight, and sex. We measured CWT with ultrasound at the second intercostal space, midclavicular line and at the fourth intercostal space, midaxillary line on supine subjects. We correlated BMI (weight [in kilograms]/height(2) [in square meters]) with CWT using linear regression. 95% Confidence intervals (CIs) assessed statistical significance. National Health and Nutrition Examination Survey results for 2007-2008 were combined to estimate national BMI adult measurements. Of 51 subjects, 33 (65%) were male and 18 (35%) were female. Mean anterior CWT (male, 2.1 cm; CI, 1.9-2.3; female, 2.3 cm; CI, 1.7-2.7), lateral CWT (male, 2.4 cm; CI, 2.1-2.6; female, 2.5 cm; CI 2.0-2.9), and BMI (male, 27.7; CI, 26.1-29.3; female, 30.0; CI, 25.8-34.2) did not differ by sex. Lateral CWT was greater than anterior CWT (0.2 cm; CI, 0.1-0.4; P < .01). Only one subject with a BMI of 48.2 had a CWT that exceeded 4.5 cm. Using national BMI estimates, less than 1% of the US population would be expected to have CWT greater than 4.5 cm. Ultrasound measurements suggest that most patients will have CWT less than 4.5 cm and that CWT may not be the source of the high failure rate of needle decompression in tension pneumothorax. Copyright © 2011 Elsevier Inc. All rights reserved.

Automatic lumen and outer wall segmentation of the carotid artery using deformable three-dimensional models in MR angiography and vessel wall images.

PubMed

van 't Klooster, Ronald; de Koning, Patrick J H; Dehnavi, Reza Alizadeh; Tamsma, Jouke T; de Roos, Albert; Reiber, Johan H C; van der Geest, Rob J

2012-01-01

To develop and validate an automated segmentation technique for the detection of the lumen and outer wall boundaries in MR vessel wall studies of the common carotid artery. A new segmentation method was developed using a three-dimensional (3D) deformable vessel model requiring only one single user interaction by combining 3D MR angiography (MRA) and 2D vessel wall images. This vessel model is a 3D cylindrical Non-Uniform Rational B-Spline (NURBS) surface which can be deformed to fit the underlying image data. Image data of 45 subjects was used to validate the method by comparing manual and automatic segmentations. Vessel wall thickness and volume measurements obtained by both methods were compared. Substantial agreement was observed between manual and automatic segmentation; over 85% of the vessel wall contours were segmented successfully. The interclass correlation was 0.690 for the vessel wall thickness and 0.793 for the vessel wall volume. Compared with manual image analysis, the automated method demonstrated improved interobserver agreement and inter-scan reproducibility. Additionally, the proposed automated image analysis approach was substantially faster. This new automated method can reduce analysis time and enhance reproducibility of the quantification of vessel wall dimensions in clinical studies. Copyright © 2011 Wiley Periodicals, Inc.

Wall-pressure fluctuations beneath a spatially evolving turbulent boundary layer

NASA Astrophysics Data System (ADS)

Mahesh, Krishnan; Kumar, Praveen

2016-11-01

Wall-pressure fluctuations beneath a turbulent boundary layer are important in applications dealing with structural deformation and acoustics. Simulations are performed for flat plate and axisymmetric, spatially evolving zero-pressure-gradient turbulent boundary layers at inflow Reynolds number of 1400 and 2200 based on momentum thickness. The simulations generate their own inflow using the recycle-rescale method. The results for mean velocity and second-order statistics show excellent agreement with the data available in literature. The spectral characteristics of wall-pressure fluctuations and their relation to flow structure will be discussed. This work is supported by ONR.

Effect of the body wall on lithotripter shock waves.

PubMed

Li, Guangyan; McAteer, James A; Williams, James C; Berwick, Zachary C

2014-04-01

Determine the influence of passage through the body wall on the properties of lithotripter shock waves (SWs) and the characteristics of the acoustic field of an electromagnetic lithotripter. Full-thickness ex vivo segments of pig abdominal wall were secured against the acoustic window of a test tank coupled to the lithotripter. A fiber-optic probe hydrophone was used to measure SW pressures, determine shock rise time, and map the acoustic field in the focal plane. Peak positive pressure on axis was attenuated roughly proportional to tissue thickness-approximately 6% per cm. Irregularities in the tissue path affected the symmetry of SW focusing, shifting the maximum peak positive pressure laterally by as much as ∼2 mm. Within the time resolution of the hydrophone (7-15 ns), shock rise time was unchanged, measuring ∼17-21 ns with and without tissue present. Mapping of the field showed no effect of the body wall on focal width, regardless of thickness of the body wall. Passage through the body wall has minimal effect on the characteristics of lithotripter SWs. Other than reducing pulse amplitude and having the potential to affect the symmetry of the focused wave, the body wall has little influence on the acoustic field. These findings help to validate laboratory assessment of lithotripter acoustic field and suggest that the properties of SWs in the body are much the same as have been measured in vitro.

Partial Insulation of Aerated Concrete Wall in its Thermal Bridge Regions

NASA Astrophysics Data System (ADS)

Li, Baochang; Guo, Lirong; Li, Yubao; Zhang, Tiantian; Tan, Yufei

2018-01-01

As a self-insulating building material which can meet the 65 percent energy-efficiency requirements in cold region of China, aerated concrete blocks often go moldy, frost heaving, or cause plaster layer hollowing at thermal bridge parts in the extremely cold regions due to the restrictions of environmental climate and construction technique. In this paper, partial insulation measures of the thermal-bridge position of these parts of aerated concrete walls are designed to weaken or even eliminate thermal bridge effect and improve the temperature of thermal-bridge position. A heat transfer calculation model for L-shaped wall and T-shaped wall is developed. Based on the simulation result, the influence of the thickness on the temperature field is analyzed. Consequently, the condensation inside self-thermal-insulating wall and frost heaving caused by condensation and low temperature will be reduced, avoiding damage to the wall body from condensation..

Inflated Sporopollenin Exine Capsules Obtained from Thin-Walled Pollen

NASA Astrophysics Data System (ADS)

Park, Jae Hyeon; Seo, Jeongeun; Jackman, Joshua A.; Cho, Nam-Joon

2016-06-01

Sporopollenin is a physically robust and chemically resilient biopolymer that comprises the outermost layer of pollen walls and is the first line of defense against harsh environmental conditions. The unique physicochemical properties of sporopollenin increasingly motivate the extraction of sporopollenin exine capsules (SECs) from pollen walls as a renewable source of organic microcapsules for encapsulation applications. Despite the wide range of different pollen species with varying sizes and wall thicknesses, faithful extraction of pollen-mimetic SECs has been limited to thick-walled pollen capsules with rigid mechanical properties. There is an unmet need to develop methods for producing SECs from thin-walled pollen capsules which constitute a large fraction of all pollen species and have attractive materials properties such as greater aerosol dispersion. Herein, we report the first successful extraction of inflated SEC microcapsules from a thin-walled pollen species (Zea mays), thereby overcoming traditional challenges with mechanical stability and loss of microstructure. Morphological and compositional characterization of the SECs obtained by the newly developed extraction protocol confirms successful protein removal along with preservation of nanoscale architectural features. Looking forward, there is excellent potential to apply similar strategies across a wide range of unexplored thin-walled pollen species.

Space- and time-resolved resistive measurements of liquid metal wall thickness.

PubMed

Mirhoseini, S M H; Volpe, F A

2016-11-01

In a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion. The electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. Here a matrix of electrodes is shown to provide spatially and temporally resolved measurements of liquid metal thickness in the absence of plasma. First a theory is developed for m × n electrodes, and then it is experimentally demonstrated for 3 × 1 electrodes, as the liquid stands still or is agitated by means of a shaker. The experiments were carried out with Galinstan, but are easily extended to lithium or other liquid metals.

Thick SS316 materials TIG welding development activities towards advanced fusion reactor vacuum vessel applications

NASA Astrophysics Data System (ADS)

Kumar, B. Ramesh; Gangradey, R.

2012-11-01

Advanced fusion reactors like ITER and up coming Indian DEMO devices are having challenges in terms of their materials design and fabrication procedures. The operation of these devices is having various loads like structural, thermo-mechanical and neutron irradiation effects on major systems like vacuum vessel, divertor, magnets and blanket modules. The concept of double wall vacuum vessel (VV) is proposed in view of protecting of major reactor subsystems like super conducting magnets, diagnostic systems and other critical components from high energy 14 MeV neutrons generated from fusion plasma produced by D-T reactions. The double walled vacuum vessel is used in combination with pressurized water circulation and some special grade borated steel blocks to shield these high energy neutrons effectively. The fabrication of sub components in VV are mainly used with high thickness SS materials in range of 20 mm- 60 mm of various grades based on the required protocols. The structural components of double wall vacuum vessel uses various parts like shields, ribs, shells and diagnostic vacuum ports. These components are to be developed with various welding techniques like TIG welding, Narrow gap TIG welding, Laser welding, Hybrid TIG laser welding, Electron beam welding based on requirement. In the present paper the samples of 20 mm and 40 mm thick SS 316 materials are developed with TIG welding process and their mechanical properties characterization with Tensile, Bend tests and Impact tests are carried out. In addition Vickers hardness tests and microstructural properties of Base metal, Heat Affected Zone (HAZ) and Weld Zone are done. TIG welding application with high thick SS materials in connection with vacuum vessel requirements and involved criticalities towards welding process are highlighted.

The interaction of moderately strong shock waves with thick perforated walls of low porosity

NASA Technical Reports Server (NTRS)

Grant, D. J.

1972-01-01

A theoretical prediction is given of the flow through thick perforated walls of low porosity resulting from the impingement of a moderately strong traveling shock wave. The model was a flat plate positioned normal to the direction of the flow. Holes bored in the plate parallel to the direction of the flow provided nominal hole length-to-diameter ratios of 10:1 and an axial porosity of 25 percent of the flow channel cross section. The flow field behind the reflected shock wave was assumed to behave as a reservoir producing a quasi-steady duct flow through the model. Rayleigh and Fanno duct flow theoretical computations for each of three possible auxiliary wave patterns that can be associated with the transmitted shock (to satisfy contact surface compatibility) were used to provide bounding solutions as an alternative to the more complex influence coefficients method. Qualitative and quantitative behavior was verified in a 1.5- by 2.0-in. helium shock tube. High speed Schlieren photography, piezoelectric pressure-time histories, and electronic-counter wave speed measurements were used to assess the extent of correlation with the theoretical flow models. Reduced data indicated the adequacy of the bounding theory approach to predict wave phenomena and quantitative response.

Space- and time-resolved resistive measurements of liquid metal wall thickness

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

Mirhoseini, S. M. H.; Volpe, F. A., E-mail: fvolpe@columbia.edu

In a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion. The electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. Here a matrix of electrodes is shown to provide spatially and temporally resolved measurements of liquid metal thickness in the absence of plasma. First a theory is developed for m × n electrodes, and then it is experimentally demonstratedmore » for 3 × 1 electrodes, as the liquid stands still or is agitated by means of a shaker. The experiments were carried out with Galinstan, but are easily extended to lithium or other liquid metals.« less

Computer-aided detection of bladder wall thickening in CT urography (CTU)

NASA Astrophysics Data System (ADS)

Cha, Kenny H.; Hadjiiski, Lubomir M.; Chan, Heang-Ping; Caoili, Elaine M.; Cohan, Richard H.; Weizer, Alon Z.; Gordon, Marshall N.; Samala, Ravi K.

2018-02-01

We are developing a computer-aided detection system for bladder cancer in CT urography (CTU). Bladder wall thickening is a manifestation of bladder cancer and its detection is more challenging than the detection of bladder masses. We first segmented the inner and outer bladder walls using our method that combined deep-learning convolutional neural network with level sets. The non-contrast-enhanced region was separated from the contrast-enhanced region with a maximum-intensity-projection-based method. The non-contrast region was smoothed and gray level threshold was applied to the contrast and non-contrast regions separately to extract the bladder wall and potential lesions. The bladder wall was transformed into a straightened thickness profile, which was analyzed to identify regions of wall thickening candidates. Volume-based features of the wall thickening candidates were analyzed with linear discriminant analysis (LDA) to differentiate bladder wall thickenings from false positives. A data set of 112 patients, 87 with wall thickening and 25 with normal bladders, was collected retrospectively with IRB approval, and split into independent training and test sets. Of the 57 training cases, 44 had bladder wall thickening and 13 were normal. Of the 55 test cases, 43 had wall thickening and 12 were normal. The LDA classifier was trained with the training set and evaluated with the test set. FROC analysis showed that the system achieved sensitivities of 93.2% and 88.4% for the training and test sets, respectively, at 0.5 FPs/case.

Progress Towards an LES Wall Model Including Unresolved Roughness

NASA Astrophysics Data System (ADS)

Craft, Kyle; Redman, Andrew; Aikens, Kurt

2015-11-01

Wall models used in large eddy simulations (LES) are often based on theories for hydraulically smooth walls. While this is reasonable for many applications, there are also many where the impact of surface roughness is important. A previously developed wall model has been used primarily for jet engine aeroacoustics. However, jet simulations have not accurately captured thick initial shear layers found in some experimental data. This may partly be due to nozzle wall roughness used in the experiments to promote turbulent boundary layers. As a result, the wall model is extended to include the effects of unresolved wall roughness through appropriate alterations to the log-law. The methodology is tested for incompressible flat plate boundary layers with different surface roughness. Correct trends are noted for the impact of surface roughness on the velocity profile. However, velocity deficit profiles and the Reynolds stresses do not collapse as well as expected. Possible reasons for the discrepancies as well as future work will be presented. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1053575. Computational resources on TACC Stampede were provided under XSEDE allocation ENG150001.

Measure Guideline. Incorporating Thick Layers of Exterior Rigid Insulation on Walls

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

Lstiburek, Joseph; Baker, Peter

This measure guideline, written by the U.S. Department of Energy’s Building America team Building Science Corporation, provides information about the design and construction of wall assemblies that use layers of rigid exterior insulation thicker than 1-½ in. and that require a secondary cladding attachment location exterior to the insulation. The guideline is separated into several distinct sections that cover: (1) fundamental building science principles relating to the use of exterior insulation on wall assemblies; (2) design principles for tailoring this use to the specific project goals and requirements; and (3) construction detailing to increase understanding about implementing the various designmore » elements.« less

Microstructure of a base metal thick film system. [Glass frit with base metal oxide addition

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

Mentley, D.E.

1976-06-01

A base metal thick film conductor system using glass frits with base metal oxide additions was investigated as metallization for hybrid microcircuits. Application of previous work on wetting and chemical bonding was made to this system. The observation of changes in the properties of the thick film was made by photomicrographs of screened samples and sheet resistivity measurements. In addition to the chemical and wetting properties, the effect of glass frit particle size on conductivity was also analyzed. The base metal oxide addition was found to produce a more consistent thick film conductor at low volume percentages of metal bymore » inhibiting the formation of low melting redox reaction products.« less

Thick strings, the liquid crystal blue phase, and cosmological large-scale structure

NASA Technical Reports Server (NTRS)

Luo, Xiaochun; Schramm, David N.

1992-01-01

A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasi-periodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts. The model appears to work with either cold or hot dark matter.

Dry granular avalanche impact force on a rigid wall of semi-infinite height

NASA Astrophysics Data System (ADS)

Albaba, Adel; Lambert, Stéphane; Faug, Thierry

2017-06-01

The present paper tackles the problem of the impact of a dry granular avalanche-flow on a rigid wall of semi-infinite height. An analytic force model based on depth-averaged shock theory is proposed to describe the flow-wall interaction and the resulting impact force on the wall. Provided that the analytic force model is fed with the incoming flow conditions regarding thickness, velocity and density, all averaged over a certain distance downstream of the undisturbed incoming flow, it reproduces very well the time history of the impact force actually measured by detailed discrete element simulations, for a wide range of slope angles.

Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

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

Gomez-Cardona, Daniel; Nagle, Scott K.; Department of Radiology, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792

Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiationmore » dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low

Inflated Sporopollenin Exine Capsules Obtained from Thin-Walled Pollen

PubMed Central

Park, Jae Hyeon; Seo, Jeongeun; Jackman, Joshua A.; Cho, Nam-Joon

2016-01-01

Sporopollenin is a physically robust and chemically resilient biopolymer that comprises the outermost layer of pollen walls and is the first line of defense against harsh environmental conditions. The unique physicochemical properties of sporopollenin increasingly motivate the extraction of sporopollenin exine capsules (SECs) from pollen walls as a renewable source of organic microcapsules for encapsulation applications. Despite the wide range of different pollen species with varying sizes and wall thicknesses, faithful extraction of pollen-mimetic SECs has been limited to thick-walled pollen capsules with rigid mechanical properties. There is an unmet need to develop methods for producing SECs from thin-walled pollen capsules which constitute a large fraction of all pollen species and have attractive materials properties such as greater aerosol dispersion. Herein, we report the first successful extraction of inflated SEC microcapsules from a thin-walled pollen species (Zea mays), thereby overcoming traditional challenges with mechanical stability and loss of microstructure. Morphological and compositional characterization of the SECs obtained by the newly developed extraction protocol confirms successful protein removal along with preservation of nanoscale architectural features. Looking forward, there is excellent potential to apply similar strategies across a wide range of unexplored thin-walled pollen species. PMID:27302853

Single-Walled Carbon Nanotube Film Supported Nanofiltration Membrane with a Nearly 10 nm Thick Polyamide Selective Layer for High-Flux and High-Rejection Desalination.

PubMed

Zhu, Yuzhang; Xie, Wei; Gao, Shoujian; Zhang, Feng; Zhang, Wenbin; Liu, Zhaoyang; Jin, Jian

2016-09-01

Fabricating nanofiltration (NF) membranes with high permeating flux and simultaneous high rejection rate for desalination is rather significant and highly desired. A new avenue is reported in this work to design NF membrane by using polydopamine wrapped single-walled carbon nanotube (PD/SWCNTs) ultrathin film as support layer instead of the use of traditional polymer-based underlying layers. Thanks to the high porosity, smooth surface, and more importantly optimal hydrophilic surface of PD/SWCNTs film, a defect-free polyamide selective layer for NF membrane with thickness of as thin as 12 nm is achieved. The obtained NF membrane exhibits an extremely high performance with a permeating flux of 32 L m -2 h -1 bar -1 and a rejection rate of 95.9% to divalent ions. This value is two to five times higher than the traditional NF membranes with similar rejection rate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasonographic evaluation of myometrial thickness and prediction of a successful external cephalic version.

PubMed

Buhimschi, Catalin S; Buhimschi, Irina A; Wehrum, Mark J; Molaskey-Jones, Sherry; Sfakianaki, Anna K; Pettker, Christian M; Thung, Stephen; Campbell, Katherine H; Dulay, Antonette T; Funai, Edmund F; Bahtiyar, Mert O

2011-10-01

To test the hypothesis that myometrial thickness predicts the success of external cephalic version. Abdominal ultrasonographic scans were performed in 114 consecutive pregnant women with breech singletons before an external cephalic version maneuver. Myometrial thickness was measured by a standardized protocol at three sites: the lower segment, midanterior wall, and the fundal uterine wall. Independent variables analyzed in conjunction with myometrial thickness were: maternal age, parity, body mass index, abdominal wall thickness, estimated fetal weight, amniotic fluid index, placental thickness and location, fetal spine position, breech type, and delivery outcomes such as final mode of delivery and birth weight. Successful version was associated with a thicker ultrasonographic fundal myometrium (unsuccessful: 6.7 [5.5-8.4] compared with successful: 7.4 [6.6-9.7] mm, P=.037). Multivariate regression analysis showed that increased fundal myometrial thickness, high amniotic fluid index, and nonfrank breech presentation were the strongest independent predictors of external cephalic version success (P<.001). A fundal myometrial thickness greater than 6.75 mm and an amniotic fluid index greater than 12 cm were each associated with successful external cephalic versions (fundal myometrial thickness: odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1-5.2, P=.029; amniotic fluid index: OR 2.8, 95% CI 1.3-6.0, P=.008). Combining the two variables resulted in an absolute risk reduction for a failed version of 27.6% (95% CI 7.1-48.1) and a number needed to treat of four (95% CI 2.1-14.2). Fundal myometrial thickness and amniotic fluid index contribute to success of external cephalic version and their evaluation can be easily incorporated in algorithms before the procedure. III.

Serum Carotenoids Reduce Progression of Early Atherosclerosis in the Carotid Artery Wall among Eastern Finnish Men

PubMed Central

Karppi, Jouni; Kurl, Sudhir; Ronkainen, Kimmo; Kauhanen, Jussi; Laukkanen, Jari A.

2013-01-01

Background Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. Methods We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between concentrations of serum carotenoids, and intima-media thickness of the common carotid artery wall was explored in 840 middle-aged men (aged 46–65 years) from Eastern Finland. Ultrasonography of the common carotid arteries were performed at baseline and 7-year follow-up. Serum levels of carotenoids were analyzed at baseline. Changes in mean and maximum intima media thickness of carotid artery wall were related to baseline serum carotenoid levels in covariance analyses adjusted for covariates. Results In a covariance analysis with adjustment for age, ultrasound sonographer, maximum intima media thickness, examination year, body mass index, systolic blood pressure, smoking, physical activity, serum LDL cholesterol, family history of coronary heart disease, antihypertensive medication and serum high sensitivity C-reactive protein, 7-year change in maximum intima media thickness was inversely associated with lycopene (p = 0.005), α-carotene (p = 0.002) and β-carotene (p = 0.019), respectively. Conclusions The present study shows that high serum concentrations of carotenoids may be protective against early atherosclerosis. PMID:23700460

Nonlinear analysis of composite thin-walled helicopter blades

NASA Astrophysics Data System (ADS)

Kalfon, J. P.; Rand, O.

Nonlinear theoretical modeling of laminated thin-walled composite helicopter rotor blades is presented. The derivation is based on nonlinear geometry with a detailed treatment of the body loads in the axial direction which are induced by the rotation. While the in-plane warping is neglected, a three-dimensional generic out-of-plane warping distribution is included. The formulation may also handle varying thicknesses and mass distribution along the cross-sectional walls. The problem is solved by successive iterations in which a system of equations is constructed and solved for each cross-section. In this method, the differential equations in the spanwise directions are formulated and solved using a finite-differences scheme which allows simple adaptation of the spanwise discretization mesh during iterations.

Right ventricular relative wall thickness as a predictor of outcomes and of right ventricular reverse remodeling for patients with pulmonary hypertension.

