Requirements of Inconel 718 alloy for aeronautical applications

NASA Astrophysics Data System (ADS)

Ghiban, Brandusa; Elefterie, Cornelia Florina; Guragata, Constantin; Bran, Dragos

2018-02-01

The main requirements imposed by aviation components made from super alloys based on Nickel are presented in present paper. A significant portion of fasteners, locking lugs, blade retainers and inserts are manufactured from Inconel 718 alloy. The thesis describes environmental factors (corrosion), conditions of external aggression (salt air, intense heat, heavy industrial pollution, high condensation, high pressure), mechanical characteristics (tensile strength, creep, density, yield strength, fracture toughness, fatigue resistance) and loadings (tensions, compression loads) that must be satisfied simultaneously by Ni-based super alloy, compared to other classes of aviation alloys (as egg. Titanium alloys, Aluminum alloys). For this alloy the requirements are strength, durability, damage tolerance, fail safety and so on. The corrosion can be an issue, but the fatigue under high-magnitude cyclic tensile loading it what limits the lifetime of the airframe. The excellent malleability and weldability characteristics of the 718 system make the material physical properties tolerant of manufacturing processes. These characteristics additionally continue to provide new opportunities for advanced manufacturing methods.

Aeronautical requirements for Inconel 718 alloy

NASA Astrophysics Data System (ADS)

Elefterie, C. F.; Guragata, C.; Bran, D.; Ghiban, B.

2017-06-01

The project goal is to present the requirements imposed by aviation components made from super alloys based on Nickel. A significant portion of fasteners, locking lugs, blade retainers and inserts are manufactured from Alloy 718. The thesis describes environmental factors (corrosion), conditions of external aggression (salt air, intense heat, heavy industrial pollution, high condensation, high pressure), mechanical characteristics (tensile strength, yield strength and fatigue resistance) and loadings (tensions, compression loads) that must be satisfied simultaneously by Ni-based super alloy, compared to other classes of aviation alloys (as egg. Titanium alloys, Aluminum alloys). For this alloy the requirements are strength durability, damage tolerance, fail safety and so on. The corrosion can be an issue, but the fatigue under high-magnitude cyclic tensile loading it’s what limits the lifetime of the airframe. Also, the excellent malleability and weldability characteristics of the 718 system make the material physical properties tolerant of manufacturing processes. These characteristics additionally continue to provide new opportunities for advanced manufacturing methods.

How prepared are college freshmen athletes for the rigors of college strength and conditioning? A survey of college strength and conditioning coaches.

PubMed

Wade, Susan M; Pope, Zachary C; Simonson, Shawn R

2014-10-01

Training programs for high school athletes have changed over the last 20 years. High school physical education classes have transformed into sport-specific conditioning classes with intensities matching college or professional athlete programming. In addition, involvement in private, sport-specific, training increased; but despite these advanced training methods, are high school athletes prepared for collegiate sport competition? An anonymous survey was sent to 195 Division I strength and conditioning coaches (SCC) to discern incoming college freshman athletes' physical and psychological preparedness for the rigors of collegiate training and sport competition. Fifty-seven (29%) responses were received. Strength and conditioning coaches stated that incoming college freshman athletes lack lower extremity strength, overall flexibility, and core strength as well as proper Olympic lifting technique. Strength and conditioning coaches also stated that athletes lacked the mental toughness to endure collegiate sport training in addition to claiming incoming athletes lacked knowledge of correct nutrition and recovery principles. These results suggest a lack of collegiate training/sport preparedness of high school athletes. High school strength and conditioning specialist's goal is to produce better athletes and doing so requires the strength and conditioning coach/trainer to have knowledge of how to train high school athletes. One way to assure adequate knowledge of strength and conditioning training principles is for high school coaches/trainers to be certified in the field. Strength and conditioning certifications among high school strength and conditioning coaches/trainers would encourage developmentally appropriate training and would provide universities with athletes who are prepared for the rigors of collegiate sport training/competition.

RTM: Cost-effective processing of composite structures

NASA Technical Reports Server (NTRS)

Hasko, Greg; Dexter, H. Benson

1991-01-01

Resin transfer molding (RTM) is a promising method for cost effective fabrication of high strength, low weight composite structures from textile preforms. In this process, dry fibers are placed in a mold, resin is introduced either by vacuum infusion or pressure, and the part is cured. RTM has been used in many industries, including automotive, recreation, and aerospace. Each of the industries has different requirements of material strength, weight, reliability, environmental resistance, cost, and production rate. These requirements drive the selection of fibers and resins, fiber volume fractions, fiber orientations, mold design, and processing equipment. Research is made into applying RTM to primary aircraft structures which require high strength and stiffness at low density. The material requirements are discussed of various industries, along with methods of orienting and distributing fibers, mold configurations, and processing parameters. Processing and material parameters such as resin viscosity, perform compaction and permeability, and tool design concepts are discussed. Experimental methods to measure preform compaction and permeability are presented.

Strength and reliability analysis of metal-composite overwrapped pressure vessel

NASA Astrophysics Data System (ADS)

Burov, A. E.; Lepikhin, A. M.; Moskvichev, V. V.

2017-12-01

Metal-composite overwrapped pressure vessels (MCOPV) have found a wide application in aerospace and aeronautical industries. Such vessels should combine impermeability and high weight efficiency with enhanced long-term safety and durability. To meet these requirements, theoretical and experimental studies on the mechanics of deformation and failure of MCOPV are required. In the paper, the analysis on strength, lifetime and reliability of MCOPV is presented. A high performance of the MCOPV is justified by comparing the calculation results with experiment data obtained on full-scale samples.

Kic size effect study on two high-strength steels using notched bend specimens

NASA Technical Reports Server (NTRS)

Stonesifer, F. R.

1974-01-01

Five methods are used to calculate plane strain fracture toughness (K sub Q) values for bend-specimens of various sizes from two high-strength steels. None of the methods appeared to satisfactorily predict valid stress intensity factor (K sub IC) values from specimens of sizes well below that required by E399 standard tests.

Development of high strength, high temperature ceramics

NASA Technical Reports Server (NTRS)

Hall, W. B.

1982-01-01

Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.

Possibilities for specific utilization of material properties for an optimal part design

NASA Astrophysics Data System (ADS)

Beier, T.; Gerlach, J.; Roettger, R.; Kuhn, P.

2017-09-01

High-strength, cold-formable steels offer great potential for meeting cost and safety requirements in the automotive industry. In view of strengths of up to 1200 MPa now attainable, certain aspects need to be analysed and evaluated in advance in the development process using these materials. In addition to early assessment of crash properties, it is also highly important to adapt the forming process to match the material potential. The steel making companies have widened their portfolios of cold-rolled dual-phase steels well beyond the conventional high-strength steels. There are added new grades which offer a customized selection of high energy absorption, deformation resistance or enhanced cold-forming properties. In this article the necessary components for material modelling for finite element simulation are discussed. Additionally the required tests for material model calibration are presented and the potentials of the thyssenkrupp Steel material data base are introduced. Besides classical tensile tests at different angles to rolling direction and the forming limit curve, the hydraulic bulge test is now available for a wide range of modern steel grades. Using the conventional DP-K®60/98 and the DP-K®700Y980T with higher yield strength the method for calibrating yield locus, hardening and formability is given. With reference to the examples of an A-pillar reinforcement and different crash tests the procedure is shown how the customer can evaluate an optimal steel grade for specific requirements. Although the investigated materials have different yield strengths, no large differences in the forming process between the two steel grades can be found. However some advantages of the high-yield grade can be detected in crash performance depending on the specific boundary and loading conditions.

Simulated Single Tooth Bending of High Temperature Alloys

NASA Technical Reports Server (NTRS)

Handschuh, Robert, F.; Burke, Christopher

2012-01-01

Future unmanned space missions will require mechanisms to operate at extreme conditions in order to be successful. In some of these mechanisms, very high gear reductions will be needed to permit very small motors to drive other components at low rotational speed with high output torque. Therefore gearing components are required that can meet the mission requirements. In mechanisms such as this, bending fatigue strength capacity of the gears is very important. The bending fatigue capacity of a high temperature, nickel-based alloy, typically used for turbine disks in gas turbine engines and two tool steel materials with high vanadium content, were compared to that of a typical aerospace alloy-AISI 9310. Test specimens were fabricated by electro-discharge machining without post machining processing. Tests were run at 24 and at 490 C. As test temperature increased from 24 to 490 C the bending fatigue strength was reduced by a factor of five.

[Methodological aspects of functional neuroimaging at high field strength: a critical review].

PubMed

Scheef, L; Landsberg, M W; Boecker, H

2007-09-01

The last few years have proven that high field magnetic resonance imaging (MRI) is superior in nearly every way to conventional equipment up to 1.5 tesla (T). Following the global success of 3T-scanners in research institutes and medical practices, a new generation of MRI devices with field strengths of 7T and higher is now on the horizon. The introduction of ultra high fields has brought MRI technology closer to the physical limitations and increasingly greater costs are required to achieve this goal. This article provides a critical overview of the advantages and problems of functional neuroimaging using ultra high field strengths. This review is principally limited to T2*-based functional imaging techniques not dependent on contrast agents. The main issues include the significance of high field technology with respect to SNR, CNR, resolution, and sequences, as well as artifacts, noise exposure, and SAR. Of great relevance is the discussion of parallel imaging, which will presumably determine the further development of high and ultra high field strengths. Finally, the importance of high field strengths for functional neuroimaging is explained by selected publications.

Tensile strength/yield strength (TS/YS) ratios of high-strength steel (HSS) reinforcing bars

NASA Astrophysics Data System (ADS)

Tavio, Anggraini, Retno; Raka, I. Gede Putu; Agustiar

2018-05-01

The building codes such as American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013 require that the ratio of tensile strength (TS) and yield strength (YS) should not less than 1.25. The requirement is based on the assumption that a capability of a structural member to develop inelastic rotation capacity is a function of the length of the yield region. This paper reports an investigation on various steel grades, namely Grades 420, 550, 650, and 700 MPa, to examine the impact of different TS/YS ratios if it is less or greater than the required value. Grades 550, 650, and 700 MPa were purposely selected with the intention to examine if these higher grades are still promising to be implemented in special structural systems since they are prohibited by the building codes for longitudinal reinforcement, whereas Grade 420 MPa bars are the maximum limit of yield strength of reinforcing bars that is allowable for longitudinal reinforcement of special structural systems. Tensile tests of these steel samples were conducted under displacement controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. From the study, it can be concluded that Grade 420 performed higher TS/YS ratios and they were able to reach up to more than 1.25. However, the High Strength Still (HSS) bars (Grades 550, 600, and 700 MPa) resulted in lower TS/YS ratios (less than 1.25) compared with those of Grade 420 MPa.

Advances in Low Carbon, High Strength Ferrous Alloys

DTIC Science & Technology

1993-04-01

35 TABLES 1. Specified chemical compositions and mechanical properties for GMAW/SAW/ GTAW wire electrodes, MIL-XXXS type, for welding...minimum service temperature of +300 F. The chromium and molybdenum additions improved hardenability and promoted the formation of mar- tensite in thick...alloying ele- ments ( chromium , nickel and molybdenum) are required, especially for thick sections. Production of high strength steel plate for military

High stenghth concrete with high cement substitution by adding fly ash, CaCO3, silica sand, and superplasticizer

NASA Astrophysics Data System (ADS)

Wicaksono, Muchammad Ridho Sigit; Qoly, Amelia; Hidayah, Annisaul; Pangestuti, Endah Kanti

2017-03-01

Concrete is a mixture of cement, fine aggregate, coarse aggregate and water with or without additives. Concrete can be made with substitution of cement with materials like Fly Ash, CaCO3 and silica sand that can increase the binding on pasta and also increase the compressive strength of concrete. The Superplasticizer on a mixture is used to reduce the high water content, improve concrete durability, low permeability concrete by making it more resilient, and improve the quality of concrete. The combination between Fly Ash (30% of cement required), CaCO3 (10% of cement required) and silica sand (5% of cement required) with added MasterGlenium ACE 8595 as much as 1,2% from total cement will produces compressive strength of up to 1080 kN/cm2 or 73,34 Mpa when the concrete is aged at 28 day. By using this technique and innovation, it proves that the cost reduction is calculated at 27%, which is much more efficient. While the strength of the concrete is increased at 5% compared with normal mixture.

High dislocation density-induced large ductility in deformed and partitioned steels

NASA Astrophysics Data System (ADS)

He, B. B.; Hu, B.; Yen, H. W.; Cheng, G. J.; Wang, Z. K.; Luo, H. W.; Huang, M. X.

2017-09-01

A wide variety of industrial applications require materials with high strength and ductility. Unfortunately, the strategies for increasing material strength, such as processing to create line defects (dislocations), tend to decrease ductility. We developed a strategy to circumvent this in inexpensive, medium manganese steel. Cold rolling followed by low-temperature tempering developed steel with metastable austenite grains embedded in a highly dislocated martensite matrix. This deformed and partitioned (D and P) process produced dislocation hardening but retained high ductility, both through the glide of intensive mobile dislocations and by allowing us to control martensitic transformation. The D and P strategy should apply to any other alloy with deformation-induced martensitic transformation and provides a pathway for the development of high-strength, high-ductility materials.

Evaluation and comparison of transverse and impact strength of different high strength denture base resins.

PubMed

Gupta, Abhinav; Tewari, R K

2016-01-01

The present study was undertaken to evaluate and compare the impact strength and transverse strength of the high-impact denture base materials. A conventional heat polymerized acrylic resin was used as a control. The entire experiment was divided into four main groups with twenty specimens each according to denture base material selected Trevalon, Trevalon Hi, DPI Tuff and Metrocryl Hi. These groups were further subgrouped into the two parameters selected, impact strength and flexural strength with ten specimens each. These specimens were then subjected to transverse bend tests with the help of Lloyds instrument using a three point bend principle. Impact tests were undertaken using an Izod-Charpy digital impact tester. This study was analyzed with one-way analysis of variance using Fisher f-test and Bonferroni t-test. There was a significant improvement in the impact strength of high-impact denture base resins as compared to control (Trevalon). However, in terms of transverse bend tests, only DPI Tuff showed higher transverse strength in comparison to control. Trevalon Hi and Metrocryl Hi showed a decrease in transverse strength. Within the limits of this in vitro study, (1) There is a definite increase in impact strength due to the incorporation of butadiene styrene rubber in this high strength denture base materials as compared to Trevalon used as a control. (2) Further investigations are required to prevent the unduly decrease of transverse strength. (3) It was the limitation of the study that the exact composition of the high-impact resins was not disclosed by the manufacturer that would have helped in better understanding of their behavior.

Analysis of local warm forming of high strength steel using near infrared ray energy

NASA Astrophysics Data System (ADS)

Yang, W. H.; Lee, K.; Lee, E. H.; Yang, D. Y.

2013-12-01

The automotive industry has been pressed to satisfy more rigorous fuel efficiency requirements to promote energy conservation, safety features and cost containment. To satisfy this need, high strength steel has been developed and used for many different vehicle parts. The use of high strength steels, however, requires careful analysis and creativity in order to accommodate its relatively high springback behavior. An innovative method, called local warm forming with near infrared ray, has been developed to help promote the use of high strength steels in sheet metal forming. For this method, local regions of the work piece are heated using infrared ray energy, thereby promoting the reduction of springback behavior. In this research, a V-bend test is conducted with DP980. After springback, the bend angles for specimens without local heating are compared to those with local heating. Numerical analysis has been performed using the commercial program, DEFORM-2D. This analysis is carried out with the purpose of understanding how changes to the local stress distribution will affect the springback during the unloading process. The results between experimental and computational approaches are evaluated to assure the accuracy of the simulation. Subsequent numerical simulation studies are performed to explore best practices with respect to thermal boundary conditions, timing, and applicability to the production environment.

Fabrication and processing of high-strength densely packed carbon nanotube yarns without solution processes.

PubMed

Liu, Kai; Zhu, Feng; Liu, Liang; Sun, Yinghui; Fan, Shoushan; Jiang, Kaili

2012-06-07

Defects of carbon nanotubes, weak tube-tube interactions, and weak carbon nanotube joints are bottlenecks for obtaining high-strength carbon nanotube yarns. Some solution processes are usually required to overcome these drawbacks. Here we fabricate ultra-long and densely packed pure carbon nanotube yarns by a two-rotator twisting setup with the aid of some tensioning rods. The densely packed structure enhances the tube-tube interactions, thus making high tensile strengths of carbon nanotube yarns up to 1.6 GPa. We further use a sweeping laser to thermally treat as-produced yarns for recovering defects of carbon nanotubes and possibly welding carbon nanotube joints, which improves their Young's modulus by up to ∼70%. The spinning and laser sweeping processes are solution-free and capable of being assembled together to produce high-strength yarns continuously as desired.

Development of Low-Carbon, Copper-Strengthened HSLA Steel Plate for Naval Ship Construction

DTIC Science & Technology

1990-06-01

steel plate microstructures, 2% nital etch . ...................................................... 13 2. Charpy V-notch impact energy transition for...met a minimum yield strength requirement of 80 ksi yield strength through 3/4 inch gage, had high Charpy V-notch impact energy at low tempera- tures...tempered HSLA line-pipe steels, which typically could not meet the minimum Charpy V-notch impact toughness requirement of 35 ft-lb at -1 200 F. In 1984

Computer modeling design of a frame pier for a high-speed railway project

NASA Astrophysics Data System (ADS)

Shi, Jing-xian; Fan, Jiang

2018-03-01

In this paper, a double line pier on a high-speed railway in China is taken as an example. the size of each location is drawn up firstly. The design of pre-stressed steel beam for its crossbeam is carried out, and the configuration of ordinary reinforcement is carried out for concrete piers. Combined with bridge structure analysis software Midas Civil and BSAS, the frame pier is modeled and calculated. The results show that the beam and pier column section size reasonable design of pre-stressed steel beam with 17-7V5 high strength low relaxation steel strand, can meet the requirements of high speed railway carrying capacity; the main reinforcement of pier shaft with HRB400 diameter is 28mm, ring arranged around the pier, can satisfy the eccentric compression strength, stiffness and stability requirements, also meet the requirements of seismic design.

Continuous treatment of high strength wastewaters using air-cathode microbial fuel cells.

PubMed

Kim, Kyoung-Yeol; Yang, Wulin; Evans, Patrick J; Logan, Bruce E

2016-12-01

Treatment of low strength wastewaters using microbial fuel cells (MFCs) has been effective at hydraulic retention times (HRTs) similar to aerobic processes, but treatment of high strength wastewaters can require longer HRTs. The use of two air-cathode MFCs hydraulically connected in series was examined to continuously treat high strength swine wastewater (7-8g/L of chemical oxygen demand) at an HRT of 16.7h. The maximum power density of 750±70mW/m 2 was produced after 12daysof operation. However, power decreased by 85% after 185d of operation due to serious cathode fouling. COD removal was improved by using a lower external resistance, and COD removal rates were substantially higher than those previously reported for a low strength wastewater. However, removal rates were inconsistent with first order kinetics as the calculated rate constant was an order of magnitude lower than rate constant for the low strength wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

High-Tensile Strength Tape Versus High-Tensile Strength Suture: A Biomechanical Study.

PubMed

Gnandt, Ryan J; Smith, Jennifer L; Nguyen-Ta, Kim; McDonald, Lucas; LeClere, Lance E

2016-02-01

To determine which suture design, high-tensile strength tape or high-tensile strength suture, performed better at securing human tissue across 4 selected suture techniques commonly used in tendinous repair, by comparing the total load at failure measured during a fixed-rate longitudinal single load to failure using a biomechanical testing machine. Matched sets of tendon specimens with bony attachments were dissected from 15 human cadaveric lower extremities in a manner allowing for direct comparison testing. With the use of selected techniques (simple Mason-Allen in the patellar tendon specimens, whip stitch in the quadriceps tendon specimens, and Krackow stitch in the Achilles tendon specimens), 1 sample of each set was sutured with a 2-mm braided, nonabsorbable, high-tensile strength tape and the other with a No. 2 braided, nonabsorbable, high-tensile strength suture. A total of 120 specimens were tested. Each model was loaded to failure at a fixed longitudinal traction rate of 100 mm/min. The maximum load and failure method were recorded. In the whip stitch and the Krackow-stitch models, the high-tensile strength tape had a significantly greater mean load at failure with a difference of 181 N (P = .001) and 94 N (P = .015) respectively. No significant difference was found in the Mason-Allen and simple stitch models. Pull-through remained the most common method of failure at an overall rate of 56.7% (suture = 55%; tape = 58.3%). In biomechanical testing during a single load to failure, high-tensile strength tape performs more favorably than high-tensile strength suture, with a greater mean load to failure, in both the whip- and Krackow-stitch models. Although suture pull-through remains the most common method of failure, high-tensile strength tape requires a significantly greater load to pull-through in a whip-stitch and Krakow-stitch model. The biomechanical data obtained in the current study indicates that high-tensile strength tape may provide better repair strength compared with high-tensile strength suture at time-zero simulated testing. Published by Elsevier Inc.

Astrocytes regulate heterogeneity of presynaptic strengths in hippocampal networks

PubMed Central

Letellier, Mathieu; Park, Yun Kyung; Chater, Thomas E.; Chipman, Peter H.; Gautam, Sunita Ghimire; Oshima-Takago, Tomoko; Goda, Yukiko

2016-01-01

Dendrites are neuronal structures specialized for receiving and processing information through their many synaptic inputs. How input strengths are modified across dendrites in ways that are crucial for synaptic integration and plasticity remains unclear. We examined in single hippocampal neurons the mechanism of heterosynaptic interactions and the heterogeneity of synaptic strengths of pyramidal cell inputs. Heterosynaptic presynaptic plasticity that counterbalances input strengths requires N-methyl-d-aspartate receptors (NMDARs) and astrocytes. Importantly, this mechanism is shared with the mechanism for maintaining highly heterogeneous basal presynaptic strengths, which requires astrocyte Ca2+ signaling involving NMDAR activation, astrocyte membrane depolarization, and L-type Ca2+ channels. Intracellular infusion of NMDARs or Ca2+-channel blockers into astrocytes, conditionally ablating the GluN1 NMDAR subunit, or optogenetically hyperpolarizing astrocytes with archaerhodopsin promotes homogenization of convergent presynaptic inputs. Our findings support the presence of an astrocyte-dependent cellular mechanism that enhances the heterogeneity of presynaptic strengths of convergent connections, which may help boost the computational power of dendrites. PMID:27118849

Stiff, light, strong and ductile: nano-structured High Modulus Steel.

PubMed

Springer, H; Baron, C; Szczepaniak, A; Uhlenwinkel, V; Raabe, D

2017-06-05

Structural material development for lightweight applications aims at improving the key parameters strength, stiffness and ductility at low density, but these properties are typically mutually exclusive. Here we present how we overcome this trade-off with a new class of nano-structured steel - TiB 2 composites synthesised in-situ via bulk metallurgical spray-forming. Owing to the nano-sized dispersion of the TiB 2 particles of extreme stiffness and low density - obtained by the in-situ formation with rapid solidification kinetics - the new material has the mechanical performance of advanced high strength steels, and a 25% higher stiffness/density ratio than any of the currently used high strength steels, aluminium, magnesium and titanium alloys. This renders this High Modulus Steel the first density-reduced, high stiffness, high strength and yet ductile material which can be produced on an industrial scale. Also ideally suited for 3D printing technology, this material addresses all key requirements for high performance and cost effective lightweight design.

Critical factors in displacement ductility assessment of high-strength concrete columns

NASA Astrophysics Data System (ADS)

Taheri, Ali; Moghadam, Abdolreza S.; Tasnimi, Abass Ali

2017-12-01

Ductility of high-strength concrete (HSC) columns with rectangular sections was assessed in this study by reviewing experimental data from the available literature. Up to 112 normal weights concrete columns with strength in the range of 50-130 MPa were considered and presented as a database. The data included the results of column testes under axial and reversed lateral loading. Displacement ductility of HSC columns was evaluated in terms of their concrete and reinforcement strengths, bar arrangement, volumetric ratio of transverse reinforcement, and axial loading. The results indicated that the confinement requirements and displacement ductility in HSC columns are more sensitive than those in normal strength concrete columns. Moreover, ductility is descended by increasing concrete strength. However, it was possible to obtain ductile behavior in HSC columns through proper confinement. Furthermore, this study casts doubt about capability of P/ A g f c' ratio that being inversely proportional to displacement ductility of HSC columns.

Design Concept for a Reusable/Propellantless MXER Tether Space Transportation System

NASA Technical Reports Server (NTRS)

McCandless, B., II; Kustas, F. m.; Marshall, L. S.; Lytle, W. B.; Hansen, N. P.

2005-01-01

The Momentum Exchange/Electrodynamic Reboost (MXER) tether facility is a transformational concept that significantly reduces the fuel requirements (and associated costs) in transferring payloads above low earth orbit (LEO). Facility reboost is accomplished without propellant by driving current against a voltage created by a conducting tether's interaction with the Earth's magnetic field (electrodynamic reboost). This system can be used for transferring a variety of payloads (scientific, cargo, and human space vehicles) to multiple destinations including geosynchronous transfer orbit, the Moon or Mars. MXER technology advancement requires development in two key areas: survivable, high tensile strength non-conducting tethers and reliable, lightweight payload catch/release mechanisms. Fundamental requirements associated with the MXER non-conducting strength tether and catch mechanism designs will be presented. Key requirements for the tether design include high specific-strength (tensile strength/material density), material survivability to the space environment (atomic oxygen and ultraviolet radiation), and structural survivability to micrometeoroid/orbital debris (MM/OD) impacts. The driving mechanism key,gequirements include low mass-to-capture-volume ratio, positional and velocity error tolerance, and operational reliability. Preliminary tether and catch mechanism design criteria are presented, which have been used as guidelines to "screen" and down-select initial concepts. Candidate tether materials and protective coatings are summarized along with their performance in simulated space environments (e.g., oxygen plasma, thermal cycling). A candidate catch mechanism design concept is presented along with examples of demonstration hardware.

Mechanical and Tear Properties of Fabric/Film Laminates

NASA Technical Reports Server (NTRS)

Said, Magdi A.

1998-01-01

Films reinforced with woven fabrics are being considered for the development of a material suitable for long duration scientific balloons under a program managed by the National Aeronautics and Space Administration (NASA). Recently developed woven fabrics provide a relatively high strength to weight ratio compared to standard homogenous films. Woven fabrics also have better crack propagation resistance and rip stop capabilities when compared to homogenous lightweight, high strength polymeric films such as polyester and nylon. If joining is required, such as in the case of scientific balloons, woven fabrics have the advantage over polymeric thin films to utilize traditional textile methods as well as other techniques including hot sealing, adhesion, and ultrasonic means. Woven fabrics, however, lack the barrier properties required for helium filled scientific balloons, therefore lamination with homogenous films is required to provide the gas barrier capabilities required in these applications.

Performance Steel Castings

DTIC Science & Technology

2012-09-30

Development of Sand Properties 103 Advanced Modeling Dataset.. 105 High Strength Low Alloy (HSLA) Steels 107 Steel Casting and Engineering Support...to achieve the performance goals required for new systems. The dramatic reduction in weight and increase in capability will require high performance...for improved weapon system reliability. SFSA developed innovative casting design and manufacturing processes for high performance parts. SFSA is

Material and cooling requirements for poly-Bitter resistive magnets and hybrid inserts generating continuous fields up to 50 T

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

Gao, B.J.; Bird, M.D.; Eyssa, Y.M.

1994-07-01

The new National High Magnetic Field Laboratory (NHMFL), equipped with a 40 MW DC power supply, will design and construct the next generation of high field resistive magnets and hybrid inserts generating DC fields up to 50 T. The authors present a study on the required materials and the necessary cooling characteristics, these magnets need. The configuration selected for this study consists of a combination of thin poly-Bitter and thick Bitter coils optimized in dimensions and power under constraint of maximum design stress and heat removal to obtain maximum field. The study shows that each design requires a different optimummore » ratio of conductor strength to electrical conductivity and that efficient cooling is only advantageous if strong copper alloys are used. For efficient use of the available power the development of new high strength, high conductivity materials will be necessary. Equally important are improvements in the heat transfer characteristics of these high power density magnets.« less

Jet engine applications for materials with nanometer-scale dimensions

NASA Technical Reports Server (NTRS)

Appleby, J. W., Jr.

1995-01-01

The performance of advanced military and commercial gas turbine engines is often linked to advances in materials technology. High performance gas turbine engines being developed require major material advances in strength, toughness, reduced density and improved temperature capability. The emerging technology of nanostructured materials has enormous potential for producing materials with significant improvements in these properties. Extraordinary properties demonstrated in the laboratory include material strengths approaching theoretical limit, ceramics that demonstrate ductility and toughness, and materials with ultra-high hardness. Nanostructured materials and coatings have the potential for meeting future gas turbine engine requirements for improved performance, reduced weight and lower fuel consumption.

Jet engine applications for materials with nanometer-scale dimensions

NASA Technical Reports Server (NTRS)

Appleby, J. W., Jr.

1995-01-01

The performance of advanced military and commercial gas turbine engines is often linked to advances in materials technology. High performance gas turbine engines being developed require major material advances in strength, toughness, reduced density and improved temperature capability. The emerging technology of nanostructured materials has enormous potential for producing materials with significant improvements in these properties. Extraordinary properties demonstrated in the laboratory include material strengths approaching theoretical limit, ceramics that demonstrate ductility and toughness, and material with ultra-high hardness. Nanostructured materials and coatings have the potential for meeting future gas turbine engine requirements for improved performance, reduced weight and lower fuel consumption.

Retort braze bonding of borsic/aluminum composite sheet to titanium

NASA Technical Reports Server (NTRS)

Webb, B. A.; Dolowy, J. F., Jr.

1975-01-01

Braze bonding studies between Borsic/aluminum composite and titanium sheet were conducted to establish acceptable brazing techniques and to assess potential joint efficiencies. Excellent braze joints were produced which exhibited joint strengths exceeding 117 MPa (17,000 psi) and which retained up to 2/3 of this strength at 589 K (600 F). Noticeable composite strength degradation resulting from the required high temperature braze cycle was found to be a problem.

Design of High Voltage Electrical Breakdown Strength measuring system at 1.8K with a G-M cryocooler

NASA Astrophysics Data System (ADS)

Li, Jian; Huang, Rongjin; Li, Xu; Xu, Dong; Liu, Huiming; Li, Laifeng

2017-09-01

Impregnating resins as electrical insulation materials for use in ITER magnets and feeder system are required to be radiation stable, good mechanical performance and high voltage electrical breakdown strength. In present ITER project, the breakdown strength need over 30 kV/mm, for future DEMO reactor, it will be greater than this value. In order to develop good property insulation materials to satisfy the requirements of future fusion reactor, high voltage breakdown strength measurement system at low temperature is necessary. In this paper, we will introduce our work on the design of this system. This measuring system has two parts: one is an electrical supply system which provides the high voltage from a high voltage power between two electrodes; the other is a cooling system which consists of a G-M cryocooler, a superfluid chamber and a heat switch. The two stage G-M cryocooler pre-cool down the system to 4K, the superfluid helium pot is used for a container to depress the helium to superfluid helium which cool down the sample to 1.8K and a mechanical heat switch connect or disconnect the cryocooler and the pot. In order to provide the sufficient time for the test, the cooling system is designed to keep the sample at 1.8K for 300 seconds.

Self-compacting geopolymer concrete-a review

NASA Astrophysics Data System (ADS)

Ukesh Praveen, P.; Srinivasan, K.

2017-11-01

In this construction world, Geopolymer concrete is a special concrete which doesn’t requires the Ordinary Portland Cement and also reduces the emission of carbon-dioxide. The Geopolymer Concrete is made up of industrial by-products (which contains more Silica and Alumina) and activated with the help of Alkaline solution (combination of sodium hydroxide & sodium silicate or potassium hydroxide & potassium silicate). The high viscosity nature of Geopolymer Concrete had the ability to fail due to lack of compaction. In improvising the issue, Self Compacting Geopolymer Concrete has been introduced. The SCGC doesn’t require any additional compaction it will flow and compacted by its own weight. This concrete is made up of industrial by-products like Fly ash, GGBFS and Silica Fume and activated with alkaline solution. The earlier research was mostly on Fly ash based SCGC. In few research works Fly ash was partially replaced with GGBS and Silica Fume. They evaluated the compressive strength of concrete with varying molarities of NaOH; curing time and curing temperature. The flexural behaviour of the concrete also examined. The Fly ash based SCGC was got high compressive strength in heat curing as well as low compressive strength in ambient curing. The presence of GGBS improves the strength in ambient curing. For aiming the high strength in ambient curing Fly ash will be completely replace and examine with different mineral admixtures.

Shoulder Strength Requirements for Upper Limb Functional Tasks: Do Age and Rotator Cuff Tear Status Matter?

PubMed

Santago, Anthony C; Vidt, Meghan E; Li, Xiaotong; Tuohy, Christopher J; Poehling, Gary G; Freehill, Michael T; Saul, Katherine R

2017-12-01

Understanding upper limb strength requirements for daily tasks is imperative for early detection of strength loss that may progress to disability due to age or rotator cuff tear. We quantified shoulder strength requirements for 5 upper limb tasks performed by 3 groups: uninjured young adults and older adults, and older adults with a degenerative supraspinatus tear prior to repair. Musculoskeletal models were developed for each group representing age, sex, and tear-related strength losses. Percentage of available strength used was quantified for the subset of tasks requiring the largest amount of shoulder strength. Significant differences in strength requirements existed across tasks: upward reach 105° required the largest average strength; axilla wash required the largest peak strength. However, there were limited differences across participant groups. Older adults with and without a tear used a larger percentage of their shoulder elevation (p < .001, p < .001) and external rotation (p < .001, p = .017) strength than the young adults, respectively. Presence of a tear significantly increased percentage of internal rotation strength compared to young (p < .001) and uninjured older adults (p = .008). Marked differences in strength demand across tasks indicate the need for evaluating a diversity of functional tasks to effectively detect early strength loss, which may lead to disability.

A Rational Approach to Determine Minimum Strength Thresholds in Novel Structural Materials

NASA Technical Reports Server (NTRS)

Schur, Willi W.; Bilen, Canan; Sterling, Jerry

2003-01-01

Design of safe and survivable structures requires the availability of guaranteed minimum strength thresholds for structural materials to enable a meaningful comparison of strength requirement and available strength. This paper develops a procedure for determining such a threshold with a desired degree of confidence, for structural materials with none or minimal industrial experience. The problem arose in attempting to use a new, highly weight-efficient structural load tendon material to achieve a lightweight super-pressure balloon. The developed procedure applies to lineal (one dimensional) structural elements. One important aspect of the formulation is that it extrapolates to expected probability distributions for long length specimen samples from some hypothesized probability distribution that has been obtained from a shorter length specimen sample. The use of the developed procedure is illustrated using both real and simulated data.

49 CFR 195.112 - New pipe.

Code of Federal Regulations, 2013 CFR

2013-10-01

... with the following: (a) The pipe must be made of steel of the carbon, low alloy-high strength, or alloy... sets forth the chemical requirements for the pipe steel and mechanical tests for the pipe to provide... made, the specified minimum yield strength or grade, and the pipe size. The marking must be applied in...

49 CFR 195.112 - New pipe.

Code of Federal Regulations, 2012 CFR

2012-10-01

... with the following: (a) The pipe must be made of steel of the carbon, low alloy-high strength, or alloy... sets forth the chemical requirements for the pipe steel and mechanical tests for the pipe to provide... made, the specified minimum yield strength or grade, and the pipe size. The marking must be applied in...

49 CFR 195.112 - New pipe.

Code of Federal Regulations, 2014 CFR

2014-10-01

... with the following: (a) The pipe must be made of steel of the carbon, low alloy-high strength, or alloy... sets forth the chemical requirements for the pipe steel and mechanical tests for the pipe to provide... made, the specified minimum yield strength or grade, and the pipe size. The marking must be applied in...

49 CFR 195.112 - New pipe.

Code of Federal Regulations, 2011 CFR

2011-10-01

... with the following: (a) The pipe must be made of steel of the carbon, low alloy-high strength, or alloy... sets forth the chemical requirements for the pipe steel and mechanical tests for the pipe to provide... made, the specified minimum yield strength or grade, and the pipe size. The marking must be applied in...

49 CFR 195.112 - New pipe.

Code of Federal Regulations, 2010 CFR

2010-10-01

... with the following: (a) The pipe must be made of steel of the carbon, low alloy-high strength, or alloy... sets forth the chemical requirements for the pipe steel and mechanical tests for the pipe to provide... made, the specified minimum yield strength or grade, and the pipe size. The marking must be applied in...

Burst strength of tubing and casing based on twin shear unified strength theory.

PubMed

Lin, Yuanhua; Deng, Kuanhai; Sun, Yongxing; Zeng, Dezhi; Liu, Wanying; Kong, Xiangwei; Singh, Ambrish

2014-01-01

The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

Burst Strength of Tubing and Casing Based on Twin Shear Unified Strength Theory

PubMed Central

Lin, Yuanhua; Deng, Kuanhai; Sun, Yongxing; Zeng, Dezhi; Liu, Wanying; Kong, Xiangwei; Singh, Ambrish

2014-01-01

The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells. PMID:25397886

Limits on rock strength under high confinement

NASA Astrophysics Data System (ADS)

Renshaw, Carl E.; Schulson, Erland M.

2007-06-01

Understanding of deep earthquake source mechanisms requires knowledge of failure processes active under high confinement. Under low confinement the compressive strength of rock is well known to be limited by frictional sliding along stress-concentrating flaws. Under higher confinement strength is usually assumed limited by power-law creep associated with the movement of dislocations. In a review of existing experimental data, we find that when the confinement is high enough to suppress frictional sliding, rock strength increases as a power-law function only up to a critical normalized strain rate. Within the regime where frictional sliding is suppressed and the normalized strain rate is below the critical rate, both globally distributed ductile flow and localized brittle-like failure are observed. When frictional sliding is suppressed and the normalized strain rate is above the critical rate, failure is always localized in a brittle-like manner at a stress that is independent of the degree of confinement. Within the high-confinement, high-strain rate regime, the similarity in normalized failure strengths across a variety of rock types and minerals precludes both transformational faulting and dehydration embrittlement as strength-limiting mechanisms. The magnitude of the normalized failure strength corresponding to the transition to the high-confinement, high-strain rate regime and the observed weak dependence of failure strength on strain rate within this regime are consistent with a localized Peierls-type strength-limiting mechanism. At the highest strain rates the normalized strengths approach the theoretical limit for crystalline materials. Near-theoretical strengths have previously been observed only in nano- and micro-scale regions of materials that are effectively defect-free. Results are summarized in a new deformation mechanism map revealing that when confinement and strain rate are sufficient, strengths approaching the theoretical limit can be achieved in cm-scale sized samples of rocks rich in defects. Thus, non-frictional failure processes must be considered when interpreting rock deformation data collected under high confinement and low temperature. Further, even at higher temperatures the load-bearing ability of crustal rocks under high confinement may not be limited by a frictional process under typical geologic strain rates.

Local heat treatment of high strength steels with zoom-optics and 10kW-diode laser

NASA Astrophysics Data System (ADS)

Baumann, Markus; Krause, Volker; Bergweiler, Georg; Flaischerowitz, Martin; Banik, Janko

2012-03-01

High strength steels enable new solutions for weight optimized car bodies without sacrificing crash safety. However, cold forming of these steels is limited due to the need of high press capacity, increased tool wear, and limitations in possible geometries. One can compensate for these drawbacks by local heat treatment of the blanks. In high-deformation areas the strength of the material is reduced and the plasticity is increased by diode laser irradiation. Local heat treatment with diode laser radiation could also yield key benefits for the applicability of press hardened parts. High strength is not desired all over the part. Joint areas or deformation zones for requested crash properties require locally reduced strength. In the research project "LOKWAB" funded by the German Federal Ministry of Education and Research (BMBF), heat treatment of high strength steels was investigated in cooperation with Audi, BMW, Daimler, ThyssenKrupp, Fraunhofer- ILT, -IWU and others. A diode laser with an output power of 10 kW was set up to achieve acceptable process speed. Furthermore a homogenizing zoom-optics was developed, providing a rectangular focus with homogeneous power density. The spot size in x- and y-direction can be changed independently during operation. With pyrometer controlled laser power the surface temperature is kept constant, thus the laser treated zone can be flexibly adapted to the needs. Deep-drawing experiments show significant improvement in formability. With this technique, parts can be manufactured, which can conventionally only be made of steel with lower strength. Locally reduced strength of press hardened serial parts was demonstrated.

Ternary blends containing demercurated lighting phosphor and MSWI fly ash as high-performance binders for stabilizing and recycling electroplating sludge.

PubMed

Huang, Wu-Jang; Wu, Chia-Teng; Wu, Chang-En; Hsieh, Lin-Huey; Li, Chang-Chien; Lain, Chi-Yuan; Chu, Wei

2008-08-15

This paper describes the solidification and stabilization of electroplating sludge treated with a high-performance binder made from portland type-I cement, municipal solid waste incineration fly ash, and lighting phosphor powder (called as cement-fly ash-phosphor binder, CFP). The highest 28-day unconfined compressive strength of the CFP-treated paste was 816 kg/cm(2) at a ratio of cement to fly ash to lighting phosphor powder of 90:5:5; the strength of this composition also fulfilled the requirement of a high-strength concrete (>460 kg/cm(2) at 28 days). The CFP-stabilized sludge paste samples passed the Taiwanese EPA toxicity characteristic leaching procedure test and, therefore, could be used either as a building material or as a controlled low-strength material, depending on the sludge-to-CFP binder ratio.

The interfacial strength of carbon nanofiber epoxy composite using single fiber pullout experiments.

PubMed

Manoharan, M P; Sharma, A; Desai, A V; Haque, M A; Bakis, C E; Wang, K W

2009-07-22

Carbon nanotubes and nanofibers are extensively researched as reinforcing agents in nanocomposites for their multifunctionality, light weight and high strength. However, it is the interface between the nanofiber and the matrix that dictates the overall properties of the nanocomposite. The current trend is to measure elastic properties of the bulk nanocomposite and then compare them with theoretical models to extract the information on the interfacial strength. The ideal experiment is single fiber pullout from the matrix because it directly measures the interfacial strength. However, the technique is difficult to apply to nanocomposites because of the small size of the fibers and the requirement for high resolution force and displacement sensing. We present an experimental technique for measuring the interfacial strength of nanofiber-reinforced composites using the single fiber pullout technique and demonstrate the technique for a carbon nanofiber-reinforced epoxy composite. The experiment is performed in situ in a scanning electron microscope and the interfacial strength for the epoxy composite was measured to be 170 MPa.

The Bendability of Ultra High strength Steels

NASA Astrophysics Data System (ADS)

Hazra, S. K.; Efthymiadis, P.; Alamoudi, A.; Kumar, R. L. V.; Shollock, B.; Dashwood, R.

2016-08-01

Automotive manufacturers have been reducing the weight of their vehicles to meet increasingly stringent environmental legislation that reflects public demand. A strategy is to use higher strength materials for parts with reduced cross-sections. However, such materials are less formable than traditional grades. The frequent result is increased processing and piece costs. 3D roll forming is a novel and flexible process: it is estimated that a quarter of the structure of a vehicle can be made with a single set of tooling. Unlike stamping, this process requires material with low work hardening rates. In this paper, we present results of ultra high strength steels that have low elongation in a tension but display high formability in bending through the suppression of the necking response.

Metal-Matrix/Hollow-Ceramic-Sphere Composites

NASA Technical Reports Server (NTRS)

Baker, Dean M.

2011-01-01

A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

I-15 reconstruction long-term embankment monitoring study : final report.

DOT National Transportation Integrated Search

2012-05-01

The I-15 Reconstruction Project in Salt Lake City, Utah required rapid embankment construction in an urban environment atop soft lacustrine soils. These soils are thick, highly compressible, have low shear strength and require significant time to com...

High Temperature Structural Foam

NASA Technical Reports Server (NTRS)

Weiser, Erik S.; Baillif, Faye F.; Grimsley, Brian W.; Marchello, Joseph M.

1997-01-01

The Aerospace Industry is experiencing growing demand for high performance polymer foam. The X-33 program needs structural foam insulation capable of retaining its strength over a wide range of environmental conditions. The High Speed Research Program has a need for low density core splice and potting materials. This paper reviews the state of the art in foam materials and describes experimental work to fabricate low density, high shear strength foam which can withstand temperatures from -220 C to 220 C. Commercially available polymer foams exhibit a wide range of physical properties. Some with densities as low as 0.066 g/cc are capable of co-curing at temperatures as high as 182 C. Rohacell foams can be resin transfer molded at temperatures up to 180 C. They have moduli of elasticity of 0.19 MPa, tensile strengths of 3.7 Mpa and compressive strengths of 3.6 MPa. The Rohacell foams cannot withstand liquid hydrogen temperatures, however Imi-Tech markets Solimide (trademark) foams which withstand temperatures from -250 C to 200 C, but they do not have the required structural integrity. The research activity at NASA Langley Research Center focuses on using chemical blowing agents to produce polyimide thermoplastic foams capable of meeting the above performance requirements. The combination of blowing agents that decompose at the minimum melt viscosity temperature together with plasticizers to lower the viscosity has been used to produce foams by both extrusion and oven heating. The foams produced exhibit good environmental stability while maintaining structural properties.

Combined coagulation-flocculation and sequencing batch reactor with phosphorus adjustment for the treatment of high-strength landfill leachate: experimental kinetics and chemical oxygen demand fractionation.

PubMed

El-Fadel, M; Matar, F; Hashisho, J

2013-05-01

The treatability of high-strength landfill leachate is challenging and relatively limited. This study examines the feasibility of treating high-strength landfill leachate (chemical oxygen demand [COD]: 7,760-11,770 mg/L, biochemical oxygen demand [BOD5]: 2,760-3,569 mg/L, total nitrogen [TN] = 980-1,160 mg/L) using a sequencing batch reactor (SBR) preceded by a coagulation-flocculation process with phosphorus nutritional balance under various mixing and aeration patterns. Simulations were also conducted to define kinetic parameters and COD fractionation. Removal efficiencies reached 89% for BOD5, 60% for COD, and 72% for TN, similar to and better than reported studies, albeit with a relatively lower hydraulic retention time (HRT) and solid retention time (SRT). The coupled experimental and simulation results contribute in filling a gap toward managing high-strength landfill leachate and providing guidelines for corresponding SBR applications. The treatability of high-strength landfill leachate, which is challenging and relatively limited, was demonstrated using a combined coagulation-flocculation with SBR technology and nutrient balance adjustment. The most suitable coagulant, kinetic design parameters, and COD fractionation were defined using coupled experimental and simulation results contributing in filling a gap toward managing high-strength leachate by providing guidelines for corresponding SBR applications and anticipating potential constraints related to the non-biodegradable COD fraction. In this context, while the combined coagulation-flocculation and SBR process improved removal efficiencies, posttreatment may be required for high-strength leachate, depending on discharge standards and ultimate usage of the treated leachate.

47 CFR 80.753 - Signal strength requirements at the service area contour.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Signal strength requirements at the service... Station VHF Coverage § 80.753 Signal strength requirements at the service area contour. (a) The requirements for reception by a marine VHF shipboard receiver are satisfied if the field strength from the...

47 CFR 80.753 - Signal strength requirements at the service area contour.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Signal strength requirements at the service... Station VHF Coverage § 80.753 Signal strength requirements at the service area contour. (a) The requirements for reception by a marine VHF shipboard receiver are satisfied if the field strength from the...

Updated Review of the Applied Physiology of American College Football: Physical Demands, Strength and Conditioning, Nutrition, and Injury Characteristics of America's Favorite Game.

PubMed

Fullagar, Hugh H K; McCunn, Robert; Murray, Andrew

2017-11-01

While there are various avenues for performance improvement in college American football (AF), there is no comprehensive evaluation of the collective array of resources around performance, physical conditioning, and injury and training/game characteristics to guide future research and inform practitioners. Accordingly, the aim of the present review was to provide a current examination of these areas in college AF. Recent studies show that there is a wide range of body compositions and strength characteristics between players, which appear to be influenced by playing position, level of play, training history/programming, and time of season. Collectively, game demands may require a combination of upper- and lower-body strength and power production, rapid acceleration (positive and negative), change of direction, high running speed, high-intensity and repetitive collisions, and muscle-strength endurance. These may be affected by the timing of and between-plays and/or coaching style. AF players appear to possess limited nutrition and hydration practices, which may be disadvantageous to performance. AF injuries appear due to a multitude of factors-strength, movement quality, and previous injury-while there is also potential for extrinsic factors such as playing surface type, travel, time of season, playing position, and training load. Future proof-of-concept studies are required to determine the quantification of game demands with regard to game style, type of opposition, and key performance indicators. Moreover, more research is required to understand the efficacy of recovery and nutrition interventions. Finally, the assessment of the relationship between external/internal-load constructs and injury risk is warranted.

Creep Strength of Nb-1Zr for SP-100 Applications

NASA Astrophysics Data System (ADS)

Horak, James A.; Egner, Larry K.

1994-07-01

Power systems that are used to provide electrical power in space are designed to optimize conversion of thermal energy to electrical energy and to minimize the mass and volume that must be launched. Only refractory metals and their alloys have sufficient long-term strength for several years of uninterrupted operation at the required temperatures of 1200 K and above. The high power densities and temperatures at which these reactors must operate require the use of liquid-metal coolants. The alloy Nb-1 wt % Zr (Nb-lZr), which exhibits excellent corrosion resistance to alkali liquid-metals at high temperatures, is being considered for the fuel cladding, reactor structural, and heat-transport systems for the SP-100 reactor system. Useful lifetime of this system is limited by creep deformation in the reactor core. Nb-lZr sheet procured to American Society for Testing and Materials (ASTM) specifications for reactor grade and commercial grade has been processed by several different cold work and annealing treatments to attempt to produce the grain structure (size, shape, and distribution of sizes) that provides the maximum creep strength of this alloy at temperatures from 1250 to 1450 K. The effects of grain size, differences in oxygen concentrations, tungsten concentrations, and electron beam and gas tungsten arc weldments on creep strength were studied. Grain size has a large effect on creep strength at 1450 K but only material with a very large grain size (150 μm) exhibits significantly higher creep strength at 1350 K. Differences in oxygen or tungsten concentrations did not affect creep strength, and the creep strengths of weldments were equal to, or greater than, those for base metal.

Modern high-strength steels for heavily loaded gearing (a review of engineering patents)

NASA Astrophysics Data System (ADS)

Voronenko, B. I.

1996-08-01

In order to increase the service life of machines the life of their parts should be increased. For example, in machine tool and lifting-and-transport manufacture the maintenance cost of the equipment over the duration of its operation often exceeds the cost of the new equipment by a factor of 10-20. This imposes strict requirements on structural materials for heavily loaded gearings, including the development of high-strength, wear-resistant, manufacture-adaptable, and economically alloyed steels.

Developing radiopure copper alloys for high strength low background applications

NASA Astrophysics Data System (ADS)

Suriano, A. M.; Howard, S. M.; Christofferson, C. D.; Arnquist, I. J.; Hoppe, E. W.

2018-01-01

High purity copper continues to play an important role for ultra-low-background detectors. Measurements of rare nuclear decays, e.g. neutrinoless double-beta decay, and searches for dark matter can require construction materials that have high thermal and electrical conductivity with bulk radiopurity less than one micro-Becquerel per kilogram. However, experiments currently using components constructed of radiopure electroformed copper struggle with design of structural and mechanical parts due to the physical properties of pure copper. A higher strength material which possesses many of the favorable attributes of copper yet remains radiopure is desired. A number of copper alloying candidates which may provide improved mechanical performance and adequate radiopurity were considered. Development of an electrodeposited copper-chrome alloy from additive-free electrolyte systems is discussed. The resulting material is shown to possess high strength and meets the aforementioned radiopurity goals.

The effect of steel slag as a coarse aggregate and Sinabung volcanic ash a filler on high strength concrete

NASA Astrophysics Data System (ADS)

Karolina, R.; Putra, A. L. A.

2018-02-01

The Development of concrete technology is continues to grow. The requisite for efficient constructions that are often viewed in terms of concrete mechanical behavior, application on the field, and cost estimation of implementation increasingly require engineers to optimize construction materials, especially for concrete materials. Various types of concrete have now been developed according to their needs, such as high strength concrete. On high strength concrete design, it is necessary to consider several factors that will affect the reach of the quality strength, Those are cement, water cement ratio (w/c), aggregates, and proper admixture. In the use of natural mineral, it is important for an engineer to keep an eye on the natural conditions that have been explored. So the selection of aggregates as possible is a material that is not causing nature destruction. On this experiment the use of steel slag from PT.Growth Sumatra Industry as a substitute of coarse and fine aggregate, and volcanic ash of mount Sinabung as microsilka in concrete mixture substituted to create high strength concrete that is harmless for the environment. The use of mount sinabung volcanic ash as microsilika coupled with the use of Master Glenium Sky 8614 superplasticizer. This experiment intend to compare high strength concrete based slag steel as the main constituent aggregates and high strength concrete with a conventional mixture. The research result for 28 days old concrete shows that conventional concrete compressive strength is 67.567 MPa, slag concrete 75.958 Mpa, conventional tensile strength 5.435 Mpa while slag concrete 5.053 Mpa, conventional concrete bending strength 44064.96 kgcm while concrete slag 51473.94 kgcm and modulus of conventional concrete fracture 124.978 kg / cm2 while slag concrete 145.956 kg / cm2. Both concrete slump values shows similar results due to the use of superplasticizer.

Homogeneous/Inhomogeneous-Structured Dielectrics and their Energy-Storage Performances.

PubMed

Yao, Zhonghua; Song, Zhe; Hao, Hua; Yu, Zhiyong; Cao, Minghe; Zhang, Shujun; Lanagan, Michael T; Liu, Hanxing

2017-05-01

The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Fidelity Tape Transfer Printing Based On Chemically Induced Adhesive Strength Modulation

NASA Astrophysics Data System (ADS)

Sim, Kyoseung; Chen, Song; Li, Yuhang; Kammoun, Mejdi; Peng, Yun; Xu, Minwei; Gao, Yang; Song, Jizhou; Zhang, Yingchun; Ardebili, Haleh; Yu, Cunjiang

2015-11-01

Transfer printing, a two-step process (i.e. picking up and printing) for heterogeneous integration, has been widely exploited for the fabrication of functional electronics system. To ensure a reliable process, strong adhesion for picking up and weak or no adhesion for printing are required. However, it is challenging to meet the requirements of switchable stamp adhesion. Here we introduce a simple, high fidelity process, namely tape transfer printing(TTP), enabled by chemically induced dramatic modulation in tape adhesive strength. We describe the working mechanism of the adhesion modulation that governs this process and demonstrate the method by high fidelity tape transfer printing several types of materials and devices, including Si pellets arrays, photodetector arrays, and electromyography (EMG) sensors, from their preparation substrates to various alien substrates. High fidelity tape transfer printing of components onto curvilinear surfaces is also illustrated.

