[Employees in high-reliability organizations: systematic selection of personnel as a final criterion].

PubMed

Oubaid, V; Anheuser, P

2014-05-01

Employees represent an important safety factor in high-reliability organizations. The combination of clear organizational structures, a nonpunitive safety culture, and psychological personnel selection guarantee a high level of safety. The cockpit personnel selection process of a major German airline is presented in order to demonstrate a possible transferability into medicine and urology.

The Reliability, Validity, and Evaluation of the Objective Structured Clinical Examination in Podiatry (Chiropody).

ERIC Educational Resources Information Center

Woodburn, Jim; Sutcliffe, Nick

1996-01-01

The Objective Structured Clinical Examination (OSCE), initially developed for undergraduate medical education, has been adapted for assessment of clinical skills in podiatry students. A 12-month pilot study found the test had relatively low levels of reliability, high construct and criterion validity, and good stability of performance over time.…

Best Practices for Reliable and Robust Spacecraft Structures

NASA Technical Reports Server (NTRS)

Raju, Ivatury S.; Murthy, P. L. N.; Patel, Naresh R.; Bonacuse, Peter J.; Elliott, Kenny B.; Gordon, S. A.; Gyekenyesi, J. P.; Daso, E. O.; Aggarwal, P.; Tillman, R. F.

2007-01-01

A study was undertaken to capture the best practices for the development of reliable and robust spacecraft structures for NASA s next generation cargo and crewed launch vehicles. In this study, the NASA heritage programs such as Mercury, Gemini, Apollo, and the Space Shuttle program were examined. A series of lessons learned during the NASA and DoD heritage programs are captured. The processes that "make the right structural system" are examined along with the processes to "make the structural system right". The impact of technology advancements in materials and analysis and testing methods on reliability and robustness of spacecraft structures is studied. The best practices and lessons learned are extracted from these studies. Since the first human space flight, the best practices for reliable and robust spacecraft structures appear to be well established, understood, and articulated by each generation of designers and engineers. However, these best practices apparently have not always been followed. When the best practices are ignored or short cuts are taken, risks accumulate, and reliability suffers. Thus program managers need to be vigilant of circumstances and situations that tend to violate best practices. Adherence to the best practices may help develop spacecraft systems with high reliability and robustness against certain anomalies and unforeseen events.

Reliability of a novel, semi-quantitative scale for classification of structural brain magnetic resonance imaging in children with cerebral palsy.

PubMed

Fiori, Simona; Cioni, Giovanni; Klingels, Katrjin; Ortibus, Els; Van Gestel, Leen; Rose, Stephen; Boyd, Roslyn N; Feys, Hilde; Guzzetta, Andrea

2014-09-01

To describe the development of a novel rating scale for classification of brain structural magnetic resonance imaging (MRI) in children with cerebral palsy (CP) and to assess its interrater and intrarater reliability. The scale consists of three sections. Section 1 contains descriptive information about the patient and MRI. Section 2 contains the graphical template of brain hemispheres onto which the lesion is transposed. Section 3 contains the scoring system for the quantitative analysis of the lesion characteristics, grouped into different global scores and subscores that assess separately side, regions, and depth. A larger interrater and intrarater reliability study was performed in 34 children with CP (22 males, 12 females; mean age at scan of 9 y 5 mo [SD 3 y 3 mo], range 4 y-16 y 11 mo; Gross Motor Function Classification System level I, [n=22], II [n=10], and level III [n=2]). Very high interrater and intrarater reliability of the total score was found with indices above 0.87. Reliability coefficients of the lobar and hemispheric subscores ranged between 0.53 and 0.95. Global scores for hemispheres, basal ganglia, brain stem, and corpus callosum showed reliability coefficients above 0.65. This study presents the first visual, semi-quantitative scale for classification of brain structural MRI in children with CP. The high degree of reliability of the scale supports its potential application for investigating the relationship between brain structure and function and examining treatment response according to brain lesion severity in children with CP. © 2014 Mac Keith Press.

Ferroelectric nanoparticle-embedded sponge structure triboelectric generators

NASA Astrophysics Data System (ADS)

Park, Daehoon; Shin, Sung-Ho; Yoon, Ick-Jae; Nah, Junghyo

2018-05-01

We report high-performance triboelectric nanogenerators (TENGs) employing ferroelectric nanoparticles (NPs) embedded in a sponge structure. The ferroelectric BaTiO3 NPs inside the sponge structure play an important role in increasing surface charge density by polarized spontaneous dipoles, enabling the packaging of TENGs even with a minimal separation gap. Since the friction surfaces are encapsulated in the packaged device structure, it suffers negligible performance degradation even at a high relative humidity of 80%. The TENGs also demonstrated excellent mechanical durability due to the elasticity and flexibility of the sponge structure. Consequently, the TENGs can reliably harvest energy even under harsh conditions. The approach introduced here is a simple, effective, and reliable way to fabricate compact and packaged TENGs for potential applications in wearable energy-harvesting devices.

Ferroelectric nanoparticle-embedded sponge structure triboelectric generators.

PubMed

Park, Daehoon; Shin, Sung-Ho; Yoon, Ick-Jae; Nah, Junghyo

2018-05-04

We report high-performance triboelectric nanogenerators (TENGs) employing ferroelectric nanoparticles (NPs) embedded in a sponge structure. The ferroelectric BaTiO 3 NPs inside the sponge structure play an important role in increasing surface charge density by polarized spontaneous dipoles, enabling the packaging of TENGs even with a minimal separation gap. Since the friction surfaces are encapsulated in the packaged device structure, it suffers negligible performance degradation even at a high relative humidity of 80%. The TENGs also demonstrated excellent mechanical durability due to the elasticity and flexibility of the sponge structure. Consequently, the TENGs can reliably harvest energy even under harsh conditions. The approach introduced here is a simple, effective, and reliable way to fabricate compact and packaged TENGs for potential applications in wearable energy-harvesting devices.

Study on safety level of RC beam bridges under earthquake

NASA Astrophysics Data System (ADS)

Zhao, Jun; Lin, Junqi; Liu, Jinlong; Li, Jia

2017-08-01

This study considers uncertainties in material strengths and the modeling which have important effects on structural resistance force based on reliability theory. After analyzing the destruction mechanism of a RC bridge, structural functions and the reliability were given, then the safety level of the piers of a reinforced concrete continuous girder bridge with stochastic structural parameters against earthquake was analyzed. Using response surface method to calculate the failure probabilities of bridge piers under high-level earthquake, their seismic reliability for different damage states within the design reference period were calculated applying two-stage design, which describes seismic safety level of the built bridges to some extent.

Reliable 6 PEP LTPS device for AMOLED's

NASA Astrophysics Data System (ADS)

Chou, Cheng-Wei; Wang, Pei-Yun; Hu, Chin-Wei; Chang, York; Chuang, Ching-Sang; Lin, Yusin

2013-09-01

This study presents a TFT structure which has less photo process and higher cost competitiveness in AMOLED display markets. A novel LTPS based 6 masks TFT structure for bottom emission AMOLED display is demonstrated in this paper. High field effect mobility (PMOS < 80 cm2/Vs ) and high reliability (PBTS △Vth< 0.02V @ 50oC VG=15V 10ks) was accomplished without the high temperature and rapid thermal annealing (RTA) activation process. Furthermore, a 14-inch AMOLED TV was achieved on the proposed 6-pep TFT backplane using the Gen. 3.5 mass production factory.

Multilevel Factor Structure, Concurrent Validity, and Test-Retest Reliability of the High School Teacher Version of the Authoritative School Climate Survey

ERIC Educational Resources Information Center

Huang, Francis L.; Cornell, Dewey G.

2016-01-01

Although school climate has long been recognized as an important factor in the school improvement process, there are few psychometrically supported measures based on teacher perspectives. The current study replicated and extended the factor structure, concurrent validity, and test-retest reliability of the teacher version of the Authoritative…

The application of structural reliability techniques to plume impingement loading of the Space Station Freedom Photovoltaic Array

NASA Technical Reports Server (NTRS)

Yunis, Isam S.; Carney, Kelly S.

1993-01-01

A new aerospace application of structural reliability techniques is presented, where the applied forces depend on many probabilistic variables. This application is the plume impingement loading of the Space Station Freedom Photovoltaic Arrays. When the space shuttle berths with Space Station Freedom it must brake and maneuver towards the berthing point using its primary jets. The jet exhaust, or plume, may cause high loads on the photovoltaic arrays. The many parameters governing this problem are highly uncertain and random. An approach, using techniques from structural reliability, as opposed to the accepted deterministic methods, is presented which assesses the probability of failure of the array mast due to plume impingement loading. A Monte Carlo simulation of the berthing approach is used to determine the probability distribution of the loading. A probability distribution is also determined for the strength of the array. Structural reliability techniques are then used to assess the array mast design. These techniques are found to be superior to the standard deterministic dynamic transient analysis, for this class of problem. The results show that the probability of failure of the current array mast design, during its 15 year life, is minute.

Two-year Test-Retest Reliability in High School Athletes Using the Four- and Two-Factor ImPACT Composite Structures: The Effects of Learning Disorders and Headache/Migraine Treatment History.

PubMed

Brett, Benjamin L; Solomon, Gary S; Hill, Jennifer; Schatz, Philip

2018-03-01

This study examined the test-retest reliability of the four- and two-factor structures (i.e., Memory and Speed) of ImPACT over a 2-year interval across multiple groups with premorbid conditions, including those with a history of special education or learning disorders (LD; n = 114), treatment history for headache/migraine (n = 81), and a control group (n = 792). Nine hundred and eighty seven high school athletes completed baseline testing using online ImPACT across a 2-year interval. Paired-samples t-tests documented improvement from initial to follow-up assessments. Test stability was examined using Regression-based measures (RBM) and Reliable change indices (RCI). Reliability was examined using intraclass correlation coefficients (ICC). Significant improvement on all four composites were observed for the control group over a 2-year interval; whereas significant differences were observed only on Visual Motor Speed for the LD and headache/migraine treatment history groups. ICCs ranges were similar across groups and greater or comparable reliability was observed for the two-factor structure on Memory (0.67-0.73) and Speed (0.76-0.78) composites. RCIs and RBMs demonstrated stability for the four- and two-factor structures, with few cases falling outside the range of expected change within a healthy sample at the 90% and 95% CIs. Typical practices of obtaining new baselines every 2 years in the high school population can be applied to athletes with a history of special education or LD and headache/migraine treatment. The two-factor structure has potential to increase test-retest reliability. Further research regarding clinical utility is needed. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Identification of Extracellular Segments by Mass Spectrometry Improves Topology Prediction of Transmembrane Proteins.

PubMed

Langó, Tamás; Róna, Gergely; Hunyadi-Gulyás, Éva; Turiák, Lilla; Varga, Julia; Dobson, László; Várady, György; Drahos, László; Vértessy, Beáta G; Medzihradszky, Katalin F; Szakács, Gergely; Tusnády, Gábor E

2017-02-13

Transmembrane proteins play crucial role in signaling, ion transport, nutrient uptake, as well as in maintaining the dynamic equilibrium between the internal and external environment of cells. Despite their important biological functions and abundance, less than 2% of all determined structures are transmembrane proteins. Given the persisting technical difficulties associated with high resolution structure determination of transmembrane proteins, additional methods, including computational and experimental techniques remain vital in promoting our understanding of their topologies, 3D structures, functions and interactions. Here we report a method for the high-throughput determination of extracellular segments of transmembrane proteins based on the identification of surface labeled and biotin captured peptide fragments by LC/MS/MS. We show that reliable identification of extracellular protein segments increases the accuracy and reliability of existing topology prediction algorithms. Using the experimental topology data as constraints, our improved prediction tool provides accurate and reliable topology models for hundreds of human transmembrane proteins.

Probabilistic simulation of uncertainties in thermal structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Shiao, Michael

1990-01-01

Development of probabilistic structural analysis methods for hot structures is a major activity at Lewis Research Center. It consists of five program elements: (1) probabilistic loads; (2) probabilistic finite element analysis; (3) probabilistic material behavior; (4) assessment of reliability and risk; and (5) probabilistic structural performance evaluation. Recent progress includes: (1) quantification of the effects of uncertainties for several variables on high pressure fuel turbopump (HPFT) blade temperature, pressure, and torque of the Space Shuttle Main Engine (SSME); (2) the evaluation of the cumulative distribution function for various structural response variables based on assumed uncertainties in primitive structural variables; (3) evaluation of the failure probability; (4) reliability and risk-cost assessment, and (5) an outline of an emerging approach for eventual hot structures certification. Collectively, the results demonstrate that the structural durability/reliability of hot structural components can be effectively evaluated in a formal probabilistic framework. In addition, the approach can be readily extended to computationally simulate certification of hot structures for aerospace environments.

Problems of the high-cycle fatigue of the materials intended for the parts of modern gas-turbine engines and power plants

NASA Astrophysics Data System (ADS)

Petukhov, A. N.

2010-10-01

The problems related to the determination of the life of the structural materials applied for important parts in gas-turbine engines and power plants from the results of high-cycle fatigue tests are discussed. Methods for increasing the reliability of the high-cycle fatigue characteristics and the factors affecting the operational reliability are considered.

Investigation of veritcal graded channel doping in nanoscale fully-depleted SOI-MOSFET

NASA Astrophysics Data System (ADS)

Ramezani, Zeinab; Orouji, Ali A.

2016-10-01

For achieving reliable transistor, we investigate an amended channel doping (ACD) engineering which improves the electrical and thermal performances of fully-depleted silicon-on-insulator (SOI) MOSFET. We have called the proposed structure with the amended channel doping engineering as ACD-SOI structure and compared it with a conventional fully-depleted SOI MOSFET (C-SOI) with uniform doping distribution using 2-D ATLAS simulator. The amended channel doping is a vertical graded doping that is distributed from the surface of structure with high doping density to the bottom of channel, near the buried oxide, with low doping density. Short channel effects (SCEs) and leakage current suppress due to high barrier height near the source region and electric field modification in the ACD-SOI in comparison with the C-SOI structure. Furthermore, by lower electric field and electron temperature near the drain region that is the place of hot carrier generation, we except the improvement of reliability and gate induced drain lowering (GIDL) in the proposed structure. Undesirable Self heating effect (SHE) that become a critical challenge for SOI MOSFETs is alleviated in the ACD-SOI structure because of utilizing low doping density near the buried oxide. Thus, refer to accessible results, the ACD-SOI structure with graded distribution in vertical direction is a reliable device especially in low power and high temperature applications.

Puncture Self-Healing Polymers for Aerospace Applications

NASA Technical Reports Server (NTRS)

Gordon, Keith L.; Penner, Ronald K.; Bogert, Phil B.; Yost, W. T.; Siochi, Emilie J.

2011-01-01

Space exploration launch costs on the order of $10K per pound provide ample incentive to seek innovative, cost-effective ways to reduce structural mass without sacrificing safety and reliability. Damage-tolerant structural systems can provide a route to avoiding weight penalty while enhancing vehicle safety and reliability. Self-healing polymers capable of spontaneous puncture repair show great promise to mitigate potentially catastrophic damage from events such as micrometeoroid penetration. Effective self-repair requires these materials to heal instantaneously following projectile penetration while retaining structural integrity. Poly(ethylene-co-methacrylic acid) (EMMA), also known as Surlyn is an ionomer-based copolymer that undergoes puncture reversal (self-healing) following high impact puncture at high velocities. However EMMA is not a structural engineering polymer, and will not meet the demands of aerospace applications requiring self-healing engineering materials. Current efforts to identify candidate self-healing polymer materials for structural engineering systems are reported. Rheology, high speed thermography, and high speed video for self-healing semi-crystalline and amorphous polymers will be reported.

High-Temperature Storage Testing of ACF Attached Sensor Structures

PubMed Central

Lahokallio, Sanna; Hoikkanen, Maija; Vuorinen, Jyrki; Frisk, Laura

2015-01-01

Several electronic applications must withstand elevated temperatures during their lifetime. Materials and packages for use in high temperatures have been designed, but they are often very expensive, have limited compatibility with materials, structures, and processing techniques, and are less readily available than traditional materials. Thus, there is an increasing interest in using low-cost polymer materials in high temperature applications. This paper studies the performance and reliability of sensor structures attached with anisotropically conductive adhesive film (ACF) on two different organic printed circuit board (PCB) materials: FR-4 and Rogers. The test samples were aged at 200 °C and 240 °C and monitored electrically during the test. Material characterization techniques were also used to analyze the behavior of the materials. Rogers PCB was observed to be more stable at high temperatures in spite of degradation observed, especially during the first 120 h of aging. The electrical reliability was very good with Rogers. At 200 °C, the failures occurred after 2000 h of testing, and even at 240 °C the interconnections were functional for 400 h. The study indicates that, even though these ACFs were not designed for use in high temperatures, with stable PCB material they are promising interconnection materials at elevated temperatures, especially at 200 °C. However, the fragility of the structure due to material degradation may cause reliability problems in long-term high temperature exposure. PMID:28793735

Effect of Clinically Discriminating, Evidence-Based Checklist Items on the Reliability of Scores from an Internal Medicine Residency OSCE

ERIC Educational Resources Information Center

Daniels, Vijay J.; Bordage, Georges; Gierl, Mark J.; Yudkowsky, Rachel

2014-01-01

Objective structured clinical examinations (OSCEs) are used worldwide for summative examinations but often lack acceptable reliability. Research has shown that reliability of scores increases if OSCE checklists for medical students include only clinically relevant items. Also, checklists are often missing evidence-based items that high-achieving…

Care 3 model overview and user's guide, first revision

NASA Technical Reports Server (NTRS)

Bavuso, S. J.; Petersen, P. L.

1985-01-01

A manual was written to introduce the CARE III (Computer-Aided Reliability Estimation) capability to reliability and design engineers who are interested in predicting the reliability of highly reliable fault-tolerant systems. It was also structured to serve as a quick-look reference manual for more experienced users. The guide covers CARE III modeling and reliability predictions for execution in the CDC CYber 170 series computers, DEC VAX-11/700 series computer, and most machines that compile ANSI Standard FORTRAN 77.

Highly uniform and reliable resistive switching characteristics of a Ni/WOx/p+-Si memory device

NASA Astrophysics Data System (ADS)

Kim, Tae-Hyeon; Kim, Sungjun; Kim, Hyungjin; Kim, Min-Hwi; Bang, Suhyun; Cho, Seongjae; Park, Byung-Gook

2018-02-01

In this paper, we investigate the resistive switching behavior of a bipolar resistive random-access memory (RRAM) in a Ni/WOx/p+-Si RRAM with CMOS compatibility. Highly unifrom and reliable bipolar resistive switching characteristics are observed by a DC voltage sweeping and its switching mechanism can be explained by SCLC model. As a result, the possibility of metal-insulator-silicon (MIS) structural WOx-based RRAM's application to Si-based 1D (diode)-1R (RRAM) or 1T (transistor)-1R (RRAM) structure is demonstrated.

Design for a Crane Metallic Structure Based on Imperialist Competitive Algorithm and Inverse Reliability Strategy

NASA Astrophysics Data System (ADS)

Fan, Xiao-Ning; Zhi, Bo

2017-07-01

Uncertainties in parameters such as materials, loading, and geometry are inevitable in designing metallic structures for cranes. When considering these uncertainty factors, reliability-based design optimization (RBDO) offers a more reasonable design approach. However, existing RBDO methods for crane metallic structures are prone to low convergence speed and high computational cost. A unilevel RBDO method, combining a discrete imperialist competitive algorithm with an inverse reliability strategy based on the performance measure approach, is developed. Application of the imperialist competitive algorithm at the optimization level significantly improves the convergence speed of this RBDO method. At the reliability analysis level, the inverse reliability strategy is used to determine the feasibility of each probabilistic constraint at each design point by calculating its α-percentile performance, thereby avoiding convergence failure, calculation error, and disproportionate computational effort encountered using conventional moment and simulation methods. Application of the RBDO method to an actual crane structure shows that the developed RBDO realizes a design with the best tradeoff between economy and safety together with about one-third of the convergence speed and the computational cost of the existing method. This paper provides a scientific and effective design approach for the design of metallic structures of cranes.

Evaluation Applied to Reliability Analysis of Reconfigurable, Highly Reliable, Fault-Tolerant, Computing Systems for Avionics

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques are proposed as a solution to a difficulty arising in the analysis of the reliability of highly reliable computer systems for future commercial aircraft. The difficulty, viz., the lack of credible precision in reliability estimates obtained by analytical modeling techniques are established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible, (2) a complex system design technique, fault tolerance, (3) system reliability dominated by errors due to flaws in the system definition, and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. The technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. The use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques.

Interphase Thermomechanical Reliability and Optimization for High-Performance Ti Metal Laminates

DTIC Science & Technology

2011-12-19

Thermomechanical Reliability and Optimization for High-Performance Ti FA9550-08-l-0015 Metal Laminates Sb. GRANT NUMBER Program Manager: Dr Joycelyn Harrison...OSR-VA-TR-2012-0202 12. DISTRIBUTION/AVAILABILITY STATEMENT A 13. SUPPLEMENTARY NOTES 14. ABSTRACT Hybrid laminated composites such as titanium...graphite (TiGr) laminates are an emerging class of structural materials with the potential to enable a new generation of efficient, high-performance

Highly reliable 637-639 nm red high-power LDs for displays

NASA Astrophysics Data System (ADS)

Nishida, Takehiro; Shimada, Naoyuki; Ono, Kenichi; Yagi, Tetsuya; Shima, Akihiro

2010-02-01

Higher power laser diodes (LDs) with a wavelength of 637-639nm are strongly demanded as a light source of display applications because luminosity factor of laser light is relatively high. In order to realize reliable high power operation, we have optimized LD structure, focusing on improvement of power saturation and sudden degradation. As a result, 40μm-wide broad-area (BA) LDs with window-mirror structure have been designed. We fabricated two kinds of single emitter LDs of 1.0mm cavity and 1.5mm cavity. The single LD is installed in conventional φ5.6 mm TO-CAN package. The 1.0mm LD showed very high wall plug efficiency (WPE) of 33% at 25 ºC (23% at 45 ºC) in the power range of around 300mW (30 lm). High output power of 600mW (60 lm) is realized by the 1.5mm LD. Both LDs have operated for over 1,000 hours without any degradation. Estimated mean time to failure (MTTF) is 10,000 hours. In addition, we fabricated an array LD consisting of 20 emitters (BA-LD structure), which shows reliable CW operation of 8W (at junction temperature of 50 ºC) for 10,000 hours.

Experimental application of OMA solutions on the model of industrial structure

NASA Astrophysics Data System (ADS)

Mironov, A.; Mironovs, D.

2017-10-01

It is very important and sometimes even vital to maintain reliability of industrial structures. High quality control during production and structural health monitoring (SHM) in exploitation provides reliable functioning of large, massive and remote structures, like wind generators, pipelines, power line posts, etc. This paper introduces a complex of technological and methodical solutions for SHM and diagnostics of industrial structures, including those that are actuated by periodic forces. Solutions were verified on a wind generator scaled model with integrated system of piezo-film deformation sensors. Simultaneous and multi-patch Operational Modal Analysis (OMA) approaches were implemented as methodical means for structural diagnostics and monitoring. Specially designed data processing algorithms provide objective evaluation of structural state modification.

The German version of the Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5): psychometric properties and diagnostic utility.

PubMed

Krüger-Gottschalk, Antje; Knaevelsrud, Christine; Rau, Heinrich; Dyer, Anne; Schäfer, Ingo; Schellong, Julia; Ehring, Thomas

2017-11-28

The Posttraumatic Stress Disorder (PTSD) Checklist (PCL, now PCL-5) has recently been revised to reflect the new diagnostic criteria of the disorder. A clinical sample of trauma-exposed individuals (N = 352) was assessed with the Clinician Administered PTSD Scale for DSM-5 (CAPS-5) and the PCL-5. Internal consistencies and test-retest reliability were computed. To investigate diagnostic accuracy, we calculated receiver operating curves. Confirmatory factor analyses (CFA) were performed to analyze the structural validity. Results showed high internal consistency (α = .95), high test-retest reliability (r = .91) and a high correlation with the total severity score of the CAPS-5, r = .77. In addition, the recommended cutoff of 33 on the PCL-5 showed high diagnostic accuracy when compared to the diagnosis established by the CAPS-5. CFAs comparing the DSM-5 model with alternative models (the three-factor solution, the dysphoria, anhedonia, externalizing behavior and hybrid model) to account for the structural validity of the PCL-5 remained inconclusive. Overall, the findings show that the German PCL-5 is a reliable instrument with good diagnostic accuracy. However, more research evaluating the underlying factor structure is needed.

Probabilistic design of fibre concrete structures

NASA Astrophysics Data System (ADS)

Pukl, R.; Novák, D.; Sajdlová, T.; Lehký, D.; Červenka, J.; Červenka, V.

2017-09-01

Advanced computer simulation is recently well-established methodology for evaluation of resistance of concrete engineering structures. The nonlinear finite element analysis enables to realistically predict structural damage, peak load, failure, post-peak response, development of cracks in concrete, yielding of reinforcement, concrete crushing or shear failure. The nonlinear material models can cover various types of concrete and reinforced concrete: ordinary concrete, plain or reinforced, without or with prestressing, fibre concrete, (ultra) high performance concrete, lightweight concrete, etc. Advanced material models taking into account fibre concrete properties such as shape of tensile softening branch, high toughness and ductility are described in the paper. Since the variability of the fibre concrete material properties is rather high, the probabilistic analysis seems to be the most appropriate format for structural design and evaluation of structural performance, reliability and safety. The presented combination of the nonlinear analysis with advanced probabilistic methods allows evaluation of structural safety characterized by failure probability or by reliability index respectively. Authors offer a methodology and computer tools for realistic safety assessment of concrete structures; the utilized approach is based on randomization of the nonlinear finite element analysis of the structural model. Uncertainty of the material properties or their randomness obtained from material tests are accounted in the random distribution. Furthermore, degradation of the reinforced concrete materials such as carbonation of concrete, corrosion of reinforcement, etc. can be accounted in order to analyze life-cycle structural performance and to enable prediction of the structural reliability and safety in time development. The results can serve as a rational basis for design of fibre concrete engineering structures based on advanced nonlinear computer analysis. The presented methodology is illustrated on results from two probabilistic studies with different types of concrete structures related to practical applications and made from various materials (with the parameters obtained from real material tests).

Integrated material state awareness system with self-learning symbiotic diagnostic algorithms and models

NASA Astrophysics Data System (ADS)

Banerjee, Sourav; Liu, Lie; Liu, S. T.; Yuan, Fuh-Gwo; Beard, Shawn

2011-04-01

Materials State Awareness (MSA) goes beyond traditional NDE and SHM in its challenge to characterize the current state of material damage before the onset of macro-damage such as cracks. A highly reliable, minimally invasive system for MSA of Aerospace Structures, Naval structures as well as next generation space systems is critically needed. Development of such a system will require a reliable SHM system that can detect the onset of damage well before the flaw grows to a critical size. Therefore, it is important to develop an integrated SHM system that not only detects macroscale damages in the structures but also provides an early indication of flaw precursors and microdamages. The early warning for flaw precursors and their evolution provided by an SHM system can then be used to define remedial strategies before the structural damage leads to failure, and significantly improve the safety and reliability of the structures. Thus, in this article a preliminary concept of developing the Hybrid Distributed Sensor Network Integrated with Self-learning Symbiotic Diagnostic Algorithms and Models to accurately and reliably detect the precursors to damages that occur to the structure are discussed. Experiments conducted in a laboratory environment shows potential of the proposed technique.

Structural Deterministic Safety Factors Selection Criteria and Verification

NASA Technical Reports Server (NTRS)

Verderaime, V.

1992-01-01

Though current deterministic safety factors are arbitrarily and unaccountably specified, its ratio is rooted in resistive and applied stress probability distributions. This study approached the deterministic method from a probabilistic concept leading to a more systematic and coherent philosophy and criterion for designing more uniform and reliable high-performance structures. The deterministic method was noted to consist of three safety factors: a standard deviation multiplier of the applied stress distribution; a K-factor for the A- or B-basis material ultimate stress; and the conventional safety factor to ensure that the applied stress does not operate in the inelastic zone of metallic materials. The conventional safety factor is specifically defined as the ratio of ultimate-to-yield stresses. A deterministic safety index of the combined safety factors was derived from which the corresponding reliability proved the deterministic method is not reliability sensitive. The bases for selecting safety factors are presented and verification requirements are discussed. The suggested deterministic approach is applicable to all NASA, DOD, and commercial high-performance structures under static stresses.

Statistical Analysis on the Mechanical Properties of Magnesium Alloys

PubMed Central

Liu, Ruoyu; Jiang, Xianquan; Zhang, Hongju; Zhang, Dingfei; Wang, Jingfeng; Pan, Fusheng

2017-01-01

Knowledge of statistical characteristics of mechanical properties is very important for the practical application of structural materials. Unfortunately, the scatter characteristics of magnesium alloys for mechanical performance remain poorly understood until now. In this study, the mechanical reliability of magnesium alloys is systematically estimated using Weibull statistical analysis. Interestingly, the Weibull modulus, m, of strength for magnesium alloys is as high as that for aluminum and steels, confirming the very high reliability of magnesium alloys. The high predictability in the tensile strength of magnesium alloys represents the capability of preventing catastrophic premature failure during service, which is essential for safety and reliability assessment. PMID:29113116

An Acoustic Charge Transport Imager for High Definition Television Applications: Reliability Modeling and Parametric Yield Prediction of GaAs Multiple Quantum Well Avalanche Photodiodes. Degree awarded Oct. 1997

NASA Technical Reports Server (NTRS)

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Yun, Ilgu

1994-01-01

Reliability modeling and parametric yield prediction of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiodes (APDs), which are of interest as an ultra-low noise image capture mechanism for high definition systems, have been investigated. First, the effect of various doping methods on the reliability of GaAs/AlGaAs multiple quantum well (MQW) avalanche photodiode (APD) structures fabricated by molecular beam epitaxy is investigated. Reliability is examined by accelerated life tests by monitoring dark current and breakdown voltage. Median device lifetime and the activation energy of the degradation mechanism are computed for undoped, doped-barrier, and doped-well APD structures. Lifetimes for each device structure are examined via a statistically designed experiment. Analysis of variance shows that dark-current is affected primarily by device diameter, temperature and stressing time, and breakdown voltage depends on the diameter, stressing time and APD type. It is concluded that the undoped APD has the highest reliability, followed by the doped well and doped barrier devices, respectively. To determine the source of the degradation mechanism for each device structure, failure analysis using the electron-beam induced current method is performed. This analysis reveals some degree of device degradation caused by ionic impurities in the passivation layer, and energy-dispersive spectrometry subsequently verified the presence of ionic sodium as the primary contaminant. However, since all device structures are similarly passivated, sodium contamination alone does not account for the observed variation between the differently doped APDs. This effect is explained by the dopant migration during stressing, which is verified by free carrier concentration measurements using the capacitance-voltage technique.

Probabilistic Structural Analysis and Reliability Using NESSUS With Implemented Material Strength Degradation Model

NASA Technical Reports Server (NTRS)

Bast, Callie C.; Jurena, Mark T.; Godines, Cody R.; Chamis, Christos C. (Technical Monitor)

2001-01-01

This project included both research and education objectives. The goal of this project was to advance innovative research and education objectives in theoretical and computational probabilistic structural analysis, reliability, and life prediction for improved reliability and safety of structural components of aerospace and aircraft propulsion systems. Research and education partners included Glenn Research Center (GRC) and Southwest Research Institute (SwRI) along with the University of Texas at San Antonio (UTSA). SwRI enhanced the NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) code and provided consulting support for NESSUS-related activities at UTSA. NASA funding supported three undergraduate students, two graduate students, a summer course instructor and the Principal Investigator. Matching funds from UTSA provided for the purchase of additional equipment for the enhancement of the Advanced Interactive Computational SGI Lab established during the first year of this Partnership Award to conduct the probabilistic finite element summer courses. The research portion of this report presents the cumulation of work performed through the use of the probabilistic finite element program, NESSUS, Numerical Evaluation and Structures Under Stress, and an embedded Material Strength Degradation (MSD) model. Probabilistic structural analysis provided for quantification of uncertainties associated with the design, thus enabling increased system performance and reliability. The structure examined was a Space Shuttle Main Engine (SSME) fuel turbopump blade. The blade material analyzed was Inconel 718, since the MSD model was previously calibrated for this material. Reliability analysis encompassing the effects of high temperature and high cycle fatigue, yielded a reliability value of 0.99978 using a fully correlated random field for the blade thickness. The reliability did not change significantly for a change in distribution type except for a change in distribution from Gaussian to Weibull for the centrifugal load. The sensitivity factors determined to be most dominant were the centrifugal loading and the initial strength of the material. These two sensitivity factors were influenced most by a change in distribution type from Gaussian to Weibull. The education portion of this report describes short-term and long-term educational objectives. Such objectives serve to integrate research and education components of this project resulting in opportunities for ethnic minority students, principally Hispanic. The primary vehicle to facilitate such integration was the teaching of two probabilistic finite element method courses to undergraduate engineering students in the summers of 1998 and 1999.

Universal first-order reliability concept applied to semistatic structures

NASA Technical Reports Server (NTRS)

Verderaime, V.

1994-01-01

A reliability design concept was developed for semistatic structures which combines the prevailing deterministic method with the first-order reliability method. The proposed method surmounts deterministic deficiencies in providing uniformly reliable structures and improved safety audits. It supports risk analyses and reliability selection criterion. The method provides a reliability design factor derived from the reliability criterion which is analogous to the current safety factor for sizing structures and verifying reliability response. The universal first-order reliability method should also be applicable for air and surface vehicles semistatic structures.

Universal first-order reliability concept applied to semistatic structures

NASA Astrophysics Data System (ADS)

Verderaime, V.

1994-07-01

A reliability design concept was developed for semistatic structures which combines the prevailing deterministic method with the first-order reliability method. The proposed method surmounts deterministic deficiencies in providing uniformly reliable structures and improved safety audits. It supports risk analyses and reliability selection criterion. The method provides a reliability design factor derived from the reliability criterion which is analogous to the current safety factor for sizing structures and verifying reliability response. The universal first-order reliability method should also be applicable for air and surface vehicles semistatic structures.

Emulation applied to reliability analysis of reconfigurable, highly reliable, fault-tolerant computing systems

NASA Technical Reports Server (NTRS)

Migneault, G. E.

1979-01-01

Emulation techniques applied to the analysis of the reliability of highly reliable computer systems for future commercial aircraft are described. The lack of credible precision in reliability estimates obtained by analytical modeling techniques is first established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Next, the technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. Use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques. Finally an illustrative example is presented to demonstrate from actual use the promise of the proposed application of emulation.

Methodological issues in volumetric magnetic resonance imaging of the brain in the Edinburgh High Risk Project.

PubMed

Whalley, H C; Kestelman, J N; Rimmington, J E; Kelso, A; Abukmeil, S S; Best, J J; Johnstone, E C; Lawrie, S M

1999-07-30

The Edinburgh High Risk Project is a longitudinal study of brain structure (and function) in subjects at high risk of developing schizophrenia in the next 5-10 years for genetic reasons. In this article we describe the methods of volumetric analysis of structural magnetic resonance images used in the study. We also consider potential sources of error in these methods: the validity of our image analysis techniques; inter- and intra-rater reliability; possible positional variation; and thresholding criteria used in separating brain from cerebro-spinal fluid (CSF). Investigation with a phantom test object (of similar imaging characteristics to the brain) provided evidence for the validity of our image acquisition and analysis techniques. Both inter- and intra-rater reliability were found to be good in whole brain measures but less so for smaller regions. There were no statistically significant differences in positioning across the three study groups (patients with schizophrenia, high risk subjects and normal volunteers). A new technique for thresholding MRI scans longitudinally is described (the 'rescale' method) and compared with our established method (thresholding by eye). Few differences between the two techniques were seen at 3- and 6-month follow-up. These findings demonstrate the validity and reliability of the structural MRI analysis techniques used in the Edinburgh High Risk Project, and highlight methodological issues of general concern in cross-sectional and longitudinal studies of brain structure in healthy control subjects and neuropsychiatric populations.

Characterizing ceramics and the interfacial adhesion to resin: I - The relationship of microstructure, composition, properties and fractography.

PubMed

Della Bona, Alvaro

2005-03-01

The appeal of ceramics as structural dental materials is based on their light weight, high hardness values, chemical inertness, and anticipated unique tribological characteristics. A major goal of current ceramic research and development is to produce tough, strong ceramics that can provide reliable performance in dental applications. Quantifying microstructural parameters is important to develop structure/property relationships. Quantitative microstructural analysis provides an association among the constitution, physical properties, and structural characteristics of materials. Structural reliability of dental ceramics is a major factor in the clinical success of ceramic restorations. Complex stress distributions are present in most practical conditions and strength data alone cannot be directly extrapolated to predict structural performance.

Effect of reflective p-type ohmic contact on thermal reliability of vertical InGaN/GaN LEDs

NASA Astrophysics Data System (ADS)

Son, Jun Ho; Song, Yang Hee; Kim, Buem Joon; Lee, Jong-Lam

2014-11-01

We report on the enhanced thermal reliability of vertical-LEDs (VLEDs) using novel reflective p-type ohmic contacts with good thermal stability. The reflective p-type ohmic contacts with Ni/Ag-Cu alloy multi-layer structure shows low contact resistivity, as low as 9.3 × 10-6 Ωcm2, and high reflectance of 86% after annealing at 450°C. The V-LEDs with Ni/Ag-Cu alloy multi-layer structure show good thermal reliability with stress time at 300°C in air ambient. The improved thermal stability of the reflective ohmic contacts to p-type GaN is believed to play a critical role in the thermal reliability of V-LEDs. [Figure not available: see fulltext.

Review of Heterojunctin Bipolar Transistor Structure, Applications, and Reliability

NASA Technical Reports Server (NTRS)

Lee, C.; Kayali, S.

1993-01-01

Heterojunction Bipolar Transistors (HBTs) are increasingly employed in high frequency, high linerity, and high efficiency applications. As the utilization of these devices becomes more widespread, their operation will be viewed with more scrutiny.

Reliability Analysis of a Glacier Lake Warning System Using a Bayesian Net

NASA Astrophysics Data System (ADS)

Sturny, Rouven A.; Bründl, Michael

2013-04-01

Beside structural mitigation measures like avalanche defense structures, dams and galleries, warning and alarm systems have become important measures for dealing with Alpine natural hazards. Integrating them into risk mitigation strategies and comparing their effectiveness with structural measures requires quantification of the reliability of these systems. However, little is known about how reliability of warning systems can be quantified and which methods are suitable for comparing their contribution to risk reduction with that of structural mitigation measures. We present a reliability analysis of a warning system located in Grindelwald, Switzerland. The warning system was built for warning and protecting residents and tourists from glacier outburst floods as consequence of a rapid drain of the glacier lake. We have set up a Bayesian Net (BN, BPN) that allowed for a qualitative and quantitative reliability analysis. The Conditional Probability Tables (CPT) of the BN were determined according to manufacturer's reliability data for each component of the system as well as by assigning weights for specific BN nodes accounting for information flows and decision-making processes of the local safety service. The presented results focus on the two alerting units 'visual acoustic signal' (VAS) and 'alerting of the intervention entities' (AIE). For the summer of 2009, the reliability was determined to be 94 % for the VAS and 83 % for the AEI. The probability of occurrence of a major event was calculated as 0.55 % per day resulting in an overall reliability of 99.967 % for the VAS and 99.906 % for the AEI. We concluded that a failure of the VAS alerting unit would be the consequence of a simultaneous failure of the four probes located in the lake and the gorge. Similarly, we deduced that the AEI would fail either if there were a simultaneous connectivity loss of the mobile and fixed network in Grindelwald, an Internet access loss or a failure of the regional operations centre. However, the probability of a common failure of these components was assumed to be low. Overall it can be stated that due to numerous redundancies, the investigated warning system is highly reliable and its influence on risk reduction is very high. Comparable studies in the future are needed to classify these results and to gain more experience how the reliability of warning systems could be determined in practice.

Reliability-Based Design Optimization of a Composite Airframe Component

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Pai, Shantaram S.; Coroneos, Rula M.

2009-01-01

A stochastic design optimization methodology (SDO) has been developed to design components of an airframe structure that can be made of metallic and composite materials. The design is obtained as a function of the risk level, or reliability, p. The design method treats uncertainties in load, strength, and material properties as distribution functions, which are defined with mean values and standard deviations. A design constraint or a failure mode is specified as a function of reliability p. Solution to stochastic optimization yields the weight of a structure as a function of reliability p. Optimum weight versus reliability p traced out an inverted-S-shaped graph. The center of the inverted-S graph corresponded to 50 percent (p = 0.5) probability of success. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure that corresponds to unity for reliability p (or p = 1). Weight can be reduced to a small value for the most failure-prone design with a reliability that approaches zero (p = 0). Reliability can be changed for different components of an airframe structure. For example, the landing gear can be designed for a very high reliability, whereas it can be reduced to a small extent for a raked wingtip. The SDO capability is obtained by combining three codes: (1) The MSC/Nastran code was the deterministic analysis tool, (2) The fast probabilistic integrator, or the FPI module of the NESSUS software, was the probabilistic calculator, and (3) NASA Glenn Research Center s optimization testbed CometBoards became the optimizer. The SDO capability requires a finite element structural model, a material model, a load model, and a design model. The stochastic optimization concept is illustrated considering an academic example and a real-life raked wingtip structure of the Boeing 767-400 extended range airliner made of metallic and composite materials.

HDMR methods to assess reliability in slope stability analyses

NASA Astrophysics Data System (ADS)

Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna

2014-05-01

Stability analyses of complex rock-soil deposits shall be tackled considering the complex structure of discontinuities within rock mass and embedded soil layers. These materials are characterized by a high variability in physical and mechanical properties. Thus, to calculate the slope safety factor in stability analyses two issues must be taken into account: 1) the uncertainties related to structural setting of the rock-slope mass and 2) the variability in mechanical properties of soils and rocks. High Dimensional Model Representation (HDMR) (Chowdhury et al. 2009; Chowdhury and Rao 2010) can be used to carry out the reliability index within complex rock-soil slopes when numerous random variables with high coefficient of variations are considered. HDMR implements the inverse reliability analysis, meaning that the unknown design parameters are sought provided that prescribed reliability index values are attained. Such approach uses implicit response functions according to the Response Surface Method (RSM). The simple RSM can be efficiently applied when less than four random variables are considered; as the number of variables increases, the efficiency in reliability index estimation decreases due to the great amount of calculations. Therefore, HDMR method is used to improve the computational accuracy. In this study, the sliding mechanism in Polish Flysch Carpathian Mountains have been studied by means of HDMR. The Southern part of Poland where Carpathian Mountains are placed is characterized by a rather complicated sedimentary pattern of flysh rocky-soil deposits that can be simplified into three main categories: (1) normal flysch, consisting of adjacent sandstone and shale beds of approximately equal thickness, (2) shale flysch, where shale beds are thicker than adjacent sandstone beds, and (3) sandstone flysch, where the opposite holds. Landslides occur in all flysch deposit types thus some configurations of possible unstable settings (within fractured rocky-soil masses) resulting in sliding mechanisms have been investigated in this study. The reliability indices values drawn from the HDRM method have been compared with conventional approaches as neural networks: the efficiency of HDRM is shown in the case studied. References Chowdhury R., Rao B.N. and Prasad A.M. 2009. High-dimensional model representation for structural reliability analysis. Commun. Numer. Meth. Engng, 25: 301-337. Chowdhury R. and Rao B. 2010. Probabilistic Stability Assessment of Slopes Using High Dimensional Model Representation. Computers and Geotechnics, 37: 876-884.

Development of Equivalent Material Properties of Microbump for Simulating Chip Stacking Packaging

PubMed Central

Lee, Chang-Chun; Tzeng, Tzai-Liang; Huang, Pei-Chen

2015-01-01

A three-dimensional integrated circuit (3D-IC) structure with a significant scale mismatch causes difficulty in analytic model construction. This paper proposes a simulation technique to introduce an equivalent material composed of microbumps and their surrounding wafer level underfill (WLUF). The mechanical properties of this equivalent material, including Young’s modulus (E), Poisson’s ratio, shear modulus, and coefficient of thermal expansion (CTE), are directly obtained by applying either a tensile load or a constant displacement, and by increasing the temperature during simulations, respectively. Analytic results indicate that at least eight microbumps at the outermost region of the chip stacking structure need to be considered as an accurate stress/strain contour in the concerned region. In addition, a factorial experimental design with analysis of variance is proposed to optimize chip stacking structure reliability with four factors: chip thickness, substrate thickness, CTE, and E-value. Analytic results show that the most significant factor is CTE of WLUF. This factor affects microbump reliability and structural warpage under a temperature cycling load and high-temperature bonding process. WLUF with low CTE and high E-value are recommended to enhance the assembly reliability of the 3D-IC architecture. PMID:28793495

B-52 stability augmentation system reliability

NASA Technical Reports Server (NTRS)

Bowling, T. C.; Key, L. W.

1976-01-01

The B-52 SAS (Stability Augmentation System) was developed and retrofitted to nearly 300 aircraft. It actively controls B-52 structural bending, provides improved yaw and pitch damping through sensors and electronic control channels, and puts complete reliance on hydraulic control power for rudder and elevators. The system has experienced over 300,000 flight hours and has exhibited service reliability comparable to the results of the reliability test program. Development experience points out numerous lessons with potential application in the mechanization and development of advanced technology control systems of high reliability.

A Vision for Spaceflight Reliability: NASA's Objectives Based Strategy

NASA Technical Reports Server (NTRS)

Groen, Frank; Evans, John; Hall, Tony

2015-01-01

In defining the direction for a new Reliability and Maintainability standard, OSMA has extracted the essential objectives that our programs need, to undertake a reliable mission. These objectives have been structured to lead mission planning through construction of an objective hierarchy, which defines the critical approaches for achieving high reliability and maintainability (R M). Creating a hierarchy, as a basis for assurance implementation, is a proven approach; yet, it holds the opportunity to enable new directions, as NASA moves forward in tackling the challenges of space exploration.

An Assessment of Reliability and Validity of a Rubric for Grading APA-Style Introductions

ERIC Educational Resources Information Center

Stellmack, Mark A.; Konheim-Kalkstein, Yasmine L.; Manor, Julia E.; Massey, Abigail R.; Schmitz, Julie Ann P.

2009-01-01

This article describes the empirical evaluation of the reliability and validity of a grading rubric for grading APA-style introductions of undergraduate students. Levels of interrater agreement and intrarater agreement were not extremely high but were similar to values reported in the literature for comparably structured rubrics. Rank-order…

Research on High Reliability Organizations: Implications for School Effects Research, Policy, and Educational Practice.

ERIC Educational Resources Information Center

Stringfield, Sam

Current theorizing in education, as in industry, is largely devoted to explaining trial-and-error, failure-tolerant, low-reliability organizations. This article examines changing societal demands on education and argues that effective responses to those demands require new and different organizational structures. Schools must abandon industrial…

Creation of the TXP parenting questionnaire and study of its psychometric properties.

PubMed

Benito, Ana; Calvo, Gema; Real-López, Matías; Gallego, María José; Francés, Sonia; Turbi, Ángel; Haro, Gonzalo

2018-01-15

Parenting is linked to conduct disorders (CD) and substance related disorders (SRD) in adolescents, but with differences according to cultural context. A questionnaire with two versions (parenting questionnaire TXP-A for adolescents and TXP-C  for primary caregivers) was designed using the Delphi method to evaluate parenting practices related to CD and SRD in a Spanish population. It was validated in a community sample of 631 adolescents aged between 14 and 16 and their caregivers. Results suggest a 29-item TXP-A questionnaire with bifactorial structure: affection-communication and control-structure, with high internal (Cronbach’s alpha=0.89) and test-retest (intraclass correlation coefficient=0.94) reliabilities. Both factors are related to SRD (r=0.273, p<0.001) and with most of the psychopathological dimensions studied. The total score and affection-communication are related to dissocial disorder (t=3.259, p=0.001) and its severity (r=-0,119; p=0.003). Inter-observer reliability between adolescents and caregivers is low, in part because the 16-item TXP-C has a different bifactorial structure: affection-communication and prosocial values. TXP-C’s internal (Cronbach’s alpha=0.87) and test-retest (intraclass correlation coefficient=0.94) reliabilities are high. The total score and affection-communication were related to dissocial disorder (t=2.586; p=0.010) but TXP-C did not discriminate according to SRD. In conclusion, the TXP-A questionnaire for adolescents seems to be a reliable, valid and unbiased instrument that evaluates the perception of parenting practices, relating higher affection-communication and control-structure to less psychopathology and alcohol and drug use. TXP-C also seems to be reliable and unbiased, but shows less evidence of validity regarding substance use and psychopathology. .

The process group approach to reliable distributed computing

NASA Technical Reports Server (NTRS)

Birman, Kenneth P.

1992-01-01

The difficulty of developing reliable distribution software is an impediment to applying distributed computing technology in many settings. Experience with the ISIS system suggests that a structured approach based on virtually synchronous process groups yields systems that are substantially easier to develop, exploit sophisticated forms of cooperative computation, and achieve high reliability. Six years of research on ISIS, describing the model, its implementation challenges, and the types of applications to which ISIS has been applied are reviewed.

An overview of computational simulation methods for composite structures failure and life analysis

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

1993-01-01

Three parallel computational simulation methods are being developed at the LeRC Structural Mechanics Branch (SMB) for composite structures failure and life analysis: progressive fracture CODSTRAN; hierarchical methods for high-temperature composites; and probabilistic evaluation. Results to date demonstrate that these methods are effective in simulating composite structures failure/life/reliability.

Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

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

Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke

2015-02-23

Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysismore » also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs.« less

Mechanically and optically reliable folding structure with a hyperelastic material for seamless foldable displays

NASA Astrophysics Data System (ADS)

Kwon, Hyuk-Jun; Shim, HongShik; Kim, Sunkook; Choi, Woong; Chun, Youngtea; Kee, InSeo; Lee, SangYoon

2011-04-01

We report a mechanically and optically robust folding structure to realize a foldable active matrix organic-light-emitting-diode (AMOLED) display without a visible crease at the junction. A nonlinear stress analysis, based on a finite element method, provided an optimized design. The folding-unfolding test on the structure exhibited negligible deterioration of the relative brightness at the junction of the individual panels up to 105 cycles at a folding radius of 1 mm, indicating highly reliable mechanical and optical tolerances. These results demonstrate the feasibility of seamless foldable AMOLED displays, with potentially important technical implications on fabricating large size flexible displays.

Fracture Toughness and Reliability in High-Temperature Structural Ceramics and Composites: Prospects and Challenges for the 21st Century

NASA Technical Reports Server (NTRS)

Dutta, Sunil

1999-01-01

The importance of high fracture toughness and reliability in Si3N4, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defense and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fiber into Si3N4 and SiC matrices. All toughening mechanisms, e.g. crack deflection, crack branching, crack bridging, etc., essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability. Because of flaw insensitivity, continuous fiber reinforced ceramic composite (CFCC) was found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibers should display sufficient high temperature strength and creep resistance at service temperatures above 1000 'C. The greatest challenge to date is the development of high quality ceramic fibers with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are, preparation of optimum matrix precursors, precursor infiltration into fiber array, and matrix densification at a temperature, where grain crystallization and fiber degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems.

Reliability prediction of large fuel cell stack based on structure stress analysis

NASA Astrophysics Data System (ADS)

Liu, L. F.; Liu, B.; Wu, C. W.

2017-09-01

The aim of this paper is to improve the reliability of Proton Electrolyte Membrane Fuel Cell (PEMFC) stack by designing the clamping force and the thickness difference between the membrane electrode assembly (MEA) and the gasket. The stack reliability is directly determined by the component reliability, which is affected by the material property and contact stress. The component contact stress is a random variable because it is usually affected by many uncertain factors in the production and clamping process. We have investigated the influences of parameter variation coefficient on the probability distribution of contact stress using the equivalent stiffness model and the first-order second moment method. The optimal contact stress to make the component stay in the highest level reliability is obtained by the stress-strength interference model. To obtain the optimal contact stress between the contact components, the optimal thickness of the component and the stack clamping force are optimally designed. Finally, a detailed description is given how to design the MEA and gasket dimensions to obtain the highest stack reliability. This work can provide a valuable guidance in the design of stack structure for a high reliability of fuel cell stack.

Large-scale systems: Complexity, stability, reliability

NASA Technical Reports Server (NTRS)

Siljak, D. D.

1975-01-01

After showing that a complex dynamic system with a competitive structure has highly reliable stability, a class of noncompetitive dynamic systems for which competitive models can be constructed is defined. It is shown that such a construction is possible in the context of the hierarchic stability analysis. The scheme is based on the comparison principle and vector Liapunov functions.

Structural reliability assessment capability in NESSUS

NASA Technical Reports Server (NTRS)

Millwater, H.; Wu, Y.-T.

1992-01-01

The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.

Structural reliability assessment capability in NESSUS

NASA Astrophysics Data System (ADS)

Millwater, H.; Wu, Y.-T.

1992-07-01

The principal capabilities of NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), an advanced computer code developed for probabilistic structural response analysis, are reviewed, and its structural reliability assessed. The code combines flexible structural modeling tools with advanced probabilistic algorithms in order to compute probabilistic structural response and resistance, component reliability and risk, and system reliability and risk. An illustrative numerical example is presented.

First Order Reliability Application and Verification Methods for Semistatic Structures

NASA Technical Reports Server (NTRS)

Verderaime, Vincent

1994-01-01

Escalating risks of aerostructures stimulated by increasing size, complexity, and cost should no longer be ignored by conventional deterministic safety design methods. The deterministic pass-fail concept is incompatible with probability and risk assessments, its stress audits are shown to be arbitrary and incomplete, and it compromises high strength materials performance. A reliability method is proposed which combines first order reliability principles with deterministic design variables and conventional test technique to surmount current deterministic stress design and audit deficiencies. Accumulative and propagation design uncertainty errors are defined and appropriately implemented into the classical safety index expression. The application is reduced to solving for a factor that satisfies the specified reliability and compensates for uncertainty errors, and then using this factor as, and instead of, the conventional safety factor in stress analyses. The resulting method is consistent with current analytical skills and verification practices, the culture of most designers, and with the pace of semistatic structural designs.

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.

The Reliability Mandate: Optimizing the Use of Highly Reliable Parts, Materials, and Processes (PM&P) to Maximize System Component Reliability in the Life Cycle

DTIC Science & Technology

2002-06-01

projects are converted into bricks and mortar , as Figure 5 illustrates. Making major changes in LCC after projects are turned over to production is...matter experts ( SMEs ) in the parts, materials, and processes functional area. Data gathering and analysis were conducted through structured interviews...The analysis synthesized feedback and searched for collective issues from the various SMEs on managing PM&P Program requirements, the

Popular or Unpopular? Therapists' Use of Structured Interviews and Their Estimation of Patient Acceptance

ERIC Educational Resources Information Center

Bruchmuller, Katrin; Margraf, Jurgen; Suppiger, Andrea; Schneider, Silvia

2011-01-01

An accurate diagnosis is an important precondition for effective psychotherapeutic treatment. The use of structured interviews provides the gold standard for reliable diagnosis. Suppiger et al. (2009) showed that structured interviews have a high acceptance among patients. On a scale from 0 ("not at all satisfied") to 100 ("totally…

Reliability based impact localization in composite panels using Bayesian updating and the Kalman filter

NASA Astrophysics Data System (ADS)

Morse, Llewellyn; Sharif Khodaei, Zahra; Aliabadi, M. H.

2018-01-01

In this work, a reliability based impact detection strategy for a sensorized composite structure is proposed. Impacts are localized using Artificial Neural Networks (ANNs) with recorded guided waves due to impacts used as inputs. To account for variability in the recorded data under operational conditions, Bayesian updating and Kalman filter techniques are applied to improve the reliability of the detection algorithm. The possibility of having one or more faulty sensors is considered, and a decision fusion algorithm based on sub-networks of sensors is proposed to improve the application of the methodology to real structures. A strategy for reliably categorizing impacts into high energy impacts, which are probable to cause damage in the structure (true impacts), and low energy non-damaging impacts (false impacts), has also been proposed to reduce the false alarm rate. The proposed strategy involves employing classification ANNs with different features extracted from captured signals used as inputs. The proposed methodologies are validated by experimental results on a quasi-isotropic composite coupon impacted with a range of impact energies.

The procedure for determining the residual life of high-temperature aggregates

NASA Astrophysics Data System (ADS)

Nikiforov, A. S.; Prihodko, E. V.; Kinzhibekova, A. K.; Karmanov, A. E.

2018-01-01

One of the main reasons for the withdrawal of high-temperature aggregates for repairs is the destruction of enclosing structures due to the occurrence of temperature stresses. A wide range of refractory materials used, a large number of product names, a difference in the operation of even the same aggregates makes it impossible to apply general principles for determining the residual resource of high-temperature aggregates, which is based, as a rule, on the determination of temperature stresses. In the article there is suggested a technique based on the method of simulation modeling, allowing to estimate the remaining resource and reliability of the operating equipment. There are given data on the calculation of these indicators for a 25-ton steel-casting ladle. The values obtained make it possible to evaluate the rationality of the further operation of the high-temperature unit by the condition of reliability of the enclosing structures.

Fatigue Reliability of Gas Turbine Engine Structures

NASA Technical Reports Server (NTRS)

Cruse, Thomas A.; Mahadevan, Sankaran; Tryon, Robert G.

1997-01-01

The results of an investigation are described for fatigue reliability in engine structures. The description consists of two parts. Part 1 is for method development. Part 2 is a specific case study. In Part 1, the essential concepts and practical approaches to damage tolerance design in the gas turbine industry are summarized. These have evolved over the years in response to flight safety certification requirements. The effect of Non-Destructive Evaluation (NDE) methods on these methods is also reviewed. Assessment methods based on probabilistic fracture mechanics, with regard to both crack initiation and crack growth, are outlined. Limit state modeling techniques from structural reliability theory are shown to be appropriate for application to this problem, for both individual failure mode and system-level assessment. In Part 2, the results of a case study for the high pressure turbine of a turboprop engine are described. The response surface approach is used to construct a fatigue performance function. This performance function is used with the First Order Reliability Method (FORM) to determine the probability of failure and the sensitivity of the fatigue life to the engine parameters for the first stage disk rim of the two stage turbine. A hybrid combination of regression and Monte Carlo simulation is to use incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system fatigue life to the engine parameters of the high pressure turbine. 'ne variation in the primary hot gas and secondary cooling air, the uncertainty of the complex mission loading, and the scatter in the material data are considered.

Reliability of the Structured Clinical Interview for DSM-5 Sleep Disorders Module.

PubMed

Taylor, Daniel J; Wilkerson, Allison K; Pruiksma, Kristi E; Williams, Jacob M; Ruggero, Camilo J; Hale, Willie; Mintz, Jim; Organek, Katherine Marczyk; Nicholson, Karin L; Litz, Brett T; Young-McCaughan, Stacey; Dondanville, Katherine A; Borah, Elisa V; Brundige, Antoinette; Peterson, Alan L

2018-03-15

To develop and demonstrate interrater reliability for a Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Sleep Disorders (SCISD). The SCISD was designed to be a brief, reliable, and valid interview assessment of adult sleep disorders as defined by the DSM-5. A sample of 106 postdeployment active-duty military members seeking cognitive behavioral therapy for insomnia in a randomized clinical trial were assessed with the SCISD prior to treatment to determine eligibility. Audio recordings of these interviews were double-scored for interrater reliability. The interview is 8 pages long, includes 20 to 51 questions, and takes 10 to 20 minutes to administer. Of the nine major disorders included in the SCISD, six had prevalence rates high enough (ie, n ≥ 5) to include in analyses. Cohen kappa coefficient (κ) was used to assess interrater reliability for insomnia, hypersomnolence, obstructive sleep apnea hypopnea (OSAH), circadian rhythm sleep-wake, nightmare, and restless legs syndrome disorders. There was excellent interrater reliability for insomnia (1.0) and restless legs syndrome (0.83); very good reliability for nightmare disorder (0.78) and OSAH (0.73); and good reliability for hypersomnolence (0.50) and circadian rhythm sleep-wake disorders (0.50). The SCISD is a brief, structured clinical interview that is easy for clinicians to learn and use. The SCISD showed moderate to excellent interrater reliability for six of the major sleep disorders in the DSM-5 among active duty military seeking cognitive behavioral therapy for insomnia in a randomized clinical trial. Replication and extension studies are needed. Registry: ClinicalTrials.gov; Title: Comparing Internet and In-Person Brief Cognitive Behavioral Therapy of Insomnia; Identifier: NCT01549899; URL: https://clinicaltrials.gov/ct2/show/NCT01549899. © 2018 American Academy of Sleep Medicine.

Reliability analysis applied to structural tests

NASA Technical Reports Server (NTRS)

Diamond, P.; Payne, A. O.

1972-01-01

The application of reliability theory to predict, from structural fatigue test data, the risk of failure of a structure under service conditions because its load-carrying capability is progressively reduced by the extension of a fatigue crack, is considered. The procedure is applicable to both safe-life and fail-safe structures and, for a prescribed safety level, it will enable an inspection procedure to be planned or, if inspection is not feasible, it will evaluate the life to replacement. The theory has been further developed to cope with the case of structures with initial cracks, such as can occur in modern high-strength materials which are susceptible to the formation of small flaws during the production process. The method has been applied to a structure of high-strength steel and the results are compared with those obtained by the current life estimation procedures. This has shown that the conventional methods can be unconservative in certain cases, depending on the characteristics of the structure and the design operating conditions. The suitability of the probabilistic approach to the interpretation of the results from full-scale fatigue testing of aircraft structures is discussed and the assumptions involved are examined.

Psychometric Properties of the School Attitude Assessment Survey-Revised with International Baccalaureate High School Students

ERIC Educational Resources Information Center

Dedrick, Robert F.; Shaunessy-Dedrick, Elizabeth; Suldo, Shannon M.; Ferron, John M.

2015-01-01

In two studies (ns = 312 and 1,149) with 9- to 12-grade students in pre-International Baccalaureate (IB) and IB Diploma programs, we evaluated the reliability, factor structure, measurement invariance, and criterion-related validity of the scores from the School Attitude Assessment Survey-Revised (SAAS-R). Reliabilities of the five SAAS-R subscale…

Increased reliability of nuclear magnetic resonance protein structures by consensus structure bundles.

PubMed

Buchner, Lena; Güntert, Peter

2015-02-03

Nuclear magnetic resonance (NMR) structures are represented by bundles of conformers calculated from different randomized initial structures using identical experimental input data. The spread among these conformers indicates the precision of the atomic coordinates. However, there is as yet no reliable measure of structural accuracy, i.e., how close NMR conformers are to the "true" structure. Instead, the precision of structure bundles is widely (mis)interpreted as a measure of structural quality. Attempts to increase precision often overestimate accuracy by tight bundles of high precision but much lower accuracy. To overcome this problem, we introduce a protocol for NMR structure determination with the software package CYANA, which produces, like the traditional method, bundles of conformers in agreement with a common set of conformational restraints but with a realistic precision that is, throughout a variety of proteins and NMR data sets, a much better estimate of structural accuracy than the precision of conventional structure bundles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Failure Mode and Effects Analysis: views of hospital staff in the UK.