PubMed

Sano, Hiroyuki; Tanaka, Hidekazu; Motoji, Yoshiki; Fukuda, Yuko; Mochizuki, Yasuhide; Hatani, Yutaka; Matsuzoe, Hiroki; Hatazawa, Keiko; Shimoura, Hiroyuki; Ooka, Junichi; Ryo-Koriyama, Keiko; Nakayama, Kazuhiko; Matsumoto, Kensuke; Emoto, Noriaki; Hirata, Ken-Ichi

2017-03-01

Mid-term right ventricular (RV) reverse remodeling after treatment in patients with pulmonary hypertension (PH) is associated with long-term outcome as well as baseline RV remodeling. However, baseline factors influencing mid-term RV reverse remodeling after treatment and its prognostic capability remain unclear. We studied 54 PH patients. Mid-term RV remodeling was assessed in terms of the RV area, which was traced planimetrically at the end-systole (RVESA). RV reverse remodeling was defined as a relative decrease in the RVESA of at least 15% at 10.2 ± 9.4 months after treatment. Long-term follow-up was 5 years. Adverse events occurred in ten patients (19%) and mid-term RV reverse remodeling after treatment was observed in 37 (69%). Patients with mid-term RV reverse remodeling had more favorable long-term outcomes than those without (log-rank: p = 0.01). Multivariate logistic regression analysis showed that RV relative wall thickness (RV-RWT), as calculated as RV free-wall thickness/RV basal linear dimension at end-diastole, was an independent predictor of mid-term RV reverse remodeling (OR 1.334; 95% CI, 1.039-1.713; p = 0.03). Moreover, patients with RV-RWT ≥0.21 showed better long-term outcomes than did those without (log-rank p = 0.03), while those with RV-RWT ≥0.21 and mid-term RV reverse remodeling had the best long-term outcomes. Patients with RV-RWT <0.21 and without mid-term RV reverse remodeling, on the other hand, had worse long-term outcomes than other sub-groups. In conclusions, RV-RWT could predict mid-term RV reverse remodeling after treatment in PH patients, and was associated with long-term outcomes. Our finding may have clinical implications for better management of PH patients.

COMPARISON STUDY OF VARIOUS PLASTICS AS THE WALL MATERIAL OF THGEM-BASED MICRODOSEMETERS FOR FAST NEUTRON MEASUREMENTS.

PubMed

Moslehi, A; Raisali, G; Lamehi, M

2017-04-15

To find appropriate substitutions for the expensive plastics of A-150 and rexolite used in the construction of thick gas electron multiplier (THGEM)-based tissue-equivalent proportional counters, in the present work, the responses of a THGEM-based microdosimetric detector made of A-150 and rexolite and three others composed of plexiglas (PMMA), polyethylene and polystyrene plastics as the wall materials have been compared. Lineal energy distribution, frequency-averaged lineal energy, dose-averaged lineal energy, mean quality factor and dose-equivalent for 0.1, 1 and 10 MeV neutrons and also for 241Am-Be neutrons are calculated using Geant4 simulation toolkit. Frequency-averaged lineal energy, dose-averaged lineal energy, mean quality factor and dose-equivalent values for all plastics are found similar. In addition, the response of an indigenously constructed microdosemeter with PMMA walls is also measured for 241Am-Be neutrons. The experimental results are in good agreement with the simulation predictions. Conclusively, it was found that the three considered plastics can be used as good candidates instead of A-150 and rexolite plastics in fast neutron microdosimetry. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Intracranial Vascular Disease Evaluation With Combined Vessel Wall Imaging And Patient Specific Hemodynamics

NASA Astrophysics Data System (ADS)

Samson, Kurt; Mossa-Basha, Mahmud; Yuan, Chun; Canton, Maria De Gador; Aliseda, Alberto

2017-11-01

Intracranial vascular pathologies are evaluated with angiography, conventional digital subtraction angiography or non-invasive (MRI, CT). Current techniques present limitations on the resolution with which the vessel wall characteristics can be measured, presenting a major challenge to differential diagnostic of cerebral vasculopathies. A new combined approach is presented that incorporates patient-specific image-based CFD models with intracranial vessel-wall MRI (VWMRI). Comparisons of the VWMRI measurements, evaluated for the presence of wall enhancement and thin-walled regions, against CFD metrics such as wall shear stress (WSS), and oscillatory shear index (OSI) are used to understand how the new imaging technique developed can predict the influence of hemodynamics on the deterioration of the aneurysmal wall, leading to rupture. Additionally, histology of each resected aneurysm, evaluated for inflammatory infiltration and wall thickness features, is used to validate the analysis from VWMRI and CFD. This data presents a solid foundation on which to build a new framework for combined VWMRI-CFD to predict unstable wall changes in unruptured intracranial aneurysms, and support clinical monitoring and intervention decisions.

Development of a Versatile Laser-Ultrasonic System and Application to the Online Measurement for Process Control of Wall Thickness and Eccentricity of Seamless Tubes

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

Robert V. Kolarik II

2002-10-23

A system for the online, non-contact measurement of wall thickness in steel seamless mechanical tubing has been developed and demonstrated at a tubing production line at the Timken Company in Canton, Ohio. The system utilizes laser-generation of ultrasound and laser-detection of time of flight with interferometry, laser-doppler velocimetry and pyrometry, all with fiber coupling. Accuracy (<1% error) and precision (1.5%) are at targeted levels. Cost and energy savings have exceeded estimates. The system has shown good reliability in measuring over 200,000 tubes in its first six months of deployment.

Computer vision based nacre thickness measurement of Tahitian pearls

NASA Astrophysics Data System (ADS)

Loesdau, Martin; Chabrier, Sébastien; Gabillon, Alban

2017-03-01

The Tahitian Pearl is the most valuable export product of French Polynesia contributing with over 61 million Euros to more than 50% of the total export income. To maintain its excellent reputation on the international market, an obligatory quality control for every pearl deemed for exportation has been established by the local government. One of the controlled quality parameters is the pearls nacre thickness. The evaluation is currently done manually by experts that are visually analyzing X-ray images of the pearls. In this article, a computer vision based approach to automate this procedure is presented. Even though computer vision based approaches for pearl nacre thickness measurement exist in the literature, the very specific features of the Tahitian pearl, namely the large shape variety and the occurrence of cavities, have so far not been considered. The presented work closes the. Our method consists of segmenting the pearl from X-ray images with a model-based approach, segmenting the pearls nucleus with an own developed heuristic circle detection and segmenting possible cavities with region growing. Out of the obtained boundaries, the 2-dimensional nacre thickness profile can be calculated. A certainty measurement to consider imaging and segmentation imprecisions is included in the procedure. The proposed algorithms are tested on 298 manually evaluated Tahitian pearls, showing that it is generally possible to automatically evaluate the nacre thickness of Tahitian pearls with computer vision. Furthermore the results show that the automatic measurement is more precise and faster than the manual one.

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

DOE PAGES

Duan, R.; Jalowicka, Aleksandra; Unocic, Kinga A.; ...

2016-10-18

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up tomore » 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.« less

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

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

Duan, R.; Jalowicka, Aleksandra; Unocic, Kinga A.

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up tomore » 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.« less

Controlled Patterning and Growth of Single Wall and Multi-wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delzeit, Lance D. (Inventor)

2005-01-01

Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH4 or C2Hn with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

PubMed

Han, Zhao Jun; Ostrikov, Kostya

2012-04-04

Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

Double wall vacuum tubing and method of manufacture

DOEpatents

Stahl, Charles R.; Gibson, Michael A.; Knudsen, Christian W.

1989-01-01

An evacuated double wall tubing is shown together with a method for the manufacture of such tubing which includes providing a first pipe of predetermined larger diameter and a second pipe having an O.D. substantially smaller than the I.D. of the first pipe. An evacuation opening is then in the first pipe. The second pipe is inserted inside the first pipe with an annular space therebetween. The pipes are welded together at one end. A stretching tool is secured to the other end of the second pipe after welding. The second pipe is then prestressed mechanically with the stretching tool an amount sufficient to prevent substantial buckling of the second pipe under normal operating conditions of the double wall pipe. The other ends of the first pipe and the prestressed second pipe are welded together, preferably by explosion welding, without the introduction of mechanical spacers between the pipes. The annulus between the pipes is evacuated through the evacuation opening, and the evacuation opening is finally sealed. The first pipe is preferably of steel and the second pipe is preferably of titanium. The pipes may be of a size and wall thickness sufficient for the double wall pipe to be structurally load bearing or may be of a size and wall thickness insufficient for the double wall pipe to be structurally load bearing, and the double wall pipe positioned with a sliding fit inside a third pipe of a load-bearing size.

Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance

PubMed Central

Ene, Iuliana V.; Walker, Louise A.; Schiavone, Marion; Lee, Keunsook K.; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A. R.; Munro, Carol A.

2015-01-01

ABSTRACT The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. PMID:26220968

Noninvasive detection of coronary artery wall thickening with age in healthy subjects using high resolution MRI with beat-to-beat respiratory motion correction.

PubMed

Scott, Andrew D; Keegan, Jennifer; Mohiaddin, Raad H; Firmin, David N

2011-10-01

To demonstrate coronary artery wall thickening with age in a small healthy cohort using a highly efficient, reliable, and reproducible high-resolution MR technique. A 3D cross-sectional MR vessel wall images (0.7 × 0.7 × 3 mm resolution) with retrospective beat-to-beat respiratory motion correction (B2B-RMC) were obtained in the proximal right coronary artery of 21 healthy subjects (age, 22-62 years) with no known cardiovascular disease. Lumen and outer wall (lumen + vessel wall) areas were measured in one central slice from each subject and average wall thickness and wall area/outer wall area ratio (W/OW) calculated. Imaging was successful in 18 (86%) subjects with average respiratory efficiency 99.3 ± 1.7%. Coronary vessel wall thickness and W/OW significantly correlate with subject age, increasing by 0.088 mm and 0.031 per decade respectively (R = 0.53, P = 0.024 and R = 0.48, P = 0.046). No relationship was found between lumen area and vessel wall thickness (P = NS), but outer wall area increased significantly with vessel wall thickness at 19 mm(2) per mm (P = 0.046). This is consistent with outward vessel wall remodeling. Despite the small size of our healthy cohort, using high-resolution MR imaging and B2B-RMC, we have demonstrated increasing coronary vessel wall thickness and W/OW with age. The results obtained are consistent with outward vessel wall remodeling. Copyright © 2011 Wiley-Liss, Inc.

High-frequency guided ultrasonic waves to monitor corrosion thickness loss

NASA Astrophysics Data System (ADS)

Fromme, Paul; Bernhard, Fabian; Masserey, Bernard

2017-02-01

Corrosion due to adverse environmental conditions can occur for a range of industrial structures, e.g., ships and offshore oil platforms. Pitting corrosion and generalized corrosion can lead to the reduction of the strength and thus degradation of the structural integrity. The nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high frequency guided ultrasonic waves propagating along the structure. Using standard ultrasonic transducers with single sided access to the structure, the two fundamental Lamb wave modes were selectively generated simultaneously, penetrating through the complete thickness of the structure. The wave propagation and interference of the guided wave modes depends on the thickness of the structure. Numerical simulations were performed using a 2D Finite Difference Method (FDM) algorithm in order to visualize the guided wave propagation and energy transfer across the plate thickness. Laboratory experiments were conducted and the wall thickness reduced initially uniformly by milling of the steel structure. Further measurements were conducted using accelerated corrosion in salt water. From the measured signal change due to the wave mode interference, the wall thickness reduction was monitored and good agreement with theoretical predictions was achieved. Corrosion can lead to non-uniform thickness reduction and the influence of this on the propagation of the high frequency guided ultrasonic waves was investigated. The wave propagation in a steel specimen with varying thickness was measured experimentally and the influence on the wave propagation characteristics quantified.

Plant cell wall sugars: sweeteners for a bio-based economy.

PubMed

Van de Wouwer, Dorien; Boerjan, Wout; Vanholme, Bartel

2018-02-12

Global warming and the consequent climate change is one of the major environmental challenges we are facing today. The driving force behind the rise in temperature is our fossil-based economy, which releases massive amounts of the greenhouse gas carbon dioxide into the atmosphere. In order to reduce greenhouse gas emission, we need to scale down our dependency on fossil resources, implying that we need other sources for energy and chemicals to feed our economy. Here, plants have an important role to play; by means of photosynthesis, plants capture solar energy to split water and fix carbon derived from atmospheric carbon dioxide. A significant fraction of the fixed carbon ends up as polysaccharides in the plant cell wall. Fermentable sugars derived from cell wall polysaccharides form an ideal carbon source for the production of bio-platform molecules. However, a major limiting factor in the use of plant biomass as feedstock for the bio-based economy is the complexity of the plant cell wall and its recalcitrance towards deconstruction. To facilitate the release of fermentable sugars during downstream biomass processing, the composition and structure of the cell wall can be engineered. Different strategies to reduce cell wall recalcitrance will be described in this review. The ultimate goal is to obtain a tailor-made biomass, derived from plants with a cell wall optimized for particular industrial or agricultural applications, without affecting plant growth and development. This article is protected by copyright. All rights reserved.

Non-exposed endoscopic wall-inversion surgery for gastrointestinal stromal tumor

PubMed Central

Mitsui, Takashi; Aikou, Susumu; Niimi, Keiko; Fujishiro, Mitsuhiro; Seto, Yasuyuki

2018-01-01

Laparoscopic and endoscopic cooperative surgery (LECS) is an accepted method of laparoscopic wedge resection, which is minimally invasive, for gastrointestinal stromal tumors (GISTs). We established a type of LECS achieving a full-thickness resection, non-exposed endoscopic wall-inversion surgery (NEWS), in an effort to prevent exposure of the peritoneal cavity to gastric intraluminal contents. We employed this surgical technique in 28 gastric GIST patients. We failed to complete NEWS in the initial two patients and in one patient with a large tumor (40 mm × 35 mm), but otherwise carried out the procedure successfully. Although a learning effect is speculated to occur, based on a decreasing trend in the operation time, the median operation time was 184 minutes showing that NEWS is still a time-consuming method. No significant differences were recognized in tumor size or location, except near the esophagogastric junction (EGJ), nor in the cross-sectional circumference. NEWS is feasible and appears to be a good option, especially for small GISTs with mucosal ulceration rendering full-thickness enucleation by opening of the gastric wall unfeasible. PMID:29682624

3D cardiac wall thickening assessment for acute myocardial infarction

NASA Astrophysics Data System (ADS)

Khalid, A.; Chan, B. T.; Lim, E.; Liew, Y. M.

2017-06-01

Acute myocardial infarction (AMI) is the most severe form of coronary artery disease leading to localized myocardial injury and therefore irregularities in the cardiac wall contractility. Studies have found very limited differences in global indices (such as ejection fraction, myocardial mass and volume) between healthy subjects and AMI patients, and therefore suggested regional assessment. Regional index, specifically cardiac wall thickness (WT) and thickening is closely related to cardiac function and could reveal regional abnormality due to AMI. In this study, we developed a 3D wall thickening assessment method to identify regional wall contractility dysfunction due to localized myocardial injury from infarction. Wall thickness and thickening were assessed from 3D personalized cardiac models reconstructed from cine MRI images by fitting inscribed sphere between endocardial and epicardial wall. The thickening analysis was performed in 5 patients and 3 healthy subjects and the results were compared against the gold standard 2D late-gadolinium-enhanced (LGE) images for infarct localization. The notable finding of this study is the highly accurate estimation and visual representation of the infarct size and location in 3D. This study provides clinicians with an intuitive way to visually and qualitatively assess regional cardiac wall dysfunction due to infarction in AMI patients.

Three-dimensional ultrasound measurements of carotid vessel wall and plaque thickness and their relationship with pulmonary abnormalities in ex-smokers without airflow limitation.

PubMed

Cheng, Jieyu; Pike, Damien; Chow, Tommy W S; Kirby, Miranda; Parraga, Grace; Chiu, Bernard

2016-09-01

The relationship between carotid disease and modestly abnormal airflow in ex-smokers without chronic obstructive pulmonary disease (COPD) is not well-understood. We generated 3D ultrasound measurements of carotid vessel-wall-plus-plaque thickness (VWT) and vessel wall volume (VWV) to quantify and evaluate such carotid ultrasound measurements in ex- and never-smokers without airflow limitation. These patients did not fulfill the diagnostic criteria for COPD. We also investigated the relationship of carotid atherosclerosis with pulmonary phenotypes of COPD. We evaluated 61 subjects without a clinical diagnosis of pulmonary or vascular diseases including 34 never-smokers (72 ± 6 year) and 27 ex-smokers (73 ± 9 year). We measured mean VWT ([Formula: see text]) and mean VWT specific to carotid regions-of-interest ([Formula: see text]) and evaluated potential differences between ex- and never-smokers. Carotid ultrasound and pulmonary disease measurement relationships were also evaluated using correlation coefficients (r) and multivariate regression analyses. Ex-smokers had a significantly greater [Formula: see text] (p = 0.003) and [Formula: see text] (p < 0.00001) than never-smokers, whereas a significant difference between the two groups was not detected by VWV (p = 1.0). There were significant correlations between the ventilation defect percent (VDP) measured by MRI with [Formula: see text] (r = 0.42, p = 0.001) and [Formula: see text] (r = 0.56, p = 0.00001). Multivariate regression models showed that VDP significantly predicted [Formula: see text] (β = 0.38, p = 0.004) and [Formula: see text] (β = 0.50, p = 0.00001). VWT-based measurements detected differences in vessel-wall-plus-plaque burden in ex- and never-smokers, which were not revealed using VWV. There were significant correlations between cardiovascular and pulmonary disease biomarkers in these ex-smokers who did not have a clinical diagnosis of

The Relationship of Educational Attainment with Pulmonary Emphysema and Airway Wall Thickness.

PubMed

Gjerdevik, Miriam; Grydeland, Thomas B; Washko, George R; Coxson, Harvey O; Silverman, Edwin K; Gulsvik, Amund; Bakke, Per S

2015-06-01

Low educational attainment is a risk factor of chronic obstructive pulmonary disease (COPD). There is limited knowledge on the relationship between educational level and computed tomography measures of emphysema and airway wall thickness (AWT). We hypothesized that low educational attainment is associated with increased emphysema and AWT in ever-smokers with and without COPD. We included 462 and 485 ever-smokers with and without COPD in a cross-sectional study, aged 40-86 years. The sample was divided into groups reflecting educational attainment: primary, secondary, and university. We performed linear regression to examine associations between educational attainment and both emphysema and AWT separately for those with and without COPD. We adjusted for sex, age, smoking status, age of onset of smoking, pack-years, height, and body mass index. Compared with university education, in subjects with COPD, primary education was associated with a 68.1% (95% confidence interval = 14.2-147.6%; P = 0.01) relative increase in emphysema and secondary education was associated with a 50.6% (95% confidence interval = 5.7-114.6%; P = 0.02) relative increase. There was a nonsignificant trend toward an association between lower educational attainment and increased emphysema among those without COPD (P = 0.18), yet greater age appeared to modify this association (P = 0.01). We did not detect significant linear relationships between educational attainment and AWT in subjects with or without COPD. Lower educational attainment was associated with increased emphysema among adults with COPD. Among those without COPD, this association was more pronounced with increasing age. No significant linear relationship between educational attainment and AWT was found. Clinicians treating adults with emphysema should keep in mind that factors related to low education beyond that of smoking and occupational dust exposure might be of importance to the disease.

Measurement of retinal wall-to-lumen ratio by adaptive optics retinal camera: a clinical research.

PubMed

Meixner, Eva; Michelson, Georg

2015-11-01

To measure the wall-to-lumen ratio (WLR) and the cross-sectional area of the vascular wall (WCSA) of retinal arterioles by an Adaptive Optics (AO) retinal camera. Forty-seven human subjects were examined and their medical history was explored. WLR and WCSA were measured on the basis of retinal arteriolar wall thickness (VW), lumen diameter (LD) and vessel diameter (VD) assessed by rtx1 Adaptive Optics retinal camera. WLR was calculated by the formula [Formula: see text]. Arterio-venous ratio (AVR) and microvascular abnormalities were attained by quantitative and qualitative assessment of fundus photographs. Influence of age, arterial hypertension, body mass index (BMI) and retinal microvascular abnormalities on the WLR was examined. An age-adjusted WLR was created to test influences on WLR independently of age. Considering WLR and WCSA, a distinction between eutrophic and hypertrophic retinal remodeling processes was possible. The intra-observer variability (IOV) was 6 % ± 0.9 for arteriolar wall thickness and 2 % ± 0.2 for arteriolar wall thickness plus vessel lumen. WLR depended significantly on the wall thickness (r = 0.715; p < 0.01) of retinal arterioles, but was independent of the total vessel diameter (r = 0.052; p = 0.728). WLR correlated significantly with age (r = 0.769; p < 0.01). Arterial hypertension and a higher BMI were significantly associated with an increased age-adjusted WLR. WLR correlated significantly with the stage of microvascular abnormalities. 55 % of the hypertensive subjects and 11 % of the normotensive subjects showed eutrophic remodeling, while hypertrophic remodeling was not detectable. WLR correlated inversely with AVR. AVR was independent of the arteriolar wall thickness, age and arterial hypertension. The technique of AO retinal imaging allows a direct measurement of the retinal vessel wall and lumen diameter with good intra-observer variability. Age, arterial hypertension and an elevated BMI level

Differential assembly of alpha- and gamma-filagenins into thick filaments in Caenorhabditis elegans

NASA Technical Reports Server (NTRS)

Liu, F.; Ortiz, I.; Hutagalung, A.; Bauer, C. C.; Cook, R. G.; Epstein, H. F.

2000-01-01

Muscle thick filaments are highly organized supramolecular assemblies of myosin and associated proteins with lengths, diameters and flexural rigidities characteristic of their source. The cores of body wall muscle thick filaments of the nematode Caenorhabditis elegans are tubular structures of paramyosin sub-filaments coupled by filagenins and have been proposed to serve as templates for the assembly of native thick filaments. We have characterized alpha- and gamma-filagenins, two novel proteins of the cores with calculated molecular masses of 30,043 and 19,601 and isoelectric points of 10.52 and 11.49, respectively. Western blot and immunoelectron microscopy using affinity-purified antibodies confirmed that the two proteins are core components. Immunoelectron microscopy of the cores revealed that they assemble with different periodicities. Immunofluorescence microscopy showed that alpha-filagenin is localized in the medial regions of the A-bands of body wall muscle cells whereas gamma-filagenin is localized in the flanking regions, and that alpha-filagenin is expressed in 1.5-twofold embryos while gamma-filagenin becomes detectable only in late vermiform embryos. The expression of both proteins continues throughout later stages of development. C. elegans body wall muscle thick filaments of these developmental stages have distinct lengths. Our results suggest that the differential assembly of alpha- and gamma-filagenins into thick filaments of distinct lengths may be developmentally regulated.

Wall Boundary Layer Measurements for the NASA Langley Transonic Dynamics Tunnel

NASA Technical Reports Server (NTRS)

Wieseman, Carol D.; Bennett, Robert M.