Influence of Composition and Deformation Conditions on the Strength and Brittleness of Shale Rock

NASA Astrophysics Data System (ADS)

Rybacki, E.; Reinicke, A.; Meier, T.; Makasi, M.; Dresen, G. H.

2015-12-01

Stimulation of shale gas reservoirs by hydraulic fracturing operations aims to increase the production rate by increasing the rock surface connected to the borehole. Prospective shales are often believed to display high strength and brittleness to decrease the breakdown pressure required to (re-) initiate a fracture as well as slow healing of natural and hydraulically induced fractures to increase the lifetime of the fracture network. Laboratory deformation tests were performed on several, mainly European black shales with different mineralogical composition, porosity and maturity at ambient and elevated pressures and temperatures. Mechanical properties such as compressive strength and elastic moduli strongly depend on shale composition, porosity, water content, structural anisotropy, and on pressure (P) and temperature (T) conditions, but less on strain rate. We observed a transition from brittle to semibrittle deformation at high P-T conditions, in particular for high porosity shales. At given P-T conditions, the variation of compressive strength and Young's modulus with composition can be roughly estimated from the volumetric proportion of all components including organic matter and pores. We determined also brittleness index values based on pre-failure deformation behavior, Young's modulus and bulk composition. At low P-T conditions, where samples showed pronounced post-failure weakening, brittleness may be empirically estimated from bulk composition or Young's modulus. Similar to strength, at given P-T conditions, brittleness depends on the fraction of all components and not the amount of a specific component, e.g. clays, alone. Beside strength and brittleness, knowledge of the long term creep properties of shales is required to estimate in-situ stress anisotropy and the healing of (propped) hydraulic fractures.

49 CFR 571.223 - Standard No. 223; Rear impact guards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... member necessary to achieve a 100 mm high projected vertical height are located not more than 305 mm... Figure 1 of this section. S5.2 Strength and Energy Absorption. When tested under the procedures of S6 of this section, each guard shall comply with the strength requirements of S5.2.1 of this section at each...

49 CFR 571.223 - Standard No. 223; Rear impact guards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... member necessary to achieve a 100 mm high projected vertical height are located not more than 305 mm... Figure 1 of this section. S5.2 Strength and Energy Absorption. When tested under the procedures of S6 of this section, each guard shall comply with the strength requirements of S5.2.1 of this section at each...

49 CFR 571.223 - Standard No. 223; Rear impact guards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... member necessary to achieve a 100 mm high projected vertical height are located not more than 305 mm... Figure 1 of this section. S5.2 Strength and Energy Absorption. When tested under the procedures of S6 of this section, each guard shall comply with the strength requirements of S5.2.1 of this section at each...

49 CFR 571.223 - Standard No. 223; Rear impact guards.

Code of Federal Regulations, 2011 CFR

2011-10-01

... member necessary to achieve a 100 mm high projected vertical height are located not more than 305 mm... Figure 1 of this section. S5.2 Strength and Energy Absorption. When tested under the procedures of S6 of this section, each guard shall comply with the strength requirements of S5.2.1 of this section at each...

49 CFR 571.223 - Standard No. 223; Rear impact guards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... member necessary to achieve a 100 mm high projected vertical height are located not more than 305 mm... Figure 1 of this section. S5.2 Strength and Energy Absorption. When tested under the procedures of S6 of this section, each guard shall comply with the strength requirements of S5.2.1 of this section at each...

Development in high-grade dual phase steels with low C and Si design

NASA Astrophysics Data System (ADS)

Zhu, Guo-hui; Zhang, Xue-hui; Mao, Wei-min

2009-12-01

Cold rolled dual phase steels with low C and Si addition were investigated in terms of combination of composition and processing in order to improve mechanical properties and workability including welding and galvanizing. Mo and Cr could be used as alloying elements to partially replace C and Si to assure enough hardening ability of the steels and also give solute-hardening. Mo addition is more effective than Cr addition in terms of obtaining the required volume fraction of martensite and mechanical strength. The ferrite grain was effectively refined by addition of Nb microalloying, which gives optimized mechanical properties. The experimental results show that it is possible to obtain the required mechanical properties of high grade 800 MPa dual phase steel, i.e., tensile strength > 780 MPa, elongation > 15%, and yield/tensile strength ratio < 0.6 in the condition of low carbon (C < 0.11 wt.%) and low silicon design (Si < 0.05 wt.%) through adequate combination of composition and processing.

Metal-Phenolic Carbon Nanocomposites for Robust and Flexible Energy-Storage Devices.

PubMed

Oh, Jun Young; Jung, Yeonsu; Cho, Young Shik; Choi, Jaeyoo; Youk, Ji Ho; Fechler, Nina; Yang, Seung Jae; Park, Chong Rae

2017-04-22

Future electronics applications such as wearable electronics depend on the successful construction of energy-storage devices with superior flexibility and high electrochemical performance. However, these prerequisites are challenging to combine: External forces often cause performance degradation, whereas the trade-off between the required nanostructures for strength and electrochemical performance only results in diminished energy storage. Herein, a flexible supercapacitor based on tannic acid (TA) and carbon nanotubes (CNTs) with a unique nanostructure is presented. TA was self-assembled on the surface of the CNTs by metal-phenolic coordination bonds, which provides the hybrid film with both high strength and high pseudocapacitance. Besides 17-fold increased mechanical strength of the final composite, the hybrid film simultaneously exhibits excellent flexibility and volumetric capacitance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strength Estimation for Hydrate-Bearing Sediments From Direct Shear Tests of Hydrate-Bearing Sand and Silt

NASA Astrophysics Data System (ADS)

Liu, Zhichao; Dai, Sheng; Ning, Fulong; Peng, Li; Wei, Houzhen; Wei, Changfu

2018-01-01

Safe and economic methane gas production, as well as the replacement of methane while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding of the strength and volume responses of hydrate-bearing sediments during shear. This study employs a custom-made apparatus to investigate the mechanical and volumetric behaviors of carbon dioxide hydrate-bearing sediments subjected to direct shear. The results show that both peak and residual strengths increase with increased hydrate saturation and vertical stress. Hydrate contributes mainly the cohesion and dilatancy constraint to the peak strength of hydrate-bearing sediments. The postpeak strength reduction is more evident and brittle in specimens with higher hydrate saturation and under lower stress. Significant strength reduction after shear failure is expected in silty sediments with high hydrate saturation Sh ≥ 0.65. Hydrate contribution to the residual strength is mainly by increasing cohesion at low hydrate saturation and friction at high hydrate saturation. Stress state and hydrate saturation are dominating both the stiffness and the strength of hydrate-bearing sediments; thus, a wave velocity-based peak strength prediction model is proposed and validated, which allows for precise estimation of the shear strength of hydrate-bearing sediments through acoustic logging data. This method is advantageous to geomechanical simulators, particularly when the experimental strength data of natural samples are not available.

46 CFR 160.049-3 - Materials.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... Cotton fabrics and coated upholstery cloth meeting the minimum requirements set forth in paragraphs (c... Type I, Class 3 material. (2) Coated upholstery cloth. Coated upholstery cloth shall comply with the..., class I, laminated vinyl-nylon high strength cloth in accordance with the requirements of Specification...

46 CFR 160.049-3 - Materials.

Code of Federal Regulations, 2013 CFR

2013-10-01

.... Cotton fabrics and coated upholstery cloth meeting the minimum requirements set forth in paragraphs (c... Type I, Class 3 material. (2) Coated upholstery cloth. Coated upholstery cloth shall comply with the..., class I, laminated vinyl-nylon high strength cloth in accordance with the requirements of Specification...

46 CFR 160.049-3 - Materials.

Code of Federal Regulations, 2012 CFR

2012-10-01

.... Cotton fabrics and coated upholstery cloth meeting the minimum requirements set forth in paragraphs (c... Type I, Class 3 material. (2) Coated upholstery cloth. Coated upholstery cloth shall comply with the..., class I, laminated vinyl-nylon high strength cloth in accordance with the requirements of Specification...

49 CFR 192.505 - Strength test requirements for steel pipeline to operate at a hoop stress of 30 percent or more...

Code of Federal Regulations, 2013 CFR

2013-10-01

... sections of pipe, for which a post installation test is impractical, a preinstallation strength test must... 49 Transportation 3 2013-10-01 2013-10-01 false Strength test requirements for steel pipeline to...: MINIMUM FEDERAL SAFETY STANDARDS Test Requirements § 192.505 Strength test requirements for steel pipeline...

Filler metal selection for welding a high nitrogen stainless steel

NASA Astrophysics Data System (ADS)

Du Toit, Madeleine

2002-06-01

Cromanite is a high-strength austenitic stainless steel that contains approximately 19% chromium, 10% manganese, and 0.5% nitrogen. It can be welded successfully, but due to the high nitrogen content of the base metal, precautions have to be taken to ensure sound welds with the desired combination of properties. Although no matching filler metals are currently available, Cromanite can be welded using a range of commercially available stainless steel welding consumables. E307 stainless steel, the filler metal currently recommended for joining Cromanite, produces welds with mechanical properties that are generally inferior to those of the base metal. In wear applications, these lower strength welds would probably be acceptable, but in applications where full use is made of the high strength of Cromanite, welds with matching strength levels would be required. In this investigation, two welding consumables, ER2209 (a duplex austenitic-ferritic stainless steel) and 15CrMn (an austenitic-manganese hardfacing wire), were evaluated as substitutes for E307. When used to join Cromanite, 15CrMn produced welds displaying severe nitrogen-induced porosity, and this consumable is therefore not recommended. ER2209, however, outperformed E307, producing sound porosity-free welds with excellent mechanical properties, including high ductility and strength levels exceeding the minimum limits specified for Cromanite.

Evaluation of the cryogenic mechanical properties of the insulation material for ITER Feeder superconducting joint

NASA Astrophysics Data System (ADS)

Wu, Zhixiong; Huang, Rongjin; Huang, ChuanJun; Yang, Yanfang; Huang, Xiongyi; Li, Laifeng

2017-12-01

The Glass-fiber reinforced plastic (GFRP) fabricated by the vacuum bag process was selected as the high voltage electrical insulation and mechanical support for the superconducting joints and the current leads for the ITER Feeder system. To evaluate the cryogenic mechanical properties of the GFRP, the mechanical properties such as the short beam strength (SBS), the tensile strength and the fatigue fracture strength after 30,000 cycles, were measured at 77K in this study. The results demonstrated that the GFRP met the design requirements of ITER.

Material Properties Analysis of Structural Members in Pumpkin Balloons

NASA Technical Reports Server (NTRS)

Sterling, W. J.

2003-01-01

The efficient design, service-life qualification, and reliability predictions for lightweight aerospace structures require careful mechanical properties analysis of candidate structural materials. The demand for high-quality laboratory data is particularly acute when the candidate material or the structural design has little history. The pumpkin-shaped super-pressure balloon presents both challenges. Its design utilizes load members (tendons) extending from apex to base around the gas envelope to achieve a lightweight structure. The candidate tendon material is highly weight-efficient braided HM cord. Previous mechanical properties studies of Zylon have focused on fiber and yarn, and industrial use of the material in tensile applications is limited. For high-performance polymers, a carefully plamed and executed properties analysis scheme is required to ensure the data are relevant to the desired application. Because no directly-applicable testing standard was available, a protocol was developed based on guidelines fiom professional and industry organizations. Due to the liquid-crystalline nature of the polymer, the cord is very stiff, creeps very little, and does not yield. Therefore, the key material property for this application is the breaking strength. The pretension load and gauge length were found to have negligible effect on the measured breaking strength over the ranges investigated. Strain rate was found to have no effect on breaking strength, within the range of rates suggested by the standards organizations. However, at the lower rate more similar to ULDB operations, the strength was reduced. The breaking strength increased when the experiment temperature was decreased from ambient to 183K which is the lowest temperature ULDB is expected to experience. The measured strength under all test conditions was well below that resulting from direct scale-up of fiber strength based on the manufacturers data. This expected result is due to the effects of the braiding process and material ageing.

A novel anchoring system for use in a nonfusion scoliosis correction device.

PubMed

Wessels, Martijn; Homminga, Jasper J; Hekman, Edsko E G; Verkerke, Gijsbertus J

2014-11-01

Insertion of a pedicle screw in the mid- and high thoracic regions has a serious risk of facet joint damage. Because flexible implant systems require intact facet joints, we developed an enhanced fixation that is less destructive to spinal structures. The XSFIX is a posterior fixation system that uses cables that are attached to the transverse processes of a vertebra. To determine whether a fixation to the transverse process using the XSFIX is strong enough to withstand the loads applied by the XSLATOR (a novel, highly flexible nonfusion implant system) and thus, whether it is a suitable alternative for pedicle screw fixation. The strength of a novel fixation system using transverse process cables was determined and compared with the strength of a similar fixation using polyaxial pedicle screws on different vertebral levels. Each of the 58 vertebrae, isolated from four adult human cadavers, was instrumented with either a pedicle screw anchor (PSA) system or a prototype of the XSFIX. The PSA consisted of two polyaxial pedicle screws and a 5 mm diameter rod. The XSFIX prototype consisted of two bodies that were fixed to the transverse processes, interconnected with a similar rod. Each fixation system was subjected to a lateral or an axial torque. The PSA demonstrated fixation strength in lateral loading and torsion higher than required for use in the XSLATOR. The XSFIX demonstrated high enough fixation strength (in both lateral loading and torsion), only in the high and midthoracic regions (T10-T12). This experiment showed that the fixation strength of XSFIX is sufficient for use with the XSLATOR only in mid- and high thoracic regions. For the low thoracic and lumbar region, the PSA is a more rigid fixation. Because the performance of the new fixation system appears to be favorable in the high and midthoracic regions, a clinical study is the next challenge. Copyright © 2014 Elsevier Inc. All rights reserved.

High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

2002-01-01

In this paper, a new high strength and wear resistant aluminum cast alloy invented by NASA-MSFC for high temperature applications will be presented. Developed to meet U.S. automotive legislation requiring low-exhaust emission, the novel NASA 398 aluminum-silicon alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (500 F-800 F), enabling new pistons to utilize less material, which can lead to reducing part weight and cost as well as improving performance. NASA 398 alloy also offers greater wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys for several commercial and automotive applications. The new alloy can be produced economically using permanent steel molds from conventional gravity casting or sand casting. The technology was developed to stimulate the development of commercial aluminum casting products from NASA-developed technology by offering companies the opportunity to license this technology.

Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.

2003-01-01

In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

Constitutive Model Constants for Al7075-T651 and Al7075-T6

NASA Astrophysics Data System (ADS)

Brar, N. S.; Joshi, V. S.; Harris, B. W.

2009-12-01

Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these materials. Although the two tempers show similar elongation at breakage, the ultimate tensile strength of T651 temper is generally lower than the T6 temper. Johnson-Cook strength model constants (A, B, n, C, and m) for the two alloys are determined from high strain rate tension stress-strain data at room and high temperature to 250°C. The Johnson-Cook fracture model constants are determined from quasi-static and medium strain rate as well as high temperature tests on notched and smooth tension specimens. Although the J-C strength model constants are similar, the fracture model constants show wide variations. Details of the experimental method used and the results for the two alloys are presented.

High performance sapphire windows

NASA Technical Reports Server (NTRS)

Bates, Stephen C.; Liou, Larry

1993-01-01

High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

High performance sapphire windows

NASA Astrophysics Data System (ADS)

Bates, Stephen C.; Liou, Larry

1993-02-01

High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

Optimizing the coupled effects of Hall-Petch and precipitation strengthening in a Al 0.3 CoCrFeNi high entropy alloy

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

Gwalani, B.; Soni, Vishal; Lee, Michael

2017-05-01

A successful demonstration of applying integrated strengthening using Hall-Petch strengthening (grains size effect) and precipitation strengthening is shown in the fcc based high entropy alloy (HEA) Al0.3CoCrFeNi, leading to quantitative determinations of the Hall-Petch coefficients for both hardness and tensile yield strength, aswell as the enhancements in the yield strength fromtwo distinct types of ordered precipitates, L12 and B2. An excellent combination of yield strength (~490MPa), ultimate tensile strength (~850MPa), and ductility (~45% elongation) was achieved by optimizing and coupling both strengtheningmechanisms, resulting from a refined grain size as well as both L12 and B2 ordered precipitates. This opens upmore » new avenues for the future development of HEAs, with the appropriate balance of properties required for engineering applications.« less

Development of estimation system of knee extension strength using image features in ultrasound images of rectus femoris

NASA Astrophysics Data System (ADS)

Murakami, Hiroki; Watanabe, Tsuneo; Fukuoka, Daisuke; Terabayashi, Nobuo; Hara, Takeshi; Muramatsu, Chisako; Fujita, Hiroshi

2016-04-01

The word "Locomotive syndrome" has been proposed to describe the state of requiring care by musculoskeletal disorders and its high-risk condition. Reduction of the knee extension strength is cited as one of the risk factors, and the accurate measurement of the strength is needed for the evaluation. The measurement of knee extension strength using a dynamometer is one of the most direct and quantitative methods. This study aims to develop a system for measuring the knee extension strength using the ultrasound images of the rectus femoris muscles obtained with non-invasive ultrasonic diagnostic equipment. First, we extract the muscle area from the ultrasound images and determine the image features, such as the thickness of the muscle. We combine these features and physical features, such as the patient's height, and build a regression model of the knee extension strength from training data. We have developed a system for estimating the knee extension strength by applying the regression model to the features obtained from test data. Using the test data of 168 cases, correlation coefficient value between the measured values and estimated values was 0.82. This result suggests that this system can estimate knee extension strength with high accuracy.

Seminar on Use of High Strength Deformed Bars

NASA Astrophysics Data System (ADS)

1981-04-01

Steel requirements, cost and energy for two lane curved and straight bridges for 20 m span are studied. Saving in steel cost and energy by using high strength bars is also discussed. Only 20 m span, straight simply supported and 5 deg, 10 deg and 15 deg curved simply supported bridges are considered. The width of bridge is taken as 7.8 m. Bridges are designed with steel stresses 1900 kgs/cm sq, 2100 kgs/sq cm and 2500 kgs/sq cm and saving in steel, cost and energy is given.

Accelerated Comparative Fatigue Strength Testing of Belt Adhesive Joints

NASA Astrophysics Data System (ADS)

Bajda, Miroslaw; Blazej, Ryszard; Jurdziak, Leszek

2017-12-01

Belt joints are the weakest link in the serial structure that creates an endless loop of spliced belt segments. This affects not only the lower strength of adhesive joints of textile belts in comparison to vulcanized splices, but also the replacement of traditional glues to more ecological but with other strength parameters. This is reflected in the lowered durability of adhesive joints, which in underground coal mines is nearly twice shorter than the operating time of belts. Vulcanized splices require high precision in performance, they need long time to achieve cross-linking of the friction mixture and, above all, they require specialized equipment (vulcanization press) which is not readily available and often takes much time to be delivered down, which means reduced mining output or even downtime. All this reduces the reliability and durability of adhesive joints. In addition, due to the consolidation on the Polish coal market, mines are joined into large economic units serviced by a smaller number of processing plants. The consequence is to extend the transport routes downstream and increase reliability requirements. The greater number of conveyors in the chain reduces reliability of supply and increases production losses. With high fixed costs of underground mines, the reduction in mining output is reflected in the increase in unit costs, and this at low coal prices on the market can mean substantial losses for mines. The paper describes the comparative study of fatigue strength of shortened samples of adhesive joints conducted to compare many different variants of joints (various adhesives and materials). Shortened samples were exposed to accelerated fatigue in the usually long-lasting dynamic studies, allowing more variants to be tested at the same time. High correlation between the results obtained for shortened (100 mm) and traditional full-length (3×250 mm) samples renders accelerated tests possible.

Effects of plyometric training volume and training surface on explosive strength.

PubMed

Ramírez-Campillo, Rodrigo; Andrade, David C; Izquierdo, Mikel

2013-10-01

The purpose of this study is to examine the effects of different volume and training surfaces during a short-term plyometric training program on neuromuscular performance. Twenty-nine subjects were randomly assigned to 4 groups: control group (CG, n = 5), moderate volume group (MVG, n = 9, 780 jumps), moderate volume hard surface group (MVGHS, n = 8, 780 jumps), and high volume group (HVG, n = 7, 1,560 jumps). A series of tests were performed by the subjects before and after 7 weeks of plyometric training. These tests were measurement of maximum strength (5 maximum repetitions [5RMs]), drop jumps (DJs) of varying heights (20, 40, and 60 cm), squat and countermovement jumps (SJ and CMJ, respectively), timed 20-m sprint, agility, body weight, and height. The results of the present study suggest that high training volume leads to a significant increase in explosive performance that requires fast stretch-shortening cycle (SSC) actions (such as DJ and sprint) in comparison to what is observed after a moderate training volume regimen. Second, when plyometric training is performed on a hard training surface (high-impact reaction force), a moderate training volume induces optimal stimulus to increase explosive performance requiring fast SSC actions (e.g., DJ), maximal dynamic strength enhancement, and higher training efficiency. Thus, a finding of interest in the study was that after 7 weeks of plyometric training, performance enhancement in maximal strength and in actions requiring fast SSC (such as DJ and sprint) were dependent on the volume of training and the surface on which it was performed. This must be taken into account when using plyometric training on different surfaces.

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

Yang, W. H., E-mail: whyang21@hyundai.com; Lee, K., E-mail: klee@deform.co.kr; Lee, E. H., E-mail: mtgs2@kaist.ac.kr, E-mail: dyyang@kaist.ac.kr

The automotive industry has been pressed to satisfy more rigorous fuel efficiency requirements to promote energy conservation, safety features and cost containment. To satisfy this need, high strength steel has been developed and used for many different vehicle parts. The use of high strength steels, however, requires careful analysis and creativity in order to accommodate its relatively high springback behavior. An innovative method, called local warm forming with near infrared ray, has been developed to help promote the use of high strength steels in sheet metal forming. For this method, local regions of the work piece are heated using infraredmore » ray energy, thereby promoting the reduction of springback behavior. In this research, a V-bend test is conducted with DP980. After springback, the bend angles for specimens without local heating are compared to those with local heating. Numerical analysis has been performed using the commercial program, DEFORM-2D. This analysis is carried out with the purpose of understanding how changes to the local stress distribution will affect the springback during the unloading process. The results between experimental and computational approaches are evaluated to assure the accuracy of the simulation. Subsequent numerical simulation studies are performed to explore best practices with respect to thermal boundary conditions, timing, and applicability to the production environment.« less

Hanford's Simulated Low Activity Waste Cast Stone Processing

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

Kim, Young

2013-08-20

Cast Stone is undergoing evaluation as the supplemental treatment technology for Hanford’s (Washington) high activity waste (HAW) and low activity waste (LAW). This report will only cover the LAW Cast Stone. The programs used for this simulated Cast Stone were gradient density change, compressive strength, and salt waste form phase identification. Gradient density changes show a favorable outcome by showing uniformity even though it was hypothesized differently. Compressive strength exceeded the minimum strength required by Hanford and greater compressive strength increase seen between the uses of different salt solution The salt waste form phase is still an ongoing process asmore » this time and could not be concluded.« less

Precipitation Strengthening by Induction Treatment in High Strength Low Carbon Microalloyed Hot-Rolled Plates

NASA Astrophysics Data System (ADS)

Larzabal, G.; Isasti, N.; Rodriguez-Ibabe, J. M.; Uranga, P.

2018-03-01

The use of microalloyed steels in the production of thick plates is expanding due to the possibility of achieving attractive combinations of strength and toughness. As market requirements for high strength plates are increasing and new applications require reduced weight and innovative designs, novel approaches to attaining cost-effective grades are being developed. The mechanism of precipitation strengthening has been widely used in thin strip products, since the optimization of the coiling strategy offers interesting combinations in terms of final properties and microalloying additions. Precipitation strengthening in thick plates, however, is less widespread due to the limitation of interphase precipitation during continuous cooling after hot rolling. With the main objective of exploring the limits of this strengthening mechanism, laboratory thermomechanical simulations that reproduced plate hot rolling mill conditions were performed using low carbon steels microalloyed with Nb, NbMo, and TiMo additions. After continuous cooling to room temperature, a set of heat treatments using fast heating rates were applied simulating the conditions of induction heat treatments. An important increase of both yield and tensile strengths was measured after induction treatment without any important impairment in toughness properties. A significant precipitation hardening is observed in Mo-containing grades under specific heat treatment parameters.

Relationship of Cure Temperature to Mechanical, Physical, and Dielectric Performance of PDMS Glass Composite for Electric Motor Insulation

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Becker, Kathleen; Williams, Tiffany S.; Scheiman, Daniel A.; McCorkle, Linda S.; Heimann, Paula J.; Ring, Andrew; Woodworth, Andrew

2017-01-01

Achieving NASAs aggressive fuel burn and emission reduction for N-plus-3 aircraft will require hybrid electric propulsion system in which electric motors driven by either power generated from turbine or energy storage system will power the fan for propulsion. Motors designed for hybrid electric aircraft are expected to operate at medium to high voltages over long durations in a high altitude service environment. Such conditions have driven research toward the development of wire insulation with improved mechanical strength, thermal stability and increased breakdown voltage. The silicone class of materials has been considered for electric wire insulation due to its inherent thermal stability, dielectric strength and mechanical integrity. This paper evaluates the dependence of these properties on the cure conditions of a polydimethyl-siloxane (PDMS) elastomer; where both cure temperature and base-to-catalyst ratio were varied. The PDMS elastomer was evaluated as a bulk material and an impregnation matrix within a lightweight glass veil support. The E-glass support was selected for mechanical stiffness and dielectric strength. This work has shown a correlation between cure conditions and material physical properties. Tensile strength increased with cure temperature whereas breakdown voltage tended to be independent of process variations. The results will be used to direct material formulation based on specific insulation requirements.

Influence of repeated quenching-tempering on spheroidized carbide area in JIS SUJ2 bearing steel

NASA Astrophysics Data System (ADS)

Egawa, K.; Yoshida, I.; Yoshida, H.; Mizobe, K.; Kida, K.

2018-02-01

High-carbon high-strength JIS-SUJ2 bearing steel is mainly used for rolling contact applications which require high fatigue strength. We had applied repeated quenching which refine the prior austenite grains to this steel. In this work, we prepared JIS SUJ2 bearing steel bar specimens which were quenched three times (Q3T1) and quenched-tempered three times (QTQTQT) in order to investigate the influence of tempering before quenching on the microstructure. The specimens were etched by picral to observe the microstructure. We found that the spheroidized carbide area was important for the prior austenite grain formation.

BCB Bonding Technology of Back-Side Illuminated COMS Device

NASA Astrophysics Data System (ADS)

Wu, Y.; Jiang, G. Q.; Jia, S. X.; Shi, Y. M.

2018-03-01

Back-side illuminated CMOS(BSI) sensor is a key device in spaceborne hyperspectral imaging technology. Compared with traditional devices, the path of incident light is simplified and the spectral response is planarized by BSI sensors, which meets the requirements of quantitative hyperspectral imaging applications. Wafer bonding is the basic technology and key process of the fabrication of BSI sensors. 6 inch bonding of CMOS wafer and glass wafer was fabricated based on the low bonding temperature and high stability of BCB. The influence of different thickness of BCB on bonding strength was studied. Wafer bonding with high strength, high stability and no bubbles was fabricated by changing bonding conditions.

High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.; Chen, Po Shou

2003-01-01

Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent thermal growth stability, surface hardness and wear resistant properties.

Design Investigation on Applicable Mesh Structures for Medical Stent Applications

NASA Astrophysics Data System (ADS)

Asano, Shoji; He, Jianmei

2017-11-01

In recent years, utilization of medical stents is one of effective treatments for stenosis and occlusion occurring in a living body’s lumen indispensable for maintenance of human life such as superficial femoral artery (SFA) occlusion. However, there are concerns about the occurrence of fatigue fractures caused by stress concentrations, neointimal hyperplasia and the like due to the shape structure and the manufacturing method in the conventional stents, and a stent having high strength and high flexibility is required. Therefore, in this research, applicable mesh structures for medical stents based on the design concepts of high strength, high flexibility are interested to solve various problem of conventional stent. According to the shape and dimensions of SFA occlusion therapy stent and indwelling delivery catheter, shape design of the meshed stent are performed using 3-dimensional CAD software Solid Works first. Then analytical examination on storage characteristics and compression characteristics of such mesh structure applied stent models were carried out through finite element analysis software ANSYS Workbench. Meshed stent models with higher strength and higher flexibility with integral molding are investigated analytically. It was found that the storage characteristics and compression characteristics of meshed stent modles are highly dependent on the basic mesh shapes with same surface void ratio. Trade-off relationship between flexibility and storage characteristics is found exited, it is required to provide appropriate curvatures during basic mesh shape design.

Lightweight orthotic appliances

NASA Technical Reports Server (NTRS)

Baucom, R. M.; St. Clair, T. L.

1976-01-01

Graphite-filament reinforced polymer materials are used in applications requiring high tensile strength and modulus. Superior properties of graphite composite materials permit fabrication of supports that are considerably lighter, thinner, and stiffer than conventional components.

Considerations for an exercise prescription

NASA Technical Reports Server (NTRS)

Convertino, Victor A.

1989-01-01

A number of past and most recent research findings that describe some of the physiological responses to exercise in man and their relationship with exposure to various gravitational environments are discussed. Most of the data pertain to adaptations of the cardiovascular and body fluid systems. It should be kept in mind that the data from studies on microgravity simulation in man include exposures of relatively short duration (5 hours to 14 days). However, it is argued that the results may provide important guidelines for the consideration of many variables which are pertinent to the development of exercise prescription for long-duration space flight. The following considerations for exercise prescriptions during long-duration space flight are noted: (1) Relatively high aerobic fitness and strength, especially of the upper body musculature, should be a criterion for selection of astronauts who will be involved in EVA, since endurance and strength appear to be predominant characteristics for work performance. (2) Some degree of upper body strength will probably be required for effective performance of EVA. However, the endurance and strength required by the upper body for EVA can probably be obtained through preflight exercise prescription which involves swimming. (3) Although some degree of arm exercise may be required to maintain preflight endurance and strength, researchers propose that regular EVA will probably be sufficient to maintain the endurance and strength required to effectively perform work tasks during space flight. (4) A minimum of one maximal aerobic exercise every 7 to 10 days during space flight may be all that is necessary for maintenance of normal cardiovascular responsiveness and replacement of body fluids for reentry following prolonged space flight. (5) The possible reduction in the amount of exercise required for maintenance of cardiovascular system and body fluids in combination with the use of electromyostimulation (EMS) or methods other than conventional exercise for maintaining size and strength of muscles and bones needs great consideration for further research. These approaches represent a potential solution to the problem of compromising valuable time for exercise that is needed for daily operations.

Fiber reinforced superalloys for rocket engines

NASA Technical Reports Server (NTRS)

Petrasek, Donald W.; Stephens, Joseph R.

1989-01-01

High pressure turbopumps for advanced reusable liquid propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several fold increase in life and over a 200 C increase in temperature capability over the current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

Fiber reinforced superalloys for rocket engines

NASA Technical Reports Server (NTRS)

Petrasek, Donald W.; Stephens, Joseph R.

1988-01-01

High-pressure turbopumps for advanced reusable liquid-propellant rocket engines such as that for the Space Shuttle Main Engine (SSME) require turbine blade materials that operate under extreme conditions of temperature, hydrogen environment, high-cycle fatigue loading, thermal fatigue and thermal shock. Such requirements tax the capabilities of current blade materials. Based on projections of properties for tungsten fiber reinforced superalloy (FRS) composites, it was concluded that FRS turbine blades offer the potential of a several-fold increase in life and over a 200C increase in temperature capability over current SSME blade material. FRS composites were evaluated with respect to mechanical property requirements for SSME blade applications. Compared to the current blade material, the thermal shock resistance of FRS materials is excellent, two to nine times better, and their thermal fatigue resistance is equal to or higher than the current blade material. FRS materials had excellent low and high-cycle fatigue strengths, and thermal shock-induced surface microcracks had no influence on their fatigue strength. The material also exhibited negligible embrittlement when exposed to a hydrogen environment.

Gradient Tempering Of Bearing Races

NASA Technical Reports Server (NTRS)

Parr, Richardson A.

1991-01-01

Gradient-tempering process increases fracture toughness and resistance to stress-corrosion cracking of ball-bearing races made of hard, strong steels and subject to high installation stresses and operation in corrosive media. Also used in other applications in which local toughening of high-strength/low-toughness materials required.

47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Measurements required: Field strength of spurious radiation. 2.1053 Section 2.1053 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1053 Measurements required: Field strength of spurious radiation. (a...

47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Measurements required: Field strength of spurious radiation. 2.1053 Section 2.1053 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1053 Measurements required: Field strength of spurious radiation. (a...

47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Measurements required: Field strength of spurious radiation. 2.1053 Section 2.1053 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL... Procedures Certification § 2.1053 Measurements required: Field strength of spurious radiation. (a...

High-Strength Aluminum Casting Alloy for High-Temperature Applications (MSFC Center Director's Discretionary Fund Final Project No. 97-10)

NASA Technical Reports Server (NTRS)

Lee, J. A.

1998-01-01

A new aluminum-silicon alloy has been successfully developed at Marshall Space Flight Center that has a significant improvement in tensile strength at elevated temperatures (550 to 700 F). For instance, the new alloy shows in average tensile strength of at least 90 percent higher than the current 390 aluminum piston alloy tested at 500 F. Compared to conventional aluminum alloys, automotive engines using the new piston alloy will have improved gas mileage, and may produce less air pollution in order to meet the future U.S. automotive legislative requirements for low hydrocarbon emissions. The projected cost for this alloy is less than $0.95/lb, and it readily allows the automotive components to be cast at a high production volume with a low, fully accounted cost. It is economically produced by pouring molten metal directly into conventional permanent steel molds or die casting.

Advanced thermoplastic resins, phase 2

NASA Technical Reports Server (NTRS)

Brown, A. M.; Hill, S. G.; Falcone, A.

1991-01-01

High temperature structural resins are required for use on advanced aerospace vehicles as adhesives and composite matrices. NASA-Langley developed polyimide resins were evaluated as high temperature structural adhesives for metal to metal bonding and as composite matrices. Adhesive tapes were prepared on glass scrim fabric from solutions of polyamide acids of the semicrystalline polyimide LARC-CPI, developed at the NASA-Langley Research Center. Using 6Al-4V titanium adherends, high lap shear bond strengths were obtained at ambient temperature (45.2 MPa, 6550 psi) and acceptable strengths were obtained at elevated temperature (14.0 MPa, 2030 psi) using the Pasa-Jell 107 conversion coating on the titanium and a bonding pressure of 1.38 MPa (200 psi). Average zero degree composite tensile and compressive strengths of 1290 MPa (187 ksi) and 883 MPa (128 ksi) respectively were obtained at ambient temperature with unsized AS-4 carbon fiber reinforcement.

Synapsin Is Required to "Boost" Memory Strength for Highly Salient Events

ERIC Educational Resources Information Center

Kleber, Jörg; Chen, Yi-Chun; Michels, Birgit; Saumweber, Timo; Schleyer, Michael; Kähne, Thilo; Buchner, Erich; Gerber, Bertram

2016-01-01

Synapsin is an evolutionarily conserved presynaptic phosphoprotein. It is encoded by only one gene in the "Drosophila" genome and is expressed throughout the nervous system. It regulates the balance between reserve and releasable vesicles, is required to maintain transmission upon heavy demand, and is essential for proper memory function…

Tensile strength and failure mechanisms of tantalum at extreme strain rates

NASA Astrophysics Data System (ADS)

Hahn, Eric; Fensin, Saryu; Germann, Timothy; Meyers, Marc

Non-equilibrium molecular dynamics simulations are used to probe the tensile response of monocrystalline, bicrystalline, and nanocrystalline tantalum over six orders of magnitude of strain rate. Our analysis of the strain rate dependence of strength is extended to over nine orders of magnitude by bridging the present simulations to recent laser-driven shock experiments. Tensile strength shows a power-law dependence with strain rate over this wide range, with different relationships depending on the initial microstructure and active deformation mechanism. At high strain rates, multiple spall events occur independently and continue to occur until communication occurs by means of relaxation waves. Temperature plays a significant role in the reduction of spall strength as the initial shock required to achieve such large strain rates also contributes to temperature rise, through pressure-volume work as well as visco-plastic heating, which leads to softening and sometimes melting upon release. At ultra-high strain rates, those approaching or exceeding the atomic vibrational frequency, spall strength saturates at the ultimate cohesive strength of the material. UC Research Laboratories Grant (09-LR-06-118456-MEYM); Department of Energy NNSA/SSAP (DE-NA0002080); DOE ASCR Exascale Co-design Center for Materials in Extreme Environments.

Systems design of transformation toughened blast-resistant naval hull steels

NASA Astrophysics Data System (ADS)

Saha, Arup

A systems approach to computational materials design has demonstrated a new class of ultratough, weldable secondary hardened plate steels combining new levels of strength and toughness while meeting processability requirements. A first prototype alloy has achieved property goals motivated by projected naval hull applications requiring extreme fracture toughness (Cv > 85 ft-lbs (115 J) corresponding to KId > 200 ksi.in1/2 (220 MPa.m1/2)) at strength levels of 150--180 ksi (1034--1241 MPa) yield strength in weldable, formable plate steels. A theoretical design concept was explored integrating the mechanism of precipitated nickel-stabilized dispersed austenite for transformation toughening in an alloy strengthened by combined precipitation of M2C carbides and BCC copper both at an optimal ˜3nm particle size for efficient strengthening. This concept was adapted to plate steel design by employing a mixed bainitic/martensitic matrix microstructure produced by air-cooling after solution-treatment and constraining the composition to low carbon content for weldability. With optimized levels of copper and M2C carbide formers based on a quantitative strength model, a required alloy nickel content of 6.5 wt% was predicted for optimal austenite stability for transformation toughening at the desired strength level of 160 ksi (1100 MPa) yield strength. A relatively high Cu level of 3.65 wt% was employed to allow a carbon limit of 0.05 wt% for good weldability. Hardness and tensile tests conducted on the designed prototype confirmed predicted precipitation strengthening behavior in quench and tempered material. Multi-step tempering conditions were employed to achieve the optimal austenite stability resulting in significant increase of impact toughness to 130 ft-lb (176 J) at a strength level of 160 ksi (1100 MPa). Comparison with the baseline toughness-strength combination determined by isochronal tempering studies indicates a transformation toughening increment of 60% in Charpy energy. Predicted Cu particle number densities and the heterogeneous nucleation of optimal stability high Ni 5 nm austenite on nanometer-scale copper precipitates in the multi-step tempered samples was confirmed using three-dimensional atom probe microscopy. Charpy impact tests and fractography demonstrate ductile fracture with C v > 90 ft-lbs (122 J) down to -40°C, with a substantial toughness peak at 25°C consistent with designed transformation toughening behavior. The properties demonstrated in this first prototype represent a substantial advance over existing naval hull steels.

The Effect of Weld Penetration on Blast Performance of Welded Panels

DTIC Science & Technology

2014-08-01

requirements of blast and ballistic protection, structural strength, fatigue resistance, unit mass and production cost. The testing described in this report...UNCLASSIFIED 7 TETRA S 20 9 3-G is an austenitic filler material often selected for welding high strength armour steels to control hydrogen induced...repeatability, lower cost, faster test turnaround and a reduced number of variables to control . Figure 30 is an illustration of the simplifications made

Oxidation resistant iron and nickel alloys for high temperature use

NASA Technical Reports Server (NTRS)

Hill, V. L.; Misra, S. K.; Wheaton, H. L.

1970-01-01

Iron-base and nickel-base alloys exhibit good oxidation resistance and improved ductility with addition of small amounts of yttrium, tantalum /or hafnium/, and thorium. They can be used in applications above the operating temperatures of the superalloys, if high strength materials are not required.

Refractory ceramic has wide usage, low fabrication cost

NASA Technical Reports Server (NTRS)

1964-01-01

Particulate, fused amorphous silica is formed into complex shapes by casting in plaster molds. High temperature firing is not required. This ceramic is resistant to thermal shock and exhibits good strength properties.

Ultra-porous titanium oxide scaffold with high compressive strength

PubMed Central

Tiainen, Hanna; Lyngstadaas, S. Petter; Ellingsen, Jan Eirik

2010-01-01

Highly porous and well interconnected titanium dioxide (TiO2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics, such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore architectural characteristics were investigated in order to identify the key processing steps and morphological properties that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability. Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry. Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters indicating a reduced flaw size in the scaffold struts. The fabricated TiO2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required. PMID:20711636

High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

NASA Astrophysics Data System (ADS)

Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

2016-02-01

An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

Further development and application of polycrystalline metal whiskers

NASA Technical Reports Server (NTRS)

Schladitz, H. J.

1979-01-01

High strength metal whiskers have a larger versatile field of application than monocrystalline whiskers. Although polycrystalline metal whiskers can be used for composites, preferably by extrusion in thermoplastics or by infiltration of resins or metals into whisker networks, the chief application at present may be the production and various use of whisker networks. Such networks can be produced up to high degrees of porosity and besides high mechanical strength, they have high inside surfaces and high electric conductivity. There are for instance, applications concerning construction of electrodes for batteries and fuel cells, catalysts and also new heat-exchanger material, capable of preparing fuel oil and gasoline in order to assist a high-efficiency combustion. The technical application of polycrystalline metal whiskers require their modification as well as the construction of a pilot production unit.

Inferring Strength of Tantalum from Hydrodynamic Instability Recovery Experiments

NASA Astrophysics Data System (ADS)

Sternberger, Z.; Maddox, B.; Opachich, Y.; Wehrenberg, C.; Kraus, R.; Remington, B.; Randall, G.; Farrell, M.; Ravichandran, G.

2018-05-01

Hydrodynamic instability experiments allow access to material properties at extreme conditions, where strain rates exceed 105 s-1 and pressures reach 100 GPa. Current hydrodynamic instability experimental methods require in-flight radiography to image the instability growth at high pressure and high strain rate, limiting the facilities where these experiments can be performed. An alternate approach, recovering the sample after loading, allows measurement of the instability growth with profilometry. Tantalum samples were manufactured with different 2D and 3D initial perturbation patterns and dynamically compressed by a blast wave generated by laser ablation. The samples were recovered from peak pressures between 30 and 120 GPa and strain rates on the order of 107 s-1, providing a record of the growth of the perturbations due to hydrodynamic instability. These records are useful validation points for hydrocode simulations using models of material strength at high strain rate. Recovered tantalum samples were analyzed, providing an estimate of the strength of the material at high pressure and strain rate.

Influence of Drug Properties and Formulation on In Vitro Drug Release and Biowaiver Regulation of Oral Extended Release Dosage Forms.

PubMed

Lin, Zhongqiang; Zhou, Deliang; Hoag, Stephen; Qiu, Yihong

2016-03-01

Bioequivalence (BE) studies are often required to ensure therapeutic equivalence for major product and manufacturing changes. Waiver of a BE study (biowaiver) is highly desired for such changes. Current regulatory guidelines allow for biowaiver of proportionally similar lower strengths of an extended release (ER) product provided it exhibits similar dissolution to the higher strength in multimedia. The objective of this study is to demonstrate that (1) proportionally similar strengths of ER tablets exhibiting similar in vitro dissolution profiles do not always assure BE and (2) different strengths that do not meet the criteria for dissolution profile similarity may still be bioequivalent. Four marketed ER tablets were used as model drug products. Higher and lower (half) strength tablets were prepared or obtained from commercial source. In vitro drug release was compared using multi-pH media (pH 1.2, 4.5, 6.8) per regulatory guidance. In vivo performance was assessed based on the available in vivo BE data or established in vitro-in vivo relationships. This study demonstrated that the relationship between in vitro dissolution and in vivo performance is complex and dependent on the characteristics of specific drug molecules, product design, and in vitro test conditions. As a result, proportionally similar strengths of ER dosage forms that meet biowaiver requirements per current regulatory guidelines cannot ensure bioequivalence in all cases. Thus, without an established relationship between in vitro and in vivo performance, granting biowaiver based on passing in vitro tests may result in the approval of certain bioinequivalent products, presenting risks to patients. To justify any biowaiver using in vitro test, it is essential to understand the effects of drug properties, formulation design, product characteristics, test method, and its in vivo relevance. Therefore, biowaiver requirements of different strengths of ER dosage forms specified in the current regulatory guidance should be reevaluated to assure consistent safety and efficacy among different strengths.

Amateur boxing: physical and physiological attributes.

PubMed

Chaabène, Helmi; Tabben, Montassar; Mkaouer, Bessem; Franchini, Emerson; Negra, Yassine; Hammami, Mehrez; Amara, Samiha; Chaabène, Raja Bouguezzi; Hachana, Younés

2015-03-01

Boxing is one of the oldest combat sports. The aim of the current review is to critically analyze the amateur boxer's physical and physiological characteristics and to provide practical recommendations for training as well as new areas of scientific research. High-level male and female boxers show a propensity for low body fat levels. Although studies on boxer somatotypes are limited, the available information shows that elite-level male boxers are characterized by a higher proportion of mesomorphy with a well-developed muscle mass and a low body fat level. To help support the overall metabolic demands of a boxing match and to accelerate the recovery process between rounds, athletes of both sexes require a high level of cardiorespiratory fitness. International boxers show a high peak and mean anaerobic power output. Muscle strength in both the upper and lower limbs is paramount for a fighter's victory and is one of the keys to success in boxing. As boxing punches are brief actions and very dynamic, high-level boxing performance requires well-developed muscle power in both the upper and lower limbs. Albeit limited, the available studies reveal that isometric strength is linked to high-level boxing performance. Future investigations into the physical and physiological attributes of boxers are required to enrich the current data set and to help create a suitable training program.

Effects of Cognitive Interventions on Sports Anxiety and Performance.

ERIC Educational Resources Information Center

Murphy, Shane M.; Woolfolk, Robert L.

Oxendine (1970) hypothesized that the arousal-performance relationship varies across tasks, such that gross motor activities will require high arousal for optimal performance while fine motor activities will be facilitated by low arousal, but adversely affected by high arousal. Although the effects of preparatory arousal on strength performance…

High-Maintenance Parents--Responding in the Spirit of Partnership.

ERIC Educational Resources Information Center

Gonzalez-Mena, Janet; Stonehouse, Anne

2000-01-01

Defines a high-maintenance parent as one requiring more from the child care organization than the average parent. Suggests six points for choosing response: take a positive nonjudgmental approach; see parent's view; focus on strengths; understand importance of communication and negotiation skills; be respectful; and respect boundaries of your own…

Explosive bonding of metal-matrix composites

NASA Technical Reports Server (NTRS)

Reece, O. Y.

1969-01-01

Explosive bonding process produces sheet composites of aluminum alloy reinforced by high-strength stainless steel wires. The bonds are excellent metallurgically, no external heat is required, various metals can be bonded, and the process is inexpensive.

Optimum Design and Development of High Strength and Toughness Welding Wire for Pipeline Steel

NASA Astrophysics Data System (ADS)

Chen, Cuixin; Xue, Haitao; Yin, Fuxing; Peng, Huifen; Zhi, Lei; Wang, Sixu

Pipeline steel with higher strength(>800MPa) has been gradually used in recent years, so how to achieve good match of base metal and weld deposit is very important for its practical application. Based on the alloy system of 0.02-0.04%C, 2.0%Mn and 0.5%Si, four different kinds of welding wires were designed and produced. The effects of alloy elements on phase transformation and mechanical properties were analyzed. Experimental results show that the designed steels with the addition of 2-4% Ni+Cr+Mo and <0.2% Nb+V+Ti have high strength (>800MPa) and good elongation (>15%). The microstructure of deposits metal is mainly composed of granular bainite and M-A constituents with the mean size of 0.2-07μm are dispersed on ferritic matrix. The deposited metals have good match of strength (>800MPa) and impact toughness (>130J) which well meet the requirement of pipeline welding.

Non-random walk diffusion enhances the sink strength of semicoherent interfaces

DOE PAGES

Vattré, A.; Jourdan, T.; Ding, H.; ...

2016-01-29

Clean, safe and economical nuclear energy requires new materials capable of withstanding severe radiation damage. One strategy of imparting radiation resistance to solids is to incorporate into them a high density of solid-phase interfaces capable of absorbing and annihilating radiation-induced defects. Here we show that elastic interactions between point defects and semicoherent interfaces lead to a marked enhancement in interface sink strength. Our conclusions stem from simulations that integrate first principles, object kinetic Monte Carlo and anisotropic elasticity calculations. Surprisingly, the enhancement in sink strength is not due primarily to increased thermodynamic driving forces, but rather to reduced defect migrationmore » barriers, which induce a preferential drift of defects towards interfaces. The sink strength enhancement is highly sensitive to the detailed character of interfacial stresses, suggesting that ‘super-sink’ interfaces may be designed by optimizing interface stress fields. Lastly, such interfaces may be used to create materials with unprecedented resistance to radiation-induced damage.« less

Effect of nickel addition on mechanical properties of powder forged Fe-Cu-C

NASA Astrophysics Data System (ADS)

Archana Barla, Nikki

2018-03-01

Fe-Cu-C system is very popular in P/M industry for its good compressibility and dimensional stability with high strength. Fe-Cu-C is a structural material and is used where high strength with high hardness is required. The composition of powder metallurgy steel plays a vital role in the microstructure and physical properties of the sintered component. Fe-2Cu-0.7C-Ni alloy with varying nickel composition (0%, 0.5%, 1.0%, 1.5%, 2.0%, and 3.0%) wt. % was prepared by powder metallurgy (P/M) sinter forging process. The present work discuss the effect of varying nickel content on microstructure and mechanical properties.

The development of Nb-based advanced intermetallic alloys for structural applications

NASA Astrophysics Data System (ADS)

Subramanian, P. R.; Mendiratta, M. G.; Dimiduk, D. M.

1996-01-01

A new generation of refractory material systems with significant increases in temperature capability is required to meet the demands of future aerospace applications. Such materials require a balance of properties such as low-temperature damage tolerance, high-temperature strength, creep resistance, and superior environmental stability for implementation in advanced aerospace systems. Systems incorporating niobium-based beta alloys and intermetallic compounds have the potential for meeting these requirements.

FE Simulation Models for Hot Stamping an Automobile Component with Tailor-Welded High-Strength Steels

NASA Astrophysics Data System (ADS)

Tang, Bingtao; Wang, Qiaoling; Wei, Zhaohui; Meng, Xianju; Yuan, Zhengjun

2016-05-01

Ultra-high-strength in sheet metal parts can be achieved with hot stamping process. To improve the crash performance and save vehicle weight, it is necessary to produce components with tailored properties. The use of tailor-welded high-strength steel is a relatively new hot stamping process for saving weight and obtaining desired local stiffness and crash performance. The simulation of hot stamping boron steel, especially tailor-welded blanks (TWBs) stamping, is more complex and challenging. Information about thermal/mechanical properties of tools and sheet materials, heat transfer, and friction between the deforming material and the tools is required in detail. In this study, the boron-manganese steel B1500HS and high-strength low-alloy steel B340LA are tailor welded and hot stamped. In order to precisely simulate the hot stamping process, modeling and simulation of hot stamping tailor-welded high-strength steels, including phase transformation modeling, thermal modeling, and thermal-mechanical modeling, is investigated. Meanwhile, the welding zone of tailor-welded blanks should be sufficiently accurate to describe thermal, mechanical, and metallurgical parameters. FE simulation model using TWBs with the thickness combination of 1.6 mm boron steel and 1.2 mm low-alloy steel is established. In order to evaluate the mechanical properties of the hot stamped automotive component (mini b-pillar), hardness and microstructure at each region are investigated. The comparisons between simulated results and experimental observations show the reliability of thermo-mechanical and metallurgical modeling strategies of TWBs hot stamping process.

Ceramics for engines

NASA Technical Reports Server (NTRS)

Kiser, James D.; Levine, Stanley R.; Dicarlo, James A.

1987-01-01

Structural ceramics were under nearly continuous development for various heat engine applications since the early 1970s. These efforts were sustained by the properties that ceramics offer in the areas of high-temperature strength, environmental resistance, and low density and the large benefits in system efficiency and performance that can result. The promise of ceramics was not realized because their brittle nature results in high sensitivity to microscopic flaws and catastrophic fracture behavior. This translated into low reliability for ceramic components and thus limited their application in engines. For structural ceramics to successfully make inroads into the terrestrial heat engine market requires further advances in low cost, net shape fabrication of high reliability components, and improvements in properties such as toughness, and strength. These advances will lead to very limited use of ceramics in noncritical applications in aerospace engines. For critical aerospace applications, an additional requirement is that the components display markedly improved toughness and noncatastrophic or graceful fracture. Thus the major emphasis is on fiber-reinforced ceramics.

Development of reaction-sintered SiC mirror for space-borne optics

NASA Astrophysics Data System (ADS)

Yui, Yukari Y.; Kimura, Toshiyoshi; Tange, Yoshio

2017-11-01

We are developing high-strength reaction-sintered silicon carbide (RS-SiC) mirror as one of the new promising candidates for large-diameter space-borne optics. In order to observe earth surface or atmosphere with high spatial resolution from geostationary orbit, larger diameter primary mirrors of 1-2 m are required. One of the difficult problems to be solved to realize such optical system is to obtain as flat mirror surface as possible that ensures imaging performance in infrared - visible - ultraviolet wavelength region. This means that homogeneous nano-order surface flatness/roughness is required for the mirror. The high-strength RS-SiC developed and manufactured by TOSHIBA is one of the most excellent and feasible candidates for such purpose. Small RS-SiC plane sample mirrors have been manufactured and basic physical parameters and optical performances of them have been measured. We show the current state of the art of the RS-SiC mirror and the feasibility of a large-diameter RS-SiC mirror for space-borne optics.

Experimental evaluation of tool wear throughout a continuous stroke blanking process of quenched 22MnB5 ultra-high-strength steel

NASA Astrophysics Data System (ADS)

Vogt, S.; Neumayer, F. F.; Serkyov, I.; Jesner, G.; Kelsch, R.; Geile, M.; Sommer, A.; Golle, R.; Volk, W.

2017-09-01

Steel is the most common material used in vehicles’ chassis, which makes its research an important topic for the automotive industry. Recently developed ultra-high-strength steels (UHSS) provide extreme tensile strength up to 1,500 MPa and combine great crashworthiness with good weight reduction potential. However, in order to reach the final shape of sheet metal parts additional cutting steps such as trimming and piercing are often required. The final trimming of quenched metal sheets presents a huge challenge to a conventional process, mainly because of the required extreme cutting force. The high cutting impact, due to the materials’ brittleness, causes excessive tool wear or even sudden tool failure. Therefore, a laser is commonly used for the cutting process, which is time and energy consuming. The purpose of this paper is to demonstrate the capability of a conventional blanking tool design in a continuous stroke piercing process using boron steel 22MnB5 sheets. Two different types of tool steel were tested for their suitability as active cutting elements: electro-slag remelted (ESR) cold work tool steel Bohler K340 ISODUR and powder-metallurgic (PM) high speed steel Bohler S390 MICROCLEAN. A FEM study provided information about an optimized punch design, which withstands buckling under high cutting forces. The wear behaviour of the process was assessed by the tool wear of the active cutting elements as well as the quality of cut surfaces.

Behavior of drilled shafts with high-strength reinforcement and casing.

