Development of Benchmark Examples for Quasi-Static Delamination Propagation and Fatigue Growth Predictions

NASA Technical Reports Server (NTRS)

Krueger, Ronald

2012-01-01

The development of benchmark examples for quasi-static delamination propagation and cyclic delamination onset and growth prediction is presented and demonstrated for Abaqus/Standard. The example is based on a finite element model of a Double-Cantilever Beam specimen. The example is independent of the analysis software used and allows the assessment of the automated delamination propagation, onset and growth prediction capabilities in commercial finite element codes based on the virtual crack closure technique (VCCT). First, a quasi-static benchmark example was created for the specimen. Second, based on the static results, benchmark examples for cyclic delamination growth were created. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. Fourth, starting from an initially straight front, the delamination was allowed to grow under cyclic loading. The number of cycles to delamination onset and the number of cycles during delamination growth for each growth increment were obtained from the automated analysis and compared to the benchmark examples. Again, good agreement between the results obtained from the growth analysis and the benchmark results could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Selecting the appropriate input parameters, however, was not straightforward and often required an iterative procedure. Overall the results are encouraging, but further assessment for mixed-mode delamination is required.

Development of Benchmark Examples for Static Delamination Propagation and Fatigue Growth Predictions

NASA Technical Reports Server (NTRS)

Kruger, Ronald

2011-01-01

The development of benchmark examples for static delamination propagation and cyclic delamination onset and growth prediction is presented and demonstrated for a commercial code. The example is based on a finite element model of an End-Notched Flexure (ENF) specimen. The example is independent of the analysis software used and allows the assessment of the automated delamination propagation, onset and growth prediction capabilities in commercial finite element codes based on the virtual crack closure technique (VCCT). First, static benchmark examples were created for the specimen. Second, based on the static results, benchmark examples for cyclic delamination growth were created. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. Fourth, starting from an initially straight front, the delamination was allowed to grow under cyclic loading. The number of cycles to delamination onset and the number of cycles during stable delamination growth for each growth increment were obtained from the automated analysis and compared to the benchmark examples. Again, good agreement between the results obtained from the growth analysis and the benchmark results could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with the input parameters of the particular implementation. Selecting the appropriate input parameters, however, was not straightforward and often required an iterative procedure. Overall, the results are encouraging but further assessment for mixed-mode delamination is required.

Development and Application of Benchmark Examples for Mode II Static Delamination Propagation and Fatigue Growth Predictions

NASA Technical Reports Server (NTRS)

Krueger, Ronald

2011-01-01

The development of benchmark examples for static delamination propagation and cyclic delamination onset and growth prediction is presented and demonstrated for a commercial code. The example is based on a finite element model of an End-Notched Flexure (ENF) specimen. The example is independent of the analysis software used and allows the assessment of the automated delamination propagation, onset and growth prediction capabilities in commercial finite element codes based on the virtual crack closure technique (VCCT). First, static benchmark examples were created for the specimen. Second, based on the static results, benchmark examples for cyclic delamination growth were created. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. Fourth, starting from an initially straight front, the delamination was allowed to grow under cyclic loading. The number of cycles to delamination onset and the number of cycles during delamination growth for each growth increment were obtained from the automated analysis and compared to the benchmark examples. Again, good agreement between the results obtained from the growth analysis and the benchmark results could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Selecting the appropriate input parameters, however, was not straightforward and often required an iterative procedure. Overall the results are encouraging, but further assessment for mixed-mode delamination is required.

Static air-gap eccentricity fault diagnosis using rotor slot harmonics in line neutral voltage of three-phase squirrel cage induction motor

NASA Astrophysics Data System (ADS)

Oumaamar, Mohamed El Kamel; Maouche, Yassine; Boucherma, Mohamed; Khezzar, Abdelmalek

2017-02-01

The mixed eccentricity fault detection in a squirrel cage induction motor has been thoroughly investigated. However, a few papers have been related to pure static eccentricity fault and the authors focused on the RSH harmonics presented in stator current. The main objective of this paper is to present an alternative method based on the analysis of line neutral voltage taking place between the supply and the stator neutrals in order to detect air-gap static eccentricity, and to highlight the classification of all RSH harmonics in line neutral voltage. The model of squirrel cage induction machine relies on the rotor geometry and winding layout. Such developed model is used to analyze the impact of the pure static air-gap eccentricity by predicting the related frequencies in the line neutral voltage spectrum. The results show that the line neutral voltage spectrum are more sensitive to the air-gap static eccentricity fault compared to stator current one. The theoretical analysis and simulated results are confirmed by experiments.

Flight calibration of compensated and uncompensated pitot-static airspeed probes and application of the probes to supersonic cruise vehicles

NASA Technical Reports Server (NTRS)

Webb, L. D.; Washington, H. P.

1972-01-01

Static pressure position error calibrations for a compensated and an uncompensated XB-70 nose boom pitot static probe were obtained in flight. The methods (Pacer, acceleration-deceleration, and total temperature) used to obtain the position errors over a Mach number range from 0.5 to 3.0 and an altitude range from 25,000 feet to 70,000 feet are discussed. The error calibrations are compared with the position error determined from wind tunnel tests, theoretical analysis, and a standard NACA pitot static probe. Factors which influence position errors, such as angle of attack, Reynolds number, probe tip geometry, static orifice location, and probe shape, are discussed. Also included are examples showing how the uncertainties caused by position errors can affect the inlet controls and vertical altitude separation of a supersonic transport.

An Aeroelastic Analysis of a Thin Flexible Membrane

NASA Technical Reports Server (NTRS)

Scott, Robert C.; Bartels, Robert E.; Kandil, Osama A.

2007-01-01

Studies have shown that significant vehicle mass and cost savings are possible with the use of ballutes for aero-capture. Through NASA's In-Space Propulsion program, a preliminary examination of ballute sensitivity to geometry and Reynolds number was conducted, and a single-pass coupling between an aero code and a finite element solver was used to assess the static aeroelastic effects. There remain, however, a variety of open questions regarding the dynamic aeroelastic stability of membrane structures for aero-capture, with the primary challenge being the prediction of the membrane flutter onset. The purpose of this paper is to describe and begin addressing these issues. The paper includes a review of the literature associated with the structural analysis of membranes and membrane utter. Flow/structure analysis coupling and hypersonic flow solver options are also discussed. An approach is proposed for tackling this problem that starts with a relatively simple geometry and develops and evaluates analysis methods and procedures. This preliminary study considers a computationally manageable 2-dimensional problem. The membrane structural models used in the paper include a nonlinear finite-difference model for static and dynamic analysis and a NASTRAN finite element membrane model for nonlinear static and linear normal modes analysis. Both structural models are coupled with a structured compressible flow solver for static aeroelastic analysis. For dynamic aeroelastic analyses, the NASTRAN normal modes are used in the structured compressible flow solver and 3rd order piston theories were used with the finite difference membrane model to simulate utter onset. Results from the various static and dynamic aeroelastic analyses are compared.

VFMA: Topographic Analysis of Sensitivity Data From Full-Field Static Perimetry

PubMed Central

Weleber, Richard G.; Smith, Travis B.; Peters, Dawn; Chegarnov, Elvira N.; Gillespie, Scott P.; Francis, Peter J.; Gardiner, Stuart K.; Paetzold, Jens; Dietzsch, Janko; Schiefer, Ulrich; Johnson, Chris A.

2015-01-01

Purpose: To analyze static visual field sensitivity with topographic models of the hill of vision (HOV), and to characterize several visual function indices derived from the HOV volume. Methods: A software application, Visual Field Modeling and Analysis (VFMA), was developed for static perimetry data visualization and analysis. Three-dimensional HOV models were generated for 16 healthy subjects and 82 retinitis pigmentosa patients. Volumetric visual function indices, which are measures of quantity and comparable regardless of perimeter test pattern, were investigated. Cross-validation, reliability, and cross-sectional analyses were performed to assess this methodology and compare the volumetric indices to conventional mean sensitivity and mean deviation. Floor effects were evaluated by computer simulation. Results: Cross-validation yielded an overall R2 of 0.68 and index of agreement of 0.89, which were consistent among subject groups, indicating good accuracy. Volumetric and conventional indices were comparable in terms of test–retest variability and discriminability among subject groups. Simulated floor effects did not negatively impact the repeatability of any index, but large floor changes altered the discriminability for regional volumetric indices. Conclusions: VFMA is an effective tool for clinical and research analyses of static perimetry data. Topographic models of the HOV aid the visualization of field defects, and topographically derived indices quantify the magnitude and extent of visual field sensitivity. Translational Relevance: VFMA assists with the interpretation of visual field data from any perimetric device and any test location pattern. Topographic models and volumetric indices are suitable for diagnosis, monitoring of field loss, patient counseling, and endpoints in therapeutic trials. PMID:25938002

Analysis of high-rise constructions with the using of three-dimensional models of rods in the finite element program PRINS

NASA Astrophysics Data System (ADS)

Agapov, Vladimir

2018-03-01

The necessity of new approaches to the modeling of rods in the analysis of high-rise constructions is justified. The possibility of the application of the three-dimensional superelements of rods with rectangular cross section for the static and dynamic calculation of the bar and combined structures is considered. The results of the eighteen-story spatial frame free vibrations analysis using both one-dimensional and three-dimensional models of rods are presented. A comparative analysis of the obtained results is carried out and the conclusions on the possibility of three-dimensional superelements application in static and dynamic analysis of high-rise constructions are given on its basis.

A refined analysis of composite laminates. [theory of statics and dynamics

NASA Technical Reports Server (NTRS)

Srinivas, S.

1973-01-01

The purpose of this paper is to develop a sufficiently accurate analysis, which is much simpler than exact three-dimensional analysis, for statics and dynamics of composite laminates. The governing differential equations and boundary conditions are derived by following a variational approach. The displacements are assumed piecewise linear across the thickness and the effects of transverse shear deformations and rotary inertia are included. A procedure for obtaining the general solution of the above governing differential equations in the form of hyperbolic-trigonometric series is given. The accuracy of the present theory is assessed by obtaining results for free vibrations and flexure of simply supported rectangular laminates and comparing them with results from exact three-dimensional analysis.

Numerical analyses of a rocket engine turbine and comparison with air test data

NASA Technical Reports Server (NTRS)

Tran, Ken; Chan, Daniel C.; Hudson, Susan T.; Gaddis, Stephen W.

1992-01-01

The study presents cold air test data on the Space Shuttle Main Engine High Pressure Fuel Turbopump turbine recently collected at the NASA Marshall Space Flight Center. Overall performance data, static pressures on the first- and second-stage nozzles, and static pressures along with the gas path at the hub and tip are gathered and compared with various (1D, quasi-3D, and 3D viscous) analysis procedures. The results of each level of analysis are compared to test data to demonstrate the range of applicability for each step in the design process of a turbine. One-dimensional performance prediction, quasi-3D loading prediction, 3D wall pressure distribution prediction, and 3D viscous wall pressure distribution prediction are illustrated.

The influence of computational assumptions on analysing abdominal aortic aneurysm haemodynamics.

PubMed

Ene, Florentina; Delassus, Patrick; Morris, Liam

2014-08-01

The variation in computational assumptions for analysing abdominal aortic aneurysm haemodynamics can influence the desired output results and computational cost. Such assumptions for abdominal aortic aneurysm modelling include static/transient pressures, steady/transient flows and rigid/compliant walls. Six computational methods and these various assumptions were simulated and compared within a realistic abdominal aortic aneurysm model with and without intraluminal thrombus. A full transient fluid-structure interaction was required to analyse the flow patterns within the compliant abdominal aortic aneurysms models. Rigid wall computational fluid dynamics overestimates the velocity magnitude by as much as 40%-65% and the wall shear stress by 30%-50%. These differences were attributed to the deforming walls which reduced the outlet volumetric flow rate for the transient fluid-structure interaction during the majority of the systolic phase. Static finite element analysis accurately approximates the deformations and von Mises stresses when compared with transient fluid-structure interaction. Simplifying the modelling complexity reduces the computational cost significantly. In conclusion, the deformation and von Mises stress can be approximately found by static finite element analysis, while for compliant models a full transient fluid-structure interaction analysis is required for acquiring the fluid flow phenomenon. © IMechE 2014.

Free-stream static pressure measurements in the Longshot hypersonic wind tunnel and sensitivity analysis

NASA Astrophysics Data System (ADS)

Grossir, Guillaume; Van Hove, Bart; Paris, Sébastien; Rambaud, Patrick; Chazot, Olivier

2016-05-01

The performance of fast-response slender static pressure probes is evaluated in the short-duration, cold-gas, VKI Longshot hypersonic wind tunnel. Free-stream Mach numbers range between 9.5 and 12, and unit Reynolds numbers are within 3-10 × 106/m. Absolute pressure sensors are fitted within the probes, and an inexpensive calibration method, suited to low static pressure environments (200-1000 Pa), is described. Transfer functions relating the probe measurements p w to the free-stream static pressure p ∞ are established for the Longshot flow conditions based on numerical simulations. The pressure ratios p w / p ∞ are found to be close to unity for both laminar and turbulent boundary layers. Weak viscous effects characterized by small viscous interaction parameters {bar{χ }}<1.5 are confirmed experimentally for probe aspect ratios of L/ D > 16.5 by installing multiple pressure sensors in a single probe. The effect of pressure orifice geometry is also evaluated experimentally and found to be negligible for either straight or chamfered holes, 0.6-1 mm in diameter. No sensitivity to probe angle of attack could be evidenced for α < 0.33°. Pressure measurements are compared to theoretical predictions assuming an isentropic nozzle flow expansion. Significant deviations from this ideal case and the Mach 14 contoured nozzle design are uncovered. Validation of the static pressure measurements is obtained by comparing shock wave locations on Schlieren photographs to numerical predictions using free-stream properties derived from the static pressure probes. While these results apply to the Longshot wind tunnel, the present methodology and sensitivity analysis can guide similar investigations for other hypersonic test facilities.

Static Analysis Using Abstract Interpretation

NASA Technical Reports Server (NTRS)

Arthaud, Maxime

2017-01-01

Short presentation about static analysis and most particularly abstract interpretation. It starts with a brief explanation on why static analysis is used at NASA. Then, it describes the IKOS (Inference Kernel for Open Static Analyzers) tool chain. Results on NASA projects are shown. Several well known algorithms from the static analysis literature are then explained (such as pointer analyses, memory analyses, weak relational abstract domains, function summarization, etc.). It ends with interesting problems we encountered (such as C++ analysis with exception handling, or the detection of integer overflow).

Static and Dynamical Structural Investigations of Metal-Oxide Nanocrystals by Powder X-ray Diffraction: Colloidal Tungsten Oxide as a Case Study

DOE PAGES

Caliandro, Rocco; Sibillano, Teresa; Belviso, B. Danilo; ...

2016-02-02

In this study, we have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO 3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO 3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtlemore » stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO 3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO 3-x NC lattice, rather than a variation in stoichiometry. Finally, the time behavior of such structural change is identified on the basis of multivariate analysis.« less

Theoretical analysis for the design of the French watt balance experiment force comparator

NASA Astrophysics Data System (ADS)

Pinot, Patrick; Genevès, Gerard; Haddad, Darine; David, Jean; Juncar, Patrick; Lecollinet, Michel; Macé, Stéphane; Villar, François

2007-09-01

This paper presents a preliminary analysis for designing a force comparator to be used in the French watt balance experiment. The first stage of this experiment consists in a static equilibrium, by means of a mechanical beam balance, between a gravitational force (a weight of an artefact having a known mass submitted to the acceleration due to the gravity) and a vertical electromagnetic force acting on a coil driven by a current subject to the magnetic induction field provided by a permanent magnet. The principle of the force comparison in the French experiment is explained. The general design configuration of the force balance using flexure strips as pivots is discussed and theoretical calculation results based on realistic assumptions of the static and dynamic behaviors of the balance are presented.

Theoretical analysis for the design of the French watt balance experiment force comparator.

PubMed

Pinot, Patrick; Genevès, Gerard; Haddad, Darine; David, Jean; Juncar, Patrick; Lecollinet, Michel; Macé, Stéphane; Villar, François

2007-09-01

This paper presents a preliminary analysis for designing a force comparator to be used in the French watt balance experiment. The first stage of this experiment consists in a static equilibrium, by means of a mechanical beam balance, between a gravitational force (a weight of an artefact having a known mass submitted to the acceleration due to the gravity) and a vertical electromagnetic force acting on a coil driven by a current subject to the magnetic induction field provided by a permanent magnet. The principle of the force comparison in the French experiment is explained. The general design configuration of the force balance using flexure strips as pivots is discussed and theoretical calculation results based on realistic assumptions of the static and dynamic behaviors of the balance are presented.

Comparison of Inter-Observer Variability and Diagnostic Performance of the Fifth Edition of BI-RADS for Breast Ultrasound of Static versus Video Images.

PubMed

Youk, Ji Hyun; Jung, Inkyung; Yoon, Jung Hyun; Kim, Sung Hun; Kim, You Me; Lee, Eun Hye; Jeong, Sun Hye; Kim, Min Jung

2016-09-01

Our aim was to compare the inter-observer variability and diagnostic performance of the Breast Imaging Reporting and Data System (BI-RADS) lexicon for breast ultrasound of static and video images. Ninety-nine breast masses visible on ultrasound examination from 95 women 19-81 y of age at five institutions were enrolled in this study. They were scheduled to undergo biopsy or surgery or had been stable for at least 2 y of ultrasound follow-up after benign biopsy results or typically benign findings. For each mass, representative long- and short-axis static ultrasound images were acquired; real-time long- and short-axis B-mode video images through the mass area were separately saved as cine clips. Each image was reviewed independently by five radiologists who were asked to classify ultrasound features according to the fifth edition of the BI-RADS lexicon. Inter-observer variability was assessed using kappa (κ) statistics. Diagnostic performance on static and video images was compared using the area under the receiver operating characteristic curve. No significant difference was found in κ values between static and video images for all descriptors, although κ values of video images were higher than those of static images for shape, orientation, margin and calcifications. After receiver operating characteristic curve analysis, the video images (0.83, range: 0.77-0.87) had higher areas under the curve than the static images (0.80, range: 0.75-0.83; p = 0.08). Inter-observer variability and diagnostic performance of video images was similar to that of static images on breast ultrasonography according to the new edition of BI-RADS. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

IKOS: A Framework for Static Analysis based on Abstract Interpretation (Tool Paper)

NASA Technical Reports Server (NTRS)

Brat, Guillaume P.; Laserna, Jorge A.; Shi, Nija; Venet, Arnaud Jean

2014-01-01

The RTCA standard (DO-178C) for developing avionic software and getting certification credits includes an extension (DO-333) that describes how developers can use static analysis in certification. In this paper, we give an overview of the IKOS static analysis framework that helps developing static analyses that are both precise and scalable. IKOS harnesses the power of Abstract Interpretation and makes it accessible to a larger class of static analysis developers by separating concerns such as code parsing, model development, abstract domain management, results management, and analysis strategy. The benefits of the approach is demonstrated by a buffer overflow analysis applied to flight control systems.

Development and Application of Benchmark Examples for Mixed-Mode I/II Quasi-Static Delamination Propagation Predictions

NASA Technical Reports Server (NTRS)

Krueger, Ronald

2012-01-01

The development of benchmark examples for quasi-static delamination propagation prediction is presented. The example is based on a finite element model of the Mixed-Mode Bending (MMB) specimen for 50% mode II. The benchmarking is demonstrated for Abaqus/Standard, however, the example is independent of the analysis software used and allows the assessment of the automated delamination propagation prediction capability in commercial finite element codes based on the virtual crack closure technique (VCCT). First, a quasi-static benchmark example was created for the specimen. Second, starting from an initially straight front, the delamination was allowed to propagate under quasi-static loading. Third, the load-displacement as well as delamination length versus applied load/displacement relationships from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Overall, the results are encouraging, but further assessment for mixed-mode delamination fatigue onset and growth is required.

Correcting (18)F-fluoride PET static scan measurements of skeletal plasma clearance for tracer efflux from bone.

PubMed

Siddique, Musib; Frost, Michelle L; Moore, Amelia E B; Fogelman, Ignac; Blake, Glen M

2014-03-01

The aim of the study was to examine whether (18)F-fluoride PET ((18)F-PET) static scan measurements of bone plasma clearance (Ki) can be corrected for tracer efflux from bone from the time of injection. The efflux of tracer from bone mineral to plasma was described by a first-order rate constant kloss. A modified Patlak analysis was applied to 60-min dynamic (18)F-PET scans of the spine and hip acquired during trials on the bone anabolic agent teriparatide to find the best-fit values of kloss at the lumbar spine, total hip and femoral shaft. The resulting values of kloss were used to extrapolate the modified Patlak plots to 120 min after injection and derive a sequence of static scan estimates of Ki at 4-min intervals that were compared with the Patlak Ki values from the 60-min dynamic scans. A comparison was made with the results of the standard static scan analysis, which assumes kloss=0. The best-fit values of kloss for the spine and hip regions of interest averaged 0.006/min and did not change when patients were treated with teriparatide. Static scan values of Ki calculated using the modified analysis with kloss=0.006/min were independent of time between 10 and 120 min after injection and were in close agreement with findings from the dynamic scans. In contrast, by 2 h after injection the static scan Ki values calculated using the standard analysis underestimated the dynamic scan results by 20%. Using a modified analysis that corrects for F efflux from bone, estimates of Ki from static PET scans can be corrected for time up to 2 h after injection. This simplified approach may obviate the need to perform dynamic scans and hence shorten the scanning procedure for the patient and reduce the cost of studies. It also enables reliable estimates of Ki to be obtained from multiple skeletal sites with a single injection of tracer.

Dynamic analysis of solid propellant grains subjected to ignition pressurization loading

NASA Astrophysics Data System (ADS)

Chyuan, Shiang-Woei

2003-11-01

Traditionally, the transient analysis of solid propellant grains subjected to ignition pressurization loading was not considered, and quasi-elastic-static analysis was widely adopted for structural integrity because the analytical task gets simplified. But it does not mean that the dynamic effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the dynamic response for solid rocket motor, a transient finite element model, accompanied by concepts of time-temperature shift principle, reduced integration and thermorheologically simple material assumption, was used. For studying the dynamic response, diverse ignition pressurization loading cases were used and investigated in the present paper. Results show that the dynamic effect is important for structural integrity of solid propellant grains under ignition pressurization loading. Comparing the effective stress of transient analysis and of quasi-elastic-static analysis, one can see that there is an obvious difference between them because of the dynamic effect. From the work of quasi-elastic-static and transient analyses, the dynamic analysis highlighted several areas of interest and a more accurate and reasonable result could be obtained for the engineer.

Comparative Tests of Pitot-static Tubes

NASA Technical Reports Server (NTRS)

Merriam, Kenneth G; Spaulding, Ellis R

1935-01-01

Comparative tests were made on seven conventional Pitot-static tubes to determine their static, dynamic, and resultant errors. The effect of varying the dynamic opening, static opening, wall thickness, and inner-tube diameter was investigated. Pressure-distribution measurements showing stem and tip effects were also made. A tentative design for a standard Pitot-static tube for use in measuring air velocity is submitted.

The scope of the LeChatelier Principle

NASA Astrophysics Data System (ADS)

George M., Lady; Quirk, James P.

2007-07-01

LeChatelier [Comptes Rendus 99 (1884) 786; Ann. Mines 13 (2) (1888) 157] showed that a physical system's “adjustment” to a disturbance to its equilibrium tended to be smaller as constraints were added to the adjustment process. Samuelson [Foundations of Economic Analysis, Harvard University Press, Cambridge, 1947] applied this result to economics in the context of the comparative statics of the actions of individual agents characterized as the solutions to optimization problems; and later (1960), extended the application of the Principle to a stable, multi-market equilibrium and the case of all commodities gross substitutes [e.g., L. Metzler, Stability of multiple markets: the hicks conditions. Econometrica 13 (1945) 277-292]. Refinements and alternative routes of derivation have appeared in the literature since then, e.g., Silberberg [The LeChatelier Principle as a corollary to a generalized envelope theorem, J. Econ. Theory 3 (1971) 146-155; A revision of comparative statics methodology in economics, or, how to do comparative statics on the back of an envelope, J. Econ. Theory 7 (1974) 159-172], Milgrom and Roberts [The LeChatelier Principle, Am. Econ. Rev. 86 (1996) 173-179], W. Suen, E. Silberberg, P. Tseng [The LeChatelier Principle: the long and the short of it, Econ. Theory 16 (2000) 471-476], and Chavas [A global analysis of constrained behavior: the LeChatelier Principle ‘in the large’, South. Econ. J. 72 (3) (2006) 627-644]. In this paper, we expand the scope of the Principle in various ways keyed to Samuelson's proposed means of testing comparative statics results (optimization, stability, and qualitative analysis). In the optimization framework, we show that the converse LeChatelier Principle also can be found in constrained optimization problems and for not initially “conjugate” sensitivities. We then show how the Principle and its converse can be found through the qualitative analysis of any linear system. In these terms, the Principle and its converse also may be found in the same system at the same time with respect to the imposition of the same constraint. Based upon this, we expand the cases for which the Principle can be found based upon the stability hypothesis.

Analysis of laboratory compaction methods of roller compacted concrete

NASA Astrophysics Data System (ADS)

Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

2017-09-01

Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

Analysis and testing of high entrainment single nozzle jet pumps with variable mixing tubes

NASA Technical Reports Server (NTRS)

Hickman, K. E.; Hill, P. G.; Gilbert, G. B.

1972-01-01

An analytical model was developed to predict the performance characteristics of axisymmetric single-nozzle jet pumps with variable area mixing tubes. The primary flow may be subsonic or supersonic. The computer program uses integral techniques to calculate the velocity profiles and the wall static pressures that result from the mixing of the supersonic primary jet and the subsonic secondary flow. An experimental program was conducted to measure mixing tube wall static pressure variations, velocity profiles, and temperature profiles in a variable area mixing tube with a supersonic primary jet. Static pressure variations were measured at four different secondary flow rates. These test results were used to evaluate the analytical model. The analytical results compared well to the experimental data. Therefore, the analysis is believed to be ready for use to relate jet pump performance characteristics to mixing tube design.

Impaired social brain network for processing dynamic facial expressions in autism spectrum disorders.

PubMed

Sato, Wataru; Toichi, Motomi; Uono, Shota; Kochiyama, Takanori

2012-08-13

Impairment of social interaction via facial expressions represents a core clinical feature of autism spectrum disorders (ASD). However, the neural correlates of this dysfunction remain unidentified. Because this dysfunction is manifested in real-life situations, we hypothesized that the observation of dynamic, compared with static, facial expressions would reveal abnormal brain functioning in individuals with ASD.We presented dynamic and static facial expressions of fear and happiness to individuals with high-functioning ASD and to age- and sex-matched typically developing controls and recorded their brain activities using functional magnetic resonance imaging (fMRI). Regional analysis revealed reduced activation of several brain regions in the ASD group compared with controls in response to dynamic versus static facial expressions, including the middle temporal gyrus (MTG), fusiform gyrus, amygdala, medial prefrontal cortex, and inferior frontal gyrus (IFG). Dynamic causal modeling analyses revealed that bi-directional effective connectivity involving the primary visual cortex-MTG-IFG circuit was enhanced in response to dynamic as compared with static facial expressions in the control group. Group comparisons revealed that all these modulatory effects were weaker in the ASD group than in the control group. These results suggest that weak activity and connectivity of the social brain network underlie the impairment in social interaction involving dynamic facial expressions in individuals with ASD.

Implementation of structural response sensitivity calculations in a large-scale finite-element analysis system

NASA Technical Reports Server (NTRS)

Giles, G. L.; Rogers, J. L., Jr.

1982-01-01

The methodology used to implement structural sensitivity calculations into a major, general-purpose finite-element analysis system (SPAR) is described. This implementation includes a generalized method for specifying element cross-sectional dimensions as design variables that can be used in analytically calculating derivatives of output quantities from static stress, vibration, and buckling analyses for both membrane and bending elements. Limited sample results for static displacements and stresses are presented to indicate the advantages of analytically calculating response derivatives compared to finite difference methods. Continuing developments to implement these procedures into an enhanced version of SPAR are also discussed.

An analysis of the effects of aeroelasticity on static longitudinal stability and control of a swept-back-wing airplane

NASA Technical Reports Server (NTRS)

Skoog, Richard B

1951-01-01

A theoretical analysis of the effects of aeroelasticity on the stick-fixed static longitudinal stability and elevator angle required for balance of an airplane is presented together with calculated effects for a swept-wing bomber of relatively high flexibility. Although large changes in stability due to certain parameters are indicated for the example airplane, the over-all stability change after considering all parameters was quite small, compared to the individual effects, due to the counterbalancing of wing and tail contributions. The effect of flexibility on longitudinal control for the example airplane was found to be of little real importance.

A Comparative Study of Registration Methods for RGB-D Video of Static Scenes

PubMed Central

Morell-Gimenez, Vicente; Saval-Calvo, Marcelo; Azorin-Lopez, Jorge; Garcia-Rodriguez, Jose; Cazorla, Miguel; Orts-Escolano, Sergio; Fuster-Guillo, Andres

2014-01-01

The use of RGB-D sensors for mapping and recognition tasks in robotics or, in general, for virtual reconstruction has increased in recent years. The key aspect of these kinds of sensors is that they provide both depth and color information using the same device. In this paper, we present a comparative analysis of the most important methods used in the literature for the registration of subsequent RGB-D video frames in static scenarios. The analysis begins by explaining the characteristics of the registration problem, dividing it into two representative applications: scene modeling and object reconstruction. Then, a detailed experimentation is carried out to determine the behavior of the different methods depending on the application. For both applications, we used standard datasets and a new one built for object reconstruction. PMID:24834909

Implementation of structural response sensitivity calculations in a large-scale finite-element analysis system

NASA Technical Reports Server (NTRS)

Giles, G. L.; Rogers, J. L., Jr.

1982-01-01

The implementation includes a generalized method for specifying element cross-sectional dimensions as design variables that can be used in analytically calculating derivatives of output quantities from static stress, vibration, and buckling analyses for both membrane and bending elements. Limited sample results for static displacements and stresses are presented to indicate the advantages of analytically calclating response derivatives compared to finite difference methods. Continuing developments to implement these procedures into an enhanced version of the system are also discussed.

Development and Application of Benchmark Examples for Mixed-Mode I/II Quasi-Static Delamination Propagation Predictions

NASA Technical Reports Server (NTRS)

Krueger, Ronald

2012-01-01

The development of benchmark examples for quasi-static delamination propagation prediction is presented and demonstrated for a commercial code. The examples are based on finite element models of the Mixed-Mode Bending (MMB) specimen. The examples are independent of the analysis software used and allow the assessment of the automated delamination propagation prediction capability in commercial finite element codes based on the virtual crack closure technique (VCCT). First, quasi-static benchmark examples were created for the specimen. Second, starting from an initially straight front, the delamination was allowed to propagate under quasi-static loading. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. Good agreement between the results obtained from the automated propagation analysis and the benchmark results could be achieved by selecting input parameters that had previously been determined during analyses of mode I Double Cantilever Beam and mode II End Notched Flexure specimens. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Overall the results are encouraging, but further assessment for mixed-mode delamination fatigue onset and growth is required.

Comparison of tropical cyclogenesis processes in climate model and cloud-resolving model simulations using moist static energy budget analysis

NASA Astrophysics Data System (ADS)

Wing, Allison; Camargo, Suzana; Sobel, Adam; Kim, Daehyun; Murakami, Hiroyuki; Reed, Kevin; Vecchi, Gabriel; Wehner, Michael; Zarzycki, Colin; Zhao, Ming

2017-04-01

In recent years, climate models have improved such that high-resolution simulations are able to reproduce the climatology of tropical cyclone activity with some fidelity and show some skill in seasonal forecasting. However biases remain in many models, motivating a better understanding of what factors control the representation of tropical cyclone activity in climate models. We explore the tropical cyclogenesis processes in five high-resolution climate models, including both coupled and uncoupled configurations. Our analysis framework focuses on how convection, moisture, clouds and related processes are coupled and employs budgets of column moist static energy and the spatial variance of column moist static energy. The latter was originally developed to study the mechanisms of tropical convective organization in idealized cloud-resolving models, and allows us to quantify the different feedback processes responsible for the amplification of moist static energy anomalies associated with the organization of convection and cyclogenesis. We track the formation and evolution of tropical cyclones in the climate model simulations and apply our analysis both along the individual tracks and composited over many tropical cyclones. We then compare the genesis processes; in particular, the role of cloud-radiation interactions, to those of spontaneous tropical cyclogenesis in idealized cloud-resolving model simulations.

Landing Biomechanics in Participants With Different Static Lower Extremity Alignment Profiles

PubMed Central

Nguyen, Anh-Dung; Shultz, Sandra J.; Schmitz, Randy J.

2015-01-01

Context: Whereas static lower extremity alignment (LEA) has been identified as a risk factor for anterior cruciate ligament injury, little is known about its influence on joint motion and moments commonly associated with anterior cruciate ligament injury. Objective: To cluster participants according to combinations of LEA variables and compare these clusters in hip- and knee-joint kinematics and kinetics during the landing phase of a drop-jump task. Design: Descriptive laboratory study. Setting: Research laboratory. Patients or Other Participants: A total of 141 participants (50 men: age = 22.2 ± 2.8 years, height = 177.9 ± 9.3 cm, weight = 80.9 ± 13.3 kg; 91 women: age = 21.2 ± 2.6 years, height = 163.9 ± 6.6 cm, weight = 61.1 ± 8.7 kg). Main Outcome Measure(s): Static LEA included pelvic angle, femoral anteversion, quadriceps angle, tibiofemoral angle, genu recurvatum, tibial torsion, and navicular drop. Cluster analysis grouped participants according to their static LEA profiles, and these groups were compared on their hip- and knee-joint kinematics and external moments during the landing phase of a double-legged drop jump. Results: Three distinct clusters (C1–C3) were identified based on their static LEAs. Participants in clusters characterized with static internally rotated hip and valgus knee posture (C1) and externally rotated knee and valgus knee posture (C3) alignments demonstrated greater knee-valgus motion and smaller hip-flexion moments than the cluster with more neutral static alignment (C2). Participants in C1 also experienced greater hip internal-rotation and knee external-rotation moments than those in C2 and C3. Conclusions: Static LEA clusters that are positioned anatomically with a more rotated and valgus knee posture experienced greater dynamic valgus along with hip and knee moments during landing. Whereas static LEA contributes to differences in hip and knee rotational moments, sex may influence the differences in frontal-plane knee kinematics and sagittal-plane hip moments. PMID:25658815

Statically vs dynamically balanced gait: Analysis of a robotic exoskeleton compared with a human.

PubMed

Barbareschi, Giulia; Richards, Rosie; Thornton, Matt; Carlson, Tom; Holloway, Catherine

2015-01-01

In recent years exoskeletons able to replicate human gait have begun to attract growing popularity for both assistive and rehabilitative purposes. Although wearable robots often need the use of external support in order to maintain stability, the REX exoskeleton by REX Bionics is able to self-balance through the whole cycle. However this statically balanced gait presents important differences with the dynamically balanced gait of human subjects. This paper will examine kinematic and kinetic differences between the gait analysis performed on a subject wearing the REX exoskeleton and human gait analysis data as presented in literature. We will also provide an insight on the impact that these differences can have for both rehabilitative and assistive applications.

Effectiveness of Simulation in a Hybrid and Online Networking Course.

ERIC Educational Resources Information Center

Cameron, Brian H.

2003-01-01

Reports on a study that compares the performance of students enrolled in two sections of a Web-based computer networking course: one utilizing a simulation package and the second utilizing a static, graphical software package. Analysis shows statistically significant improvements in performance in the simulation group compared to the…

Scaling Effects in Carbon/Epoxy Laminates Under Transverse Quasi-Static Loading

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Douglas, Michael J.; Estes, Eric E.

1999-01-01

Scaling effects were considered for 8, 16, 32, and 64 ply IM-7/8551-7 carbon/epoxy composites plates transversely loaded to the first significant load drop by means of both a quasi-static and an equivalent impact force. The resulting damage was examined by x-ray and photomicroscopy analysis. Load-deflection curves were generated for the quasi-static tests and the resulting indentation depth was measured. Results showed that the load-deflection data scaled well for most of the various thicknesses of plates. However, damage did not scale as well. No correlation could be found between dent depth and any of the other parameters measured in this study. The impact test results showed that significantly less damage was formed compared to the quasi- static results for a given maximum transverse load. The criticality of ply-level scaling (grouping plies) was also examined.

Combining Static Analysis and Model Checking for Software Analysis

NASA Technical Reports Server (NTRS)

Brat, Guillaume; Visser, Willem; Clancy, Daniel (Technical Monitor)

2003-01-01

We present an iterative technique in which model checking and static analysis are combined to verify large software systems. The role of the static analysis is to compute partial order information which the model checker uses to reduce the state space. During exploration, the model checker also computes aliasing information that it gives to the static analyzer which can then refine its analysis. The result of this refined analysis is then fed back to the model checker which updates its partial order reduction. At each step of this iterative process, the static analysis computes optimistic information which results in an unsafe reduction of the state space. However we show that the process converges to a fired point at which time the partial order information is safe and the whole state space is explored.

Respiratory monitoring system based on the nasal pressure technique for the analysis of sleep breathing disorders: Reduction of static and dynamic errors, and comparisons with thermistors and pneumotachographs

NASA Astrophysics Data System (ADS)

Alves de Mesquita, Jayme; Lopes de Melo, Pedro

2004-03-01

Thermally sensitive devices—thermistors—have usually been used to monitor sleep-breathing disorders. However, because of their long time constant, these devices are not able to provide a good characterization of fast events, like hypopneas. Nasal pressure recording technique (NPR) has recently been suggested to quantify airflow during sleep. It is claimed that the short time constants of the devices used to implement this technique would allow an accurate analysis of fast abnormal respiratory events. However, these devices present errors associated with nonlinearities and acoustic resonance that could reduce the diagnostic value of the NPR. Moreover, in spite of the high scientific and clinical potential, there is no detailed description of a complete instrumentation system to implement this promising technique in sleep studies. In this context, the purpose of this work was twofold: (1) describe the development of a flexible NPR device and (2) evaluate the performance of this device when compared to pneumotachographs (PNTs) and thermistors. After the design details are described, the system static accuracy is evaluated by a comparative analysis with a PNT. This analysis revealed a significant reduction (p<0.001) of the static error when system nonlinearities were reduced. The dynamic performance of the NPR system was investigated by frequency response analysis and time constant evaluations and the results showed that the developed device response was as good as PNT and around 100 times faster (τ=5,3 ms) than thermistors (τ=512 ms). Experimental results obtained in simulated clinical conditions and in a patient are presented as examples, and confirmed the good features achieved in engineering tests. These results are in close agreement with physiological fundamentals, supplying substantial evidence that the improved dynamic and static characteristics of this device can contribute to a more accurate implementation of medical research projects and to improve the diagnoses of sleep-breathing disorders.

A Comparison of the Immediate Effects of Eccentric Training vs Static Stretch on Hamstring Flexibility in High School and College Athletes.

PubMed

Nelson, Russell T

2006-05-01

A pre-event static stretching program is often used to prepare an athlete for competition. Recent studies have suggested that static stretching may not be an effective method for stretching the muscle prior to competition. The intent of this study was to compare the immediate effect of static stretching, eccentric training, and no stretching/training on hamstring flexibility in high school and college athletes. Seventy-five athletes, with a mean age of 17.22 (+/- 1.30) were randomly assigned to one of three groups - thirty- second static stretch one time, an eccentric training protocol through a full range of motion, and a control group. All athletes had limited hamstring flexibility, defined as a 20° loss of knee extension measured with the femur held at 90° of hip flexion. A significant difference was indicated by follow up analysis between the control group (gain = -1.08°) and both the static stretch (gain = 5.05°) and the eccentric training group (gain = 9.48°). In addition, the gains in the eccentric training group were significantly greater than the static stretch group. The findings of this study reveal that one session of eccentrically training through a full range of motion improved hamstring flexibility better than the gains made by a static stretch group or a control group.

A Comparison of the Immediate Effects of Eccentric Training vs Static Stretch on Hamstring Flexibility in High School and College Athletes

PubMed Central

2006-01-01

Background A pre-event static stretching program is often used to prepare an athlete for competition. Recent studies have suggested that static stretching may not be an effective method for stretching the muscle prior to competition. Objective The intent of this study was to compare the immediate effect of static stretching, eccentric training, and no stretching/training on hamstring flexibility in high school and college athletes. Methods Seventy-five athletes, with a mean age of 17.22 (+/- 1.30) were randomly assigned to one of three groups - thirty- second static stretch one time, an eccentric training protocol through a full range of motion, and a control group. All athletes had limited hamstring flexibility, defined as a 20° loss of knee extension measured with the femur held at 90° of hip flexion. Results A significant difference was indicated by follow up analysis between the control group (gain = -1.08°) and both the static stretch (gain = 5.05°) and the eccentric training group (gain = 9.48°). In addition, the gains in the eccentric training group were significantly greater than the static stretch group. Discussion and Conclusion The findings of this study reveal that one session of eccentrically training through a full range of motion improved hamstring flexibility better than the gains made by a static stretch group or a control group. PMID:21522215

Dynamic stress analysis of smooth and notched fiber composite flexural specimens

NASA Technical Reports Server (NTRS)

Murthy, P. L. N.; Chamis, C. C.