2007-01-01

Measurements of the boundary layer parameters in the NASA Langley Transonic Dynamics tunnel were conducted during extensive calibration activities following the facility conversion from a Freon-12 heavy-gas test medium to R-134a. Boundary-layer rakes were mounted on the wind-tunnel walls, ceiling, and floor. Measurements were made over the range of tunnel operation envelope in both heavy gas and air and without a model in the test section at three tunnel stations. Configuration variables included open and closed east sidewall wall slots, for air and R134a test media, reentry flap settings, and stagnation pressures over the full range of tunnel operation. The boundary layer thickness varied considerably for the six rakes. The thickness for the east wall was considerably larger that the other rakes and was also larger than previously reported. There generally was some reduction in thickness at supersonic Mach numbers, but the effect of stagnation pressure, and test medium were not extensive.

Comparison of Current and Field Driven Domain Wall Motion in Beaded Permalloy Nanowires

NASA Astrophysics Data System (ADS)

Lage, Enno; Dutta, Sumit; Ross, Caroline A.

2015-03-01

Domain wall based devices are promising candidates for non-volatile memory devices with no static power consumption. A common approach is the use of (field assisted) current driven domain wall motion in magnetic nanowires. In such systems local variations in linewidth act as obstacles for propagating domain walls. In this study we compare simulated field driven and current driven domain wall motion in permalloy nanowires with anti-notches. The simulations were obtained using the Object Oriented MicroMagnetics Framework (OOMMF). The wires with a constant thickness of 8 nm exhibit linewidths ranging from 40 nm to 300 nm. Circular shaped anti-notches extend the linewidth locally by 10% to 30% and raise information about the domain wall propagation in such beaded nanowires. The results are interpreted in terms of the observed propagation behavior and summarized in maps indicating ranges of different ability to overcome the pinning caused by anti-notches of different sizes. Furthermore, regimes of favored domain wall type (transverse walls or vortex walls) and complex propagation effects like walker breakdown behavior or dynamic change between domain wall structures are identified The authors thank the German Academic Exchange Service (DAAD) for funding.

Application Of Moldex3D For Thin-wall Injection Moulding Simulation

NASA Astrophysics Data System (ADS)

Šercer, Mladen; Godec, Damir; Bujanić, Božo

2007-05-01

The benefits associated with decreasing wall thicknesses below their current values are still measurable and desired even if the final wall thickness is nowhere near those of the aggressive portable electronics industry. It is important to note that gains in wall section reduction do not always occur without investment, in this case, in tooling and machinery upgrades. Equally important is the fact that productivity and performance benefits of reduced material usage, fast cycle times, and lighter weight can often outweigh most of the added costs. In order to eliminate unnecessary mould trials, minimize product development cycle, reduce overall costs and improve product quality, polymeric engineers use new CAE technology (Computer Aided Engineering). This technology is a simulation tool, which combines proven theories, material properties and process conditions to generate realistic simulations and produce valuable recommendations. Based on these recommendations, an optional combination of product design, material and process conditions can be identified. In this work, Moldex3D software was used for simulation of injection moulding in order to avoid potential moulding problems. The results gained from the simulation were used for the optimization of an existing product design, for mould development and for optimization of processing parameters, e.g. injection pressure, mould cavity temperature, etc.

The rotation of cellulose synthase trajectories is microtubule dependent and influences the texture of epidermal cell walls in Arabidopsis hypocotyls.

PubMed

Chan, Jordi; Crowell, Elizabeth; Eder, Magdalena; Calder, Grant; Bunnewell, Susan; Findlay, Kim; Vernhettes, Samantha; Höfte, Herman; Lloyd, Clive

2010-10-15

Plant shoots have thick, polylamellate outer epidermal walls based on crossed layers of cellulose microfibrils, but the involvement of microtubules in such wall lamellation is unclear. Recently, using a long-term movie system in which Arabidopsis seedlings were grown in a biochamber, the tracks along which cortical microtubules move were shown to undergo slow rotary movements over the outer surface of hypocotyl epidermal cells. Because microtubules are known to guide cellulose synthases over the short term, we hypothesised that this previously unsuspected microtubule rotation could, over the longer term, help explain the cross-ply structure of the outer epidermal wall. Here, we test that hypothesis using Arabidopsis plants expressing the cellulose synthase GFP-CESA3 and show that cellulose synthase trajectories do rotate over several hours. Neither microtubule-stabilising taxol nor microtubule-depolymerising oryzalin affected the linear rate of GFP-CESA3 movement, but both stopped the rotation of cellulose synthase tracks. Transmission electron microscopy revealed that drug-induced suppression of rotation alters the lamellation pattern, resulting in a thick monotonous wall layer. We conclude that microtubule rotation, rather than any hypothetical mechanism for wall self-assembly, has an essential role in developing cross-ply wall texture.

Spin wave based parallel logic operations for binary data coded with domain walls

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

Urazuka, Y.; Oyabu, S.; Chen, H.

2014-05-07

We numerically investigate the feasibility of spin wave (SW) based parallel logic operations, where the phase of SW packet (SWP) is exploited as a state variable and the phase shift caused by the interaction with domain wall (DW) is utilized as a logic inversion functionality. A designed functional element consists of parallel ferromagnetic nanowires (6 nm-thick, 36 nm-width, 5120 nm-length, and 200 nm separation) with the perpendicular magnetization and sub-μm scale overlaid conductors. The logic outputs for binary data, coded with the existence (“1”) or absence (“0”) of the DW, are inductively read out from interferometric aspect of the superposed SWPs, one of themmore » propagating through the stored data area. A practical exclusive-or operation, based on 2π periodicity in the phase logic, is demonstrated for the individual nanowire with an order of different output voltage V{sub out}, depending on the logic output for the stored data. The inductive output from the two nanowires exhibits well defined three different signal levels, corresponding to the information distance (Hamming distance) between 2-bit data stored in the multiple nanowires.« less

Electron Microscopy of Staphylococcus aureus Cell Wall Lysis

PubMed Central

Virgilio, R.; González, C.; Muñoz, Nubia; Mendoza, Silvia

1966-01-01

Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018–2024. 1966.—A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents. Images PMID:5939482

Electron microscopy of Staphylococcus aureus cell wall lysis.

PubMed

Virgilio, R; González, C; Muñoz, N; Mendoza, S

1966-05-01

Virgilio, Rafael (Escuela de Química y Farmacia, Universidad de Chile, Santiago, Chile), C. González, Nubia Muñoz, and Silvia Mendoza. Electron microscopy of Staphylococcus aureus cell wall lysis. J. Bacteriol. 91:2018-2024. 1966.-A crude suspension of Staphylococcus aureus cell walls (strain Cowan III) in buffer solution was shown by electron microscopy to lyse slightly after 16 hr, probably owing to the action of autolysin. The lysis was considerably faster and more intense after the addition of lysozyme. A remarkable reduction in thickness and rigidity of the cell walls, together with the appearance of many irregular protrusions in their outlines, was observed after 2 hr; after 16 hr, there remained only a few recognizable cell wall fragments but many residual particulate remnants. When autolysin was previously inactivated by trypsin, there was a complete inhibition of the lytic action of lysozyme; on the other hand, when autolysin was inactivated by heat and lysozyme was added, a distinct decrease in the thickness of the cell walls was observed, but there was no destruction of the walls. The lytic action of lysozyme, after treatment with hot 5% trichloroacetic acid, gave rise to a marked dissolution of the structure of the cell walls, which became lost against the background, without, however, showing ostensible alteration of wall outlines. From a morphological point of view, the lytic action of autolysin plus lysozyme was quite different from that of trichloroacetic acid plus lysozyme, as shown by electron micrographs, but in both cases it was very intense. This would suggest different mechanisms of action for these agents.

A new fractional order derivative based active contour model for colon wall segmentation

NASA Astrophysics Data System (ADS)

Chen, Bo; Li, Lihong C.; Wang, Huafeng; Wei, Xinzhou; Huang, Shan; Chen, Wensheng; Liang, Zhengrong

2018-02-01

Segmentation of colon wall plays an important role in advancing computed tomographic colonography (CTC) toward a screening modality. Due to the low contrast of CT attenuation around colon wall, accurate segmentation of the boundary of both inner and outer wall is very challenging. In this paper, based on the geodesic active contour model, we develop a new model for colon wall segmentation. First, tagged materials in CTC images were automatically removed via a partial volume (PV) based electronic colon cleansing (ECC) strategy. We then present a new fractional order derivative based active contour model to segment the volumetric colon wall from the cleansed CTC images. In this model, the regionbased Chan-Vese model is incorporated as an energy term to the whole model so that not only edge/gradient information but also region/volume information is taken into account in the segmentation process. Furthermore, a fractional order differentiation derivative energy term is also developed in the new model to preserve the low frequency information and improve the noise immunity of the new segmentation model. The proposed colon wall segmentation approach was validated on 16 patient CTC scans. Experimental results indicate that the present scheme is very promising towards automatically segmenting colon wall, thus facilitating computer aided detection of initial colonic polyp candidates via CTC.

Molecular imprinting at walls of silica nanotubes for TNT recognition.

PubMed

Xie, Chenggen; Liu, Bianhua; Wang, Zhenyang; Gao, Daming; Guan, Guijian; Zhang, Zhongping

2008-01-15

This paper reports the molecular imprinting at the walls of highly uniform silica nanotubes for the recognition of 2,4,6-trinitrotoluene (TNT). It has been demonstrated that TNT templates were efficiently imprinted into the matrix of silica through the strong acid-base pairing interaction between TNT and 3-aminopropyltriethoxysilane (APTS). TNT-imprinted silica nanotubes were synthesized by the gelation reaction between APTS and tetraethylorthosilicate (TEOS), selectively occurring at the porous walls of APTS-modified alumina membranes. The removal of the original TNT templates leaves the imprinted cavities with covalently anchored amine groups at the cavity walls. A high density of recognition sites with molecular selectivity to the TNT analyte was created at the wall of silica nanotubes. Furthermore, most of these recognition sites are situated at the inside and outside surfaces of tubular walls and in the proximity of the two surfaces due to the ultrathin wall thickness of only 15 nm, providing a better site accessibility and lower mass-transfer resistance. Therefore, greater capacity and faster kinetics of uptaking target species were achieved. The silica nanotube reported herein is an ideal form of material for imprinting various organic or biological molecules toward applications in chemical/biological sensors and bioassay.

Investigation into the influence of laser energy input on selective laser melted thin-walled parts by response surface method

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Jian; Pang, Zhicong; Wu, Weihui

2018-04-01

Selective laser melting (SLM) provides a feasible way for manufacturing of complex thin-walled parts directly, however, the energy input during SLM process, namely derived from the laser power, scanning speed, layer thickness and scanning space, etc. has great influence on the thin wall's qualities. The aim of this work is to relate the thin wall's parameters (responses), namely track width, surface roughness and hardness to the process parameters considered in this research (laser power, scanning speed and layer thickness) and to find out the optimal manufacturing conditions. Design of experiment (DoE) was used by implementing composite central design to achieve better manufacturing qualities. Mathematical models derived from the statistical analysis were used to establish the relationships between the process parameters and the responses. Also, the effects of process parameters on each response were determined. Then, a numerical optimization was performed to find out the optimal process set at which the quality features are at their desired values. Based on this study, the relationship between process parameters and SLMed thin-walled structure was revealed and thus, the corresponding optimal process parameters can be used to manufactured thin-walled parts with high quality.

Theory of Current-Driven Domain Wall Motion

NASA Astrophysics Data System (ADS)

Tatara, Gen

2004-03-01

Current-induced motion of a domain wall is studied starting from a microscopic Hamiltonian with an exchange interaction between conduction electrons and spins of the wall [1]. With a key observation that the position X and the angle φ0 the wall magnetization forms with the easy plane are the proper collective coordinates to describe its dynamics, it follows straightforwardly that the electric current affects the wall motion in two different ways, in agreement with Berger's pioneering observations[2]. The first is as a force, or momentum transfer, due to the reflection of conduction electrons. This force is proportional to the charge current j and wall resistivity ρ_w, and hence becomes important in thin walls. The other is as a spin torque or spin transfer[3], which is dominant for thick walls where the spin of conduction electron follows the magnetization adiabatically. The motion of a domain wall under a steady current is studied in two limiting cases. In the adiabatic case, we show that even without a pinning force, there is a threshold spin current, j_s^cr∝ K_⊥λ, below which the wall does not move (K_⊥ and λ being the hard-axis magnetic anisotropy and wall thickness, respectively). Below the threshold, the transferred angular momentum is used to shift φ0 and not to the wall motion. The pinning potential V0 affects j_s^cr only if it is very strong, V0 > K_⊥/α, where α is the damping parameter in the Landau-Lifshits-Gilbert equation. Therefore, the critical current for the adiabatic wall does not suffer very much from weak pinning, which is consistent with experimental observations[4]. The wall velocity after depinning is found to be ∝[(j_s/j_s^cr)^2-1]^1/2. In the case of thin wall, driven by a force ∝ ρw j, the critical current density is given by j^cr∝ V_0/ρ_w. In nanocontacts, this is estimated to be ˜ 10^7[A/m^2]. This small critical current would be advantageous for device application. [1] G.Tatara and H.Kohno, cond-mat/0308464

49 CFR 179.100-6 - Thickness of plates.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

49 CFR 179.100-6 - Thickness of plates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

49 CFR 179.220-6 - Thickness of plates.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-6 Thickness of plates. (a) The wall...

49 CFR 179.100-6 - Thickness of plates.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-6 Thickness of plates. (a) The wall...

49 CFR 179.200-6 - Thickness of plates.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-6 Thickness of plates. (a) The wall...

49 CFR 179.220-6 - Thickness of plates.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-6 Thickness of plates. (a) The wall...

49 CFR 179.200-6 - Thickness of plates.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-6 Thickness of plates. (a) The wall...

An experimental study of near wall flow parameters in the blade end-wall corner region

NASA Technical Reports Server (NTRS)

Bhargava, Rakesh K.; Raj, Rishi S.

1989-01-01

The near wall flow parameters in the blade end-wall corner region is investigated. The blade end-wall corner region was simulated by mounting an airfoil section (NACA 65-015 base profile) symmetric blades on both sides of the flat plate with semi-circular leading edge. The initial 7 cm from the leading edge of the flat plate was roughened by gluing No. 4 floor sanding paper to artificially increase the boundary layer thickness on the flat plate. The initial flow conditions of the boundary layer upstream of the corner region are expected to dictate the behavior of flow inside the corner region. Therefore, an experimental investigation was extended to study the combined effect of initial roughness and increased level of free stream turbulence on the development of a 2-D turbulent boundary layer in the absence of the blade. The measurement techniques employed in the present investigation included, the conventional pitot and pitot-static probes, wall taps, the Preston tube, piezoresistive transducer and the normal sensor hot-wire probe. The pitot and pitot-static probes were used to obtain mean velocity profile measurements within the boundary layer. The measurements of mean surface static pressure were obtained with the surface static tube and the conventional wall tap method. The wall shear vector measurements were made with a specially constructed Preston tube. The flush mounted piezoresistive type pressure transducer were employed to measure the wall pressure fluctuation field. The velocity fluctuation measurements, used in obtaining the wall pressure-velocity correlation data, were made with normal single sensor hot-wire probe. At different streamwise stations, in the blade end-wall corner region, the mean values of surface static pressure varied more on the end-wall surface in the corner region were mainly caused by the changes in the curvature of the streamlines. The magnitude of the wall shear stress in the blade end-wall corner region increased significantly

Effect of wall roughness on liquid oscillations damping in rectangular tanks

NASA Technical Reports Server (NTRS)

Bugg, F. M.

1970-01-01

Tests were conducted in two rectangular glass tanks using silicon carbide grit bonded to walls to determine effect of wall roughness for damping liquid oscillations. Tests included effects of roughness height, roughness location, roughness at various values, amplitude decay, Reynolds number, and boundary layer thickness.

Dry granular avalanche impact force on a rigid wall: Analytic shock solution versus discrete element simulations

NASA Astrophysics Data System (ADS)

Albaba, Adel; Lambert, Stéphane; Faug, Thierry

2018-05-01

The present paper investigates the mean impact force exerted by a granular mass flowing down an incline and impacting a rigid wall of semi-infinite height. First, this granular flow-wall interaction problem is modeled by numerical simulations based on the discrete element method (DEM). These DEM simulations allow computing the depth-averaged quantities—thickness, velocity, and density—of the incoming flow and the resulting mean force on the rigid wall. Second, that problem is described by a simple analytic solution based on a depth-averaged approach for a traveling compressible shock wave, whose volume is assumed to shrink into a singular surface, and which coexists with a dead zone. It is shown that the dead-zone dynamics and the mean force on the wall computed from DEM can be reproduced reasonably well by the analytic solution proposed over a wide range of slope angle of the incline. These results are obtained by feeding the analytic solution with the thickness, the depth-averaged velocity, and the density averaged over a certain distance along the incline rather than flow quantities taken at a singular section before the jump, thus showing that the assumption of a shock wave volume shrinking into a singular surface is questionable. The finite length of the traveling wave upstream of the grains piling against the wall must be considered. The sensitivity of the model prediction to that sampling length remains complicated, however, which highlights the need of further investigation about the properties and the internal structure of the propagating granular wave.

Numerical simulation of the effect of groundwater salinity on artificial freezing wall in coastal area

NASA Astrophysics Data System (ADS)

Hu, Rui; Liu, Quan

2017-04-01

During the engineering projects with artificial ground freezing (AFG) techniques in coastal area, the freezing effect is affected by groundwater salinity. Based on the theories of artificially frozen soil and heat transfer in porous material, and with the assumption that only the variations of total dissolved solids (TDS) impact on freezing point and thermal conductivity, a numerical model of an AFG project in a saline aquifer was established and validated by comparing the simulated temperature field with the calculated temperature based on the analytic solution of rupak (reference) for single-pipe freezing temperature field T. The formation and development of freezing wall were simulated with various TDS. The results showed that the variety of TDS caused the larger temperature difference near the frozen front. With increasing TDS in the saline aquifer (1 35g/L), the average thickness of freezing wall decreased linearly and the total formation time of the freezing wall increased linearly. Compared with of the scenario of fresh-water (<1g/L), the average thickness of frozen wall decreased by 6% and the total formation time of the freezing wall increased by 8% with each increasing TDS of 7g/L. Key words: total dissolved solids, freezing point, thermal conductivity, freezing wall, numerical simulation Reference D.J.Pringel, H.Eicken, H.J.Trodahl, etc. Thermal conductivity of landfast Antarctic and Arctic sea ice[J]. Journal of Geophysical Research, 2007, 112: 1-13. Lukas U.Arenson, Dave C.Sego. The effect of salinity on the freezing of coarse- grained sand[J]. Canadian Geotechnical Journal, 2006, 43: 325-337. Hui Bing, Wei Ma. Laboratory investigation of the freezing point of saline soil[J]. Cold Regions Science and Technology, 2011, 67: 79-88.

Fiber pigtailed thin wall capillary coupler for excitation of microsphere WGM resonator.

PubMed

Wang, Hanzheng; Lan, Xinwei; Huang, Jie; Yuan, Lei; Kim, Cheol-Woon; Xiao, Hai

2013-07-01

In this paper, we demonstrate a fiber pigtailed thin wall capillary coupler for excitation of Whispering Gallery Modes (WGMs) of microsphere resonators. The coupler is made by fusion-splicing an optical fiber with a capillary tube and consequently etching the capillary wall to a thickness of a few microns. Light is coupled through the peripheral contact between inserted microsphere and the etched capillary wall. The coupling efficiency as a function of the wall thickness was studied experimentally. WGM resonance with a Q-factor of 1.14 × 10(4) was observed using a borosilicate glass microsphere with a diameter of 71 μm. The coupler operates in the reflection mode and provides a robust mechanical support to the microsphere resonator. It is expected that the new coupler may find broad applications in sensors, optical filters and lasers.

The effect of ethanol vapour exposure on atrial and ventricular walls of chick embryos.

PubMed

Kamran, Kiran; Khan, Muhammad Yunus; Minhas, Liaqat Ali

2016-10-01

To study the effects of ethanol vapour exposure on atrial and ventricular walls of heart in chick embryo. The study design was experimental, conducted at Islamabad Centre of College of Physicians and Surgeons, Pakistan. One hundred and eighty chicken eggs were divided into two groups, experimental and control, of 90 eggs each. Each group was subdivided into three subgroups of 30 eggs each based on the day of sacrifice. Experimental group was exposed to ethanol vapours and then compared with age matched controls. The thickness of atrial and ventricular walls along with lengths of valvular cusps increased in hearts of day 7 and day 10 chick embryos in experimental group. There was thinning of walls and decreased length of valvular cusps in hearts of experimental chicks on hatching as compared to age matched controls. Ethanol vapour exposure during development causes cardiac and septal wall thickening during initial days of development followed by cardiac and septal wall thinning which is a classical picture of alcohol induced cardiomyopathies.

Positive feedback loop for cystitis cystica: the effect of recurrent urinary tract infection on the number of bladder wall mucosa nodules.

PubMed

Vrljicak, Kristina; Turudić, Daniel; Bambir, Ivan; Gradiski, Ivan Pavao; Spajić, Borislav; Batinić, Danica; Topalović-Grković, Marija; Spajić, Marija; Batinić, Danko; Milosević, Danko

2013-12-01

The main purpose of this study was to demonstrate positive feedback loop between bladder wall nodules (nodules being one of the key diagnostic factors), bladder wall thickness, and recurrent urinary tract infections. Cystitis cystica was diagnosed in 115 prepubertal girls (mean age 7.79 +/- 3.05 years) by optic examination of bladder mucosal nodules and by ultrasonographic measurement of bladder wall thickness. Bladder wall thickness increased with the frequency of recurrent urinary tract infections as well as with the number of nodules on bladder wall mucosa (3.52 +/- 0.522 mm < or = 5 nodules vs. 4.42 +/- 0.429 mm 6-10 nodules vs. 5.20 +/- 0.610 mm > 10 nodules, respectively). Study results suggested that early control of urinary tract infections by chemoprophylaxis could prevent higher grades of bladder wall mucosal changes and consequently shorten the length of chemoprophylaxis.

Domain wall roughness and creep in nanoscale crystalline ferroelectric polymers

NASA Astrophysics Data System (ADS)

Xiao, Z.; Poddar, Shashi; Ducharme, Stephen; Hong, X.

2013-09-01

We report piezo-response force microscopy studies of the static and dynamic properties of domain walls (DWs) in 11 to 36 nm thick films of crystalline ferroelectric poly(vinylidene-fluoride-trifluorethylene). The DW roughness exponent ζ ranges from 0.39 to 0.48 and the DW creep exponent μ varies from 0.20 to 0.28, revealing an unexpected effective dimensionality of ˜1.5 that is independent of film thickness. Our results suggest predominantly 2D ferroelectricity in the layered polymer and we attribute the fractal dimensionality to DW deroughening due to the correlations between the in-plane and out-of-plane polarization, an effect that can be exploited to achieve high lateral domain density for developing nanoscale ferroelectrics-based applications.