PubMed

Shebl, Nada; Franklin, Bryony; Barber, Nick; Burnett, Susan; Parand, Anam

2012-01-01

To explore health care professionals' experiences and perceptions of Failure Mode and Effects Analysis (FMEA), a team-based, prospective risk analysis technique. Semi-structured interviews were conducted with 21 operational leads (20 pharmacists, one nurse) in medicines management teams of hospitals participating in a national quality improvement programme. Interviews were transcribed, coded and emergent themes identified using framework analysis. Themes identified included perceptions and experiences of participants with FMEA, validity and reliability issues, and FMEA's use in practice. FMEA was considered to be a structured but subjective process that helps health care professionals get together to identify high risk areas of care. Both positive and negative opinions were expressed, with the majority of interviewees expressing positive views towards FMEA in relation to its structured nature and the use of a multidisciplinary team. Other participants criticised FMEA for being subjective and lacking validity. Most likely to restrict its widespread use were its time consuming nature and its perceived lack of validity and reliability. FMEA is a subjective but systematic tool that helps identify high risk areas, but its time consuming nature, difficulty with the scores and perceived lack of validity and reliability may limit its widespread use.

Static test induced loads verification beyond elastic limit

NASA Technical Reports Server (NTRS)

Verderaime, V.; Harrington, F.

1996-01-01

Increasing demands for reliable and least-cost high-performance aerostructures are pressing design analyses, materials, and manufacturing processes to new and narrowly experienced performance and verification technologies. This study assessed the adequacy of current experimental verification of the traditional binding ultimate safety factor which covers rare events in which no statistical design data exist. Because large high-performance structures are inherently very flexible, boundary rotations and deflections under externally applied loads approaching fracture may distort their transmission and unknowingly accept submarginal structures or prematurely fracturing reliable ones. A technique was developed, using measured strains from back-to-back surface mounted gauges, to analyze, define, and monitor induced moments and plane forces through progressive material changes from total-elastic to total-inelastic zones within the structural element cross section. Deviations from specified test loads are identified by the consecutively changing ratios of moment-to-axial load.

Static test induced loads verification beyond elastic limit

NASA Technical Reports Server (NTRS)

Verderaime, V.; Harrington, F.

1996-01-01

Increasing demands for reliable and least-cost high performance aerostructures are pressing design analyses, materials, and manufacturing processes to new and narrowly experienced performance and verification technologies. This study assessed the adequacy of current experimental verification of the traditional binding ultimate safety factor which covers rare events in which no statistical design data exist. Because large, high-performance structures are inherently very flexible, boundary rotations and deflections under externally applied loads approaching fracture may distort their transmission and unknowingly accept submarginal structures or prematurely fracturing reliable ones. A technique was developed, using measured strains from back-to-back surface mounted gauges, to analyze, define, and monitor induced moments and plane forces through progressive material changes from total-elastic to total inelastic zones within the structural element cross section. Deviations from specified test loads are identified by the consecutively changing ratios of moment-to-axial load.

Structural Analyses of Stirling Power Convertor Heater Head for Long-Term Reliability, Durability, and Performance

NASA Technical Reports Server (NTRS)

Halford, Gary R.; Shah, Ashwin; Arya, Vinod K.; Krause, David L.; Bartolotta, Paul A.

2002-01-01

Deep-space missions require onboard electric power systems with reliable design lifetimes of up to 10 yr and beyond. A high-efficiency Stirling radioisotope power system is a likely candidate for future deep-space missions and Mars rover applications. To ensure ample durability, the structurally critical heater head of the Stirling power convertor has undergone extensive computational analyses of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Durability predictions are presented in terms of the probability of survival. A benchmark structural testing program has commenced to support the analyses. This report presents the current status of durability assessments.

High-fidelity large area nano-patterning of silicon with femtosecond light sheet

NASA Astrophysics Data System (ADS)

Sidhu, Mehra S.; Munjal, Pooja; Singh, Kamal P.

2018-01-01

We employ a femtosecond light sheet generated by a cylindrical lens to rapidly produce high-fidelity nano-structures over large area on silicon surface. The Fourier analysis of electron microscopy images of the laser-induced surface structures reveals sharp peaks indicating good homogeneity. We observed an emergence of second-order spatial periodicity on increasing the scan speed. Our reliable approach may rapidly nano-pattern curved solid surfaces and tiny objects for diverse potential applications in optical devices, structural coloring, plasmonic substrates and in high-harmonic generation.

Electrical characteristics of high-power AlGaN-GaN high electron mobility transistors irradiated with protons and heavy ions

NASA Astrophysics Data System (ADS)

Sin, Yongkun; Bonsall, Jeremy; Lingley, Zachary; Brodie, Miles; Mason, Maribeth

2017-02-01

High electron mobility transistors (HEMTs) based on AlGaN-GaN hetero-structures are finding an increasing number of commercial and military applications that require high voltage, high power, and high efficiency operation. In recent years, leading GaN HEMT manufacturers have reported excellent RF power characteristics and encouraging reliability, but long-term reliability in the space environment still remains a major concern due to a large number of defects and traps present both in the bulk as well as at the surface, leading to undesirable characteristics including current collapse. Furthermore, degradation mechanisms in GaN HEMTs are still not well understood. Thus, reliability and radiation effects of GaN HEMTs should be studied before solid state power amplifiers (SSPAs) based on GaN HEMT technology are successfully deployed in space satellite systems. For the present study, we investigated electrical characteristics of high-power GaN HEMTs irradiated with protons and heavy ions under various irradiation and biasing conditions.

Reliability and risk assessment of structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.

1991-01-01

Development of reliability and risk assessment of structural components and structures is a major activity at Lewis Research Center. It consists of five program elements: (1) probabilistic loads; (2) probabilistic finite element analysis; (3) probabilistic material behavior; (4) assessment of reliability and risk; and (5) probabilistic structural performance evaluation. Recent progress includes: (1) the evaluation of the various uncertainties in terms of cumulative distribution functions for various structural response variables based on known or assumed uncertainties in primitive structural variables; (2) evaluation of the failure probability; (3) reliability and risk-cost assessment; and (4) an outline of an emerging approach for eventual certification of man-rated structures by computational methods. Collectively, the results demonstrate that the structural durability/reliability of man-rated structural components and structures can be effectively evaluated by using formal probabilistic methods.

Improved reliability of wind turbine towers with active tuned mass dampers (ATMDs)

NASA Astrophysics Data System (ADS)

Fitzgerald, Breiffni; Sarkar, Saptarshi; Staino, Andrea

2018-04-01

Modern multi-megawatt wind turbines are composed of slender, flexible, and lightly damped blades and towers. These components exhibit high susceptibility to wind-induced vibrations. As the size, flexibility and cost of the towers have increased in recent years, the need to protect these structures against damage induced by turbulent aerodynamic loading has become apparent. This paper combines structural dynamic models and probabilistic assessment tools to demonstrate improvements in structural reliability when modern wind turbine towers are equipped with active tuned mass dampers (ATMDs). This study proposes a multi-modal wind turbine model for wind turbine control design and analysis. This study incorporates an ATMD into the tower of this model. The model is subjected to stochastically generated wind loads of varying speeds to develop wind-induced probabilistic demand models for towers of modern multi-megawatt wind turbines under structural uncertainty. Numerical simulations have been carried out to ascertain the effectiveness of the active control system to improve the structural performance of the wind turbine and its reliability. The study constructs fragility curves, which illustrate reductions in the vulnerability of towers to wind loading owing to the inclusion of the damper. Results show that the active controller is successful in increasing the reliability of the tower responses. According to the analysis carried out in this paper, a strong reduction of the probability of exceeding a given displacement at the rated wind speed has been observed.

Accounting for Proof Test Data in a Reliability Based Design Optimization Framework

NASA Technical Reports Server (NTRS)

Ventor, Gerharad; Scotti, Stephen J.

2012-01-01

This paper investigates the use of proof (or acceptance) test data during the reliability based design optimization of structural components. It is assumed that every component will be proof tested and that the component will only enter into service if it passes the proof test. The goal is to reduce the component weight, while maintaining high reliability, by exploiting the proof test results during the design process. The proposed procedure results in the simultaneous design of the structural component and the proof test itself and provides the designer with direct control over the probability of failing the proof test. The procedure is illustrated using two analytical example problems and the results indicate that significant weight savings are possible when exploiting the proof test results during the design process.

Assessment of mesh simplification algorithm quality

NASA Astrophysics Data System (ADS)

Roy, Michael; Nicolier, Frederic; Foufou, S.; Truchetet, Frederic; Koschan, Andreas; Abidi, Mongi A.

2002-03-01

Traditionally, medical geneticists have employed visual inspection (anthroposcopy) to clinically evaluate dysmorphology. In the last 20 years, there has been an increasing trend towards quantitative assessment to render diagnosis of anomalies more objective and reliable. These methods have focused on direct anthropometry, using a combination of classical physical anthropology tools and new instruments tailor-made to describe craniofacial morphometry. These methods are painstaking and require that the patient remain still for extended periods of time. Most recently, semiautomated techniques (e.g., structured light scanning) have been developed to capture the geometry of the face in a matter of seconds. In this paper, we establish that direct anthropometry and structured light scanning yield reliable measurements, with remarkably high levels of inter-rater and intra-rater reliability, as well as validity (contrasting the two methods).

90-kilobar diamond-anvil high-pressure cell for use on an automatic diffractometer.

PubMed

Schiferl, D; Jamieson, J C; Lenko, J E

1978-03-01

A gasketed diamond-anvil high-pressure cell is described which can be used on a four-circle automatic diffractometer to collect x-ray intensity data from single-crystal samples subjected to truly hydrostatic pressures of over 90 kilobars. The force generating system exerts only forces normal to the diamond faces to obtain maximum reliability. A unique design allows exceptionally large open areas for maximum x-ray access and is particularly well suited for highly absorbing materials, as the x rays are not transmitted through the sample. Studies on ruby show that high-pressure crystal structure determinations may be done rapidly, reliably, and routinely with this system.

A test-retest dataset for assessing long-term reliability of brain morphology and resting-state brain activity.

PubMed

Huang, Lijie; Huang, Taicheng; Zhen, Zonglei; Liu, Jia

2016-03-15

We present a test-retest dataset for evaluation of long-term reliability of measures from structural and resting-state functional magnetic resonance imaging (sMRI and rfMRI) scans. The repeated scan dataset was collected from 61 healthy adults in two sessions using highly similar imaging parameters at an interval of 103-189 days. However, as the imaging parameters were not completely identical, the reliability estimated from this dataset shall reflect the lower bounds of the true reliability of sMRI/rfMRI measures. Furthermore, in conjunction with other test-retest datasets, our dataset may help explore the impact of different imaging parameters on reliability of sMRI/rfMRI measures, which is especially critical for assessing datasets collected from multiple centers. In addition, intelligence quotient (IQ) was measured for each participant using Raven's Advanced Progressive Matrices. The data can thus be used for purposes other than assessing reliability of sMRI/rfMRI alone. For example, data from each single session could be used to associate structural and functional measures of the brain with the IQ metrics to explore brain-IQ association.

Assessment of Semi-Structured Clinical Interview for Mobile Phone Addiction Disorder.

PubMed

Alavi, Seyyed Salman; Mohammadi, Mohammad Reza; Jannatifard, Fereshteh; Mohammadi Kalhori, Soroush; Sepahbodi, Ghazal; BabaReisi, Mohammad; Sajedi, Sahar; Farshchi, Mojtaba; KhodaKarami, Rasul; Hatami Kasvaee, Vahid

2016-04-01

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) classified mobile phone addiction disorder under "impulse control disorder not elsewhere classified". This study surveyed the diagnostic criteria of DSM-IV-TR for the diagnosis of mobile phone addiction in correspondence with Iranian society and culture. Two hundred fifty students of Tehran universities were entered into this descriptive-analytical and cross-sectional study. Quota sampling method was used. At first, semi- structured clinical interview (based on DSM-IV-TR) was performed for all the cases, and another specialist reevaluated the interviews. Data were analyzed using content validity, inter-scorer reliability (Kappa coefficient) and test-retest via SPSS18 software. The content validity of the semi- structured clinical interview matched the DSM-IV-TR criteria for behavioral addiction. Moreover, their content was appropriate, and two items, including "SMS pathological use" and "High monthly cost of using the mobile phone" were added to promote its validity. Internal reliability (Kappa) and test-retest reliability were 0.55 and r = 0.4 (p<0. 01) respectively. The results of this study revealed that semi- structured diagnostic criteria of DSM-IV-TR are valid and reliable for diagnosing mobile phone addiction, and this instrument is an effective tool to diagnose this disorder.

Measurement of Family Affective Structure.

ERIC Educational Resources Information Center

Lowman, Joseph

1980-01-01

Three studies demonstrate that the Inventory of Family Feelings, a measure of family affective structure, has high reliability and construct and concurrent validity. It is appropriate for affective comparisons by age, sex, and ordinal position of children and for measuring change after family or marital therapy, or after predictable stress…

Contemporary Methodology for Protein Structure Determination.

ERIC Educational Resources Information Center

Hunkapiller, Michael W.; And Others

1984-01-01

Describes the nature and capabilities of methods used to characterize protein and peptide structure, indicating that they have undergone changes which have improved the speed, reliability, and applicability of the process. Also indicates that high-performance liquid chromatography and gel electrophoresis have made purifying proteins and peptides a…

An accurate and efficient reliability-based design optimization using the second order reliability method and improved stability transformation method

NASA Astrophysics Data System (ADS)

Meng, Zeng; Yang, Dixiong; Zhou, Huanlin; Yu, Bo

2018-05-01

The first order reliability method has been extensively adopted for reliability-based design optimization (RBDO), but it shows inaccuracy in calculating the failure probability with highly nonlinear performance functions. Thus, the second order reliability method is required to evaluate the reliability accurately. However, its application for RBDO is quite challenge owing to the expensive computational cost incurred by the repeated reliability evaluation and Hessian calculation of probabilistic constraints. In this article, a new improved stability transformation method is proposed to search the most probable point efficiently, and the Hessian matrix is calculated by the symmetric rank-one update. The computational capability of the proposed method is illustrated and compared to the existing RBDO approaches through three mathematical and two engineering examples. The comparison results indicate that the proposed method is very efficient and accurate, providing an alternative tool for RBDO of engineering structures.

Simplified Technique for Predicting Offshore Pipeline Expansion

NASA Astrophysics Data System (ADS)

Seo, J. H.; Kim, D. K.; Choi, H. S.; Yu, S. Y.; Park, K. S.

2018-06-01

In this study, we propose a method for estimating the amount of expansion that occurs in subsea pipelines, which could be applied in the design of robust structures that transport oil and gas from offshore wells. We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines. Due to the effects of high pressure and high temperature, the production of fluid from offshore wells is typically caused by physical deformation of subsea structures, e.g., expansion and contraction during the transportation process. In severe cases, vertical and lateral buckling occurs, which causes a significant negative impact on structural safety, and which is related to on-bottom stability, free-span, structural collapse, and many other factors. In addition, these factors may affect the production rate with respect to flow assurance, wax, and hydration, to name a few. In this study, we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage, which can lead to savings in both cost and computation time. As such, in this paper, we propose an applicable diagram, which we call the standard dimensionless ratio (SDR) versus virtual anchor length (L A ) diagram, that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios. With this user guideline, offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation, design, and maintenance of the subsea pipeline.

The decay of NASA's technical culture

NASA Technical Reports Server (NTRS)

Mccurdy, Howard E.

1989-01-01

Changes in the organization structure and technical research activities of NASA since 1970 are evaluated. The creation of NASA and the original organizational structure and operation of NASA are reviewed. The relationship between organization and advanced technology is discussed and suggestions are given for ways of maintaining NASA as a high reliability organization.

The German Version of the Gaze Anxiety Rating Scale (GARS): Reliability and Validity

PubMed Central

Domes, Gregor; Marx, Lisa; Spenthof, Ines; Heinrichs, Markus

2016-01-01

Objective Fear of eye gaze and avoidance of eye contact are core features of social anxiety disorders (SAD). To measure self-reported fear and avoidance of eye gaze, the Gaze Anxiety Rating Scale (GARS) has been developed and validated in recent years in its English version. The main objectives of the present study were to psychometrically evaluate the German translation of the GARS concerning its reliability, factorial structure, and validity. Methods Three samples of participants were enrolled in the study. (1) A non-patient sample (n = 353) completed the GARS and a set of trait questionnaires to assess internal consistency, test-retest reliability, factorial structure, and concurrent and divergent validity. (2) A sample of patients with SAD (n = 33) was compared to a healthy control group (n = 30) regarding their scores on the GARS and the trait measures. Results The German GARS fear and avoidance scales exhibited excellent internal consistency and high stability over 2 and 4 months, as did the original version. The English version’s factorial structure was replicated, yielding two categories of situations: (1) everyday situations and (2) situations involving high evaluative threat. GARS fear and avoidance displayed convergent validity with trait measures of social anxiety and were markedly higher in patients with GSAD than in healthy controls. Fear and avoidance of eye contact in situations involving high levels of evaluative threat related more closely to social anxiety than to gaze anxiety in everyday situations. Conclusions The German version of the GARS has demonstrated reliability and validity similar to the original version, and is thus well suited to capture fear and avoidance of eye contact in different social situations as a valid self-report measure of social anxiety and related disorders in the social domain for use in both clinical practice and research. PMID:26937638

The German Version of the Gaze Anxiety Rating Scale (GARS): Reliability and Validity.

PubMed

Domes, Gregor; Marx, Lisa; Spenthof, Ines; Heinrichs, Markus

2016-01-01

Fear of eye gaze and avoidance of eye contact are core features of social anxiety disorders (SAD). To measure self-reported fear and avoidance of eye gaze, the Gaze Anxiety Rating Scale (GARS) has been developed and validated in recent years in its English version. The main objectives of the present study were to psychometrically evaluate the German translation of the GARS concerning its reliability, factorial structure, and validity. Three samples of participants were enrolled in the study. (1) A non-patient sample (n = 353) completed the GARS and a set of trait questionnaires to assess internal consistency, test-retest reliability, factorial structure, and concurrent and divergent validity. (2) A sample of patients with SAD (n = 33) was compared to a healthy control group (n = 30) regarding their scores on the GARS and the trait measures. The German GARS fear and avoidance scales exhibited excellent internal consistency and high stability over 2 and 4 months, as did the original version. The English version's factorial structure was replicated, yielding two categories of situations: (1) everyday situations and (2) situations involving high evaluative threat. GARS fear and avoidance displayed convergent validity with trait measures of social anxiety and were markedly higher in patients with GSAD than in healthy controls. Fear and avoidance of eye contact in situations involving high levels of evaluative threat related more closely to social anxiety than to gaze anxiety in everyday situations. The German version of the GARS has demonstrated reliability and validity similar to the original version, and is thus well suited to capture fear and avoidance of eye contact in different social situations as a valid self-report measure of social anxiety and related disorders in the social domain for use in both clinical practice and research.

Flexible Transparent Conductive Films with High Performance and Reliability Using Hybrid Structures of Continuous Metal Nanofiber Networks for Flexible Optoelectronics.

PubMed

Park, Juyoung; Hyun, Byung Gwan; An, Byeong Wan; Im, Hyeon-Gyun; Park, Young-Geun; Jang, Junho; Park, Jang-Ung; Bae, Byeong-Soo

2017-06-21

We report an Ag nanofiber-embedded glass-fabric reinforced hybrimer (AgNF-GFRHybrimer) composite film as a reliable and high-performance flexible transparent conducting film. The continuous AgNF network provides superior optoelectronic properties of the composite film by minimizing transmission loss and junction resistance. In addition, the excellent thermal/chemical stability and mechanical durability of the GFRHybrimer matrix provides enhanced mechanical durability and reliability of the final AgNF-GFRHybrimer composite film. To demonstrate the availability of our AgNF-GFRHybrimer composite as a transparent conducting film, we fabricated a flexible organic light-emitting diode (OLED) device on the AgNF-GFRHybrimer film; the OLED showed stable operation during a flexing.

Development and thermal management of 10 kW CW, direct diode laser source

NASA Astrophysics Data System (ADS)

Zhu, Hongbo; Hao, Mingming; Zhang, Jianwei; Ji, Wenyu; Lin, Xingchen; Zhang, Jinsheng; Ning, Yongqiang

2016-01-01

We report on the development of direct diode laser source with high-power and high reliability. The laser source was realized by the polarization and wavelength combination of four diode laser stacks. When at the operating current of 122 A, the source was capable of producing 10,120 W output while maintaining 46% electro-optical conversion efficiency. The maximum temperature on the lens was decreased from 442.2 K to 320 K by utilizing an efficient thermal dissipation structure, and the corresponding maximum von Mises stress was reduced from 75.4 MPa to 14 MPa. In addition, a reliability test demonstrated that our laser source was reliable and potential in the applications of laser cladding and heat treatment.

First-order reliability application and verification methods for semistatic structures

NASA Astrophysics Data System (ADS)

Verderaime, V.

1994-11-01

Escalating risks of aerostructures stimulated by increasing size, complexity, and cost should no longer be ignored in conventional deterministic safety design methods. The deterministic pass-fail concept is incompatible with probability and risk assessments; stress audits are shown to be arbitrary and incomplete, and the concept compromises the performance of high-strength materials. A reliability method is proposed that combines first-order reliability principles with deterministic design variables and conventional test techniques to surmount current deterministic stress design and audit deficiencies. Accumulative and propagation design uncertainty errors are defined and appropriately implemented into the classical safety-index expression. The application is reduced to solving for a design factor that satisfies the specified reliability and compensates for uncertainty errors, and then using this design factor as, and instead of, the conventional safety factor in stress analyses. The resulting method is consistent with current analytical skills and verification practices, the culture of most designers, and the development of semistatic structural designs.

Highly-reliable operation of 638-nm broad stripe laser diode with high wall-plug efficiency for display applications

NASA Astrophysics Data System (ADS)

Yagi, Tetsuya; Shimada, Naoyuki; Nishida, Takehiro; Mitsuyama, Hiroshi; Miyashita, Motoharu

2013-03-01

Laser based displays, as pico to cinema laser projectors have gathered much attention because of wide gamut, low power consumption, and so on. Laser light sources for the displays are operated mainly in CW, and heat management is one of the big issues. Therefore, highly efficient operation is necessitated. Also the light sources for the displays are requested to be highly reliable. 638 nm broad stripe laser diode (LD) was newly developed for high efficiency and highly reliable operation. An AlGaInP/GaAs red LD suffers from low wall plug efficiency (WPE) due to electron overflow from an active layer to a p-cladding layer. Large optical confinement factor (Γ) design with AlInP cladding layers is adopted to improve the WPE. The design has a disadvantage for reliable operation because the large Γ causes high optical density and brings a catastrophic optical degradation (COD) at a front facet. To overcome the disadvantage, a window-mirror structure is also adopted in the LD. The LD shows WPE of 35% at 25°C, highest record in the world, and highly stable operation at 35°C, 550 mW up to 8,000 hours without any catastrophic optical degradation.

Probabilistic Assessment of High-Throughput Wireless Sensor Networks

PubMed Central

Kim, Robin E.; Mechitov, Kirill; Sim, Sung-Han; Spencer, Billie F.; Song, Junho

2016-01-01

Structural health monitoring (SHM) using wireless smart sensors (WSS) has the potential to provide rich information on the state of a structure. However, because of their distributed nature, maintaining highly robust and reliable networks can be challenging. Assessing WSS network communication quality before and after finalizing a deployment is critical to achieve a successful WSS network for SHM purposes. Early studies on WSS network reliability mostly used temporal signal indicators, composed of a smaller number of packets, to assess the network reliability. However, because the WSS networks for SHM purpose often require high data throughput, i.e., a larger number of packets are delivered within the communication, such an approach is not sufficient. Instead, in this study, a model that can assess, probabilistically, the long-term performance of the network is proposed. The proposed model is based on readily-available measured data sets that represent communication quality during high-throughput data transfer. Then, an empirical limit-state function is determined, which is further used to estimate the probability of network communication failure. Monte Carlo simulation is adopted in this paper and applied to a small and a full-bridge wireless networks. By performing the proposed analysis in complex sensor networks, an optimized sensor topology can be achieved. PMID:27258270

A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference.

PubMed

Sahoo, Prasan Kumar; Pattanaik, Sudhir Ranjan; Wu, Shih-Lin

2017-06-07

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new channel access mechanism is designed for the buffer constraint sensor devices to reduce the packet drop rate, energy consumption and collisions. In order to avoid collision due to the hidden terminal problem, a new frame structure is designed for the data transmission. A new superframe structure is proposed to mitigate the problems due to WiFi and ZigBee interference. A modified superframe structure with a new retransmission opportunity for failure devices is proposed to reduce the collisions and retransmission delay with high reliability. Performance evaluation and validation of our scheme indicate that the packet drop rate, throughput, reliability, energy consumption and average delay of the nodes can be improved significantly.

Time-Varying, Multi-Scale Adaptive System Reliability Analysis of Lifeline Infrastructure Networks

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

Gearhart, Jared Lee; Kurtz, Nolan Scot

2014-09-01

The majority of current societal and economic needs world-wide are met by the existing networked, civil infrastructure. Because the cost of managing such infrastructure is high and increases with time, risk-informed decision making is essential for those with management responsibilities for these systems. To address such concerns, a methodology that accounts for new information, deterioration, component models, component importance, group importance, network reliability, hierarchical structure organization, and efficiency concerns has been developed. This methodology analyzes the use of new information through the lens of adaptive Importance Sampling for structural reliability problems. Deterioration, multi-scale bridge models, and time-variant component importance aremore » investigated for a specific network. Furthermore, both bridge and pipeline networks are studied for group and component importance, as well as for hierarchical structures in the context of specific networks. Efficiency is the primary driver throughout this study. With this risk-informed approach, those responsible for management can address deteriorating infrastructure networks in an organized manner.« less

Precarious employment in Chile: psychometric properties of the Chilean version of Employment Precariousness Scale in private sector workers.

PubMed

Vives-Vergara, Alejandra; González-López, Francisca; Solar, Orielle; Bernales-Baksai, Pamela; González, María José; Benach, Joan

2017-04-20

The purpose of this study is to perform a psychometric analysis (acceptability, reliability and factor structure) of the Chilean version of the new Employment Precariousness Scale (EPRES). The data is drawn from a sample of 4,248 private salaried workers with a formal contract from the first Chilean Employment Conditions, Work, Health and Quality of Life (ENETS) survey, applied to a nationally representative sample of the Chilean workforce in 2010. Item and scale-level statistics were performed to assess scaling properties, acceptability and reliability. The six-dimensional factor structure was examined with confirmatory factor analysis. The scale exhibited high acceptability (roughly 80%) and reliability (Cronbach's alpha 0.83) and the factor structure was confirmed. One subscale (rights) demonstrated poorer metric properties without compromising the overall scale. The Chilean version of the Employment Precariousness Scale (EPRES-Ch) demonstrated good metric properties, pointing to its suitability for use in epidemiologic and public health research.

Research on the optimal structure configuration of dither RLG used in skewed redundant INS

NASA Astrophysics Data System (ADS)

Gao, Chunfeng; Wang, Qi; Wei, Guo; Long, Xingwu

2016-05-01

The actual combat effectiveness of weapon equipment is restricted by the performance of Inertial Navigation System (INS), especially in high reliability required situations such as fighter, satellite and submarine. Through the use of skewed sensor geometries, redundant technique has been applied to reduce the cost and improve the reliability of the INS. In this paper, the structure configuration and the inertial sensor characteristics of Skewed Redundant Strapdown Inertial Navigation System (SRSINS) using dithered Ring Laser Gyroscope (RLG) are analyzed. For the dither coupling effects of the dither gyro, the system measurement errors can be amplified either the individual gyro dither frequency is near one another or the structure of the SRSINS is unreasonable. Based on the characteristics of RLG, the research on coupled vibration of dithered RLG in SRSINS is carried out. On the principle of optimal navigation performance, optimal reliability and optimal cost-effectiveness, the comprehensive evaluation scheme of the inertial sensor configuration of SRINS is given.

A Reliable Data Transmission Model for IEEE 802.15.4e Enabled Wireless Sensor Network under WiFi Interference

PubMed Central

Sahoo, Prasan Kumar; Pattanaik, Sudhir Ranjan; Wu, Shih-Lin

2017-01-01

The IEEE 802.15.4e standard proposes Medium Access Control (MAC) to support collision-free wireless channel access mechanisms for industrial, commercial and healthcare applications. However, unnecessary wastage of energy and bandwidth consumption occur due to inefficient backoff management and collisions. In this paper, a new channel access mechanism is designed for the buffer constraint sensor devices to reduce the packet drop rate, energy consumption and collisions. In order to avoid collision due to the hidden terminal problem, a new frame structure is designed for the data transmission. A new superframe structure is proposed to mitigate the problems due to WiFi and ZigBee interference. A modified superframe structure with a new retransmission opportunity for failure devices is proposed to reduce the collisions and retransmission delay with high reliability. Performance evaluation and validation of our scheme indicate that the packet drop rate, throughput, reliability, energy consumption and average delay of the nodes can be improved significantly. PMID:28590434

A system methodology for optimization design of the structural crashworthiness of a vehicle subjected to a high-speed frontal crash

NASA Astrophysics Data System (ADS)

Xia, Liang; Liu, Weiguo; Lv, Xiaojiang; Gu, Xianguang

2018-04-01

The structural crashworthiness design of vehicles has become an important research direction to ensure the safety of the occupants. To effectively improve the structural safety of a vehicle in a frontal crash, a system methodology is presented in this study. The surrogate model of Online support vector regression (Online-SVR) is adopted to approximate crashworthiness criteria and different kernel functions are selected to enhance the accuracy of the model. The Online-SVR model is demonstrated to have the advantages of solving highly nonlinear problems and saving training costs, and can effectively be applied for vehicle structural crashworthiness design. By combining the non-dominated sorting genetic algorithm II and Monte Carlo simulation, both deterministic optimization and reliability-based design optimization (RBDO) are conducted. The optimization solutions are further validated by finite element analysis, which shows the effectiveness of the RBDO solution in the structural crashworthiness design process. The results demonstrate the advantages of using RBDO, resulting in not only increased energy absorption and decreased structural weight from a baseline design, but also a significant improvement in the reliability of the design.

Exploration of multi-fold symmetry element-loaded superconducting radio frequency structure for reliable acceleration of low- & medium-beta ion species

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

Huang, Shichun; Geng, Rongli

2015-09-01

Reliable acceleration of low- to medium-beta proton or heavy ion species is needed for future high-current superconducting radio frequency (SRF) accelerators. Due to the high-Q nature of an SRF resonator, it is sensitive to many factors such as electron loading (from either the accelerated beam or from parasitic field emitted electrons), mechanical vibration, and liquid helium bath pressure fluctuation etc. To increase the stability against those factors, a mechanically strong and stable RF structure is desirable. Guided by this consideration, multi-fold symmetry element-loaded SRF structures (MFSEL), cylindrical tanks with multiple (n>=3) rod-shaped radial elements, are being explored. The top goalmore » of its optimization is to improve mechanical stability. A natural consequence of this structure is a lowered ratio of the peak surface electromagnetic field to the acceleration gradient as compared to the traditional spoke cavity. A disadvantage of this new structure is an increased size for a fixed resonant frequency and optimal beta. This paper describes the optimization of the electro-magnetic (EM) design and preliminary mechanical analysis for such structures.« less

Design and simulation of a novel E-mode GaN MIS-HEMT based on a cascode connection for suppression of electric field under gate and improvement of reliability

NASA Astrophysics Data System (ADS)

Li, Weiyi; Zhang, Zhili; Fu, Kai; Yu, Guohao; Zhang, Xiaodong; Sun, Shichuang; Song, Liang; Hao, Ronghui; Fan, Yaming; Cai, Yong; Zhang, Baoshun

2017-07-01

We proposed a novel AlGaN/GaN enhancement-mode (E-mode) high electron mobility transistor (HEMT) with a dual-gate structure and carried out the detailed numerical simulation of device operation using Silvaco Atlas. The dual-gate device is based on a cascode connection of an E-mode and a D-mode gate. The simulation results show that electric field under the gate is decreased by more than 70% compared to that of the conventional E-mode MIS-HEMTs (from 2.83 MV/cm decreased to 0.83 MV/cm). Thus, with the discussion of ionized trap density, the proposed dual-gate structure can highly improve electric field-related reliability, such as, threshold voltage stability. In addition, compared with HEMT with field plate structure, the proposed structure exhibits a simplified fabrication process and a more effective suppression of high electric field. Project supported by the Key Technologies Support Program of Jiangsu Province (No. BE2013002-2) and the National Key Scientific Instrument and Equipment Development Projects of China (No. 2013YQ470767).

Microgravity

NASA Image and Video Library

1992-06-25

Zeolites are crystalline aluminosilicates that have complex framework structures. However, there are several features of zeolite crystals that make unequivocal structure determinations difficult. The acquisition of reliable structural information on zeolites is greatly facilitated by the availability of high-quality specimens. For structure determinations by conventional diffraction techniques, large single-crystal specimens are essential. Alternatively, structural determinations by powder profile refinement methods relax the constraints on crystal size, but still require materials with a high degree of crystalline perfection. Studies conducted at CAMMP (Center for Advanced Microgravity Materials Processing) have demonstrated that microgravity processing can produce larger crystal sizes and fewer structural defects relative to terrestrial crystal growth. Principal Investigator: Dr. Albert Sacco

Zeolites

NASA Technical Reports Server (NTRS)

1992-01-01

Zeolites are crystalline aluminosilicates that have complex framework structures. However, there are several features of zeolite crystals that make unequivocal structure determinations difficult. The acquisition of reliable structural information on zeolites is greatly facilitated by the availability of high-quality specimens. For structure determinations by conventional diffraction techniques, large single-crystal specimens are essential. Alternatively, structural determinations by powder profile refinement methods relax the constraints on crystal size, but still require materials with a high degree of crystalline perfection. Studies conducted at CAMMP (Center for Advanced Microgravity Materials Processing) have demonstrated that microgravity processing can produce larger crystal sizes and fewer structural defects relative to terrestrial crystal growth. Principal Investigator: Dr. Albert Sacco

Cross-cultural adaptation and psychometric properties of the Korean Scale for Internet Addiction (K-Scale) in Japanese high school students.

PubMed

Mak, Kwok-Kei; Nam, JeeEun Karin; Kim, Dongil; Aum, Narae; Choi, Jung-Seok; Cheng, Cecilia; Ko, Huei-Chen; Watanabe, Hiroko

2017-03-01

The Korean Scale for Internet Addiction (K-Scale) was developed in Korea for assessing addictive internet behaviors. This study aims to adopt K-Scale and examine its psychometric properties in Japanese adolescents. In 2014, 589 (36.0% boys) high school students (Grade 10-12) from Japan completed a survey, including items of Japanese versions of K-Scale and Smartphone Scale for Smartphone Addiction (S-Scale). Model fit indices of the original four-factor structure, three-factor structure obtained from exploratory factor analysis, and improved two-factor structure of K-Scale were computed using confirmatory factor analysis, with internal reliability of included items reported. The convergent validity of K-Scale was tested against self-rated internet addiction, and S-Scale using multiple regression models. The results showed that a second-order two-factor 13-item structure was the most parsimonious model (NFI=0.919, NNFI=0.935, CFI=0.949, and RMSEA=0.05) with good internal reliability (Cronbach's alpha=0.87). The two factors revealed were "Disturbance of Adaptation and Life Orientation" and "Withdrawal and Tolerance". Moreover, the correlation between internet user classifications defined by K-Scale and self-rating was significant. K-Scale total score was significantly and positively associated with S-Scale total (adjusted R 2 =0.440) and subscale scores (adjusted R 2 =0.439). In conclusion, K-Scale is a valid and reliable assessment scale of internet addiction for Japanese high school students after modifications. Copyright © 2017. Published by Elsevier B.V.

A digital photographic measurement method for quantifying foot posture: validity, reliability, and descriptive data.

PubMed

Cobb, Stephen C; James, C Roger; Hjertstedt, Matthew; Kruk, James

2011-01-01

Although abnormal foot posture long has been associated with lower extremity injury risk, the evidence is equivocal. Poor intertester reliability of traditional foot measures might contribute to the inconsistency. To investigate the validity and reliability of a digital photographic measurement method (DPMM) technology, the reliability of DPMM-quantified foot measures, and the concurrent validity of the DPMM with clinical-measurement methods (CMMs) and to report descriptive data for DPMM measures with moderate to high intratester and intertester reliability. Descriptive laboratory study. Biomechanics research laboratory. A total of 159 people participated in 3 groups. Twenty-eight people (11 men, 17 women; age  =  25 ± 5 years, height  =  1.71 ± 0.10 m, mass  =  77.6 ± 17.3 kg) were recruited for investigation of intratester and intertester reliability of the DPMM technology; 20 (10 men, 10 women; age  =  24 ± 2 years, height  =  1.71 ± 0.09 m, mass  =  76 ± 16 kg) for investigation of DPMM and CMM reliability and concurrent validity; and 111 (42 men, 69 women; age  =  22.8 ± 4.7 years, height  =  168.5 ± 10.4 cm, mass  =  69.8 ± 13.3 kg) for development of a descriptive data set of the DPMM foot measurements with moderate to high intratester and intertester reliabilities. The dimensions of 10 model rectangles and the 28 participants' feet were measured, and DPMM foot posture was measured in the 111 participants. Two clinicians assessed the DPMM and CMM foot measures of the 20 participants. Validity and reliability were evaluated using mean absolute and percentage errors and intraclass correlation coefficients. Descriptive data were computed from the DPMM foot posture measures. The DPMM technology intratester and intertester reliability intraclass correlation coefficients were 1.0 for each tester and variable. Mean absolute errors were equal to or less than 0.2 mm for the bottom and right-side variables and 0.1° for the calculated angle variable. Mean percentage errors between the DPMM and criterion reference values were equal to or less than 0.4%. Intratester and intertester reliabilities of DPMM-computed structural measures of arch and navicular indices were moderate to high (>0.78), and concurrent validity was moderate to strong. The DPMM is a valid and reliable clinical and research tool for quantifying foot structure. The DPMM and the descriptive data might be used to define groups in future studies in which the relationship between foot posture and function or injury risk is investigated.

Repeated-measure validation of craniofacial metrics from three-dimensional surface scans: application to medical genetics

NASA Astrophysics Data System (ADS)

Lauer, Eric A.; Corner, Brian D.; Li, Peng; Beecher, Robert M.; Deutsch, Curtis

2002-03-01

Traditionally, medical geneticists have employed visual inspection (anthroposcopy) to clinically evaluate dysmorphology. In the last 20 years, there has been an increasing trend towards quantitative assessment to render diagnosis of anomalies more objective and reliable. These methods have focused on direct anthropometry, using a combination of classical physical anthropology tools and new instruments tailor-made to describe craniofacial morphometry. These methods are painstaking and require that the patient remain still for extended periods of time. Most recently, semiautomated techniques (e.g., structured light scanning) have been developed to capture the geometry of the face in a matter of seconds. In this paper, we establish that direct anthropometry and structured light scanning yield reliable measurements, with remarkably high levels of inter-rater and intra-rater reliability, as well as validity (contrasting the two methods).

Factor Structure, Reliability and Criterion Validity of the Autism-Spectrum Quotient (AQ): A Study in Dutch Population and Patient Groups

PubMed Central

Bartels, Meike; Cath, Danielle C.; Boomsma, Dorret I.

2008-01-01

The factor structure of the Dutch translation of the Autism-Spectrum Quotient (AQ; a continuous, quantitative measure of autistic traits) was evaluated with confirmatory factor analyses in a large general population and student sample. The criterion validity of the AQ was examined in three matched patient groups (autism spectrum conditions (ASC), social anxiety disorder, and obsessive–compulsive disorder). A two factor model, consisting of a “Social interaction” factor and “Attention to detail” factor could be identified. The internal consistency and test–retest reliability of the AQ were satisfactory. High total AQ and factor scores were specific to ASC patients. Men scored higher than women and science students higher than non-science students. The Dutch translation of the AQ is a reliable instrument to assess autism spectrum conditions. PMID:18302013

The Child and Adolescent Services Assessment: Interrater Reliability and Predictors of Rater Disagreement.

PubMed

Schwartz, Karen T G; Bowling, Amanda A; Dickerson, John F; Lynch, Frances L; Brent, David A; Porta, Giovanna; Iyengar, Satish; Weersing, V Robin

2018-05-24

The current study evaluated the interrater reliability of the Child and Adolescent Services Assessment (CASA), a widely used structured interview measuring pediatric mental health service use. Interviews (N = 72) were randomly selected from a pediatric effectiveness trial, and audio was coded by an independent rater. Regressions were employed to identify predictors of rater disagreement. Interrater reliability was high for items (> 94%) and summary metrics (ICC > .79) across service sectors. Predictors of disagreement varied by domain; significant predictors indexed higher clinical severity or social disadvantage. Results support the CASA as a reliable and robust assessment of pediatric service use, but administrators should be alert when assessing vulnerable populations.

Critical Assessment of the Foundations of Power Transmission and Distribution Reliability Metrics and Standards.

PubMed

Nateghi, Roshanak; Guikema, Seth D; Wu, Yue Grace; Bruss, C Bayan

2016-01-01

The U.S. federal government regulates the reliability of bulk power systems, while the reliability of power distribution systems is regulated at a state level. In this article, we review the history of regulating electric service reliability and study the existing reliability metrics, indices, and standards for power transmission and distribution networks. We assess the foundations of the reliability standards and metrics, discuss how they are applied to outages caused by large exogenous disturbances such as natural disasters, and investigate whether the standards adequately internalize the impacts of these events. Our reflections shed light on how existing standards conceptualize reliability, question the basis for treating large-scale hazard-induced outages differently from normal daily outages, and discuss whether this conceptualization maps well onto customer expectations. We show that the risk indices for transmission systems used in regulating power system reliability do not adequately capture the risks that transmission systems are prone to, particularly when it comes to low-probability high-impact events. We also point out several shortcomings associated with the way in which regulators require utilities to calculate and report distribution system reliability indices. We offer several recommendations for improving the conceptualization of reliability metrics and standards. We conclude that while the approaches taken in reliability standards have made considerable advances in enhancing the reliability of power systems and may be logical from a utility perspective during normal operation, existing standards do not provide a sufficient incentive structure for the utilities to adequately ensure high levels of reliability for end-users, particularly during large-scale events. © 2015 Society for Risk Analysis.

[Inter-rater reliability and construct validity of the OPD-CA axis structure: first study results regarding the integration of OPD-CA into clinical practice].

PubMed

Cropp, Carola; Salzer, Simone; Häusser, Leonard F; Streeck-Fischer, Annette

2013-01-01

The axis structure of the Operationalized Psychodynamic Diagnostics in childhood and adolescence (OPD-CA) has proven to be a reliable and valid diagnostic tool under research conditions. However, corresponding data regarding the integration of OPD-CA axis structure into clinical practice is still lacking. Hence, this aspect was examined as part of a randomized controlled clinical trial realized at Asklepios Fachklinikum Tiefenbrunn. Here, the OPD-CA axis structure has been applied to assess the structural level of 42 adolescent patients (15-19 years). In contrast to previous studies, the assessment was not carried out by independent raters using a videotaped OPD-CA interview, but the rating was part of clinical routine procedures. Also under these conditions, inter-rater reliability was high, in particular regarding the four subscales of the OPD-CA axis structure. With respect to construct validity, the results of our study supported a two-factor solution, which is in accordance with the findings of two previous works. One factor corresponded to the dimension "self-regulation" while the other factor included both the dimension "self-perception and object perception" as well as the dimension "communication skills". Implications of the findings for research and practice are discussed.

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

Dondero, Rachel Elizabeth

The increased use of Field Programmable Gate Arrays (FPGAs) in critical systems brings new challenges in securing the diversely programmable fabric from cyber-attacks. FPGAs are an inexpensive, efficient, and flexible alternative to Application Specific Integrated Circuits (ASICs), which are becoming increasingly expensive and impractical for low volume manufacturing as technology nodes continue to shrink. Unfortunately, FPGAs are not designed for high security applications, and their high-flexibility lends itself to low security and vulnerability to malicious attacks. Similar to securing an ASIC’s functionality, FPGA programmers can exploit the inherent randomness introduced into hardware structures during fabrication for security applications. Physically Unclonablemore » Functions (PUFs) are one such solution that uses the die specific variability in hardware fabrication for both secret key generation and verification. PUFs strive to be random, unique, and reliable. Throughout recent years many PUF structures have been presented to try and maximize these three design constraints, reliability being the most difficult of the three to achieve. This thesis presents a new PUF structure that combines two elementary PUF concepts (a bi-stable SRAM PUF and a delay-based arbiter PUF) to create a PUF with increased reliability, while maintaining both random and unique qualities. Properties of the new PUF will be discussed as well as the various design modifications that can be made to tweak the desired performance and overhead.« less

NASA Office of Aeronautical and Space Technology Summer Workshop. Volume 6: Structures and dynamics panel

NASA Technical Reports Server (NTRS)

1975-01-01

Structural requirements for future space missions were defined in relation to technology needs and payloads. Specific areas examined include: large area space structures (antennas, solar array structures, and platforms); a long, slender structure or boom used to support large objects from the shuttle or hold two bodies apart in space; and advanced composite structures for cost effective weight reductions. Other topics discussed include: minimum gage concepts, high temperature components, load and response determination and control, and reliability and life prediction.

System reliability approaches for advanced propulsion system structures

NASA Technical Reports Server (NTRS)

Cruse, T. A.; Mahadevan, S.

1991-01-01

This paper identifies significant issues that pertain to the estimation and use of system reliability in the design of advanced propulsion system structures. Linkages between the reliabilities of individual components and their effect on system design issues such as performance, cost, availability, and certification are examined. The need for system reliability computation to address the continuum nature of propulsion system structures and synergistic progressive damage modes has been highlighted. Available system reliability models are observed to apply only to discrete systems. Therefore a sequential structural reanalysis procedure is formulated to rigorously compute the conditional dependencies between various failure modes. The method is developed in a manner that supports both top-down and bottom-up analyses in system reliability.

Understanding the Reliability of Solder Joints Used in Advanced Structural and Electronics Applications: Part 2 - Reliability Performance.

DOE PAGES

Vianco, Paul T.

2017-03-01

Whether structural or electronic, all solder joints must provide the necessary level of reliability for the application. The Part 1 report examined the effects of filler metal properties and the soldering process on joint reliability. Filler metal solderability and mechanical properties, as well as the extents of base material dissolution and interface reaction that occur during the soldering process, were shown to affect reliability performance. The continuation of this discussion is presented in this Part 2 report, which highlights those factors that directly affect solder joint reliability. There is the growth of an intermetallic compound (IMC) reaction layer at themore » solder/base material interface by means of solid-state diffusion processes. In terms of mechanical response by the solder joint, fatigue remains as the foremost concern for long-term performance. Thermal mechanical fatigue (TMF), a form of low-cycle fatigue (LCF), occurs when temperature cycling is combined with mismatched values of the coefficient of thermal expansion (CTE) between materials comprising the solder joint “system.” Vibration environments give rise to high-cycle fatigue (HCF) degradation. Although accelerated aging studies provide valuable empirical data, too many variants of filler metals, base materials, joint geometries, and service environments are forcing design engineers to embrace computational modeling to predict the long-term reliability of solder joints.« less

On the Factorial Structure of the SAT and Implications for Next-Generation College Readiness Assessments

ERIC Educational Resources Information Center

Wiley, Edward W.; Shavelson, Richard J.; Kurpius, Amy A.

2014-01-01

The name "SAT" has become synonymous with college admissions testing; it has been dubbed "the gold standard." Numerous studies on its reliability and predictive validity show that the SAT predicts college performance beyond high school grade point average. Surprisingly, studies of the factorial structure of the current version…

Rapid and reliable protein structure determination via chemical shift threading.

PubMed

Hafsa, Noor E; Berjanskii, Mark V; Arndt, David; Wishart, David S

2018-01-01

Protein structure determination using nuclear magnetic resonance (NMR) spectroscopy can be both time-consuming and labor intensive. Here we demonstrate how chemical shift threading can permit rapid, robust, and accurate protein structure determination using only chemical shift data. Threading is a relatively old bioinformatics technique that uses a combination of sequence information and predicted (or experimentally acquired) low-resolution structural data to generate high-resolution 3D protein structures. The key motivations behind using NMR chemical shifts for protein threading lie in the fact that they are easy to measure, they are available prior to 3D structure determination, and they contain vital structural information. The method we have developed uses not only sequence and chemical shift similarity but also chemical shift-derived secondary structure, shift-derived super-secondary structure, and shift-derived accessible surface area to generate a high quality protein structure regardless of the sequence similarity (or lack thereof) to a known structure already in the PDB. The method (called E-Thrifty) was found to be very fast (often < 10 min/structure) and to significantly outperform other shift-based or threading-based structure determination methods (in terms of top template model accuracy)-with an average TM-score performance of 0.68 (vs. 0.50-0.62 for other methods). Coupled with recent developments in chemical shift refinement, these results suggest that protein structure determination, using only NMR chemical shifts, is becoming increasingly practical and reliable. E-Thrifty is available as a web server at http://ethrifty.ca .

Evaluation of Behaviours of Laminated Glass

NASA Astrophysics Data System (ADS)

Sable, L.; Japins, G.; Kalnins, K.

2015-11-01

Visual appearance of building facades and other load bearing structures, which now are part of modern architecture, is the reason why it is important to investigate in more detail the reliability of laminated glass for civil structures. Laminated glass in particular has become one of the trendy materials, for example Apple© stores have both load carrying capacity and transparent appearance. Glass has high mechanical strength and relatively medium density, however, the risk of sudden brittle failure like concrete or other ceramics determine relatively high conservatism in design practice of glass structures. This should be changed as consumer requirements evolve calling for a safe and reliable design methodology and corresponding building standards. A design methodology for glass and glass laminates should be urgently developed and included as a chapter in Eurocode. This paper presents initial experimental investigation of behaviour of simple glass sheets and laminated glass samples in 4-point bending test. The aim of the current research is to investigate laminated glass characteristic values and to verify the obtained experimental results with finite element method for glass and EVA material in line with future European Structural Design of Glass Components code.

Developing an assessment of fire-setting to guide treatment in secure settings: the St Andrew's Fire and Arson Risk Instrument (SAFARI).

PubMed

Long, Clive G; Banyard, Ellen; Fulton, Barbara; Hollin, Clive R

2014-09-01

Arson and fire-setting are highly prevalent among patients in secure psychiatric settings but there is an absence of valid and reliable assessment instruments and no evidence of a significant approach to intervention. To develop a semi-structured interview assessment specifically for fire-setting to augment structured assessments of risk and need. The extant literature was used to frame interview questions relating to the antecedents, behaviour and consequences necessary to formulate a functional analysis. Questions also covered readiness to change, fire-setting self-efficacy, the probability of future fire-setting, barriers to change, and understanding of fire-setting behaviour. The assessment concludes with indications for assessment and a treatment action plan. The inventory was piloted with a sample of women in secure care and was assessed for comprehensibility, reliability and validity. Staff rated the St Andrews Fire and Risk Instrument (SAFARI) as acceptable to patients and easy to administer. SAFARI was found to be comprehensible by over 95% of the general population, to have good acceptance, high internal reliability, substantial test-retest reliability and validity. SAFARI helps to provide a clear explanation of fire-setting in terms of the complex interplay of antecedents and consequences and facilitates the design of an individually tailored treatment programme in sympathy with a cognitive-behavioural approach. Further studies are needed to verify the reliability and validity of SAFARI with male populations and across settings.

[The Basel Screening Instrument for Psychosis (BSIP): development, structure, reliability and validity].

PubMed

Riecher-Rössler, A; Aston, J; Ventura, J; Merlo, M; Borgwardt, S; Gschwandtner, U; Stieglitz, R-D

2008-04-01

Early detection of psychosis is of growing clinical importance. So far there is, however, no screening instrument for detecting individuals with beginning psychosis in the atypical early stages of the disease with sufficient validity. We have therefore developed the Basel Screening Instrument for Psychosis (BSIP) and tested its feasibility, interrater-reliability and validity. Aim of this paper is to describe the development and structure of the instrument, as well as to report the results of the studies on reliability and validity. The instrument was developed based on a comprehensive search of literature on the most important risk factors and early signs of schizophrenic psychoses. The interraterreliability study was conducted on 24 psychiatric cases. Validity was tested based on 206 individuals referred to our early detection clinic from 3/1/2000 until 2/28/2003. We identified seven categories of relevance for early detection of psychosis and used them to construct a semistructured interview. Interrater-reliability for high risk individuals was high (Kappa .87). Predictive validity was comparable to other, more comprehensive instruments: 16 (32 %) of 50 individuals classified as being at risk for psychosis by the BSIP have in fact developed frank psychosis within an follow-up period of two to five years. The BSIP is the first screening instrument for the early detection of psychosis which has been validated based on transition to psychosis. The BSIP is easy to use by experienced psychiatrists and has a very good interrater-reliability and predictive validity.

Assessment of Semi-Structured Clinical Interview for Mobile Phone Addiction Disorder

PubMed Central

Alavi, Seyyed Salman; Jannatifard, Fereshteh; Mohammadi Kalhori, Soroush; Sepahbodi, Ghazal; BabaReisi, Mohammad; Sajedi, Sahar; Farshchi, Mojtaba; KhodaKarami, Rasul; Hatami Kasvaee, Vahid

2016-01-01

Objective: The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) classified mobile phone addiction disorder under “impulse control disorder not elsewhere classified”. This study surveyed the diagnostic criteria of DSM-IV-TR for the diagnosis of mobile phone addiction in correspondence with Iranian society and culture. Method: Two hundred fifty students of Tehran universities were entered into this descriptive-analytical and cross-sectional study. Quota sampling method was used. At first, semi- structured clinical interview (based on DSM-IV-TR) was performed for all the cases, and another specialist reevaluated the interviews. Data were analyzed using content validity, inter-scorer reliability (Kappa coefficient) and test-retest via SPSS18 software. Results: The content validity of the semi- structured clinical interview matched the DSM–IV-TR criteria for behavioral addiction. Moreover, their content was appropriate, and two items, including “SMS pathological use” and “High monthly cost of using the mobile phone” were added to promote its validity. Internal reliability (Kappa) and test–retest reliability were 0.55 and r = 0.4 (p<0. 01) respectively. Conclusion: The results of this study revealed that semi- structured diagnostic criteria of DSM-IV-TR are valid and reliable for diagnosing mobile phone addiction, and this instrument is an effective tool to diagnose this disorder. PMID:27437008

Extensive validation of the pain disability index in 3 groups of patients with musculoskeletal pain.

PubMed

Soer, Remko; Köke, Albère J A; Vroomen, Patrick C A J; Stegeman, Patrick; Smeets, Rob J E M; Coppes, Maarten H; Reneman, Michiel F

2013-04-20

A cross-sectional study design was performed. To validate the pain disability index (PDI) extensively in 3 groups of patients with musculoskeletal pain. The PDI is a widely used and studied instrument for disability related to various pain syndromes, although there is conflicting evidence concerning factor structure, test-retest reliability, and missing items. Additionally, an official translation of the Dutch language version has never been performed. For reliability, internal consistency, factor structure, test-retest reliability and measurement error were calculated. Validity was tested with hypothesized correlations with pain intensity, kinesiophobia, Rand-36 subscales, Depression, Roland-Morris Disability Questionnaire, Quality of Life, and Work Status. Structural validity was tested with independent backward translation and approval from the original authors. One hundred seventy-eight patients with acute back pain, 425 patients with chronic low back pain and 365 with widespread pain were included. Internal consistency of the PDI was good. One factor was identified with factor analyses. Test-retest reliability was good for the PDI (intraclass correlation coefficient, 0.76). Standard error of measurement was 6.5 points and smallest detectable change was 17.9 points. Little correlations between the PDI were observed with kinesiophobia and depression, fair correlations with pain intensity, work status, and vitality and moderate correlations with the Rand-36 subscales and the Roland-Morris Disability Questionnaire. The PDI-Dutch language version is internally consistent as a 1-factor structure, and test-retest reliable. Missing items seem high in sexual and professional items. Using the PDI as a 2-factor questionnaire has no additional value and is unreliable.

Control of Ga-oxide interlayer growth and Ga diffusion in SiO2/GaN stacks for high-quality GaN-based metal-oxide-semiconductor devices with improved gate dielectric reliability

NASA Astrophysics Data System (ADS)

Yamada, Takahiro; Watanabe, Kenta; Nozaki, Mikito; Yamada, Hisashi; Takahashi, Tokio; Shimizu, Mitsuaki; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2018-01-01

A simple and feasible method for fabricating high-quality and highly reliable GaN-based metal-oxide-semiconductor (MOS) devices was developed. The direct chemical vapor deposition of SiO2 films on GaN substrates forming Ga-oxide interlayers was carried out to fabricate SiO2/GaO x /GaN stacked structures. Although well-behaved hysteresis-free GaN-MOS capacitors with extremely low interface state densities below 1010 cm-2 eV-1 were obtained by postdeposition annealing, Ga diffusion into overlying SiO2 layers severely degraded the dielectric breakdown characteristics. However, this problem was found to be solved by rapid thermal processing, leading to the superior performance of the GaN-MOS devices in terms of interface quality, insulating property, and gate dielectric reliability.

Single-anchor support and supercritical CO2 drying enable high-precision microfabrication of three-dimensional structures.

PubMed

Maruo, Shoji; Hasegawa, Takuya; Yoshimura, Naoki

2009-11-09

In high-precision two-photon microfabrication of three-dimensional (3-D) polymeric microstructures, supercritical CO(2) drying was employed to reduce surface tension, which tends to cause the collapse of micro/nano structures. Use of supercritical drying allowed high-aspect ratio microstructures, such as micropillars and cantilevers, to be fabricated. We also propose a single-anchor supporting method to eliminate non-uniform shrinkage of polymeric structures otherwise caused by attachment to the substrate. Use of this method permitted frame models such as lattices to be produced without harmful distortion. The combination of supercritical CO(2) drying and the single-anchor supporting method offers reliable high-precision microfabrication of sophisticated, fragile 3-D micro/nano structures.

Recent advances in computational structural reliability analysis methods

NASA Astrophysics Data System (ADS)

Thacker, Ben H.; Wu, Y.-T.; Millwater, Harry R.; Torng, Tony Y.; Riha, David S.

1993-10-01

The goal of structural reliability analysis is to determine the probability that the structure will adequately perform its intended function when operating under the given environmental conditions. Thus, the notion of reliability admits the possibility of failure. Given the fact that many different modes of failure are usually possible, achievement of this goal is a formidable task, especially for large, complex structural systems. The traditional (deterministic) design methodology attempts to assure reliability by the application of safety factors and conservative assumptions. However, the safety factor approach lacks a quantitative basis in that the level of reliability is never known and usually results in overly conservative designs because of compounding conservatisms. Furthermore, problem parameters that control the reliability are not identified, nor their importance evaluated. A summary of recent advances in computational structural reliability assessment is presented. A significant level of activity in the research and development community was seen recently, much of which was directed towards the prediction of failure probabilities for single mode failures. The focus is to present some early results and demonstrations of advanced reliability methods applied to structural system problems. This includes structures that can fail as a result of multiple component failures (e.g., a redundant truss), or structural components that may fail due to multiple interacting failure modes (e.g., excessive deflection, resonate vibration, or creep rupture). From these results, some observations and recommendations are made with regard to future research needs.

Recent advances in computational structural reliability analysis methods

NASA Technical Reports Server (NTRS)

Thacker, Ben H.; Wu, Y.-T.; Millwater, Harry R.; Torng, Tony Y.; Riha, David S.

1993-01-01

The goal of structural reliability analysis is to determine the probability that the structure will adequately perform its intended function when operating under the given environmental conditions. Thus, the notion of reliability admits the possibility of failure. Given the fact that many different modes of failure are usually possible, achievement of this goal is a formidable task, especially for large, complex structural systems. The traditional (deterministic) design methodology attempts to assure reliability by the application of safety factors and conservative assumptions. However, the safety factor approach lacks a quantitative basis in that the level of reliability is never known and usually results in overly conservative designs because of compounding conservatisms. Furthermore, problem parameters that control the reliability are not identified, nor their importance evaluated. A summary of recent advances in computational structural reliability assessment is presented. A significant level of activity in the research and development community was seen recently, much of which was directed towards the prediction of failure probabilities for single mode failures. The focus is to present some early results and demonstrations of advanced reliability methods applied to structural system problems. This includes structures that can fail as a result of multiple component failures (e.g., a redundant truss), or structural components that may fail due to multiple interacting failure modes (e.g., excessive deflection, resonate vibration, or creep rupture). From these results, some observations and recommendations are made with regard to future research needs.

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.

Optimizing the Reliability and Performance of Service Composition Applications with Fault Tolerance in Wireless Sensor Networks

PubMed Central

Wu, Zhao; Xiong, Naixue; Huang, Yannong; Xu, Degang; Hu, Chunyang

2015-01-01

The services composition technology provides flexible methods for building service composition applications (SCAs) in wireless sensor networks (WSNs). The high reliability and high performance of SCAs help services composition technology promote the practical application of WSNs. The optimization methods for reliability and performance used for traditional software systems are mostly based on the instantiations of software components, which are inapplicable and inefficient in the ever-changing SCAs in WSNs. In this paper, we consider the SCAs with fault tolerance in WSNs. Based on a Universal Generating Function (UGF) we propose a reliability and performance model of SCAs in WSNs, which generalizes a redundancy optimization problem to a multi-state system. Based on this model, an efficient optimization algorithm for reliability and performance of SCAs in WSNs is developed based on a Genetic Algorithm (GA) to find the optimal structure of SCAs with fault-tolerance in WSNs. In order to examine the feasibility of our algorithm, we have evaluated the performance. Furthermore, the interrelationships between the reliability, performance and cost are investigated. In addition, a distinct approach to determine the most suitable parameters in the suggested algorithm is proposed. PMID:26561818

Magnetic resonance imaging can accurately assess the long-term progression of knee structural changes in experimental dog osteoarthritis.