1984-01-01

A detailed analysis of the dynamic stress field in smooth and notched fiber composite (Charpy-type) specimens is reported in this paper. The analysis is performed with the aid of the direct transient response analysis solution sequence of MSC/NASTRAN. Three unidirectional composites were chosen for the study. They are S-Glass/Epoxy, Kevlar/Epoxy and T-300/Epoxy composite systems. The specimens are subjected to an impact load which is modeled as a triangular impulse with a maximum of 2000 lb and a duration of 1 ms. The results are compared with those of static analysis of the specimens subjected to a peak load of 2000 lb. For the geometry and type of materials studied, the static analysis results gave close conservative estimates for the dynamic stresses. Another interesting inference from the study is that the impact induced effects are felt by S-Glass/Epoxy specimens sooner than Kevlar/Epoxy or T-300/Epoxy specimens.

Analysis of foot structure in athletes sustaining proximal fifth metatarsal stress fracture.

PubMed

Hetsroni, Iftach; Nyska, Meir; Ben-Sira, David; Mann, Gideon; Segal, Ofer; Maoz, Guy; Ayalon, Moshe

2010-03-01

In the past, several studies provided anecdotal descriptions of high-arched feet in individuals sustaining proximal fifth metatarsal stress fractures. This relationship has never been supported by scientific evidence. Our objective was to examine whether athletes who sustained this injury had an exceptional static foot structure or dynamic loading pattern. Ten injured professional soccer players who regained full professional activity following a unilateral proximal fifth metatarsal stress fracture and ten control soccer players were examined. Independent variables included static evaluation of foot and arch structure, followed by dynamic plantar foot pressure evaluation. Each variable was compared between injured, contra-lateral uninjured, and control feet. Static measurements of foot and arch structure did not reveal differences among the groups. However, plantar pressure evaluation revealed relative unloading of the fourth metatarsal in injured and uninjured limbs of injured athletes compared with control, while the fifth metatarsal revealed pressure reduction only in the injured limbs of injured athletes. Athletes who sustained proximal fifth metatarsal stress fracture were not characterized by an exceptional static foot structure. Dynamically, lateral metatarsal unloading during stance may either play a role in the pathogenesis of the injury, or alternately represent an adaptive process. Footwear fabrication for previously injured athletes should not categorically address cushioning properties designed for high-arch feet, but rather focus on individual dynamic evaluation of forefoot loading, with less attention applied to static foot and arch characteristics.

Application of Benchmark Examples to Assess the Single and Mixed-Mode Static Delamination Propagation Capabilities in ANSYS

NASA Technical Reports Server (NTRS)

Krueger, Ronald

2012-01-01

The application of benchmark examples for the assessment of quasi-static delamination propagation capabilities is demonstrated for ANSYS. The examples are independent of the analysis software used and allow the assessment of the automated delamination propagation in commercial finite element codes based on the virtual crack closure technique (VCCT). The examples selected are based on two-dimensional finite element models of Double Cantilever Beam (DCB), End-Notched Flexure (ENF), Mixed-Mode Bending (MMB) and Single Leg Bending (SLB) specimens. First, the quasi-static benchmark examples were recreated for each specimen using the current implementation of VCCT in ANSYS . Second, the delamination was allowed to propagate under quasi-static loading from its initial location using the automated procedure implemented in the finite element software. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Overall the results are encouraging, but further assessment for three-dimensional solid models is required.

A potential model for drug screening by simulating the effect of shear stress in vivo on endothelium.

PubMed

Xu, Yingqian; Wang, Bochu; Deng, Jia; Liu, Zerong; Zhu, Liancai

2013-01-01

The purpose of this paper was to research the potential of a dynamic cell model in drug screening by studying the influence of microvascular wall shear stress on the drug absorption of endothelial cells compared to that in the static state. The cells were grown and seeded on gelatin-coated glass slides and were pretreated with extracts of Salviae miltiorrhizae (200 μg/ml) for 1 h. Then oxidative stress damage was produced by H2O2 (300 μmol/l) for 0.5 h under the 1.5 dyn/cm2 shear stress incorporated in a parallel plate flow chamber. Morphological analysis was conducted with an inverted microscope and image analysis software, and high performance liquid chromatography-mass spectrometry was used for the detection of active compounds. We compared the drug absorption in the dynamic group with that in the static group. In the dynamic model, five compounds and two new metabolite peaks were detected. However, in the static model, four compounds were absorbed by cells, and one metabolite peak was found. This study indicated that there were some effects on the absorption and metabolism of drugs under the microvascular shear stress compared to that under stasis. We infer that shear stress in the microcirculation situation in vivo played a role in causing the differences between drug screening in vitro and in vivo.

Stall flutter analysis of propfans

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.

1988-01-01

Three semi-empirical aerodynamic stall models are compared with respect to their lift and moment hysteresis loop prediction, limit cycle behavior, easy implementation, and feasibility in developing the parameters required for stall flutter prediction of advanced turbines. For the comparison of aeroelastic response prediction including stall, a typical section model and a plate structural model are considered. The response analysis includes both plunging and pitching motions of the blades. In model A, a correction of the angle of attack is applied when the angle of attack exceeds the static stall angle. In model B, a synthesis procedure is used for angles of attack above static stall angles, and the time history effects are accounted for through the Wagner function.

Closed-form Static Analysis with Inertia Relief and Displacement-Dependent Loads Using a MSC/NASTRAN DMAP Alter

NASA Technical Reports Server (NTRS)

Barnett, Alan R.; Widrick, Timothy W.; Ludwiczak, Damian R.

1995-01-01

Solving for the displacements of free-free coupled systems acted upon by static loads is commonly performed throughout the aerospace industry. Many times, these problems are solved using static analysis with inertia relief. This solution technique allows for a free-free static analysis by balancing the applied loads with inertia loads generated by the applied loads. For some engineering applications, the displacements of the free-free coupled system induce additional static loads. Hence, the applied loads are equal to the original loads plus displacement-dependent loads. Solving for the final displacements of such systems is commonly performed using iterative solution techniques. Unfortunately, these techniques can be time-consuming and labor-intensive. Since the coupled system equations for free-free systems with displacement-dependent loads can be written in closed-form, it is advantageous to solve for the displacements in this manner. Implementing closed-form equations in static analysis with inertia relief is analogous to implementing transfer functions in dynamic analysis. Using a MSC/NASTRAN DMAP Alter, displacement-dependent loads have been included in static analysis with inertia relief. Such an Alter has been used successfully to solve efficiently a common aerospace problem typically solved using an iterative technique.

Impaired social brain network for processing dynamic facial expressions in autism spectrum disorders

PubMed Central

2012-01-01

Background Impairment of social interaction via facial expressions represents a core clinical feature of autism spectrum disorders (ASD). However, the neural correlates of this dysfunction remain unidentified. Because this dysfunction is manifested in real-life situations, we hypothesized that the observation of dynamic, compared with static, facial expressions would reveal abnormal brain functioning in individuals with ASD. We presented dynamic and static facial expressions of fear and happiness to individuals with high-functioning ASD and to age- and sex-matched typically developing controls and recorded their brain activities using functional magnetic resonance imaging (fMRI). Result Regional analysis revealed reduced activation of several brain regions in the ASD group compared with controls in response to dynamic versus static facial expressions, including the middle temporal gyrus (MTG), fusiform gyrus, amygdala, medial prefrontal cortex, and inferior frontal gyrus (IFG). Dynamic causal modeling analyses revealed that bi-directional effective connectivity involving the primary visual cortex–MTG–IFG circuit was enhanced in response to dynamic as compared with static facial expressions in the control group. Group comparisons revealed that all these modulatory effects were weaker in the ASD group than in the control group. Conclusions These results suggest that weak activity and connectivity of the social brain network underlie the impairment in social interaction involving dynamic facial expressions in individuals with ASD. PMID:22889284

Stiffness Parameter Design of Suspension Element of Under-Chassis-Equipment for A Rail Vehicle

NASA Astrophysics Data System (ADS)

Ma, Menglin; Wang, Chengqiang; Deng, Hai

2017-06-01

According to the frequency configuration requirements of the vibration of railway under-chassis-equipment, the three- dimension stiffness of the suspension elements of under-chassis-equipment is designed based on the static principle and dynamics principle. The design results of the concrete engineering case show that, compared with the design method based on the static principle, the three- dimension stiffness of the suspension elements designed by the dynamic principle design method is more uniform. The frequency and decoupling degree analysis show that the calculation frequency of under-chassis-equipment under the two design methods is basically the same as the predetermined frequency. Compared with the design method based on the static principle, the design method based on the dynamic principle is adopted. The decoupling degree can be kept high, and the coupling vibration of the corresponding vibration mode can be reduced effectively, which can effectively reduce the fatigue damage of the key parts of the hanging element.

Detection of Fatty Acids from Intact Microorganisms by Molecular Beam Static Secondary Ion Mass Spectrometry

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

Ingram, Jani Cheri; Lehman, Richard Michael; Bauer, William Francis

We report the use of a surface analysis approach, static secondary ion mass spectrometry (SIMS) equipped with a molecular (ReO4-) ion primary beam, to analyze the surface of intact microbial cells. SIMS spectra of 28 microorganisms were compared to fatty acid profiles determined by gas chromatographic analysis of transesterfied fatty acids extracted from the same organisms. The results indicate that surface bombardment using the molecular primary beam cleaved the ester linkage characteristic of bacteria at the glycerophosphate backbone of the phospholipid components of the cell membrane. This cleavage enables direct detection of the fatty acid conjugate base of intact microorganismsmore » by static SIMS. The limit of detection for this approach is approximately 107 bacterial cells/cm2. Multivariate statistical methods were applied in a graded approach to the SIMS microbial data. The results showed that the full data set could initially be statistically grouped based upon major differences in biochemical composition of the cell wall. The gram-positive bacteria were further statistically analyzed, followed by final analysis of a specific bacterial genus that was successfully grouped by species. Additionally, the use of SIMS to detect microbes on mineral surfaces is demonstrated by an analysis of Shewanella oneidensis on crushed hematite. The results of this study provide evidence for the potential of static SIMS to rapidly detect bacterial species based on ion fragments originating from cell membrane lipids directly from sample surfaces.« less

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

Caliandro, Rocco; Sibillano, Teresa; Belviso, B. Danilo

In this study, we have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO 3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO 3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtlemore » stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO 3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO 3-x NC lattice, rather than a variation in stoichiometry. Finally, the time behavior of such structural change is identified on the basis of multivariate analysis.« less

Compilation time analysis to minimize run-time overhead in preemptive scheduling on multiprocessors

NASA Astrophysics Data System (ADS)

Wauters, Piet; Lauwereins, Rudy; Peperstraete, J.

1994-10-01

This paper describes a scheduling method for hard real-time Digital Signal Processing (DSP) applications, implemented on a multi-processor. Due to the very high operating frequencies of DSP applications (typically hundreds of kHz) runtime overhead should be kept as small as possible. Because static scheduling introduces very little run-time overhead it is used as much as possible. Dynamic pre-emption of tasks is allowed if and only if it leads to better performance in spite of the extra run-time overhead. We essentially combine static scheduling with dynamic pre-emption using static priorities. Since we are dealing with hard real-time applications we must be able to guarantee at compile-time that all timing requirements will be satisfied at run-time. We will show that our method performs at least as good as any static scheduling method. It also reduces the total amount of dynamic pre-emptions compared with run time methods like deadline monotonic scheduling.

Comparison and statistical analysis of four write stability metrics in bulk CMOS static random access memory cells

NASA Astrophysics Data System (ADS)

Qiu, Hao; Mizutani, Tomoko; Saraya, Takuya; Hiramoto, Toshiro

2015-04-01

The commonly used four metrics for write stability were measured and compared based on the same set of 2048 (2k) six-transistor (6T) static random access memory (SRAM) cells by the 65 nm bulk technology. The preferred one should be effective for yield estimation and help predict edge of stability. Results have demonstrated that all metrics share the same worst SRAM cell. On the other hand, compared to butterfly curve with non-normality and write N-curve where no cell state flip happens, bit-line and word-line margins have good normality as well as almost perfect correlation. As a result, both bit line method and word line method prove themselves preferred write stability metrics.

Discourse Analysis and Development of English Listening for Non-English Majors in China

ERIC Educational Resources Information Center

Ji, Yinxiu

2015-01-01

Traditional approach of listening teaching mainly focuses on the sentence level and regards the listening process in a passive and static way. To compensate for this deficiency, a new listening approach, that is, discourse-oriented approach has been introduced into the listening classroom. Although discourse analysis is a comparatively new field…

MSC/NASTRAN DMAP Alter Used for Closed-Form Static Analysis With Inertia Relief and Displacement-Dependent Loads

NASA Technical Reports Server (NTRS)

1996-01-01

Solving for the displacements of free-free coupled systems acted upon by static loads is a common task in the aerospace industry. Often, these problems are solved by static analysis with inertia relief. This technique allows for a free-free static analysis by balancing the applied loads with the inertia loads generated by the applied loads. For some engineering applications, the displacements of the free-free coupled system induce additional static loads. Hence, the applied loads are equal to the original loads plus the displacement-dependent loads. A launch vehicle being acted upon by an aerodynamic loading can have such applied loads. The final displacements of such systems are commonly determined with iterative solution techniques. Unfortunately, these techniques can be time consuming and labor intensive. Because the coupled system equations for free-free systems with displacement-dependent loads can be written in closed form, it is advantageous to solve for the displacements in this manner. Implementing closed-form equations in static analysis with inertia relief is analogous to implementing transfer functions in dynamic analysis. An MSC/NASTRAN (MacNeal-Schwendler Corporation/NASA Structural Analysis) DMAP (Direct Matrix Abstraction Program) Alter was used to include displacement-dependent loads in static analysis with inertia relief. It efficiently solved a common aerospace problem that typically has been solved with an iterative technique.

Nonlinear static and dynamic finite element analysis of an eccentrically loaded graphite-epoxy beam

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Jones, Lisa E.

1991-01-01

The Dynamic Crash Analysis of Structures (DYCAT) and NIKE3D nonlinear finite element codes were used to model the static and implulsive response of an eccentrically loaded graphite-epoxy beam. A 48-ply unidirectional composite beam was tested under an eccentric axial compressive load until failure. This loading configuration was chosen to highlight the capabilities of two finite element codes for modeling a highly nonlinear, large deflection structural problem which has an exact solution. These codes are currently used to perform dynamic analyses of aircraft structures under impact loads to study crashworthiness and energy absorbing capabilities. Both beam and plate element models were developed to compare with the experimental data using the DYCAST and NIKE3D codes.

Nuclear reactor transient analysis via a quasi-static kinetics Monte Carlo method

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

Jo, YuGwon; Cho, Bumhee; Cho, Nam Zin, E-mail: nzcho@kaist.ac.kr

2015-12-31

The predictor-corrector quasi-static (PCQS) method is applied to the Monte Carlo (MC) calculation for reactor transient analysis. To solve the transient fixed-source problem of the PCQS method, fission source iteration is used and a linear approximation of fission source distributions during a macro-time step is introduced to provide delayed neutron source. The conventional particle-tracking procedure is modified to solve the transient fixed-source problem via MC calculation. The PCQS method with MC calculation is compared with the direct time-dependent method of characteristics (MOC) on a TWIGL two-group problem for verification of the computer code. Then, the results on a continuous-energy problemmore » are presented.« less

Direct surface analysis of pesticides on soil, leaves, grass, and stainless steel by static secondary ion mass spectrometry

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

Ingram, J.C.; Groenewold, G.S.; Appelhans, A.D.

1997-02-01

Direct surface analyses by static secondary ion mass spectrometry (SIMS) were performed for the following pesticides adsorbed on dandelion leaves, grass, soil, and stainless steel samples: alachlor, atrazine, captan, carbofuran, chlorpyrifos, chlorosulfuron, chlorthal-dimethyl, cypermethrin, 2,4-D, diuron, glyphosate, malathion, methomyl, methyl arsonic acid, mocap, norflurazon, oxyfluorfen, paraquat, temik, and trifluralin. The purpose of this study was to evaluate static SIMS as a tool for pesticide analysis, principally for use in screening samples for pesticides. The advantage of direct surface analysis compared with conventional pesticide analysis methods is the elimination of sample pretreatment including extraction, which streamlines the analysis substantially; total analysismore » time for SIMS analysis was ca. 10 min/sample. Detection of 16 of the 20 pesticides on all four substrates was achieved. Of the remaining four pesticides, only one (trifluralin) was not detected on any of the samples. The minimum detectable quantity was determined for paraquat on soil in order to evaluate the efficacy of using SIMS as a screening tool. Paraquat was detected at 3 pg/mm{sup 2} (c.a. 0.005 monolayers). The results of these studies suggest that SIMS is capable of direct surface detection of a range of pesticides, with low volatility, polar pesticides being the most easily detected. 25 refs., 2 figs., 2 tabs.« less

Applications of Temporal Graph Metrics to Real-World Networks

NASA Astrophysics Data System (ADS)

Tang, John; Leontiadis, Ilias; Scellato, Salvatore; Nicosia, Vincenzo; Mascolo, Cecilia; Musolesi, Mirco; Latora, Vito

Real world networks exhibit rich temporal information: friends are added and removed over time in online social networks; the seasons dictate the predator-prey relationship in food webs; and the propagation of a virus depends on the network of human contacts throughout the day. Recent studies have demonstrated that static network analysis is perhaps unsuitable in the study of real world network since static paths ignore time order, which, in turn, results in static shortest paths overestimating available links and underestimating their true corresponding lengths. Temporal extensions to centrality and efficiency metrics based on temporal shortest paths have also been proposed. Firstly, we analyse the roles of key individuals of a corporate network ranked according to temporal centrality within the context of a bankruptcy scandal; secondly, we present how such temporal metrics can be used to study the robustness of temporal networks in presence of random errors and intelligent attacks; thirdly, we study containment schemes for mobile phone malware which can spread via short range radio, similar to biological viruses; finally, we study how the temporal network structure of human interactions can be exploited to effectively immunise human populations. Through these applications we demonstrate that temporal metrics provide a more accurate and effective analysis of real-world networks compared to their static counterparts.

Dynamic ambulance reallocation for the reduction of ambulance response times using system status management.

PubMed

Lam, Sean Shao Wei; Zhang, Ji; Zhang, Zhong Cheng; Oh, Hong Choon; Overton, Jerry; Ng, Yih Yng; Ong, Marcus Eng Hock

2015-02-01

Dynamically reassigning ambulance deployment locations throughout a day to balance ambulance availability and demands can be effective in reducing response times. The objectives of this study were to model dynamic ambulance allocation plans in Singapore based on the system status management (SSM) strategy and to evaluate the dynamic deployment plans using a discrete event simulation (DES) model. The geographical information system-based analysis and mathematical programming were used to develop the dynamic ambulance deployment plans for SSM based on ambulance calls data from January 1, 2011, to June 30, 2011. A DES model that incorporated these plans was used to compare the performance of the dynamic SSM strategy against static reallocation policies under various demands and travel time uncertainties. When the deployment plans based on the SSM strategy were followed strictly, the DES model showed that the geographical information system-based plans resulted in approximately 13-second reduction in the median response times compared to the static reallocation policy, whereas the mathematical programming-based plans resulted in approximately a 44-second reduction. The response times and coverage performances were still better than the static policy when reallocations happened for only 60% of all the recommended moves. Dynamically reassigning ambulance deployment locations based on the SSM strategy can result in superior response times and coverage performance compared to static reallocation policies even when the dynamic plans were not followed strictly. Copyright © 2014 Elsevier Inc. All rights reserved.

The role of visual representation in physics learning: dynamic versus static visualization

NASA Astrophysics Data System (ADS)

Suyatna, Agus; Anggraini, Dian; Agustina, Dina; Widyastuti, Dini

2017-11-01

This study aims to examine the role of visual representation in physics learning and to compare the learning outcomes of using dynamic and static visualization media. The study was conducted using quasi-experiment with Pretest-Posttest Control Group Design. The samples of this research are students of six classes at State Senior High School in Lampung Province. The experimental class received a learning using dynamic visualization and control class using static visualization media. Both classes are given pre-test and post-test with the same instruments. Data were tested with N-gain analysis, normality test, homogeneity test and mean difference test. The results showed that there was a significant increase of mean (N-Gain) learning outcomes (p <0.05) in both experimental and control classes. The averages of students’ learning outcomes who are using dynamic visualization media are significantly higher than the class that obtains learning by using static visualization media. It can be seen from the characteristics of visual representation; each visualization provides different understanding support for the students. Dynamic visual media is more suitable for explaining material related to movement or describing a process, whereas static visual media is appropriately used for non-moving physical phenomena and requires long-term observation.

Relative effects of posture and activity on human height estimation from surveillance footage.

PubMed

Ramstrand, Nerrolyn; Ramstrand, Simon; Brolund, Per; Norell, Kristin; Bergström, Peter

2011-10-10

Height estimations based on security camera footage are often requested by law enforcement authorities. While valid and reliable techniques have been established to determine vertical distances from video frames, there is a discrepancy between a person's true static height and their height as measured when assuming different postures or when in motion (e.g., walking). The aim of the research presented in this report was to accurately record the height of subjects as they performed a variety of activities typically observed in security camera footage and compare results to height recorded using a standard height measuring device. Forty-six able bodied adults participated in this study and were recorded using a 3D motion analysis system while performing eight different tasks. Height measurements captured using the 3D motion analysis system were compared to static height measurements in order to determine relative differences. It is anticipated that results presented in this report can be used by forensic image analysis experts as a basis for correcting height estimations of people captured on surveillance footage. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Assessment of Diagnostic Value of Single View Dynamic Technique in Diagnosis of Developmental Dysplasia of Hip: A Comparison with Static and Dynamic Ultrasond Techniques

PubMed Central

Alamdaran, Seyed Ali; Kazemi, Sahar; Parsa, Ali; Moghadam, Mohammad Hallaj; Feyzi, Ali; Mardani, Reza

2016-01-01

Background: Developmental dysplasia of hip (DDH) is a common childhood disorder, and ultrasonography examination is routinely used for screening purposes. In this study, we aimed to evaluate a modified combined static and dynamic ultrasound technique for the detection of DDH and to compare with the results of static and dynamic ultrasound techniques. Methods: In this cross-sectional study, during 2013- 2015, 300 high-risk infants were evaluated by ultrasound for DDH. Both hips were examined with three techniques: static, dynamic and single view static and dynamic technique. Statistical analysis was performed using SPSS version 11.5. Results: Patients aged 9 days to 83 weeks. 75% of the patients were 1 to 3 months old. Among 600 hip joints, about 5% were immature in static sonography and almost all of them were unstable in dynamic techniques. 0.3% of morphologically normal hips were unstable in dynamic sonography and 9% of unstable hips had normal morphology. The mean β angle differences in coronal view before and after stress maneuver was 14.43±5.47° in unstable hips. Single view static and dynamic technique revealed that all cases with acetabular dysplasia, instability and dislocation, except two dislocations, were detected by dynamic transverse view. For two cases, Ortolani maneuver showed femoral head reversibility in dislocated hips. Using single view static and dynamic technique was indicative and applicable for detection of more than 99% of cases. Conclusion: Single view static and dynamic technique not only is a fast and easy technique, but also it is of high diagnostic value in assessment of DDH. PMID:27847852

Assessment of current AASHTO LRFD methods for static pile capacity analysis in Rhode Island soils.

DOT National Transportation Integrated Search

2013-07-01

This report presents an assessment of current AASHTO LRFD methods for static pile capacity analysis in Rhode : Island soils. Current static capacity methods and associated resistance factors are based on pile load test data in sands : and clays. Some...

Using Queue Time Predictions for Processor Allocation

DTIC Science & Technology

1997-01-01

Diego Supercomputer Center, 1996. 19 [15] Vijay K. Naik, Sanjeev K. Setia , and Mark S. Squillante. Performance analysis of job schedul- ing policies in...Processing, pages 101{111, 1995. [19] Sanjeev K. Setia and Satish K. Tripathi. An analysis of several processor partitioning policies for parallel...computers. Technical Report CS-TR-2684, University of Maryland, May 1991. [20] Sanjeev K. Setia and Satish K. Tripathi. A comparative analysis of static

Static Corrosion Test of Porous Iron Material with Polymer Coating

NASA Astrophysics Data System (ADS)

Markušová-Bučková, Lucia; Oriňaková, Renáta; Oriňak, Andrej; Gorejová, Radka; Kupková, Miriam; Hrubovčáková, Monika; Baláž, Matej; Kováľ, Karol

2016-12-01

At present biodegradable implants received increased attention due to their use in various fields of medicine. This work is dedicated to testing of biodegradable materials which could be used as bone implants. The samples were prepared from the carbonyl iron powder by replication method and surface polymer film was produced through sol-gel process. Corrosion testing was carried out under static conditions during 12 weeks in Hank's solution. The quantity of corrosion products increased with prolonging time of static test as it can be concluded from the results of EDX analysis. The degradation of open cell materials with polyethylene glycol coating layer was faster compared to uncoated Fe sample. Also the mass losses were higher for samples with PEG coating. The polymer coating brought about the desired increase in degradation rate of porous iron material.

Results of the first complete static calibration of the RSRA rotor-load-measurement system

NASA Technical Reports Server (NTRS)

Acree, C. W., Jr.

1984-01-01

The compound Rotor System Research Aircraft (RSRA) is designed to make high-accuracy, simultaneous measurements of all rotor forces and moments in flight. Physical calibration of the rotor force- and moment-measurement system when installed in the aircraft is required to account for known errors and to ensure that measurement-system accuracy is traceable to the National Bureau of Standards. The first static calibration and associated analysis have been completed with good results. Hysteresis was a potential cause of static calibration errors, but was found to be negligible in flight compared to full-scale loads, and analytical methods have been devised to eliminate hysteresis effects on calibration data. Flight tests confirmed that the calibrated rotor-load-measurement system performs as expected in flight and that it can dependably make direct measurements of fuselage vertical drag in hover.

Detection Of Malware Collusion With Static Dependence Analysis On Inter-App Communication

DTIC Science & Technology

2016-12-08

DETECTION OF MALWARE COLLUSION WITH STATIC DEPENDENCE ANALYSIS ON INTER-APP COMMUNICATION VIRGINIA TECH DECEMBER 2016 FINAL TECHNICAL REPORT... DEPENDENCE ANALYSIS ON INTER-APP COMMUNICATION 5a. CONTRACT NUMBER FA8750-15-2-0076 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S...exploited. 15. SUBJECT TERMS Malware Collusion; Inter-App Communication; Static Dependence Analysis 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

A Model for Speedup of Parallel Programs

DTIC Science & Technology

1997-01-01

Sanjeev. K Setia . The interaction between mem- ory allocation and adaptive partitioning in message- passing multicomputers. In IPPS 󈨣 Workshop on Job...Scheduling Strategies for Parallel Processing, pages 89{99, 1995. [15] Sanjeev K. Setia and Satish K. Tripathi. A compar- ative analysis of static

A Comparative Study of the Effects of Pilates and Latin Dance on Static and Dynamic Balance in Older Adults.

PubMed

Sofianidis, George; Dimitriou, Anna-Maria; Hatzitaki, Vassilia

2017-07-01

The present study was designed to compare the effectiveness of exercise programs with Pilates and Latin dance on older adults' static and dynamic balance. Thirty-two older adults were divided into three groups: Pilates group, Dance group, and Control group. Static and dynamic balance was assessed with following tasks: (a) tandem stance, (b) one-leg stance, and (c) periodic sway with and without metronome guidance. Analysis revealed a significant reduction of the trunk sway amplitude during the tandem stance with eyes closed, reduction in the center of pressure (CoP) displacement during one-leg stance, and increase in the amplitude of trunk oscillation during the sway task for both intervention groups, and reduction in the standard deviation of the CoP displacement during the metronome paced task only for the dance group. The differences in specific balance indices between the two programs suggest some specific adaptations that may provide useful knowledge for the selection of exercises that are better tailored to the needs of the old adult.

Design and development aspects of flexure mechanism for high precision application

NASA Astrophysics Data System (ADS)

Sollapur, Shrishail B.; Patil, M. S.; Deshmukh, S. P.

2018-04-01

Planer XY Flexurel Mechanisms has various applications in precision motion mechanisms. A flexural mechanism generates relative motion between fixed support and motion stage using flexibility of material. This mechanism offers zero backlash, frictionless motion and high order repeatability. It is relatively compact in design as compared to rigid link mechanism. The merits of using flexure is complete mechanism can be from single monolith. Modelling of flexural mechanism to provide accurate scanning of comparatively larger range at a higher speed. Static Analysis of mechanism is carried out on FEA tool to determine static deflection of motion stage. Further Mechanism is actuated with the help of weight pan and weights. The resultant displacement is measured on Dial Gauge Indicator. Experimental set-up consists of Flexural mechanism, Dial Gauge, Weight Pan and Weights, Pulley, String, Small metal strip, Optical Bread Board etc. Further experimental Results and Analytical Results are compared and minimum deviation is found.

Gas Measurement Using Static Fourier Transform Infrared Spectrometers.

PubMed

Köhler, Michael H; Schardt, Michael; Rauscher, Markus S; Koch, Alexander W

2017-11-13

Online monitoring of gases in industrial processes is an ambitious task due to adverse conditions such as mechanical vibrations and temperature fluctuations. Whereas conventional Fourier transform infrared (FTIR) spectrometers use rather complex optical and mechanical designs to ensure stable operation, static FTIR spectrometers do not require moving parts and thus offer inherent stability at comparatively low costs. Therefore, we present a novel, compact gas measurement system using a static single-mirror Fourier transform spectrometer (sSMFTS). The system works in the mid-infrared range from 650 cm - 1 to 1250 cm - 1 and can be operated with a customized White cell, yielding optical path lengths of up to 120 cm for highly sensitive quantification of gas concentrations. To validate the system, we measure different concentrations of 1,1,1,2-Tetrafluoroethane (R134a) and perform a PLS regression analysis of the acquired infrared spectra. Thereby, the measured absorption spectra show good agreement with reference data. Since the system additionally permits measurement rates of up to 200 Hz and high signal-to-noise ratios, an application in process analysis appears promising.

Gas Measurement Using Static Fourier Transform Infrared Spectrometers

PubMed Central

Schardt, Michael; Rauscher, Markus S.; Koch, Alexander W.

2017-01-01

Online monitoring of gases in industrial processes is an ambitious task due to adverse conditions such as mechanical vibrations and temperature fluctuations. Whereas conventional Fourier transform infrared (FTIR) spectrometers use rather complex optical and mechanical designs to ensure stable operation, static FTIR spectrometers do not require moving parts and thus offer inherent stability at comparatively low costs. Therefore, we present a novel, compact gas measurement system using a static single-mirror Fourier transform spectrometer (sSMFTS). The system works in the mid-infrared range from 650 cm−1 to 1250 cm−1 and can be operated with a customized White cell, yielding optical path lengths of up to 120 cm for highly sensitive quantification of gas concentrations. To validate the system, we measure different concentrations of 1,1,1,2-Tetrafluoroethane (R134a) and perform a PLS regression analysis of the acquired infrared spectra. Thereby, the measured absorption spectra show good agreement with reference data. Since the system additionally permits measurement rates of up to 200 Hz and high signal-to-noise ratios, an application in process analysis appears promising. PMID:29137193

Static, Modal and Buckling Analyses of Automotive Propeller Shaft using Finite Element Methods

NASA Astrophysics Data System (ADS)

Kumar, Mukul; Singh, Nilamber Kumar

2018-03-01

This paper presents a comparative study of static, modal and buckling analyses of aluminium alloys and steel, Al6351, Al7075 and SM45C made automotive propeller shafts using finite element methods. The 3D-model of propeller shaft is created in CATIA and then analysis is done using ANSYS. Natural frequency is determined for six different mode shapes and the critical load at which the propeller shaft starts buckling is compared for dissimilar materials. The stress distribution and unsafe areas are shown for the modification in existing design of the propeller shaft. It is found that the aluminum propeller shaft has higher natural frequency than the steel propeller shaft. Therefore, the resonance stage reaches later in aluminum propeller shaft and enhances its life.

Static and Dynamic Measurement of Accommodation Using the Grand Seiko WAM-5500 Autorefractor

PubMed Central

Win-Hall, Dorothy M.; Houser, Jaime; Glasser, Adrian

2013-01-01

Purpose The Grand Seiko WR-5500 (WAM) is an open field autorefractor capable of measuring accommodation and pupil diameter dynamically. This study was undertaken to compare static and dynamic accommodation measurements with this instrument in young, phakic subjects. Methods Fifteen subjects, aged 20–28 years (23.8±0.58; mean±SD) participated. Accommodation was stimulated with text printed on a transparent sheet presented at various distances. In static mode, subjects focused on the near text and three measurements were taken for each stimulus amplitude. In dynamic mode, the 5 Hz recording was started and subjects alternately looked through the transparent near chart and focused on a letter chart at 6 m for 5 seconds and then focused on the near letter chart for 5 seconds for a total of 30 seconds. After smoothing the raw data, the highest three individual values recorded in each 5 second interval of focusing at near were averaged for each stimulus amplitude. ANOVA and Bland-Altman analysis were used to compare the static and dynamic measurements. A calibration was performed with +3.00 to -10.00 D trial lenses behind an IR filter, in 1.00 D steps in 5 of the 15 subjects. Results Stimulus-response graphs from static and dynamic modes were not significantly different in the lower stimulus range (< 5.00 D, p = 0.93), but differed significantly for the higher stimulus amplitudes (p = 0.0027). One of 15 subjects showed a significant difference between the static and dynamic modes. Corresponding pupil diameter could be recorded along with the accommodation responses for the subjects and pupil diameter decreased with increasing stimulus demand. Calibration curves for static and dynamic measurements were not significantly different from the 1:1 line or from each other (p = 0.32). Conclusion Although slight differences between the dynamically and statically recorded responses were identified, the Grand-Seiko WAM autorefractor provides the ability to measure both. Dynamic measurement of accommodation and pupil constriction potentially provides additional useful information on the accommodative response other than simply the response amplitude. PMID:20852450

A foundational methodology for determining system static complexity using notional lunar oxygen production processes

NASA Astrophysics Data System (ADS)

Long, Nicholas James

This thesis serves to develop a preliminary foundational methodology for evaluating the static complexity of future lunar oxygen production systems when extensive information is not yet available about the various systems under consideration. Evaluating static complexity, as part of a overall system complexity analysis, is an important consideration in ultimately selecting a process to be used in a lunar base. When system complexity is higher, there is generally an overall increase in risk which could impact the safety of astronauts and the economic performance of the mission. To evaluate static complexity in lunar oxygen production, static complexity is simplified and defined into its essential components. First, three essential dimensions of static complexity are investigated, including interconnective complexity, strength of connections, and complexity in variety. Then a set of methods is developed upon which to separately evaluate each dimension. Q-connectivity analysis is proposed as a means to evaluate interconnective complexity and strength of connections. The law of requisite variety originating from cybernetic theory is suggested to interpret complexity in variety. Secondly, a means to aggregate the results of each analysis is proposed to create holistic measurement for static complexity using the Single Multi-Attribute Ranking Technique (SMART). Each method of static complexity analysis and the aggregation technique is demonstrated using notional data for four lunar oxygen production processes.

Eccentric Training and Static Stretching Improve Hamstring Flexibility of High School Males

PubMed Central

Bandy, William D.

2004-01-01

Objective: To determine if the flexibility of high-school-aged males would improve after a 6-week eccentric exercise program. In addition, the changes in hamstring flexibility that occurred after the eccentric program were compared with a 6-week program of static stretching and with a control group (no stretching). Design and Setting: We used a test-retest control group design in a laboratory setting. Subjects were assigned randomly to 1 of 3 groups: eccentric training, static stretching, or control. Subjects: A total of 69 subjects, with a mean age of 16.45 ± 0.96 years and with limited hamstring flexibility (defined as 20° loss of knee extension measured with the thigh held at 90° of hip flexion) were recruited for this study. Measurements: Hamstring flexibility was measured using the passive 90/90 test before and after the 6-week program. Results: Differences were significant for test and for the test-by-group interaction. Follow-up analysis indicated significant differences between the control group (gain = 1.67°) and both the eccentric-training (gain = 12.79°) and static-stretching (gain = 12.05°) groups. No difference was found between the eccentric and static-stretching groups. Conclusions: The gains achieved in range of motion of knee extension (indicating improvement in hamstring flexibility) with eccentric training were equal to those made by statically stretching the hamstring muscles. PMID:15496995

Eccentric Training and Static Stretching Improve Hamstring Flexibility of High School Males.

PubMed

Nelson, Russell T; Bandy, William D

2004-09-01

OBJECTIVE: To determine if the flexibility of high-school-aged males would improve after a 6-week eccentric exercise program. In addition, the changes in hamstring flexibility that occurred after the eccentric program were compared with a 6-week program of static stretching and with a control group (no stretching). DESIGN AND SETTING: We used a test-retest control group design in a laboratory setting. Subjects were assigned randomly to 1 of 3 groups: eccentric training, static stretching, or control. SUBJECTS: A total of 69 subjects, with a mean age of 16.45 +/- 0.96 years and with limited hamstring flexibility (defined as 20 degrees loss of knee extension measured with the thigh held at 90 degrees of hip flexion) were recruited for this study. MEASUREMENTS: Hamstring flexibility was measured using the passive 90/90 test before and after the 6-week program. RESULTS: Differences were significant for test and for the test-by-group interaction. Follow-up analysis indicated significant differences between the control group (gain = 1.67 degrees ) and both the eccentric-training (gain = 12.79 degrees ) and static-stretching (gain = 12.05 degrees ) groups. No difference was found between the eccentric and static-stretching groups. CONCLUSIONS: The gains achieved in range of motion of knee extension (indicating improvement in hamstring flexibility) with eccentric training were equal to those made by statically stretching the hamstring muscles.

Effect of yoga training on one leg standing and functional reach tests in obese individuals with poor postural control

PubMed Central

Jorrakate, Chaiyong; Kongsuk, Jutaluk; Pongduang, Chiraprapa; Sadsee, Boontiwa; Chanthorn, Phatchari

2015-01-01

[Purpose] The aim of the present study was to investigate the effect of yoga training on static and dynamic standing balance in obese individuals with poor standing balance. [Subjects and Methods] Sixteen obese volunteers were randomly assigned into yoga and control groups. The yoga training program was performed for 45 minutes per day, 3 times per week, for 4 weeks. Static and dynamic balance were assessed in volunteers with one leg standing and functional reach tests. Outcome measures were tested before training and after a single week of training. Two-way repeated measure analysis of variance with Tukey’s honestly significant difference post hoc statistics was used to analyze the data. [Results] Obese individuals showed significantly increased static standing balance in the yoga training group, but there was no significant improvement of static or dynamic standing balance in the control group after 4 weeks. In the yoga group, significant increases in static standing balance was found after the 2nd, 3rd, and 4th weeks. Compared with the control group, static standing balance in the yoga group was significantly different after the 2nd week, and dynamic standing balance was significantly different after the 4th week. [Conclusion] Yoga training would be beneficial for improving standing balance in obese individuals with poor standing balance. PMID:25642038

Supporting secure programming in web applications through interactive static analysis.

PubMed

Zhu, Jun; Xie, Jing; Lipford, Heather Richter; Chu, Bill

2014-07-01

Many security incidents are caused by software developers' failure to adhere to secure programming practices. Static analysis tools have been used to detect software vulnerabilities. However, their wide usage by developers is limited by the special training required to write rules customized to application-specific logic. Our approach is interactive static analysis, to integrate static analysis into Integrated Development Environment (IDE) and provide in-situ secure programming support to help developers prevent vulnerabilities during code construction. No additional training is required nor are there any assumptions on ways programs are built. Our work is motivated in part by the observation that many vulnerabilities are introduced due to failure to practice secure programming by knowledgeable developers. We implemented a prototype interactive static analysis tool as a plug-in for Java in Eclipse. Our technical evaluation of our prototype detected multiple zero-day vulnerabilities in a large open source project. Our evaluations also suggest that false positives may be limited to a very small class of use cases.

Supporting secure programming in web applications through interactive static analysis

PubMed Central

Zhu, Jun; Xie, Jing; Lipford, Heather Richter; Chu, Bill

2013-01-01

Many security incidents are caused by software developers’ failure to adhere to secure programming practices. Static analysis tools have been used to detect software vulnerabilities. However, their wide usage by developers is limited by the special training required to write rules customized to application-specific logic. Our approach is interactive static analysis, to integrate static analysis into Integrated Development Environment (IDE) and provide in-situ secure programming support to help developers prevent vulnerabilities during code construction. No additional training is required nor are there any assumptions on ways programs are built. Our work is motivated in part by the observation that many vulnerabilities are introduced due to failure to practice secure programming by knowledgeable developers. We implemented a prototype interactive static analysis tool as a plug-in for Java in Eclipse. Our technical evaluation of our prototype detected multiple zero-day vulnerabilities in a large open source project. Our evaluations also suggest that false positives may be limited to a very small class of use cases. PMID:25685513

NASA-approved rotary bioreactor enhances proliferation of human epidermal stem cells and supports formation of 3D epidermis-like structure.