DOT National Transportation Integrated Search

2015-09-01

Drilled shafts provide significant geotechnical resistance for support of highway bridges, and are used throughout the States of Oregon : and Washington to meet their structural foundation requirements. Due to changes in construction methods and poor...

Design and analysis of composite structures with stress concentrations

NASA Technical Reports Server (NTRS)

Garbo, S. P.

1983-01-01

An overview of an analytic procedure which can be used to provide comprehensive stress and strength analysis of composite structures with stress concentrations is given. The methodology provides designer/analysts with a user-oriented procedure which, within acceptable engineering accuracy, accounts for the effects of a wide range of application design variables. The procedure permits the strength of arbitrary laminate constructions under general bearing/bypass load conditions to be predicted with only unnotched unidirectional strength and stiffness input data required. Included is a brief discussion of the relevancy of this analysis to the design of primary aircraft structure; an overview of the analytic procedure with theory/test correlations; and an example of the use and interaction of this strength analysis relative to the design of high-load transfer bolted composite joints.

Mechanical properties of direct core build-up materials.

PubMed

Combe, E C; Shaglouf, A M; Watts, D C; Wilson, N H

1999-05-01

This work was undertaken to measure mechanical properties of a diverse group of materials used for direct core build-ups, including a high copper amalgam, a silver cermet cement, a VLC resin composite and two composites specifically developed for this application. Compressive strength, elastic modulus, diametral tensile strength and flexural strength and modulus were measured for each material as a function of time up to 3 months, using standard specification tests designed for the materials. All the materials were found to meet the minimum specification requirements except in terms of flexural strength for the amalgam after 1 h and the silver cermet at all time intervals. There proved to be no obvious superior material in all respects for core build-ups, and the need exists for a specification to be established specifically for this application.

Nutritional aspects of women strength athletes.

PubMed

Volek, J S; Forsythe, C E; Kraemer, W J

2006-09-01

Strength training elicits sports related and health benefits for both men and women. Although sexual dimorphism is observed in exercise metabolism, there is little information outlining the specific nutritional needs of women strength athletes. Many women athletes restrict energy intake, specifically fat consumption, in order to modify body composition, but this nutritional practice is often counter-productive. Compared to men, women appear to be less reliant on glycogen during exercise and less responsive to carbohydrate mediated glycogen synthesis during recovery. Female strength athletes may require more protein than their sedentary and endurance training counterparts to attain positive nitrogen balance and promote protein synthesis. Therefore, women strength athletes should put less emphasis on a very high carbohydrate intake and more emphasis on quality protein and fat consumption in the context of energy balance to enhance adaptations to training and improve general health. Attention to timing of nutrient ingestion, macronutrient quality, and dietary supplementation (for example, creatine) are briefly discussed as important components of a nutritionally adequate and effective strength training diet for women.

High strength air-dried aerogels

DOEpatents

Coronado, Paul R.; Satcher, Jr., Joe H.

2012-11-06

A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

Material selection indices for design of surgical instruments with long tubular shafts.

PubMed

Nelson, Carl A

2013-02-01

In any medical device design process, material selection plays an important role. For devices which sustain mechanical loading, strength and stiffness requirements can be significant drivers of the design. This paper examines the specific case of minimally invasive surgical instruments, including robotic instruments, having long, tubular shafts. Material properties-based selection indices are derived for achieving high performance of these devices in terms of strength and stiffness, and the use of these indices for informing the medical device design problem is illustrated.

Application of Strength Requirements to Complex Loading Scenarios

NASA Technical Reports Server (NTRS)

England, Scott; Rajulu, Sudhakar

2016-01-01

NASA's endeavors in human spaceflight rely on extensive volumes of human-systems integration requirements to ensure mission success. These requirements protect for space hardware accommodation for the full range of potential crewmembers, but cannot cover every possible action and contingency in detail. This study was undertaken in response to questions from various strength requirement users who were unclear how to apply idealized strength requirements that did not map well to the complex loading scenarios that crewmembers would encounter. Three of the most commonly occurring questions from stakeholders were selected to be investigated with human testing and human modeling. Preliminary findings indicate deviation from nominal postures can affect strength requirement compliance positively or negatively, depending on the nature of the deviation. Human modeling offers some avenues for quickly addressing requirement verification questions, but is limited by the fidelity of the model and environment.

The Effect of CFRP Surface Treatment on the Splat Morphology and Coating Adhesion Strength

NASA Astrophysics Data System (ADS)

Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

2014-01-01

Metallization of Carbon Fiber-Reinforced Polymer (CFRP) composites aggrandized their application to aircraft, automobile, and wind power industries. Recently, the metallization of CFRP surface using thermal spray technique, especially the cold spray, a solid state deposition technique, is a topic of research. However, a direct cold spray deposition on the CFRP substrate often imposes severe erosion on the surface owing to the high-impact energy of the sprayed particles. This urges the requirement of an interlayer on the CFRP surface. In the present study, the effect of surface treatment on the interlayer adhesion strength is evaluated. The CFRP samples were initially treated mechanically, chemically, and thermally and then an interlayer was developed by atmospheric plasma spray system. The quality of the coating is highly dependent on the splat taxonomy; therefore the present work also devoted to study the splat formation behavior using the splat-collection experiments, where the molten Cu particles impinged on the treated CFRP substrates. These results were correlated with the coating adhesion strength. The coating adhesion strength was measured by pull-out test. The results showed that the surface treatment, particularly the chemical treatment, was fairly successful in improving the adhesion strength.

Circuit Training: Exercise That Counts.

ERIC Educational Resources Information Center

Mosher, Patricia E.; Underwood, Steven A.

1992-01-01

Describes how to assess and implement aerobic circuit training, which involves multistation weight training apparatus, handweights, and aerobic activity equipment to increase cardiovascular fitness and strength. Designed for high school and college students, the circuit requires 25 minutes to complete. (SM)

High Performance Arcjet Engines

NASA Technical Reports Server (NTRS)

Kennel, Elliot B.; Ivanov, Alexey Nikolayevich; Nikolayev, Yuri Vyacheslavovich

1994-01-01

This effort sought to exploit advanced single crystal tungsten-tantalum alloy material for fabrication of a high strength, high temperature arcjet anode. The use of this material is expected to result in improved strength, temperature resistance, and lifetime compared to state of the art polycrystalline alloys. In addition, the use of high electrical and thermal conductivity carbon-carbon composites was considered, and is believed to be a feasible approach. Highly conductive carbon-carbon composite anode capability represents enabling technology for rotating-arc designs derived from the Russian Scientific Research Institute of Thermal Processes (NIITP) because of high heat fluxes at the anode surface. However, for US designs the anode heat flux is much smaller, and thus the benefits are not as great as in the case of NIITP-derived designs. Still, it does appear that the tensile properties of carbon-carbon can be even better than those of single crystal tungsten alloys, especially when nearly-single-crystal fibers such as vapor grown carbon fiber (VGCF) are used. Composites fabricated from such materials must be coated with a refractory carbide coating in order to ensure compatibility with high temperature hydrogen. Fabrication of tungsten alloy single crystals in the sizes required for fabrication of an arcjet anode has been shown to be feasible. Test data indicate that the material can be expected to be at least the equal of W-Re-HfC polycrystalline alloy in terms of its tensile properties, and possibly superior. We are also informed by our colleagues at Scientific Production Association Luch (NP0 Luch) that it is possible to use Russian technology to fabricate polycrystalline W-Re-HfC or other high strength alloys if desired. This is important because existing engines must rely on previously accumulated stocks of these materials, and a fabrication capability for future requirements is not assured.

High performance arcjet engines

NASA Astrophysics Data System (ADS)

Kennel, Elliot B.; Ivanov, Alexey Nikolayevich; Nikolayev, Yuri Vyacheslavovich

1994-10-01

This effort sought to exploit advanced single crystal tungsten-tantalum alloy material for fabrication of a high strength, high temperature arcjet anode. The use of this material is expected to result in improved strength, temperature resistance, and lifetime compared to state of the art polycrystalline alloys. In addition, the use of high electrical and thermal conductivity carbon-carbon composites was considered, and is believed to be a feasible approach. Highly conductive carbon-carbon composite anode capability represents enabling technology for rotating-arc designs derived from the Russian Scientific Research Institute of Thermal Processes (NIITP) because of high heat fluxes at the anode surface. However, for US designs the anode heat flux is much smaller, and thus the benefits are not as great as in the case of NIITP-derived designs. Still, it does appear that the tensile properties of carbon-carbon can be even better than those of single crystal tungsten alloys, especially when nearly-single-crystal fibers such as vapor grown carbon fiber (VGCF) are used. Composites fabricated from such materials must be coated with a refractory carbide coating in order to ensure compatibility with high temperature hydrogen. Fabrication of tungsten alloy single crystals in the sizes required for fabrication of an arcjet anode has been shown to be feasible. Test data indicate that the material can be expected to be at least the equal of W-Re-HfC polycrystalline alloy in terms of its tensile properties, and possibly superior. We are also informed by our colleagues at Scientific Production Association Luch (NP0 Luch) that it is possible to use Russian technology to fabricate polycrystalline W-Re-HfC or other high strength alloys if desired. This is important because existing engines must rely on previously accumulated stocks of these materials, and a fabrication capability for future requirements is not assured.

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

Kamiya, Junichiro, E-mail: kamiya.junichiro@jaea.go.jp; Hikichi, Yusuke; Kinsho, Michikazu

For the vacuum systems of high-intensity beam accelerators, low radioactivation materials with good vacuum characteristics and high mechanical strength are required. The titanium alloy Ti-6Al-4V was investigated as a potential low activation vacuum material with high mechanical strength for the fabrication of vacuum components, particularly the flanges of beam pipes, in the J-PARC 3 GeV synchrotron. The dose rate of Ti-6Al-4V when irradiated by a 400 MeV proton was observed to decrease more rapidly than that of stainless steel. Furthermore, the generated radioactive isotopes were nuclides with relatively short half-lives. The outgassing rate per unit area of Ti-6Al-4V was approximately 10{sup −8 }Pamore » m{sup 3}/s m{sup 2} after pumping for 100 h, which is the same as the typical value for stainless steel. Additionally, the hydrogen concentration in bulk Ti-6Al-4V was reduced to approximately 1 ppm by vacuum firing at 700 °C for 9 h; the mechanical strength was not reduced by this process. These results indicate that Ti-6Al-4V is a good candidate for use as a low activation vacuum material with high mechanical strength.« less

Normative values of isometric elbow strength in healthy adults: a systematic review.

PubMed

Kotte, Shamala H P; Viveen, Jetske; Koenraadt, Koen L M; The, Bertram; Eygendaal, Denise

2018-07-01

Post-traumatic deformities such as biceps tendon rupture or (peri-)articular fractures of the elbow are often related to a decrease in muscle strength. Postoperative evaluation of these deformities requires normative values of elbow strength. The purpose of this systematic review was to determine these normative values of isometric elbow strength in healthy adults resulting from studies evaluating this strength (i.e. flexion, extension, pronation and supination strength). The databases of PubMed, EMBASE and Web of Sciences were searched and screened for studies involving the isometric elbow strength as measured in asymptomatic volunteers. The quality of the studies was assessed and studies of low quality were excluded. Nineteen studies met the inclusion criteria and were of sufficiently high quality to be included in the present review. In these studies, elbow strength was measured in a total of 1880 healthy volunteers. The experimental set-up and devices used to measure elbow strength varied between studies. Using some assumptions, a normative values table was assembled. Large standard deviations of normative values in combination with different measurement devices used, as well as the different measurement positions of the subjects, demonstrated that there is no consensus about measuring the isometric elbow strength and therefore the normative values have to be interpreted with caution.

Exploiting enzyme catalysis in ultra-low ion strength media for impedance biosensing of avian influenza virus using a bare interdigitated electrode.

PubMed

Fu, Yingchun; Callaway, Zachary; Lum, Jacob; Wang, Ronghui; Lin, Jianhan; Li, Yanbin

2014-02-18

Enzyme catalysis is broadly used in various fields but generally applied in media with high ion strength. Here, we propose the exploitation of enzymatic catalysis in ultra-low ion strength media to induce ion strength increase for developing a novel impedance biosensing method. Avian influenza virus H5N1, a serious worldwide threat to poultry and human health, was adopted as the analyte. Magnetic beads were modified with H5N1-specific aptamer to capture the H5N1 virus. This was followed by binding concanavalin A (ConA), glucose oxidase (GOx), and Au nanoparticles (AuNPs) to create bionanocomposites through a ConA-glycan interaction. The yielded sandwich complex was transferred to a glucose solution to trigger an enzymatic reaction to produce gluconic acid, which ionized to increase the ion strength of the solution, thus decreasing the impedance on a screen-printed interdigitated array electrode. This method took advantages of the high efficiency of enzymatic catalysis and the high susceptibility of electrochemical impedance on the ion strength and endowed the biosensor with high sensitivity and a detection limit of 8 × 10(-4) HAU in 200 μL sample, which was magnitudes lower than that of some analogues based on biosensing methods. Furthermore, the proposed method required only a bare electrode for measurements of ion strength change and had negligible change on the surficial properties of the electrode, though some modification of magnetic beads/Au nanoparticles and the construction of a sandwich complex were still needed. This helped to avoid the drawbacks of commonly used electrode immobilization methods. The merit for this method makes it highly useful and promising for applications. The proposed method may create new possibilities in the broad and well-developed enzymatic catalysis fields and find applications in developing sensitive, rapid, low-cost, and easy-to-operate biosensing and biocatalysis devices.

Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation

NASA Astrophysics Data System (ADS)

Jiang, Suihe; Wang, Hui; Wu, Yuan; Liu, Xiongjun; Chen, Honghong; Yao, Mengji; Gault, Baptiste; Ponge, Dirk; Raabe, Dierk; Hirata, Akihiko; Chen, Mingwei; Wang, Yandong; Lu, Zhaoping

2017-04-01

Next-generation high-performance structural materials are required for lightweight design strategies and advanced energy applications. Maraging steels, combining a martensite matrix with nanoprecipitates, are a class of high-strength materials with the potential for matching these demands. Their outstanding strength originates from semi-coherent precipitates, which unavoidably exhibit a heterogeneous distribution that creates large coherency strains, which in turn may promote crack initiation under load. Here we report a counterintuitive strategy for the design of ultrastrong steel alloys by high-density nanoprecipitation with minimal lattice misfit. We found that these highly dispersed, fully coherent precipitates (that is, the crystal lattice of the precipitates is almost the same as that of the surrounding matrix), showing very low lattice misfit with the matrix and high anti-phase boundary energy, strengthen alloys without sacrificing ductility. Such low lattice misfit (0.03 ± 0.04 per cent) decreases the nucleation barrier for precipitation, thus enabling and stabilizing nanoprecipitates with an extremely high number density (more than 1024 per cubic metre) and small size (about 2.7 ± 0.2 nanometres). The minimized elastic misfit strain around the particles does not contribute much to the dislocation interaction, which is typically needed for strength increase. Instead, our strengthening mechanism exploits the chemical ordering effect that creates backstresses (the forces opposing deformation) when precipitates are cut by dislocations. We create a class of steels, strengthened by Ni(Al,Fe) precipitates, with a strength of up to 2.2 gigapascals and good ductility (about 8.2 per cent). The chemical composition of the precipitates enables a substantial reduction in cost compared to conventional maraging steels owing to the replacement of the essential but high-cost alloying elements cobalt and titanium with inexpensive and lightweight aluminium. Strengthening of this class of steel alloy is based on minimal lattice misfit to achieve maximal precipitate dispersion and high cutting stress (the stress required for dislocations to cut through coherent precipitates and thus produce plastic deformation), and we envisage that this lattice misfit design concept may be applied to many other metallic alloys.

Ultrastrong steel via minimal lattice misfit and high-density nanoprecipitation.

PubMed

Jiang, Suihe; Wang, Hui; Wu, Yuan; Liu, Xiongjun; Chen, Honghong; Yao, Mengji; Gault, Baptiste; Ponge, Dirk; Raabe, Dierk; Hirata, Akihiko; Chen, Mingwei; Wang, Yandong; Lu, Zhaoping

2017-04-27

Next-generation high-performance structural materials are required for lightweight design strategies and advanced energy applications. Maraging steels, combining a martensite matrix with nanoprecipitates, are a class of high-strength materials with the potential for matching these demands. Their outstanding strength originates from semi-coherent precipitates, which unavoidably exhibit a heterogeneous distribution that creates large coherency strains, which in turn may promote crack initiation under load. Here we report a counterintuitive strategy for the design of ultrastrong steel alloys by high-density nanoprecipitation with minimal lattice misfit. We found that these highly dispersed, fully coherent precipitates (that is, the crystal lattice of the precipitates is almost the same as that of the surrounding matrix), showing very low lattice misfit with the matrix and high anti-phase boundary energy, strengthen alloys without sacrificing ductility. Such low lattice misfit (0.03 ± 0.04 per cent) decreases the nucleation barrier for precipitation, thus enabling and stabilizing nanoprecipitates with an extremely high number density (more than 10 24 per cubic metre) and small size (about 2.7 ± 0.2 nanometres). The minimized elastic misfit strain around the particles does not contribute much to the dislocation interaction, which is typically needed for strength increase. Instead, our strengthening mechanism exploits the chemical ordering effect that creates backstresses (the forces opposing deformation) when precipitates are cut by dislocations. We create a class of steels, strengthened by Ni(Al,Fe) precipitates, with a strength of up to 2.2 gigapascals and good ductility (about 8.2 per cent). The chemical composition of the precipitates enables a substantial reduction in cost compared to conventional maraging steels owing to the replacement of the essential but high-cost alloying elements cobalt and titanium with inexpensive and lightweight aluminium. Strengthening of this class of steel alloy is based on minimal lattice misfit to achieve maximal precipitate dispersion and high cutting stress (the stress required for dislocations to cut through coherent precipitates and thus produce plastic deformation), and we envisage that this lattice misfit design concept may be applied to many other metallic alloys.

Biaxial Testing of High-Strength Fabric Improves Design of Inflatable Radar Domes

NASA Technical Reports Server (NTRS)

Krause, David L.; Bartolotta, Paul A.

2001-01-01

Large radar installations around the globe continuously watch the skies, unobtrusively providing security to the United States; these systems have been in active use for the past 50 years. Often situated in extreme environments, the radar dishes require shielding from the harsh elements. Air-inflated domes (over 100 ft in diameter) are one structure of choice for providing this essential protection. The radomes are constructed from highstrength fabric that is strong enough to withstand the inflation pressure, high winds, and other environmental loads, yet transparent to the microwave signal to allow precise radar mapping. This fabric is woven from glass fibers for high strength and embedded in a polytetrafluoroethylene resin matrix, akin to the nonstick coatings used on cookware.

[Health-related strength and power training in seniors: Purpose and recommendations].

PubMed

Donath, Lars; Faude, Oliver; Bopp, Micha; Zahner, Lukas

2015-05-01

The proportion of older people in western societies rapidly increases. Aging-induced disease conditions accompanied with declines in cardiocirculatory and neuromuscular performance constitute a major individual and economic health burden. Besides decreasing vascular and cardiac function during the process of aging, a loss of skeletal muscle mass, muscle structure and function seem to mainly account for decreasing maximal strength, strength development and strength endurance. These findings adversely interfer with static and dynamic postural control and may lead to an increased risk of falling with impairments of autonomy and quality of life. Traditional strength training recommendations basing on health-related exercise prescriptions for elderly people have been proven to counteract or at least attenuate aging-induced declines of neuromuscular muscular function. Multimodal and combined strength and balance training deliver additional improvements of neuromuscular capacity. Recent evidence additionally underpin the need of trunk muscle training and claimed for regimes considering explosive and high-velocity strength training in seniors. High quality RCTs revealed notable strength training effects on mobility, autonomy, quality of life and the reduction of the risk of falling (up to 50%). Available evidence also indicates that various strength training regimes elicit preventive and therapeutic effects on osteoporosis, diabetes type 2 and other chronic diseases, with effect sizes comparable to medication intake. Thus, health care providers, health insurances, Employers' Liability Insurance Associations and politicians should promote infrastructural developments that enable feasible and cost-effective access to health-related fitness centers or other sport facilities (e. g. sport clubs). These environmental requirements should be embedded in multi-centric education programs and campaigns that might enable regularly conducted strength and endurance training perceived as beneficial and valuable from an individual health care perspective.

Increased Antibiotic Release from a Bone Cement Containing Bacterial Cellulose

PubMed Central

Nakai, Takahisa; Enomoto, Koichi; Uchio, Yuji; Yoshino, Katsumi

2010-01-01

Background Major disadvantages of antibiotic bone cements include limited drug release and reduced strength resulting from the addition of high doses of antibiotics. Bacterial cellulose, a three-dimensional hydrophilic mesh, may retain antibiotics and release them gradually. We hypothesized that the addition of cellulose to antibiotic bone cement would improve mechanical strength and antibiotic release. Questions/purposes We therefore examined the mechanical strength and antibiotic release of cellulose antibiotic cement. Methods A high dose of antibiotics (5 g per 40 g cement powder) was incorporated into bacterial cellulose and then mixed with bone cement. We compared the compression strength, fracture toughness, fatigue life, and elution kinetics of this formulation with those of plain cement and a traditional antibiotic cement. Results The average values for compression strength, fracture toughness, and fatigue life of the cellulose antibiotic cement were 97%, 97%, and 78% of the values obtained for plain cement, respectively. The corresponding values for the traditional antibiotic cement were 79%, 82%, and 17%, respectively. The cumulative elution over 35 days was 129% greater from the cellulose antibiotic cement than from the traditional antibiotic cement. Conclusions With a high dose of antibiotics, incorporating cellulose into the bone cement prevented compression and fracture fragility, improved fatigue life, and increased antibiotic elution. Clinical Relevance Antibiotic cements containing cellulose may have applications in clinical situations that require high levels of antibiotic release and preservation of the mechanical properties of the cement. PMID:20945120

Fatigue and fracture properties of a super-austenitic stainless steel at 295 K and 4 K

NASA Astrophysics Data System (ADS)

McRae, D. M.; Walsh, R. P.; Dalder, E. N. C.; Litherland, S.; Trosen, M.; Kuhlmann, D. J.

2014-01-01

The tie plate structure for the ITER Central Solenoid (CS) is required to have high strength and good fatigue and fracture behavior at both room temperature and 4 K. A super-austenitic stainless steel - UNS 20910, commonly referred to by its trade name, Nitronic 50 (N50) - has been chosen for consideration to fulfill this task, due to its good room temperature and cryogenic yield strengths and weldability. Although N50 is often considered for cryogenic applications, little published data exists at 4 K. Here, a full series of tests have been conducted at 295 K and 4 K, and static tensile properties of four forgings of commercially-available N50 are reported along with fatigue life, fatigue crack growth rate (FCGR), and fracture toughness data. This study makes a significant contribution to the cryogenic mechanical properties database of high strength, paramagnetic alloys with potential for superconducting magnet applications.

The Evolution of Plate and Extruded Products with High Strength and Fracture Toughness

NASA Astrophysics Data System (ADS)

Denzer, D. K.; Rioja, R. J.; Bray, G. H.; Venema, G. B.; Colvin, E. L.

From the first use of 2017-T74 on the Junkers F13, improvements have been made to plate and extruded products for applications requiring the highest attainable strength and adequate fracture toughness. One such application is the upper wing of large aircraft. The progression of these product improvements achieved through the development of alloys that include 7075-(T6 & T76), 7150-(T6 & T77) and 7055-(T77 & T79) and most recently 7255-(T77 & T79) is reviewed. The most current advancements include aluminum-copper-lithium, alloy 2055 plate and extruded products that can attain strength equivalent to that of 7055-T77 with higher modulus, similar fracture toughness and improved fatigue, fatigue crack growth and corrosion performance. The achievement of these properties is explained in terms of the several alloy design principles. The highly desired and balanced characteristics make these products ideal for upper wing applications.

Structural studies with the use of XRD and Mössbauer spectroscopy of new high Manganese steels

NASA Astrophysics Data System (ADS)

Jablonska, Magdalena Barbara

2014-04-01

New high-strength austenitic and austenitic-ferritic manganese steels represent a significant potential in applications for structural components in the automotive and railway industry due to the excellent combination of high mechanical properties and good plasticity. They belong to the group of steels called AHSS (Advanced High Strength Steels) and UHSS (Ultra High Strength Steels). Application of this combination of properties allows a reduction in the weight of vehicles by the use of reduced cross-section components, and thus to reduce fuel consumption. The development and implementation of industrial production of such interesting and promising steel and its use as construction material requires an improvement of their casting properties and susceptibility to deformation in plastic working conditions. In this work, XRD, Transmission Mössbauer Spectroscopy and Conversion Electron Mössbauer Spectroscopy were employed in a study of the new high-manganese steels with a austenite and austenite-ferrite structure. The influence of the plastic deformation parameters on the changes in the structure, distribution of ferrite and disclosure of the presence of carbides was determined. The analysis of phase transformations in various times using CEMS method made possible to reveal their fine details.

Mechanical and biological behavior of ultrafine-grained Ti alloy aneurysm clip processed using high-pressure torsion.

PubMed

Um, Ho Yong; Park, Byung Ho; Ahn, Dong-Hyun; Abd El Aal, Mohamed Ibrahim; Park, Jaechan; Kim, Hyoung Seop

2017-04-01

Severe plastic deformation (SPD) has recently been advanced as the main process for fabricating bulk ultrafine grained or nanocrystalline metallic materials, which present much higher strength and better bio-compatibility than coarse-grained counterparts. Medical devices, such as aneurysm clips and dental implants, require high mechanical and biological performance (e.g., stiffness, yield strength, fatigue resistance, and bio-compatibility). These requirements match well the characteristics of SPD-processed materials. Typical aneurysm clips are made of a commercial Ti-6Al-4V alloy, which has higher yield strength than Ti. In this work, Ti and Ti-6Al-4V workpieces were processed by high-pressure torsion (HPT) to enhance their mechanical properties. Tensile tests and hardness tests were performed to evaluate their mechanical properties, and their microstructure was investigated. The hardness and yield stress of the HPT-processed Ti are comparable to those of the initial Ti-6Al-4V due to significantly refined microstructure. Finite element analyses for evaluating the opening performance of a specific geometry of the YASARGIL aneurysm clip were carried out using mechanical properties of the initial and HPT-processed Ti and Ti-6Al-4V. These results indicate that SPD-processed Ti could be a good candidate to substitute for Ti-6Al-4V in aneurysm clips. Copyright © 2017 Elsevier Ltd. All rights reserved.

Global motion compensated visual attention-based video watermarking

NASA Astrophysics Data System (ADS)

Oakes, Matthew; Bhowmik, Deepayan; Abhayaratne, Charith

2016-11-01

Imperceptibility and robustness are two key but complementary requirements of any watermarking algorithm. Low-strength watermarking yields high imperceptibility but exhibits poor robustness. High-strength watermarking schemes achieve good robustness but often suffer from embedding distortions resulting in poor visual quality in host media. This paper proposes a unique video watermarking algorithm that offers a fine balance between imperceptibility and robustness using motion compensated wavelet-based visual attention model (VAM). The proposed VAM includes spatial cues for visual saliency as well as temporal cues. The spatial modeling uses the spatial wavelet coefficients while the temporal modeling accounts for both local and global motion to arrive at the spatiotemporal VAM for video. The model is then used to develop a video watermarking algorithm, where a two-level watermarking weighting parameter map is generated from the VAM saliency maps using the saliency model and data are embedded into the host image according to the visual attentiveness of each region. By avoiding higher strength watermarking in the visually attentive region, the resulting watermarked video achieves high perceived visual quality while preserving high robustness. The proposed VAM outperforms the state-of-the-art video visual attention methods in joint saliency detection and low computational complexity performance. For the same embedding distortion, the proposed visual attention-based watermarking achieves up to 39% (nonblind) and 22% (blind) improvement in robustness against H.264/AVC compression, compared to existing watermarking methodology that does not use the VAM. The proposed visual attention-based video watermarking results in visual quality similar to that of low-strength watermarking and a robustness similar to those of high-strength watermarking.

Nanoscale origins of the damage tolerance of the high-entropy alloy CrMnFeCoNi

DOE PAGES

Zhang, ZiJiao; Mao, M. M.; Wang, Jiangwei; ...

2015-12-09

Damage tolerance can be an elusive characteristic of structural materials requiring both high strength and ductility, properties that are often mutually exclusive. High-entropy alloys are of interest in this regard. Specifically, the single-phase CrMnFeCoNi alloy displays tensile strength levels of ~1 GPa, excellent ductility (~60–70%) and exceptional fracture toughness (KJIc>200M Pa√m). Here through the use of in situ straining in an aberration-corrected transmission electron microscope, we report on the salient atomistic to micro-scale mechanisms underlying the origin of these properties. We identify a synergy of multiple deformation mechanisms, rarely achieved in metallic alloys, which generates high strength, work hardening andmore » ductility, including the easy motion of Shockley partials, their interactions to form stacking-fault parallelepipeds, and arrest at planar slip bands of undissociated dislocations. In conclusion, we further show that crack propagation is impeded by twinned, nanoscale bridges that form between the near-tip crack faces and delay fracture by shielding the crack tip.« less

Nanoscale origins of the damage tolerance of the high-entropy alloy CrMnFeCoNi

PubMed Central

Zhang, ZiJiao; Mao, M. M.; Wang, Jiangwei; Gludovatz, Bernd; Zhang, Ze; Mao, Scott X.; George, Easo P.; Yu, Qian; Ritchie, Robert O.

2015-01-01

Damage tolerance can be an elusive characteristic of structural materials requiring both high strength and ductility, properties that are often mutually exclusive. High-entropy alloys are of interest in this regard. Specifically, the single-phase CrMnFeCoNi alloy displays tensile strength levels of ∼1 GPa, excellent ductility (∼60–70%) and exceptional fracture toughness (KJIc>200 MPa√m). Here through the use of in situ straining in an aberration-corrected transmission electron microscope, we report on the salient atomistic to micro-scale mechanisms underlying the origin of these properties. We identify a synergy of multiple deformation mechanisms, rarely achieved in metallic alloys, which generates high strength, work hardening and ductility, including the easy motion of Shockley partials, their interactions to form stacking-fault parallelepipeds, and arrest at planar slip bands of undissociated dislocations. We further show that crack propagation is impeded by twinned, nanoscale bridges that form between the near-tip crack faces and delay fracture by shielding the crack tip. PMID:26647978

Latest Development and Application of Nb-Bearing High Strength Pipeline Steels

NASA Astrophysics Data System (ADS)

Zhang, Yongqing; Shang, Chengjia; Guo, Aimin; Zheng, Lei; Niu, Tao; Han, Xiulin

In order to solve the pollution problem emerging in China recently, China's central government is making great efforts to raise the percentage of natural gas consumption in the China's primary energy mix, which needs to construct big pipelines to transport natural gas from the nation's resource-rich western regions to the energy-starved east, as well as import from the Central Asia and Russia. With this mainstream trend, high strength, high toughness, heavy gauge, and large diameter pipeline steels are needed to improve the transportation efficiency. This paper describes the latest progresses in Nb-bearing high strength pipeline steels with regard to metallurgical design, development and application, including X80 coil with a thickness up to 22.0mm, X80 plate with a diameter as much as 1422mm, X80 plate with low-temperature requirements and low-Mn sour service X65 for harsh sour service environments. Moreover, based on widely accepted TMCP and HTP practices with low carbon and Nb micro-alloying design, this paper also investigated some new metallurgical phenomena based on powerful rolling mills and heavy ACC equipment.

Improving resistance of high strength concrete (HSC) bridge beams to frost and defrosting salt attack by application of hydrophobic agent

NASA Astrophysics Data System (ADS)

Kolisko, Jiri; Balík, Lukáš; Kostelecka, Michaela; Pokorný, Petr

2017-09-01

HSC (High Strength Concrete) is increasingly used for bearing bridge structures nowadays. Bridge structures in the Czech Republic are exposed to severe conditions in winter time and durability of the concrete is therefore a crucial requirement. The high strength and low water absorption of HSC suggests that the material will have high durability. However, the situation may not be so straightforward. We carried out a study of the very poor durability of HSC concrete C70/85 used to produce prestresed beams 37.1 m in length to build a 6-span highway bridge. After the beams were cast, a production control test indicated some problems with the durability of the concrete. There was a danger that 42 of the beams would not be suitable for use. All participants in the bridge project finally decided, after extensive discussions, to attempt to improve the durability of the concrete by applying a hydrophobic agent. Paper will present the results of comparative tests of four hydrophobic agents in order to choose one for real application and describes this application on construction site.

Mechanical and low-cycle fatigue behavior of stainless reinforcing steel for earthquake engineering applications

NASA Astrophysics Data System (ADS)

Zhou, Yihui; Ou, Yu-Chen; Lee, George C.; O'Connor, Jerome S.

2010-09-01

Use of stainless reinforcing steel (SRS) in reinforced concrete (RC) structures is a promising solution to corrosion issues. However, for SRS to be used in seismic applications, several mechanical properties need to be investigated. These include specified and actual yield strengths, tensile strengths, uniform elongations and low-cycle fatigue behavior. Three types of SRSs (Talley S24100, Talley 316LN and Talley 2205) were tested and the results are reported in this paper. They were compared with the properties of A706 carbon reinforcing steel (RS), which is typical for seismic applications, and MMFX II, which is a high strength, corrosion resistant RS. Low-cycle fatigue tests of the RS coupons were conducted under strain control with constant amplitude to obtain strain life models of the steels. Test results show that the SRSs have slightly lower moduli of elasticity, higher uniform elongations before necking, and better low-cycle fatigue performance than A706 and MMFX II. All five types of RSs tested satisfy the requirements of the ACI 318 code on the lower limit of the tensile to yield strength ratio. Except Talley 2205, the other four types of RSs investigated meet the ACI 318 requirement that the actual yield strength does not exceed the specified yield strength by more than 18 ksi (124 MPa). Among the three types of SRSs tested, Talley S24100 possesses the highest uniform elongation before necking, and the best low-cycle fatigue performance.

Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)

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

Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu

Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds weremore » made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.« less

Ceramic Borehole Seals for Nuclear Waste Disposal Applications

NASA Astrophysics Data System (ADS)

Lowry, B.; Coates, K.; Wohletz, K.; Dunn, S.; Patera, E.; Duguid, A.; Arnold, B.; Zyvoloski, G.; Groven, L.; Kuramyssova, K.

2015-12-01

Sealing plugs are critical features of the deep borehole system design. They serve as structural platforms to bear the weight of the backfill column, and as seals through their low fluid permeability and bond to the borehole or casing wall. High hydrostatic and lithostatic pressures, high mineral content water, and elevated temperature due to the waste packages and geothermal gradient challenge the long term performance of seal materials. Deep borehole nuclear waste disposal faces the added requirement of assuring performance for thousands of years in large boreholes, requiring very long term chemical and physical stability. A high performance plug system is being developed which capitalizes on the energy of solid phase reactions to form a ceramic plug in-situ. Thermites are a family of self-oxidized metal/oxide reactions with very high energy content and the ability to react under water. When combined with engineered additives the product exhibits attractive structural, sealing, and corrosion properties. In the initial phase of this research, exploratory and scaled tests demonstrated formulations that achieved controlled, fine grained, homogeneous, net shape plugs composed predominantly of ceramic material. Laboratory experiments produced plug cores with confined fluid permeability as low as 100 mDarcy, compressive strength as high as 70 MPa (three times the strength of conventional well cement), with the inherent corrosion resistance and service temperature of ceramic matrices. Numerical thermal and thermal/structural analyses predicted the in-situ thermal performance of the reacted plugs, showing that they cooled to ambient temperature (and design strength) within 24 to 48 hours. The current development effort is refining the reactant formulations to achieve desired performance characteristics, developing the system design and emplacement processes to be compatible with conventional well service practices, and understanding the thermal, fluid, and structural effects the plug will have on surrounding media. This paper will report on the state of the development effort and plans for a field demonstration in early 2016 in a cased well with traditional plug seal and strength measurements.

Effects of Testing Method on Stretch-Flangeability of Dual-Phase 980/1180 Steel Grades

NASA Astrophysics Data System (ADS)

Madrid, Mykal; Van Tyne, Chester J.; Sadagopan, Sriram; Pavlina, Erik J.; Hu, Jun; Clarke, Kester D.

2018-04-01

Challenging fuel economy and safety standards in the automotive industry have led to the need for materials with higher strength while maintaining levels of formability that meet component manufacturing requirements. Advanced high-strength steels, such as dual-phase steels with tensile strengths of 980 MPa and 1180 MPa, are of interest to address this need. Increasing the strength of these materials typically comes at the expense of ductility, which may result in problems when stamping parts with trimmed or sheared edges, as cracking at the sheared edge may occur at lower strains. Here, hole expansion tests were performed with different punch geometries (conical and flat-bottom) and different edge conditions (sheared and machined) to understand the effects of testing conditions on performance, and these results are discussed in terms of mechanical properties and microstructures.

Effects of Testing Method on Stretch-Flangeability of Dual-Phase 980/1180 Steel Grades

NASA Astrophysics Data System (ADS)

Madrid, Mykal; Van Tyne, Chester J.; Sadagopan, Sriram; Pavlina, Erik J.; Hu, Jun; Clarke, Kester D.

2018-06-01

Challenging fuel economy and safety standards in the automotive industry have led to the need for materials with higher strength while maintaining levels of formability that meet component manufacturing requirements. Advanced high-strength steels, such as dual-phase steels with tensile strengths of 980 MPa and 1180 MPa, are of interest to address this need. Increasing the strength of these materials typically comes at the expense of ductility, which may result in problems when stamping parts with trimmed or sheared edges, as cracking at the sheared edge may occur at lower strains. Here, hole expansion tests were performed with different punch geometries (conical and flat-bottom) and different edge conditions (sheared and machined) to understand the effects of testing conditions on performance, and these results are discussed in terms of mechanical properties and microstructures.

Pervious concrete mix optimization for sustainable pavement solution

NASA Astrophysics Data System (ADS)

Barišić, Ivana; Galić, Mario; Netinger Grubeša, Ivanka

2017-10-01

In order to fulfill requirements of sustainable road construction, new materials for pavement construction are investigated with the main goal to preserve natural resources and achieve energy savings. One of such sustainable pavement material is pervious concrete as a new solution for low volume pavements. To accommodate required strength and porosity as the measure of appropriate drainage capability, four mixtures of pervious concrete are investigated and results of laboratory tests of compressive and flexural strength and porosity are presented. For defining the optimal pervious concrete mixture in a view of aggregate and financial savings, optimization model is utilized and optimal mixtures defined according to required strength and porosity characteristics. Results of laboratory research showed that comparing single-sized aggregate pervious concrete mixtures, coarse aggregate mixture result in increased porosity but reduced strengths. The optimal share of the coarse aggregate turn to be 40.21%, the share of fine aggregate is 49.79% for achieving required compressive strength of 25 MPa, flexural strength of 4.31 MPa and porosity of 21.66%.

Environment-friendly wood fibre composite with high bonding strength and water resistance

PubMed Central

Ji, Xiaodi; Dong, Yue; Nguyen, Tat Thang; Chen, Xueqi

2018-01-01

With the growing depletion of wood-based materials and concerns over emissions of formaldehyde from traditional wood fibre composites, there is a desire for environment-friendly binders. Herein, we report a green wood fibre composite with specific bonding strength and water resistance that is superior to a commercial system by using wood fibres and chitosan-based adhesives. When the mass ratio of solid content in the adhesive and absolute dry wood fibres was 3%, the bonding strength and water resistance of the wood fibre composite reached the optimal level, which was significantly improved over that of wood fibre composites without adhesive and completely met the requirements of the Chinese national standard GB/T 11718-2009. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations revealed that the excellent performance of the binder might partly be due to the amide linkages and hydrogen bonding between wood fibres and the chitosan-based adhesive. We believe that this strategy could open new insights into the design of environment-friendly wood fibre composites with high bonding strength and water resistance for multifunctional applications. PMID:29765653

Environment-friendly wood fibre composite with high bonding strength and water resistance

NASA Astrophysics Data System (ADS)

Ji, Xiaodi; Dong, Yue; Nguyen, Tat Thang; Chen, Xueqi; Guo, Minghui

2018-04-01

With the growing depletion of wood-based materials and concerns over emissions of formaldehyde from traditional wood fibre composites, there is a desire for environment-friendly binders. Herein, we report a green wood fibre composite with specific bonding strength and water resistance that is superior to a commercial system by using wood fibres and chitosan-based adhesives. When the mass ratio of solid content in the adhesive and absolute dry wood fibres was 3%, the bonding strength and water resistance of the wood fibre composite reached the optimal level, which was significantly improved over that of wood fibre composites without adhesive and completely met the requirements of the Chinese national standard GB/T 11718-2009. Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations revealed that the excellent performance of the binder might partly be due to the amide linkages and hydrogen bonding between wood fibres and the chitosan-based adhesive. We believe that this strategy could open new insights into the design of environment-friendly wood fibre composites with high bonding strength and water resistance for multifunctional applications.

Effect of Prestrain on Precipitation Behaviors of Ti-2.5Cu Alloy

NASA Astrophysics Data System (ADS)

Lincai, Zhang; Xiaoming, Ding; Wei, Ye; Man, Zhang; Zhenya, Song

2018-04-01

As a special hardenable α titanium alloy, Ti-2.5 Cu alloy was a candidate material for high temperature components requiring high strength and plasticity. The effect of prestrain on the precipitation behaviors was investigated in the present study. Tensile tests show that elongation up to 22 % can be obtained after solid solution (SS) treatment. Thereafter, prestrain in tension with 5 %, 10 %, 15 % and 20 % was carried out for the SS samples and then duplex aging was applied. Transmitting electron microscopy (TEM) investigations show that larger Ti2Cu particles were observed in the prestrained condition than free aging one, as prestrain significantly speeds up the precipitation kinetics. The strength firstly increases and then decreases for the prestrained samples after duplex aging, where the competition between precipitation hardening and recovery softening should be responsible. With the consideration of SS, precipitation and recovery, a strength model for duplex aging combined with prestrain was established, which is in well agreement with experiments. Present study may provide a promising way to obtain the strength of deformed hcp materials in industry application.

An Investigation of Crystalline Intensity of the Wood of Poplar Clones Grown in Jiangsu Province, China

Treesearch

Bernard R. Parresol; Fuliang Cao

1998-01-01

To establish manmade poplar (Populus spp.) clonal forests for industrial uses, two requirements must be met. First, forests must have high yield;and second, wood fibers must have specific mechanical properties. For example, both fiberboard and plywood require fibers with a certain stiffness and strength. In fact, fiber characteristics are closely related to the fiber?s...

Precision glass molding of high-resolution diffractive optical elements

NASA Astrophysics Data System (ADS)

Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

2016-04-01

The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

Fundamental Insulation Characteristics of Air, N2, CO2, N2/O2 and SF6/N2 Mixed Gases

NASA Astrophysics Data System (ADS)

Rokunohe, Toshiaki; Yagihashi, Yoshitaka; Endo, Fumihiro; Oomori, Takashi

SF6 gas has excellent dielectric strength and interruption performance. For these reasons, it has been widely used for gas insulated switchgear (GIS). However, use of SF6 gas has become regulated under agreements set at the 1997 COP3. Presently, development of a gas circuit breaker (GCB) using CO2 gas and development of a high voltage vacuum circuit breaker (VCB) are being pursued. GIS consists of disconnectors (DS), earthing switches (ES) and buses in addition to GCB. Since the interruption performance is not an important requirement for DS, ES and BUS, use of a gas with high dielectric strength is better than use of a gas with good interruption performance. Air and N2 are not greenhouse gases, and their dielectric strengths are higher than those of other SF6 alternative gases, but only about one-third of the dielectric strength of SF6 gas. This paper deals with a suitable insulation gas which has no greenhouse effect as an SF6 alternative gas. The N2/O2 mixed gas was investigated by changing the ratio of O2. Moreover, the effect of an insulation coating was investigated and compared with the dielectric strength of SF6/N2 mixed gas. The dielectric strength of air under the coating condition was equal to that of 10%SF6/N2 mixed gas.

Magnetic moments, E3 transitions and the structure of high-spin core excited states in 211Rn

NASA Astrophysics Data System (ADS)

Poletti, A. R.; Dracoulis, G. D.; Byrne, A. P.; Stuchbery, A. E.; Poletti, S. J.; Gerl, J.; Lewis, P. M.

1985-05-01

The results of g-factor measurements of high-spin states in 211Rn are: Ex = 8856 + Δ' keV (Jπ = 63/2-), g = 0.626(7); 6101 + Δ' KeV (49/2+), 0.766(8); 5347 + Δ' KeV (43/2-), 0.74(2); 3927 + Δ KeV (35/2+), 1.017(12); 1578 + Δ KeV (17/2-), 0.912(9). These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in 211Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously.

Comparative study of the physical properties of core materials.

PubMed

Saygili, Gülbin; Mahmali, Sevil M

2002-08-01

This study was undertaken to measure physical properties of materials used for direct core buildups, including high-copper amalgam, visible light-cured resin composite, autocured titanium-containing composite, polyacid-modified composite, resin-modified glass-ionomer, and silver cermet cement. Compressive strength, diametral tensile strength, and flexural strength of six core materials of various material classes were measured for each material as a function of time up to 3 months at different storage conditions, using a standard specification test designed for the materials. Three different storage conditions (dry, humid, wet) at 37 degrees C were chosen. Materials were manipulated according to manufacturers' instructions for use as cores. Mean compressive, diametral tensile, and flexural strengths with associated standard deviations were calculated for each material. Multiple comparison and Newman-Keuls tests discerned many differences among materials. All materials were found to meet the minimum specification requirements, except in terms of flexural strength for amalgam after 1 hour and the silver cermet at all time intervals.

Polarographic determination of lead hydroxide formation constants at low ionic strength

USGS Publications Warehouse

Lind, Carol J.

1978-01-01

Values of formation constants for lead hydroxide at 25 ??C were calculated from normal pulse polarographic measurements of 10-6 M lead in 0.01 M sodium perchlorate. The low concentrations simulate those found in many freshwaters, permitting direct application of the values when considering distributions of lead species. The precise evaluation of species distribution in waters at other ionic strengths requires activity coefficient corrections. As opposed to much of the previously published work done at high ionic strength, the values reported here were obtained at low ionic strength, permitting use of smaller and better defined activity coefficient corrections. These values were further confirmed by differential-pulse polarography and differential-pulse anodic stripping voltammetry data. The logs of the values for ??1??? ??2???, and ??3??? were calculated to be 6.59, 10.80, and 13.63, respectively. When corrected to zero ionic strength these values were calculated to be 6.77, 11.07, and 13.89, respectively.

Using carboxylated nanocrystalline cellulose as an additive in cellulosic paper and poly (vinyl alcohol) fiber paper.

PubMed

Cha, Ruitao; Wang, Chengyu; Cheng, Shaoling; He, Zhibin; Jiang, Xingyu

2014-09-22

Specialty paper (e.g. cigarette paper and battery diaphragm paper) requires extremely high strength properties. The addition of strength agents plays an important role in increasing strength properties of paper. Nanocrystalline cellulose (NCC), or cellulose whiskers, has the potential to enhance the strength properties of paper via improving inter-fibers bonding. This paper was to determine the potential of using carboxylated nanocrystalline cellulose (CNCC) to improve the strength properties of paper made of cellulosic fiber or poly (vinyl alcohol) (PVA) fiber. The results indicated that the addition of CNCC can effectively improve the strength properties. At a CNCC dosage of 0.7%, the tear index and tensile index of the cellulosic paper reached the maximum of 12.8 mN m2/g and 100.7 Nm/g, respectively. More importantly, when increasing the CNCC dosage from 0.1 to 1.0%, the tear index and tensile index of PVA fiber paper were increased by 67.29%, 22.55%, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low Temperature Consolidation of Micro/Nanosilver Die-Attach Preforms

NASA Astrophysics Data System (ADS)

McCoppin, Jared; Reitz, Thomas L.; Miller, Ryan; Vijwani, Hema; Mukhopadhyay, Sharmila; Young, Daniel

2014-09-01

Organically passivated silver nanopowder paste-based sintering is considered a promising solution for die-attach in high temperature power and sensing electronic devices. However, oxygen requirements during burnout and inherently high shrinkage rates limit their use to small die sizes. This work reports an alternative fabrication method that resolves decomposition and shrinkage issues of the die-attach by utilizing a prestressed optimized tape cast mixture of micro- and nanosilver particles with a polypropylene carbonate binder. The effects of prestressing, micro/nanosilver bimodal distribution, and polymer content on resulting microstructure and shear strength were investigated. Prior to application as a die-attach, uniaxial compression of the tape was found to significantly decrease shrinkage and improve green strength. This pre-stressing strategy allows for a decoupling of the resulting die-attach materials properties from the pressure applied during assembly. Bimodal mixtures consisting of 1-3 μm spherical powders with nanosilver resulted in shear strengths comparable to those of pure nanosilver. Shear strength decreased as bimodal particle size increased above 5 μm. A polymer content of ˜10 wt.% polypropylene carbonate combined with prestressing was identified as optimal for maximizing die-attach shear strength while still maintaining pliability and formability. Tape casts that were prestressed to 212 MPa by uniaxially compression and formulated with 10 wt.% of polypropylene carbonate resulted in a die-attach material with a shear strength of 54 MPa when sintered. These materials were used to demonstrate void-free 25-mm2 die-attach assemblies, suggesting that tape cast micro/nanosilver materials may be a promising die-attach method for high temperature and large-area electronics devices.

Comparison of the Effect of Curing on the Properties of E-Glass/Cyanate modified Epoxy Cross Plied Laminates

NASA Astrophysics Data System (ADS)

Nallayan, W. Andrew; Vijayakumar, K. R.; Rasheed, Usama Tariq

2017-05-01

High performance polymer composite laminates that are used in Aerospace and Electronics industries requires laminates that are structurally rigid besides exhibiting high stiffness and good di electrical properties. They are required to be transparent to EM waves in order to transmit the signal with almost zero transmission loss. Response of the laminates under different loadings could hence establish a potent material combination with high structural strengths that could be used in sectors dealing with Signal transmissions. The results thus acquired can be used as a database for choosing relatively better materials for Radome and their advanced versions in the coming decades. To augment this, thin laminates with 4 plies with simple stacking configurations of 0/90/0/90 degrees as applicable to a cross plied laminates were fabricated with cyanate ester modified epoxy resin and 1200GSM E glass unidirectional fiber. Flexural and Impact strength were the properties identified for the accessing the structural responses of the Laminate as against room and oven curing conditions. FESEM images were applied to validate the experimental findings.

Selective laser melting of Inconel super alloy-a review

NASA Astrophysics Data System (ADS)

Karia, M. C.; Popat, M. A.; Sangani, K. B.

2017-07-01

Additive manufacturing is a relatively young technology that uses the principle of layer by layer addition of material in solid, liquid or powder form to develop a component or product. The quality of additive manufactured part is one of the challenges to be addressed. Researchers are continuously working at various levels of additive manufacturing technologies. One of the significant powder bed processes for met als is Selective Laser Melting (SLM). Laser based processes are finding more attention of researchers and industrial world. The potential of this technique is yet to be fully explored. Due to very high strength and creep resistance Inconel is extensively used nickel based super alloy for manufacturing components for aerospace, automobile and nuclear industries. Due to law content of Aluminum and Titanium, it exhibits good fabricability too. Therefore the alloy is ideally suitable for selective laser melting to manufacture intricate components with high strength requirements. The selection of suitable process for manufacturing for a specific component depends on geometrical complexity, production quantity, and cost and required strength. There are numerous researchers working on various aspects like metallurgical and micro structural investigations and mechanical properties, geometrical accuracy, effects of process parameters and its optimization and mathematical modeling etc. The present paper represents a comprehensive overview of selective laser melting process for Inconel group of alloys.

An extrapolation method for compressive strength prediction of hydraulic cement products

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

Siqueira Tango, C.E. de

1998-07-01

The basis for the AMEBA Method is presented. A strength-time function is used to extrapolate the predicted cementitious material strength for a late (ALTA) age, based on two earlier age strengths--medium (MEDIA) and low (BAIXA) ages. The experimental basis for the method is data from the IPT-Brazil laboratory and the field, including a long-term study on concrete, research on limestone, slag, and fly-ash additions, and quality control data from a cement factory, a shotcrete tunnel lining, and a grout for structural repair. The method applicability was also verified for high-performance concrete with silica fume. The formula for predicting late agemore » (e.g., 28 days) strength, for a given set of involved ages (e.g., 28,7, and 2 days) is normally a function only of the two earlier ages` (e.g., 7 and 2 days) strengths. This equation has been shown to be independent on materials variations, including cement brand, and is easy to use also graphically. Using the AMEBA method, and only needing to know the type of cement used, it has been possible to predict strengths satisfactorily, even without the preliminary tests which are required in other methods.« less

76 FR 55708 - Servicing Multi-Piece and Single Piece Rim Wheels; Extension of the Office of Management and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

... strength requirements specified in the Standard, and a requirement that defective wheels and wheel... or a Registered Professional Engineer must certify that the strength requirements specified in (d)(3...

Perspectives on Aerobic and Strength Influences on Military Physical Readiness: Report of an International Military Physiology Roundtable.

PubMed

Friedl, Karl E; Knapik, Joseph J; Häkkinen, Keijo; Baumgartner, Neal; Groeller, Herbert; Taylor, Nigel A S; Duarte, Antonio F A; Kyröläinen, Heikki; Jones, Bruce H; Kraemer, William J; Nindl, Bradley C

2015-11-01

Physical fitness training of military recruits is an enduring focus of armies. This is important for safe and effective performance of general tasks that anyone may have to perform in a military setting as well as preparation for more specialized training in specific job specialties. Decades of studies on occupationally specific physical requirements have characterized the dual aerobic and strength demands of typical military tasks; however, scientifically founded strategies to prepare recruits with a good mix of these 2 physiologically opposing capabilities have not been well established. High levels of aerobic training can compromise resistance training gains and increase injury rates. Resistance training requires a greater commitment of time and resources as well as a greater understanding of the science to produce true strength gains that may be beneficial to military performance. These are critical issues for modern armies with increased demands for well-prepared soldiers and fewer injury losses. The actual physical requirements tied to metrics of success in military jobs are also under renewed examination as women are increasingly integrated into military jobs previously performed only by men. At the third International Congress on Soldiers' Physical Performance, a roundtable of 10 physiologists with military expertise presented comparative perspectives on aerobic and strength training. These topics included the physiological basis of training benefits, how to train effectively, how to measure training effectiveness, considerations for the integration of women, and the big perspective. Key discussion points centered on (a) the significance of findings from research on integrated training, (b) strategies for effective strength development, and (c) injury reduction in training as well as the benefits of improved fitness to injury reduction across the force.

High-strength bolt corrosion fatigue life model and application.