PubMed

Boileau, C; Martel-Pelletier, J; Abram, F; Raynauld, J-P; Troncy, E; D'Anjou, M-A; Moreau, M; Pelletier, J-P

2008-07-01

Osteoarthritis (OA) structural changes take place over decades in humans. MRI can provide precise and reliable information on the joint structure and changes over time. In this study, we investigated the reliability of quantitative MRI in assessing knee OA structural changes in the experimental anterior cruciate ligament (ACL) dog model of OA. OA was surgically induced by transection of the ACL of the right knee in five dogs. High resolution three dimensional MRI using a 1.5 T magnet was performed at baseline, 4, 8 and 26 weeks post surgery. Cartilage volume/thickness, cartilage defects, trochlear osteophyte formation and subchondral bone lesion (hypersignal) were assessed on MRI images. Animals were killed 26 weeks post surgery and macroscopic evaluation was performed. There was a progressive and significant increase over time in the loss of knee cartilage volume, the cartilage defect and subchondral bone hypersignal. The trochlear osteophyte size also progressed over time. The greatest cartilage loss at 26 weeks was found on the tibial plateaus and in the medial compartment. There was a highly significant correlation between total knee cartilage volume loss or defect and subchondral bone hypersignal, and also a good correlation between the macroscopic and the MRI findings. This study demonstrated that MRI is a useful technology to provide a non-invasive and reliable assessment of the joint structural changes during the development of OA in the ACL dog model. The combination of this OA model with MRI evaluation provides a promising tool for the evaluation of new disease-modifying osteoarthritis drugs (DMOADs).

Reliability study of refractory gate gallium arsenide MESFETS

NASA Technical Reports Server (NTRS)

Yin, J. C. W.; Portnoy, W. M.

1981-01-01

Refractory gate MESFET's were fabricated as an alternative to aluminum gate devices, which have been found to be unreliable as RF power amplifiers. In order to determine the reliability of the new structures, statistics of failure and information about mechanisms of failure in refractory gate MESFET's are given. Test transistors were stressed under conditions of high temperature and forward gate current to enhance failure. Results of work at 150 C and 275 C are reported.

Reliability study of refractory gate gallium arsenide MESFETS

NASA Astrophysics Data System (ADS)

Yin, J. C. W.; Portnoy, W. M.

Refractory gate MESFET's were fabricated as an alternative to aluminum gate devices, which have been found to be unreliable as RF power amplifiers. In order to determine the reliability of the new structures, statistics of failure and information about mechanisms of failure in refractory gate MESFET's are given. Test transistors were stressed under conditions of high temperature and forward gate current to enhance failure. Results of work at 150 C and 275 C are reported.

Feasibility model of a high reliability five-year tape transport, Volume 1. [development, performance, and test results

NASA Technical Reports Server (NTRS)

Eshleman, R. L.; Meyers, A. P.; Davidson, W. A.; Gortowski, R. C.; Anderson, M. E.

1973-01-01

The development, performance, and test results for the spaceborne magnetic tape transport are discussed. An analytical model of the tape transport was used to optimize its conceptual design. Each of the subsystems was subjected to reliability analyses which included structural integrity, maintenance of system performance within acceptable bounds, and avoidance of fatigue failure. These subsystems were also compared with each other in order to evaluate reliability characteristics. The transport uses no mechanical couplings. Four drive motors, one for each reel and one for each of two capstans, are used in a differential mode. There are two hybrid, spherical, cone tapered-crown rollers for tape guidance. Storage of the magnetic tape is provided by a reel assembly which includes the reel, a reel support structure and bearings, dust seals, and a dc drive motor. A summary of transport test results on tape guidance, flutter, and skew is provided.

Strength Analysis and Reliability Evaluation for Speed Reducers

NASA Astrophysics Data System (ADS)

Tsai, Yuo-Tern; Hsu, Yung-Yuan

2017-09-01

This paper studies the structural stresses of differential drive (DD) and harmonic drive (HD) for design improvement of reducers. The designed principles of the two reducers are reported for function comparison. The critical components of the reducers are constructed for performing motion simulation and stress analysis. DD is designed based on differential displacement of the decelerated gear ring as well as HD on a flexible spline. Finite element method (FEM) is used to analyze the structural stresses including the dynamic properties of the reducers. The stresses including kinematic properties of the two reducers are compared to observe the properties of the designs. The analyzed results are applied to identify the allowable loads of the reducers in use. The reliabilities of the reducers in different loads are further calculated according to the variation of stress. The studied results are useful on engineering analysis and reliability evaluation for designing a speed reducer with high ratios.

Reliability and Validity of the Chinese (Mandarin) Tinnitus Handicap Inventory

PubMed Central

Meng, Zhaoli; Zheng, Yun; Wang, Kai; Kong, Xiudan; Tao, Yong; Xu, Ke; Liu, Guanjian

2012-01-01

Objectives The Tinnitus Handicap Inventory (THI) is a commonly used self-reporting tinnitus questionnaire. We undertook this study to determine the reliability and validity of the Chinese-Mandarin version of the Tinnitus Handicap Inventory (THI-CM) for measuring tinnitus-related handicaps. Methods We tested the test-retest reliability, internal reliability, and construct validity of the THI-CM. Two-hundred patients seeking treatment for primary or secondary tinnitus in Southwest China were asked to complete THI-CM prior to clinical evaluation. Patients were evaluated by a clinician using standard methods, and 40 patients were asked to complete THI-CM a second time 14±3 days after the initial interview. Results The test-retest reliability of THI-CM was high (Pearson correlation, 0.98), as was the internal reliability (Cronbach's α, 0.93). Factor analysis indicated that THI-CM has a unifactorial structure. Conclusion The THI-CM version is reliable. The total score in THI-CM can be used to measure tinnitus-related handicaps in Mandarin-speaking populations. PMID:22468196

Reliability Analysis of Sealing Structure of Electromechanical System Based on Kriging Model

NASA Astrophysics Data System (ADS)

Zhang, F.; Wang, Y. M.; Chen, R. W.; Deng, W. W.; Gao, Y.

2018-05-01

The sealing performance of aircraft electromechanical system has a great influence on flight safety, and the reliability of its typical seal structure is analyzed by researcher. In this paper, we regard reciprocating seal structure as a research object to study structural reliability. Having been based on the finite element numerical simulation method, the contact stress between the rubber sealing ring and the cylinder wall is calculated, and the relationship between the contact stress and the pressure of the hydraulic medium is built, and the friction force on different working conditions are compared. Through the co-simulation, the adaptive Kriging model obtained by EFF learning mechanism is used to describe the failure probability of the seal ring, so as to evaluate the reliability of the sealing structure. This article proposes a new idea of numerical evaluation for the reliability analysis of sealing structure, and also provides a theoretical basis for the optimal design of sealing structure.

Development and Testing of an Inflatable, Rigidizable Space Structure Experiment

DTIC Science & Technology

2006-03-01

successful, including physical dimension, weight , and cost. Inflatable structures have the potential to achieve greater efficiency in all of these...potential for low cost, high mechanical packaging efficiency, deployment reliability and low weight (13). The term inflatable structure indicates that a...back-up inflation gas a necessity for long term success. This addition can be very costly in terms of volume, weight , and expense due to added or

Development of a Drilling Fluid Drive Downhole Tractor in Oil Field

NASA Astrophysics Data System (ADS)

Fang, Delei; Shang, Jianzhong; Liu, Yiying; Wu, Wei; Luo, Zirong

2018-01-01

This paper proposes a drilling fluid drive downhole tractor, which has the advantages of compact structure, large traction, fast speed and high reliability. The overall mechanical structure of the tractor is introduced, the concrete structures including supporting structure and cushion mechanism are designed. And its all-hydraulic drive continuous propulsion principle is analyzed. Finally the simulation analysis of the tractor operation is carried out to prove that the traction motion scheme is feasible.

Investigation of the Stability of a Two-Span Bridge with the use of a High-Precision Laser Displacement Sensors

NASA Astrophysics Data System (ADS)

Poddaeva, O.; Churin, P.; Fedosova, A.; Truhanov, S.

2018-03-01

Studies of aerodynamics of bridge structures are an actual problem. Such attention is paid to the study of wind influence on bridge structures not at all by chance; a large number of cases of loss of stability of such structures are known under the influence of wind up to their complete destruction. The development of non-contact systems of measuring equipment allows solving this problem with a high level of accuracy and reliability. This article presents the results of experimental studies of wind impact on a two-span bridge using specialized measuring system based on high-precision laser displacement sensors.

Possibilities for serial femtosecond crystallography sample delivery at future light sourcesa)

PubMed Central

Chavas, L. M. G.; Gumprecht, L.; Chapman, H. N.

2015-01-01

Serial femtosecond crystallography (SFX) uses X-ray pulses from free-electron laser (FEL) sources that can outrun radiation damage and thereby overcome long-standing limits in the structure determination of macromolecular crystals. Intense X-ray FEL pulses of sufficiently short duration allow the collection of damage-free data at room temperature and give the opportunity to study irreversible time-resolved events. SFX may open the way to determine the structure of biological molecules that fail to crystallize readily into large well-diffracting crystals. Taking advantage of FELs with high pulse repetition rates could lead to short measurement times of just minutes. Automated delivery of sample suspensions for SFX experiments could potentially give rise to a much higher rate of obtaining complete measurements than at today's third generation synchrotron radiation facilities, as no crystal alignment or complex robotic motions are required. This capability will also open up extensive time-resolved structural studies. New challenges arise from the resulting high rate of data collection, and in providing reliable sample delivery. Various developments for fully automated high-throughput SFX experiments are being considered for evaluation, including new implementations for a reliable yet flexible sample environment setup. Here, we review the different methods developed so far that best achieve sample delivery for X-ray FEL experiments and present some considerations towards the goal of high-throughput structure determination with X-ray FELs. PMID:26798808

Recent progress in high performance and reliable n-type transition metal oxide-based thin film transistors

NASA Astrophysics Data System (ADS)

Kwon, Jang Yeon; Kyeong Jeong, Jae

2015-02-01

This review gives an overview of the recent progress in vacuum-based n-type transition metal oxide (TMO) thin film transistors (TFTs). Several excellent review papers regarding metal oxide TFTs in terms of fundamental electron structure, device process and reliability have been published. In particular, the required field-effect mobility of TMO TFTs has been increasing rapidly to meet the demands of the ultra-high-resolution, large panel size and three dimensional visual effects as a megatrend of flat panel displays, such as liquid crystal displays, organic light emitting diodes and flexible displays. In this regard, the effects of the TMO composition on the performance of the resulting oxide TFTs has been reviewed, and classified into binary, ternary and quaternary composition systems. In addition, the new strategic approaches including zinc oxynitride materials, double channel structures, and composite structures have been proposed recently, and were not covered in detail in previous review papers. Special attention is given to the advanced device architecture of TMO TFTs, such as back-channel-etch and self-aligned coplanar structure, which is a key technology because of their advantages including low cost fabrication, high driving speed and unwanted visual artifact-free high quality imaging. The integration process and related issues, such as etching, post treatment, low ohmic contact and Cu interconnection, required for realizing these advanced architectures are also discussed.

Memorial Hermann: high reliability from board to bedside.

PubMed

Shabot, M Michael; Monroe, Douglas; Inurria, Juan; Garbade, Debbi; France, Anne-Claire

2013-06-01

In 2006 the Memorial Hermann Health System (MHHS), which includes 12 hospitals, began applying principles embraced by high reliability organizations (HROs). Three factors support its HRO journey: (1) aligned organizational structure with transparent management systems and compressed reporting processes; (2) Robust Process Improvement (RPI) with high-reliability interventions; and (3) cultural establishment, sustainment, and evolution. The Quality and Safety strategic plan contains three domains, each with a specific set of measures that provide goals for performance: (1) "Clinical Excellence;" (2) "Do No Harm;" and (3) "Saving Lives," as measured by the Serious Safety Event rate. MHHS uses a uniform approach to performance improvement--RPI, which includes Six Sigma, Lean, and change management, to solve difficult safety and quality problems. The 9 acute care hospitals provide multiple opportunities to integrate high-reliability interventions and best practices across MHHS. For example, MHHS partnered with the Joint Commission Center for Transforming Healthcare in its inaugural project to establish reliable hand hygiene behaviors, which improved MHHS's average hand hygiene compliance rate from 44% to 92% currently. Soon after compliance exceeded 85% at all 12 hospitals, the average rate of central line-associated bloodstream and ventilator-associated pneumonias decreased to essentially zero. MHHS's size and diversity require a disciplined approach to performance improvement and systemwide achievement of measurable success. The most significant cultural change at MHHS has been the expectation for 100% compliance with evidence-based quality measures and 0% incidence of patient harm.

A Critique of a Phenomenological Fiber Breakage Model for Stress Rupture of Composite Materials

NASA Technical Reports Server (NTRS)

Reeder, James R.

2010-01-01

Stress rupture is not a critical failure mode for most composite structures, but there are a few applications where it can be critical. One application where stress rupture can be a critical design issue is in Composite Overwrapped Pressure Vessels (COPV's), where the composite material is highly and uniformly loaded for long periods of time and where very high reliability is required. COPV's are normally required to be proof loaded before being put into service to insure strength, but it is feared that the proof load may cause damage that reduces the stress rupture reliability. Recently, a fiber breakage model was proposed specifically to estimate a reduced reliability due to proof loading. The fiber breakage model attempts to model physics believed to occur at the microscopic scale, but validation of the model has not occurred. In this paper, the fiber breakage model is re-derived while highlighting assumptions that were made during the derivation. Some of the assumptions are examined to assess their effect on the final predicted reliability.

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.

[A modified intracellular labelling technique for high-resolution staining of neuron in 500 microm-thickness brain slice].

PubMed

Zhao, Ming-liang; Liu, Guo-long; Sui, Jian-feng; Ruan, Huai-zhen; Xiong, Ying

2007-05-01

To develop simple but reliable intracellular labelling method for high-resolution visualization of the fine structure of single neurons in brain slice with thickness of 500 microm. Biocytin was introduced into neurons in 500 microm-thickness brain slices while blind whole cell recording. Following processed for histochemistry using the avidin-biotin-complex method, stained slices were mounted in glycerol on special glass slides. Labelled cells were digital photomicrographed every 30 microm and reconstructed with Adobe Photoshop software. After histochemistry, limited background staining was produced. The resolution was so high that fine structure, including branching, termination of individual axons and even spines of neurons could be identified in exquisite detail with optic microscope. With the help of software, the neurons of interest could be reconstructed from a stack of photomicrographs. The modified method provides an easy and reliable approach to revealing the detailed morphological properties of single neurons in 500 microm-thickness brain slice. Without requisition of special equipment, it is suited to be broadly applied.

A Digital Photographic Measurement Method for Quantifying Foot Posture: Validity, Reliability, and Descriptive Data

PubMed Central

Cobb, Stephen C.; James, C. Roger; Hjertstedt, Matthew; Kruk, James

2011-01-01

Abstract Context: Although abnormal foot posture long has been associated with lower extremity injury risk, the evidence is equivocal. Poor intertester reliability of traditional foot measures might contribute to the inconsistency. Objectives: To investigate the validity and reliability of a digital photographic measurement method (DPMM) technology, the reliability of DPMM-quantified foot measures, and the concurrent validity of the DPMM with clinical-measurement methods (CMMs) and to report descriptive data for DPMM measures with moderate to high intratester and intertester reliability. Design: Descriptive laboratory study. Setting: Biomechanics research laboratory. Patients or Other Participants: A total of 159 people participated in 3 groups. Twenty-eight people (11 men, 17 women; age  =  25 ± 5 years, height  =  1.71 ± 0.10 m, mass  =  77.6 ± 17.3 kg) were recruited for investigation of intratester and intertester reliability of the DPMM technology; 20 (10 men, 10 women; age  =  24 ± 2 years, height  =  1.71 ± 0.09 m, mass  =  76 ± 16 kg) for investigation of DPMM and CMM reliability and concurrent validity; and 111 (42 men, 69 women; age  =  22.8 ± 4.7 years, height  =  168.5 ± 10.4 cm, mass  =  69.8 ± 13.3 kg) for development of a descriptive data set of the DPMM foot measurements with moderate to high intratester and intertester reliabilities. Intervention(s): The dimensions of 10 model rectangles and the 28 participants' feet were measured, and DPMM foot posture was measured in the 111 participants. Two clinicians assessed the DPMM and CMM foot measures of the 20 participants. Main Outcome Measure(s): Validity and reliability were evaluated using mean absolute and percentage errors and intraclass correlation coefficients. Descriptive data were computed from the DPMM foot posture measures. Results: The DPMM technology intratester and intertester reliability intraclass correlation coefficients were 1.0 for each tester and variable. Mean absolute errors were equal to or less than 0.2 mm for the bottom and right-side variables and 0.1° for the calculated angle variable. Mean percentage errors between the DPMM and criterion reference values were equal to or less than 0.4%. Intratester and intertester reliabilities of DPMM-computed structural measures of arch and navicular indices were moderate to high (>0.78), and concurrent validity was moderate to strong. Conclusions: The DPMM is a valid and reliable clinical and research tool for quantifying foot structure. The DPMM and the descriptive data might be used to define groups in future studies in which the relationship between foot posture and function or injury risk is investigated. PMID:21214347

The scientific data acquisition system of the GAMMA-400 space project

NASA Astrophysics Data System (ADS)

Bobkov, S. G.; Serdin, O. V.; Gorbunov, M. S.; Arkhangelskiy, A. I.; Topchiev, N. P.

2016-02-01

The description of scientific data acquisition system (SDAS) designed by SRISA for the GAMMA-400 space project is presented. We consider the problem of different level electronics unification: the set of reliable fault-tolerant integrated circuits fabricated on Silicon-on-Insulator 0.25 mkm CMOS technology and the high-speed interfaces and reliable modules used in the space instruments. The characteristics of reliable fault-tolerant very large scale integration (VLSI) technology designed by SRISA for the developing of computation systems for space applications are considered. The scalable net structure of SDAS based on Serial RapidIO interface including real-time operating system BAGET is described too.

A lightweight thermal heat switch for redundant cryocooling on satellites

NASA Astrophysics Data System (ADS)

Dietrich, M.; Euler, A.; Thummes, G.

2017-04-01

A previously designed cryogenic thermal heat switch for space applications has been optimized for low mass, high structural stability, and reliability. The heat switch makes use of the large linear thermal expansion coefficient (CTE) of the thermoplastic UHMW-PE for actuation. A structure model, which includes the temperature dependent properties of the actuator, is derived to be able to predict the contact pressure between the switch parts. This pressure was used in a thermal model in order to predict the switch performance under different heat loads and operating temperatures. The two models were used to optimize the mass and stability of the switch. Its reliability was proven by cyclic actuation of the switch and by shaker tests.

Design of Water Temperature Control System Based on Single Chip Microcomputer

NASA Astrophysics Data System (ADS)

Tan, Hanhong; Yan, Qiyan

2017-12-01

In this paper, we mainly introduce a multi-function water temperature controller designed with 51 single-chip microcomputer. This controller has automatic and manual water, set the water temperature, real-time display of water and temperature and alarm function, and has a simple structure, high reliability, low cost. The current water temperature controller on the market basically use bimetal temperature control, temperature control accuracy is low, poor reliability, a single function. With the development of microelectronics technology, monolithic microprocessor function is increasing, the price is low, in all aspects of widely used. In the water temperature controller in the application of single-chip, with a simple design, high reliability, easy to expand the advantages of the function. Is based on the appeal background, so this paper focuses on the temperature controller in the intelligent control of the discussion.

Nuclear surface diffuseness revealed in nucleon-nucleus diffraction

NASA Astrophysics Data System (ADS)

Hatakeyama, S.; Horiuchi, W.; Kohama, A.

2018-05-01

The nuclear surface provides useful information on nuclear radius, nuclear structure, as well as properties of nuclear matter. We discuss the relationship between the nuclear surface diffuseness and elastic scattering differential cross section at the first diffraction peak of high-energy nucleon-nucleus scattering as an efficient tool in order to extract the nuclear surface information from limited experimental data involving short-lived unstable nuclei. The high-energy reaction is described by a reliable microscopic reaction theory, the Glauber model. Extending the idea of the black sphere model, we find one-to-one correspondence between the nuclear bulk structure information and proton-nucleus elastic scattering diffraction peak. This implies that we can extract both the nuclear radius and diffuseness simultaneously, using the position of the first diffraction peak and its magnitude of the elastic scattering differential cross section. We confirm the reliability of this approach by using realistic density distributions obtained by a mean-field model.

Mapping the categories of the Swedish primary health care version of ICD-10 to SNOMED CT concepts: Rule development and intercoder reliability in a mapping trial

PubMed Central

Vikström, Anna; Skånér, Ylva; Strender, Lars-Erik; Nilsson, Gunnar H

2007-01-01

Background Terminologies and classifications are used for different purposes and have different structures and content. Linking or mapping terminologies and classifications has been pointed out as a possible way to achieve various aims as well as to attain additional advantages in describing and documenting health care data. The objectives of this study were: • to explore and develop rules to be used in a mapping process • to evaluate intercoder reliability and the assessed degree of concordance when the 'Swedish primary health care version of the International Classification of Diseases version 10' (ICD-10) is matched to the Systematized Nomenclature of Medicine, Clinical Terms (SNOMED CT) • to describe characteristics in the coding systems that are related to obstacles to high quality mapping. Methods Mapping (interpretation, matching, assessment and rule development) was done by two coders. The Swedish primary health care version of ICD-10 with 972 codes was randomly divided into an allotment of three sets of categories, used in three mapping sequences, A, B and C. Mapping was done independently by the coders and new rules were developed between the sequences. Intercoder reliability was measured by comparing the results after each set. The extent of matching was assessed as either 'partly' or 'completely concordant' Results General principles for mapping were outlined before the first sequence, A. New mapping rules had significant impact on the results between sequences A - B (p < 0.01) and A - C (p < 0.001). The intercoder reliability in our study reached 83%. Obstacles to high quality mapping were mainly a lack of agreement by the coders due to structural and content factors in SNOMED CT and in the current ICD-10 version. The predominant reasons for this were difficulties in interpreting the meaning of the categories in the current ICD-10 version, and the presence of many related concepts in SNOMED CT. Conclusion Mapping from ICD-10-categories to SNOMED CT needs clear and extensive rules. It is possible to reach high intercoder reliability in mapping from ICD-10-categories to SNOMED CT. However, several obstacles to high quality mapping remain due to structure and content characteristics in both coding systems. PMID:17472757

CCARES: A computer algorithm for the reliability analysis of laminated CMC components

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Gyekenyesi, John P.

1993-01-01

Structural components produced from laminated CMC (ceramic matrix composite) materials are being considered for a broad range of aerospace applications that include various structural components for the national aerospace plane, the space shuttle main engine, and advanced gas turbines. Specifically, these applications include segmented engine liners, small missile engine turbine rotors, and exhaust nozzles. Use of these materials allows for improvements in fuel efficiency due to increased engine temperatures and pressures, which in turn generate more power and thrust. Furthermore, this class of materials offers significant potential for raising the thrust-to-weight ratio of gas turbine engines by tailoring directions of high specific reliability. The emerging composite systems, particularly those with silicon nitride or silicon carbide matrix, can compete with metals in many demanding applications. Laminated CMC prototypes have already demonstrated functional capabilities at temperatures approaching 1400 C, which is well beyond the operational limits of most metallic materials. Laminated CMC material systems have several mechanical characteristics which must be carefully considered in the design process. Test bed software programs are needed that incorporate stochastic design concepts that are user friendly, computationally efficient, and have flexible architectures that readily incorporate changes in design philosophy. The CCARES (Composite Ceramics Analysis and Reliability Evaluation of Structures) program is representative of an effort to fill this need. CCARES is a public domain computer algorithm, coupled to a general purpose finite element program, which predicts the fast fracture reliability of a structural component under multiaxial loading conditions.

Compact tracking of surgical instruments through structured markers.

PubMed

Alberto Borghese, N; Frosio, I

2013-07-01

Virtual and augmented reality surgery calls for reliable and efficient tracking of the surgical instruments in the virtual or real operating theatre. The most diffused approach uses three or more not aligned markers, attached to each instrument and surveyed by a set of cameras. However, the structure required to carry the markers does modify the instrument's mass distribution and can interfere with surgeon movements. To overcome these problems, we propose here a new methodology, based on structured markers, to compute the six degrees of freedom of a surgical instrument. Two markers are attached on the instrument axis and one of them has a stripe painted over its surface. We also introduce a procedure to compute with high accuracy the markers center on the cameras image, even when partially occluded by the instrument's axis or by other structures. Experimental results demonstrate the reliability and accuracy of the proposed approach. The introduction of structured passive markers can open new possibilities to accurate tracking, combining markers detection with real-time image processing.

Intra-session test-retest reliability of magnitude and structure of center of pressure from the Nintendo Wii Balance Board™ for a visually impaired and normally sighted population

PubMed Central

Jeter, Pamela E.; Wang, Jiangxia; Gu, Jialiang; Barry, Michael P.; Roach, Crystal; Corson, Marilyn; Yang, Liancheng; Dagnelie, Gislin

2014-01-01

Individuals with visual impairment (VI) have irreparable damage to one of the input streams contributing to postural stability. Here, we evaluated the intra-session test-retest reliability of the Wii Balance Board (WBB) for measuring Center of Pressure (COP) magnitude and structure, i.e. approximate entropy (ApEn) in fourteen legally blind participants and 21 participants with corrected-to-normal vision. Participants completed a validated balance protocol which included four sensory conditions: double-leg standing on a firm surface with eyes open (EO-firm); a firm surface with eyes closed (EC-firm); a foam surface with EO (EO-foam); and a foam surface with EC (EC-foam). Participants performed the full balance protocol twice during the session, separated by a period of 15 minutes, to determine the intraclass correlation coefficient (ICC). Absolute reliability was determined by the standard of measurement (SEM). The minimal difference (MD) was estimated to determine clinical significance for future studies. COP measures were derived from data sent by the WBB to a laptop via Bluetooth. COP scores increased with the difficulty of sensory condition indicating WBB sensitivity (all p < 0.01). ICCs in the VI group ranged from 0.73 to 0.95, indicating high to very high correlations, and the normal group showed moderate to very high ICCs (0.62–0.94). The SEM was comparable between groups regardless of between-subject variability. The reliability of the WBB makes it practical to screen for balance impairment among VI persons. PMID:25555361

Software reliability experiments data analysis and investigation

NASA Technical Reports Server (NTRS)

Walker, J. Leslie; Caglayan, Alper K.

1991-01-01

The objectives are to investigate the fundamental reasons which cause independently developed software programs to fail dependently, and to examine fault tolerant software structures which maximize reliability gain in the presence of such dependent failure behavior. The authors used 20 redundant programs from a software reliability experiment to analyze the software errors causing coincident failures, to compare the reliability of N-version and recovery block structures composed of these programs, and to examine the impact of diversity on software reliability using subpopulations of these programs. The results indicate that both conceptually related and unrelated errors can cause coincident failures and that recovery block structures offer more reliability gain than N-version structures if acceptance checks that fail independently from the software components are available. The authors present a theory of general program checkers that have potential application for acceptance tests.

A reliable ground bounce noise reduction technique for nanoscale CMOS circuits

NASA Astrophysics Data System (ADS)

Sharma, Vijay Kumar; Pattanaik, Manisha

2015-11-01

Power gating is the most effective method to reduce the standby leakage power by adding header/footer high-VTH sleep transistors between actual and virtual power/ground rails. When a power gating circuit transitions from sleep mode to active mode, a large instantaneous charge current flows through the sleep transistors. Ground bounce noise (GBN) is the high voltage fluctuation on real ground rail during sleep mode to active mode transitions of power gating circuits. GBN disturbs the logic states of internal nodes of circuits. A novel and reliable power gating structure is proposed in this article to reduce the problem of GBN. The proposed structure contains low-VTH transistors in place of high-VTH footer. The proposed power gating structure not only reduces the GBN but also improves other performance metrics. A large mitigation of leakage power in both modes eliminates the need of high-VTH transistors. A comprehensive and comparative evaluation of proposed technique is presented in this article for a chain of 5-CMOS inverters. The simulation results are compared to other well-known GBN reduction circuit techniques at 22 nm predictive technology model (PTM) bulk CMOS model using HSPICE tool. Robustness against process, voltage and temperature (PVT) variations is estimated through Monte-Carlo simulations.

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.

Crystalline-silicon reliability lessons for thin-film modules

NASA Technical Reports Server (NTRS)

Ross, R. G., Jr.

1985-01-01

The reliability of crystalline silicon modules has been brought to a high level with lifetimes approaching 20 years, and excellent industry credibility and user satisfaction. The transition from crystalline modules to thin film modules is comparable to the transition from discrete transistors to integrated circuits. New cell materials and monolithic structures will require new device processing techniques, but the package function and design will evolve to a lesser extent. Although there will be new encapsulants optimized to take advantage of the mechanical flexibility and low temperature processing features of thin films, the reliability and life degradation stresses and mechanisms will remain mostly unchanged. Key reliability technologies in common between crystalline and thin film modules include hot spot heating, galvanic and electrochemical corrosion, hail impact stresses, glass breakage, mechanical fatigue, photothermal degradation of encapsulants, operating temperature, moisture sorption, circuit design strategies, product safety issues, and the process required to achieve a reliable product from a laboratory prototype.

The Transition Readiness Assessment Questionnaire (TRAQ): its factor structure, reliability, and validity.

PubMed

Wood, David L; Sawicki, Gregory S; Miller, M David; Smotherman, Carmen; Lukens-Bull, Katryne; Livingood, William C; Ferris, Maria; Kraemer, Dale F

2014-01-01

National consensus statements recommend that providers regularly assess the transition readiness skills of adolescent and young adults (AYA). In 2010 we developed a 29-item version of Transition Readiness Assessment Questionnaire (TRAQ). We reevaluated item performance and factor structure, and reassessed the TRAQ's reliability and validity. We surveyed youth from 3 academic clinics in Jacksonville, Florida; Chapel Hill, North Carolina; and Boston, Massachusetts. Participants were AYA with special health care needs aged 14 to 21 years. From a convenience sample of 306 patients, we conducted item reduction strategies and exploratory factor analysis (EFA). On a second convenience sample of 221 patients, we conducted confirmatory factor analysis (CFA). Internal reliability was assessed by Cronbach's alpha and criterion validity. Analyses were conducted by the Wilcoxon rank sum test and mixed linear models. The item reduction and EFA resulted in a 20-item scale with 5 identified subscales. The CFA conducted on a second sample provided a good fit to the data. The overall scale has high reliability overall (Cronbach's alpha = .94) and good reliability for 4 of the 5 subscales (Cronbach's alpha ranging from .90 to .77 in the pooled sample). Each of the 5 subscale scores were significantly higher for adolescents aged 18 years and older versus those younger than 18 (P < .0001) in both univariate and multivariate analyses. The 20-item, 5-factor structure for the TRAQ is supported by EFA and CFA on independent samples and has good internal reliability and criterion validity. Additional work is needed to expand or revise the TRAQ subscales and test their predictive validity. Copyright © 2014 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Effects of PCB Pad Metal Finishes on the Cu-Pillar/Sn-Ag Micro Bump Joint Reliability of Chip-on-Board (COB) Assembly

NASA Astrophysics Data System (ADS)

Kim, Youngsoon; Lee, Seyong; Shin, Ji-won; Paik, Kyung-Wook

2016-06-01

While solder bumps have been used as the bump structure to form the interconnection during the last few decades, the continuing scaling down of devices has led to a change in the bump structure to Cu-pillar/Sn-Ag micro-bumps. Cu-pillar/Sn-Ag micro-bump interconnections differ from conventional solder bump interconnections in terms of their assembly processing and reliability. A thermo-compression bonding method with pre-applied b-stage non-conductive films has been adopted to form solder joints between Cu pillar/Sn-Ag micro bumps and printed circuit board vehicles, using various pad metal finishes. As a result, various interfacial inter-metallic compounds (IMCs) reactions and stress concentrations occur at the Cu pillar/Sn-Ag micro bumps joints. Therefore, it is necessary to investigate the influence of pad metal finishes on the structural reliability of fine pitch Cu pillar/Sn-Ag micro bumps flip chip packaging. In this study, four different pad surface finishes (Thin Ni ENEPIG, OSP, ENEPIG, ENIG) were evaluated in terms of their interconnection reliability by thermal cycle (T/C) test up to 2000 cycles at temperatures ranging from -55°C to 125°C and high-temperature storage test up to 1000 h at 150°C. The contact resistances of the Cu pillar/Sn-Ag micro bump showed significant differences after the T/C reliability test in the following order: thin Ni ENEPIG > OSP > ENEPIG where the thin Ni ENEPIG pad metal finish provided the best Cu pillar/Sn-Ag micro bump interconnection in terms of bump joint reliability. Various IMCs formed between the bump joint areas can account for the main failure mechanism.

Reliable and valid assessment of point-of-care ultrasonography.

PubMed

Todsen, Tobias; Tolsgaard, Martin Grønnebæk; Olsen, Beth Härstedt; Henriksen, Birthe Merete; Hillingsø, Jens Georg; Konge, Lars; Jensen, Morten Lind; Ringsted, Charlotte

2015-02-01

To explore the reliability and validity of the Objective Structured Assessment of Ultrasound Skills (OSAUS) scale for point-of-care ultrasonography (POC US) performance. POC US is increasingly used by clinicians and is an essential part of the management of acute surgical conditions. However, the quality of performance is highly operator-dependent. Therefore, reliable and valid assessment of trainees' ultrasonography competence is needed to ensure patient safety. Twenty-four physicians, representing novices, intermediates, and experts in POC US, scanned 4 different surgical patient cases in a controlled set-up. All ultrasound examinations were video-recorded and assessed by 2 blinded radiologists using OSAUS. Reliability was examined using generalizability theory. Construct validity was examined by comparing performance scores between the groups and by correlating physicians' OSAUS scores with diagnostic accuracy. The generalizability coefficient was high (0.81) and a D-study demonstrated that 1 assessor and 5 cases would result in similar reliability. The construct validity of the OSAUS scale was supported by a significant difference in the mean scores between the novice group (17.0; SD 8.4) and the intermediate group (30.0; SD 10.1), P = 0.007, as well as between the intermediate group and the expert group (72.9; SD 4.4), P = 0.04, and by a high correlation between OSAUS scores and diagnostic accuracy (Spearman ρ correlation coefficient = 0.76; P < 0.001). This study demonstrates high reliability as well as evidence of construct validity of the OSAUS scale for assessment of POC US competence. Hence, the OSAUS scale may be suitable for both in-training as well as end-of-training assessment.

Reliability analysis of composite structures

NASA Technical Reports Server (NTRS)

Kan, Han-Pin

1992-01-01

A probabilistic static stress analysis methodology has been developed to estimate the reliability of a composite structure. Closed form stress analysis methods are the primary analytical tools used in this methodology. These structural mechanics methods are used to identify independent variables whose variations significantly affect the performance of the structure. Once these variables are identified, scatter in their values is evaluated and statistically characterized. The scatter in applied loads and the structural parameters are then fitted to appropriate probabilistic distribution functions. Numerical integration techniques are applied to compute the structural reliability. The predicted reliability accounts for scatter due to variability in material strength, applied load, fabrication and assembly processes. The influence of structural geometry and mode of failure are also considerations in the evaluation. Example problems are given to illustrate various levels of analytical complexity.

The Shutdown Dissociation Scale (Shut-D)

PubMed Central

Schalinski, Inga; Schauer, Maggie; Elbert, Thomas

2015-01-01

The evolutionary model of the defense cascade by Schauer and Elbert (2010) provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D) was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity). A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups) from healthy controls. The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding. PMID:25976478

Highly reliable high-power AlGaAs/GaAs 808 nm diode laser bars

NASA Astrophysics Data System (ADS)

Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Hennig, P.

2007-02-01

There are strong demands at the market to increase power and reliability for 808 nm diode laser bars. Responding to this JENOPTIK Diode Lab GmbH developed high performance 808 nm diode laser bars in the AlGaAs/GaAs material system with special emphasis to high power operation and long term stability. Optimization of the epitaxy structure and improvements in the diode laser bar design results in very high slope efficiency of >1.2 W/A, low threshold current and small beam divergence in slow axis direction. Including low serial resistance the overall wall plug efficiency is up to 65% for our 20%, 30% and 50% filling factor 10 mm diode laser bars. With the JENOPTIK Diode Lab cleaving and coating technique the maximum output power is 205 W in CW operation and 377 W in QCW operation (200 μs, 2% duty cycle) for bars with 50% filling factor. These bars mounted on micro channel cooled package are showing a very high reliability of >15.000 h. Mounted on conductive cooled package high power operation at 100 W is demonstrated for more than 5000h.

Stirling Convertor Fasteners Reliability Quantification

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Korovaichuk, Igor; Kovacevich, Tiodor; Schreiber, Jeffrey G.

2006-01-01

Onboard Radioisotope Power Systems (RPS) being developed for NASA s deep-space science and exploration missions require reliable operation for up to 14 years and beyond. Stirling power conversion is a candidate for use in an RPS because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced inventory of radioactive material. Structural fasteners are responsible to maintain structural integrity of the Stirling power convertor, which is critical to ensure reliable performance during the entire mission. Design of fasteners involve variables related to the fabrication, manufacturing, behavior of fasteners and joining parts material, structural geometry of the joining components, size and spacing of fasteners, mission loads, boundary conditions, etc. These variables have inherent uncertainties, which need to be accounted for in the reliability assessment. This paper describes these uncertainties along with a methodology to quantify the reliability, and provides results of the analysis in terms of quantified reliability and sensitivity of Stirling power conversion reliability to the design variables. Quantification of the reliability includes both structural and functional aspects of the joining components. Based on the results, the paper also describes guidelines to improve the reliability and verification testing.

An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments

DOE PAGES

Guthrie, Michael A.

2013-01-01

limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment.more » For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.« less

Advances and trends in computational structural mechanics

NASA Technical Reports Server (NTRS)

Noor, A. K.

1986-01-01

Recent developments in computational structural mechanics are reviewed with reference to computational needs for future structures technology, advances in computational models for material behavior, discrete element technology, assessment and control of numerical simulations of structural response, hybrid analysis, and techniques for large-scale optimization. Research areas in computational structural mechanics which have high potential for meeting future technological needs are identified. These include prediction and analysis of the failure of structural components made of new materials, development of computational strategies and solution methodologies for large-scale structural calculations, and assessment of reliability and adaptive improvement of response predictions.

Study on application of aerospace technology to improve surgical implants

NASA Technical Reports Server (NTRS)

Johnson, R. E.; Youngblood, J. L.

1982-01-01

The areas where aerospace technology could be used to improve the reliability and performance of metallic, orthopedic implants was assessed. Specifically, comparisons were made of material controls, design approaches, analytical methods and inspection approaches being used in the implant industry with hardware for the aerospace industries. Several areas for possible improvement were noted such as increased use of finite element stress analysis and fracture control programs on devices where the needs exist for maximum reliability and high structural performance.

Structural design and analysis for an ultra low CTE optical bench for the Hubble Space Telescope corrective optics

NASA Technical Reports Server (NTRS)

Neam, Douglas C.; Gerber, John D.

1992-01-01

The stringent stability requirements of the Corrective Optics Space Telescope Axial Replacement (COSTAR) necessitates a Deployable Optical Bench (DOB) with both a low CTE and high resonant frequency. The DOB design consists of a monocoque thin shell structure which marries metallic machined parts with graphite epoxy formed structure. Structural analysis of the DOB has been integrated into the laminate design and optimization process. Also, the structural analytical results are compared with vibration and thermal test data to assess the reliability of the analysis.

Field-Induced Crystalline-to-Amorphous Phase Transformation on the Si Nano-Apex and the Achieving of Highly Reliable Si Nano-Cathodes

PubMed Central

Huang, Yifeng; Deng, Zexiang; Wang, Weiliang; Liang, Chaolun; She, Juncong; Deng, Shaozhi; Xu, Ningsheng

2015-01-01

Nano-scale vacuum channel transistors possess merits of higher cutoff frequency and greater gain power as compared with the conventional solid-state transistors. The improvement in cathode reliability is one of the major challenges to obtain high performance vacuum channel transistors. We report the experimental findings and the physical insight into the field induced crystalline-to-amorphous phase transformation on the surface of the Si nano-cathode. The crystalline Si tip apex deformed to amorphous structure at a low macroscopic field (0.6~1.65 V/nm) with an ultra-low emission current (1~10 pA). First-principle calculation suggests that the strong electrostatic force exerting on the electrons in the surface lattices would take the account for the field-induced atomic migration that result in an amorphization. The arsenic-dopant in the Si surface lattice would increase the inner stress as well as the electron density, leading to a lower amorphization field. Highly reliable Si nano-cathodes were obtained by employing diamond like carbon coating to enhance the electron emission and thus decrease the surface charge accumulation. The findings are crucial for developing highly reliable Si-based nano-scale vacuum channel transistors and have the significance for future Si nano-electronic devices with narrow separation. PMID:25994377

Development of highly efficient laser bars emitting at around 1060 nm for medical applications

NASA Astrophysics Data System (ADS)

Pietrzak, Agnieszka; Zorn, Martin; Meusel, Jens; Huelsewede, Ralf; Sebastian, Juergen

2018-02-01

An overview is presented on the recent progress in the development of high power laser bars at wavelengths around 1060nm. The development is focused on highly efficient and reliable laser performance under pulsed operation for medical applications. The epitaxial structure and lateral layout of the laser bars were tailored to meet the application requirements. Reliable operation peak powers of 350W and 500W are demonstrated from laser bars with fill-factor FF=75% and resonator lengths 1.5mm and 2.0mm, respectively. Moreover, 60W at current 65A with lifetime <10.000h are presented. The power scaling with fill-factor enables a cost reduction ($/W) up to 35%.

Characterization and reliability of aluminum gallium nitride/gallium nitride high electron mobility transistors

NASA Astrophysics Data System (ADS)

Douglas, Erica Ann

Compound semiconductor devices, particularly those based on GaN, have found significant use in military and civilian systems for both microwave and optoelectronic applications. Future uses in ultra-high power radar systems will require the use of GaN transistors operated at very high voltages, currents and temperatures. GaN-based high electron mobility transistors (HEMTs) have proven power handling capability that overshadows all other wide band gap semiconductor devices for high frequency and high-power applications. Little conclusive research has been reported in order to determine the dominating degradation mechanisms of the devices that result in failure under standard operating conditions in the field. Therefore, it is imperative that further reliability testing be carried out to determine the failure mechanisms present in GaN HEMTs in order to improve device performance, and thus further the ability for future technologies to be developed. In order to obtain a better understanding of the true reliability of AlGaN/GaN HEMTs and determine the MTTF under standard operating conditions, it is crucial to investigate the interaction effects between thermal and electrical degradation. This research spans device characterization, device reliability, and device simulation in order to obtain an all-encompassing picture of the device physics. Initially, finite element thermal simulations were performed to investigate the effect of device design on self-heating under high power operation. This was then followed by a study of reliability of HEMTs and other tests structures during high power dc operation. Test structures without Schottky contacts showed high stability as compared to HEMTs, indicating that degradation of the gate is the reason for permanent device degradation. High reverse bias of the gate has been shown to induce the inverse piezoelectric effect, resulting in a sharp increase in gate leakage current due to crack formation. The introduction of elevated temperatures during high reverse gate bias indicated that device failure is due to the breakdown of an unintentional gate oxide. RF stress of AlGaN/GaN HEMTs showed comparable critical voltage breakdown regime as that of similar devices stressed under dc conditions. Though RF device characteristics showed stability up to a drain bias of 20 V, Schottky diode characteristics degraded substantially at all voltages investigated. Results from both dc and RF stress conditions, under several bias regimes, confirm that the primary root for stress induced degradation was due to the Schottky contact. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Co3O4 based non-enzymatic glucose sensor with high sensitivity and reliable stability derived from hollow hierarchical architecture.

PubMed

Tian, Liangliang; He, Gege; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Yang, Cong; Chen, Yanling; Li, Lu

2018-02-16

Inspired by kinetics, the design of hollow hierarchical electrocatalysts through large-scale integration of building blocks is recognized as an effective approach to the achievement of superior electrocatalytic performance. In this work, a hollow, hierarchical Co 3 O 4 architecture (Co 3 O 4 HHA) was constructed using a coordinated etching and precipitation (CEP) method followed by calcination. The resulting Co 3 O 4 HHA electrode exhibited excellent electrocatalytic activity in terms of high sensitivity (839.3 μA mM -1 cm -2 ) and reliable stability in glucose detection. The high sensitivity could be attributed to the large specific surface area (SSA), ample unimpeded penetration diffusion paths and high electron transfer rate originating from the unique two-dimensional (2D) sheet-like character and hollow porous architecture. The hollow hierarchical structure also affords sufficient interspace for accommodation of volume change and structural strain, resulting in enhanced stability. The results indicate that Co 3 O 4 HHA could have potential for application in the design of non-enzymatic glucose sensors, and that the construction of hollow hierarchical architecture provides an efficient way to design highly active, stable electrocatalysts.

Co3O4 based non-enzymatic glucose sensor with high sensitivity and reliable stability derived from hollow hierarchical architecture

NASA Astrophysics Data System (ADS)

Tian, Liangliang; He, Gege; Cai, Yanhua; Wu, Shenping; Su, Yongyao; Yan, Hengqing; Yang, Cong; Chen, Yanling; Li, Lu

2018-02-01

Inspired by kinetics, the design of hollow hierarchical electrocatalysts through large-scale integration of building blocks is recognized as an effective approach to the achievement of superior electrocatalytic performance. In this work, a hollow, hierarchical Co3O4 architecture (Co3O4 HHA) was constructed using a coordinated etching and precipitation (CEP) method followed by calcination. The resulting Co3O4 HHA electrode exhibited excellent electrocatalytic activity in terms of high sensitivity (839.3 μA mM-1 cm-2) and reliable stability in glucose detection. The high sensitivity could be attributed to the large specific surface area (SSA), ample unimpeded penetration diffusion paths and high electron transfer rate originating from the unique two-dimensional (2D) sheet-like character and hollow porous architecture. The hollow hierarchical structure also affords sufficient interspace for accommodation of volume change and structural strain, resulting in enhanced stability. The results indicate that Co3O4 HHA could have potential for application in the design of non-enzymatic glucose sensors, and that the construction of hollow hierarchical architecture provides an efficient way to design highly active, stable electrocatalysts.

Development of a probabilistic analysis methodology for structural reliability estimation

NASA Technical Reports Server (NTRS)

Torng, T. Y.; Wu, Y.-T.

1991-01-01

The novel probabilistic analysis method for assessment of structural reliability presented, which combines fast-convolution with an efficient structural reliability analysis, can after identifying the most important point of a limit state proceed to establish a quadratic-performance function. It then transforms the quadratic function into a linear one, and applies fast convolution. The method is applicable to problems requiring computer-intensive structural analysis. Five illustrative examples of the method's application are given.

Application of Advanced Fracture Mechanics Technology to Ensure Structural Reliability in Critical Titanium Structures,

DTIC Science & Technology

1982-11-22

RD-Ri42 354 APPLICATION OF ADVANCED FRACTURE MECHANICS TECHNOLOGY i/i TT ENSURE STRUCTURA..(U) 1WESTINGHOUSE RESEARCH FND DEVELOPMENT CENTER...I Iml .4. 47 Igo 12. 4 %B 1. __ ~. ~% ski Z L __ 12 APPLICATION OF ADVANCED FRACTURE MECHANICS -p TECHNOLOGY TO ENSURE STRUCTURAL RELIABILITY IN...Road W Pilttsburgh. Pennsylvania 15235 84 06 18 207 APPLICATION OF ADVANCED FRACTURE MECHANICS TECHNOLOGY TO ENSURE STRUCTURAL RELIABILITY IN CRITICAL

Environmental change mediates mate choice for an extended phenotype, but not for mate quality.

PubMed

Head, Megan L; Fox, Rebecca J; Barber, Iain

2017-01-01

Sexual cues, including extended phenotypes, are expected to be reliable indicators of male genetic quality and/or provide information on parental quality. However, the reliability of these cues may be dependent on stability of the environment, with heterogeneity affecting how selection acts on such traits. Here, we test how environmental change mediates mate choice for multiple sexual traits, including an extended phenotype--the structure of male-built nests - in stickleback fish. First, we manipulated the dissolved oxygen (DO) content of water to create high or low DO environments in which male fish built nests. Then we recorded the mate choice of females encountering these males (and their nests), under either the same or reversed DO conditions. Males in high DO environments built more compact nests than those in low DO conditions and males adjusted their nest structure in response to changing conditions. Female mate choice for extended phenotype (male nests) was environmentally dependent (females chose more compact nests in high DO conditions), while female choice for male phenotype was not (females chose large, vigorous males regardless of DO level). Examining mate choice in this dynamic context suggests that females evaluate the reliability of multiple sexual cues, taking into account environmental heterogeneity. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Three-dimensional facial anthropometry of unilateral cleft lip infants with a structured light scanning system.

PubMed

Li, Guanghui; Wei, Jianhua; Wang, Xi; Wu, Guofeng; Ma, Dandan; Wang, Bo; Liu, Yanpu; Feng, Xinghua

2013-08-01

Cleft lip in the presence or absence of a cleft palate is a major public health problem. However, few studies have been published concerning the soft-tissue morphology of cleft lip infants. Currently, obtaining reliable three-dimensional (3D) surface models of infants remains a challenge. The aim of this study was to investigate a new way of capturing 3D images of cleft lip infants using a structured light scanning system. In addition, the accuracy and precision of the acquired facial 3D data were validated and compared with direct measurements. Ten unilateral cleft lip patients were enrolled in the study. Briefly, 3D facial images of the patients were acquired using a 3D scanner device before and after the surgery. Fourteen items were measured by direct anthropometry and 3D image software. The accuracy and precision of the 3D system were assessed by comparative analysis. The anthropometric data obtained using the 3D method were in agreement with the direct anthropometry measurements. All data calculated by the software were 'highly reliable' or 'reliable', as defined in the literature. The localisation of four landmarks was not consistent in repeated experiments of inter-observer reliability in preoperative images (P<0.05), while the intra-observer reliability in both pre- and postoperative images was good (P>0.05). The structured light scanning system is proven to be a non-invasive, accurate and precise method in cleft lip anthropometry. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

An Overview of Long Duration Sodium Heat Pipe Tests

NASA Astrophysics Data System (ADS)

Rosenfeld, John H.; Ernst, Donald M.; Lindemuth, James E.; Sanzi, James L.; Geng, Steven M.; Zuo, Jon

2004-02-01

High temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, and Stirling cycle heat sources; with the resurgence of space nuclear power, additional applications include reactor heat removal elements and radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly long-term materials compatibility is being evaluated through the use of high temperature life test heat pipes. Thermacore, Inc. has carried out several sodium heat pipe life tests to establish long term operating reliability. Four sodium heat pipes have recently demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A 316L stainless steel heat pipe with a sintered porous nickel wick structure and an integral brazed cartridge heater has successfully operated at 650C to 700C for over 115,000 hours without signs of failure. A second 316L stainless steel heat pipe with a specially-designed Inconel 601 rupture disk and a sintered nickel powder wick has demonstrated over 83,000 hours at 600C to 650C with similar success. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 41,000 hours at nearly 700C. A hybrid (i.e. gas-fired and solar) heat pipe with a Haynes 230 envelope and a sintered porous nickel wick structure was operated for about 20,000 hours at nearly 700C without signs of degradation. These life test results collectively have demonstrated the potential for high temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability. Detailed design specifications, operating history, and test results are described for each of these sodium heat pipes. Lessons learned and future life test plans are also discussed.

An Overview of Long Duration Sodium Heat Pipe Tests

NASA Technical Reports Server (NTRS)

Rosenfeld, John H.; Ernst, Donald M.; Lindemuth, James E.; Sanzi, James L.; Geng, Steven M.; Zuo, Jon

2004-01-01

High temperature heat pipes are being evaluated for use in energy conversion applications such as fuel cells, gas turbine re-combustors, and Stirling cycle heat sources; with the resurgence of space nuclear power, additional applications include reactor heat removal elements and radiator elements. Long operating life and reliable performance are critical requirements for these applications. Accordingly long-term materials compatibility is being evaluated through the use of high temperature life test heat pipes. Thermacore International, Inc., has carried out several sodium heat pipe life tests to establish long term operating reliability. Four sodium heat pipes have recently demonstrated favorable materials compatibility and heat transport characteristics at high operating temperatures in air over long time periods. A 3l6L stainless steel heat pipe with a sintered porous nickel wick structure and an integral brazed cartridge heater has successfully operated at 650 to 700 C for over 115,000 hours without signs of failure. A second 3l6L stainless steel heat pipe with a specially-designed Inconel 60 I rupture disk and a sintered nickel powder wick has demonstrated over 83,000 hours at 600 to 650 C with similar success. A representative one-tenth segment Stirling Space Power Converter heat pipe with an Inconel 718 envelope and a stainless steel screen wick has operated for over 41 ,000 hours at nearly 700 0c. A hybrid (i.e. gas-fired and solar) heat pipe with a Haynes 230 envelope and a sintered porous nickel wick structure was operated for about 20,000 hours at nearly 700 C without signs of degradation. These life test results collectively have demonstrated the potential for high temperature heat pipes to serve as reliable energy conversion system components for power applications that require long operating lifetime with high reliability, Detailed design specifications, operating hi story, and test results are described for each of these sodium heat pipes. Lessons learned and future life test plans are also discussed.

Anticipating College Enrollment: Adapting "SuccessNavigator"® for High School Students. Research Report. ETS RR-15-37

ERIC Educational Resources Information Center

Rikoon, Samuel H.; Liebtag, Travis; Olivera-Aguilar, Margarita; Steinberg, Jonathan; Robbins, Steven B.

2015-01-01

In this report, we describe the development of an extension of the "SuccessNavigator"® assessment for late high school settings. We discuss the assessment's conceptualization and support its application with psychometric studies detailing scale development in terms of structural analyses, reliability, and several other aspects of…

The Addiction Severity Index: reliability and validity in a Dutch alcoholic population.

PubMed

DeJong, C A; Willems, J C; Schippers, G M; Hendriks, V M

1995-04-01

The Addiction Severity Index (ASI) was evaluated for its psychometric qualities in a Dutch alcoholic population admitted to an addiction treatment center in The Netherlands. Its factorial structure in this population was found to be consistent with the established six factor structure of the ASI. Reliability analysis revealed that the homogeneity of the subscales was acceptable with the exception of the Alcohol Scale. The six subscales were not highly intercorrelated. The results of this study indicate that the ASI is a useful instrument for the assessment of several problems associated with alcoholism. However, the Alcohol Scale appears to be limited as a diagnostic and research instrument in the field of inpatient treatment of alcohol dependence in The Netherlands.

Choosing a reliability inspection plan for interval censored data

DOE PAGES

Lu, Lu; Anderson-Cook, Christine Michaela

2017-04-19

Reliability test plans are important for producing precise and accurate assessment of reliability characteristics. This paper explores different strategies for choosing between possible inspection plans for interval censored data given a fixed testing timeframe and budget. A new general cost structure is proposed for guiding precise quantification of total cost in inspection test plan. Multiple summaries of reliability are considered and compared as the criteria for choosing the best plans using an easily adapted method. Different cost structures and representative true underlying reliability curves demonstrate how to assess different strategies given the logistical constraints and nature of the problem. Resultsmore » show several general patterns exist across a wide variety of scenarios. Given the fixed total cost, plans that inspect more units with less frequency based on equally spaced time points are favored due to the ease of implementation and consistent good performance across a large number of case study scenarios. Plans with inspection times chosen based on equally spaced probabilities offer improved reliability estimates for the shape of the distribution, mean lifetime, and failure time for a small fraction of population only for applications with high infant mortality rates. The paper uses a Monte Carlo simulation based approach in addition to the common evaluation based on the asymptotic variance and offers comparison and recommendation for different applications with different objectives. Additionally, the paper outlines a variety of different reliability metrics to use as criteria for optimization, presents a general method for evaluating different alternatives, as well as provides case study results for different common scenarios.« less

Choosing a reliability inspection plan for interval censored data

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

Lu, Lu; Anderson-Cook, Christine Michaela

Reliability test plans are important for producing precise and accurate assessment of reliability characteristics. This paper explores different strategies for choosing between possible inspection plans for interval censored data given a fixed testing timeframe and budget. A new general cost structure is proposed for guiding precise quantification of total cost in inspection test plan. Multiple summaries of reliability are considered and compared as the criteria for choosing the best plans using an easily adapted method. Different cost structures and representative true underlying reliability curves demonstrate how to assess different strategies given the logistical constraints and nature of the problem. Resultsmore » show several general patterns exist across a wide variety of scenarios. Given the fixed total cost, plans that inspect more units with less frequency based on equally spaced time points are favored due to the ease of implementation and consistent good performance across a large number of case study scenarios. Plans with inspection times chosen based on equally spaced probabilities offer improved reliability estimates for the shape of the distribution, mean lifetime, and failure time for a small fraction of population only for applications with high infant mortality rates. The paper uses a Monte Carlo simulation based approach in addition to the common evaluation based on the asymptotic variance and offers comparison and recommendation for different applications with different objectives. Additionally, the paper outlines a variety of different reliability metrics to use as criteria for optimization, presents a general method for evaluating different alternatives, as well as provides case study results for different common scenarios.« less

The Norwegian Computerized Adaptive Test of Personality Disorder-Static Form (CAT-PD-SF): Reliability, Factor Structure, and Relationships With Personality Functioning.

PubMed

Thimm, Jens C

2017-12-01

The Computerized Adaptive Test of Personality Disorder-Static Form (CAT-PD-SF) is a self-report inventory developed to assess pathological personality traits. The current study explored the reliability and higher order factor structure of the Norwegian version of the CAT-PD-SF and the relationships between the CAT-PD traits and domains of personality functioning in an undergraduate student sample ( N = 375). In addition to the CAT-PD-SF, the short form of the Severity Indices of Personality Problems and the Brief Symptom Inventory were administered. The results showed that the Norwegian CAT-PD-SF has good score reliability. Factor analysis of the CAT-PD-SF scales indicated five superordinate factors that correspond to the trait domains of the alternative DSM-5 model for personality disorders. The CAT-PD traits were highly predictive of impaired personality functioning after controlling for psychological distress. It is concluded that the CAT-PD-SF is a promising tool for the assessment of personality disorder traits.

Developing a novel hierarchical approach for multiscale structural reliability predictions for ultra-high consequence applications

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

Emery, John M.; Coffin, Peter; Robbins, Brian A.

Microstructural variabilities are among the predominant sources of uncertainty in structural performance and reliability. We seek to develop efficient algorithms for multiscale calcu- lations for polycrystalline alloys such as aluminum alloy 6061-T6 in environments where ductile fracture is the dominant failure mode. Our approach employs concurrent multiscale methods, but does not focus on their development. They are a necessary but not sufficient ingredient to multiscale reliability predictions. We have focused on how to efficiently use concurrent models for forward propagation because practical applications cannot include fine-scale details throughout the problem domain due to exorbitant computational demand. Our approach begins withmore » a low-fidelity prediction at the engineering scale that is sub- sequently refined with multiscale simulation. The results presented in this report focus on plasticity and damage at the meso-scale, efforts to expedite Monte Carlo simulation with mi- crostructural considerations, modeling aspects regarding geometric representation of grains and second-phase particles, and contrasting algorithms for scale coupling.« less

Development of highly reliable static random access memory for 40-nm embedded split gate-MONOS flash memory

NASA Astrophysics Data System (ADS)

Okamoto, Shin-ichi; Maekawa, Kei-ichi; Kawashima, Yoshiyuki; Shiba, Kazutoshi; Sugiyama, Hideki; Inoue, Masao; Nishida, Akio

2015-04-01

High quality static random access memory (SRAM) for 40-nm embedded MONOS flash memory with split gate (SG-MONOS) was developed. Marginal failure, which results in threshold voltage/drain current tailing and outliers of SRAM transistors, occurs when using a conventional SRAM structure. These phenomena can be explained by not only gate depletion but also partial depletion and percolation path formation in the MOS channel. A stacked poly-Si gate structure can suppress these phenomena and achieve high quality SRAM without any defects in the 6σ level and with high affinity to the 40-nm SG-MONOS process was developed.

[Psychometric properties of the third version of family adaptability and cohesion evaluation scales (FACES-III): a study of peruvian adolescents].

PubMed

Bazo-Alvarez, Juan Carlos; Bazo-Alvarez, Oscar Alfredo; Aguila, Jeins; Peralta, Frank; Mormontoy, Wilfredo; Bennett, Ian M

2016-01-01

Our aim was to evaluate the psychometric properties of the FACES-III among Peruvian high school students. This is a psychometric cross-sectional study. A probabilistic sampling was applied, defined by three stages: stratum one (school), stratum two (grade) and cluster (section). The participants were 910 adolescent students of both sexes, between 11 and 18 years of age. The instrument was also the object of study: the Olson's FACES-III. The analysis included a review of the structure / construct validity of the measure by factor analysis and assessment of internal consistency (reliability). The real-cohesion scale had moderately high reliability (Ω=.85) while the real-flexibility scale had moderate reliability (Ω=.74). The reliability found for the ideal-cohesion was moderately high (Ω=.89) like for the scale of ideal-flexibility (Ω=.86). Construct validity was confirmed by the goodness of fit of a two factor model (cohesion and flexibility) with 10 items each [Adjusted goodness of fit index (AGFI) = 0.96; Expected Cross Validation Index (ECVI) = 0.87; Normed fit index (NFI) = 0.93; Goodness of fit index (GFI) = 0.97; Root mean square error of approximation (RMSEA) = 0.06]. FACES-III has sufficient reliability and validity to be used in Peruvian adolescents for the purpose of group or individual assessment.

Probabilistic durability assessment of concrete structures in marine environments: Reliability and sensitivity analysis

NASA Astrophysics Data System (ADS)

Yu, Bo; Ning, Chao-lie; Li, Bing

2017-03-01

A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.

Reliability and validity of a semi-structured DSM-based diagnostic interview module for the assessment of Attention Deficit Hyperactivity Disorder in adult psychiatric outpatients.

PubMed

Gorlin, Eugenia I; Dalrymple, Kristy; Chelminski, Iwona; Zimmerman, Mark

2016-08-30

Despite growing recognition that the symptoms and functional impairments of Attention Deficit/Hyperactivity Disorder (ADHD) persist into adulthood, only a few psychometrically sound diagnostic measures have been developed for the assessment of ADHD in adults, and none have been validated for use in a broad treatment-seeking psychiatric sample. The current study presents the reliability and validity of a semi-structured DSM-based diagnostic interview module for ADHD, which was administered to 1194 adults presenting to an outpatient psychiatric practice. The module showed excellent internal consistency and interrater reliability, good convergent and discriminant validity (as indexed by relatively high correlations with self-report measures of ADHD and ADHD-related constructs and little or no correlation with other, non-ADHD symptom domains), and good construct validity (as indexed by significantly higher rates of psychosocial impairment and self-reported family history of ADHD in individuals who meet criteria for an ADHD diagnosis). This instrument is thus a reliable and valid diagnostic tool for the detection of ADHD in adults presenting for psychiatric evaluation and treatment. Published by Elsevier Ireland Ltd.

A Structured Clinical Interview for Kleptomania (SCI-K): preliminary validity and reliability testing.