PubMed

Lei, Xiao-hua; Ning, Li-na; Cao, Yu-jing; Liu, Shuang; Zhang, Shou-bing; Qiu, Zhi-fang; Hu, Hui-min; Zhang, Hui-shan; Liu, Shu; Duan, En-kui

2011-01-01

The skin is susceptible to different injuries and diseases. One major obstacle in skin tissue engineering is how to develop functional three-dimensional (3D) substitute for damaged skin. Previous studies have proved a 3D dynamic simulated microgravity (SMG) culture system as a "stimulatory" environment for the proliferation and differentiation of stem cells. Here, we employed the NASA-approved rotary bioreactor to investigate the proliferation and differentiation of human epidermal stem cells (hEpSCs). hEpSCs were isolated from children foreskins and enriched by collecting epidermal stem cell colonies. Cytodex-3 micro-carriers and hEpSCs were co-cultured in the rotary bioreactor and 6-well dish for 15 days. The result showed that hEpSCs cultured in rotary bioreactor exhibited enhanced proliferation and viability surpassing those cultured in static conditions. Additionally, immunostaining analysis confirmed higher percentage of ki67 positive cells in rotary bioreactor compared with the static culture. In contrast, comparing with static culture, cells in the rotary bioreactor displayed a low expression of involucrin at day 10. Histological analysis revealed that cells cultured in rotary bioreactor aggregated on the micro-carriers and formed multilayer 3D epidermis structures. In conclusion, our research suggests that NASA-approved rotary bioreactor can support the proliferation of hEpSCs and provide a strategy to form multilayer epidermis structure.

Aerodynamic characteristics of a large-scale semispan model with a swept wing and an augmented jet flap with hypermixing nozzles. [Ames 40- by 80-Foot Wind Tunnel and Static Test Facility

NASA Technical Reports Server (NTRS)

Aiken, T. N.; Falarski, M. D.; Koenin, D. G.

1979-01-01

The aerodynamic characteristics of the augmentor wing concept with hypermixing primary nozzles were investigated. A large-scale semispan model in the Ames 40- by 80-Foot Wind Tunnel and Static Test Facility was used. The trailing edge, augmentor flap system occupied 65% of the span and consisted of two fixed pivot flaps. The nozzle system consisted of hypermixing, lobe primary nozzles, and BLC slot nozzles at the forward inlet, both sides and ends of the throat, and at the aft flap. The entire wing leading edge was fitted with a 10% chord slat and a blowing slot. Outboard of the flap was a blown aileron. The model was tested statically and at forward speed. Primary parameters and their ranges included angle of attack from -12 to 32 degrees, flap angles of 20, 30, 45, 60 and 70 degrees, and deflection and diffuser area ratios from 1.16 to 2.22. Thrust coefficients ranged from 0 to 2.73, while nozzle pressure ratios varied from 1.0 to 2.34. Reynolds number per foot varied from 0 to 1.4 million. Analysis of the data indicated a maximum static, gross augmentation of 1.53 at a flap angle of 45 degrees. Analysis also indicated that the configuration was an efficient powered lift device and that the net thrust was comparable with augmentor wings of similar static performance. Performance at forward speed was best at a diffuser area ratio of 1.37.

Utilization of Facial Image Analysis Technology for Blink Detection: A Validation Study.

PubMed

Kitazawa, Momoko; Yoshimura, Michitaka; Liang, Kuo-Ching; Wada, Satoshi; Mimura, Masaru; Tsubota, Kazuo; Kishimoto, Taishiro

2018-06-25

The assessment of anterior eye diseases and the understanding of psychological functions of blinking can benefit greatly from a validated blinking detection technology. In this work, we proposed an algorithm based on facial recognition built on current video processing technologies to automatically filter and analyze blinking movements. We compared electrooculography (EOG), the gold standard of blinking measurement, with manual video tape recording counting (mVTRc) and our proposed automated video tape recording analysis (aVTRa) in both static and dynamic conditions to validate our aVTRa method. We measured blinking in both static condition, where the subject was sitting still with chin fixed on the table, and dynamic condition, where the subject's face was not fixed and natural communication was taking place between the subject and interviewer. We defined concordance of blinks between measurement methods as having less than 50 ms difference between eyes opening and closing. The subjects consisted of seven healthy Japanese volunteers (3 male, four female) without significant eye disease with average age of 31.4±7.2. The concordance of EOG vs. aVTRa, EOG vs. mVTRc, and aVTRa vs. mVTRc (average±SD) were found to be 92.2±10.8%, 85.0±16.5%, and 99.6±1.0% in static conditions and 32.6±31.0%, 28.0±24.2%, and 98.5±2.7% in dynamic conditions, respectively. In static conditions, we have found a high blink concordance rate between the proposed aVTRa versus EOG, and confirmed the validity of aVTRa in both static and dynamic conditions.

Level of functional capacities following soccer-specific warm-up methods among elite collegiate soccer players.

PubMed

Vazini Taher, Amir; Parnow, Abdolhossein

2017-05-01

Different methods of warm-up may have implications in improving various aspects of soccer performance. The present study aimed to investigate acute effects of soccer specific warm-up protocols on functional performance tests. This study using randomized within-subject design, investigated the performance of 22 collegiate elite soccer player following soccer specific warm-ups using dynamic stretching, static stretching, and FIFA 11+ program. Post warm-up examinations consisted: 1) Illinois Agility Test; 2) vertical jump; 3) 30 meter sprint; 4) consecutive turns; 5) flexibility of knee. Vertical jump performance was significantly lower following static stretching, as compared to dynamic stretching (P=0.005). Sprint performance declined significantly following static stretching as compared to FIFA 11+ (P=0.023). Agility time was significantly faster following dynamic stretching as compared to FIFA 11+ (P=0.001) and static stretching (P=0.001). Knee flexibility scores were significantly improved following the static stretching as compared to dynamic stretching (P=016). No significant difference was observed for consecutive turns between three warm-up protocol. The present finding showed that a soccer specific warm-up protocol relied on dynamic stretching is preferable in enhancing performance as compared to protocols relying on static stretches and FIFA 11+ program. Investigators suggest that while different soccer specific warm-up protocols have varied types of effects on performance, acute effects of dynamic stretching on performance in elite soccer players are assured, however application of static stretching in reducing muscle stiffness is demonstrated.

Structural integrity of a confinement vessel for testing nuclear fuels for space propulsion

NASA Astrophysics Data System (ADS)

Bergmann, V. L.

Nuclear propulsion systems for rockets could significantly reduce the travel time to distant destinations in space. However, long before such a concept can become reality, a significant effort must be invested in analysis and ground testing to guide the development of nuclear fuels. Any testing in support of development of nuclear fuels for space propulsion must be safely contained to prevent the release of radioactive materials. This paper describes analyses performed to assess the structural integrity of a test confinement vessel. The confinement structure, a stainless steel pressure vessel with bolted flanges, was designed for operating static pressures in accordance with the ASME Boiler and Pressure Vessel Code. In addition to the static operating pressures, the confinement barrier must withstand static overpressures from off-normal conditions without releasing radioactive material. Results from axisymmetric finite element analyses are used to evaluate the response of the confinement structure under design and accident conditions. For the static design conditions, the stresses computed from the ASME code are compared with the stresses computed by the finite element method.

Impaired recognition of body expressions in the behavioral variant of frontotemporal dementia.

PubMed

Van den Stock, Jan; De Winter, François-Laurent; de Gelder, Beatrice; Rangarajan, Janaki Raman; Cypers, Gert; Maes, Frederik; Sunaert, Stefan; Goffin, Karolien; Vandenberghe, Rik; Vandenbulcke, Mathieu

2015-08-01

Progressive deterioration of social cognition and emotion processing are core symptoms of the behavioral variant of frontotemporal dementia (bvFTD). Here we investigate whether bvFTD is also associated with impaired recognition of static (Experiment 1) and dynamic (Experiment 2) bodily expressions. In addition, we compared body expression processing with processing of static (Experiment 3) and dynamic (Experiment 4) facial expressions, as well as with face identity processing (Experiment 5). The results reveal that bvFTD is associated with impaired recognition of static and dynamic bodily and facial expressions, while identity processing was intact. No differential impairments were observed regarding motion (static vs. dynamic) or category (body vs. face). Within the bvFTD group, we observed a significant partial correlation between body and face expression recognition, when controlling for performance on the identity task. Voxel-Based Morphometry (VBM) analysis revealed that body emotion recognition was positively associated with gray matter volume in a region of the inferior frontal gyrus (pars orbitalis/triangularis). The results are in line with a supramodal emotion recognition deficit in bvFTD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dynamic mechanical characterization of aluminum: analysis of strain-rate-dependent behavior

NASA Astrophysics Data System (ADS)

Rahmat, Meysam

2018-05-01

A significant number of materials show different mechanical behavior under dynamic loads compared to quasi-static (Salvado et al. in Prog. Mater. Sci. 88:186-231, 2017). Therefore, a comprehensive study of material dynamic behavior is essential for applications in which dynamic loads are dominant (Li et al. in J. Mater. Process. Technol. 255:373-386, 2018). In this work, aluminum 6061-T6, as an example of ductile alloys with numerous applications including in the aerospace industry, has been studied under quasi-static and dynamic tensile tests with strain rates of up to 156 s^{-1}. Dogbone specimens were designed, instrumented and tested with a high speed servo-hydraulic load frame, and the results were validated with the literature. It was observed that at a strain rate of 156 s^{-1} the yield and ultimate strength increased by 31% and 33% from their quasi-static values, respectively. Moreover, the failure elongation and fracture energy per unit volume also increased by 18% and 52%, respectively. A Johnson-Cook model was used to capture the behavior of the material at different strain rates, and a modified version of this model was presented to enhance the capabilities of the original model, especially in predicting material properties close to the failure point. Finally, the fracture surfaces of specimens tested under quasi-static and dynamic loads were compared and conclusions about the differences were drawn.

Comparison of 3-D Multi-Lag Cross-Correlation and Speckle Brightness Aberration Correction Algorithms on Static and Moving Targets

PubMed Central

Ivancevich, Nikolas M.; Dahl, Jeremy J.; Smith, Stephen W.

2010-01-01

Phase correction has the potential to increase the image quality of 3-D ultrasound, especially transcranial ultrasound. We implemented and compared 2 algorithms for aberration correction, multi-lag cross-correlation and speckle brightness, using static and moving targets. We corrected three 75-ns rms electronic aberrators with full-width at half-maximum (FWHM) auto-correlation lengths of 1.35, 2.7, and 5.4 mm. Cross-correlation proved the better algorithm at 2.7 and 5.4 mm correlation lengths (P < 0.05). Static cross-correlation performed better than moving-target cross-correlation at the 2.7 mm correlation length (P < 0.05). Finally, we compared the static and moving-target cross-correlation on a flow phantom with a skull casting aberrator. Using signal from static targets, the correction resulted in an average contrast increase of 22.2%, compared with 13.2% using signal from moving targets. The contrast-to-noise ratio (CNR) increased by 20.5% and 12.8% using static and moving targets, respectively. Doppler signal strength increased by 5.6% and 4.9% for the static and moving-targets methods, respectively. PMID:19942503

Comparison of 3-D multi-lag cross- correlation and speckle brightness aberration correction algorithms on static and moving targets.

PubMed

Ivancevich, Nikolas M; Dahl, Jeremy J; Smith, Stephen W

2009-10-01

Phase correction has the potential to increase the image quality of 3-D ultrasound, especially transcranial ultrasound. We implemented and compared 2 algorithms for aberration correction, multi-lag cross-correlation and speckle brightness, using static and moving targets. We corrected three 75-ns rms electronic aberrators with full-width at half-maximum (FWHM) auto-correlation lengths of 1.35, 2.7, and 5.4 mm. Cross-correlation proved the better algorithm at 2.7 and 5.4 mm correlation lengths (P < 0.05). Static cross-correlation performed better than moving-target cross-correlation at the 2.7 mm correlation length (P < 0.05). Finally, we compared the static and moving-target cross-correlation on a flow phantom with a skull casting aberrator. Using signal from static targets, the correction resulted in an average contrast increase of 22.2%, compared with 13.2% using signal from moving targets. The contrast-to-noise ratio (CNR) increased by 20.5% and 12.8% using static and moving targets, respectively. Doppler signal strength increased by 5.6% and 4.9% for the static and moving-targets methods, respectively.

Experimental analysis of quasi-static and dynamic fracture initiation toughness of gy4 armor steel material

NASA Astrophysics Data System (ADS)

Ren, Peng; Guo, Zitao

Quasi-static and dynamic fracture initiation toughness of gy4 armour steel material are investigated using three point bend specimen. The modified split Hopkinson pressure bar (SHPB) apparatus with digital image correlation (DIC) system is applied to dynamic loading experiments. Full-field deformation measurements are obtained by using DIC to elucidate on the strain fields associated with the mechanical response. A series of experiments are conducted at different strain rate ranging from 10-3 s-1 to 103 s-1, and the loading rate on the fracture initiation toughness is investigated. Specially, the scanning electron microscope imaging technique is used to investigate the fracture failure micromechanism of fracture surfaces. The gy4 armour steel material fracture toughness is found to be sensitive to strain rate and higher for dynamic loading as compared to quasi-static loading. This work is supported by National Nature Science Foundation under Grant 51509115.

Nonlinear versus Ordinary Adaptive Control of Continuous Stirred-Tank Reactor

PubMed Central

Dostal, Petr

2015-01-01

Unfortunately, the major group of the systems in industry has nonlinear behavior and control of such processes with conventional control approaches with fixed parameters causes problems and suboptimal or unstable control results. An adaptive control is one way to how we can cope with nonlinearity of the system. This contribution compares classic adaptive control and its modification with Wiener system. This configuration divides nonlinear controller into the dynamic linear part and the static nonlinear part. The dynamic linear part is constructed with the use of polynomial synthesis together with the pole-placement method and the spectral factorization. The static nonlinear part uses static analysis of the controlled plant for introducing the mathematical nonlinear description of the relation between the controlled output and the change of the control input. Proposed controller is tested by the simulations on the mathematical model of the continuous stirred-tank reactor with cooling in the jacket as a typical nonlinear system. PMID:26346878

Behavior of plywood and fiberglass steel composite tube structures subjected to impact loading

NASA Astrophysics Data System (ADS)

Armaghani, Seyamend Bilind

Paratransit buses are custom built as the major vehicle manufacturer produces the custom built passenger cage installed on the chassis for the Paratransit bus. In order for these Paratransit bus members to be sufficient, they have to be evaluated for crashworthiness and energy absorption. This has prompted Florida Department of Transportation (FDOT) to fund research for the safety evaluation of Paratransit busses consisting of crash and safety analysis. There has been a large body of research done on steel subjected to static loads, but more research is needed for steel applied under dynamic loading and high speeds in order to improve crashworthiness in events such as rollovers and side impacts. Bare steel Hollow Structural Section (HSS) tubing are used a lot as structural members of Paratransit buses because of their lightness and progressive buckling under loading. The research will be conducted on quantifying the tubing's behavior under bending by conducting static three point bending and impact loading tests. In addition to the bare tubing, plywood and fiberglass composites are investigated because they are both strong and lightweight and their behavior under dynamic loading hasn't been quantified. As a result, the main purpose of this research is to quantify the differences between the dynamic and static behavior of plywood steel composite and fiberglass steel composite tubing and compare these findings with those of bare steel tubing. The differences will be quantified using detailed and thorough experiments that will examine the composites behavior under both static and dynamic loading. These tests will determine if there are any advantages of using the composite materials and thus allow for recommendations to be made to the FDOT with the goal of improving the safety of Paratransit busses. Tensile tests were conducted to determine the material properties of the tested specimens. Before the static and dynamic experiments are run to investigate the differences between static and dynamic behavior, Preliminary three point bending testing was conducted to determine the parameters for the final experiments. Static bending testing was conducted on the bare, plywood composite, and fiberglass composite steel tubing. The point of these experiments was to produce a Moment vs. Rotation plot to determine the specimens' maximum moments and their associated rotation, as that is when the steel buckles and fails. The dynamic three point bending experiments were conducted using the impact loading apparatus and had the same purpose as the static experiments. For both static and dynamic experiments, the performances of the different types of specimens were compared based upon their Moment vs. Rotation plots. This will determine the effect that the composite has on the rotation and maximum moment at which the tubing fails. After conducting these experiments, amplification factors were established for each specimen by comparing the maximum moment and their associated rotation between static and dynamic testing. lambda was calculated to quantify the ratio between the static and dynamic maximum moments. beta was used to quantify the ratio between the rotation needed to produce the maximum moment between static and dynamic events. A small amplification factor denotes that material performs well under impact loading and the material doesn't experience dramatic change in behavior during dynamic events. Amplification factors were compared between the bare, plywood, and fiberglass composite steel tubing in order to evaluate the performance of the composites. After comparing the amplification factors of the different types of tubing, recommendations can be made. Fiberglass and plywood composite were shown to be valuable because it decreased the effect of dynamic forces as beta was reduced by a factor of 2 in comparison to bare tubing. Based upon the amplification factors, it was recommended to use 14 gauge fiberglass composite tubing as Paratransit bus structural members because it was affected the least by dynamic loading.

Embedded data collector (EDC) evaluation, phase II - comparison with instrumented static load tests.

DOT National Transportation Integrated Search

2013-12-01

A total of 139 piles and 213,000 hammer blows were compared between the Embedded Data Collector : (EDC), the Pile Driving Analyzer (PDA), and the CAse Pile Wave Analysis Program (CAPWAP) along with : SmartPile Review versions (3.6, 3.72, 3.73, 3.76 a...

Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system.

PubMed

Hirata, Akimasa; Ito, Fumihiro; Laakso, Ilkka

2013-09-07

The present study discusses the applicability of the magneto-quasi-static approximation to the calculation of the specific absorption rate (SAR) in a cylindrical model for a wireless power transfer system. Resonant coils with different parameters were considered in the 10 MHz band. A two-step quasi-static method that is comprised of the method of moments and the scalar-potential finite-difference methods is applied, which can consider the effects of electric and magnetic fields on the induced SAR separately. From our computational results, the SARs obtained from our quasi-static method are found to be in good agreement with full-wave analysis for different positions of the cylindrical model relative to the wireless power transfer system, confirming the applicability of the quasi-static approximation in the 10 MHz band. The SAR induced by the external electric field is found to be marginal as compared to that induced by the magnetic field. Thus, the dosimetry for the external magnetic field, which may be marginally perturbed by the presence of biological tissue, is confirmed to be essential for SAR compliance in the 10 MHz band or lower. This confirmation also suggests that the current in the coil rather than the transferred power is essential for SAR compliance.

Trajectory Adjustments Underlying Task-Specific Intermittent Force Behaviors and Muscular Rhythms

PubMed Central

Chen, Yi-Ching; Lin, Yen-Ting; Huang, Chien-Ting; Shih, Chia-Li; Yang, Zong-Ru; Hwang, Ing-Shiou

2013-01-01

Force intermittency is one of the major causes of motor variability. Focusing on the dynamics of force intermittency, this study was undertaken to investigate how force trajectory is fine-tuned for static and dynamic force-tracking of a comparable physical load. Twenty-two healthy adults performed two unilateral resistance protocols (static force-tracking at 75% maximal effort and dynamic force-tracking in the range of 50%–100% maximal effort) using the left hand. The electromyographic activity and force profile of the designated hand were monitored. Gripping force was off-line decomposed into a primary movement spectrally identical to the target motion and a force intermittency profile containing numerous force pulses. The results showed that dynamic force-tracking exhibited greater intermittency amplitude and force pulse but a smaller amplitude ratio of primary movement to force intermittency than static force-tracking. Multi-scale entropy analysis revealed that force intermittency during dynamic force-tracking was more complex on a low time scale but more regular on a high time scale than that of static force-tracking. Together with task-dependent force intermittency properties, dynamic force-tracking exhibited a smaller 8–12 Hz muscular oscillation but a more potentiated muscular oscillation at 35–50 Hz than static force-tracking. In conclusion, force intermittency reflects differing trajectory controls for static and dynamic force-tracking. The target goal of dynamic tracking is achieved through trajectory adjustments that are more intricate and more frequent than those of static tracking, pertaining to differing organizations and functioning of muscular oscillations in the alpha and gamma bands. PMID:24098640

A Procedure for Modeling Structural Component/Attachment Failure Using Transient Finite Element Analysis

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Jegley, Dawn C. (Technical Monitor)

2007-01-01

Structures often comprise smaller substructures that are connected to each other or attached to the ground by a set of finite connections. Under static loading one or more of these connections may exceed allowable limits and be deemed to fail. Of particular interest is the structural response when a connection is severed (failed) while the structure is under static load. A transient failure analysis procedure was developed by which it is possible to examine the dynamic effects that result from introducing a discrete failure while a structure is under static load. The failure is introduced by replacing a connection load history by a time-dependent load set that removes the connection load at the time of failure. The subsequent transient response is examined to determine the importance of the dynamic effects by comparing the structural response with the appropriate allowables. Additionally, this procedure utilizes a standard finite element transient analysis that is readily available in most commercial software, permitting the study of dynamic failures without the need to purchase software specifically for this purpose. The procedure is developed and explained, demonstrated on a simple cantilever box example, and finally demonstrated on a real-world example, the American Airlines Flight 587 (AA587) vertical tail plane (VTP).

Assessing validity by comparing transition and static measures of dyspnea in patients with acute decompensated heart failure.

PubMed

Smithline, Howard A; Caglar, Selin; Blank, Fidela S J

2010-01-01

This study assessed the convergent validity of 2 dyspnea measures, the transition measure and the change measure, by comparing them with each other in patients admitted to the hospital with acute decompensated heart failure. Static measures of dyspnea were obtained at baseline (pre-static measure) and at time 1 hour and 4 hour (post-static measures). The change measure was calculated as the difference between the pre-static and post-static measures. Transition measures were obtained at time 1 hour and 4 hour. Visual analog scales and Likert scales were used. Both physicians and patients measured the dyspnea independently. A total of 112 patients had complete data sets at time 0 and 1 hour and 86 patients had complete data sets at all 3 time points. Correlations were calculated between the transition measures and static measures (pre-static, post-static, and change measure). Bland-Altman plots were generated and the mean difference and limits of agreement between the transition measures and the change measures were calculated. In general, short-term dyspnea assessment using transition measures and serial static measures can not be used to validate each other in this population of patients being admitted with acute decompensated heart failure. © 2010 Wiley Periodicals, Inc.

76 FR 28131 - Federal Motor Vehicle Safety Standards; Motorcycle Helmets

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-13

..., this final rule sets a quasi-static load application rate for the helmet retention system; revises the... Analysis and Conclusion e. Quasi-Static Retention Test f. Helmet Conditioning Tolerances g. Other... it as a quasi-static test, instead of a static test. Specifying the application rate will aid...

Comparative analysis of the volatile composition of honeys from Brazilian stingless bees by static headspace GC-MS.

PubMed

de Lima Morais da Silva, Patricia; de Lima, Liliane Schier; Caetano, Ísis Kaminski; Torres, Yohandra Reyes

2017-12-01

The volatile composition of honeys produced by eight species of stingless bees collected in three municipalities in the state of Paraná (Brazil) was compared by combining static headspace GC-MS and chemometrics methods. Forty-four compounds were identified using NIST library and linear retention index relative to n-alkanes (C 8 -C 40 ). Linalool derivatives were the most abundant peaks in most honeys regardless geographical or entomological origin. However, Principal Component Analysis discriminated honeys from different geographical origins considering their distinctive minor volatile components. Honey samples from Guaraqueçaba were characterized by the presence of hotrienol while those from Cambará showed epoxylinalol, benzaldehyde and TDN as minor discriminating compounds. Punctual species such as Borá showed similar fingerprints regardless geographical origin, with ethyl octanoate and ethyl decanoate as characteristic intense chromatographic peaks, which may suggest a specialized behavior for nectar collection. Discriminant Analysis allowed correct geographic discrimination of most honeys produced in the three spots tested. We concluded that volatile profile of stingless bee honeys can be used to attest authenticity related to regional origin of honeys. Copyright © 2017. Published by Elsevier Ltd.

Gravity Tides Extracted from Relative Gravimeter Data by Combining Empirical Mode Decomposition and Independent Component Analysis

NASA Astrophysics Data System (ADS)

Yu, Hongjuan; Guo, Jinyun; Kong, Qiaoli; Chen, Xiaodong

2018-04-01

The static observation data from a relative gravimeter contain noise and signals such as gravity tides. This paper focuses on the extraction of the gravity tides from the static relative gravimeter data for the first time applying the combined method of empirical mode decomposition (EMD) and independent component analysis (ICA), called the EMD-ICA method. The experimental results from the CG-5 gravimeter (SCINTREX Limited Ontario Canada) data show that the gravity tides time series derived by EMD-ICA are consistent with the theoretical reference (Longman formula) and the RMS of their differences only reaches 4.4 μGal. The time series of the gravity tides derived by EMD-ICA have a strong correlation with the theoretical time series and the correlation coefficient is greater than 0.997. The accuracy of the gravity tides estimated by EMD-ICA is comparable to the theoretical model and is slightly higher than that of independent component analysis (ICA). EMD-ICA could overcome the limitation of ICA having to process multiple observations and slightly improve the extraction accuracy and reliability of gravity tides from relative gravimeter data compared to that estimated with ICA.

Missing value imputation: with application to handwriting data

NASA Astrophysics Data System (ADS)

Xu, Zhen; Srihari, Sargur N.

2015-01-01

Missing values make pattern analysis difficult, particularly with limited available data. In longitudinal research, missing values accumulate, thereby aggravating the problem. Here we consider how to deal with temporal data with missing values in handwriting analysis. In the task of studying development of individuality of handwriting, we encountered the fact that feature values are missing for several individuals at several time instances. Six algorithms, i.e., random imputation, mean imputation, most likely independent value imputation, and three methods based on Bayesian network (static Bayesian network, parameter EM, and structural EM), are compared with children's handwriting data. We evaluate the accuracy and robustness of the algorithms under different ratios of missing data and missing values, and useful conclusions are given. Specifically, static Bayesian network is used for our data which contain around 5% missing data to provide adequate accuracy and low computational cost.

An assessment of gains and losses from international trade in the forest sector

Treesearch

Joseph Buongiorno; Craig Johnston; Shushuai Zhu

2017-01-01

The importance of international trade for the welfare of actors in the forest sector was estimated by comparing the current state of the world with a world in pure autarky with zero imports and exports of roundwood and manufactured wood products. The analysis was done with a comparative statics application of the Global Forest Products Model. The model was first...

Theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains

NASA Astrophysics Data System (ADS)

Zhu, Ning; Sun, Shou-Guang; Li, Qiang; Zou, Hua

2014-12-01

One of the major problems in structural fatigue life analysis is establishing structural load spectra under actual operating conditions. This study conducts theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains. The quasistatic load series that corresponds to quasi-static deformation modes are identified according to the structural form and bearing conditions of high-speed train bogie frames. Moreover, a force-measuring frame is designed and manufactured based on the quasi-static load series. The load decoupling model of the quasi-static load series is then established via calibration tests. Quasi-static load-time histories, together with online tests and decoupling analysis, are obtained for the intermediate range of the Beijing—Shanghai dedicated passenger line. The damage consistency calibration of the quasi-static discrete load spectra is performed according to a damage consistency criterion and a genetic algorithm. The calibrated damage that corresponds with the quasi-static discrete load spectra satisfies the safety requirements of bogie frames.

In vitro evaluation of stiffness and load sharing in a two-level corpectomy: comparison of static and dynamic cervical plates.

PubMed

Fogel, Guy R; Li, Zhenyu; Liu, Weiqiang; Liao, Zhenhua; Wu, Jia; Zhou, Wenyu

2010-05-01

Anterior cervical plating has been accepted in corpectomy and fusion of the cervical spine. Constrained plates were criticized for stress shielding that may lead to subsidence and pseudarthrosis. A dynamic plate allows load sharing as the graft subsides. Ideally, the dynamic plate design should maintain adequate stiffness of the construct while providing a reasonable load sharing with the strut graft. The purpose of the study was to compare dynamic and static plate kinematics with graft subsidence. The study designed was an in vitro biomechanical study in a porcine cervical spine model. Twelve spines were initially tested in intact condition with 20-N axial load in 15 degrees of flexion and extension range of motion (ROM). Then, a two-level corpectomy was created in all specimens with spines randomized to receive either a static or dynamic plate. The spines were retested under identical conditions with optimal length and undersized graft. Range of motion and graft loading were analyzed with a one-way analysis of variance (p<.05). Both plates significantly limited ROM compared with the intact spine in both graft length conditions. In extension graft, load was significantly higher (p=.001) in the static plate with optimal length, and in flexion, there was a significant loss of graft load (p=.0004). In flexion, the dynamic plate with undersized graft demonstrated significantly more load sustained (p=.0004). Both plates reasonably limited the ROM of the corpectomy. The static plate had significantly higher graft loads in extension and significant loss of graft load in flexion, whereas the dynamic plate maintained a reasonable graft load in ROM even when graft contact was imperfect. Copyright 2010 Elsevier Inc. All rights reserved.

Static γ-motoneurones couple group Ia and II afferents of single muscle spindles in anaesthetised and decerebrate cats

PubMed Central

Gladden, M H; Matsuzaki, H

2002-01-01

Ideas about the functions of static γ-motoneurones are based on the responses of primary and secondary endings to electrical stimulation of single static γ-axons, usually at high frequencies. We compared these effects with the actions of spontaneously active γ-motoneurones. In anaesthetised cats, afferents and efferents were recorded in intramuscular nerve branches to single muscle spindles. The occurrence of γ-spikes, identified by a spike shape recognition system, was linked to video-taped contractions of type-identified intrafusal fibres in the dissected muscle spindles. When some static γ-motoneurones were active at low frequency (< 15 Hz) they coupled the firing of group Ia and II afferents. Activity of other static γ-motoneurones which tensed the intrafusal fibres appeared to enhance this effect. Under these conditions the secondary ending responded at shorter latency than the primary ending. In another series of experiments on decerebrate cats, responses of primary and secondary endings of single muscle spindles to activation of γ-motoneurones by natural stimuli were compared with their responses to electrical stimulation of single γ-axons supplying the same spindle. Electrical stimulation mimicked the natural actions of γ-motoneurones on either the primary or the secondary ending, but not on both together. However, γ-activity evoked by natural stimuli coupled the firing of afferents with the muscle at constant length, and also when it was stretched. Analysis showed that the timing and tightness of this coupling determined the degree of summation of excitatory postsynaptic potentials (EPSPs) evoked by each afferent in α-motoneurones and interneurones contacted by terminals of both endings, and thus the degree of facilitation of reflex actions of group II afferents. PMID:12181298

Static postural control among school-aged youth with Down syndrome: A systematic review.

PubMed

Maïano, Christophe; Hue, Olivier; Tracey, Danielle; Lepage, Geneviève; Morin, Alexandre J S; Moullec, Grégory

2018-05-01

Youth with Down syndrome are characterized by motor delays when compared to typically developing (TD) youth, which may be explained by a lower postural control or reduced postural tone. In the present article, we summarize research comparing the static postural control, assessed by posturography, between youth with Down syndrome and TD youth. A systematic literature search was performed in 10 databases and seven studies, published between 2001 and 2017, met our inclusion criteria. Based on the present reviewed findings, it is impossible to conclude that children with Down syndrome present significantly lower static postural control compared to TD children. In contrast, findings showed that adolescents with Down syndrome tended to present significantly lower static postural control compared to TD adolescents when visual and plantar cutaneous inputs were disturbed separately or simultaneously. The present findings should be interpreted with caution given the limitations of the small number of reviewed studies. Therefore, the static postural control among youth with Down syndrome should be further investigated in future rigorous studies examining the contribution of a range of sensory information. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of Wind Tunnel Oscillatory Data of the X-31A Aircraft

NASA Technical Reports Server (NTRS)

Smith, Mark S.

1999-01-01

Wind tunnel oscillatory tests in pitch, roll, and yaw were performed on a 19%-scale model of the X-31A aircraft. These tests were used to study the aerodynamic characteristics of the X-31A in response to harmonic oscillations at six frequencies. In-phase and out-of-phase components of the aerodynamic coefficients were obtained over a range of angles of attack from 0 to 90 deg. To account for the effect of frequency on the data, mathematical models with unsteady terms were formulated by use of two different indicial functions. Data from a reduced set of frequencies were used to estimate model parameters, including steady-state static and dynamic stability derivatives. Both models showed good prediction capability and the ability to accurately fit the measured data. Estimated static stability derivatives compared well with those obtained from static wind tunnel tests. The roll and yaw rate derivative estimates were compared with rotary-balanced wind tunnel data and theoretical predictions. The estimates and theoretical predictions were in agreement at small angles of attack. The rotary-balance data showed, in general, acceptable agreement with the steady-state derivative estimates.

Analysis of Pull-In Instability of Geometrically Nonlinear Microbeam Using Radial Basis Artificial Neural Network Based on Couple Stress Theory

PubMed Central

Heidari, Mohammad; Heidari, Ali; Homaei, Hadi

2014-01-01

The static pull-in instability of beam-type microelectromechanical systems (MEMS) is theoretically investigated. Two engineering cases including cantilever and double cantilever microbeam are considered. Considering the midplane stretching as the source of the nonlinearity in the beam behavior, a nonlinear size-dependent Euler-Bernoulli beam model is used based on a modified couple stress theory, capable of capturing the size effect. By selecting a range of geometric parameters such as beam lengths, width, thickness, gaps, and size effect, we identify the static pull-in instability voltage. A MAPLE package is employed to solve the nonlinear differential governing equations to obtain the static pull-in instability voltage of microbeams. Radial basis function artificial neural network with two functions has been used for modeling the static pull-in instability of microcantilever beam. The network has four inputs of length, width, gap, and the ratio of height to scale parameter of beam as the independent process variables, and the output is static pull-in voltage of microbeam. Numerical data, employed for training the network, and capabilities of the model have been verified in predicting the pull-in instability behavior. The output obtained from neural network model is compared with numerical results, and the amount of relative error has been calculated. Based on this verification error, it is shown that the radial basis function of neural network has the average error of 4.55% in predicting pull-in voltage of cantilever microbeam. Further analysis of pull-in instability of beam under different input conditions has been investigated and comparison results of modeling with numerical considerations shows a good agreement, which also proves the feasibility and effectiveness of the adopted approach. The results reveal significant influences of size effect and geometric parameters on the static pull-in instability voltage of MEMS. PMID:24860602

Static aeroelastic analysis and tailoring of a single-element racing car wing

NASA Astrophysics Data System (ADS)

Sadd, Christopher James

This thesis presents the research from an Engineering Doctorate research programme in collaboration with Reynard Motorsport Ltd, a manufacturer of racing cars. Racing car wing design has traditionally considered structures to be rigid. However, structures are never perfectly rigid and the interaction between aerodynamic loading and structural flexibility has a direct impact on aerodynamic performance. This interaction is often referred to as static aeroelasticity and the focus of this research has been the development of a computational static aeroelastic analysis method to improve the design of a single-element racing car wing. A static aeroelastic analysis method has been developed by coupling a Reynolds-Averaged Navier-Stokes CFD analysis method with a Finite Element structural analysis method using an iterative scheme. Development of this method has included assessment of CFD and Finite Element analysis methods and development of data transfer and mesh deflection methods. Experimental testing was also completed to further assess the computational analyses. The computational and experimental results show a good correlation and these studies have also shown that a Navier-Stokes static aeroelastic analysis of an isolated wing can be performed at an acceptable computational cost. The static aeroelastic analysis tool was used to assess methods of tailoring the structural flexibility of the wing to increase its aerodynamic performance. These tailoring methods were then used to produce two final wing designs to increase downforce and reduce drag respectively. At the average operating dynamic pressure of the racing car, the computational analysis predicts that the downforce-increasing wing has a downforce of C[1]=-1.377 in comparison to C[1]=-1.265 for the original wing. The computational analysis predicts that the drag-reducing wing has a drag of C[d]=0.115 in comparison to C[d]=0.143 for the original wing.

Results of application of automatic computation of static corrections on data from the South Banat Terrain

NASA Astrophysics Data System (ADS)

Milojević, Slavka; Stojanovic, Vojislav

2017-04-01

Due to the continuous development of the seismic acquisition and processing method, the increase of the signal/fault ratio always represents a current target. The correct application of the latest software solutions improves the processing results and justifies their development. A correct computation and application of static corrections represents one of the most important tasks in pre-processing. This phase is of great importance for further processing steps. Static corrections are applied to seismic data in order to compensate the effects of irregular topography, the difference between the levels of source points and receipt in relation to the level of reduction, of close to the low-velocity surface layer (weathering correction), or any reasons that influence the spatial and temporal position of seismic routes. The refraction statics method is the most common method for computation of static corrections. It is successful in resolving of both the long-period statics problems and determining of the difference in the statics caused by abrupt lateral changes in velocity in close to the surface layer. XtremeGeo FlatironsTM is a program whose main purpose is computation of static correction through a refraction statics method and allows the application of the following procedures: picking of first arrivals, checking of geometry, multiple methods for analysis and modelling of statics, analysis of the refractor anisotropy and tomography (Eikonal Tomography). The exploration area is located on the southern edge of the Pannonian Plain, in the plain area with altitudes of 50 to 195 meters. The largest part of the exploration area covers Deliblato Sands, where the geological structure of the terrain and high difference in altitudes significantly affects the calculation of static correction. Software XtremeGeo FlatironsTM has powerful visualization and tools for statistical analysis which contributes to significantly more accurate assessment of geometry close to the surface layers and therefore more accurately computed static corrections.

Static and Completion Analysis for Planning Knowledge Base Development and Verification

NASA Technical Reports Server (NTRS)

Chien, Steve A.

1996-01-01

A key obstacle hampering fielding of AI planning applications is the considerable expense of developing, verifying, updating, and maintaining the planning knowledge base (KB). Planning systems must be able to compare favorably in terms of software lifecycle costs to other means of automation such as scripts or rule-based expert systems.

Standing Postural Control in Individuals with Autism Spectrum Disorder: Systematic Review and Meta-Analysis

ERIC Educational Resources Information Center

Lim, Yi Huey; Partridge, Katie; Girdler, Sonya; Morris, Susan L.

2017-01-01

Impairments in postural control affect the development of motor and social skills in individuals with autism spectrum disorder (ASD). This review compared the effect of different sensory conditions on static standing postural control between ASD and neurotypical individuals. Results from 19 studies indicated a large difference in postural control…

Static stretching vs. dynamic warm-ups: a comparison of their effects on torque and electromyography output of the quadriceps and hamstring muscles.

PubMed

Williams, N; Coburn, J; Gillum, T

2015-11-01

The aim of this paper was to determine if two different warm-up protocols differently affect torque of the quadriceps and hamstrings, and electromyography (EMG) output of the rectus femoris (RF) and vastus lateralis (VL) when completing 30 maximal leg extensions and curls. Twenty-one healthy male (N.=8) and female (N.=13) subjects volunteered to participate in a familiarization session and three testing sessions. The three testing sessions control, dynamic, and static were completed in a counterbalanced order on non-consecutive days. First, subjects warmed-up on a treadmill for five minutes before completing six dynamic movements, six static-stretches, or no stretches. They then rested for five minutes before completing 30 maximal leg extensions and curls at a speed of 60 s-1. A significant decrease in quadriceps torque output over time was determined for the dynamic protocol when compared to the control (P<0.01) and static (P<0.05) protocols. A significant decrease was found in peak quadriceps torque for the dynamic protocol (P<0.01) when compared to the static, and a significant increase was found for the static protocol (P<0.05) when compared to the control. A significant decrease in average quadriceps torque was found for the dynamic protocol when compared to the static (P<0.05) and control (P<0.01) protocols. No difference was found in hamstring torque or EMG output of the RF and VL. Short duration static-stretching has the ability to increase peak and average torque of the leg extensors, while some types of anaerobic exercise involving maximal contractions to fatigue may be hindered by performing dynamic movements as part of the warm-up.

Experimental study on energy absorption of foam filled kraft paper honeycomb subjected to quasi-static uniform compression loading

NASA Astrophysics Data System (ADS)

Abd Kadir, N.; Aminanda, Y.; Ibrahim, M. S.; Mokhtar, H.

2016-10-01

A statistical analysis was performed to evaluate the effect of factor and to obtain the optimum configuration of Kraft paper honeycomb. The factors considered in this study include density of paper, thickness of paper and cell size of honeycomb. Based on three level factorial design, two-factor interaction model (2FI) was developed to correlate the factors with specific energy absorption and specific compression strength. From the analysis of variance (ANOVA), the most influential factor on responses and the optimum configuration was identified. After that, Kraft paper honeycomb with optimum configuration is used to fabricate foam-filled paper honeycomb with five different densities of polyurethane foam as filler (31.8, 32.7, 44.5, 45.7, 52 kg/m3). The foam-filled paper honeycomb is subjected to quasi-static compression loading. Failure mechanism of the foam-filled honeycomb was identified, analyzed and compared with the unfilled paper honeycomb. The peak force and energy absorption capability of foam-filled paper honeycomb are increased up to 32% and 30%, respectively, compared to the summation of individual components.

Acceleration of a Static Observer Near the Event Horizon of a Static Isolated Black Hole.

ERIC Educational Resources Information Center

Doughty, Noel A.