Reconstruction with a patient-specific titanium implant after a wide anterior chest wall resection

PubMed Central

Turna, Akif; Kavakli, Kuthan; Sapmaz, Ersin; Arslan, Hakan; Caylak, Hasan; Gokce, Hasan Suat; Demirkaya, Ahmet

2014-01-01

The reconstruction of full-thickness chest wall defects is a challenging problem for thoracic surgeons, particularly after a wide resection of the chest wall that includes the sternum. The location and the size of the defect play a major role when selecting the method of reconstruction, while acceptable cosmetic and functional results remain the primary goal. Improvements in preoperative imaging techniques and reconstruction materials have an important role when planning and performing a wide chest wall resection with a low morbidity rate. In this report, we describe the reconstruction of a wide anterior chest wall defect with a patient-specific custom-made titanium implant. An infected mammary tumour recurrence in a 62-year old female, located at the anterior chest wall including the sternum, was resected, followed by a large custom-made titanium implant. Latissimus dorsi flap and split-thickness graft were also used for covering the implant successfully. A titanium custom-made chest wall implant could be a viable alternative for patients who had large chest wall tumours. PMID:24227881

Associations of anger, anxiety, and depressive symptoms with carotid arterial wall thickness: the multi-ethnic study of atherosclerosis.

PubMed

Ohira, Tetsuya; Diez Roux, Ana V; Polak, Joseph F; Homma, Shunichi; Iso, Hiroyasu; Wasserman, Bruce A

2012-06-01

Carotid arterial wall thickness, measured as intima-media thickness (IMT), is an early subclinical indicator of cardiovascular disease. Few studies have investigated the association of psychological factors with IMT across multiple ethnic groups and by sex. We included 6561 men and women (2541 whites, 1790 African Americans, 1436 Hispanics, and 794 Chinese) aged 45 to 84 years who took part in the first examination of the Multi-Ethnic Study of Atherosclerosis. Associations of trait anger, trait anxiety, and depressive symptoms with mean values of common carotid artery (CCA) and internal carotid artery (ICA) IMTs were investigated using multivariable regression and logistic models. In age-, sex-, and race/ethnicity-adjusted analyses, the trait anger score was positively associated with CCA and ICA IMTs (mean differences per 1-standard deviation increment of trait anger score were 0.014 [95% confidence interval {CI} = 0.003-0.025, p = .01] and 0.054 [95% CI = 0.017-0.090, p = .004] for CCA and ICA IMTs, respectively). Anger was also associated with the presence of carotid plaque (age-, sex-, and race/ethnicity-adjusted odds ratio per 1-standard deviation increase in trait anger = 1.27 [95% CI = 1.06-1.52]). The associations of the anger score with thicker IMT were attenuated after adjustment for covariates but remained statistically significant. Associations were stronger in men than in women and in whites than in other race/ethnic groups, but heterogeneity was only marginally statistically significant by race/ethnicity. There was no association of depressive symptoms or trait anxiety with IMT. Only one of the three measures examined was associated with IMT, and the patterns seemed to be heterogeneous across race/ethnic groups.

Effect of metallic walls on dynamos generated by laminar boundary-driven flow in a spherical domain.

PubMed

Guervilly, Céline; Wood, Toby S; Brummell, Nicholas H

2013-11-01

We present a numerical study of dynamo action in a conducting fluid encased in a metallic spherical shell. Motions in the fluid are driven by differential rotation of the outer metallic shell, which we refer to as "the wall." The two hemispheres of the wall are held in counter-rotation, producing a steady, axisymmetric interior flow consisting of differential rotation and a two-cell meridional circulation with radial inflow in the equatorial plane. From previous studies, this type of flow is known to maintain a stationary equatorial dipole by dynamo action if the magnetic Reynolds number is larger than about 300 and if the outer boundary is electrically insulating. We vary independently the thickness, electrical conductivity, and magnetic permeability of the wall to determine their effect on the dynamo action. The main results are the following: (a) Increasing the conductivity of the wall hinders the dynamo by allowing eddy currents within the wall, which are induced by the relative motion of the equatorial dipole field and the wall. This processes can be viewed as a skin effect or, equivalently, as the tearing apart of the dipole by the differential rotation of the wall, to which the field lines are anchored by high conductivity. (b) Increasing the magnetic permeability of the wall favors dynamo action by constraining the magnetic field lines in the fluid to be normal to the wall, thereby decoupling the fluid from any induction in the wall. (c) Decreasing the wall thickness limits the amplitude of the eddy currents, and is therefore favorable for dynamo action, provided that the wall is thinner than the skin depth. We explicitly demonstrate these effects of the wall properties on the dynamo field by deriving an effective boundary condition in the limit of vanishing wall thickness.

Research on the thickness control method of workbench oil film based on theoretical model

NASA Astrophysics Data System (ADS)

Pei, Tang; Lin, Lin; Liu, Ge; Yu, Liping; Xu, Zhen; Zhao, Di

2018-06-01

To improve the thickness adjustability of the workbench oil film, we designed a software system to control the thickness of oil film based on the Siemens 840dsl CNC system and set up an experimental platform. A regulation scheme of oil film thickness based on theoretical model is proposed, the accuracy and feasibility of which is proved by experiment results. It's verified that the method mentioned above can meet the demands of workbench oil film thickness control, the experiment is simple and efficient with high control precision. Reliable theory support is supplied for the development of workbench oil film active control system as well.

Thickness optimization of the ZnO based TCO layer in a CZTSSe solar cell. Evolution of its performance with thickness when external temperature changes.

NASA Astrophysics Data System (ADS)

Chadel, Meriem; Moustafa Bouzaki, Mohammed; Chadel, Asma; Aillerie, Michel; Benyoucef, Boumediene

2017-07-01

The influence of the thickness of a Zinc Oxide (ZnO) transparent conductive oxide (TCO) layer on the performance of the CZTSSe solar cell is shown in detail. In a photovoltaic cell, the thickness of each layer largely influence the performance of the solar cell and optimization of each layer constitutes a complete work. Here, using the Solar Cell Capacitance Simulation (SCAPS) software, we present simulation results obtained in the analyze of the influence of the TCO layer thickness on the performance of a CZTSSe solar cell, starting from performance of a CZTSSe solar cell commercialized in 2014 with an initial efficiency equal to 12.6%. In simulation, the temperature was considered as a functioning parameter and the evolution of tthe performance of the cell for various thickness of the TCO layer when the external temperature changes is simulated and discussed. The best efficiency of the solar cell based in CZTSSe is obtained with a ZnO thickness equal to 50 nm and low temperature. Based on the considered marketed cell, we show a technological possible increase of the global efficiency achieving 13% by optimization of ZnO based TCO layer.

Acid base activity of live bacteria: Implications for quantifying cell wall charge

NASA Astrophysics Data System (ADS)

Claessens, Jacqueline; van Lith, Yvonne; Laverman, Anniet M.; Van Cappellen, Philippe

2006-01-01

To distinguish the buffering capacity associated with functional groups in the cell wall from that resulting from metabolic processes, base or acid consumption by live and dead cells of the Gram-negative bacterium Shewanella putrefaciens was measured in a pH stat system. Live cells exhibited fast consumption of acid (pH 4) or base (pH 7, 8, 9, and 10) during the first few minutes of the experiments. At pH 5.5, no acid or base was required to maintain the initial pH constant. The initial amounts of acid or base consumed by the live cells at pH 4, 8, and 10 were of comparable magnitudes as those neutralized at the same pHs by intact cells killed by exposure to gamma radiation or ethanol. Cells disrupted in a French press required higher amounts of acid or base, due to additional buffering by intracellular constituents. At pH 4, acid neutralization by suspensions of live cells stopped after 50 min, because of loss of viability. In contrast, under neutral and alkaline conditions, base consumption continued for the entire duration of the experiments (5 h). This long-term base neutralization was, at least partly, due to active respiration by the cells, as indicated by the build-up of succinate in solution. Qualitatively, the acid-base activity of live cells of the Gram-positive bacterium Bacillus subtilis resembled that of S. putrefaciens. The pH-dependent charging of ionizable functional groups in the cell walls of the live bacteria was estimated from the initial amounts of acid or base consumed in the pH stat experiments. From pH 4 to 10, the cell wall charge increased from near-zero values to about -4 × 10 -16 mol cell -1 and -6.5 × 10 -16 mol cell -1 for S. putrefaciens and B. subtilis, respectively. The similar cell wall charging of the two bacterial strains is consistent with the inferred low contribution of lipopolysaccharides to the buffering capacity of the Gram-negative cell wall (of the order of 10%).

BALLIST: A computer program to empirically predict the bumper thickness required to prevent perforation of the Space Station by orbital debris

NASA Technical Reports Server (NTRS)

Rule, William Keith

1991-01-01

A computer program called BALLIST that is intended to be a design tool for engineers is described. BALLlST empirically predicts the bumper thickness required to prevent perforation of the Space Station pressure wall by a projectile (such as orbital debris) as a function of the projectile's velocity. 'Ballistic' limit curves (bumper thickness vs. projectile velocity) are calculated and are displayed on the screen as well as being stored in an ASCII file. A Whipple style of spacecraft wall configuration is assumed. The predictions are based on a database of impact test results. NASA/Marshall Space Flight Center currently has the capability to generate such test results. Numerical simulation results of impact conditions that can not be tested (high velocities or large particles) can also be used for predictions.

Research on the effect of wall corrosion and rim seal on the withdrawal loss for a floating roof tank.

PubMed

Wang, Yongqiang; Liu, Minmin; Liu, Fang; Zhao, Chaocheng; Zhao, Dongfeng; Han, Fenglei; Liu, Chunshuang

2018-04-25

Storage tanks are important parts of volatile organic compound (VOC) fugitive emission sources of the petrochemical industry; the floating roof tank is the main oil storage facility at present. Based on the mechanism of withdrawal loss and the type of rim seal, octane and gasoline were taken as the research objects. A model instrument for simulating the oil loading process by the 316 stainless steel and A3 carbon steel as the test piece was designed, and the film thickness was measured by wet film thickness gauge to investigate the influence of the corrosion of the tank wall and rim seal on the withdrawal loss for floating roof tanks. It was found that withdrawal loss was directly proportional to the shell factor, and the oil thickness of the octane and gasoline increased with the strength of the wall corrosion with the same wall material and rim seal. Compared with the untreated test piece, the oil film thickness of the octane/gasoline was increased by 7.04~8.57 μm/13.14~21.93 μm and 5.59~11.49 μm/11.61~25.48 μm under the corrosion of hydrochloric acid for 32 and 75 h, respectively. The oil film thickness of octane and gasoline decreased with the increasing of the rim seal, and the oil film thickness of the octane decreased by 11.97~28.90% and 37.32~73.83% under the resilient-filled seal and the double seal, respectively. The gasoline dropped by 11.97~31.18% and 45.98~75.34% under the resilient-filled seal and the double seal, respectively. In addition, the tank surface roughness reduced the compression of the rim seal on the tank wall, and the effect of scraping decreased. The API withdrawal loss formula for a floating roof tank was recommended to take into account the effect of the rim seal to improve the accuracy of the loss evaluation. Finally, some measures of reducing the withdrawal loss were proposed.

Turbulent flame-wall interaction: a DNS study

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

Chen, Jackie; Hawkes, Evatt R; Sankaran, Ramanan

2010-01-01

A turbulent flame-wall interaction (FWI) configuration is studied using three-dimensional direct numerical simulation (DNS) and detailed chemical kinetics. The simulations are used to investigate the effects of the wall turbulent boundary layer (i) on the structure of a hydrogen-air premixed flame, (ii) on its near-wall propagation characteristics and (iii) on the spatial and temporal patterns of the convective wall heat flux. Results show that the local flame thickness and propagation speed vary between the core flow and the boundary layer, resulting in a regime change from flamelet near the channel centreline to a thickened flame at the wall. This findingmore » has strong implications for the modelling of turbulent combustion using Reynolds-averaged Navier-Stokes or large-eddy simulation techniques. Moreover, the DNS results suggest that the near-wall coherent turbulent structures play an important role on the convective wall heat transfer by pushing the hot reactive zone towards the cold solid surface. At the wall, exothermic radical recombination reactions become important, and are responsible for approximately 70% of the overall heat release rate at the wall. Spectral analysis of the convective wall heat flux provides an unambiguous picture of its spatial and temporal patterns, previously unobserved, that is directly related to the spatial and temporal characteristic scalings of the coherent near-wall turbulent structures.« less

Enhanced cortical thickness measurements for rodent brains via Lagrangian-based RK4 streamline computation

NASA Astrophysics Data System (ADS)

Lee, Joohwi; Kim, Sun Hyung; Oguz, Ipek; Styner, Martin

2016-03-01

The cortical thickness of the mammalian brain is an important morphological characteristic that can be used to investigate and observe the brain's developmental changes that might be caused by biologically toxic substances such as ethanol or cocaine. Although various cortical thickness analysis methods have been proposed that are applicable for human brain and have developed into well-validated open-source software packages, cortical thickness analysis methods for rodent brains have not yet become as robust and accurate as those designed for human brains. Based on a previously proposed cortical thickness measurement pipeline for rodent brain analysis,1 we present an enhanced cortical thickness pipeline in terms of accuracy and anatomical consistency. First, we propose a Lagrangian-based computational approach in the thickness measurement step in order to minimize local truncation error using the fourth-order Runge-Kutta method. Second, by constructing a line object for each streamline of the thickness measurement, we can visualize the way the thickness is measured and achieve sub-voxel accuracy by performing geometric post-processing. Last, with emphasis on the importance of an anatomically consistent partial differential equation (PDE) boundary map, we propose an automatic PDE boundary map generation algorithm that is specific to rodent brain anatomy, which does not require manual labeling. The results show that the proposed cortical thickness pipeline can produce statistically significant regions that are not observed in the previous cortical thickness analysis pipeline.

Cladding Attachment Over Thick Exterior Insulating Sheathing

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

Baker, P.; Eng, P.; Lepage, R.

The addition of insulation to the exterior of buildings is an effective means of increasing the thermal resistance of both wood framed walls as well as mass masonry wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use of wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location (Straube and Smegal 2009, Pettit 2009, Joyce 2009, Ueno 2010). The research presented in this report is intended to help develop a better understanding of the systemmore » mechanics involved and the potential for environmental exposure induced movement between the furring strip and the framing. BSC sought to address the following research questions: 1.What are the relative roles of the mechanisms and the magnitudes of the force that influence the vertical displacement resistance of the system? 2.Can the capacity at a specified deflection be reliably calculated using mechanics based equations? 3.What are the impacts of environmental exposure on the vertical displacement of furring strips attached directly through insulation back to a wood structure?« less

Cladding Attachment Over Thick Exterior Insulating Sheathing

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

Baker, P.; Eng, P.; Lepage, R.

The addition of insulation to the exterior of buildings is an effective means of increasing the thermal resistance of both wood framed walls as well as mass masonry wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use of wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location (Straube and Smegal 2009, Pettit 2009, Joyce 2009, Ueno 2010). The research presented in this report is intended to help develop a better understanding of the systemmore » mechanics involved and the potential for environmental exposure induced movement between the furring strip and the framing. BSC sought to address the following research questions: 1. What are the relative roles of the mechanisms and the magnitudes of the force that influence the vertical displacement resistance of the system? 2. Can the capacity at a specified deflection be reliably calculated using mechanics based equations? 3. What are the impacts of environmental exposure on the vertical displacement of furring strips attached directly through insulation back to a wood structure?« less

Stress-based control of magnetic nanowire domain walls in artificial multiferroic systems

NASA Astrophysics Data System (ADS)

Dean, J.; Bryan, M. T.; Schrefl, T.; Allwood, D. A.

2011-01-01

Artificial multiferroic systems, which combine piezoelectric and piezomagnetic materials, offer novel methods of controlling material properties. Here, we use combined structural and magnetic finite element models to show how localized strains in a piezoelectric film coupled to a piezomagnetic nanowire can attract and pin magnetic domain walls. Synchronous switching of addressable contacts enables the controlled movement of pinning sites, and hence domain walls, in the nanowire without applied magnetic field or spin-polarized current, irrespective of domain wall structure. Conversely, domain wall-induced strain in the piezomagnetic material induces a local potential difference in the piezoelectric, providing a mechanism for sensing domain walls. This approach overcomes the problems in magnetic nanowire memories of domain wall structure-dependent behavior and high power consumption. Nonvolatile random access or shift register memories based on these effects can achieve storage densities >1 Gbit/In2, sub-10 ns switching times, and power consumption <100 keV per operation.

Optimization of an asymmetric thin-walled tube in rotary draw bending process

NASA Astrophysics Data System (ADS)

Xue, Xin; Liao, Juan; Vincze, Gabriela; Gracio, Jose J.

2013-12-01

The rotary draw bending is one of the advanced thin-walled tube forming processes with high efficiency, low consumption and good flexibility in several industries such as automotive, aerospace and shipping. However it may cause undesirable deformations such as over-thinning and ovalization, which bring the weakening of the strength and difficulties in the assembly process respectively. Accurate modeling and effective optimization design to eliminate or reduce undesirable deformations in tube bending process have been a challenging topic. In this paper, in order to study the deformation behaviors of an asymmetric thin-walled tube in rotary draw bending process, a 3D elastic-plastic finite element model has been built under the ABAQUS environment, and the reliability of the model is validated by comparison with experiment. Then, the deformation mechanism of thin-walled tube in bending process was briefly analysis and the effects of wall thickness ratio, section height width ratio and mandrel extension on wall thinning and ovalization in bending process were investigated by using Response Surface Methodology. Finally, multi-objective optimization method was used to obtain an optimum solution of design variables based on simulation results.

Thermal modeling and analysis of thin-walled structures in micro milling

NASA Astrophysics Data System (ADS)

Zhang, J. F.; Ma, Y. H.; Feng, C.; Tang, W.; Wang, S.

2017-11-01

The numerical analytical model has been developed to predict the thermal effect with respect to thin walled structures by micro-milling. In order to investigate the temperature distribution around micro-edge of cutter, it is necessary to considering the friction power, the shearing power, the shear area between the tool micro-edge and materials. Due to the micro-cutting area is more difficult to be measured accurately, the minimum chip thickness as one of critical factors is also introduced. Finite element-based simulation was employed by the Advantedge, which was determined from the machining of Ti-6Al-4V over a range of the uncut chip thicknesses. Results from the proposed model have been successfully accounted for the effects of thermal softening for material.

Layer-by-layer-based silica encapsulation of individual yeast with thickness control.

PubMed

Lee, Hojae; Hong, Daewha; Choi, Ji Yu; Kim, Ji Yup; Lee, Sang Hee; Kim, Ho Min; Yang, Sung Ho; Choi, Insung S

2015-01-01

In the area of cell-surface engineering with nanomaterials, the metabolic and functional activities of the encapsulated cells are manipulated and controlled by various parameters of the artificial shells that encase the cells, such as stiffness and elasticity, thickness, and porosity. The mechanical durability and physicochemical stability of inorganic shells prove superior to layer-by-layer-based organic shells with regard to cytoprotection, but it has been difficult to vary the parameters of inorganic shells including their thickness. In this work, we combine the layer-by-layer technique with a process of bioinspired silicification to control the thickness of the silica shells that encapsulate yeast Saccharomyces cerevisiae cells individually, and investigate the thickness-dependent microbial growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laser and Pressure Resistance Weld of Thin-Wall Cladding for LWR Accident-Tolerant Fuels

NASA Astrophysics Data System (ADS)

Gan, J.; Jerred, N.; Perez, E.; Haggard, D. C.

2017-12-01

FeCrAl alloy with typical composition of approximately Fe-15Cr-5Al is considered a primary candidate cladding material for light water reactor accident-tolerant fuel because of its superior resistance to oxidation in high-temperature steam compared with Zircaloy cladding. Thin-walled FeCrAl cladding at 350 μm wall thickness is required, and techniques for joining endplug to cladding need to be developed. Fusion-based laser weld and solid-state joining with pressure resistance weld were investigated in this study. The results of microstructural characterization, mechanical property evaluation by tensile testing, and hydraulic pressure burst testing of the welds for the cladding-endplug specimen are discussed.

Laser and Pressure Resistance Weld of Thin-Wall Cladding for LWR Accident-Tolerant Fuels

NASA Astrophysics Data System (ADS)

Gan, J.; Jerred, N.; Perez, E.; Haggard, D. C.

2018-02-01

FeCrAl alloy with typical composition of approximately Fe-15Cr-5Al is considered a primary candidate cladding material for light water reactor accident-tolerant fuel because of its superior resistance to oxidation in high-temperature steam compared with Zircaloy cladding. Thin-walled FeCrAl cladding at 350 μm wall thickness is required, and techniques for joining endplug to cladding need to be developed. Fusion-based laser weld and solid-state joining with pressure resistance weld were investigated in this study. The results of microstructural characterization, mechanical property evaluation by tensile testing, and hydraulic pressure burst testing of the welds for the cladding-endplug specimen are discussed.

Gastric wall changes after intragastric balloon placement: a preliminary experience.

PubMed

Périssé, Luís Gustavo Santos; Ecbc-Rj, Paulo Cézar Marques Périssé; Ribeiro, Kelson Ferreira

2016-01-01

: to evaluate the thickness of the gastric wall at the time of intra gastric balloon (IGB) placement, at the time of its withdrawal and one month after withdrawal. : fifteen morbidly obese patients underwent the introduction of IGB under general anesthesia. In all patients, there was infusion of 500ml of distilled water in the balloon for the test. Measurements of the thickness of the gastric wall were made in the antrum, body and proximal body, using a radial echoendoscope with a frequency of 12MHz and maximum zoom, and its own balloon inflated with 5ml of distilled water. : the presence of IGB led to increased wall thickness of the gastric body by expanding the muscle layer. These changes were apparently transient, since 30 days after the balloon withdrawal there was a tendency to return of the wall thickness values ​​observed before the balloon insertion. : the use of intragastric balloon for the treatment of obesity determines transient increase in the wall thickness of the gastric body caused by expanded muscle layer. avaliar a espessura da parede gástrica no momento do posicionamento do balão intragástrico (BIG), no momento de sua retirada e um mês após a retirada. quinze pacientes obesos mórbidos foram submetidos à introdução de BIG sob anestesia geral. Em todos os pacientes foi feita infusão de 500 ml de água destilada e o balão foi insuflado com 5ml de água destilada. As medidas da espessura da parede gástrica foram feitas no antro, corpo e corpo alto utilizando-se um ecoendoscópio radial com frequência de 12MHz e zoom máximo. a presença do BIG levou ao aumento da espessura da parede do corpo gástrico pelo aumento de espessura da sua camada muscular. Estas alterações são aparentemente transitórias já que após 30 dias da retirada do balão existiu uma tendência de retorno da espessura da parede aos valores observados antes do seu posicionamento. a utilização do balão intragástrico para tratamento da obesidade determina

Translucency of zirconia-based pressable ceramics with different core and veneer thicknesses.