PubMed

Hui-li, Wang; Si-feng, Qin

2014-01-01

The corrosion fatigue performance of high-strength bolt was studied. Based on the fracture mechanics theory and the Gerberich-Chen formula, the high-strength bolt corrosion fracture crack model and the fatigue life model were established. The high-strength bolt crack depth and the fatigue life under corrosion environment were quantitatively analyzed. The factors affecting high-strength bolt corrosion fatigue life were discussed. The result showed that the high-strength bolt corrosion fracture biggest crack depth reduces along with the material yield strength and the applied stress increases. The material yield strength was the major factor. And the high-strength bolt corrosion fatigue life reduced along with the increase of material strength, the applied stress or stress amplitude. The stress amplitude influenced the most, and the material yield strength influenced the least. Low bolt strength and a low stress amplitude level could extend high-strength bolt corrosion fatigue life.

Development of high strength siloxane poly(urethane-urea) elastomers based on linked macrodiols for heart valve application.

PubMed

Dandeniyage, Loshini S; Gunatillake, Pathiraja A; Adhikari, Raju; Bown, Mark; Shanks, Robert; Adhikari, Benu

2017-08-31

Mixed macrodiol based siloxane poly(urethane-urea)s (SiPUU) having number average molecular weights in the range 87-129 kDa/mol were synthesized to give elastomers with high tensile and tear strengths required to fabricate artificial heart valves. Polar functional groups were introduced into the soft segment to improve the poor segmental compatibility of siloxane polyurethanes. This was achieved by linking α,ω-bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane) (PDMS) or poly(hexamethylene oxide) (PHMO) macrodiols with either 4,4'-methylenediphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI) prior to polyurethane synthesis. The hard segment was composed of MDI, and a 1:1 mixture of 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane and 1,2-ethylene diamine. We report the effect of urethane linkers in soft segments on properties of the SiPUU. PHMO linked with either MDI or IPDI produced SiPUU with the highest tensile and tear strengths. Linking PDMS hardly affected the tensile strength; however, the tear strength was improved. The stress-strain curves showed no plastic deformation region typically observed for conventional polyurethanes indicating good creep resistance. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

Lightweight Shield for Centrifuge

NASA Technical Reports Server (NTRS)

Luper, C.

1982-01-01

Centrifuge bowl composed of laminated aluminum offers required combination of high strength at reduced weight. Around outside wall of bowl core of 1/16 inch thick spun aluminum are wrapped two layers of aluminum, each also one-sixteenth inch thick. Layered structure prevents cracks from propagating through wall.

49 CFR 180.407 - Requirements for test and inspection of specification cargo tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... constructed of mild steel or high-strength, low-alloy steel, that create air cavities adjacent to the tank...) Equipment must consist of: (A) A high frequency spark tester capable of producing sufficient voltage to...; and (C) A steel calibration coupon 30.5 cm × 30.5 cm (12 inches × 12 inches) covered with the same...

49 CFR 180.407 - Requirements for test and inspection of specification cargo tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... constructed of mild steel or high-strength, low-alloy steel, that create air cavities adjacent to the tank...) Equipment must consist of: (A) A high frequency spark tester capable of producing sufficient voltage to...; and (C) A steel calibration coupon 30.5 cm × 30.5 cm (12 inches × 12 inches) covered with the same...

49 CFR 180.407 - Requirements for test and inspection of specification cargo tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... constructed of mild steel or high-strength, low-alloy steel, that create air cavities adjacent to the tank...) Equipment must consist of: (A) A high frequency spark tester capable of producing sufficient voltage to...; and (C) A steel calibration coupon 30.5 cm × 30.5 cm (12 inches × 12 inches) covered with the same...

Development of a new generation of high-temperature composite materials

NASA Technical Reports Server (NTRS)

Brindley, Pamela K.

1987-01-01

There are ever-increasing demands to develop low-density materials that maintain high strength and stiffness properties at elevated temperatures. Such materials are essential if the requirements for advanced aircraft, space power generation, and space station plans are to be realized. Metal matrix composites and intermetallic matrix composites are currently being investigated at NASA Lewis for such applications because they offer potential increases in strength, stiffness, and use temperature at a lower density than the most advanced single-crystal superalloys presently available. Today's discussion centers around the intermetallic matrix composites proposed by Lewis for meeting advanced aeropropulsion requirements. The fabrication process currently being used at Lewis to produce intermetallic matrix composites will be reviewed, and the properties of one such composite, SiC/Ti3Al+Nb, will be presented. In addition, the direction of future research will be outlined, including plans for enhanced fabrication of aluminide composites by the arc spray technique and fiber development by the floating-zone process.

Defense Small Business Innovation Research Program (SBIR) FY 1984.

DTIC Science & Technology

1984-01-12

nuclear submarine non-metallic, light weight, high strength piping . Includes the development of adequate fabrication procedures for attaching pipe ...waste heat economizer methods, require development. Improved conventional and hybrid heat pipes and/or two phase transport devices 149 IF are required...DESCRIPTION: A need exists to conceive, design, fabricate and test a method of adjusting the length of the individual legs of nylon or Kevlar rope sling

Quenching and Partitioning Process Development to Replace Hot Stamping of High Strength Automotive Steel

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

De Moor, Emmanuel

The present project investigated Quenching and Partitioning (Q&P) to process cold rolled steels to develop high strength sheet steels that exhibit superior ductility compared to available grades with the intent to allow forming of high strength parts at room temperature to provide an alternative to hot stamping of parts. Hot stamping of boron alloyed steel is the current technology to manufacture thinner gauge sections in automotive structures to guarantee anti-intrusion during collisions whilst improving fuel efficiency by decreasing vehicle weight. Hot stamping involves reheating steel to 900 °C or higher followed by deformation and quenching in the die to producemore » ultra-high strength materials. Hot stamping requires significant energy to reheat the steel and is less productive than traditional room temperature stamping operations. Stamping at elevated temperature was developed due to the lack of available steels with strength levels of interest possessing sufficient ductility enabling traditional room temperature forming. This process is seeing growing demand within the automotive industry and, given the reheating step in this operation, increased energy consumption during part manufacturing results. The present research program focused on the development of steel grades via Q&P processing that exhibit high strength and formability enabling room temperature forming to replace hot stamping. The main project objective consisted of developing sheet steels exhibiting minimum ultimate tensile strength levels of 1200 MPa in combination with minimum tensile elongation levels of 15 pct using Q&P processing through judicious alloy design and heat treating parameter definition. In addition, detailed microstructural characterization and study of properties, processing and microstructure interrelationships were pursued to develop strategies to further enhance tensile properties. In order to accomplish these objectives, alloy design was conducted towards achieving the target properties. Twelve alloys were designed and laboratory produced involving melting, alloying, casting, hot rolling, and cold rolling to obtain sheet steels of approximately 1 mm thickness. Q&P processing of the samples was then conducted. Target properties were achieved and substantially exceeded demonstrating success in the developed and employed alloy design approaches. The best combinations of tensile properties were found at approximately 1550 MPa with a total elongation in excess of 20 pct clearly showing the potential for replacement of hot stamping to produce advanced high strength steels.« less

Movement compatibility for frontal controls with displays located in four cardinal orientations.

PubMed

Chan, Alan H S; Hoffmann, Errol R

2010-12-01

Strength and reversibility of direction-of-motion stereotypes and response times are presented for different configurations of horizontal, vertical and rotary controls with horizontal, vertical and circular displays. Measures of the strength and reversibility of stereotypes were used to analyse the effects of direction of turn instruction (clockwise/anticlockwise; up/down; left/right), display orientation (North; East; South; West) and hand side (left/right) on movement compatibility. A number of acceptable display/control arrangements were identified for displays in each of the North, East, South and West orientations relative to the operator. For the horizontally moving control, the Worringham and Beringer principle was found to identify display/control arrangements having both high stereotype strength and high reversibility. Vertically moving controls are excellent with vertical displays but poor with horizontal and circular displays. Rotary controls have high stereotype strength and reversibility with both horizontal and circular displays (with the indicator at the 12 o'clock position). STATEMENT OF RELEVANCE: Design of display/control arrangements requires a strong relationship between operator's expectancies and the response of a device to control inputs. The present research fills in gaps for stereotypes where data are not available, in particular where the operator is not seated facing a display directly to the front.

Formability and mechanical properties of porous titanium produced by a moldless process.

PubMed

Naito, Yoshihito; Bae, Jiyoung; Tomotake, Yoritoki; Hamada, Kenichi; Asaoka, Kenzo; Ichikawa, Tetsuo

2013-08-01

Tailor-made porous titanium implants show great promise in both orthopedic and dental applications. However, traditional powder metallurgical processes require a high-cost mold, making them economically unviable for producing unique devices. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering. The formability of the mixture, the dimensional changes after sintering, and the physical and mechanical properties of the sintered porous titanium were evaluated. A 90:10 wt % mixture of Ti powder and wax binder was created manually at 70°C. After debindering, the specimen was sintered in Ar at 1100°C without any mold for 1, 5, and 10 h. The shrinkage, porosity, absorption ratio, bending and compressive strength, and elastic modulus were measured. The bending strength (135-356 MPa), compression strength (178-1226 MPa), and elastic modulus (24-54 GPa) increased with sintering time; the shrinkage also increased, whereas the porosity (from 37.1 to 29.7%) and absorption ratio decreased. The high formability of the binder/metal powder mixture presents a clear advantage for fabricating tailor-made bone and hard tissue substitution units. Moreover, the sintered compacts showed high strength and an elastic modulus comparable to that of cortical bone. Copyright © 2013 Wiley Periodicals, Inc.

Ergonomic assessment of airport shuttle driver tasks using an ergonomic analysis toolset.

PubMed

Çakıt, Erman

2018-06-01

This study aimed to (a) evaluate strength requirements and lower back stresses during lifting and baggage handling tasks with the 3D Static Strength Prediction Program (3DSSPP) and (b) provide additional analyses using rapid entire body assessment (REBA) and the NASA task load index (TLX) to assess the risks associated with the tasks. Four healthy female shuttle drivers of good health aged between 55 and 60 years were observed and interviewed in an effort to determine the tasks required of their occupations. The results indicated that lifting bags and placing them in a shuttle were high risk for injury and possible changes should be further investigated. The study concluded there was a potential for injury associated with baggage storing and retrieval tasks of a shuttle driver.

AHRQ series paper 5: grading the strength of a body of evidence when comparing medical interventions--agency for healthcare research and quality and the effective health-care program.

PubMed

Owens, Douglas K; Lohr, Kathleen N; Atkins, David; Treadwell, Jonathan R; Reston, James T; Bass, Eric B; Chang, Stephanie; Helfand, Mark

2010-05-01

To establish guidance on grading strength of evidence for the Evidence-based Practice Center (EPC) program of the U.S. Agency for Healthcare Research and Quality. Authors reviewed authoritative systems for grading strength of evidence, identified domains and methods that should be considered when grading bodies of evidence in systematic reviews, considered public comments on an earlier draft, and discussed the approach with representatives of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) working group. The EPC approach is conceptually similar to the GRADE system of evidence rating; it requires assessment of four domains: risk of bias, consistency, directness, and precision. Additional domains to be used when appropriate include dose-response association, presence of confounders that would diminish an observed effect, strength of association, and publication bias. Strength of evidence receives a single grade: high, moderate, low, or insufficient. We give definitions, examples, mechanisms for scoring domains, and an approach for assigning strength of evidence. EPCs should grade strength of evidence separately for each major outcome and, for comparative effectiveness reviews, all major comparisons. We will collaborate with the GRADE group to address ongoing challenges in assessing the strength of evidence.

Improving UV Resistance of High Strength Fibers Used In Large Scientific Balloons

NASA Technical Reports Server (NTRS)

Said, M.; Gupta, A.; Seyam, A.; Mock, G.; Theyson, T.

2004-01-01

For the last three decades, NASA has been involved in the development of giant balloons that are capable of lifting heavy payloads of equipment (such as large telescopes and scientific instruments) to the upper atmosphere. While the use of such balloons has led to scientific discoveries, the demand for competitive science payloads and observational programs continues to rise. The NASA Balloon Program Office has entered a new phase of research to develop an Ultra Long Duration Balloon (ULDB) that will lift payloads of up to 3,600 kg to altitudes of up to 40 km. The flight duration is targeted to ranges between 30 to 100 days. Attaining these target durations requires the development of a super-pressure balloon design. The use of textile structures have already been established in these missions in the form of high strength tendons essential for the super pressure pumpkin design. Unfortunately, high strength fibers lose significant strength upon exposure to Ultra Violet (UV) radiation. Such UV degradation poses a serious challenge for the development of the ULDB. To improve the mission performance of the ULDB, new methods for protecting the tendons from the environmental effects need to be developed. NASA and NC State University College of Textiles are undertaking a research program to address these issues. Four tracks have been identified to prepare finishes that are believed to enhance the resistance of high strength fibers to UV. These tracks are: (a) self-polymerizing, (b) diffusion application, (c) polymer-filled with 30-40% UV absorber, and (d) combination of dyeing plus surface application. Four high performance fibers have been selected for this research investigation. These are Vectran (trademark), Spectra (trademark), Kevlar (trademark) and, PBO (Zylon (trademark)). This work will address the current progress of evaluating the performance of the UV finishes. This will be accomplished by comparing the tensile properties (strength, breaking elongation, modulus, etc) of untreated, unexposed to UV fibers; untreated exposed to UV fibers; and treated exposed to UV fibers.

Aluminum-Scandium Alloys: Material Characterization, Friction Stir Welding, and Compatibility With Hydrogen Peroxide (MSFC Center Director's Discretionary Fund Final Report, Proj. No. 04-14)

NASA Technical Reports Server (NTRS)

Lee, J. A.; Chen, P. S.

2004-01-01

This Technical Memorandum describes the development of several high-strength aluminum (Al) alloys that are compatible with hydrogen peroxide (H2O2) propellant for NASA Hypersonic-X (Hyper-X) vehicles fuel tanks and structures. The yield strengths for some of these Al-magnesium-based alloys are more than 3 times stronger than the conventional 5254-H112 Al alloy, while maintaining excellent H2O2 compatibility similar to class 1 5254 alloy. The alloy development strategy is to add scandium, zirconium, and other transitional metals with unique electrochemical properties, which will not act as catalysts, to decompose the highly concentrated 90 percent H2O2. Test coupons are machined from sheet metals for H2O2 long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloys using friction stir welding has also been explored. The new high-strength alloys could represent an enabling material technology for Hyper-X vehicles, where flight weight reduction is a critical requirement.

A self-sustaining high-strength wastewater treatment system using solar-bio-hybrid power generation.

PubMed

Bustamante, Mauricio; Liao, Wei

2017-06-01

This study focuses on system analysis of a self-sustaining high-strength wastewater treatment concept combining solar technologies, anaerobic digestion, and aerobic treatment to reclaim water. A solar bio-hybrid power generation unit was adopted to power the wastewater treatment. Concentrated solar power (CSP) and photovoltaics (PV) were combined with biogas energy from anaerobic digestion. Biogas is also used to store the extra energy generated by the hybrid power unit and ensure stable and continuous wastewater treatment. It was determined from the energy balance analysis that the PV-bio hybrid power unit is the preferred energy unit to realize the self-sustaining high-strength wastewater treatment. With short-term solar energy storage, the PV-bio-hybrid power unit in Phoenix, AZ requires solar collection area (4032m 2 ) and biogas storage (35m 3 ), while the same unit in Lansing, MI needs bigger solar collection area and biogas storage (5821m 2 and 105m 3 , respectively) due to the cold climate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Progress with High-Field Superconducting Magnets for High-Energy Colliders

NASA Astrophysics Data System (ADS)

Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

2015-10-01

One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ˜10 T at 1.9 K. Fields above 10 T became possible with the use of Nb3Sn superconductors. Nb3Sn accelerator magnets can provide operating fields up to ˜15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. This review discusses the status and main results of Nb3Sn accelerator magnet research and development and work toward 20-T magnets.

Progress with high-field superconducting magnets for high-energy colliders

DOE PAGES

Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

2015-10-01

One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ~10 T at 1.9 K. Fields above 10 T became possible with the use of Nbmore » $$_3$$Sn superconductors. Nb$$_3$$Sn accelerator magnets can provide operating fields up to ~15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. Furthermore, this review discusses the status and main results of Nb$$_3$$Sn accelerator magnet research and development and work toward 20-T magnets.« less

Direct ink writing of highly porous and strong glass scaffolds for load-bearing bone defects repair and regeneration.

PubMed

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P

2011-10-01

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires the development of porous, high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inks were optimized for the printing of features as fine as 30 μm and of three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds showed a compressive strength (136 ± 22 MPa) comparable with that of human cortical bone (100-150 MPa), while the porosity (60%) was in the range of that of trabecular bone (50-90%). The strength is ~100-times that of polymer scaffolds and 4-5-times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in SBF, the value (77 MPa) is still far above that of trabecular bone after 3 weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. Published by Elsevier Ltd.

Direct Ink Writing of Highly Porous and Strong Glass Scaffolds for Load-bearing Bone Defects Repair and Regeneration

PubMed Central

Fu, Qiang; Saiz, Eduardo; Tomsia, Antoni P.

2011-01-01

The quest for synthetic materials to repair load-bearing bone lost because of trauma, cancer, or congenital bone defects requires development of porous and high-performance scaffolds with exceptional mechanical strength. However, the low mechanical strength of porous bioactive ceramic and glass scaffolds, compared with that of human cortical bone, has limited their use for these applications. In the present work, bioactive 6P53B glass scaffolds with superior mechanical strength were fabricated using a direct ink writing technique. The rheological properties of Pluronic® F-127 (referred to hereafter simply as F-127) hydrogel-based inkswere optimized for the printing of features as fine as 30 μm and of the three-dimensional scaffolds. The mechanical strength and in vitro degradation of the scaffolds were assessed in a simulated body fluid (SBF). The sintered glass scaffolds show a compressive strength (136 ± 22 MPa) comparable to that of human cortical bone (100-150 MPa), while the porosity (60%) is in the range of that of trabecular bone (50-90%).The strength is ~100 times that of polymer scaffolds and 4–5 times that of ceramic and glass scaffolds with comparable porosities. Despite the strength decrease resulting from weight loss during immersion in an SBF, the value (77 MPa) is still far above that of trabecular bone after three weeks. The ability to create both porous and strong structures opens a new avenue for fabricating scaffolds for load-bearing bone defect repair and regeneration. PMID:21745606

How long does it take to become fit?

PubMed Central

Pearn, J

1980-01-01

To become fit an individual must generate optimal muscle strength and must develop cardiopulmonary reserve, or stamina. Physical fitness programmes require motivation, a graded series of appropriately designed exercises, and scientific surveillance. Motivation and efficiency in fitness programmes depends on early positive feedback to participants, confirming that stamina and strength are developing. A practical field experiment was performed to determine the minimum time that healthy young adults require to reach an initial plateau in objective measures of fitness. Fifty male university undergraduates were studied during an annual volunteer military training camp. Thirty had volunteered to take part in the fitness programme; the remaining 20 had initially rejected the offer but underwent the programme as part of their military training and acted as unmotivated controls. All the subjects became fit within 14 days of starting training, with objective improvement in both absolute strength and pulse recovery times. Non-motivated individuals, training with motivated individuals for 20 minutes each day, can therefore achieve levels of fitness indistinguishable from those of healthy highly motivated subjects. Fitness programmes must be carefully supervised, however, with medical examinations for those about to undergo vigorous exercise. PMID:7437862

Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

NASA Astrophysics Data System (ADS)

de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

2018-01-01

The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

The young skater.

PubMed

Smith, A D

2000-10-01

Figure skating is one of the best lifetime sports. Participants may skate alone or with a group, recreationally or competitively, at all ages and at all skill levels. As a sport that improves physical fitness, skating builds strength, flexibility, and cardiopulmonary endurance. As a weight-bearing or high-impact activity, it is one of the best sports for increasing bone mineral density and perhaps for preventing osteoporosis. At least half of all competitive figure skating injuries appear preventable. Boots should be as flexible as the skater can control and should be carefully fitted. Normal flexibility of lower extremity muscles, especially in the growing athlete, markedly decreases the incidence of overuse symptoms of the knee. Core body strength is critical for controlling high-impact jump landings and decreasing injuries to the spine, pelvis, and hip girdle. Adequate shoulder strength is required for pair skaters and ice dancers. A well-designed off-ice training program decreases injury incidence and enhances performance. Assisting these dedicated athletes is truly rewarding as they train and compete at their highest potential, with passion for their sport.

Ego depletion and attention regulation under pressure: is a temporary loss of self-control strength indeed related to impaired attention regulation?

PubMed

Englert, Chris; Zwemmer, Kris; Bertrams, Alex; Oudejans, Raôul R

2015-04-01

In the current study we investigated whether ego depletion negatively affects attention regulation under pressure in sports by assessing participants' dart throwing performance and accompanying gaze behavior. According to the strength model of self-control, the most important aspect of self-control is attention regulation. Because higher levels of state anxiety are associated with impaired attention regulation, we chose a mixed design with ego depletion (yes vs. no) as between-subjects and anxiety level (high vs. low) as within-subjects factor. Participants performed a perceptual-motor task requiring selective attention, namely, dart throwing. In line with our expectations, depleted participants in the high-anxiety condition performed worse and displayed a shorter final fixation on bull's eye, demonstrating that when one's self-control strength is depleted, attention regulation under pressure cannot be maintained. This is the first study that directly supports the general assumption that ego depletion is a major factor in influencing attention regulation under pressure.

Compressive Strength and Water Absorption of Pervious Concrete that Using the Fragments of Ceramics and Roof Tiles

NASA Astrophysics Data System (ADS)

Prahara, E.; Meilani

2014-03-01

Pervious concrete was introduced in America in 2003, popularized by Dan Brown and used as a rigid pavement in the open parking lot. Rigid pavement using pervious concrete can absorb water in the surface to go straight through the concrete to the ground below.This water flow is one of the benefit of using the pervious concrete. Using of wastes such as broken roof and ceramics tiles are not commonly used in Indonesia. Utilization these kind of wastes is predicted lower the compressive strength of pervious concrete as they are used as a substitute for coarse aggregate.In this research, pervious concrete is made using a mixture of the fragment of ceramics and roof tiles.This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve. The water cement ratio is 0.3 and to assist the mixing process, the addition of addictive in pervious concrete is used.The size of coarse aggregate used in the mixture affects the strength of pervious concrete. The larger the size of aggregate, the obtained compressive strength becomes smaller. It also affects the density of pervious concrete. The using of mixture of ceramics and roof tiles only reduce 2 MPa of pervious concrete compressive strength so this mixture can be used as a substitute for coarse aggregate with a maximum portion of 30 %. The high porosity of the specimens causes the reduction of pervious concrete density that affect the compressive strength. This high level of porosity can be seen from the high level of water absorption that exceed the required limit of water infiltration.

User's Guide to Computing High School Graduation Rates. Volume 1. Technical Report: Review of Current and Proposed Graduation Indicators. NCES 2006-604

ERIC Educational Resources Information Center

Seastrom, Marilyn M.; Chapman, Chris; Stillwell, Robert; McGrath, Daniel; Peltola, Pia; Dinkes, Rachel; Xu, Zeyu

2006-01-01

The first volume of this report examines the existing measures of high school completion and the newly proposed proxy measures. This includes a description of the computational formulas, the data required for each indicator, the assumptions underlying each formula, the strengths and weaknesses of each indicator relative to a true cohort on-time…

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

Robert Radtke

The manufacture of thermally stable diamond (TSP) cutters for drill bits used in petroleum drilling requires the brazing of two dissimilar materials--TSP diamond and tungsten carbide. The ENDURUS{trademark} thermally stable diamond cutter developed by Technology International, Inc. exhibits (1) high attachment (shear) strength, exceeding 345 MPa (50,000 psi), (2) TSP diamond impact strength increased by 36%, (3) prevents TSP fracture when drilling hard rock, and (4) maintains a sharp edge when drilling hard and abrasive rock. A novel microwave brazing (MWB) method for joining dissimilar materials has been developed. A conventional braze filler metal is combined with microwave heating whichmore » minimizes thermal residual stress between materials with dissimilar coefficients of thermal expansion. The process results in preferential heating of the lower thermal expansion diamond material, thus providing the ability to match the thermal expansion of the dissimilar material pair. Methods for brazing with both conventional and exothermic braze filler metals have been developed. Finite element modeling (FEM) assisted in the fabrication of TSP cutters controllable thermal residual stress and high shear attachment strength. Further, a unique cutter design for absorbing shock, the densification of otherwise porous TSP diamond for increased mechanical strength, and diamond ion implantation for increased diamond fracture resistance resulted in successful drill bit tests.« less

Exercise-Based Fall Prevention in the Elderly: What About Agility?

PubMed

Donath, Lars; van Dieën, Jaap; Faude, Oliver

2016-02-01

Annually, one in three seniors aged over 65 years fall. Balance and strength training can reduce neuromuscular fall risk factors and fall rates. Besides conventional balance and strength training, explosive or high-velocity strength training, eccentric exercises, perturbation-based balance training, trunk strength, and trunk control have also been emphasized. In contrast, aerobic exercise has to date not been included in fall-prevention studies. However, well-developed endurance capacity might attenuate fatigue-induced declines in postural control in sports-related or general activities of daily living. Physical performance indices, such as balance, strength, and endurance, are generally addressed independently in exercise guidelines. This approach seems time consuming and may impede integrative training of sensorimotor, neuromuscular, and cardiocirculatory functions required to deal with balance-threatening situations in the elderly. An agility-based conceptual training framework comprising perception and decision making (e.g., visual scanning, pattern recognition, anticipation) and changes of direction (e.g., sudden starts, stops and turns; reactive control; concentric and eccentric contractions) might enable an integrative neuromuscular, cardiocirculatory, and cognitive training. The present paper aims to provide a scientific sketch of how to build such an integrated modular training approach, allowing adaptation of intensity, complexity, and cognitive challenge of the agility tasks to the participant's capacity. Subsequent research should address the (1) link between agility and fall risk factors as well as fall rates, (2) benefit-risk ratios of the proposed approach, (3) psychosocial aspects of agility training (e.g., motivation), and (4) logistical requirements (e.g., equipment needed).

Characterization of welded HP 9-4-30 steel for the advanced solid rocket motor

NASA Technical Reports Server (NTRS)

Watt, George William

1990-01-01

Solid rocket motor case materials must be high-strength, high-toughness, weldable alloys. The Advanced Solid Rocket Motor (ASRM) cases currently being developed will be made from a 9Ni-4Co quench and temper steel called HP 9-4-30. These ultra high-strength steels must be carefully processed to give a very clean material and a fine grained microstructure, which insures excellent ductility and toughness. The HP 9-4-30 steels are vacuum arc remelted and carbon deoxidized to give the cleanliness required. The ASRM case material will be formed into rings and then welded together to form the case segments. Welding is the desired joining technique because it results in a lower weight than other joining techniques. The mechanical and corrosion properties of the weld region material were fully studied.

Assessment of brittleness and empirical correlations between physical and mechanical parameters of the Asmari limestone in Khersan 2 dam site, in southwest of Iran

NASA Astrophysics Data System (ADS)

Lashkaripour, Gholam Reza; Rastegarnia, Ahmad; Ghafoori, Mohammad

2018-02-01

The determination of brittleness and geomechanical parameters, especially uniaxial compressive strength (UCS) and Young's modulus (ES) of rocks are needed for the design of different rock engineering applications. Evaluation of these parameters are time-consuming processes, tedious, expensive and require well-prepared rock cores. Therefore, compressional wave velocity (Vp) and index parameters such as point load index and porosity are often used to predict the properties of rocks. In this paper, brittleness and other properties, physical and mechanical in type, of 56 Asmari limestones in dry and saturated conditions were analyzed. The rock samples were collected from Khersan 2 dam site. This dam with the height of 240 m is being constructed and located in the Zagros Mountain, in the southwest of Iran. The bedrock and abutments of the dam site consist of Asemari and Gachsaran Formations. In this paper, a practical relation for predicting brittleness and some relations between mechanical and index parameters of the Asmari limestone were established. The presented equation for predicting brittleness based on UCS, Brazilian tensile strength and Vp had high accuracy. Moreover, results showed that the brittleness estimation based on B3 concept (the ratio of multiply compressive strength in tensile strength divided 2) had more accuracy as compared to the B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength) and B1 (the ratio of compressive strength to tensile strength) concepts.

Hydrogen suppression of 'ductile' processes

NASA Technical Reports Server (NTRS)

Sisson, R. D., Jr.; Wilson, J. H.; Adler, T. A.; Mcnitt, R. P.; Louthan, M. R., Jr.

1980-01-01

Experimental results are reported for torsional fatigue specimens of high-strength steel 4370 and tensile bars of mild steel A-106 which present evidence of a hydrogen-induced strain-aided hardening effect. These results are consistent with the postulate that hydrogen suppresses ductile processes required for crack initiation at large plastic strains.

Through the Looking Glass: One School's Reflection on Differentiation

ERIC Educational Resources Information Center

Tieso, Carol

2004-01-01

Teachers must deal with a diversity of students' abilities, strengths, and interests in their classrooms while at the same time covering the material, prepping students for standardized tests, and preparing themselves to be "highly qualified." Legislation requiring services for gifted and talented students and the paucity of quality programs for…

Braided Composites for Aerospace Applications. (Latest citations from the Aerospace Database)

NASA Technical Reports Server (NTRS)

1996-01-01

The bibliography contains citations concerning the design, fabrication, and testing of structural composites formed by braiding machines. Topics include computer aided design and associated computer aided manufacture of braided tubular and flat forms. Applications include aircraft and spacecraft structures, where high shear strength and stiffness are required.

Asteroid collisions, craters, regoliths, and lifetimes

NASA Technical Reports Server (NTRS)

Chapman, C. R.

1978-01-01

Laboratory experiments and computer modeling are used to predict the development of regoliths on all asteroids more than a few tens of kilometers in diameter, allowing for a wide range in the intrinsic strength of asteroidal surface materials. The high frequency of interasteroid collisions requires nearly all asteroids to be fragments of precursors.

Estimating the strength of bone using linear response

NASA Astrophysics Data System (ADS)

Gunaratne, Gemunu H.

2002-12-01

Accurate diagnostic tools are required for effective management of osteoporosis; one method to identify additional diagnostics is to search for observable consequences of bone loss. An analysis of a model system is used to show that weakening of a bone is accompanied by a reduction of the fraction of the bone that participates in load transmission. On the basis of this observation, it is argued that the ratio Γ of linear responses of a network to dc and high-frequency ac driving can be used as a surrogate for their strength. Protocols needed to obtain Γ for bone samples are discussed.

Development and characterization of fatigue resistant Aramid reinforced aluminium laminates (ARALL) for fatigue Critical aircraft components

NASA Astrophysics Data System (ADS)

Qaiser, M. H.; Umar, S.; Nauman, S.

2014-06-01

The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced ALuminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft.

47 CFR 2.1053 - Measurements required: Field strength of spurious radiation.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... For equipment operating on frequencies below 890 MHz, an open field test is normally required, with... either impractical or impossible to make open field measurements (e.g. a broadcast transmitter installed... 47 Telecommunication 1 2010-10-01 2010-10-01 false Measurements required: Field strength of...

Materials and structures for hypersonic vehicles

NASA Technical Reports Server (NTRS)

Tenney, Darrel R.; Lisagor, W. Barry; Dixon, Sidney C.

1988-01-01

Hypersonic vehicles are envisioned to require, in addition to carbon-carbon and ceramic-matrix composities for leading edges heated to above 2000 F, such 600 to 1800 F operating temperature materials as advanced Ti alloys, nickel aluminides, and metal-matrix composited; These possess the necessary low density and high strength and stiffness. The primary design drivers are maximum vehicle heating rate, total heat load, flight envelope, propulsion system type, mission life requirements and liquid hydrogen containment systems. Attention is presently given to aspects of these materials and structures requiring more intensive development.

Fracture control for the Oman India Pipeline

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

Bruno, T.V.

1996-12-31

This paper describes the evaluation of the resistance to fracture initiation and propagation for the high-strength, heavy-wall pipe required for the Oman India Pipeline (OIP). It discusses the unique aspects of this pipeline and their influence on fracture control, reviews conventional fracture control design methods, their limitations with regard to the pipe in question, the extent to which they can be utilized for this project, and other approaches being explored. Test pipe of the size and grade required for the OIP show fracture toughness well in excess of the minimum requirements.

An investigation into the immediate effects of pelvic taping on hamstring eccentric force in an elite male sprinter - A case report.

PubMed

Macdonald, Ben

2017-11-01

Hamstring Injuries commonly cause missed training and competition time in elite sports. Injury surveillance studies have demonstrated high injury and re-injury rates, which have not improved across sports despite screening and prevention programmes being commonplace. The most commonly suggested intervention for hamstring prevention and rehabilitation is eccentric strength assessment and training. This case study describes the management of an elite sprinter with a history of hamstring injury. A multi-variate screening process based around lumbar-pelvic dysfunction and hamstring strength assessment using the Nordbord is employed. The effect of external pelvic compression using a taping technique, on eccentric hamstring strength is evaluated. A persistent eccentric strength asymmetry of 17% was recorded as well as lumbar-pelvic control deficits. Pelvic taping appears to improve load transfer capability across the pelvis, resulting in correction of eccentric strength asymmetry. Screening strategies and interventions to prevent hamstring injury have failed to consistently improve injury rates across various sports. In this case study external pelvic compression resulted in normalising eccentric strength deficits assessed using the Nordbord. The inclusion of lumbar-pelvic motor control assessment, in relation to hamstring strength and function, as part of a multi-variate screening strategy requires further research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elucidation of the genetic basis of variation for stem strength characteristics in bread wheat by Associative Transcriptomics.

PubMed

Miller, Charlotte N; Harper, Andrea L; Trick, Martin; Werner, Peter; Waldron, Keith; Bancroft, Ian

2016-07-16

The current approach to reducing the tendency for wheat grown under high fertilizer conditions to collapse (lodge) under the weight of its grain is based on reducing stem height via the introduction of Rht genes. However, these reduce the yield of straw (itself an important commodity) and introduce other undesirable characteristics. Identification of alternative height-control loci is therefore of key interest. In addition, the improvement of stem mechanical strength provides a further way through which lodging can be reduced. To investigate the prospects for genetic alternatives to Rht, we assessed variation for plant height and stem strength properties in a training genetic diversity panel of 100 wheat accessions fixed for Rht. Using mRNAseq data derived from RNA purified from leaves, functional genotypes were developed for the panel comprising 42,066 Single Nucleotide Polymorphism (SNP) markers and 94,060 Gene Expression Markers (GEMs). In the first application in wheat of the recently-developed method of Associative Transcriptomics, we identified associations between trait variation and both SNPs and GEMs. Analysis of marker-trait associations revealed candidates for the causative genes underlying the trait variation, implicating xylan acetylation and the COP9 signalosome as contributing to stem strength and auxin in the control of the observed variation for plant height. Predictive capabilities of key markers for stem strength were validated using a test genetic diversity panel of 30 further wheat accessions. This work illustrates the power of Associative Transcriptomics for the exploration of complex traits of high agronomic importance in wheat. The careful selection of genotypes included in the analysis, allowed for high resolution mapping of novel trait-controlling loci in this staple crop. The use of Gene Expression markers coupled with the more traditional sequence-based markers, provides the power required to understand the biological context of the marker-trait associations observed. This not only adds to the wealth of knowledge that we strive to accumulate regarding gene function and plant adaptation, but also provides breeders with the information required to make more informed decisions regarding the potential consequences of incorporating the use of particular markers into future breeding programmes.

Grading the quality of evidence and the strength of recommendations in clinical dentistry: a critical review of 2 prominent approaches.

PubMed

Faggion, Clovis Mariano

2010-06-01

The objective of this article was to critically review 2 prominent approaches used to grade the quality of evidence and the strength of recommendations. Every year much information becomes available as a result of publication of scientific papers, and clinicians should be able to assess current evidence so they, along with their patients, can make the most appropriate clinical decisions. This is particularly important when there is little or no high-quality evidence available about the subject of interest. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) and the Strength of Recommendation Taxonomy (SORT) were evaluated. Strengths and weaknesses of these 2 systems are discussed, mainly on the basis of their relevance to clinical dentistry. The conclusion was that use of a system for grading the quality of evidence and the strength of recommendations is urgently required because of the great heterogeneity of the quality and type of evidence relating to many dental procedures. Use of such a system will enable clinicians and their patients to make more informed decisions.

Repairability of CAD/CAM high-density PMMA- and composite-based polymers.

PubMed

Wiegand, Annette; Stucki, Lukas; Hoffmann, Robin; Attin, Thomas; Stawarczyk, Bogna

2015-11-01

The study aimed to analyse the shear bond strength of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA)- and composite-based polymer materials repaired with a conventional methacrylate-based composite after different surface pretreatments. Each 48 specimens was prepared from six different CAD/CAM polymer materials (Ambarino high-class, artBloc Temp, CAD-Temp, Lava Ultimate, Telio CAD, Everest C-Temp) and a conventional dimethacrylate-based composite (Filtek Supreme XTE, control) and aged by thermal cycling (5000 cycles, 5-55 °C). The surfaces were left untreated or were pretreated by mechanical roughening, aluminium oxide air abrasion or silica coating/silanization (each subgroup n = 12). The surfaces were further conditioned with an etch&rinse adhesive (OptiBond FL) before the repair composite (Filtek Supreme XTE) was adhered to the surface. After further thermal cycling, shear bond strength was tested, and failure modes were assessed. Shear bond strength was statistically analysed by two- and one-way ANOVAs and Weibull statistics, failure mode by chi(2) test (p ≤ 0.05). Shear bond strength was highest for silica coating/silanization > aluminium oxide air abrasion = mechanical roughening > no surface pretreatment. Independently of the repair pretreatment, highest bond strength values were observed in the control group and for the composite-based Everest C-Temp and Ambarino high-class, while PMMA-based materials (artBloc Temp, CAD-Temp and Telio CAD) presented significantly lowest values. For all materials, repair without any surface pretreatment resulted in adhesive failures only, which mostly were reduced when surface pretreatment was performed. Repair of CAD/CAM high-density polymers requires surface pretreatment prior to adhesive and composite application. However, four out of six of the tested CAD/CAM materials did not achieve the repair bond strength of a conventional dimethacrylate-based composite. Repair of PMMA- and composite-based polymers can be achieved by surface pretreatment followed by application of an adhesive and a conventional methacrylate-based composite.

Conceptual design of ACB-CP for ITER cryogenic system

NASA Astrophysics Data System (ADS)

Jiang, Yongcheng; Xiong, Lianyou; Peng, Nan; Tang, Jiancheng; Liu, Liqiang; Zhang, Liang

2012-06-01

ACB-CP (Auxiliary Cold Box for Cryopumps) is used to supply the cryopumps system with necessary cryogen in ITER (International Thermonuclear Experimental Reactor) cryogenic distribution system. The conceptual design of ACB-CP contains thermo-hydraulic analysis, 3D structure design and strength checking. Through the thermohydraulic analysis, the main specifications of process valves, pressure safety valves, pipes, heat exchangers can be decided. During the 3D structure design process, vacuum requirement, adiabatic requirement, assembly constraints and maintenance requirement have been considered to arrange the pipes, valves and other components. The strength checking has been performed to crosscheck if the 3D design meets the strength requirements for the ACB-CP.

Indoor positioning algorithm combined with angular vibration compensation and the trust region technique based on received signal strength-visible light communication

NASA Astrophysics Data System (ADS)

Wang, Jin; Li, Haoxu; Zhang, Xiaofeng; Wu, Rangzhong

2017-05-01

Indoor positioning using visible light communication has become a topic of intensive research in recent years. Because the normal of the receiver always deviates from that of the transmitter in application, the positioning systems which require that the normal of the receiver be aligned with that of the transmitter have large positioning errors. Some algorithms take the angular vibrations into account; nevertheless, these positioning algorithms cannot meet the requirement of high accuracy or low complexity. A visible light positioning algorithm combined with angular vibration compensation is proposed. The angle information from the accelerometer or other angle acquisition devices is used to calculate the angle of incidence even when the receiver is not horizontal. Meanwhile, a received signal strength technique with high accuracy is employed to determine the location. Moreover, an eight-light-emitting-diode (LED) system model is provided to improve the accuracy. The simulation results show that the proposed system can achieve a low positioning error with low complexity, and the eight-LED system exhibits improved performance. Furthermore, trust region-based positioning is proposed to determine three-dimensional locations and achieves high accuracy in both the horizontal and the vertical components.

Investigation of Self Consolidating Concrete Containing High Volume of Supplementary Cementitious Materials and Recycled Asphalt Pavement Aggregates

NASA Astrophysics Data System (ADS)

Patibandla, Varun chowdary

The use of sustainable technologies such as supplementary cementitiuous materials (SCMs), and/or recycled materials is expected to positively affect the performance of concrete mixtures. However, it is important to study and qualify such mixtures and check if the required specifications of their intended application are met before they can be implemented in practice. This study presents the results of a laboratory investigation of Self Consolidating concrete (SCC) containing sustainable technologies. A total of twelve concrete mixtures were prepared with various combinations of fly ash, slag, and recycled asphalt pavement (RAP). The mixtures were divided into three groups with constant water to cementitiuous materials ratio of 0.37, and based on the RAP content; 0, 25, and 50% of coarse aggregate replaced by RAP. All mixtures were prepared to achieve a target slump flow equal to or higher than 500 mm (24in). A control mixture for each group was prepared with 100% Portland cement whereas all other mixtures were designed to have up to 70% of portland cement replaced by a combination of supplementary cementitiuous materials (SCMs) such as class C fly ash and granulated blast furnace slag. The properties of fresh concrete investigated in this study include flowability, deformability; filling capacity, and resistance to segregation. In addition, the compressive strength at 3, 14, and 28 days, the tensile strength, and the unrestrained shrinkage up to 80 days was also investigated. As expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Analysis of the experimental data indicated that inclusion of RAP not only reduces the ultimate strength, but it also affected the compressive strength development rate. Moreover, several mixes satisfied compressive strength requirements for pavements and bridges; those mixes included relatively high percentages of SCMs and RAP. Based on the results obtained in this study, it is not recommended to replace the coarse aggregate in SCC by more than 25% RAP.

Effect of core geometry and size on concrete compressive strength.

DOT National Transportation Integrated Search

2016-07-01

To evaluate the in-place concrete strength for acceptance for a structural member with : potentially substandard strength, the compressive strength of cores may be required for : assessment. Depending on the geometry and size of the core specimen, th...

A comparative study of the mechanical performance of Glass and Glass/Carbon hybrid polymer composites at different temperature environments

NASA Astrophysics Data System (ADS)

Shukla, M. J.; Kumar, D. S.; Mahato, K. K.; Rathore, D. K.; Prusty, R. K.; Ray, B. C.

2015-02-01

Glass Fiber Reinforced Polymer (GFRP) composites have been widely accepted as high strength, low weight structural material as compared to their metallic counterparts. Some specific advanced high performance applications such as aerospace components still require superior specific strength and specific modulus. Carbon Fiber Reinforced Polymer (CFRP) composites exhibit superior specific strength and modulus but have a lower failure strain and high cost. Hence, the combination of both glass and carbon fiber in polymer composite may yield optimized mechanical properties. Further the in-service environment has a significant role on the mechanical performance of this class of materials. Present study aims to investigate the mechanical property of GFRP and Glass/Carbon (G/C hybrid) composites at room temperature, in-situ and ex-situ temperature conditions. In-situ testing at +70°C and +100°C results in significant loss in inter-laminar shear strength (ILSS) for both the composites as compared to room temperature. The ILSS was nearly equal for both the composite systems tested in-situ at +100°C and effect of fiber hybridisation was completely diminished there. At low temperature ex-situ conditioning significant reduction in ILSS was observed for both the systems. Further at -60°C G/C hybrid exhibited 32.4 % higher ILSS than GFRP. Hence this makes G/C hybrid a better choice of material in low temperature environmental applications.

Low-Carbon Metallurgical Concepts for Seamless Octg Pipe

NASA Astrophysics Data System (ADS)

Mohrbacher, Hardy

Seamless pipes are available with wall gages of up to 100 mm and outer diameters up to around 700 mm. Such pipes are typically used for oil country tubular goods as well as for structural applications. Due to market requirements the demand for high strength grade seamless pipes is increasing. Many applications need high toughness in addition to high strength. The different rolling processes applied in production depend on wall gage and pipe diameter. The continuous mandrel mill process is used to produce smaller gages and diameters; plug mill processing covers medium gages and diameters; Pilger mill processing allows producing larger diameters and heavy wall gage. In all these processes only a limited degree of thermo-mechanical rolling can be achieved. Therefore strengthening and toughening by severe grain refinement employing a conventional niobium-based microalloying concept is not easily achievable. Accordingly, high strength and toughness seamless pipe is typically produced via a quench and tempering process route. This route however is costly and above that often constitutes a capacity bottleneck in the mill. Innovative low-carbon alloy concepts however do allow producing strength up to grade X70 at very high toughness directly off the rolling plant, i.e., without quench and tempering treatment. Due to the low carbon content also welding is much facilitated. The paper reveals the metallurgical principles, which are based on appropriate niobium and molybdenum alloying. Additionally the paper demonstrates how heavy gaged seamless pipes up to 70 mm wall thickness can be produced based on a low-carbon Nb-Mo approach using quench and temper treatment.

47 CFR 90.671 - Field strength limits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required to...

47 CFR 90.671 - Field strength limits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Field strength limits. 90.671 Section 90.671... 896-901/935-940 Mhz Band § 90.671 Field strength limits. The predicted or measured field strength at... all bordering MTA licensees agree to a higher field strength. MTA licensees are also required to...

Initial Calibration of the AEDC Impulse Tunnel

DTIC Science & Technology

1996-08-01

material characteristics required are a high yield strength, a low coefficient of expansion, and a high hardness. The calculations in this section were...Qualified users may obtain copies of this report from the Defense Technical Information Center. References to named commercial products in this...report are not to be considered in any sense as an endorsement of the product by the United States Air Force or the Government. This report has been

Development and Property Evaluation of Selected HfO2-Silicon and Rare Earth-Silicon Based Bond Coats and Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

Ceramic environmental barrier coatings (EBC) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiC/SiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si and rare earth Si based EBC bond coat EBC systems for SiC/SiC CMC combustor and turbine airfoil applications are investigated. High temperature properties of the advanced EBC systems, including the strength, fracture toughness, creep and oxidation resistance have been studied and summarized. The advanced NASA EBC systems showed some promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Reinforcements: The key to high performance composite materials

NASA Technical Reports Server (NTRS)

Grisaffe, Salvatore J.

1990-01-01

Better high temperature fibers are the key to high performance, light weight composite materials. However, current U.S. and Japanese fibers still have inadequate high temperature strength, creep resistance, oxidation resistance, modulus, stability, and thermal expansion match with some of the high temperature matrices being considered for future aerospace applications. In response to this clear deficiency, both countries have research and development activities underway. Once successful fibers are identified, their production will need to be taken from laboratory scale to pilot plant scale. In such efforts it can be anticipated that the Japanese decisions will be based on longer term criteria than those applied in the U.S. Since the initial markets will be small, short term financial criteria may adversely minimize the number and strength of U.S. aerospace materials suppliers to well into the 21st century. This situation can only be compounded by the Japanese interests in learning to make commercial products with existing materials so that when the required advanced fibers eventually do arrive, their manufacturing skills will be developed.

14 CFR 31.27 - Strength.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Strength. 31.27 Section 31.27 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.27 Strength. (a) The structure must be able to...

14 CFR 29.305 - Strength and deformation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Strength and deformation. 29.305 Section 29.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements General § 29.305 Strength and...

14 CFR 29.305 - Strength and deformation.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength and deformation. 29.305 Section 29.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements General § 29.305 Strength and...

Evaluation of super-water reducers for highway applications

NASA Astrophysics Data System (ADS)

Whiting, D.

1981-03-01

Super-water reducers were characterized and evaluated as potential candidates for production of low water to cement ratio, high strength concretes for highway construction applications. Admixtures were composed of either naphthalene or melamine sulfonated formaldehyde condensates. A mini-slump procedure was used to assess dosage requirements and behavior of workability with time of cement pastes. Required dosage was found to be a function of tricalcium aluminate content, alkali content, and fineness of the cement. Concretes exhibited high rates of slump loss when super-water reducers were used. The most promising area of application of these products appears to be in production of dense, high cement content concrete using mobile concrete mixer/transporters.

Principles of strengths-based nursing leadership for strengths-based nursing care: a new paradigm for nursing and healthcare for the 21st century.

PubMed

Gottlieb, Laurie N; Gottlieb, Bruce; Shamian, Judith

2012-06-01

The current healthcare system is slowly evolving into a new system built on a vision of health promotion, primary care and community-based home care, with hospitals still being a core pillar of the healthcare system but not its primary service. This transformation requires a new approach to practice, namely, Strengths-Based Nursing Care (SBC). SBC is about mobilizing, capitalizing and developing a person's strengths to promote health and facilitate healing. For nurses to practise SBNC requires strong nursing leadership that creates conditions to enable them to do so. Strengths-Based Nursing Leadership complements and acts in synergy with, SBNC. This paper describes eight principles of Strengths-Based Nursing Leadership to support SBNC.

Application of lap laser welding technology on stainless steel railway vehicles

NASA Astrophysics Data System (ADS)

Wang, Hongxiao; Wang, Chunsheng; He, Guangzhong; Li, Wei; Liu, Liguo

2016-10-01

Stainless steel railway vehicles with so many advantages, such as lightweight, antirust, low cost of maintenance and simple manufacturing process, so the production of high level stainless steel railway vehicles has become the development strategy of European, American and other developed nations. The current stainless steel railway vehicles body and structure are usually assembled by resistance spot welding process. The weak points of this process are the poor surface quality and bad airtight due to the pressure of electrodes. In this study, the partial penetration lap laser welding process was investigated to resolve the problems, by controlling the laser to stop at the second plate in the appropriate penetration. The lap laser welding joint of stainless steel railway vehicle car body with partial penetration has higher strength and surface quality than those of resistance spot welding joint. The biggest problem of lap laser welding technology is to find the balance of the strength and surface quality with different penetrations. The mechanism of overlap laser welding of stainless steel, mechanical tests, microstructure analysis, the optimization of welding parameters, analysis of fatigue performance, the design of laser welding stainless steel railway vehicles structure and the development of non-destructive testing technology were systematically studied before lap laser welding process to be applied in manufacture of railway vehicles. The results of the experiments and study show that high-quality surface state and higher fatigue strength can be achieved by the partial penetration overlap laser welding of the side panel structure, and the structure strength of the car body can be higher than the requirements of En12663, the standard of structural requirements of railway vehicles bodies. Our company has produced the stainless steel subway and high way railway vehicles by using overlap laser welding technology. The application of lap laser welding will be a big change of railway vehicles manufacturing technology.

A feasibility study of high-strength Bi-2223 conductor for high-field solenoids

NASA Astrophysics Data System (ADS)

Godeke, A.; Abraimov, D. V.; Arroyo, E.; Barret, N.; Bird, M. D.; Francis, A.; Jaroszynski, J.; Kurteva, D. V.; Markiewicz, W. D.; Marks, E. L.; Marshall, W. S.; McRae, D. M.; Noyes, P. D.; Pereira, R. C. P.; Viouchkov, Y. L.; Walsh, R. P.; White, J. M.

2017-03-01

We performed a feasibility study on a high-strength Bi{}2-xPb x Sr2Ca2Cu3O{}10-x(Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries. It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress-strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥slant 0.92 % (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions.

A Feasibility Study of High-Strength Bi-2223 Conductor for High-Field Solenoids

PubMed Central

Godeke, A; Abraimov, D V; Arroyo, E; Barret, N; Bird, M D; Francis, A; Jaroszynski, J; Kurteva, D V; Markiewicz, W D; Marks, E L; Marshall, W S; McRae, D M; Noyes, P D; Pereira, R C P; Viouchkov, Y L; Walsh, R P; White, J M

2017-01-01

We performed a feasibility study on a high-strength Bi2−xPbxSr2Ca2Cu3O10−x (Bi-2223) tape conductor for high-field solenoid applications. The investigated conductor, DI-BSCCO Type HT-XX, is a pre-production version of Type HT-NX, which has recently become available from Sumitomo Electric Industries (SEI). It is based on their DI-BSCCO Type H tape, but laminated with a high-strength Ni-alloy. We used stress-strain characterizations, single- and double-bend tests, easy- and hard-way bent coil-turns at various radii, straight and helical samples in up to 31.2 T background field, and small 20-turn coils in up to 17 T background field to systematically determine the electro-mechanical limits in magnet-relevant conditions. In longitudinal tensile tests at 77 K, we found critical stress- and strain-levels of 516 MPa and 0.57%, respectively. In three decidedly different experiments we detected an amplification of the allowable strain with a combination of pure bending and Lorentz loading to ≥ 0.92% (calculated elastically at the outer tape edge). This significant strain level, and the fact that it is multi-filamentary conductor and available in the reacted and insulated state, makes DI-BSCCO HT-NX highly suitable for very high-field solenoids, for which high current densities and therefore high loads are required to retain manageable magnet dimensions. PMID:28360455

Influence of processing factors over concrete strength.

NASA Astrophysics Data System (ADS)

Kara, K. A.; Dolzhenko, A. V.; Zharikov, I. S.

2018-03-01

Construction of facilities of cast in-situ reinforced concrete poses additional requirements to quality of material, peculiarities of the construction process may sometimes lead to appearance of lamination planes and inhomogeneity of concrete, which reduce strength of the material and structure as a whole. Technology compliance while working with cast in-situ concrete has a significant impact onto the concrete strength. Such process factors as concrete curing, vibration and compaction of the concrete mixture, temperature treatment, etc., when they are countered or inadequately followed lead to a significant reduction in concrete strength. Here, the authors experimentally quantitatively determine the loss of strength in in-situ cast concrete structures due to inadequate following of process requirements, in comparison with full compliance.

9 Cr-- 1 Mo steel material for high temperature application

DOEpatents

Jablonski, Paul D; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

2012-11-27

One or more embodiments relates to a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The 9 Cr-1 Mo steel has a tempered martensite microstructure and is comprised of both large (0.5-3 .mu.m) primary titanium carbides and small (5-50 nm) secondary titanium carbides in a ratio of. from about 1:1.5 to about 1.5:1. The 9 Cr-1 Mo steel may be fabricated using exemplary austenizing, rapid cooling, and tempering steps without subsequent hot working requirements. The 9 Cr-1 Mo steel exhibits improvements in total mass gain, yield strength, and time-to-rupture over ASTM P91 and ASTM P92 at the temperature and time conditions examined.

Fracture mechanics concepts in reliability analysis of monolithic ceramics

NASA Technical Reports Server (NTRS)

Manderscheid, Jane M.; Gyekenyesi, John P.

1987-01-01

Basic design concepts for high-performance, monolithic ceramic structural components are addressed. The design of brittle ceramics differs from that of ductile metals because of the inability of ceramic materials to redistribute high local stresses caused by inherent flaws. Random flaw size and orientation requires that a probabilistic analysis be performed in order to determine component reliability. The current trend in probabilistic analysis is to combine linear elastic fracture mechanics concepts with the two parameter Weibull distribution function to predict component reliability under multiaxial stress states. Nondestructive evaluation supports this analytical effort by supplying data during verification testing. It can also help to determine statistical parameters which describe the material strength variation, in particular the material threshold strength (the third Weibull parameter), which in the past was often taken as zero for simplicity.