1981-01-01

Compares the magnitude of the proper acceleration of a static observer in a static, isolated, spherically symmetric space-time region with the Newtonian result including the situation in the interior of a perfect-fluid star. This provides a simple physical interpretation of surface gravity and illustrates the global nature of the event horizon.…

Sawja: Static Analysis Workshop for Java

NASA Astrophysics Data System (ADS)

Hubert, Laurent; Barré, Nicolas; Besson, Frédéric; Demange, Delphine; Jensen, Thomas; Monfort, Vincent; Pichardie, David; Turpin, Tiphaine

Static analysis is a powerful technique for automatic verification of programs but raises major engineering challenges when developing a full-fledged analyzer for a realistic language such as Java. Efficiency and precision of such a tool rely partly on low level components which only depend on the syntactic structure of the language and therefore should not be redesigned for each implementation of a new static analysis. This paper describes the Sawja library: a static analysis workshop fully compliant with Java 6 which provides OCaml modules for efficiently manipulating Java bytecode programs. We present the main features of the library, including i) efficient functional data-structures for representing a program with implicit sharing and lazy parsing, ii) an intermediate stack-less representation, and iii) fast computation and manipulation of complete programs. We provide experimental evaluations of the different features with respect to time, memory and precision.

Quantifying hypoxia in human cancers using static PET imaging.

PubMed

Taylor, Edward; Yeung, Ivan; Keller, Harald; Wouters, Bradley G; Milosevic, Michael; Hedley, David W; Jaffray, David A

2016-11-21

Compared to FDG, the signal of 18 F-labelled hypoxia-sensitive tracers in tumours is low. This means that in addition to the presence of hypoxic cells, transport properties contribute significantly to the uptake signal in static PET images. This sensitivity to transport must be minimized in order for static PET to provide a reliable standard for hypoxia quantification. A dynamic compartmental model based on a reaction-diffusion formalism was developed to interpret tracer pharmacokinetics and applied to static images of FAZA in twenty patients with pancreatic cancer. We use our model to identify tumour properties-well-perfused without substantial necrosis or partitioning-for which static PET images can reliably quantify hypoxia. Normalizing the measured activity in a tumour voxel by the value in blood leads to a reduction in the sensitivity to variations in 'inter-corporal' transport properties-blood volume and clearance rate-as well as imaging study protocols. Normalization thus enhances the correlation between static PET images and the FAZA binding rate K 3 , a quantity which quantifies hypoxia in a biologically significant way. The ratio of FAZA uptake in spinal muscle and blood can vary substantially across patients due to long muscle equilibration times. Normalized static PET images of hypoxia-sensitive tracers can reliably quantify hypoxia for homogeneously well-perfused tumours with minimal tissue partitioning. The ideal normalizing reference tissue is blood, either drawn from the patient before PET scanning or imaged using PET. If blood is not available, uniform, homogeneously well-perfused muscle can be used. For tumours that are not homogeneously well-perfused or for which partitioning is significant, only an analysis of dynamic PET scans can reliably quantify hypoxia.

The impact of dynamic balance measures on walking performance in multiple sclerosis

PubMed Central

Fritz, Nora E.; Marasigan, Rhul Evans R.; Calabresi, Peter A.; Newsome, Scott D.; Zackowski, Kathleen M.

2014-01-01

Background Static posture imbalance and gait dysfunction are common in individuals with multiple sclerosis (MS). Although the impact of strength and static balance on walking has been examined, little is known about the impact of dynamic standing balance on walking in MS. Objective To determine the impact of dynamic balance, static balance, sensation, and strength measures to walking in individuals with MS. Methods 52 individuals with MS (27 females; 26 relapsing-remitting; mean age 45.6±10.3 years; median EDSS 3.5 (range 0-7) participated in testing for dynamic and static posturography (Kistler 9281 force plate), hip flexion, hip extension, and ankle dorsiflexion strength (Microfet2 hand-held dynamometer), sensation (Vibratron II) and walk velocity (Optotrak Motion Analysis System). Mann-Whitney tests, Spearman correlation coefficients, and forward stepwise multiple regression were used to assess statistical significance. Results All measures were significantly abnormal in MS subjects when compared to age and sex-matched norms (p<0.05 for all). Static balance (eyes open, feet together [EOFT]), anterior- posterior (AP) dynamic sway, and hip extension strength were strongly correlated with fast walking velocity (AP sway r=0.68; hip extension strength r=0.73; EOFT r=-0.40). Together, AP dynamic sway (ρr=0.71, p<0.001), hip extension strength (ρr=0.54, p<0.001), and EOFT static balance (ρr=-0.41, p=0.01) explained more than 70% of the variance in fast walking velocity (p<0.001). Conclusions These data suggest that AP dynamic sway impacts walking performance in MS. A combined evaluation of dynamic balance, static balance and strength may lead to a better understanding of walking mechanisms as well as the development of strategies to improve walking. PMID:24795162

Clinical Phenotype Classifications Based on Static Varus Alignment and Varus Thrust in Japanese Patients With Medial Knee Osteoarthritis

PubMed Central

Iijima, Hirotaka; Fukutani, Naoto; Fukumoto, Takahiko; Uritani, Daisuke; Kaneda, Eishi; Ota, Kazuo; Kuroki, Hiroshi; Matsuda, Shuichi

2015-01-01

Objective To investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA). Methods Patients in an orthopedic clinic (n = 266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n = 173), dynamic varus (n = 17), static varus (n = 50), and static varus + dynamic varus (n = 26). The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity. Results Multiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08–12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19–320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results. Conclusion Varus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA. PMID:26017348

Quantifying hypoxia in human cancers using static PET imaging

NASA Astrophysics Data System (ADS)

Taylor, Edward; Yeung, Ivan; Keller, Harald; Wouters, Bradley G.; Milosevic, Michael; Hedley, David W.; Jaffray, David A.

2016-11-01

Compared to FDG, the signal of 18F-labelled hypoxia-sensitive tracers in tumours is low. This means that in addition to the presence of hypoxic cells, transport properties contribute significantly to the uptake signal in static PET images. This sensitivity to transport must be minimized in order for static PET to provide a reliable standard for hypoxia quantification. A dynamic compartmental model based on a reaction-diffusion formalism was developed to interpret tracer pharmacokinetics and applied to static images of FAZA in twenty patients with pancreatic cancer. We use our model to identify tumour properties—well-perfused without substantial necrosis or partitioning—for which static PET images can reliably quantify hypoxia. Normalizing the measured activity in a tumour voxel by the value in blood leads to a reduction in the sensitivity to variations in ‘inter-corporal’ transport properties—blood volume and clearance rate—as well as imaging study protocols. Normalization thus enhances the correlation between static PET images and the FAZA binding rate K 3, a quantity which quantifies hypoxia in a biologically significant way. The ratio of FAZA uptake in spinal muscle and blood can vary substantially across patients due to long muscle equilibration times. Normalized static PET images of hypoxia-sensitive tracers can reliably quantify hypoxia for homogeneously well-perfused tumours with minimal tissue partitioning. The ideal normalizing reference tissue is blood, either drawn from the patient before PET scanning or imaged using PET. If blood is not available, uniform, homogeneously well-perfused muscle can be used. For tumours that are not homogeneously well-perfused or for which partitioning is significant, only an analysis of dynamic PET scans can reliably quantify hypoxia.

Evolution of brain-body allometry in Lake Tanganyika cichlids.

PubMed

Tsuboi, Masahito; Kotrschal, Alexander; Hayward, Alexander; Buechel, Severine Denise; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

2016-07-01

Brain size is strongly associated with body size in all vertebrates. This relationship has been hypothesized to be an important constraint on adaptive brain size evolution. The essential assumption behind this idea is that static (i.e., within species) brain-body allometry has low ability to evolve. However, recent studies have reported mixed support for this view. Here, we examine brain-body static allometry in Lake Tanganyika cichlids using a phylogenetic comparative framework. We found considerable variation in the static allometric intercept, which explained the majority of variation in absolute and relative brain size. In contrast, the slope of the brain-body static allometry had relatively low variation, which explained less variation in absolute and relative brain size compared to the intercept and body size. Further examination of the tempo and mode of evolution of static allometric parameters confirmed these observations. Moreover, the estimated evolutionary parameters indicate that the limited observed variation in the static allometric slope could be a result of strong stabilizing selection. Overall, our findings suggest that the brain-body static allometric slope may represent an evolutionary constraint in Lake Tanganyika cichlids. © 2016 The Author(s).

Analysis of the behavior of a wiper blade around the reversal in consideration of dynamic and static friction

NASA Astrophysics Data System (ADS)

Unno, M.; Shibata, A.; Yabuno, H.; Yanagisawa, D.; Nakano, T.

2017-04-01

Reducing noise generated by automobile windshield wipers during reversals is a desirable feature. For this purpose, details of the behavior of the wiper blade need to be ascertained. In this study, we present theoretical and experimental clarification of this behavior during reversals. Using simulation algorithms to consider exactly the effects of dynamic and static friction, we determined theoretical predictions for the vibrational response caused by friction and the response frequency and compared these results with experimental ones obtained from a mock-up incorporating an actual wiper blade. We introduce an analytical link model with two degrees of freedom and consider two types of states at the blade tip. In the stick and the slip states, static friction and dynamic friction, respectively, act on the blade tip. In the theoretical approach, the static friction is expressed by a set-valued function. The transition between the two states is repeated and an evaluation of an exact transition time leads to an accurate prediction of the behavior of the wiper system. In the analysis, the slack variable method is used to find the exact transition time. Assuming low blade speeds during reversal, a parameter study indicates that the blade tip transitions between slip and stick states and the frequency of the vibration caused by this transitions is close to the natural frequency of the neck of the wiper blade. The theoretical predictions are in good agreement with experimental observations.

The acute effects of a warm-up including static or dynamic stretching on countermovement jump height, reaction time, and flexibility.

PubMed

Perrier, Erica T; Pavol, Michael J; Hoffman, Mark A

2011-07-01

The purpose of this research was to compare the effects of a warm-up with static vs. dynamic stretching on countermovement jump (CMJ) height, reaction time, and low-back and hamstring flexibility and to determine whether any observed performance deficits would persist throughout a series of CMJs. Twenty-one recreationally active men (24.4 ± 4.5 years) completed 3 data collection sessions. Each session included a 5-minute treadmill jog followed by 1 of the stretch treatments: no stretching (NS), static stretching (SS), or dynamic stretching (DS). After the jog and stretch treatment, the participant performed a sit-and-reach test. Next, the participant completed a series of 10 maximal-effort CMJs, during which he was asked to jump as quickly as possible after seeing a visual stimulus (light). The CMJ height and reaction time were determined from measured ground reaction forces. A treatment × jump repeated-measures analysis of variance for CMJ height revealed a significant main effect of treatment (p = 0.004). The CMJ height was greater for DS (43.0 cm) than for NS (41.4 cm) and SS (41.9 cm) and was not less for SS than for NS. Analysis also revealed a significant main effect of jump (p = 0.005) on CMJ height: Jump height decreased from the early to the late jumps. The analysis of reaction time showed no significant effect of treatment. Treatment had a main effect (p < 0.001) on flexibility, however. Flexibility was greater after both SS and DS compared to after NS, with no difference in flexibility between SS and DS. Athletes in sports requiring lower-extremity power should use DS techniques in warm-up to enhance flexibility while improving performance.

Effect of Ankle Range of Motion (ROM) and Lower-Extremity Muscle Strength on Static Balance Control Ability in Young Adults: A Regression Analysis

PubMed Central

Kim, Seong-Gil

2018-01-01

Background The purpose of this study was to investigate the effect of ankle ROM and lower-extremity muscle strength on static balance control ability in young adults. Material/Methods This study was conducted with 65 young adults, but 10 young adults dropped out during the measurement, so 55 young adults (male: 19, female: 36) completed the study. Postural sway (length and velocity) was measured with eyes open and closed, and ankle ROM (AROM and PROM of dorsiflexion and plantarflexion) and lower-extremity muscle strength (flexor and extensor of hip, knee, and ankle joint) were measured. Pearson correlation coefficient was used to examine the correlation between variables and static balance ability. Simple linear regression analysis and multiple linear regression analysis were used to examine the effect of variables on static balance ability. Results In correlation analysis, plantarflexion ROM (AROM and PROM) and lower-extremity muscle strength (except hip extensor) were significantly correlated with postural sway (p<0.05). In simple correlation analysis, all variables that passed the correlation analysis procedure had significant influence (p<0.05). In multiple linear regression analysis, plantar flexion PROM with eyes open significantly influenced sway length (B=0.681) and sway velocity (B=0.011). Conclusions Lower-extremity muscle strength and ankle plantarflexion ROM influenced static balance control ability, with ankle plantarflexion PROM showing the greatest influence. Therefore, both contractile structures and non-contractile structures should be of interest when considering static balance control ability improvement. PMID:29760375

Effect of Ankle Range of Motion (ROM) and Lower-Extremity Muscle Strength on Static Balance Control Ability in Young Adults: A Regression Analysis.

PubMed

Kim, Seong-Gil; Kim, Wan-Soo

2018-05-15

BACKGROUND The purpose of this study was to investigate the effect of ankle ROM and lower-extremity muscle strength on static balance control ability in young adults. MATERIAL AND METHODS This study was conducted with 65 young adults, but 10 young adults dropped out during the measurement, so 55 young adults (male: 19, female: 36) completed the study. Postural sway (length and velocity) was measured with eyes open and closed, and ankle ROM (AROM and PROM of dorsiflexion and plantarflexion) and lower-extremity muscle strength (flexor and extensor of hip, knee, and ankle joint) were measured. Pearson correlation coefficient was used to examine the correlation between variables and static balance ability. Simple linear regression analysis and multiple linear regression analysis were used to examine the effect of variables on static balance ability. RESULTS In correlation analysis, plantarflexion ROM (AROM and PROM) and lower-extremity muscle strength (except hip extensor) were significantly correlated with postural sway (p<0.05). In simple correlation analysis, all variables that passed the correlation analysis procedure had significant influence (p<0.05). In multiple linear regression analysis, plantar flexion PROM with eyes open significantly influenced sway length (B=0.681) and sway velocity (B=0.011). CONCLUSIONS Lower-extremity muscle strength and ankle plantarflexion ROM influenced static balance control ability, with ankle plantarflexion PROM showing the greatest influence. Therefore, both contractile structures and non-contractile structures should be of interest when considering static balance control ability improvement.

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

NASA Astrophysics Data System (ADS)

Rodi, A. R.; Leon, D. C.

2012-05-01

Geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft - a "trailing cone" - in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

PubMed Central

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2013-01-01

The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. −1.45%, p < 0.001), RF (37.5% vs. −8.33%, p < 0.001), VM (12% vs. −12%, p < 0.018), and VL EMG activity (20% vs. −6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching. PMID:24511339

Cyclic fatigue resistance of ProTaper Universal instruments when subjected to static and dynamic tests.

PubMed

Lopes, Hélio P; Britto, Izabelle M O; Elias, Carlos N; Machado de Oliveira, Julio C; Neves, Mônica A S; Moreira, Edson J L; Siqueira, José F

2010-09-01

This study evaluated the number of cycles to fracture of ProTaper Universal S2 instruments when subjected to static and dynamic cyclic fatigue tests. ProTaper Universal S2 instruments were used until fracture in an artificial curved canal under rotational speed of 300 rpm in either a static or a dynamic test model. Afterward, the length of the fractured segments was measured and fractured surfaces and helical shafts analyzed by scanning electron microscopy (SEM). The number of cycles to fracture was significantly increased when instruments were tested in the dynamic model (P<.001). Instrument separation occurred at the point of maximum flexure within the artificial canals, i.e., the midpoint of the curved canal segment. SEM analysis revealed that fractured surfaces exhibited characteristics of the ductile mode. Plastic deformation was not observed in the helical shaft of fractured instruments. The number of cycles to fracture ProTaper Universal S2 instruments significantly increased with the use of instruments in a dynamic cyclic fatigue test compared with a static model. These findings reinforce the need for performing continuous pecking motions during rotary instrumentation of curved root canals. Copyright (c) 2010 Mosby, Inc. All rights reserved.

Static and Vibration Analyses of General Wing Structures Using Equivalent Plate Models

NASA Technical Reports Server (NTRS)

Kapania, Rakesh K.; Liu, Youhua

1999-01-01

An efficient method, using equivalent plate model, is developed for studying the static and vibration analyses of general built-up wing structures composed of skins, spars, and ribs. The model includes the transverse shear effects by treating the built-up wing as a plate following the Reissner-Mindlin theory, the so-called First-order Shear Deformation Theory (FSDT). The Ritz method is used with the Legendre polynomials being employed as the trial functions. This is in contrast to previous equivalent plate model methods which have used simple polynomials, known to be prone to numerical ill-conditioning, as the trial functions. The present developments are evaluated by comparing the results with those obtained using MSC/NASTRAN, for a set of examples. These examples are: (i) free-vibration analysis of a clamped trapezoidal plate with (a) uniform thickness, and (b) non-uniform thickness varying as an airfoil, (ii) free-vibration and static analyses (including skin stress distribution) of a general built-up wing, and (iii) free-vibration and static analyses of a swept-back box wing. The results obtained by the present equivalent plate model are in good agreement with those obtained by the finite element method.

Parametric analysis of swept-wing geometry with sheared wing tips

NASA Technical Reports Server (NTRS)

Fremaux, C. M.; Vijgen, P. M. H. W.; Van Dam, C. P.

1990-01-01

A computational parameter study is presented of potential reductions in induced drag and increases in lateral-directional stability due to sheared wing tips attached to an untwisted wing of moderate sweep and aspect ratio. Sheared tips are swept and tapered wing-tip devices mounted in the plane of the wing. The induced-drag results are obtained using an inviscid, incompressible surface-panel method that models the nonlinear effects due to the deflected and rolled-up wake behind the lifting surface. The induced-drag results with planar sheared tips are compared to straight-tapered tip extensions and nonplanar winglet geometries. The lateral-directional static-stability characteristics of the wing with sheared tips are estimated using a quasi-vortex-lattice method. For certain combinations of sheared-tip sweep and taper, both the induced efficiency of the wing and the relevant static-stability derivatives are predicted to increase compared to the wing with a straight-tapered tip modification.

pH Static Titration: A Quasistatic Approach

ERIC Educational Resources Information Center

Michalowski, Tadeusz; Toporek, Marcin; Rymanowski, Maciej

2007-01-01

The pH-static titration is applicable to those systems where at least two types of reactions occur in comparable intensities. The commonalities in titrimetric procedure realized according to pH-static titration, irrespective of the kind of chemical processes occurring are discussed.

Thermodynamic Cycle and CFD Analyses for Hydrogen Fueled Air-breathing Pulse Detonation Engines

NASA Technical Reports Server (NTRS)

Povinelli, Louis A.; Yungster, Shaye

2002-01-01

This paper presents the results of a thermodynamic cycle analysis of a pulse detonation engine (PDE) using a hydrogen-air mixture at static conditions. The cycle performance results, namely the specific thrust, fuel consumption and impulse are compared to a single cycle CFD analysis for a detonation tube which considers finite rate chemistry. The differences in the impulse values were indicative of the additional performance potential attainable in a PDE.

Influence of different manufacturing methods on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

PubMed

Rodrigues, Renata C V; Lopes, Hélio P; Elias, Carlos N; Amaral, Georgiana; Vieira, Victor T L; De Martin, Alexandre S

2011-11-01

The aim of this study was to evaluate, by static and dynamic cyclic fatigue tests, the number of cycles to fracture (NCF) 2 types of rotary NiTi instruments: Twisted File (SybronEndo, Orange, CA), which is manufactured by a proprietary twisting process, and RaCe files (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which are manufactured by grinding. Twenty Twisted Files (TFs) and 20 RaCe files #25/.006 taper instruments were allowed to rotate freely in an artificial curved canal at 310 rpm in a static or a dynamic model until fracture occurred. Measurements of the fractured fragments showed that fracture occurred at the point of maximum flexure in the midpoint of the curved segment. The NCF was significantly lower for RaCe instruments compared with TFs. The NCF was also lower for instruments subjected to the static test compared with the dynamic model in both groups. Scanning electron microscopic analysis revealed ductile morphologic characteristics on the fractured surfaces of all instruments and no plastic deformation in their helical shafts. Rotary NiTi endodontic instruments manufactured by twisting present greater resistance to cyclic fatigue compared with instruments manufactured by grinding. The fracture mode observed in all instruments was of the ductile type. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Validation of instrumentation to monitor dynamic performance of olympic weightlifters.

PubMed

Bruenger, Adam J; Smith, Sarah L; Sands, William A; Leigh, Michael R

2007-05-01

The purpose of this study was to validate the accuracy and reliability of the Weightlifting Video Overlay System (WVOS) used by coaches and sport biomechanists at the United States Olympic Training Center. Static trials with the bar set at specific positions and dynamic trials of a power snatch were performed. Static and dynamic values obtained by the WVOS were compared with values obtained by tape measure and standard video kinematic analysis. Coordinate positions (horizontal [X] and vertical [Y]) were compared on both ends (left and right) of the bar. Absolute technical error of measurement between WVOS and kinematic values were calculated (0.97 cm [left X], 0.98 cm [right X], 0.88 cm [left Y], and 0.53 cm [right Y]) for the static data. Pearson correlations for all dynamic trials exceeded r = 0.88. The greatest discrepancies between the 2 measuring systems were found to occur when there was twisting of the bar during the performance. This error was probably due to the location on the bar where the coordinates were measured. The WVOS appears to provide accurate position information when compared with standard kinematics; however, care must be taken in evaluating position measurements if there is a significant amount of twisting in the movement. The WVOS appears to be reliable and valid within reasonable error limits for the determination of weightlifting movement technique.

Individuals Achieve More Accurate Results with Meters That Are Codeless and Employ Dynamic Electrochemistry

PubMed Central

Rao, Anoop; Wiley, Meg; Iyengar, Sridhar; Nadeau, Dan; Carnevale, Julie

2010-01-01

Background Studies have shown that controlling blood glucose can reduce the onset and progression of the long-term microvascular and neuropathic complications associated with the chronic course of diabetes mellitus. Improved glycemic control can be achieved by frequent testing combined with changes in medication, exercise, and diet. Technological advancements have enabled improvements in analytical accuracy of meters, and this paper explores two such parameters to which that accuracy can be attributed. Methods Four blood glucose monitoring systems (with or without dynamic electrochemistry algorithms, codeless or requiring coding prior to testing) were evaluated and compared with respect to their accuracy. Results Altogether, 108 blood glucose values were obtained for each system from 54 study participants and compared with the reference values. The analysis depicted in the International Organization for Standardization table format indicates that the devices with dynamic electrochemistry and the codeless feature had the highest proportion of acceptable results overall (System A, 101/103). Results were significant when compared at the 10% bias level with meters that were codeless and utilized static electrochemistry (p = .017) or systems that had static electrochemistry but needed coding (p = .008). Conclusions Analytical performance of these blood glucose meters differed significantly depending on their technologic features. Meters that utilized dynamic electrochemistry and did not require coding were more accurate than meters that used static electrochemistry or required coding. PMID:20167178

Individuals achieve more accurate results with meters that are codeless and employ dynamic electrochemistry.

PubMed

Rao, Anoop; Wiley, Meg; Iyengar, Sridhar; Nadeau, Dan; Carnevale, Julie

2010-01-01

Studies have shown that controlling blood glucose can reduce the onset and progression of the long-term microvascular and neuropathic complications associated with the chronic course of diabetes mellitus. Improved glycemic control can be achieved by frequent testing combined with changes in medication, exercise, and diet. Technological advancements have enabled improvements in analytical accuracy of meters, and this paper explores two such parameters to which that accuracy can be attributed. Four blood glucose monitoring systems (with or without dynamic electrochemistry algorithms, codeless or requiring coding prior to testing) were evaluated and compared with respect to their accuracy. Altogether, 108 blood glucose values were obtained for each system from 54 study participants and compared with the reference values. The analysis depicted in the International Organization for Standardization table format indicates that the devices with dynamic electrochemistry and the codeless feature had the highest proportion of acceptable results overall (System A, 101/103). Results were significant when compared at the 10% bias level with meters that were codeless and utilized static electrochemistry (p = .017) or systems that had static electrochemistry but needed coding (p = .008). Analytical performance of these blood glucose meters differed significantly depending on their technologic features. Meters that utilized dynamic electrochemistry and did not require coding were more accurate than meters that used static electrochemistry or required coding. 2010 Diabetes Technology Society.

Acute Effects of Different Agonist and Antagonist Stretching Arrangements on Static and Dynamic Range of Motion.

PubMed

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2015-12-01

Traditionally, stretching exercises are considered as basic components of warm up aiming to prepare the musculoskeletal system for performance and to prevent injuries. The purpose of this study was to examine the effects of different agonist and antagonist stretching arrangements within a pre-exercise warm-up on hip static (SROM) and dynamic range of motion (DROM). Sixty trained male subjects (Mean ± SD: height, 177.38 ± 6.92 cm; body mass, 68.4 ± 10.22 kg; age, 21.52 ± 1.17 years) volunteered to participate in this study. SROM was measured by V-sit test and DROM captured by a motion analysis system before and after (i) static stretching for both hip flexor and extensor muscles (SFSE), (ii) dynamic stretching for both hip flexor and extensor muscles (DFDE), (iii) static stretching for the hip flexors and dynamic stretching for hip extensors (SFDE), and (iv) dynamic stretching for the hip flexors and static stretching for hip extensors (DFSE). DFSE showed a significantly higher increase in DROM and SROM than the remainder of the stretching protocols (P < 0.05). There were significant differences between DFDE with SFSE and SFDE (P < 0.05) and SFSE showed significant increase as compared to SFDE (P < 0.05). In conclusion, DFSE is probably the best stretching arrangement due to producing more post activation potentiation on agonist muscles and less muscle stiffness in antagonist muscles.

Flight effects on noise by the JT8D engine with inverted primary/fan flow as measured in the NASA-Ames 40 by 80 foot wind tunnel

NASA Technical Reports Server (NTRS)

Strout, F. G.

1978-01-01

A JT8D-17R engine with inverted primary and fan flows was tested under static conditions as well as in the NASA Ames 40 by 80 Foot Wind Tunnel to determine static and flight noise characteristics, and flow profile of a large scale engine. Test and analysis techniques developed by a previous model and JT8D engine test program were used to determine the in-flight noise. The engine with inverted flow was tested with a conical nozzle and with a plug nozzle, 20 lobe nozzle, and an acoustic shield. Wind tunnel results show that forward velocity causes significant reduction in peak PNL suppression relative to uninverted flow. The loss of EPNL suppression is relatively modest. The in-flight peak PNL suppression of the inverter with conical nozzle was 2.5 PNdb relative to a static value of 5.5 PNdb. The corresponding EPNL suppression was 4.0 EPNdb for flight and 5.0 EPNdb for static operation. The highest in-flight EPNL suppression was 7.5 EPNdb obtained by the inverter with 20 lobe nozzle and acoustic shield. When compared with the JT8D engine with internal mixer, the inverted flow configuration provides more EPNL suppression under both static and flight conditions.

Bifurcation Analysis of an Electrostatically Actuated Nano-Beam Based on Modified Couple Stress Theory

NASA Astrophysics Data System (ADS)

Rezaei Kivi, Araz; Azizi, Saber; Norouzi, Peyman

2017-12-01

In this paper, the nonlinear size-dependent static and dynamic behavior of an electrostatically actuated nano-beam is investigated. A fully clamped nano-beam is considered for the modeling of the deformable electrode of the NEMS. The governing differential equation of the motion is derived using Hamiltonian principle based on couple stress theory; a non-classical theory for considering length scale effects. The nonlinear partial differential equation of the motion is discretized to a nonlinear Duffing type ODE's using Galerkin method. Static and dynamic pull-in instabilities obtained by both classical theory and MCST are compared. At the second stage of analysis, shooting technique is utilized to obtain the frequency response curve, and to capture the periodic solutions of the motion; the stability of the periodic solutions are gained by Floquet theory. The nonlinear dynamic behavior of the deformable electrode due to the AC harmonic accompanied with size dependency is investigated.

Strength and Stiffness Analysis by the Finite-Difference Method of a Concrete Floor Slab Reinforced with Composite Rods During a Fire

NASA Astrophysics Data System (ADS)

Shirko, A. V.; Kamlyuk, A. N.; Drobysh, A. S.; Spiglazov, A. V.

2017-05-01

A strength and stiffness comparative analysis has been made of a concrete slab reinforced with composite-reinforcement rods and a slab reinforced with steel rods. The stress-strain state has been assessed for both versions of reinforcement of the slab. The stress-strain state was determined under the action of only static load and with subsequent application of temperature fields, i.e., under standard-fire conditions. It has been shown that the fire resistance of the slab with a composite reinforcement turns out to be 1.6 higher as far as the bearing capacity is concerned, than the fire resistance of the slab with a steel reinforcement, although the initial deflection due to the action of only static load for the slab reinforced with composite rods exceeds six to seven times the deflection of the slab reinforced with steel rods.

Structural Analysis Peer Review for the Static Display of the Orbiter Atlantis at the Kennedy Space Center Visitors Center

NASA Technical Reports Server (NTRS)

Minute, Stephen A.

2013-01-01

Mr. Christopher Miller with the Kennedy Space Center (KSC) NASA Safety & Mission Assurance (S&MA) office requested the NASA Engineering and Safety Center's (NESC) technical support on March 15, 2012, to review and make recommendations on the structural analysis being performed for the Orbiter Atlantis static display at the KSC Visitor Center. The principal focus of the assessment was to review the engineering firm's structural analysis for lifting and aligning the orbiter and its static display configuration

Parametric optimization and design validation based on finite element analysis of hybrid socket adapter for transfemoral prosthetic knee.

PubMed

Kumar, Neelesh

2014-10-01

Finite element analysis has been universally employed for the stress and strain analysis in lower extremity prosthetics. The socket adapter was the principal subject of interest due to its importance in deciding the knee motion range. This article focused on the static and dynamic stress analysis of the designed hybrid adapter developed by the authors. A standard mechanical design validation approach using von Mises was followed. Four materials were considered for the analysis, namely, carbon fiber, oil-filled nylon, Al-6061, and mild steel. The paper analyses the static and dynamic stress on designed hybrid adapter which incorporates features of conventional male and female socket adapters. The finite element analysis was carried out for possible different angles of knee flexion simulating static and dynamic gait situation. Research was carried out on available design of socket adapter. Mechanical design of hybrid adapter was conceptualized and a CAD model was generated using Inventor modelling software. Static and dynamic stress analysis was carried out on different materials for optimization. The finite element analysis was carried out on the software Autodesk Inventor Professional Ver. 2011. The peak value of von Mises stress occurred in the neck region of the adapter and in the lower face region at rod eye-adapter junction in static and dynamic analyses, respectively. Oil-filled nylon was found to be the best material among the four with respect to strength, weight, and cost. Research investigations on newer materials for development of improved prosthesis will immensely benefit the amputees. The study analyze the static and dynamic stress on the knee joint adapter to provide better material used for hybrid design of adapter. © The International Society for Prosthetics and Orthotics 2013.

Predictive modeling in Clostridium acetobutylicum fermentations employing Raman spectroscopy and multivariate data analysis for real-time culture monitoring

NASA Astrophysics Data System (ADS)

Zu, Theresah N. K.; Liu, Sanchao; Germane, Katherine L.; Servinsky, Matthew D.; Gerlach, Elliot S.; Mackie, David M.; Sund, Christian J.

2016-05-01

The coupling of optical fibers with Raman instrumentation has proven to be effective for real-time monitoring of chemical reactions and fermentations when combined with multivariate statistical data analysis. Raman spectroscopy is relatively fast, with little interference from the water peak present in fermentation media. Medical research has explored this technique for analysis of mammalian cultures for potential diagnosis of some cancers. Other organisms studied via this route include Escherichia coli, Saccharomyces cerevisiae, and some Bacillus sp., though very little work has been performed on Clostridium acetobutylicum cultures. C. acetobutylicum is a gram-positive anaerobic bacterium, which is highly sought after due to its ability to use a broad spectrum of substrates and produce useful byproducts through the well-known Acetone-Butanol-Ethanol (ABE) fermentation. In this work, real-time Raman data was acquired from C. acetobutylicum cultures grown on glucose. Samples were collected concurrently for comparative off-line product analysis. Partial-least squares (PLS) models were built both for agitated cultures and for static cultures from both datasets. Media components and metabolites monitored include glucose, butyric acid, acetic acid, and butanol. Models were cross-validated with independent datasets. Experiments with agitation were more favorable for modeling with goodness of fit (QY) values of 0.99 and goodness of prediction (Q2Y) values of 0.98. Static experiments did not model as well as agitated experiments. Raman results showed the static experiments were chaotic, especially during and shortly after manual sampling.

LEWICE3D/GlennHT Particle Analysis of the Honeywell Al502 Low Pressure Compressor

NASA Technical Reports Server (NTRS)

Bidwell, Colin S.; Rigby, David L.

2015-01-01

A flow and ice particle trajectory analysis was performed for the booster of the Honeywell AL502 engine. The analysis focused on two closely related conditions one of which produced a rollback and another which did not rollback during testing in the Propulsion Systems Lab at NASA Glenn Research Center. The flow analysis was generated using the NASA Glenn GlennHT flow solver and the particle analysis was generated using the NASA Glenn LEWICE3D v3.56 ice accretion software. The flow and particle analysis used a 3D steady flow, mixing plane approach to model the transport of flow and particles through the engine. The inflow conditions for the rollback case were: airspeed, 145 ms; static pressure, 33,373 Pa; static temperature, 253.3 K. The inflow conditions for the non-roll-back case were: airspeed, 153 ms; static pressure, 34,252 Pa; static temperature, 260.1 K. Both cases were subjected to an ice particle cloud with a median volume diameter of 24 microns, an ice water content of 2.0 gm3 and a relative humidity of 100 percent. The most significant difference between the rollback and non-rollback conditions was the inflow static temperature which was 6.8 K higher for the non-rollback case.

Comparison between static stretching and the Pilates method on the flexibility of older women.

PubMed

Oliveira, Laís Campos de; Oliveira, Raphael Gonçalves de; Pires-Oliveira, Deise Aparecida de Almeida

2016-10-01

Flexibility decreases with advancing age and some forms of exercise, such as static stretching and Pilates, can contribute to the improvement of this physical ability. To compare the effects of static stretching and Pilates on the flexibility of healthy older women, over the age of 60 years. Thirty-two volunteers were randomized into two groups (Static stretching or Pilates) to perform exercises for 60 min, twice a week, for three months. Evaluations to analyze the movements of the trunk (flexion and extension), hip flexion and plantar and dorsiflexion of the ankle were performed before and after the intervention, using a fleximeter. The static stretching exercises improved the trunk flexion and hip flexion movements, while the Pilates improved all evaluated movements. However, over time, the groups presented differences only for the trunk extension movement. For some body segments, Pilates may be more effective for improving flexibility in older women compared to static stretching. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microcracking, microcrack-induced delamination, and longitudinal splitting of advanced composite structures

NASA Technical Reports Server (NTRS)

Nairn, John A.

1992-01-01

A combined analytical and experimental study was conducted to analyze microcracking, microcrack-induced delamination, and longitudinal splitting in polymer matrix composites. Strain energy release rates, calculated by a variational analysis, were used in a failure criterion to predict microcracking. Predictions and test results were compared for static, fatigue, and cyclic thermal loading. The longitudinal splitting analysis accounted for the effects of fiber bridging. Test data are analyzed and compared for longitudinal splitting and delamination under mixed-mode loading. This study emphasizes the importance of using fracture mechanics analyses to understand the complex failure processes that govern composite strength and life.

Effect of Seepage on Change in Stress Distribution Scenario in Static and Seismic Behaviour of Earthen Dams

NASA Astrophysics Data System (ADS)

Nandi, N.; Chowdhury, Roy; Dutta, S. C.

2018-02-01

The present study makes an effort to understand the damage of earthen dams under static and seismic loading condition. To make the investigation more realistic, behaviour of earthen dams considering the occurrence of a phreatic line indicating the submerged zone due to seepage within the dam body is considered. In case of earthen dams, homogeneous or nonhomogeneous, the consideration of the occurrence of a phreatic line or seepage line through the dam body is an important part of the earthen dam design methodology. The impervious material properties in the submerged zone below the phreatic line due to seepage may differ a lot in magnitudes as compared to the value of the same materials lying above this line. Hence, to have the exact stress distribution scenarios within the earthen dam, the different material properties above and below the phreatic line are considered in this present study. The study is first carried out by two-dimensional as well as three-dimensional finite element analysis under static loading condition. The work is further extended to observe the effect of seepage due to the consideration of the phreatic line on dynamic characteristics of earthen dams. Free vibration analysis and seismic analysis based on the Complete Quadratic Combination (CQC) method by considering twodimensional and three-dimensional modeling are carried out to present the frequencies, mode shapes and the stress distribution pattern of the earthen dam.

Theoretical Analysis of Penalized Maximum-Likelihood Patlak Parametric Image Reconstruction in Dynamic PET for Lesion Detection.

PubMed

Yang, Li; Wang, Guobao; Qi, Jinyi

2016-04-01

Detecting cancerous lesions is a major clinical application of emission tomography. In a previous work, we studied penalized maximum-likelihood (PML) image reconstruction for lesion detection in static PET. Here we extend our theoretical analysis of static PET reconstruction to dynamic PET. We study both the conventional indirect reconstruction and direct reconstruction for Patlak parametric image estimation. In indirect reconstruction, Patlak parametric images are generated by first reconstructing a sequence of dynamic PET images, and then performing Patlak analysis on the time activity curves (TACs) pixel-by-pixel. In direct reconstruction, Patlak parametric images are estimated directly from raw sinogram data by incorporating the Patlak model into the image reconstruction procedure. PML reconstruction is used in both the indirect and direct reconstruction methods. We use a channelized Hotelling observer (CHO) to assess lesion detectability in Patlak parametric images. Simplified expressions for evaluating the lesion detectability have been derived and applied to the selection of the regularization parameter value to maximize detection performance. The proposed method is validated using computer-based Monte Carlo simulations. Good agreements between the theoretical predictions and the Monte Carlo results are observed. Both theoretical predictions and Monte Carlo simulation results show the benefit of the indirect and direct methods under optimized regularization parameters in dynamic PET reconstruction for lesion detection, when compared with the conventional static PET reconstruction.

Learning Enterprise Malware Triage from Automatic Dynamic Analysis

DTIC Science & Technology

2013-03-01

Kolter and Maloof n-gram method, Dube’s malware target recognition (MaTR) static method performs significantly more accurately at the 95% confidence...from the static method as in Kolter and Maloof. The MIST approach with behavior sequences 9 allows researchers to tailor the level of analysis to the...citations, none publish work that implements it. Only Kolter and Maloof use nearly as long gram structures, although that research uses static grams rather

Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

NASA Astrophysics Data System (ADS)

Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio

2015-09-01

Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

An investigation of the self-heating phenomenon in viscoelastic materials subjected to cyclic loadings accounting for prestress

NASA Astrophysics Data System (ADS)

de Lima, A. M. G.; Rade, D. A.; Lacerda, H. B.; Araújo, C. A.

2015-06-01

It has been demonstrated by many authors that the internal damping mechanism of the viscoelastic materials offers many possibilities for practical engineering applications. However, in traditional procedures of analysis and design of viscoelastic dampers subjected to cyclic loadings, uniform, constant temperature is generally assumed and do not take into account the self-heating phenomenon. Moreover, for viscoelastic materials subjected to dynamic loadings superimposed on static preloads, such as engine mounts, these procedures can lead to poor designs or even severe failures since the energy dissipated within the volume of the material leads to temperature rises. In this paper, a hybrid numerical-experimental investigation of effects of the static preloads on the self-heating phenomenon in viscoelastic dampers subjected to harmonic loadings is reported. After presenting the theoretical foundations, the numerical and experimental results obtained in terms of the temperature evolutions at different points within the volume of the viscoelastic material for various static preloads are compared, and the main features of the methodology are discussed.

Spreading Effect in Industrial Complex Network Based on Revised Structural Holes Theory

PubMed Central

Ye, Qing; Guan, Jun

2016-01-01

This paper analyzed the spreading effect of industrial sectors with complex network model under perspective of econophysics. Input-output analysis, as an important research tool, focuses more on static analysis. However, the fundamental aim of industry analysis is to figure out how interaction between different industries makes impacts on economic development, which turns out to be a dynamic process. Thus, industrial complex network based on input-output tables from WIOD is proposed to be a bridge connecting accurate static quantitative analysis and comparable dynamic one. With application of revised structural holes theory, flow betweenness and random walk centrality were respectively chosen to evaluate industrial sectors’ long-term and short-term spreading effect process in this paper. It shows that industries with higher flow betweenness or random walk centrality would bring about more intensive industrial spreading effect to the industrial chains they stands in, because value stream transmission of industrial sectors depends on how many products or services it can get from the other ones, and they are regarded as brokers with bigger information superiority and more intermediate interests. PMID:27218468

Spreading Effect in Industrial Complex Network Based on Revised Structural Holes Theory.

PubMed

Xing, Lizhi; Ye, Qing; Guan, Jun

2016-01-01

This paper analyzed the spreading effect of industrial sectors with complex network model under perspective of econophysics. Input-output analysis, as an important research tool, focuses more on static analysis. However, the fundamental aim of industry analysis is to figure out how interaction between different industries makes impacts on economic development, which turns out to be a dynamic process. Thus, industrial complex network based on input-output tables from WIOD is proposed to be a bridge connecting accurate static quantitative analysis and comparable dynamic one. With application of revised structural holes theory, flow betweenness and random walk centrality were respectively chosen to evaluate industrial sectors' long-term and short-term spreading effect process in this paper. It shows that industries with higher flow betweenness or random walk centrality would bring about more intensive industrial spreading effect to the industrial chains they stands in, because value stream transmission of industrial sectors depends on how many products or services it can get from the other ones, and they are regarded as brokers with bigger information superiority and more intermediate interests.