PubMed

Jeong, Il-Do; Bae, So-Yeon; Kim, Dong-Yeon; Kim, Ji-Hwan; Kim, Woong-Chul

2016-06-01

Little information is available on the translucency of zirconia-based pressable ceramic restorations with a pressed ceramic veneer and zirconia core in various thickness combinations. The purpose of this in vitro study was to assess the translucency of 3 types of zirconia-based pressable ceramics for different core-veneer thickness combinations. A bilayered ceramic specimen was prepared with a pressable ceramic (IPS e.max Zirpress, Initial IQ, Rosetta UltraPress) veneer over a zirconia core (Zenostar Zr). Three groups of specimens (n=7) were formed with the following core+veneer thicknesses: 1 +0.5 mm, 0.7 +0.8 mm, and 0.5 +1 mm. To obtain consistent thickness and high translucency, all specimens were subjected to surface grinding with a grinding machine. To eliminate the effect of differences in roughness on the translucency, the surface roughness of the ground specimens was measured with a scanning profiler, and the consistency of these measured values was verified through statistical analysis. The luminous transmittance of the specimens was measured with a spectrophotometer. The effects of the pressable ceramic type and core-veneer thickness combination on transmittance were assessed using a 2-way ANOVA (α=.05). The consistency of the surface roughness among the tested specimens was confirmed using a 1-way ANOVA and the Tukey HSD post hoc test (P<.05). The luminous transmittance exhibited a statistically significant dependence on both the type of pressable ceramic and the core-veneer thickness combination (P<.05). The type of pressable ceramic and core-veneer thickness combination affected the translucency of the restoration. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall

PubMed Central

Huang, Shiping; Hu, Mengyu; Cui, Nannan; Wang, Weifeng

2018-01-01

The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry. PMID:29673176

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall.

PubMed

Huang, Shiping; Hu, Mengyu; Huang, Yonghui; Cui, Nannan; Wang, Weifeng

2018-04-17

The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry.

Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance.

PubMed

Ene, Iuliana V; Walker, Louise A; Schiavone, Marion; Lee, Keunsook K; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A R; Munro, Carol A; Brown, Alistair J P

2015-07-28

The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. The C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by

Mechanical Properties of Additively Manufactured Thick Honeycombs.

PubMed

Hedayati, Reza; Sadighi, Mojtaba; Mohammadi Aghdam, Mohammad; Zadpoor, Amir Abbas

2016-07-23

Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson's ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

Mechanical Properties of Additively Manufactured Thick Honeycombs

PubMed Central

Hedayati, Reza; Sadighi, Mojtaba; Mohammadi Aghdam, Mohammad; Zadpoor, Amir Abbas

2016-01-01

Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions. PMID:28773735

Modelling the thermomechanical behaviour of the tungsten first wall in HiPER laser fusion scenarios

NASA Astrophysics Data System (ADS)

Garoz, D.; Páramo, A. R.; Rivera, A.; Perlado, J. M.; González-Arrabal, R.

2016-12-01

The behaviour of a tungsten first wall is studied under the irradiation conditions predicted for the different operational scenarios of the European laser fusion project HiPER, which is based on direct drive targets and an evacuated dry wall chamber. The scenarios correspond to different stages in the development of a nuclear fusion reactor, from proof of principle (bunch mode facility) to economic feasibility (pre-commercial power plant). This work constitutes a quantitative study to evaluate first wall performance under realistic irradiation conditions in the different scenarios. We calculated the radiation fluxes assuming the geometrical configurations reported so far for HiPER. Then, we calculated the irradiation-induced evolution of first wall temperature and the thermomechanical response of the material. The results indicate that the first wall will plastically deform up to a few microns underneath the surface. Continuous operation in a power plant leads to fatigue failure with crack generation and growth. Finally, crack propagation and the minimum tungsten thickness required to fulfil the first wall protection role is studied. The response of tungsten as a first wall material as well as its main limitations will be discussed for the HiPER scenarios.

Biofilm thickness measurement using an ultrasound method in a liquid phase.

PubMed

Maurício, R; Dias, C J; Jubilado, N; Santana, F

2013-10-01

In this report, the development of an online, noninvasive, measurement method of the biofilm thickness in a liquid phase is presented. The method is based in the analysis of the ultrasound wave pulse-echo behavior in a liquid phase reproducing the real reactor conditions. It does not imply the removal of the biomass from the support or any kind of intervention in the support (pipes) to detect and perform the measurements (non-invasiveness). The developed method allows for its sensor to be easily and quickly mounted and unmounted in any location along a pipe or reactor wall. Finally, this method is an important innovation because it allows the thickness measurement of a biofilm, in liquid phase conditions that can be used in monitoring programs, to help in scheduling cleaning actions to remove the unwanted biofilm, in several application areas, namely in potable water supply pipes.

Experimental Investigation of Compliant Wall Surface Deformation in Turbulent Boundary Layer

NASA Astrophysics Data System (ADS)

Wang, Jin; Agarwal, Karuna; Katz, Joseph

2017-11-01

On-going research integrates Tomographic PIV (TPIV) with Mach-Zehnder Interferometry (MZI) to measure the correlations between deformation of a compliant wall and a turbulent channel flow or a boundary layer. Aiming to extend the scope to two-way coupling, in the present experiment the wall properties have been designed, based on a theoretical analysis, to increase the amplitude of deformation to several μm, achieving the same order of magnitude as the boundary layer wall unit (5-10 μm). It requires higher speeds and a softer surface that has a Young's modulus of 0.1MPa (vs. 1Mpa before), as well as proper thickness (5 mm) that maximize the wall response to excitation at scales that fall within the temporal and spatial resolution of the instruments. The experiments are performed in a water tunnel extension to the JHU refractive index matched facility. The transparent compliant surface is made of PDMS molded on the tunnel window, and measurements are performed at friction velocity Reynolds numbers in the 1000-7000 range. MZI measures the 2D surface deformation as several magnifications. The time-resolved 3D pressure distribution is determined by calculating to spatial distribution of material acceleration from the TPIV data and integrating it using a GPU-based, parallel-line, omni-directional integration method. ONR.

A Near-Wall Reynolds-Stress Closure without Wall Normals

NASA Technical Reports Server (NTRS)

Yuan, S. P.; So, R. M. C.

1997-01-01

With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on the SSG high-Reynolds-stress model with wall-independent near-wall corrections. Only one damping function is used for flows with a wide range of Reynolds numbers to ensure that the near-wall modifications diminish away from the walls. The model is able to reproduce complicated flow phenomena induced by complex geometry, such as flow recirculation, reattachment and boundary-layer redevelopment in backward-facing step flow and secondary flow in three-dimensional square duct flow. In simple flows, including fully developed channel/pipe flow, Couette flow and boundary-layer flow, the wall effects are dominant, and the NNWRS model predicts less degree of turbulent anisotropy in the near-wall region compared with a wall-dependent near-wall Reynolds Stress model (NWRS) developed by So and colleagues. The comparison of the predictions given by the two models rectifies the misconception that the overshooting of skin friction coefficient in backward-facing step flow prevalent in those near-wall, models with wall normal is caused by he use of wall normal.

Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

PubMed

Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

2015-01-01

The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

An experimental study of the wall-pressure fluctuations beneath low Reynolds number turbulent boundary layers.

PubMed

Van Blitterswyk, Jared; Rocha, Joana

2017-02-01

A more complete understanding of the physical relationships, between wall-pressure and turbulence, is required for modeling flow-induced noise and developing noise reduction strategies. In this study, the wall-pressure fluctuations, induced by low Reynolds number turbulent boundary layers, are experimentally studied using a high-resolution microphone array. Statistical characteristics obtained using traditional cross-correlation and cross-spectra analyses are complimented with wall-pressure-velocity cross-spectra and wavelet cross-correlations. Wall-pressure-velocity correlations revealed that turbulent activity in the buffer layer contributes at least 40% of the energy to the wall-pressure spectrum at all measured frequencies. As Reynolds number increases, the low-frequency energy shifts from the buffer layer to the logarithmic layer, as expected for regions of uniform streamwise momentum formed by hairpin packets. Conditional cross-spectra suggests that the majority of broadband wall-pressure energy is concentrated within the packets, with the pressure signatures of individual hairpin vortices estimated to decay on average within traveling ten displacement thicknesses, and the packet signature is retained for up to seven boundary layer thicknesses on average.

Cell-wall disruption and lipid/astaxanthin extraction from microalgae: Chlorella and Haematococcus.

PubMed

Kim, Dong-Yeon; Vijayan, Durairaj; Praveenkumar, Ramasamy; Han, Jong-In; Lee, Kyubock; Park, Ji-Yeon; Chang, Won-Seok; Lee, Jin-Suk; Oh, You-Kwan

2016-01-01

Recently, biofuels and nutraceuticals produced from microalgae have emerged as major interests, resulting in intensive research of the microalgal biorefinery process. In this paper, recent developments in cell-wall disruption and extraction methods are reviewed, focusing on lipid and astaxanthin production from the biotechnologically important microalgae Chlorella and Haematococcus, respectively. As a common, critical bottleneck for recovery of intracellular components such as lipid and astaxanthin from these microalgae, the composition and structure of rigid, thick cell-walls were analyzed. Various chemical, physical, physico-chemical, and biological methods applied for cell-wall breakage and lipid/astaxanthin extraction from Chlorella and Haematococcus are discussed in detail and compared based on efficiency, energy consumption, type and dosage of solvent, biomass concentration and status (wet/dried), toxicity, scalability, and synergistic combinations. This report could serve as a useful guide to the implementation of practical downstream processes for recovery of valuable products from microalgae including Chlorella and Haematococcus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hygrothermal Anaylsis of Wood-Frame Wall Assemblies in a Mixed-Humid Climate

Treesearch

Samuel V. Glass

2013-01-01

This study uses a one-dimensional hygrothermal model to investigate the moisture performance of 10 residential wood-frame wall assemblies in a representative mixed-humid climate location of Baltimore, Maryland (climate zone 4A). All the assemblies include oriented strandboard (OSB) sheathing and vinyl siding. The walls differ in stud cavity thickness, level of cavity...

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes/polymer composite thin film.

PubMed

Rajanna, Pramod Mulbagal; Gilshteyn, Evgenia; Yagafarov, Timur; Alekseeva, Alena; Anisimov, Anton; Sergeev, Oleg; Neumueller, Alex; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert

2018-01-09

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and a thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high quality SWCNTs with an enhanced conductivity by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with different SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit Jsc, open-circuit Voc, and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and efficiency of 3.4% under simulated one-sun AM 1.5G direct illumination. © 2018 IOP Publishing Ltd.

Skyrmion domain wall collision and domain wall-gated skyrmion logic

NASA Astrophysics Data System (ADS)

Xing, Xiangjun; Pong, Philip W. T.; Zhou, Yan

2016-08-01

Skyrmions and domain walls are significant spin textures of great technological relevance to magnetic memory and logic applications, where they can be used as carriers of information. The unique topology of skyrmions makes them display emergent dynamical properties as compared with domain walls. Some studies have demonstrated that the two topologically inequivalent magnetic objects could be interconverted by using cleverly designed geometric structures. Here, we numerically address the skyrmion domain wall collision in a magnetic racetrack by introducing relative motion between the two objects based on a specially designed junction. An electric current serves as the driving force that moves a skyrmion toward a trapped domain wall pair. We see different types of collision dynamics depending on the driving parameters. Most importantly, the modulation of skyrmion transport using domain walls is realized in this system, allowing a set of domain wall-gated logical NOT, NAND, and NOR gates to be constructed. This work provides a skyrmion-based spin-logic architecture that is fully compatible with racetrack memories.

Application of Pressure-Based Wall Correction Methods to Two NASA Langley Wind Tunnels

NASA Technical Reports Server (NTRS)

Iyer, V.; Everhart, J. L.

2001-01-01

This paper is a description and status report on the implementation and application of the WICS wall interference method to the National Transonic Facility (NTF) and the 14 x 22-ft subsonic wind tunnel at the NASA Langley Research Center. The method calculates free-air corrections to the measured parameters and aerodynamic coefficients for full span and semispan models when the tunnels are in the solid-wall configuration. From a data quality point of view, these corrections remove predictable bias errors in the measurement due to the presence of the tunnel walls. At the NTF, the method is operational in the off-line and on-line modes, with three tests already computed for wall corrections. At the 14 x 22-ft tunnel, initial implementation has been done based on a test on a full span wing. This facility is currently scheduled for an upgrade to its wall pressure measurement system. With the addition of new wall orifices and other instrumentation upgrades, a significant improvement in the wall correction accuracy is expected.

A Near-Wall Reynolds-Stress Closure Without Wall Normals

NASA Technical Reports Server (NTRS)

Yuan, S. P.; So, R. M. C.

1997-01-01

Turbulent wall-bounded complex flows are commonly encountered in engineering practice and are of considerable interest in a variety of industrial applications. The presence of a wall significantly affects turbulence characteristics. In addition to the wall effects, turbulent wall-bounded flows become more complicated by the presence of additional body forces (e.g. centrifugal force and Coriolis force) and complex geometry. Most near-wall Reynolds stress models are developed from a high-Reynolds-number model which assumes turbulence is homogenous (or quasi-homogenous). Near-wall modifications are proposed to include wall effects in near-wall regions. In this process, wall normals are introduced. Good predictions could be obtained by Reynolds stress models with wall normals. However, ambiguity arises when the models are applied in flows with multiple walls. Many models have been proposed to model turbulent flows. Among them, Reynolds stress models, in which turbulent stresses are obtained by solving the Reynolds stress transport equations, have been proved to be the most successful ones. To apply the Reynolds stress models to wall-bounded flows, near-wall corrections accounting for the wall effects are needed, and the resulting models are called near-wall Reynolds stress models. In most of the existing near-wall models, the near-wall corrections invoke wall normals. These wall-dependent near-wall models are difficult to implement for turbulent flows with complex geometry and may give inaccurate predictions due to the ambiguity of wall normals at corners connecting multiple walls. The objective of this study is to develop a more general and flexible near-wall Reynolds stress model without using any wall-dependent variable for wall-bounded turbulent flows. With the aid of near-wall asymptotic analysis and results of direct numerical simulation, a new near-wall Reynolds stress model (NNWRS) is formulated based on Speziale et al.'s high-Reynolds-stress model with wall

Revision of orthovoltage chest wall treatment using Monte Carlo simulations.

PubMed

Zeinali-Rafsanjani, B; Faghihi, R; Mosleh-Shirazi, M A; Mosalaei, A; Hadad, K

2017-01-01

Given the high local control rates observed in breast cancer patients undergoing chest wall irradiation by kilovoltage x-rays, we aimed to revisit this treatment modality by accurate calculation of dose distributions using Monte Carlo simulation. The machine components were simulated using the MCNPX code. This model was used to assess the dose distribution of chest wall kilovoltage treatment in different chest wall thicknesses and larger contour or fat patients in standard and mid sternum treatment plans. Assessments were performed at 50 and 100 cm focus surface distance (FSD) and different irradiation angles. In order to evaluate different plans, indices like homogeneity index, conformity index, the average dose of heart, lung, left anterior descending artery (LAD) and percentage target coverage (PTC) were used. Finally, the results were compared with the indices provided by electron therapy which is a more routine treatment of chest wall. These indices in a medium chest wall thickness in standard treatment plan at 50 cm FSD and 15 degrees tube angle was as follows: homogeneity index 2.57, conformity index 7.31, average target dose 27.43 Gy, average dose of heart, lung and LAD, 1.03, 2.08 and 1.60 Gy respectively and PTC 11.19%. Assessments revealed that dose homogeneity in planning target volume (PTV) and conformity between the high dose region and PTV was poor. To improve the treatment indices, the reference point was transferred from the chest wall skin surface to the center of PTV. The indices changed as follows: conformity index 7.31, average target dose 60.19 Gy, the average dose of heart, lung and LAD, 3.57, 6.38 and 5.05 Gy respectively and PTC 55.24%. Coverage index of electron therapy was 89% while it was 22.74% in the old orthovoltage method and also the average dose of the target was about 50 Gy but in the given method it was almost 30 Gy. The results of the treatment study show that the optimized standard and mid sternum treatment for different chest

The relation of apple texture with cell wall nanostructure studied using an atomic force microscope.

PubMed

Cybulska, Justyna; Zdunek, Artur; Psonka-Antonczyk, Katarzyna M; Stokke, Bjørn T

2013-01-30

In this study, the relation of the nanostructure of cell walls with their texture was investigated for six different apple cultivars. Cell wall material (CWM) and cellulose microfibrils were imaged by atomic force microscope (AFM). The mean diameter of cellulose microfibrils for each cultivar was estimated based on the AFM height topographs obtained using the tapping mode of dried specimens. Additionally, crystallinity of cellulose microfibrils and pectin content was determined. Texture of apple cultivars was evaluated by sensory and instrumental analysis. Differences in cellulose diameter as determined from the AFM height topographs of the nanostructure of cell walls of the apple cultivars are found to relate to the degree of crystallinity and pectin content. Cultivars with thicker cellulose microfibrils also revealed crisper, harder and juicier texture, and greater acoustic emission. The data suggest that microfibril thickness affects the mechanical strength of cell walls which has consequences for sensory and instrumental texture. Copyright © 2012 Elsevier Ltd. All rights reserved.

Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

NASA Astrophysics Data System (ADS)

Jiang, Jun; Bai, Zi Long; Chen, Zhi Hui; He, Long; Zhang, David Wei; Zhang, Qing Hua; Shi, Jin An; Park, Min Hyuk; Scott, James F.; Hwang, Cheol Seong; Jiang, An Quan

2018-01-01

Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

Characterization of Kerfless Linear Arrays Based on PZT Thick Film.

PubMed

Zawada, Tomasz; Bierregaard, Louise Moller; Ringgaard, Erling; Xu, Ruichao; Guizzetti, Michele; Levassort, Franck; Certon, Dominique

2017-09-01

Multielement transducers enabling novel cost-effective fabrication of imaging arrays for medical applications have been presented earlier. Due to the favorable low lateral coupling of the screen-printed PZT, the elements can be defined by the top electrode pattern only, leading to a kerfless design with low crosstalk between the elements. The thick-film-based linear arrays have proved to be compatible with a commercial ultrasonic scanner and to support linear array beamforming as well as phased array beamforming. The main objective of the presented work is to investigate the performance of the devices at the transducer level by extensive measurements of the test structures. The arrays have been characterized by several different measurement techniques. First, electrical impedance measurements on several elements in air and liquid have been conducted in order to support material parameter identification using the Krimholtz-Leedom-Matthaei model. It has been found that electromechanical coupling is at the level of 35%. The arrays have also been characterized by a pulse-echo system. The measured sensitivity is around -60 dB, and the fractional bandwidth is close to 60%, while the center frequency is about 12 MHz over the whole array. Finally, laser interferometry measurements have been conducted indicating very good displacement level as well as pressure. The in-depth characterization of the array structure has given insight into the performance parameters for the array based on PZT thick film, and the obtained information will be used to optimize the key parameters for the next generation of cost-effective arrays based on piezoelectric thick film.

Estimation of soft sediment thickness in Kuala Lumpur based on microtremor observation data

NASA Astrophysics Data System (ADS)

Chiew, Chang Chyau; Cheah, Yi Ben; Tan, Chin Guan; Lau, Tze Liang

2017-10-01

Seismic site effect is one of the major concerns in earthquake engineering. Soft ground tends to amplify the seismic wave in surficial geological layers. The determination of soft ground thickness on the surface layers of the earth is an important input for seismic hazard assessment. This paper presents an easy and convenient approach to estimate the soft sediment thickness at the site using microtremor observation technique. A total number of 133 survey points were conducted in selected sites around Kuala Lumpur area using a microtremor measuring instrument, but only 103 survey points contributed to the seismic microzonation and sediment thickness plots. The bedrock of Kuala Lumpur area is formed by Kenny Hill Formation, limestone, granite, and the Hawthornden Schist; however, the thickness of surface soft ground formed by alluvial deposits, mine tailings, and residual soils remains unknown. Hence, the predominant frequency of the ground in each site was determined based on Nakamura method. A total number of 14 sites with known depth to bedrock from the supply of geotechnical reports in the study area were determined. An empirical correlation was developed to relate the ground predominant frequency and soft ground thickness. This correlation may contribute to local soil underlying the subsurface of Kuala Lumpur area. The finding provides an important relationship for engineers to estimate the soft ground thickness in Kuala Lumpur area based on the dynamic characteristics of the ground measured from microtremor observation.

Study of noise transmission through double wall aircraft windows

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1983-01-01

Analytical and experimental procedures were used to predict the noise transmitted through double wall windows into the cabin of a twin-engine G/A aircraft. The analytical model was applied to optimize cabin noise through parametric variation of the structural and acoustic parameters. The parametric study includes mass addition, increase in plexiglass thickness, decrease in window size, increase in window cavity depth, depressurization of the space between the two window plates, replacement of the air cavity with a transparent viscoelastic material, change in stiffness of the plexiglass material, and different absorptive materials for the interior walls of the cabin. It was found that increasing the exterior plexiglass thickness and/or decreasing the total window size could achieve the proper amount of noise reduction for this aircraft. The total added weight to the aircraft is then about 25 lbs.

Experimental, numerical, and analytical studies on the seismic response of steel-plate concrete (SC) composite shear walls

NASA Astrophysics Data System (ADS)

Epackachi, Siamak

The seismic performance of rectangular steel-plate concrete (SC) composite shear walls is assessed for application to buildings and mission-critical infrastructure. The SC walls considered in this study were composed of two steel faceplates and infill concrete. The steel faceplates were connected together and to the infill concrete using tie rods and headed studs, respectively. The research focused on the in-plane behavior of flexure- and flexure-shear-critical SC walls. An experimental program was executed in the NEES laboratory at the University at Buffalo and was followed by numerical and analytical studies. In the experimental program, four large-size specimens were tested under displacement-controlled cyclic loading. The design variables considered in the testing program included wall thickness, reinforcement ratio, and slenderness ratio. The aspect ratio (height-to-length) of the four walls was 1.0. Each SC wall was installed on top of a re-usable foundation block. A bolted baseplate to RC foundation connection was used for all four walls. The walls were identified to be flexure- and flexure-shear critical. The progression of damage in the four walls was identical, namely, cracking and crushing of the infill concrete at the toes of the walls, outward buckling and yielding of the steel faceplates near the base of the wall, and tearing of the faceplates at their junctions with the baseplate. A robust finite element model was developed in LS-DYNA for nonlinear cyclic analysis of the flexure- and flexure-shear-critical SC walls. The DYNA model was validated using the results of the cyclic tests of the four SC walls. The validated and benchmarked models were then used to conduct a parametric study, which investigated the effects of wall aspect ratio, reinforcement ratio, wall thickness, and uniaxial concrete compressive strength on the in-plane response of SC walls. Simplified analytical models, suitable for preliminary analysis and design of SC walls, were

Thickness optimization of auricular silicone scaffold based on finite element analysis.