PubMed

Grant, Jon E; Kim, Suck Won; McCabe, James S

2006-06-01

Kleptomania presents difficulties in diagnosis for clinicians. This study aimed to develop and test a DSM-IV-based diagnostic instrument for kleptomania. To assess for current kleptomania the Structured Clinical Interview for Kleptomania (SCI-K) was administered to 112 consecutive subjects requesting psychiatric outpatient treatment for a variety of disorders. Reliability and validity were determined. Classification accuracy was examined using the longitudinal course of illness. The SCI-K demonstrated excellent test-retest (Phi coefficient = 0.956 (95% CI = 0.937, 0.970)) and inter-rater reliability (phi coefficient = 0.718 (95% CI = 0.506, 0.848)) in the diagnosis of kleptomania. Concurrent validity was observed with a self-report measure using DSM-IV kleptomania criteria (phi coefficient = 0.769 (95% CI = 0.653, 0.850)). Discriminant validity was observed with a measure of depression (point biserial coefficient = -0.020 (95% CI = -0.205, 0.166)). The SCI-K demonstrated both high sensitivity and specificity based on longitudinal assessment. The SCI-K demonstrated excellent reliability and validity in diagnosing kleptomania in subjects presenting with various psychiatric problems. These findings require replication in larger groups, including non-psychiatric populations, to examine their generalizability. Copyright (c) 2006 John Wiley & Sons, Ltd.

Reliability Analysis of Brittle Material Structures - Including MEMS(?) - With the CARES/Life Program

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.

2002-01-01

Brittle materials are being used, or considered, for a wide variety of high tech applications that operate in harsh environments, including static and rotating turbine parts. thermal protection systems, dental prosthetics, fuel cells, oxygen transport membranes, radomes, and MEMS. Designing components to sustain repeated load without fracturing while using the minimum amount of material requires the use of a probabilistic design methodology. The CARES/Life code provides a general-purpose analysis tool that predicts the probability of failure of a ceramic component as a function of its time in service. For this presentation an interview of the CARES/Life program will be provided. Emphasis will be placed on describing the latest enhancements to the code for reliability analysis with time varying loads and temperatures (fully transient reliability analysis). Also, early efforts in investigating the validity of using Weibull statistics, the basis of the CARES/Life program, to characterize the strength of MEMS structures will be described as as well as the version of CARES/Life for MEMS (CARES/MEMS) being prepared which incorporates single crystal and edge flaw reliability analysis capability. It is hoped this talk will open a dialog for potential collaboration in the area of MEMS testing and life prediction.

The German Version of the Herth Hope Index (HHI-D): Development and Psychometric Properties.

PubMed

Geiser, Franziska; Zajackowski, Katharina; Conrad, Rupert; Imbierowicz, Katrin; Wegener, Ingo; Herth, Kaye A; Urbach, Anne Sarah

2015-01-01

The importance of hope is evident in clinical oncological care. Hope is associated with psychological and also physical functioning. However, there is still a dearth of empirical research on hope as a multidimensional concept. The Herth Hope Index is a reliable and valid instrument for the measurement of hope and is available in many languages. Until now no authorized German translation has been published and validated. After translation, the questionnaire was completed by 192 patients with different tumor entities in radiation therapy. Reliability, concurrent validity, and factor structure of the questionnaire were determined. Correlations were high with depression and anxiety as well as optimism and pessimism. As expected, correlations with coping styles were moderate. Internal consistency and test-retest reliability were satisfactory. We could not replicate the original 3-factor model. Application of the scree plot criterion in an exploratory factor analysis resulted in a single-factor structure. The Herth Hope Index - German Version (HHI-D) is a short, reliable, and valid instrument for the assessment of hope in patient populations. We recommend using only the HHI-D total score until further research gives more insights into possible factorial solutions and subscales. © 2015 S. Karger GmbH, Freiburg.

Implementation strategies influence the structure, process and outcome of quality systems: an empirical study of hospital departments in Sweden.

PubMed

Kunkel, S; Rosenqvist, U; Westerling, R

2009-02-01

To analyse whether the organisation of quality systems (structure, process, and outcome) is related to how these systems were implemented (implementation prerequisites, cooperation between managers and staff, and source of initiative). A questionnaire was developed, piloted and distributed to 600 hospital departments. Questions were included to reflect implementation prerequisites (adequate resources, competence, problem-solving capacity and high expectations), cooperative implementation, source of initiative (manager, staff and purchaser), structure (resources and administration), process (culture and cooperation) and outcome (goal evaluation and competence development). The adjusted response rate was 75%. Construct validity and reliability was assessed by confirmatory factor analysis, and Cronbach alpha scores were calculated. The relationships among the variables were analysed with structural equation modelling with LISREL. Implementation prerequisites were highly related to structure (0.51) and process (0.33). Cooperative implementation was associated with process (0.26) and outcome (0.34). High manager initiative was related to structure (0.19) and process (0.17). The numbers in parentheses can be interpreted as correlations. Construct validity was good, and reliability was excellent for all factors (Cronbach alpha>0.78). The model was a good representation of reality (model fit p value = 0.082). The implementation of organisationally demanding quality systems may require managers to direct and lead the process while assuring that their staff get opportunities to contribute to the planning and designing of the new system. This would correspond to a cooperative implementation strategy rather than to top-down or bottom-up strategies. The results of this study could be used to adjust implementation processes.

MEMS Reliability Assurance Activities at JPL

NASA Technical Reports Server (NTRS)

Kayali, S.; Lawton, R.; Stark, B.

2000-01-01

An overview of Microelectromechanical Systems (MEMS) reliability assurance and qualification activities at JPL is presented along with the a discussion of characterization of MEMS structures implemented on single crystal silicon, polycrystalline silicon, CMOS, and LIGA processes. Additionally, common failure modes and mechanisms affecting MEMS structures, including radiation effects, are discussed. Common reliability and qualification practices contained in the MEMS Reliability Assurance Guideline are also presented.

High-rate RTK and PPP multi-GNSS positioning for small-scale dynamic displacements monitoring

NASA Astrophysics Data System (ADS)

Paziewski, Jacek; Sieradzki, Rafał; Baryła, Radosław; Wielgosz, Pawel

2017-04-01

The monitoring of dynamic displacements and deformations of engineering structures such as buildings, towers and bridges is of great interest due to several practical and theoretical reasons. The most important is to provide information required for safe maintenance of the constructions. High temporal resolution and precision of GNSS observations predestine this technology to be applied to most demanding application in terms of accuracy, availability and reliability. GNSS technique supported by appropriate processing methodology may meet the specific demands and requirements of ground and structures monitoring. Thus, high-rate multi-GNSS signals may be used as reliable source of information on dynamic displacements of ground and engineering structures, also in real time applications. In this study we present initial results of application of precise relative GNSS positioning for detection of small scale (cm level) high temporal resolution dynamic displacements. Methodology and algorithms applied in self-developed software allowing for relative positioning using high-rate dual-frequency phase and pseudorange GPS+Galileo observations are also given. Additionally, an approach was also made to use the Precise Point Positioning technique to such application. In the experiment were used the observations obtained from high-rate (20 Hz) geodetic receivers. The dynamic displacements were simulated using specially constructed device moving GNSS antenna with dedicated amplitude and frequency. The obtained results indicate on possibility of detection of dynamic displacements of the GNSS antenna even at the level of few millimetres using both relative and Precise Point Positioning techniques after suitable signals processing.

Predicting laser weld reliability with stochastic reduced-order models. Predicting laser weld reliability

DOE PAGES

Emery, John M.; Field, Richard V.; Foulk, James W.; ...

2015-05-26

Laser welds are prevalent in complex engineering systems and they frequently govern failure. The weld process often results in partial penetration of the base metals, leaving sharp crack-like features with a high degree of variability in the geometry and material properties of the welded structure. Furthermore, accurate finite element predictions of the structural reliability of components containing laser welds requires the analysis of a large number of finite element meshes with very fine spatial resolution, where each mesh has different geometry and/or material properties in the welded region to address variability. We found that traditional modeling approaches could not bemore » efficiently employed. Consequently, a method is presented for constructing a surrogate model, based on stochastic reduced-order models, and is proposed to represent the laser welds within the component. Here, the uncertainty in weld microstructure and geometry is captured by calibrating plasticity parameters to experimental observations of necking as, because of the ductility of the welds, necking – and thus peak load – plays the pivotal role in structural failure. The proposed method is exercised for a simplified verification problem and compared with the traditional Monte Carlo simulation with rather remarkable results.« less

The Reliability of Psychiatric Diagnosis Revisited

PubMed Central

Rankin, Eric; France, Cheryl; El-Missiry, Ahmed; John, Collin

2006-01-01

Background: The authors reviewed the topic of reliability of psychiatric diagnosis from the turn of the 20th century to present. The objectives of this paper are to explore the reasons of unreliability of psychiatric diagnosis and propose ways to improve the reliability of psychiatric diagnosis. Method: The authors reviewed the literature on the concept of reliability of psychiatric diagnosis with emphasis on the impact of interviewing skills, use of diagnostic criteria, and structured interviews on the reliability of psychiatric diagnosis. Results: Causes of diagnostic unreliability are attributed to the patient, the clinician and psychiatric nomenclature. The reliability of psychiatric diagnosis can be enhanced by using diagnostic criteria, defining psychiatric symptoms and structuring the interviews. Conclusions: The authors propose the acronym ‘DR.SED,' which stands for diagnostic criteria, reference definitions, structuring the interview, clinical experience, and data. The authors recommend that clinicians use the DR.SED paradigm to improve the reliability of psychiatric diagnoses. PMID:21103149

Intra-session test-retest reliability of magnitude and structure of center of pressure from the Nintendo Wii Balance Board™ for a visually impaired and normally sighted population.

PubMed

Jeter, Pamela E; Wang, Jiangxia; Gu, Jialiang; Barry, Michael P; Roach, Crystal; Corson, Marilyn; Yang, Lindsay; Dagnelie, Gislin

2015-02-01

Individuals with visual impairment (VI) have irreparable damage to one of the input streams contributing to postural stability. Here, we evaluated the intra-session test-retest reliability of the Wii Balance Board (WBB) for measuring Center of Pressure (COP) magnitude and structure, i.e. approximate entropy (ApEn) in fourteen legally blind participants and 21 participants with corrected-to-normal vision. Participants completed a validated balance protocol which included four sensory conditions: double-leg standing on a firm surface with eyes open (EO-firm); a firm surface with eyes closed (EC-firm); a foam surface with EO (EO-foam); and a foam surface with EC (EC-foam). Participants performed the full balance protocol twice during the session, separated by a period of 15min, to determine the intraclass correlation coefficient (ICC). Absolute reliability was determined by the standard error of measurement (SEM). The minimal difference (MD) was estimated to determine clinical significance for future studies. COP measures were derived from data sent by the WBB to a laptop via Bluetooth. COP scores increased with the difficulty of sensory condition indicating WBB sensitivity (all p<0.01). ICCs in the VI group ranged from 0.73 to 0.95, indicating high to very high correlations, and the normal group showed moderate to very high ICCs (0.62-0.94). The SEM was comparable between groups regardless of between-subject variability. The reliability of the WBB makes it practical to screen for balance impairment among VI persons. Copyright © 2014 Elsevier B.V. All rights reserved.

Radioistopes to Solar to High Energy Accelerators - Chip-Scale Energy Sources

NASA Astrophysics Data System (ADS)

Lal, Amit

2013-12-01

This talk will present MEMS based power sources that utilize radioisotopes, solar energy, and potentially nuclear energy through advancements in integration of new structures and materials within MEMS. Micro power harvesters can harness power from vibration, radioisotopes, light, sound, and biology may provide pathways to minimize or even eliminate batteries in sensor nodes. In this talk work on radioisotope thin films for MEMS will be include the self-reciprocating cantilever, betavoltaic cells, and high DC voltages. The self-reciprocating cantilever energy harvester allows small commercially viable amounts of radioisotopes to generate mW to Watts of power so that very reliable power sources that last 100s of years are possible. The tradeoffs between reliability and potential stigma with radioisotopes allow one to span a useful design space with reliability as a key parameter. These power sources provide pulsed power at three different time scales using mechanical, RF, and static extraction of energy from collected charge. Multi-use capability, both harvesting radioisotope power and local vibration energy extends the reliability of micro-power sources further.

Analysis of whisker-toughened CMC structural components using an interactive reliability model

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.; Palko, Joseph L.

1992-01-01

Realizing wider utilization of ceramic matrix composites (CMC) requires the development of advanced structural analysis technologies. This article focuses on the use of interactive reliability models to predict component probability of failure. The deterministic William-Warnke failure criterion serves as theoretical basis for the reliability model presented here. The model has been implemented into a test-bed software program. This computer program has been coupled to a general-purpose finite element program. A simple structural problem is presented to illustrate the reliability model and the computer algorithm.

First trimester size charts of embryonic brain structures.

PubMed

Gijtenbeek, M; Bogers, H; Groenenberg, I A L; Exalto, N; Willemsen, S P; Steegers, E A P; Eilers, P H C; Steegers-Theunissen, R P M

2014-02-01

Can reliable size charts of human embryonic brain structures be created from three-dimensional ultrasound (3D-US) visualizations? Reliable size charts of human embryonic brain structures can be created from high-quality images. Previous studies on the visualization of both the cavities and the walls of the brain compartments were performed using 2D-US, 3D-US or invasive intrauterine sonography. However, the walls of the diencephalon, mesencephalon and telencephalon have not been measured non-invasively before. Last-decade improvements in transvaginal ultrasound techniques allow a better visualization and offer the tools to measure these human embryonic brain structures with precision. This study is embedded in a prospective periconceptional cohort study. A total of 141 pregnancies were included before the sixth week of gestation and were monitored until delivery to assess complications and adverse outcomes. For the analysis of embryonic growth, 596 3D-US scans encompassing the entire embryo were obtained from 106 singleton non-malformed live birth pregnancies between 7(+0) and 12(+6) weeks' gestational age (GA). Using 4D View (3D software) the measured embryonic brain structures comprised thickness of the diencephalon, mesencephalon and telencephalon, and the total diameter of the diencephalon and mesencephalon. Of 596 3D scans, 161 (27%) high-quality scans of 79 pregnancies were eligible for analysis. The reliability of all embryonic brain structure measurements, based on the intra-class correlation coefficients (ICCs) (all above 0.98), was excellent. Bland-Altman plots showed moderate agreement for measurements of the telencephalon, but for all other measurements the agreement was good. Size charts were constructed according to crown-rump length (CRL). The percentage of high-quality scans suitable for analysis of these brain structures was low (27%).  The size charts of human embryonic brain structures can be used to study normal and abnormal development of brain development in future. Also, the effects of periconceptional maternal exposures, such as folic acid supplement use and smoking, on human embryonic brain development can be a topic of future research. This study was supported by the Department of Obstetrics and Gynaecology of the Erasmus University Medical Center. M.G. was supported by an additional grant from the Sophia Foundation for Medical Research (SSWO grant number 644). No competing interests are declared.

75 FR 40775 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-14

... operation at low and high power. No degradation of the beam quality due to thermal stress can be tolerated.... Therefore a simple and reliable structure like the 4-rod RFQ is the best choice for the required task of...

Composite membrane with integral rim

DOEpatents

Routkevitch, Dmitri; Polyakov, Oleg G

2015-01-27

Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

[Comparative study of the population structure and population assignment of sockeye salmon Oncorhynchus nerka from West Kamchatka based on RAPD-PCR and microsatellite polymorphism].

PubMed

Zelenina, D A; Khrustaleva, A M; Volkov, A A

2006-05-01

Using two types of molecular markers, a comparative analysis of the population structure of sockeye salmon from West Kamchatka as well as population assignment of each individual fish were carried out. The values of a RAPD-PCR-based population assignment test (94-100%) were somewhat higher than those based on microsatellite data (74-84%). However, these results seem quite satisfactory because of high polymorphism of the microsatellite loci examined. The UPGMA dendrograms of genetic similarity of three largest spawning populations, constructed using each of the methods, were highly reliable, which was demonstrated by high bootstrap indices (100% in the case of RAPD-PCR; 84 and 100%, in the case of microsatellite analysis), though the resultant trees differed from one another. The different topology of the trees, in our view, is explained by the fact that the employed methods explored different parts of the genome; hence, the obtained results, albeit valid, may not correlate. Thus, to enhance reliability of the results, several methods of analysis should be used concurrently.

Psychometric Properties and Factor Structure of the German Version of the Clinician-Administered PTSD Scale for DSM-5.

PubMed

Müller-Engelmann, Meike; Schnyder, Ulrich; Dittmann, Clara; Priebe, Kathlen; Bohus, Martin; Thome, Janine; Fydrich, Thomas; Pfaltz, Monique C; Steil, Regina

2018-05-01

The Clinician-Administered PTSD Scale (CAPS) is a widely used diagnostic interview for posttraumatic stress disorder (PTSD). Following fundamental modifications in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition ( DSM-5), the CAPS had to be revised. This study examined the psychometric properties (internal consistency, interrater reliability, convergent and discriminant validity, and structural validity) of the German version of the CAPS-5 in a trauma-exposed sample ( n = 223 with PTSD; n =51 without PTSD). The results demonstrated high internal consistency (αs = .65-.93) and high interrater reliability (ICCs = .81-.89). With regard to convergent and discriminant validity, we found high correlations between the CAPS severity score and both the Posttraumatic Diagnostic Scale sum score ( r = .87) and the Beck Depression Inventory total score ( r = .72). Regarding the underlying factor structure, the hybrid model demonstrated the best fit, followed by the anhedonia model. However, we encountered some nonpositive estimates for the correlations of the latent variables (factors) for both models. The model with the best fit without methodological problems was the externalizing behaviors model, but the results also supported the DSM-5 model. Overall, the results demonstrate that the German version of the CAPS-5 is a psychometrically sound measure.

Structural system reliability calculation using a probabilistic fault tree analysis method

NASA Technical Reports Server (NTRS)

Torng, T. Y.; Wu, Y.-T.; Millwater, H. R.

1992-01-01

The development of a new probabilistic fault tree analysis (PFTA) method for calculating structural system reliability is summarized. The proposed PFTA procedure includes: developing a fault tree to represent the complex structural system, constructing an approximation function for each bottom event, determining a dominant sampling sequence for all bottom events, and calculating the system reliability using an adaptive importance sampling method. PFTA is suitable for complicated structural problems that require computer-intensive computer calculations. A computer program has been developed to implement the PFTA.

[Reliability and construct validity of the OPD-CA axes structure and prerequisites for treatment].

PubMed

Weitkamp, Katharina; Wiegand-Grefe, Silke; Romer, Georg

2013-01-01

As an instrument to assess specific psychodynamic dimensions, the Operationalized Psychodynamic Diagnostics in Childhood and Adolescence (OPD-CA) is widely used in clinical care and psychotherapeutic training. However, the psychometric validation of its axes is partly still missing. The aim of this study was to test the reliability and construct validity of the axes structure and prerequisites of treatment. 171 children and adolescents (aged 4 to 21 years) with a diagnosed psychiatric disorder who began an analytic psychotherapy were additionally assessed with the OPD-CA by their therapists (n = 25) in the context of naturalistic care in private practice. Therapists were all qualified as analytic child and adolescent psychotherapists and underwent a standardized OPD-CA training. Results indicated conceptually meaningful factor structures for both axes tested. These factor structures predominantly followed the conceptually defined dimensions. Internal consistency was high for the axis structure, modest to low fort he axis prerequisites of treatment. Implications and recommendations for a future revision of the OPD-CA with particular respect of single items and their operationalization are discussed.

High-power 0.87-micron channel substrate planar lasers for spaceborne communications

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Stewart, T. R.; Gilbert, D. B.; Slavin, S. E.; Carlin, D. B.

1988-01-01

High-power single-mode channeled-substrate planar AlGaAs diode lasers are being developed for reliable high-power operation for use as sources in spaceborne optical communication systems. The CSP laser structure has been optimized for operation at an emission wavelength of 870 nm. Such devices have exhibited output powers in excess of 80 mW CW at an operating temperature of 80 C.

On the design and structural analysis of jet engine fan blade structures

NASA Astrophysics Data System (ADS)

Amoo, Leye M.

2013-07-01

Progress in the design and structural analysis of commercial jet engine fan blades is reviewed and presented. This article is motivated by the key role fan blades play in the performance of advanced gas turbine jet engines. The fundamentals of the associated physics are emphasized. Recent developments and advancements have led to an increase and improvement in fan blade structural durability, stability and reliability. This article is intended as a high level review of the fan blade environment and current state of structural design to aid further research in developing new and innovative fan blade technologies.

Nearest-neighbor guided evaluation of data reliability and its applications.

PubMed

Boongoen, Tossapon; Shen, Qiang

2010-12-01

The intuition of data reliability has recently been incorporated into the main stream of research on ordered weighted averaging (OWA) operators. Instead of relying on human-guided variables, the aggregation behavior is determined in accordance with the underlying characteristics of the data being aggregated. Data-oriented operators such as the dependent OWA (DOWA) utilize centralized data structures to generate reliable weights, however. Despite their simplicity, the approach taken by these operators neglects entirely any local data structure that represents a strong agreement or consensus. To address this issue, the cluster-based OWA (Clus-DOWA) operator has been proposed. It employs a cluster-based reliability measure that is effective to differentiate the accountability of different input arguments. Yet, its actual application is constrained by the high computational requirement. This paper presents a more efficient nearest-neighbor-based reliability assessment for which an expensive clustering process is not required. The proposed measure can be perceived as a stress function, from which the OWA weights and associated decision-support explanations can be generated. To illustrate the potential of this measure, it is applied to both the problem of information aggregation for alias detection and the problem of unsupervised feature selection (in which unreliable features are excluded from an actual learning process). Experimental results demonstrate that these techniques usually outperform their conventional state-of-the-art counterparts.

Examination of Anomalous World Experience: A Report on Reliability.

PubMed

Conerty, Joseph; Skodlar, Borut; Pienkos, Elizabeth; Zadravek, Tina; Byrom, Greg; Sass, Louis

2017-01-01

The EAWE (Examination of Anomalous World Experience) is a newly developed, semi-structured interview that aims to capture anomalies of subjectivity, common in schizophrenia spectrum disorders, that pertain to experiences of the lived world, including space, time, people, language, atmosphere, and certain existential attitudes. By contrast, previous empirical studies of subjective experience in schizophrenia have focused largely on disturbances in self-experience. To assess the reliability of the EAWE, including internal consistency and interrater reliability. In the course of developing the EAWE, two distinct studies were conducted, one in the United States and the other in Slovenia. Thirteen patients diagnosed with schizophrenia spectrum or mood disorders were recruited for the US study. Fifteen such patients were recruited for the Slovenian study. Two live interviewers conducted the EAWE in the US. The Slovenian interviews were completed by one live interviewer with a second rater reviewing audiorecordings of the interview. Internal consistency and interrater reliability were calculated independently for each study, utilizing Cronbach's α, Spearman's ρ, and Cohen's κ. Each study yielded high internal consistency (Cronbach's α >0.82) and high interrater reliability for total EAWE scores (ρ > 0.83; average κ values were at least 0.78 for each study, with EAWE domain-specific κ not lower than 0.73). The EAWE, containing world-oriented inquiries into anomalies in subjective experience, has adequate reliability for use in a clinical or research setting. © 2017 S. Karger AG, Basel.

An experimental investigation of fault tolerant software structures in an avionics application

NASA Technical Reports Server (NTRS)

Caglayan, Alper K.; Eckhardt, Dave E., Jr.

1989-01-01

The objective of this experimental investigation is to compare the functional performance and software reliability of competing fault tolerant software structures utilizing software diversity. In this experiment, three versions of the redundancy management software for a skewed sensor array have been developed using three diverse failure detection and isolation algorithms and incorporated into various N-version, recovery block and hybrid software structures. The empirical results show that, for maximum functional performance improvement in the selected application domain, the results of diverse algorithms should be voted before being processed by multiple versions without enforced diversity. Results also suggest that when the reliability gain with an N-version structure is modest, recovery block structures are more feasible since higher reliability can be obtained using an acceptance check with a modest reliability.

National audit of continence care: laying the foundation.

PubMed

Mian, Sarah; Wagg, Adrian; Irwin, Penny; Lowe, Derek; Potter, Jonathan; Pearson, Michael

2005-12-01

National audit provides a basis for establishing performance against national standards, benchmarking against other service providers and improving standards of care. For effective audit, clinical indicators are required that are valid, feasible to apply and reliable. This study describes the methods used to develop clinical indicators of continence care in preparation for a national audit. To describe the methods used to develop and test clinical indicators of continence care with regard to validity, feasibility and reliability. A multidisciplinary working group developed clinical indicators that measured the structure, process and outcome of care as well as case-mix variables. Literature searching, consensus workshops and a Delphi process were used to develop the indicators. The indicators were tested in 15 secondary care sites, 15 primary care sites and 15 long-term care settings. The process of development produced indicators that received a high degree of consensus within the Delphi process. Testing of the indicators demonstrated an internal reliability of 0.7 and an external reliability of 0.6. Data collection required significant investment in terms of staff time and training. The method used produced indicators that achieved a high degree of acceptance from health care professionals. The reliability of data collection was high for this audit and was similar to the level seen in other successful national audits. Data collection for the indicators was feasible to collect, however, issues of time and staffing were identified as limitations to such data collection. The study has described a systematic method for developing clinical indicators for national audit. The indicators proved robust and reliable in primary and secondary care as well as long-term care settings.

Specialty fibers for fiber optic sensor application

NASA Astrophysics Data System (ADS)

Bennett, K.; Koh, J.; Coon, J.; Chien, C. K.; Artuso, A.; Chen, X.; Nolan, D.; Li, M.-J.

2007-09-01

Over the last several years, Fiber Optic Sensor (FOS) applications have seen an increased acceptance in many areas including oil & gas production monitoring, gyroscopes, current sensors, structural sensing and monitoring, and aerospace applications. High level optical and mechanical reliability of optical fiber is necessary to guarantee reliable performance of FOS. In this paper, we review recent research and development activities on new specialty fibers. We discuss fiber design concepts and present both modeling and experimental results. The main approaches to enhancing fiber attributes include new index profile design and fiber coating modification.

Factor structure and psychometric properties of the trier inventory for chronic stress (TICS) in a representative german sample

PubMed Central

2012-01-01

Background Chronic stress results from an imbalance of personal traits, resources and the demands placed upon an individual by social and occupational situations. This chronic stress can be measured using the Trier Inventory for Chronic Stress (TICS). Aims of the present study are to test the factorial structure of the TICS, report its psychometric properties, and evaluate the influence of gender and age on chronic stress. Methods The TICS was answered by N = 2,339 healthy participants aged 14 to 99. The sample was selected by random-route sampling. Exploratory factor analyses with Oblimin-rotated Principal Axis extraction were calculated. Confirmatory factor analyses applying Robust Maximum Likelihood estimations (MLM) tested model fit and configural invariance as well as the measurement invariance for gender and age. Reliability estimations and effect sizes are reported. Results In the exploratory factor analyses, both a two-factor and a nine-factor model emerged. Confirmatory factor analyses resulted in acceptable model fit (RMSEA), with model comparison fit statistics corroborating the superiority of the nine-factor model. Most factors were moderately to highly intercorrelated. Reliabilities were good to very good. Measurement invariance tests gave evidence for differential effects of gender and age on the factor structure. Furthermore, women and younger individuals, especially those aged 35 to 44, tended to report more chronic stress than men and older individuals. Conclusions The proposed nine-factor structure could be factorially validated, results in good scale reliability, and heuristically can be grouped by two higher-order factors: "High Demands" and "Lack of Satisfaction". Age and gender represent differentiable and meaningful contributors to the perception of chronic stress. PMID:22463771

Functional Design of Highly Robust and Flexible Thin-Film Encapsulation Composed of Quasi-Perfect Sublayers for Transparent, Flexible Displays.

PubMed

Kwon, Jeong Hyun; Jeon, Yongmin; Choi, Seungyeop; Park, Jeong Woo; Kim, Hyuncheol; Choi, Kyung Cheol

2017-12-20

In this study, a structurally and materially designed thin-film encapsulation is proposed to guarantee the reliability of transparent, flexible displays by significantly improving their barrier properties, mechanical stability, and environmental reliability, all of which are essential for organic light-emitting diode (OLED) encapsulation. We fabricated a bioinspired, nacre-like ZnO/Al 2 O 3 /MgO laminate structure (ZAM) using atomic layer deposition for the microcrack toughening effect. The ZAM film was formed with intentional voids and defects through the formation of a quasi-perfect sublayer, rather than the simple fabrication of nanolaminate structures. The 240 nm thick ZAM-based multibarrier (ZAM-TFE) with a compressively strained organic layer demonstrated an optical transmittance of 91.35% in the visible range, an extremely low water vapor transmission rate of 2.06 × 10 -6 g/m 2 /day, a mechanical stability enduring a strain close to 1%, and a residual stress close to 0, showing significant improvement of key TFE properties in comparison to an Al 2 O 3 -based multibarrier. In addition, ZAM-TFE demonstrated superior environmental resistance without degradation of barrier properties in a severe environment of 85 °C and 90% relative humidity (RH). Thus, our structurally and materially designed ZAM film has been well optimized in terms of its applicability as a gas diffusion barrier as well as in terms of its mechanical and environmental reliability. Finally, we confirmed the feasibility of the ZAM-TFE through application in OLEDs. The low-temperature ZAM-TFE technology showed great potential to provide a highly robust and flexible TFE of TFOLEDs.

Training and quality assurance with the Structured Clinical Interview for DSM-IV (SCID-I/P).

PubMed

Ventura, J; Liberman, R P; Green, M F; Shaner, A; Mintz, J

1998-06-15

Accuracy in psychiatric diagnosis is critical for evaluating the suitability of the subjects for entry into research protocols and for establishing comparability of findings across study sites. However, training programs in the use of diagnostic instruments for research projects are not well systematized. Furthermore, little information has been published on the maintenance of interrater reliability of diagnostic assessments. At the UCLA Research Center for Major Mental Illnesses, a Training and Quality Assurance Program for SCID interviewers was used to evaluate interrater reliability and diagnostic accuracy. Although clinically experienced interviewers achieved better interrater reliability and overall diagnostic accuracy than neophyte interviewers, both groups were able to achieve and maintain high levels of interrater reliability, diagnostic accuracy, and interviewer skill. At the first quality assurance check after training, there were no significant differences between experienced and neophyte interviewers in interrater reliability or diagnostic accuracy. Standardization of training and quality assurance procedures within and across research projects may make research findings from study sites more comparable.

Design and Analysis of Wind Turbine Rotors Using Hinged Structures and Rods

NASA Astrophysics Data System (ADS)

Lu, Hongya; Zeng, Pan; Lei, Liping

2018-03-01

Light weight and high stiffness are key design factors in ensuring cost effectiveness and reliability of wind turbines, especially for the inboard region of the rotor blades. In this study, several novel designs were developed to improve the mechanical performance of the rotor. Experiments were performed on an isolated blade incorporating the new features of a hinged structure and rods. The results validated the effectiveness of these features at alleviating the root-bending moment of the blade under varying wind loads and enhancing the stiffness of the blade. A numerical investigation was carried out to further examine the bending moment distribution, shear and axial force, and rod tension of these novel rotor designs under uniform loads. Longitudinal geometrical variations of the blade were considered in the model. Results showed that two designs realized a favorable bending moment distribution and improved the modal frequencies of the edgewise modes: bisymmetrical rods on a single-hinged structure and interveined symmetrical rods on a cantilevered structure. However, these designs have different deformation mechanisms. In addition, the first group of edgewise modal frequencies of these two designs were improved compared with the traditional rotor design. Their potential values in the application to the design of a lightweight, high-stiffness, and reliable wind turbine rotor were discussed.

CPHmodels-3.0--remote homology modeling using structure-guided sequence profiles.

PubMed

Nielsen, Morten; Lundegaard, Claus; Lund, Ole; Petersen, Thomas Nordahl

2010-07-01

CPHmodels-3.0 is a web server predicting protein 3D structure by use of single template homology modeling. The server employs a hybrid of the scoring functions of CPHmodels-2.0 and a novel remote homology-modeling algorithm. A query sequence is first attempted modeled using the fast CPHmodels-2.0 profile-profile scoring function suitable for close homology modeling. The new computational costly remote homology-modeling algorithm is only engaged provided that no suitable PDB template is identified in the initial search. CPHmodels-3.0 was benchmarked in the CASP8 competition and produced models for 94% of the targets (117 out of 128), 74% were predicted as high reliability models (87 out of 117). These achieved an average RMSD of 4.6 A when superimposed to the 3D structure. The remaining 26% low reliably models (30 out of 117) could superimpose to the true 3D structure with an average RMSD of 9.3 A. These performance values place the CPHmodels-3.0 method in the group of high performing 3D prediction tools. Beside its accuracy, one of the important features of the method is its speed. For most queries, the response time of the server is <20 min. The web server is available at http://www.cbs.dtu.dk/services/CPHmodels/.

Study of structural reliability of existing concrete structures

NASA Astrophysics Data System (ADS)

Druķis, P.; Gaile, L.; Valtere, K.; Pakrastiņš, L.; Goremikins, V.

2017-10-01

Structural reliability of buildings has become an important issue after the collapse of a shopping center in Riga 21.11.2013, caused the death of 54 people. The reliability of a building is the practice of designing, constructing, operating, maintaining and removing buildings in ways that ensure maintained health, ward suffered injuries or death due to use of the building. Evaluation and improvement of existing buildings is becoming more and more important. For a large part of existing buildings, the design life has been reached or will be reached in the near future. The structures of these buildings need to be reassessed in order to find out whether the safety requirements are met. The safety requirements provided by the Eurocodes are a starting point for the assessment of safety. However, it would be uneconomical to require all existing buildings and structures to comply fully with these new codes and corresponding safety levels, therefore the assessment of existing buildings differs with each design situation. This case study describes the simple and practical procedure of determination of minimal reliability index β of existing concrete structures designed by different codes than Eurocodes and allows to reassess the actual reliability level of different structural elements of existing buildings under design load.

Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

NASA Astrophysics Data System (ADS)

Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

2014-07-01

The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

Reliability Modeling of Double Beam Bridge Crane

NASA Astrophysics Data System (ADS)

Han, Zhu; Tong, Yifei; Luan, Jiahui; Xiangdong, Li

2018-05-01

This paper briefly described the structure of double beam bridge crane and the basic parameters of double beam bridge crane are defined. According to the structure and system division of double beam bridge crane, the reliability architecture of double beam bridge crane system is proposed, and the reliability mathematical model is constructed.

A millimeter-wave tunneladder TWT

NASA Technical Reports Server (NTRS)

Wilson, D.

1988-01-01

A millimeter-wave traveling wave tube (TWT) was developed using a dispersive, high-impedance forward wave interaction structure based on a ladder, with non-space-harmonic interaction, for a tube with high gain per inch and high efficiency. The 'TunneLadder' interaction structure combines ladder properties modified to accommodate Pierce gun beam optics in a radially magnetized PM focusing structure. The development involved the fabrication of chemically milled, shaped ladders diffusion brazed to diamond cubes which are in turn active diffusion brazed to each ridge of a doubly ridged waveguide. Cold-test data, representing the (omega)(beta) and and impedance characteristics of the modified ladder circuit, were used in small and large-signal computer programs to predict TWT gain and efficiency. The structural design emphasizes ruggedness and reliability. Actual data from tested tubes verify the predicted performance while providing broader bandwidth than expected.

The influence of various test plans on mission reliability. [for Shuttle Spacelab payloads

NASA Technical Reports Server (NTRS)

Stahle, C. V.; Gongloff, H. R.; Young, J. P.; Keegan, W. B.

1977-01-01

Methods have been developed for the evaluation of cost effective vibroacoustic test plans for Shuttle Spacelab payloads. The shock and vibration environments of components have been statistically represented, and statistical decision theory has been used to evaluate the cost effectiveness of five basic test plans with structural test options for two of the plans. Component, subassembly, and payload testing have been performed for each plan along with calculations of optimum test levels and expected costs. The tests have been ranked according to both minimizing expected project costs and vibroacoustic reliability. It was found that optimum costs may vary up to $6 million with the lowest plan eliminating component testing and maintaining flight vibration reliability via subassembly tests at high acoustic levels.

The Four-Dimensional Symptom Questionnaire (4DSQ) in the general population: scale structure, reliability, measurement invariance and normative data: a cross-sectional survey.

PubMed

Terluin, Berend; Smits, Niels; Brouwers, Evelien P M; de Vet, Henrica C W

2016-09-15

The Four-Dimensional Symptom Questionnaire (4DSQ) is a self-report questionnaire measuring distress, depression, anxiety and somatization with separate scales. The 4DSQ has extensively been validated in clinical samples, especially from primary care settings. Information about measurement properties and normative data in the general population was lacking. In a Dutch general population sample we examined the 4DSQ scales' structure, the scales' reliability and measurement invariance with respect to gender, age and education, the scales' score distributions across demographic categories, and normative data. 4DSQ data were collected in a representative Dutch Internet panel. Confirmatory factor analysis was used to examine the scales' structure. Reliability was examined by Cronbach's alpha, and coefficients omega-total and omega-hierarchical. Differential item functioning (DIF) analysis was used to evaluate measurement invariance across gender, age and education. The total response rate was 82.4 % (n = 5273/6399). The depression scale proved to be unidimensional. The other scales were best represented as bifactor models consisting of a large general factor and one or more smaller specific factors. The general factors accounted for more than 95 % of the reliable variance of the scales. Reliability was high (≥0.85) by all estimates. The distress-, depression- and anxiety scales were invariant across gender, age and education. The somatization scale demonstrated some lack of measurement invariance as a result of decreased thresholds for some of the items in young people (16-24 years) and increased thresholds in elderly people (65+ years). The somatization scale was invariant regarding gender and education. The 4DSQ scores varied significantly across demographic categories, but the explained variance was small (<6 %). Normative data were generated for gender and age categories. Approximately 17 % of the participants scored above average on de distress scale, whereas 12 % scored above average on de somatization scale. Percentages of people scoring high enough on depression or anxiety as to suspect the presence of depressive or anxiety disorder were 4.1 and 2.5 respectively. Evidence supports reliability and measurement invariance of the 4DSQ in the general Dutch population. The normative data provided in this study can be used to compare a subject's 4DSQ scores with a general population reference group.

Psychometric evaluation of a motor control test battery of the craniofacial region.

PubMed

von Piekartz, H; Stotz, E; Both, A; Bahn, G; Armijo-Olivo, S; Ballenberger, N

2017-12-01

The primary objective of this study was to determine the structural and known-group validity as well as the inter-rater reliability of a test battery to evaluate the motor control of the craniofacial region. Seventy volunteers without TMD and 25 subjects with TMD (Axes I) per the DC/TMD were asked to execute a test battery consisting of eight tests. The tests were video-taped in the same sequence in a standardised manner. Two experienced physical therapists participated in this study as blinded assessors. We used exploratory factor analysis to identify the underlying component structure of the eight tests. Internal consistency (Cronbach's α), inter-rater reliability (intra-class correlation coefficient) and construct validity (ie, hypothesis testing-known-group validity) (receiver operating curves) were also explored for the test battery. The structural validity showed the presence of one factor underlying the construct of the test battery. The internal consistency was excellent (0.90) as well as the inter-rater reliability. All values of reliability were close to 0.9 or above indicating very high inter-rater reliability. The area under the curve (AUC) was 0.93 for rater 1 and 0.94 for rater two, respectively, indicating excellent discrimination between subjects with TMD and healthy controls. The results of the present study support the psychometric properties of test battery to measure motor control of the craniofacial region when evaluated through videotaping. This test battery could be used to differentiate between healthy subjects and subjects with musculoskeletal impairments in the cervical and oro-facial regions. In addition, this test battery could be used to assess the effectiveness of management strategies in the craniofacial region. © 2017 John Wiley & Sons Ltd.

High-Temperature Strain Sensing for Aerospace Applications

NASA Technical Reports Server (NTRS)

Piazza, Anthony; Richards, Lance W.; Hudson, Larry D.

2008-01-01

Thermal protection systems (TPS) and hot structures are utilizing advanced materials that operate at temperatures that exceed abilities to measure structural performance. Robust strain sensors that operate accurately and reliably beyond 1800 F are needed but do not exist. These shortcomings hinder the ability to validate analysis and modeling techniques and hinders the ability to optimize structural designs. This presentation examines high-temperature strain sensing for aerospace applications and, more specifically, seeks to provide strain data for validating finite element models and thermal-structural analyses. Efforts have been made to develop sensor attachment techniques for relevant structural materials at the small test specimen level and to perform laboratory tests to characterize sensor and generate corrections to apply to indicated strains. Areas highlighted in this presentation include sensors, sensor attachment techniques, laboratory evaluation/characterization of strain measurement, and sensor use in large-scale structures.

Psychometric properties of the Internalized Stigma of Mental Illness scale adapted for people who use psychoactive substances.

PubMed

Gallo, Verónica Del Valle; Burrone, María Soledad; Fernandez, Alicia Ruth; Boyd, Jennifer E; Abeldaño, Roberto Ariel

2017-01-01

People who consume psychoactive substances may experience situations of social stigma on the part of the society in general, and also situations of internalized-stigma derived from their own consumption of substances. The Internalized Stigma of Mental Illness (ISMI) scale has been shown to be valid and reliable to evaluate the internalized-stigma in people with severe mental disorders, but in Argentina there is no a Spanish version of this scale for use with people who use psychoactive substances. The objective of this work was to evaluate the psychometric properties of the Spanish version of the Internalized Stigma of Mental Illness instrument adapted for people who use psychoactive substances. The work was carried out on a sample of 200 patients older than 18 years under treatment of rehabilitation by consumption of psychoactive substances in a public institution of the city of Córdoba (Argentina) between the years 2014 and 2016. The instrument used was the Internalized Stigma of Mental Illness (ISMI) previously adapted for use in these groups of patients. It was determined the reliability of the scale through Cronbach's coefficients α and factorial structure was analyzed through an exploratory factor analysis. The obtained coefficients showed a high reliability, while in the factorial structure emerged the 4 theoretical dimensions described by Ritsher, namely: social isolation, perceived discrimination, alienation and stereotyping. It is concluded that the scale adapted for people who use psychoactive substances is reliable and with an adequate factorial structure.

Advanced Stirling Convertor Testing at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Poriti, Sal

2010-01-01

The NASA Glenn Research Center (GRC) has been testing high-efficiency free-piston Stirling convertors for potential use in radioisotope power systems (RPSs) since 1999. The current effort is in support of the Advanced Stirling Radioisotope Generator (ASRG), which is being developed by the U.S. Department of Energy (DOE), Lockheed Martin Space Systems Company (LMSSC), Sunpower, Inc., and the NASA GRC. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs) to convert thermal energy from a radioisotope heat source into electricity. As reliability is paramount to a RPS capable of providing spacecraft power for potential multi-year missions, GRC provides direct technology support to the ASRG flight project in the areas of reliability, convertor and generator testing, high-temperature materials, structures, modeling and analysis, organics, structural dynamics, electromagnetic interference (EMI), and permanent magnets to reduce risk and enhance reliability of the convertor as this technology transitions toward flight status. Convertor and generator testing is carried out in short- and long-duration tests designed to characterize convertor performance when subjected to environments intended to simulate launch and space conditions. Long duration testing is intended to baseline performance and observe any performance degradation over the life of the test. Testing involves developing support hardware that enables 24/7 unattended operation and data collection. GRC currently has 14 Stirling convertors under unattended extended operation testing, including two operating in the ASRG Engineering Unit (ASRG-EU). Test data and high-temperature support hardware are discussed for ongoing and future ASC tests with emphasis on the ASC-E and ASC-E2.

Short forms of the Schedule for Nonadaptive and Adaptive Personality (SNAP) for self- and collateral ratings: development, reliability, and validity.

PubMed

Harlan, E; Clark, L A

1999-06-01

Researchers and clinicians alike increasingly seek brief, reliable, and valid measures to obtain personality trait ratings from both selves and peers. We report the development of a paragraph-descriptor short form of a full-length personality assessment instrument, the Schedule for Nonadaptive and Adaptive Personality (SNAP) with both self- and other versions. Reliability and validity data were collected on a sample of 294 college students, from 90 of whom we also obtained parental ratings of their personality. Internal consistency reliability was good in both self- and parent data. The factorial structures of the self-report short and long forms were very similar. Convergence between parental ratings was moderately high. Self-parent convergence was variable, with lower agreement on scales assessing subjective distress than those assessing more observable behaviors; it also was stronger for higher order factors than for scales.

Brazilian Portuguese version of the Revised Fibromyalgia Impact Questionnaire (FIQR-Br): cross-cultural validation, reliability, and construct and structural validation.

PubMed

Lupi, Jaqueline Basilio; Carvalho de Abreu, Daniela Cristina; Ferreira, Mariana Candido; Oliveira, Renê Donizeti Ribeiro de; Chaves, Thais Cristina

2017-08-01

This study aimed to culturally adapt and validate the Revised Fibromyalgia Impact Questionnaire (FIQR) to Brazilian Portuguese, by the use of analysis of internal consistency, reliability, and construct and structural validity. A total of 100 female patients with fibromyalgia participated in the validation process of the Brazilian Portuguese version of the FIQR (FIQR-Br).The intraclass correlation coefficient (ICC) was used for statistical analysis of reliability (test-retest), Cronbach's alpha for internal consistency, Pearson's rank correlation for construct validity, and confirmatory factor analysis (CFA) for structural validity. It was verified excellent levels of reliability, with ICC greater than 0.75 for all questions and domains of the FIQR-Br. For internal consistency, alpha values greater than 0.70 for the items and domains of the questionnaire were observed. Moderate (0.40 < r < 0.70) and strong (r > 0.70) correlations were observed for the scores of domains and total score between the FIQR-Br and FIQ-Br. The structure of the three domains of the FIQR-Br was confirmed by CFA. The results of this study suggest that that the FIQR-Br is a reliable and valid instrument for assessing fibromyalgia-related impact, and supports its use in clinical settings and research. The structure of the three domains of the FIQR-Br was also confirmed. Implications for Rehabilitation Fibromyalgia is a chronic musculoskeletal disorder characterized by widespread and diffuse pain, fatigue, sleep disturbances, and depression. The disease significantly impairs patients' quality of life and can be highly disabling. To be used in multicenter research efforts, the Revised Fibromyalgia Impact Questionnaire (FIQR) must be cross-culturally validated and psychometrically tested. This paper will make available a new version of the FIQR-Br since another version already exists, but there are concerns about its measurement properties. The availability of an instrument adapted to and validated for Brazilian Portuguese may make it possible to reliably verify the effects of rehabilitation programs on disability from fibromyalgia. The FIQR-Br showed results comparable with other versions of the FIQR in other languages, thereby enabling comparison of effects of rehabilitation interventions on disability from fibromyalgia conducted in Brazil with results of studies carried out in other parts of the world.

New materials for high temperature turbines; ONERA's DS composites confronted with blade problems

NASA Technical Reports Server (NTRS)

Bibring, H.

1977-01-01

ONERA's refractory DS composites were cited as materials required for use in advanced aircraft turbines, operating at high temperatures. These materials were found to be reliable in the construction of turbine blades. Requirements for a blade material in aircraft turbines operating at higher temperatures were compared with the actual performance as found in COTAC DS composite testing. The structure and properties of the more fully developed 74 and 741 types were specified. High temperature structural stability, impact of thermal and mechanical fatigue, oxidation resistance and coating capability were thoroughly evaluated. The problem of cooling passages in DS eutectic blades is also outlined.

An antisymmetric cell structure for high-performance zinc bromine flow battery

NASA Astrophysics Data System (ADS)

Kim, Yongbeom; Jeon, Joonhyeon

2017-12-01

Zinc-bromine flow batteries (ZBBs) remain a problem of designing a cell with high coulombic efficiency and stability. This problem is caused intrinsically by different phase transition in each side of the half-cells during charge-discharge process. This paper describes a ZBB with an antisymmetric cell structure, which uses anode and cathode with different surface morphologies, for high-discharge capacity and reliability. The structure of the antisymmetric ZBB cell contains a carbon-surface electrode and a carbon-volume electrode in zinc and bromine half cells, respectively. To demonstrate the effectiveness of this proposed ZBB cell structure, Cyclic Voltammetry measurement is performed on a graphite foil and a carbon felt which are used as the surface and electrodes. Charge and discharge cyclic operations are also carried out with symmetric and antisymmetric ZBB cells combined with the two electrode types. Experimental results show that the arrangement of antisymmetric cell structure in ZBB provides a solution to the high performance and durability.

A reliability analysis framework with Monte Carlo simulation for weld structure of crane's beam

NASA Astrophysics Data System (ADS)

Wang, Kefei; Xu, Hongwei; Qu, Fuzheng; Wang, Xin; Shi, Yanjun

2018-04-01

The reliability of the crane product in engineering is the core competitiveness of the product. This paper used Monte Carlo method analyzed the reliability of the weld metal structure of the bridge crane whose limit state function is mathematical expression. Then we obtained the minimum reliable welding feet height value for the welds between cover plate and web plate on main beam in different coefficients of variation. This paper provides a new idea and reference for the growth of the inherent reliability of crane.

Assessment of concrete damage and strength degradation caused by reinforcement corrosion

NASA Astrophysics Data System (ADS)

Nepal, Jaya; Chen, Hua-Peng

2015-07-01

Structural performance deterioration of reinforced concrete structures has been extensively investigated, but very limited studies have been carried out to investigate the effect of reinforcement corrosion on time-dependent reliability with consideration of the influence of mechanical characteristics of the bond interface due to corrosion. This paper deals with how corrosion in reinforcement creates different types of defects in concrete structure and how they are responsible for the structural capacity deterioration of corrosion affected reinforced concrete structures during their service life. Cracking in cover concrete due to reinforcement corrosion is investigated by using rebar-concrete model and realistic concrete properties. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution due to reinforcement corrosion, which is examined by the experimental data available. The time-dependent reliability analysis is undertaken to calculate the life time structural reliability of corrosion damaged concrete structures by stochastic deterioration modelling of reinforced concrete. The results from the numerical example show that the proposed approach is capable of evaluating the damage caused by reinforcement corrosion and also predicting the structural reliability of concrete structures during their lifecycle.

Compliance and High Reliability in a Complex Healthcare Organization.

PubMed

Simon, Maxine dellaBadia

2018-01-01

When considering the impact of regulation on healthcare, visualize a spider's web. The spider weaves sections together to create the whole, with each fiber adding to the structure to support its success or lead to its failure. Each section is dependent on the others, and all must be aligned to maintain the structure. Outside forces can cause a shift in the web's fragile equilibrium.The interdependence of the sections of the spider's web is similar to the way hospital departments and services work together. An organization's structure must be shaped to support its mission and vision. At the same time, the business of healthcare requires the development and achievement of operational objectives and financial performance goals. Establishing a culture that is flexible enough to permit creativity, provide resiliency, and manage complexity as the organization grows is fundamental to success. An organization must address each of these factors while maintaining stability, carrying out its mission, and fostering improvement.Nature's order maintains the spider's web. Likewise, regulation can strengthen healthcare organizations by initiating disruptive changes that can support efforts to achieve and sustain high reliability in the delivery of care. To that end, leadership must be willing to provide the necessary vision and resources.

Simultaneous control of magnetic topologies for reconfigurable vortex arrays

DOE PAGES

Im, Mi-Young; Fischer, Peter; Han, Hee-Sung; ...

2017-02-10

The topological spin textures in magnetic vortices in confined magnetic elements offer a platform for understanding the fundamental physics of nanoscale spin behavior and the potential of harnessing their unique spin structures for advanced magnetic technologies. For magnetic vortices to be practical, an effective reconfigurability of the two topologies of magnetic vortices, that is, the circularity and the polarity, is an essential prerequisite. The reconfiguration issue is highly relevant to the question of whether both circularity and polarity are reliably and efficiently controllable. In this work, we report the first direct observation of simultaneous control of both circularity and polaritymore » by the sole application of an in-plane magnetic field to arrays of asymmetrically shaped permalloy disks. Our investigation demonstrates that a high degree of reliability for control of both topologies can be achieved by tailoring the geometry of the disk arrays. We also propose a new approach to control the vortex structures by manipulating the effect of the stray field on the dynamics of vortex creation. The current study is expected to facilitate complete and effective reconfiguration of magnetic vortex structures, thereby enhancing the prospects for technological applications of magnetic vortices.« less

Simultaneous control of magnetic topologies for reconfigurable vortex arrays

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

Im, Mi-Young; Fischer, Peter; Han, Hee-Sung

The topological spin textures in magnetic vortices in confined magnetic elements offer a platform for understanding the fundamental physics of nanoscale spin behavior and the potential of harnessing their unique spin structures for advanced magnetic technologies. For magnetic vortices to be practical, an effective reconfigurability of the two topologies of magnetic vortices, that is, the circularity and the polarity, is an essential prerequisite. The reconfiguration issue is highly relevant to the question of whether both circularity and polarity are reliably and efficiently controllable. In this work, we report the first direct observation of simultaneous control of both circularity and polaritymore » by the sole application of an in-plane magnetic field to arrays of asymmetrically shaped permalloy disks. Our investigation demonstrates that a high degree of reliability for control of both topologies can be achieved by tailoring the geometry of the disk arrays. We also propose a new approach to control the vortex structures by manipulating the effect of the stray field on the dynamics of vortex creation. The current study is expected to facilitate complete and effective reconfiguration of magnetic vortex structures, thereby enhancing the prospects for technological applications of magnetic vortices.« less

Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes

NASA Astrophysics Data System (ADS)

Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

2016-08-01

In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process.

Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes

PubMed Central

Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

2016-01-01

In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process. PMID:27553755

Cross-cultural validation of the Child Abuse Potential Inventory in Greece: a preliminary study.

PubMed

Diareme, S; Tsiantis, J; Tsitoura, S

1997-11-01

The aim of this study was first, to provide preliminary findings on the reliability and validity of a Greek translation of the CAP Inventory (Milner, 1986), and second, to examine whether there were any differences between Greek and American scores in the CAP Inventory. A convenience sample of 320 Greek parents was recruited from the outpatient unit of a large Children's Hospital in Athens, Greece. Greek scores were compared with American scores taken from the test manual. Internal consistency reliability was high for the Abuse scale (.91), two factor scales (Distress = .93 and Rigidity = .86) and one Validity scale (Inconsistency = .80). The Greek version of the Abuse scale had a similar factorial structure with the American version. Also, 78.1% of Greek parents were classified correctly as nonabusive by the Abuse scale. This rate was increased to 88.6% when invalid questionnaires were excluded from the sample. Comparisons between Greek and American mean scale scores indicated that Greek scores were significantly higher than American scores in all but one scale. Greeks had significantly lower scores than Americans in the Problems with Child and Self scale. Current findings including the high reliability, relatively high correct classification rates and factorial structure of the Greek Abuse scale are promising and support the idea of continuation of research for the development and validation of the Greek CAP Inventory. The difference between Greek and American scores in particular indicates the need for adjustment of cut off scores in the Greek scale.

Reliability-based design optimization of reinforced concrete structures including soil-structure interaction using a discrete gravitational search algorithm and a proposed metamodel

NASA Astrophysics Data System (ADS)

Khatibinia, M.; Salajegheh, E.; Salajegheh, J.; Fadaee, M. J.

2013-10-01

A new discrete gravitational search algorithm (DGSA) and a metamodelling framework are introduced for reliability-based design optimization (RBDO) of reinforced concrete structures. The RBDO of structures with soil-structure interaction (SSI) effects is investigated in accordance with performance-based design. The proposed DGSA is based on the standard gravitational search algorithm (GSA) to optimize the structural cost under deterministic and probabilistic constraints. The Monte-Carlo simulation (MCS) method is considered as the most reliable method for estimating the probabilities of reliability. In order to reduce the computational time of MCS, the proposed metamodelling framework is employed to predict the responses of the SSI system in the RBDO procedure. The metamodel consists of a weighted least squares support vector machine (WLS-SVM) and a wavelet kernel function, which is called WWLS-SVM. Numerical results demonstrate the efficiency and computational advantages of DGSA and the proposed metamodel for RBDO of reinforced concrete structures.

Psychometric evaluation of an inpatient consumer survey measuring satisfaction with psychiatric care.

PubMed

Ortiz, Glorimar; Schacht, Lucille

2012-01-01

Measurement of consumers' satisfaction in psychiatric settings is important because it has been correlated with improved clinical outcomes and administrative measures of high-quality care. These consumer satisfaction measurements are actively used as performance measures required by the accreditation process and for quality improvement activities. Our objectives were (i) to re-evaluate, through exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), the structure of an instrument intended to measure consumers' satisfaction with care in psychiatric settings and (ii) to examine and publish the psychometric characteristics, validity and reliability, of the Inpatient Consumer Survey (ICS). To psychometrically test the structure of the ICS, 34 878 survey results, submitted by 90 psychiatric hospitals in 2008, were extracted from the Behavioral Healthcare Performance Measurement System (BHPMS). Basic descriptive item-response and correlation analyses were performed for total surveys. Two datasets were randomly created for analysis. A random sample of 8229 survey results was used for EFA. Another random sample of 8261 consumer survey results was used for CFA. This same sample was used to perform validity and reliability analyses. The item-response analysis showed that the mean range for a disagree/agree five-point scale was 3.10-3.94. Correlation analysis showed a strong relationship between items. Six domains (dignity, rights, environment, empowerment, participation, and outcome) with internal reliabilities between good to moderate (0.87-0.73) were shown to be related to overall care satisfaction. Overall reliability for the instrument was excellent (0.94). Results from CFA provided support for the domains structure of the ICS proposed through EFA. The overall findings from this study provide evidence that the ICS is a reliable measure of consumer satisfaction in psychiatric inpatient settings. The analysis has shown the ICS to provide valid and reliable results and to focus on the specific concerns of consumers of psychiatric inpatient care. Scores by item indicate that opportunity for improvement exists across healthcare organizations.

Psychometric evaluation of the Chinese version of the fear of intimacy with helping professionals scale

PubMed Central

Chan, Kin Sun

2018-01-01

Objectives This study aimed to evaluate the internal consistency, reliability, convergent validity, known-group comparisons, and structural validity of the Chinese version of Fear of Intimacy with Helping Professionals (C–FIS–HP) scale in Macau. Methods A cross-sectional design was used on a sample of 593 older people in 6 health centers. We used Chinese version of Exercise of Self-Care Agency Scale (C-ESCAS) and Morisky 4-item medication adherence scale to evaluate self-care actions and medication adherence. The internal consistency and reliability of C–FIS–HP were analyzed using the Spearman-Brown split-half reliability, Cronbach’s alpha, and test–retest reliability. Convergent validity was tested the construct of C–FIS–HP and self-care actions. Known-group comparisons differentiated predefined groups in an expected direction. Two separated samples were used to test the structural validity. An exploratory factor analysis (EFA) tested the factor structure of C–FISHP using the principal axis factoring. A confirmatory factor analysis (CFA) was further conducted to confirm the factor structure constructed in the prior EFA. Results The C–FIS–HP had a Spearman-Brown split-half coefficient, Cronbach’s alpha, and intraclass correlation coefficient of 0.96, 0.93, and 0.96, respectively. Convergent validity was satisfactory with significantly correlations between the C-FIS-HP and C-ESCAS. C–FIS–HP to differentiate the differences between high-, moderate-, and low- medication adherence groups. EFA demonstrated a two-factor structure among 297 older people. A first-order CFA was performed to confirm the construct dimensionality of C–FIS–HP with satisfactory fit indices (NFI = 0.92; IFI = 0.95; TLI = 0.94; CFI = 0.95 and RMSEA = 0.07) among 296 older people. Conclusions C–FIS–HP is a reliable and valid test for assessing helping relationships in older Chinese people. Health professionals can use C–FIS–HP as a clinical tool to assess the comfort level of patients in a helping relationship, and use this information to develop culturally sensitive therapeutic interventions and treatment plans. Further studies need to be conducted concerning the different psychometric properties, as well as the application of C–FIS–HP in various regions. PMID:29795563

The reliability paradox: Why robust cognitive tasks do not produce reliable individual differences.

PubMed

Hedge, Craig; Powell, Georgina; Sumner, Petroc

2018-06-01

Individual differences in cognitive paradigms are increasingly employed to relate cognition to brain structure, chemistry, and function. However, such efforts are often unfruitful, even with the most well established tasks. Here we offer an explanation for failures in the application of robust cognitive paradigms to the study of individual differences. Experimental effects become well established - and thus those tasks become popular - when between-subject variability is low. However, low between-subject variability causes low reliability for individual differences, destroying replicable correlations with other factors and potentially undermining published conclusions drawn from correlational relationships. Though these statistical issues have a long history in psychology, they are widely overlooked in cognitive psychology and neuroscience today. In three studies, we assessed test-retest reliability of seven classic tasks: Eriksen Flanker, Stroop, stop-signal, go/no-go, Posner cueing, Navon, and Spatial-Numerical Association of Response Code (SNARC). Reliabilities ranged from 0 to .82, being surprisingly low for most tasks given their common use. As we predicted, this emerged from low variance between individuals rather than high measurement variance. In other words, the very reason such tasks produce robust and easily replicable experimental effects - low between-participant variability - makes their use as correlational tools problematic. We demonstrate that taking such reliability estimates into account has the potential to qualitatively change theoretical conclusions. The implications of our findings are that well-established approaches in experimental psychology and neuropsychology may not directly translate to the study of individual differences in brain structure, chemistry, and function, and alternative metrics may be required.

The reliability and validity study of the Kinesthetic and Visual Imagery Questionnaire in individuals with Multiple Sclerosis

PubMed Central

Tabrizi, Yousef Moghadas; Zangiabadi, Nasser; Mazhari, Shahrzad; Zolala, Farzaneh

2013-01-01

Objective Motor imagery (MI) has been recently considered as an adjunct to physical rehabilitation in patients with multiple sclerosis (MS). It is necessary to assess MI abilities and benefits in patients with MS by using a reliable tool. The Kinesthetic and Visual Imagery Questionnaire (KVIQ) was recently developed to assess MI ability in patients with stroke and other disabilities. Considering the different underlying pathologies, the present study aimed to examine the validity and reliability of the KVIQ in MS patients. Method Fifteen MS patients were assessed using the KVIQ in 2 sessions (5-14days apart) by the same examiner. In the second session, the participants also completed a revised MI questionnaire (MIQ-R) as the gold standard. Intra-class correlation coefficients (ICCs) were measured to determine test-retest reliability. Spearman's correlation analysis was performed to assess concurrent validity with the MIQ-R. Furthermore, the internal consistency (Cronbach's alpha) and factorial structure of the KVIQ were studied. Results The test-retest reliability for the KVIQ was good (ICCs: total KVIQ=0.89, visual KVIQ=0.85, and kinesthetic KVIQ=0.93), and the concurrent validity between the KVIQ and MIQ-R was good (r=0.79). The KVIQ had good internal consistency, with high Cronbach's alpha (alpha=0.84). Factorial analysis showed the bi-factorial structure of the KVIQ, which was explained by visual=57.6% and kinesthetic=32.4%. Conclusions The results of the present study revealed that the KVIQ is a valid and reliable tool for assessing MI in MS patients. PMID:24271091

The reliability and validity study of the Kinesthetic and Visual Imagery Questionnaire in individuals with multiple sclerosis.