20 CFR 220.127 - When the only work experience is arduous unskilled physical labor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... unskilled physical labor. 220.127 Section 220.127 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS... only work experience is arduous unskilled physical labor. (a) Arduous work. Arduous work is primarily physical work requiring a high level of strength or endurance. The Board will consider the claimant unable...

20 CFR 220.127 - When the only work experience is arduous unskilled physical labor.

Code of Federal Regulations, 2013 CFR

2013-04-01

... unskilled physical labor. 220.127 Section 220.127 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS... only work experience is arduous unskilled physical labor. (a) Arduous work. Arduous work is primarily physical work requiring a high level of strength or endurance. The Board will consider the claimant unable...

20 CFR 220.127 - When the only work experience is arduous unskilled physical labor.

Code of Federal Regulations, 2012 CFR

2012-04-01

... unskilled physical labor. 220.127 Section 220.127 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS... only work experience is arduous unskilled physical labor. (a) Arduous work. Arduous work is primarily physical work requiring a high level of strength or endurance. The Board will consider the claimant unable...

20 CFR 220.127 - When the only work experience is arduous unskilled physical labor.

Code of Federal Regulations, 2014 CFR

2014-04-01

... unskilled physical labor. 220.127 Section 220.127 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS... only work experience is arduous unskilled physical labor. (a) Arduous work. Arduous work is primarily physical work requiring a high level of strength or endurance. The Board will consider the claimant unable...

New Approach to School Health Initiatives: Using Fitness Measures Instead of Body Mass Index to Evaluate Outcomes

ERIC Educational Resources Information Center

Phelps, Joshua; Smith, Amanda; Parker, Stephany; Hermann, Janice

2016-01-01

Oklahoma Cooperative Extension Service provided elementary school students with a program that included a noncompetitive physical activity component: circuit training that combined cardiovascular, strength, and flexibility activities without requiring high skill levels. The intent was to improve fitness without focusing on body mass index as an…

The Western Sydney Rustbelt: Recognizing and Building on Strengths in Pre-Service Teacher Education

ERIC Educational Resources Information Center

Naidoo, Loshini; D'warte, Jacqueline Ann

2017-01-01

Preparing pre-service teachers to address the disparities in educational attainment that occur in settings with complex demographics such as high poverty and super diversity (Vertovec, 2007) require a theoretically driven contextual and spacial (Soja, 1996) understanding of disadvantage. This understanding highlights the structural and systemic…

Voice Savers for Music Teachers

ERIC Educational Resources Information Center

Cookman, Starr

2012-01-01

Music teachers are in a class all their own when it comes to voice use. These elite vocal athletes require stamina, strength, and flexibility from their voices day in, day out for hours at a time. Voice rehabilitation clinics and research show that music education ranks high among the professionals most commonly affected by voice problems.…

A low-cost, high-field-strength magnetic resonance imaging-compatible actuator.

PubMed

Secoli, Riccardo; Robinson, Matthew; Brugnoli, Michele; Rodriguez y Baena, Ferdinando

2015-03-01

To perform minimally invasive surgical interventions with the aid of robotic systems within a magnetic resonance imaging scanner offers significant advantages compared to conventional surgery. However, despite the numerous exciting potential applications of this technology, the introduction of magnetic resonance imaging-compatible robotics has been hampered by safety, reliability and cost concerns: the robots should not be attracted by the strong magnetic field of the scanner and should operate reliably in the field without causing distortion to the scan data. Development of non-conventional sensors and/or actuators is thus required to meet these strict operational and safety requirements. These demands commonly result in expensive actuators, which mean that cost effectiveness remains a major challenge for such robotic systems. This work presents a low-cost, high-field-strength magnetic resonance imaging-compatible actuator: a pneumatic stepper motor which is controllable in open loop or closed loop, along with a rotary encoder, both fully manufactured in plastic, which are shown to perform reliably via a set of in vitro trials while generating negligible artifacts when imaged within a standard clinical scanner. © IMechE 2015.

Isothermal pumping analysis for high-altitude tethered balloons

PubMed Central

Kuo, Kirsty A.; Hunt, Hugh E. M.

2015-01-01

High-altitude tethered balloons have potential applications in communications, surveillance, meteorological observations and climate engineering. To maintain balloon buoyancy, power fuel cells and perturb atmospheric conditions, fluids could be pumped from ground level to altitude using the tether as a hose. This paper examines the pumping requirements of such a delivery system. Cases considered include delivery of hydrogen, sulfur dioxide (SO2) and powders as fluid-based slurries. Isothermal analysis is used to determine the variation of pressures and velocities along the pipe length. Results show that transport of small quantities of hydrogen to power fuel cells and maintain balloon buoyancy can be achieved at pressures and temperatures that are tolerable in terms of both the pipe strength and the current state of pumping technologies. To avoid solidification, transport of SO2 would require elevated temperatures that cannot be tolerated by the strength fibres in the pipe. While the use of particle-based slurries rather than SO2 for climate engineering can reduce the pipe size significantly, the pumping pressures are close to the maximum bursting pressure of the pipe. PMID:26543573

Isothermal pumping analysis for high-altitude tethered balloons.

PubMed

Kuo, Kirsty A; Hunt, Hugh E M

2015-06-01

High-altitude tethered balloons have potential applications in communications, surveillance, meteorological observations and climate engineering. To maintain balloon buoyancy, power fuel cells and perturb atmospheric conditions, fluids could be pumped from ground level to altitude using the tether as a hose. This paper examines the pumping requirements of such a delivery system. Cases considered include delivery of hydrogen, sulfur dioxide (SO2) and powders as fluid-based slurries. Isothermal analysis is used to determine the variation of pressures and velocities along the pipe length. Results show that transport of small quantities of hydrogen to power fuel cells and maintain balloon buoyancy can be achieved at pressures and temperatures that are tolerable in terms of both the pipe strength and the current state of pumping technologies. To avoid solidification, transport of SO2 would require elevated temperatures that cannot be tolerated by the strength fibres in the pipe. While the use of particle-based slurries rather than SO2 for climate engineering can reduce the pipe size significantly, the pumping pressures are close to the maximum bursting pressure of the pipe.

Indoor-Outdoor Detection Using a Smart Phone Sensor.

PubMed

Wang, Weiping; Chang, Qiang; Li, Qun; Shi, Zesen; Chen, Wei

2016-09-22

In the era of mobile internet, Location Based Services (LBS) have developed dramatically. Seamless Indoor and Outdoor Navigation and Localization (SNAL) has attracted a lot of attention. No single positioning technology was capable of meeting the various positioning requirements in different environments. Selecting different positioning techniques for different environments is an alternative method. Detecting the users' current environment is crucial for this technique. In this paper, we proposed to detect the indoor/outdoor environment automatically without high energy consumption. The basic idea was simple: we applied a machine learning algorithm to classify the neighboring Global System for Mobile (GSM) communication cellular base station's signal strength in different environments, and identified the users' current context by signal pattern recognition. We tested the algorithm in four different environments. The results showed that the proposed algorithm was capable of identifying open outdoors, semi-outdoors, light indoors and deep indoors environments with 100% accuracy using the signal strength of four nearby GSM stations. The required hardware and signal are widely available in our daily lives, implying its high compatibility and availability.

Modular fabrication and characterization of complex silicon carbide composite structures Advanced Reactor Technologies (ART) Research Final Report (Feb 2015 – May 2017)

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

Khalifa, Hesham

Advanced ceramic materials exhibit properties that enable safety and fuel cycle efficiency improvements in advanced nuclear reactors. In order to fully exploit these desirable properties, new processing techniques are required to produce the complex geometries inherent to nuclear fuel assemblies and support structures. Through this project, the state of complex SiC-SiC composite fabrication for nuclear components has advanced significantly. New methods to produce complex SiC-SiC composite structures have been demonstrated in the form factors needed for in-core structural components in advanced high temperature nuclear reactors. Advanced characterization techniques have been employed to demonstrate that these complex SiC-SiC composite structures providemore » the strength, toughness and hermeticity required for service in harsh reactor conditions. The complex structures produced in this project represent a significant step forward in leveraging the excellent high temperature strength, resistance to neutron induced damage, and low neutron cross section of silicon carbide in nuclear applications.« less

Creep Response and Deformation Processes in Nanocluster Strengthened Ferritic Steels

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

Hayashi, Taisuke; Sarosi, P. M.; Schneibel, Joachim H

2008-01-01

There is increasing demand for oxide-dispersion-strengthened ferritic alloys that possess both high-temperature strength and irradiation resistance. Improvement of the high-temperature properties requires an understanding of the operative deformation mechanisms. In this study, the microstructures and creep properties of the oxide-dispersion-strengthened alloy 14YWT have been evaluated as a function of annealing at 1000 C for 1 hour up to 32 days. The ultra-fine initial grain size (approx. 100nm) is stable after the shortest annealing time, and even after subsequent creep at 800 C. Longer annealing periods lead to anomalous grain growth that is further enhanced following creep. Remarkably, the minimum creepmore » rate is relatively insensitive to this dramatic grain-coarsening. The creep strength is attributed to highly stable, Ti-rich nanoclusters that appear to pin the initial primary grains, and present strong obstacles to dislocation motion in the large, anomalously grown grains.« less

Structural Polymer-Based Carbon Nanotube Composite Fibers: Understanding the Processing–Structure–Performance Relationship

PubMed Central

Song, Kenan; Zhang, Yiying; Meng, Jiangsha; Green, Emily C.; Tajaddod, Navid; Li, Heng; Minus, Marilyn L.

2013-01-01

Among the many potential applications of carbon nanotubes (CNT), its usage to strengthen polymers has been paid considerable attention due to the exceptional stiffness, excellent strength, and the low density of CNT. This has provided numerous opportunities for the invention of new material systems for applications requiring high strength and high modulus. Precise control over processing factors, including preserving intact CNT structure, uniform dispersion of CNT within the polymer matrix, effective filler–matrix interfacial interactions, and alignment/orientation of polymer chains/CNT, contribute to the composite fibers’ superior properties. For this reason, fabrication methods play an important role in determining the composite fibers’ microstructure and ultimate mechanical behavior. The current state-of-the-art polymer/CNT high-performance composite fibers, especially in regards to processing–structure–performance, are reviewed in this contribution. Future needs for material by design approaches for processing these nano-composite systems are also discussed. PMID:28809290

Flow properties of a series of experimental thermoplastic polymides

NASA Technical Reports Server (NTRS)

Burks, H. D.; Nelson, J. B.; Price, H. L.

1981-01-01

The softening temperature to degradation temperature range of the polymers was about 440 to 650 K. All of the polymers retained small amounts of solvent as indicated by an increase in T(sub g) as the polymers were dried. The flow properties showed that all three polymers had very high apparent viscosities and would require high pressures and/or high temperatures and/or long times to obtain adequate flow in prepregging and molding. Although none was intended for such application, two of the polymers were combined with carbon fibers by solution prepregging. The prepregs were molded into laminates at temperatures and times, the selection of which was guided by the results from the flow measurements. These laminates had room temperature short beam shear strength similar to that of carbon fiber laminates with a thermosetting polyimide matrix. However, the strength had considerable scatter, and given the difficult processing, these polymides probably would not be suitable for continuous fiber composites.

Heat treated 9 Cr-1 Mo steel material for high temperature application

DOEpatents

Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

2012-08-21

The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

Hybrid Welding Possibilities of Thick Sections for Arctic Applications

NASA Astrophysics Data System (ADS)

Bunaziv, Ivan; Akselsen, Odd M.; Ren, Xiaobo; Salminen, Antti

The arctic shelf contains about 20% of all undiscovered hydrocarbons on our planet, therefore oil and gas industry requires advanced steels to be used which withstand appropriate fracture toughness up to -60 °C and suitable welding technologies. High brightness laser with combination with arc source can be appropriate joining process even for very high strength advanced steels above 700 MPa for low temperature applications. Hybrid welding has improved each year becoming more standardized and reliable welding process. However, until now, its application was limited to shipbuilding and pipeline industry. Due to many reasonable advantages, hybrid welding, especially when it is combined with MIG/MAG, can be used in every possible industry. Inherent filler wire addition from the MIG/MAG source can improve fracture toughness at lower temperatures and increase overall productivity. This paper provides information about recent breakthrough in hybrid welding of thick section high-strength steels.

Study of the technics of coating stripping and FBG writing on polyimide fiber

NASA Astrophysics Data System (ADS)

Song, ZhiQiang; Qi, HaiFeng; Ni, JiaSheng; Wang, Chang

2017-10-01

Compared with ordinary optical fiber, polyimide fiber has the characteristics of high temperature resistance and high strength, which has important application in the field of optical fiber sensing. The common methods of polyimide coating stripping were introduced in this paper, including high temperature stripping, chemical stripping and arc ablation. In order to meet the requirements of FBG writing technology, a method using argon ion laser ablation coating was proposed. The method can precisely control the stripping length of the coating and completely does not affect the tensile strength of the optical fiber. According to the experiment, the fabrication process of polyimide FBG is stripping-hydrogen loadingwriting. Under the same conditions, 10 FBG samples were fabricated with good uniformity of wavelength bandwidth and reflectivity. UV laser ablation of polyimide coating has been proved to be a safe, reliable and efficient method.

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

Becher, P.F.; Sun, E.Y.; Hsueh, C.H.

The development of high strength ({ge} 1 GPa), high toughness ({ge} 10 MPa {radical}m) ceramic systems is being examined using two approaches. In silicon nitride, toughening is achieved by the introduction of large prismatic shaped grains dispersed in a fine grain matrix. For the system examined herein, both the microstructure and the composition must be controlled. A distinctly bimodal distribution of grain diameters combined with controlled yttria to alumina ratio in additives to promote interfacial debonding is required. Using a cermet approach, ductile Ni{sub 3}Al-bonded TiC exhibited toughening due to plastic deformation within the Ni{sub 3}Al binder phase assisted bymore » interfacial debonding and cleavage of TiC grains. The TiC-Ni{sub 3}Al cermets have toughness values equal to those of the WC-Co cermets. Furthermore, the TiC-Ni{sub 3}Al cermets exhibit high strengths that are retained in air to temperatures of {approximately} 1,000 C.« less

High power x-ray welding of metal-matrix composites

DOEpatents

Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

1999-01-01

A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10.sup.4 watts/cm.sup.2 and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

The Science of Cost-Effective Materials Design - A Study in the Development of a High Strength, Impact Resistant Steel

NASA Astrophysics Data System (ADS)

Abrahams, Rachel

2017-06-01

Intermediate alloy steels are widely used in applications where both high strength and toughness are required for extreme/dynamic loading environments. Steels containing greater than 10% Ni-Co-Mo are amongst the highest strength martensitic steels, due to their high levels of solution strengthening, and preservation of toughness through nano-scaled secondary hardening, semi-coherent hcp-M2 C carbides. While these steels have high yield strengths (σy 0.2 % >1200 MPa) with high impact toughness values (CVN@-40 >30J), they are often cost-prohibitive due to the material and processing cost of nickel and cobalt. Early stage-I steels such as ES-1 (Eglin Steel) were developed in response to the high cost of nickel-cobalt steels and performed well in extreme shock environments due to the presence of analogous nano-scaled hcp-Fe2.4 C epsilon carbides. Unfortunately, the persistence of W-bearing carbides limited the use of ES-1 to relatively thin sections. In this study, we discuss the background and accelerated development cycle of AF96, an alternative Cr-Mo-Ni-Si stage-I temper steel using low-cost heuristic and Integrated Computational Materials Engineering (ICME)-assisted methods. The microstructure of AF96 was tailored to mimic that of ES-1, while reducing stability of detrimental phases and improving ease of processing in industrial environments. AF96 is amenable to casting and forging, deeply hardenable, and scalable to 100,000 kg melt quantities. When produced at the industrial scale, it was found that AF96 exhibits near-statistically identical mechanical properties to ES-1 at 50% of the cost.

Cryogenic electrical properties of irradiated cyanate ester/epoxy insulation for fusion magnets

NASA Astrophysics Data System (ADS)

Li, X.; Wu, Z. X.; Li, J.; Xu, D.; Liu, H. M.; Huang, R. J.; Li, L. F.

2017-12-01

The insulation materials used in high field fusion magnets require excellent mechanical properties, high electrical breakdown strength, good thermal conductivity and high radiation tolerance. Previous investigations showed that cyanate ester/epoxy (CE/EP) insulation material, a candidate insulation for fusion magnets, can maintain good mechanical performance at cryogenic temperature after 10 MGy irradiation and has a much longer pot life than traditional epoxy insulation material. In order to quantify the electrical properties of the CE/EP insulation material at low temperature, a cryogenic electrical property testing system cooled by a G-M cryocooler was developed for this study. An insulation material with 40% cyanate ester and 60% epoxy was subjected to 60Co γ-ray irradiation in air at ambient temperature with a dose rate of 300 Gy/min, and total doses of 1 MGy, 5 MGy and 10 MGy. The electrical breakdown strength of this CE/EP insulation material was measured before and after irradiation. The results show that cryogenic temperature has a positive effect on the electrical breakdown strength of this composite, while the influence of 60Co γ-ray irradiation is not obvious at 6.1 K.

Shear joint capability versus bolt clearance

NASA Technical Reports Server (NTRS)

Lee, H. M.

1992-01-01

The results of a conservative analysis approach into the determination of shear joint strength capability for typical space-flight hardware as a function of the bolt-hole clearance specified in the design are presented. These joints are comprised of high-strength steel fasteners and abutments constructed of aluminum alloys familiar to the aerospace industry. A general analytical expression was first arrived at which relates bolt-hole clearance to the bolt shear load required to place all joint fasteners into a shear transferring position. Extension of this work allowed the analytical development of joint load capability as a function of the number of fasteners, shear strength of the bolt, bolt-hole clearance, and the desired factor of safety. Analysis results clearly indicate that a typical space-flight hardware joint can withstand significant loading when less than ideal bolt hole clearances are used in the design.

Characterization of three commercial Y-TZP ceramics produced for their high-translucency, high-strength and high-surface area.

PubMed

Tong, Hui; Tanaka, Carina B; Kaizer, Marina R; Zhang, Yu

2016-01-01

Developing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with high strength and translucency could significantly widen the clinical indications of monolithic zirconia restorations. This study investigates the mechanical and optical properties of three Y-TZP ceramics: High-Translucency, High-Strength and High-Surface Area. The four-point bending strengths (mean ± standard error) for the three Y-TZP ceramics ( n = 10) were 990 ± 39, 1416 ± 33 and 1076 ± 32 MPa for High-Translucency, High-Strength and High-Surface Area, respectively. The fracture toughness values (mean ± standard error) for the three zirconias ( n = 10) were 3.24 ± 0.10, 3.63 ± 0.12 and 3.21 ± 0.14 MPa m 1/2 for High-Translucency, High-Strength and High-Surface Area, respectively. Both strength and toughness values of High-Strength zirconia were significantly higher than High-Surface Area and High-Translucency zirconias. Translucency parameter values of High-Translucency zirconia were considerably higher than High-Strength and High-Surface Area zirconias. However, all three zirconias became essentially opaque when their thickness reached 1 mm or greater. Our findings suggest that there exists a delicate balance between mechanical and optical properties of the current commercial Y-TZP ceramics.

Approaches for springback reduction when forming ultra high-strength sheet metals

NASA Astrophysics Data System (ADS)

Radonjic, R.; Liewald, M.

2016-11-01

Nowadays, the automotive industry is challenged constantly by increasing environmental regulations and the continuous enhancement of standards with regard to passenger's safety (NCAP, Part 1). In order to fulfil the aforementioned requirements, the use of ultra high-strength steels in research and industrial applications is of high interest. When forming such materials, the main problem results from the large amount of springback which occurs after the release of the part. This paper shows the applicability of several approaches for the reduction of springback amount by forming of one hat channel shaped component. A novel approach for springack reduction which is based on forming with an alternating blank draw-in is presented as well. In this investigation an ultra high-strength steel of the grade DP 980 was used. The part's measurements were taken at significant cross-sections in order to provide a qualitative comparison between the reference geometry and the part's released shape. The obtained results were analysed and used in order to quantify the success of particular approaches for springback reduction. When taking a curved hat channel shaped component as an example, the results achieved in the investigations showed that it is possible to reduce part shape deviations significantly when using DP 980 as workpiece material.

Rats avoid high magnetic fields: dependence on an intact vestibular system

PubMed Central

Houpt, Thomas A.; Cassell, Jennifer A.; Riccardi, Christina; DenBleyker, Megan D.; Hood, Alison; Smith, James C.

2009-01-01

Summary HOUPT, T.A., J.A. CASSELL, C. RICCARDI, M.D. DENBLEYKER, A. HOOD, AND J.C. SMITH. Rats avoid high magnetic fields: dependence on an intact vestibular system. PHYSIOL BEHAV 00(0)000-000, 2006. High strength static magnetic fields are thought to be benign and largely undetectable by mammals. As magnetic resonance imaging (MRI) machines increase in strength, however, potential aversive effects may become clinically relevant. Here we report that rats find entry into a 14.1 T magnet aversive, and that they can detect and avoid entry into the magnet at a point where the magnetic field is 2 T or lower. Rats were trained to climb a ladder through the bore of a 14.1 T superconducting magnet. After their first climb into 14.1 T, most rats refused to re-enter the magnet or climb past the 2 T field line. This result was confirmed in a resistive magnet in which the magnetic field was varied from 1 to 14 T. Detection and avoidance required the vestibular apparatus of the inner ear, because labyrinthectomized rats readily traversed the magnet. The inner ear is a novel site for magnetic field transduction in mammals, but perturbation of the vestibular apparatus would be consistent with human reports of vertigo and nausea around high strength MRI machines. PMID:17585969

Constitutive Model Constants for Al7075-T651 and Al7075-T6

NASA Astrophysics Data System (ADS)

Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

2009-06-01

Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

NASA Astrophysics Data System (ADS)

Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

2017-01-01

Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

Latest Development and Application of High Strength and Heavy Gauge Pipeline Steel in China

NASA Astrophysics Data System (ADS)

Yongqing, Zhang; Aimin, Guo; Chengjia, Shang; Qingyou, Liu; Gray, J. Malcolm; Barbaro, Frank

Over the past twenty years, significant advances have been made in the field of microalloying and associated application, among which one of the most successful application cases is HTP practice for heavy gauge, high strength pipeline steels. Combined the strengthening effects of TMCP and retardation effects of austenite recrystallization with increasing Nb in austenite region, HTP conception with low carbon and high niobium alloy design has been successfully applied to develop X80 coil with a thickness of 18.4mm used for China's Second West-East pipeline. During this process, big efforts were made to further develop and enrich the application of microalloying technology, and at the same time the strengthening effects of Nb have been completely unfolded and fully utilized with improved metallurgical quality and quantitative analysis of microstructure. In this paper, the existing status and strengthening effect of Nb during reheating, rolling, cooling and welding have been analyzed and characterized based on mass production samples and laboratory analysis. As confirmed, grain refinement remains the most basic strengthening measure to reduce the microstructure gradient along the thickness, which in turn enlarges the processing window to improve upon low temperature toughness, and finally make it possible to develop heavy gauge, high strength pipeline steels with more challenging fracture toughness requirements.

Effects of a Fibrin Sealant on Skin Graft Tissue Adhesion in a Rodent Model.

PubMed

Balceniuk, Mark D; Wingate, Nicholas A; Krein, Howard; Curry, Joseph; Cognetti, David; Heffelfiner, Ryan; Luginbuhl, Adam

2016-07-01

To establish a rodent model for skin grafting with fibrin glue and examine the effects of fibrin glue on the adhesive strength of skin grafts without bolsters. Animal cohort. Academic hospital laboratory. Three skin grafts were created using a pneumatic microtome on the dorsum of 12 rats. Rats were evenly divided into experimental (n = 6) and control (n = 6) groups. The experimental group received a thin layer of fibrin glue between the graft and wound bed, and the control group was secured with standard bolsters. Adherence strength of the skin graft was tested by measurement of force required to sheer the graft from the recipient wound. Adhesion strength measurements were taken on postoperative days (PODs) 1, 2, and 3. The experimental group required an average force of 719 g on POD1, 895 g on POD2, and 676 g on POD3, while the average force in the control group was 161 g on POD1, 257 g on POD2, and 267 g on POD3. On each of the 3 PODs, there was a significant difference in adherence strength between the experimental and control groups (P = .036, P = .029, P = .024). There is a significant difference in the adhesion strength of skin grafts to the wound bed in the early postoperative period of the 2 groups. In areas of high mobility, using the fibrin sealant can keep the graft immobile during the critical phases of early healing. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

Data error and highly parameterized groundwater models

USGS Publications Warehouse

Hill, M.C.

2008-01-01

Strengths and weaknesses of highly parameterized models, in which the number of parameters exceeds the number of observations, are demonstrated using a synthetic test case. Results suggest that the approach can yield close matches to observations but also serious errors in system representation. It is proposed that avoiding the difficulties of highly parameterized models requires close evaluation of: (1) model fit, (2) performance of the regression, and (3) estimated parameter distributions. Comparisons to hydrogeologic information are expected to be critical to obtaining credible models. Copyright ?? 2008 IAHS Press.

Reliable bonding using indium-based solders

NASA Astrophysics Data System (ADS)

Cheong, Jongpil; Goyal, Abhijat; Tadigadapa, Srinivas; Rahn, Christopher

2004-01-01

Low temperature bonding techniques with high bond strengths and reliability are required for the fabrication and packaging of MEMS devices. Indium and indium-tin based bonding processes are explored for the fabrication of a flextensional MEMS actuator, which requires the integration of lead zirconate titanate (PZT) substrate with a silicon micromachined structure at low temperatures. The developed technique can be used either for wafer or chip level bonding. The lithographic steps used for the patterning and delineation of the seed layer limit the resolution of this technique. Using this technique, reliable bonds were achieved at a temperature of 200°C. The bonds yielded an average tensile strength of 5.41 MPa and 7.38 MPa for samples using indium and indium-tin alloy solders as the intermediate bonding layers respectively. The bonds (with line width of 100 microns) showed hermetic sealing capability of better than 10-11 mbar-l/s when tested using a commercial helium leak tester.

Reliable bonding using indium-based solders

NASA Astrophysics Data System (ADS)

Cheong, Jongpil; Goyal, Abhijat; Tadigadapa, Srinivas; Rahn, Christopher

2003-12-01

Low temperature bonding techniques with high bond strengths and reliability are required for the fabrication and packaging of MEMS devices. Indium and indium-tin based bonding processes are explored for the fabrication of a flextensional MEMS actuator, which requires the integration of lead zirconate titanate (PZT) substrate with a silicon micromachined structure at low temperatures. The developed technique can be used either for wafer or chip level bonding. The lithographic steps used for the patterning and delineation of the seed layer limit the resolution of this technique. Using this technique, reliable bonds were achieved at a temperature of 200°C. The bonds yielded an average tensile strength of 5.41 MPa and 7.38 MPa for samples using indium and indium-tin alloy solders as the intermediate bonding layers respectively. The bonds (with line width of 100 microns) showed hermetic sealing capability of better than 10-11 mbar-l/s when tested using a commercial helium leak tester.

Methods, strengths, weaknesses, and limitations of bioequivalence tests with special regard to immunosuppressive drugs.

PubMed

van Gelder, Teun; Gabardi, Steven

2013-08-01

Within the field of solid organ transplantation, the patents for a number of immunosuppressive drugs have expired in the last few years. Tacrolimus, cyclosporine, and mycophenolate mofetil are now available as generic drugs. In some countries, the market penetration of these generic formulations is as high as 70%, whereas in some other countries, this figure is below 10%. Several professional societies have published position papers on the risks and benefits of generic substitution of immunosuppressive drugs. It often appears that transplant professionals are not fully aware of the requirements for registration of generic drugs. This article describes the registration requirements with a focus on bioequivalence testing, the strengths and weaknesses in this process, and the differences between Europe and the US. © 2013 The Authors Transplant International © 2013 European Society for Organ Transplantation. Published by Blackwell Publishing Ltd.

Nutritional Requirements for Space Station Freedom Crews

NASA Technical Reports Server (NTRS)

Lane, Helen W.; Rice, Barbara L.; Wogan, Christine F. (Editor)

1992-01-01

The purpose of this report was to set preliminary nutritional requirements for crewmembers flying from 90 to 180 day missions on Space Station Freedom. Specific recommendations included providing crewmembers with in flight feedback on nutritional intake, weight and strength, and incorporating issues of energy intake, body weight, body composition, strength, and protein intake in the flight medicine program. Exercise must be considered an integral part of any plan to maintain nutritional status, especially those modes that stress the skeleton and maintain body weight. Nutrient intake, amount of exercise, and drugs ingested must be recorded daily; high priority should be given to development of fully automated record systems that minimize astronauts' effort. A system of nutritional supplements should be developed to provide a method for reducing intake deficits that become apparent. Finally, post flight monitoring should include bone density, muscle mass and function, and iron status at three and six months after landing.

Solid-state Bonding of Superplastic Aluminum Alloy 7475 Sheet

NASA Technical Reports Server (NTRS)

Byun, T. D. S.; Vastava, R. B.

1985-01-01

Experimental works were carried out to study the feasibility of solid state bonding of superplastic aluminum 7475 sheet. Amount of deformation, bonding time, surface cleaning method and intermediate layer were the process parameters investigated. Other parameters, held constant by the superplastic forming condition which is required to obtain a concurrent solid state bonding, are bonding temperature, bonding pressure and atmosphere. Bond integrity was evaluated through metallographic examination, X-ray line scan analysis, SEM fractographic analysis and lap shear tests. The early results of the development program indicated that sound solid state bonding was accomplished for this high strength 7475 alloy with significant amounts of deformation. A thin intermediate layer of the soft 5052 aluminum alloy aided in achieving a solid state bonding by reducing the required amount of plastic deformation at the interface. Bond strength was substantially increased by a post bond heat treatment.

Hydrodynamics with strength: scaling-invariant solutions for elastic-plastic cavity expansion models

NASA Astrophysics Data System (ADS)

Albright, Jason; Ramsey, Scott; Baty, Roy

2017-11-01

Spherical cavity expansion (SCE) models are used to describe idealized detonation and high-velocity impact in a variety of materials. The common theme in SCE models is the presence of a pressure-driven cavity or void within a domain comprised of plastic and elastic response sub-regions. In past work, the yield criterion characterizing material strength in the plastic sub-region is usually taken for granted and assumed to take a known functional form restrictive to certain classes of materials, e.g. ductile metals or brittle geologic materials. Our objective is to systematically determine a general functional form for the yield criterion under the additional requirement that the SCE admits a similarity solution. Solutions determined under this additional requirement have immediate implications toward development of new compressible flow algorithm verification test problems. However, more importantly, these results also provide novel insight into modeling the yield criteria from the perspective of hydrodynamic scaling.

Experimental investigation of mode I fracture for brittle tube-shaped particles

NASA Astrophysics Data System (ADS)

Stasiak, Marta; Combe, Gaël; Desrues, Jacques; Richefeu, Vincent; Villard, Pascal; Armand, Gilles; Zghondi, Jad

2017-06-01

We focus herein on the mechanical behavior of highly crushable grains. The object of our interest, named shell, is a hollow cylinder grain with ring cross-section, made of baked clay. The objective is to model the fragmentation of such shells, by means of discrete element (DE) approach. To this end, fracture modes I (opening fracture) and II (in-plane shear fracture) have to be investigated experimentally. This paper is essentially dedicated to mode I fracture. Therefore, a campaign of Brazilian-like compression tests, that result in crack opening, has been performed. The distribution of the occurrence of tensile strength is shown to obey a Weibull distribution for the studied shells, and Weibull's modulus was quantified. Finally, an estimate of the numerical/physical parameters required in a DE model (local strength), is proposed on the basis of the energy required to fracture through a given surface in mode I or II.

Improvement of mechanical strength of sintered Mo alloyed steel by optimization of sintering and cold-forging processes with densification

NASA Astrophysics Data System (ADS)

Kamakoshi, Y.; Shohji, I.; Inoue, Y.; Fukuda, S.

2017-10-01

Powder metallurgy (P/M) materials have been expected to be spread in automotive industry. Generally, since sintered materials using P/M ones contain many pores and voids, mechanical properties of them are inferior to those of conventional wrought materials. To improve mechanical properties of the sintered materials, densification is effective. The aim of this study is to improve mechanical strength of sintered Mo-alloyed steel by optimizing conditions in sintering and cold-forging processes. Mo-alloyed steel powder was compacted. Then, pre-sintering (PS) using a vacuum sintering furnace was conducted. Subsequently, coldforging (CF) by a backward extrusion method was conducted to the pre-sintered specimen. Moreover, the cold-forged specimen was heat treated by carburizing, tempering and quenching (CQT). Afterwards, mechanical properties were investigated. As a result, it was found that the density of the PS specimen is required to be more than 7.4 Mg/m3 to strengthen the specimen by heat treatment after CF. Furthermore, density and the microstructure of the PS specimen are most important factors to make the high density and strength material by CF. At the CF load of 1200 kN, the maximum density ratio reached approximately 99% by the use of the PS specimen with proper density and microstructure. At the CF load of 900 kN, although density ratio was high like more than 97.8%, transverse rupture strength decreased sharply. Since densification caused high shear stress and stress concentration in the surface layer, microcracks occurred by the damages of inter-particle sintered connection of the surface layer. On the contrary, in case of the CF load of 1200 kN, ultra-densification of the surface layer occurred by a sufficient plastic flow. Such sufficient compressed specimens regenerated the sintered connections by high temperature heat treatment and thus the high strength densified material was obtained. These processes can be applicable to near net shape manufacturing without surface machining.

The Effect of Low Extremity Plyometric Training on Back Muscle Power of High School Throwing Event Athletes

PubMed Central

Park, Gi Duck; Lee, Joong Chul; Lee, Juri

2014-01-01

[Purpose] The physical strength elements required for athletic throwing events include muscle strength, swiftness, agility, speed, flexibility, and physical balance. Although plyometric training and weight training are implemented as representative training methods for improving swiftness and agility, most studies of it have been conducted with players of other sports. [Subjects] The study subjects were 10 throwing event athletes attending K physical education high school. The subjects were randomly assigned to a control group of five subjects and an experimental group of five subjects. To analyze the body composition, an Inbody 3.0 instrument (Biospace, Korea) was used as experimental equipment to measure heights, weight, body fat percentages, and muscle masses and a Biodex system 4.0 (BIODEX, USA) was used to measure isokinetic muscle-joint and lumbar muscle strengths. The plyometric training consisted of 15 techniques out of the training methods introduced in the ‘Power up plyometric training’. The plyometric program was implemented without any training load three times per week during daybreak exercises for the experimental group. The number of times and the number of sets were changed over time as follows: three sets of 10 times in the 1st −4th weeks, three sets of 15 times in the 5th–8th weeks, and five sets of 15 times in the 9th−12th weeks. [Results] According to the ANCOVA results of lumbar extensor muscle strength at 60°/sec, the overall reliability of the model was significant. According to the ANCOVA results of lumbar flexor muscle strength at 60°/sec, the overall reliability of the model was significant. [Conclusion] Plyometric training positively affected high school throwing event athletes. To summarize the study findings, the application of plyometric training with high intensity and loads improved the results of athletes who perform highly intensive exercises at normal times. PMID:24567698

The effect of low extremity plyometric training on back muscle power of high school throwing event athletes.

PubMed

Park, Gi Duck; Lee, Joong Chul; Lee, Juri

2014-01-01

[Purpose] The physical strength elements required for athletic throwing events include muscle strength, swiftness, agility, speed, flexibility, and physical balance. Although plyometric training and weight training are implemented as representative training methods for improving swiftness and agility, most studies of it have been conducted with players of other sports. [Subjects] The study subjects were 10 throwing event athletes attending K physical education high school. The subjects were randomly assigned to a control group of five subjects and an experimental group of five subjects. To analyze the body composition, an Inbody 3.0 instrument (Biospace, Korea) was used as experimental equipment to measure heights, weight, body fat percentages, and muscle masses and a Biodex system 4.0 (BIODEX, USA) was used to measure isokinetic muscle-joint and lumbar muscle strengths. The plyometric training consisted of 15 techniques out of the training methods introduced in the 'Power up plyometric training'. The plyometric program was implemented without any training load three times per week during daybreak exercises for the experimental group. The number of times and the number of sets were changed over time as follows: three sets of 10 times in the 1st -4th weeks, three sets of 15 times in the 5th-8th weeks, and five sets of 15 times in the 9th-12th weeks. [Results] According to the ANCOVA results of lumbar extensor muscle strength at 60°/sec, the overall reliability of the model was significant. According to the ANCOVA results of lumbar flexor muscle strength at 60°/sec, the overall reliability of the model was significant. [Conclusion] Plyometric training positively affected high school throwing event athletes. To summarize the study findings, the application of plyometric training with high intensity and loads improved the results of athletes who perform highly intensive exercises at normal times.

Issues associated with the use of Yoshida nonlinear isotropic/kinematic hardening material model in Advanced High Strength Steels

NASA Astrophysics Data System (ADS)

Shi, Ming F.; Zhang, Li; Zhu, Xinhai

2016-08-01

The Yoshida nonlinear isotropic/kinematic hardening material model is often selected in forming simulations where an accurate springback prediction is required. Many successful application cases in the industrial scale automotive components using advanced high strength steels (AHSS) have been reported to give better springback predictions. Several issues have been raised recently in the use of the model for higher strength AHSS including the use of two C vs. one C material parameters in the Armstrong and Frederick model (AF model), the original Yoshida model vs. Original Yoshida model with modified hardening law, and constant Young's Modulus vs. decayed Young's Modulus as a function of plastic strain. In this paper, an industrial scale automotive component using 980 MPa strength materials is selected to study the effect of two C and one C material parameters in the AF model on both forming and springback prediction using the Yoshida model with and without the modified hardening law. The effect of decayed Young's Modulus on the springback prediction for AHSS is also evaluated. In addition, the limitations of the material parameters determined from tension and compression tests without multiple cycle tests are also discussed for components undergoing several bending and unbending deformations.

MECHANICAL STRENGTH RESPONSES OF POLED LEAD ZIRCONATE TITANATE UNDER EXTREME ELECTRIC FIELD AND VARIOUS TEMPERATURE CONDITIONS

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

Wang, Hong; Matsunaga, Tadashi; Zhang, Kewei

PZT (lead zirconate titanate), particularly PZT-5A, is used in a variety of critical actuation and sensing systems because of its high Curie temperature and large piezoelectric coefficients. However, PZT is susceptible to mechanical failure. The evaluation of the mechanical strength of the material under the target working conditions is very important. This study presents part of the recent experimental developments in mechanical testing and evaluation of PZT materials at Oak Ridge National Laboratory. Ball-on-ring and four-point bending testing setups were used, with modifications made to account for testing requirements from high-level electric field and elevated temperature. The poled PZT-5A ormore » equivalent material was tested under various specimen and testing conditions. The parameters of the distribution of strengths (characteristic strength and Weibull modulus) are discussed in relation to the testing conditions. Fractographic results based on scanning electron microscopy are also presented and discussed. The related data can serve as input for the design of piezoceramic devices, not only those used in energy systems like fuel injectors in heavy-duty diesel engines, but also those used in structural health monitoring, energy harvesting, and other critical systems in aerospace and civil engineering.« less

Mega-earthquakes rupture flat megathrusts.

PubMed

Bletery, Quentin; Thomas, Amanda M; Rempel, Alan W; Karlstrom, Leif; Sladen, Anthony; De Barros, Louis

2016-11-25

The 2004 Sumatra-Andaman and 2011 Tohoku-Oki earthquakes highlighted gaps in our understanding of mega-earthquake rupture processes and the factors controlling their global distribution: A fast convergence rate and young buoyant lithosphere are not required to produce mega-earthquakes. We calculated the curvature along the major subduction zones of the world, showing that mega-earthquakes preferentially rupture flat (low-curvature) interfaces. A simplified analytic model demonstrates that heterogeneity in shear strength increases with curvature. Shear strength on flat megathrusts is more homogeneous, and hence more likely to be exceeded simultaneously over large areas, than on highly curved faults. Copyright © 2016, American Association for the Advancement of Science.

Investigation of Test Methods, Material Properties, and Processes for Solar Cell Encapsulants

NASA Technical Reports Server (NTRS)

1979-01-01

During this quarter the technical activities were directed toward the reformulation of ethylene/vinyl acetate copolymer for use as a compound in solar cell module fabrication. Successful formulations were devised that lowered the temperature required for cure and raised the gel content. A major volatile component was also eliminated (acrylate crosslinking agent) which should aid in the production of bubble free laminates. Adhesive strengths and primers for the bonding of ethylene/vinyl acetate to supersyrate and substrate materials was assessed with encouraging results. The incorporation of silane compounds gave high bond strengths. A survey of scrim materials was also conducted.

Detection of alpha radiation in a beta radiation field

DOEpatents

Mohagheghi, Amir H.; Reese, Robert P.

2001-01-01

An apparatus and method for detecting alpha particles in the presence of high activities of beta particles utilizing an alpha spectrometer. The apparatus of the present invention utilizes a magnetic field applied around the sample in an alpha spectrometer to deflect the beta particles from the sample prior to reaching the detector, thus permitting detection of low concentrations of alpha particles. In the method of the invention, the strength of magnetic field required to adequately deflect the beta particles and permit alpha particle detection is given by an algorithm that controls the field strength as a function of sample beta energy and the distance of the sample to the detector.

Ultrahigh Elastic Strain Energy Storage in Metal-Oxide-Infiltrated Patterned Hybrid Polymer Nanocomposites

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

Dusoe, Keith J.; Ye, Xinyi; Kisslinger, Kim

Modulus of resilience, the measure of a material’s capacity to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young’s modulus against their mutual scaling behavior. This task becomes further challenging if it needs to be carried out at the nanometer scale. Here, we demonstrate organic–inorganic hybrid composite nanopillars with one of the highest modulus of resilience per density by utilizing vapor-phase aluminum oxide infiltration in lithographically patterned negative photoresist SU-8. In situ nanomechanical measurementsmore » reveal a metal-like high yield strength (~500 MPa) with an unusually low, foam-like Young’s modulus (~7 GPa), a unique pairing that yields ultrahigh modulus of resilience, reaching up to ~24 MJ/m 3 as well as exceptional modulus of resilience per density of ~13.4 kJ/kg, surpassing those of most engineering materials. The hybrid polymer nanocomposite features lightweight, ultrahigh tunable modulus of resilience and versatile nanoscale lithographic patternability with potential for application as nanomechanical components which require ultrahigh mechanical resilience and strength.« less

Ultrahigh Elastic Strain Energy Storage in Metal-Oxide-Infiltrated Patterned Hybrid Polymer Nanocomposites

DOE PAGES

Dusoe, Keith J.; Ye, Xinyi; Kisslinger, Kim; ...

2017-10-19

Modulus of resilience, the measure of a material’s capacity to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young’s modulus against their mutual scaling behavior. This task becomes further challenging if it needs to be carried out at the nanometer scale. Here, we demonstrate organic–inorganic hybrid composite nanopillars with one of the highest modulus of resilience per density by utilizing vapor-phase aluminum oxide infiltration in lithographically patterned negative photoresist SU-8. In situ nanomechanical measurementsmore » reveal a metal-like high yield strength (~500 MPa) with an unusually low, foam-like Young’s modulus (~7 GPa), a unique pairing that yields ultrahigh modulus of resilience, reaching up to ~24 MJ/m 3 as well as exceptional modulus of resilience per density of ~13.4 kJ/kg, surpassing those of most engineering materials. The hybrid polymer nanocomposite features lightweight, ultrahigh tunable modulus of resilience and versatile nanoscale lithographic patternability with potential for application as nanomechanical components which require ultrahigh mechanical resilience and strength.« less

Statistical strength of experiments to reject local realism with photon pairs and inefficient detectors

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

Zhang Yanbao; Mathematical and Computational Sciences Division, National Institute of Standards and Technology, Boulder, Colorado, 80305; Knill, Emanuel

2010-03-15

Because of the fundamental importance of Bell's theorem, a loophole-free demonstration of a violation of local realism (LR) is highly desirable. Here, we study violations of LR involving photon pairs. We quantify the experimental evidence against LR by using measures of statistical strength related to the Kullback-Leibler (KL) divergence, as suggested by van Dam et al.[W. van Dam, R. D. Gill, and P. D. Grunwald, IEEE Trans. Inf. Theory. 51, 2812 (2005)]. Specifically, we analyze a test of LR with entangled states created from two independent polarized photons passing through a polarizing beam splitter. We numerically study the detection efficiencymore » required to achieve a specified statistical strength for the rejection of LR depending on whether photon counters or detectors are used. Based on our results, we find that a test of LR free of the detection loophole requires photon counters with efficiencies of at least 89.71%, or photon detectors with efficiencies of at least 91.11%. For comparison, we also perform this analysis with ideal unbalanced Bell states, which are known to allow rejection of LR with detector efficiencies above 2/3.« less

Design of the NASA Robonaut Hand

NASA Technical Reports Server (NTRS)

Lovchik, Chris S.; Aldridge, H. A.; Driftler, Myron A.

1999-01-01

The design of a highly anthropomorphic human scale robot hand for space based operations is described. This five finger hand combined with its integrated wrist and forearm has fourteen independent degrees of freedom. The device approximates very well the kinematics and required strength of an astronaut's hand when operating through a pressurized space suit glove. The mechanisms used to meet these requirements are explained in detail along with the design philosophy behind them. Integration experiences reveal the challenges associated with obtaining the required capabilities within the desired size. The initial finger control strategy is presented along with examples of obtainable grasps.

47 CFR 73.311 - Field strength contours.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b) The...

47 CFR 73.311 - Field strength contours.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false Field strength contours. 73.311 Section 73.311... Broadcast Stations § 73.311 Field strength contours. (a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate. (b) The...

Fitness characteristics of a suburban special weapons and tactics team.

PubMed

Pryor, Riana R; Colburn, Deanna; Crill, Matthew T; Hostler, David P; Suyama, J

2012-03-01

Special Weapons and Tactics (SWAT) operators are specialized law enforcement officers who traditionally perform their duties with higher anticipated workloads because of additional body armor, weapons, and equipment used for enhanced operations and protection. This elevated workload increases the need for SWAT operators to improve or maintain their physical fitness to consistently perform routine operations. Typical tasks require trunk rotation, overhead upper extremity use, upper and lower body strength use, and long waiting periods followed by explosive movements while wearing additional equipment. Eleven male SWAT operators from 1 SWAT team performed flexibility, strength, power, and aerobic capacity tests and a variety of job-related tasks. Data were compared with age- and gender-based normative data. Fitness testing revealed that officers ranked high on tests of muscular strength (leg strength, 90th percentile; bench press, 85th percentile); however, body composition (55th percentile), core body strength, and flexibility ranked lower. Furthermore, aerobic capacity and muscular power had a wide range of scores and were also not ideal to support maximal performance during routine operations. These data can assist exercise specialists choose fitness programs specifically for job-related tasks of SWAT operators when creating fitness programs. Fitness programming for law enforcement should focus on improving aerobic fitness, flexibility, core strength, and muscular power while maintaining muscular strength to meet the needs of these specialized officers.

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

14 CFR 31.21 - Loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Loads. 31.21 Section 31.21 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS Strength Requirements § 31.21 Loads. Strength requirements are specified in terms of...

Improving the prediction of the final part geometry in high strength steels U drawing by means of advanced material and friction models

NASA Astrophysics Data System (ADS)

de Argandoña, Eneko Saenz; Mendiguren, Joseba; Otero, Irune; Mugarra, Endika; Otegi, Nagore; Galdos, Lander

2018-05-01

Steel has been used in vehicles from the automotive industry's inception. Different steel grades are continually being developed in order to satisfy new fuel economy requirements. For example, advanced high strength steel grades (AHSS) are widely used due to their good strength/weight ratio. Because each steel grade has a different microstructure composition and hardness, they show different behaviors when they are subjected to different strain paths. Similarly, the friction behavior when using different contact pressures is considerably altered. In the present paper, four different steel grades, ZSt380, DP600, DP780 and Fortiform 1050 materials are deeply characterized using uniaxial and cyclic tension-compression tests. Coefficient of friction (COF) is also obtained using strip drawing tests. These results have been used to calibrate mixed kinematic-hardening material models as well as pressure dependent friction models. Finally, the geometrical accuracy of the different material and friction models has been evaluated by comparing the numerical predictions with experimental demonstrators obtained using a U-Drawing tester.

HAMSTRING INJURY REHABILITATION AND PREVENTION OF REINJURY USING LENGTHENED STATE ECCENTRIC TRAINING: A NEW CONCEPT

PubMed Central

Tim, Tyler; McHugh, Malachy

2012-01-01

Back ground and Purpose: Hamstring injury is a common occurrence in sport and there has been limited success in reducing this rate of recurrence to date. Description of Topic with Related Evidence: High speed running requires eccentric strength when the hamstring muscles are in a lengthened state. The lengthened state occurs when the hip is in flexion and the lower leg moves into extension, thus lengthening the two joint hamstring muscle over both articulations upon which they act. There is evidence to suggest that athletes who have sustained a hamstring strain lack strength when the muscle is utilized during performance in a lengthened state. Purpose: To examine the risk factors contributing to such a high recurrence rate and propose a unique rehabilitation strategy addressing these factors in order to decrease the rate of reinjury. Discussion/Relation to Clinical Practice: Failing to increase an athlete's eccentric strength in a lengthened position after a hamstring injury may predispose an athlete to subsequent reinjury. Incorporating lengthened state eccentric training may help reduce the rate of reinjury. Level of Evidence: Level 5 PMID:22666648

Lightweight Ceramics for Aeroacoustic Applications

NASA Technical Reports Server (NTRS)

Kwan, H. W.; Spamer, G. T.; Yu, J.; Yasukawa, B.

1997-01-01

The use of a HTP (High Temperature Performance) ceramic foam for aeroacoustic applications is investigated. HTP ceramic foam is a composition of silica and alumina fibers developed by LMMS. This foam is a lightweight high-temperature fibrous bulk material with small pore size, ultra high porosity, and good strength. It can be used as a broadband noise absorber at both room and high temperature (up to 1800 F). The investigation included an acoustic assessment as well as material development, and environmental and structural evaluations. The results show that the HTP ceramic foam provides good broadband noise absorbing capability and adequate strength when incorporating the HTP ceramic foam system into a honeycomb sandwich structure. On the other hand, the material is sensitive to Skydrol and requires further improvements. Good progress has been made in the impedance model development. A relationship between HTP foam density, flow resistance, and tortuosity will be established in the near future. Additional effort is needed to investigate the coupling effects between face sheet and HTP foam material.

Wireless Sensor Network for Radiometric Detection and Assessment of Partial Discharge in High-Voltage Equipment

NASA Astrophysics Data System (ADS)

Upton, D. W.; Saeed, B. I.; Mather, P. J.; Lazaridis, P. I.; Vieira, M. F. Q.; Atkinson, R. C.; Tachtatzis, C.; Garcia, M. S.; Judd, M. D.; Glover, I. A.

2018-03-01

Monitoring of partial discharge (PD) activity within high-voltage electrical environments is increasingly used for the assessment of insulation condition. Traditional measurement techniques employ technologies that either require off-line installation or have high power consumption and are hence costly. A wireless sensor network is proposed that utilizes only received signal strength to locate areas of PD activity within a high-voltage electricity substation. The network comprises low-power and low-cost radiometric sensor nodes which receive the radiation propagated from a source of PD. Results are reported from several empirical tests performed within a large indoor environment and a substation environment using a network of nine sensor nodes. A portable PD source emulator was placed at multiple locations within the network. Signal strength measured by the nodes is reported via WirelessHART to a data collection hub where it is processed using a location algorithm. The results obtained place the measured location within 2 m of the actual source location.

High-volume resistance training session acutely diminishes respiratory muscle strength.

PubMed

Hackett, Daniel A; Johnson, Nathan A; Chow, Chin-Moi

2012-01-01

This study investigated the effect of a high-volume compared to a low-volume resistance training session on maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Twenty male subjects with resistance training experience (6.2 ± 3.2 y), in a crossover trial, completed two resistance training protocols (high-volume: 5 sets per exercise; low-volume: 2 sets per exercise) and a control session (no exercise) on 3 separate occasions. MIP and MEP decreased by 13.6% (p < 0.01) and 14.7% (p < 0.01) respectively from pre-session MIP and MEP, following the high-volume session. MIP and MEP were unaffected following the low-volume or the control sessions. MIP returned to pre-session values after 40 minutes, whereas MEP remained significantly reduced after 60 minutes post-session by 9.2% compared to pre-session (p < 0.01). The findings suggest that the high-volume session significantly decreased MIP and MEP post-session, implicating a substantially increased demand on the respiratory muscles and that adequate recovery is mandatory following this mode of training. Key pointsRespiratory muscular strength performance is acutely diminished following a high-volume whole-body resistance training session.Greater ventilatory requirements and generation of IAP during the high-volume resistance training session may have contributed to the increased demand placed on the respiratory muscles.Protracted return of respiratory muscular strength performance to baseline levels may have implications for individuals prior to engaging in subsequent exercise bouts.

Exercise training guidelines for the elderly.

PubMed

Evans, W J

1999-01-01

The capacity of older men and women to adapt to increased levels of physical activity is preserved, even in the most elderly. Aerobic exercise results in improvements in functional capacity and reduced risk of developing Type II diabetes in the elderly. High-intensity resistance training (above 60% of the one repetition maximum) has been demonstrated to cause large increases in strength in the elderly. In addition, resistance training result in significant increases in muscle size in elderly men and women. Resistance training has also been shown to significantly increase energy requirements and insulin action of the elderly. We have recently demonstrated that resistance training has a positive effect on multiple risk factors for osteoporotic fracture in previously sedentary postmenopausal women. Because the sedentary lifestyle of a long-term care facility may exacerbate losses of muscle function, we have applied this same training program to frail, institutionalized elderly men and women. In a population of 100 nursing home residents, a randomly assigned high-intensity strength-training program resulted in significant gains in strength and functional status. In addition, spontaneous activity, measured by activity monitors, increased significantly in those participating in the exercise program whereas there was no change in the sedentary control group. Before the strength training intervention, the relationship of whole body potassium and leg strength was seen to be relatively weak (r2 = 0.29, P < 0.001), indicating that in the very old, muscle mass is an important but not the only determining factor of functional status. Thus, exercise may minimize or reverse the syndrome of physical frailty, which is so prevalent among the most elderly. Because of their low functional status and high incidence of chronic disease, there is no segment of the population that can benefit more from exercise than the elderly.

On the Contribution of Curl-Free Current Patterns to the Ultimate Intrinsic Signal-to-Noise Ratio at Ultra-High Field Strength.