PubMed

Jiang, Tao; Shang, Jianzhong; Tang, Li; Wang, Zhuo

2016-01-01

An optimized thickness of a transplantable auricular silicone scaffold was researched. The original image data were acquired from CT scans, and reverse modeling technology was used to build a digital 3D model of an auricle. The transplant process was simulated in ANSYS Workbench by finite element analysis (FEA), solid scaffolds were manufactured based on the FEA results, and the transplantable artificial auricle was finally obtained with an optimized thickness, as well as sufficient intensity and hardness. This paper provides a reference for clinical transplant surgery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spaceflight Affects Postnatal Development of the Aortic Wall in Rats

PubMed Central

Yamasaki, Masao; Waki, Hidefumi; Miyake, Masao; Nagayama, Tadanori; Miyamoto, Yukako; Wago, Haruyuki; Okouchi, Toshiyasu; Shimizu, Tsuyoshi

2014-01-01

We investigated effect of microgravity environment during spaceflight on postnatal development of the rheological properties of the aorta in rats. The neonate rats were randomly divided at 7 days of age into the spaceflight, asynchronous ground control, and vivarium control groups (8 pups for one dam). The spaceflight group rats at 9 days of age were exposed to microgravity environment for 16 days. A longitudinal wall strip of the proximal descending thoracic aorta was subjected to stress-strain and stress-relaxation tests. Wall tensile force was significantly smaller in the spaceflight group than in the two control groups, whereas there were no significant differences in wall stress or incremental elastic modulus at each strain among the three groups. Wall thickness and number of smooth muscle fibers were significantly smaller in the spaceflight group than in the two control groups, but there were no significant differences in amounts of either the elastin or collagen fibers among the three groups. The decreased thickness was mainly caused by the decreased number of smooth muscle cells. Plastic deformation was observed only in the spaceflight group in the stress-strain test. A microgravity environment during spaceflight could affect postnatal development of the morphological and rheological properties of the aorta. PMID:25210713

Three-dimensional analysis of alveolar wall destruction in the early stage of pulmonary emphysema.

PubMed

Kobayashi, Yukihiro; Uehara, Takeshi; Kawasaki, Kenji; Sugano, Mitsutoshi; Matsumoto, Takehisa; Matsumoto, Gou; Honda, Takayuki

2015-03-01

The morphological mechanism of alveolar wall destruction during pulmonary emphysema has not been clarified. The aim of this study was to elucidate this process three-dimensionally. Lung specimens from five patients with pulmonary emphysema were used, and five controls with normal alveolar structure were also examined. Sections 150 μm thick were stained with hematoxylin and eosin, elastica, and silver impregnation, and immunostained with selected antibodies. We examined these sections three-dimensionally using a laser confocal microscope and a light microscope. There were only a few Kohn's pores and no fenestrae in the normal alveoli from the controls. In the lungs of the emphysema patients a small rupture appeared in the extremely thin alveolar wall among the alveolar capillaries. This rupture enlarged to form a circle surrounded by the capillaries, which was called an alveolar fenestra. Two neighboring fenestrae fused by breakdown of the collapsed or cord-like capillary between them to form a large fenestra. The large fenestrae fused repeatedly to become larger, and these were bordered by thick elastic fibers constructing an alveolar framework. Alveolar wall destruction during emphysema could start from small ruptures of the alveolar wall that become fenestrae surrounded by capillaries, which fuse repeatedly to become larger fenestrae rimmed with elastic fibers. The alveolar capillary network could initially prevent enlargement of the fenestrae, and the thick elastic fibers constituting the alveolar framework could secondarily prevent destruction of the alveolar wall structure. © 2014 Wiley Periodicals, Inc.

Elastohydrodynamic film thickness formula based on X-ray measurements with a synthetic paraffinic oil

NASA Technical Reports Server (NTRS)

Loewenthal, S. H.; Parker, R. J.; Zaretsky, E. V.

1973-01-01

An empirical elastohydrodynamic film thickness formula for heavily loaded contacts based upon X-ray film thickness measurements made with a synthetic paraffinic oil is presented. The deduced relation was found to adequately reflect the high load dependence exhibited by the measured minimum film thickness data at high Hertizian contact stresses, that is, above 1.04 x 10 to the ninth N/sq m (150,000 psi). Comparisons were made with the numerical results from a theoretical isothermal film thickness formula. The effects of changes in contact geometry, material, and lubricant properties on the form of the empirical model are also discussed.

Comparison of lateral abdominal muscle thickness between weightlifters and matched controls.

PubMed

Sitilertpisan, Patraporn; Pirunsan, Ubon; Puangmali, Aatit; Ratanapinunchai, Jonjin; Kiatwattanacharoen, Suchart; Neamin, Hudsaleark; Laskin, James J

2011-11-01

To compare lateral abdominal muscle thickness between weightlifters and matched controls. A case control study design. University laboratory. 16 female Thai national weightlifters and 16 matched controls participated in this study. Ultrasound imaging with a 12-MHz linear array was used to measure the resting thickness of transversus abdominis (TrA), internal oblique (IO) and total thickness (Total) of lateral abdominal muscle (LAM) on the right side of abdominal wall. The absolute muscle thickness and the relative contribution of each muscle to the total thickness were determined. Weightlifters had significantly thicker absolute TrA and IO muscles than matched controls (p < 0.01). Further, the relative thickness of the IO was significantly greater in weightlifters than matched controls (p < 0.05). The findings of this study suggest that routine Olympic style weight training among female weightlifters appears to result in preferential hypertrophy or adaptation of the IO muscle. Copyright © 2011 Elsevier Ltd. All rights reserved.

13. LONG WEST WALL (LEFT) AND SHORT SOUTH WALL (RIGHT) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. LONG WEST WALL (LEFT) AND SHORT SOUTH WALL (RIGHT) OF AR-9, ALSO SHOWING MORE RECENT CONTROL ROOM BUILDING AT RIGHT. VIEW IS TO THE NORTHEAST. - Edwards Air Force Base, South Base, Rammed Earth Aircraft Dispersal Revetments, Western Shore of Rogers Dry Lake, Boron, Kern County, CA

Responses of retaining wall and surrounding ground to pre-excavation dewatering in an alternated multi-aquifer-aquitard system

NASA Astrophysics Data System (ADS)

Zeng, Chao-Feng; Xue, Xiu-Li; Zheng, Gang; Xue, Teng-Yun; Mei, Guo-Xiong

2018-04-01

Pre-excavation dewatering (PED) is an important construction stage in deep excavation. Field measurements show that retaining walls can develop obvious deflections during PED, which has been rarely considered in the past. The characteristics of PED-induced wall deflection, and the relationship of this deflection to surrounding ground deformation are still unclear. In this study, a PED test is simulated by a numerical model. The model is verified by field observations and used to investigate the responses of retaining wall and surrounding ground to PED. Results indicate that the maximum wall defection (δhm) and surface settlement (δvm) can all reach centimeter level under common conditions of PED. The ratio of δvm to δhm varies at the range of 0.45-0.67. Wall and soil deformations will be more obvious if the soils within the dewatering depth (Hd) have better permeability. The relative positions between Hd and strata (i.e., aquifer or aquitard) have great influence on the PED-induced deformations. If an aquifer appears below Hd, further increasing Hd can induce a rapid growth of wall and soil deformations. If thick aquitard appears below Hd, the deformation increments by further increasing Hd are not apparent. However, once Hd exceeds the center of the thick aquitard and reaches a thick confined aquifer, the wall deflections and soil deformation zones behind the wall will enlarge significantly. Meanwhile, a large bending moment in the retaining wall will arise around the bottom of the confined aquifer. The designers should consider this condition and allocate enough steel rebars there, preventing the appearance of wall cracks in the confined aquifer.

The rollup of a vortex layer near a wall

NASA Technical Reports Server (NTRS)

Jimenez, Javier; Orlandi, Paolo

1993-01-01

The behavior of an inviscid vortex layer of non-zero thickness near a wall is studied, both through direct numerical simulation of the two-dimensional vorticity equation at high Reynolds numbers, and using an approximate ordinary nonlinear integro-differential equation which is satisfied in the limit of a thin layer under long-wavelength perturbations. For appropriate initial conditions the layer rolls up and breaks into compact vortices which move along the wall at constant speed. Because of the effect of the wall, they correspond to equilibrium counter-rotating vortex dipoles. This breakup can be related to the disintegration of the initial conditions of the approximate nonlinear dispersive equation into solitary waves. The study is motivated by the formation of longitudinal vortices from vortex sheets in the wall region of a turbulent channel.

Phenotype-Based Screening of Small Molecules to Modify Plant Cell Walls Using BY-2 Cells.

PubMed

Okubo-Kurihara, Emiko; Matsui, Minami

2018-01-01

The plant cell wall is an important and abundant biomass with great potential for use as a modern recyclable resource. For effective utilization of this cellulosic biomass, its ability to degrade efficiently is key point. With the aim of modifying the cell wall to allow easy decomposition, we used chemical biological technology to alter its structure. As a first step toward evaluating the chemicals in the cell wall we employed a phenotype-based approach using high-throughput screening. As the plant cell wall is essential in determining cell morphology, phenotype-based screening is particularly effective in identifying compounds that bring about alterations in the cell wall. For rapid and reproducible screening, tobacco BY-2 cell is an excellent system in which to observe cell morphology. In this chapter, we provide a detailed chemical biological methodology for studying cell morphology using tobacco BY-2 cells.

Virtual wall-based haptic-guided teleoperated surgical robotic system for single-port brain tumor removal surgery.

PubMed

Seung, Sungmin; Choi, Hongseok; Jang, Jongseong; Kim, Young Soo; Park, Jong-Oh; Park, Sukho; Ko, Seong Young

2017-01-01

This article presents a haptic-guided teleoperation for a tumor removal surgical robotic system, so-called a SIROMAN system. The system was developed in our previous work to make it possible to access tumor tissue, even those that seat deeply inside the brain, and to remove the tissue with full maneuverability. For a safe and accurate operation to remove only tumor tissue completely while minimizing damage to the normal tissue, a virtual wall-based haptic guidance together with a medical image-guided control is proposed and developed. The virtual wall is extracted from preoperative medical images, and the robot is controlled to restrict its motion within the virtual wall using haptic feedback. Coordinate transformation between sub-systems, a collision detection algorithm, and a haptic-guided teleoperation using a virtual wall are described in the context of using SIROMAN. A series of experiments using a simplified virtual wall are performed to evaluate the performance of virtual wall-based haptic-guided teleoperation. With haptic guidance, the accuracy of the robotic manipulator's trajectory is improved by 57% compared to one without. The tissue removal performance is also improved by 21% ( p < 0.05). The experiments show that virtual wall-based haptic guidance provides safer and more accurate tissue removal for single-port brain surgery.

Comparative evaluation of physicians' pulmonary nodule detection with reduced slice thickness at CT screening

NASA Astrophysics Data System (ADS)

Sinsuat, Marodina; Shimamura, Ichiro; Saita, Shinsuke; Kubo, Mitsuru; Kawata, Yoshiki; Niki, Noboru; Ohmatsu, Hironobu; Kakinuma, Ryutaro; Eguchi, Kenji; Kaneko, Masahiro; Tominaga, Keigo; Moriyama, Noriyuki

2008-03-01

With thin and thick section Multi-slice CT images at lung cancer screening, we have statistically and quantitatively shown and evaluated the diagnostic capabilities of these slice thicknesses on physicians' pulmonary nodule diagnosis. To comparatively evaluate the 2 mm and 10 mm slice thicknesses, MSCT images of 360 people were read by six physicians. The reading criteria consisted of nodule for further examination (NFE), nodule for no further examination (NNFE) and no abnormality (NA) case. For reading results evaluation; firstly, cross-tabulation was carried out to roughly analyze the diagnoses based on whole lung field and each lung lobes. Secondly, from semi-automated extraction result of the nodule, detailed quantitative analysis was carried out to determine the diagnostic capabilities of two slice thicknesses. Finally, using the reading results of 2 mm thick image as the gold standard, the diagnostic capabilities were analyzed through the features and locations of pulmonary nodules. The study revealed that both slice thicknesses can depict lung cancer. Thin section may not be effective to diagnose nodules of <=3 mm in size and nodules of <= 5mm in size for thick section. Though thick section is less tiring for reading physicians, it is not good at depicting nodules located at the border of lung upper lobe and which have a pixel size distance of <=5 from the chest wall. The information presented may serve as a useful reference to determine in which particular pulmonary nodule condition the two slice thicknesses can be effectively used for early detection of lung cancer.

Fabrication of single/multi-walled hybrid buckypaper composites and their enhancement of electromagnetic interference shielding performance

NASA Astrophysics Data System (ADS)

Lu, Shaowei; Shao, Junyan; Ma, Keming; Wang, Xiaoqiang; Zhang, Lu; Meng, Qingshi

2016-11-01

Multi-walled carbon nanotubes and single-walled carbon nanotubes show great potential for the application as an electromagnetic interference shielding material. In this paper, the electromagnetic interference shielding the effectiveness of a composite surface coated single/multi-walled carbon nanotube hybrid buckypaper was measured, which showed an average shielding effectiveness of ~55 dB with a buckypaper thickness of 50 µm, and bukypaper density of 0.76 g cm-3, it is much higher than other carbon nanotube/resin materials when sample thickness is on the similar order. The structural, specific surface area and conductivity of the buckypapers were examined by field-emission scanning electron microscopy, specific surface area analyzer and four probes resistance tester, respectively.

A Reynolds stress model for near-wall turbulence

NASA Technical Reports Server (NTRS)

Durbin, P. A.

1993-01-01

The paper formulates a tensorially consistent near-wall second-order closure model. Redistributive terms in the Reynolds stress equations are modeled by an elliptic relaxation equation in order to represent strongly nonhomogeneous effects produced by the presence of walls; this replaces the quasi-homogeneous algebraic models that are usually employed, and avoids the need for ad hoc damping functions. The model is solved for channel flow and boundary layers with zero and adverse pressure gradients. Good predictions of Reynolds stress components, mean flow, skin friction, and displacement thickness are obtained in various comparisons to experimental and direct numerical simulation data. The model is also applied to a boundary layer flowing along a wall with a 90-deg, constant-radius, convex bend.

Large scale structures in a turbulent boundary layer and their imprint on wall shear stress

NASA Astrophysics Data System (ADS)

Pabon, Rommel; Barnard, Casey; Ukeiley, Lawrence; Sheplak, Mark

2015-11-01

Experiments were performed on a turbulent boundary layer developing on a flat plate model under zero pressure gradient flow. A MEMS differential capacitive shear stress sensor with a 1 mm × 1 mm floating element was used to capture the fluctuating wall shear stress simultaneously with streamwise velocity measurements from a hot-wire anemometer traversed in the wall normal direction. Near the wall, the peak in the cross correlation corresponds to an organized motion inclined 45° from the wall. In the outer region, the peak diminishes in value, but is still significant at a distance greater than half the boundary layer thickness, and corresponds to a structure inclined 14° from the wall. High coherence between the two signals was found for the low-frequency content, reinforcing the belief that large scale structures have a vital impact on wall shear stress. Thus, estimation of the wall shear stress from the low-frequency velocity signal will be performed, and is expected to be statistically significant in the outer boundary layer. Additionally, conditionally averaged mean velocity profiles will be presented to assess the effects of high and low shear stress. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.

Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption

PubMed Central

Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

2015-01-01

The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry. PMID:26295574

Changes in optical coherence tomography measurements after orbital wall decompression in dysthyroid optic neuropathy.

PubMed

Park, Kyung-Ah; Kim, Yoon-Duck; Woo, Kyung In

2018-06-01

The purpose of our study was to assess changes in peripapillary retinal nerve fiber layer (RNFL) thickness after orbital wall decompression in eyes with dysthyroid optic neuropathy (DON). We analyzed peripapillary optical coherence tomography (OCT) images (Cirrus HD-OCT) from controls and patients with DON before and 1 and 6 months after orbital wall decompression. There was no significant difference in mean preoperative peripapillary retinal nerve fiber layer thickness between eyes with DON and controls. The superior and inferior peripapillary RNFL thickness decreased significantly 1 month after decompression surgery compared to preoperative values (p = 0.043 and p = 0.022, respectively). The global average, superior, temporal, and inferior peripapillary RNFL thickness decreased significantly 6 months after decompression surgery compared to preoperative values (p = 0.015, p = 0.028, p = 0.009, and p = 0.006, respectively). Patients with greater preoperative inferior peripapillary RNFL thickness tended to have better postoperative visual acuity at the last visit (p = 0.024, OR = 0.926). Our data revealed a significant decrease in peripapillary RNFL thickness postoperatively after orbital decompression surgery in patients with DON. We also found that greater preoperative inferior peripapillary RNFL thickness was associated with better visual outcomes. We suggest that RNFL thickness can be used as a prognostic factor for DON before decompression surgery.

Correlating Abdominal Wall Thickness and Body Mass Index to Predict Usefulness of Right Lower Quadrant Ultrasound for Evaluation of Pediatric Appendicitis.

PubMed

Kwon, Jeannie K; Trexler, Nowice; Reisch, Joan; Pfeifer, Cory M; Ginos, Jason; Powell, Jerry Allen; Veltkamp, Jennifer; Anene, Alvin; Fernandes, Neil; Chen, Li Ern

2017-11-06

To inform selective and efficient use of appendix ultrasound (US) beyond adult parameters of body mass index (BMI) of less than 25 kg/m, we correlate abdominal wall thickness (AWT) with age and BMI to generate parameters for male and female children. Information presented in chart format can aid in the decision to utilize US for the evaluation of appendicitis. In this observational study, 1600 pediatric computed tomography scans of the abdomen and pelvis were analyzed to obtain measurements of AWT in the right lower quadrant. Measurements were correlated by patient age, BMI, and sex. Results and consensus-based recommendations were presented in chart format with color-coded groupings to allow for convenient referencing in the clinical setting. One thousand four hundred eighty-eight computed tomography scans and AWT measurements were included. All age groups with BMI of less than 25 kg/m and all male and female groups younger than 6 years regardless of BMI had median AWT of less than 4 cm resulting in strong recommendation for US. Males older than 6 years and all female age groups with BMI of greater than 30 kg/m and female older than 15 years and BMI of greater than 25 kg/m had AWT of more than 5 cm resulting in low recommendation for US. While the BMI cutoff standard of less than 25 kg/m for usefulness of appendix US holds in the adult population, our data expand the acceptable range in children younger than 9 years regardless of BMI and male children with BMI up to 30 kg/m. Female children younger than 15 years with a BMI up to 30 kg/m may also be amenable to right lower quadrant US based on AWT. These parameters inform selective and efficient use of US for appendix evaluation.

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film.

PubMed

Rajanna, Pramod M; Gilshteyn, Evgenia P; Yagafarov, Timur; Aleekseeva, Alena K; Anisimov, Anton S; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G

2018-01-31

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

Enhanced efficiency of hybrid amorphous silicon solar cells based on single-walled carbon nanotubes and polymer composite thin film

NASA Astrophysics Data System (ADS)

Rajanna, Pramod M.; Gilshteyn, Evgenia P.; Yagafarov, Timur; Aleekseeva, Alena K.; Anisimov, Anton S.; Neumüller, Alex; Sergeev, Oleg; Bereznev, Sergei; Maricheva, Jelena; Nasibulin, Albert G.

2018-03-01

We report a simple approach to fabricate hybrid solar cells (HSCs) based on a single-walled carbon nanotube (SWCNT) film and thin film hydrogenated amorphous silicon (a-Si:H). Randomly oriented high-quality SWCNTs with conductivity enhanced by means of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate are used as a window layer and a front electrode. A series of HSCs are fabricated in ambient conditions with varying SWCNT film thicknesses. The polymethylmethacrylate layer drop-casted on fabricated HSCs reduces the reflection fourfold and enhances the short-circuit J sc , open-circuit V oc , and efficiency by nearly 10%. A state-of-the-art J-V performance is shown for SWCNT/a-Si HSC with an open-circuit voltage of 900 mV and an efficiency of 3.4% under simulated one-sun AM 1.5 G direct illumination.

In-Line Ultrasonic Monitoring for Sediments Stuck on Inner Wall of a Polyvinyl Chloride Pipe

PubMed Central

2014-01-01

This research verified the applicability and effectiveness of the ultrasonic monitoring of sediments stuck on the inner wall of polyvinyl chloride (PVC) pipes. For identifying the transmittance of acoustic energy and the speed of sound in the PVC material, the pulse-echo ultrasonic testing was conducted for PVC sheets of different thicknesses. To simulate the solidified sediment, the hot melt adhesive (HMA) was covered on the inner wall of the PVC pipe in different heights. From the experiment, the speeds of sound in the PVC and the HMA materials were obtained as about 2258 and 2000 m/s, respectively. The thickness of the materials was calculated through the signal processing such as taking the absolute value and low pass filtering, the echo detection, and the measurement of the time of flight. The errors between actual and measured thicknesses of PVC sheets were below 5%. In the case of the substance stuck on the inner wall, the errors were below 2.5%. Since the pulse-echo ultrasonic inspection is available on the outer surface and its measurement accuracy was over 95%, it can be an efficient and effective in-service structural health monitoring for the sediment on the wall of PVC pipes. PMID:25243223

Gender-based analysis of cortical thickness and structural connectivity in Parkinson's disease.

PubMed

Yadav, Santosh K; Kathiresan, Nagarajan; Mohan, Suyash; Vasileiou, Georgia; Singh, Anup; Kaura, Deepak; Melhem, Elias R; Gupta, Rakesh K; Wang, Ena; Marincola, Francesco M; Borthakur, Arijitt; Haris, Mohammad

2016-11-01

Parkinson's disease (PD) is a progressive neurological disorder and appears to have gender-specific symptoms. Studies have observed a higher frequency for development of PD in male than in female. In the current study, we evaluated the gender-based changes in cortical thickness and structural connectivity in PD patients. With informed consent, 64 PD (43 males and 21 females) patients, and 46 (12 males and 34 females) age-matched controls underwent clinical assessment including Mini-Mental State Examination (MMSE) and magnetic resonance imaging on a 1.5 Tesla clinical MR scanner. Whole brain high-resolution T1-weighted images were acquired from all subjects and used to measure cortical thickness and structural network connectivity. No significant difference in MMSE score was observed between male and female both in control and PD subjects. Male PD patients showed significantly reduced cortical thickness in multiple brain regions including frontal, parietal, temporal, and occipital lobes as compared with those in female PD patients. The graph theory-based network analysis depicted lower connection strengths, lower clustering coefficients, and altered network hubs in PD male than in PD female. Male-specific cortical thickness changes and altered connectivity in PD patients may derive from behavioral, physiological, environmental, and genetical differences between male and female, and may have significant implications in diagnosing and treating PD among genders.