PubMed

Tabrizi, Yousef Moghadas; Zangiabadi, Nasser; Mazhari, Shahrzad; Zolala, Farzaneh

2013-01-01

Motor imagery (MI) has been recently considered as an adjunct to physical rehabilitation in patients with multiple sclerosis (MS). It is necessary to assess MI abilities and benefits in patients with MS by using a reliable tool. The Kinesthetic and Visual Imagery Questionnaire (KVIQ) was recently developed to assess MI ability in patients with stroke and other disabilities. Considering the different underlying pathologies, the present study aimed to examine the validity and reliability of the KVIQ in MS patients. Fifteen MS patients were assessed using the KVIQ in 2 sessions (5-14 days apart) by the same examiner. In the second session, the participants also completed a revised MI questionnaire (MIQ-R) as the gold standard. Intra-class correlation coefficients (ICCs) were measured to determine test-retest reliability. Spearman's correlation analysis was performed to assess concurrent validity with the MIQ-R. Furthermore, the internal consistency (Cronbach's alpha) and factorial structure of the KVIQ were studied. The test-retest reliability for the KVIQ was good (ICCs: total KVIQ=0.89, visual KVIQ=0.85, and kinesthetic KVIQ=0.93), and the concurrent validity between the KVIQ and MIQ-R was good (r=0.79). The KVIQ had good internal consistency, with high Cronbach's alpha (alpha=0.84). Factorial analysis showed the bi-factorial structure of the KVIQ, which was explained by visual=57.6% and kinesthetic=32.4%. The results of the present study revealed that the KVIQ is a valid and reliable tool for assessing MI in MS patients.

Attention-deficit/hyperactivity disorder dimensionality: the reliable 'g' and the elusive 's' dimensions.

PubMed

Wagner, Flávia; Martel, Michelle M; Cogo-Moreira, Hugo; Maia, Carlos Renato Moreira; Pan, Pedro Mario; Rohde, Luis Augusto; Salum, Giovanni Abrahão

2016-01-01

The best structural model for attention-deficit/hyperactivity disorder (ADHD) symptoms remains a matter of debate. The objective of this study is to test the fit and factor reliability of competing models of the dimensional structure of ADHD symptoms in a sample of randomly selected and high-risk children and pre-adolescents from Brazil. Our sample comprised 2512 children aged 6-12 years from 57 schools in Brazil. The ADHD symptoms were assessed using parent report on the development and well-being assessment (DAWBA). Fit indexes from confirmatory factor analysis were used to test unidimensional, correlated, and bifactor models of ADHD, the latter including "g" ADHD and "s" symptom domain factors. Reliability of all models was measured with omega coefficients. A bifactor model with one general factor and three specific factors (inattention, hyperactivity, impulsivity) exhibited the best fit to the data, according to fit indices, as well as the most consistent factor loadings. However, based on omega reliability statistics, the specific inattention, hyperactivity, and impulsivity dimensions provided very little reliable information after accounting for the reliable general ADHD factor. Our study presents some psychometric evidence that ADHD specific ("s") factors might be unreliable after taking common ("g" factor) variance into account. These results are in accordance with the lack of longitudinal stability among subtypes, the absence of dimension-specific molecular genetic findings and non-specific effects of treatment strategies. Therefore, researchers and clinicians might most effectively rely on the "g" ADHD to characterize ADHD dimensional phenotype, based on currently available symptom items.

A recursive Bayesian approach for fatigue damage prognosis: An experimental validation at the reliability component level

NASA Astrophysics Data System (ADS)

Gobbato, Maurizio; Kosmatka, John B.; Conte, Joel P.

2014-04-01

Fatigue-induced damage is one of the most uncertain and highly unpredictable failure mechanisms for a large variety of mechanical and structural systems subjected to cyclic and random loads during their service life. A health monitoring system capable of (i) monitoring the critical components of these systems through non-destructive evaluation (NDE) techniques, (ii) assessing their structural integrity, (iii) recursively predicting their remaining fatigue life (RFL), and (iv) providing a cost-efficient reliability-based inspection and maintenance plan (RBIM) is therefore ultimately needed. In contribution to these objectives, the first part of the paper provides an overview and extension of a comprehensive reliability-based fatigue damage prognosis methodology — previously developed by the authors — for recursively predicting and updating the RFL of critical structural components and/or sub-components in aerospace structures. In the second part of the paper, a set of experimental fatigue test data, available in the literature, is used to provide a numerical verification and an experimental validation of the proposed framework at the reliability component level (i.e., single damage mechanism evolving at a single damage location). The results obtained from this study demonstrate (i) the importance and the benefits of a nearly continuous NDE monitoring system, (ii) the efficiency of the recursive Bayesian updating scheme, and (iii) the robustness of the proposed framework in recursively updating and improving the RFL estimations. This study also demonstrates that the proposed methodology can lead to either an extent of the RFL (with a consequent economical gain without compromising the minimum safety requirements) or an increase of safety by detecting a premature fault and therefore avoiding a very costly catastrophic failure.

Toward smart aerospace structures: design of a piezoelectric sensor and its analog interface for flaw detection.

PubMed

Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

2014-10-31

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated.

Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

PubMed Central

Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

2014-01-01

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated. PMID:25365457

Evaluation of a model of violence risk assessment among forensic psychiatric patients.

PubMed

Douglas, Kevin S; Ogloff, James R P; Hart, Stephen D

2003-10-01

This study tested the interrater reliability and criterion-related validity of structured violence risk judgments made by using one application of the structured professional judgment model of violence risk assessment, the HCR-20 violence risk assessment scheme, which assesses 20 key risk factors in three domains: historical, clinical, and risk management. The HCR-20 was completed for a sample of 100 forensic psychiatric patients who had been found not guilty by reason of a mental disorder and were subsequently released to the community. Violence in the community was determined from multiple file-based sources. Interrater reliability of structured final risk judgments of low, moderate, or high violence risk made on the basis of the structured professional judgment model was acceptable (weighted kappa=.61). Structured final risk judgments were significantly predictive of postrelease community violence, yielding moderate to large effect sizes. Event history analyses showed that final risk judgments made with the structured professional judgment model added incremental validity to the HCR-20 used in an actuarial (numerical) sense. The findings support the structured professional judgment model of risk assessment as well as the HCR-20 specifically and suggest that clinical judgment, if made within a structured context, can contribute in meaningful ways to the assessment of violence risk.

A Note on Structural Equation Modeling Estimates of Reliability

ERIC Educational Resources Information Center

Yang, Yanyun; Green, Samuel B.

2010-01-01

Reliability can be estimated using structural equation modeling (SEM). Two potential problems with this approach are that estimates may be unstable with small sample sizes and biased with misspecified models. A Monte Carlo study was conducted to investigate the quality of SEM estimates of reliability by themselves and relative to coefficient…

How to assess communication, professionalism, collaboration and the other intrinsic CanMEDS roles in orthopedic residents: use of an objective structured clinical examination (OSCE)

PubMed Central

Dwyer, Tim; Takahashi, Susan Glover; Hynes, Melissa Kennedy; Herold, Jodi; Wasserstein, David; Nousiainen, Markku; Ferguson, Peter; Wadey, Veronica; Murnaghan, M. Lucas; Leroux, Tim; Semple, John; Hodges, Brian; Ogilvie-Harris, Darrell

2014-01-01

Background Assessing residents’ understanding and application of the 6 intrinsic CanMEDS roles (communicator, professional, manager, collaborator, health advocate, scholar) is challenging for postgraduate medical educators. We hypothesized that an objective structured clinical examination (OSCE) designed to assess multiple intrinsic CanMEDS roles would be sufficiently reliable and valid. Methods The OSCE comprised 6 10-minute stations, each testing 2 intrinsic roles using case-based scenarios (with or without the use of standardized patients). Residents were evaluated using 5-point scales and an overall performance rating at each station. Concurrent validity was sought by correlation with in-training evaluation reports (ITERs) from the last 12 months and an ordinal ranking created by program directors (PDs). Results Twenty-five residents from postgraduate years (PGY) 0, 3 and 5 participated. The interstation reliability for total test scores (percent) was 0.87, while reliability for each of the communicator, collaborator, manager and professional roles was greater than 0.8. Total test scores, individual station scores and individual CanMEDS role scores all showed a significant effect by PGY level. Analysis of the PD rankings of intrinsic roles demonstrated a high correlation with the OSCE role scores. A correlation was seen between ITER and OSCE for the communicator role, while the ITER medical expert and total scores highly correlated with the communicator, manager and professional OSCE scores. Conclusion An OSCE designed to assess the intrinsic CanMEDS roles was sufficiently valid and reliable for regular use in an orthopedic residency program. PMID:25078926

Implementing and Evaluating a National Certification Technical Skills Examination: The Colorectal Objective Structured Assessment of Technical Skill.

PubMed

de Montbrun, Sandra; Roberts, Patricia L; Satterthwaite, Lisa; MacRae, Helen

2016-07-01

To implement the Colorectal Objective Structured Assessment of Technical skill (COSATS) into American Board of Colon and Rectal Surgery (ABCRS) certification and build evidence of validity for the interpretation of the scores of this high stakes assessment tool. Currently, technical skill assessment is not a formal component of board certification. With the technical demands of surgical specialties, documenting competence in technical skill at the time of certification with a valid tool is ideal. In September 2014, the COSATS was a mandatory component of ABCRS certification. Seventy candidates took the examination, with their performance evaluated by expert colorectal surgeons using a task-specific checklist, global rating scale, and overall performance scale. Passing scores were set and compared using 2 standard setting methodologies, using a compensatory and conjunctive model. Inter-rater reliability and the reliability of the pass/fail decision were calculated using Cronbach alpha and Subkoviak methodology, respectively. Overall COSATS scores and pass/fail status were compared with results on the ABCRS oral examination. The pass rate ranged from 85.7% to 90%. Inter-rater reliability (0.85) and reliability of the pass/fail decision (0.87 and 0.84) were high. A low positive correlation (r= 0.25) was seen between the COSATS and oral examination. All individuals who failed the COSATS passed the ABCRS oral examination. COSATS is the first technical skill examination used in national surgical board certification. This study suggests that the current certification process may be failing to identify individuals who have demonstrated technical deficiencies on this standardized assessment tool.

An atlas of high-resolution IRAS maps on nearby galaxies

NASA Technical Reports Server (NTRS)

Rice, Walter

1993-01-01

An atlas of far-infrared IRAS maps with near 1 arcmin angular resolution of 30 optically large galaxies is presented. The high-resolution IRAS maps were produced with the Maximum Correlation Method (MCM) image construction and enhancement technique developed at IPAC. The MCM technique, which recovers the spatial information contained in the overlapping detector data samples of the IRAS all-sky survey scans, is outlined and tests to verify the structural reliability and photometric integrity of the high-resolution maps are presented. The infrared structure revealed in individual galaxies is discussed. The atlas complements the IRAS Nearby Galaxy High-Resolution Image Atlas, the high-resolution galaxy images encoded in FITS format, which is provided to the astronomical community as an IPAC product.

Probabilistic structural analysis methods of hot engine structures

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Hopkins, D. A.

1989-01-01

Development of probabilistic structural analysis methods for hot engine structures at Lewis Research Center is presented. Three elements of the research program are: (1) composite load spectra methodology; (2) probabilistic structural analysis methodology; and (3) probabilistic structural analysis application. Recent progress includes: (1) quantification of the effects of uncertainties for several variables on high pressure fuel turbopump (HPFT) turbine blade temperature, pressure, and torque of the space shuttle main engine (SSME); (2) the evaluation of the cumulative distribution function for various structural response variables based on assumed uncertainties in primitive structural variables; and (3) evaluation of the failure probability. Collectively, the results demonstrate that the structural durability of hot engine structural components can be effectively evaluated in a formal probabilistic/reliability framework.

Recent advances in electron tomography: TEM and HAADF-STEM tomography for materials science and semiconductor applications.

PubMed

Kübel, Christian; Voigt, Andreas; Schoenmakers, Remco; Otten, Max; Su, David; Lee, Tan-Chen; Carlsson, Anna; Bradley, John

2005-10-01

Electron tomography is a well-established technique for three-dimensional structure determination of (almost) amorphous specimens in life sciences applications. With the recent advances in nanotechnology and the semiconductor industry, there is also an increasing need for high-resolution three-dimensional (3D) structural information in physical sciences. In this article, we evaluate the capabilities and limitations of transmission electron microscopy (TEM) and high-angle-annular-dark-field scanning transmission electron microscopy (HAADF-STEM) tomography for the 3D structural characterization of partially crystalline to highly crystalline materials. Our analysis of catalysts, a hydrogen storage material, and different semiconductor devices shows that features with a diameter as small as 1-2 nm can be resolved in three dimensions by electron tomography. For partially crystalline materials with small single crystalline domains, bright-field TEM tomography provides reliable 3D structural information. HAADF-STEM tomography is more versatile and can also be used for high-resolution 3D imaging of highly crystalline materials such as semiconductor devices.

Stirling engine - Approach for long-term durability assessment

NASA Technical Reports Server (NTRS)

Tong, Michael T.; Bartolotta, Paul A.; Halford, Gary R.; Freed, Alan D.

1992-01-01

The approach employed by NASA Lewis for the long-term durability assessment of the Stirling engine hot-section components is summarized. The approach consists of: preliminary structural assessment; development of a viscoplastic constitutive model to accurately determine material behavior under high-temperature thermomechanical loads; an experimental program to characterize material constants for the viscoplastic constitutive model; finite-element thermal analysis and structural analysis using a viscoplastic constitutive model to obtain stress/strain/temperature at the critical location of the hot-section components for life assessment; and development of a life prediction model applicable for long-term durability assessment at high temperatures. The approach should aid in the provision of long-term structural durability and reliability of Stirling engines.

Thermal and Structural Analysis of Micro-Fabricated Involute Regenerators

NASA Astrophysics Data System (ADS)

Qiu, Songgang; Augenblick, Jack E.

2005-02-01

Long-life, high-efficiency power generators based on free-piston Stirling engines are an energy conversion solution for future space power generation and commercial applications. As part of the efforts to further improve Stirling engine efficiency and reliability, a micro-fabricated, involute regenerator structure is proposed by a Cleveland State University-led regenerator research team. This paper reports on thermal and structural analyses of the involute regenerator to demonstrate the feasibility of the proposed regenerator. The results indicate that the involute regenerator has extremely high axial stiffness to sustain reasonable axial compression forces with negligible lateral deformation. The relatively low radial stiffness may impose some challenges to the appropriate installation of the in-volute regenerators.

Development of a problematic mobile phone use scale for Turkish adolescents.

PubMed

Güzeller, Cem Oktay; Coşguner, Tolga

2012-04-01

Abstract The aim of this study was to evaluate the psychometric properties of the Problematic Mobile Phone Use Scale (PMPUS) for Turkish Adolescents. The psychometric properties of PMPUS were tested in two separate sample groups that consisted of 950 Turkish high school students. The first sample group (n=309) was used to determine the factor structure of the scale. The second sample group (n=461) was used to test data conformity with the identified structure, discriminant validity and concurrent scale validity, internal consistency reliability calculations, and item statistics calculations. The results of exploratory factor analyses indicated that the scale had three factors: interference with negative effect, compulsion/persistence, and withdrawal/tolerance. The results showed that item and construct reliability values yielded satisfactory rates in general for the three-factor construct. On the other hand, the average variance extracted value remained below the scale value for three subscales. The scores for the scale significantly correlated with depression and loneliness. In addition, the discriminant validity value was above the scale in all sub-dimensions except one. Based on these data, the reliability of the PMPUS scale appears to be satisfactory and provides good internal consistency. Therefore, with limited exception, the PMPUS was found to be reliable and valid in the context of Turkish adolescents.

Composite membranes and methods for making same

DOEpatents

Routkevitch, Dmitri; Polyakov, Oleg G

2012-07-03

Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

Electrostatic and structural similarity of classical and non-classical lactam compounds

NASA Astrophysics Data System (ADS)

Coll, Miguel; Frau, Juan; Vilanova, Bartolomé; Donoso, Josefa; Muñoz, Francisco

2001-09-01

Various electrostatic and structural parameters for a series of classical and non-classical β-lactams were determined and compared in order to ascertain whether some specific β-lactams possess antibacterial or β-lactamase inhibitory properties. The electrostatic parameters obtained, based on the Distributed Multipole Analysis (DMA) of high-quality wavefunctions for the studied structures, suggest that some non-classical β-lactams effectively inhibit the action of β-lactamases. As shown in this work, such electrostatic parameters provide much more reliable information about the antibacterial and inhibitory properties of β-lactams than do structural parameters.

Recent developments of the NESSUS probabilistic structural analysis computer program

NASA Technical Reports Server (NTRS)

Millwater, H.; Wu, Y.-T.; Torng, T.; Thacker, B.; Riha, D.; Leung, C. P.

1992-01-01

The NESSUS probabilistic structural analysis computer program combines state-of-the-art probabilistic algorithms with general purpose structural analysis methods to compute the probabilistic response and the reliability of engineering structures. Uncertainty in loading, material properties, geometry, boundary conditions and initial conditions can be simulated. The structural analysis methods include nonlinear finite element and boundary element methods. Several probabilistic algorithms are available such as the advanced mean value method and the adaptive importance sampling method. The scope of the code has recently been expanded to include probabilistic life and fatigue prediction of structures in terms of component and system reliability and risk analysis of structures considering cost of failure. The code is currently being extended to structural reliability considering progressive crack propagation. Several examples are presented to demonstrate the new capabilities.

Parcellation of the human orbitofrontal cortex based on gray matter volume covariance.

PubMed

Liu, Huaigui; Qin, Wen; Qi, Haotian; Jiang, Tianzi; Yu, Chunshui

2015-02-01

The human orbitofrontal cortex (OFC) is an enigmatic brain region that cannot be parcellated reliably using diffusional and functional magnetic resonance imaging (fMRI) because there is signal dropout that results from an inherent defect in imaging techniques. We hypothesise that the OFC can be reliably parcellated into subregions based on gray matter volume (GMV) covariance patterns that are derived from artefact-free structural images. A total of 321 healthy young subjects were examined by high-resolution structural MRI. The OFC was parcellated into subregions-based GMV covariance patterns; and then sex and laterality differences in GMV covariance pattern of each OFC subregion were compared. The human OFC was parcellated into the anterior (OFCa), medial (OFCm), posterior (OFCp), intermediate (OFCi), and lateral (OFCl) subregions. This parcellation scheme was validated by the same analyses of the left OFC and the bilateral OFCs in male and female subjects. Both visual observation and quantitative comparisons indicated a unique GMV covariance pattern for each OFC subregion. These OFC subregions mainly covaried with the prefrontal and temporal cortices, cingulate cortex and amygdala. In addition, GMV correlations of most OFC subregions were similar across sex and laterality except for significant laterality difference in the OFCl. The right OFCl had stronger GMV correlation with the right inferior frontal cortex. Using high-resolution structural images, we established a reliable parcellation scheme for the human OFC, which may provide an in vivo guide for subregion-level studies of this region and improve our understanding of the human OFC at subregional levels. © 2014 Wiley Periodicals, Inc.

Children's Hospitals' Solutions for Patient Safety Collaborative Impact on Hospital-Acquired Harm.

PubMed

Lyren, Anne; Brilli, Richard J; Zieker, Karen; Marino, Miguel; Muething, Stephen; Sharek, Paul J

2017-09-01

To determine if an improvement collaborative of 33 children's hospitals focused on reliable best practice implementation and culture of safety improvements can reduce hospital-acquired conditions (HACs) and serious safety events (SSEs). A 3-year prospective cohort study design with a 12-month historical control population was completed by the Children's Hospitals' Solutions for Patient Safety collaborative. Identification and dissemination of best practices related to 9 HACs and SSE reduction focused on key process and culture of safety improvements. Individual hospital improvement teams leveraged the resources of a large, structured children's hospital collaborative using electronic, virtual, and in-person interactions. Thirty-three children's hospitals from across the United States volunteered to be part of the Children's Hospitals' Solutions for Patient Safety collaborative. Thirty-two met all the data submission eligibility requirements for the HAC improvement objective of this study, and 21 participated in the high-reliability culture work aimed at reducing SSEs. Significant harm reduction occurred in 8 of 9 common HACs (range 9%-71%; P < .005 for all). The mean monthly SSE rate decreased 32% (from 0.77 to 0.52; P < .001). The 12-month rolling average SSE rate decreased 50% (from 0.82 to 0.41; P < .001). Participation in a structured collaborative dedicated to implementing HAC-related best-practice prevention bundles and culture of safety interventions designed to increase the use of high-reliability organization practices resulted in significant HAC and SSE reductions. Structured collaboration and rapid sharing of evidence-based practices and tools are effective approaches to decreasing hospital-acquired harm. Copyright © 2017 by the American Academy of Pediatrics.

Validity and reliability of the Malay version of the Hill-Bone compliance to high blood pressure therapy scale for use in primary healthcare settings in Malaysia: A cross-sectional study.

PubMed

Cheong, A T; Tong, S F; Sazlina, S G

2015-01-01

Hill-Bone compliance to high blood pressure therapy scale (HBTS) is one of the useful scales in primary care settings. It has been tested in America, Africa and Turkey with variable validity and reliability. The aim of this paper was to determine the validity and reliability of the Malay version of HBTS (HBTS-M) for the Malaysian population. HBTS comprises three subscales assessing compliance to medication, appointment and salt intake. The content validity of HBTS to the local population was agreed through consensus of expert panel. The 14 items used in the HBTS were adapted to reflect the local situations. It was translated into Malay and then back-translated into English. The translated version was piloted in 30 participants. This was followed by structural and predictive validity, and internal consistency testing in 262 patients with hypertension, who were on antihypertensive agent(s) for at least 1 year in two primary healthcare clinics in Kuala Lumpur, Malaysia. Exploratory factor analyses and the correlation between HBTS-M total score and blood pressure were performed. The Cronbach's alpha was calculated accordingly. Factor analysis revealed a three-component structure represented by two components on medication adherence and one on salt intake adherence. The Kaiser-Meyer-Olkin statistic was 0.764. The variance explained by each factors were 23.6%, 10.4% and 9.8%, respectively. However, the internal consistency for each component was suboptimal with Cronbach's alpha of 0.64, 0.55 and 0.29, respectively. Although there were two components representing medication adherence, the theoretical concepts underlying each concept cannot be differentiated. In addition, there was no correlation between the HBTS-M total score and blood pressure. HBTS-M did not conform to the structural and predictive validity of the original scale. Its reliability on assessing medication and salt intake adherence would most probably to be suboptimal in the Malaysian primary care setting.

Cross-cultural adaptation, reliability and validity of the Turkish version of the Lower Limb Functional Index.

PubMed

Duruturk, Neslihan; Tonga, Eda; Gabel, Charles Philip; Acar, Manolya; Tekindal, Agah

2015-07-26

This study aims to adapt culturally a Turkish version of the Lower Limb Functional Index (LLFI) and to determine its validity, reliability, internal consistency, measurement sensitivity and factor structure in lower limb problems. The LLFI was translated into Turkish and cross-culturally adapted with a double forward-backward protocol that determined face and content validity. Individuals (n = 120) with lower limb musculoskeletal disorders completed the LLFI and Short Form-36 questionnaires and the Timed Up and Go physical test. The psychometric properties were evaluated for the all participants from patient-reported outcome measures made at baseline and repeated at day 3 to determine criterion between scores (Pearson's r), internal consistency (Cronbachs α) and test-retest reliability (intraclass correlation coefficient - ICC 2.1 ). Error was determined using standard error of the measurement (SEM) and minimal detectable change at the 90% level (MDC 90 ), while factor structure was determined using exploratory factor analysis with maximum likelihood extraction and Varimax rotation. The psychometric characteristics showed strong criterion validity (r = 0.74-0.76), high internal consistency (α = 0.82) and high test-retest reability (ICC 2.1  = 0.97). The SEM of 3.2% gave an MDC 90  = 5.8%. The factor structure was uni-dimensional. Turkish version of LLFI was found to be valid and reliable for the measurement of lower limb function in a Turkish population. Implications for Rehabilitation Lower extremity musculoskeletal disorders are common and greatly impact activities among the affected individuals pertaining to daily living, work, leisure and quality of life. Patient-reported outcome (PRO) measures have advantages as they are practical, cost-effective and clinically convenient for use in patient-centered care. The Lower Limb Functional Index is a recently validated PRO measure shown to have strong clinimetric properties.

Item Response Theory analysis of Fagerström Test for Cigarette Dependence.

PubMed

Svicher, Andrea; Cosci, Fiammetta; Giannini, Marco; Pistelli, Francesco; Fagerström, Karl

2018-02-01

The Fagerström Test for Cigarette Dependence (FTCD) and the Heaviness of Smoking Index (HSI) are the gold standard measures to assess cigarette dependence. However, FTCD reliability and factor structure have been questioned and HSI psychometric properties are in need of further investigations. The present study examined the psychometrics properties of the FTCD and the HSI via the Item Response Theory. The study was a secondary analysis of data collected in 862 Italian daily smokers. Confirmatory factor analysis was run to evaluate the dimensionality of FTCD. A Grade Response Model was applied to FTCD and HSI to verify the fit to the data. Both item and test functioning were analyzed and item statistics, Test Information Function, and scale reliabilities were calculated. Mokken Scale Analysis was applied to estimate homogeneity and Loevinger's coefficients were calculated. The FTCD showed unidimensionality and homogeneity for most of the items and for the total score. It also showed high sensitivity and good reliability from medium to high levels of cigarette dependence, although problems related to some items (i.e., items 3 and 5) were evident. HSI had good homogeneity, adequate item functioning, and high reliability from medium to high levels of cigarette dependence. Significant Differential Item Functioning was found for items 1, 4, 5 of the FTCD and for both items of HSI. HSI seems highly recommended in clinical settings addressed to heavy smokers while FTCD would be better used in smokers with a level of cigarette dependence ranging between low and high. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advanced Stirling Convertor Heater Head Durability and Reliability Quantification

NASA Technical Reports Server (NTRS)

Krause, David L.; Shah, Ashwin R.; Korovaichuk, Igor; Kalluri, Sreeramesh

2008-01-01

The National Aeronautics and Space Administration (NASA) has identified the high efficiency Advanced Stirling Radioisotope Generator (ASRG) as a candidate power source for long duration Science missions, such as lunar applications, Mars rovers, and deep space missions, that require reliable design lifetimes of up to 17 years. Resistance to creep deformation of the MarM-247 heater head (HH), a structurally critical component of the ASRG Advanced Stirling Convertor (ASC), under high temperatures (up to 850 C) is a key design driver for durability. Inherent uncertainties in the creep behavior of the thin-walled HH and the variations in the wall thickness, control temperature, and working gas pressure need to be accounted for in the life and reliability prediction. Due to the availability of very limited test data, assuring life and reliability of the HH is a challenging task. The NASA Glenn Research Center (GRC) has adopted an integrated approach combining available uniaxial MarM-247 material behavior testing, HH benchmark testing and advanced analysis in order to demonstrate the integrity, life and reliability of the HH under expected mission conditions. The proposed paper describes analytical aspects of the deterministic and probabilistic approaches and results. The deterministic approach involves development of the creep constitutive model for the MarM-247 (akin to the Oak Ridge National Laboratory master curve model used previously for Inconel 718 (Special Metals Corporation)) and nonlinear finite element analysis to predict the mean life. The probabilistic approach includes evaluation of the effect of design variable uncertainties in material creep behavior, geometry and operating conditions on life and reliability for the expected life. The sensitivity of the uncertainties in the design variables on the HH reliability is also quantified, and guidelines to improve reliability are discussed.

Blinded evaluation of interrater reliability of an operative competency assessment tool for direct laryngoscopy and rigid bronchoscopy.

PubMed

Ishman, Stacey L; Benke, James R; Johnson, Kaalan Erik; Zur, Karen B; Jacobs, Ian N; Thorne, Marc C; Brown, David J; Lin, Sandra Y; Bhatti, Nasir; Deutsch, Ellen S

2012-10-01

OBJECTIVES To confirm interrater reliability using blinded evaluation of a skills-assessment instrument to assess the surgical performance of resident and fellow trainees performing pediatric direct laryngoscopy and rigid bronchoscopy in simulated models. DESIGN Prospective, paired, blinded observational validation study. SUBJECTS Paired observers from multiple institutions simultaneously evaluated residents and fellows who were performing surgery in an animal laboratory or using high-fidelity manikins. The evaluators had no previous affiliation with the residents and fellows and did not know their year of training. INTERVENTIONS One- and 2-page versions of an objective structured assessment of technical skills (OSATS) assessment instrument composed of global and a task-specific surgical items were used to evaluate surgical performance. RESULTS Fifty-two evaluations were completed by 17 attending evaluators. The instrument agreement for the 2-page assessment was 71.4% when measured as a binary variable (ie, competent vs not competent) (κ = 0.38; P = .08). Evaluation as a continuous variable revealed a 42.9% percentage agreement (κ = 0.18; P = .14). The intraclass correlation was 0.53, considered substantial/good interrater reliability (69% reliable). For the 1-page instrument, agreement was 77.4% when measured as a binary variable (κ = 0.53, P = .0015). Agreement when evaluated as a continuous measure was 71.0% (κ = 0.54, P < .001). The intraclass correlation was 0.73, considered high interrater reliability (85% reliable). CONCLUSIONS The OSATS assessment instrument is an effective tool for evaluating surgical performance among trainees with acceptable interrater reliability in a simulator setting. Reliability was good for both the 1- and 2-page OSATS checklists, and both serve as excellent tools to provide immediate formative feedback on operational competency.

Short Scales for the Assessment of Personality Traits: Development and Validation of the Portuguese Ten-Item Personality Inventory (TIPI)

PubMed Central

Nunes, Andreia; Limpo, Teresa; Lima, César F.; Castro, São Luís

2018-01-01

The importance of quickly assessing personality traits in many studies prompted the development of brief scales such as the Ten-Item Personality Inventory (TIPI), a measure of five personality traits (extraversion, agreeableness, conscientiousness, emotional stability, and openness). In the current study, we present the Portuguese version of TIPI and examine its psychometric properties, based on a sample of 333 Portuguese adults aged 18 to 65 years. The results revealed reliability coefficients similar to the original version (α = 0.39–0.72), very good 4-week test–retest reliability (n = 81, rs > 0.71), expected factorial structure, high convergent validity with the Big-Five Inventory (rs > 0.60), and correlations with self-esteem, affect, and aggressiveness similar to those found with standard measures of personality traits. Overall, our findings suggest that the Portuguese TIPI is a reliable and valid alternative to longer measures: it offers a promising tool for research contexts in which the available time for personality assessment is highly limited. PMID:29674989

Short Scales for the Assessment of Personality Traits: Development and Validation of the Portuguese Ten-Item Personality Inventory (TIPI).

PubMed

Nunes, Andreia; Limpo, Teresa; Lima, César F; Castro, São Luís

2018-01-01

The importance of quickly assessing personality traits in many studies prompted the development of brief scales such as the Ten-Item Personality Inventory (TIPI), a measure of five personality traits (extraversion, agreeableness, conscientiousness, emotional stability, and openness). In the current study, we present the Portuguese version of TIPI and examine its psychometric properties, based on a sample of 333 Portuguese adults aged 18 to 65 years. The results revealed reliability coefficients similar to the original version (α = 0.39-0.72), very good 4-week test-retest reliability ( n = 81, r s > 0.71), expected factorial structure, high convergent validity with the Big-Five Inventory ( r s > 0.60), and correlations with self-esteem, affect, and aggressiveness similar to those found with standard measures of personality traits. Overall, our findings suggest that the Portuguese TIPI is a reliable and valid alternative to longer measures: it offers a promising tool for research contexts in which the available time for personality assessment is highly limited.

Psychometric Properties of Physical Activity and Leisure Motivation Scale in Farsi: an International Collaborative Project on Motivation for Physical Activity and Leisure.

PubMed

Zarei, Sahar; Memari, Amir-Hossein; Moshayedi, Pouria; Mosayebi, Fatolla; Mansournia, Mohammad Ali; Khoo, Selina; Morris, Tony

2016-10-01

Given the importance of regular physical activity, it is crucial to evaluate the factors favoring participation in physical activity. We aimed to report the psychometric analysis of the Farsi version of the Physical Activity and Leisure Motivation Scale (PALMS). The Farsi version of PALMS was completed by 406 healthy adult individuals to test its factor structure and concurrent validity and reliability. Conducting the exploratory factor analysis revealed nine factors that accounted for 64.6% of the variances. The PALMS reliability was supported with a high internal consistency of 0.91 and a high test-retest reliability of 0.97 (95% CI: 0.97-0.98). The association between the PALMS and its previous version Recreational Exercise Motivation Measure scores was strongly significant (r= 0.86, P < 0.001). We have shown that the Farsi version of the PALMS appears to be a valuable instrument to measure motivation for physical activity and leisure.

The Reliability and Predictive Validity of the Stalking Risk Profile.

PubMed

McEwan, Troy E; Shea, Daniel E; Daffern, Michael; MacKenzie, Rachel D; Ogloff, James R P; Mullen, Paul E

2018-03-01

This study assessed the reliability and validity of the Stalking Risk Profile (SRP), a structured measure for assessing stalking risks. The SRP was administered at the point of assessment or retrospectively from file review for 241 adult stalkers (91% male) referred to a community-based forensic mental health service. Interrater reliability was high for stalker type, and moderate-to-substantial for risk judgments and domain scores. Evidence for predictive validity and discrimination between stalking recidivists and nonrecidivists for risk judgments depended on follow-up duration. Discrimination was moderate (area under the curve = 0.66-0.68) and positive and negative predictive values good over the full follow-up period ( Mdn = 170.43 weeks). At 6 months, discrimination was better than chance only for judgments related to stalking of new victims (area under the curve = 0.75); however, high-risk stalkers still reoffended against their original victim(s) 2 to 4 times as often as low-risk stalkers. Implications for the clinical utility and refinement of the SRP are discussed.

Maximally reliable Markov chains under energy constraints.

PubMed

Escola, Sean; Eisele, Michael; Miller, Kenneth; Paninski, Liam

2009-07-01

Signal-to-noise ratios in physical systems can be significantly degraded if the outputs of the systems are highly variable. Biological processes for which highly stereotyped signal generations are necessary features appear to have reduced their signal variabilities by employing multiple processing steps. To better understand why this multistep cascade structure might be desirable, we prove that the reliability of a signal generated by a multistate system with no memory (i.e., a Markov chain) is maximal if and only if the system topology is such that the process steps irreversibly through each state, with transition rates chosen such that an equal fraction of the total signal is generated in each state. Furthermore, our result indicates that by increasing the number of states, it is possible to arbitrarily increase the reliability of the system. In a physical system, however, an energy cost is associated with maintaining irreversible transitions, and this cost increases with the number of such transitions (i.e., the number of states). Thus, an infinite-length chain, which would be perfectly reliable, is infeasible. To model the effects of energy demands on the maximally reliable solution, we numerically optimize the topology under two distinct energy functions that penalize either irreversible transitions or incommunicability between states, respectively. In both cases, the solutions are essentially irreversible linear chains, but with upper bounds on the number of states set by the amount of available energy. We therefore conclude that a physical system for which signal reliability is important should employ a linear architecture, with the number of states (and thus the reliability) determined by the intrinsic energy constraints of the system.

Implications of scaling on static RAM bit cell stability and reliability

NASA Astrophysics Data System (ADS)

Coones, Mary Ann; Herr, Norm; Bormann, Al; Erington, Kent; Soorholtz, Vince; Sweeney, John; Phillips, Michael

1993-01-01

In order to lower manufacturing costs and increase performance, static random access memory (SRAM) bit cells are scaled progressively toward submicron geometries. The reliability of an SRAM is highly dependent on the bit cell stability. Smaller memory cells with less capacitance and restoring current make the array more susceptible to failures from defectivity, alpha hits, and other instabilities and leakage mechanisms. Improving long term reliability while migrating to higher density devices makes the task of building in and improving reliability increasingly difficult. Reliability requirements for high density SRAMs are very demanding with failure rates of less than 100 failures per billion device hours (100 FITs) being a common criteria. Design techniques for increasing bit cell stability and manufacturability must be implemented in order to build in this level of reliability. Several types of analyses are performed to benchmark the performance of the SRAM device. Examples of these analysis techniques which are presented here include DC parametric measurements of test structures, functional bit mapping of the circuit used to characterize the entire distribution of bits, electrical microprobing of weak and/or failing bits, and system and accelerated soft error rate measurements. These tests allow process and design improvements to be evaluated prior to implementation on the final product. These results are used to provide comprehensive bit cell characterization which can then be compared to device models and adjusted accordingly to provide optimized cell stability versus cell size for a particular technology. The result is designed in reliability which can be accomplished during the early stages of product development.

Correlation-based motion vector processing with adaptive interpolation scheme for motion-compensated frame interpolation.

PubMed

Huang, Ai-Mei; Nguyen, Truong

2009-04-01

In this paper, we address the problems of unreliable motion vectors that cause visual artifacts but cannot be detected by high residual energy or bidirectional prediction difference in motion-compensated frame interpolation. A correlation-based motion vector processing method is proposed to detect and correct those unreliable motion vectors by explicitly considering motion vector correlation in the motion vector reliability classification, motion vector correction, and frame interpolation stages. Since our method gradually corrects unreliable motion vectors based on their reliability, we can effectively discover the areas where no motion is reliable to be used, such as occlusions and deformed structures. We also propose an adaptive frame interpolation scheme for the occlusion areas based on the analysis of their surrounding motion distribution. As a result, the interpolated frames using the proposed scheme have clearer structure edges and ghost artifacts are also greatly reduced. Experimental results show that our interpolated results have better visual quality than other methods. In addition, the proposed scheme is robust even for those video sequences that contain multiple and fast motions.

Reliability assessment of an OVH HV power line truss transmission tower subjected to seismic loading

NASA Astrophysics Data System (ADS)

Winkelmann, Karol; Jakubowska, Patrycja; Soltysik, Barbara

2017-03-01

The study focuses on the reliability of a transmission tower OS24 ON150 + 10, an element of an OVH HV power line, under seismic loading. In order to describe the seismic force, the real-life recording of the horizontal component of the El Centro earthquake was adopted. The amplitude and the period of this excitation are assumed random, their variation is described by Weibull distribution. The possible space state of the phenomenon is given in the form of a structural response surface (RSM methodology), approximated by an ANOVA table with directional sampling (DS) points. Four design limit states are considered: stress limit criterion for a natural load combination, criterion for an accidental combination (one-sided cable snap), vertical and horizontal translation criteria. According to these cases the HLRF reliability index β is used for structural safety assessment. The RSM approach is well suited for the analysis - it is numerically efficient, not excessively time consuming, indicating a high confidence level. Given the problem conditions, the seismic excitation is shown the sufficient trigger to the loss of load-bearing capacity or stability of the tower.

Psychometric properties of the Social Phobia and Anxiety Inventory for Children in a Spanish sample.

PubMed

Olivares, José; Sánchez-García, Raquel; López-Pina, José Antonio; Rosa-Alcázar, Ana Isabel

2010-11-01

The objectives of the present study were to adapt and analyze the factor structure, reliability, and validity of the Social Phobia and Anxiety Inventory for Children (SPAI-C; Beidel, Turner, & Morris, 1995) in a Spanish population. The SPAI-C was applied to a sample of 1588 children and adolescents with ages ranging from 10 to 17 years. The confirmatory factor analysis (CFA) showed a four-factor structure: Public performance, Assertiveness, Fear and avoidance/escape in social encounters, and Cognitive and psychophysiological interferences. Internal consistency was high (.90) and test-retest reliability was moderate (.56). Significant differences were found in the variables sex and age, although the effect size was small in both variables and their interaction. Overall, the increase of the age value was inversely proportional to that of social anxiety measured with the SPAI-C; in participants of the same age, values were higher for girls than for boys. Results suggest that the Social Phobia and Anxiety Inventory For Children is a valid and reliable instrument to assess social anxiety in Spanish children and adolescents.

Reliability, Factor Structure, and Measurement Invariance of the Dominic Interactive Across European Countries: Cross-Country Utility of a Child Mental Health Self-Report

PubMed Central

Kuijpers, Rowella C. W. M.; Otten, Roy; Vermulst, Ad A.; Bitfoi, Adina; Goelitz, Dietmar; Koç, Ceren; Mihova, Zlatka; Pez, Ondine; Carta, Mauro; Keyes, Katherine; Lesinskiene, Sigita; Engels, Rutger C. M. E.; Kovess, Viviane

2015-01-01

Large-scale international surveys are important to globally evaluate, monitor, and promote children's mental health. However, use of young children's self-reports in these studies is still controversial. The Dominic Interactive, a computerized DSM-IV–based child mental health self-report questionnaire, has unique characteristics that may make it preeminently appropriate for usage in cross-country comparisons. This study aimed to determine scale score reliabilities (omega) of the Dominic Interactive in a sample of 8,135 primary school children, ages 6–11 years old, in 7 European countries, to confirm the proposed 7-scale factor structure, and to test for measurement invariance of scale and item scores across countries. Omega reliability values for scale scores were good to high in every country, and the factor structure was confirmed for all countries. A thorough examination of measurement invariance provided evidence for cross-country test score comparability of 5 of the 7 scales and partial scale score invariance of 2 anxiety scales. Possible explanations for this partial invariance include cross-country differences in conceptualizing items and defining what is socially and culturally acceptable anxiety. The convincing evidence for validity of score interpretation makes the Dominic Interactive an indispensable tool for cross-country screening purposes. PMID:26237209

Properties Of Carbon/Carbon and Carbon/Phenolic Composites

NASA Technical Reports Server (NTRS)

Mathis, John R.; Canfield, A. R.

1993-01-01

Report presents data on physical properties of carbon-fiber-reinforced carbon-matrix and phenolic-matrix composite materials. Based on tests conducted on panels, cylinders, blocks, and formed parts. Data used by designers to analyze thermal-response and stress levels and develop structural systems ensuring high reliability at minimum weight.

Measuring Long-Distance Romantic Relationships: A Validity Study

ERIC Educational Resources Information Center

Pistole, M. Carole; Roberts, Amber

2011-01-01

This study investigated aspects of construct validity for the scores of a new long-distance romantic relationship measure. A single-factor structure of the long-distance romantic relationship index emerged, with convergent and discriminant evidence of external validity, high internal consistency reliability, and applied utility of the scores.…

The Mindful Attention Awareness Scale (MAAS) in an Argentine Population

ERIC Educational Resources Information Center

Montes, Silvana Andrea; Ledesma, Rubén Daniel; García, Natalia Mariana; Poó, Fernando Martín

2014-01-01

The purpose of this study was to provide evidence of validity for the Mindful Attention Awareness Scale scores in an Argentine sample (Spanish-language version). Results indicated satisfactory psychometric properties (a one-factor structure, good item discrimination, high reliability, and significant correlations with additional measures). This…

Fatigue reliability of deck structures subjected to correlated crack growth

NASA Astrophysics Data System (ADS)

Feng, G. Q.; Garbatov, Y.; Guedes Soares, C.

2013-12-01

The objective of this work is to analyse fatigue reliability of deck structures subjected to correlated crack growth. The stress intensity factors of the correlated cracks are obtained by finite element analysis and based on which the geometry correction functions are derived. The Monte Carlo simulations are applied to predict the statistical descriptors of correlated cracks based on the Paris-Erdogan equation. A probabilistic model of crack growth as a function of time is used to analyse the fatigue reliability of deck structures accounting for the crack propagation correlation. A deck structure is modelled as a series system of stiffened panels, where a stiffened panel is regarded as a parallel system composed of plates and are longitudinal. It has been proven that the method developed here can be conveniently applied to perform the fatigue reliability assessment of structures subjected to correlated crack growth.

Verification and Validation in a Rapid Software Development Process

NASA Technical Reports Server (NTRS)

Callahan, John R.; Easterbrook, Steve M.

1997-01-01

The high cost of software production is driving development organizations to adopt more automated design and analysis methods such as rapid prototyping, computer-aided software engineering (CASE) tools, and high-level code generators. Even developers of safety-critical software system have adopted many of these new methods while striving to achieve high levels Of quality and reliability. While these new methods may enhance productivity and quality in many cases, we examine some of the risks involved in the use of new methods in safety-critical contexts. We examine a case study involving the use of a CASE tool that automatically generates code from high-level system designs. We show that while high-level testing on the system structure is highly desirable, significant risks exist in the automatically generated code and in re-validating releases of the generated code after subsequent design changes. We identify these risks and suggest process improvements that retain the advantages of rapid, automated development methods within the quality and reliability contexts of safety-critical projects.

Reliability and Validity of the Telephone-Based eHealth Literacy Scale Among Older Adults: Cross-Sectional Survey.

PubMed

Stellefson, Michael; Paige, Samantha R; Tennant, Bethany; Alber, Julia M; Chaney, Beth H; Chaney, Don; Grossman, Suzanne

2017-10-26

Only a handful of studies have examined reliability and validity evidence of scores produced by the 8-item eHealth literacy Scale (eHEALS) among older adults. Older adults are generally more comfortable responding to survey items when asked by a real person rather than by completing self-administered paper-and-pencil or online questionnaires. However, no studies have explored the psychometrics of this scale when administered to older adults over the telephone. The objective of our study was to examine the reliability and internal structure of eHEALS data collected from older adults aged 50 years or older responding to items over the telephone. Respondents (N=283) completed eHEALS as part of a cross-sectional landline telephone survey. Exploratory structural equation modeling (E-SEM) analyses examined model fit of eHEALS scores with 1-, 2-, and 3-factor structures. Subsequent analyses based on the partial credit model explored the internal structure of eHEALS data. Compared with 1- and 2-factor models, the 3-factor eHEALS structure showed the best global E-SEM model fit indices (root mean square error of approximation=.07; comparative fit index=1.0; Tucker-Lewis index=1.0). Nonetheless, the 3 factors were highly correlated (r range .36 to .65). Item analyses revealed that eHEALS items 2 through 5 were overfit to a minor degree (mean square infit/outfit values <1.0; t statistics less than -2.0), but the internal structure of Likert scale response options functioned as expected. Overfitting eHEALS items (2-5) displayed a similar degree of information for respondents at similar points on the latent continuum. Test information curves suggested that eHEALS may capture more information about older adults at the higher end of the latent continuum (ie, those with high eHealth literacy) than at the lower end of the continuum (ie, those with low eHealth literacy). Item reliability (value=.92) and item separation (value=11.31) estimates indicated that eHEALS responses were reliable and stable. Results support administering eHEALS over the telephone when surveying older adults regarding their use of the Internet for health information. eHEALS scores best captured 3 factors (or subscales) to measure eHealth literacy in older adults; however, statistically significant correlations between these 3 factors suggest an overarching unidimensional structure with 3 underlying dimensions. As older adults continue to use the Internet more frequently to find and evaluate health information, it will be important to consider modifying the original eHEALS to adequately measure societal shifts in online health information seeking among aging populations. ©Michael Stellefson, Samantha R Paige, Bethany Tennant, Julia M Alber, Beth H Chaney, Don Chaney, Suzanne Grossman. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 26.10.2017.

Supporting Technology at GRC to Mitigate Risk as Stirling Power Conversion Transitions to Flight

NASA Technical Reports Server (NTRS)

Schreiber, Jeffrey G.; Thieme, Lanny G.; Wong, Wayne A.

2009-01-01

Stirling power conversion technology has been reaching more advanced levels of maturity during its development for space power applications. The current effort is in support of the Advanced Stirling Radioisotope Generator (ASRG), which is being developed by the U.S. Department of Energy (DOE), Lockheed Martin Space Systems Company (LMSSC), Sunpower Inc., and the NASA Glenn Research Center (GRC). This generator would use two high-efficiency Advanced Stirling Convertors (ASCs) to convert thermal energy from a radioisotope heat source into electricity. Of paramount importance is the reliability of the power system and as a part of this, the Stirling power convertors. GRC has established a supporting technology effort with tasks in the areas of reliability, convertor testing, high-temperature materials, structures, advanced analysis, organics, and permanent magnets. The project utilizes the matrix system at GRC to make use of resident experts in each of the aforementioned fields. Each task is intended to reduce risk and enhance reliability of the convertor as this technology transitions toward flight status. This paper will provide an overview of each task, outline the recent efforts and accomplishments, and show how they mitigate risk and impact the reliability of the ASC s and ultimately, the ASRG.

Supporting Technology at GRC to Mitigate Risk as Stirling Power Conversion Transitions to Flight

NASA Technical Reports Server (NTRS)

Schreiber, Jeffrey G.; Thieme, Lanny G.; Wong, Wayne A.

2008-01-01

Stirling power conversion technology has been reaching more advanced levels of maturity during its development for space power applications. The current effort is in support of the Advanced Stirling Radioisotope Generator (ASRG), which is being developed by the U.S. Department of Energy (DOE), Lockheed Martin Space Systems Company (LMSSC), Sunpower Inc., and the NASA Glenn Research Center (GRC). This generator would use two high-efficiency Advanced Stirling Convertors (ASCs) to convert thermal energy from a radioisotope heat source into electricity. Of paramount importance is the reliability of the power system and as a part of this, the Stirling power convertors. GRC has established a supporting technology effort with tasks in the areas of reliability, convertor testing, high-temperature materials, structures, advanced analysis, organics, and permanent magnets. The project utilizes the matrix system at GRC to make use of resident experts in each of the aforementioned fields. Each task is intended to reduce risk and enhance reliability of the convertor as this technology transitions toward flight status. This paper will provide an overview of each task, outline the recent efforts and accomplishments, and show how they mitigate risk and impact the reliability of the ASC s and ultimately, the ASRG.

Reliability of Summed Item Scores Using Structural Equation Modeling: An Alternative to Coefficient Alpha

ERIC Educational Resources Information Center

Green, Samuel B.; Yang, Yanyun

2009-01-01

A method is presented for estimating reliability using structural equation modeling (SEM) that allows for nonlinearity between factors and item scores. Assuming the focus is on consistency of summed item scores, this method for estimating reliability is preferred to those based on linear SEM models and to the most commonly reported estimate of…

Interval Estimation of Revision Effect on Scale Reliability via Covariance Structure Modeling

ERIC Educational Resources Information Center

Raykov, Tenko

2009-01-01

A didactic discussion of a procedure for interval estimation of change in scale reliability due to revision is provided, which is developed within the framework of covariance structure modeling. The method yields ranges of plausible values for the population gain or loss in reliability of unidimensional composites, which results from deletion or…

A theoretical probe of high-valence uranium and transuranium silylamides: Structural and redox properties

NASA Astrophysics Data System (ADS)

Zhong, Yu-Xi; Guo, Yuan-Ru; Pan, Qing-Jiang

2016-02-01

Relativistic density functional theory was used to explore the structural and redox properties of 18 prototypical actinyl silylamides including a variation of metals (U, Np and Pu), metal oxidation states (VI and V) and equatorial ligands. A theoretical approach associated with implicit solvation and spin-orbit/multiplet corrections was proved to be reliable. A marked shift of reduction potentials of actinyl silylamides caused by changes of equatorial coordination ligands and implicit solvation was elucidated by analyses of electronic structures and single-electron reduction mechanism.

Computational methods for efficient structural reliability and reliability sensitivity analysis

NASA Technical Reports Server (NTRS)

Wu, Y.-T.

1993-01-01

This paper presents recent developments in efficient structural reliability analysis methods. The paper proposes an efficient, adaptive importance sampling (AIS) method that can be used to compute reliability and reliability sensitivities. The AIS approach uses a sampling density that is proportional to the joint PDF of the random variables. Starting from an initial approximate failure domain, sampling proceeds adaptively and incrementally with the goal of reaching a sampling domain that is slightly greater than the failure domain to minimize over-sampling in the safe region. Several reliability sensitivity coefficients are proposed that can be computed directly and easily from the above AIS-based failure points. These probability sensitivities can be used for identifying key random variables and for adjusting design to achieve reliability-based objectives. The proposed AIS methodology is demonstrated using a turbine blade reliability analysis problem.

Probabilistic sizing of laminates with uncertainties

NASA Technical Reports Server (NTRS)

Shah, A. R.; Liaw, D. G.; Chamis, C. C.

1993-01-01

A reliability based design methodology for laminate sizing and configuration for a special case of composite structures is described. The methodology combines probabilistic composite mechanics with probabilistic structural analysis. The uncertainties of constituent materials (fiber and matrix) to predict macroscopic behavior are simulated using probabilistic theory. Uncertainties in the degradation of composite material properties are included in this design methodology. A multi-factor interaction equation is used to evaluate load and environment dependent degradation of the composite material properties at the micromechanics level. The methodology is integrated into a computer code IPACS (Integrated Probabilistic Assessment of Composite Structures). Versatility of this design approach is demonstrated by performing a multi-level probabilistic analysis to size the laminates for design structural reliability of random type structures. The results show that laminate configurations can be selected to improve the structural reliability from three failures in 1000, to no failures in one million. Results also show that the laminates with the highest reliability are the least sensitive to the loading conditions.

Multidisciplinary System Reliability Analysis

NASA Technical Reports Server (NTRS)

Mahadevan, Sankaran; Han, Song; Chamis, Christos C. (Technical Monitor)

2001-01-01

The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code, developed under the leadership of NASA Glenn Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multidisciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

Multi-Disciplinary System Reliability Analysis

NASA Technical Reports Server (NTRS)

Mahadevan, Sankaran; Han, Song

1997-01-01

The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code developed under the leadership of NASA Lewis Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multi-disciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

Development, validity and reliability of the short multidimensional positive mental health instrument.

PubMed

Vaingankar, Janhavi Ajit; Subramaniam, Mythily; Abdin, Edimansyah; Picco, Louisa; Chua, Boon Yiang; Eng, Goi Khia; Sambasivam, Rajeswari; Shafie, Saleha; Zhang, Yunjue; Chong, Siow Ann

2014-06-01

The 47-item positive mental health (PMH) instrument measures the level of PMH in multiethnic adult Asian populations. This study aimed to (1) develop a short PMH instrument and (2) establish its validity and reliability among the adult Singapore population. Two separate studies were conducted among adult community-dwelling Singapore residents of Chinese, Malay or Indian ethnicity where participants completed self-administered questionnaires. In the first study, secondary data analysis was conducted using confirmatory factor analysis (CFA) to shorten the PMH instrument. In the second study, the newly developed short PMH instrument and other scales were administered to 201 residents to establish its factor structure, validity and reliability. A 20-item short PMH instrument fulfilling a higher-order six-factor structure was developed following secondary analysis. The mean age of the participants in the second study was 41 years and about 53% were women. One item with poor factor loading was further removed to generate a 19-item version of the PMH instrument. CFA demonstrated a first-order six-factor model of the short PMH instrument. The PMH-19 instrument and its subscales fulfilled criterion validity hypotheses. Internal consistency and test-retest reliability of the PMH-19 instrument were high (Cronbach's α coefficient = 0.87; intraclass correlation coefficient = 0.93, respectively). The 19-item PMH instrument is multidimensional, valid and reliable, and most importantly, with its reduced administration time, the short PMH instrument can be used to measure and evaluate PMH in Asian communities.

A high reliability module with thermoelectric device by molding technology for M2M wireless sensor network

NASA Astrophysics Data System (ADS)

Nakagawa, K.; Tanaka, T.; Suzuki, T.

2015-10-01

This paper presents the fabrication of a new energy harvesting module that uses a thermoelectric device (TED) by using molding technology. Through molding technology, the TED and circuit board can be properly protected and a heat-radiating fin structure can be simultaneously constructed. The output voltage per heater temperature of the TED module at 20 °C ambient temperature is 8 mV K-1, similar to the result with the aluminum heat sink which is almost the same fin size as the TED module. The accelerated environmental tests are performed on a damp heat test, which is an aging test under high temperature and high humidity, highly accelerated temperature, and humidity stress test (HAST) for the purpose of evaluating the electrical reliability in harsh environments, cold test and thermal cycle test to evaluate degrading characteristics by cycling through two temperatures. All test results indicate that the TED and circuit board can be properly protected from harsh temperature and humidity by using molding technology because the output voltage of after-tested modules is reduced by less than 5%. This study presents a novel fabrication method for a high reliability TED-installed module appropriate for Machine to Machine wireless sensor networks.

The Experiences in Close Relationship Scale (ECR)-short form: reliability, validity, and factor structure.

PubMed

Wei, Meifen; Russell, Daniel W; Mallinckrodt, Brent; Vogel, David L

2007-04-01

We developed a 12-item, short form of the Experiences in Close Relationship Scale (ECR; Brennan, Clark, & Shaver, 1998) across 6 studies. In Study 1, we examined the reliability and factor structure of the measure. In Studies 2 and 3, we cross-validated the reliability, factor structure, and validity of the short form measure; whereas in Study 4, we examined test-retest reliability over a 1-month period. In Studies 5 and 6, we further assessed the reliability, factor structure, and validity of the short version of the ECR when administered as a stand-alone instrument. Confirmatory factor analyses indicated that 2 factors, labeled Anxiety and Avoidance, provided a good fit to the data after removing the influence of response sets. We found validity to be equivalent for the short and the original versions of the ECR across studies. Finally, the results were comparable when we embedded the short form within the original version of the ECR and when we administered it as a stand-alone measure.

Reliability of a structured interview for admission to an emergency medicine residency program.

PubMed

Blouin, Danielle

2010-10-01

Interviews are most important in resident selection. Structured interviews are more reliable than unstructured ones. We sought to measure the interrater reliability of a newly designed structured interview during the selection process to an Emergency Medicine residency program. The critical incident technique was used to extract the desired dimensions of performance. The interview tool consisted of 7 clinical scenarios and 1 global rating. Three trained interviewers marked each candidate on all scenarios without discussing candidates' responses. Interitem consistency and estimates of variance were computed. Twenty-eight candidates were interviewed. The generalizability coefficient was 0.67. Removing the central tendency ratings increased the coefficient to 0.74. Coefficients of interitem consistency ranged from 0.64 to 0.74. The structured interview tool provided good although suboptimal interrater reliability. Increasing the number of scenarios improves reliability as does applying differential weights to the rating scale anchors. The latter would also facilitate the identification of those candidates with extreme ratings.

A novel method for finding the initial structure parameters of optical systems via a genetic algorithm

NASA Astrophysics Data System (ADS)

Jun, LIU; Huang, Wei; Hongjie, Fan

2016-02-01

A novel method for finding the initial structure parameters of an optical system via the genetic algorithm (GA) is proposed in this research. Usually, optical designers start their designs from the commonly used structures from a patent database; however, it is time consuming to modify the patented structures to meet the specification. A high-performance design result largely depends on the choice of the starting point. Accordingly, it would be highly desirable to be able to calculate the initial structure parameters automatically. In this paper, a method that combines a genetic algorithm and aberration analysis is used to determine an appropriate initial structure of an optical system. We use a three-mirror system as an example to demonstrate the validity and reliability of this method. On-axis and off-axis telecentric three-mirror systems are obtained based on this method.

Plate and butt-weld stresses beyond elastic limit, material and structural modeling

NASA Technical Reports Server (NTRS)

Verderaime, V.

1991-01-01

Ultimate safety factors of high performance structures depend on stress behavior beyond the elastic limit, a region not too well understood. An analytical modeling approach was developed to gain fundamental insights into inelastic responses of simple structural elements. Nonlinear material properties were expressed in engineering stresses and strains variables and combined with strength of material stress and strain equations similar to numerical piece-wise linear method. Integrations are continuous which allows for more detailed solutions. Included with interesting results are the classical combined axial tension and bending load model and the strain gauge conversion to stress beyond the elastic limit. Material discontinuity stress factors in butt-welds were derived. This is a working-type document with analytical methods and results applicable to all industries of high reliability structures.

The Role of Phase Changes in TiO2/Pt/TiO2 Filaments

NASA Astrophysics Data System (ADS)

Bíró, Ferenc; Hajnal, Zoltán; Dücső, Csaba; Bársony, István

2018-04-01

This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance ( R) versus temperature ( T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.

Study of fail-safe abort system for an actively cooled hypersonic aircraft, volume 2

NASA Technical Reports Server (NTRS)

Peeples, M. E.; Herring, R. L.

1976-01-01

Conceptual designs of a fail-safe abort system for hydrogen fueled actively cooled high speed aircraft are examined. The fail-safe concept depends on basically three factors: (1) a reliable method of detecting a failure or malfunction in the active cooling system, (2) the optimization of abort trajectories which minimize the descent heat load to the aircraft, and (3) fail-safe thermostructural concepts to minimize both the weight and the maximum temperature the structure will reach during descent. These factors are examined and promising approaches are evaluated based on weight, reliability, ease of manufacture and cost.

Reducing Bolt Preload Variation with Angle-of-Twist Bolt Loading

NASA Technical Reports Server (NTRS)

Thompson, Bryce; Nayate, Pramod; Smith, Doug; McCool, Alex (Technical Monitor)

2001-01-01

Critical high-pressure sealing joints on the Space Shuttle reusable solid rocket motor require precise control of bolt preload to ensure proper joint function. As the reusable solid rocket motor experiences rapid internal pressurization, correct bolt preloads maintain the sealing capability and structural integrity of the hardware. The angle-of-twist process provides the right combination of preload accuracy, reliability, process control, and assembly-friendly design. It improves significantly over previous methods. The sophisticated angle-of-twist process controls have yielded answers to all discrepancies encountered while the simplicity of the root process has assured joint preload reliability.

Psychometric Evaluation of the Wang Pregnancy Stress Scale: Revised for Taiwanese Women.

PubMed

Wang, Janet F; Billings, Anthony A

2015-01-01

Develop and assess psychometric properties of the Wang Pregnancy Stress Scale for measuring stress among pregnant women in Taiwan. Data were collected in 3 obstetric and gynecological clinics in Taiwan; 485 pregnant women participated in this study. We used exploratory factor analysis and internal consistency reliability was measured using Cronbach's alpha. A 4-factor structure emerged for the Wang Pregnancy Stress Scale. The internal reliability of the scale as measured by Cronbach's alpha was .898, with standardized alpha .905. The Wang Pregnancy Stress Scale has high reliability and validity in measuring pregnancy stress that would allow nurses or health care workers to measure women's stress levels during pregnancy. Nurses can use the assessed pregnancy stress to alter intervention of care for their pregnant clients.

Standardization of the Hare Psychopathy Checklist-Revised in a Spanish prison sample.

PubMed

Moltó, J; Poy, R; Torrubia, R

2000-01-01

This investigation examined the reliability, validity, and factor structure of the Hare Psychopathy Checklist-Revised (PCL-R) in male adult Spanish prison populations (n = 117). The interrater reliability and internal consistency coefficients were high, and similar to those obtained in other countries. This data provides support for the homogeneity and unidimensionality of the psychopathy construct in Spanish male prison samples. The analysis of factor structure also replicated the two factor solution of previous studies. The two factors showed different patterns of intercorrelations with several self-report measures of personality, demographic, and criminal history variables, which confirmed the construct validity of PCL-R. The results confirm the psychometric properties of the PCL-R as a measure of psychopathy in Spanish male inmates, and suggest that psychopathy is a construct also observed in Southern European countries.

Structural Probability Concepts Adapted to Electrical Engineering

NASA Technical Reports Server (NTRS)

Steinberg, Eric P.; Chamis, Christos C.