PubMed

Pfrommer, Andreas; Henning, Anke

2017-05-01

The ultimate intrinsic signal-to-noise ratio (SNR) is a coil independent performance measure to compare different receive coil designs. To evaluate this benchmark in a sample, a complete electromagnetic basis set is required. The basis set can be obtained by curl-free and divergence-free surface current distributions, which excite linearly independent solutions to Maxwell's equations. In this work, we quantitatively investigate the contribution of curl-free current patterns to the ultimate intrinsic SNR in a spherical head-sized model at 9.4 T. Therefore, we compare the ultimate intrinsic SNR obtained with having only curl-free or divergence-free current patterns, with the ultimate intrinsic SNR obtained from a combination of curl-free and divergence-free current patterns. The influence of parallel imaging is studied for various acceleration factors. Moreover results for different field strengths (1.5 T up to 11.7 T) are presented at specific voxel positions and acceleration factors. The full-wave electromagnetic problem is analytically solved using dyadic Green's functions. We show, that at ultra-high field strength (B 0 ⩾7T) a combination of curl-free and divergence-free current patterns is required to achieve the best possible SNR at any position in a spherical head-sized model. On 1.5- and 3T platforms, divergence-free current patterns are sufficient to cover more than 90% of the ultimate intrinsic SNR. Copyright © 2017 John Wiley & Sons, Ltd.

Battlefield MRI

DOE PAGES

Espy, Michelle

2015-06-01

Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

Code of Federal Regulations, 2013 CFR

2013-10-01

... the following additional requirements: Note: For high alloy steels refer to § 54.25-15. For heat... tempered steels. The ultimate and yield strengths shall be as shown in the applicable specification and... 46 Shipping 2 2013-10-01 2013-10-01 false Low temperature operation-ferritic steels (replaces UCS...

46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

Code of Federal Regulations, 2014 CFR

2014-10-01

... the following additional requirements: Note: For high alloy steels refer to § 54.25-15. For heat... tempered steels. The ultimate and yield strengths shall be as shown in the applicable specification and... 46 Shipping 2 2014-10-01 2014-10-01 false Low temperature operation-ferritic steels (replaces UCS...

46 CFR 54.25-10 - Low temperature operation-ferritic steels (replaces UCS-65 through UCS-67).

Code of Federal Regulations, 2012 CFR

2012-10-01

... the following additional requirements: Note: For high alloy steels refer to § 54.25-15. For heat... tempered steels. The ultimate and yield strengths shall be as shown in the applicable specification and... 46 Shipping 2 2012-10-01 2012-10-01 false Low temperature operation-ferritic steels (replaces UCS...

A Method of Computing Electric Field Parameters on Boundaries between Two Media

ERIC Educational Resources Information Center

Rizhov, Alexander

2010-01-01

Many problems of electric field strength on a boundary between two media require college-level mathematical analysis. However, when the boundary between media is represented by a sphere or a flat plane, these types of problems can be solved algebraically, placing them within reach of high school students. This article presents a solution analysis…

Sit-to-Stand Movement in Children with Cerebral Palsy: A Critical Review

ERIC Educational Resources Information Center

dos Santos, Adriana Neves; Pavao, Silvia Leticia; Rocha, Nelci Adriana Cicuto Ferreira

2011-01-01

Sit-to-stand (STS) movement is widely performed in daily life and an important pre requisite for acquisition of functional abilities. However, STS is a biomechanical demanding task which requires high levels of neuromuscular coordination, muscle strength and postural control. As children with cerebral palsy (CP) exhibit a series of impairments in…

Battlefield MRI

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

Espy, Michelle

Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

Microstructural Control and Characterization of Bi2V0.9Cu0.1O5.35 (BICUVOX) Ceramics

NASA Astrophysics Data System (ADS)

Razmyar, Soheil

2011-12-01

The widespread commercialization of solid-oxide fuel cells (SOFCs) and solid-oxide electrolyte cells (SOECs) is primarily limited by material degradation issues related to the required high temperature operation (>800°C). Applications of stabilized zirconia based electrolytes, which are the most commonly used oxide ion conductors, have been limited to this high temperature regime due to its low oxygen ion conductivity below 800°C. Solid electrolytes made of the BIMEVOX compositional family of materials (Bi2MexV 1-xO5.5-delta where Me=Cu, Co, Mg, Ni, Fe...) exhibit high oxide ionic conductivity similar to YSZ at a low temperature (300--600°C). Among these materials copper-substituted bismuth vanadate (Bi2V0.9Cu0.1O5.35, BICUVOX), was reported to have the highest ionic conductivity at 400°C (0.02 S/cm). It's one of the most important drawbacks of using BICUVOX, as a SOFC electrolyte is the low mechanical strength, which makes it unusable for most electrolyte supported applications. This research aims at improving mechanical strength by careful control of synthesis processing and sintering processes, thus making BICUVOX a viable material option for intermediate temperature SOFC. A co-precipitation method was used to synthesize submicron BICUVOX powder. The powder was utilized to fabricate a thin (< 250 microm) BICUVOX electrolyte membrane, with 2.5 cm2 active area and high mechanical strength. The fabricated BICUVOX membranes were densified to 97% theoretical density at lower sintering temperature and shorter time (675°C/1 h), and shows fine grain size (<1.5microm) and high mechanical strength (159 MPa).

Nutrition guidelines for strength sports: sprinting, weightlifting, throwing events, and bodybuilding.

PubMed

Slater, Gary; Phillips, Stuart M

2011-01-01

Strength and power athletes are primarily interested in enhancing power relative to body weight and thus almost all undertake some form of resistance training. While athletes may periodically attempt to promote skeletal muscle hypertrophy, key nutritional issues are broader than those pertinent to hypertrophy and include an appreciation of the sports supplement industry, the strategic timing of nutrient intake to maximize fuelling and recovery objectives, plus achievement of pre-competition body mass requirements. Total energy and macronutrient intakes of strength-power athletes are generally high but intakes tend to be unremarkable when expressed relative to body mass. Greater insight into optimization of dietary intake to achieve nutrition-related goals would be achieved from assessment of nutrient distribution over the day, especially intake before, during, and after exercise. This information is not readily available on strength-power athletes and research is warranted. There is a general void of scientific investigation relating specifically to this unique group of athletes. Until this is resolved, sports nutrition recommendations for strength-power athletes should be directed at the individual athlete, focusing on their specific nutrition-related goals, with an emphasis on the nutritional support of training.

Validity and reliability of a low-cost digital dynamometer for measuring isometric strength of lower limb.

PubMed

Romero-Franco, Natalia; Jiménez-Reyes, Pedro; Montaño-Munuera, Juan A

2017-11-01

Lower limb isometric strength is a key parameter to monitor the training process or recognise muscle weakness and injury risk. However, valid and reliable methods to evaluate it often require high-cost tools. The aim of this study was to analyse the concurrent validity and reliability of a low-cost digital dynamometer for measuring isometric strength in lower limb. Eleven physically active and healthy participants performed maximal isometric strength for: flexion and extension of ankle, flexion and extension of knee, flexion, extension, adduction, abduction, internal and external rotation of hip. Data obtained by the digital dynamometer were compared with the isokinetic dynamometer to examine its concurrent validity. Data obtained by the digital dynamometer from 2 different evaluators and 2 different sessions were compared to examine its inter-rater and intra-rater reliability. Intra-class correlation (ICC) for validity was excellent in every movement (ICC > 0.9). Intra and inter-tester reliability was excellent for all the movements assessed (ICC > 0.75). The low-cost digital dynamometer demonstrated strong concurrent validity and excellent intra and inter-tester reliability for assessing isometric strength in the main lower limb movements.

Observational evidence and strength of evidence domains: case examples

PubMed Central

2014-01-01

Background Systematic reviews of healthcare interventions most often focus on randomized controlled trials (RCTs). However, certain circumstances warrant consideration of observational evidence, and such studies are increasingly being included as evidence in systematic reviews. Methods To illustrate the use of observational evidence, we present case examples of systematic reviews in which observational evidence was considered as well as case examples of individual observational studies, and how they demonstrate various strength of evidence domains in accordance with current Agency for Healthcare Research and Quality (AHRQ) Evidence-based Practice Center (EPC) methods guidance. Results In the presented examples, observational evidence is used when RCTs are infeasible or raise ethical concerns, lack generalizability, or provide insufficient data. Individual study case examples highlight how observational evidence may fulfill required strength of evidence domains, such as study limitations (reduced risk of selection, detection, performance, and attrition); directness; consistency; precision; and reporting bias (publication, selective outcome reporting, and selective analysis reporting), as well as additional domains of dose-response association, plausible confounding that would decrease the observed effect, and strength of association (magnitude of effect). Conclusions The cases highlighted in this paper demonstrate how observational studies may provide moderate to (rarely) high strength evidence in systematic reviews. PMID:24758494

Effects of porosity on weld-joint tensile strength of aluminum alloys

NASA Technical Reports Server (NTRS)

Lovoy, C. V.

1974-01-01

Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

Evaluating of NASA-Langley Research Center explosion seam welding

NASA Technical Reports Server (NTRS)

Otto, H. E.; Wittman, R.

1977-01-01

An explosion bonding technique to meet current fabrication requirements was demonstrated. A test program was conducted on explosion bonded joints, compared to fusion joints in 6061-T6 aluminum. The comparison was made in required fixtures, non-destructive testing, static strength and fatigue strength.

Rapid Tooling for Functional Prototype of Metal Mold Processes Final Report CRADA No. TC-1032-98

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

Heestand, G.; Jaskolski, T.

Production inserts for die-casting were generally fabricated from materials with sufficient strength and· good wear properties at casting temperatures for long life. Frequently tool steels were used and machining was done with a combination of. conventional and Electric Discharge Machining (EDM) with some handwork, an expensive and time consuming process, partilly for prototype work. We proposed electron beam physical vapor deposition (EBPVD) as a process for rapid fabrication of dies. Metals, ranging from low melting point to refractory metals (Ta, Mo, etc.), would be evaporated and deposited at high rates (-2mm/hr.). Alloys could be easily evaporated and deposited if theirmore » constituent vapor pressures were similar and with more difficulty if they were not. Of course, layering of different materials was possible if required for a specific application. For example, a hard surface layer followed by a tough steel and backed by a high thermal conductivity (possibly cooled) copper layer could be fabricated. Electron-beam deposits exhibited 100% density and lull strength when deposited at a substrate (mandrel) temperature that was a substantial fraction of the deposited material's melting point. There were several materials that could have the required high temperature properties and ease of fabrication required for such a mandrel. We had successfully used graphite, machined from free formed objects with a replicator, to produce aluminum-bronze test molds. There were several parting layer materials of interest, but the ideal material depended upon the specific application.« less

GingisKHAN™ protease cleavage allows a high-throughput antibody to Fab conversion enabling direct functional assessment during lead identification of human monoclonal and bispecific IgG1 antibodies

PubMed Central

Moelleken, Jörg; Gassner, Christian; Lingke, Sabine; Tomaschek, Simone; Tyshchuk, Oksana; Lorenz, Stefan; Mølhøj, Michael

2017-01-01

ABSTRACT The determination of the binding strength of immunoglobulins (IgGs) to targets can be influenced by avidity when the targets are soluble di- or multimeric proteins, or associated to cell surfaces, including surfaces introduced from heterogeneous assays. However, for the understanding of the contribution of a second drug-to-target binding site in molecular design, or for ranking of monovalent binders during lead identification, affinity-based assessment of the binding strength is required. Typically, monovalent binders like antigen-binding fragments (Fabs) are generated by proteolytic cleavage with papain, which often results in a combination of under- and over-digestion, and requires specific optimization and chromatographic purification of the desired Fabs. Alternatively, the Fabs are produced by recombinant approaches. Here, we report a lean approach for the functional assessment of human IgG1s during lead identification based on an in-solution digestion with the GingisKHAN™ protease, generating a homogenous pool of intact Fabs and Fcs and enabling direct assaying of the Fab in the digestion mixture. The digest with GingisKHAN™ is highly specific and quantitative, does not require much optimization, and the protease does not interfere with methods typically applied for lead identification, such as surface plasmon resonance or cell-based assays. GingisKHAN™ is highly suited to differentiate between affinity and avidity driven binding of human IgG1 monoclonal and bispecific antibodies during lead identification. PMID:28805498

Ultra-High Temperature Materials Characterization for Space and Missile Applications

NASA Technical Reports Server (NTRS)

Rogers, Jan; Hyers, Robert

2007-01-01

Numerous advanced space and missile technologies including propulsion systems require operations at high temperatures. Some very high-temperature materials are being developed to meet these needs, including refractory metal alloys, carbides, borides, and silicides. System design requires data for materials properties at operating temperatures. Materials property data are not available at the desired operating temperatures for many materials of interest. The objective of this work is to provide important physical property data at ultra-high temperatures. The MSFC Electrostatic Levitation (ESL) facility can provide measurements of thermophysical properties which include: creep strength, emissivity, density and thermal expansion. ESL uses electrostatic fields to position samples between electrodes during processing and characterization experiments. Samples float between the electrodes during studies and are free from any contact with a container or test apparatus. This provides a high purity environment for the study of high-temperature, reactive materials. ESL can be used to process a wide variety of materials including metals, alloys, ceramics, glasses and semiconductors. A system for the determination of total hemispherical emissivity is being developed for the MSFC ESL facility by AZ Technology Inc. The instrument has been designed to provide emissivity measurements for samples during ESL experiments over the temperature range 700-3400K. A novel non-contact technique for the determination of high-temperature creep strength has been developed. Data from selected ESL-based characterization studies will be presented. The ESL technique could advance space and missile technologies by advancing the knowledge base and the technology readiness level for ultra-high temperature materials. Applications include non-eroding nozzle materials and lightweight, high-temperature alloys for turbines and structures.

Effect of adding acid solution on setting time and compressive strength of high calcium fly ash based geopolymer

NASA Astrophysics Data System (ADS)

Antoni, Herianto, Jason Ghorman; Anastasia, Evelin; Hardjito, Djwantoro

2017-09-01

Fly ash with high calcium oxide content when used as the base material in geopolymer concrete could cause flash setting or rapid hardening. However, it might increase the compressive strength of geopolymer concrete. This rapid hardening could cause problems if the geopolymer concrete is used on a large scale casting that requires a long setting time. CaO content can be indicated by pH values of the fly ash, while higher pH is correlated with the rapid setting time of fly ash-based geopolymer. This study investigates the addition of acid solution to reduce the initial pH of the fly ash and to prolong the setting time of the mixture. The acids used in this study are hydrochloric acid (HCl), sulfuric acid (H2 SO4), nitric acid (HNO3) and acetic acid (CH3 COOH). It was found that the addition of acid solution in fly ash was able to decrease the initial pH of fly ash, however, the initial setting time of geopolymer was not reduced. It was even faster than that of the control mixture. The acid type causes various influence, depending on the fly ash properties. In addition, the use of acid solution in fly ash reduces the compressive strength of geopolymer mortar. It is concluded that the addition of acid solution cannot prolong the rapid hardening of high calcium fly ash geopolymer, and it causes adverse effect on the compressive strength.

Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when integrated with advanced EBC top coats, showed promise to achieve 1500 C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and long-term durability.

Study of the structure and properties of metal of the major steam lines of a CCGT-420 unit made from high-chromium X10CrMoVNb9-1 (P91) steel

NASA Astrophysics Data System (ADS)

Grin', E. A.; Anokhov, A. E.; Pchelintsev, A. V.; Krüger, E.-T.

2016-07-01

The technology of manufacture of live steam lines and hot reheat lines at FINOW Rohrsysteme GmbH are discussed. These pipelines are designed for high-performance CCGT units and are made from high-chromium martensitic steel X10CrMoVNb9-1 (P91). The principles of certification and evaluation of conformance of thermal and mechanical equipment made from new construction materials with the TRCU 032-2013 technical regulation of the Customs Union are detailed. The requirements outlined in Russian and international regulatory documents regarding the manufacture of pipes and semifinished products for pipeline systems are compared. The characteristic features of high-chromium martensitic steel, which define the requirements for its heat treatment and welding, are outlined. The methodology and the results of a comprehensive analysis of metal of pipes, fittings, and weld joints of steam lines are presented. It is demonstrated that the short-term mechanical properties of metal (P91 steel) of pipes, bends, and weld joints meet the requirements of European standards and Russian technical specifications. The experimental data on long-term strength of metal of pipes from a live steam line virtually match the corresponding reference curve from the European standard, while certain experimental points for metal of bends of this steam line and metal of pipes and bends from a hot reheat line lie below the reference curve, but they definitely stay within the qualifying (20%) interval of the scatter band. The presence of a weakened layer in the heat-affected zone of weld joints of steel P91 is established. It is shown that the properties of this zone govern the short-term and long-term strength of weld joints in general. The results of synthesis and analysis of research data support the notion that the certification testing of steam lines and other equipment made from chromium steels should necessarily involve the determination of long-term strength parameters.

Micro Environmental Concrete

NASA Astrophysics Data System (ADS)

Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

Soil Transport Implement

NASA Technical Reports Server (NTRS)

Dixon, William; Fan, William; Lloyd, Joey; Pham, Nam-Anh; Stevens, Michael

1988-01-01

The design of the Soil Transport Implement (STI) for SKITTER is presented. The purpose of STI is to provide a protective layer of lunar soil for the lunar modules. The objective is to cover the lunar module with a layer of soil approximately two meters thick within a two week period. The amount of soil required to cover the module is roughly 77 dump truck loads or three million earth pounds. A spinning disk is employed to accomplish its task. STI is an autonomous, teleoperated system. The design incorporates the latest advances in composite materials and high strength, light weight alloys to achieve a high strength to weight ratio. The preliminary design should only be used to assess the feasibility of employing a spinning wheel as a soil transport implement. A mathematical model of the spinning wheel was used to evaluate the performance of this design.

Carbon fibers coated with graphene reinforced TiAl alloy composite with high strength and toughness.

PubMed

Cui, Sen; Cui, Chunxiang; Xie, Jiaqi; Liu, Shuangjin; Shi, Jiejie

2018-02-05

To meet the more rigorous requirement in aerospace industry, recent studies on strengthening and toughening TiAl alloys mostly focus on high Nb addition, which inevitably bring in an increasing of density. In this study, a carbon fibers coated with graphene reinforced TiAl alloy composite was fabricated by powder metallurgy, melt spun and vacuum melting. This composite got remarkable mechanical properties combined with a prominent density reduction. In contrast with pure TiAl ingots, this sample exhibits an average fracture strain from 16% up to 26.27%, and an average strength from 1801 MPa up to 2312 MPa. Thus, we can achieve a new method to fabricate this low-density, good mechanical performance TiAl composite which could bring in more opportunities for application in aerospace industry.

Novel Active Combustion Control Valve

NASA Technical Reports Server (NTRS)

Caspermeyer, Matt

2014-01-01

This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

Influence of PC-GTAW Parameters on the Microstructural and Mechanical Properties of Thin AISI 1008 Steel Joints

NASA Astrophysics Data System (ADS)

Kumar, Ravindra; Anant, Ramkishor; Ghosh, P. K.; Kumar, Ankit; Agrawal, B. P.

2016-09-01

Butt weld joints are prepared using pulse current gas tungsten arc welding out of thin sheets of AISI 1008 steel using various combinations of pulse parameters. During welding, the welding speed was kept high, but with the increase of welding speed the mean current was also increased to get the required weld joint at the constant heat input. The use of pulse current has led to improvement in mechanical and metallurgical properties of weld joints. It has resulted in less development of humping which is a common problem with high-speed welding. The undercut or dipped weld face is not observed severe. The tensile strength and hardness are enhanced by 12.5 and 12%. The increase of tensile strength and hardness is justified through TEM micrograph showing the presence of dislocation.

40 CFR 63.524 - Standards for wet strength resins manufacturers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Standards for wet strength resins... Polyamides Production § 63.524 Standards for wet strength resins manufacturers. (a) Owners or operators of... strength resins produced; or (2) Comply with the requirements of subpart H of this part to control...

40 CFR 63.524 - Standards for wet strength resins manufacturers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards for wet strength resins... Polyamides Production § 63.524 Standards for wet strength resins manufacturers. (a) Owners or operators of... strength resins produced; or (2) Comply with the requirements of subpart H of this part to control...

Nanotwinned metal MEMS films with unprecedented strength and stability

PubMed Central

Sim, Gi-Dong; Krogstad, Jessica A.; Reddy, K. Madhav; Xie, Kelvin Y.; Valentino, Gianna M.; Weihs, Timothy P.; Hemker, Kevin J.

2017-01-01

Silicon-based microelectromechanical systems (MEMS) sensors have become ubiquitous in consumer-based products, but realization of an interconnected network of MEMS devices that allows components to be remotely monitored and controlled, a concept often described as the “Internet of Things,” will require a suite of MEMS materials and properties that are not currently available. We report on the synthesis of metallic nickel-molybdenum-tungsten films with direct current sputter deposition, which results in fully dense crystallographically textured films that are filled with nanotwins. These films exhibit linear elastic mechanical behavior and tensile strengths exceeding 3 GPa, which is unprecedented for materials that are compatible with wafer-level device fabrication processes. The ultrahigh strength is attributed to a combination of solid solution strengthening and the presence of dense nanotwins. These films also have excellent thermal and mechanical stability, high density, and electrical properties that are attractive for next-generation metal MEMS applications. PMID:28782015

[Clinical MR at 3 Tesla: current status].

PubMed

Baudendistel, K T; Heverhagen, J T; Knopp, M V

2004-01-01

Clinical MRI is mostly performed at field strengths up to 1.5 Tesla (T). Recently, approved clinical whole-body MR-systems with a field strength of 3 T became available. Its installation base is more rapidly growing than anticipated. While site requirements and operation of these systems do not differ substantially from systems with lower field strength, there are differences in practical applications. Imaging applications can use the gain in signal-to-noise for increased spatial resolution or gain in speed. This comes at a trade off in increased sensitivity to field inhomogeneities and changes in relaxation times, which lead to changes in image contrast. The benefit of high field for spectroscopy consists in increased signal-to-noise-ratio and improvement in frequency resolution. The increase in energy deposition necessitates the use of special strategies to reduce the specific absorption rate (SAR). This paper summarizes the current state of MR at 3 T.

A Step Made Toward Designing Microelectromechanical System (MEMS) Structures With High Reliability

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.

2003-01-01

The mechanical design of microelectromechanical systems-particularly for micropower generation applications-requires the ability to predict the strength capacity of load-carrying components over the service life of the device. These microdevices, which typically are made of brittle materials such as polysilicon, show wide scatter (stochastic behavior) in strength as well as a different average strength for different sized structures (size effect). These behaviors necessitate either costly and time-consuming trial-and-error designs or, more efficiently, the development of a probabilistic design methodology for MEMS. Over the years, the NASA Glenn Research Center s Life Prediction Branch has developed the CARES/Life probabilistic design methodology to predict the reliability of advanced ceramic components. In this study, done in collaboration with Johns Hopkins University, the ability of the CARES/Life code to predict the reliability of polysilicon microsized structures with stress concentrations is successfully demonstrated.

Fabrication And Evaluation Of Sic/Sic Tubes With Various Fiber Architectures

NASA Technical Reports Server (NTRS)

Yun, H. M.; DiCarlo, J. A.; Fox, D. S.

2003-01-01

SiC/SiC composites are excellent material candidates for high temperature applications where the performance requirements are high strength, high creep-rupture resistance, high environmental durability, and high thermal conductivity. In the past, the NASA UEET program has demonstrated fabrication of high-performance SiC/SiC flat panels reinforced by Sylramic-iBN SiC fibers. Currently NASA UEET is scaling up this SiC/SiC system by fabrication of more complex shaped components using the same fiber type. This paper reports the effects of various fiber architectures on the processing, mechanical, and durability behavior of small-diameter 0.5" ID SiC/SiC tubes, which are potential sub-elements for leading edges and cooling channels in turbine vanes and blades. Nine different fiber architectures were utilized for construction of seamless tube preforms, from simple 2D jelly-rolling to complex braiding, pin-weaving, filament-winding and 3D orthogonal weaving with approximately 5% fibers in the thru-thickness direction. Using the BN interphase and Sic matrix processing steps established for the flat panels, SiC/SiC tubes were fabricated with wall thicknesses of approximately 60 mils and total fiber fractions of approximately 35%. The "D" split ring tests for hoop tensile properties, micro-structural examinations for relationship between fiber architecture formation and matrix infiltration, and the low-pressure burner rig tests for the high temperature durability under thru-thickness thermal gradient were conducted. The better matrix infiltration and higher hoop strength were achieved using the tri-axial braided and the three-float pin woven SiC/SiC tubes. In general, it needs not only higher hoop direction fibers but also axial direction fibers for the higher hoop strength and the better infiltration, respectively. These results are analyzed to offer general guidelines for selecting fiber pre-form architectures and SiC/SiC processes that maximize tube hoop strength, thru-thickness thermal conductivity, and burner-rig durability under a high thermal gradient.

14 CFR 25.651 - Proof of strength.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Surfaces § 25.651 Proof of strength. (a) Limit load tests of control surfaces are required. These tests must include the horn or fitting to which the control system is attached. (b) Compliance with the special factors requirements of...

14 CFR 25.651 - Proof of strength.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Surfaces § 25.651 Proof of strength. (a) Limit load tests of control surfaces are required. These tests must include the horn or fitting to which the control system is attached. (b) Compliance with the special factors requirements of...

14 CFR 25.651 - Proof of strength.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Surfaces § 25.651 Proof of strength. (a) Limit load tests of control surfaces are required. These tests must include the horn or fitting to which the control system is attached. (b) Compliance with the special factors requirements of...

14 CFR 25.651 - Proof of strength.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Surfaces § 25.651 Proof of strength. (a) Limit load tests of control surfaces are required. These tests must include the horn or fitting to which the control system is attached. (b) Compliance with the special factors requirements of...

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

PubMed Central

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-01-01

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction. PMID:28787809

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products.

PubMed

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-12-25

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete's water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

Hydration Effects on Human Physiology and Exercise-Heat Performance

DTIC Science & Technology

1989-11-01

lifter and marathon runner are all dissimilar. Some of these activities require primarily anaerobic metabolism and skeletal muscle strength, whereas...require aerobic metabolism and that are prolonged will1 more likely be adversely influenced by hypohydration than exercilse tasks that require anaerobic ...hypohydration on muscular strength and endurance as well as anaerobic performance (114). Table 4. Summary of studies investigating the influence of

Special Inspector General for Afghanistan Reconstruction (SIGAR). Supplement

DTIC Science & Technology

2015-01-30

Some information concerning corps-level ANSF personnel strength data, future requirements for Afghan Air Force (AAF) equipment, the number of trained...to press. SIGAR has published an unclassified Quarterly Report to Congress since 2008, as required by our authorizing statute. On January 30, 2015...based on the declassified materials provided. Some information con- cerning corps level ANSF personnel strength data, future requirements for Afghan Air

THE FUEL ELEMENT GRAPHITE. Project DRAGON.

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

Graham, L.W.; Price, M.S.T.

1963-01-15

The main requirements of a fuel element graphite for reactors based on the Dragon concept are low transmission coefficient for fission products, dimensional stability under service conditions, high strength, high thermal conductivity, high purity, and high resistance to oxidation. Since conclusions reached in early 1960, a considerable amount of information has accumulated concerning the likely behaviour of graphites in high temperature reactor systems, particularly data on dimensional stability under irradiation. The influence of this new knowledge on the development of fuel element graphite with the Dragon Project is discussed in detail in the final section of this paper.

Effects of exercise improves muscle strength and fat mass in patients with high fracture risk: A randomized control trial.

PubMed

Chan, Ding-Cheng; Chang, Chirn-Bin; Han, Der-Sheng; Hong, Cian-Hui; Hwang, Jawl-Shan; Tsai, Keh-Sung; Yang, Rong-Sen

2017-10-26

The deterioration of the musculoskeletal system imposes significant impact on physical activity. Exercise is an important strategy which minimizes these changes. It is not clear which type of exercise provides better improvement on low physical performance, low muscle mass and low strength of sarcopenia. We aim to develop an integrated care (IC) model and compare its relative efficacy in limb fat free mass, muscle strength, and physical performance with low extremities exercise (LEE) in community dwelling older adults with high risk of fractures (Fracture Risk Assessment Tool (FRAX ® )) ≧3% for hip fracture, ≧20% for major osteoporotic fracture or 1-min osteoporosis risk test (≧1 point) or fall (≧2 falls in previous year). Patients were assigned randomized to participate in either IC or LEE group (n = 55 each) for 3 months. All participants received education including home-based exercise. The IC group consisted of different modalities of exercise while the LEE group performed machine-based low extremities exercise. Fat free mass, muscle strength, and physical performance were measured at their baseline and 3-months follow-up. Mean age was 73.8 ± 7 years with 69.1% women. Entire cohort demonstrated significant increment in fat free mass, muscle strength (4 indicators) and physical performance (3 indicators). However, between group differences were not significant. With regular supervise exercise; both groups are equally effective in decreasing fat mass and increasing physical performance, muscle mass and strength. However, the IC group required fewer resources and thus more financially feasible in a community setting. Copyright © 2017. Published by Elsevier B.V.

Engineering and fabrication cost considerations for cryogenic wind tunnel models

NASA Technical Reports Server (NTRS)

Boykin, R. M., Jr.; Davenport, J. B., Jr.

1983-01-01

Design and fabrication cost drivers for cryogenic transonic wind tunnel models are defined. The major cost factors for wind tunnel models are model complexity, tolerances, surface finishes, materials, material validation, and model inspection. The cryogenic temperatures require the use of materials with relatively high fracture toughness but at the same time high strength. Some of these materials are very difficult to machine, requiring extensive machine hours which can add significantly to the manufacturing costs. Some additional engineering costs are incurred to certify the materials through mechanical tests and nondestructive evaluation techniques, which are not normally required with conventional models. When instrumentation such as accelerometers and electronically scanned pressure modules is required, temperature control of these devices needs to be incorporated into the design, which requires added effort. Additional thermal analyses and subsystem tests may be necessary, which also adds to the design costs. The largest driver to the design costs is potentially the additional static and dynamic analyses required to insure structural integrity of the model and support system.

Increasing the strength and bioactivity of collagen scaffolds using customizable arrays of 3D-printed polymer fibers.

PubMed

Mozdzen, Laura C; Rodgers, Ryan; Banks, Jessica M; Bailey, Ryan C; Harley, Brendan A C

2016-03-01

Tendon is a highly aligned connective tissue which transmits force from muscle to bone. Each year, people in the US sustain more than 32 million tendon injuries. To mitigate poor functional outcomes due to scar formation, current surgical techniques rely heavily on autografts. Biomaterial platforms and tissue engineering methods offer an alternative approach to address these injuries. Scaffolds incorporating aligned structural features can promote expansion of adult tenocytes and mesenchymal stem cells capable of tenogenic differentiation. However, appropriate balance between scaffold bioactivity and mechanical strength of these constructs remains challenging. The high porosity required to facilitate cell infiltration, nutrient and oxygen biotransport within three-dimensional constructs typically results in insufficient biomechanical strength. Here we describe the use of three-dimensional printing techniques to create customizable arrays of acrylonitrile butadiene styrene (ABS) fibers that can be incorporated into a collagen scaffold under development for tendon repair. Notably, mechanical performance of scaffold-fiber composites (elastic modulus, peak stress, strain at peak stress, and toughness) can be selectively manipulated by varying fiber-reinforcement geometry without affecting the native bioactivity of the collagen scaffold. Further, we report an approach to functionalize ABS fibers with activity-inducing growth factors via sequential oxygen plasma and carbodiimide crosslinking treatments. Together, we report an adaptable approach to control both mechanical strength and presence of biomolecular cues in a manner orthogonal to the architecture of the collagen scaffold itself. Tendon injuries account for more than 32 million injuries each year in the US alone. Current techniques use allografts to mitigate poor functional outcomes, but are not ideal platforms to induce functional regeneration following injury. Tissue engineering approaches using biomaterial substrates have significant potential for addressing these defects. However, the high porosity required to facilitate cell infiltration and nutrient transport often dictates that the resultant biomaterials has insufficient biomechanical strength. Here we describe the use of three-dimensional printing techniques to generate customizable fiber arrays from ABS polymer that can be incorporated into a collagen scaffold under development for tendon repair applications. Notably, the mechanical performance of the fiber-scaffold composite can be defined by the fiber array independent of the bioactivity of the collagen scaffold design. Further, the fiber array provides a substrate for growth factor delivery to aid healing. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Musculoskeletal phenotype through the life course: the role of nutrition.

PubMed

Ward, Kate

2012-02-01

This review considers the definition of a healthy bone phenotype through the life course and the modulating effects of muscle function and nutrition. In particular, it will emphasise that optimal bone strength (and how that is regulated) is more important than simple measures of bone mass. The forces imposed on bone by muscle loading are the primary determinants of musculoskeletal health. Any factor that changes muscle loading on the bone, or the response of bone to loading results in alterations of bone strength. Advances in technology have enhanced the understanding of a healthy bone phenotype in different skeletal compartments. Multiple components of muscle strength can also be quantified. The critical evaluation of emerging technologies for assessment of bone and muscle phenotype is vital. Populations with low and moderate/high daily Ca intakes and/or different vitamin D status illustrate the importance of nutrition in determining musculoskeletal phenotype. Changes in mass and architecture maintain strength despite low Ca intake or vitamin D status. There is a complex interaction between body fat and bone which, in addition to protein intake, is emerging as a key area of research. Muscle and bone should be considered as an integrative unit; the role of body fat requires definition. There remains a lack of longitudinal evidence to understand how nutrition and lifestyle define musculoskeletal health. In conclusion, a life-course approach is required to understand the definition of healthy skeletal phenotype in different populations and at different stages of life.

An Atom Probe Tomographic Investigation of High-Strength, High-Toughness Precipitation Strengthened Steels for Naval Applications

NASA Astrophysics Data System (ADS)

Hunter, Allen H.

Novel high-strength high-toughness alloys strengthened by precipitation are investigated for use in naval applications. The mechanical properties of an experimental steel alloy, NUCu-140, are evaluated and are not suitable for the naval requirements due to poor impact toughness at -40°C. An investigation is conducted to determine optimum processing conditions to restore toughness. A detailed aging study is conducted at 450, 500, and 550°C to determine the evolution of the microstructure and mechanical properties. A combination of transmission electron microscopy (TEM), synchrotron X-ray Diffraction (XRD), and Local electrode atom probe (LEAP) tomography are used to measure the evolution of the Cu precipitates, austenite, NbC, and cementite phases during aging. The evolution of the Cu precipitates significantly affects the yield strength of the steel, but low temperature toughness is controlled by the cementite precipitates. Extended aging is effective at improving the impact toughness but the yield strength is also decreased due to coarsening of the Cu precipitates. To provide a foundation for successful welding of NUCu-140 steel, an investigation of the effects of gas metal arc welding (GMAW) are performed. The microstructures in the base metal (BM), heat affected zone (HAZ), and fusion zone (FZ) of a GMAW sample are analyzed to determine the effects of the welding thermal cycle. Weld simulation samples with known thermal histories are prepared and analyzed by XRD and LEAP tomography. A significant loss in microhardness is observed as a result of dissolution of the Cu precipitates after the weld thermal cycle. The cooling time is too rapid to allow significant precipitation of Cu. In addition to the NUCu-140 alloy, a production HSLA-115 steel alloy is investigated using TEM, XRD, and LEAP tomography. The strength of the HSLA-115 is found to be derived primarily from Cu precipitates. The volume fractions of cementite, austenite, and NbC are measured by XRD. Austenite precipitates are observed at martensite lath boundaries using TEM.

Measures of Strength and Fitness for Older Populations.

ERIC Educational Resources Information Center

Osness, Wayne H.; Hiebert, Lujean M.

The overall strength of the musculature does not require testing of large numbers of muscle groups and can be accomplished from three or four tests. Small batteries of strength tests have been devised to predict total strength. The best combination of tests for males are thigh flexors, leg extensors, arm flexors, and pectoralis major. The battery…

Unravel the key genes potentially related to high strength of cotton fiber by comparative phenotypic and genomic analyses

USDA-ARS?s Scientific Manuscript database

The demand of high strength of cotton fibers has been increased dramatically with the advent of modern high speed spinning technology for producing yarn. Bundle fiber strength is affected by fiber-to-fiber interactions in addition to the individual fiber strength. The bundle fiber strength is not al...

Molybdenum-base cermet fuel development

NASA Astrophysics Data System (ADS)

Pilger, James P.; Gurwell, William E.; Moss, Ronald W.; White, George D.; Seifert, David A.

Development of a multimegawatt (MMW) space nuclear power system requires identification and resolution of several technical feasibility issues before selecting one or more promising system concepts. Demonstration of reactor fuel fabrication technology is required for cermet-fueled reactor concepts. The MMW reactor fuel development activity at Pacific Northwest Laboratory (PNL) is focused on producing a molybdenum-matrix uranium-nitride (UN) fueled cermte. This cermet is to have a high matrix density (greater than or equal to 95 percent) for high strength and high thermal conductance coupled with a high particle (UN) porosity (approximately 25 percent) for retention of released fission gas at high burnup. Fabrication process development involves the use of porous TiN microspheres as surrogate fuel material until porous Un microspheres become available. Process development was conducted in the areas of microsphere synthesis, particle sealing/coating, and high-energy-rate forming (HERF) and the vacuum hot press consolidation techniques. This paper summarizes the status of these activities.

Effect of cooling rate during hot stamping on low cyclic fatigue of boron steel sheet

NASA Astrophysics Data System (ADS)

Suh, Chang Hee; Jang, Won Seok; Oh, Sang Kyun; Lee, Rac Gyu; Jung, Yun-Chul; Kim, Young Suk

2012-08-01

Boron steel is widely used throughout the automobile industry due to its high tensile strength and hardenability. When boron steel is used for body parts, only high strength is required for crashworthiness. However, when boron steel is used for chassis parts, a high fatigue life is needed. The microstructure of boron steel is mainly affected by the cooling rate during hot stamping. Therefore, this study investigated the low cyclic fatigue life according to the cooling rate. The fatigue life increased at a low strain amplitude when the cooling rate was fast. However, at a high strain amplitude, the fatigue life decreased, due to the low ductility and fracture toughness of the martensite formed by rapid cooling. Martensite formed by a fast cooling rate shows excellent fatigue life at a low total strain amplitude; however, a multiphase microstructure formed by a slow cooling rate is recommended if the parts experience high and low total strain amplitudes alternately. In addition, the cooling rate has little effect on the distribution of solute boron and boron precipitations, so it is expected that boron rarely affects low cyclic fatigue.

Phase I: Evaluation of Low Flexural Strength for Northern Nevada Concrete Paving Mixtures

DOT National Transportation Integrated Search

2017-07-01

Production paving grade concrete in Northern Nevada having acceptable strength is universally acknowledged to be difficult; however understanding why this is true remains elusive. Current practice is to meet flexural strength requirements by using mi...

One-dimensional polaritons with size-tunable and enhanced coupling strengths in semiconductor nanowires.

PubMed

van Vugt, Lambert K; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh

2011-06-21

Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk.

One-dimensional polaritons with size-tunable and enhanced coupling strengths in semiconductor nanowires

PubMed Central

van Vugt, Lambert K.; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh

2011-01-01

Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk. PMID:21628582

Influence of Bond Coat on HVOF-Sprayed Gradient Cermet Coating on Copper Alloy

NASA Astrophysics Data System (ADS)

Ke, Peng; Cai, Fei; Chen, Wanglin; Wang, Shuoyu; Ni, Zhenhang; Hu, Xiaohong; Li, Mingxi; Zhu, Guanghong; Zhang, Shihong

2017-06-01

Coatings are required on mold copper plates to prolong their service life through enhanced hardness, wear resistance, and oxidation resistance. In the present study, NiCr-30 wt.%Cr3C2 ceramic-metallic (cermet) layers were deposited by high velocity oxy-fuel (HVOF) spraying on different designed bond layers, including electroplated Ni, HVOF-sprayed NiCr, and double-decker Ni-NiCr. Annealing was also conducted on the gradient coating (GC) with NiCr bond layer to improve the wear resistance and adhesion strength. Coating microstructure was investigated by scanning electron microscopy and x-ray diffraction analysis. Mechanical properties including microhardness, wear resistance, and adhesion strength of the different coatings were evaluated systematically. The results show that the types of metallic bond layer and annealing process had a significant impact on the mechanical properties of the GCs. The GCs with electroplated Ni bond layer exhibited the highest adhesion strength (about 70 MPa). However, the GC with HVOF-sprayed NiCr bond layer exhibited better wear resistance. The wear resistance and adhesion strength of the coating with NiCr metallic bond layer were enhanced after annealing.

"Brick-and-Mortar" Nanostructured Interphase for Glass-Fiber-Reinforced Polymer Composites.

PubMed

De Luca, Francois; Sernicola, Giorgio; Shaffer, Milo S P; Bismarck, Alexander

2018-02-28

The fiber-matrix interface plays a critical role in determining composite mechanical properties. While a strong interface tends to provide high strength, a weak interface enables extensive debonding, leading to a high degree of energy absorption. Balancing these conflicting requirements by engineering composite interfaces to improve strength and toughness simultaneously still remains a great challenge. Here, a nanostructured fiber coating was realized to manifest the critical characteristics of natural nacre, at a reduced length scale, consistent with the surface curvature of fibers. The new interphase contains a high proportion (∼90 wt %) of well-aligned inorganic platelets embedded in a polymer; the window of suitable platelet dimensions is very narrow, with an optimized platelet width and thickness of about 130 and 13 nm, respectively. An anisotropic, nanostructured coating was uniformly and conformally deposited onto a large number of 9 μm diameter glass fibers, simultaneously, using self-limiting layer-by-layer assembly (LbL); this parallel approach demonstrates a promising strategy to exploit LbL methods at scale. The resulting nanocomposite interphase, primarily loaded in shear, provides new mechanisms for stress dissipation and plastic deformation. The energy released by fiber breakage in tension appear to spread and dissipate within the nanostructured interphase, accompanied by stable fiber slippage, while the interfacial strength was improved up to 30%.

Modeling and experiments on the drive characteristics of high-strength water hydraulic artificial muscles

NASA Astrophysics Data System (ADS)

Zhang, Zengmeng; Hou, Jiaoyi; Ning, Dayong; Gong, Xiaofeng; Gong, Yongjun

2017-05-01

Fluidic artificial muscles are popular in robotics and function as biomimetic actuators. Their pneumatic version has been widely investigated. A novel water hydraulic artificial muscle (WHAM) with high strength is developed in this study. WHAMs can be applied to underwater manipulators widely used in ocean development because of their environment-friendly characteristics, high force-to-weight ratio, and good bio-imitability. Therefore, the strength of WHAMs has been improved to fit the requirements of underwater environments and the work pressure of water hydraulic components. However, understanding the mechanical behaviors of WHAMs is necessary because WHAMs use work media and pressure control that are different from those used by pneumatic artificial muscles. This paper presents the static and dynamic characteristics of the WHAM system, including the water hydraulic pressure control circuit. A test system is designed and built to analyze the drive characteristics of the developed WHAM. The theoretical relationships among the amount of contraction, pressure, and output drawing force of the WHAM are tested and verified. A linearized transfer function is proposed, and the dynamic characteristics of the WHAM are investigated through simulation and inertia load experiments. Simulation results agree with the experimental results and show that the proposed model can be applied to the control of WHAM actuators.

Material Interactions in a Novel Pinless Tool Approach to Friction Stir Spot Welding Thin Aluminum Sheet

NASA Astrophysics Data System (ADS)

Bakavos, Dimitrios; Chen, Yingchun; Babout, Laurent; Prangnell, Phil

2011-05-01

The requirement for a probe, or pin, in friction stir spot welding (FSSW) leads to an undesirable keyhole and "hooking," which can influence the fracture path and weld strength. Furthermore, the full weld cycle for FSSW is typically longer than ideal for the automotive industry, being 2 to 5 seconds. Here, it is shown that using a novel pinless tool design it is possible to achieve high lap shear strength (~3.4 kN) in thin aluminum sheet (~1 mm thick), with short weld cycle times (<1 second). Several techniques have been exploited to study the material flow and mechanisms of weld formation in pinless FSSW, including high-resolution X-ray tomography, to understand the role of the tool design and weld parameters. Despite the "simple" nature of a pinless tool, material flow in the weld zone was found to be surprisingly complex and strongly influenced by surface features on the tool, which greatly increased the penetration of the plastic zone into the bottom sheet. Because of the rapid thermal cycle and high level of grain refinement, the weld zone was found to develop a higher strength than the parent material with little evidence of a heat affected zone (HAZ) after postweld natural aging.

Effects of using blended binder of RHA and GGBS on the properties of concrete: A review

NASA Astrophysics Data System (ADS)

Ishak, Nuril Izzeaty; Johari, Megat Azmi Megat; Hashim, Syed Fuad Saiyid

2017-10-01

Concern about protecting and preserving the environment has driven many researchers to innovate the concrete materials in pursuing better mechanical and physical properties of the fresh and hardened concrete. This paper presents an overview of the microstructural properties, workability, and strength performance of concrete incorporated with mineral admixtures from rice husk ash (RHA) and ground granulated blast-furnace slag (GGBS). The substitution of these supplementary cementitious materials as a ternary blended binder concrete has also been included. It was found that, the average of RHA replacement in concrete is about 10%, while for GGBS is in the range of 40 to 50 % replacement of Portland cement. The results from previous studies yield to a better strength and could potentially be used as high performance concrete, but the high replacement with RHA decreased workability and required more water demand due to the micro porous character, high specific surface area and higher in carbon content of the material. Thus, the necessity of using superlasticizer is crucial to improve the workability and strength. The collection of comprehensive literatures elaborated that the usage of RHA and GGBS enhanced the properties of concrete while gives a better solution for the plenteous of waste produced from the agricultural and industrial sectors.

Bioresorbable Ca-phosphate-polymer/metal and Fe-Ag nanocomposites for macro-porous scaffolds with tunable degradation and drug release

NASA Astrophysics Data System (ADS)

Gotman, I.; Swain, S. K.; Sharipova, A.; Gutmanas, E. Y.

2016-11-01

Bioresorbable implants are increasingly gaining popularity as an attractive alternative to traditional permanent bone healing devices. The advantage of bioresorbable implantable devices is that they slowly degrade over time and disappear once their "mission" is accomplished. Thus, no foreign material is left behind that can cause adverse effects on the host, such as long term local or systemic immune response and stress-shielding related bone atrophy. Resorbable materials considered for surgical implant applications include degradable polymers, Ca phosphate ceramics (CaP) and corrodible metals. Degradable polymers, such as polycaprolactone and lactic acid are weak, lack osteoconductivity and degrade to acidic products that can cause late inflammation. Resorbable CaP ceramics (e.g., β-TCP) are attractive materials for bone regeneration bear close resemblance to the bone mineral, however they are intrinsically brittle and thus unsuitable for use in load-bearing sites. Moreover, introducing high porosity required to encourage better cellular ingrowth into bone regeneration scaffolds is detrimental to the mechanical strength of the material. In present work we review and discuss our results on development of strong bioresorbable Ca-phosphate-polymer/metal nanonocomposites and highly porous scaffolds from them. By introduction of nanoscale ductile polymer or metal phase into CaP ceramic an attempt was made to mimic structure of natural bone, where nanocrystallites of CaP ceramic are bonded by thin collagen layers. Recent results on development of high strength scaffolds from Fe-Ag nanocomposites are also reported. High energy milling of powders followed by cold sintering—high pressure consolidation at ambient temperature in combination with modified porogen leaching method was employed for processing. The developed nanocomposites and scaffolds exhibited high mechanical strength coupled with measurable ductility, gradual lost weight and strength during immersion in physiological media and high permeability falling in the range of trabecular bone. The proposed low-temperature processing approach allows for incorporation of drugs into the residual nanopores without damaging the biomolecule activity.

Thermostructural Properties Of Sic/Sic Panels With 2.5d And 3d Fiber Architectures

NASA Technical Reports Server (NTRS)

Yun, H. M.; DeCarlo, J. A.; Bhatt, R. H.; Jaskowiak, M. H.

2005-01-01

CMC hot-section components in advanced engines for power and propulsion will typically require high cracking strength, high ultimate strength and strain, high creep- rupture resistance, and high thermal conductivity in all directions. In the past, NASA has demonstrated fabrication of a variety of SiC/SiC flat panels and round tubes with various 2D fiber architectures using the high-modulus high-performance Sylramic-iBN Sic fiber and Sic-based matrices derived by CVI, MI, and/or PIP processes. The thermo- mechanical properties of these CMC have shown state-of-the-art performance, but primarily in the in-plane directions. Currently NASA is extending the thermostructural capability of these SiC/SiC systems in the thru-thickness direction by using various 2.5D and 3D fiber architectures. NASA is also using specially designed fabrication steps to optimize the properties of the BN-based interphase and Sic-based matrices. In this study, Sylramic-iBN/SiC panels with 2D plain weave, 2.5D satin weave, 2.5D ply-to-ply interlock weave, and 3D angle interlock fiber architectures, all woven at AITI, were fabricated using matrix densification routes previously established between NASA and GEPSC for CVI-MI processes and between NASA and Starfire-Systems for PIP processes. Introduction of the 2.5 D fiber architecture along with an improved matrix process was found to increase inter-laminar tensile strength from 1.5 -2 to 3 - 4 ksi and thru-thickness thermal conductivity from 15-20 to 30-35 BTU/ft.hr.F with minimal reduction in in-plane strength and creep-rupture properties. Such improvements should reduce thermal stresses and increase the thermostructural operating envelope for SiC/SiC engine components. These results are analyzed to offer general guidelines for selecting fiber architectures and constituent processes for high-performance SiC/SiC engine components.

Cycle training induces muscle hypertrophy and strength gain: strategies and mechanisms.

PubMed

Ozaki, Hayao; Loenneke, J P; Thiebaud, R S; Abe, T

2015-03-01

Cycle training is widely performed as a major part of any exercise program seeking to improve aerobic capacity and cardiovascular health. However, the effect of cycle training on muscle size and strength gain still requires further insight, even though it is known that professional cyclists display larger muscle size compared to controls. Therefore, the purpose of this review is to discuss the effects of cycle training on muscle size and strength of the lower extremity and the possible mechanisms for increasing muscle size with cycle training. It is plausible that cycle training requires a longer period to significantly increase muscle size compared to typical resistance training due to a much slower hypertrophy rate. Cycle training induces muscle hypertrophy similarly between young and older age groups, while strength gain seems to favor older adults, which suggests that the probability for improving in muscle quality appears to be higher in older adults compared to young adults. For young adults, higher-intensity intermittent cycling may be required to achieve strength gains. It also appears that muscle hypertrophy induced by cycle training results from the positive changes in muscle protein net balance.

The Effect of Baggase Ash on Fly Ash-Based Geopolimer Binder

NASA Astrophysics Data System (ADS)

Bayuaji, R.; Darmawan, M. S.; Husin, N. A.; Banugraha, R.; Alfi, M.; Abdullah, M. M. A. B.

2018-06-01

Geopolymer concrete is an environmentally friendly concrete. However, the geopolymer binder has a problem with setting time; mainly the composition comprises high calcium fly ash. This study utilized bagasse ash to improve setting time on fly ash-based geopolymer binder. The characterization of bagasse ash was carried out by using chemical and phase analysis, while the morphology characterization was examined by scanning electron microscope (SEM). The setting time test and the compressive strength test used standard ASTM C 191-04 and ASTM C39 / C39M respectively. The compressive strength of the samples determined at 3, 28 and 56 days. The result compared the requirement of the standards.

A Comprehensive Solution of the Problems of Ensuring the Strength of Gas Turbine Engine Compressor at the Design Stage

NASA Astrophysics Data System (ADS)

Vedeneev, V. V.; Kolotnikov, M. E.; Mossakovskii, P. A.; Kostyreva, L. A.; Abdukhakimov, F. A.; Makarov, P. V.; Pyhalov, A. A.; Dudaev, M. A.

2018-01-01

In this paper we present a complex numerical workflow for analysis of blade flutter and high-amplitude resonant oscillations, impenetrability of casing if the blade is broken off, and the rotor reaction to the blade detachment and following misbalance, with the assessment of a safe flight possibility at the auto-rotation regime. All the methods used are carefully verified by numerical convergence study and correlations with experiments. The use of the workflow developed significantly improves the efficiency of the design process of modern jet engine compressors. It ensures a significant reduction of time and cost of the compressor design with the required level of strength and durability.

Flywheel rotor and containment technology development for FY 1982

NASA Astrophysics Data System (ADS)

Kulkarni, S. V.

1982-12-01

The status of technology development for an efficient, economical, and practical composite flywheel having an energy density of 88 Wh/kg (20 to 25 E Wh/lb) and an energy storge capacity of approximately 1 kWh is reported. Progress is also reported in the development of a fail-safe, lightweight, and low cost composite containment for the flywheel. One containment design was selected for prototype fabrication and testing. Flywheel rotor cyclic test capability was also demonstrated and evaluated. High strength Kevlar and graphite fibers are being studied. Tests of the elastomeric bond between the rotor and hub indicate that the bond strength exceeds the minimum torque requirements for automobile applications.

Image Analysis and Classification Based on Soil Strength

DTIC Science & Technology

2016-08-01

Satellite imagery classification is useful for a variety of commonly used ap- plications, such as land use classification, agriculture , wetland...required use of a coinci- dent digital elevation model (DEM) and a high-resolution orthophoto- graph collected by the National Agriculture Imagery Program...14. ABSTRACT Satellite imagery classification is useful for a variety of commonly used applications, such as land use classification, agriculture

High Reliability Prototype Quadrupole for the Next Linear Collider

NASA Astrophysics Data System (ADS)

Spencer, C. M.

2001-01-01

The Next Linear Collider (NLC) will require over 5600 magnets, each of which must be highly reliable and/or quickly repairable in order that the NLC reach its 85/ overall availability goal. A multidiscipline engineering team was assembled at SLAC to develop a more reliable electromagnet design than historically had been achieved at SLAC. This team carried out a Failure Mode and Effects Analysis (FMEA) on a standard SLAC quadrupole magnet system. They overcame a number of longstanding design prejudices, producing 10 major design changes. This paper describes how a prototype magnet was constructed and the extensive testing carried out on it to prove full functionality with an improvement in reliability. The magnet's fabrication cost will be compared to the cost of a magnet with the same requirements made in the historic SLAC way. The NLC will use over 1600 of these 12.7 mm bore quadrupoles with a range of integrated strengths from 0.6 to 132 Tesla, a maximum gradient of 135 Tesla per meter, an adjustment range of 0 to -20/ and core lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micron during the 20/ adjustment. A magnetic measurement set-up has been developed that can measure sub-micron shifts of a magnetic center. The prototype satisfied the center shift requirement over the full range of integrated strengths.

Durability and Life of Ceramic Matrix Composites in Combustion Environment

NASA Technical Reports Server (NTRS)

Tewari, Surendra

1997-01-01

It is now generally recognized that the next frontier in the commercial air travel will be achieved by an optimum combination of the concepts being used for the air and space transports. It will depend upon the new engines specifically designed to meet the demanding strength, temperature, environment and economy requirements. The successful development of an advanced propulsion system for a 21st Century High Speed Civil Transport will require key advances in the combustor system. Minimizing nitrous oxide (NO(x)) emission is critical, since the deleterious interaction within the ozone layer would occur at the proposed vehicle cruise level of about 75,000 feet. In order to achieve the low NOx levels an efficient combustor operating at controlled equivalence ratios and high combustion temperatures are required. This requires a combustor, whose one portion will be operating in an oxidizing environment while the other portion will operate in a reducing environment. This rather unusual requirement has introduced considerable challenge to the materials scientists and engineers, the development of material systems capable of long-life at high temperatures (up to 3000 F) in an oxidizing and/or reducing environment.