Strength Tests on Thin-walled Duralumin Cylinders in Torsion

NASA Technical Reports Server (NTRS)

Lundquist, Eugene E

1932-01-01

This report is the first of a series presenting the results of strength tests on thin-walled cylinders and truncated cones of circular and elliptical section; it comprises the results obtained to date from torsion (pure shear) tests on 65 thin-walled duralumin cylinders of circular section with ends clamped to rigid bulkheads. The effect of variations in the length/radius and radius/thickness ratios on the type of failure is indicated, and a semi-empirical equation for the shearing stress at maximum load is given.

Endoscopic full-thickness resection: Current status

PubMed Central

Schmidt, Arthur; Meier, Benjamin; Caca, Karel

2015-01-01

Conventional endoscopic resection techniques such as endoscopic mucosal resection or endoscopic submucosal dissection are powerful tools for treatment of gastrointestinal neoplasms. However, those techniques are restricted to superficial layers of the gastrointestinal wall. Endoscopic full-thickness resection (EFTR) is an evolving technique, which is just about to enter clinical routine. It is not only a powerful tool for diagnostic tissue acquisition but also has the potential to spare surgical therapy in selected patients. This review will give an overview about current EFTR techniques and devices. PMID:26309354

Endoscopic full-thickness resection: Current status.

PubMed

Schmidt, Arthur; Meier, Benjamin; Caca, Karel

2015-08-21

Conventional endoscopic resection techniques such as endoscopic mucosal resection or endoscopic submucosal dissection are powerful tools for treatment of gastrointestinal neoplasms. However, those techniques are restricted to superficial layers of the gastrointestinal wall. Endoscopic full-thickness resection (EFTR) is an evolving technique, which is just about to enter clinical routine. It is not only a powerful tool for diagnostic tissue acquisition but also has the potential to spare surgical therapy in selected patients. This review will give an overview about current EFTR techniques and devices.

Design optimization of tailor-rolled blank thin-walled structures based on ɛ-support vector regression technique and genetic algorithm

NASA Astrophysics Data System (ADS)

Duan, Libin; Xiao, Ning-cong; Li, Guangyao; Cheng, Aiguo; Chen, Tao

2017-07-01

Tailor-rolled blank thin-walled (TRB-TH) structures have become important vehicle components owing to their advantages of light weight and crashworthiness. The purpose of this article is to provide an efficient lightweight design for improving the energy-absorbing capability of TRB-TH structures under dynamic loading. A finite element (FE) model for TRB-TH structures is established and validated by performing a dynamic axial crash test. Different material properties for individual parts with different thicknesses are considered in the FE model. Then, a multi-objective crashworthiness design of the TRB-TH structure is constructed based on the ɛ-support vector regression (ɛ-SVR) technique and non-dominated sorting genetic algorithm-II. The key parameters (C, ɛ and σ) are optimized to further improve the predictive accuracy of ɛ-SVR under limited sample points. Finally, the technique for order preference by similarity to the ideal solution method is used to rank the solutions in Pareto-optimal frontiers and find the best compromise optima. The results demonstrate that the light weight and crashworthiness performance of the optimized TRB-TH structures are superior to their uniform thickness counterparts. The proposed approach provides useful guidance for designing TRB-TH energy absorbers for vehicle bodies.

Power spectral estimation of high-harmonics in echoes of wall resonances to improve resolution in non-invasive measurements of wall mechanical properties in rubber tube and ex-vivo artery.

PubMed

Bazan, I; Ramos, A; Balay, G; Negreira, C

2018-07-01

The aim of this work is to develop a new type of ultrasonic analysis of the mechanical properties of an arterial wall with improved resolution, and to confirm its feasibility under laboratory conditions. it is expected that this would facilitate a non-invasive path for accurate predictive diagnosis that enables an early detection & therapy of vascular pathologies. In particular, the objective is to detect and quantify the small elasticity changes (in Young's modulus E) of arterial walls, which precede pathology. A submicron axial resolution is required for this analysis, as the periodic widening of the wall (under oscillatory arterial pressure) varies between ±10 and 20 μm. This high resolution represents less than 1% of the parietal thickness (e.g., < 7 μm in carotid arteries). The novelty of our proposal is the new technique used to estimate the modulus E of the arterial walls, which achieves the requisite resolution. It calculates the power spectral evolution associated with the temporal dynamics in higher harmonics of the wall internal resonance f 0 . This was attained via the implementation of an autoregressive parametric algorithm that accurately detects parietal echo-dynamics during a heartbeat. Thus, it was possible to measure the punctual elasticity of the wall, with a higher resolution (> an order of magnitude) compared to conventional approaches. The resolution of a typical ultrasonic image is limited to several hundred microns, and thus, such small changes are undetected. The proposed procedure provides a non-invasive and direct measure of elasticity by doing an estimation of changes in the Nf 0 harmonics and wall thickness with a resolution of 0.1%, for first time. The results obtained by using the classic temporal cross-correlation method (TCC) were compared to those obtained with the new procedure. The latter allowed the evaluation of alterations in the elastic properties of arterial walls that are 30 times smaller than those being

Derivation of the out-of-plane behaviour of an English bond masonry wall through homogenization strategies

NASA Astrophysics Data System (ADS)

Silva, Luís Carlos; Milani, Gabriele; Lourenço, Paulo B.

2017-11-01

Two finite element homogenized-based strategies are presented for the out-of-plane behaviour characterization of an English bond masonry wall. A finite element micro-modelling approach using Cauchy stresses and first order movements are assumed for both strategies. The material nonlinearity is lumped on joints interfaces and bricks are considered elastic. Nevertheless, the first model is based on a Plane-stress assumption, in which the out-of-plane quantities are derived through on-thickness wall integration considering a Kirchhoff-plate theory. The second model is a tridimensional one, in which the homogenized out-of-plane quantities can be directly derived after solving the boundary value problem. The comparison is conducted by assessing the obtained out-of-plane bending- and torsion-curvature diagrams. A good agreement is found for the present study case.

Aqueous-based thick photoresist removal for bumping applications

NASA Astrophysics Data System (ADS)

Moore, John C.; Brewer, Alex J.; Law, Alman; Pettit, Jared M.

2015-03-01

Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

Direct calculation of wall interferences and wall adaptation for two-dimensional flow in wind tunnels with closed walls

NASA Technical Reports Server (NTRS)

Amecke, Juergen

1986-01-01

A method for the direct calculation of the wall induced interference velocity in two dimensional flow based on Cauchy's integral formula was derived. This one-step method allows the calculation of the residual corrections and the required wall adaptation for interference-free flow starting from the wall pressure distribution without any model representation. Demonstrated applications are given.

Carotid artery thickness is associated with chronic use of highly active antiretroviral therapy in patients infected with human immunodeficiency virus: A 3.0 Tesla magnetic resonance imaging study.

PubMed

LaBounty, T M; Hardy, W D; Fan, Z; Yumul, R; Li, D; Dharmakumar, R; Conte, A Hernandez

2016-08-01

While patients with HIV infection have an elevated stroke risk, ultrasound studies of carotid artery wall thickness have reported variable results. We hypothesized that subjects with HIV infection on chronic highly active antiretroviral therapy (HAART) would have increased carotid artery wall thickness by magnetic resonance imaging (MRI). This cross-sectional study compared carotid artery wall thickness between 26 individuals infected with HIV on chronic HAART and 20 controls, without HIV infection but with similar cardiovascular risk factors, using 3.0-T noncontrast MRI. Inclusion criteria included male gender, age 35-55 years, and chronic HAART (≥ 3 years) among HIV-seropositive subjects; those with known cardiovascular disease or diabetes were excluded. Between subjects with HIV infection and controls, there were no differences in mean (±SD) age (47.8 ± 5.0 vs. 47.8 ± 4.7 years, respectively; P = 0.19) or cardiovascular risk factors (P > 0.05 for each). Mean (±SD) wall thickness was increased in those with HIV infection vs. controls for the left (0.88 ± 0.08 vs. 0.83 ± 0.08 mm, respectively; P = 0.03) and right (0.90 ± 0.10 vs. 0.85 ± 0.07 mm, respectively; P = 0.046) common carotid arteries. Among individuals with HIV infection, variables associated with increased mean carotid artery wall thickness included lipoaccumulation [+0.09 mm; 95% confidence interval (CI) 0.03-0.14 mm; P = 0.003], Framingham risk score ≥ 5% (+0.07 mm; 95% CI 0.01-0.12; P = 0.02 mm), and increased duration of protease inhibitor therapy (+0.03 mm per 5 years; 95% CI 0.01-0.06 mm; P = 0.02). Individuals with HIV infection on chronic HAART had increased carotid artery wall thickness as compared to similar controls. In subjects with HIV infection, the presence of lipoaccumulation and longer duration of protease inhibitor therapy were associated with greater wall thickness. © 2015 British HIV Association.

On the three-dimensional instability of laminar boundary layers on concave walls

NASA Technical Reports Server (NTRS)

Gortler, Henry

1954-01-01

A study is made of the stability of laminar boundary-layer profiles on slightly curved walls relative to small disturbances that result from vortices whose axes are parallel to the principal direction of flow. The result is an eigenvalue problem by which, for a given undisturbed flow at a prescribed wall, the amplification or decay is computed for each Reynolds number and each vortex thickness. For neutral disturbances (zero amplification) a critical Reynolds number is determined for each vortex distribution. The numerical calculation produces amplified disturbances on concave walls only.

Highly efficient nonrigid motion‐corrected 3D whole‐heart coronary vessel wall imaging

PubMed Central

Atkinson, David; Henningsson, Markus; Botnar, Rene M.; Prieto, Claudia

2016-01-01

Purpose To develop a respiratory motion correction framework to accelerate free‐breathing three‐dimensional (3D) whole‐heart coronary lumen and coronary vessel wall MRI. Methods We developed a 3D flow‐independent approach for vessel wall imaging based on the subtraction of data with and without T2‐preparation prepulses acquired interleaved with image navigators. The proposed method corrects both datasets to the same respiratory position using beat‐to‐beat translation and bin‐to‐bin nonrigid corrections, producing coregistered, motion‐corrected coronary lumen and coronary vessel wall images. The proposed method was studied in 10 healthy subjects and was compared with beat‐to‐beat translational correction (TC) and no motion correction for the left and right coronary arteries. Additionally, the coronary lumen images were compared with a 6‐mm diaphragmatic navigator gated and tracked scan. Results No significant differences (P > 0.01) were found between the proposed method and the gated and tracked scan for coronary lumen, despite an average improvement in scan efficiency to 96% from 59%. Significant differences (P < 0.01) were found in right coronary artery vessel wall thickness, right coronary artery vessel wall sharpness, and vessel wall visual score between the proposed method and TC. Conclusion The feasibility of a highly efficient motion correction framework for simultaneous whole‐heart coronary lumen and vessel wall has been demonstrated. Magn Reson Med 77:1894–1908, 2017. © 2016 International Society for Magnetic Resonance in Medicine PMID:27221073

Full-Thickness Reconstruction with Pedicle Flap and Diced Homologous Cartilage Over the Pericardium Complicated. Cardiac Arrest

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

Rees, Thomas D.

1961-01-01

Successful repair by plastic surgery of nonhealing ulceration of the chest wall, induced by radiotherapy for breast cancer, is described. Reconstruction of the chest wali defect by pedicle flap coverage was carried out. Radiation injury extended through the entire thickness of the chest wall and osteoradionecrosis of the ribs was present. Reconstruction with thoracoabdominal tube was considered to be the best technique, so a 4- by 9-in. tube pedicle was constructed. The underlying donor wound of the pedicle was covered with a split- thickness skin graft. Healing was without incident, and approximates 3 weeks after formation, the inferior end ofmore » this tube pedicle was migrated to the left epigastrium as an intermediate step. Healing was uncomplicated, and the lateral attachment of the pedicle was partially severed. Three weeks later, resection of all avascular tissue along with portions of the fourth and fifth ribs was carried out. This created a full-thickness chest wall defect measuring 4 by 8 in., with the anterior surface of the pericardial sac exposed in the wound. The end of the abdominal tube pedicle was elevated from its bed, rotated into position, and sutured to the healthy margins of the chest wall defect. The exposed subcutaneous fat of the undersurface of the pedicle was placed in juxtaposition to the pericardium. A split-thickness skin graft was cut from the skin of the left thigh and draped over the pedicle flap donor wound. All sutured wounds healed per primum and the entire skin graft survived. The inferior inset of the tube pedicle was cut free and the pedicle flap was tailored into position 6 weeks later. The patient was discharged from the hospital in good condition and engaged in normal activities. An attempt was made to provide protection for the heart beneath the pedicle inset by introduction of diced homologous cartilage grafts, just beneath the skin of the pedicle flap. This healed with the formation of a thick fibrocartilaginous

Current-induced domain wall motion in permalloy nanowires with a rectangular cross-section

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

Ai, J. H.; Miao, B. F.; Sun, L.

2011-11-01

We performed micromagnetic simulations of the current-induced domain wall motion in permalloy nanowires with rectangular cross-section. In the absence of the nonadiabatic spin-transfer term, a threshold current, J{sub c} is required to drive the domain wall moving continuously. We find that J{sub c} is proportional to the maximum cross product of the demagnetization field and magnetization orientation of the domain wall and the domain wall width. With varying both the wire thickness and width, a minimum threshold current in the order of 10{sup 6} A/cm{sup 2} is obtained when the thickness is equivalent to the wire width. With the nonadiabaticmore » spin-transfer term, the calculated domain wall velocity {nu} equals to the adiabatic spin transfer velocity u when the current is far above the Walker limit J{sub w}. Below J{sub w}, {nu}=({beta}/{alpha})u, where {beta} is the nonadiabatic parameter and {alpha} is the damping factor. For different {beta}, we find the Walker limit can be scaled as J{sub w}=({alpha}/{beta}-{alpha})J{sub c}. Our simulations agree well with the one dimensional analytical calculation, suggesting the findings are the general behaviors of the systems in this particular geometry.« less

Gortler vortices and transition in wall boundary layers of two Mach 5 nozzles

NASA Technical Reports Server (NTRS)

Beckwith, I. E.; Holley, B. B.

1981-01-01

The onset of transition in the wall boundary layers of two axisymmetric Mach 5 wind-tunnel nozzles has been measured under conditions of extremely low incident disturbance levels. The range of test unit Reynolds numbers, based on conditions at the nozzle exit, was from 6 x 10 to the 6th power m to 2.5 x 10 to the 7th power m. When the nozzle walls were maintained in a polished and clean condition, transition moved gradually upstream as the test Reynolds number was increased. When transition occurred in the supersonic concave wall region, the values of the local Gortler parameter at transition varied from about 5 to 6, whereas the momentum thickness Reynolds number varied from about 750 to 1050. Oil flow patterns obtained near the exit of the nozzles indicated that Gortler vortices were always present when the wall boundary layers were laminar. Calculations for the growth of Gortler vortices based on new results from linear theory for supersonic flat-plate profiles gave amplification ratios to transition from e to the 4th power to e to the 15th power. Possible reasons for this wide range in amplification ratios are discussed, but no definite conclusions are yet possible regarding the values of n in a simple e to the nth power type theory for the assumed linear amplification of Gortler vortices to transition in supersonic nozzles.

[The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

PubMed

Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

2015-06-01

To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

Wall of fundamental constants

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

Olive, Keith A.; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, 55455; Peloso, Marco

2011-02-15

We consider the signatures of a domain wall produced in the spontaneous symmetry breaking involving a dilatonlike scalar field coupled to electromagnetism. Domains on either side of the wall exhibit slight differences in their respective values of the fine-structure constant, {alpha}. If such a wall is present within our Hubble volume, absorption spectra at large redshifts may or may not provide a variation in {alpha} relative to the terrestrial value, depending on our relative position with respect to the wall. This wall could resolve the contradiction between claims of a variation of {alpha} based on Keck/Hires data and of themore » constancy of {alpha} based on Very Large Telescope data. We derive the properties of the wall and the parameters of the underlying microscopic model required to reproduce the possible spatial variation of {alpha}. We discuss the constraints on the existence of the low-energy domain wall and describe its observational implications concerning the variation of the fundamental constants.« less

Increased Airway Wall Thickness is Associated with Adverse Longitudinal First-Second Forced Expiratory Volume Trajectories of Former World Trade Center workers.

PubMed

de la Hoz, Rafael E; Liu, Xiaoyu; Doucette, John T; Reeves, Anthony P; Bienenfeld, Laura A; Wisnivesky, Juan P; Celedón, Juan C; Lynch, David A; San José Estépar, Raúl

2018-05-24

Occupational exposures at the WTC site after September 11, 2001 have been associated with several presumably inflammatory lower airway diseases. In this study, we describe the trajectories of expiratory air flow decline, identify subgroups with adverse progression, and investigate the association of a quantitative computed tomography (QCT) imaging measurement of airway wall thickness, and other risk factors for adverse progression. We examined the trajectories of expiratory air flow decline in a group of 799 former WTC workers and volunteers with QCT-measured (with two independent systems) wall area percent (WAP) and at least 3 periodic spirometries. We calculated individual regression lines for first-second forced expiratory volume (FEV 1 ), identified subjects with rapidly declining and increasing ("gainers"), and compared them to subjects with normal and "stable" FEV 1 decline. We used multivariate logistic regression to model decliner vs. stable trajectories. The mean longitudinal FEV 1 slopes for the entire study population, and its stable, decliner, and gainer subgroups were, respectively, - 35.8, - 8, - 157.6, and + 173.62 ml/year. WAP was associated with "decliner" status (OR adj 1.08, 95% CI 1.02, 1.14, per 5% increment) compared to stable. Age, weight gain, baseline FEV 1 percent predicted, bronchodilator response, and pre-WTC occupational exposures were also significantly associated with accelerated FEV 1 decline. Analyses of gainers vs. stable subgroup showed WAP as a significant predictor in unadjusted but not consistently in adjusted analyses. The apparent normal age-related rate of FEV 1 decline results from averaging widely divergent trajectories. WAP is significantly associated with accelerated air flow decline in WTC workers.

A thin-walled pressurized sphere exposed to external general corrosion and nonuniform heating

NASA Astrophysics Data System (ADS)

Sedova, Olga S.; Pronina, Yulia G.; Kuchin, Nikolai L.

2018-05-01

A thin-walled spherical shell subjected to simultaneous action of internal and external pressure, nonuniform heating and outside mechanochemical corrosion is considered. It is assumed that the shell is homogeneous, isotropic and linearly elastic. The rate of corrosion is linearly dependent on the equivalent stress, which is the sum of mechanical and temperature stress components. Paper presents a new analytical solution, which takes into account the effect of the internal and external pressure values themselves, not only their difference. At the same time, the new solution has a rather simple form as compared to the results based on the solution to the Lame problem for a thick-walled sphere under pressure. The solution obtained can serve as a benchmark for numerical analysis and for a qualitative forecast of durability of the vessel.

Plasma Chamber and First Wall of the Ignitor Experiment^*

NASA Astrophysics Data System (ADS)

Cucchiaro, A.; Coppi, B.; Bianchi, A.; Lucca, F.

2005-10-01

The new designs of the Plasma Chamber (PC) and of the First Wall (FW) system are based on updated scenarios for vertical plasma disruption (VDE) as well as estimates for the maximum thermal wall loadings at ignition. The PC wall thickness has been optimized to reduce the deformation during the worst disruption event without sacrificing the dimensions of the plasma column. A non linear dynamic analysis of the PC has been performed on a 360^o model of it, taking into account possible toroidal asymmetries of the halo current. Radial EM loads obtained by scaling JET measurements have been also considered. The low-cycle fatigue analysis confirms that the PC is able to meet a lifetime of few thousand cycles for the most extreme combinations of magnetic fields and plasma currents. The FW, made of Molybdenum (TZM) tiles covering the entire inner surface of the PC, has been designed to withstand thermal and EM loads, both under normal operating conditions and in case of disruption. Detailed elasto-plastic structural analyses of the most (EM) loaded tile-carriers show that these are compatible with the adopted fabrication requirements. ^*Sponsored in part by ENEA of Italy and by the U.S. DOE.

Evaluation of Strains and Thicknesses of Pipe Elbows on the Basis of Expressions Resulting from the Eudirective for the Case of Large and Small Deformations

NASA Astrophysics Data System (ADS)

Śloderbach, Z.

2017-12-01

The relations to calculate the maximum value of strains in processes of bending tubes on benders, in stretched layers of tubes, are presented in this work on the basis of the EU-Directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of the knee after bending.

Accommodating Thickness in Origami-Based Deployable Arrays

NASA Technical Reports Server (NTRS)

Zirbel, Shannon A.; Magleby, Spencer P.; Howell, Larry L.; Lang, Robert J.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Trease, Brian P.

2013-01-01

The purpose of this work is to create deployment systems with a large ratio of stowed-to-deployed diameter. Deployment from a compact form to a final flat state can be achieved through origami-inspired folding of panels. There are many models capable of this motion when folded in a material with negligible thickness; however, when the application requires the folding of thick, rigid panels, attention must be paid to the effect of material thickness not only on the final folded state, but also during the folding motion (i.e., the panels must not be required to flex to attain the final folded form). The objective is to develop new methods for deployment from a compact folded form to a large circular array (or other final form). This paper describes a mathematical model for modifying the pattern to accommodate material thickness in the context of the design, modeling, and testing of a deployable system inspired by an origami six-sided flasher model. The model is demonstrated in hardware as a 1/20th scale prototype of a deployable solar array for space applications. The resulting prototype has a ratio of stowed-to-deployed diameter of 9.2 (or 1.25 m deployed outer diameter to 0.136 m stowed outer diameter).

Energy transmission through a double-wall curved stiffened panel using Green's theorem

NASA Astrophysics Data System (ADS)

Ghosh, Subha; Bhattacharya, Partha

2015-04-01

It is a common practice in aerospace and automobile industries to use double wall panels as fuselage skins or in window panels to improve acoustic insulation. However, the scientific community is yet to develop a reliable prediction method for a suitable vibro-acoustic model for sound transmission through a curved double-wall panel. In this quest, the present work tries to delve into the modeling of energy transmission through a double-wall curved panel. Subsequently the radiation of sound power into the free field from the curved panel in the low to mid frequency range is also studied. In the developed model to simulate a stiffened aircraft fuselage configuration, the outer wall is provided with longitudinal stiffeners. A modal expansion theory based on Green's theorem is implemented to model the energy transmission through an acoustically coupled double-wall curved panel. An elemental radiator approach is implemented to calculate the radiated energy from the curved surface in to the free field. The developed model is first validated with various numerical models available. It has been observed in the present study that the radius of curvature of the surface has a prominent effect on the behavior of radiated sound power into the free field. Effect of the thickness of the air gap between the two curved surfaces on the sound power radiation has also been noted.

Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

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

Xi, Xiaoning; Tittmann, Bernhard; Kim, Seong H.

An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impactsmore » on the cell wall modulus, and not the cellulose microfibril packing.« less

Wall interference in a two-dimensional-flow wind tunnel, with consideration of the effect of compressibility

NASA Technical Reports Server (NTRS)

Allen, H Julian; Vincenti, Walter G

1944-01-01

Theoretical tunnel-wall corrections are derived for an airfoil of finite thickness and camber in a two-dimensional-flow wind tunnel. The theory takes account of the effects of the wake of the airfoil and of the compressibility of the fluid, and is based upon the assumption that the chord of the airfoil is small in comparison with the height of the tunnel. Consideration is given to the phenomenon of choking at high speeds and its relation to the tunnel-wall corrections. The theoretical results are compared with the small amount of low-speed experimental data available and the agreement is seen to be satisfactory, even for relatively large values of the chord-height ratio.

Experimental study on the heat transfer characteristics of a nuclear reactor containment wall cooled by gravitationally falling water

NASA Astrophysics Data System (ADS)

Pasek, Ari D.; Umar, Efrison; Suwono, Aryadi; Manalu, Reinhard E. E.

2012-06-01

Gravitationally falling water cooling is one of mechanism utilized by a modern nuclear Pressurized Water Reactor (PWR) for its Passive Containment Cooling System (PCCS). Since the cooling is closely related to the safety, water film cooling characteristics of the PCCS should be studied. This paper deals with the experimental study of laminar water film cooling on the containment model wall. The influences of water mass flow rate and wall heat rate on the heat transfer characteristic were studied. This research was started with design and assembly of a containment model equipped with the water cooling system, and calibration of all measurement devices. The containment model is a scaled down model of AP 1000 reactor. Below the containment steam is generated using electrical heaters. The steam heated the containment wall, and then the temperatures of the wall in several positions were measure transiently using thermocouples and data acquisition. The containment was then cooled by falling water sprayed from the top of the containment. The experiments were done for various wall heat rate and cooling water flow rate. The objective of the research is to find the temperature profile along the wall before and after the water cooling applied, prediction of the water film characteristic such as means velocity, thickness and their influence to the heat transfer coefficient. The result of the experiments shows that the wall temperatures significantly drop after being sprayed with water. The thickness of water film increases with increasing water flow rate and remained constant with increasing wall heat rate. The heat transfer coefficient decreases as film mass flow rate increase due to the increases of the film thickness which causes the increasing of the thermal resistance. The heat transfer coefficient increases slightly as the wall heat rate increases. The experimental results were then compared with previous theoretical studied.

Correlation of root dentin thickness and length of roots in mesial roots of mandibular molars.

PubMed

Dwivedi, Shweta; Dwivedi, Chandra Dhar; Mittal, Neelam

2014-09-01

The purpose of this study was to analyze the relation of tooth length and distal wall thickness of mesial roots in mandibular molars at different locations (ie, 2 mm below the furcation and at the junction between the middle and apical third). Forty-five mandibular first molars were taken, and the length of each tooth was measured. Then, specimens were divided into three groups according to their length: group I-long (24.2 mm ± 1.8), group II-medium (21 mm ± 1.5) and group III-short (16.8 mm ± 1.8). mesial root of each marked at two levels - at 2 mm below the furcation as well as at junction of apical and middle third of roots. The minimum thickness of the distal root dentine associated with the buccal and lingual canals of the mesial roots was measured, The distance between the buccal and lingual canals and the depth of concavity in the distal surface of the mesial roots were also measured. Statistical analysis was performed by using analysis of variance and the Student-Newman-Keuls test. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < .001) between groups 1 (long) and 3 (short). Distal wall thickness of the mesiobuccal root and distal concavity of the mesial root of mandibular first molars were found to be thinner in longer teeth compared with shorter teeth. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Implementing Green Walls in Schools.

PubMed

McCullough, Michael B; Martin, Michael D; Sajady, Mollika A

2018-01-01

Numerous studies in applied pedagogical design have shown that, at all educational levels, direct exposure to the natural environment can enhance learning by improving student attention and behaviors. Implementing green walls-a "vertical garden," or "living wall" interior wall that typically includes greenery, a growing medium (soil or substrate) and a water delivery system-provides environmental health benefits, but also provides a practical application within classrooms for minimizing directed attention fatigue in students by connecting them to "outdoor nature" within the indoor environment. Hands-on "project-based" learning is another pedagogical strategy that has proved to be effective across the spectrum of educational levels and across subject areas. Green walls have the potential to inspire critical thinking through a combination of project-based learning strategies and environmental education. The authors have outlined a curriculum involving the implementation of an indoor living wall system within a classroom-learning environment, incorporating project-based learning modules that interact with the wall. In conjunction with the passive health benefits of a green wall, project-based curriculum models can connect students interactively with indoor nature and have the potential to inspire real-world thinking related to science, technology, engineering, art, and mathematics fields within the indoor learning environment. Through a combination of these passive and interactive modes, students are connected to nature in the indoor environment regardless of weather conditions outdoors. Future research direction could include post-construction studies of the effectiveness of project-based curricula related to living walls, and the long-term impacts of implementing green walls in classrooms on school achievement and student behaviors.

Growth and cell wall changes in stem organs under microgravity and hypergravity conditions

NASA Astrophysics Data System (ADS)

Hoson, Takayuki; Soga, Kouichi; Wakabayashi, Kazuyuki; Kamisaka, Seiichiro

Gravity strongly influences plant growth and development, which is fundamentally brought about by modifications to the properties of the cell wall. We have examined the changes in growth and cell wall properties in seedling organs under hypergravity conditions produced by centrifugation and under microgravity conditions in space. Hypergravity stimuli have been shown to decrease the growth rate of various seedling organs. When hypergravity suppressed elongation growth, a decrease in cell wall extensibility (an increase in cell wall rigidity) was induced. Hypergravity has also been shown to increase cell wall thickness in various mate-rials. In addition, a polymerization of certain matrix polysaccharides was brought about by hypergravity: in dicotyledons hypergravity increased the molecular size of xyloglucans, whereas hypergravity increased that of 1,3,1,4-β-glucans in monocotyledonous Gramineae. These mod-ifications to cell wall metabolism may be responsible for a decrease in cell wall extensibility, leading to growth suppression under hypergravity conditions. How then does microgravity in-fluence growth and cell wall properties? Here, there was a possibility that microgravity might induce changes similar to those by hypergravity, because plants have evolved and adapted to 1 g condition for more than 400 million years. However, the changes observed under microgravity conditions in space were just opposite to those induced by hypergravity: stimulation of elonga-tion growth, an increase in cell wall extensibility, and a decrease in cell wall thickness as well as depolymerization of cell wall polysaccharides were brought about in space. Furthermore, growth and cell wall properties varied in proportion to the logarithm of the magnitude of grav-ity in the range from microgravity to hypergravity, as shown in the dose-response relation in light and hormonal responses. Thus, microgravity may be a `stress-less' environment for plant seedlings to grow and develop

Rock classification based on resistivity patterns in electrical borehole wall images

NASA Astrophysics Data System (ADS)

Linek, Margarete; Jungmann, Matthias; Berlage, Thomas; Pechnig, Renate; Clauser, Christoph

2007-06-01

Electrical borehole wall images represent grey-level-coded micro-resistivity measurements at the borehole wall. Different scientific methods have been implemented to transform image data into quantitative log curves. We introduce a pattern recognition technique applying texture analysis, which uses second-order statistics based on studying the occurrence of pixel pairs. We calculate so-called Haralick texture features such as contrast, energy, entropy and homogeneity. The supervised classification method is used for assigning characteristic texture features to different rock classes and assessing the discriminative power of these image features. We use classifiers obtained from training intervals to characterize the entire image data set recovered in ODP hole 1203A. This yields a synthetic lithology profile based on computed texture data. We show that Haralick features accurately classify 89.9% of the training intervals. We obtained misclassification for vesicular basaltic rocks. Hence, further image analysis tools are used to improve the classification reliability. We decompose the 2D image signal by the application of wavelet transformation in order to enhance image objects horizontally, diagonally and vertically. The resulting filtered images are used for further texture analysis. This combined classification based on Haralick features and wavelet transformation improved our classification up to a level of 98%. The application of wavelet transformation increases the consistency between standard logging profiles and texture-derived lithology. Texture analysis of borehole wall images offers the potential to facilitate objective analysis of multiple boreholes with the same lithology.

Detection of honeycomb cell walls from measurement data based on Harris corner detection algorithm

NASA Astrophysics Data System (ADS)

Qin, Yan; Dong, Zhigang; Kang, Renke; Yang, Jie; Ayinde, Babajide O.

2018-06-01

A honeycomb core is a discontinuous material with a thin-wall structure—a characteristic that makes accurate surface measurement difficult. This paper presents a cell wall detection method based on the Harris corner detection algorithm using laser measurement data. The vertexes of honeycomb cores are recognized with two different methods: one method is the reduction of data density, and the other is the optimization of the threshold of the Harris corner detection algorithm. Each cell wall is then identified in accordance with the neighboring relationships of its vertexes. Experiments were carried out for different types and surface shapes of honeycomb cores, where the proposed method was proved effective in dealing with noise due to burrs and/or deformation of cell walls.

Inverse measurement of wall pressure field in flexible-wall wind tunnels using global wall deformation data

NASA Astrophysics Data System (ADS)

Brown, Kenneth; Brown, Julian; Patil, Mayuresh; Devenport, William

2018-02-01

The Kevlar-wall anechoic wind tunnel offers great value to the aeroacoustics research community, affording the capability to make simultaneous aeroacoustic and aerodynamic measurements. While the aeroacoustic potential of the Kevlar-wall test section is already being leveraged, the aerodynamic capability of these test sections is still to be fully realized. The flexibility of the Kevlar walls suggests the possibility that the internal test section flow may be characterized by precisely measuring small deflections of the flexible walls. Treating the Kevlar fabric walls as tensioned membranes with known pre-tension and material properties, an inverse stress problem arises where the pressure distribution over the wall is sought as a function of the measured wall deflection. Experimental wall deformations produced by the wind loading of an airfoil model are measured using digital image correlation and subsequently projected onto polynomial basis functions which have been formulated to mitigate the impact of measurement noise based on a finite-element study. Inserting analytic derivatives of the basis functions into the equilibrium relations for a membrane, full-field pressure distributions across the Kevlar walls are computed. These inversely calculated pressures, after being validated against an independent measurement technique, can then be integrated along the length of the test section to give the sectional lift of the airfoil. Notably, these first-time results are achieved with a non-contact technique and in an anechoic environment.

Measurements in the near-wall region of a relaxing three-dimensional low speed turbulent air boundary layer

NASA Technical Reports Server (NTRS)

Hebbar, K. S.; Melnik, W. L.

1976-01-01

An experimental investigation was conducted at selected locations of the near-wall region of a three dimensional turbulent air boundary layer relaxing in a nominally zero external pressure gradient behind a transverse hump (in the form of a 30 deg swept, 5-foot chord wing-type model) faired into the side wall of a low speed wind tunnel. Wall shear stresses measured with a flush-mounted hot-film gage and a sublayer fence were in very good agreement with experimental data obtained with two Preston probes. With the upstream unit Reynolds number held constant at 325,000/ft. approximately one-fourth of the boundary layer thickness adjacent to the wall was surveyed with a single rotated hot-wire probe mounted on a specially designed minimum interference traverse mechanism. The boundary layer (approximately 3.5 in thick near the first survey station where the length Reynolds number was 5.5 million) had a maximum crossflow velocity ratio of 0.145 and a maximum crossflow angle of 21.875 deg close to the wall.

Regulation of Neurospora crassa cell wall remodeling via the cot-1 pathway is mediated by gul-1.

PubMed

Herold, Inbal; Yarden, Oded

2017-02-01

Impairment of the Neurospora crassa Nuclear DBF2-related kinase-encoding gene cot-1 results in pleiotropic effects, including abnormally thick hyphal cell walls and septa. An increase in the transcript abundance of genes encoding chitin and glucan synthases and the chitinase gh18-5, but not the cell wall integrity pathway transcription factor rlm-1, accompany the phenotypic changes observed. Deletion of chs-5 or chs-7 in a cot-1 background results in a reduction of hyperbranching frequency characteristic of the cot-1 parent. gul-1 (a homologue of the yeast SSD1 gene) encodes a translational regulator and has been shown to partially suppress cot-1. We demonstrate that the high expression levels of the cell wall remodeling genes analyzed is curbed, and reaches near wild type levels, when gul-1 is inactivated. This is accompanied by morphological changes that include reduced cell wall thickness and restoration of normal chitin levels. We conclude that gul-1 is a mediator of cell wall remodeling within the cot-1 pathway.

Transport Equation Based Wall Distance Computations Aimed at Flows With Time-Dependent Geometry

NASA Technical Reports Server (NTRS)

Tucker, Paul G.; Rumsey, Christopher L.; Bartels, Robert E.; Biedron, Robert T.

2003-01-01

Eikonal, Hamilton-Jacobi and Poisson equations can be used for economical nearest wall distance computation and modification. Economical computations may be especially useful for aeroelastic and adaptive grid problems for which the grid deforms, and the nearest wall distance needs to be repeatedly computed. Modifications are directed at remedying turbulence model defects. For complex grid structures, implementation of the Eikonal and Hamilton-Jacobi approaches is not straightforward. This prohibits their use in industrial CFD solvers. However, both the Eikonal and Hamilton-Jacobi equations can be written in advection and advection-diffusion forms, respectively. These, like the Poisson s Laplacian, are commonly occurring industrial CFD solver elements. Use of the NASA CFL3D code to solve the Eikonal and Hamilton-Jacobi equations in advective-based forms is explored. The advection-based distance equations are found to have robust convergence. Geometries studied include single and two element airfoils, wing body and double delta configurations along with a complex electronics system. It is shown that for Eikonal accuracy, upwind metric differences are required. The Poisson approach is found effective and, since it does not require offset metric evaluations, easiest to implement. The sensitivity of flow solutions to wall distance assumptions is explored. Generally, results are not greatly affected by wall distance traits.

Transport Equation Based Wall Distance Computations Aimed at Flows With Time-Dependent Geometry

NASA Technical Reports Server (NTRS)

Tucker, Paul G.; Rumsey, Christopher L.; Bartels, Robert E.; Biedron, Robert T.

2003-01-01

Eikonal, Hamilton-Jacobi and Poisson equations can be used for economical nearest wall distance computation and modification. Economical computations may be especially useful for aeroelastic and adaptive grid problems for which the grid deforms, and the nearest wall distance needs to be repeatedly computed. Modifications are directed at remedying turbulence model defects. For complex grid structures, implementation of the Eikonal and Hamilton-Jacobi approaches is not straightforward. This prohibits their use in industrial CFD solvers. However, both the Eikonal and Hamilton-Jacobi equations can be written in advection and advection-diffusion forms, respectively. These, like the Poisson's Laplacian, are commonly occurring industrial CFD solver elements. Use of the NASA CFL3D code to solve the Eikonal and Hamilton-Jacobi equations in advective-based forms is explored. The advection-based distance equations are found to have robust convergence. Geometries studied include single and two element airfoils, wing body and double delta configurations along with a complex electronics system. It is shown that for Eikonal accuracy, upwind metric differences are required. The Poisson approach is found effective and, since it does not require offset metric evaluations, easiest to implement. The sensitivity of flow solutions to wall distance assumptions is explored. Generally, results are not greatly affected by wall distance traits.

Cortical thickness and prosocial behavior in school-age children: A population-based MRI study.

PubMed

Thijssen, Sandra; Wildeboer, Andrea; Muetzel, Ryan L; Bakermans-Kranenburg, Marian J; El Marroun, Hanan; Hofman, Albert; Jaddoe, Vincent W V; van der Lugt, Aad; Verhulst, Frank C; Tiemeier, Henning; van IJzendoorn, Marinus H; White, Tonya

2015-01-01

Prosocial behavior plays an important role in establishing and maintaining relationships with others and thus may have important developmental implications. This study examines the association between cortical thickness and prosocial behavior in a population-based sample of 6- to 9-year-old children. The present study was embedded within the Generation R Study. Magnetic resonance scans were acquired from 464 children whose parents had completed the prosocial scale of the Strengths and Difficulties Questionnaire. To study the association between cortical thickness and prosocial behavior, we performed whole-brain surface-based analyses. Prosocial behavior was related to a thicker cortex in a cluster that covers part of the left superior frontal and rostral middle frontal cortex (p < .001). Gender moderated the association between prosocial behavior and cortical thickness in a cluster including the right rostral middle frontal and superior frontal cortex (p < .001) as well as in a cluster covering the right superior parietal cortex, cuneus, and precuneus (p < .001). Our results suggest that prosocial behavior is associated with cortical thickness in regions related to theory of mind (superior frontal cortex, rostral middle frontal cortex cuneus, and precuneus) and inhibitory control (superior frontal and rostral middle frontal cortex).

Magnetic domain wall engineering in a nanoscale permalloy junction

NASA Astrophysics Data System (ADS)

Wang, Junlin; Zhang, Xichao; Lu, Xianyang; Zhang, Jason; Yan, Yu; Ling, Hua; Wu, Jing; Zhou, Yan; Xu, Yongbing

2017-08-01

Nanoscale magnetic junctions provide a useful approach to act as building blocks for magnetoresistive random access memories (MRAM), where one of the key issues is to control the magnetic domain configuration. Here, we study the domain structure and the magnetic switching in the Permalloy (Fe20Ni80) nanoscale magnetic junctions with different thicknesses by using micromagnetic simulations. It is found that both the 90-° and 45-° domain walls can be formed between the junctions and the wire arms depending on the thickness of the device. The magnetic switching fields show distinct thickness dependencies with a broad peak varying from 7 nm to 22 nm depending on the junction sizes, and the large magnetic switching fields favor the stability of the MRAM operation.

Single-Side Two-Location Spotlight Imaging for Building Based on MIMO Through-Wall-Radar.

PubMed

Jia, Yong; Zhong, Xiaoling; Liu, Jiangang; Guo, Yong

2016-09-07

Through-wall-radar imaging is of interest for mapping the wall layout of buildings and for the detection of stationary targets within buildings. In this paper, we present an easy single-side two-location spotlight imaging method for both wall layout mapping and stationary target detection by utilizing multiple-input multiple-output (MIMO) through-wall-radar. Rather than imaging for building walls directly, the images of all building corners are generated to speculate wall layout indirectly by successively deploying the MIMO through-wall-radar at two appropriate locations on only one side of the building and then carrying out spotlight imaging with two different squint-views. In addition to the ease of implementation, the single-side two-location squint-view detection also has two other advantages for stationary target imaging. The first one is the fewer multi-path ghosts, and the second one is the smaller region of side-lobe interferences from the corner images in comparison to the wall images. Based on Computer Simulation Technology (CST) electromagnetic simulation software, we provide multiple sets of validation results where multiple binary panorama images with clear images of all corners and stationary targets are obtained by combining two single-location images with the use of incoherent additive fusion and two-dimensional cell-averaging constant-false-alarm-rate (2D CA-CFAR) detection.

A mobility based vibroacoustic energy transmission simulation into an enclosure through a double-wall panel.

PubMed

Sahu, Atanu; Bhattacharya, Partha; Niyogi, Arup Guha; Rose, Michael

2017-06-01

Double-wall panels are known for their superior sound insulation properties over single wall panels as a sound barrier. The sound transmission phenomenon through a double-wall structure is a complex process involving vibroacoustic interaction between structural panels, the air-cushion in between, and the secondary acoustic domain. It is in this context a versatile and a fully coupled technique based on the finite-element-boundary element model is developed that enables estimation of sound transfer through a double-wall panel into an adjacent enclosure while satisfying the displacement compatibility across the interface. The contribution of individual components in the transmitted energy is identified through numerical simulations.

Positive ion temperature effect on the plasma-wall transition

NASA Astrophysics Data System (ADS)

Morales Crespo, R.

2018-06-01

This paper analyses the plasma-wall interaction of a plasma in contact with a conducting planar surface when the positive-ion temperature is not negligible compared with the electron one. The electric potential from the plasma to the wall is obtained by the appropriate formulation of the model as an initial-value problem as well as some features useful for experimental applications, such as the positive current-to-voltage characteristics, the saturation current density, the floating potential or an estimation of the sheath thickness. Finally, it is analysed how all these quantities depend on the ionization degree and the positive-ion temperature.

On investigating wall shear stress in two-dimensional plane turbulent wall jets

NASA Astrophysics Data System (ADS)

Mehdi, Faraz; Johansson, Gunnar; White, Christopher; Naughton, Jonathan

2012-11-01

Mehdi & White [Exp Fluids 50:43-51(2011)] presented a full momentum integral based method for determining wall shear stress in zero pressure gradient turbulent boundary layers. They utilized the boundary conditions at the wall and at the outer edge of the boundary layer. A more generalized expression is presented here that uses just one boundary condition at the wall. The method is mathematically exact and has an advantage of having no explicit streamwise gradient terms. It is successfully applied to two different experimental plane turbulent wall jet datasets for which independent estimates of wall shear stress were known. Complications owing to experimental inaccuracies in determining wall shear stress from the proposed method are also discussed.

Method of non-destructively inspecting a curved wall portion

DOEpatents

Fong, James T.

1996-01-01

A method of non-destructively inspecting a curved wall portion of a large and thick walled vessel for a defect by computed tomography is provided. A collimated source of radiation is placed adjacent one side of the wall portion and an array of detectors for the radiation is placed on the other side adjacent the source. The radiation from the source passing through the wall portion is then detected with the detectors over a limited angle, dependent upon the curvature of the wall of the vessel, to obtain a dataset. The source and array are then coordinately moved relative to the wall portion in steps and a further dataset is obtained at each step. The plurality of datasets obtained over the limited angle is then processed to produce a tomogram of the wall portion to determine the presence of a defect therein. In a preferred embodiment, the curved wall portion has a center of curvature so that the source and the array are positioned at each step along a respective arc curved about the center. If desired, the detector array and source can be reoriented relative to a new wall portion and an inspection of the new wall portion can be easily obtained. Further, the source and detector array can be indexed in a direction perpendicular to a plane including the limited angle in a plurality of steps so that by repeating the detecting and moving steps at each index step, a three dimensional image can be created of the wall portion.