1994-01-01

Through the use of equivalent variable analogies, the authors demonstrate how an electrical subsystem can be modeled by an equivalent structural subsystem. This allows the electrical subsystem to be probabilistically analyzed by using available structural reliability computer codes such as NESSUS. With the ability to analyze the electrical subsystem probabilistically, we can evaluate the reliability of systems that include both structural and electrical subsystems. Common examples of such systems are a structural subsystem integrated with a health-monitoring subsystem, and smart structures. Since these systems have electrical subsystems that directly affect the operation of the overall system, probabilistically analyzing them could lead to improved reliability and reduced costs. The direct effect of the electrical subsystem on the structural subsystem is of secondary order and is not considered in the scope of this work.

Relational, Structural, and Semantic Analysis of Graphical Representations and Concept Maps

ERIC Educational Resources Information Center

Ifenthaler, Dirk

2010-01-01

The demand for good instructional environments presupposes valid and reliable analytical instruments for educational research. This paper introduces the "SMD Technology" (Surface, Matching, Deep Structure), which measures relational, structural, and semantic levels of graphical representations and concept maps. The reliability and validity of the…

Development of Korean Smartphone addiction proneness scale for youth.

PubMed

Kim, Dongil; Lee, Yunhee; Lee, Juyoung; Nam, JeeEun Karin; Chung, Yeoju

2014-01-01

This study developed a Smartphone Addiction Proneness Scale (SAPS) based on the existing internet and cellular phone addiction scales. For the development of this scale, 29 items (1.5 times the final number of items) were initially selected as preliminary items, based on the previous studies on internet/phone addiction as well as the clinical experience of involved experts. The preliminary scale was administered to a nationally representative sample of 795 students in elementary, middle, and high schools across South Korea. Then, final 15 items were selected according to the reliability test results. The final scale consisted of four subdomains: (1) disturbance of adaptive functions, (2) virtual life orientation, (3) withdrawal, and (4) tolerance. The final scale indicated a high reliability with Cronbach's α of .880. Support for the scale's criterion validity has been demonstrated by its relationship to the internet addiction scale, KS-II (r  =  .49). For the analysis of construct validity, we tested the Structural Equation Model. The results showed the four-factor structure to be valid (NFI  =  .943, TLI  =  .902, CFI  =  .902, RMSEA  =  .034). Smartphone addiction is gaining a greater spotlight as possibly a new form of addiction along with internet addiction. The SAPS appears to be a reliable and valid diagnostic scale for screening adolescents who may be at risk of smartphone addiction. Further implications and limitations are discussed.

Development of Korean Smartphone Addiction Proneness Scale for Youth

PubMed Central

Kim, Dongil; Lee, Yunhee; Lee, Juyoung; Nam, JeeEun Karin; Chung, Yeoju

2014-01-01

This study developed a Smartphone Addiction Proneness Scale (SAPS) based on the existing internet and cellular phone addiction scales. For the development of this scale, 29 items (1.5 times the final number of items) were initially selected as preliminary items, based on the previous studies on internet/phone addiction as well as the clinical experience of involved experts. The preliminary scale was administered to a nationally representative sample of 795 students in elementary, middle, and high schools across South Korea. Then, final 15 items were selected according to the reliability test results. The final scale consisted of four subdomains: (1) disturbance of adaptive functions, (2) virtual life orientation, (3) withdrawal, and (4) tolerance. The final scale indicated a high reliability with Cronbach's α of .880. Support for the scale's criterion validity has been demonstrated by its relationship to the internet addiction scale, KS-II (r  =  .49). For the analysis of construct validity, we tested the Structural Equation Model. The results showed the four-factor structure to be valid (NFI  =  .943, TLI  =  .902, CFI  =  .902, RMSEA  =  .034). Smartphone addiction is gaining a greater spotlight as possibly a new form of addiction along with internet addiction. The SAPS appears to be a reliable and valid diagnostic scale for screening adolescents who may be at risk of smartphone addiction. Further implications and limitations are discussed. PMID:24848006

Analysis of the Seismic Performance of Isolated Buildings according to Life-Cycle Cost

PubMed Central

Dang, Yu; Han, Jian-ping; Li, Yong-tao

2015-01-01

This paper proposes an indicator of seismic performance based on life-cycle cost of a building. It is expressed as a ratio of lifetime damage loss to life-cycle cost and determines the seismic performance of isolated buildings. Major factors are considered, including uncertainty in hazard demand and structural capacity, initial costs, and expected loss during earthquakes. Thus, a high indicator value indicates poor building seismic performance. Moreover, random vibration analysis is conducted to measure structural reliability and evaluate the expected loss and life-cycle cost of isolated buildings. The expected loss of an actual, seven-story isolated hospital building is only 37% of that of a fixed-base building. Furthermore, the indicator of the structural seismic performance of the isolated building is much lower in value than that of the structural seismic performance of the fixed-base building. Therefore, isolated buildings are safer and less risky than fixed-base buildings. The indicator based on life-cycle cost assists owners and engineers in making investment decisions in consideration of structural design, construction, and expected loss. It also helps optimize the balance between building reliability and building investment. PMID:25653677

Analysis of the seismic performance of isolated buildings according to life-cycle cost.

PubMed

Dang, Yu; Han, Jian-Ping; Li, Yong-Tao

2015-01-01

This paper proposes an indicator of seismic performance based on life-cycle cost of a building. It is expressed as a ratio of lifetime damage loss to life-cycle cost and determines the seismic performance of isolated buildings. Major factors are considered, including uncertainty in hazard demand and structural capacity, initial costs, and expected loss during earthquakes. Thus, a high indicator value indicates poor building seismic performance. Moreover, random vibration analysis is conducted to measure structural reliability and evaluate the expected loss and life-cycle cost of isolated buildings. The expected loss of an actual, seven-story isolated hospital building is only 37% of that of a fixed-base building. Furthermore, the indicator of the structural seismic performance of the isolated building is much lower in value than that of the structural seismic performance of the fixed-base building. Therefore, isolated buildings are safer and less risky than fixed-base buildings. The indicator based on life-cycle cost assists owners and engineers in making investment decisions in consideration of structural design, construction, and expected loss. It also helps optimize the balance between building reliability and building investment.

Nickel-free austenitic stainless steels for medical applications.

PubMed

Yang, Ke; Ren, Yibin

2010-02-01

The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength and good plasticity, better corrosion and wear resistances, and superior biocompatibility compared to the currently used 316L stainless steel, the newly developed high-nitrogen nickel-free stainless steel is a reliable substitute for the conventional medical stainless steels.

Nickel-free austenitic stainless steels for medical applications

PubMed Central

Yang, Ke; Ren, Yibin

2010-01-01

The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength and good plasticity, better corrosion and wear resistances, and superior biocompatibility compared to the currently used 316L stainless steel, the newly developed high-nitrogen nickel-free stainless steel is a reliable substitute for the conventional medical stainless steels. PMID:27877320

Enhanced fatigue endurance of metallic glasses through a staircase-like fracture mechanism.

PubMed

Gludovatz, Bernd; Demetriou, Marios D; Floyd, Michael; Hohenwarter, Anton; Johnson, William L; Ritchie, Robert O

2013-11-12

Bulk-metallic glasses (BMGs) are now candidate materials for structural applications due to their exceptional strength and toughness. However, their fatigue resistance can be poor and inconsistent, severely limiting their potential as reliable structural materials. As fatigue limits are invariably governed by the local arrest of microscopically small cracks at microstructural features, the lack of microstructure in monolithic glasses, often coupled with other factors, such as the ease of crack formation in shear bands or a high susceptibility to corrosion, can lead to low fatigue limits (some ~1/20 of their tensile strengths) and highly variable fatigue lives. BMG-matrix composites can provide a solution here as their duplex microstructures can arrest shear bands at a second phase to prevent cracks from exceeding critical size; under these conditions, fatigue limits become comparable with those of crystalline alloys. Here, we report on a Pd-based glass that similarly has high fatigue resistance but without a second phase. This monolithic glass displays high intrinsic toughness from extensive shear-band proliferation with cavitation and cracking effectively obstructed. We find that this property can further promote fatigue resistance through extrinsic crack-tip shielding, a mechanism well known in crystalline metals but not previously reported in BMGs, whereby cyclically loaded cracks propagate in a highly "zig-zag" manner, creating a rough "staircase-like" profile. The resulting crack-surface contact (roughness-induced crack closure) elevates fatigue properties to those comparable to crystalline alloys, and the accompanying plasticity helps to reduce flaw sensitivity in the glass, thereby promoting structural reliability.

Enhanced fatigue endurance of metallic glasses through a staircase-like fracture mechanism

PubMed Central

Gludovatz, Bernd; Demetriou, Marios D.; Floyd, Michael; Hohenwarter, Anton; Johnson, William L.; Ritchie, Robert O.

2013-01-01

Bulk-metallic glasses (BMGs) are now candidate materials for structural applications due to their exceptional strength and toughness. However, their fatigue resistance can be poor and inconsistent, severely limiting their potential as reliable structural materials. As fatigue limits are invariably governed by the local arrest of microscopically small cracks at microstructural features, the lack of microstructure in monolithic glasses, often coupled with other factors, such as the ease of crack formation in shear bands or a high susceptibility to corrosion, can lead to low fatigue limits (some ∼1/20 of their tensile strengths) and highly variable fatigue lives. BMG-matrix composites can provide a solution here as their duplex microstructures can arrest shear bands at a second phase to prevent cracks from exceeding critical size; under these conditions, fatigue limits become comparable with those of crystalline alloys. Here, we report on a Pd-based glass that similarly has high fatigue resistance but without a second phase. This monolithic glass displays high intrinsic toughness from extensive shear-band proliferation with cavitation and cracking effectively obstructed. We find that this property can further promote fatigue resistance through extrinsic crack-tip shielding, a mechanism well known in crystalline metals but not previously reported in BMGs, whereby cyclically loaded cracks propagate in a highly “zig-zag” manner, creating a rough “staircase-like” profile. The resulting crack-surface contact (roughness-induced crack closure) elevates fatigue properties to those comparable to crystalline alloys, and the accompanying plasticity helps to reduce flaw sensitivity in the glass, thereby promoting structural reliability. PMID:24167284

Movement sense determination in sheared rocks

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

Simpson, C.

1985-01-01

Deformation within fault zones produces sheared rocks that range from cataclasites at high structural level, to mylonites and mylonitic gneiss at deeper levels. These rocks are easily recognized and mapped in the field and the strike and dip of the fault zone established. However, present-day geometry of the fault zone does not necessarily indicate relative motion - a zone dipping at 15/sup 0/ could represent a listric normal, thrust, oblique-slip or tilted strike-slip fault. Where offset stratigraphic or lithological markers are absent, the movement sense may be determined from meso- and micro-structural features within the sheared rocks. Of prime importancemore » is the orientation of mineral elongation or stretching lineations which record the finite X direction of strain in the rock; this direction approaches the bulk movement direction with increase in strain. At mesoscopic scale the most reliable shear sense indicators are shear bands and associated features. Use of fold vergence requires caution. On a micro-structural scale, shear bands, mica fish, microfolds, rotated grains, asymmetrical augen structure and fiber growth patterns all give reliable results. Thin sections should be cut parallel to lineation and perpendicular to foliation in order to view maximum rotational component. Asymmetry of crystallographic fabric patterns gives consistent results in zones of relatively simple movement history. For high confidence shear sense determination, all structural elements should be internally consistent. If inconsistency occurs this may indicate a complex, multidirectional movement history for the fault zone.« less

High-power laser diodes at various wavelengths

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

Emanuel, M.A.

High power laser diodes at various wavelengths are described. First, performance and reliability of an optimized large transverse mode diode structure at 808 and 941 nm are presented. Next, data are presented on a 9.5 kW peak power array at 900 nm having a narrow emission bandwidth suitable for pumping Yb:S-FAP laser materials. Finally, results on a fiber-coupled laser diode array at {approx}730 nm are presented.

Structural reliability calculation method based on the dual neural network and direct integration method.

PubMed

Li, Haibin; He, Yun; Nie, Xiaobo

2018-01-01

Structural reliability analysis under uncertainty is paid wide attention by engineers and scholars due to reflecting the structural characteristics and the bearing actual situation. The direct integration method, started from the definition of reliability theory, is easy to be understood, but there are still mathematics difficulties in the calculation of multiple integrals. Therefore, a dual neural network method is proposed for calculating multiple integrals in this paper. Dual neural network consists of two neural networks. The neural network A is used to learn the integrand function, and the neural network B is used to simulate the original function. According to the derivative relationships between the network output and the network input, the neural network B is derived from the neural network A. On this basis, the performance function of normalization is employed in the proposed method to overcome the difficulty of multiple integrations and to improve the accuracy for reliability calculations. The comparisons between the proposed method and Monte Carlo simulation method, Hasofer-Lind method, the mean value first-order second moment method have demonstrated that the proposed method is an efficient and accurate reliability method for structural reliability problems.

Ceramic strengthening by tuning the elastic moduli of resin-based luting agents.

PubMed

Spazzin, Aloísio O; Bacchi, Ataís; Alessandretti, Rodrigo; Santos, Mateus B; Basso, Gabriela R; Griggs, Jason; Moraes, Rafael R

2017-03-01

Resin-based luting agents (RBLAs) with tuned elastic moduli (E) were prepared and their influence on the strengthening, reliability, and mode of failure of luted feldspar ceramic was investigated. RBLAs with low E (2.6GPa), intermediate E (6.6GPa), and high E (13.3GPa) were prepared and used to coat acid-etched ceramic disks. Positive (untreated ceramic) and negative (acid-etched ceramic) control groups were tested. The response variables (n=30) were biaxial flexural strength (σ bf , MPa), characteristic strength (σ 0 , MPa), and Weibull modulus at the ceramic surface (z=0) and luting agent surface (z=-t 2 ). A 3D finite element analysis simulated the biaxial flexural test. Fractographic analysis and morphology of the bonded interfaces were analyzed using scanning electron microscopy. The RBLAs improved σ bf and σ 0 at z=0, particularly those with intermediate and high E, whereas the mechanical reliability was only affected in the negative control. At z=-t 2 , differences between all RBLAs were observed but the structural reliability was independent of the RBLA tested. Increasing E of the RBLA was associated with increased stress concentration at the RBLA and reduced stresses reaching the ceramic. Failures originated on the ceramic surface at the ceramic-cement interface. In the high E group, failure sometimes originated from the RBLA free surface. All RBLAs completely filled the ceramic irregularities. Increased E of the RBLA reduced the variability of strength, the stress reaching the ceramic structure, and sometimes altered the origin of failure. The use of high E RBLAs seems beneficial for luting feldspar ceramics. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of Random Thermal Spikes on Stirling Convertor Heater Head Reliability

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Korovaichuk, Igor; Halford, Gary R.

2004-01-01

Onboard radioisotope power systems being developed to support future NASA exploration missions require reliable design lifetimes of up to 14 yr and beyond. The structurally critical heater head of the high-efficiency developmental Stirling power convertor has undergone extensive computational analysis of operating temperatures (up to 650 C), stresses, and creep resistance of the thin-walled Inconel 718 bill of material. Additionally, assessment of the effect of uncertainties in the creep behavior of the thin-walled heater head, the variation in the manufactured thickness, variation in control temperature, and variation in pressure on the durability and reliability were performed. However, it is possible for the heater head to experience rare incidences of random temperature spikes (excursions) of short duration. These incidences could occur randomly with random magnitude and duration during the desired mission life. These rare incidences could affect the creep strain rate and therefore the life. The paper accounts for these uncertainties and includes the effect of such rare incidences, random in nature, on the reliability. The sensitivities of variables affecting the reliability are quantified and guidelines developed to improve the reliability are outlined. Furthermore, the quantified reliability is being verified with test data from the accelerated benchmark tests being conducted at the NASA Glenn Research Center.

Reliability-Based Life Assessment of Stirling Convertor Heater Head

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Halford, Gary R.; Korovaichuk, Igor

2004-01-01

Onboard radioisotope power systems being developed and planned for NASA's deep-space missions require reliable design lifetimes of up to 14 yr. The structurally critical heater head of the high-efficiency Stirling power convertor has undergone extensive computational analysis of operating temperatures, stresses, and creep resistance of the thin-walled Inconel 718 bill of material. A preliminary assessment of the effect of uncertainties in the material behavior was also performed. Creep failure resistance of the thin-walled heater head could show variation due to small deviations in the manufactured thickness and in uncertainties in operating temperature and pressure. Durability prediction and reliability of the heater head are affected by these deviations from nominal design conditions. Therefore, it is important to include the effects of these uncertainties in predicting the probability of survival of the heater head under mission loads. Furthermore, it may be possible for the heater head to experience rare incidences of small temperature excursions of short duration. These rare incidences would affect the creep strain rate and, therefore, the life. This paper addresses the effects of such rare incidences on the reliability. In addition, the sensitivities of variables affecting the reliability are quantified, and guidelines developed to improve the reliability are outlined. Heater head reliability is being quantified with data from NASA Glenn Research Center's accelerated benchmark testing program.

Computer assisted Objective structured clinical examination versus Objective structured clinical examination in assessment of Dermatology undergraduate students.

PubMed

Chaudhary, Richa; Grover, Chander; Bhattacharya, S N; Sharma, Arun

2017-01-01

The assessment of dermatology undergraduates is being done through computer assisted objective structured clinical examination at our institution for the last 4 years. We attempted to compare objective structured clinical examination (OSCE) and computer assisted objective structured clinical examination (CA-OSCE) as assessment tools. To assess the relative effectiveness of CA-OSCE and OSCE as assessment tools for undergraduate dermatology trainees. Students underwent CA-OSCE as well as OSCE-based evaluation of equal weightage as an end of posting assessment. The attendance as well as the marks in both the examination formats were meticulously recorded and statistically analyzed using SPSS version 20.0. Intercooled Stata V9.0 was used to assess the reliability and internal consistency of the examinations conducted. Feedback from both students and examiners was also recorded. The mean attendance for the study group was 77% ± 12.0%. The average score on CA- OSCE and OSCE was 47.4% ± 19.8% and 53.5% ± 18%, respectively. These scores showed a mutually positive correlation, with Spearman's coefficient being 0.593. Spearman's rank correlation coefficient between attendance scores and assessment score was 0.485 for OSCE and 0.451 for CA-OSCE. The Cronbach's alpha coefficient for all the tests ranged from 0.76 to 0.87 indicating high reliability. The comparison was based on a single batch of 139 students. Such an evaluation on more students in larger number of batches over successive years could help throw more light on the subject. Computer assisted objective structured clinical examination was found to be a valid, reliable and effective format for dermatology assessment, being rated as the preferred format by examiners.

A strategy to improve the identification reliability of the chemical constituents by high-resolution mass spectrometry-based isomer structure prediction combined with a quantitative structure retention relationship analysis: Phthalide compounds in Chuanxiong as a test case.

PubMed

Zhang, Qingqing; Huo, Mengqi; Zhang, Yanling; Qiao, Yanjiang; Gao, Xiaoyan

2018-06-01

High-resolution mass spectrometry (HRMS) provides a powerful tool for the rapid analysis and identification of compounds in herbs. However, the diversity and large differences in the content of the chemical constituents in herbal medicines, especially isomerisms, are a great challenge for mass spectrometry-based structural identification. In the current study, a new strategy for the structural characterization of potential new phthalide compounds was proposed by isomer structure predictions combined with a quantitative structure-retention relationship (QSRR) analysis using phthalide compounds in Chuanxiong as an example. This strategy consists of three steps. First, the structures of phthalide compounds were reasonably predicted on the basis of the structure features and MS/MS fragmentation patterns: (1) the collected raw HRMS data were preliminarily screened by an in-house database; (2) the MS/MS fragmentation patterns of the analogous compounds were summarized; (3) the reported phthalide compounds were identified, and the structures of the isomers were reasonably predicted. Second, the QSRR model was established and verified using representative phthalide compound standards. Finally, the retention times of the predicted isomers were calculated by the QSRR model, and the structures of these peaks were rationally characterized by matching retention times of the detected chromatographic peaks and the predicted isomers. A multiple linear regression QSRR model in which 6 physicochemical variables were screened was built using 23 phthalide standards. The retention times of the phthalide isomers in Chuanxiong were well predicted by the QSRR model combined with reasonable structure predictions (R 2 =0.955). A total of 81 peaks were detected from Chuanxiong and assigned to reasonable structures, and 26 potential new phthalide compounds were structurally characterized. This strategy can improve the identification efficiency and reliability of homologues in complex materials. Copyright © 2018 Elsevier B.V. All rights reserved.

Design-for-reliability (DfR) of aerospace electronics: Attributes and challenges

NASA Astrophysics Data System (ADS)

Bensoussan, A.; Suhir, E.

The next generation of multi-beam satellite systems that would be able to provide effective interactive communication services will have to operate within a highly flexible architecture. One option to develop such flexibility is to employ microwaves and/or optoelectronic components and to make them reliable. The use of optoelectronic devices, equipments and systems will result indeed in significant improvement in the state-of-the-art only provided that the new designs will suggest a novel and effective architecture that will combine the merits of good functional performance, satisfactory mechanical (structural) reliability and high cost effectiveness. The obvious challenge is the ability to design and fabricate equipment based on EEE components that would be able to successfully withstand harsh space environments for the entire duration of the mission. It is imperative that the major players in the space industry, such as manufacturers, industrial users, and space agencies, understand the importance and the limits of the achievable quality and reliability of optoelectronic devices operated in harsh environments. It is equally imperative that the physics of possible failures is well understood and, if necessary, minimized, and that adequate Quality Standards are developed and employed. The space community has to identify and to develop the strategic approach for validating optoelectronic products. This should be done with consideration of numerous intrinsic and extrinsic requirements for the systems' performance. When considering a particular next generation optoelectronic space system, the space community needs to address the following major issues: proof of concept for this system, proof of reliability and proof of performance. This should be done with taking into account the specifics of the anticipated application. High operational reliability cannot be left to the prognostics and health monitoring/management (PHM) effort and stage, no matter how important and - ffective such an effort might be. Reliability should be pursued at all the stages of the equipment lifetime: design, product development, manufacturing, burn-in testing and, of course, subsequent PHM after the space apparatus is launched and operated.

The Cutting Edge of High-Temperature Composites

NASA Technical Reports Server (NTRS)

2006-01-01

NASA s Ultra-Efficient Engine Technology (UEET) program was formed in 1999 at Glenn Research Center to manage an important national propulsion program for the Space Agency. The UEET program s focus is on developing innovative technologies to enable intelligent, environmentally friendly, and clean-burning turbine engines capable of reducing harmful emissions while maintaining high performance and increasing reliability. Seven technology projects exist under the program, with each project working towards specific goals to provide new technology for propulsion. One of these projects, Materials and Structures for High Performance, is concentrating on developing and demonstrating advanced high-temperature materials to enable high-performance, high-efficiency, and environmentally compatible propulsion systems. Materials include ceramic matrix composite (CMC) combustor liners and turbine vanes, disk alloys, turbine airfoil material systems, high-temperature polymer matrix composites, and lightweight materials for static engine structures.

Does Changing Examiner Stations During UK Postgraduate Surgery Objective Structured Clinical Examinations Influence Examination Reliability and Candidates' Scores?

PubMed

Brennan, Peter A; Croke, David T; Reed, Malcolm; Smith, Lee; Munro, Euan; Foulkes, John; Arnett, Richard

2016-01-01

Objective structured clinical examinations (OSCE) are widely used for summative assessment in surgery. Despite standardizing these as much as possible, variation, including examiner scoring, can occur which may affect reliability. In study of a high-stakes UK postgraduate surgical OSCE, we investigated whether examiners changing stations once during a long examining day affected marking, reliability, and overall candidates' scores compared with examiners who examined the same scenario all day. An observational study of 18,262 examiner-candidate interactions from the UK Membership of the Royal College of Surgeons examination was carried at 3 Surgical Colleges across the United Kingdom. Scores between examiners were compared using analysis of variance. Examination reliability was assessed with Cronbach's alpha, and the comparative distribution of total candidates' scores for each day was evaluated using t-tests of unit-weighted z scores. A significant difference was found in absolute scores differences awarded in the morning and afternoon sessions between examiners who changed stations at lunchtime and those who did not (p < 0.001). No significant differences were found for the main effects of either broad content area (p = 0.290) or station content area (p = 0.450). The reliability of each day was not affected by examiner switching (p = 0.280). Overall, no difference was found in z-score distribution of total candidate scores and categories of examiner switching. This large study has found that although the range of marks awarded varied when examiners change OSCE stations, examination reliability and the likely candidate outcome were not affected. These results may have implications for examination design and examiner experience in surgical OSCEs and beyond. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

[Reliability and Validity of the Behavioral Check List for Preschool Children to Measure Attention Deficit Hyperactivity Behaviors].

PubMed

Tsuno, Kanami; Yoshimasu, Kouichi; Hayashi, Takashi; Tatsuta, Nozomi; Ito, Yuki; Kamijima, Michihiro; Nakai, Kunihiko

2018-01-01

Nowadays, attention deficit hyperactivity (ADH) problems are observed commonly among school-age children. However, questionnaires specific to ADH behaviors among preschool children are very few. The aim of this study was to investigate the reliability and validity of the 25-item Behavioral Check List (BCL), which was developed from interviews of parents with children who were diagnosed as having Attention-deficit/hyperactivity disorder (ADHD) and measures ADH behaviors in preschool age. We recruited 22 teachers from 10 nurseries/kindergartens in Miyagi Prefecture, Japan. A total of 138 preschool children were assessed using the BCL. To investigate inter-rater reliability, two teachers from each facility assess seven to twenty children in their class, and intraclass correlation coefficients (ICCs) were calculated. The teachers additionally answered questions in the 1/5-5 Caregiver-Teacher Report Form (C-TRF) to investigate the criterion validity of the BCL. To investigate structural validity, exploratory factor analysis with promax rotation and confirmatory factor analysis were performed. The internal consistency reliability of the BCL was good (α = 0.92) and correlation analyses also confirmed its excellent criterion validity. Although exploratory factor analysis for the BCL yielded a five-factor model that consisted of a factor structure different from that of the original one, the results were similar to the original six factors. The ICCs of the BCL were 0.38-0.99 and it was not high enough for inter-rater reliability in some facilities. However, there is a possibility to improve it by giving raters adequate explanations when using BCL. The present study showed acceptable levels of reliability and validity of the BCL among Japanese preschool children.

A psychometric investigation of the hypersexual disorder screening inventory among highly sexually active gay and bisexual men: an item response theory analysis.

PubMed

Parsons, Jeffrey T; Rendina, H Jonathon; Ventuneac, Ana; Cook, Karon F; Grov, Christian; Mustanski, Brian

2013-12-01

The Hypersexual Disorder Screening Inventory (HDSI) was designed as an instrument for the screening of hypersexuality by the American Psychiatric Association's taskforce for the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. Our study sought to conduct a psychometric analysis of the HDSI, including an investigation of its underlying structure and reliability utilizing item response theory (IRT) modeling, and an examination of its polythetic scoring criteria in comparison to a standard dimensionally based cutoff score. We examined a diverse group of 202 highly sexually active gay and bisexual men in New York City. We conducted psychometric analyses of the HDSI, including both confirmatory factor analysis of its structure and IRT analysis of the item and scale reliabilities. We utilized the HDSI. The HDSI adequately fit a single-factor solution, although there was evidence that two of the items may measure a second factor that taps into sex as a form of coping. The scale showed evidence of strong reliability across much of the continuum of hypersexuality, and results suggested that, in addition to the proposed polythetic scoring criteria, a cutoff score of 20 on the severity index might be used for preliminary classification of HD. The HDSI was found to be highly reliable, and results suggested that a unidimensional, quantitative conception of hypersexuality with a clinically relevant cutoff score may be more appropriate than a qualitative syndrome comprised of multiple distinct clusters of problems. However, we also found preliminary evidence that three clusters of symptoms may constitute an HD syndrome as opposed to the two clusters initially proposed. Future research is needed to determine which of these issues are characteristic of the hypersexuality and HD constructs themselves and which are more likely to be methodological artifacts of the HDSI. © 2013 International Society for Sexual Medicine.

A Comparison of Low and High Structure Practice for Learning Interactional Analysis Skills

ERIC Educational Resources Information Center

Davis, Matthew James

2011-01-01

Innovative training approaches in work domains such as professional athletics, aviation, and the military have shown that specific types of practice can reliably lead to higher levels of performance for the average professional. This study describes the development of an initial effort toward creating a similar practice method for psychotherapy…

Mississippi Scale for Combat-Related Posttraumatic Stress Disorder: Three Studies in Reliabilty and Validity.

ERIC Educational Resources Information Center

Keane, Terence M.; And Others

1988-01-01

Explored the psychometric properties of the Mississippi Scale for Combat-Related Posttraumatic Stress Disorder to assess its internal consistency and factor structure. Administered the test to Vietnam veterans seeking help at Veteran Centers. Demonstrated high test-retest reliability, sensitivity of .93, specificity .89, and overall hit rate .90…

Eliciting Proto-Imperatives and Proto-Declaratives in Children with Intellectual Disabilities

ERIC Educational Resources Information Center

Vandereet, Joke; Maes, Bea; Lembrechts, Dirk; Zink, Inge

2010-01-01

Background: Although high-structured elicitation tasks have been shown to be efficient means to sample communication in children with intellectual disabilities, their validity and reliability remain to be evaluated. The aims of this study were threefold: (i) to evaluate the eliciting potential, (ii) to examine the utterance forms of…

Blake's Development of the Number Words "One," "Two," and "Three"

ERIC Educational Resources Information Center

Palmer, Alexis; Baroody, Arthur J.

2011-01-01

A mother tracked her preschooler's number word development daily from 18 to 49 months of age. Naturalistic observations were supplemented with observations during structured (Kumon) training and microgenetic testing. The boy's everyday use of "two" did not become highly reliable and selective for 10 months (at 28 months), emerged later than that…

High Power Microwave Tube Reliability Study

DTIC Science & Technology

1976-08-01

Factors . . . . . ................ 67 1. Environmental Factors . . . . . . . . . a. Ground Fixed ...... .......... 67 b. Ground Mobile ...including cube structure and operating parameters as factors in the models but also environment and aplication . Initially, the tubes to be included in...instLllations. Mobile ground based and seagoing systems have minimum restrictions, spacecraft systems the maximum and airborne system Y 6 .*.. restrictionts

Psychometric Evaluation of Kingston Caregiver Stress Scale.

PubMed

Sadak, Tatiana; Korpak, Anna; Wright, Jacob D; Lee, Mee Kyung; Noel, Margaret; Buckwalter, Kathleen; Borson, Soo

2017-01-01

Standardized measurement of caregiver stress is a component of Medicare's new health care benefit supporting care planning for people with dementia. In this article we identify existing measures of caregiver stress, strain and burden and propose specific criteria for choosing tools that may be suitable for wide use in primary care settings. We reviewed 22 measures and identified one, the Kingston Caregiver Stress Scale (KCSS), which met all the proposed criteria but had not been studied in a U.S. We conducted a psychometric evaluation of KCSS to determine its potential usefulness as a care planning tool with a U.S. We examined the internal consistency, test-retest reliability, component structure, and relationship to depression and anxiety in 227 dementia caregivers at two U.S. sites. The KCSS has high internal consistency and test-retest reliability, a strong factor structure, and moderate to high correlations with caregiver depression and anxiety. KCSS is a good candidate for use as part of comprehensive care planning for people with dementia and their caregivers. Routine assessment of caregiver stress in clinical care may facilitate timely intervention and potentially improve both patient and caregiver outcomes.

[Development of Autogenic Training Clinical Effectiveness Scale (ATCES)].

PubMed

Ikezuki, Makoto; Miyauchi, Yuko; Yamaguchi, Hajime; Koshikawa, Fusako

2002-02-01

The purpose of the present study was to develop a scale measuring clinical effectiveness of autogenic training. In Study 1, 167 undergraduates completed a survey of items concerning physical and mental states, which were thought to vary in the course of autogenic training. With item and factor analyses, 20 items were selected, and the resulting scale (ATCES) had high discrimination and clear factor structure. In Study 2, reliability and concurrent and clinical validity of the scale were examined with three groups of respondents: 85 mentally healthy, 31 control, 13 clinical persons. The scale showed a high test-retest correlation (r = .83) and alpha coefficient (alpha = .86). ATCES had a Pearson correlation coefficient of r = .56 with General Health Questionnaire (GHQ-12), and r = .73 with trait anxiety (STAI-T). And ATCES successfully discriminated the mentally healthy and clinical groups in terms of clinical effectiveness. These results demonstrated high reliability and sufficient concurrent and clinical validity of the new scale.

Scale for positive aspects of caregiving experience: development, reliability, and factor structure.

PubMed

Kate, N; Grover, S; Kulhara, P; Nehra, R

2012-06-01

OBJECTIVE. To develop an instrument (Scale for Positive Aspects of Caregiving Experience [SPACE]) that evaluates positive caregiving experience and assess its psychometric properties. METHODS. Available scales which assess some aspects of positive caregiving experience were reviewed and a 50-item questionnaire with a 5-point rating was constructed. In all, 203 primary caregivers of patients with severe mental disorders were asked to complete the questionnaire. Internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity were evaluated. Principal component factor analysis was run to assess the factorial validity of the scale. RESULTS. The scale developed as part of the study was found to have good internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity. Principal component factor analysis yielded a 4-factor structure, which also had good test-retest reliability and cross-language reliability. There was a strong correlation between the 4 factors obtained. CONCLUSION. The SPACE developed as part of this study has good psychometric properties.

An Update on the Clinical Utility of the Children's Post-Traumatic Cognitions Inventory.

PubMed

McKinnon, Anna; Smith, Patrick; Bryant, Richard; Salmon, Karen; Yule, William; Dalgleish, Tim; Dixon, Clare; Nixon, Reginald D V; Meiser-Stedman, Richard

2016-06-01

The Children's Post-Traumatic Cognitions Inventory (CPTCI) is a self-report questionnaire that measures maladaptive cognitions in children and young people following exposure to trauma. In this study, the psychometric properties of the CPTCI were examined in further detail with the objective of furthering its utility as a clinical tool. Specifically, we investigated the CPTCI's discriminant validity, test-retest reliability, and the potential for the development of a short form of the measure. Three samples (London, East Anglia, Australia) of children and young people exposed to trauma (N = 535; 7-17 years old) completed the CPTCI and a structured clinical interview to measure posttraumatic stress disorder (PTSD) symptoms between 1 and 6 months following trauma. Test-retest reliability was investigated in a subsample of 203 cases. The results showed that a score in the range of 46 to 48 on the CPTCI was indicative of clinically significant appraisals as determined by the presence of PTSD. The measure also had moderate-to-high test-retest reliability (r = .78) over a 2-month period. The Children's Post-Traumatic Cognitions Inventory-Short Form (CPTCI-S) had excellent internal consistency (α = .92), and moderate-to-high test-retest reliability (r = .78). The examination of construct validity showed the model had an excellent fitting factor structure (Comparative Fit index = 0.95, Tucker-Lewis index = 0.91, Root Mean Square Error of Approximation = .07). A score ranging from 16 to 18 was the best cutoff point on the CPTCI-S, in that it was indicative of clinically significant appraisals as determined by the presence of PTSD. Based on these results, we concluded that the CPTCI is a useful tool to support the practice of clinicians and that the CPTCI-S has excellent psychometric properties. Copyright © 2016 International Society for Traumatic Stress Studies.

Monolithic solid-state lasers for spaceflight

NASA Astrophysics Data System (ADS)

Krainak, Michael A.; Yu, Anthony W.; Stephen, Mark A.; Merritt, Scott; Glebov, Leonid; Glebova, Larissa; Ryasnyanskiy, Aleksandr; Smirnov, Vadim; Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

2015-02-01

A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state lasers.

Optimal periodic proof test based on cost-effective and reliability criteria

NASA Technical Reports Server (NTRS)

Yang, J.-N.

1976-01-01

An exploratory study for the optimization of periodic proof tests for fatigue-critical structures is presented. The optimal proof load level and the optimal number of periodic proof tests are determined by minimizing the total expected (statistical average) cost, while the constraint on the allowable level of structural reliability is satisfied. The total expected cost consists of the expected cost of proof tests, the expected cost of structures destroyed by proof tests, and the expected cost of structural failure in service. It is demonstrated by numerical examples that significant cost saving and reliability improvement for fatigue-critical structures can be achieved by the application of the optimal periodic proof test. The present study is relevant to the establishment of optimal maintenance procedures for fatigue-critical structures.

Mid-frequency Band Dynamics of Large Space Structures

NASA Technical Reports Server (NTRS)

Coppolino, Robert N.; Adams, Douglas S.

2004-01-01

High and low intensity dynamic environments experienced by a spacecraft during launch and on-orbit operations, respectively, induce structural loads and motions, which are difficult to reliably predict. Structural dynamics in low- and mid-frequency bands are sensitive to component interface uncertainty and non-linearity as evidenced in laboratory testing and flight operations. Analytical tools for prediction of linear system response are not necessarily adequate for reliable prediction of mid-frequency band dynamics and analysis of measured laboratory and flight data. A new MATLAB toolbox, designed to address the key challenges of mid-frequency band dynamics, is introduced in this paper. Finite-element models of major subassemblies are defined following rational frequency-wavelength guidelines. For computational efficiency, these subassemblies are described as linear, component mode models. The complete structural system model is composed of component mode subassemblies and linear or non-linear joint descriptions. Computation and display of structural dynamic responses are accomplished employing well-established, stable numerical methods, modern signal processing procedures and descriptive graphical tools. Parametric sensitivity and Monte-Carlo based system identification tools are used to reconcile models with experimental data and investigate the effects of uncertainties. Models and dynamic responses are exported for employment in applications, such as detailed structural integrity and mechanical-optical-control performance analyses.

A systematic review of the factor structure and reliability of the Spence Children's Anxiety Scale.

PubMed

Orgilés, Mireia; Fernández-Martínez, Iván; Guillén-Riquelme, Alejandro; Espada, José P; Essau, Cecilia A

2016-01-15

The Spence Children's Anxiety Scale (SCAS) is a widely used instrument for assessing symptoms of anxiety disorders among children and adolescents. Previous studies have demonstrated its good reliability for children and adolescents from different backgrounds. However, remarkable variability in the reliability of the SCAS across studies and inconsistent results regarding its factor structure has been found. The present study aims to examine the SCAS factor structure by means of a systematic review with narrative synthesis, the mean reliability of the SCAS by means of a meta-analysis, and the influence of the moderators on the SCAS reliability. Databases employed to collect the studies included Scholar Google, PsycARTICLES, PsycINFO, Web of Science, and Scopus since 1997. Twenty-nine and 32 studies, which examined the factor structure and the internal consistency of the SCAS, respectively, were included. The SCAS was found to have strong internal consistency, influenced by different moderators. The systematic review demonstrated that the original six-factor model was supported by most studies. Factorial invariance studies (across age, gender, country) and test-retest reliability of the SCAS were not examined in this study. It is concluded that the SCAS is a reliable instrument for cross-cultural use, and it is suggested that the original six-factor model is appropriate for cross-cultural application. Copyright © 2015 Elsevier B.V. All rights reserved.

Integrity management of offshore structures and its implication on computation of structural action effects and resistance

NASA Astrophysics Data System (ADS)

Moan, T.

2017-12-01

An overview of integrity management of offshore structures, with emphasis on the oil and gas energy sector, is given. Based on relevant accident experiences and means to control the associated risks, accidents are categorized from a technical-physical as well as human and organizational point of view. Structural risk relates to extreme actions as well as structural degradation. Risk mitigation measures, including adequate design criteria, inspection, repair and maintenance as well as quality assurance and control of engineering processes, are briefly outlined. The current status of risk and reliability methodology to aid decisions in the integrity management is briefly reviewed. Finally, the need to balance the uncertainties in data, methods and computational efforts and the cautious use and quality assurance and control in applying high fidelity methods to avoid human errors, is emphasized, and with a plea to develop both high fidelity as well as efficient, simplified methods for design.

Development and validation of the ASPIRE-VA coaching fidelity checklist (ACFC): a tool to help ensure delivery of high-quality weight management interventions.

PubMed

Damschroder, Laura J; Goodrich, David E; Kim, Hyungjin Myra; Holleman, Robert; Gillon, Leah; Kirsh, Susan; Richardson, Caroline R; Lutes, Lesley D

2016-09-01

Practical and valid instruments are needed to assess fidelity of coaching for weight loss. The purpose of this study was to develop and validate the ASPIRE Coaching Fidelity Checklist (ACFC). Classical test theory guided ACFC development. Principal component analyses were used to determine item groupings. Psychometric properties, internal consistency, and inter-rater reliability were evaluated for each subscale. Criterion validity was tested by predicting weight loss as a function of coaching fidelity. The final 19-item ACFC consists of two domains (session process and session structure) and five subscales (sets goals and monitor progress, assess and personalize self-regulatory content, manages the session, creates a supportive and empathetic climate, and stays on track). Four of five subscales showed high internal consistency (Cronbach alphas > 0.70) for group-based coaching; only two of five subscales had high internal reliability for phone-based coaching. All five sub-scales were positively and significantly associated with weight loss for group- but not for phone-based coaching. The ACFC is a reliable and valid instrument that can be used to assess fidelity and guide skill-building for weight management interventionists.

Psychometric Properties of Difficulties of Working with Patients with Personality Disorders and Attitudes Towards Patients with Personality Disorders Scales.

PubMed

Eren, Nurhan

2014-12-01

In this study, we aimed to develop two reliable and valid assessment instruments for investigating the level of difficulties mental health workers experience while working with patients with personality disorders and the attitudes they develop tt the patients. The research was carried out based on the general screening model. The study sample consisted of 332 mental health workers in several mental health clinics of Turkey, with a certain amount of experience in working with personality disorders, who were selected with a random assignment method. In order to collect data, the Personal Information Questionnaire, Difficulty of Working with Personality Disorders Scale (PD-DWS), and Attitudes Towards Patients with Personality Disorders Scale (PD-APS), which are being examined for reliability and validity, were applied. To determine construct validity, the Adjective Check List, Maslach Burnout Inventory, and State and Trait Anxiety Inventory were used. Explanatory factor analysis was used for investigating the structural validity, and Cronbach alpha, Spearman-Brown, Guttman Split-Half reliability analyses were utilized to examine the reliability. Also, item reliability and validity computations were carried out by investigating the corrected item-total correlations and discriminative indexes of the items in the scales. For the PD-DWS KMO test, the value was .946; also, a significant difference was found for the Bartlett sphericity test (p<.001). The computed test-retest coefficient reliability was .702; the Cronbach alpha value of the total test score was .952. For PD-APS KMO, the value was .925; a significant difference was found in Bartlett sphericity test (p<.001); the computed reliability coefficient based on continuity was .806; and the Cronbach alpha value of the total test score was .913. Analyses on both scales were based on total scores. It was found that PD-DWS and PD-APS have good psychometric properties, measuring the structure that is being investigated, are compatible with other scales, have high levels of internal reliability between their items, and are consistent across time. Therefore, it was concluded that both scales are valid and reliable instruments.

Probabilistic and structural reliability analysis of laminated composite structures based on the IPACS code

NASA Technical Reports Server (NTRS)

Sobel, Larry; Buttitta, Claudio; Suarez, James

1993-01-01

Probabilistic predictions based on the Integrated Probabilistic Assessment of Composite Structures (IPACS) code are presented for the material and structural response of unnotched and notched, 1M6/3501-6 Gr/Ep laminates. Comparisons of predicted and measured modulus and strength distributions are given for unnotched unidirectional, cross-ply, and quasi-isotropic laminates. The predicted modulus distributions were found to correlate well with the test results for all three unnotched laminates. Correlations of strength distributions for the unnotched laminates are judged good for the unidirectional laminate and fair for the cross-ply laminate, whereas the strength correlation for the quasi-isotropic laminate is deficient because IPACS did not yet have a progressive failure capability. The paper also presents probabilistic and structural reliability analysis predictions for the strain concentration factor (SCF) for an open-hole, quasi-isotropic laminate subjected to longitudinal tension. A special procedure was developed to adapt IPACS for the structural reliability analysis. The reliability results show the importance of identifying the most significant random variables upon which the SCF depends, and of having accurate scatter values for these variables.

Researcher Biographies

Science.gov Websites

interest: mechanical system design sensitivity analysis and optimization of linear and nonlinear structural systems, reliability analysis and reliability-based design optimization, computational methods in committee member, ISSMO; Associate Editor, Mechanics Based Design of Structures and Machines; Associate

Reliability Analysis and Reliability-Based Design Optimization of Circular Composite Cylinders Under Axial Compression

NASA Technical Reports Server (NTRS)

Rais-Rohani, Masoud

2001-01-01

This report describes the preliminary results of an investigation on component reliability analysis and reliability-based design optimization of thin-walled circular composite cylinders with average diameter and average length of 15 inches. Structural reliability is based on axial buckling strength of the cylinder. Both Monte Carlo simulation and First Order Reliability Method are considered for reliability analysis with the latter incorporated into the reliability-based structural optimization problem. To improve the efficiency of reliability sensitivity analysis and design optimization solution, the buckling strength of the cylinder is estimated using a second-order response surface model. The sensitivity of the reliability index with respect to the mean and standard deviation of each random variable is calculated and compared. The reliability index is found to be extremely sensitive to the applied load and elastic modulus of the material in the fiber direction. The cylinder diameter was found to have the third highest impact on the reliability index. Also the uncertainty in the applied load, captured by examining different values for its coefficient of variation, is found to have a large influence on cylinder reliability. The optimization problem for minimum weight is solved subject to a design constraint on element reliability index. The methodology, solution procedure and optimization results are included in this report.

Spatial Correlations in Natural Scenes Modulate Response Reliability in Mouse Visual Cortex

PubMed Central

Rikhye, Rajeev V.

2015-01-01

Intrinsic neuronal variability significantly limits information encoding in the primary visual cortex (V1). Certain stimuli can suppress this intertrial variability to increase the reliability of neuronal responses. In particular, responses to natural scenes, which have broadband spatiotemporal statistics, are more reliable than responses to stimuli such as gratings. However, very little is known about which stimulus statistics modulate reliable coding and how this occurs at the neural ensemble level. Here, we sought to elucidate the role that spatial correlations in natural scenes play in reliable coding. We developed a novel noise-masking method to systematically alter spatial correlations in natural movies, without altering their edge structure. Using high-speed two-photon calcium imaging in vivo, we found that responses in mouse V1 were much less reliable at both the single neuron and population level when spatial correlations were removed from the image. This change in reliability was due to a reorganization of between-neuron correlations. Strongly correlated neurons formed ensembles that reliably and accurately encoded visual stimuli, whereas reducing spatial correlations reduced the activation of these ensembles, leading to an unreliable code. Together with an ensemble-specific normalization model, these results suggest that the coordinated activation of specific subsets of neurons underlies the reliable coding of natural scenes. SIGNIFICANCE STATEMENT The natural environment is rich with information. To process this information with high fidelity, V1 neurons have to be robust to noise and, consequentially, must generate responses that are reliable from trial to trial. While several studies have hinted that both stimulus attributes and population coding may reduce noise, the details remain unclear. Specifically, what features of natural scenes are important and how do they modulate reliability? This study is the first to investigate the role of spatial correlations, which are a fundamental attribute of natural scenes, in shaping stimulus coding by V1 neurons. Our results provide new insights into how stimulus spatial correlations reorganize the correlated activation of specific ensembles of neurons to ensure accurate information processing in V1. PMID:26511254

Tribological Properties of Structural Ceramics

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Miyoshi, Kazuhisa

1987-01-01

Paper discusses tribological properties of structural ceramics. Function of tribological research is to bring about reduction in adhesion, friction, and wear of mechanical components; to prevent failures; and to provide long, reliable component life, through judicious selection of materials, operating parameters, and lubricants. Paper reviews adhesion, friction, wear, and lubrication of ceramics; anisotropic friction and wear behavior; and effects of surface films and interactions between ceramics and metals. Analogies with metals are made. Both oxide and nonoxide ceramics, including ceramics used as high temperature lubricants, are dicussed.

Structural design of high-performance capacitive accelerometers using parametric optimization with uncertainties

NASA Astrophysics Data System (ADS)

Teves, André da Costa; Lima, Cícero Ribeiro de; Passaro, Angelo; Silva, Emílio Carlos Nelli

2017-03-01

Electrostatic or capacitive accelerometers are among the highest volume microelectromechanical systems (MEMS) products nowadays. The design of such devices is a complex task, since they depend on many performance requirements, which are often conflicting. Therefore, optimization techniques are often used in the design stage of these MEMS devices. Because of problems with reliability, the technology of MEMS is not yet well established. Thus, in this work, size optimization is combined with the reliability-based design optimization (RBDO) method to improve the performance of accelerometers. To account for uncertainties in the dimensions and material properties of these devices, the first order reliability method is applied to calculate the probabilities involved in the RBDO formulation. Practical examples of bulk-type capacitive accelerometer designs are presented and discussed to evaluate the potential of the implemented RBDO solver.

Stress corrosion cracking properties of 15-5PH steel

NASA Technical Reports Server (NTRS)

Rosa, Ferdinand

1993-01-01

Unexpected occurrence of failures, due to stress corrosion cracking (SCC) of structural components, indicate a need for improved characterization of materials and more advanced analytical procedures for reliably predicting structures performance. Accordingly, the purpose of this study was to determine the stress corrosion susceptibility of 15-5PH steel over a wide range of applied strain rates in a highly corrosive environment. The selected environment for this investigation was a highly acidified sodium chloride (NaCl) aqueous solution. The selected alloy for the study was a 15-5PH steel in the H900 condition. The slow strain rate technique was selected to test the metals specimens.

Mechanical behavior of precipitation hardenable steels exposed to highly corrosive environment

NASA Technical Reports Server (NTRS)

Rosa, Ferdinand

1994-01-01

Unexpected occurrences of failures, due to stress corrosion cracking (SCC) of structural components, indicate a need for improved characterization of materials and more advanced analytical procedures for reliably predicting structures performance. Accordingly, the purpose of this study was to determine the stress corrosion susceptibility of 15 - 5 PH steel over a wide range of applied strain rates in a highly corrosive environment. The selected environment for this investigation was a 3.5 percent NaCl aqueous solution. The material selected for the study was 15 - 5 PH steel in the H 900 condition. The Slow Strain Rate technique was used to test the metallic specimens.

Assessing motivation for work environment improvements: internal consistency, reliability and factorial structure.

PubMed

Hedlund, Ann; Ateg, Mattias; Andersson, Ing-Marie; Rosén, Gunnar

2010-04-01

Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation. A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees. The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance. The questionnaire can be a useful tool in improving intervention methods. The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. Copyright 2010 Elsevier Ltd. All rights reserved.

System data communication structures for active-control transport aircraft, volume 2

NASA Technical Reports Server (NTRS)

Hopkins, A. L.; Martin, J. H.; Brock, L. D.; Jansson, D. G.; Serben, S.; Smith, T. B.; Hanley, L. D.

1981-01-01

The application of communication structures to advanced transport aircraft are addressed. First, a set of avionic functional requirements is established, and a baseline set of avionics equipment is defined that will meet the requirements. Three alternative configurations for this equipment are then identified that represent the evolution toward more dispersed systems. Candidate communication structures are proposed for each system configuration, and these are compared using trade off analyses; these analyses emphasize reliability but also address complexity. Multiplex buses are recognized as the likely near term choice with mesh networks being desirable for advanced, highly dispersed systems.

INFLUENCES OF RESPONSE RATE AND DISTRIBUTION ON THE CALCULATION OF INTEROBSERVER RELIABILITY SCORES

PubMed Central

Rolider, Natalie U.; Iwata, Brian A.; Bullock, Christopher E.

2012-01-01

We examined the effects of several variations in response rate on the calculation of total, interval, exact-agreement, and proportional reliability indices. Trained observers recorded computer-generated data that appeared on a computer screen. In Study 1, target responses occurred at low, moderate, and high rates during separate sessions so that reliability results based on the four calculations could be compared across a range of values. Total reliability was uniformly high, interval reliability was spuriously high for high-rate responding, proportional reliability was somewhat lower for high-rate responding, and exact-agreement reliability was the lowest of the measures, especially for high-rate responding. In Study 2, we examined the separate effects of response rate per se, bursting, and end-of-interval responding. Response rate and bursting had little effect on reliability scores; however, the distribution of some responses at the end of intervals decreased interval reliability somewhat, proportional reliability noticeably, and exact-agreement reliability markedly. PMID:23322930

Validity and reliability of the robotic objective structured assessment of technical skills

PubMed Central

Siddiqui, Nazema Y.; Galloway, Michael L.; Geller, Elizabeth J.; Green, Isabel C.; Hur, Hye-Chun; Langston, Kyle; Pitter, Michael C.; Tarr, Megan E.; Martino, Martin A.

2015-01-01

Objective Objective structured assessments of technical skills (OSATS) have been developed to measure the skill of surgical trainees. Our aim was to develop an OSATS specifically for trainees learning robotic surgery. Study Design This is a multi-institutional study in eight academic training programs. We created an assessment form to evaluate robotic surgical skill through five inanimate exercises. Obstetrics/gynecology, general surgery, and urology residents, fellows, and faculty completed five robotic exercises on a standard training model. Study sessions were recorded and randomly assigned to three blinded judges who scored performance using the assessment form. Construct validity was evaluated by comparing scores between participants with different levels of surgical experience; inter- and intra-rater reliability were also assessed. Results We evaluated 83 residents, 9 fellows, and 13 faculty, totaling 105 participants; 88 (84%) were from obstetrics/gynecology. Our assessment form demonstrated construct validity, with faculty and fellows performing significantly better than residents (mean scores: 89 ± 8 faculty; 74 ± 17 fellows; 59 ± 22 residents, p<0.01). In addition, participants with more robotic console experience scored significantly higher than those with fewer prior console surgeries (p<0.01). R-OSATS demonstrated good inter-rater reliability across all five drills (mean Cronbach's α: 0.79 ± 0.02). Intra-rater reliability was also high (mean Spearman's correlation: 0.91 ± 0.11). Conclusions We developed an assessment form for robotic surgical skill that demonstrates construct validity, inter- and intra-rater reliability. When paired with standardized robotic skill drills this form may be useful to distinguish between levels of trainee performance. PMID:24807319

Reliability, factor structure, and validity of the German version of the Trauma Symptom Checklist for Children in a sample of adolescents

PubMed Central

Matulis, Simone; Loos, Laura; Langguth, Nadine; Schreiber, Franziska; Gutermann, Jana; Gawrilow, Caterina; Steil, Regina

2015-01-01

Background The Trauma Symptom Checklist for Children (TSC-C) is the most widely used self-report scale to assess trauma-related symptoms in children and adolescents on six clinical scales. The purpose of the present study was to develop a German version of the TSC-C and to investigate its psychometric properties, such as factor structure, reliability, and validity, in a sample of German adolescents. Method A normative sample of N=583 and a clinical sample of N=41 adolescents with a history of physical or sexual abuse aged between 13 and 21 years participated in the study. Results The Confirmatory Factor Analysis on the six-factor model (anger, anxiety, depression, dissociation, posttraumatic stress, and sexual concerns with the subdimensions preoccupation and distress) revealed acceptable to good fit statistics in the normative sample. One item had to be excluded from the German version of the TSC-C because the factor loading was too low. All clinical scales presented acceptable to good reliability, with Cronbach's α's ranging from .80 to .86 in the normative sample and from .72 to .87 in the clinical sample. Concurrent validity was also demonstrated by the high correlations between the TSC-C scales and instruments measuring similar psychopathology. TSC-C scores reliably differentiated between adolescents with trauma history and those without trauma history, indicating discriminative validity. Conclusions In conclusion, the German version of the TSC-C is a reliable and valid instrument for assessing trauma-related symptoms on six different scales in adolescents aged between 13 and 21 years. PMID:26498182

Reliability, factor structure, and validity of the German version of the Trauma Symptom Checklist for Children in a sample of adolescents.

PubMed

Matulis, Simone; Loos, Laura; Langguth, Nadine; Schreiber, Franziska; Gutermann, Jana; Gawrilow, Caterina; Steil, Regina

2015-01-01

The Trauma Symptom Checklist for Children (TSC-C) is the most widely used self-report scale to assess trauma-related symptoms in children and adolescents on six clinical scales. The purpose of the present study was to develop a German version of the TSC-C and to investigate its psychometric properties, such as factor structure, reliability, and validity, in a sample of German adolescents. A normative sample of N=583 and a clinical sample of N=41 adolescents with a history of physical or sexual abuse aged between 13 and 21 years participated in the study. The Confirmatory Factor Analysis on the six-factor model (anger, anxiety, depression, dissociation, posttraumatic stress, and sexual concerns with the subdimensions preoccupation and distress) revealed acceptable to good fit statistics in the normative sample. One item had to be excluded from the German version of the TSC-C because the factor loading was too low. All clinical scales presented acceptable to good reliability, with Cronbach's α's ranging from .80 to .86 in the normative sample and from .72 to .87 in the clinical sample. Concurrent validity was also demonstrated by the high correlations between the TSC-C scales and instruments measuring similar psychopathology. TSC-C scores reliably differentiated between adolescents with trauma history and those without trauma history, indicating discriminative validity. In conclusion, the German version of the TSC-C is a reliable and valid instrument for assessing trauma-related symptoms on six different scales in adolescents aged between 13 and 21 years.

The somatic symptom scale-8 (SSS-8): a brief measure of somatic symptom burden.

PubMed

Gierk, Benjamin; Kohlmann, Sebastian; Kroenke, Kurt; Spangenberg, Lena; Zenger, Markus; Brähler, Elmar; Löwe, Bernd

2014-03-01

Somatic symptoms are the core features of many medical diseases, and they are used to evaluate the severity and course of illness. The 8-item Somatic Symptom Scale (SSS-8) was recently developed as a brief, patient-reported outcome measure of somatic symptom burden, but its reliability, validity, and usefulness have not yet been tested. To investigate the reliability, validity, and severity categories as well as the reference scores of the SSS-8. A national, representative general-population survey was performed between June 15, 2012, and July 15, 2012, in Germany, including 2510 individuals older than 13 years. The SSS-8 mean (SD), item-total correlations, Cronbach α, factor structure, associations with measures of construct validity (Patient Health Questionnaire-2 depression scale, Generalized Anxiety Disorder-2 scale, visual analog scale for general health status, 12-month health care use), severity categories, and percentile rank reference scores. The SSS-8 had excellent item characteristics and good reliability (Cronbach α = 0.81). The factor structure reflects gastrointestinal, pain, fatigue, and cardiopulmonary aspects of the general somatic symptom burden. Somatic symptom burden as measured by the SSS-8 was significantly associated with depression (r = 0.57 [95% CI, 0.54 to 0.60]), anxiety (r = 0.55 [95% CI, 0.52 to 0.58]), general health status (r = -0.24 [95% CI, -0.28 to -0.20]), and health care use (incidence rate ratio, 1.12 [95% CI, 1.10 to 1.14]). The SSS-8 severity categories were calculated in accordance with percentile ranks: no to minimal (0-3 points), low (4-7 points), medium (8-11 points), high (12-15 points), and very high (16-32 points) somatic symptom burden. For every SSS-8 severity category increase, there was a 53% (95% CI, 44% to 63%) increase in health care visits. The SSS-8 is a reliable and valid self-report measure of somatic symptom burden. Cutoff scores identify individuals with low, medium, high, and very high somatic symptom burden.

Enhanced performance of amorphous In-Ga-Zn-O thin-film transistors using different metals for source/drain electrodes

NASA Astrophysics Data System (ADS)

Pyo, Ju-Young; Cho, Won-Ju

2017-09-01

In this paper, we propose an amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) with off-planed source/drain electrodes. We applied different metals for the source/drain electrodes with Ni and Ti to control the work function as high and low. When we measured the configuration of Ni to drain and source to Ti, the a-IGZO TFT showed increased driving current, decreased leakage current, a high on/off current ratio, low subthreshold swing, and high mobility. In addition, we conducted a reliability test with a gate bias stress test at various temperatures. The results of the reliability test showed the Ni drain and Ti drain had an equivalent effective energy barrier height. Thus, we confirmed that the proposed off-planed structure improved the electrical characteristics of the fabricated devices without any degradation of characteristics. Through the a-IGZO TFT with different source/drain electrode metal engineering, we realized high-performance TFTs for next-generation display devices.

Brightness-enhanced high-efficiency single emitters for fiber laser pumping

NASA Astrophysics Data System (ADS)

Yanson, Dan; Rappaport, Noam; Shamay, Moshe; Cohen, Shalom; Berk, Yuri; Klumel, Genadi; Don, Yaroslav; Peleg, Ophir; Levy, Moshe

2013-02-01

Reliable single emitters delivering <10W in the 9xx nm spectral range, are common energy sources for fiber laser pumps. The brightness (radiance) of a single emitter, which connotes the angular concentration of the emitted energy, is just as important a parameter as the output power alone for fiber coupling applications. We report on the development of high-brightness single emitters that demonstrate <12W output with 60% wall-plug efficiency and a lateral emission angle that is compatible with coupling into 0.15 NA delivery fiber. Using a purpose developed active laser model, simulation of far-field patterns in the lateral (slow) axis can be performed for different epitaxial wafer structures. By optimizing both the wafer and chip designs, we have both increased the device efficiency and improved the slow-axis divergence in high-current operation. Device reliability data are presented. The next-generation emitters will be integrated in SCD's NEON fiber pump modules to upgrade the pump output towards higher ex-fiber powers with high efficiency.

Study of a fail-safe abort system for an actively cooled hypersonic aircraft. Volume 1: Technical summary

NASA Technical Reports Server (NTRS)

Pirello, C. J.; Herring, R. L.

1976-01-01

Conceptual designs of a fail-safe abort system for hydrogen fueled actively cooled high speed aircraft are examined. The fail-safe concept depends on basically three factors: (1) a reliable method of detecting a failure or malfunction in the active cooling system, (2) the optimization of abort trajectories which minimize the descent heat load to the aircraft, and (3) fail-safe thermostructural concepts to minimize both the weight and the maximum temperature the structure will reach during descent. These factors are examined and promising approaches are evaluated based on weight, reliability, ease of manufacture and cost.

Honing process optimization algorithms

NASA Astrophysics Data System (ADS)

Kadyrov, Ramil R.; Charikov, Pavel N.; Pryanichnikova, Valeria V.

2018-03-01

This article considers the relevance of honing processes for creating high-quality mechanical engineering products. The features of the honing process are revealed and such important concepts as the task for optimization of honing operations, the optimal structure of the honing working cycles, stepped and stepless honing cycles, simulation of processing and its purpose are emphasized. It is noted that the reliability of the mathematical model determines the quality parameters of the honing process control. An algorithm for continuous control of the honing process is proposed. The process model reliably describes the machining of a workpiece in a sufficiently wide area and can be used to operate the CNC machine CC743.