Overdose of Rogaine Extra Strength for Men topical minoxidil preparation.

PubMed

Farrell, S E; Epstein, S K

1999-01-01

Minoxidil is a potent arterial vasodilator used in the treatment of hypertension. A side effect, hypertrichosis, has prompted the marketing of a topical preparation, Rogaine, for the treatment of male-pattern baldness. Recently, a 5% solution of minoxidil became available over-the-counter as Rogaine Extra Strength For Men Hair Regrowth Treatment. We describe an oral overdose of minoxidil 3 g as the Rogaine Extra Strength preparation. Toxicity manifested as profound hypotension, requiring vasopressor support, intubation, prolonged tachycardia, and fluid overload with pleural effusions, requiring several days of therapy with furosemide. This is the largest reported ingestion of minoxidil and the first reported overdose of the extra strength 5% solution.

Materials Research for High Speed Civil Transport and Generic Hypersonics-Metals Durability

NASA Technical Reports Server (NTRS)

Schulz, Paul; Hoffman, Daniel

1996-01-01

This report covers a portion of an ongoing investigation of the durability of titanium alloys for the High Speed Civil Transport (HSCT). Candidate alloys need to possess an acceptable combination of properties including strength and toughness as well as fatigue and corrosion resistance when subjected to the HSCT operational environment. These materials must also be capable of being processed into required product forms while maintaining their properties. Processing operations being considered for this airplane include forming, welding, adhesive bonding, and superplastic forming with or without diffusion bonding. This program was designed to develop the material properties database required to lower the risk of using advanced titanium alloys on the HSCT.

Measurement of the mechanical properties of car body sheet steels at high strain rates and non ambient temperature

NASA Astrophysics Data System (ADS)

Bleck, W.; Larour, P.

2003-09-01

Crash behaviour and light weight have become the major design criteria for car bodies. Modem high strength steels offer appropriate solutions for these requirements. The prediction of the crash behaviour in simulation programs requires the information on materials behaviour during dynamic testing. The reduction of the signal waviness and the inertia effects at strain rates above 50s^{-1} are major issues in dynamic tensile testing. Damping techniques or load measurement on the sample itself are the common way to reduce oscillations. Strain measurement from the piston displacement or from optical devices on the specimen itself are also compared. Advantages and drawbacks of those various measurement techniques are presented.

The flexural properties of endodontic post materials.

PubMed

Stewardson, Dominic A; Shortall, Adrian C; Marquis, Peter M; Lumley, Philip J

2010-08-01

To measure the flexural strengths and moduli of endodontic post materials and to assess the effect on the calculated flexural properties of varying the diameter/length (D/L) ratio of three-point bend test samples. Three-point bend testing of samples of 2mm diameter metal and fiber-reinforced composite (FRC) rods was carried out and the mechanical properties calculated at support widths of 16 mm, 32 mm and 64 mm. Weibull analysis was performed on the strength data. The flexural strengths of all the FRC post materials exceeded the yield strengths of the gold and stainless steel samples; the flexural strengths of two FRC materials were comparable with the yield strength of titanium. Stainless steel recorded the highest flexural modulus while the titanium and the two carbon fiber materials exhibited similar values just exceeding that of gold. The remaining glass fiber materials were of lower modulus within the range of 41-57 GPa. Weibull modulus values for the FRC materials ranged from 16.77 to 30.09. Decreasing the L/D ratio produced a marked decrease in flexural modulus for all materials. The flexural strengths of FRC endodontic post materials as new generally exceed the yield strengths of metals from which endodontic posts are made. The high Weibull modulus values suggest good clinical reliability of FRC posts. The flexural modulus values of the tested posts were from 2-6 times (FRC) to 4-10 times (metal) that of dentin. Valid measurement of flexural properties of endodontic post materials requires that test samples have appropriate L/D ratios. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

An in vitro study to compare the transverse strength of thermopressed and conventional compression-molded polymethylmethacrylate polymers.

PubMed

Raut, Anjana; Rao, Polsani Laxman; Vikas, B V J; Ravindranath, T; Paradkar, Archana; Malakondaiah, G

2013-01-01

Acrylic resins have been in the center stage of Prosthodontics for more than half a century. The flexural fatigue failure of denture base materials is the primary mode of clinical failure. Hence there is a need for superior physical and mechanical properties. This in vitro study compared the transverse strength of specimens of thermopressed injection-molded and conventional compression-molded polymethylmethacrylate polymers and examined the morphology and microstructure of fractured acrylic specimens. The following denture base resins were examined: Brecrystal (Thermopressed injection-molded, modified polymethylmethacrylate) and Pyrax (compression molded, control group). Specimens of each material were tested according to the American Society for Testing and Materials standard D790-03 for flexural strength testing of reinforced plastics and subsequently examined under SEM. The data was analyzed with Student unpaired t test. Flexural strength of Brecrystal (82.08 ± 1.27 MPa) was significantly higher than Pyrax (72.76 ± 0.97 MPa). The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa). The scanning electron microscopy image of Brecrystal revealed a ductile fracture with crazing. The fracture pattern of control group specimens exhibited poorly defined crystallographic planes with a high degree of disorganization. Flexural strength of Brecrystal was significantly higher than the control group. Brecrystal showed a higher mean transverse strength value of 82.08 ± 1.27 MPa and a more homogenous pattern at microscopic level. Based on flexural strength properties and handling characteristics, Brecrystal may prove to be an useful alternative to conventional denture base resins.

Review on fatigue behavior of high-strength concrete after high temperature

NASA Astrophysics Data System (ADS)

Zhao, Dongfu; Jia, Penghe; Gao, Haijing

2017-06-01

The fatigue of high-strength concrete after high temperature has begun to attract attention. But so far the researches work about the fatigue of high-strength concrete after high temperature have not been reported. This article based on a large number of literature. The research work about the fatigue of high-strength concrete after high temperature are reviewed, analysed and expected, which can provide some reference for the experimental study of fatigue damage analysis.

Jet formation in cerium metal to examine material strength

DOE PAGES

Jensen, B. J.; Cherne, F. J.; Prime, M. B.; ...

2015-11-18

Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Some recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solidmore » phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. And from these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. Finally, the data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.« less

Nanofiber reinforcement of a geopolymer matrix for improved composite materials mechanical performance

NASA Astrophysics Data System (ADS)

Rahman, AKM Samsur

Geopolymers have the potential to cross the process performance gap between polymer matrix and ceramic matrix composites (CMC), enabling high temperature capable composites that are manufactured at relatively low temperatures. Unfortunately, the inherently low toughness of these geopolymers limits the performance of the resulting fiber reinforced geopolymer matrix composites. Toughness improvements in composites can be addressed through the adjustments in the fiber/matrix interfacial strength and through the improvements in the inherent toughness of the constituent materials. This study investigates the potential to improve the inherent toughness of the geopolymer matrix material through the addition of nanofillers, by considering physical dimensions, mechanical properties, reinforcing capability and interfacial bond strength effects. A process optimization study was first undertaken to develop the ability to produce consistent, neat geopolymer samples, a critical precursor to producing nano-filled geopolymer for toughness evaluation. After that, single edge notched bend beam fracture toughness and un-notched beam flexural strength were evaluated for silicon carbide, alumina and carbon nanofillers reinforced geopolymer samples treated at various temperatures in reactive and inert environments. Toughness results of silicon carbide and carbon nanofillers reinforced geopolymers suggested that with the improved baseline properties, high aspect ratio nanofillers with high interfacial bond strength are the most capable in further improving the toughness of geopolymers. Among the high aspect ratio nanofillers i.e. nanofibers, 2vol% silicon carbide whicker (SCW) showed the highest improvement in fracture toughness and flexural strength of ~164% & ~185%, respectively. After heat treatment at 650 °C, SCW reinforcement was found to be effective, with little reduction in the performance, while the performance of alumina nanofiber (ANF) reinforced geopolymer significantly reduced. By means of SEM, EDS and X-ray diffraction techniques, it was found that the longer and stronger SCW is more capable of reinforcing the microstructurally inhomogeneous geopolymer than the smaller diameter, shorter ANF. After heat treatment at 760 °C, the effectiveness of SCW as reinforcement in both fracture toughness and flexural strength was reduced by ~89% and ~43%, respectively, while, the ANF filled materials performed worse than the neat geopolymer. A strong interaction was suggested between ANF and geopolymer at high temperature by means of chemical reactions and diffusion. SEM & X-ray diffraction results suggested the formation of Al4C3 on the SCW surface, which could reduce the interface strength between SCW and geopolymer. Therefore it is suggested that the interface strength should be as high as required for load transfer and crack bridging. Finally, to investigate the potential synergy of a nano-filled matrix material and the fiber/matrix interface toughening mechanism of a continuous fiber composite, composite specimens were produced and tested. Flexural and shear strengths of Nextel 610 continuous fiber reinforced 2vol% SCW filled geopolymer matrix composites were investigated. Specimens were produced with cleaned Nextel fiber and with carbon-coated fibers to investigate the combinations of nano-filled matrix with continuous reinforcement that is well bonded (cleaned fiber) versus poorly bonded (carbon-coated fiber) to the matrix. The results showed that flexural strength of cleaned and coated fiber composites improved by ~35% and ~21% respectively, while shear strength of the similar composite systems improved by ~39.5% and ~24%. The results verified the effectiveness of SCW in toughening not only the neat geopolymer, but also continuous fiber reinforced geopolymer matrix composites.

Thermal and Mechanical Buckling Analysis of Hypersonic Aircraft Hat-Stiffened Panels With Varying Face Sheet Geometry and Fiber Orientation

NASA Technical Reports Server (NTRS)

Ko, William L.

1996-01-01

Mechanical and thermal buckling behavior of monolithic and metal-matrix composite hat-stiffened panels were investigated. The panels have three types of face-sheet geometry: Flat face sheet, microdented face sheet, and microbulged face sheet. The metal-matrix composite panels have three types of face-sheet layups, each of which is combined with various types of hat composite layups. Finite-element method was used in the eigenvalue extractions for both mechanical and thermal buckling. The thermal buckling analysis required both eigenvalue and material property iterations. Graphical methods of the dual iterations are shown. The mechanical and thermal buckling strengths of the hat-stiffened panels with different face-sheet geometry are compared. It was found that by just microdenting or microbulging of the face sheet, the axial, shear, and thermal buckling strengths of both types of hat-stiffened panels could be enhanced considerably. This effect is more conspicuous for the monolithic panels. For the metal-matrix composite panels, the effect of fiber orientations on the panel buckling strengths was investigated in great detail, and various composite layup combinations offering, high panel buckling strengths are presented. The axial buckling strength of the metal-matrix panel was sensitive to the change of hat fiber orientation. However, the lateral, shear, and thermal buckling strengths were insensitive to the change of hat fiber orientation.

Experimental Studies on Strength Behaviour of Notched Glass/Epoxy Laminated Composites under Uni-axial and Bi-axial Loading

NASA Astrophysics Data System (ADS)

Guptha, V. L. Jagannatha; Sharma, Ramesh S.

2017-11-01

The use of FRP composite materials in aerospace, aviation, marine, automotive and civil engineering industry has increased rapidly in recent years due to their high specific strength and stiffness properties. The structural members contrived from such composite materials are generally subjected to complex loading conditions and leads to multi-axial stress conditions at critical surface localities. Presence of notches, much required for joining process of composites, makes it further significant. The current practice of using uni-axial test data alone to validate proposed material models is inadequate leading to evaluation and consideration of bi-axial test data. In order to correlate the bi-axial strengths with the uni-axial strengths of GFRP composite laminates in the presence of a circular notch, bi-axial tests using four servo-hydraulic actuators with four load cells were carried out. To determine the in-plane strength parameters, bi-axial cruciform test specimen model was considered. Three different fibre orientations, namely, 0°, 45°, and 90° are considered with a central circular notch of 10 mm diameter in the present investigation. From the results obtained, it is observed that there is a reduction in strength of 5.36, 2.41 and 13.92% in 0°, 45°, and 90° fibre orientation, respectively, under bi-axial loading condition as compared to that of uni-axial loading in laminated composite.

Design of a self-calibration high precision micro-angle deformation optical monitoring scheme

NASA Astrophysics Data System (ADS)

Gu, Yingying; Wang, Li; Guo, Shaogang; Wu, Yun; Liu, Da

2018-03-01

In order to meet the requirement of high precision and micro-angle measurement on orbit, a self-calibrated optical non-contact real-time monitoring device is designed. Within three meters, the micro-angle variable of target relative to measuring basis can be measured in real-time. The range of angle measurement is +/-50'', the angle measurement accuracy is less than 2''. The equipment can realize high precision real-time monitoring the micro-angle deformation, which caused by high strength vibration and shock of rock launching, sun radiation and heat conduction on orbit and so on.

Magnetic slippery extreme icephobic surfaces

PubMed Central

Irajizad, Peyman; Hasnain, Munib; Farokhnia, Nazanin; Sajadi, Seyed Mohammad; Ghasemi, Hadi

2016-01-01

Anti-icing surfaces have a critical footprint on daily lives of humans ranging from transportation systems and infrastructure to energy systems, but creation of these surfaces for low temperatures remains elusive. Non-wetting surfaces and liquid-infused surfaces have inspired routes for the development of icephobic surfaces. However, high freezing temperature, high ice adhesion strength, and high cost have restricted their practical applications. Here we report new magnetic slippery surfaces outperforming state-of-the-art icephobic surfaces with a ice formation temperature of −34 °C, 2–3 orders of magnitude higher delay time in ice formation, extremely low ice adhesion strength (≈2 Pa) and stability in shear flows up to Reynolds number of 105. In these surfaces, we exploit the magnetic volumetric force to exclude the role of solid–liquid interface in ice formation. We show that these inexpensive surfaces are universal and can be applied to all types of solids (no required micro/nano structuring) with no compromise to their unprecedented properties. PMID:27824053

Variable high gradient permanent magnet quadrupole (QUAPEVA)

NASA Astrophysics Data System (ADS)

Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

2017-12-01

Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

The human peripheral subunit-binding domain folds rapidly while overcoming repulsive Coulomb forces

PubMed Central

Arbely, Eyal; Neuweiler, Hannes; Sharpe, Timothy D; Johnson, Christopher M; Fersht, Alan R

2010-01-01

Peripheral subunit binding domains (PSBDs) are integral parts of large multienzyme complexes involved in carbohydrate metabolism. PSBDs facilitate shuttling of prosthetic groups between different catalytic subunits. Their protein surface is characterized by a high density of positive charges required for binding to subunits within the complex. Here, we investigated folding thermodynamics and kinetics of the human PSBD (HSBD) using circular dichroism and tryptophan fluorescence experiments. HSBD was only marginally stable under physiological solvent conditions but folded within microseconds via a barrier-limited apparent two-state transition, analogous to its bacterial homologues. The high positive surface-charge density of HSBD leads to repulsive Coulomb forces that modulate protein stability and folding kinetics, and appear to even induce native-state movement. The electrostatic strain was alleviated at high solution-ionic-strength by Debye-Hückel screening. Differences in ionic-strength dependent characteristics among PSBD homologues could be explained by differences in their surface charge distributions. The findings highlight the trade-off between protein function and stability during protein evolution. PMID:20662005

Comparison and Analysis of Steel Frame Based on High Strength Column and Normal Strength Column

NASA Astrophysics Data System (ADS)

Liu, Taiyu; An, Yuwei

2018-01-01

The anti-seismic performance of high strength steel has restricted its industrialization in civil buildings. In order to study the influence of high strength steel column on frame structure, three models are designed through MIDAS/GEN finite element software. By comparing the seismic performance and economic performance of the three models, the three different structures are comprehensively evaluated to provide some references for the development of high strength steel in steel structure.

46 CFR 42.09-10 - Stability, subdivision, and strength.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Stability, subdivision, and strength. 42.09-10 Section..., subdivision, and strength. (a) All vessels. Where regulations in this part, or in part 46 of this subchapter... strength requirements are in §§ 42.09-1, 42.13-1, 42.13-5, and 42.15-1. The applicable flooded stability...

46 CFR 42.09-10 - Stability, subdivision, and strength.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Stability, subdivision, and strength. 42.09-10 Section..., subdivision, and strength. (a) All vessels. Where regulations in this part, or in part 46 of this subchapter... strength requirements are in §§ 42.09-1, 42.13-1, 42.13-5, and 42.15-1. The applicable flooded stability...

Low temperature reactive bonding

DOEpatents

Makowiecki, D.M.; Bionta, R.M.

1995-01-17

The joining technique is disclosed that requires no external heat source and generates very little heat during joining. It involves the reaction of thin multilayered films deposited on faying surfaces to create a stable compound that functions as an intermediate or braze material in order to create a high strength bond. While high temperatures are reached in the reaction of the multilayer film, very little heat is generated because the films are very thin. It is essentially a room temperature joining process. 5 figures.

Physical requirements in Olympic sailing.

PubMed

Bojsen-Møller, J; Larsson, B; Aagaard, P

2015-01-01

Physical fitness and muscular strength are important performance parameters in Olympic sailing although their relative importance changes between classes. The Olympic format consists of eight yacht types combined into 10 so-called events with total 15 sailors (male and female) in a complete national Olympic delegation. The yachts have different requirements with respect to handling, and moreover, each sailor plays a specific role when sailing. Therefore physical demands remain heterogeneous for Olympic sailors. Previous studies have mainly examined sailors where 'hiking' (the task of leaning over the side of the yacht to increase righting moment) is the primary requirement. Other than the ability to sustain prolonged quasi-isometric contractions, hiking seems to require significant maximal muscle strength especially in knee extensors, hip flexors and abdominal and lower back muscles. Another group of studies has investigated boardsailing and provided evidence to show that windsurfing requires very high aerobic and anaerobic capacity. Although data exist on other types of sailors, the information is limited, and moreover the profile of the Olympic events has changed markedly over the last few years to involve more agile, fast and spectacular yachts. The change of events in Olympic sailing has likely added to physical requirements; however, data on sailors in the modern-type yachts are scarce. The present paper describes the recent developments in Olympic sailing with respect to yacht types, and reviews the existing knowledge on physical requirements in modern Olympic sailing. Finally, recommendations for future research in sailing are given.

Mechanical and fracture behavior of veneer-framework composites for all-ceramic dental bridges.

PubMed

Studart, André R; Filser, Frank; Kocher, Peter; Lüthy, Heinz; Gauckler, Ludwig J

2007-01-01

High-strength ceramics are required in dental posterior restorations in order to withstand the excessive tensile stresses that occur during mastication. The aim of this study was to investigate the fracture behavior and the fast-fracture mechanical strength of three veneer-framework composites (Empress 2/IPS Eris, TZP/Cercon S and Inceram-Zirconia/Vita VM7) for all-ceramic dental bridges. The load bearing capacity of the veneer-framework composites were evaluated using a bending mechanical apparatus. The stress distribution through the rectangular-shaped layered samples was assessed using simple beam calculations and used to estimate the fracture strength of the veneer layer. Optical microscopy of fractured specimens was employed to determine the origin of cracks and the fracture mode. Under fast fracture conditions, cracks were observed to initiate on, or close to, the veneer outer surface and propagate towards the inner framework material. Crack deflection occurred at the veneer-framework interface of composites containing a tough framework material (TZP/Cercon S and Inceram-Zirconia/Vita VM7), as opposed to the straight propagation observed in the case of weaker frameworks (Empress 2/IPS Eris). The mechanical strength of dental composites containing a weak framework (K(IC)<3 MPam(1/2)) is ultimately determined by the low fracture strength of the veneer layer, since no crack arresting occurs at the veneer-framework interface. Therefore, high-toughness ceramics (K(IC)>5 MPam(1/2)) should be used as framework materials of posterior all-ceramic bridges, so that cracks propagating from the veneer layer do not lead to a premature failure of the prosthesis.

Influence of Abutment Design on Stiffness, Strength, and Failure of Implant-Supported Monolithic Resin Nano Ceramic (RNC) Crowns.

PubMed

Joda, Tim; Huber, Samuel; Bürki, Alexander; Zysset, Philippe; Brägger, Urs

2015-12-01

Recent technical development allows the digital manufacturing of monolithic reconstructions with high-performance materials. For implant-supported crowns, the fixation requires an abutment design onto which the reconstruction can be bonded. The aim of this laboratory investigation was to analyze stiffness, strength, and failure modes of implant-supported, computer-assisted design and computer-aided manufacturing (CAD/CAM)-generated resin nano ceramic (RNC) crowns bonded to three different titanium abutments. Eighteen monolithic RNC crowns were produced and loaded in a universal testing machine under quasi-static condition according to DIN ISO 14801. With regard to the type of titanium abutment, three groups were defined: (1) prefabricated cementable standard; (2) CAD/CAM-constructed individualized; and (3) novel prefabricated bonding base. Stiffness and strength were measured and analyzed statistically with Wilcoxon rank sum test. Sections of the specimens were examined microscopically. Stiffness demonstrated high stability for all specimens loaded in the physiological loading range with means and standard deviations of 1,579 ± 120 N/mm (group A), 1,733 ± 89 N/mm (group B), and 1,704 ± 162 N/mm (group C). Mean strength of the novel prefabricated bonding base (group C) was 17% lower than of the two other groups. Plastic deformations were detectable for all implant-abutment crown connections. Monolithic implant crowns made of RNC seem to represent a feasible and stable prosthetic construction under laboratory testing conditions with strength higher than the average occlusal force, independent of the different abutment designs used in this investigation. © 2014 Wiley Periodicals, Inc.

Method and system for controlling chemical reactions between superconductors and metals in superconducting cables

DOEpatents

Shen, Tengming

2016-11-15

A method, system, and apparatus for fabricating a high-strength Superconducting cable comprises pre-oxidizing at least one high-strength alloy wire, coating at least one Superconducting wire with a protective layer, and winding the high-strength alloy wire and the Superconducting wire to form a high-strength Superconducting cable.

Method and system for controlling chemical reactions between superconductors and metals in superconducting cables

DOEpatents

Shen, Tengming

2018-01-02

A method, system, and apparatus for fabricating a high-strength Superconducting cable comprises pre-oxidizing at least one high-strength alloy wire, coating at least one Superconducting wire with a protective layer, and winding the high-strength alloy wire and the Superconducting wire to form a high-strength Superconducting cable.

Low cost tooling material and process for graphite and Kevlar composites

NASA Technical Reports Server (NTRS)

Childs, William I.

1987-01-01

An Extruded Sheet Tooling Compound (ESTC) was developed for use in quickly building low cost molds for fabricating composites. The ESTC is a very highly mineral-filled resin system formed into a 6 mm thick sheet. The sheet is laid on the pattern, vacuum (bag) is applied to remove air from the pattern surface, and the assembly is heat cured. The formed ESTC is then backed and/or framed and ready for use. The cured ESTC exhibits low coefficient of thermal expansion and maintains strength at temperatures of 180 to 200 C. Tools were made and used successfully for: Compression molding of high strength epoxy sheet molding compound, stamping of aluminum, resin transfer molding of polyester, and liquid resin molding of polyester. Several variations of ESTC can be made for specific requirements. Higher thermal conductivity can be achieved by using an aluminum particle filler. Room temperature gel is possible to allow use of foam patterns.

Cold Cracking During Direct-Chill Casting

NASA Astrophysics Data System (ADS)

Eskin, D. G.; Lalpoor, M.; Katgerman, L.

Cold cracking phenomenon is the least studied, yet very important defect occurring during direct chill casting. The spontaneous nature of this defect makes its systematic study almost impossible, and the computer simulation of the thermomechanical behavior of the ingot during its cooling after the end of solidification requires constitutive parameters of high-strength aluminum alloys in the as-cast condition, which are not readily available. In this paper we describe constitutive behavior of high strength 7xxx series aluminum alloys in the as-cast condition based on experimentally measured tensile properties at different strain rates and temperatures, plane strain fracture toughness at different temperatures, and thermal contraction. In addition, fracture and structure of the specimens and real cold-cracked billets are examined. As a result a fracture-mechanics-based criterion of cold cracking is suggested based on the critical crack length, and is validated upon pilot-scale billet casting.

Reaction-induced rheological weakening enables oceanic plate subduction.

PubMed

Hirauchi, Ken-Ichi; Fukushima, Kumi; Kido, Masanori; Muto, Jun; Okamoto, Atsushi

2016-08-26

Earth is the only terrestrial planet in our solar system where an oceanic plate subducts beneath an overriding plate. Although the initiation of plate subduction requires extremely weak boundaries between strong plates, the way in which oceanic mantle rheologically weakens remains unknown. Here we show that shear-enhanced hydration reactions contribute to the generation and maintenance of weak mantle shear zones at mid-lithospheric depths. High-pressure friction experiments on peridotite gouge reveal that in the presence of hydrothermal water, increasing strain and reactions lead to an order-of-magnitude reduction in strength. The rate of deformation is controlled by pressure-solution-accommodated frictional sliding on weak hydrous phyllosilicate (talc), providing a mechanism for the 'cutoff' of the high peak strength at the brittle-plastic transition. Our findings suggest that infiltration of seawater into transform faults with long lengths and low slip rates is an important controlling factor on the initiation of plate tectonics on terrestrial planets.

Beryllium-aluminum alloys for investment castings

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

Nachtrab, W.T.; Levoy, N.

1997-05-01

Beryllium-aluminum alloys containing greater than 60 wt % beryllium are very favorable materials for applications requiring light weight and high stiffness. However, when produced by traditional powder metallurgical methods, these alloys are expensive and have limited applications. To reduce the cost of making beryllium-aluminum components, Nuclear Metals Inc. (NMI) and Lockheed Martin Electronics and Missiles have recently developed a family of patented beryllium-aluminum alloys that can be investment cast. Designated Beralcast, the alloys can achieve substantial weight savings because of their high specific strength and stiffness. In some cases, weight has been reduced by up to 50% over aluminum investmentmore » casting. Beralcast is now being used to make thin wall precision investment castings for several advanced aerospace applications, such as the RAH-66 Comanche helicopter and F-22 jet fighter. This article discusses alloy compositions, properties, casting method, and the effects of cobalt additions on strength.« less

Sex- and Age-Related Differences in Bone Microarchitecture in Men Relative to Women Assessed by High-Resolution Peripheral Quantitative Computed Tomography

PubMed Central

Amin, Shreyasee; Khosla, Sundeep

2012-01-01

The trabecular and cortical compartments of bone each contributes to bone strength. Until recently, assessment of trabecular and cortical microstructure has required a bone biopsy. Now, trabecular and cortical microstructure of peripheral bone sites can be determined noninvasively using high-resolution peripheral quantitative computed tomography (HR-pQCT). Studies that have used HR-pQCT to evaluate cohorts of both men and women have provided novel insights into the changes in bone microarchitecture that occur with age between the sexes, which may help to explain the lower fracture incidence in older men relative to women. This review will highlight observations from these studies on both the sex- and age-related differences in trabecular and cortical microstructure that may underlie the differences in bone strength, and thereby fracture risk, between men and women. PMID:22496983

Cryogenic Properties of Aluminum Beryllium and Beryllium Materials

NASA Technical Reports Server (NTRS)

Gamwell, Wayne R.; McGill, Preston B.

2003-01-01

Ultimate tensile strength, yield strength, and elongation were obtained for the aluminum-beryllium alloy, AlBeMetl62 (38%Al-62%Be), at cryogenic (-195.5 C (-320 F) and (-252.8 C) (-423 F)) temperatures, and for an optical grade beryllium, O-30H (99%Be), at -252.8 C. AlBeMetl62 material was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions." O-30H material was purchased to the requirements of Brush Wellman Inc. specification O-30H Optical Grade Beryllium. The ultimate tensile and yield strengths for extruded AlBeMetl62 material increased with decreasing temperature, and the percent elongation decreased with decreasing temperature. Design properties for the ultimate tensile strength, yield strength, and percent elongation for extruded AlBeMetl62 were generated. It was not possible to distinguish a difference in the room and cryogenic ultimate strength for the hot isostatically pressed (HIP'ed) O-30H material. The O30H elongation decreased with decreasing temperature.

The circumstellar envelope of the C-rich post-AGB star HD 56126

NASA Astrophysics Data System (ADS)

Hony, S.; Tielens, A. G. G. M.; Waters, L. B. F. M.; de Koter, A.

2003-04-01

We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch ``21 mu m object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use amorphous carbon, hydrogenated amorphous carbon, magnesium sulfide and titanium carbide. We present a detailed parametrisation of the optical properties of hydrogenated amorphous carbon as a function of H/C content. The mid-infrared imaging and spectroscopy is best reproduced by a single dust shell from 1.2 to 2.6'' radius around the central star. This shell originates from a short period during which the mass-loss rate exceeded 10-4 Msun/yr. We find that the strength of the ``21'' mu m feature poses a problem for the TiC identification. The low abundance of Ti requires very high absorption cross-sections in the ultraviolet and visible wavelength range to explain the strength of the feature. Other nano-crystalline metal carbides should be considered as well. We find that hydrogenated amorphous carbon in radiative equilibrium with the local radiation field does not reach a high enough temperature to explain the strength of the 3.3-3.4 and 6-9 mu m hydrocarbon features relative to the 11-17 mu m hydrocarbon features. We propose that the carriers of these hydrocarbon features are not in radiative equilibrium but are transiently heated to high temperature. We find that 2 per cent of the dust mass is required to explain the strength of the ``30'' mu m feature, which fits well within the measured atmospheric abundance of Mg and S. This further strengthens the MgS identification of the ``30'' mu m feature. Based on observations taken at the European Southern Observatory, La Silla, Chile and observation obtained with ISO, an ESA project with instruments funded by ESA Member states (especially the PI countries: France, Germany, The Netherlands and the UK) with the participation of ISAS and NASA.

Precipitation-Strengthened, High-Temperature, High-Force Shape Memory Alloys

NASA Technical Reports Server (NTRS)

Noebe, Ronald D.; Draper, Susan L.; Nathal, Michael V.; Crombie, Edwin A.

2008-01-01

Shape memory alloys (SMAs) are an enabling component in the development of compact, lightweight, durable, high-force actuation systems particularly for use where hydraulics or electrical motors are not practical. However, commercial shape memory alloys based on NiTi are only suitable for applications near room temperature, due to their relatively low transformation temperatures, while many potential applications require higher temperature capability. Consequently, a family of (Ni,Pt)(sub 1-x)Ti(sub x) shape memory alloys with Ti concentrations ranging from about 15 to 25 at.% have been developed for applications in which there are requirements for SMA actuators to exert high forces at operating temperatures higher than those of conventional binary NiTi SMAs. These alloys can be heat treated in the range of 500 C to produce a series of fine precipitate phases that increase the strength of alloy while maintaining a high transformation temperature, even in Ti-lean compositions.

Role of the polymer phase in the mechanics of nacre-like composites

NASA Astrophysics Data System (ADS)

Niebel, Tobias P.; Bouville, Florian; Kokkinis, Dimitri; Studart, André R.

2016-11-01

Although strength and toughness are often mutually exclusive properties in man-made structural materials, nature is full of examples of composite materials that combine these properties in a remarkable way through sophisticated multiscale architectures. Understanding the contributions of the different constituents to the energy dissipating toughening mechanisms active in these natural materials is crucial for the development of strong artificial composites with a high resistance to fracture. Here, we systematically study the influence of the polymer properties on the mechanics of nacre-like composites containing an intermediate fraction of mineral phase (57 vol%). To this end, we infiltrate ceramic scaffolds prepared by magnetically assisted slip casting (MASC) with monomers that are subsequently cured to yield three drastically different polymers: (i) poly(lauryl methacrylate) (PLMA), a soft and weak elastomer; (ii) poly(methyl methacrylate) (PMMA), a strong, stiff and brittle thermoplastic; and (iii) polyether urethane diacrylate-co-poly(2-hydroxyethyl methacrylate) (PUA-PHEMA), a tough polymer of intermediate strength and stiffness. By combining our experimental data with finite element modeling, we find that stiffer polymers can increase the strength of the composite by reducing stress concentrations in the inorganic scaffold. Moreover, infiltrating the scaffolds with tough polymers leads to composites with high crack initiation toughness KIC. An organic phase with a minimum strength and toughness is also required to fully activate the mechanisms programmed within the ceramic structure for a rising R-curve behavior. Our results indicate that a high modulus of toughness is a key parameter for the selection of polymers leading to strong and tough bioinspired nacre-like composites.

Physical, mechanical, and flexural properties of 3 orthodontic wires: an in-vitro study.

PubMed

Juvvadi, Shubhaker Rao; Kailasam, Vignesh; Padmanabhan, Sridevi; Chitharanjan, Arun B

2010-11-01

Understanding the biologic requirements of orthodontic patients requires proper characterization studies of new archwire alloys. The aims of this study were to evaluate properties of wires made of 2 new materials and to compare their properties with those of stainless steel. The sample consisted of 30 straight lengths of 3 types of wires: stainless steel, titanium-molybdenum alloy, and beta-titanium alloy. Eight properties were evaluated: wire dimension, edge bevel, composition, surface characteristics, frictional characteristics, ultimate tensile strength (UTS), modulus of elasticity (E), yield strength (YS), and load deflection characteristics. A toolmaker's microscope was used to measure the edge bevel, and x-ray fluorescence was used for composition analysis. Surface profilometry and scanning electron microscopy were used for surface evaluation. A universal testing machine was used to evaluate frictional characteristics, tensile strength, and 3-point bending. Stainless steel was the smoothest wire; it had the lowest friction and spring-back values and high values for stiffness, E, YS, and UTS. The titanium-molybdenum alloy was the roughest wire; it had high friction and intermediate spring-back, stiffness, and UTS values. The beta-titanium alloy was intermediate for smoothness, friction, and UTS but had the highest spring-back. The beta-titanium alloy with increased UTS and YS had a low E value, suggesting that it would have greater resistance to fracture, thereby overcoming a major disadvantage of titanium-molybdenum alloy wires. The beta-titanium alloy wire would also deliver gentler forces. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Diaphragm Plasticity in Aging and Disease: Therapies for Muscle Weakness go from Strength to Strength.

PubMed

Greising, Sarah M; Ottenheijm, Coen A C; O'Halloran, Ken D; Barreiro, Esther

2018-04-19

The diaphragm is the main inspiratory muscle and is required to be highly active throughout the lifespan. The diaphragm muscle must be able to produce and sustain various behaviors that range from ventilatory to non-ventilatory such as those required for airway maintenance and clearance. Throughout the lifespan various circumstances and conditions may affect the ability of the diaphragm muscle to generate requisite forces and in turn the diaphragm muscle may undergo significant weakness and dysfunction. For example, hypoxic stress, critical illness, cancer cachexia, chronic obstructive pulmonary disorder (COPD), and age-related sarcopenia all represent conditions in which significant diaphragm muscle dysfunction exits. This perspective review article presents several interesting topics involving diaphragm plasticity in aging and disease that were presented at the International Union of Physiological Sciences (IUPS) Conference in 2017.This review seeks to maximize the broad and collective research impact on diaphragm muscle dysfunction in the search for transformative treatment approaches to improve the diaphragm muscle health during aging and disease.

Hollow proppants and a process for their manufacture

DOEpatents

Jones, A.H.; Cutler, R.A.

1985-10-15

Hollow, fine-grained ceramic proppants are less expensive and improve fracture control when compared to conventional proppants (dense alumina, mullite, bauxite, zirconia, etc.). Hollow proppants of the present invention have been fabricated by spray drying, followed by sintering in order to obtain a dense case and a hollow core. These proppants generally have high sphericity and roundness (Krumbein sphericity and roundness greater than 0.8), have diameters on average between 2,250 and 125 [mu]m, depending on proppant size required, and have strength equal to or greater than that of sand. The hollow core, the size of which can be controlled, permits better fracture control in hydraulic fracturing treatments since the proppant can be transported in lower viscosity fluids. Hollow proppants produced at the same cost/weight as conventional proppants also provide for lower costs, since less weight is required to fill the same volume. The fine-grained (preferably less than 5 [mu]m in diameter) ceramic case provides the strength necessary to withstand closure stresses and prevent crushing. 6 figs.

Hollow proppants and a process for their manufacture

DOEpatents

Jones, Arfon H.; Cutler, Raymond A.

1985-01-01

Hollow, fine-grained ceramic proppants are less expensive and improve fracture control when compared to conventional proppants (dense alumina, mullite, bauxite, zirconia, etc.). Hollow proppants of the present invention have been fabricated by spray drying, followed by sintering in order to obtain a dense case and a hollow core. These proppants generally have high sphericity and roundness (Krumbein sphericity and roundness greater than 0.8), have diameters on average between 2250 and 125 .mu.m, depending on proppant size required, and have strength equal to or greater than that of sand. The hollow core, the size of which can be controlled, permits better fracture control in hydraulic fracturing treatments since the proppant can be transported in lower viscosity fluids. Hollow proppants produced at the same cost/weight as conventional proppants also provide for lower costs, since less weight is required to fill the same volume. The fine-grained (preferably less than 5 .mu.m in diameter) ceramic case provides the strength necessary to withstand closure stresses and prevent crushing.

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

Paillard, Pascal

Two try-out campaigns of friction stir welding (FSW) were performed with different friction parameters to join S690QL high yield strength steel. The welds were investigated at macroscopic and microscopic scales using optical and electronic microscopy and microhardness mapping. Welds of the second campaign exhibit microstructures and mechanical properties in accordance with requirements for service use. Microtexture measurements were carried out in different zones of welds by electron backscattered diffraction (EBSD). It is shown that that texture of the bottom of the weld is similar to that of the base metal, suggesting a diffusion bonding mechanism. Finally, the mechanical properties (tensilemore » strength, resilience, bending) were established on the most promising welds. It is shown that it is possible to weld this high yield strength steel using FSW process with satisfactory geometric, microstructural and mechanical properties. - Highlights: •1000 mm ∗ 400 mm ∗ 8 mm S690QL steel plates are joined by friction stir welding (FSW). •Maximum hardness is reduced by optimization of process parameters. •Various microstructures are formed but no martensite after process optimization. •Texture is modified in mechanically affected zones of the weld. •Texture in the bottom of the weld is preserved, suggesting diffusion bonding.« less

Dynamic compressive properties obtained from a split Hopkinson pressure bar test of Boryeong shale

NASA Astrophysics Data System (ADS)

Kang, Minju; Cho, Jung-Woo; Kim, Yang Gon; Park, Jaeyeong; Jeong, Myeong-Sik; Lee, Sunghak

2016-09-01

Dynamic compressive properties of a Boryeong shale were evaluated by using a split Hopkinson pressure bar, and were compared with those of a Hwangdeung granite which is a typical hard rock. The results indicated that the dynamic compressive loading reduced the resistance to fracture. The dynamic compressive strength was lower in the shale than in the granite, and was raised with increasing strain rate by microcracking effect as well as strain rate strengthening effect. Since the number of microcracked fragments increased with increasing strain rate in the shale having laminated weakness planes, the shale showed the better fragmentation performance than the granite at high strain rates. The effect of transversely isotropic plane on compressive strength decreased with increasing strain rate, which was desirable for increasing the fragmentation performance. Thus, the shale can be more reliably applied to industrial areas requiring good fragmentation performance as the striking speed of drilling or hydraulic fracturing machines increased. The present dynamic compressive test effectively evaluated the fragmentation performance as well as compressive strength and strain energy density by controlling the air pressure, and provided an important idea on which rock was more readily fragmented under dynamically processing conditions such as high-speed drilling and blasting.

Improved silicon nitride for advanced heat engines

NASA Technical Reports Server (NTRS)

Yeh, Hun C.; Fang, Ho T.

1987-01-01

The technology base required to fabricate silicon nitride components with the strength, reliability, and reproducibility necessary for actual heat engine applications is presented. Task 2 was set up to develop test bars with high Weibull slope and greater high temperature strength, and to conduct an initial net shape component fabrication evaluation. Screening experiments were performed in Task 7 on advanced materials and processing for input to Task 2. The technical efforts performed in the second year of a 5-yr program are covered. The first iteration of Task 2 was completed as planned. Two half-replicated, fractional factorial (2 sup 5), statistically designed matrix experiments were conducted. These experiments have identified Denka 9FW Si3N4 as an alternate raw material to GTE SN502 Si3N4 for subsequent process evaluation. A detailed statistical analysis was conducted to correlate processing conditions with as-processed test bar properties. One processing condition produced a material with a 97 ksi average room temperature MOR (100 percent of goal) with 13.2 Weibull slope (83 percent of goal); another condition produced 86 ksi (6 percent over baseline) room temperature strength with a Weibull slope of 20 (125 percent of goal).

Transition to complete synchronization and global intermittent synchronization in an array of time-delay systems.

PubMed

Suresh, R; Senthilkumar, D V; Lakshmanan, M; Kurths, J

2012-07-01

We report the nature of transitions from the nonsynchronous to a complete synchronization (CS) state in arrays of time-delay systems, where the systems are coupled with instantaneous diffusive coupling. We demonstrate that the transition to CS occurs distinctly for different coupling configurations. In particular, for unidirectional coupling, locally (microscopically) synchronization transition occurs in a very narrow range of coupling strength but for a global one (macroscopically) it occurs sequentially in a broad range of coupling strength preceded by an intermittent synchronization. On the other hand, in the case of mutual coupling, a very large value of coupling strength is required for local synchronization and, consequently, all the local subsystems synchronize immediately for the same value of the coupling strength and, hence, globally, synchronization also occurs in a narrow range of the coupling strength. In the transition regime, we observe a type of synchronization transition where long intervals of high-quality synchronization which are interrupted at irregular times by intermittent chaotic bursts simultaneously in all the systems and which we designate as global intermittent synchronization. We also relate our synchronization transition results to the above specific types using unstable periodic orbit theory. The above studies are carried out in a well-known piecewise linear time-delay system.

Responsive nanoporous metals: recoverable modulations on strength and shape by watering

NASA Astrophysics Data System (ADS)

Ye, Xing-Long; Liu, Ling-Zhi; Jin, Hai-Jun

2016-08-01

Many biological materials can readily modulate their mechanical properties and shape by interacting with water in the surrounding environment, which is essential to their high performance in application. In contrast, typical inorganic materials (such as the metals) cannot change their strength and shape without involving thermal/mechanical treatments. By introducing nano-scale porous structure and exploiting a simple physical concept—the water-capillarity in nanopores, here we report that a ‘dead’ metal can be transformed into a ‘smart’ material with water-responsive properties. We demonstrate that the apparent strength, volume and shape of nanoporous Au and Au(Pt) can be modulated in situ, dramatically and recoverably, in response to water-dipping and partial-drying. The amplitude of strength-modulation reaches 20 MPa, which is nearly 50% of the yield strength at initial state. This approach also leads to reversible length change up to 1.3% in nanoporous Au and a large reversible bending motion of a bi-layer strip with tip displacement of ˜20 mm, which may be used for actuation. This method is simple and effective, occurring in situ under ambient conditions and requiring no external power, analogous to biological materials. The findings may open up novel applications in many areas such as micro-robotics and bio-medical devices.

Effect of yield curves and porous crush on hydrocode simulations of asteroid airburst

NASA Astrophysics Data System (ADS)

Robertson, D. K.; Mathias, D. L.

2017-03-01

Simulations of asteroid airburst are being conducted to obtain best estimates of damage areas and assess sensitivity to variables for asteroid characterization and mitigation efforts. The simulations presented here employed the ALE3D hydrocode to examine the breakup and energy deposition of asteroids entering the Earth's atmosphere, using the Chelyabinsk meteor as a test case. This paper examines the effect of increasingly complex material models on the energy deposition profile. Modeling the meteor as a rock having a single strength can reproduce airburst altitude and energy deposition reasonably well but is not representative of real rock masses (large bodies of material). Accounting for a yield curve that includes different tensile, shear, and compressive strengths shows that shear strength determines the burst altitude. Including yield curves and compaction of porous spaces in the material changes the detailed mechanics of the breakup but only has a limited effect on the burst altitude and energy deposition. Strong asteroids fail and create peak energy deposition close to the altitude at which ram dynamic pressure equals the material strength. Weak asteroids, even though they structurally fail at high altitude, require the increased pressure at lower altitude to disrupt and disperse the rubble. As a result, a wide range of weaker asteroid strengths produce peak energy deposition at a similar altitude.

Strength Training for Women as a Vehicle for Health Promotion at Work.

PubMed

Nestler, Kai; Witzki, Alexander; Rohde, Ulrich; Rüther, Thomas; Tofaute, Kim Alexander; Leyk, Dieter

2017-06-30

Women, on average, have less muscle strength than men. This anthropometric-physiological trait may make them more vulnerable to ex - cessive physical strain, injury, and inability to work. Strength training is used for preventive health maintenance and to lessen musculoskeletal symptoms. In this context, we studied whether the degree of muscle strength has any effect on women's health in everyday working life, and also the effects of strength training for women on their health in the workplace. We systematically searched the PubMed/MEDLINE, Embase, CINAHL, Web of Science, CENTRAL, and SPOLIT databases for pertinent publications, in accordance with the PRISMA criteria for literature searches. We analyzed all of the retrieved randomized controlled trials conducted on women aged 18 to 65 to determine the effects of training on muscle strength, physical performance ability, and health-related parameters including body composition, musculo - skeletal pain, and subjective well-being. We did not find any studies that provided answers to the first question. As for the second question, the selection criteria were met by 12 of the 4969 retrieved studies, which dealt with the effect of strength training on health in the occupational environment and involved a total of 1365 female subjects. These studies were carried out in heterogeneous subject groups, with a variety of overlapping interventions consisting of both strength and endurance training. Significantly increased strength was found in all studies, as was a reduction of pain in all of the studies where this question was asked. Inconsistent results were obtained with respect to body weight, body composition, and subjective well-being. The interventions that were conducted in these studies succeeded in increasing strength and reducing pain, even when the training was brief and of low intensity. This was true not only for women working in occupations requiring unusual physical strength, but also for those in sedentary occupations. The small number of studies performed on this subject to date is surprising in view of the high prevalence of musculoskeletal symptoms in women.

U.S. Immigration Policy and the National Interest.

ERIC Educational Resources Information Center

Fauriol, Georges

1984-01-01

The national security of the United States depends upon its domestic strength and international stability. This strength requires an ability to control national borders, the maintenance of an independent foreign policy, a prosperous economy, and a cohesive domestic political environment. Uncontrolled migration is undermining this strength. (RM)

24 CFR 3280.810 - Electrical testing.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Electrical testing. (a) Dielectric strength test. The wiring of each manufactured home shall be subjected to a 1-minute, 900 to 1079 volt dielectric strength test (with all switches closed) between live parts... listed shall not be required to withstand the dielectric strength test. (b) Each manufactured home shall...

24 CFR 3280.810 - Electrical testing.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Electrical testing. (a) Dielectric strength test. The wiring of each manufactured home shall be subjected to a 1-minute, 900 to 1079 volt dielectric strength test (with all switches closed) between live parts... listed shall not be required to withstand the dielectric strength test. (b) Each manufactured home shall...

Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

NASA Astrophysics Data System (ADS)

Amare, Belachew N.

Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural coating. During this project it was found that stiffness response to increase and remain stable to a certain level and reduce at latter stages of thermal cyclic exposure. The predominant growth and adherent Ni-rich outer oxide scale was found on top of the alumina scale throughout the oxidation cycles. The FEA analysis revealed that ODS alloys could be potential high temperature turbine coating materials if micro-channel cooling system is implemented.

Weld Design, Testing, and Assessment Procedures for High Strength Pipelines

DOT National Transportation Integrated Search

2011-12-20

Long-distance high-strength pipelines are increasingly being constructed for the efficient transportation of energy products. While the high-strength linepipe steels and high productivity welding processes are being applied, the procedures employed f...

Study to determine and analyze the strength of high modulus glass in epoxy-matrix composites

NASA Technical Reports Server (NTRS)

Bacon, J. F.

1974-01-01

Glass composition research was conducted to produce a high modulus, high strength beryllium-free glass fiber. This program was built on the previous research for developing high modulus, high strength glass fibers which had a 5 weight percent beryllia content. The fibers resulting from the composition program were then used to produce fiber reinforced-epoxy resin composites which were compared with composites reinforced by commercial high modulus glass fibers, Thornel S graphite fiber, and hybrids where the external quarters were reinforced with Thornel S graphite fiber and the interior half with glass fiber as well as the reverse hybrid. The composites were given tensile strength, compressive strength, short-beam shear strength, creep and fatigue tests. Comments are included on the significance of the test data.

The research on delayed fracture behavior of high-strength bolts in steel structure

NASA Astrophysics Data System (ADS)

Li, Guo dong; Li, Nan

2017-07-01

High-strength bolts have been widely used in power plants. However, the high-strength bolts which being employed in pumping station, steel structure and pipeline anti-whip structure have been found delayed fracture for many times in a power plant, this will affect the reliability of steel fracture and bring blow risk caused by falling objects. The high-strength bolt with delayed fracture was carried out fracture analysis, metallurgical analysis, chemical analysis, mechanical analysis, as well as bolts installation analysis, it can be comprehensively confirmed that the direct cause of high-strength bolts delayed fracture is the stress corrosion, and the root cause of high-strength bolts delayed fracture should be the improper installation at the initial and the imperfect routine anti-corrosion maintenance.

Solid-Liquid Interdiffusion Bonding of Silicon Carbide to Steel for High Temperature MEMS Sensor Packaging and Bonding

NASA Astrophysics Data System (ADS)

Chan, Matthew Wei-Jen

Complex engineering systems ranging from automobile engines to geothermal wells require specialized sensors to monitor conditions such as pressure, acceleration and temperature in order to improve efficiency and monitor component lifetime in what may be high temperature, corrosive, harsh environments. Microelectromechanical systems (MEMS) have demonstrated their ability to precisely and accurately take measurements under such conditions. The systems being monitored are typically made from metals, such as steel, while the MEMS sensors used for monitoring are commonly fabricated from silicon, silicon carbide and aluminum nitride, and so there is a sizable thermal expansion mismatch between the two. For these engineering applications the direct bonding of MEMS sensors to the components being monitored is often required. This introduces several challenges, namely the development of a bond that is capable of surviving high temperature harsh environments while mitigating the thermally induced strains produced during bonding. This project investigates the development of a robust packaging and bonding process, using the gold-tin metal system and the solid-liquid interdiffusion (SLID) bonding process, to join silicon carbide substrates directly to type-316 stainless steel. The SLID process enables bonding at lower temperatures while producing a bond capable of surviving higher temperatures. Finite element analysis was performed to model the thermally induced strains generated in the bond and to understand the optimal way to design the bond. The cross-sectional composition of the bonds has been analyzed and the bond strength has been investigated using die shear testing. The effects of high temperature aging on the bond's strength and the metallurgy of the bond were studied. Additionally, loading of the bond was performed at temperatures over 415 °C, more than 100 °C, above the temperature used for bonding, with full survival of the bond, thus demonstrating the benefit of SLID bonding for high temperature applications. Lastly, this dissertation provides recommendations for improving the strength and durability of the bond at temperatures of 400 °C and provides the framework for future work in the area of high temperature harsh environment MEMS packaging that would take directly bonded MEMS to temperatures of 600 °C and beyond.

Energy efficient engine high-pressure turbine detailed design report

NASA Technical Reports Server (NTRS)

Thulin, R. D.; Howe, D. C.; Singer, I. D.

1982-01-01

The energy efficient engine high-pressure turbine is a single stage system based on technology advancements in the areas of aerodynamics, structures and materials to achieve high performance, low operating economics and durability commensurate with commercial service requirements. Low loss performance features combined with a low through-flow velocity approach results in a predicted efficiency of 88.8 for a flight propulsion system. Turbine airfoil durability goals are achieved through the use of advanced high-strength and high-temperature capability single crystal materials and effective cooling management. Overall, this design reflects a considerable extension in turbine technology that is applicable to future, energy efficient gas-turbine engines.

Effect of soil acidity, soil strength and macropores on root growth and morphology of perennial grass species differing in acid-soil resistance.

PubMed

Haling, Rebecca E; Simpson, Richard J; Culvenor, Richard A; Lambers, Hans; Richardson, Alan E

2011-03-01

It is unclear whether roots of acid-soil resistant plants have significant advantages, compared with acid-soil sensitive genotypes, when growing in high-strength, acid soils or in acid soils where macropores may allow the effects of soil acidity and strength to be avoided. The responses of root growth and morphology to soil acidity, soil strength and macropores by seedlings of five perennial grass genotypes differing in acid-soil resistance were determined, and the interaction of soil acidity and strength for growth and morphology of roots was investigated. Soil acidity and strength altered root length and architecture, root hair development, and deformed the root tip, especially in acid-soil sensitive genotypes. Root length was restricted to some extent by soil acidity in all genotypes, but the adverse impact of soil acidity on root growth by acid-soil resistant genotypes was greater at high levels of soil strength. Roots reacted to soil acidity when growing in macropores, but elongation through high-strength soil was improved. Soil strength can confound the effect of acidity on root growth, with the sensitivity of acid-resistant genotypes being greater in high-strength soils. This highlights the need to select for genotypes that resist both acidity and high soil strength. © 2010 Blackwell Publishing Ltd.

Development of lightweight fire retardant, low-smoke, high-strength, thermally stable aircraft floor paneling

NASA Technical Reports Server (NTRS)

Arnold, D. B.; Burnside, J. V.; Hajari, J. V.

1976-01-01

Fire resistance mechanical property tests were conducted on sandwich configurations composed of resin-fiberglass laminates bonded with adhesives to Nomex honeycomb core. The test results were compared to proposed and current requirements for aircraft floor panel applications to demonstrate that the fire safety of the airplane could be improved without sacrificing mechanical performance of the aircraft floor panels.

User's Guide to Computing High School Graduation Rates. Volume 2. Technical Report: Technical Evaluation of Proxy Graduation Indicators. NCES 2006-605

ERIC Educational Resources Information Center

Seastrom, Marilyn M.; Chapman, Chris; Stillwell, Robert; McGrath, Daniel; Peltola, Pia; Dinkes, Rachel; Xu, Zeyu

2006-01-01

This report consists of two volumes, the first takes an in-depth look at the various graduation indicators, with a description of the computational formulas, the data required for each indicator, the assumptions underlying each formula, the strengths and weaknesses of each indicator, and a consideration of the conditions under which each indicator…

Electroactive Polymers as Environmentally Benign Coating Replacements for Cadmium Plating on High Strength Steels

DTIC Science & Technology

2008-06-01

using a modified tap wrench around the square bulk section, within the required 3 to 20 seconds, with an average of approximately 10 seconds. vi...My Documents\\Wa~tz\\Zarras sa~t foq pane~s\\Stee~ 1x3 pane~s\\PZ1764-76PS 24 hrs\\b o ttom ~ eft darker area 22X. spc Labe~ :Adhesion promoter

Grout Impregnation of Pre-Placed Recycled Concrete Pavement (RCP) for Rapid Repair of Deteriorated Portland Cement Concrete Airfield Pavement

DTIC Science & Technology

2007-04-01

generation, to reduce the amount of cement required, and to provide additional tensile strength to the concrete. Although there was limited success with...generally less workable and requires more cement due to the increased water requirements. He further states that with the equipment currently...52- Table 9. Results of the Type III Grout Scoping Study Mixture Water Cement Ratio Sand Replicate Compressive Strength MPa (psi) Flow Cone

46 CFR 42.13-5 - Strength of vessel.

Code of Federal Regulations, 2010 CFR

2010-10-01

... information to the Commandant. (b) Vessels built and maintained in conformity with the requirements of a classification society recognized by the Commandant are considered to possess adequate strength for the purpose... General Rules for Determining Load Lines § 42.13-5 Strength of vessel. (a) The assigning and issuing...