Efficiency of static core turn-off in a system-on-a-chip with variation

DOEpatents

Cher, Chen-Yong; Coteus, Paul W; Gara, Alan; Kursun, Eren; Paulsen, David P; Schuelke, Brian A; Sheets, II, John E; Tian, Shurong

2013-10-29

A processor-implemented method for improving efficiency of a static core turn-off in a multi-core processor with variation, the method comprising: conducting via a simulation a turn-off analysis of the multi-core processor at the multi-core processor's design stage, wherein the turn-off analysis of the multi-core processor at the multi-core processor's design stage includes a first output corresponding to a first multi-core processor core to turn off; conducting a turn-off analysis of the multi-core processor at the multi-core processor's testing stage, wherein the turn-off analysis of the multi-core processor at the multi-core processor's testing stage includes a second output corresponding to a second multi-core processor core to turn off; comparing the first output and the second output to determine if the first output is referring to the same core to turn off as the second output; outputting a third output corresponding to the first multi-core processor core if the first output and the second output are both referring to the same core to turn off.

The impact of dynamic balance measures on walking performance in multiple sclerosis.

PubMed

Fritz, Nora E; Marasigan, Rhul Evans R; Calabresi, Peter A; Newsome, Scott D; Zackowski, Kathleen M

2015-01-01

Static posture imbalance and gait dysfunction are common in individuals with multiple sclerosis (MS). Although the impact of strength and static balance on walking has been examined, the impact of dynamic standing balance on walking in MS remains unclear. To determine the impact of dynamic balance, static balance, sensation, and strength measures on walking in individuals with MS. Fifty-two individuals with MS (27 women; 26 relapsing-remitting; mean age = 45.6 ± 10.3 years; median Expanded Disability Status Scale score = 3.5) participated in posturography testing (Kistler-9281 force plate), hip flexion, hip extension, ankle dorsiflexion strength (Microfet2 hand-held dynamometer), sensation (Vibratron II), and walk velocity (Optotrak Motion Analysis System). Analyses included, Mann-Whitney, Spearman correlation coefficients, and multiple regression. All measures were abnormal in individuals with MS when compared with norms (P < .05). Static balance (eyes open, feet together [EOFT]), anterior-posterior (AP) dynamic sway, and hip extension strength were strongly correlated with walking velocity (AP sway r = 0.68; hip extension strength r = 0.73; EOFT r = -0.40). Together, AP dynamic sway (ρr = 0.71; P < .001), hip extension strength (ρr = 0.54; P < .001), and EOFT static balance (ρr = -0.41; P = .01) explained more than 70% of the variance in walking velocity (P < .001). AP dynamic sway affects walking performance in MS. A combined evaluation of dynamic balance, static balance, and strength may lead to a better understanding of walking mechanisms and the development of strategies to improve walking. © The Author(s) 2014.

A Comparison of Laser and Video Techniques for Determining Displacement and Velocity during Running

ERIC Educational Resources Information Center

Harrison, Andrew J.; Jensen, Randall L.; Donoghue, Orna

2005-01-01

The reliability of a laser system was compared with the reliability of a video-based kinematic analysis in measuring displacement and velocity during running. Validity and reliability of the laser on static measures was also assessed at distances between 10 m and 70 m by evaluating the coefficient of variation and intraclass correlation…

Investigation of two pitot-static tubes at supersonic speeds

NASA Technical Reports Server (NTRS)

Hasel, Lowell E; Coletti, Donald E

1948-01-01

The results of tests at a Mach number of 1.94 of an ogives-nose cylindrical pitot-static tube and similar tests at Mach numbers of 1.93 and 1.62 of a service pitot-static tube to determine body static pressures and indicated Mach numbers are presented and discussed. The radial pressure distribution on the cylindrical bodies is compared with that calculated by an approximate theory.

Actinobacillus pleuropneumoniae genes expression in biofilms cultured under static conditions and in a drip-flow apparatus

PubMed Central

2013-01-01

Background Actinobacillus pleuropneumoniae is the Gram-negative bacterium responsible for porcine pleuropneumonia. This respiratory infection is highly contagious and characterized by high morbidity and mortality. The objectives of our study were to study the transcriptome of A. pleuropneumoniae biofilms at different stages and to develop a protocol to grow an A. pleuropneumoniae biofilm in a drip-flow apparatus. This biofilm reactor is a system with an air-liquid interface modeling lung-like environment. Bacteria attached to a surface (biofilm) and free floating bacteria (plankton) were harvested for RNA isolation. Labelled cDNA was hybridized to a microarray to compare the expression profiles of planktonic cells and biofilm cells. Results It was observed that 47 genes were differentially expressed (22 up, 25 down) in a 4 h-static growing/maturing biofilm and 117 genes were differentially expressed (49 up, 68 down) in a 6h-static dispersing biofilm. The transcriptomes of a 4 h biofilm and a 6 h biofilm were also compared and 456 genes (235 up, 221 down) were identified as differently expressed. Among the genes identified in the 4 h vs 6h biofilm experiment, several regulators of stress response were down-regulated and energy metabolism associated genes were up-regulated. Biofilm bacteria cultured using the drip-flow apparatus differentially expressed 161 genes (68 up, 93 down) compared to the effluent bacteria. Cross-referencing of differentially transcribed genes in the different assays revealed that drip-flow biofilms shared few differentially expressed genes with static biofilms (4 h or 6 h) but shared several differentially expressed genes with natural or experimental infections in pigs. Conclusion The formation of a static biofilm by A. pleuropneumoniae strain S4074 is a rapid process and transcriptional analysis indicated that dispersal observed at 6 h is driven by nutritional stresses. Furthermore, A. pleuropneumoniae can form a biofilm under low-shear force in a drip-flow apparatus and analyses indicated that the formation of a biofilm under low-shear force requires a different sub-set of genes than a biofilm grown under static conditions. The drip-flow apparatus may represent the better in vitro model to investigate biofilm formation of A. pleuropneumoniae. PMID:23725589

Static, Dynamic, and Fatigue Analysis of the Mechanical System of Ultrasonic Scanner for Inservice Inspection of Research Reactors

NASA Astrophysics Data System (ADS)

Awwaluddin, Muhammad; Kristedjo, K.; Handono, Khairul; Ahmad, H.

2018-02-01

This analysis is conducted to determine the effects of static and dynamic loads of the structure of mechanical system of Ultrasonic Scanner i.e., arm, column, and connection systems for inservice inspection of research reactors. The analysis is performed using the finite element method with 520 N static load. The correction factor of dynamic loads used is the Gerber mean stress correction (stress life). The results of the analysis show that the value of maximum equivalent von Mises stress is 1.3698E8 Pa for static loading and value of the maximum equivalent alternating stress is 1.4758E7 Pa for dynamic loading. These values are below the upper limit allowed according to ASTM A240 standards i.e. 2.05E8 Pa. The result analysis of fatigue life cycle are at least 1E6 cycle, so it can be concluded that the structure is in the high life cycle category.

Application of a transonic potential flow code to the static aeroelastic analysis of three-dimensional wings

NASA Technical Reports Server (NTRS)

Whitlow, W., Jr.; Bennett, R. M.

1982-01-01

Since the aerodynamic theory is nonlinear, the method requires the coupling of two iterative processes - an aerodynamic analysis and a structural analysis. A full potential analysis code, FLO22, is combined with a linear structural analysis to yield aerodynamic load distributions on and deflections of elastic wings. This method was used to analyze an aeroelastically-scaled wind tunnel model of a proposed executive-jet transport wing and an aeroelastic research wing. The results are compared with the corresponding rigid-wing analyses, and some effects of elasticity on the aerodynamic loading are noted.

Hydrogen bonding interactions and supramolecular assemblies in 2-amino guanidinium 4-methyl benzene sulphonate crystal structure: Hirshfeld surfaces and computational calculations

NASA Astrophysics Data System (ADS)

Muthuraja, P.; Joselin Beaula, T.; Balachandar, S.; Bena Jothy, V.; Dhandapani, M.

2017-10-01

2-aminoguanidinium 4-methyl benzene sulphonate (AGMS), an organic compound with big assembly of hydrogen bonding interactions was crystallized at room temperature. The structure of the compound was confirmed by FT-IR, NMR and single crystal X-ray diffraction analysis. Numerous hydrogen bonded interactions were found to form supramolecular assemblies in the molecular structure. Fingerprint plots of Hirshfeld surface analysis spells out the interactions in various directions. The molecular structure of AGMS was optimised by HF, MP2 and DFT (B3LYP and CAM-B3LYP) methods at 6-311G (d,p) basis set and the geometrical parameters were compared. Electrostatic potential calculations of the reactants and product confirm the transfer of proton. Optical properties of AGMS were ascertained by UV-Vis absorbance and reflectance spectra. The band gap of AGMS is found to be 2.689 eV. Due to numerous hydrogen bonds, the crystal is thermally stable up to 200 °C. Hyperconjugative interactions which are responsible for the second hyperpolarizabilities were accounted by NBO analysis. Static and frequency dependent optical properties were calculated at HF and DFT methods. The hyperpolarizabilities of AGMS increase rapidly at frequencies 0.0428 and 0.08 a.u. compared to static one. The compound exhibits violet and blue emission.

MO-F-16A-01: Implementation of MPPG TPS Verification Tests On Various Accelerators

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

Smilowitz, J; Bredfeldt, J; Geurts, M

2014-06-15

Purpose: To demonstrate the implementation of the Medical Physics Practice Guideline (MPPG) for dose calculation and beam parameters verification of treatment planning systems (TPS). Methods: We implemented the draft TPS MPPG for three linacs: Varian Trilogy, TomoHDA and Elekta Infinity. Static and modulated test plans were created. The static fields are different than used in commissioning. Data was collected using ion chambers and diodes in a scanning water tank, Delta4 phantom and a custom phantom. MatLab and Microsoft Excel were used to create analysis tools to compare reference DICOM dose with scan data. This custom code allowed for the interpolation,more » registration and gamma analysis of arbitrary dose profiles. It will be provided as open source code. IMRT fields were validated with Delta4 registration and comparison tools. The time for each task was recorded. Results: The tests confirmed the strengths, and revealed some limitations, of our TPS. The agreement between calculated and measured dose was reported for all beams. For static fields, percent depth dose and profiles were analyzed with criteria in the draft MPPG. The results reveal areas of slight mismatch with the model (MLC leaf penumbra, buildup region.) For TomoTherapy, the IMRT plan 2%/2 mm gamma analysis revealed poorest agreement in the low dose regions. For one static test plan for all 10MV Trilogy photon beams, the plan generation, scan queue creation, data collection, data analysis and report took 2 hours, excluding tank setup. Conclusions: We have demonstrated the implementation feasibility of the TPS MPPG. This exercise generated an open source tool for dose comparisons between scan data and DICOM dose data. An easily reproducible and efficient infrastructure with streamlined data collection was created for repeatable robust testing of the TPS. The tests revealed minor discrepancies in our models and areas for improvement that are being investigated.« less

Comprehensive Forced Response Analysis of J2X Turbine Bladed-Discs with 360 Degree Variation in CFD Loading

NASA Technical Reports Server (NTRS)

Elrod, David; Christensen, Eric; Brown, Andrew

2011-01-01

The temporal frequency content of the dynamic pressure predicted by a 360 degree computational fluid dynamics (CFD) analysis of a turbine flow field provides indicators of forcing function excitation frequencies (e.g., multiples of blade pass frequency) for turbine components. For the Pratt and Whitney Rocketdyne J-2X engine turbopumps, Campbell diagrams generated using these forcing function frequencies and the results of NASTRAN modal analyses show a number of components with modes in the engine operating range. As a consequence, forced response and static analyses are required for the prediction of combined stress, high cycle fatigue safety factors (HCFSF). Cyclically symmetric structural models have been used to analyze turbine vane and blade rows, not only in modal analyses, but also in forced response and static analyses. Due to the tortuous flow pattern in the turbine, dynamic pressure loading is not cyclically symmetric. Furthermore, CFD analyses predict dynamic pressure waves caused by adjacent and non-adjacent blade/vane rows upstream and downstream of the row analyzed. A MATLAB script has been written to calculate displacements due to the complex cyclically asymmetric dynamic pressure components predicted by CFD analysis, for all grids in a blade/vane row, at a chosen turbopump running speed. The MATLAB displacements are then read into NASTRAN, and dynamic stresses are calculated, including an adjustment for possible mistuning. In a cyclically symmetric NASTRAN static analysis, static stresses due to centrifugal, thermal, and pressure loading at the mode running speed are calculated. MATLAB is used to generate the HCFSF at each grid in the blade/vane row. When compared to an approach assuming cyclic symmetry in the dynamic flow field, the current approach provides better assurance that the worst case safety factor has been identified. An extended example for a J-2X turbopump component is provided.

Stability of the Einstein static universe in open cosmological models

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

Canonico, Rosangela; Parisi, Luca; INFN, Sezione di Napoli, GC di Salerno, Via Ponte Don Melillo, I-84081 Baronissi

2010-09-15

The stability properties of the Einstein static solution of general relativity are altered when corrective terms arising from modification of the underlying gravitational theory appear in the cosmological equations. In this paper the existence and stability of static solutions are considered in the framework of two recently proposed quantum gravity models. The previously known analysis of the Einstein static solutions in the semiclassical regime of loop quantum cosmology with modifications to the gravitational sector is extended to open cosmological models where a static neutrally stable solution is found. A similar analysis is also performed in the framework of Horava-Lifshitz gravitymore » under detailed balance and projectability conditions. In the case of open cosmological models the two solutions found can be either unstable or neutrally stable according to the admitted values of the parameters.« less

Comparison of quasi-static and dynamic squats: a three-dimensional kinematic, kinetic and electromyographic study of the lower limbs.

PubMed

Clément, Julien; Hagemeister, Nicola; Aissaoui, Rachid; de Guise, Jacques A

2014-01-01

Numerous studies have described 3D kinematics, 3D kinetics and electromyography (EMG) of the lower limbs during quasi-static or dynamic squatting activities. One study compared these two squatting conditions but only at low speed on healthy subjects, and provided no information on kinetics and EMG of the lower limbs. The purpose of the present study was to contrast simultaneous recordings of 3D kinematics, 3D kinetics and EMG of the lower limbs during quasi-stat ic and fast-dynamic squats in healthy and pathological subjects. Ten subjects were recruited: five healthy and five osteoarthritis subjects. A motion-capture system, force plate, and surface electrodes respectively recorded 3D kinematics, 3D kinetics and EMG of the lower limbs. Each subject performed a quasi-static squat and several fast-dynamic squats from 0° to 70° of knee flexion. The two squatting conditions were compared for positions where quasi-static and fast-dynamic knee flexion-extension angles were similar. Mean differences between quasi-static and fast-dynamic squats were 1.5° for rotations, 1.9 mm for translations, 2.1% of subjects' body weight for ground reaction forces, 6.6 Nm for torques, 11.2 mm for center of pressure, and 6.3% of maximum fast-dynamic electromyographic activities for EMG. Some significant differences (p<0.05) were found in internal rotation, anterior translation, vertical force and EMG. All differences between quasi-static and fast-dynamic squats were small. 69.5% of compared data were equivalent. In conclusion, this study showed that quasi-static and fast-dynamic squatting activities are comparable in terms of 3D kinematics, 3D kinetics and EMG, although some reservations still remain. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of static habitat attributes on local and regional Rocky intertidal community structure

USGS Publications Warehouse

Konar, B.; Iken, K.; Coletti, H.; Monson, Daniel H.; Weitzman, Ben P.

2016-01-01

Rocky intertidal communities are structured by local environmental drivers, which can be dynamic, fluctuating on various temporal scales, or static and not greatly varying across years. We examined the role of six static drivers (distance to freshwater, tidewater glacial presence, wave exposure, fetch, beach slope, and substrate composition) on intertidal community structure across the northern Gulf of Alaska. We hypothesized that community structure is less similar at the local scale compared with the regional scale, coinciding with static drivers being less similar on smaller than larger scales. We also hypothesized that static attributes mainly drive local biological community structure. For this, we surveyed five to six sites in each of the six regions in the mid and low intertidal strata. Across regions, static attributes were not consistently different and only small clusters of sites had similar attributes. Additionally, intertidal communities were less similar on the site compared with the region level. These results suggest that these biological communities are not strongly influenced by the local static attributes measured in this study. An alternative explanation is that static attributes among our regions are not different enough to influence the biological communities. This lack of evidence for a strong static driver may be a result of our site selection, which targeted rocky sheltered communities. This suggests that this habitat may be ideal to examine the influence of dynamic drivers. We recommend that future analyses of dynamic attributes may best be performed after analyses have demonstrated that sites do not differ in static attributes.

Postoperative dynamic extension splinting compared with fixation with Kirschner wires and static splinting in contractures of burned hands: a comparative study of 57 cases in 9 years.

PubMed

Tan, Onder; Atik, Bekir; Dogan, Ali; Uslu, Mustafa; Alpaslan, Suleyman

2007-01-01

Skin grafting is widely used for the treatment of postburn contractures. Their main disadvantage, a tendency to contract again, can be reduced and better outcomes achieved by postoperative splinting. In this study we compared the outcomes of dynamic and static splinting postoperatively. Of the 57 patients managed by split grafts, 36 (44 hands) had Kirschner (K) wires applied with static splints, whereas 21 (26 hands) had dynamic splinting. The mean age was 11 (range 2-37) and 15 (range 2-50) years in the two groups. Before and after the operation, basic hand functions were evaluated clinically, and the results analysed statistically. The mean follow-up times were 18 and 14 months respectively, and recurrence rates were 22% and 14%. We think that the postoperative dynamic splinting is superior to fixation with K-wires with or without static splints.

Experimental Investigation on the Resonance of a Liquid Column in a Capillary Tube.

PubMed

Hilpert; Miller

1999-11-01

Using a visualization technique, we observed the resonance of a water column trapped in a vertically oriented capillary tube due to acoustic excitation. The analysis of the quasi-static response suggests that the upper nonvisible meniscus followed the imposed flow by means of a sliding contact line without changing its shape. We compared the experiments with a previously developed theoretical model that addresses dissipation by assuming an axially symmetric and incompressible flow field that is spatially constant along the tube axis. Whereas the model agrees well with the measured quasi-static response, the deviations in the dynamic response reveal shortcomings of the model due to the simplified treatment of the viscous dissipation. Copyright 1999 Academic Press.

Comparison of Analysis with Test for Static Loading of Two Hypersonic Inflatable Aerodynamic Decelerator Concepts

NASA Technical Reports Server (NTRS)

Lyle, Karen H.

2015-01-01

Acceptance of new spacecraft structural architectures and concepts requires validated design methods to minimize the expense involved with technology demonstration via flight-testing. Hypersonic Inflatable Aerodynamic Decelerator (HIAD) architectures are attractive for spacecraft deceleration because they are lightweight, store compactly, and utilize the atmosphere to decelerate a spacecraft during entry. However, designers are hesitant to include these inflatable approaches for large payloads or spacecraft because of the lack of flight validation. This publication summarizes results comparing analytical results with test data for two concepts subjected to representative entry, static loading. The level of agreement and ability to predict the load distribution is considered sufficient to enable analytical predictions to be used in the design process.

Static magnetic field effects on proteases with fibrinolytic activity produced by Mucor subtilissimus.

PubMed

Albuquerque, Wendell; Nascimento, Thiago; Brandão-Costa, Romero; Fernandes, Thiago; Porto, Ana

2017-02-01

The influence of a static magnetic field (SMF) on crude enzyme extracts with proteolytic activity is described and discussed. Proteolytic enzymes, which hydrolyze peptide bonds, and fibrinolytic enzymes, which dissolve fibrin clots, have industrial relevance, and applicability dependent on improvements of productivity and activity. We investigated whether a moderate SMF affects proteolysis in different in vitro tests: general proteolysis of azocasein substrate, and static and dynamic fibrinolytic processes (to compare fibrin gel configuration under exposure). Crude enzyme extracts, obtained from solid state fermentation of Mucor subtilissimus UCP (Universidade Católica de Pernambuco, Recife, Brazil) 1262, were used to carry out assays under slightly heterogeneous fields: a varied vertical SMF (for tests in Eppendorf tubes, from 0.100 to 0.170 T) and a varied horizontal SMF (for tests in Petri dishes, from 0.01 to 0.122 T), generated by two permanent magnets (NdFeB alloy). Results showed significant differences (P < 0.05) in static fibrinolysis assays after 24 h of exposure. The mean diameter of halos of fibrin degradation in the treated group increased by 21% compared to the control group; and the pixel number count of fibrin consumption (in a computational analysis of the area of each halo) enhanced by 30% with exposure. However, in dynamic fibrinolysis assays, no effects of SMF were observed. These results suggest a response of fibrin monomers to the SMF as a possible cause of the observed effects. Bioelectromagnetics. 38:109-120, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Aeroelastic Ground Wind Loads Analysis Tool for Launch Vehicles

NASA Technical Reports Server (NTRS)

Ivanco, Thomas G.

2016-01-01

Launch vehicles are exposed to ground winds during rollout and on the launch pad that can induce static and dynamic loads. Of particular concern are the dynamic loads caused by vortex shedding from nearly-cylindrical structures. When the frequency of vortex shedding nears that of a lowly-damped structural mode, the dynamic loads can be more than an order of magnitude greater than mean drag loads. Accurately predicting vehicle response to vortex shedding during the design and analysis cycles is difficult and typically exceeds the practical capabilities of modern computational fluid dynamics codes. Therefore, mitigating the ground wind loads risk typically requires wind-tunnel tests of dynamically-scaled models that are time consuming and expensive to conduct. In recent years, NASA has developed a ground wind loads analysis tool for launch vehicles to fill this analytical capability gap in order to provide predictions for prelaunch static and dynamic loads. This paper includes a background of the ground wind loads problem and the current state-of-the-art. It then discusses the history and significance of the analysis tool and the methodology used to develop it. Finally, results of the analysis tool are compared to wind-tunnel and full-scale data of various geometries and Reynolds numbers.

[Assessment of the macula function by static perimetry, microperimetry and rarebit perimetry in patients suffering from dry age related macular degeneration].

PubMed

Nowomiejska, Katarzyna; Oleszczuk, Agnieszka; Zubilewicz, Anna; Krukowski, Jacek; Mańkowska, Anna; Rejdak, Robert; Zagórski, Zbigniew

2007-01-01

To compare the visual field results obtained by static perimetry, microperimetry and rabbit perimetry in patients suffering from dry age related macular degeneration (AMD). Fifteen eyes with dry AMD (hard or soft macula drusen and RPE disorders) were enrolled into the study. Static perimetry was performed using M2 macula program included in Octopus 101 instrument. Microperimetry was performed using macula program (14-2 threshold, 10dB) within 10 degrees of the central visual field. The fovea program within 4 degrees was used while performing rarebit perimetry. The mean sensitivity was significantly lower (p<0.001) during microperimetry (13.5 dB) comparing to static perimetry (26.7 dB). The mean deviation was significantly higher (p<0.001) during microperimetry (-6.32 dB) comparing to static perimetry (-3.11 dB). The fixation was unstable in 47% and eccentric in 40% while performing microperimetry. The median of the "mean hit rate" in rarebit perimetry was 90% (range 40-100%). The mean examination duration was 6.5 min. in static perimetry, 10.6 min. in microperimetry and 5,5 min. in rarebit perimetry (p<0.001). Sensitivity was 30%, 53% and 93% respectively. The visual field defects obtained by microperimetry were more pronounced than those obtained by static perimetry. Microperimetry was the most sensitive procedure although the most time-consuming. Microperimetry enables the control of the fixation position and stability, that is not possible using the remaining methods. Rarebit perimetry revealed slight reduction of the integrity of neural architecture of the retina. Microperimetry and rarebit perimetry provide more information in regard to the visual function than static perimetry, thus are the valuable method in the diagnosis of dry AMD.

Comparison of composite rotor blade models: A coupled-beam analysis and an MSC/NASTRAN finite-element model

NASA Technical Reports Server (NTRS)

Hodges, Robert V.; Nixon, Mark W.; Rehfield, Lawrence W.

1987-01-01

A methodology was developed for the structural analysis of composite rotor blades. This coupled-beam analysis is relatively simple to use compared with alternative analysis techniques. The beam analysis was developed for thin-wall single-cell rotor structures and includes the effects of elastic coupling. This paper demonstrates the effectiveness of the new composite-beam analysis method through comparison of its results with those of an established baseline analysis technique. The baseline analysis is an MSC/NASTRAN finite-element model built up from anisotropic shell elements. Deformations are compared for three linear static load cases of centrifugal force at design rotor speed, applied torque, and lift for an ideal rotor in hover. A D-spar designed to twist under axial loading is the subject of the analysis. Results indicate the coupled-beam analysis is well within engineering accuracy.

On the construction of a direct numerical simulation of a breaking inertia-gravity wave in the upper mesosphere

NASA Astrophysics Data System (ADS)

Fruman, Mark D.; Remmler, Sebastian; Achatz, Ulrich; Hickel, Stefan

2014-10-01

A systematic approach to the direct numerical simulation (DNS) of breaking upper mesospheric inertia-gravity waves of amplitude close to or above the threshold for static instability is presented. Normal mode or singular vector analysis applied in a frame of reference moving with the phase velocity of the wave (in which the wave is a steady solution) is used to determine the most likely scale and structure of the primary instability and to initialize nonlinear "2.5-D" simulations (with three-dimensional velocity and vorticity fields but depending only on two spatial coordinates). Singular vector analysis is then applied to the time-dependent 2.5-D solution to predict the transition of the breaking event to three-dimensional turbulence and to initialize three-dimensional DNS. The careful choice of the computational domain and the relatively low Reynolds numbers, on the order of 25,000, relevant to breaking waves in the upper mesosphere, makes the three-dimensional DNS tractable with present-day computing clusters. Three test cases are presented: a statically unstable low-frequency inertia-gravity wave, a statically and dynamically stable inertia-gravity wave, and a statically unstable high-frequency gravity wave. The three-dimensional DNS are compared to ensembles of 2.5-D simulations. In general, the decay of the wave and generation of turbulence is faster in three dimensions, but the results are otherwise qualitatively and quantitatively similar, suggesting that results of 2.5-D simulations are meaningful if the domain and initial condition are chosen properly.

Biomimetic evaluation of β tricalcium phosphate prepared by hot isostatic pressing

PubMed Central

Mateescu, Mihaela; Rguitti, Emmanuelle; Ponche, Arnaud; Descamps, Michel; Anselme, Karine

2012-01-01

Two types of completely densified β-TCP tablets were synthesized from a stoichiometric β-TCP powder. The first ones (TCP) were conventionally sintered, while the second ones (TCP-T) were sintered and treated by hot isostatic process (HIP). The HIP produced completely densified materials with relative densities greater than 99.9% and a transparent appearance of tablets. Samples were immersed in culture medium with (CM) or without serum (NCM) in static and dynamic conditions for a biomimetic evaluation. Similarly, SaOs-2 cells were cultured on samples in a static or dynamic flow perfusion system. The results of surface transformation in absence of cells showed that the dynamic condition increased the speed of calcium phosphate precipitations compared with the static condition. The morphology of precipitates was different with nature of tablets. The immersion in CM did impede this precipitation. XPS analysis of TCP-T tablets showed the presence of hydroxyapatite (HA) precipitates after incubation in NCM while octacalcium phosphate (OCP) precipitates were formed after incubation in CM. The analysis of the response of SaOs-2 cells on surfaces showed that the two types of materials are biocompatible. However, the dynamic mode of culture stimulated the differentiation of cells. Finally, it appears that the HIP treatment of TCP produces highly densified and transparent samples that display a good in vitro biocompatibility in static and dynamic culture conditions. Moreover, an interesting result of this work is the relationship between the presence of proteins in the immersion medium and the quality of precipitates formed on hipped TCP surface. PMID:23507861

Expert Design Advisor

DTIC Science & Technology

1990-10-01

to economic, technological, spatial or logistic concerns, or involve training, man-machine interfaces, or integration into existing systems. Once the...probabilistic reasoning, mixed analysis- and simulation-oriented, mixed computation- and communication-oriented, nonpreemptive static priority...scheduling base, nonrandomized, preemptive static priority scheduling base, randomized, simulation-oriented, and static scheduling base. The selection of both

A prospective randomized multicenter trial comparing clinical outcomes of patients treated surgically with a static or dynamic implant for acute ankle syndesmosis rupture.

PubMed

Laflamme, Mélissa; Belzile, Etienne L; Bédard, Luc; van den Bekerom, Michel P J; Glazebrook, Mark; Pelet, Stéphane

2015-05-01

To compare the clinical and radiographic outcome after stabilization of an acute syndesmosis rupture with either a static implant (a 3.5-mm metallic screw through 4 cortices) or a dynamic device (TightRope; Arthrex). Multicenter randomized double-blind controlled trial. Study realized in 5 trauma centers (2 level 1 and 3 level 2) in 2 countries. Seventy subjects admitted for an acute ankle syndesmosis rupture entered the study and were randomized into 2 groups (dynamic fixation = 34 and static fixation = 36). The 2 groups were similar regarding demographic, social, and surgical data. Sixty-five patients (dynamic = 33 and static = 32) completed the study and were available for analysis. Syndesmosis fixation in the static group was realized with a 4 cortices 3.5-mm cortical screw (Synthes) and in the dynamic group with 1 TightRope (Arthrex). Standardized rehabilitation process for the 2 groups: no weight bearing in a cast for 6 weeks and then rehabilitation without protection. Olerud-Molander score. Subjects with dynamic fixation achieved better clinical performances as described with the Olerud-Molander scores at 3 (68.8 vs. 60.2, P = 0.067), 6 (84.2 vs. 76.8, P = 0.082), and 12 months (93.3 vs. 87.6, P = 0.046). We also observed higher American Orthopaedic Foot and Ankle Society scores at 3 months (78.6 vs. 70.6, P = 0.016), but these were not significant at 6 (87.1 vs. 83.8, P = 0.26) or 12 months (93.1 vs. 89.9, P = 0.26). Implant failure was higher in the screw group (36.1% vs. 0%, P < 0.05). Loss of reduction was observed in 4 cases in the static screw group (11.1% vs. 0%, P = 0.06). Dynamic fixation of acute ankle syndesmosis rupture with a dynamic device seems to result in better clinical and radiographic outcomes. The implant offers adequate syndesmotic stabilization without failure or loss of reduction, and the reoperation rate is significantly lower than with conventional screw fixation. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force.

PubMed

Alizadeh Ebadi, Leyla; Çetin, Ebru

2018-03-13

The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles' isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball) participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A) 5 min jogging; (B) 5 min jogging followed by 15 s static stretching; (C) 5 min jogging followed by 30 s static stretching; (D) 5 min jogging, followed by static stretching for 45 s). Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

Duration Dependent Effect of Static Stretching on Quadriceps and Hamstring Muscle Force

PubMed Central

Çetin, Ebru

2018-01-01

The aim of this study was to determine the acute effect of static stretching on hamstring and quadriceps muscles’ isokinetic strength when applied for various durations to elite athletes, to investigate the effect of different static stretching durations on isokinetic strength, and finally to determine the optimal stretching duration. Fifteen elite male athletes from two different sport branches (10 football and five basketball) participated in this study. Experimental protocol was designed as 17 repetitive static stretching exercises for hamstring and quadriceps muscle groups according to the indicated experimental protocols; ((A) 5 min jogging; (B) 5 min jogging followed by 15 s static stretching; (C) 5 min jogging followed by 30 s static stretching; (D) 5 min jogging, followed by static stretching for 45 s). Immediately after each protocol, an isokinetic strength test consisting of five repetitions at 60°/s speed and 20 repetitions at 180°/s speed was recorded for the right leg by the Isomed 2000 device. Friedman variance analysis test was employed for data analysis. According to the analyzes, it was observed that 5 min jogging and 15 s stretching exercises increased the isokinetic strength, whereas 30 and 45 s stretching exercises caused a decrease.

Performance tradeoffs in static and dynamic load balancing strategies

NASA Technical Reports Server (NTRS)

Iqbal, M. A.; Saltz, J. H.; Bokhart, S. H.

1986-01-01

The problem of uniformly distributing the load of a parallel program over a multiprocessor system was considered. A program was analyzed whose structure permits the computation of the optimal static solution. Then four strategies for load balancing were described and their performance compared. The strategies are: (1) the optimal static assignment algorithm which is guaranteed to yield the best static solution, (2) the static binary dissection method which is very fast but sub-optimal, (3) the greedy algorithm, a static fully polynomial time approximation scheme, which estimates the optimal solution to arbitrary accuracy, and (4) the predictive dynamic load balancing heuristic which uses information on the precedence relationships within the program and outperforms any of the static methods. It is also shown that the overhead incurred by the dynamic heuristic is reduced considerably if it is started off with a static assignment provided by either of the other three strategies.

Acute Effects of Different Agonist and Antagonist Stretching Arrangements on Static and Dynamic Range of Motion

PubMed Central

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2015-01-01

Background: Traditionally, stretching exercises are considered as basic components of warm up aiming to prepare the musculoskeletal system for performance and to prevent injuries. Objectives: The purpose of this study was to examine the effects of different agonist and antagonist stretching arrangements within a pre-exercise warm-up on hip static (SROM) and dynamic range of motion (DROM). Materials and Methods: Sixty trained male subjects (Mean ± SD: height, 177.38 ± 6.92 cm; body mass, 68.4 ± 10.22 kg; age, 21.52 ± 1.17 years) volunteered to participate in this study. SROM was measured by V-sit test and DROM captured by a motion analysis system before and after (i) static stretching for both hip flexor and extensor muscles (SFSE), (ii) dynamic stretching for both hip flexor and extensor muscles (DFDE), (iii) static stretching for the hip flexors and dynamic stretching for hip extensors (SFDE), and (iv) dynamic stretching for the hip flexors and static stretching for hip extensors (DFSE). Results: DFSE showed a significantly higher increase in DROM and SROM than the remainder of the stretching protocols (P < 0.05). There were significant differences between DFDE with SFSE and SFDE (P < 0.05) and SFSE showed significant increase as compared to SFDE (P < 0.05). Conclusions: In conclusion, DFSE is probably the best stretching arrangement due to producing more post activation potentiation on agonist muscles and less muscle stiffness in antagonist muscles. PMID:26715975

Ab-initio study of several static and dynamic properties of liquid palladium and platinum

NASA Astrophysics Data System (ADS)

González, L. E.; González, D. J.; Molla, Mohammad Riazuddin; Ahmed, A. Z. Ziauddin; Bhuiyan, G. M.

2017-08-01

We report a study on several static and dynamic properties of liquid Pd and Pt metals at thermodynamic conditions near their respective triple points. The calculations have been carried out by an ab initio molecular dynamics simulation technique. Results are reported for several static structural magnitudes which are compared with the available X-ray diffraction. As for the dynamic properties, results have been obtained for both single and collective dynamical magnitudes as well as for some transport coeffcients which are compared with the corresponding experimental data.

Scaling effects in the static and dynamic response of graphite-epoxy beam-columns. Ph.D. Thesis - Virginia Polytechnic Inst. and State Univ.

NASA Technical Reports Server (NTRS)

Jackson, Karen E.

1990-01-01

Scale model technology represents one method of investigating the behavior of advanced, weight-efficient composite structures under a variety of loading conditions. It is necessary, however, to understand the limitations involved in testing scale model structures before the technique can be fully utilized. These limitations, or scaling effects, are characterized. in the large deflection response and failure of composite beams. Scale model beams were loaded with an eccentric axial compressive load designed to produce large bending deflections and global failure. A dimensional analysis was performed on the composite beam-column loading configuration to determine a model law governing the system response. An experimental program was developed to validate the model law under both static and dynamic loading conditions. Laminate stacking sequences including unidirectional, angle ply, cross ply, and quasi-isotropic were tested to examine a diversity of composite response and failure modes. The model beams were loaded under scaled test conditions until catastrophic failure. A large deflection beam solution was developed to compare with the static experimental results and to analyze beam failure. Also, the finite element code DYCAST (DYnamic Crash Analysis of STructure) was used to model both the static and impulsive beam response. Static test results indicate that the unidirectional and cross ply beam responses scale as predicted by the model law, even under severe deformations. In general, failure modes were consistent between scale models within a laminate family; however, a significant scale effect was observed in strength. The scale effect in strength which was evident in the static tests was also observed in the dynamic tests. Scaling of load and strain time histories between the scale model beams and the prototypes was excellent for the unidirectional beams, but inconsistent results were obtained for the angle ply, cross ply, and quasi-isotropic beams. Results show that valuable information can be obtained from testing on scale model composite structures, especially in the linear elastic response region. However, due to scaling effects in the strength behavior of composite laminates, caution must be used in extrapolating data taken from a scale model test when that test involves failure of the structure.

Disrupted global metastability and static and dynamic brain connectivity across individuals in the Alzheimer’s disease continuum

NASA Astrophysics Data System (ADS)

Córdova-Palomera, Aldo; Kaufmann, Tobias; Persson, Karin; Alnæs, Dag; Doan, Nhat Trung; Moberget, Torgeir; Lund, Martina Jonette; Barca, Maria Lage; Engvig, Andreas; Brækhus, Anne; Engedal, Knut; Andreassen, Ole A.; Selbæk, Geir; Westlye, Lars T.

2017-01-01

As findings on the neuropathological and behavioral components of Alzheimer’s disease (AD) continue to accrue, converging evidence suggests that macroscale brain functional disruptions may mediate their association. Recent developments on theoretical neuroscience indicate that instantaneous patterns of brain connectivity and metastability may be a key mechanism in neural communication underlying cognitive performance. However, the potential significance of these patterns across the AD spectrum remains virtually unexplored. We assessed the clinical sensitivity of static and dynamic functional brain disruptions across the AD spectrum using resting-state fMRI in a sample consisting of AD patients (n = 80) and subjects with either mild (n = 44) or subjective (n = 26) cognitive impairment (MCI, SCI). Spatial maps constituting the nodes in the functional brain network and their associated time-series were estimated using spatial group independent component analysis and dual regression, and whole-brain oscillatory activity was analyzed both globally (metastability) and locally (static and dynamic connectivity). Instantaneous phase metrics showed functional coupling alterations in AD compared to MCI and SCI, both static (putamen, dorsal and default-mode) and dynamic (temporal, frontal-superior and default-mode), along with decreased global metastability. The results suggest that brains of AD patients display altered oscillatory patterns, in agreement with theoretical premises on cognitive dynamics.

Slope Stability Analysis In Seismic Areas Of The Northern Apennines (Italy)

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

Lo Presti, D.; Fontana, T.; Marchetti, D.

2008-07-08

Several research works have been published on the slope stability in the northern Tuscany (central Italy) and particularly in the seismic areas of Garfagnana and Lunigiana (Lucca and Massa-Carrara districts), aimed at analysing the slope stability under static and dynamic conditions and mapping the landslide hazard. In addition, in situ and laboratory investigations are available for the study area, thanks to the activities undertaken by the Tuscany Seismic Survey. Based on such a huge information the co-seismic stability of few ideal slope profiles have been analysed by means of Limit equilibrium method LEM - (pseudo-static) and Newmark sliding block analysismore » (pseudo-dynamic). The analysis--results gave indications about the most appropriate seismic coefficient to be used in pseudo-static analysis after establishing allowable permanent displacement. Such indications are commented in the light of the Italian and European prescriptions for seismic stability analysis with pseudo-static approach. The stability conditions, obtained from the previous analyses, could be used to define microzonation criteria for the study area.« less

Cyclic stress analysis of an air-cooled turbine vane

NASA Technical Reports Server (NTRS)

Kaufman, A.; Gauntner, D. J.; Gauntner, J. W.

1975-01-01

The effects of gas pressure level, coolant temperature, and coolant flow rate on the stress-strain history and life of an air-cooled vane were analyzed using measured and calculated transient metal temperatures and a turbine blade stress analysis program. Predicted failure locations were compared to results from cyclic tests in a static cascade and engine. The results indicate that a high gas pressure was detrimental, a high coolant flow rate somewhat beneficial, and a low coolant temperature the most beneficial to vane life.

Evaluation of SAR in a human body model due to wireless power transmission in the 10 MHz band.

PubMed

Laakso, Ilkka; Tsuchida, Shogo; Hirata, Akimasa; Kamimura, Yoshitsugu

2012-08-07

This study discusses a computational method for calculating the specific absorption rate (SAR) due to a wireless power transmission system in the 10 MHz frequency band. A two-step quasi-static method comprised of the method of moments and the scalar potential finite-difference method are proposed. The applicability of the quasi-static approximation for localized exposure in this frequency band is discussed by comparing the SAR in a lossy dielectric cylinder computed with a full-wave electromagnetic analysis and the quasi-static approximation. From the computational results, the input impedance of the resonant coils was affected by the existence of the cylinder. On the other hand, the magnetic field distribution in free space and considering the cylinder and an impedance matching circuit were in good agreement; the maximum difference in the amplitude of the magnetic field was 4.8%. For a cylinder-coil distance of 10 mm, the difference between the peak 10 g averaged SAR in the cylinder computed with the full-wave electromagnetic method and our quasi-static method was 7.8%. These results suggest that the quasi-static approach is applicable for conducting the dosimetry of wireless power transmission in the 10 MHz band. With our two-step quasi-static method, the SAR in the anatomically based model was computed for different exposure scenarios. From those computations, the allowable input power satisfying the limit of a peak 10 g averaged SAR of 2.0 W kg(-1) was 830 W in the worst case exposure scenario with a coil positioned at a distance of 30 mm from the chest.