Robotic Assembly of Truss Structures for Space Systems and Future Research Plans

NASA Technical Reports Server (NTRS)

Doggett, William

2002-01-01

Many initiatives under study by both the space science and earth science communities require large space systems, i.e. with apertures greater than 15 m or dimensions greater than 20 m. This paper reviews the effort in NASA Langley Research Center's Automated Structural Assembly Laboratory which laid the foundations for robotic construction of these systems. In the Automated Structural Assembly Laboratory reliable autonomous assembly and disassembly of an 8 meter planar structure composed of 102 truss elements covered by 12 panels was demonstrated. The paper reviews the hardware and software design philosophy which led to reliable operation during weeks of near continuous testing. Special attention is given to highlight the features enhancing assembly reliability.

Scheduling structural health monitoring activities for optimizing life-cycle costs and reliability of wind turbines

NASA Astrophysics Data System (ADS)

Hanish Nithin, Anu; Omenzetter, Piotr

2017-04-01

Optimization of the life-cycle costs and reliability of offshore wind turbines (OWTs) is an area of immense interest due to the widespread increase in wind power generation across the world. Most of the existing studies have used structural reliability and the Bayesian pre-posterior analysis for optimization. This paper proposes an extension to the previous approaches in a framework for probabilistic optimization of the total life-cycle costs and reliability of OWTs by combining the elements of structural reliability/risk analysis (SRA), the Bayesian pre-posterior analysis with optimization through a genetic algorithm (GA). The SRA techniques are adopted to compute the probabilities of damage occurrence and failure associated with the deterioration model. The probabilities are used in the decision tree and are updated using the Bayesian analysis. The output of this framework would determine the optimal structural health monitoring and maintenance schedules to be implemented during the life span of OWTs while maintaining a trade-off between the life-cycle costs and risk of the structural failure. Numerical illustrations with a generic deterioration model for one monitoring exercise in the life cycle of a system are demonstrated. Two case scenarios, namely to build initially an expensive and robust or a cheaper but more quickly deteriorating structures and to adopt expensive monitoring system, are presented to aid in the decision-making process.

Optimization of structures on the basis of fracture mechanics and reliability criteria

NASA Technical Reports Server (NTRS)

Heer, E.; Yang, J. N.

1973-01-01

Systematic summary of factors which are involved in optimization of given structural configuration is part of report resulting from study of analysis of objective function. Predicted reliability of performance of finished structure is sharply dependent upon results of coupon tests. Optimization analysis developed by study also involves expected cost of proof testing.

Reliability, Validity, and Factor Structure of the Imaginative Capability Scale

ERIC Educational Resources Information Center

Liang, Chaoyun; Chia, Tsorng-Lin

2014-01-01

Three studies were combined to test the reliability, validity, and factor structure of the imaginative capability scale (ICS). The ICS was a new self-report measure, which was developed to be empirically valid and easy to administer. Study 1 consisted in an exploratory factor analysis to determine the most appropriate structure of the ICS in a…

Cross-cultural adaptation of the Female Genital Self-Image Scale (FGSIS) in Iranian female college students.

PubMed

Pakpour, Amir H; Zeidi, Isa Mohammadi; Ziaeiha, Masoumeh; Burri, Andrea

2014-01-01

The aim of the present study was to investigate the psychometric properties of a translated and culturally adapted Iranian version of the Female Genital Self-Image Scale (FGSIS-I) in a sample of college women. Further, the relationship between women's self-image, body appreciation, sexual functioning, and gynecological exam behavior was explored. A sample of 1,877 female students from five different universities across Qazvin and Tehran completed the Female Sexual Function Index (FSFI), the Body Appreciation Scale (BAS), the Rosenberg Self-Esteem Scale (RSES), the FGSIS-I, and a gynecological exam behavior questionnaire. Good to excellent internal consistency reliability, test-retest reliability, and convergent and construct validity were found. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) both provided a two-factor structure for the FGSIS-I. The validity of the FGSIS-I in predicting gynecological exam behavior of college women was tested using structural equation modeling (SEM). The final model accounted for 33% of the variance in gynecological exam behavior (p < 0.01). In conclusion, the FGSIS-I was found to be a highly valid and reliable instrument to assess female genital self-image in Iranian women.

A modular and cost-effective superconducting generator design for offshore wind turbines

NASA Astrophysics Data System (ADS)

Keysan, Ozan; Mueller, Markus

2015-03-01

Superconducting generators have the potential to reduce the tower head mass for large (∼10 MW) offshore wind turbines. However, a high temperature superconductor generator should be as reliable as conventional generators for successful entry into the market. Most of the proposed designs use the superconducting synchronous generator concept, which has a higher cost than conventional generators and suffers from reliability issues. In this paper, a novel claw pole type of superconducting machine is presented. The design has a stationary superconducting field winding, which simplifies the design and increases the reliability. The machine can be operated in independent modules; thus even if one of the sections fails, the rest can operate until the next planned maintenance. Another advantage of the design is the very low superconducting wire requirement; a 10 MW, 10 rpm design is presented which uses 13 km of MgB2 wire at 30 K. The outer diameter of the machine is 6.63 m and it weighs 184 tonnes including the structural mass. The design is thought to be a good candidate for entering the renewable energy market, with its low cost and robust structure.

Developmental monitoring using caregiver reports in a resource-limited setting: the case of Kilifi, Kenya

PubMed Central

Abubakar, A; Holding, P; Van de Vijver, F; Bomu, G; Van Baar, A

2010-01-01

Aim: The main aim of the current study was to evaluate the reliability, validity and acceptability of developmental monitoring using caregiver reports among mothers in a rural African setting. Methods: A structured interview for parents of children aged 24 months and less was developed through both participant consultation and a review of literature. The reliability and validity of the schedule was evaluated through a 10-month monitoring programme of 95 children, aged 2–10 months. The acceptability of the process was evaluated by studying retention rates and by organizing focus group discussions with participating mothers. Results: The structured interview ‘Developmental Milestones Checklist’ consisted of 66 items covering three broad domains of child functioning: motor, language and personal–social development. The interview yielded scores of developmental achievements that showed high internal consistency and excellent test–retest reliability. The results were sensitive to maturational changes and nutritional deficiencies. In addition, acceptable retention rates of approximately 80% were found. Participating mothers reported that they found the procedures both acceptable and beneficial. Conclusion: Developmental monitoring using caregiver report is a viable method to identify and monitor at-risk children in Sub-Saharan Africa. PMID:20353499

Structure and kinematics of the broad-line regions in active galaxies from IUE variability data

NASA Technical Reports Server (NTRS)

Koratkar, Anuradha P.; Gaskell, C. Martin

1991-01-01

IUE archival data are used here to investigate the structure nad kinematics of the broad-line regions (BLRs) in nine AGN. It is found that the centroid of the line-continuum cross-correlation functions (CCFs) can be determined with reasonable reliability. The errors in BLR size estimates from CCFs for irregularly sampled light curves are fairly well understood. BLRs are found to have small luminosity-weighted radii, and lines of high ionization tend to be emitted closer to the central source than lines of low ionization, especially for low-luminosity objects. The motion of the gas is gravity-dominated with both pure inflow and pure outflow of high-velocity gas being excluded at a high confidence level for certain geometries.

Regulation of the Dynamic Live Load Factor for Calculation of Bridge Structures on High-Speed Railway Mainlines

NASA Astrophysics Data System (ADS)

Dyachenko, Leonid K.; Benin, Andrey V.

2017-06-01

When the high-speed railway traffic is being organized, it becomes necessary to elaborate bridge design standards for high-speed railways (HSR). Methodology of studying the issues of HSR bridge design is based on the comprehensive analysis of domestic research as well as international experience in design, construction and operation of high-speed railways. Serious requirements are imposed on the HSR artificial structures, which raise a number of scientific tasks associated mainly with the issues of the dynamic interaction of the rolling stock and the bridge elements. To ensure safety of traffic and reliability of bridges during the whole period of operation one needs to resolve the dynamic problems of various types of high-speed trains moving along the structures. The article analyses dependences of the magnitude of inertial response on the external stress parameters and proposes a simplified method of determination of the dynamic live load factor caused by the passage of high-speed trains. The usefulness of the given research arises from the reduction of complexity of the complicated dynamic calculations needed to describe a high-speed train travelling along the artificial structures.

Reliability-based structural optimization: A proposed analytical-experimental study

NASA Technical Reports Server (NTRS)

Stroud, W. Jefferson; Nikolaidis, Efstratios

1993-01-01

An analytical and experimental study for assessing the potential of reliability-based structural optimization is proposed and described. In the study, competing designs obtained by deterministic and reliability-based optimization are compared. The experimental portion of the study is practical because the structure selected is a modular, actively and passively controlled truss that consists of many identical members, and because the competing designs are compared in terms of their dynamic performance and are not destroyed if failure occurs. The analytical portion of this study is illustrated on a 10-bar truss example. In the illustrative example, it is shown that reliability-based optimization can yield a design that is superior to an alternative design obtained by deterministic optimization. These analytical results provide motivation for the proposed study, which is underway.

Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: manufacturing corrective optical elements for high-power laser applications.

PubMed

Menapace, Joseph A; Ehrmann, Paul E; Bayramian, Andrew J; Bullington, Amber; Di Nicola, Jean-Michel G; Haefner, Constantin; Jarboe, Jeffrey; Marshall, Christopher; Schaffers, Kathleen I; Smith, Cal

2016-07-01

Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry, is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique's capabilities. This high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.

Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: Manufacturing corrective optical elements for high-power laser applications

DOE PAGES

Menapace, Joseph A.; Ehrmann, Paul E.; Bayramian, Andrew J.; ...

2016-03-15

Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry,more » is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique’s capabilities. As a result, this high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.« less

Solid Oxide Fuel Cell Seal Development at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Steinetz, Bruce M.; Bansal, Narottam P.; Dynys, Fred W.; Lang, Jerry; Daniels, Christopher C.; Palko, Joeseph L.; Choi, S. R.

2004-01-01

Researchers at NASA GRC are confronting the seal durability challenges of Solid Oxide Fuel Cells by pursuing an integrated and multidisciplinary development effort incorporating thermo-structural analyses, advanced materials, experimentation, and novel seal design concepts. The successful development of durable hermetic SOFC seals is essential to reliably producing the high power densities required for aerospace applications.

Refining the Assessment of Hopelessness: An Improved Way to Look to the Future

ERIC Educational Resources Information Center

Fisher, Lauren B.; Overholser, James C.

2013-01-01

Despite its high sensitivity, the Beck Hopelessness Scale (BHS) has demonstrated low specificity, has an ambiguous factor structure, and includes inadequate items. The current study examined the psychometric properties of a modified BHS (mBHS) using a Likert scale format that would allow for improved reliability, validity, and clinical utility.…

Needs Assessment in STEM Disciplines: Reliability, Validity and Factor Structure of the Student Support Needs Scale (SSNS)

ERIC Educational Resources Information Center

Hardy, Precious; Aruguete, Mara

2014-01-01

Retention is a major problem in most colleges and universities. High dropout rates, especially in the STEM disciplines (science, technology, engineering and mathematics), have proved intractable despite the offering of supplemental instruction. A broad model of support systems that includes psychological factors is needed to address retention in…

Test-retest reliability of quantitative sensory testing for mechanical somatosensory and pain modulation assessment of masticatory structures.

PubMed

Costa, Y M; Morita-Neto, O; de Araújo-Júnior, E N S; Sampaio, F A; Conti, P C R; Bonjardim, L R

2017-03-01

Assessing the reliability of medical measurements is a crucial step towards the elaboration of an applicable clinical instrument. There are few studies that evaluate the reliability of somatosensory assessment and pain modulation of masticatory structures. This study estimated the test-retest reliability, that is over time, of the mechanical somatosensory assessment of anterior temporalis, masseter and temporomandibular joint (TMJ) and the conditioned pain modulation (CPM) using the anterior temporalis as the test site. Twenty healthy women were evaluated in two sessions (1 week apart) by the same examiner. Mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind-up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying the anterior temporalis, masseter and TMJ of the dominant side. CPM was tested by comparing PPT before and during the hand immersion in a hot water bath. anova and intra-class correlation coefficients (ICCs) were applied to the data (α = 5%). The overall ICCs showed acceptable values for the test-retest reliability of mechanical somatosensory assessment of masticatory structures. The ICC values of 75% of all quantitative sensory measurements were considered fair to excellent (fair = 8·4%, good = 33·3% and excellent = 33·3%). However, the CPM paradigm presented poor reliability (ICC = 0·25). The mechanical somatosensory assessment of the masticatory structures, but not the proposed CPM protocol, can be considered sufficiently reliable over time to evaluate the trigeminal sensory function. © 2016 John Wiley & Sons Ltd.

Assessing the surgical skills of trainees in the operating theatre: a prospective observational study of the methodology.

PubMed

Beard, J D; Marriott, J; Purdie, H; Crossley, J

2011-01-01

To compare user satisfaction and acceptability, reliability and validity of three different methods of assessing the surgical skills of trainees by direct observation in the operating theatre across a range of different surgical specialties and index procedures. A 2-year prospective, observational study in the operating theatres of three teaching hospitals in Sheffield. The assessment methods were procedure-based assessment (PBA), Objective Structured Assessment of Technical Skills (OSATS) and Non-technical Skills for Surgeons (NOTSS). The specialties were obstetrics and gynaecology (O&G) and upper gastrointestinal, colorectal, cardiac, vascular and orthopaedic surgery. Two to four typical index procedures were selected from each specialty. Surgical trainees were directly observed performing typical index procedures and assessed using a combination of two of the three methods (OSATS or PBA and NOTSS for O&G, PBA and NOTSS for the other specialties) by the consultant clinical supervisor for the case and the anaesthetist and/or scrub nurse, as well as one or more independent assessors from the research team. Information on user satisfaction and acceptability of each assessment method from both assessor and trainee perspectives was obtained from structured questionnaires. The reliability of each method was measured using generalisability theory. Aspects of validity included the internal structure of each tool and correlation between tools, construct validity, predictive validity, interprocedural differences, the effect of assessor designation and the effect of assessment on performance. Of the 558 patients who were consented, a total of 437 (78%) cases were included in the study: 51 consultant clinical supervisors, 56 anaesthetists, 39 nurses, 2 surgical care practitioners and 4 independent assessors provided 1635 assessments on 85 trainees undertaking the 437 cases. A total of 749 PBAs, 695 NOTSS and 191 OSATSs were performed. Non-O&G clinical supervisors and trainees provided mixed, but predominantly positive, responses about a range of applications of PBA. Most felt that PBA was important in surgical education, and would use it again in the future and did not feel that it added time to the operating list. The overall satisfaction of O&G clinical supervisors and trainees with OSATS was not as high, and a majority of those who used both preferred PBA. A majority of anaesthetists and nurses felt that NOTSS allowed them to rate interpersonal skills (communication, teamwork and leadership) more easily than cognitive skills (situation awareness and decision-making), that it had formative value and that it was a valuable adjunct to the assessment of technical skills. PBA demonstrated high reliability (G > 0.8 for only three assessor judgements on the same index procedure). OSATS had lower reliability (G > 0.8 for five assessor judgements on the same index procedure). Both were less reliable on a mix of procedures because of strong procedure-specific factors. A direct comparison of PBA between O&G and non-O&G cases showed a striking difference in reliability. Within O&G, a good level of reliability (G > 0.8) could not be obtained using a feasible number of assessments. Conversely, the reliability within non-O&G cases was exceptionally high, with only two assessor judgements being required. The reasons for this difference probably include the more summative purpose of assessment in O&G and the much higher proportion of O&G trainees in this study with training concerns (42% vs 4%). The reliability of NOTSS was lower than that for PBA. Reliability for the same procedure (G > 0.8) required six assessor judgements. However, as procedure-specific factors exerted a lesser influence on NOTSS, reliability on a mix of procedures could be achieved using only eight assessor judgements. NOTSS also demonstrated a valid internal structure. The strongest correlations between NOTSS and PBA or OSATS were in the 'decision-making' domain. PBA and NOTSS showed better construct validity than OSATS, the year of training and the number of recent index procedures performed being significant independent predictors of performance. There was little variation in scoring between different procedures or different designations of assessor. The results suggest that PBA is a reliable and acceptable method of assessing surgical skills, with good construct validity. Specialties that use OSATS may wish to consider changing the design or switching to PBA. Whatever workplace-based assessment method is used, the purpose, timing and frequency of assessment require detailed guidance. NOTSS is a promising tool for the assessment of non-technical skills, and surgical specialties may wish to consider its inclusion in their assessment framework. Further research is required into the use of health-care professionals other than consultant surgeons to assess trainees, the relationship between performance and experience, the educational impact of assessment and the additional value of video recording.

Sensory Topography of Oral Structures.

PubMed

Bearelly, Shethal; Cheung, Steven W

2017-01-01

Sensory function in the oral cavity and oropharynx is integral to effective deglutition and speech production. The main hurdle to evaluation of tactile consequences of upper aerodigestive tract diseases and treatments is access to a reliable clinical tool. We propose a rapid and reliable procedure to determine tactile thresholds using buckling monofilaments to advance care. To develop novel sensory testing monofilaments and map tactile thresholds of oral cavity and oropharyngeal structures. A prospective cross-sectional study of 37 healthy adults (12 men, 25 women), specifically without a medical history of head and neck surgery, radiation, or chemotherapy, was carried out in an academic tertiary medical center to capture normative data on tactile sensory function in oral structures. Cheung-Bearelly monofilaments were constructed by securing nylon monofilament sutures (2-0 through 9-0) in the lumen of 5-French ureteral catheters, exposing 20 mm for tapping action. Buckling force consistency was evaluated for 3 lots of each suture size. Sensory thresholds of 4 oral cavity and 2 oropharyngeal subsites in healthy participants (n = 37) were determined by classical signal detection methodology (d-prime ≥1). In 21 participants, test-retest reliability of sensory thresholds was evaluated. Separately in 16 participants, sensory thresholds determined by a modified staircase method were cross-validated with those obtained by classical signal detection. Buckling forces of successive suture sizes were distinct (P < .001), consistent (Cronbach α, 0.99), and logarithmically related (r = 0.99, P < .001). Test-retest reliability of sensory threshold determination was high (Cronbach α, >0.7). The lower lip, anterior tongue, and buccal mucosa were more sensitive than the soft palate, posterior tongue, and posterior pharyngeal wall (P < .001). Threshold determination by classical signal detection and modified staircase methods were highly correlated (r = 0.93, P < .001). Growth of perceptual intensity was logarithmically proportional to stimulus strength (P < .01). Topography of normal oral cavity and oropharyngeal tactile sensation is organized in accordance to decreasing sensitivity along the anteroposterior trajectory and growth of perceptual intensity at all subsites is log-linear. Cheung-Bearelly monofilaments are accessible, disposable, and consistent esthesiometers. This novel clinical tool is deployable for quantitative sensory function assessment of oral cavity and oropharyngeal structures.

Translation and Initial Validation of the Chinese (Cantonese) Version of Community Integration Measure for Use in Patients with Chronic Stroke

PubMed Central

Ng, Shamay S. M.; Ng, Gabriel Y. F.

2014-01-01

Objectives. To (1) translate and culturally adapt the English version Community Integration Measure into Chinese (Cantonese), (2) report the results of initial validation of the Chinese (Cantonese) version of CIM (CIM-C) including the content validity, internal consistency, test-retest reliability, and factor structure of CIM-C for use in stroke survivors in a Chinese community setting, and (3) investigate the level of community integration of stroke survivors living in Hong Kong. Design. Cross-sectional study. Setting. University-based rehabilitation centre. Participants. 62 (n = 62) subjects with chronic stroke. Methods. The CIM-C was produced after forward-backward translation, expert panel review, and pretesting. 25 (n = 25) of the same subjects were reassessed after a 1-week interval. Results. The items of the CIM-C demonstrated high internal consistency with a Cronbach's α of 0.84. The CIM-C showed good test-retest reliability with an intraclass correlation coefficient (ICC) of 0.84 (95% confidence interval, 0.64–0.93). A 3-factor structure of the CIM-C including “relationship and engagement,” “sense of knowing,” and “independent living,” was consistent with the original theoretical model. Hong Kong stroke survivors revealed a high level of community integration as measured by the CIM-C (mean (SD): 43.48 (5.79)). Conclusions. The CIM-C is a valid and reliable measure for clinical use. PMID:24995317

A reliable algorithm for optimal control synthesis

NASA Technical Reports Server (NTRS)

Vansteenwyk, Brett; Ly, Uy-Loi

1992-01-01

In recent years, powerful design tools for linear time-invariant multivariable control systems have been developed based on direct parameter optimization. In this report, an algorithm for reliable optimal control synthesis using parameter optimization is presented. Specifically, a robust numerical algorithm is developed for the evaluation of the H(sup 2)-like cost functional and its gradients with respect to the controller design parameters. The method is specifically designed to handle defective degenerate systems and is based on the well-known Pade series approximation of the matrix exponential. Numerical test problems in control synthesis for simple mechanical systems and for a flexible structure with densely packed modes illustrate positively the reliability of this method when compared to a method based on diagonalization. Several types of cost functions have been considered: a cost function for robust control consisting of a linear combination of quadratic objectives for deterministic and random disturbances, and one representing an upper bound on the quadratic objective for worst case initial conditions. Finally, a framework for multivariable control synthesis has been developed combining the concept of closed-loop transfer recovery with numerical parameter optimization. The procedure enables designers to synthesize not only observer-based controllers but also controllers of arbitrary order and structure. Numerical design solutions rely heavily on the robust algorithm due to the high order of the synthesis model and the presence of near-overlapping modes. The design approach is successfully applied to the design of a high-bandwidth control system for a rotorcraft.

Validation of the French version of the yale food addiction scale: an examination of its factor structure, reliability, and construct validity in a nonclinical sample.

PubMed

Brunault, Paul; Ballon, Nicolas; Gaillard, Philippe; Réveillère, Christian; Courtois, Robert

2014-05-01

The concept of food addiction has recently been proposed by applying the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria for substance dependence to eating behaviour. Food addiction has received increased attention given that it may play a role in binge eating, eating disorders, and the recent increase in obesity prevalence. Currently, there is no psychometrically sound tool for assessing food addiction in French. Our study aimed to test the psychometric properties of a French version of the Yale Food Addiction Scale (YFAS) by establishing its factor structure and construct validity in a nonclinical population. A total of 553 participants were assessed for food addiction (French version of the YFAS) and binge eating behaviour (Bulimic Investigatory Test Edinburgh and Binge Eating Scale). We tested the scale's factor structure (factor analysis for dichotomous data based on tetrachoric correlation coefficients), internal consistency, and construct validity with measures of binge eating. Our results supported a 1-factor structure, which accounted for 54.1% of the variance. This tool had adequate reliability and high construct validity with measures of binge eating in this population, both in its diagnosis and symptom count version. A 2-factor structure explained an additional 9.1% of the variance, and could differentiate between patients with high, compared with low, levels of insight regarding addiction symptoms. In our study, we validated a psychometrically sound French version of the YFAS, both in its symptom count and diagnostic version. Future studies should validate this tool in clinical samples.

Reliability and validity of the Incontinence Quiz-Turkish version.

PubMed

Kara, Kerime C; Çıtak Karakaya, İlkim; Tunalı, Nur; Karakaya, Mehmet G

2018-01-01

The aim of this study was to investigate the reliability and validity of the Turkish version of the Incontinence Quiz, which was developed by Branch et al. (1994), to assess women's knowledge of and attitudes toward urinary incontinence. Comprehensibility of the Turkish version of the 14-item Incontinence Quiz, which was prepared following translation-back translation procedures, was tested on a pilot group of eight women, and its internal reliability, test-retest reliability and construct validity were assessed in 150 women who attended the gynecology clinics of three hospitals in İçel, Turkey. Physical and sociodemographic characteristics and presence of incontinence complaints were also recorded. Data were analyzed at the 0.05 alpha level, using SPSS version 22. The scale had good reliability and validity. The internal reliability coefficient (Cronbach α) was 0.80, test-retest correlation coefficients were 0.83-0.94; and with regard to construct validity, Kaiser-Meyer-Olkin coefficient was 0.76 and Barlett sphericity test was 562.777 (P = 0.000). Turkish version of the Incontinence Quiz had a four-factor structure, with Eigenvalues ranging from 1.17 to 4.08. The Incontinence Quiz-Turkish version is a highly comprehensible, reliable and valid scale, which may be used to assess Turkish-speaking women's knowledge of and attitudes toward urinary incontinence. © 2017 Japan Society of Obstetrics and Gynecology.

The modified patient enablement instrument: a Portuguese cross-cultural adaptation, validity and reliability study.

PubMed

Remelhe, Mafalda; Teixeira, Pedro M; Lopes, Irene; Silva, Luís; Correia de Sousa, Jaime

2017-01-12

Enabling patients with asthma to obtain the knowledge, confidence and skills they need in order to assume a major role in the management of their disease is cost effective. It should be an integral part of any plan for long-term control of asthma. The modified Patient Enablement Instrument (mPEI) is an easily administered questionnaire that was adapted in the United Kingdom to measure patient enablement in asthma, but its applicability in Portugal is not known. Validity and reliability of questionnaires should be tested before use in settings different from those of the original version. The purpose of this study was to test the applicability of the mPEI to Portuguese asthma patients after translation and cross-cultural adaptation, and to verify the structural validity, internal consistency and reproducibility of the instrument. The mPEI was translated to Portuguese and back translated to English. Its content validity was assessed by a debriefing interview with 10 asthma patients. The translated instrument was then administered to a random sample of 142 patients with persistent asthma. Structural validity and internal consistency were assessed. For reproducibility analysis, 86 patients completed the instrument again 7 days later. Item-scale correlations and exploratory factor analysis were used to assess structural validity. Cronbach's alpha was used to test internal consistency, and the intra-class correlation coefficient was used for the analysis of reproducibility. All items of the Portuguese version of the mPEI were found to be equivalent to the original English version. There were strong item-scale correlations that confirmed construct validity, with a one component structure and good internal consistency (Cronbach's alpha >0.8) as well as high test-retest reliability (ICC=0.85). The mPEI showed sound psychometric properties for the evaluation of enablement in patients with asthma making it a reliable instrument for use in research and clinical practice in Portugal. Further studies are needed to confirm its responsiveness.

Validity and Reliability of the Turkish Version of Needs Based Biopsychosocial Distress Instrument for Cancer Patients (CANDI)

PubMed Central

Beyhun, Nazim Ercument; Can, Gamze; Tiryaki, Ahmet; Karakullukcu, Serdar; Bulut, Bekir; Yesilbas, Sehbal; Kavgaci, Halil; Topbas, Murat

2016-01-01

Background Needs based biopsychosocial distress instrument for cancer patients (CANDI) is a scale based on needs arising due to the effects of cancer. Objectives The aim of this research was to determine the reliability and validity of the CANDI scale in the Turkish language. Patients and Methods The study was performed with the participation of 172 cancer patients aged 18 and over. Factor analysis (principal components analysis) was used to assess construct validity. Criterion validities were tested by computing Spearman correlation between CANDI and hospital anxiety depression scale (HADS), and brief symptom inventory (BSI) (convergent validity) and quality of life scales (FACT-G) (divergent validity). Test-retest reliabilities and internal consistencies were measured with intraclass correlation (ICC) and Cronbach-α. Results A three-factor solution (emotional, physical and social) was found with factor analysis. Internal reliability (α = 0.94) and test-retest reliability (ICC = 0.87) were significantly high. Correlations between CANDI and HADS (rs = 0.67), and BSI (rs = 0.69) and FACT-G (rs = -0.76) were moderate and significant in the expected direction. Conclusions CANDI is a valid and reliable scale in cancer patients with a three-factor structure (emotional, physical and social) in the Turkish language. PMID:27621931

Regional reliability of quantitative signal targeting with alternating radiofrequency (STAR) labeling of arterial regions (QUASAR).

PubMed

Tatewaki, Yasuko; Higano, Shuichi; Taki, Yasuyuki; Thyreau, Benjamin; Murata, Takaki; Mugikura, Shunji; Ito, Daisuke; Takase, Kei; Takahashi, Shoki

2014-01-01

Quantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability. Using a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution. The mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries. Thus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter. © 2014 The Authors. Journal of Neuroimaging published by the American Society of Neuroimaging.

Regional Reliability of Quantitative Signal Targeting with Alternating Radiofrequency (STAR) Labeling of Arterial Regions (QUASAR)

PubMed Central

Tatewaki, Yasuko; Higano, Shuichi; Taki, Yasuyuki; Thyreau, Benjamin; Murata, Takaki; Mugikura, Shunji; Ito, Daisuke; Takase, Kei; Takahashi, Shoki

2014-01-01

BACKGROUND AND PURPOSE Quantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability. METHODS Using a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution. RESULTS The mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries. CONCLUSIONS Thus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter. PMID:25370338

An empirical look at the Defense Mechanism Test (DMT): reliability and construct validity.

PubMed

Ekehammar, Bo; Zuber, Irena; Konstenius, Marja-Liisa

2005-07-01

Although the Defense Mechanism Test (DMT) has been in use for almost half a century, there are still quite contradictory views about whether it is a reliable instrument, and if so, what it really measures. Thus, based on data from 39 female students, we first examined DMT inter-coder reliability by analyzing the agreement among trained judges in their coding of the same DMT protocols. Second, we constructed a "parallel" photographic picture that retained all structural characteristic of the original and analyzed DMT parallel-test reliability. Third, we examined the construct validity of the DMT by (a) employing three self-report defense-mechanism inventories and analyzing the intercorrelations between DMT defense scores and corresponding defenses in these instruments, (b) studying the relationships between DMT responses and scores on trait and state anxiety, and (c) relating DMT-defense scores to measures of self-esteem. The main results showed that the DMT can be coded with high reliability by trained coders, that the parallel-test reliability is unsatisfactory compared to traditional psychometric standards, that there is a certain generalizability in the number of perceptual distortions that people display from one picture to another, and that the construct validation provided meager empirical evidence for the conclusion that the DMT measures what it purports to measure, that is, psychological defense mechanisms.

Effect of working fluids on thermal performance of closed loop pulsating heat pipe

NASA Astrophysics Data System (ADS)

Kolková, Zuzana; Malcho, Milan

2014-08-01

Improving the performance of electrical components needs higher heat removal from these systems. One of the solutions available is to use a sealed heat pipe with a throbbing filling, where development meets the current requirements for intensification of heat removal and elimination of moving parts cooling systems. Heat pipes operate using phase change working fluid, and it is evaporation and condensation. They have a meandering shape and are characterized by high intensity of heat transfer, high durability and reliability. Advantage of these tubes is that it is not necessary to create the internal capillary structure for transporting liquid and they need any pump to the working fluid circulation. They have a simple structure, low cost, high performance, and they can be used for various structural applications. The choice of working fluid volume and performance affects thermal performance. Distilled water, ethanol and acetone were used in the performance ranges 0-80%.

Spanish version validation of the Marihuana Motives Measure in a drug-consuming adolescent sample.

PubMed

Matali Costa, Josep; Simons, J; Pardo, M; Lleras, M; Pérez, A; Andión, O

2018-01-15

Cannabis is the illicit drug mostly widely consumed by adolescents in Spain. The understanding of consumption motives is an important factor for intervention. In Spain, there are no available instruments for their evaluation, hence, the goal of this paper is to study the psychometric properties of the Marihuana Motives Measure (MMM) in a sample of adolescent consumers. Firstly, translation and back-translation was performed. A total of 228 adolescent consumers of cannabis were evaluated. Factorial analysis was conducted, and the reliability of the total scores and of each scale of the questionnaire was studied through Cronbach's alpha. Test-retest reliability was analyzed through interclass correlations. Validity evidence of the MMM was examined through correlations between current cannabis use, subjective consumption effects measured with the Addiction Research Center Inventory (ARCI), and personality measured with the Millon Adolescent Clinical Inventory (MACI). High reliability was observed in total score of the MMM (Cronbach α = .86), and high and moderate reliability for each of the five factors obtained in the factorial analysis of the MMM, Social = .82, Enhancement = .72, Coping = .83, Expansion = .74, and Conformity = .64. Significant correlations were also observed between cannabis consumption motives and subjective effects, and between consumption motives and personality. The Spanish version of the MMM shows a similar factorial structure as the one obtained by the original author, and its measures are reliable and valid for the study of cannabis consumption motives in adolescent consumer population.

Development of an Extreme High Temperature n-type Ohmic Contact to Silicon Carbide

NASA Technical Reports Server (NTRS)

Evans, Laura J.; Okojie, Robert S.; Lukco, Dorothy

2011-01-01

We report on the initial demonstration of a tungsten-nickel (75:25 at. %) ohmic contact to silicon carbide (SiC) that performed for up to fifteen hours of heat treatment in argon at 1000 C. The transfer length method (TLM) test structure was used to evaluate the contacts. Samples showed consistent ohmic behavior with specific contact resistance values averaging 5 x 10-4 -cm2. The development of this contact metallization should allow silicon carbide devices to operate more reliably at the present maximum operating temperature of 600 C while potentially extending operations to 1000 C. Introduction Silicon Carbide (SiC) is widely recognized as one of the materials of choice for high temperature, harsh environment sensors and electronics due to its ability to survive and continue normal operation in such environments [1]. Sensors and electronics in SiC have been developed that are capable of operating at temperatures of 600 oC. However operating these devices at the upper reliability temperature threshold increases the potential for early degradation. Therefore, it is important to raise the reliability temperature ceiling higher, which would assure increased device reliability when operated at nominal temperature. There are also instances that require devices to operate and survive for prolonged periods of time above 600 oC [2, 3]. This is specifically needed in the area of hypersonic flight where robust sensors are needed to monitor vehicle performance at temperature greater than 1000 C, as well as for use in the thermomechanical characterization of high temperature materials (e.g. ceramic matrix composites). While SiC alone can withstand these temperatures, a major challenge is to develop reliable electrical contacts to the device itself in order to facilitate signal extraction

Origins of serotonin innervation of forebrain structures

NASA Technical Reports Server (NTRS)

Kellar, K. J.; Brown, P. A.; Madrid, J.; Bernstein, M.; Vernikos-Danellis, J.; Mehler, W. R.

1977-01-01

The tryptophan hydroxylase activity and high-affinity uptake of (3H) serotonin ((3H)5-HT) were measured in five discrete brain regions of rats following lesions of the dorsal or median raphe nuclei. Dorsal raphe lesions reduced enzyme and uptake activity in the striatum only. Median raphe lesions reduced activities in the hippocampus, septal area, frontal cortex, and, to a lesser extent, in the hypothalamus. These data are consistent with the suggestion that the dorsal and median raphe nuclei are the origins of two separate ascending serotonergic systems - one innervating striatal structures and the other mesolimbic structures, predominantly. In addition, the data suggest that measurements of high-affinity uptake of (3H)5-HT may be a more reliable index of innervation than either 5-HT content or tryptophan hydroxylase activity.

Probabilistic Structural Analysis Program

NASA Technical Reports Server (NTRS)

Pai, Shantaram S.; Chamis, Christos C.; Murthy, Pappu L. N.; Stefko, George L.; Riha, David S.; Thacker, Ben H.; Nagpal, Vinod K.; Mital, Subodh K.

2010-01-01

NASA/NESSUS 6.2c is a general-purpose, probabilistic analysis program that computes probability of failure and probabilistic sensitivity measures of engineered systems. Because NASA/NESSUS uses highly computationally efficient and accurate analysis techniques, probabilistic solutions can be obtained even for extremely large and complex models. Once the probabilistic response is quantified, the results can be used to support risk-informed decisions regarding reliability for safety-critical and one-of-a-kind systems, as well as for maintaining a level of quality while reducing manufacturing costs for larger-quantity products. NASA/NESSUS has been successfully applied to a diverse range of problems in aerospace, gas turbine engines, biomechanics, pipelines, defense, weaponry, and infrastructure. This program combines state-of-the-art probabilistic algorithms with general-purpose structural analysis and lifting methods to compute the probabilistic response and reliability of engineered structures. Uncertainties in load, material properties, geometry, boundary conditions, and initial conditions can be simulated. The structural analysis methods include non-linear finite-element methods, heat-transfer analysis, polymer/ceramic matrix composite analysis, monolithic (conventional metallic) materials life-prediction methodologies, boundary element methods, and user-written subroutines. Several probabilistic algorithms are available such as the advanced mean value method and the adaptive importance sampling method. NASA/NESSUS 6.2c is structured in a modular format with 15 elements.

Influence of ordering change on the optical and thermal properties of inflation polyethylene films

NASA Astrophysics Data System (ADS)

Morikawa, Junko; Orie, Akihiro; Hikima, Yuta; Hashimoto, Toshimasa; Juodkazis, Saulius

2011-04-01

Changes of thermal diffusivity inside femtosecond laser-structured volumes as small as few percent were reliably determined (with standard deviation less than 1%) with miniaturized sensors. An increase of thermal diffusivity of a crystalline high-density polyethylene (HDPE) inflation films by 10-20% from the measured (1.16 ± 0.01) × 10 -7 m 2 s -1 value in regions not structured by femtosecond laser pulses is considerably larger than that of non-crystalline polymers, 0-3%. The origin of the change of thermal diffusivity are interplay between the laser induced disordering, voids' formation, compaction, and changes in molecular orientation. It is shown that laser structuring can be used to modify thermal and optical properties. The birefringence and infrared spectroscopy with thermal imaging of CH 2 vibrations are confirming inter-relation between structural, optical, and thermal properties of the laser-structured crystalline HDPE inflation films. Birefringence modulation as high as Δ n ˜ ± 1 × 10 -3 is achieved with grating structures.

High-Yield Synthesis of Stoichiometric Boron Nitride Nanostructures

DOE PAGES

Nocua, José E.; Piazza, Fabrice; Weiner, Brad R.; ...

2009-01-01

Boron nimore » tride (BN) nanostructures are structural analogues of carbon nanostructures but have completely different bonding character and structural defects. They are chemically inert, electrically insulating, and potentially important in mechanical applications that include the strengthening of light structural materials. These applications require the reliable production of bulk amounts of pure BN nanostructures in order to be able to reinforce large quantities of structural materials, hence the need for the development of high-yield synthesis methods of pure BN nanostructures. Using borazine ( B 3 N 3 H 6 ) as chemical precursor and the hot-filament chemical vapor deposition (HFCVD) technique, pure BN nanostructures with cross-sectional sizes ranging between 20 and 50 nm were obtained, including nanoparticles and nanofibers. Their crystalline structure was characterized by (XRD), their morphology and nanostructure was examined by (SEM) and (TEM), while their chemical composition was studied by (EDS), (FTIR), (EELS), and (XPS). Taken altogether, the results indicate that all the material obtained is stoichiometric nanostructured BN with hexagonal and rhombohedral crystalline structure.« less

A Swedish cross-cultural adaptation and validation of the Tinnitus Functional Index.

PubMed

Hoff, Maria; Kähäri, Kim

2017-04-01

The Tinnitus Functional Index (TFI) is a recent self-report instrument for tinnitus with potential advantages over other existing instruments, including a demonstrated high responsiveness. The objectives of this study were to translate and cross-culturally adapt the TFI into Swedish and to investigate its validity and reliability. The development of the Swedish version (TFI-SE) followed published guidelines on cross-cultural adaptation of health questionnaires. Validity and reliability was investigated by correlating responses on the TFI-SE with other tinnitus measures [Tinnitus Handicap Inventory (THI) and visual analogue scale (VAS)] and a scale measuring anxiety and depression (HADS). Consecutively recruited tinnitus patients (n = 100) from four Swedish clinics completed the questionnaires. The mean age of the sample was 51 years (SD =17). The internal consistency of the TFI-SE was good (α = 0.95) and the test-retest reliability was high (ICC =0.93). Our results supported the eight-factor structure proposed for the original TFI, and a high correlation between the TFI-SE and the THI (r = 0.8; p < 0.01) and lower correlations between the TFI-SE and the HADS-D (r = 0.60; p < 0.01) and HADS-A (r = 0.59; p < 0.01) confirmed satisfactory convergent and discriminant validity. We found that the Swedish translation and cross-cultural adaptation of the TFI is valid and reliable for use with adult tinnitus patients.

Structural Reliability and Monte Carlo Simulation.

ERIC Educational Resources Information Center

Laumakis, P. J.; Harlow, G.

2002-01-01

Analyzes a simple boom structure and assesses its reliability using elementary engineering mechanics. Demonstrates the power and utility of Monte-Carlo simulation by showing that such a simulation can be implemented more readily with results that compare favorably to the theoretical calculations. (Author/MM)

Large scale distribution monitoring of FRP-OF based on BOTDR technique for infrastructures

NASA Astrophysics Data System (ADS)

Zhou, Zhi; He, Jianping; Yan, Kai; Ou, Jinping

2007-04-01

BOTDA(R) sensing technique is considered as one of the most practical solution for large-sized structures as the instrument. However, there is still a big obstacle to apply BOTDA(R) in large-scale area due to the high cost and the reliability problem of sensing head which is associated to the sensor installation and survival. In this paper, we report a novel low-cost and high reliable BOTDA(R) sensing head using FRP(Fiber Reinforced Polymer)-bare optical fiber rebar, named BOTDA(R)-FRP-OF. We investigated the surface bonding and its mechanical strength by SEM and intensity experiments. Considering the strain difference between OF and host matrix which may result in measurement error, the strain transfer from host to OF have been theoretically studied. Furthermore, GFRP-OFs sensing properties of strain and temperature at different gauge length were tested under different spatial and readout resolution using commercial BOTDA. Dual FRP-OFs temperature compensation method has also been proposed and analyzed. And finally, BOTDA(R)-OFs have been applied in Tiyu west road civil structure at Guangzhou and Daqing Highway. This novel FRP-OF rebar shows both high strengthen and good sensing properties, which can be used in long-term SHM for civil infrastructures.

Studying tantalum-based high-κ dielectrics in terms of capacitance measurements

NASA Astrophysics Data System (ADS)

Stojanovska-Georgievska, L.

2016-08-01

The trend of rapid development of microelectronics towards nano-miniaturization dictates the inevitable introduction of dielectrics with high permittivity (high-κ dielectrics), as alternative material for replacing SiO2. Therefore, studying these materials in terms of their characteristics, especially in terms of reliability, is of great importance for proper design and manufacture of devices. In this paper, alteration of capacitance in different frequency regimes is used, in order to determine the overall behavior of the material. Samples investigated here are MOS structures containing nanoscale tantalum based dielectrics. Layers of pure Ta2O5, but also Hf and Ti doped tantalum pentoxide, i.e. Ta2O5:Hf and Ta2O5:Ti are studied here. All samples are considered as ultrathin oxide layers with thicknesses less than 15 nm, obtained by radio frequent sputtering on p-type silicon substrate. Measuring capacitive characteristics enables determination of several specific parameters of the structures. The obtained results for capacitance in accumulation, the thickness and time evolution of the interfacial SiO2 layer, values of flatband and threshold voltage, density of oxide charges, interfacial and border states, and reliability properties favor the possibilities for more intensive use of studied materials in new nanoelectronic technologies.

FG Width Scalability of the 3-D Vertical FG NAND Using the Sidewall Control Gate (SCG)

NASA Astrophysics Data System (ADS)

Seo, Moon-Sik; Endoh, Tetsuo

Recently, the 3-D vertical Floating Gate (FG) type NAND cell arrays with the Sidewall Control Gate (SCG), such as ESCG, DC-SF and S-SCG, are receiving attention to overcome the reliability issues of Charge Trap (CT) type device. Using this novel cell structure, highly reliable flash cell operations were successfully implemented without interference effect on the FG type cell. However, the 3-D vertical FG type cell has large cell size by about 60% for the cylindrical FG structure. In this point of view, we intensively investigate the scalability of the FG width of the 3-D vertical FG NAND cells. In case of the planar FG type NAND cell, the FG height cannot be scaled down due to the necessity of obtaining sufficient coupling ratio and high program speed. In contrast, for the 3-D vertical FG NAND with SCG, the FG is formed cylindrically, which is fully covered with surrounded CG, and very high CG coupling ratio can be achieved. As results, the scaling of FG width of the 3-D vertical FG NAND cell with S-SCG can be successfully demonstrated at 10nm regime, which is almost the same as the CT layer of recent BE-SONOS NAND.

Optimization of Adaptive Intraply Hybrid Fiber Composites with Reliability Considerations

NASA Technical Reports Server (NTRS)

Shiao, Michael C.; Chamis, Christos C.

1994-01-01

The reliability with bounded distribution parameters (mean, standard deviation) was maximized and the reliability-based cost was minimized for adaptive intra-ply hybrid fiber composites by using a probabilistic method. The probabilistic method accounts for all naturally occurring uncertainties including those in constituent material properties, fabrication variables, structure geometry, and control-related parameters. Probabilistic sensitivity factors were computed and used in the optimization procedures. For actuated change in the angle of attack of an airfoil-like composite shell structure with an adaptive torque plate, the reliability was maximized to 0.9999 probability, with constraints on the mean and standard deviation of the actuation material volume ratio (percentage of actuation composite material in a ply) and the actuation strain coefficient. The reliability-based cost was minimized for an airfoil-like composite shell structure with an adaptive skin and a mean actuation material volume ratio as the design parameter. At a O.9-mean actuation material volume ratio, the minimum cost was obtained.

Durability reliability analysis for corroding concrete structures under uncertainty

NASA Astrophysics Data System (ADS)

Zhang, Hao

2018-02-01

This paper presents a durability reliability analysis of reinforced concrete structures subject to the action of marine chloride. The focus is to provide insight into the role of epistemic uncertainties on durability reliability. The corrosion model involves a number of variables whose probabilistic characteristics cannot be fully determined due to the limited availability of supporting data. All sources of uncertainty, both aleatory and epistemic, should be included in the reliability analysis. Two methods are available to formulate the epistemic uncertainty: the imprecise probability-based method and the purely probabilistic method in which the epistemic uncertainties are modeled as random variables. The paper illustrates how the epistemic uncertainties are modeled and propagated in the two methods, and shows how epistemic uncertainties govern the durability reliability.

Advanced and safer lithium-ion battery based on sustainable electrodes

NASA Astrophysics Data System (ADS)

Ding, Xiang; Huang, Xiaobing; Jin, Junling; Ming, Hai; Wang, Limin; Ming, Jun

2018-03-01

Seeking advanced and safer lithium-ion battery with sustainable characteristic is significant for the development of electronic devices and electric vehicles. Herein, a new porous TiO2 nanobundles (PTNBs) is synthesized though a scalable and green hydrothermal strategy from the TiO2 powders without using any high-cost and harmful organic titanium-based compounds. The PTNBs exhibits an extremely high lithium storage capacity of 296 mAh g-1 at 100 mA g-1, where the capacity can maintain over 146 mAh g-1 even after 500 cycles at 1000 mA g-1. To pursue more reliable Li-ion batteries, full batteries of PTNBs/LiNixMn1-xO4 (x = 0, 0.5) using spinel structured cathode are constructed. The batteries have the features of sustainability and deliver high capacities of 112 mAh gcathode-1 and 102 mAh gcathode-1 with stable capacity retentions of 99% and 90% over 140 cycles. Note that the energy densities can achieve as high as 267 and 270 Wh kgcathode-1 (535 and 540 Wh kganode-1) respectively, which is feasible to satisfy diverse requirements for energy storage products. We believe that the universal synthetic strategy, appealing structure and intriguing properties of PTNBs is applicable for wider applications, while the concept of sustainable strategy seeking reliable and safer Li-ion battery can attract broad interest.

Distributed collaborative probabilistic design of multi-failure structure with fluid-structure interaction using fuzzy neural network of regression

NASA Astrophysics Data System (ADS)

Song, Lu-Kai; Wen, Jie; Fei, Cheng-Wei; Bai, Guang-Chen

2018-05-01

To improve the computing efficiency and precision of probabilistic design for multi-failure structure, a distributed collaborative probabilistic design method-based fuzzy neural network of regression (FR) (called as DCFRM) is proposed with the integration of distributed collaborative response surface method and fuzzy neural network regression model. The mathematical model of DCFRM is established and the probabilistic design idea with DCFRM is introduced. The probabilistic analysis of turbine blisk involving multi-failure modes (deformation failure, stress failure and strain failure) was investigated by considering fluid-structure interaction with the proposed method. The distribution characteristics, reliability degree, and sensitivity degree of each failure mode and overall failure mode on turbine blisk are obtained, which provides a useful reference for improving the performance and reliability of aeroengine. Through the comparison of methods shows that the DCFRM reshapes the probability of probabilistic analysis for multi-failure structure and improves the computing efficiency while keeping acceptable computational precision. Moreover, the proposed method offers a useful insight for reliability-based design optimization of multi-failure structure and thereby also enriches the theory and method of mechanical reliability design.

Probabilistic Structural Analysis Methods (PSAM) for select space propulsion system components, part 2

NASA Technical Reports Server (NTRS)

1991-01-01

The technical effort and computer code enhancements performed during the sixth year of the Probabilistic Structural Analysis Methods program are summarized. Various capabilities are described to probabilistically combine structural response and structural resistance to compute component reliability. A library of structural resistance models is implemented in the Numerical Evaluations of Stochastic Structures Under Stress (NESSUS) code that included fatigue, fracture, creep, multi-factor interaction, and other important effects. In addition, a user interface was developed for user-defined resistance models. An accurate and efficient reliability method was developed and was successfully implemented in the NESSUS code to compute component reliability based on user-selected response and resistance models. A risk module was developed to compute component risk with respect to cost, performance, or user-defined criteria. The new component risk assessment capabilities were validated and demonstrated using several examples. Various supporting methodologies were also developed in support of component risk assessment.

Validity and reliability of a structured interview for early detection and risk assessment of parenting and developmental problems in young children: a cross-sectional study

PubMed Central

2012-01-01

Background Preventive child health care is well suited for the early detection of parenting and developmental problems. However, as far as the younger age group is concerned, there are no validated early detection instruments which cover both the child and its environment. Therefore, we have developed a broad-scope structured interview which assesses parents’ concerns and their need for support, using both the parental perspective and the experience of the child health care nurse: the Structured Problem Analysis of Raising Kids (SPARK). This study reports the psychometric characteristics of the SPARK. Method A cross-sectional study of 2012 18-month-old children, living in Zeeland, a province of the Netherlands. Inter-rater reliability was assessed in 67 children. Convergent validity was assessed by comparing SPARK-domains with domains in self-report questionnaires on child development and parenting stress. Discriminative validity was assessed by comparing different outcomes of the SPARK between groups with different levels of socio-economic status and by performing an extreme-groups comparison. The user experience of both parents and nurses was assessed with the aid of an online survey. Results The response rate was 92.1% for the SPARK. Self-report questionnaires were returned in the case of 66.9% of the remaining 1721 children. There was selective non-reporting: 33.1% of the questionnaires were not returned, covering 65.2% of the children with a high-risk label according to the SPARK (p < 0.001). Inter-rater reliability was good to excellent with intraclass correlations between 0.85 and 1.0 for physical topics; between 0.61 and 0.8 for social-emotional topics and 0.92 for the overall risk assessment. Convergent validity was unexpectedly low (all correlations ≤0.3) although the pattern was as expected. Discriminative validity was good. Users were satisfied with the SPARK and identified some topics for improvement. Conclusion The SPARK discriminates between children with a high, increased and low risk of parenting and developmental problems. It does so in a reliable way, but more research is needed on aspects of validity and in other populations. PMID:22697218

The new GRID Hamilton Rating Scale for Depression demonstrates excellent inter-rater reliability for inexperienced and experienced raters before and after training.

PubMed

Tabuse, Hideaki; Kalali, Amir; Azuma, Hideki; Ozaki, Norio; Iwata, Nakao; Naitoh, Hiroshi; Higuchi, Teruhiko; Kanba, Shigenobu; Shioe, Kunihiko; Akechi, Tatsuo; Furukawa, Toshi A

2007-09-30

The Hamilton Rating Scale for Depression (HAMD) is the de facto international gold standard for the assessment of depression. There are some criticisms, however, especially with regard to its inter-rater reliability, due to the lack of standardized questions or explicit scoring procedures. The GRID-HAMD was developed to provide standardized explicit scoring conventions and a structured interview guide for administration and scoring of the HAMD. We developed the Japanese version of the GRID-HAMD and examined its inter-rater reliability among experienced and inexperienced clinicians (n=70), how rater characteristics may affect it, and how training can improve it in the course of a model training program using videotaped interviews. The results showed that the inter-rater reliability of the GRID-HAMD total score was excellent to almost perfect and those of most individual items were also satisfactory to excellent, both with experienced and inexperienced raters, and both before and after the training. With its standardized definitions, questions and detailed scoring conventions, the GRID-HAMD appears to be the best achievable set of interview guides for the HAMD and can provide a solid tool for highly reliable assessment of depression severity.

Reliability and Validity of the Korean Version of the Internet Addiction Test among College Students

PubMed Central

Lee, Kounseok; Lee, Hye-Kyung; Gyeong, Hyunsu; Yu, Byeongkwan; Song, Yul-Mai

2013-01-01

We developed a Korean translation of the Internet Addiction Test (KIAT), widely used self-report for internet addiction and tested its reliability and validity in a sample of college students. Two hundred seventy-nine college students at a national university completed the KIAT. Internal consistency and two week test-retest reliability were calculated from the data, and principal component factor analysis was conducted. Participants also completed the Internet Addiction Diagnostic Questionnaire (IADQ), the Korea Internet addiction scale (K-scale), and the Patient Health Questionnaire-9 for the criterion validity. Cronbach's alpha of the whole scale was 0.91, and test-retest reliability was also good (r = 0.73). The IADQ, the K-scale, and depressive symptoms were significantly correlated with the KIAT scores, demonstrating concurrent and convergent validity. The factor analysis extracted four factors (Excessive use, Dependence, Withdrawal, and Avoidance of reality) that accounted for 59% of total variance. The KIAT has outstanding internal consistency and high test-retest reliability. Also, the factor structure and validity data show that the KIAT is comparable to the original version. Thus, the KIAT is a psychometrically sound tool for assessing internet addiction in the Korean-speaking population. PMID:23678270

High power tests of an electroforming cavity operating at 11.424 GHz

NASA Astrophysics Data System (ADS)

Dolgashev, V. A.; Gatti, G.; Higashi, Y.; Leonardi, O.; Lewandowski, J. R.; Marcelli, A.; Rosenzweig, J.; Spataro, B.; Tantawi, S. G.; Yeremian, D. A.

2016-03-01

The achievement of ultra high accelerating gradients is mandatory in order to fabricate compact accelerators at 11.424 GHz for scientific and industrial applications. An extensive experimental and theoretical program to determine a reliable ultra high gradient operation of the future linear accelerators is under way in many laboratories. In particular, systematic studies on the 11.424 GHz frequency accelerator structures, R&D on new materials and the associated microwave technology are in progress to achieve accelerating gradients well above 120 MeV/m. Among the many, the electroforming procedure is a promising approach to manufacture high performance RF devices in order to avoid the high temperature brazing and to produce precise RF structures. We report here the characterization of a hard high gradient RF accelerating structure at 11.424 GHz fabricated using the electroforming technique. Low-level RF measurements and high power RF tests carried out at the SLAC National Accelerator Laboratory on this prototype are presented and discussed. In addition, we present also a possible layout where the water-cooling of irises based on the electroforming process has been considered for the first time.

Advances in Micromechanics Modeling of Composites Structures for Structural Health Monitoring

NASA Astrophysics Data System (ADS)

Moncada, Albert

Although high performance, light-weight composites are increasingly being used in applications ranging from aircraft, rotorcraft, weapon systems and ground vehicles, the assurance of structural reliability remains a critical issue. In composites, damage is absorbed through various fracture processes, including fiber failure, matrix cracking and delamination. An important element in achieving reliable composite systems is a strong capability of assessing and inspecting physical damage of critical structural components. Installation of a robust Structural Health Monitoring (SHM) system would be very valuable in detecting the onset of composite failure. A number of major issues still require serious attention in connection with the research and development aspects of sensor-integrated reliable SHM systems for composite structures. In particular, the sensitivity of currently available sensor systems does not allow detection of micro level damage; this limits the capability of data driven SHM systems. As a fundamental layer in SHM, modeling can provide in-depth information on material and structural behavior for sensing and detection, as well as data for learning algorithms. This dissertation focuses on the development of a multiscale analysis framework, which is used to detect various forms of damage in complex composite structures. A generalized method of cells based micromechanics analysis, as implemented in NASA's MAC/GMC code, is used for the micro-level analysis. First, a baseline study of MAC/GMC is performed to determine the governing failure theories that best capture the damage progression. The deficiencies associated with various layups and loading conditions are addressed. In most micromechanics analysis, a representative unit cell (RUC) with a common fiber packing arrangement is used. The effect of variation in this arrangement within the RUC has been studied and results indicate this variation influences the macro-scale effective material properties and failure stresses. The developed model has been used to simulate impact damage in a composite beam and an airfoil structure. The model data was verified through active interrogation using piezoelectric sensors. The multiscale model was further extended to develop a coupled damage and wave attenuation model, which was used to study different damage states such as fiber-matrix debonding in composite structures with surface bonded piezoelectric sensors.

Porous membrane with high curvature, three-dimensional heat-resistance skeleton: a new and practical separator candidate for high safety lithium ion battery

NASA Astrophysics Data System (ADS)

Shi, Junli; Xia, Yonggao; Yuan, Zhizhang; Hu, Huasheng; Li, Xianfeng; Zhang, Huamin; Liu, Zhaoping

2015-02-01

Separators with high reliability and security are in urgent demand for the advancement of high performance lithium ion batteries. Here, we present a new and practical porous membrane with three-dimension (3D) heat-resistant skeleton and high curvature pore structure as a promising separator candidate to facilitate advances in battery safety and performances beyond those obtained from the conventional separators. The unique material properties combining with the well-developed structural characteristics enable the 3D porous skeleton to own several favorable properties, including superior thermal stability, good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection function, etc. which give rise to acceptable battery performances. Considering the simply and cost-effective preparation process, the porous membrane is deemed to be an interesting direction for the future lithium ion battery separator.

Porous membrane with high curvature, three-dimensional heat-resistance skeleton: a new and practical separator candidate for high safety lithium ion battery

PubMed Central

Shi, Junli; Xia, Yonggao; Yuan, Zhizhang; Hu, Huasheng; Li, Xianfeng; Zhang, Huamin; Liu, Zhaoping

2015-01-01

Separators with high reliability and security are in urgent demand for the advancement of high performance lithium ion batteries. Here, we present a new and practical porous membrane with three-dimension (3D) heat-resistant skeleton and high curvature pore structure as a promising separator candidate to facilitate advances in battery safety and performances beyond those obtained from the conventional separators. The unique material properties combining with the well-developed structural characteristics enable the 3D porous skeleton to own several favorable properties, including superior thermal stability, good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection function, etc. which give rise to acceptable battery performances. Considering the simply and cost-effective preparation process, the porous membrane is deemed to be an interesting direction for the future lithium ion battery separator. PMID:25653104

Porous membrane with high curvature, three-dimensional heat-resistance skeleton: a new and practical separator candidate for high safety lithium ion battery.

PubMed

Shi, Junli; Xia, Yonggao; Yuan, Zhizhang; Hu, Huasheng; Li, Xianfeng; Zhang, Huamin; Liu, Zhaoping

2015-02-05

Separators with high reliability and security are in urgent demand for the advancement of high performance lithium ion batteries. Here, we present a new and practical porous membrane with three-dimension (3D) heat-resistant skeleton and high curvature pore structure as a promising separator candidate to facilitate advances in battery safety and performances beyond those obtained from the conventional separators. The unique material properties combining with the well-developed structural characteristics enable the 3D porous skeleton to own several favorable properties, including superior thermal stability, good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection function, etc. which give rise to acceptable battery performances. Considering the simply and cost-effective preparation process, the porous membrane is deemed to be an interesting direction for the future lithium ion battery separator.

A scoring function based on solvation thermodynamics for protein structure prediction

PubMed Central

Du, Shiqiao; Harano, Yuichi; Kinoshita, Masahiro; Sakurai, Minoru

2012-01-01

We predict protein structure using our recently developed free energy function for describing protein stability, which is focused on solvation thermodynamics. The function is combined with the current most reliable sampling methods, i.e., fragment assembly (FA) and comparative modeling (CM). The prediction is tested using 11 small proteins for which high-resolution crystal structures are available. For 8 of these proteins, sequence similarities are found in the database, and the prediction is performed with CM. Fairly accurate models with average Cα root mean square deviation (RMSD) ∼ 2.0 Å are successfully obtained for all cases. For the rest of the target proteins, we perform the prediction following FA protocols. For 2 cases, we obtain predicted models with an RMSD ∼ 3.0 Å as the best-scored structures. For the other case, the RMSD remains larger than 7 Å. For all the 11 target proteins, our scoring function identifies the experimentally determined native structure as the best structure. Starting from the predicted structure, replica exchange molecular dynamics is performed to further refine the structures. However, we are unable to improve its RMSD toward the experimental structure. The exhaustive sampling by coarse-grained normal mode analysis around the native structures reveals that our function has a linear correlation with RMSDs < 3.0 Å. These results suggest that the function is quite reliable for the protein structure prediction while the sampling method remains one of the major limiting factors in it. The aspects through which the methodology could further be improved are discussed. PMID:27493529

The Fraunhofer MAVO FASPAS for smart system design

NASA Astrophysics Data System (ADS)

Melz, Tobias; Matthias, Michael; Drossel, Welf-Guntram; Sporn, Dieter; Schoenecker, Andreas; Poigne, Axel

2005-05-01

The Fraunhofer Gesellschaft is the largest organization for applied research in Europe, having a staff of some 12,700, predominantly qualified scientists and engineers, with an annual research budget of over one billion euros. One of its current internal Market-oriented strategic preliminary research (MaVo) projects is FASPAS (Function Consolidated Adaptive Structures Combining Piezo and Software Technologies for Autonomous Systems) which aims to promote adaptive structure technology for commercial exploitation within the current main research fields of the participating FhIs, namely automotive and machine tools engineering. Under the project management of the Fraunhofer-Institute Structural Durability and System Reliability LBF the six Fraunhofer Institutes LBF, IWU, IKTS, ISC, AiS and IIS bring together their competences ranging from material sciences to system reliability, in order to clarify unanswered questions. The predominant goal is to develop and validate methods and tools to establish a closed, modular development chain for the design and realization of such active structures which shall be useful in its width and depth, i.e. for specific R&D achievements such as the actuator development (depth) as well as the complete system design and realization (width). FASPAS focuses on the development of systems and on the following scientific topics: 1) on design and manufacturing technology for piezo components as integrable actuator/sensor semi-finished modules, 2) on development and transducer module integration of miniaturized electronics for charge generating sensor systems, 3) on the development of methods to analyze system reliability of active structures, 4) on the development of autonomous software structures for flexible, low cost electronics hardware for bulk production and 5) on the construction and validation of the complete, cost-effective development chain of function consolidated structures through application oriented demonstration structures. The research work will be oriented towards active vibration control for existing components on the basis of highly integrated, both, more or less established and highly innovative piezoelectric actuator and sensor systems in compact, cost-effective and robust design combined with advanced controllers. Within the presentation the project work will be shown using the example of one demonstration structure which is a robust interface, here for being integrated within an automotive spring strut system. The interface is designed as a modular, scalable subsystem. Being such, it can be used for similar scenarios in different technology areas e.g. for active mounting of vibration-inducing aggregates. The interface design allows for controlling uniaxial vibrations (z-direction) as well as tilting (normal to the uniaxial effect) and wobbling (rotating around the z-axis).