47 CFR 1.544 - Application for broadcast station to conduct field strength measurements and for experimental...

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Application for broadcast station to conduct field strength measurements and for experimental operation. 1.544 Section 1.544 Telecommunication... General Filing Requirements § 1.544 Application for broadcast station to conduct field strength...

Scratch-resistant, highly conductive, and high-strength carbon nanotube-based composite yarns.

PubMed

Liu, Kai; Sun, Yinghui; Lin, Xiaoyang; Zhou, Ruifeng; Wang, Jiaping; Fan, Shoushan; Jiang, Kaili

2010-10-26

High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

Highly oriented carbon fiber–polymer composites via additive manufacturing

DOE PAGES

Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; ...

2014-10-16

Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

Alternative RF coupling configurations for H{sup −} ion sources

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

Briefi, S.; Fantz, U.; AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg

2015-04-08

RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H{sup −} current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been setmore » up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region.« less

Alternative RF coupling configurations for H- ion sources

NASA Astrophysics Data System (ADS)

Briefi, S.; Gutmann, P.; Fantz, U.

2015-04-01

RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H- current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been set up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region.

Neurocomputational account of memory and perception: Thresholded and graded signals in the hippocampus.

PubMed

Elfman, Kane W; Aly, Mariam; Yonelinas, Andrew P

2014-12-01

Recent evidence suggests that the hippocampus, a region critical for long-term memory, also supports certain forms of high-level visual perception. A seemingly paradoxical finding is that, unlike the thresholded hippocampal signals associated with memory, the hippocampus produces graded, strength-based signals in perception. This article tests a neurocomputational model of the hippocampus, based on the complementary learning systems framework, to determine if the same model can account for both memory and perception, and whether it produces the appropriate thresholded and strength-based signals in these two types of tasks. The simulations showed that the hippocampus, and most prominently the CA1 subfield, produced graded signals when required to discriminate between highly similar stimuli in a perception task, but generated thresholded patterns of activity in recognition memory. A threshold was observed in recognition memory because pattern completion occurred for only some trials and completely failed to occur for others; conversely, in perception, pattern completion always occurred because of the high degree of item similarity. These results offer a neurocomputational account of the distinct hippocampal signals associated with perception and memory, and are broadly consistent with proposals that CA1 functions as a comparator of expected versus perceived events. We conclude that the hippocampal computations required for high-level perceptual discrimination are congruous with current neurocomputational models that account for recognition memory, and fit neatly into a broader description of the role of the hippocampus for the processing of complex relational information. © 2014 Wiley Periodicals, Inc.

Study on creep of fiber reinforced ultra-high strength concrete based on strength

NASA Astrophysics Data System (ADS)

Peng, Wenjun; Wang, Tao

2018-04-01

To complement the creep performance of ultra-high strength concrete, the long creep process of fiber reinforced concrete was studied in this paper. The long-term creep process and regularity of ultra-high strength concrete with 0.5% PVA fiber under the same axial compression were analyzed by using concrete strength (C80/C100/C120) as a variable. The results show that the creep coefficient of ultra-high strength concrete decreases with the increase of concrete strength. Compared with ACI209R (92), GL2000 models, it is found that the predicted value of ACI209R (92) are close to the experimental value, and the creep prediction model suitable for this experiment is proposed based on ACI209R (92).

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

Won, Jong-Pil, E-mail: jpwon@konkuk.ac.kr; Hwang, Un-Jong; Lee, Su-Jin

This study evaluated the performance of shotcrete using high strength C{sub 12}A{sub 7} mineral-based accelerator that has been developed to improve the durability and long-term strength. Rebound, compressive strength and flexural strength were tested in the field. Test result showed that existing C{sub 12}A{sub 7} mineral-based accelerator exhibits better early strength than the high-strength C{sub 12}A{sub 7} mineral-based accelerator until the early age, but high-strength C{sub 12}A{sub 7} mineral-based accelerator shows about 29% higher at the long-term age of 28 days. Microstructural analysis such as scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption method was evaluated to analyzemore » long-term strength development mechanism of high strength C{sub 12}A{sub 7} mineral-based accelerator. As analysis result, it had more dense structure due to the reaction product by adding material that used to enhanced strength. It had better resistance performance in chloride ion penetration, freezing–thawing and carbonation than shotcrete that used existing C{sub 12}A{sub 7} mineral-based accelerator.« less

Role of Heavy Meromyosin in Heat-Induced Gelation in Low Ionic Strength Solution Containing L-Histidine.

PubMed

Hayakawa, Toru; Yoshida, Yuri; Yasui, Masanori; Ito, Toshiaki; Wakamatsu, Jun-ichi; Hattori, Akihito; Nishimura, Takanori

2015-08-01

The gelation of myosin has a very important role in meat products. We have already shown that myosin in low ionic strength solution containing L-histidine forms a transparent gel after heating. To clarify the mechanism of this unique gelation, we investigated the changes in the nature of myosin subfragments during heating in solutions with low and high ionic strengths with and without L-histidine. The hydrophobicity of myosin and heavy meromyosin (HMM) in low ionic strength solution containing L-histidine was lower than in high ionic strength solution. The SH contents of myosin and HMM in low ionic strength solution containing l-histidine did not change during the heating process, whereas in high ionic strength solution they decreased slightly. The heat-induced globular masses of HMM in low ionic strength solution containing L-histidine were smaller than those in high ionic strength solution. These findings suggested that the polymerization of HMM molecules by heating was suppressed in low ionic strength solution containing L-histidine, resulting in formation of the unique gel. © 2015 Institute of Food Technologists®

Effect of screw torque level on cortical bone pullout strength.

PubMed

Cleek, Tammy M; Reynolds, Karen J; Hearn, Trevor C

2007-02-01

The objectives of this study were 2-fold: (1) to perform detailed analysis of cortical screw tightening stiffness during automated insertion, and (2) to determine the effect of 3 torque levels on the holding strength of the bone surrounding the screw threads as assessed by screw pullout. Ten pairs of ovine tibiae were used with 3 test sites spaced 20 mm apart centered along the shaft. One side of each pair was used for measuring ultimate failure torque (Tmax). These Tmax and bone-density values were used to predict Tmax at contralateral tibia sites. Screws were inserted and tightened to 50%, 70%, and 90% of predicted Tmax at the contralateral sites to encompass the average clinical level of torque (86% Tmax). Pullout tests were performed and maximum force values were normalized by cortical thickness. Torque to failure tests indicated tightening to 86% Tmax occurs after yield and leads to an average 51% loss in stiffness. Normalized pullout strength for screws tightened to 50% Tmax, 70% Tmax, and 90% Tmax were 2525 +/- 244, 2707 +/- 280, and 2344 +/- 346 N, respectively, with a significant difference between 70% Tmax and 90% Tmax groups (P < 0.05). Within the limitations of our study involving the testing of 1 type of screw purchase in ovine tibiae, results demonstrate that clinical levels of lag screw tightening (86% Tmax) are past the yield point of bone. Tightening to these high torque levels can cause damage leading to compromised holding strength. Further research is still required to establish the appropriate level of torque required for achieving optimal fracture fixation and healing.

A cross-sectional lower-body power profile of elite and subelite Australian football players.

PubMed

Caia, Johnpaul; Doyle, Tim L A; Benson, Amanda C

2013-10-01

Australian football (AF) is a sport which requires a vast array of physiological qualities, including high levels of strength and power. However, the power characteristics of AF players, particularly at the subelite level have not been extensively studied with further investigation warranted to understand the power capabilities and training requirements of elite and subelite AF groups. Therefore, the aim of this investigation was to develop a lower-body power profile of elite and subelite AF players. Eighteen elite and 12 subelite AF players completed a 1 repetition maximum (1RM) squat test to determine maximal lower-body strength, and countermovement jump (CMJ) and squat jump (SJ) testing to assess lower-body muscular power performance. Maximal lower-body strength was not statistically different between groups (p > 0.05). Elite players produced greater levels of peak power for CMJ at loads of 0, 30 (p < 0.05), and 40% (p < 0.01) of 1RM in comparison to subelite players. Squat jump peak power was statistically different between groups at 0, 20, 30, and 40% (p < 0.01) of 1RM; with elite players producing greater power than their subelite counterparts at all measured loads for SJ. Findings from this investigation demonstrate that elite AF players are able to generate greater levels of lower-body power than subelite AF players, despite no significant differences existing in maximal lower-body strength or body mass. As lower-body power levels clearly differentiate elite and subelite AF players, emphasis may be placed on improving the power levels of subelite players, particularly those aspiring to reach the elite level.

Shear capacity of high-strength concrete pre-stressed girders.

DOT National Transportation Integrated Search

1998-05-01

As part of a project at the University of Minnesota to investigate the application of high-strength concrete in prestressed girders, four shear tests were performed on high-strength concrete prestressed girders.

Influence of V-N Microalloying on the High-Temperature Mechanical Behavior and Net Crack Defect of High Strength Weathering Steel

NASA Astrophysics Data System (ADS)

Qing, Jiasheng; Wang, Lei; Dou, Kun; Wang, Bao; Liu, Qing

2016-06-01

The influence of V-N microalloying on the high-temperature mechanical behavior of high strength weathering steel is discussed through thermomechanical simulation experiment. The difference of tensile strength caused by variation of [%V][%N] appears after proeutectoid phase change, and the higher level of [%V][%N] is, the stronger the tensile strength tends to be. The ductility trough apparently becomes deeper and wider with the increase of [%V][%N]. When the level of [%V][%N] reaches to 1.7 × 10-3, high strength weathering steel shows almost similar reduction of area to 0.03% Nb-containing steel in the temperature range of 800-900°, however, the ductility trough at the low-temperature stage is wider than that of Nb-containing steel. Moreover, the net crack defect of bloom is optimized through the stable control of N content in low range under the precondition of high strength weathering steel with sufficient strength.

Laboratory observations of fault strength in response to changes in normal stress

USGS Publications Warehouse

Kilgore, Brian D.; Lozos, Julian; Beeler, Nicholas M.; Oglesby, David

2012-01-01

Changes in fault normal stress can either inhibit or promote rupture propagation, depending on the fault geometry and on how fault shear strength varies in response to the normal stress change. A better understanding of this dependence will lead to improved earthquake simulation techniques, and ultimately, improved earthquake hazard mitigation efforts. We present the results of new laboratory experiments investigating the effects of step changes in fault normal stress on the fault shear strength during sliding, using bare Westerly granite samples, with roughened sliding surfaces, in a double direct shear apparatus. Previous experimental studies examining the shear strength following a step change in the normal stress produce contradictory results: a set of double direct shear experiments indicates that the shear strength of a fault responds immediately, and then is followed by a prolonged slip-dependent response, while a set of shock loading experiments indicates that there is no immediate component, and the response is purely gradual and slip-dependent. In our new, high-resolution experiments, we observe that the acoustic transmissivity and dilatancy of simulated faults in our tests respond immediately to changes in the normal stress, consistent with the interpretations of previous investigations, and verify an immediate increase in the area of contact between the roughened sliding surfaces as normal stress increases. However, the shear strength of the fault does not immediately increase, indicating that the new area of contact between the rough fault surfaces does not appear preloaded with any shear resistance or strength. Additional slip is required for the fault to achieve a new shear strength appropriate for its new loading conditions, consistent with previous observations made during shock loading.

R&D and Applications of V-N Microalloyed Steels in China

NASA Astrophysics Data System (ADS)

Yang, Caifu

This paper reviews the recent development of V-N microalloying technologies and its applications in HSLA steels in China. Enhanced-nitrogen in V-containing steels promotes precipitation of fine V(C,N) particles, and improves markedly precipitation strengthening effectiveness of V(C,N), therefore, there is a significant saving of V addition in a given strength requirement. V-N microalloying can be used effectively for ferrite grain refinement as well by the nucleation of intra-granular ferrite promoted by VN precipitates in Austenite in V-N steels. V-N microalloying process is a cost-effective way which has been widely used for high strength rebars, section steels, forging steels, seamless pipes, and CSP strip steels in China.

The flexibility controlling study for 3D printed splint

NASA Astrophysics Data System (ADS)

Li, Jianyou; Tanaka, Hiroya

2017-04-01

The 3D printed splint's light weight, ventilation and water proof are considered as significant improvement for patients' comfortableness. Somehow, the flexible material is required in the splint to avoid skin friction may cased by its rigid edge, but this would increase the complexity and timeconsuming. In this study, two main techniques to control the infilling densities and printing temperature are applied on printing splint prototype. The gradual increasing of infilling density from splint outside to inside would turn the partial strength from hard to flexible. Besides, higher printing temperature can also achieve stronger hardness after cooling. Such structural can provide high strength in outside surface to keep the immovable function, and give flexible touch of inside surface to decrease friction on the patient's skin.

C-Coupon Studies of CMCS: Fracture Behavior and Microstructural Characterization

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.; Calomino, Anthony M.; McCue, Terry R.; Abdul-Aziz, Ali

2001-01-01

A curved beam 'C-coupon' was used to assess fracture behavior in a Sylramic(tm)/melt infiltration (MI) SiC matrix composite. Failure stresses and fracture mechanisms, as determined by optical and scanning electron microstructural analysis, are compared with finite element stress calculations to analyze failure modes. Material microstructure was found to have a strong influence on mechanical behavior. Fracture occurs in interlaminar tension (ILT), provided that the ratio of ILT to tensile strength for the material is less than the ratio of radial to hoop stresses for the C-coupon geometry. Utilization of 3D architectures to improve interlaminar strength requires significant development efforts to incorporate through thickness fibers in regions with high curvatures while maintaining uniform thickness, radius, and microstructure.

Consolidation of Si3N4 without additives (by hot isostatic pressing)

NASA Technical Reports Server (NTRS)

Yeh, H. C.

1983-01-01

The potential of using hot isostatic pressing (HIP'ing) technique to produce dense silicon nitride materials without or with a reduced amount of additives (much less than 5 w/o) was investigated. Hot isostatic pressing technique can provide higher pressure and temperature than hot pressing can, thus has the potential of requiring less densification aids to consolidate Si3N4 materials. It was anticipated that if such dense materials could be fabricated, the high temperature strength of the material should be improved significantly. Observations on the phase transformation, densification behavior, and microstructures of the samples are also documented. Density, microhardness, four point bend strength (room temperature and 1370 C) were measured on selected densified materials.

Improved capacitive stress transducers for high-field superconducting magnets

NASA Astrophysics Data System (ADS)

Benson, Christopher Pete; Holik, Eddie Frank, III; Jaisle, Andrew; McInturff, A.; McIntyre, P.

2012-06-01

High-field (12-18 Tesla) superconducting magnets are required to enable an increase in the energy of future colliders. Such field strength requires the use of Nb3Sn superconductor, which has limited tolerance for compressive and shear strain. A strategy for stress management has been developed at Texas A&M University and is being implemented in TAMU3, a short-model 14 Tesla stress-managed Nb3Sn block dipole. The strategy includes the use of laminar capacitive stress transducers to monitor the stresses within the coil package. We have developed fabrication techniques and fixtures, which improve the reproducibility of the transducer response both at room temperature and during cryogenic operation. This is a report of the status of transducer development.

A timely rationale for space exploration

NASA Technical Reports Server (NTRS)

Peterson, Douglas D.; Walters, Larry D.

1992-01-01

Space exploration is shown to be useful for enhancing a country's education, technology, and economic competitiveness. Technologies required for the Space Exploration Initiative are compared to emerging technologies identified by the U.S. Department of Commerce. The impact of previous space ventures on specific technologies are illustrated with examples such as miniaturized electronics, computers and software, and high-strength materials. The case for educational advancement as a by-product of space exploration is made by discussing the high-level requirements of the programs and describing the inspirational effect of space exploration on young students. Invigorating space exploration is argued to generate near- and long-term economic opportunities for key sectors of the national economy by means of technology transfer, space-resource utilization, and the commercialization of space.

High Integrity Castings: Proceedings of the Conference on Advances in High Integrity Castings Held in Conjunction with the 1988 World Materials Congress, Chicago, Illinois, USA, 24-30 September 1988

DTIC Science & Technology

1988-01-01

above design requirements. The The first cast parts used in this higher strength standard chemistry parts application were of the Extra Low...present work was to study the use of beta THE HIGH COST OF TITANIUM alloys can limit their titanium alloys in the cast form. Beta or use to applications ...refractory as was is intended to achieve a pouring stream su- used with the nozzles for steel applications . perior to conventional nozzle designs , and this

Determining Exercise Strength Requirements for Astronaut Critical Mission Tasks: Reaching Under G-Load

NASA Technical Reports Server (NTRS)

Schaffner, Grant; Bentley, Jason

2008-01-01

The critical mission tasks assessments effort seeks to determine the physical performance requirements that astronauts must meet in order to safely and successfully accomplish lunar exploration missions. These assessments will determine astronaut preflight strength, fitness, and flexibility requirements, and the extent to which exercise and other countermeasures must prevent the physical deconditioning associated with prolonged weightlessness. The purpose is to determine the flexibility and strength that crewmembers must possess in order to reach Crew Exploration Vehicle controls during maneuvers that result in sustained acceleration levels ranging from 3.7G to 7.8G. An industry standard multibody dynamics application was used to create human models representing a 5th percentile female, a 50th percentile male, and a 95th percentile male. The additional mass of a space suit sleeve was added to the reaching arm to account for the influence of the suit mass on the reaching effort. The human model was merged with computer models of a pilot seat and control panel for the Crew Exploration Vehicle. Three dimensional paths were created that guided the human models hand from a starting position alongside its thigh to three control targets: a joystick, a keyboard, and an overhead switch panel. The reaching motion to each target was repeated under four vehicle acceleration conditions: nominal ascent (3.7G), two ascent aborts (5.5G and 7.8G) and lunar reentry (4.6G). Elbow and shoulder joint angular excursions were analyzed to assess range of motion requirements. Mean and peak elbow and shoulder joint torques were determined and converted to equivalent resistive exercise loads to assess strength requirements. Angular excursions for the 50th and 95th percentile male models remained within joint range of motion limits. For the 5th percentile female, both the elbow and the shoulder exceeded range of motion limits during the overhead reach. Elbow joint torques ranged from 10 N-m (nominal ascent) to 60 N-m (ascent abort). Shoulder joint torques ranged from 65 N-m (nominal ascent) to 280 N-m (ascent abort). Maximal equivalent exercise loads reached 30 lb in tricep extension, 9 lb in bicep curl, 110 lb in unilateral pullover and unilateral bench press for nominal conditions (lunar reentry), and 188 lb in unilateral pullover and unilateral bench press. The location of the pilot seat was found to be inadequately located to allow a 5th percentile female to reach the switches on the overhead panel. Elbow strength requirements were found to be well within population norms. Shoulder strength was found to be a limiting factor. Reaching under nominal ascent and lunar reentry conditions was found to require near maximal shoulder strength. Reaching under ascent abort conditions requires shoulder strength well beyond population norms. Pilot seats must adjust to accomodate a 5th percentile female. Exercise countermeasures must maintain maximal pullover and bench press strength to allow pilots to reach and operate controls during lunar reentry. Reaching will not be possible during ascent abort conditions. Flight controls should be built into armrests or flight control must be accomplished by autonomous systems during acceleration exceeding 4.6G.

Development and Evaluation of Elastomeric Materials for Geothermal Applications

NASA Technical Reports Server (NTRS)

Mueller, W. A.; Kalfayan, S. H.; Reilly, W. W.; Yavrouian, A. H.; Mosesman, I. D.; Ingham, J. D.

1979-01-01

A material was formulated having about 250-350 psi tensile strength and 30-80 percent elongation at 260 C for at least 24 hours in simulated brine. The relationship between these laboratory test results and sealing performance in actual or simulated test conditions is not entirely clear; however, it is believed that no conventional formation or casing packer design is likely to perform well using these materials. The synthetic effort focused on high temperature block copolymers and development of curable polystyrene. Procedures were worked out for synthesizing these new materials. Initial results with heat-cured unfilled polystyrene 'gum' at 260 C indicate a tensile strength of about 50 psi. Cast films of the first sample of polyphenyl quinoxaline-polystyrene block copolymer, which has 'graft-block' structure consisting of a polystyrene chain with pendant polyphenyl quinoxaline groups, show elastomeric behavior in the required temperature range. Its tensile strength and elongation at 260 C were 220-350 psi and 18-36 percent, respectively. All of these materials also showed satisfactory hydrolytic stability.

Improvement of mechanical properties on metastable stainless steels by reversion heat treatments

NASA Astrophysics Data System (ADS)

Mateo, A.; Zapata, A.; Fargas, G.

2013-12-01

AISI 301LN is a metastable austenitic stainless steel that offers an excellent combination of high strength and ductility. This stainless grade is currently used in applications where severe forming operations are required, such as automotive bodies. When these metastable steels are plastically deformed at room temperature, for example by cold rolling, austenite transforms to martensite and, as a result, yield strength increases but ductility is reduced. Grain refinement is the only method that allows improving strength and ductility simultaneously. Several researchers have demonstrated that fine grain AISI 301LN can be obtained by heat treatment after cold rolling. This heat treatment is called reversion because it provokes the reversion of strain induced martensite to austenite. In the present work, sheets of AISI 301LN previously subjected to 20% of cold rolling reduction were treated and a refined grain austenitic microstructure was obtained. Mechanical properties, including fatigue limit, were determined and compared with those corresponding to the steel both before and after the cold rolling.

Development and testing of passive tracking markers for different field strengths and tracking speeds.

PubMed

Peeters, J M; Seppenwoolde, J-H; Bartels, L W; Bakker, C J G

2006-03-21

Susceptibility markers for passive tracking need to be small in order to maintain the shape and mechanical properties of the endovascular device. Nevertheless, they also must have a high magnetic moment to induce an adequate artefact at a variety of scan techniques, tracking speeds and, preferably, field strengths. Paramagnetic markers do not satisfy all of these requirements. Ferro- and ferrimagnetic materials were therefore investigated with a vibrating sample magnetometer and compared with the strongly paramagnetic dysprosium oxide. Results indicated that the magnetic behaviour of stainless steel type AISI 410 corresponds the best with ideal marker properties. Markers with different magnetic moments were constructed and tested in in vitro and in vivo experiments. The appearance of the corresponding artefacts was field strength independent above magnetic saturation of 1.5 T. Generally, the contrast-to-noise ratio decreased at increasing tracking speed and decreasing magnetic moment. Device depiction was most consistent at a frame rate of 20 frames per second.

Low Temperature Regolith Bricks for In-Situ Structural Material

NASA Technical Reports Server (NTRS)

Grossman, Kevin; Sakthivel, Tamil S.; Mantovani, James; Seal, Sudipta

2016-01-01

Current technology for producing in-situ structural materials on future missions to Mars or the moon relies heavily on energy-intensive sintering processes to produce solid bricks from regolith. This process requires heating the material up to temperatures in excess of 1000 C and results in solid regolith pieces with compressive strengths in the range of 14000 to 28000 psi, but are heavily dependent on the porosity of the final material and are brittle. This method is currently preferred over a low temperature cementation process to prevent consumption of precious water and other non-renewable materials. A high strength structural material with low energy requirements is still needed for future colonization of other planets. To fulfill these requirements, a nano-functionalization process has been developed to produce structural bricks from regolith simulant and shows promising mechanical strength results. Functionalization of granular silicate particles into alkoxides using a simple low temperature chemical process produces a high surface area zeolite particles that are held together via inter-particle oxygen bonding. Addition of water in the resulting zeolite particles produces a sol-gel reaction called "inorganic polymerization" which gives a strong solid material after a curing process at 60 C. The aqueous solution by-product of the reaction is currently being investigated for its reusability; an essential component of any ISRU technology. For this study, two batches of regolith bricks are synthesized from JSC-1A; the first batch from fresh solvents and chemicals, the second batch made from the water solution by-product of the first batch. This is done to determine the feasibility of recycling necessary components of the synthesis process, mainly water. Characterization including BET surface area, SEM, and EDS has been done on the regolith bricks as well as the constituent particles,. The specific surface area of 17.53 sq m/g (average) of the granular regolith material was obtained from nitrogen adsorption isotherm measurement. The size, shape and textures of regolith from SEM shows that the particles are 25-50 micrometers in size and mostly irregular in shape (Figure 1a). The elemental composition of regolith was identified from EDS analysis showed the presence of Si, Al, Fe, Na, Mg, Ca, Ti, O and C (see figure 1b). Each set of cylindrical brick samples were prepared by low energy process, and cured for 21 and 28 days, respectively to compare their compressive strength. Figure 1c, and d shows the JSC-1A brick and the compressive strength measurements. The results from the 21 day cured bricks (2 bricks) have been done and yielded an aver-age strength of 3050 psi, considerably higher than Portland cement mortars (Type IV and V). This promising technology provides the benefits of construction material similar to concrete, with a low complexity, low energy synthesis process and the likelihood of complete reusability of precious resources. Compressive strength using this method can be improved by increasing the surface area of the particles, using bi-modal particle size distribution, and adding certain additives to increase inter-particle forces.

Passive shimming of the fringe field of a superconducting magnet for ultra-low field hyperpolarized noble gas MRI.

PubMed

Parra-Robles, Juan; Cross, Albert R; Santyr, Giles E

2005-05-01

Hyperpolarized noble gases (HNGs) provide exciting possibilities for MR imaging at ultra-low magnetic field strengths (<0.15 T) due to the extremely high polarizations available from optical pumping. The fringe field of many superconductive magnets used in clinical MR imaging can provide a stable magnetic field for this purpose. In addition to offering the benefit of HNG MR imaging alongside conventional high field proton MRI, this approach offers the other useful advantage of providing different field strengths at different distances from the magnet. However, the extremely strong field gradients associated with the fringe field present a major challenge for imaging since impractically high active shim currents would be required to achieve the necessary homogeneity. In this work, a simple passive shimming method based on the placement of a small number of ferromagnetic pieces is proposed to reduce the fringe field inhomogeneities to a level that can be corrected using standard active shims. The method explicitly takes into account the strong variations of the field over the volume of the ferromagnetic pieces used to shim. The method is used to obtain spectra in the fringe field of a high-field (1.89 T) superconducting magnet from hyperpolarized 129Xe gas samples at two different ultra-low field strengths (8.5 and 17 mT). The linewidths of spectra measured from imaging phantoms (30 Hz) indicate a homogeneity sufficient for MRI of the rat lung.

The strength of compressed structures with CFRP materials reinforcement when exceeding the cross-section size

NASA Astrophysics Data System (ADS)

Polskoy, Petr; Mailyan, Dmitry; Georgiev, Sergey; Muradyan, Viktor

2018-03-01

The increase of high-rise construction volume or «High-Rise Construction» requires the use of high-strength concrete and that leads to the reduction in section size of structures and to the decrease in material consumption. First of all, it refers to the compressed elements for which, when the transverse dimensions are reduced, their flexibility and deformation increase but the load bearing capacity decreases. Growth in construction also leads to the increase of repair and restoration works or to the strengthening of structures. The most effective method of their strengthening in buildings of «High-Rise Construction» is the use of composite materials which reduces the weight of reinforcement elements and labour costs on execution of works. In this article the results of experimental research on strength and deformation of short compressed reinforced concrete structures, reinforced with external carbon fiber reinforcement, are presented. Their flexibility is λh=10, and the cross-section dimensions ratio b/h is 2, that is 1,5 times more, than recommended by standards in Russia. The following research was being done for three kinds of strained and deformed conditions with different variants of composite reinforcement. The results of the experiment proved the real efficiency of composite reinforcement of the compressed elements with sides ratio equal to 2, increasing the bearing capacity of pillars till 1,5 times. These results can be used for designing the buildings of different number of storeys.

Analysis of Clinicians' Perceptual Cough Evaluation.

PubMed

Laciuga, Helena; Brandimore, Alexandra E; Troche, Michelle S; Hegland, Karen W

2016-08-01

This study examined the relationships between subjective descriptors and objective airflow measures of cough. We hypothesized that coughs with specific airflow characteristics would share common subjective perceptual descriptions. Thirty clinicians (speech-language pathologists, otolaryngologists, and neurologists) perceptually evaluated ten cough audio samples with specific airflow characteristics determined by peak expiratory flow rate, cough expired volume, cough duration, and number of coughs in the cough epoch. Participants rated coughs by strength, duration, quality, quantity, and overall potential effectiveness for airway protection. Perception of cough strength and effectiveness was determined by the combination of presence of pre-expulsive compression phase, short peak expiratory airflow rate rise time, high peak expiratory flow rates, and high cough volume acceleration. Perception of cough abnormality was defined predominantly by descriptors of breathiness and strain. Breathiness was characteristic for coughs with either absent compression phases and relatively high expiratory airflow rates or coughs with significantly low expired volumes and reduced peak flow rates. In contrast, excessive strain was associated with prolonged compression phases and low expiratory airflow rates or the absence of compression phase with high peak expiratory rates. The study participants reached greatest agreement in distinguishing between single and multiple coughs. Their assessment of cough strength and effectiveness was less consistent. Finally, the least agreement was shown in determining the quality categories. Modifications of cough airflow can influence perceptual cough evaluation outcomes. However, the inconsistency of cough ratings among our participants suggests that a uniform cough rating system is required.

Trabecular Bone Strength Predictions of HR-pQCT and Individual Trabeculae Segmentation (ITS)-Based Plate and Rod Finite Element Model Discriminate Postmenopausal Vertebral Fractures

PubMed Central

Liu, X. Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X. Edward

2013-01-01

While high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (μFE) prediction of yield strength by HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high resolution μCT voxel model of 19 trabecular sub-volumes from human cadaveric tibiae samples. Both Young’s modulus and yield strength of HR-pQCT PR models strongly correlated with those of μCT voxel models (r2=0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and CPU time (>1,200-fold). Then, we applied PR model μFE analysis to HR-pQCT images of 60 postmenopausal women with (n=30) and without (n=30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young’s modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for aBMD T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against μCT voxel models and demonstrated its ability to discriminate vertebral fracture status in postmenopausal women. This accurate nonlinear μFE prediction of HR-pQCT PR model, which requires only seconds of desktop computer time, has tremendous promise for clinical assessment of bone strength. PMID:23456922

Remote magnetic actuation using a clinical scale system

PubMed Central

Stehning, Christian; Gleich, Bernhard

2018-01-01

Remote magnetic manipulation is a powerful technique for controlling devices inside the human body. It enables actuation and locomotion of tethered and untethered objects without the need for a local power supply. In clinical applications, it is used for active steering of catheters in medical interventions such as cardiac ablation for arrhythmia treatment and for steering of camera pills in the gastro-intestinal tract for diagnostic video acquisition. For these applications, specialized clinical-scale field applicators have been developed, which are rather limited in terms of field strength and flexibility of field application. For a general-purpose field applicator, flexible field generation is required at high field strengths as well as high field gradients to enable the generation of both torques and forces on magnetic devices. To date, this requirement has only been met by small-scale experimental systems. We have built a highly versatile clinical-scale field applicator that enables the generation of strong magnetic fields as well as strong field gradients over a large workspace. We demonstrate the capabilities of this coil-based system by remote steering of magnetic drills through gel and tissue samples with high torques on well-defined curved trajectories. We also give initial proof that, when equipped with high frequency transmit-receive coils, the machine is capable of real-time magnetic particle imaging while retaining a clinical-scale bore size. Our findings open the door for image-guided radiation-free remote magnetic control of devices at the clinical scale, which may be useful in minimally invasive diagnostic and therapeutic medical interventions. PMID:29494647

New Forming Technologies for Autobody at POSCO

NASA Astrophysics Data System (ADS)

Lee, Hong-Woo; Cha, Myung-Hwan; Choi, Byung-Keun; Kim, Gyo-Sung; Park, Sung-Ho

2011-08-01

As development of car body with light weight and enhanced safety became one of the hottest issues in the auto industry, the advanced high strength steels have been broadly applied to various automotive parts over the last few years. Corresponding to this trend, POSCO has developed various types of cold and hot rolled AHSSs such as DP, TRIP, CP and FB, and continues to develop new types of steel in order to satisfy the requirement of OEMs more extensively. To provide optimal technical supports to customers, POSCO has developed more advanced EVI concept, which includes the concept of CE/SE, VA/VE, VI and PP as well as the conventional EVI strategy. To realize this concept, POSCO not only supports customers with material data, process guideline, and evaluation of formability, weld-ability, paint-ability and performance but also provides parts or sub-assemblies which demand highly advanced technologies. Especially, to accelerate adoption of AHSS in autobody, POSCO has tried to come up with optimal solutions to AHSS forming. Application of conventional forming technologies has been restricted more and more by relatively low formability of AHSS with high tensile-strength. To overcome the limitation in the forming, POSCO has recently developed new forming technologies such as hydro-forming, hot press forming, roll forming and form forming. In this paper, tailored strength HPF, hydroformed torsion beam axle and multi-directional roll forming are introduced as examples of new forming technologies.

The magnetic fields, ages, and original spin periods of millisecond pulsars

NASA Technical Reports Server (NTRS)

Camilo, F.; Thorsett, S. E.; Kulkarni, S. R.

1994-01-01

Accurate determination of the spin-down rates of millisecond pulsars requires consideration of the apparent acceleration of the pulsars due to their high transverse velocities. We show that for several nearby pulsars the neglect of this effect leads to substantial errors in inferred pulsar ages and magnetic fields. Two important ramifications follow. (1) The intrinsic magnetic field strengths of all millisecond pulsars lie below 5 x 10(exp 8) G, strengthening an earlier suggestion of a 'gap' between the magnetic field strengths of millisecond pulsars and of high-mass binary pulsars such as PSR B1913+16, which are thought to have been formed by mass transfer in low-mass and high-mass X-ray binaries, respectively. This result suggests that the magnetic field strengths of recycled pulsars are related to their formation and evolution in binary systems. (2) The corrected characteristic ages of several millisecond pulsars appear to be greater than the age of the Galactic disk. We reconcile this apparent paradox by suggesting that some millisecond pulsars were born with periods close to their current periods. This conclusion has important implications for the interpretation of the cooling ages of white dwarf companions, the birthrate discrepancy between millisecond pulsars and their X-ray binary progenitors, and the possible existence of a class of weakly magnetized (B much less than 10(exp 8)G), rapidly rotating neutron stars.

Familiarization, validity and smallest detectable difference of the isometric squat test in evaluating maximal strength.

PubMed

Drake, David; Kennedy, Rodney; Wallace, Eric

2018-02-06

Isometric multi-joint tests are considered reliable and have strong relationships with 1RM performance. However, limited evidence is available for the isometric squat in terms of effects of familiarization and reliability. This study aimed to assess, the effect of familiarization, stability reliability, determine the smallest detectible difference, and the correlation of the isometric squat test with 1RM squat performance. Thirty-six strength-trained participants volunteered to take part in this study. Following three familiarization sessions, test-retest reliability was evaluated with a 48-hour window between each time point. Isometric squat peak, net and relative force were assessed. Results showed three familiarizations were required, isometric squat had a high level of stability reliability and smallest detectible difference of 11% for peak and relative force. Isometric strength at a knee angle of ninety degrees had a strong significant relationship with 1RM squat performance. In conclusion, the isometric squat is a valid test to assess multi-joint strength and can discriminate between strong and weak 1RM squat performance. Changes greater than 11% in peak and relative isometric squat performance should be considered as meaningful in participants who are familiar with the test.

Solubilization of myofibrillar proteins in water or low ionic strength media: Classical techniques, basic principles, and novel functionalities.

PubMed

Chen, Xing; Tume, Ron K; Xu, Xinglian; Zhou, Guanghong

2017-10-13

The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50% of total muscle proteins, are generally considered to be insoluble in solutions of low ionic strength (< 0.2 M), requiring high concentrations of salt (> 0.3 M) for solubilization. These soluble proteins are the ones which determine many functional properties of meat products, including emulsification and thermal gelation. In order to increase the utilization of meat and meat products, many studies have investigated the solubilization of MPs in water or low ionic strength media and determining their functionality. However, there still remains a lack of systematic information on the functional properties of MPs solubilized in this manner. Hence, this review will explore some typical techniques that have been used. The main procedures used for their solubilization, the fundamental principles and their functionalities in water (low ionic strength medium) are comprehensively discussed. In addition, advantages and disadvantages of each technique are summarized. Finally, future considerations are presented to facilitate progress in this new area and to enable water soluble muscle MPs to be utilized as novel meat ingredients in the food industry.

Effects of processing parameters on the friction stir spot joining of Al5083-O aluminum alloy to DP590 steel

NASA Astrophysics Data System (ADS)

Sung, Back-Sub; Bang, Hee-Seon; Jeong, Su-Ok; Choi, Woo-Seong; Kwon, Yong-Hyuk; Bang, Han-Sur

2017-05-01

Two dissimilar materials, aluminum alloy Al5083-O and advanced high strength steel DP590, were successfully joined by using friction stir spot joining (FSSJ). Satisfactory joint strengths were obtained at a rotational speed of 300 rpm and a plunge depth of 0.7 mm. Resulting joints were welded without a non-welded zone. This may be attributed to the enhanced smooth material flow owing to sufficient stirring effect and tool down force between the upper Al5083-O side and the lower DP590 side. The maximum tensile shear strength was 6.5 kN, which was higher than the joint strength required by the conventional method of resistance spot welding. The main fracture mode was plug fracture in the tensile shear test of joints. An intermetallic compound (IMC) layer with <6 μm thickness was formed at the joint interface, which meets the allowance value of <10 μm for the dissimilar material Al-Fe joints. Thus, the use of FSSJ to weld the dissimilar materials Al5083-O and DP590 resulted in mechanically and metallurgically sound joints.

Plasma immersion ion implantation on 15-5PH stainless steel: influence on fatigue strength and wear resistance

NASA Astrophysics Data System (ADS)

Bonora, R.; Cioffi, M. O. H.; Voorwald, H. J. C.

2017-05-01

Surface improvement in steels is of great interest for applications in industry. The aim of this investigation is to study the effect of nitrogen ion implantation on the axial fatigue strength and wear resistance of 15-5 PH stainless steel. It is well know that electroplated coatings, which are used to improve abrasive wear and corrosion properties, affects negatively the fatigue strength. It is also important to consider requirements to reduce the use of coated materials with electroplated chromium and cadmium, that produce waste, which is harmful to health and environment. The HVOF (High velocity oxygen fuel) process provides hardness, wear strength and higher fatigue resistance in comparison to electroplated chromium. Plasma immersion ion implantation has been used to enhance the hardness, wear, fatigue and corrosion properties of metals and alloys. In the present research the fatigue life increased twice for 15-5 PH three hours PIII treated in comparison to base material. From the abrasive wear tests a lower pin mass reduction was observed, associated to the superficial treatments. The improvement of fatigue and mechanical performance is attributed to a combination of nitrides phase structure and compressive residual stresses during the PIII treatment.

Mechanical properties and durability of crumb rubber concrete

NASA Astrophysics Data System (ADS)

Chylík, Roman; Trtík, Tomáš; Fládr, Josef; Bílý, Petr

2017-09-01

This paper is focused on concrete with admixture of rubber powder, generally called crumb rubber concrete (CRC). The inspiration was found in Arizona, where one of the first CRCs has been created. However, Arizona has completely different climates than Central Europe. Could we use the crumb rubber concrete on construction applications in the Central European climate too? The paper evaluates the influence of the rubber powder on material characteristics and durability of CRC. CRCs with various contents of fine and coarse crumb powder were compared. The tested parameters were slump, air content, permeability, resistance of concrete to water with deicing chemicals, compressive and splitting tensile strength. The tests showed that workability, compressive strength and permeability decreased as the amount of rubber increased, but the air content increased as the rubber content increased. Photos of air voids in cement matrix from electron microscope were captured. The results of laboratory tests showed that admixture of rubber powder in concrete could have a positive impact on durability of concrete and concurrently contribute to sustainable development. Considering the lower compressive strength, CRC is recommended for use in applications where the high strength of concrete is not required.

Nanocrystalline High-Entropy Alloys: A New Paradigm in High-Temperature Strength and Stability.

PubMed

Zou, Yu; Wheeler, Jeffrey M; Ma, Huan; Okle, Philipp; Spolenak, Ralph

2017-03-08

Metals with nanometer-scale grains or nanocrystalline metals exhibit high strengths at ambient conditions, yet their strengths substantially decrease with increasing temperature, rendering them unsuitable for usage at high temperatures. Here, we show that a nanocrystalline high-entropy alloy (HEA) retains an extraordinarily high yield strength over 5 GPa up to 600 °C, 1 order of magnitude higher than that of its coarse-grained form and 5 times higher than that of its single-crystalline equivalent. As a result, such nanostructured HEAs reveal strengthening figures of merit-normalized strength by the shear modulus above 1/50 and strength-to-density ratios above 0.4 MJ/kg, which are substantially higher than any previously reported values for nanocrystalline metals in the same homologous temperature range, as well as low strain-rate sensitivity of ∼0.005. Nanocrystalline HEAs with these properties represent a new class of nanomaterials for high-stress and high-temperature applications in aerospace, civilian infrastructure, and energy sectors.

An Analysis of Strengthening Mechanisms and Rate-Dependence in a High Strength Aluminum Alloy

NASA Astrophysics Data System (ADS)

Cao, B.; Shaeffer, M.; Cadel, D.; Ramesh, K. T.; Prasad, S.

2017-11-01

We examine the strengthening mechanisms within a high-strength aluminum alloy with the objective of providing guidelines for increased strength. First, we measure the mechanical behavior of the age-hardenable Al-Cu-Mg-Ag alloy known as Al 2139 in the T8 condition, and observe strengths of 500 MPa at quasistatic strain rates and average strengths of up to 600 MPa at high strain rates. Next, we explore the reasons for the high strength of this alloy by considering the contributions of various strengthening mechanisms to the total strength of the material. Finally, we develop an analytical approach to estimating the strengthening developed through the mechanism of dislocation cutting of closely spaced plate-like semi-coherent precipitates. Our results suggest that dislocation cutting of the Ω phase is the primary strengthening mechanism in this alloy.

Radial turbine cooling

NASA Technical Reports Server (NTRS)

Roelke, Richard J.

1992-01-01

Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

BIOMECHANICAL DIFFERENCES IN BRAZILIAN JIU-JITSU ATHLETES: THE ROLE OF COMBAT STYLE.

PubMed

Lima, Pedro Olavo de Paula; Lima, Alane Almeida; Coelho, Anita Camila Sampaio; Lima, Yuri Lopes; Almeida, Gabriel Peixoto Leão; Bezerra, Márcio Almeida; de Oliveira, Rodrigo Ribeiro

2017-02-01

Brazilian Jiu-Jitsu (BJJ) athletes can be divided into two combat styles: pass fighters (PFs) and guard fighters (GFs). Flexibility of the posterior chain muscles is highly necessary in these athletes, especially in GFs. On the other hand, isometric strength of the trunk extensors is required in PFs. Handgrip strength is important in holding the kimono of the opponent, and symmetrical lower-limb strength is important for the prevention of injuries due to the overload caused by training. The aim of this study was to compare the biomechanical profiles of BJJ athletes with different combat styles using the following outcome measures: flexibility, trunk extensor isometric endurance, postural balance, handgrip isometric endurance and lower-limb muscle strength. A cross-sectional study was conducted using 19 GFs and 19 PFs. The sit-and-reach test was used to evaluate the flexibility of the posterior chain muscles. The Biodex Balance System® was used to evaluate balance. A handgrip dynamometer and a dorsal dynamometer were used to evaluate handgrip and trunk extensor endurance, respectively. Quadriceps and hamstring strength were evaluated with an isokinetic dynamometer at 60 °/s. No differences were observed between groups in terms of flexibility, balance, handgrip isometric endurance or quadriceps and hamstring strength; however, PFs (81.33) showed more isometric trunk extension endurance than GFs (68.85) ( p = 0.02). Both groups had low values for hamstring/quadriceps ratio. No significant biomechanical differences were observed between PFs and GFs. 2b.

Moving from Pathology to Possibility: Integrating Strengths-Based Interventions in Child Welfare Provision

ERIC Educational Resources Information Center

Sabalauskas, Kara L.; Ortolani, Charles L.; McCall, Matthew J.

2014-01-01

Child welfare providers are increasingly required to demonstrate that strengths-based, evidence-informed practices are central to their intervention methodology. This case study describes how a large child welfare agency instituted cognitive behavioural therapy (CBT) as the core component of a strength-based practice model with the goal of…

Fabrication of High Strength Lightweight Metals for Armor and Structural Applications: Large Scale Equal Channel Angular Extrusion Processing of Aluminum 5083 Alloy

DTIC Science & Technology

2017-06-01

ARL-TR-8047 ● JUNE 2017 US Army Research Laboratory Fabrication of High -Strength Lightweight Metals for Armor and Structural...to the originator. ARL-TR-8047 ● JUNE 2017 US Army Research Laboratory Fabrication of High -Strength Lightweight Metals for...Fabrication of High -Strength Lightweight Metals for Armor and Structural Applications: Large-Scale Equal Channel Angular Extrusion Processing of

The Effects of Extravehicular Activity (EVA) Glove Pressure on Hand Strength

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar; Mesloh, Miranda; Thompson, Shelby; England, Scott; Benson, Liz

2009-01-01

With the new vision of space travel aimed at traveling back to the Moon and eventually to Mars, NASA is designing a new spacesuit glove. The purpose of this study was to baseline hand strength while wearing the current Extravehicular Activity (EVA) glove, the Phase VI. By varying the pressure in the glove, hand strength could be characterized as a function of spacesuit pressure. This finding is of extreme importance when evaluating missions that require varying suit pressures associated with different operations within NASA's current human spaceflight program, Constellation. This characterization fed directly into the derivation of requirements for the next EVA glove. This study captured three types of maximum hand strength: grip, lateral pinch, and pulp-2 pinch. All three strengths were measured under varying pressures and compared to a bare-hand condition. The resulting standardized data was reported as a percentage of the bare-hand strength. The first wave of tests was performed while the subjects, four female and four male, were wearing an Extravehicular Mobility Unit (EMU) suit supported by a suit stand. This portion of the test collected data from the barehand, suited unpressurized, and suited pressurized (4.3 psi) conditions. In addition, the effects of the Thermal Micrometeoroid Garment (TMG) on hand strength were examined, with the suited unpressurized and pressurized cases tested with and without a TMG. It was found that, when pressurized and with the TMG, the Phase VI glove reduced applied grip strength to a little more than half of the subject s bare-hand strength. The lateral pinch strength remained relatively constant while the pulp-2 pinch strength actually increased with pressure. The TMG was found to decrease maximum applied grip strength by an additional 10% for both pressurized and unpressurized cases, while the pinch strengths saw little to no change. In developing requirements based on human subjects, it is important to attempt to derive results that encompass the variation within the entire population. The current EMU does not accommodate humans at the extremes of the anthropometric spectrum. To account for this and to ensure that these requirements cover the population, another phase of testing will be conducted in a differential pressure glove box. This phase will focus on smaller females and very large males that do not have a properly fitted EMU suit. Instead, they would wear smaller or larger gloves and be tested in the glove box as a means to compare and contrast their strength capabilities against the EMU accommodated hand size subjects. The glove box s ability to change pressures easily will also allow for a wider range of glove pressures to be tested. Compared to the data collected on the subjects wearing the EMU suit, it is expected that there will be similar ratios to bare-hand. It is recommended that this topic be sent to the Physical Ergonomics Board for review.

The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating

PubMed Central

2017-01-01

Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation) of 30.44 (5.35) years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI), hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C) and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove). The data were analyzed using the Shapiro–Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA) of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C) had a significant influence on grip when compared to medium (25 °C) and high (45 °C) hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves. PMID:29207573

Psychological distress, television viewing, and physical activity in children aged 4 to 12 years.

PubMed

Hamer, Mark; Stamatakis, Emmanuel; Mishra, Gita

2009-05-01

Sedentary behavior and physical activity may be independent risk factors for psychological distress in adolescents, although there is no existing information for children. We examined the cross-sectional association between psychological distress, television and screen entertainment time, and physical activity levels among a representative sample of children aged 4 to 12 years from the 2003 Scottish Health Survey. Participants were 1486 boys and girls (mean age: 8.5 +/- 2.3 years). Parents answered on behalf of children who were required to be present. The parents completed the Strengths and Difficulties Questionnaire and information on television and screen entertainment time, physical activity, and dietary intake of their children. An abnormally high Strengths and Difficulties Questionnaire total difficulties score (20-40) was found in 4.2% of the sample. Approximately 25% of the children were exposed to television and screen entertainment at least 3 hours/day. In general linear models, television and screen entertainment time per week and physical activity levels were independently associated with the Strengths and Difficulties Questionnaire total difficulties score after adjustment for age, gender, area deprivation level, single-parent status, medical conditions, and various dietary intake indicators. There was also an additive interaction effect showing that the combination of high television and screen entertainment time and low physical activity was associated with the highest Strengths and Difficulties Questionnaire score. Higher television and screen entertainment exposure (>2.7 hours/day) alone resulted in a 24% increase in the Strengths and Difficulties Questionnaire score in comparison with lower television and screen entertainment exposure (<1.6 hours/day), although when combined with low physical activity this resulted in a 46% increase. Higher levels of television and screen entertainment time and low physical activity levels interact to increase psychological distress in young children.

Premixed calcium phosphate cements: synthesis, physical properties, and cell cytotoxicity.

PubMed

Xu, Hockin H K; Carey, Lisa E; Simon, Carl G; Takagi, Shozo; Chow, Laurence C

2007-04-01

Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder-liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability. PCPCs were formulated from CPC powder+non-aqueous liquid+gelling agent+hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility. Setting time (mean+/-S.D.; n=4) for PCPC-Tartaric was 8.2+/-0.8 min, significantly less than the 61.7+/-1.5 min for the Premixed Control developed previously (p<0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5+/-0.8 MPa, higher than 4.5+/-0.8 MPa of Premixed Control (p=0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p=0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p>0.1) from that of the non-premixed CPC control. PCPCs will eliminate the powder-liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs.

Resistance training status and effectiveness of low frequency resistance training on upper-body strength and power in highly trained soccer players.

PubMed

Hertzog, Maxime; Rumpf, Michael Clemens; Hader, Karim

2017-08-26

Soccer is classified as a contact/collision sport with many player-to-player duels. Winning these duels, shielding the ball or fending off an opponent requires upper-body strength and power. Therefore this study aimed, a) to examine the time-related effect of an upper-body RT on maximal strength and power changes in highly trained soccer players, b) to investigate if the resistance-training (RT) status influences these changes throughout a competitive season. Twenty-eight soccer players participated in this study and were divided into an untrained (UG) and a trained (TG) group, according to their RT status. Both groups performed the same upper-body RT once a week, over 30 weeks. Maximal strength (1RM) and maximal power (MP) were assessed before, during and after the competitive season. Both groups significantly improved 1RM and MP over the entire competitive season, with a moderate (TG, 13%) to very large (UG, 21%) magnitude in 1RM and with a small (TG, 8%) to moderate (UG, 13%) magnitude in MP. After the initial 10 weeks of RT, UG presented significant and slightly (1RM) to moderately (MP) greater improvements than TG. For all other time intervals, the between-groups changes in 1RM were rated as similar. For the last 20 weeks of the RT, the change in MP was significantly lower for UG compared to TG. One upper-body RT-session per week will provide sufficient stimulus to enable an almost certain improvement in strength and power throughout a competitive season for all players disregarding their initial RT status.

Early age compressive strength, porosity, and sorptivity of concrete using peat water to produce and cure concrete

NASA Astrophysics Data System (ADS)

Olivia, Monita; Ismeddiyanto, Wibisono, Gunawan; Sitompul, Iskandar R.

2017-09-01

Construction in peatland has faced scarce water sources for mixing and curing concrete. It is known that peat water has high organic content and low pH that can be harmful to concrete in the environment. In some remote areas in Riau Province, contractors used peat water directly without sufficient treatments to comply with SKSNI requirements of concrete mixing water. This paper presents a study of compressive strength, porosity and sorptivity of Ordinary Portland Cement (OPC) and blended OPC-Palm Oil Fuel Ash (OPC-POFA) concrete. The specimens were mixed using natural water and peat water, then some of them were cured in fresh water and peat water. Six mixtures were investigated using a variation of cement, mixing water and curing water. Tap water is used as control mixing and curing water for all specimens. The compressive strength, porosity and sorptivity were calculated at seven and 28 days. Results indicate that the use of peat water will cause low compressive strength, high porosity and sorptivity for both OPC and OPC-POFA concrete. Using peat water and curing the specimens in tap water could improve the early strength, porosity and sorptivity of OPC concrete; however, it has an adverse effect on OPC-POFA specimens. The properties of early age concrete of both types (OPC and OPC-POFA) using peat water were as good as those with tap water. Therefore, it is suggested that peat water should be considered as mixing and curing water for concrete where tap water resources are scarce. Investigation of its long-term properties, as well as extending the observed age of concrete is recommended before any use of peat water.

Evaluation of capping systems for high-strength concrete cylinders.

DOT National Transportation Integrated Search

2006-03-01

This study focused on the effects of capping systems on the compressive strength of high-strength concrete. The compressive strength levels ranged from 6,000 psi to 14,000 psi. The three systems investigated were ground ends, bonded caps, and unbonde...

Sensitization of Laser-beam Welded Martensitic Stainless Steels

NASA Astrophysics Data System (ADS)

Dahmen, Martin; Rajendran, Kousika Dhasanur; Lindner, Stefan

Ferritic and martensitic stainless steels are an attractive alternative in vehicle production due to their inherent corrosion resistance. By the opportunity of press hardening, their strength can be increased to up to 2000 MPa, making them competitors for unalloyed ultra-high strength steels. Welding, nevertheless, requires special care, especially when it comes to joining of high strength heat treated materials. With an adopted in-line heat treatment of the welds in as-rolled as well as press hardened condition, materials with sufficient fatigue strength and acceptable structural behavior can be produced. Because of microstructural transformations in the base material such as grain coarsening and forced carbide precipitation, the corrosion resistance of the weld zone may be locally impaired. Typically the material in the heat-affected zone becomes sensitive to intergranular cracking in the form of knife-edge corrosion besides the fusion line. The current study comprises of two text scenarios. By an alternating climate test, general response in a corroding environment is screened. In order to understand the corrosion mechanisms and to localize the sensitive zones, sensitisation tests were undertaken. Furthermore, the applicability of a standard test according to ASTM 763-83 was examined. It was found that the alternative climate test does not reveal any corrosion effects. Testing by the oxalic acid test revealed clearly the effect of welding, weld heat treatment and state of thermal processing. Also application of the standard which originally suited for testing ferritic stainless steels could have been justified.