Longitudinal quasi-static stability predicts changes in dog gait on rough terrain

PubMed Central

Reeve, Michelle A.; Haynes, G. Clark; Revzen, Shai; Koditschek, Daniel E.; Spence, Andrew J.

2017-01-01

ABSTRACT Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris, spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors (n=6, P<0.05). By formulating gaits as trajectories on the n-torus we are able to make tractable the analysis of gait similarity. These methods can be applied in a comparative study of gait control which will inform the ultimate role of the constraints and costs impacting locomotion, and have applications in diagnostic procedures for gait abnormalities, and in the development of agile legged robots. PMID:28264903

Longitudinal quasi-static stability predicts changes in dog gait on rough terrain.

PubMed

Wilshin, Simon; Reeve, Michelle A; Haynes, G Clark; Revzen, Shai; Koditschek, Daniel E; Spence, Andrew J

2017-05-15

Legged animals utilize gait selection to move effectively and must recover from environmental perturbations. We show that on rough terrain, domestic dogs, Canis lupus familiaris , spend more time in longitudinal quasi-statically stable patterns of movement. Here, longitudinal refers to the rostro-caudal axis. We used an existing model in the literature to quantify the longitudinal quasi-static stability of gaits neighbouring the walk, and found that trot-like gaits are more stable. We thus hypothesized that when perturbed, the rate of return to a stable gait would depend on the direction of perturbation, such that perturbations towards less quasi-statically stable patterns of movement would be more rapid than those towards more stable patterns of movement. The net result of this would be greater time spent in longitudinally quasi-statically stable patterns of movement. Limb movement patterns in which diagonal limbs were more synchronized (those more like a trot) have higher longitudinal quasi-static stability. We therefore predicted that as dogs explored possible limb configurations on rough terrain at walking speeds, the walk would shift towards trot. We gathered experimental data quantifying dog gait when perturbed by rough terrain and confirmed this prediction using GPS and inertial sensors ( n =6, P <0.05). By formulating gaits as trajectories on the n -torus we are able to make tractable the analysis of gait similarity. These methods can be applied in a comparative study of gait control which will inform the ultimate role of the constraints and costs impacting locomotion, and have applications in diagnostic procedures for gait abnormalities, and in the development of agile legged robots. © 2017. Published by The Company of Biologists Ltd.

Time series of ground reaction forces following a single leg drop jump landing in elite youth soccer players consist of four distinct phases.

PubMed

Fransz, Duncan P; Huurnink, Arnold; de Boode, Vosse A; Kingma, Idsart; van Dieën, Jaap H

2016-10-01

The single leg drop jump landing test may assess dynamic and static balance abilities in different phases of the landing. However objective definitions of different phases following landing and associated reliability are lacking. Therefore, we determined the existence of possible distinct phases of single leg drop jump landing on a force plate in 82 elite youth soccer players. Three outcome measures were calculated over moving windows of five sizes: center of pressure (COP) speed, COP sway and horizontal ground reaction force (GRF). Per outcome measure, a Factor Analysis was employed with all windows as input variables. It showed that four factors (patterns of variance) largely (>75%) explained the variance across subjects/trials along the 12s time series. Each factor was highly associated with a distinct phase of the time series signal: dynamic (0.4-2.7s), late dynamic (2.5-5.0s), static 1 (5.0-8.3s) and static 2 (8.1-11.7s). Intra-class correlations (ICC) between trials were lower for the dynamic phases (0.45-0.68) than for the static phases (0.60-0.86). The COP speed showed higher ICC's (0.63-0.86) than COP sway (0.45-0.61) and GRF (0.57-0.71) for all four phases. In conclusion, following a drop jump landing unique information is available in four distinct phases. The COP speed is most reliable, with higher reliability in the static phases compared to the dynamic phases. Future studies should assess the sensitivity of information from dynamic, late dynamic and static phases. Copyright © 2016 Elsevier B.V. All rights reserved.

The relationship between infratentorial lesions, balance deficit and accidental falls in multiple sclerosis.

PubMed

Prosperini, Luca; Kouleridou, Anna; Petsas, Nikolaos; Leonardi, Laura; Tona, Francesca; Pantano, Patrizia; Pozzilli, Carlo

2011-05-15

The role of static posturography and magnetic resonance imaging (MRI) in identifying patients at high risk of falls was investigated. Relationships between static posturography measures and MRI metrics were also investigated. A total of 31 ambulatory MS patients (EDSS ranging from 2.0 to 5.0) with a predominant balance disorder were recruited. Each patient underwent a static posturography with a monoaxial platform and a conventional 1.5 T brain MRI scan. Measurements of T1-hypointense and T2-hyperintense lesion volumes (LVs), focusing on lesions selectively located at infratentorial levels, were performed by two operators unaware of clinical data. The self-reported number of falls in the previous 6 months was considered as the main outcome measure. Fourteen (45%) patients reported 1 or more falls over the past 6 months. When compared to non-faller patients, they had a higher EDSS score, poorer static standing balance, and greater brainstem and middle cerebellar peduncle (MCP) T2-LVs. A strength correlation between brainstem T2-LV and impaired static standing balance in an open eye condition was also found. In the multivariate analysis, the variables more strictly associated with recurrent falls were greater T2-LV at the MCP (beta: 6.2; p=0.01) and brainstem (beta: 5.8; p=0.001) levels, and a wider displacement of the body center of pressure in the closed eye condition (beta: 0.02; p=0.03). Our data suggests that the damage of specific infratentorial areas negatively affect the static standing balance and may predispose MS patients to accidental falls. These findings might contribute in selecting patients requiring a proper rehabilitation intervention program. Copyright © 2011 Elsevier B.V. All rights reserved.

Auditory motion-specific mechanisms in the primate brain

PubMed Central

Baumann, Simon; Dheerendra, Pradeep; Joly, Olivier; Hunter, David; Balezeau, Fabien; Sun, Li; Rees, Adrian; Petkov, Christopher I.; Thiele, Alexander; Griffiths, Timothy D.

2017-01-01

This work examined the mechanisms underlying auditory motion processing in the auditory cortex of awake monkeys using functional magnetic resonance imaging (fMRI). We tested to what extent auditory motion analysis can be explained by the linear combination of static spatial mechanisms, spectrotemporal processes, and their interaction. We found that the posterior auditory cortex, including A1 and the surrounding caudal belt and parabelt, is involved in auditory motion analysis. Static spatial and spectrotemporal processes were able to fully explain motion-induced activation in most parts of the auditory cortex, including A1, but not in circumscribed regions of the posterior belt and parabelt cortex. We show that in these regions motion-specific processes contribute to the activation, providing the first demonstration that auditory motion is not simply deduced from changes in static spatial location. These results demonstrate that parallel mechanisms for motion and static spatial analysis coexist within the auditory dorsal stream. PMID:28472038

Does Intellectual Property Restrict Output? An Analysis of Pharmaceutical Markets*

PubMed Central

Lakdawalla, Darius; Philipson, Tomas

2013-01-01

Standard normative analysis of intellectual property focuses on the balance between incentives for research and the static welfare costs of reduced price-competition from monopoly. However, static welfare loss from patents is not universal. While patents restrict price competition, they may also provide static welfare benefits by improving incentives for marketing, which is a form of non-price competition. We show theoretically how stronger marketing incentives mitigate, and can even offset, the static costs of monopoly pricing. Empirical analysis in the pharmaceutical industry context suggests that, in the short-run, patent expirations reduce consumer welfare as a result of decreased marketing effort. In the long-run, patent expirations do benefit consumers, but by 30% less than would be implied by the reduction in price alone. The social value of monopoly marketing to consumers alone is roughly on par with its costs to firms. PMID:25221349

Does Intellectual Property Restrict Output? An Analysis of Pharmaceutical Markets.

PubMed

Lakdawalla, Darius; Philipson, Tomas

2012-02-01

Standard normative analysis of intellectual property focuses on the balance between incentives for research and the static welfare costs of reduced price-competition from monopoly. However, static welfare loss from patents is not universal. While patents restrict price competition, they may also provide static welfare benefits by improving incentives for marketing, which is a form of non -price competition. We show theoretically how stronger marketing incentives mitigate, and can even offset, the static costs of monopoly pricing. Empirical analysis in the pharmaceutical industry context suggests that, in the short-run, patent expirations reduce consumer welfare as a result of decreased marketing effort. In the long-run, patent expirations do benefit consumers, but by 30% less than would be implied by the reduction in price alone. The social value of monopoly marketing to consumers alone is roughly on par with its costs to firms.

Automatic Estimation of Verified Floating-Point Round-Off Errors via Static Analysis

NASA Technical Reports Server (NTRS)

Moscato, Mariano; Titolo, Laura; Dutle, Aaron; Munoz, Cesar A.

2017-01-01

This paper introduces a static analysis technique for computing formally verified round-off error bounds of floating-point functional expressions. The technique is based on a denotational semantics that computes a symbolic estimation of floating-point round-o errors along with a proof certificate that ensures its correctness. The symbolic estimation can be evaluated on concrete inputs using rigorous enclosure methods to produce formally verified numerical error bounds. The proposed technique is implemented in the prototype research tool PRECiSA (Program Round-o Error Certifier via Static Analysis) and used in the verification of floating-point programs of interest to NASA.

Dynamic Modeling of ALS Systems

NASA Technical Reports Server (NTRS)

Jones, Harry

2002-01-01

The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

Equipment and Protocols for Quasi-Static and Dynamic Tests of Very-High-Strength Concrete (VHSC) and High-Strength High-Ductility Concrete (HSHDC)

DTIC Science & Technology

2016-08-01

quasi -static mechanical properties, deformation behavior, and damage mechanisms in HSHDC and compare the behavior with VHSC. 2. Develop experimental ...using the experimental setup described in Chapter 6. The quasi -static strain rate was approximately 10-4/s. All panels tested have nominal dimensions...ER D C TR -1 6- 13 Force Protection Basing; TeCD 1a Equipment and Protocols for Quasi -Static and Dynamic Tests of Very-High-Strength

Comparison of forward flight effects theory of A. Michalke and U. Michel with measured data

NASA Technical Reports Server (NTRS)

Rawls, J. W., Jr.

1983-01-01

The scaling laws of a Michalke and Michel predict flyover noise of a single stream shock free circular jet from static data or static predictions. The theory is based on a farfield solution to Lighthill's equation and includes density terms which are important for heated jets. This theory is compared with measured data using two static jet noise prediction methods. The comparisons indicate the theory yields good results when the static noise levels are accurately predicted.

Analysis of an unswept propfan blade with a semiempirical dynamic stall model

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Kaza, K. R. V.

1989-01-01

The time history response of a propfan wind tunnel model with dynamic stall is studied analytically. The response obtained from the analysis is compared with available experimental data. The governing equations of motion are formulated in terms of blade normal modes which are calculated using the COSMIC-NASTRAN computer code. The response analysis considered the blade plunging and pitching motions. The lift, drag and moment coefficients for angles of attack below the static stall angle are obtained from a quasi-steady theory. For angles above static stall angles, a semiempirical dynamic stall model based on a correction to angle of attack is used to obtain lift, drag and moment coefficients. Using these coefficients, the aerodynamic forces are calculated at a selected number of strips, and integrated to obtain the total generalized forces. The combined momentum-blade element theory is used to calculate the induced velocity. The semiempirical stall model predicted a limit cycle oscillation near the setting angle at which large vibratory stresses were observed in an experiment. The predicted mode and frequency of oscillation also agreed with those measured in the experiment near the setting angle.

14 CFR 23.785 - Seats, berths, litters, safety belts, and shoulder harnesses.

Code of Federal Regulations, 2014 CFR

2014-01-01

... combination of structural analysis and static load tests to limit load; or (3) Static load tests to ultimate... OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY... resulting from the ultimate static load factors prescribed in § 23.561(b)(2) of this part. Each occupant...

14 CFR 23.785 - Seats, berths, litters, safety belts, and shoulder harnesses.

Code of Federal Regulations, 2011 CFR

2011-01-01

... combination of structural analysis and static load tests to limit load; or (3) Static load tests to ultimate... OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY... resulting from the ultimate static load factors prescribed in § 23.561(b)(2) of this part. Each occupant...

14 CFR 23.785 - Seats, berths, litters, safety belts, and shoulder harnesses.

Code of Federal Regulations, 2010 CFR

2010-01-01

... combination of structural analysis and static load tests to limit load; or (3) Static load tests to ultimate... OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY... resulting from the ultimate static load factors prescribed in § 23.561(b)(2) of this part. Each occupant...

14 CFR 23.785 - Seats, berths, litters, safety belts, and shoulder harnesses.

Code of Federal Regulations, 2012 CFR

2012-01-01

... combination of structural analysis and static load tests to limit load; or (3) Static load tests to ultimate... OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY... resulting from the ultimate static load factors prescribed in § 23.561(b)(2) of this part. Each occupant...

14 CFR 23.785 - Seats, berths, litters, safety belts, and shoulder harnesses.

Code of Federal Regulations, 2013 CFR

2013-01-01

... combination of structural analysis and static load tests to limit load; or (3) Static load tests to ultimate... OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY... resulting from the ultimate static load factors prescribed in § 23.561(b)(2) of this part. Each occupant...

Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.

PubMed

Brewer, Amandaa K; Striegel, André M

2011-04-15

The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The multidetector HDC results were also comparable to those obtained by transmission electron microscopy (TEM). Unlike off-line MALS or TEM, however, multidetector HDC is able to provide complete particle analysis based on the molar mass, size, shape, and compactness and their distributions for the entire sample population in less than 20 min. © 2011 American Chemical Society

Prediction of Mean and Design Fatigue Lives of Self Compacting Concrete Beams in Flexure

NASA Astrophysics Data System (ADS)

Goel, S.; Singh, S. P.; Singh, P.; Kaushik, S. K.

2012-02-01

In this paper, result of an investigation conducted to study the flexural fatigue characteristics of self compacting concrete (SCC) beams in flexure are presented. An experimental programme was planned in which approximately 60 SCC beam specimens of size 100 × 100 × 500 mm were tested under flexural fatigue loading. Approximately 45 static flexural tests were also conducted to facilitate fatigue testing. The flexural fatigue and static flexural strength tests were conducted on a 100 kN servo-controlled actuator. The fatigue life data thus obtained have been used to establish the probability distributions of fatigue life of SCC using two-parameter Weibull distribution. The parameters of the Weibull distribution have been obtained by different methods of analysis. Using the distribution parameters, the mean and design fatigue lives of SCC have been estimated and compared with Normally vibrated concrete (NVC), the data for which have been taken from literature. It has been observed that SCC exhibits higher mean and design fatigue lives compared to NVC.

Design of fiber optic probes for laser light scattering

NASA Technical Reports Server (NTRS)

Dhadwal, Harbans S.; Chu, Benjamin

1989-01-01

A quantitative analysis is presented of the role of optical fibers in laser light scattering. Design of a general fiber optic/microlens probe by means of ray tracing is described. Several different geometries employing an optical fiber of the type used in lightwave communications and a graded index microlens are considered. Experimental results using a nonimaging fiber optic detector probe show that due to geometrical limitations of single mode fibers, a probe using a multimode optical fiber has better performance, for both static and dynamic measurements of the scattered light intensity, compared with a probe using a single mode fiber. Fiber optic detector probes are shown to be more efficient at data collection when compared with conventional approaches to measurements of the scattered laser light. Integration of fiber optic detector probes into a fiber optic spectrometer offers considerable miniaturization of conventional light scattering spectrometers, which can be made arbitrarily small. In addition static and dynamic measurements of scattered light can be made within the scattering cell and consequently very close to the scattering center.

20 Meter Solar Sail Analysis and Correlation

NASA Technical Reports Server (NTRS)

Taleghani, B.; Lively, P.; Banik, J.; Murphy, D.; Trautt, T.

2005-01-01

This presentation discusses studies conducted to determine the element type and size that best represents a 20-meter solar sail under ground-test load conditions, the performance of test/Analysis correlation by using Static Shape Optimization Method for Q4 sail, and system dynamic. TRIA3 elements better represent wrinkle patterns than do QUAD3 elements Baseline, ten-inch elements are small enough to accurately represent sail shape, and baseline TRIA3 mesh requires a reasonable computation time of 8 min. 21 sec. In the test/analysis correlation by using Static shape optimization method for Q4 sail, ten parameters were chosen and varied during optimization. 300 sail models were created with random parameters. A response surfaces for each targets which were created based on the varied parameters. Parameters were optimized based on response surface. Deflection shape comparison for 0 and 22.5 degrees yielded a 4.3% and 2.1% error respectively. For the system dynamic study testing was done on the booms without the sails attached. The nominal boom properties produced a good correlation to test data the frequencies were within 10%. Boom dominated analysis frequencies and modes compared well with the test results.

An experimental and analytical investigation on the response of GR/EP composite I-frames

NASA Technical Reports Server (NTRS)

Moas, E., Jr.; Boitnott, R. L.; Griffin, O. H., Jr.

1991-01-01

Six-foot diameter, semicircular graphite/epoxy specimens representative of generic aircraft frames were loaded quasi-statically to determine their load response and failure mechanisms for large deflections that occur in an airplane crash. These frame-skin specimens consisted of a cylindrical skin section cocured with a semicircular I-frame. Various frame laminate stacking sequences and geometries were evaluated by statically loading the specimen until multiple failures occurred. Two analytical methods were compared for modeling the frame-skin specimens: a two-dimensional branched-shell finite element analysis and a one-dimensional, closed-form, curved beam solution derived using an energy method. Excellent correlation was obtained between experimental results and the finite element predictions of the linear response of the frames prior to the initial failure. The beam solution was used for rapid parameter and design studies, and was found to be stiff in comparison with the finite element analysis. The specimens were found to be useful for evaluating composite frame designs.

Advanced composite aileron for L-1011 transport aircraft: Design and analysis

NASA Technical Reports Server (NTRS)

Griffin, C. F.; Fogg, L. D.; Dunning, E. G.

1981-01-01

Detail design of the composite aileron has been completed. The aileron design is a multi-rib configuration with single piece upper and lower covers mechanically fastened to the substructure. Covers, front, spar and ribs are fabricated with graphite/epoxy tape or fabric composite material. The design has a weight savings of 23 percent compared to the aluminum aileron. The composite aileron has 50 percent fewer fasteners and parts than the metal aileron and is predicted to be cost competitive. Structural integrity of the composite aileron was verified by structural analysis and an extensive test program. Static, failsafe, and vibration analyses have been conducted on the composite aileron using finite element models and specialized computer programs for composite material laminates. The fundamental behavior of the composite materials used in the aileron was determined by coupon tests for a variety of environmental conditions. Critical details of the design were interrogated by static and fatigue tests on full-scale subcomponents and subassemblies of the aileron.

The analysis of non-linear dynamic behavior (including snap-through) of postbuckled plates by simple analytical solution

NASA Technical Reports Server (NTRS)

Ng, C. F.

1988-01-01

Static postbuckling and nonlinear dynamic analysis of plates are usually accomplished by multimode analyses, although the methods are complicated and do not give straightforward understanding of the nonlinear behavior. Assuming single-mode transverse displacement, a simple formula is derived for the transverse load displacement relationship of a plate under in-plane compression. The formula is used to derive a simple analytical expression for the static postbuckling displacement and nonlinear dynamic responses of postbuckled plates under sinusoidal or random excitation. Regions with softening and hardening spring behavior are identified. Also, the highly nonlinear motion of snap-through and its effects on the overall dynamic response can be easily interpreted using the single-mode formula. Theoretical results are compared with experimental results obtained using a buckled aluminum panel, using discrete frequency and broadband point excitation. Some important effects of the snap-through motion on the dynamic response of the postbuckled plates are found.

Animated graphics for comparing two risks: a cautionary tale.

PubMed

Zikmund-Fisher, Brian J; Witteman, Holly O; Fuhrel-Forbis, Andrea; Exe, Nicole L; Kahn, Valerie C; Dickson, Mark

2012-07-25

The increasing use of computer-administered risk communications affords the potential to replace static risk graphics with animations that use motion cues to reinforce key risk messages. Research on the use of animated graphics, however, has yielded mixed findings, and little research exists to identify the specific animations that might improve risk knowledge and patients' decision making. To test whether viewing animated forms of standard pictograph (icon array) risk graphics displaying risks of side effects would improve people's ability to select the treatment with the lowest risk profile, as compared with viewing static images of the same risks. A total of 4198 members of a demographically diverse Internet panel read a scenario about two hypothetical treatments for thyroid cancer. Each treatment was described as equally effective but varied in side effects (with one option slightly better than the other). Participants were randomly assigned to receive all risk information in 1 of 10 pictograph formats in a quasi-factorial design. We compared a control condition of static grouped icons with a static scattered icon display and with 8 Flash-based animated versions that incorporated different combinations of (1) building the risk 1 icon at a time, (2) having scattered risk icons settle into a group, or (3) having scattered risk icons shuffle themselves (either automatically or by user control). We assessed participants' ability to choose the better treatment (choice accuracy), their gist knowledge of side effects (knowledge accuracy), and their graph evaluation ratings, controlling for subjective numeracy and need for cognition. When compared against static grouped-icon arrays, no animations significantly improved any outcomes, and most showed significant performance degradations. However, participants who received animations of grouped icons in which at-risk icons appeared 1 at a time performed as well on all outcomes as the static grouped-icon control group. Displays with scattered icons (static or animated) performed particularly poorly unless they included the settle animation that allowed users to view event icons grouped. Many combinations of animation, especially those with scattered icons that shuffle randomly, appear to inhibit knowledge accuracy in this context. Static pictographs that group risk icons, however, perform very well on measures of knowledge and choice accuracy. These findings parallel recent evidence in other data communication contexts that less can be more-that is, that simpler, more focused information presentation can result in improved understanding. Decision aid designers and health educators should proceed with caution when considering the use of animated risk graphics to compare two risks, given that evidence-based, static risk graphics appear optimal.

Evaluation of Relationship between Trunk Muscle Endurance and Static Balance in Male Students

PubMed Central

Barati, Amirhossein; SafarCherati, Afsaneh; Aghayari, Azar; Azizi, Faeze; Abbasi, Hamed

2013-01-01

Purpose Fatigue of trunk muscle contributes to spinal instability over strenuous and prolonged physical tasks and therefore may lead to injury, however from a performance perspective, relation between endurance efficient core muscles and optimal balance control has not been well-known. The purpose of this study was to examine the relationship of trunk muscle endurance and static balance. Methods Fifty male students inhabitant of Tehran university dormitory (age 23.9±2.4, height 173.0±4.5 weight 70.7±6.3) took part in the study. Trunk muscle endurance was assessed using Sørensen test of trunk extensor endurance, trunk flexor endurance test, side bridge endurance test and static balance was measured using single-limb stance test. A multiple linear regression analysis was applied to test if the trunk muscle endurance measures significantly predicted the static balance. Results There were positive correlations between static balance level and trunk flexor, extensor and lateral endurance measures (Pearson correlation test, r=0.80 and P<0.001; r=0.71 and P<0.001; r=0.84 and P<0.001, respectively). According to multiple regression analysis for variables predicting static balance, the linear combination of trunk muscle endurance measures was significantly related to the static balance (F (3,46) = 66.60, P<0.001). Endurance of trunk flexor, extensor and lateral muscles were significantly associated with the static balance level. The regression model which included these factors had the sample multiple correlation coefficient of 0.902, indicating that approximately 81% of the variance of the static balance is explained by the model. Conclusion There is a significant relationship between trunk muscle endurance and static balance. PMID:24800004

Adaptive x-ray threat detection using sequential hypotheses testing with fan-beam experimental data (Conference Presentation)

NASA Astrophysics Data System (ADS)

Thamvichai, Ratchaneekorn; Huang, Liang-Chih; Ashok, Amit; Gong, Qian; Coccarelli, David; Greenberg, Joel A.; Gehm, Michael E.; Neifeld, Mark A.

2017-05-01

We employ an adaptive measurement system, based on sequential hypotheses testing (SHT) framework, for detecting material-based threats using experimental data acquired on an X-ray experimental testbed system. This testbed employs 45-degree fan-beam geometry and 15 views over a 180-degree span to generate energy sensitive X-ray projection data. Using this testbed system, we acquire multiple view projection data for 200 bags. We consider an adaptive measurement design where the X-ray projection measurements are acquired in a sequential manner and the adaptation occurs through the choice of the optimal "next" source/view system parameter. Our analysis of such an adaptive measurement design using the experimental data demonstrates a 3x-7x reduction in the probability of error relative to a static measurement design. Here the static measurement design refers to the operational system baseline that corresponds to a sequential measurement using all the available sources/views. We also show that by using adaptive measurements it is possible to reduce the number of sources/views by nearly 50% compared a system that relies on static measurements.

Static performance and noise tests on a thrust reverser for an augmentor wing aircraft

NASA Technical Reports Server (NTRS)

Harkonen, D. L.; Marrs, C. C.; Okeefe, J. V.

1974-01-01

A 1/3 scale model static test program was conducted to measure the noise levels and reverse thrust performance characteristics of wing-mounted thrust reverser that could be used on an advanced augmentor wing airplane. The configuration tested represents only the most fundamental designs where installation and packaging restraints are not considered. The thrust reverser performance is presented in terms of horizontal, vertical, and resultant effectiveness ratios and the reverser noise is compared on the basis of peak perceived noise level (PNL) and one-third octave band data (OASPL). From an analysis of the model force and acoustic data, an assessment is made on the stopping distance versus noise for a 90,900 kg (200,000 lb) airplane using this type of thrust reverser.

Differential Responses to a Visual Self-Motion Signal in Human Medial Cortical Regions Revealed by Wide-View Stimulation

PubMed Central

Wada, Atsushi; Sakano, Yuichi; Ando, Hiroshi

2016-01-01

Vision is important for estimating self-motion, which is thought to involve optic-flow processing. Here, we investigated the fMRI response profiles in visual area V6, the precuneus motion area (PcM), and the cingulate sulcus visual area (CSv)—three medial brain regions recently shown to be sensitive to optic-flow. We used wide-view stereoscopic stimulation to induce robust self-motion processing. Stimuli included static, randomly moving, and coherently moving dots (simulating forward self-motion). We varied the stimulus size and the presence of stereoscopic information. A combination of univariate and multi-voxel pattern analyses (MVPA) revealed that fMRI responses in the three regions differed from each other. The univariate analysis identified optic-flow selectivity and an effect of stimulus size in V6, PcM, and CSv, among which only CSv showed a significantly lower response to random motion stimuli compared with static conditions. Furthermore, MVPA revealed an optic-flow specific multi-voxel pattern in the PcM and CSv, where the discrimination of coherent motion from both random motion and static conditions showed above-chance prediction accuracy, but that of random motion from static conditions did not. Additionally, while area V6 successfully classified different stimulus sizes regardless of motion pattern, this classification was only partial in PcM and was absent in CSv. This may reflect the known retinotopic representation in V6 and the absence of such clear visuospatial representation in CSv. We also found significant correlations between the strength of subjective self-motion and univariate activation in all examined regions except for primary visual cortex (V1). This neuro-perceptual correlation was significantly higher for V6, PcM, and CSv when compared with V1, and higher for CSv when compared with the visual motion area hMT+. Our convergent results suggest the significant involvement of CSv in self-motion processing, which may give rise to its percept. PMID:26973588

Student perspectives on using egocentric video recorded by smart glasses to assess communicative and clinical skills with standardised patients.

PubMed

Zahl, D A; Schrader, S M; Edwards, P C

2018-05-01

This exploratory study evaluated student perceptions of their ability to self- and peer assess (i) interpersonal communication skills and (ii) clinical procedures (a head and neck examination) during standardised patient (SP) interactions recorded by Google Glass compared to a static camera. Students compared the Google Glass and static camera recordings using an instrument consisting of 20 Likert-type items and four open- and closed-text items. The Likert-type items asked students to rate how effectively they could assess specific aspects of interpersonal communication and a head and neck examination in these two different types of recordings. The interpersonal communication items included verbal, paraverbal and non-verbal subscales. The open- and closed-text items asked students to report on more globally the differences between the two types of recordings. Descriptive and inferential statistical analyses were conducted for all survey items. An inductive thematic analysis was conducted to determine qualitative emergent themes from the open-text questions. Students found the Glass videos more effective for assessing verbal (t 22 = 2.091, P = 0.048) and paraverbal communication skills (t 22 = 3.304, P = 0.003), whilst they reported that the static camera video was more effective for assessing non-verbal communication skills (t 22 = -2.132, P = 0.044). Four principle themes emerged from the students' open-text responses comparing Glass to static camera recordings for self- and peer assessment: (1) first-person perspective, (2) assessment of non-verbal communication, (3) audiovisual experience and (4) student operation of Glass. Our findings suggest that students perceive that Google Glass is a valuable tool for facilitating self- and peer assessment of SP examinations because of students' perceived ability to emphasise and illustrate communicative and clinical activities from a first-person perspective. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

New triangular and quadrilateral plate-bending finite elements

NASA Technical Reports Server (NTRS)

Narayanaswami, R.

1974-01-01

A nonconforming plate-bending finite element of triangular shape and associated quadrilateral elements are developed. The transverse displacement is approximated within the element by a quintic polynomial. The formulation takes into account the effects of transverse shear deformation. Results of the static and dynamic analysis of a square plate, with edges simply supported or clamped, are compared with exact solutions. Good accuracy is obtained in all calculations.

Combat Simulation Using Breach Computer Language

DTIC Science & Technology

1979-09-01

simulation and weapon system analysis computer language Two types of models were constructed: a stochastic duel and a dynamic engagement model The... duel model validates the BREACH approach by comparing results with mathematical solutions. The dynamic model shows the capability of the BREACH...BREACH 2 Background 2 The Language 3 Static Duel 4 Background and Methodology 4 Validation 5 Results 8 Tank Duel Simulation 8 Dynamic Assault Model

Static compression down-regulates N-cadherin expression and facilitates loss of cell phenotype of nucleus pulposus cells in a disc perfusion culture.

PubMed

Zhou, Haibo; Shi, Jianmin; Zhang, Chao; Li, Pei

2018-02-28

Mechanical compression often induces degenerative changes of disc nucleus pulposus (NP) tissue. It has been indicated that N-cadherin (N-CDH)-mediated signaling helps to preserve the NP cell phenotype. However, N-CDH expression and the resulting NP-specific phenotype alteration under the static compression and dynamic compression remain unclear. To study the effects of static compression and dynamic compression on N-CDH expression and NP-specific phenotype in an in vitro disc organ culture. Porcine discs were organ cultured in a self-developed mechanically active bioreactor for 7 days and subjected to static or dynamic compression (0.4 MPa for 2 h once per day). The noncompressed discs were used as controls. Compared with the dynamic compression, static compression significantly down-regulated the expression of N-CDH and NP-specific markers (laminin, brachyury, and keratin 19); decreased the Alcian Blue staining intensity, glycosaminoglycan and hydroxyproline contents; and declined the matrix macromolecule (aggrecan and collagen II) expression. Compared with the dynamic compression, static compression causes N-CDH down-regulation, loss of NP-specific phenotype, and the resulting decrease in NP matrix synthesis. © 2018 The Author(s).

A comparison of dynamic and static economic models of uneven-aged stand management

Treesearch

Robert G. Haight

1985-01-01

Numerical techniques have been used to compute the discrete-time sequence of residual diameter distributions that maximize the present net worth (PNW) of harvestable volume from an uneven-aged stand. Results contradicted optimal steady-state diameter distributions determined with static analysis. In this paper, optimality conditions for solutions to dynamic and static...

Relationships of bone characteristics in MYO9B deficient femurs.

PubMed

Kim, Do-Gyoon; Jeong, Yong-Hoon; McMichael, Brooke K; Bähler, Martin; Bodnyk, Kyle; Sedlar, Ryan; Lee, Beth S

2018-08-01

The objective of this study was to examine relationships among a variety of bone characteristics, including volumetric, mineral density, geometric, dynamic mechanical analysis, and static fracture mechanical properties. As MYO9B is an unconventional myosin in bone cells responsible for normal skeletal growth, bone characteristics of wild-type (WT), heterozygous (HET), and MYO9B knockout (KO) mice groups were compared as an animal model to express different bone quantity and quality. Forty-five sex-matched 12-week-old mice were used in this study. After euthanization, femurs were isolated and scanned using microcomputed tomography (micro-CT) to assess bone volumetric, tissue mineral density (TMD), and geometric parameters. Then, a non-destructive dynamic mechanical analysis (DMA) was performed by applying oscillatory bending displacement on the femur. Finally, the same femur was subject to static fracture testing. KO group had significantly lower length, bone mineral density (BMD), bone mass and volume, dynamic and static stiffness, and strength than WT and HET groups (p < 0.019). On the other hand, TMD parameters of KO group were comparable with those of WT group. HET group showed volumetric, geometric, and mechanical properties similar to WT group, but had lower TMD (p < 0.014). Non-destructive micro-CT and DMA parameters had significant positive correlations with strength (p < 0.015) without combined effect of groups and sex on the correlations (p > 0.077). This comprehensive characterization provides a better understanding of interactive behavior between the tissue- and organ-level of the same femur. The current findings elucidate that MYO9B is responsible for controlling bone volume to determine the growth rate and fracture risk of bone. Copyright © 2018 Elsevier Ltd. All rights reserved.

Numerical Modeling of Sliding Stability of RCC dam

NASA Astrophysics Data System (ADS)

Mughieda, O.; Hazirbaba, K.; Bani-Hani, K.; Daoud, W.

2017-06-01

Stability and stress analyses are the most important elements that require rigorous consideration in design of a dam structure. Stability of dams against sliding is crucial due to the substantial horizontal load that requires sufficient and safe resistance to develop by mobilization of adequate shearing forces along the base of the dam foundation. In the current research, the static sliding stability of a roller-compacted-concrete (RCC) dam was modelled using finite element method to investigate the stability against sliding. A commercially available finite element software (SAP 2000) was used to analyze stresses in the body of the dam and foundation. A linear finite element static analysis was performed in which a linear plane strain isoperimetric four node elements was used for modelling the dam-foundation system. The analysis was carried out assuming that no slip will occur at the interface between the dam and the foundation. Usual static loading condition was applied for the static analysis. The greatest tension was found to develop in the rock adjacent to the toe of the upstream slope. The factor of safety against sliding along the entire base of the dam was found to be greater than 1 (FS>1), for static loading conditions.

Comparison of Moist Static Energy and Budget between the GCM-Simulated Madden–Julian Oscillation and Observations over the Indian Ocean and Western Pacific

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

Wu, Xiaoqing; Deng, Liping

The moist static energy (MSE) anomalies and MSE budget associated with the Madden–Julian oscillation (MJO) simulated in the Iowa State University General Circulation Model (ISUGCM) over the Indian and Pacific Oceans are compared with observations. Different phase relationships between MJO 850-hPa zonal wind, precipitation, and surface latent heat flux are simulated over the Indian Ocean and western Pacific, which are greatly influenced by the convection closure, trigger conditions, and convective momentum transport (CMT). The moist static energy builds up from the lower troposphere 15–20 days before the peak of MJO precipitation, and reaches the maximum in the middle troposphere (500–600more » hPa) near the peak of MJO precipitation. The gradual lower-tropospheric heating and moistening and the upward transport of moist static energy are important aspects of MJO events, which are documented in observational studies but poorly simulated in most GCMs. The trigger conditions for deep convection, obtained from the year-long cloud resolving model (CRM) simulations, contribute to the striking difference between ISUGCM simulations with the original and modified convection schemes and play the major role in the improved MJO simulation in ISUGCM. Additionally, the budget analysis with the ISUGCM simulations shows the increase in MJO MSE is in phase with the horizontal advection of MSE over the western Pacific, while out of phase with the horizontal advection of MSE over the Indian Ocean. However, the NCEP analysis shows that the tendency of MJO MSE is in phase with the horizontal advection of MSE over both oceans.« less

Archer

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

Atzeni, Simone; Ahn, Dong; Gopalakrishnan, Ganesh

2017-01-12

Archer is built on top of the LLVM/Clang compilers that support OpenMP. It applies static and dynamic analysis techniques to detect data races in OpenMP programs generating a very low runtime and memory overhead. Static analyses identify data race free OpenMP regions and exclude them from runtime analysis, which is performed by ThreadSanitizer included in LLVM/Clang.

Static Analysis of Programming Exercises: Fairness, Usefulness and a Method for Application

ERIC Educational Resources Information Center

Nutbrown, Stephen; Higgins, Colin

2016-01-01

This article explores the suitability of static analysis techniques based on the abstract syntax tree (AST) for the automated assessment of early/mid degree level programming. Focus is on fairness, timeliness and consistency of grades and feedback. Following investigation into manual marking practises, including a survey of markers, the assessment…

An Economical Method for Static Headspace Enrichment for Arson Analysis

ERIC Educational Resources Information Center

Olesen, Bjorn

2010-01-01

Static headspace analysis of accelerants from suspected arsons is accomplished by placing an arson sample in a sealed container with a carbon strip suspended above the sample. The sample is heated, cooled to room temperature, and then the organic components are extracted from the carbon strip with carbon disulfide followed by gas chromatography…

Comparison of Static and Dynamic Balance in Female Collegiate Soccer, Basketball, and Gymnastics Athletes

PubMed Central

Bressel, Eadric; Yonker, Joshua C; Kras, John; Heath, Edward M

2007-01-01

Context: How athletes from different sports perform on balance tests is not well understood. When prescribing balance exercises to athletes in different sports, it may be important to recognize performance variations. Objective: To compare static and dynamic balance among collegiate athletes competing or training in soccer, basketball, and gymnastics. Design: A quasi-experimental, between-groups design. Independent variables included limb (dominant and nondominant) and sport played. Setting: A university athletic training facility. Patients or Other Participants: Thirty-four female volunteers who competed in National Collegiate Athletic Association Division I soccer (n = 11), basketball (n = 11), or gymnastics (n = 12). Intervention(s): To assess static balance, participants performed 3 stance variations (double leg, single leg, and tandem leg) on 2 surfaces (stiff and compliant). For assessment of dynamic balance, participants performed multidirectional maximal single-leg reaches from a unilateral base of support. Main Outcome Measure(s): Errors from the Balance Error Scoring System and normalized leg reach distances from the Star Excursion Balance Test were used to assess static and dynamic balance, respectively. Results: Balance Error Scoring System error scores for the gymnastics group were 55% lower than for the basketball group (P = .01), and Star Excursion Balance Test scores were 7% higher in the soccer group than the basketball group (P = .04). Conclusions: Gymnasts and soccer players did not differ in terms of static and dynamic balance. In contrast, basketball players displayed inferior static balance compared with gymnasts and inferior dynamic balance compared with soccer players. PMID:17597942

Applicability of contact angle techniques used in the analysis of contact lenses, part 1: comparative methodologies.

PubMed

Campbell, Darren; Carnell, Sarah Maria; Eden, Russell John

2013-05-01

Contact angle, as a representative measure of surface wettability, is often employed to interpret contact lens surface properties. The literature is often contradictory and can lead to confusion. This literature review is part of a series regarding the analysis of hydrogel contact lenses using contact angle techniques. Here we present an overview of contact angle terminology, methodology, and analysis. Having discussed this background material, subsequent parts of the series will discuss the analysis of contact lens contact angles and evaluate differences in published laboratory results. The concepts of contact angle, wettability and wetting are presented as an introduction. Contact angle hysteresis is outlined and highlights the advantages in using dynamic analytical techniques over static methods. The surface free energy of a material illustrates how contact angle analysis is capable of providing supplementary surface characterization. Although single values are able to distinguish individual material differences, surface free energy and dynamic methods provide an improved understanding of material behavior. The frequently used sessile drop, captive bubble, and Wilhelmy plate techniques are discussed. Their use as both dynamic and static methods, along with the advantages and disadvantages of each technique, is explained. No single contact angle technique fully characterizes the wettability of a material surface, and the application of complimenting methods allows increased characterization. At present, there is not an ISO standard method designed for soft materials. It is important that each contact angle technique has a standard protocol, as small protocol differences between laboratories often contribute to a variety of published data that are not easily comparable.

Rapid iterative reanalysis for automated design

NASA Technical Reports Server (NTRS)

Bhatia, K. G.

1973-01-01

A method for iterative reanalysis in automated structural design is presented for a finite-element analysis using the direct stiffness approach. A basic feature of the method is that the generalized stiffness and inertia matrices are expressed as functions of structural design parameters, and these generalized matrices are expanded in Taylor series about the initial design. Only the linear terms are retained in the expansions. The method is approximate because it uses static condensation, modal reduction, and the linear Taylor series expansions. The exact linear representation of the expansions of the generalized matrices is also described and a basis for the present method is established. Results of applications of the present method to the recalculation of the natural frequencies of two simple platelike structural models are presented and compared with results obtained by using a commonly applied analysis procedure used as a reference. In general, the results are in good agreement. A comparison of the computer times required for the use of the present method and the reference method indicated that the present method required substantially less time for reanalysis. Although the results presented are for relatively small-order problems, the present method will become more efficient relative to the reference method as the problem size increases. An extension of the present method to static reanalysis is described, ana a basis for unifying the static and dynamic reanalysis procedures is presented.