Modeling and numerical simulations of growth and morphologies of three dimensional aggregated silver films

NASA Astrophysics Data System (ADS)

Davis, L. J.; Boggess, M.; Kodpuak, E.; Deutsch, M.

2012-11-01

We report on a model for the deposition of three dimensional, aggregated nanocrystalline silver films, and an efficient numerical simulation method developed for visualizing such structures. We compare our results to a model system comprising chemically deposited silver films with morphologies ranging from dilute, uniform distributions of nanoparticles to highly porous aggregated networks. Disordered silver films grown in solution on silica substrates are characterized using digital image analysis of high resolution scanning electron micrographs. While the latter technique provides little volume information, plane-projected (two dimensional) island structure and surface coverage may be reliably determined. Three parameters governing film growth are evaluated using these data and used as inputs for the deposition model, greatly reducing computing requirements while still providing direct access to the complete (bulk) structure of the films throughout the growth process. We also show how valuable three dimensional characteristics of the deposited materials can be extracted using the simulated structures.

Thermal modal analysis of novel non-pneumatic mechanical elastic wheel based on FEM and EMA

NASA Astrophysics Data System (ADS)

Zhao, Youqun; Zhu, Mingmin; Lin, Fen; Xiao, Zhen; Li, Haiqing; Deng, Yaoji

2018-01-01

A combination of Finite Element Method (FEM) and Experiment Modal Analysis (EMA) have been employed here to characterize the structural dynamic response of mechanical elastic wheel (ME-Wheel) operating under a specific thermal environment. The influence of high thermal condition on the structural dynamic response of ME-Wheel is investigated. The obtained results indicate that the EMA results are in accordance with those obtained using the proposed Finite Element (FE) model, indicting the high reliability of this FE model applied in analyzing the modal of ME-Wheel working under practical thermal environment. It demonstrates that the structural dynamic response of ME-Wheel operating under a specific thermal condition can be predicted and evaluated using the proposed analysis method, which is beneficial for the dynamic optimization design of the wheel structure to avoid tire temperature related vibration failure and improve safety of tire.

Probing and Manipulating the Interfacial Defects of InGaAs Dual-Layer Metal Oxides at the Atomic Scale.

PubMed

Wu, Xing; Luo, Chen; Hao, Peng; Sun, Tao; Wang, Runsheng; Wang, Chaolun; Hu, Zhigao; Li, Yawei; Zhang, Jian; Bersuker, Gennadi; Sun, Litao; Pey, Kinleong

2018-01-01

The interface between III-V and metal-oxide-semiconductor materials plays a central role in the operation of high-speed electronic devices, such as transistors and light-emitting diodes. The high-speed property gives the light-emitting diodes a high response speed and low dark current, and they are widely used in communications, infrared remote sensing, optical detection, and other fields. The rational design of high-performance devices requires a detailed understanding of the electronic structure at this interface; however, this understanding remains a challenge, given the complex nature of surface interactions and the dynamic relationship between the morphology evolution and electronic structures. Herein, in situ transmission electron microscopy is used to probe and manipulate the structural and electrical properties of ZrO 2 films on Al 2 O 3 and InGaAs substrate at the atomic scale. Interfacial defects resulting from the spillover of the oxygen-atom conduction-band wavefunctions are resolved. This study unearths the fundamental defect-driven interfacial electric structure of III-V semiconductor materials and paves the way to future high-speed and high-reliability devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of interlocking bond strength between structured 1.0338 steel sheets and high pressure die cast AlMg5Si2

NASA Astrophysics Data System (ADS)

Senge, S.; Brachmann, J.; Hirt, G.; Bührig-Polaczek, A.

2018-05-01

Multi-material components open up new possibilities for functional design. Such components combine beneficial physical properties of different materials in a single component as for instance chemical resistance, high strength or low density. The challenge is a reliable bond between both materials to enable a long term usage. This paper deals with a form closure connection to ensure a solid connection between steel strips and high pressure die cast aluminium. Two different sizes of channel structures with width ratios of 1.0 and 1.35 are produced on a steel sheet. An ensuing flat rolling pass is performed to create undercuts with a width of up to 50 µm, enabling an interlocking of the molten aluminium in the concluding casting process. For both rolling processes the resulting geometry is analysed depending on the thickness reduction. In a subsequent high pressure die casting process, aluminium is applied resulting in a complete form filling for the coarser structure. Comparing structures with and without undercuts, only structures suited with undercuts remain gap-free after solidification contraction. The finer structure could not be filled completely; nevertheless these structures result in shear strength of up to 45 MPa transversal to the channel-direction.

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.

Tunable nanoblock lasers and stretching sensors.

PubMed

Lu, T W; Wang, C; Hsiao, C F; Lee, P T

2016-09-22

Reconfigurable, reliable, and robust nanolasers with wavelengths tunable in the telecommunication bands are currently being sought after for use as flexible light sources in photonic integrated circuits. Here, we propose and demonstrate tunable nanolasers based on 1D nanoblocks embedded within stretchable polydimethylsiloxane. Our lasers show a large wavelength tunability of 7.65 nm per 1% elongation. Moreover, this tunability is reconfigurable and reliable under repeated stretching/relaxation tests. By applying excessive stretching, wide wavelength tuning over a range of 80 nm (spanning the S, C, and L telecommunication bands) is successfully demonstrated. Furthermore, as a stretching sensor, an enhanced wavelength response to elongation of 9.9 nm per % is obtained via the signal differential from two nanoblock lasers positioned perpendicular to each other. The minimum detectable elongation is as small as 0.056%. Nanoblock lasers can function as reliable tunable light sources in telecommunications and highly sensitive on-chip structural deformation sensors.

Examining the Factor Structure and Reliability of the Safe Patient Handling Perception Scale: An Initial Validation Study.

PubMed

White-Heisel, Regina; Canfield, James P; Young-Hughes, Sadie

Perceiving imminent safe patient handling and movement (SPH&M) dangers may reduce musculoskeletal (MSK) injuries for nurses in the workplace. The purpose of this study is to develop and validate the 17-item Safe Patient Handling Perception Scale (SPHPS) as an evaluation instrument assessing perceptual risk of MSK injury based on SPH&M knowledge, practice, and resource accessibility in the workplace. Data were collected from a convenience sample (N = 117) of nursing employees at a Veteran Affairs Medical Center. Factor analysis identified three factors: knowledge, practice, and accessibility. The SPHPS demonstrated high levels of reliability, supported by acceptable alpha scores (SPHM knowledge [α = .866], SPHM practices [α = .901], and access to SPHM resources [α = .855]), in addition to the relatively low standard error of measurement scores (SEM). The study outcomes suggest that the SPHPS is a valid and reliable tool that can measure participants' perceived risk factors for MSK injuries.

Reliability Testing of NASA Piezocomposite Actuators

NASA Technical Reports Server (NTRS)

Wilkie, W.; High, J.; Bockman, J.

2002-01-01

NASA Langley Research Center has developed a low-cost piezocomposite actuator which has application for controlling vibrations in large inflatable smart space structures, space telescopes, and high performance aircraft. Tests show the NASA piezocomposite device is capable of producing large, directional, in-plane strains on the order of 2000 parts-per-million peak-to-peak, with no reduction in free-strain performance to 100 million electrical cycles. This paper describes methods, measurements, and preliminary results from our reliability evaluation of the device under externally applied mechanical loads and at various operational temperatures. Tests performed to date show no net reductions in actuation amplitude while the device was moderately loaded through 10 million electrical cycles. Tests were performed at both room temperature and at the maximum operational temperature of the epoxy resin system used in manufacture of the device. Initial indications are that actuator reliability is excellent, with no actuator failures or large net reduction in actuator performance.

Reliability-based optimization of an active vibration controller using evolutionary algorithms

NASA Astrophysics Data System (ADS)

Saraygord Afshari, Sajad; Pourtakdoust, Seid H.

2017-04-01

Many modern industrialized systems such as aircrafts, rotating turbines, satellite booms, etc. cannot perform their desired tasks accurately if their uninhibited structural vibrations are not controlled properly. Structural health monitoring and online reliability calculations are emerging new means to handle system imposed uncertainties. As stochastic forcing are unavoidable, in most engineering systems, it is often needed to take them into the account for the control design process. In this research, smart material technology is utilized for structural health monitoring and control in order to keep the system in a reliable performance range. In this regard, a reliability-based cost function is assigned for both controller gain optimization as well as sensor placement. The proposed scheme is implemented and verified for a wing section. Comparison of results for the frequency responses is considered to show potential applicability of the presented technique.

Uncertainties in obtaining high reliability from stress-strength models

NASA Technical Reports Server (NTRS)

Neal, Donald M.; Matthews, William T.; Vangel, Mark G.

1992-01-01

There has been a recent interest in determining high statistical reliability in risk assessment of aircraft components. The potential consequences are identified of incorrectly assuming a particular statistical distribution for stress or strength data used in obtaining the high reliability values. The computation of the reliability is defined as the probability of the strength being greater than the stress over the range of stress values. This method is often referred to as the stress-strength model. A sensitivity analysis was performed involving a comparison of reliability results in order to evaluate the effects of assuming specific statistical distributions. Both known population distributions, and those that differed slightly from the known, were considered. Results showed substantial differences in reliability estimates even for almost nondetectable differences in the assumed distributions. These differences represent a potential problem in using the stress-strength model for high reliability computations, since in practice it is impossible to ever know the exact (population) distribution. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability. An alternative reliability computation procedure is examined involving determination of a lower bound on the reliability values using extreme value distributions. This procedure reduces the possibility of obtaining nonconservative reliability estimates. Results indicated the method can provide conservative bounds when computing high reliability.

From a formal training program in musculoskeletal ultrasound (MSUS) to a high reproducibility for Doppler ultrasound in rheumatoid arthritis.

PubMed

Villota, Orlando; Diaz, Mario; Ceron, Carmen; Moller, Ingrid; Naredo, Esperanza; Saaibi, Diego Luis

2017-07-28

To assess the intra- and inter-observer reliability of ultrasound (US) in scoring B-mode, Doppler synovitis and combined B-mode and Doppler synovitis scores in different peripheral joints of rheumatoid arthritis (RA) patients. Four rheumatologists with a formal training in musculoskeletal US (MSKUS) particularly focus on definitions and scoring synovitis on B-mode and Doppler mode participated in a patient-based reliability exercise on 16 active RA patients. The four rheumatologists independently and consecutively performed a B-mode and power Doppler (PD) US assessment of 7 joints of each patient in two rounds in a blinded fashion. Each joint was semi quantitatively scored from 0 to 3 for B-mode synovitis (BS), Doppler synovitis (DS), and combined B-mode/Doppler synovitis (CS). Intraobserver reliability was assessed by Cohen's κ. Interobserver reliability was assessed by unweight Light's κ. The mean prevalence of synovitis on B-mode was 83% of joints; scores ranging from grade 1 in 18% of joints, to grade 3 in 33%. In 55% of joints synovial PD signal was detected and the distribution of scores range from 14% of joints for grade 3, to 26% for grade 2. After a total of 448 joints scanned with 896 adquired images our intraobserver and interobserver reliability was good to excellent for most of the joints. Formal, structured and continuous training in musculoskeletal ultrasound would bring a good to excellent reproducibility in rheumatological hands with a high reliability in real time acquisition BS, DS and CS modalities for scoring synovitis in patients with active rheumatoid arthritis. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Study of Fuze Structure and Reliability Design Based on the Direct Search Method

NASA Astrophysics Data System (ADS)

Lin, Zhang; Ning, Wang

2017-03-01

Redundant design is one of the important methods to improve the reliability of the system, but mutual coupling of multiple factors is often involved in the design. In my study, Direct Search Method is introduced into the optimum redundancy configuration for design optimization, in which, the reliability, cost, structural weight and other factors can be taken into account simultaneously, and the redundant allocation and reliability design of aircraft critical system are computed. The results show that this method is convenient and workable, and applicable to the redundancy configurations and optimization of various designs upon appropriate modifications. And this method has a good practical value.

The use of test structures for reliability prediction and process control of integrated circuits and photovoltaics

NASA Astrophysics Data System (ADS)

Trachtenberg, I.

How a reliability model might be developed with new data from accelerated stress testing, failure mechanisms, process control monitoring, and test structure evaluations is illustrated. The effects of the acceleration of temperature on operating life is discussed. Test structures that will further accelerate the failure rate are discussed. Corrosion testing is addressed. The uncoated structure is encapsulated in a variety of mold compounds and subjected to pressure-cooker testing.

Why the Major Field Test in Business Does Not Report Subscores: Reliability and Construct Validity Evidence. Research Report. ETS RR-12-11

ERIC Educational Resources Information Center

Ling, Guangming

2012-01-01

To assess the value of individual students' subscores on the Major Field Test in Business (MFT Business), I examined the test's internal structure with factor analysis and structural equation model methods, and analyzed the subscore reliabilities using the augmented scores method. Analyses of the internal structure suggested that the MFT Business…

Intrarater Reliability of Muscle Strength and Hamstring to Quadriceps Strength Imbalance Ratios During Concentric, Isometric, and Eccentric Maximal Voluntary Contractions Using the Isoforce Dynamometer.

PubMed

Mau-Moeller, Anett; Gube, Martin; Felser, Sabine; Feldhege, Frank; Weippert, Matthias; Husmann, Florian; Tischer, Thomas; Bader, Rainer; Bruhn, Sven; Behrens, Martin

2017-08-17

To determine intrasession and intersession reliability of strength measurements and hamstrings to quadriceps strength imbalance ratios (H/Q ratios) using the new isoforce dynamometer. Repeated measures. Exercise science laboratory. Thirty healthy subjects (15 females, 15 males, 27.8 years). Coefficient of variation (CV) and intraclass correlation coefficients (ICC) were calculated for (1) strength parameters, that is peak torque, mean work, and mean power for concentric and eccentric maximal voluntary contractions; isometric maximal voluntary torque (IMVT); rate of torque development (RTD), and (2) H/Q ratios, that is conventional concentric, eccentric, and isometric H/Q ratios (Hcon/Qcon at 60 deg/s, 120 deg/s, and 180 deg/s, Hecc/Qecc at -60 deg/s and Hiso/Qiso) and functional eccentric antagonist to concentric agonist H/Q ratios (Hecc/Qcon and Hcon/Qecc). High reliability: CV <10%, ICC >0.90; moderate reliability: CV between 10% and 20%, ICC between 0.80 and 0.90; low reliability: CV >20%, ICC <0.80. (1) Strength parameters: (a) high intrasession reliability for concentric, eccentric, and isometric measurements, (b) moderate-to-high intersession reliability for concentric and eccentric measurements and IMVT, and (c) moderate-to-high intrasession reliability but low intersession reliability for RTD. (2) H/Q ratios: (a) moderate-to-high intrasession reliability for conventional ratios, (b) high intrasession reliability for functional ratios, (c) higher intersession reliability for Hcon/Qcon and Hiso/Qiso (moderate to high) than Hecc/Qecc (low to moderate), and (d) higher intersession reliability for conventional H/Q ratios (low to high) than functional H/Q ratios (low to moderate). The results have confirmed the reliability of strength parameters and the most frequently used H/Q ratios.

Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

NASA Astrophysics Data System (ADS)

Broukalová, I.; Šeps, K.

2017-09-01

The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

Application of Kingview and PLC in friction durability test system

NASA Astrophysics Data System (ADS)

Gao, Yinhan; Cui, Jing; Yang, Kaiyu; Ke, Hui; Song, Bing

2013-01-01

Using PLC and Kingview software, a friction durability test system is designed. The overall program, hardware configuration, software structure and monitoring interface are described in detail. PLC ensures the stability of data acquisition, and the KingView software makes the HMI easy to manipulate. The practical application shows that the proposed system is cheap, economical and highly reliable.

Construction and Validation of the Career and Educational Decision Self-Efficacy Inventory for Secondary Students (CEDSIS)

ERIC Educational Resources Information Center

Ho, Esther Sui Chu; Sum, Kwok Wing

2018-01-01

This study aims to construct and validate the Career and Educational Decision Self-Efficacy Inventory for Secondary Students (CEDSIS) by using a sample of 2,631 students in Hong Kong. Principal component analysis yielded a three-factor structure, which demonstrated good model fit in confirmatory factor analysis. High reliability was found for the…

The Development and Validation of a Concise Instrument for Formative Assessment of Team Leader Performance During Simulated Pediatric Resuscitations.

PubMed

Nadkarni, Lindsay D; Roskind, Cindy G; Auerbach, Marc A; Calhoun, Aaron W; Adler, Mark D; Kessler, David O

2018-04-01

The aim of this study was to assess the validity of a formative feedback instrument for leaders of simulated resuscitations. This is a prospective validation study with a fully crossed (person × scenario × rater) study design. The Concise Assessment of Leader Management (CALM) instrument was designed by pediatric emergency medicine and graduate medical education experts to be used off the shelf to evaluate and provide formative feedback to resuscitation leaders. Four experts reviewed 16 videos of in situ simulated pediatric resuscitations and scored resuscitation leader performance using the CALM instrument. The videos consisted of 4 pediatric emergency department resuscitation teams each performing in 4 pediatric resuscitation scenarios (cardiac arrest, respiratory arrest, seizure, and sepsis). We report on content and internal structure (reliability) validity of the CALM instrument. Content validity was supported by the instrument development process that involved professional experience, expert consensus, focused literature review, and pilot testing. Internal structure validity (reliability) was supported by the generalizability analysis. The main component that contributed to score variability was the person (33%), meaning that individual leaders performed differently. The rater component had almost zero (0%) contribution to variance, which implies that raters were in agreement and argues for high interrater reliability. These results provide initial evidence to support the validity of the CALM instrument as a reliable assessment instrument that can facilitate formative feedback to leaders of pediatric simulated resuscitations.

Separating Common from Unique Variance Within Emotional Distress: An Examination of Reliability and Relations to Worry.

PubMed

Marshall, Andrew J; Evanovich, Emma K; David, Sarah Jo; Mumma, Gregory H

2018-01-17

High comorbidity rates among emotional disorders have led researchers to examine transdiagnostic factors that may contribute to shared psychopathology. Bifactor models provide a unique method for examining transdiagnostic variables by modelling the common and unique factors within measures. Previous findings suggest that the bifactor model of the Depression Anxiety and Stress Scale (DASS) may provide a method for examining transdiagnostic factors within emotional disorders. This study aimed to replicate the bifactor model of the DASS, a multidimensional measure of psychological distress, within a US adult sample and provide initial estimates of the reliability of the general and domain-specific factors. Furthermore, this study hypothesized that Worry, a theorized transdiagnostic variable, would show stronger relations to general emotional distress than domain-specific subscales. Confirmatory factor analysis was used to evaluate the bifactor model structure of the DASS in 456 US adult participants (279 females and 177 males, mean age 35.9 years) recruited online. The DASS bifactor model fitted well (CFI = 0.98; RMSEA = 0.05). The General Emotional Distress factor accounted for most of the reliable variance in item scores. Domain-specific subscales accounted for modest portions of reliable variance in items after accounting for the general scale. Finally, structural equation modelling indicated that Worry was strongly predicted by the General Emotional Distress factor. The DASS bifactor model is generalizable to a US community sample and General Emotional Distress, but not domain-specific factors, strongly predict the transdiagnostic variable Worry.

Reliability analysis of single crystal NiAl turbine blades

NASA Technical Reports Server (NTRS)

Salem, Jonathan; Noebe, Ronald; Wheeler, Donald R.; Holland, Fred; Palko, Joseph; Duffy, Stephen; Wright, P. Kennard

1995-01-01

As part of a co-operative agreement with General Electric Aircraft Engines (GEAE), NASA LeRC is modifying and validating the Ceramic Analysis and Reliability Evaluation of Structures algorithm for use in design of components made of high strength NiAl based intermetallic materials. NiAl single crystal alloys are being actively investigated by GEAE as a replacement for Ni-based single crystal superalloys for use in high pressure turbine blades and vanes. The driving force for this research lies in the numerous property advantages offered by NiAl alloys over their superalloy counterparts. These include a reduction of density by as much as a third without significantly sacrificing strength, higher melting point, greater thermal conductivity, better oxidation resistance, and a better response to thermal barrier coatings. The current drawback to high strength NiAl single crystals is their limited ductility. Consequently, significant efforts including the work agreement with GEAE are underway to develop testing and design methodologies for these materials. The approach to validation and component analysis involves the following steps: determination of the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; measurement of the failure strength envelope of the material; coding of statistically based reliability models; verification of the code and model; and modeling of turbine blades and vanes for rig testing.

[An instrument in Spanish to evaluate the performance of clinical teachers by students].

PubMed

Bitran, Marcela; Mena, Beltrán; Riquelme, Arnoldo; Padilla, Oslando; Sánchez, Ignacio; Moreno, Rodrigo

2010-06-01

The modernization of clinical teaching has called for the creation of faculty development programs, and the design of suitable instruments to evaluate clinical teachers' performance. To report the development and validation of an instrument in Spanish designed to measure the students' perceptions of their clinical teachers' performance and to provide them with feedback to improve their teaching practices. In a process that included the active participation of authorities, professors in charge of courses and internships, clinical teachers, students and medical education experts, we developed a 30-item questionnaire called MEDUC30 to evaluate the performance of clinical teachers by their students. The internal validity was assessed by factor analysis of 5214 evaluations of 265 teachers, gathered from 2004 to 2007. The reliability was measured with the Cronbach's alpha coefficient and the generalizability coefficient (g). MEDUC30 had good content and construct validity. Its internal structure was compatible with four factors: patient-centered teaching, teaching skills, assessment skills and learning climate, and it proved to be consistent with the structure anticipated by the theory. The scores were highly reliable (Cronbach's alpha: 0.97); five evaluations per teacher were sufficient to reach a reliability coefficient (g) of 0.8. MEDUC30 is a valid, reliable and useful instrument to evaluate the performance of clinical teachers. To our knowledge, this is the first instrument in Spanish for which solid validity and reliability evidences have been reported. We hope that MEDUC30 will be used to improve medical education in Spanish-speaking medical schools, providing teachers a specific feedback upon which to improve their pedagogical practice, and authorities with valuable information for the assessment of their faculty.

A study of the validity and the reliability of the Geriatric Anxiety Inventory in screening for anxiety after stroke in older inpatients.

PubMed

Kneebone, Ian I; Fife-Schaw, Chris; Lincoln, Nadina B; Harder, Helena

2016-12-01

To investigate the validity and reliability of the Geriatric Anxiety Inventory in screening for anxiety in older inpatients post-stroke. Longitudinal. A total of 81 inpatients with stroke aged 65 years or older were recruited at four centres in England. At phase 1 the Geriatric Anxiety Inventory and the Hospital Anxiety and Depression Scale were administered and then the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders 4th edition (phase 2). The Geriatric Anxiety Inventory was repeated a median of seven days later (phase 3). Internal reliability of the Geriatric Anxiety Inventory was high (α = 0.95) and test-retest reliability acceptable (τB = 0.53). Construct validity was evident relative to the Hospital Anxiety and Depression Scale - Anxiety subscale (τB = 0.61). At a cut off of 6/7, sensitivity of the Geriatric Anxiety Inventory was 0.88, specificity 0.84, with respect to the Structured Clinical Interview anxiety diagnosis. Hospital Anxiety and Depressions Scale - Anxiety subscale sensitivity was 0.88, specificity 0.54 at the optimum cut off of 5/6. A comparison of the areas under the curve of the Receiver Operating Characteristics for the two instruments indicated that the area under the curve of the Geriatric Anxiety Inventory was significantly larger than that of the Hospital Anxiety and Depressions Scale - Anxiety subscale, supporting its superiority. The Geriatric Anxiety Inventory is an internally consistent, reliable (stable) and valid instrument with acceptable sensitivity and specificity to screen for anxiety in older inpatients with stroke. © The Author(s) 2015.

An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions.

PubMed

Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

2016-02-26

Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack propagation under changing structural boundary conditions can be monitored reliably. The method is not limited by the properties of the structure, and thus it is feasible to be applied to composite structure.

Subcortical structure segmentation using probabilistic atlas priors

NASA Astrophysics Data System (ADS)

Gouttard, Sylvain; Styner, Martin; Joshi, Sarang; Smith, Rachel G.; Cody Hazlett, Heather; Gerig, Guido

2007-03-01

The segmentation of the subcortical structures of the brain is required for many forms of quantitative neuroanatomic analysis. The volumetric and shape parameters of structures such as lateral ventricles, putamen, caudate, hippocampus, pallidus and amygdala are employed to characterize a disease or its evolution. This paper presents a fully automatic segmentation of these structures via a non-rigid registration of a probabilistic atlas prior and alongside a comprehensive validation. Our approach is based on an unbiased diffeomorphic atlas with probabilistic spatial priors built from a training set of MR images with corresponding manual segmentations. The atlas building computes an average image along with transformation fields mapping each training case to the average image. These transformation fields are applied to the manually segmented structures of each case in order to obtain a probabilistic map on the atlas. When applying the atlas for automatic structural segmentation, an MR image is first intensity inhomogeneity corrected, skull stripped and intensity calibrated to the atlas. Then the atlas image is registered to the image using an affine followed by a deformable registration matching the gray level intensity. Finally, the registration transformation is applied to the probabilistic maps of each structures, which are then thresholded at 0.5 probability. Using manual segmentations for comparison, measures of volumetric differences show high correlation with our results. Furthermore, the dice coefficient, which quantifies the volumetric overlap, is higher than 62% for all structures and is close to 80% for basal ganglia. The intraclass correlation coefficient computed on these same datasets shows a good inter-method correlation of the volumetric measurements. Using a dataset of a single patient scanned 10 times on 5 different scanners, reliability is shown with a coefficient of variance of less than 2 percents over the whole dataset. Overall, these validation and reliability studies show that our method accurately and reliably segments almost all structures. Only the hippocampus and amygdala segmentations exhibit relative low correlation with the manual segmentation in at least one of the validation studies, whereas they still show appropriate dice overlap coefficients.

Development of a nanosatellite de-orbiting system by reliability based design optimization

NASA Astrophysics Data System (ADS)

Nikbay, Melike; Acar, Pınar; Aslan, Alim Rüstem

2015-12-01

This paper presents design approaches to develop a reliable and efficient de-orbiting system for the 3USAT nanosatellite to provide a beneficial orbital decay process at the end of a mission. A de-orbiting system is initially designed by employing the aerodynamic drag augmentation principle where the structural constraints of the overall satellite system and the aerodynamic forces are taken into account. Next, an alternative de-orbiting system is designed with new considerations and further optimized using deterministic and reliability based design techniques. For the multi-objective design, the objectives are chosen to maximize the aerodynamic drag force through the maximization of the Kapton surface area while minimizing the de-orbiting system mass. The constraints are related in a deterministic manner to the required deployment force, the height of the solar panel hole and the deployment angle. The length and the number of layers of the deployable Kapton structure are used as optimization variables. In the second stage of this study, uncertainties related to both manufacturing and operating conditions of the deployable structure in space environment are considered. These uncertainties are then incorporated into the design process by using different probabilistic approaches such as Monte Carlo Simulation, the First-Order Reliability Method and the Second-Order Reliability Method. The reliability based design optimization seeks optimal solutions using the former design objectives and constraints with the inclusion of a reliability index. Finally, the de-orbiting system design alternatives generated by different approaches are investigated and the reliability based optimum design is found to yield the best solution since it significantly improves both system reliability and performance requirements.

Development and validation of an instrument to assess perceived social influence on health behaviors

PubMed Central

HOLT, CHERYL L.; CLARK, EDDIE M.; ROTH, DAVID L.; CROWTHER, MARTHA; KOHLER, CONNIE; FOUAD, MONA; FOUSHEE, RUSTY; LEE, PATRICIA A.; SOUTHWARD, PENNY L.

2012-01-01

Assessment of social influence on health behavior is often approached through a situational context. The current study adapted an existing, theory-based instrument from another content domain to assess Perceived Social Influence on Health Behavior (PSI-HB) among African Americans, using an individual difference approach. The adapted instrument was found to have high internal reliability (α = .81–.84) and acceptable testretest reliability (r = .68–.85). A measurement model revealed a three-factor structure and supported the theoretical underpinnings. Scores were predictive of health behaviors, particularly among women. Future research using the new instrument may have applied value assessing social influence in the context of health interventions. PMID:20522506

Development and initial validation of the internalization of Asian American stereotypes scale.

PubMed

Shen, Frances C; Wang, Yu-Wei; Swanson, Jane L

2011-07-01

This research consists of four studies on the initial reliability and validity of the Internalization of Asian American Stereotypes Scale (IAASS), a self-report instrument that measures the degree Asian Americans have internalized racial stereotypes about their own group. The results from the exploratory and confirmatory factor analyses support a stable four-factor structure of the IAASS: Difficulties with English Language Communication, Pursuit of Prestigious Careers, Emotional Reservation, and Expected Academic Success. Evidence for concurrent and discriminant validity is presented. High internal-consistency and test-retest reliability estimates are reported. A discussion of how this scale can contribute to research and practice regarding internalized stereotyping among Asian Americans is provided.

Design and testing of the Space Station Freedom Propellant Tank Assembly

NASA Technical Reports Server (NTRS)

Dudley, D. D.; Thonet, T. A.; Goforth, A. M.

1992-01-01

Propellant storage and management functions for the Propulsion Module of the U.S. Space Station Freedom are provided by the Propellant Tank Assembly (PTA). The PTA consists of a surface-tension type propellant acquisition device contained within a welded titanium pressure vessel. The PTA design concept was selected with high reliability and low program risk as primary goals in order to meet stringent NASA structural, expulsion, fracture control and reliability requirements. The PTA design makes use of Shuttle Orbital Maneuvering System and Peacekeeper Propellant Storage Assembly design and analysis techniques. This paper summarizes the PTA design solution and discusses the underlying detailed analyses. In addition, design verification and qualification test activities are discussed.

Design of on-board Bluetooth wireless network system based on fault-tolerant technology

NASA Astrophysics Data System (ADS)

You, Zheng; Zhang, Xiangqi; Yu, Shijie; Tian, Hexiang

2007-11-01

In this paper, the Bluetooth wireless data transmission technology is applied in on-board computer system, to realize wireless data transmission between peripherals of the micro-satellite integrating electronic system, and in view of the high demand of reliability of a micro-satellite, a design of Bluetooth wireless network based on fault-tolerant technology is introduced. The reliability of two fault-tolerant systems is estimated firstly using Markov model, then the structural design of this fault-tolerant system is introduced; several protocols are established to make the system operate correctly, some related problems are listed and analyzed, with emphasis on Fault Auto-diagnosis System, Active-standby switch design and Data-Integrity process.

Ceramic technology for advanced heat engines project. Semiannual progress report, October 1985-March 1986

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

Not Available

1986-08-01

Significant accomplishments in fabricating cermaic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, additional research is needed in materials and processing development, design methodology, and data base and life prediction. An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotivemore » heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.« less

Multiple objective optimization in reliability demonstration test

DOE PAGES

Lu, Lu; Anderson-Cook, Christine Michaela; Li, Mingyang

2016-10-01

Reliability demonstration tests are usually performed in product design or validation processes to demonstrate whether a product meets specified requirements on reliability. For binomial demonstration tests, the zero-failure test has been most commonly used due to its simplicity and use of minimum sample size to achieve an acceptable consumer’s risk level. However, this test can often result in unacceptably high risk for producers as well as a low probability of passing the test even when the product has good reliability. This paper explicitly explores the interrelationship between multiple objectives that are commonly of interest when planning a demonstration test andmore » proposes structured decision-making procedures using a Pareto front approach for selecting an optimal test plan based on simultaneously balancing multiple criteria. Different strategies are suggested for scenarios with different user priorities and graphical tools are developed to help quantify the trade-offs between choices and to facilitate informed decision making. As a result, potential impacts of some subjective user inputs on the final decision are studied to offer insights and useful guidance for general applications.« less

Hybrid time-variant reliability estimation for active control structures under aleatory and epistemic uncertainties

NASA Astrophysics Data System (ADS)

Wang, Lei; Xiong, Chuang; Wang, Xiaojun; Li, Yunlong; Xu, Menghui

2018-04-01

Considering that multi-source uncertainties from inherent nature as well as the external environment are unavoidable and severely affect the controller performance, the dynamic safety assessment with high confidence is of great significance for scientists and engineers. In view of this, the uncertainty quantification analysis and time-variant reliability estimation corresponding to the closed-loop control problems are conducted in this study under a mixture of random, interval, and convex uncertainties. By combining the state-space transformation and the natural set expansion, the boundary laws of controlled response histories are first confirmed with specific implementation of random items. For nonlinear cases, the collocation set methodology and fourth Rounge-Kutta algorithm are introduced as well. Enlightened by the first-passage model in random process theory as well as by the static probabilistic reliability ideas, a new definition of the hybrid time-variant reliability measurement is provided for the vibration control systems and the related solution details are further expounded. Two engineering examples are eventually presented to demonstrate the validity and applicability of the methodology developed.

Development and testing of the questionnaire CEC-61: Knowledge about cervical cancer in Chilean adolescents.

PubMed

Urrutia, María Teresa; Gajardo, Macarena; Padilla, Oslando

2017-05-22

Despite a clear association between human papillomavirus and cervical cancer, knowledge in adolescent populations regarding the disease and methods for its detection and prevention is deficient. The aim of this study was to develop and test a new questionnaire concerning knowledge on cervical cancer. An instrument was developed and validated to measure knowledge in 226 Chilean adolescents between April and June 2011. Content validity, construct validity, and reliability analysis of the instrument were performed. The new, validated instrument, called CEC-61 (Conocimientos en Cancer Cérvicouterino-61 items/Knowledge in Cervical Cancer-61 items), contains nine factors and 61 items. The new questionnaire explained 81% of the variance with a reliability of 0.96. The assessment of knowledge with a valid and reliable instrument is the first step in creating interventions for a population and to encourage appropriate preventive behavior. CEC-61 is highly reliable and has a clear factorial structure to evaluate knowledge in nine domains related to cervical cancer disease, cervical cancer risk, papilloma virus infection, the Papanicolaou test, and the papilloma virus vaccine.

Automatic specification of reliability models for fault-tolerant computers

NASA Technical Reports Server (NTRS)

Liceaga, Carlos A.; Siewiorek, Daniel P.

1993-01-01

The calculation of reliability measures using Markov models is required for life-critical processor-memory-switch structures that have standby redundancy or that are subject to transient or intermittent faults or repair. The task of specifying these models is tedious and prone to human error because of the large number of states and transitions required in any reasonable system. Therefore, model specification is a major analysis bottleneck, and model verification is a major validation problem. The general unfamiliarity of computer architects with Markov modeling techniques further increases the necessity of automating the model specification. Automation requires a general system description language (SDL). For practicality, this SDL should also provide a high level of abstraction and be easy to learn and use. The first attempt to define and implement an SDL with those characteristics is presented. A program named Automated Reliability Modeling (ARM) was constructed as a research vehicle. The ARM program uses a graphical interface as its SDL, and it outputs a Markov reliability model specification formulated for direct use by programs that generate and evaluate the model.

Reliability Considerations for the Operation of Large Accelerator User Facilities

DOE PAGES

Willeke, F. J.

2016-01-29

The lecture provides an overview of considerations relevant for achieving highly reliable operation of accelerator based user facilities. The article starts with an overview of statistical reliability formalism which is followed by high reliability design considerations with examples. Finally, the article closes with operational aspects of high reliability such as preventive maintenance and spares inventory.

Optical Amplifier Based Space Solar Power

NASA Technical Reports Server (NTRS)

Fork, Richard L.

2001-01-01

The objective was to design a safe optical power beaming system for use in space. Research was focused on identification of strategies and structures that would enable achievement near diffraction limited optical beam quality, highly efficient electrical to optical conversion, and high average power in combination in a single system. Efforts centered on producing high efficiency, low mass of the overall system, low operating temperature, precision pointing and tracking capability, compatibility with useful satellite orbits, component and system reliability, and long component and system life in space. A system based on increasing the power handled by each individual module to an optimum and the number of modules in the complete structure was planned. We were concerned with identifying the most economical and rapid path to commercially viable safe space solar power.

Reliability-based econometrics of aerospace structural systems: Design criteria and test options. Ph.D. Thesis - Georgia Inst. of Tech.

NASA Technical Reports Server (NTRS)

Thomas, J. M.; Hanagud, S.

1974-01-01

The design criteria and test options for aerospace structural reliability were investigated. A decision methodology was developed for selecting a combination of structural tests and structural design factors. The decision method involves the use of Bayesian statistics and statistical decision theory. Procedures are discussed for obtaining and updating data-based probabilistic strength distributions for aerospace structures when test information is available and for obtaining subjective distributions when data are not available. The techniques used in developing the distributions are explained.

Advanced Packaging Materials and Techniques for High Power TR Module: Standard Flight vs. Advanced Packaging

NASA Technical Reports Server (NTRS)

Hoffman, James Patrick; Del Castillo, Linda; Miller, Jennifer; Jenabi, Masud; Hunter, Donald; Birur, Gajanana

2011-01-01

The higher output power densities required of modern radar architectures, such as the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI) require increasingly dense high power electronics. To enable these higher power densities, while maintaining or even improving hardware reliability, requires advances in integrating advanced thermal packaging technologies into radar transmit/receive (TR) modules. New materials and techniques have been studied and compared to standard technologies.

Optimum structural design based on reliability and proof-load testing

NASA Technical Reports Server (NTRS)

Shinozuka, M.; Yang, J. N.

1969-01-01

Proof-load test eliminates structures with strength less than the proof load and improves the reliability value in analysis. It truncates the distribution function of strength at the proof load, thereby alleviating verification of a fitted distribution function at the lower tail portion where data are usually nonexistent.

Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (< 250 V) 4H-SiC p(sup +)n Junction Diodes--Part II: Dynamic Breakdown Properties. Part 2; Dynamic Breakdown Properties

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Fazi, Christian

1999-01-01

This paper outlines the dynamic reverse-breakdown characteristics of low-voltage (<250 V) small-area <5 x 10(exp -4) sq cm 4H-SiC p(sup +)n diodes subjected to nonadiabatic breakdown-bias pulsewidths ranging from 0.1 to 20 microseconds. 4H-SiC diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities approximately five times larger than the average failure power density of reliable silicon pn rectifiers. This result indicates that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations. However, the impact of elementary screw dislocations on other more useful 4H-SiC power device structures, such as high-voltage (>1 kV) pn junction and Schottky rectifiers, and bipolar gain devices (thyristors, IGBT's, etc.) remains to be investigated.

Psychometric properties of the Adolescent Dissociative Experiences Scale in a sample of Italian adolescents.

PubMed

Schimmenti, Adriano

2016-01-01

The purpose of this study was to examine the psychometric properties of the Italian translation of the Adolescent Dissociative Experiences Scale (A-DES). A sample of 1,806 high-school students between the ages of 13 and 18 years, recruited in 6 Italian cities, completed the A-DES. The A-DES showed high internal consistency, excellent item-to-scale homogeneity, good split-half reliability, and a single-factor structure. The scores of the Italian adolescents were comparable to those found in previous research with the measure. No gender differences were found in mean A-DES scores, but boys and girls showed different patterns of responses on A-DES items. Age differences were also found, with 13- and 18-year-old students scoring higher on the measure than the other participants. A cluster analysis showed that participants could be consistently grouped into 2 clusters of low- and high-dissociative adolescents. This study supports the A-DES as a reliable and valid screening measure for dissociative symptoms in adolescents.

Preliminary Validation of a New Measure of Negative Response Bias: The Temporal Memory Sequence Test.

PubMed

Hegedish, Omer; Kivilis, Naama; Hoofien, Dan

2015-01-01

The Temporal Memory Sequence Test (TMST) is a new measure of negative response bias (NRB) that was developed to enrich the forced-choice paradigm. The TMST does not resemble the common structure of forced-choice tests and is presented as a temporal recall memory test. The validation sample consisted of 81 participants: 21 healthy control participants, 20 coached simulators, and 40 patients with acquired brain injury (ABI). The TMST had high reliability and significantly high positive correlations with the Test of Memory Malingering and Word Memory Test effort scales. Moreover, the TMST effort scales exhibited high negative correlations with the Glasgow Coma Scale, thus validating the previously reported association between probable malingering and mild traumatic brain injury. A suggested cutoff score yielded acceptable classification rates in the ABI group as well as in the simulator and control groups. The TMST appears to be a promising measure of NRB detection, with respectable rates of reliability and construct and criterion validity.

Functional maturation of motor nerve terminals in the avian iris: ultrastructure, transmitter metabolism and synaptic reliability

PubMed Central

Pilar, Guillermo; Tuttle, Jeremy; Vaca, Ken

1981-01-01

1. The transformation of easily fatigued embryonic neuromuscular junctions into highly reliable mature terminals was examined by studying functional and morphological changes during development of the avian iris. The mature ability to follow repetitive electrical nerve stimulation was correlated with the rate of acetylcholine (ACh) synthesis and choline uptake, and with the fine structure of the nerve terminals and the post-synaptic elements. 2. The terminals of the ciliary nerve of the chick initially form functional synaptic contacts with the iris muscle at embryonic St. 34-40. At the onset of this period, no Na+-dependent high affinity choline uptake can be demonstrated, and the low level of ACh synthesis present is sensitive to Na+ removal. At St. 36 [3H]ACh synthesis begins to increase, the increment being Na+-dependent. 3. ACh synthesis in the embryonic iris was insensitive to a conditioning [K+]o depolarization even as late as St. 43. Just before hatching, depolarization elicits some augmentation in synthesis, but by 2 days ex ovo this release-induced response has increased by an order of magnitude. 4. Concurrently with the acquisition of the ability to respond to depolarization with accelerated synthesis, neuromuscular transmission in the iris becomes reliable and secure during stimulation at 20 Hz. Embryonic junctions rapidly block during such stimulation, and the failure is shown to be presynaptic in origin, resulting most probably from failure to sustain adequate levels of transmitter release. 5. Ultrastructural examination of the developing ciliary terminals revealed few synaptic vesicles at early stages, and a dearth of other specializations. The sequence of development from these small structurally undistinguished endings to large en plaque junctions completely filled with vesicles was reconstructed and compared to other neuromuscular junctions. Morphological maturation appears progressive with little evidence of discontinuity signalling functional status, but it is only after the terminals enlarge and become closely packed with vesicles that mature synaptic reliability is found. 6. The temporal correlation between responsiveness of transmitter synthesis to depolarization and reliable neuromuscular transmission suggests that modulation of neurotransmitter metabolism in response to demand signals the achievement of junctional maturity. ImagesABPlate 2Plate 3Plate 4 PMID:6279822

Probabilistic Methods for Structural Reliability and Risk

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

2007-01-01

A formal method is described to quantify structural reliability and risk in the presence of a multitude of uncertainties. The method is based on the materials behavior level where primitive variables with their respective scatters are used to describe that behavior. Computational simulation is then used to propagate those uncertainties to the structural scale where reliability and risk are usually specified. A sample case is described to illustrate the effectiveness, versatility, and maturity of the method. Typical results from this method demonstrate that the method is mature and that it can be used for future strategic projections and planning to assure better, cheaper, faster products for competitive advantages in world markets. The results also indicate that the methods are suitable for predicting remaining life in aging or deteriorating structures.

A general strategy to solve the phase problem in RNA crystallography

PubMed Central

Keel, Amanda Y.; Rambo, Robert P.; Batey, Robert T.; Kieft, Jeffrey S.

2007-01-01

SUMMARY X-ray crystallography of biologically important RNA molecules has been hampered by technical challenges, including finding a heavy-atom derivative to obtain high-quality experimental phase information. Existing techniques have drawbacks, severely limiting the rate at which important new structures are solved. To address this need, we have developed a reliable means to localize heavy atoms specifically to virtually any RNA. By solving the crystal structures of thirteen variants of the G·U wobble pair cation binding motif we have identified an optimal version that when inserted into an RNA helix introduces a high-occupancy cation binding site suitable for phasing. This “directed soaking” strategy can be integrated fully into existing RNA and crystallography methods, potentially increasing the rate at which important structures are solved and facilitating routine solving of structures using Cu-Kα radiation. The success of this method has been proven in that it has already been used to solve several novel crystal structures. PMID:17637337

High-rate, roll-to-roll nanomanufacturing of flexible systems

NASA Astrophysics Data System (ADS)

Cooper, Khershed P.; Wachter, Ralph F.

2012-10-01

Since the National Nanotechnology Initiative was first announced in 2000, nanotechnology has developed an impressive catalog of nano-scale structures with building-blocks such as nanoparticles, nanotubes, nanorods, nanopillars, and quantum dots. Similarly, there are accompanying materials processes such as, atomic layer deposition, pulsed layer deposition, nanoprinting, nanoimprinting, transfer printing, nanolithography and nanopatterning. One of the challenges of nanomanufacturing is scaling up these processes reliably and affordably. Roll-to-roll manufacturing is a means for scaling up, for increasing throughput. It is high-speed production using a continuous, moving platform such as a web or a flexible substrate. The adoption of roll-to-roll to nanomanufacturing is novel. The goal is to build structures and devices with nano-scale features and specific functionality. The substrate could be a polymer, metal foil, silk, cloth or paper. The materials to build the structures and multi-level devices could be organic, inorganic or biological. Processing could be solution-based, e.g., ink-jet printing, or vacuum-based, e.g., chemical vapor deposition. Products could be electronics, optoelectronics, membranes, catalysts, microfluidics, lab-on-film, filters, etc. By this means, processing of large and conformal areas is achievable. High-throughput translates into low cost, which is the attraction of roll-to-roll nanomanufacturing. There are technical challenges requiring fundamental scientific advances in materials and process development and in manufacturing and system-integration where achieving nano-scale feature size, resolution and accuracy at high speeds can be major hurdles. We will give an overview of roll-to-roll nanomanufacturing with emphasis on the need to understand the material, process and system complexities, the need for instrumentation, measurement, and process control and describe the concept of cyber-enabled nanomanufacturing for reliable and predictable production.

confFuse: High-Confidence Fusion Gene Detection across Tumor Entities.

PubMed

Huang, Zhiqin; Jones, David T W; Wu, Yonghe; Lichter, Peter; Zapatka, Marc

2017-01-01

Background: Fusion genes play an important role in the tumorigenesis of many cancers. Next-generation sequencing (NGS) technologies have been successfully applied in fusion gene detection for the last several years, and a number of NGS-based tools have been developed for identifying fusion genes during this period. Most fusion gene detection tools based on RNA-seq data report a large number of candidates (mostly false positives), making it hard to prioritize candidates for experimental validation and further analysis. Selection of reliable fusion genes for downstream analysis becomes very important in cancer research. We therefore developed confFuse, a scoring algorithm to reliably select high-confidence fusion genes which are likely to be biologically relevant. Results: confFuse takes multiple parameters into account in order to assign each fusion candidate a confidence score, of which score ≥8 indicates high-confidence fusion gene predictions. These parameters were manually curated based on our experience and on certain structural motifs of fusion genes. Compared with alternative tools, based on 96 published RNA-seq samples from different tumor entities, our method can significantly reduce the number of fusion candidates (301 high-confidence from 8,083 total predicted fusion genes) and keep high detection accuracy (recovery rate 85.7%). Validation of 18 novel, high-confidence fusions detected in three breast tumor samples resulted in a 100% validation rate. Conclusions: confFuse is a novel downstream filtering method that allows selection of highly reliable fusion gene candidates for further downstream analysis and experimental validations. confFuse is available at https://github.com/Zhiqin-HUANG/confFuse.

High reliability and implications for nursing leaders.

PubMed

Riley, William

2009-03-01

To review high reliability theory and discuss its implications for the nursing leader. A high reliability organization (HRO) is considered that which has measurable near perfect performance for quality and safety. The author has reviewed the literature, discussed research findings that contribute to improving reliability in health care organizations, and makes five recommendations for how nursing leaders can create high reliability organizations. Health care is not a safe industry and unintended patient harm occurs at epidemic levels. Health care can learn from high reliability theory and practice developed in other high-risk industries. Viewed by HRO standards, unintended patient injury in health care is excessively high and quality is distressingly low. HRO theory and practice can be successfully applied in health care using advanced interdisciplinary teamwork training and deliberate process design techniques. Nursing has a primary leadership function for ensuring patient safety and achieving high quality in health care organizations. Learning HRO theory and methods for achieving high reliability is a foremost opportunity for nursing leaders.

Autonomous Assembly of Modular Structures in Space and on Extraterrestrial Locations

NASA Astrophysics Data System (ADS)

Alhorn, Dean C.

2005-02-01

The new U.S. National Vision for Space Exploration requires many new enabling technologies to accomplish the goals of space commercialization and returning humans to the moon and extraterrestrial environments. Traditionally, flight elements are complete sub-systems requiring humans to complete the integration and assembly. These bulky structures also require the use of heavy launch vehicles to send the units to a desired location. This philosophy necessitates a high degree of safety, numerous space walks at a significant cost. Future space mission costs must be reduced and safety increased to reasonably achieve exploration goals. One proposed concept is the autonomous assembly of space structures. This concept is an affordable, reliable solution to in-space and extraterrestrial assembly. Assembly is autonomously performed when two components join after determining that specifications are correct. Local sensors continue monitor joint integrity post assembly, which is critical for safety and structural reliability. Achieving this concept requires a change in space structure design philosophy and the development of innovative technologies to perform autonomous assembly. Assembly of large space structures will require significant numbers of integrity sensors. Thus simple, low-cost sensors are integral to the success of this concept. This paper addresses these issues and proposes a novel concept for assembling space structures autonomously. Core technologies required to achieve in space assembly are presented. These core technologies are critical to the goal of utilizing space in a cost efficient and safe manner. Additionally, these novel technologies can be applied to other systems both on earth and extraterrestrial environments.

Autonomous Assembly of Modular Structures in Space and on Extraterrestrial Locations

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.

2005-01-01

The new U.S. National Vision for Space Exploration requires many new enabling technologies to accomplish the goals of space commercialization and returning humans to the moon and extraterrestrial environments. Traditionally, flight elements are complete subsystems requiring humans to complete the integration and assembly. These bulky structures also require the use of heavy launch vehicles to send the units to a desired location. This philosophy necessitates a high degree of safety, numerous space walks at a significant cost. Future space mission costs must be reduced and safety increased to reasonably achieve exploration goals. One proposed concept is the autonomous assembly of space structures. This concept is an affordable, reliable solution to in-space and extraterrestrial assembly. Assembly is autonomously performed when two components join after determining that specifications are correct. Local sensors continue monitor joint integrity post assembly, which is critical for safety and structural reliability. Achieving this concept requires a change in space structure design philosophy and the development of innovative technologies to perform autonomous assembly. Assembly of large space structures will require significant numbers of integrity sensors. Thus simple, low-cost sensors are integral to the success of this concept. This paper addresses these issues and proposes a novel concept for assembling space structures autonomously. Core technologies required to achieve in space assembly are presented. These core technologies are critical to the goal of utilizing space in a cost efficient and safe manner. Additionally, these novel technologies can be applied to other systems both on earth and extraterrestrial environments.

System reliability of randomly vibrating structures: Computational modeling and laboratory testing

NASA Astrophysics Data System (ADS)

Sundar, V. S.; Ammanagi, S.; Manohar, C. S.

2015-09-01

The problem of determination of system reliability of randomly vibrating structures arises in many application areas of engineering. We discuss in this paper approaches based on Monte Carlo simulations and laboratory testing to tackle problems of time variant system reliability estimation. The strategy we adopt is based on the application of Girsanov's transformation to the governing stochastic differential equations which enables estimation of probability of failure with significantly reduced number of samples than what is needed in a direct simulation study. Notably, we show that the ideas from Girsanov's transformation based Monte Carlo simulations can be extended to conduct laboratory testing to assess system reliability of engineering structures with reduced number of samples and hence with reduced testing times. Illustrative examples include computational studies on a 10-degree of freedom nonlinear system model and laboratory/computational investigations on road load response of an automotive system tested on a four-post test rig.

Probabilistic Methods for Structural Design and Reliability

NASA Technical Reports Server (NTRS)

Chamis, Christos C.; Whitlow, Woodrow, Jr. (Technical Monitor)

2002-01-01

This report describes a formal method to quantify structural damage tolerance and reliability in the presence of a multitude of uncertainties in turbine engine components. The method is based at the material behavior level where primitive variables with their respective scatter ranges are used to describe behavior. Computational simulation is then used to propagate the uncertainties to the structural scale where damage tolerance and reliability are usually specified. Several sample cases are described to illustrate the effectiveness, versatility, and maturity of the method. Typical results from this method demonstrate, that it is mature and that it can be used to probabilistically evaluate turbine engine structural components. It may be inferred from the results that the method is suitable for probabilistically predicting the remaining life in aging or in deteriorating structures, for making strategic projections and plans, and for achieving better, cheaper, faster products that give competitive advantages in world markets.

The application of 3D Zernike moments for the description of "model-free" molecular structure, functional motion, and structural reliability.

PubMed

Grandison, Scott; Roberts, Carl; Morris, Richard J

2009-03-01

Protein structures are not static entities consisting of equally well-determined atomic coordinates. Proteins undergo continuous motion, and as catalytic machines, these movements can be of high relevance for understanding function. In addition to this strong biological motivation for considering shape changes is the necessity to correctly capture different levels of detail and error in protein structures. Some parts of a structural model are often poorly defined, and the atomic displacement parameters provide an excellent means to characterize the confidence in an atom's spatial coordinates. A mathematical framework for studying these shape changes, and handling positional variance is therefore of high importance. We present an approach for capturing various protein structure properties in a concise mathematical framework that allows us to compare features in a highly efficient manner. We demonstrate how three-dimensional Zernike moments can be employed to describe functions, not only on the surface of a protein but throughout the entire molecule. A number of proof-of-principle examples are given which demonstrate how this approach may be used in practice for the representation of movement and uncertainty.

Fair and Just Culture, Team Behavior, and Leadership Engagement: The Tools to Achieve High Reliability

PubMed Central

Frankel, Allan S; Leonard, Michael W; Denham, Charles R

2006-01-01

Background Disparate health care provider attitudes about autonomy, teamwork, and administrative operations have added to the complexity of health care delivery and are a central factor in medicine's unacceptably high rate of errors. Other industries have improved their reliability by applying innovative concepts to interpersonal relationships and administrative hierarchical structures (Chandler 1962). In the last 10 years the science of patient safety has become more sophisticated, with practical concepts identified and tested to improve the safety and reliability of care. Objective Three initiatives stand out as worthy regarding interpersonal relationships and the application of provider concerns to shape operational change: The development and implementation of Fair and Just Culture principles, the broad use of Teamwork Training and Communication, and tools like WalkRounds that promote the alignment of leadership and frontline provider perspectives through effective use of adverse event data and provider comments. Methods Fair and Just Culture, Teamwork Training, and WalkRounds are described, and implementation examples provided. The argument is made that they must be systematically and consistently implemented in an integrated fashion. Conclusions There are excellent examples of institutions applying Just Culture principles, Teamwork Training, and Leadership WalkRounds—but to date, they have not been comprehensively instituted in health care organizations in a cohesive and interdependent manner. To achieve reliability, organizations need to begin thinking about the relationship between these efforts and linking them conceptually. PMID:16898986

Uterine Fibroid Symptom - Quality of Life questionnaire translation and validation into Brazilian Portuguese.

PubMed

Silva, Rita Oliveira da; Gomes, Mariano Tamura Vieira; Castro, Rodrigo de Aquino; Bonduki, Cláudio Emílio; Girão, Manoel João Batista Castello

2016-10-01

Purpose  To translate into Portuguese, culturally adapt and validate the Uterine Fibroid Symptom - Quality of Life (UFS-QoL) questionnaire for Brazilian women with uterine leiomyoma. Methods  Initially, the UFS-QoL questionnaire was translated into Brazilian Portuguese in accordance with international standards, with subsequent cultural, structural, conceptual and semantic adaptations, so that patients were able to properly answer the questionnaire. Fifty patients with uterine leiomyoma and 19 patients without the disease, confirmed by abdominal pelvic examination and/or transvaginal ultrasound, were selected at the outpatient clinics of the Department of Gynecology of the Universidade Federal de São Paulo (Unifesp). The UFS-QoL questionnaire was administered to all women twice on the same day, with two different interviewers, with an interval of 15 minutes between interviews. After 15 days, the questionnaire was re-administered by the first interviewer. Reliability (internal consistency and test-retest), construct and discriminative validity were tested to ratify the questionnaire. Results  The reliability of the instrument was assessed by Cronbach's α coefficient with an overall result of 0.97, indicating high reliability. The survey results showed a high correlation ( p  = 0.94; p  ≤ 0.001). Conclusion  The UFS-QoL questionnaire was successfully adapted to the Brazilian Portuguese language and Brazilian culture, showing reliability and validity. Thieme Publicações Ltda Rio de Janeiro, Brazil.

Measuring the contribution of art therapy in multidisciplinary treatment of personality disorders: The construction of the Self‐expression and Emotion Regulation in Art Therapy Scale (SERATS)

PubMed Central

van Hooren, Susan; van der Veld, William M.; Hutschemaekers, Giel

2017-01-01

Abstract Despite the use of art therapy in clinical practice, its appreciation and reported beneficial results, no instruments are available to measure specific effects of art therapy among patients with personality disorders cluster B/C in multidisciplinary treatment. In the present study, we described the development and psychometric evaluation of the Self‐expression and Emotion Regulation in Art Therapy Scale (SERATS). Structural validity (exploratory and confirmatory factor analysis), reliability, construct validity and sensitivity to change were examined using two independent databases (n = 335; n = 34) of patients diagnosed with personality disorders cluster B/C. This resulted in a nine‐item effect scale with a single factor with a high internal reliability and high test–retest reliability; it demonstrated discriminant validity and sensitivity to change. In conclusion, the SERATS is brief and content‐valid and offers objective and reliable information on self‐expression and emotion regulation in art therapy among patients with personality disorders cluster B/C. Although more research on construct validity is needed, the SERATS is a promising tool to be applied as an effect scale and as a monitoring tool during art therapy treatment. © 2017 The Authors Personality and Mental Health Published by John Wiley & Sons Ltd PMID:28730717

Structural studies of RNA-protein complexes: A hybrid approach involving hydrodynamics, scattering, and computational methods.

PubMed

Patel, Trushar R; Chojnowski, Grzegorz; Astha; Koul, Amit; McKenna, Sean A; Bujnicki, Janusz M

2017-04-15

The diverse functional cellular roles played by ribonucleic acids (RNA) have emphasized the need to develop rapid and accurate methodologies to elucidate the relationship between the structure and function of RNA. Structural biology tools such as X-ray crystallography and Nuclear Magnetic Resonance are highly useful methods to obtain atomic-level resolution models of macromolecules. However, both methods have sample, time, and technical limitations that prevent their application to a number of macromolecules of interest. An emerging alternative to high-resolution structural techniques is to employ a hybrid approach that combines low-resolution shape information about macromolecules and their complexes from experimental hydrodynamic (e.g. analytical ultracentrifugation) and solution scattering measurements (e.g., solution X-ray or neutron scattering), with computational modeling to obtain atomic-level models. While promising, scattering methods rely on aggregation-free, monodispersed preparations and therefore the careful development of a quality control pipeline is fundamental to an unbiased and reliable structural determination. This review article describes hydrodynamic techniques that are highly valuable for homogeneity studies, scattering techniques useful to study the low-resolution shape, and strategies for computational modeling to obtain high-resolution 3D structural models of RNAs, proteins, and RNA-protein complexes. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

High-throughput screening for thermoelectric sulphides by using crystal structure features as descriptors

NASA Astrophysics Data System (ADS)

Zhang, Ruizhi; Du, Baoli; Chen, Kan; Reece, Mike; Materials Research Insititute Team

With the increasing computational power and reliable databases, high-throughput screening is playing a more and more important role in the search of new thermoelectric materials. Rather than the well established density functional theory (DFT) calculation based methods, we propose an alternative approach to screen for new TE materials: using crystal structural features as 'descriptors'. We show that a non-distorted transition metal sulphide polyhedral network can be a good descriptor for high power factor according to crystal filed theory. By using Cu/S containing compounds as an example, 1600+ Cu/S containing entries in the Inorganic Crystal Structure Database (ICSD) were screened, and of those 84 phases are identified as promising thermoelectric materials. The screening results are validated by both electronic structure calculations and experimental results from the literature. We also fabricated some new compounds to test our screening results. Another advantage of using crystal structure features as descriptors is that we can easily establish structural relationships between the identified phases. Based on this, two material design approaches are discussed: 1) High-pressure synthesis of metastable phase; 2) In-situ 2-phase composites with coherent interface. This work was supported by a Marie Curie International Incoming Fellowship of the European Community Human Potential Program.

Protein Models Docking Benchmark 2

PubMed Central

Anishchenko, Ivan; Kundrotas, Petras J.; Tuzikov, Alexander V.; Vakser, Ilya A.

2015-01-01

Structural characterization of protein-protein interactions is essential for our ability to understand life processes. However, only a fraction of known proteins have experimentally determined structures. Such structures provide templates for modeling of a large part of the proteome, where individual proteins can be docked by template-free or template-based techniques. Still, the sensitivity of the docking methods to the inherent inaccuracies of protein models, as opposed to the experimentally determined high-resolution structures, remains largely untested, primarily due to the absence of appropriate benchmark set(s). Structures in such a set should have pre-defined inaccuracy levels and, at the same time, resemble actual protein models in terms of structural motifs/packing. The set should also be large enough to ensure statistical reliability of the benchmarking results. We present a major update of the previously developed benchmark set of protein models. For each interactor, six models were generated with the model-to-native Cα RMSD in the 1 to 6 Å range. The models in the set were generated by a new approach, which corresponds to the actual modeling of new protein structures in the “real case scenario,” as opposed to the previous set, where a significant number of structures were model-like only. In addition, the larger number of complexes (165 vs. 63 in the previous set) increases the statistical reliability of the benchmarking. We estimated the highest accuracy of the predicted complexes (according to CAPRI criteria), which can be attained using the benchmark structures. The set is available at http://dockground.bioinformatics.ku.edu. PMID:25712716

A Concept for a Mobile Remote Manipulator System

NASA Technical Reports Server (NTRS)

Mikulus, M. M., Jr.; Bush, H. G.; Wallsom, R. E.; Jensen, J. K.

1985-01-01

A conceptual design for a Mobile Remote Manipulator System (MRMS) is presented. This concept does not require continuous rails for mobility (only guide pins at truss hardpoints) and is very compact, being only one bay square. The MRMS proposed is highly maneuverable and is able to move in any direction along the orthogonal guide pin array under complete control at all times. The proposed concept would greatly enhance the safety and operational capabilities of astronauts performing EVA functions such as structural assembly, payload transport and attachment, space station maintenance, repair or modification, and future spacecraft construction or servicing. The MRMS drive system conceptual design presented is a reasonably simple mechanical device which can be designed to exhibit high reliability. Developmentally, all components of the proposed MRMS either exist or are considered to be completely state of the art designs requiring minimal development, features which should enhance reliability and minimize costs.