Radiotherapy volume delineation using dynamic [18F]-FDG PET/CT imaging in patients with oropharyngeal cancer: a pilot study.

PubMed

Silvoniemi, Antti; Din, Mueez U; Suilamo, Sami; Shepherd, Tony; Minn, Heikki

2016-11-01

Delineation of gross tumour volume in 3D is a critical step in the radiotherapy (RT) treatment planning for oropharyngeal cancer (OPC). Static [ 18 F]-FDG PET/CT imaging has been suggested as a method to improve the reproducibility of tumour delineation, but it suffers from low specificity. We undertook this pilot study in which dynamic features in time-activity curves (TACs) of [ 18 F]-FDG PET/CT images were applied to help the discrimination of tumour from inflammation and adjacent normal tissue. Five patients with OPC underwent dynamic [ 18 F]-FDG PET/CT imaging in treatment position. Voxel-by-voxel analysis was performed to evaluate seven dynamic features developed with the knowledge of differences in glucose metabolism in different tissue types and visual inspection of TACs. The Gaussian mixture model and K-means algorithms were used to evaluate the performance of the dynamic features in discriminating tumour voxels compared to the performance of standardized uptake values obtained from static imaging. Some dynamic features showed a trend towards discrimination of different metabolic areas but lack of consistency means that clinical application is not recommended based on these results alone. Impact of inflammatory tissue remains a problem for volume delineation in RT of OPC, but a simple dynamic imaging protocol proved practicable and enabled simple data analysis techniques that show promise for complementing the information in static uptake values.

Static and dynamic stability of pneumatic vibration isolators and systems of isolators

NASA Astrophysics Data System (ADS)

Ryaboy, Vyacheslav M.

2014-01-01

Pneumatic vibration isolation is the most widespread effective method for creating vibration-free environments that are vital for precise experiments and manufacturing operations in optoelectronics, life sciences, microelectronics, nanotechnology and other areas. The modeling and design principles of a dual-chamber pneumatic vibration isolator, basically established a few decades ago, continue to attract attention of researchers. On the other hand, behavior of systems of such isolators was never explained in the literature in sufficient detail. This paper covers a range of questions essential for understanding the mechanics of pneumatic isolation systems from both design and application perspectives. The theory and a model of a single standalone isolator are presented in concise form necessary for subsequent analysis. Then the dynamics of a system of isolators supporting a payload is considered with main attention directed to two aspects of their behavior: first, the static stability of payloads with high positions of the center of gravity; second, dynamic stability of the feedback system formed by mechanical leveling valves. The direct method of calculating the maximum stable position of the center of gravity is presented and illustrated by three-dimensional stability domains; analytic formulas are given that delineate these domains. A numerical method for feedback stability analysis of self-leveling valve systems is given, and the results are compared with the analytical estimates for a single isolator. The relation between the static and dynamic phenomena is discussed.

Theoretical studies on the molecular structure, conformational preferences, topological and vibrational analysis of allicin

NASA Astrophysics Data System (ADS)

Durlak, Piotr; Berski, Sławomir; Latajka, Zdzisław

2016-01-01

The molecular structure, conformational preferences, topological and vibrational analysis of allicin has been investigated at two different approaches. Calculations have been carried out on static (DFT and MP2) levels with an assortment of Dunning's basis sets and dynamic CPMD simulations. In this both case within the isolated molecule approximation. The results point out that at least twenty different conformers coexist on the PES as confirmed by the flexible character of this molecule. The topological analysis of ELF showed very similar nature of the Ssbnd S and Ssbnd O bonds. The infrared spectrum has been calculated, and a comparative vibrational analysis has been performed.

Enabling Rapid and Robust Structural Analysis During Conceptual Design

NASA Technical Reports Server (NTRS)

Eldred, Lloyd B.; Padula, Sharon L.; Li, Wu

2015-01-01

This paper describes a multi-year effort to add a structural analysis subprocess to a supersonic aircraft conceptual design process. The desired capabilities include parametric geometry, automatic finite element mesh generation, static and aeroelastic analysis, and structural sizing. The paper discusses implementation details of the new subprocess, captures lessons learned, and suggests future improvements. The subprocess quickly compares concepts and robustly handles large changes in wing or fuselage geometry. The subprocess can rank concepts with regard to their structural feasibility and can identify promising regions of the design space. The automated structural analysis subprocess is deemed robust and rapid enough to be included in multidisciplinary conceptual design and optimization studies.

Patellofemoral Pressure Changes After Static and Dynamic Medial Patellofemoral Ligament Reconstructions.

PubMed

Rood, Akkie; Hannink, Gerjon; Lenting, Anke; Groenen, Karlijn; Koëter, Sander; Verdonschot, Nico; van Kampen, Albert

2015-10-01

Reconstructing the medial patellofemoral ligament (MPFL) has become a key procedure for stabilizing the patella. Different techniques to reconstruct the MPFL have been described: static techniques in which the graft is fixed rigidly to the bone or dynamic techniques with soft tissue fixation. Static MPFL reconstruction is most commonly used. However, dynamic reconstruction deforms more easily and presumably functions more like the native MPFL. The aim of the study was to evaluate the effect of the different MPFL fixation techniques on patellofemoral pressures compared with the native situation. The hypothesis was that dynamic reconstruction would result in patellofemoral pressures closer to those generated in an intact knee. Controlled laboratory study. Seven fresh-frozen knee specimens were tested in an in vitro knee joint loading apparatus. Tekscan pressure-sensitive films fixed to the retropatellar cartilage measured mean patellofemoral and peak pressures, contact area, and location of the center of force (COF) at fixed flexion angles from 0° to 110°. Four different conditions were tested: intact, dynamic, partial dynamic, and static MPFL reconstruction. Data were analyzed using linear mixed models. Static MPFL reconstruction resulted in higher peak and mean pressures from 60° to 110° of flexion (P < .001). There were no differences in pressure between the 2 different dynamic reconstructions and the intact situation (P > .05). The COF in the static reconstruction group moved more medially on the patella from 50° to 110° of flexion compared with the other conditions. The contact area showed no significant differences between the test conditions. After static MPFL reconstruction, the patellofemoral pressures in flexion angles from 60° to 110° were 3 to 5 times higher than those in the intact situation. The pressures after dynamic MPFL reconstruction were similar as compared with those in the intact situation, and therefore, dynamic MPFL reconstruction could be a safer option than static reconstruction for stabilizing the patella. This study showed that static MPFL reconstruction results in higher patellofemoral pressures and thus enhances the chance of osteoarthritis in the long term, while dynamic reconstruction results in more normal pressures. © 2015 The Author(s).

Three list scheduling temporal partitioning algorithm of time space characteristic analysis and compare for dynamic reconfigurable computing

NASA Astrophysics Data System (ADS)

Chen, Naijin

2013-03-01

Level Based Partitioning (LBP) algorithm, Cluster Based Partitioning (CBP) algorithm and Enhance Static List (ESL) temporal partitioning algorithm based on adjacent matrix and adjacent table are designed and implemented in this paper. Also partitioning time and memory occupation based on three algorithms are compared. Experiment results show LBP partitioning algorithm possesses the least partitioning time and better parallel character, as far as memory occupation and partitioning time are concerned, algorithms based on adjacent table have less partitioning time and less space memory occupation.

A Comparative Study of the Application of FACTS Devices in Wind Power Plants of the Southeast Area of the Mexican Electric System

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

Beltran-Valle, Omar; Pena-Gallardo, Rafael; Segundo-Ramirez, Juan

This paper presents a comparative study of the application of Flexible AC Transmission System (FACTS) devices, as Thyristor Controlled Series Capacitor (TCSC), Static Synchronous Compensator (STATCOM) and Unified Power Controller (UPFC) on congestion management and voltage support in the area of the Istmo of Tehuantepec, Oaxaca, Mexico. The present work provides an analysis about the performance of the control of active and reactive power of the FACTS controllers applied to mentioned problems in the power system.

Photovoltaic pumping system - Comparative study analysis between direct and indirect coupling mode

NASA Astrophysics Data System (ADS)

Harrag, Abdelghani; Titraoui, Abdessalem; Bahri, Hamza; Messalti, Sabir

2017-02-01

In this paper, P&O algorithm is used in order to improve the performance of photovoltaic water pumping system in both dynamic and static response. The efficiency of the proposed algorithm has been studied successfully using a DC motor-pump powered using controller by thirty six PV modules via DC-DC boost converter derived by a P&O MPPT algorithm. Comparative study results between the direct and indirect modes coupling confirm that the proposed algorithm can effectively improve simultaneously: accuracy, rapidity, ripple and overshoot.

A combined static-dynamic single-dose imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT.

PubMed

Sciammarella, Maria; Shrestha, Uttam M; Seo, Youngho; Gullberg, Grant T; Botvinick, Elias H

2017-08-03

SPECT myocardial perfusion imaging (MPI) is a clinical mainstay that is typically performed with static imaging protocols and visually or semi-quantitatively assessed for perfusion defects based upon the relative intensity of myocardial regions. Dynamic cardiac SPECT presents a new imaging technique based on time-varying information of radiotracer distribution, which permits the evaluation of regional myocardial blood flow (MBF) and coronary flow reserve (CFR). In this work, a preliminary feasibility study was conducted in a small patient sample designed to implement a unique combined static-dynamic single-dose one-day visit imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT for improving the diagnosis of coronary artery disease (CAD). Fifteen patients (11 males, four females, mean age 71 ± 9 years) were enrolled for a combined dynamic and static SPECT (Infinia Hawkeye 4, GE Healthcare) imaging protocol with a single dose of 99m Tc-tetrofosmin administered at rest and a single dose administered at stress in a one-day visit. Out of 15 patients, eleven had selective coronary angiography (SCA), 8 within 6 months and the rest within 24 months of SPECT imaging, without intervening symptoms or interventions. The extent and severity of perfusion defects in each myocardial region was graded visually. Dynamically acquired data were also used to estimate the MBF and CFR. Both visually graded images and estimated CFR were tested against SCA as a reference to evaluate the validity of the methods. Overall, conventional static SPECT was normal in ten patients and abnormal in five patients, dynamic SPECT was normal in 12 patients and abnormal in three patients, and CFR from dynamic SPECT was normal in nine patients and abnormal in six patients. Among those 11 patients with SCA, conventional SPECT was normal in 5, 3 with documented CAD on SCA with an overall accuracy of 64%, sensitivity of 40% and specificity of 83%. Dynamic SPECT image analysis also produced a similar accuracy, sensitivity, and specificity. CFR was normal in 6, each with CAD on SCA with an overall accuracy of 91%, sensitivity of 80%, and specificity of 100%. The mean CFR was significantly lower for SCA detected abnormal than for normal patients (3.86±1.06 vs 1.94±0. 0.67, P < 0.001). The visually assessed image findings in static and dynamic SPECT are subjective, and may not reflect direct physiologic measures of coronary lesion based on SCA. The CFR measured with dynamic SPECT is fully objective, with better sensitivity and specificity, available only with the data generated from the dynamic SPECT method.

Influence of Dynamic Hydraulic Conditions on Nitrogen Cycling in Column Experiments

NASA Astrophysics Data System (ADS)

Gassen, Niklas; von Netzer, Frederick; Ryabenko, Evgenia; Lüders, Tillmann; Stumpp, Christine

2015-04-01

In order to improve management strategies of agricultural nitrogen input, it is of major importance to further understand which factors influence turnover processes within the nitrogen cycle. Many studies have focused on the fate of nitrate in hydrological systems, but up to date only little is known about the influence of dynamic hydraulic conditions on the fate of nitrate at the soil-groundwater interface. We conducted column experiments with natural sediment and compared a system with a fluctuating water table to systems with different water content and static conditions under the constant input of ammonia into the system. We used hydrochemical methods in order to trace nitrogen species, 15N isotope methods to get information about dominating turnover processes and microbial community analysis in order to connect hydrochemical and microbial information. We found that added ammonia was removed more effectively under dynamic hydraulic conditions than under static conditions. Furthermore, denitrification is the dominant process under saturated, static conditions, while nitrification is more important under unsaturated, static conditions. We conclude that a fluctuating water table creates hot spots where both nitrification and denitrification processes can occur spatially close to each other and therefore remove nitrogen more effectively from the system. Furthermore, the fluctuating water table enhances the exchange of solutes and triggers hot moments of solute turnover. Therefore we conclude that a fluctuating water table can amplify hot spots and trigger hot moments of nitrogen cycling.

Warm-up effects from concomitant use of vibration and static stretching after cycling.

PubMed

Yang, Wen-Wen; Liu, Chiang; Shiang, Tzyy-Yuang

2017-04-01

Static stretch is routinely used in traditional warm-up but impaired muscle performance. Combining vibration with static stretching as a feasible component may be an alternative to static stretching after submaximal aerobic exercise to improve jumping as well as flexibility. Therefore, the purpose of this study was to investigate and compare the effects of aerobic exercise, static stretching, and vibration with static stretching on flexibility and vertical jumping performance. A repeated measures experimental design was used in this study. Twelve participants randomly underwent 5 different warm-ups including cycling alone (C warm-up), static stretching alone (S warm-up), combining vibration with static stretching (VS warm-up), cycling followed by S (C+S warm-up), and cycling followed by VS (C+VS warm-up) on 5 separate days. Sit-and-reach, squat jump (SJ), and counter movement jump (CMJ) were measured for pre- and post- tests. The sit-and-reach scores after the S, VS, C+S and C+VS warm-ups were significantly enhanced (P<0.001), and were significantly greater than that of the C warm-up (P<0.05). The jumping height of SJ and CMJ after the C and C+VS warm-ups were significantly increased (P<0.05), whereas a significant reduction was found after the S warm-up (P<0.05). Vibration combined with stretching after submaximal cycling exercise (C+VS warm-up) could be a feasible warm-up protocol to improve both flexibility and vertical jump performance, compared with the traditional warm-up (C+S warm-up).

Relaxation mode analysis of a peptide system: comparison with principal component analysis.

PubMed

Mitsutake, Ayori; Iijima, Hiromitsu; Takano, Hiroshi

2011-10-28

This article reports the first attempt to apply the relaxation mode analysis method to a simulation of a biomolecular system. In biomolecular systems, the principal component analysis is a well-known method for analyzing the static properties of fluctuations of structures obtained by a simulation and classifying the structures into some groups. On the other hand, the relaxation mode analysis has been used to analyze the dynamic properties of homopolymer systems. In this article, a long Monte Carlo simulation of Met-enkephalin in gas phase has been performed. The results are analyzed by the principal component analysis and relaxation mode analysis methods. We compare the results of both methods and show the effectiveness of the relaxation mode analysis.

Comparing the Impact of Dynamic and Static Media on Students' Learning of One-Dimensional Kinematics

ERIC Educational Resources Information Center

Mešic, Vanes; Dervic, Dževdeta; Gazibegovic-Busuladžic, Azra; Salibašic, Džana; Erceg, Nataša

2015-01-01

In our study, we aimed to compare the impact of simulations, sequences of printed simulation frames and conventional static diagrams on the understanding of students with regard to the one-dimensional kinematics. Our student sample consisted of three classes of middle years students (N = 63; mostly 15 year-olds). These three classes served as…

Portal Venous Oxygen Persufflation of the Donation after Cardiac Death pancreas in a rat model is superior to static cold storage and hypothermic machine perfusion.

PubMed

Reddy, Mettu S; Carter, Noel; Cunningham, Anne; Shaw, James; Talbot, David

2014-06-01

Success of clinical pancreatic islet transplantation depends on the mass of viable islets transplanted and the proportion of transplanted islets that survive early ischaemia reperfusion injury. Novel pancreas preservation techniques to improve islet preservation and viability can increase the utilization of donation after cardiac death donor pancreases for islet transplantation. Rat pancreases were retrieved after 30 min of warm ischaemia and preserved by static cold storage, hypothermic machine perfusion or retrograde portal venous oxygen persufflation for 6 h. They underwent collagenase digestion and density gradient separation to isolate islets. The yield, viability, morphology were compared. In vitro function of isolated islets was compared using glucose stimulated insulin secretion test. Portal venous oxygen persufflation improved the islet yield, viability and morphology as compared to static cold storage. The percentage of pancreases with good in vitro function (stimulation index > 1.0) was also higher after oxygen persufflation as compared to static cold storage. Retrograde portal venous oxygen persufflation of donation after cardiac death donor rat pancreases has the potential to improve islet yield. © 2014 Steunstichting ESOT.

Dynamic and static fatigue behavior of sintered silicon nitrides

NASA Technical Reports Server (NTRS)

Chang, J.; Khandelwal, P.; Heitman, P. W.

1987-01-01

The dynamic and static fatigue behavior of Kyocera SN220M sintered silicon nitride at 1000 C was studied. Fractographic analysis of the material failing in dynamic fatigue revealed the presence of slow crack growth (SCG) at stressing rates below 41 MPa/min. Under conditions of static fatigue this material also displayed SCG at stresses below 345 MPa. SCG appears to be controlled by microcracking of the grain boundaries. The crack velocity exponent (n) determined from both dynamic and static fatigue tests ranged from 11 to 16.

Traditional Chinese Mind and Body Exercises for Promoting Balance Ability of Old Adults: A Systematic Review and Meta-Analysis

PubMed Central

Zhang, Yanjie; Wang, Yong Tai; Liu, Xiao Lei

2016-01-01

The purpose of this study was to provide a quantitative evaluation of the effectiveness of traditional Chinese mind and body exercises in promoting balance ability for old adults. The eligible studies were extensively searched from electronic databases (Medline, CINAHL, SportDicus, and Web of Science) until 10 May 2016. Reference lists of relevant publications were screened for future hits. The trials used randomized controlled approaches to compare the effects of traditional Chinese mind and body exercise (TCMBE) on balance ability of old adults that were included. The synthesized results of Berg Balance Scale (BBS), Timed Up and Go Test (TUG), and static balance with 95% confidence intervals were counted under a random-effects model. Ten studies were selected based on the inclusion criteria, and a total of 1,798 participants were involved in this review. The results of the meta-analysis showed that TCMBE had no significant improvement on BBS and TUG, but the BBS and TUG could be obviously improved by prolonging the intervention time. In addition, the results showed that TCMBE could significantly improve the static balance compared to control group. In conclusion, old adults who practiced TCMBE with the time not less than 150 minutes per week for more than 15 weeks could promote the balance ability. PMID:27990168

Traditional Chinese Mind and Body Exercises for Promoting Balance Ability of Old Adults: A Systematic Review and Meta-Analysis.

PubMed

Chen, Shihui; Zhang, Yanjie; Wang, Yong Tai; Liu, Xiao Lei

2016-01-01

The purpose of this study was to provide a quantitative evaluation of the effectiveness of traditional Chinese mind and body exercises in promoting balance ability for old adults. The eligible studies were extensively searched from electronic databases (Medline, CINAHL, SportDicus, and Web of Science) until 10 May 2016. Reference lists of relevant publications were screened for future hits. The trials used randomized controlled approaches to compare the effects of traditional Chinese mind and body exercise (TCMBE) on balance ability of old adults that were included. The synthesized results of Berg Balance Scale (BBS), Timed Up and Go Test (TUG), and static balance with 95% confidence intervals were counted under a random-effects model. Ten studies were selected based on the inclusion criteria, and a total of 1,798 participants were involved in this review. The results of the meta-analysis showed that TCMBE had no significant improvement on BBS and TUG, but the BBS and TUG could be obviously improved by prolonging the intervention time. In addition, the results showed that TCMBE could significantly improve the static balance compared to control group. In conclusion, old adults who practiced TCMBE with the time not less than 150 minutes per week for more than 15 weeks could promote the balance ability.

DARKDROID: Exposing the Dark Side of Android Marketplaces

DTIC Science & Technology

2016-06-01

Moreover, our approaches can detect apps containing both intentional and unintentional vulnerabilities, such as unsafe code loading mechanisms and...Security, Static Analysis, Dynamic Analysis, Malware Detection , Vulnerability Scanning 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18...applications in a DoD context. ................... 1 1.2.2 Develop sophisticated whole-system static analyses to detect malicious Android applications

Effective Use of Multimedia Presentations to Maximize Learning within High School Science Classrooms

ERIC Educational Resources Information Center

Rapp, Eric

2013-01-01

This research used an evidenced-based experimental 2 x 2 factorial design General Linear Model with Repeated Measures Analysis of Covariance (RMANCOVA). For this analysis, time served as the within-subjects factor while treatment group (i.e., static and signaling, dynamic and signaling, static without signaling, and dynamic without signaling)…

Microbial communities acclimate to recurring changes in soil redox potential status

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

DeAngelis, Kristen M.; Silver, Whendee; Thompson, Andrew

Rapidly fluctuating environmental conditions can significantly stress organisms, particularly when fluctuations cross thresholds of normal physiological tolerance. Redox potential fluctuations are common in humid tropical soils, and microbial community acclimation or avoidance strategies for survival will in turn shape microbial community diversity and biogeochemistry. To assess the extent to which indigenous bacterial and archaeal communities are adapted to changing in redox potential, soils were incubated under static anoxic, static oxic or fluctuating redox potential conditions, and the standing (DNA-based) and active (RNA-based) communities and biogeochemistry were determined. Fluctuating redox potential conditions permitted simultaneous CO{sub 2} respiration, methanogenesis, N{sub 2}O productionmore » and iron reduction. Exposure to static anaerobic conditions significantly changed community composition, while 4-day redox potential fluctuations did not. Using RNA: DNA ratios as a measure of activity, 285 taxa were more active under fluctuating than static conditions, compared with three taxa that were more active under static compared with fluctuating conditions. These data suggest an indigenous microbialcommunity adapted to fluctuating redox potential.« less

Prediction of unsuppressed jet engine exhaust noise in flight from static data

NASA Technical Reports Server (NTRS)

Stone, J. R.

1980-01-01

A methodology developed for predicting in-flight exhaust noise from static data is presented and compared with experimental data for several unsuppressed turbojet engines. For each engine, static data over a range of jet velocities are compared with the predicted jet mixing noise and shock-cell noise. The static engine noise over and above the jet and shock noises is identified as excess noise. The excess noise data are then empirically correlated to smooth the spectral and directivity relations and account for variations in test conditions. This excess noise is then projected to flight based on the assumption that the only effects of flight are a Doppler frequency shift and a level change given by 40 log (1 - m sub 0 cos theta), where M sub 0 is the flight Mach number and theta is the observer angle relative to the jet axis.

Esterified sago waste for engine oil removal in aqueous environment.

PubMed

Ngaini, Zainab; Noh, Farid; Wahi, Rafeah

2014-01-01

Agro-waste from the bark of Metroxylon sagu (sago) was studied as a low cost and effective oil sorbent in dry and aqueous environments. Sorption study was conducted using untreated sago bark (SB) and esterified sago bark (ESB) in used engine oil. Characterization study showed that esterification has successfully improved the hydrophobicity, buoyancy, surface roughness and oil sorption capacity of ESB. Sorption study revealed that water uptake of SB is higher (30 min static: 2.46 g/g, dynamic: 2.67 g/g) compared with ESB (30 min static: 0.18 g/g, dynamic: 0.14 g/g). ESB, however, showed higher oil sorption capacity in aqueous environment (30 min static: 2.30 g/g, dynamic: 2.14) compared with SB (30 min static: 0 g/g, dynamic: 0 g/g). ESB has shown great poTENTial as effective oil sorbent in aqueous environment due to its high oil sorption capacity, low water uptake and high buoyancy.

Do Dynamic Compared to Static Facial Expressions of Happiness and Anger Reveal Enhanced Facial Mimicry?

PubMed Central

Rymarczyk, Krystyna; Żurawski, Łukasz; Jankowiak-Siuda, Kamila; Szatkowska, Iwona

2016-01-01

Facial mimicry is the spontaneous response to others’ facial expressions by mirroring or matching the interaction partner. Recent evidence suggested that mimicry may not be only an automatic reaction but could be dependent on many factors, including social context, type of task in which the participant is engaged, or stimulus properties (dynamic vs static presentation). In the present study, we investigated the impact of dynamic facial expression and sex differences on facial mimicry and judgment of emotional intensity. Electromyography recordings were recorded from the corrugator supercilii, zygomaticus major, and orbicularis oculi muscles during passive observation of static and dynamic images of happiness and anger. The ratings of the emotional intensity of facial expressions were also analysed. As predicted, dynamic expressions were rated as more intense than static ones. Compared to static images, dynamic displays of happiness also evoked stronger activity in the zygomaticus major and orbicularis oculi, suggesting that subjects experienced positive emotion. No muscles showed mimicry activity in response to angry faces. Moreover, we found that women exhibited greater zygomaticus major muscle activity in response to dynamic happiness stimuli than static stimuli. Our data support the hypothesis that people mimic positive emotions and confirm the importance of dynamic stimuli in some emotional processing. PMID:27390867

The First Static and Dynamic Analysis of 3-D Printed Sintered Ceramics for Body Armor Applications

DTIC Science & Technology

2016-09-01

evaluate sintered alumina tiles produced by 3-D printing methodology. This report examines the static and quasi -static parameters (including density...Figures iv List of Tables iv Acknowledgments v 1. Introduction 1 2. Processing and Experimental Procedures 1 3. Results and Discussion 7 4...6 Fig. 8 Experimental setup for recording fracture .............................................7 Fig. 9 Rod projectile

Flexible chain molecules in the marginal and concentrated regimes: universal static scaling laws and cross-over predictions.

PubMed

Laso, Manuel; Karayiannis, Nikos Ch

2008-05-07

We present predictions for the static scaling exponents and for the cross-over polymer volumetric fractions in the marginal and concentrated solution regimes. Corrections for finite chain length are made. Predictions are based on an analysis of correlated fluctuations in density and chain length, in a semigrand ensemble in which mers and solvent sites exchange identities. Cross-over volumetric fractions are found to be chain length independent to first order, although reciprocal-N corrections are also estimated. Predicted scaling exponents and cross-over regimes are compared with available data from extensive off-lattice Monte Carlo simulations [Karayiannis and Laso, Phys. Rev. Lett. 100, 050602 (2008)] on freely jointed, hard-sphere chains of average lengths from N=12-500 and at packing densities from dilute ones up to the maximally random jammed state.

Analysis of metal transfer in gas metal arc welding

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

Kim, Y.S.; Eager, T.W.

1993-06-01

Droplet sizes produced in GMAW are predicted using both the static force balance theory and the pinch instability theory as a function of welding current, and the results are compared with experimental measurements. The causes for the deviation of predicted droplet size from measured size are discussed with suggestions for modification of the theories in order to more accurately model metal transfer in GMAW. The mechanism of repelled metal transfer is also discussed. The transition of metal transfer mode has been considered as a critical phenomenon which changes dramatically over a narrow range of welding current. This transition has beenmore » investigated experimentally using high-speed videography which shows that the transition is much more gradual than is generally believed. The mechanism of the transition is discussed using a modified static force balance theory.« less

Finite element analysis and performance study of switched reluctance generator

NASA Astrophysics Data System (ADS)

Zhang, Qianhan; Guo, Yingjun; Xu, Qi; Yu, Xiaoying; Guo, Yajie

2017-03-01

Analyses a three-phase 12/8 switched reluctance generator (SRG) which is based on its structure and performance principle. The initial size data were calculated by MathCAD, and the simulation model was set up in the ANSOFT software environment with the maximum efficiency and the maximum output power as the main reference parameters. The outer diameter of the stator and the inner diameter of the rotor were parameterized. The static magnetic field distribution, magnetic flux, magnetic energy, torque, inductance characteristics, back electromotive force and phase current waveform of SRG is obtained by analyzing the static magnetic field and the steady state motion of two-dimensional transient magnetic field in ANSOFT environment. Finally, the experimental data of the prototype are compared with the simulation results, which provide a reliable basis for the design and research of SRG wind turbine system.

Restoration of Static JPEG Images and RGB Video Frames by Means of Nonlinear Filtering in Conditions of Gaussian and Non-Gaussian Noise

NASA Astrophysics Data System (ADS)

Sokolov, R. I.; Abdullin, R. R.

2017-11-01

The use of nonlinear Markov process filtering makes it possible to restore both video stream frames and static photos at the stage of preprocessing. The present paper reflects the results of research in comparison of these types image filtering quality by means of special algorithm when Gaussian or non-Gaussian noises acting. Examples of filter operation at different values of signal-to-noise ratio are presented. A comparative analysis has been performed, and the best filtered kind of noise has been defined. It has been shown the quality of developed algorithm is much better than quality of adaptive one for RGB signal filtering at the same a priori information about the signal. Also, an advantage over median filter takes a place when both fluctuation and pulse noise filtering.

Thrust imbalance of the Space Shuttle solid rocket motors

NASA Technical Reports Server (NTRS)

Foster, W. A., Jr.; Sforzini, R. H.; Shackelford, B. W., Jr.

1981-01-01

The Monte Carlo statistical analysis of thrust imbalance is applied to both the Titan IIIC and the Space Shuttle solid rocket motors (SRMs) firing in parallel, and results are compared with those obtained from the Space Shuttle program. The test results are examined in three phases: (1) pairs of SRMs selected from static tests of the four developmental motors (DMs 1 through 4); (2) pairs of SRMs selected from static tests of the three quality assurance motors (QMs 1 through 3); (3) SRMs on the first flight test vehicle (STS-1A and STS-1B). The simplified internal ballistic model utilized for computing thrust from head-end pressure measurements on flight tests is shown to agree closely with measured thrust data. Inaccuracies in thrust imbalance evaluation are explained by possible flight test instrumentation errors.

Physical Fitness For Futsal Referee Of Football Association In Thailand

NASA Astrophysics Data System (ADS)

Thaweesub Koeipakvaen Acting Sub L., t.

2018-01-01

The purpose of the research to study physical fitness for futsal Referee of Football Association in Thailand and Compare of the Physical Fitness for first level, second and third futsal Referee of Football Association in Thailand. The population of first level, second and third level futsal Referee of Football Association in Thailand 107 person. The sample were futsal Referee of Football Association in Thailand 97 person. First level futsal Referee 22 person. Second level futsal Referee 11 person. Third level futsal Referee 64 person. The instrument used was futsal physical fitness test of Football Association in Thailand. Endurance Test (1,000 meter), Speed Test (4x10 meter) 2 time, and Agility Test (80 meter) 2 time. The statistic for data analysis were one way Anova, Percentage, Mean, Standard Deviation and F-test. The results were as the follow: (1) the result comparing F-test first level futsal referee with level second and first level futsal referee with third level. the statically significant different at the 0.05 level, and the result comparing Endurance as the follow the Physical Fitness for first level, second and third futsal Referee. the statically significant different at the 0.05 level.

A comparative analysis of numerical approaches to the mechanics of elastic sheets

NASA Astrophysics Data System (ADS)

Taylor, Michael; Davidovitch, Benny; Qiu, Zhanlong; Bertoldi, Katia

2015-06-01

Numerically simulating deformations in thin elastic sheets is a challenging problem in computational mechanics due to destabilizing compressive stresses that result in wrinkling. Determining the location, structure, and evolution of wrinkles in these problems has important implications in design and is an area of increasing interest in the fields of physics and engineering. In this work, several numerical approaches previously proposed to model equilibrium deformations in thin elastic sheets are compared. These include standard finite element-based static post-buckling approaches as well as a recently proposed method based on dynamic relaxation, which are applied to the problem of an annular sheet with opposed tractions where wrinkling is a key feature. Numerical solutions are compared to analytic predictions of the ground state, enabling a quantitative evaluation of the predictive power of the various methods. Results indicate that static finite element approaches produce local minima that are highly sensitive to initial imperfections, relying on a priori knowledge of the equilibrium wrinkling pattern to generate optimal results. In contrast, dynamic relaxation is much less sensitive to initial imperfections and can generate low-energy solutions for a wide variety of loading conditions without requiring knowledge of the equilibrium solution beforehand.

Immediate Effects of Proprioceptive Neuromuscular Facilitation Stretching Programs Compared With Passive Stretching Programs for Hamstring Flexibility: A Critically Appraised Topic.

PubMed

Hill, Kristian J; Robinson, Kendall P; Cuchna, Jennifer W; Hoch, Matthew C

2017-11-01

Clinical Scenario: Increasing hamstring flexibility through clinical stretching interventions may be an effective means to prevent hamstring injuries. However the most effective method to increase hamstring flexibility has yet to be determined. For a healthy individual, are proprioceptive neuromuscular facilitation (PNF) stretching programs more effective in immediately improving hamstring flexibility when compared with static stretching programs? Summary of Key Findings: A thorough literature search returned 195 possible studies; 5 studies met the inclusion criteria and were included. Current evidence supports the use of PNF stretching or static stretching programs for increasing hamstring flexibility. However, neither program demonstrated superior effectiveness when examining immediate increases in hamstring flexibility. Clinical Bottom Line: There were consistent findings from multiple low-quality studies that indicate there is no difference in the immediate improvements in hamstring flexibility when comparing PNF stretching programs to static stretching programs in physically active adults. Strength of Recommendation: Grade B evidence exists that PNF and static stretching programs equally increase hamstring flexibility immediately following the stretching program.

In-flight measurement of the National Oceanic and Atmospheric Administration (NOAA)-10 static Earth sensor error

NASA Technical Reports Server (NTRS)

Harvie, E.; Filla, O.; Baker, D.

1993-01-01

Analysis performed in the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) measures error in the static Earth sensor onboard the National Oceanic and Atmospheric Administration (NOAA)-10 spacecraft using flight data. Errors are computed as the difference between Earth sensor pitch and roll angle telemetry and reference pitch and roll attitude histories propagated by gyros. The flight data error determination illustrates the effect on horizon sensing of systemic variation in the Earth infrared (IR) horizon radiance with latitude and season, as well as the effect of anomalies in the global IR radiance. Results of the analysis provide a comparison between static Earth sensor flight performance and that of scanning Earth sensors studied previously in the GSFC/FDD. The results also provide a baseline for evaluating various models of the static Earth sensor. Representative days from the NOAA-10 mission indicate the extent of uniformity and consistency over time of the global IR horizon. A unique aspect of the NOAA-10 analysis is the correlation of flight data errors with independent radiometric measurements of stratospheric temperature. The determination of the NOAA-10 static Earth sensor error contributes to realistic performance expectations for missions to be equipped with similar sensors.

Increased Dynamics of Tricarboxylic Acid Cycle and Glutamate Synthesis in Obese Adipose Tissue

PubMed Central

Nagao, Hirofumi; Nishizawa, Hitoshi; Bamba, Takeshi; Nakayama, Yasumune; Isozumi, Noriyoshi; Nagamori, Shushi; Kanai, Yoshikatsu; Tanaka, Yoshimitsu; Kita, Shunbun; Fukuda, Shiro; Funahashi, Tohru; Maeda, Norikazu; Fukusaki, Eiichiro; Shimomura, Iichiro

2017-01-01

Obesity is closely associated with various metabolic disorders. However, little is known about abnormalities in the metabolic change of obese adipose tissue. Here we use static metabolic analysis and in vivo metabolic turnover analysis to assess metabolic dynamics in obese mice. The static metabolic analyses showed that glutamate and constitutive metabolites of the TCA cycle were increased in the white adipose tissue (WAT) of ob/ob and diet-induced obesity mice but not in the liver or skeletal muscle of these obese mice. Moreover, in vivo metabolic turnover analyses demonstrated that these glucose-derived metabolites were dynamically and specifically produced in obese WAT compared with lean WAT. Glutamate rise in obese WAT was associated with down-regulation of glutamate aspartate transporter (GLAST), a major glutamate transporter for adipocytes, and low uptake of glutamate into adipose tissue. In adipocytes, glutamate treatment reduced adiponectin secretion and insulin-mediated glucose uptake and phosphorylation of Akt. These data suggest that a high intra-adipocyte glutamate level potentially relates to adipocyte dysfunction in obesity. This study provides novel insights into metabolic dysfunction in obesity through comprehensive application of in vivo metabolic turnover analysis in two obese animal models. PMID:28119455

The influence of ZrO2/20%Y2O3 and Al2O3 deposited coatings to the behavior of an aluminum alloy subjected to mechanical shock

NASA Astrophysics Data System (ADS)

Pintilei, G. L.; Crismaru, V. I.; Abrudeanu, M.; Munteanu, C.; Luca, D.; Istrate, B.

2015-10-01

Aluminum alloys are used in the aerospace industry due to their good mechanical properties and their low density compared with the density of steels. Usually the parts made of aluminum alloys contribute to the structural frame of aircrafts and they must withstand static and variable mechanical loads and also mechanical loads applied in a very short time which determine different phenomenon's in the material behavior then static or fatigue loads. This paper analysis the resilience of a 2024 aluminum alloy subjected to shock loads and the way how a coating can improve its behavior. For improving the behavior two coatings were considered: Al2O3 with 99.5% purity and ZrO2/20%Y2O3. The coatings were deposited on the base material by plasma spraying. The samples with and without coating were subject to mechanical shock to determine the resilience of the materials and the cracks propagation was investigated using SEM analysis. To highlight the physical phenomenon's that appear in the samples during the mechanical shock, explicit finite element analysis were done using Ansys 14.5 software.

Static strain and vibration characteristics of a metal semimonocoque helicopter tail cone of moderate size

NASA Technical Reports Server (NTRS)

Bielawa, Richard L.; Hefner, Rachel E.; Castagna, Andre

1991-01-01

The results are presented of an analytic and experimental research program involving a Sikorsky S-55 helicopter tail cone directed ultimately to the improved structural analysis of airframe substructures typical of moderate sized helicopters of metal semimonocoque construction. Experimental static strain and dynamic shake-testing measurements are presented. Correlation studies of each of these tests with a PC-based finite element analysis (COSMOS/M) are described. The tests included static loadings at the end of the tail cone supported in the cantilever configuration as well as vibrational shake-testing in both the cantilever and free-free configurations.

Investigating the Magnetic Interaction with Geomag and Tracker Video Analysis: Static Equilibrium and Anharmonic Dynamics

ERIC Educational Resources Information Center

Onorato, P.; Mascheretti, P.; DeAmbrosis, A.

2012-01-01

In this paper, we describe how simple experiments realizable by using easily found and low-cost materials allow students to explore quantitatively the magnetic interaction thanks to the help of an Open Source Physics tool, the Tracker Video Analysis software. The static equilibrium of a "column" of permanents magnets is carefully investigated by…

Dead zone analysis of ECAL barrel modules under static and dynamic load

NASA Astrophysics Data System (ADS)

Pierre-Emile, T.; Anduze, M.

2018-03-01

In the context of ILD project, impact studies of environmental loads on the Electromagnetic CALorimeter (ECAL) have been initiated. The ECAL part considered is the barrel and it consists of several independent modules which are mounted on the Hadronic CALorimeter barrel (HCAL) itself mounted on the cryostat coil and the yoke. The estimate of the gap required between each ECAL modules is fundamental to define the assembly step and avoid mechanical contacts over the barrel lifetime. In the meantime, it has to be done in consideration to the dead spaces reduction and detector hermiticity optimization. Several Finite Element Analysis (FEA) with static and dynamic loads have been performed in order to define correctly the minimum values for those gaps. Due to the implantation site of the whole project in Japan, seismic analysis were carried out in addition to the static ones. This article shows results of these analysis done with the Finite Element Method (FEM) in ANSYS. First results show the impact of HCAL design on the ECAL modules motion in static load. The second study dedicated to seismic approach on a larger model (including yoke and cryostat) gives additional results on earthquake consequences.

Predicting System Accidents with Model Analysis During Hybrid Simulation

NASA Technical Reports Server (NTRS)

Malin, Jane T.; Fleming, Land D.; Throop, David R.

2002-01-01

Standard discrete event simulation is commonly used to identify system bottlenecks and starving and blocking conditions in resources and services. The CONFIG hybrid discrete/continuous simulation tool can simulate such conditions in combination with inputs external to the simulation. This provides a means for evaluating the vulnerability to system accidents of a system's design, operating procedures, and control software. System accidents are brought about by complex unexpected interactions among multiple system failures , faulty or misleading sensor data, and inappropriate responses of human operators or software. The flows of resource and product materials play a central role in the hazardous situations that may arise in fluid transport and processing systems. We describe the capabilities of CONFIG for simulation-time linear circuit analysis of fluid flows in the context of model-based hazard analysis. We focus on how CONFIG simulates the static stresses in systems of flow. Unlike other flow-related properties, static stresses (or static potentials) cannot be represented by a set of state equations. The distribution of static stresses is dependent on the specific history of operations performed on a system. We discuss the use of this type of information in hazard analysis of system designs.

Failure mechanics in low-velocity impacts on thin composite plates

NASA Technical Reports Server (NTRS)

Elber, W.

1983-01-01

Eight-ply quasi-isotropic composite plates of Thornel 300 graphite in Narmco 5208 epoxy resin (T300/5208) were tested to establish the degree of equivalence between low-velocity impact and static testing. Both the deformation and failure mechanics under impact were representable by static indentation tests. Under low-velocity impacts such as tool drops, the dominant deformation mode of the plates was the first, or static, mode. Higher modes are excited on contact, but they decay significantly by the time the first-mode load reaches a maximum. The delamination patterns were observed by X-ray analysis. The areas of maximum delamination patterns were observed by X-ray analysis. The areas of maximum delamination coincided with the areas of highest peel stresses. The extent of delamination was similar for static and impact tests. Fiber failure damage was established by tensile tests on small fiber bundles obtained by deplying test specimens. The onset of fiber damage was in internal plies near the lower surface of the plates. The distribution and amount of fiber damage was similar fo impact and static tests.

Balance, dizziness and proprioception in patients with chronic whiplash associated disorders complaining of dizziness: A prospective randomized study comparing three exercise programs.

PubMed

Treleaven, Julia; Peterson, Gunnel; Ludvigsson, Maria Landén; Kammerlind, Ann-Sofi; Peolsson, Anneli

2016-04-01

Dizziness and unsteadiness are common symptoms following a whiplash injury. To compare the effect of 3 exercise programs on balance, dizziness, proprioception and pain in patients with chronic whiplash complaining of dizziness. A sub-analysis of a randomized study. One hundred and forty subjects were randomized to either a physiotherapist-guided neck-specific exercise (NSE), physiotherapist-guided neck-specific exercise, with a behavioural approach (NSEB) or prescription of general physical activity (PPA) group. Pre intervention, 3, 6 and 12 months post baseline they completed the University of California Los Angeles Dizziness Questionnaire (UCLA-DQ), Visual Analogue Scales (VAS) for, dizziness at rest and during activity and physical measures (static and dynamic clinical balance tests and head repositioning accuracy (HRA)). There were significant time by group differences with respect to dizziness during activity and UCLA-Q favouring the physiotherapy led neck specific exercise group with a behavioural approach. Within group analysis of changes over time also revealed significant changes in most variables apart from static balance. Between and within group comparisons suggest that physiotherapist led neck exercise groups including a behavioural approach had advantages in improving measures of dizziness compared with the general physical activity group, although many still complained of dizziness and balance impairment. Future studies should consider exercises specifically designed to address balance, dizziness and cervical proprioception in those with persistent whiplash. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Static analysis of the hull plate using the finite element method

NASA Astrophysics Data System (ADS)

Ion, A.

2015-11-01

This paper aims at presenting the static analysis for two levels of a container ship's construction as follows: the first level is at the girder / hull plate and the second level is conducted at the entire strength hull of the vessel. This article will describe the work for the static analysis of a hull plate. We shall use the software package ANSYS Mechanical 14.5. The program is run on a computer with four Intel Xeon X5260 CPU processors at 3.33 GHz, 32 GB memory installed. In terms of software, the shared memory parallel version of ANSYS refers to running ANSYS across multiple cores on a SMP system. The distributed memory parallel version of ANSYS (Distributed ANSYS) refers to running ANSYS across multiple processors on SMP systems or DMP systems.

Effects of quadriceps strength after static and dynamic whole-body vibration exercise.

PubMed

Bush, Jill A; Blog, Gabriel L; Kang, Jie; Faigenbaum, Avery D; Ratamess, Nicholas A

2015-05-01

Numerous studies have shown performance benefits including whole-body vibration (WBV) as a training modality or an acute exercise protocol when used as a component of the resistance training program. Some studies have indicated that performing dynamic exercises as compared with static position exercises while exposed to WBV might be beneficial; however, evidence is lacking. Thus, the purpose of this study was to determine if an acute bout of dynamic versus static squats performed during WBV results in increase in quadriceps force production by means of dynamic isokinetic knee extension and flexion exercise. Nonresistance-trained healthy young men and women (N = 21) of 18-25 years participated in 4 protocols with 2-week rest in-between. Protocol 1 consisted of 5 sets of 10 dynamic squats without vibration; Protocol 2: 5 sets of 30-second static squats without vibration; Protocol 3: 5 sets of 10 dynamic squats with 30-Hz WBV for a total of 2.5 minutes; and Protocol 4: 5 sets of 30-second static squats with 30-Hz WBV for a total of 2.5 minutes. Prestrength tests (1 set of 4 repetitions at 100° · s(-1) for the knee extension exercise) was performed within 5 minutes of starting each protocol, and poststrength testing was performed within 1 minute of completing each protocol. Strength outcomes were analyzed by repeated measures analysis of variance with a significance level set at p ≤ 0.05. A significant decrease in strength was observed after dynamic and static squats without WBV (p = 0.002); an increase in strength after dynamic squats with WBV (p = 0.003); and a decrease in strength after static squats with WBV (p = 0.003). The inclusion of WBV to dynamic resistance exercise can be an added modality to increase strength. Whole-body vibration can have varied effects in altering muscle strength in untrained individuals according to the type of resistance training performed. As a dynamic squat with WBV seems to immediately potentiate neuromuscular functioning, the combination of dynamic exercises and WBV could be used as a potential warm-up procedure before resistance exercise.

Statistical analysis of traversal behavior under different types of traffic lights

NASA Astrophysics Data System (ADS)

Wang, Boran; Wang, Ziyang; Li, Zhiyin

2017-12-01

According to the video observation, it is found that the traffic signal type signal has a significant effect on the illegal crossing behavior of pedestrians at the intersection. Through the method of statistical analysis and variance analysis, the difference between the violation rate and the waiting position of pedestrians at different intersecting lights is compared, and the influence of traffic signal type on pedestrian crossing behavior is evaluated. The results show that the violation rate of the intersection of the static pedestrian lights is significantly higher than that of the countdown signal lights. There are significant differences in the waiting position of the intersection of different signal lights.

Modeling the Structural Dynamic of Industrial Networks

NASA Astrophysics Data System (ADS)

Wilkinson, Ian F.; Wiley, James B.; Lin, Aizhong

Market systems consist of locally interacting agents who continuously pursue advantageous opportunities. Since the time of Adam Smith, a fundamental task of economics has been to understand how market systems develop and to explain their operation. During the intervening years, theory largely has stressed comparative statics analysis. Based on the assumptions of rational, utility or profit-maximizing agents, and negative, diminishing returns) feedback process, traditional economic analysis seeks to describe the, generally) unique state of an economy corresponding to an initial set of assumptions. The analysis is tatic in the sense that it does not describe the process by which an economy might get from one state to another.

Finite element analysis of metal matrix composite blade

NASA Astrophysics Data System (ADS)

Isai Thamizh, R.; Velmurugan, R.; Jayagandhan, R.

2016-10-01

In this work, compressor rotor blade of a gas turbine engine has been analyzed for stress, maximum displacement and natural frequency using ANSYS software for determining its failure strength by simulating the actual service conditions. Static stress analysis and modal analysis have been carried out using Ti-6Al-4V alloy, which is currently used in compressor blade. The results are compared with those obtained using Ti matrix composites reinforced with SiC. The advantages of using metal matrix composites in the gas turbine compressor blades are investigated. From the analyses carried out, it seems that composite rotor blades have lesser mass, lesser tip displacement and lower maximum stress values.

Analysis of heat-transfer tests of an impingement-convection- and film-cooled vane in a cascade

NASA Technical Reports Server (NTRS)

Gladden, H. J.; Gauntner, D. J.; Livingood, J. N. B.

1971-01-01

Experimental flow and heat transfer data obtained for an air-cooled turbine vane tested in a static cascade at gas temperatures and pressures to 1644 K (2500 F) and 31 N/cm2 (45 psia), respectively, are presented. Average and local vane temperatures were correlated in several ways. Calculated and measured coolant flows and vane temperatures are compared. Potential allowable increases in gas temperature are also discussed.

Enhancement of matrix production and cell proliferation in human annulus cells under bioreactor culture.

PubMed

Yang, Xinlin; Wang, Daidong; Hao, Jianrong; Gong, Meiqing; Arlet, Vincent; Balian, Gary; Shen, Francis H; Li, Xudong Joshua

2011-06-01

Tissue engineering is a promising approach for treatment of disc degeneration. Herein, we evaluated effects of rotating bioreactor culture on the extracellular matrix production and proliferation of human annulus fibrosus (AF) cells. AF cells were embedded into alginate beads, and then cultured up to 3 weeks in a rotating wall vessel bioreactor or a static vessel. By real-time reverse transcription-polymerase chain reaction, expression of aggrecan, collagen type I and type II, and collagen prolyl 4-hydroxylase II was remarkably elevated, whereas expression of matrix metalloproteinase 3 and a disintegrin and metalloproteinase with thrombospondin motifs 5 was significantly decreased under bioreactor. Biochemical analysis revealed that the levels of the whole cell-associated proteoglycan and collagen were approximately five- and twofolds in rotating bioreactor, respectively, compared to those in static culture. Moreover, AF cell proliferation was augmented in rotating bioreactor. DNA contents were threefolds higher in rotating bioreactor than that in static culture. Expression of the proliferating cell nuclear antigen was robustly enhanced in rotating bioreactor as early as 1 week. Our findings suggested that rotating bioreactor culture would be an effective technique for expansion of human annulus cells for tissue engineering driven treatment of disc degeneration.

Tadpole-improved SU(2) lattice gauge theory

NASA Astrophysics Data System (ADS)

Shakespeare, Norman H.; Trottier, Howard D.

1999-01-01

A comprehensive analysis of tadpole-improved SU(2) lattice gauge theory is made. Simulations are done on isotropic and anisotropic lattices, with and without improvement. Two tadpole renormalization schemes are employed, one using average plaquettes, the other using mean links in the Landau gauge. Simulations are done with spatial lattice spacings as in the range of about 0.1-0.4 fm. Results are presented for the static quark potential, the renormalized lattice anisotropy at/as (where at is the ``temporal'' lattice spacing), and for the scalar and tensor glueball masses. Tadpole improvement significantly reduces discretization errors in the static quark potential and in the scalar glueball mass, and results in very little renormalization of the bare anisotropy that is input to the action. We also find that tadpole improvement using mean links in the Landau gauge results in smaller discretization errors in the scalar glueball mass (as well as in the static quark potential), compared to when average plaquettes are used. The possibility is also raised that further improvement in the scalar glueball mass may result when the coefficients of the operators which correct for discretization errors in the action are computed beyond the tree level.

An analysis of the effects of aeroelasticity on static longitudinal stability and control of a swept-wing airplane

NASA Technical Reports Server (NTRS)

Skoog, Richard B

1957-01-01

A theoretical analysis has been made of the effects of aeroelasticity on the static longitudinal stability and elevator angle required for balance of an airplane. The analysis is based on the familiar stability equation expressing the contribution of wing and tail to longitudinal stability. Effects of wing, tail, and fuselage flexibility are considered. Calculated effects are shown for a swept-wing bomber of relatively high flexibility.

MSC products for the simulation of tire behavior

NASA Technical Reports Server (NTRS)

Muskivitch, John C.

1995-01-01

The modeling of tires and the simulation of tire behavior are complex problems. The MacNeal-Schwendler Corporation (MSC) has a number of finite element analysis products that can be used to address the complexities of tire modeling and simulation. While there are many similarities between the products, each product has a number of capabilities that uniquely enable it to be used for a specific aspect of tire behavior. This paper discusses the following programs: (1) MSC/NASTRAN - general purpose finite element program for linear and nonlinear static and dynamic analysis; (2) MSC/ADAQUS - nonlinear statics and dynamics finite element program; (3) MSC/PATRAN AFEA (Advanced Finite Element Analysis) - general purpose finite element program with a subset of linear and nonlinear static and dynamic analysis capabilities with an integrated version of MSC/PATRAN for pre- and post-processing; and (4) MSC/DYTRAN - nonlinear explicit transient dynamics finite element program.

A two-step FEM-SEM approach for wave propagation analysis in cable structures

NASA Astrophysics Data System (ADS)

Zhang, Songhan; Shen, Ruili; Wang, Tao; De Roeck, Guido; Lombaert, Geert

2018-02-01

Vibration-based methods are among the most widely studied in structural health monitoring (SHM). It is well known, however, that the low-order modes, characterizing the global dynamic behaviour of structures, are relatively insensitive to local damage. Such local damage may be easier to detect by methods based on wave propagation which involve local high frequency behaviour. The present work considers the numerical analysis of wave propagation in cables. A two-step approach is proposed which allows taking into account the cable sag and the distribution of the axial forces in the wave propagation analysis. In the first step, the static deformation and internal forces are obtained by the finite element method (FEM), taking into account geometric nonlinear effects. In the second step, the results from the static analysis are used to define the initial state of the dynamic analysis which is performed by means of the spectral element method (SEM). The use of the SEM in the second step of the analysis allows for a significant reduction in computational costs as compared to a FE analysis. This methodology is first verified by means of a full FE analysis for a single stretched cable. Next, simulations are made to study the effects of damage in a single stretched cable and a cable-supported truss. The results of the simulations show how damage significantly affects the high frequency response, confirming the potential of wave propagation based methods for SHM.

Hallux valgus surgery may produce early improvements in balance control: results of a cross-sectional pilot study.

PubMed

Sadra, Saba; Fleischer, Adam; Klein, Erin; Grewal, Gurtej S; Knight, Jessica; Weil, Lowell Scott; Weil, Lowell; Najafi, Bijan

2013-01-01

Hallux valgus (HV) is associated with poorer performance during gait and balance tasks and is an independent risk factor for falls in older adults. We sought to assess whether corrective HV surgery improves gait and balance. Using a cross-sectional study design, gait and static balance data were obtained from 40 adults: 19 patients with HV only (preoperative group), 10 patients who recently underwent successful HV surgery (postoperative group), and 11 control participants. Assessments were made in the clinic using body-worn sensors. Patients in the preoperative group generally demonstrated poorer static balance control compared with the other two groups. Despite similar age and body mass index, postoperative patients exhibited 29% and 63% less center of mass sway than preoperative patients during double-and single-support balance assessments, respectively (analysis of variance P =.17 and P =.14, respectively [both eyes open condition]). Overall, gait performance was similar among the groups, except for speed during gait initiation, where lower speeds were encountered in the postoperative group compared with the preoperative group (Scheffe P = .049). This study provides supportive evidence regarding the benefits of corrective lower-extremity surgery on certain aspects of balance control. Patients seem to demonstrate early improvements in static balance after corrective HV surgery, whereas gait improvements may require a longer recovery time. Further research using a longitudinal study design and a larger sample size capable of assessing the long-term effects of HV surgical correction on balance and gait is probably warranted.

Design and Static Analysis of Airlesstyre to Reduce Deformation

NASA Astrophysics Data System (ADS)

Mathew, Nibin Jacob; Sahoo, Dillip Kumar; Mithun Chakravarthy, E.

2017-05-01

In this work a model of an air less tire is introduced with a replacement of natural rubber materials in place of synthetic rubber in tread and polyester in place of nylon in carcass. The construction and material study of various types of air less tyre is done by comparing with pneumatic tire. A brief structural study has been done on spokes of airless tyre and analyzed by ANSYS software. Analysis has been carried out on various structures like honey comb, Spokes, triangular and diamond with an applied load of 1200N. Comparison study has been carried out among various structures with different materials and it study shows that tyre with diamond structure with synthetic materials gives less deformation compared to other structure

Radar cross section models for limited aspect angle windows

NASA Astrophysics Data System (ADS)

Robinson, Mark C.

1992-12-01

This thesis presents a method for building Radar Cross Section (RCS) models of aircraft based on static data taken from limited aspect angle windows. These models statistically characterize static RCS. This is done to show that a limited number of samples can be used to effectively characterize static aircraft RCS. The optimum models are determined by performing both a Kolmogorov and a Chi-Square goodness-of-fit test comparing the static RCS data with a variety of probability density functions (pdf) that are known to be effective at approximating the static RCS of aircraft. The optimum parameter estimator is also determined by the goodness of-fit tests if there is a difference in pdf parameters obtained by the Maximum Likelihood Estimator (MLE) and the Method of Moments (MoM) estimators.

Modeling analysis of pulsed magnetization process of magnetic core based on inverse Jiles-Atherton model

NASA Astrophysics Data System (ADS)

Liu, Yi; Zhang, He; Liu, Siwei; Lin, Fuchang

2018-05-01

The J-A (Jiles-Atherton) model is widely used to describe the magnetization characteristics of magnetic cores in a low-frequency alternating field. However, this model is deficient in the quantitative analysis of the eddy current loss and residual loss in a high-frequency magnetic field. Based on the decomposition of magnetization intensity, an inverse J-A model is established which uses magnetic flux density B as an input variable. Static and dynamic core losses under high frequency excitation are separated based on the inverse J-A model. Optimized parameters of the inverse J-A model are obtained based on particle swarm optimization. The platform for the pulsed magnetization characteristic test is designed and constructed. The hysteresis curves of ferrite and Fe-based nanocrystalline cores at high magnetization rates are measured. The simulated and measured hysteresis curves are presented and compared. It is found that the inverse J-A model can be used to describe the magnetization characteristics at high magnetization rates and to separate the static loss and dynamic loss accurately.

Analyzing discharge strategies during acute care: a discrete-event simulation study.

PubMed

Crawford, Elizabeth A; Parikh, Pratik J; Kong, Nan; Thakar, Charuhas V

2014-02-01

We developed a discrete-event simulation model of patient pathway through an acute care hospital that comprises an ED and several inpatient units. The effects of discharge timing on ED waiting and boarding times, ambulance diversions, leave without treatment, and readmissions were explicitly modeled. We then analyzed the impact of 1 static and 2 proactive discharge strategies on these system outcomes. Our analysis indicated that although the 2 proactive discharge strategies significantly reduced ED waiting and boarding times, and several other measures, compared with the static strategy (P < 0.01), the number of readmissions increased substantially. Further analysis indicated that these findings are sensitive to changes in patient arrival rate and conditions for ambulance diversion. Determining the appropriate time to discharge patients not only can affect individual patients' health outcomes, but also can affect various aspects of the hospital. The study improves our understanding of how individual inpatient discharge decisions can be objectively viewed in terms of their impact on other operations, such as ED crowding and readmission, in an acute care hospital.

Effect of static electronic advertising signs on road safety: an experimental case study.

PubMed

Izadpanah, Pedram; Omrani, Reza; Koo, Sheldon; Hadayeghi, Ali

2014-01-01

As technology continues to advance, the outdoor advertising industry is taking advantage of electronic signs, some of which are static electronic signs (SES), with the ability to automatically change the message shown on the sign at regular intervals. Studies indicate that SES has a negative impact on the drivers' visual attention and on vehicle control. However, the actual effects of the SES on the number of collisions have been difficult to prove conclusively. The objective of this article is to generate a clear understanding of the safety impacts of SES on the number collisions by conducting a before-and-after analysis with comparison groups. The analysis was based on a total of 10 SES along the Highway 27 and the Gardiner Expressway of the city of Toronto. The results of the before-and-after study revealed that there was not enough evidence to suggest that these signs have any impact on road safety along the adjacent roadway sections at a 95% confidence interval. The same results were obtained by comparing collisions that occurred during daylight and artificial light.

Development of the Main Wing Structure of a High Altitude Long Endurance UAV

NASA Astrophysics Data System (ADS)

Park, Sang Wook; Shin, Jeong Woo; Kim, Tae-Uk

2018-04-01

To enhance the flight endurance of a HALE UAV, the main wing of the UAV should have a high aspect ratio and low structural weight. Since a main wing constructed with the thin walled and slender components needed for low structural weight can suffer catastrophic failure during flight, it is important to develop a light-weight airframe without sacrificing structural integrity. In this paper, the design of the main wing of the HALE UAV was conducted using spars which were composed of a carbon-epoxy cylindrical tube and bulkheads to achieve both the weight reduction and structural integrity. The spars were sized using numerical analysis considering non-linear deformation under bending moment. Static strength testing of the wing was conducted under the most critical load condition. Then, the experimental results obtained for the wing were compared to the analytical result from the non-linear finite-element analysis. It was found that the developed main wing reduced its structural weight without any failure under the ultimate load condition of the static strength testing.

Microbubble Enzyme-Linked Immunosorbent Assay for the Detection of Targeted Microbubbles in in Vitro Static Binding Assays.

PubMed

Wischhusen, Jennifer; Padilla, Frederic

2017-07-01

Targeted microbubbles (MBs) are ultrasound contrast agents that are functionalized with a ligand for ultrasound molecular imaging of endothelial markers. Novel targeted MBs are characterized in vitro by incubation in protein-coated wells, followed by binding quantification by microscopy or ultrasound imaging. Both methods provide operator-dependent results: Between 3 and 20 fields of view from a heterogeneous sample are typically selected for analysis by microscopy, and in ultrasound imaging, different acoustic settings affect signal intensities. This study proposes a new method to reproducibly quantify MB binding based on enzyme-linked immunosorbent assay (ELISA), in which bound MBs are revealed with an enzyme-linked antibody. MB-ELISA was adapted to in vitro static binding assays, incubating the MBs in inverted position or by agitation, and compared with microscopy. The specificity and sensitivity of MB-ELISA enable the reliable quantification of MB binding in a rapid, high-throughput and whole-well analysis, facilitating the characterization of new targeted contrast agents. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Comparison of different biopsy forceps models for tissue sampling in eosinophilic esophagitis.

PubMed

Bussmann, Christian; Schoepfer, Alain M; Safroneeva, Ekaterina; Haas, Nadine; Godat, Sébastien; Sempoux, Christine; Simon, Hans-Uwe; Straumann, Alex

2016-12-01

Background and aims: Eosinophilic esophagitis (EoE) is a mixed inflammatory and fibrostenotic disease. Unlike superficial inflammatory changes, subepithelial fibrosis is not routinely sampled in esophageal biopsies. This study aimed to evaluate the efficacy and safety of deep esophageal sampling with four different types of biopsy forceps. Patients and methods: In this cross-sectional study, esophageal biopsies were taken in 30 adult patients by one expert endoscopist. Biopsies sampled from distal esophagus using a static jaw forceps (Olympus, FB-11K-1) were compared with proximal biopsies sampled with static jaw (Olympus, FB-45Q-1), alligator jaw (Olympus, FB-210K), and large-capacity forceps (Boston Scientific, Radial Jaw 4). One pathologist calculated the surface area of epithelial and subepithelial layers in hematoxylin and eosin (H&E)-stained biopsies. Results: Subepithelial tissue was acquired in 97 % (static jaw FB-11K-1), 93 % (static jaw FB-45Q-1), 80 % (alligator jaw), and 55 % (large-capacity) of samples. Median (interquartile [IQR]) ratios of surface area of epithelial to subepithelial tissue were: static jaw FB-45Q-1, 1.07 (0.65 - 4.465); static jaw FB-11K-1, 1.184 (0.608 - 2.545); alligator jaw, 2.353 (1.312 - 4.465); and large-capacity, 2.71 (1.611 - 4.858). The static jaw models obtained a larger surface area of subepithelial tissue compared with the alligator jaw ( P  < 0.001 and P  = 0.037, for FB-11K-1 and FB-45Q-1, respectively) and the large-capacity forceps ( P  < 0.001, for both static jaw models). No esophageal perforations occurred. Conclusions: The static jaw forceps models allowed sampling of subepithelial tissue in > 90 % of biopsies and appear to be superior to alligator or large-capacity forceps in sampling larger amounts of subepithelial tissue. © Georg Thieme Verlag KG Stuttgart · New York.

Pile Driving Analysis for Pile Design and Quality Assurance

DOT National Transportation Integrated Search

2017-08-01

Driven piles are commonly used in foundation engineering. The most accurate measurement of pile capacity is achieved from measurements made during static load tests. Static load tests, however, may be too expensive for certain projects. In these case...

Novel parametric reduced order model for aeroengine blade dynamics

NASA Astrophysics Data System (ADS)

Yuan, Jie; Allegri, Giuliano; Scarpa, Fabrizio; Rajasekaran, Ramesh; Patsias, Sophoclis

2015-10-01

The work introduces a novel reduced order model (ROM) technique to describe the dynamic behavior of turbofan aeroengine blades. We introduce an equivalent 3D frame model to describe the coupled flexural/torsional mode shapes, with their relevant natural frequencies and associated modal masses. The frame configurations are identified through a structural identification approach based on a simulated annealing algorithm with stochastic tunneling. The cost functions are constituted by linear combinations of relative errors associated to the resonance frequencies, the individual modal assurance criteria (MAC), and on either overall static or modal masses. When static masses are considered the optimized 3D frame can represent the blade dynamic behavior with an 8% error on the MAC, a 1% error on the associated modal frequencies and a 1% error on the overall static mass. When using modal masses in the cost function the performance of the ROM is similar, but the overall error increases to 7%. The approach proposed in this paper is considerably more accurate than state-of-the-art blade ROMs based on traditional Timoshenko beams, and provides excellent accuracy at reduced computational time when compared against high fidelity FE models. A sensitivity analysis shows that the proposed model can adequately predict the global trends of the variations of the natural frequencies when lumped masses are used for mistuning analysis. The proposed ROM also follows extremely closely the sensitivity of the high fidelity finite element models when the material parameters are used in the sensitivity.

Speckle temporal stability in XAO coronagraphic images. II. Refine model for quasi-static speckle temporal evolution for VLT/SPHERE

NASA Astrophysics Data System (ADS)

Martinez, P.; Kasper, M.; Costille, A.; Sauvage, J. F.; Dohlen, K.; Puget, P.; Beuzit, J. L.

2013-06-01

Context. Observing sequences have shown that the major noise source limitation in high-contrast imaging is the presence of quasi-static speckles. The timescale on which quasi-static speckles evolve is determined by various factors, mechanical or thermal deformations, among others. Aims: Understanding these time-variable instrumental speckles and, especially, their interaction with other aberrations, referred to as the pinning effect, is paramount for the search for faint stellar companions. The temporal evolution of quasi-static speckles is, for instance, required for quantifying the gain expected when using angular differential imaging (ADI) and to determining the interval on which speckle nulling techniques must be carried out. Methods: Following an early analysis of a time series of adaptively corrected, coronagraphic images obtained in a laboratory condition with the high-order test bench (HOT) at ESO Headquarters, we confirm our results with new measurements carried out with the SPHERE instrument during its final test phase in Europe. The analysis of the residual speckle pattern in both direct and differential coronagraphic images enables the characterization of the temporal stability of quasi-static speckles. Data were obtained in a thermally actively controlled environment reproducing realistic conditions encountered at the telescope. Results: The temporal evolution of the quasi-static wavefront error exhibits a linear power law, which can be used to model quasi-static speckle evolution in the context of forthcoming high-contrast imaging instruments, with implications for instrumentation (design, observing strategies, data reduction). Such a model can be used for instance to derive the timescale on which non-common path aberrations must be sensed and corrected. We found in our data that quasi-static wavefront error increases with ~0.7 Å per minute.

Correction of static axial alignment in children with knee varus or valgus deformities through guided growth: Does it also correct dynamic frontal plane moments during walking?

PubMed

Böhm, Harald; Stief, Felix; Sander, Klaus; Hösl, Matthias; Döderlein, Leonhard

2015-09-01

Malaligned knees are predisposed to the development and progression of unicompartmental degenerations because of the excessive load placed on one side of the knee. Therefore, guided growth in skeletally immature patients is recommended. Indication for correction of varus/valgus deformities are based on static weight bearing radiographs. However, the dynamic knee abduction moment during walking showed only a weak correlation to malalignment determined by static radiographs. Therefore, the aim of the study was to measure the effects of guided growth on the normalization of frontal plane knee joint moments during walking. 15 legs of 8 patients (11-15 years) with idiopathic axial varus or valgus malalignment were analyzed. 16 typically developed peers served as controls. Instrumented gait analysis and clinical assessment were performed the day before implantation and explantation of eight-plates. Correlation between static mechanical tibiofemoral axis angle (MAA) and dynamic frontal plane knee joint moments and their change by guided growth were performed. The changes in dynamic knee moment in the frontal plane following guided growth showed high and significant correlation to the changes in static MAA (R=0.97, p<0.001). Contrary to the correlation of the changes, there was no correlation between static and dynamic measures in both sessions. In consequence two patients that had a natural knee moment before treatment showed a more pathological one after treatment. In conclusion, the changes in the dynamic load situation during walking can be predicted from the changes in static alignment. If pre-surgical gait analysis reveals a natural load situation, despite a static varus or valgus deformity, the intervention must be critically discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Instance Analysis for the Error of Three-pivot Pressure Transducer Static Balancing Method for Hydraulic Turbine Runner

NASA Astrophysics Data System (ADS)

Weng, Hanli; Li, Youping

2017-04-01

The working principle, process device and test procedure of runner static balancing test method by weighting with three-pivot pressure transducers are introduced in this paper. Based on an actual instance of a V hydraulic turbine runner, the error and sensitivity of the three-pivot pressure transducer static balancing method are analysed. Suggestions about improving the accuracy and the application of the method are also proposed.

STATIC AND KINETIC SITE-SPECIFIC PROTEIN-DNA PHOTOCROSSLINKING: ANALYSIS OF BACTERIAL TRANSCRIPTION INITIATION COMPLEXES

PubMed Central

Naryshkin, Nikolai; Druzhinin, Sergei; Revyakin, Andrei; Kim, Younggyu; Mekler, Vladimir; Ebright, Richard H.

2009-01-01

Static site-specific protein-DNA photocrosslinking permits identification of protein-DNA interactions within multiprotein-DNA complexes. Kinetic site-specific protein-DNA photocrosslinking--involving rapid-quench-flow mixing and pulsed-laser irradiation--permits elucidation of pathways and kinetics of formation of protein-DNA interactions within multiprotein-DNA complexes. We present detailed protocols for application of static and kinetic site-specific protein-DNA photocrosslinking to bacterial transcription initiation complexes. PMID:19378179

iTrack: instrumented mobile electrooculography (EOG) eye-tracking in older adults and Parkinson's disease.

PubMed

Stuart, Samuel; Hickey, Aodhán; Galna, Brook; Lord, Sue; Rochester, Lynn; Godfrey, Alan

2017-01-01

Detection of saccades (fast eye-movements) within raw mobile electrooculography (EOG) data involves complex algorithms which typically process data acquired during seated static tasks only. Processing of data during dynamic tasks such as walking is relatively rare and complex, particularly in older adults or people with Parkinson's disease (PD). Development of algorithms that can be easily implemented to detect saccades is required. This study aimed to develop an algorithm for the detection and measurement of saccades in EOG data during static (sitting) and dynamic (walking) tasks, in older adults and PD. Eye-tracking via mobile EOG and infra-red (IR) eye-tracker (with video) was performed with a group of older adults (n  =  10) and PD participants (n  =  10) (⩾50 years). Horizontal saccades made between targets set 5°, 10° and 15° apart were first measured while seated. Horizontal saccades were then measured while a participant walked and executed a 40° turn left and right. The EOG algorithm was evaluated by comparing the number of correct saccade detections and agreement (ICC 2,1 ) between output from visual inspection of eye-tracker videos and IR eye-tracker. The EOG algorithm detected 75-92% of saccades compared to video inspection and IR output during static testing, with fair to excellent agreement (ICC 2,1 0.49-0.93). However, during walking EOG saccade detection reduced to 42-88% compared to video inspection or IR output, with poor to excellent (ICC 2,1 0.13-0.88) agreement between methodologies. The algorithm was robust during seated testing but less so during walking, which was likely due to increased measurement and analysis error with a dynamic task. Future studies may consider a combination of EOG and IR for comprehensive measurement.

A factorial design to identify process parameters affecting whole mechanically disrupted rat pancreata in a perfusion bioreactor.

PubMed

Sharp, Jamie; Spitters, Tim Wgm; Vermette, Patrick

2018-03-01

Few studies report whole pancreatic tissue culture, as it is a difficult task using traditional culture methods. Here, a factorial design was used to investigate the singular and combinational effects of flow, dissolved oxygen concentration (D.O.) and pulsation on whole mechanically disrupted rat pancreata in a perfusion bioreactor. Whole rat pancreata were cultured for 72 h under defined bioreactor process conditions. Secreted insulin was measured and histological (haematoxylin and eosin (H&E)) as well as immunofluorescent insulin staining were performed and quantified. The combination of flow and D.O. had the most significant effect on secreted insulin at 5 h and 24 h. The D.O. had the biggest effect on tissue histological quality, and pulsation had the biggest effect on the number of insulin-positive structures. Based on the factorial design analysis, bioreactor conditions using high flow, low D.O., and pulsation were selected to further study glucose-stimulated insulin secretion. Here, mechanically disrupted rat pancreata were cultured for 24 h under these bioreactor conditions and were then challenged with high glucose concentration for 6 h and high glucose + IBMX (an insulin secretagogue) for a further 6 h. These cultures secreted insulin in response to high glucose concentration in the first 6 h, however stimulated-insulin secretion was markedly weaker in response to high glucose concentration + IBMX thereafter. After this bioreactor culture period, higher tissue metabolic activity was found compared to that of non-bioreacted static controls. More insulin- and glucagon-positive structures, and extensive intact endothelial structures were observed compared to non-bioreacted static cultures. H&E staining revealed more intact tissue compared to static cultures. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:432-444, 2018. © 2017 American Institute of Chemical Engineers.

Precise and Efficient Static Array Bound Checking for Large Embedded C Programs

NASA Technical Reports Server (NTRS)

Venet, Arnaud

2004-01-01

In this paper we describe the design and implementation of a static array-bound checker for a family of embedded programs: the flight control software of recent Mars missions. These codes are large (up to 250 KLOC), pointer intensive, heavily multithreaded and written in an object-oriented style, which makes their analysis very challenging. We designed a tool called C Global Surveyor (CGS) that can analyze the largest code in a couple of hours with a precision of 80%. The scalability and precision of the analyzer are achieved by using an incremental framework in which a pointer analysis and a numerical analysis of array indices mutually refine each other. CGS has been designed so that it can distribute the analysis over several processors in a cluster of machines. To the best of our knowledge this is the first distributed implementation of static analysis algorithms. Throughout the paper we will discuss the scalability setbacks that we encountered during the construction of the tool and their impact on the initial design decisions.

Reactivity of seismicity rate to static Coulomb stress changes of two consecutive large earthquakes in the central Philippines

NASA Astrophysics Data System (ADS)

Dianala, J. D. B.; Aurelio, M.; Rimando, J. M.; Taguibao, K.

2015-12-01

In a region with little understanding in terms of active faults and seismicity, two large-magnitude reverse-fault related earthquakes occurred within 100km of each other in separate islands of the Central Philippines—the Mw=6.7 February 2012 Negros earthquake and the Mw=7.2 October 2013 Bohol earthquake. Based on source faults that were defined using onshore, offshore seismic reflection, and seismicity data, stress transfer models for both earthquakes were calculated using the software Coulomb. Coulomb stress triggering between the two main shocks is unlikely as the stress change caused by Negros earthquake on the Bohol fault was -0.03 bars. Correlating the stress changes on optimally-oriented reverse faults with seismicity rate changes shows that areas that decreased both in static stress and seismicity rate after the first earthquake were then areas with increased static stress and increased seismicity rate caused by the second earthquake. These areas with now increased stress, especially those with seismicity showing reactivity to static stress changes caused by the two earthquakes, indicate the presence of active structures in the island of Cebu. Comparing the history of instrumentally recorded seismicity and the recent large earthquakes of Negros and Bohol, these structures in Cebu have the potential to generate large earthquakes. Given that the Philippines' second largest metropolitan area (Metro Cebu) is in close proximity, detailed analysis of the earthquake potential and seismic hazards in these areas should be undertaken.

Genotoxic Effects of Superconducting Static Magnetic Fields (SMFs) on Wheat (Triticum aestivum) Pollen Mother Cells (PMCs)

NASA Astrophysics Data System (ADS)

Zhang, Pingping; Yin, Ruochun; Chen, Zhiyou; Wu, Lifang; Yu, Zengliang

2007-04-01

The effects of superconducting static magnetic fields (SMFs) on the pollen mother cells (PMCs) of wheat were investigated in order to evaluate the possible genotoxic effect of such non-ionizing radiation. The seeds of wheat were exposed to static magnetic fields with either different magnetic flux densities (0, 1, 3, 5 and 7 Tesla) for 5 h or different durations (1, 3 and 5 h) at a magnetic flux density of 7 Tesla. The seeds were germinated at 23oC after exposure and the seedlings were transplanted into the field. The PMCs from young wheat ears were taken and slides were made following the conventional method. The genotoxic effect was evaluated in terms of micronucleus (MN), chromosomal bridge, lagging chromosome and fragments in PMCs. Although the exposed groups of a low field intensity (below 5 Tesla) showed no statistically significant difference in the aberration frequency compared with the unexposed control groups and sham exposed groups, a significant increase in the chromosomal bridge, lagging chromosome, triple-polar segregation or micronucleus was observed at a field strength of 5 Tesla or 7 Tesla, respectively. The analysis of dose-effect relationships indicated that the increased frequency of meiotic abnormal cells correlated with the flux density of the magnetic field and duration, but no linear relationship was observed. Such statistically significant differences indicated a potential genotoxic effect of high static magnetic fields above 5 T.

Plantar-flexor Static Stretch Training Effect on Eccentric and Concentric Peak Torque – A comparative Study of Trained versus Untrained Subjects

PubMed Central

Abdel-aziem, Amr Almaz; Mohammad, Walaa Sayed

2012-01-01

The aim of this study was to examine the long-term effects of static stretching of the plantar-flexor muscles on eccentric and concentric torque and ankle dorsiflexion range of motion in healthy subjects. Seventy five healthy male volunteers, with no previous history of trauma to the calf that required surgery, absence of knee flexion contracture and no history of neurologic dysfunction or disease, systemic disease affecting the lower extremities were selected for this study. The participants were divided into three equal groups. The control group did not stretch the plantar-flexor muscles. Two Experimental groups (trained and untrained) were instructed to perform static stretching exercise of 30 second duration and 5 repetitions twice daily. The stretching sessions were carried out 5 days a week for 6 weeks. The dorsiflexion range of motion was measured in all subjects. Also measured was the eccentric and concentric torque of plantar-flexors at angular velocities of 30 and 120°/s pre and post stretching. Analysis of variance showed a significant increase in plantar-flexor eccentric and concentric torque (p < 0.05) of trained and untrained groups, and an increase in dorsiflexion range of motion (p < 0.05) at both angular velocities for the untrained group only. The static stretching program of plantar-flexors was effective in increasing the concentric and eccentric plantarflexion torque at angular velocities of 30 and 120°/s. Increases in plantar-flexors flexibility were observed in untrained subjects. PMID:23486840

Acoustic Reflexes in Normal-Hearing Adults, Typically Developing Children, and Children with Suspected Auditory Processing Disorder: Thresholds, Real-Ear Corrections, and the Role of Static Compliance on Estimates.

PubMed

Saxena, Udit; Allan, Chris; Allen, Prudence

2017-06-01

Previous studies have suggested elevated reflex thresholds in children with auditory processing disorders (APDs). However, some aspects of the child's ear such as ear canal volume and static compliance of the middle ear could possibly affect the measurements of reflex thresholds and thus impact its interpretation. Sound levels used to elicit reflexes in a child's ear may be higher than predicted by calibration in a standard 2-cc coupler, and lower static compliance could make visualization of very small changes in impedance at threshold difficult. For this purpose, it is important to evaluate threshold data with consideration of differences between children and adults. A set of studies were conducted. The first compared reflex thresholds obtained using standard clinical procedures in children with suspected APD to that of typically developing children and adults to test the replicability of previous studies. The second study examined the impact of ear canal volume on estimates of reflex thresholds by applying real-ear corrections. Lastly, the relationship between static compliance and reflex threshold estimates was explored. The research is a set of case-control studies with a repeated measures design. The first study included data from 20 normal-hearing adults, 28 typically developing children, and 66 children suspected of having an APD. The second study included 28 normal-hearing adults and 30 typically developing children. In the first study, crossed and uncrossed reflex thresholds were measured in 5-dB step size. Reflex thresholds were analyzed using repeated measures analysis of variance (RM-ANOVA). In the second study, uncrossed reflex thresholds, real-ear correction, ear canal volume, and static compliance were measured. Reflex thresholds were measured using a 1-dB step size. The effect of real-ear correction and static compliance on reflex threshold was examined using RM-ANOVA and Pearson correlation coefficient, respectively. Study 1 replicated previous studies showing elevated reflex thresholds in many children with suspected APD when compared to data from adults using standard clinical procedures, especially in the crossed condition. The thresholds measured in children with suspected APD tended to be higher than those measured in the typically developing children. There were no significant differences between the typically developing children and adults. However, when real-ear calibrated stimulus levels were used, it was found that children's thresholds were elicited at higher levels than in the adults. A significant relationship between reflex thresholds and static compliance was found in the adult data, showing a trend for higher thresholds in ears with lower static compliance, but no such relationship was found in the data from the children. This study suggests that reflex measures in children should be adjusted for real-ear-to-coupler differences before interpretation. The data in children with suspected APD support previous studies suggesting abnormalities in reflex thresholds. The lack of correlation between threshold and static compliance estimates in children as was observed in the adults may suggest a nonmechanical explanation for age and clinically related effects. American Academy of Audiology

Some studies on the use of NASTRAN for nuclear power plant structural analysis and design

NASA Technical Reports Server (NTRS)

Setlur, A. V.; Valathur, M.

1973-01-01

Studies made on the use of NASTRAN for nuclear power plant analysis and design are presented. These studies indicate that NASTRAN could be effectively used for static, dynamic and special purpose problems encountered in the design of such plants. Normal mode capability of NASTRAN is extended through a post-processor program to handle seismic analysis. Static and dynamic substructuring is discussed. Extension of NASTRAN to include the needs in the civil engineering industry is discussed.

The Effect of Basis Selection on Static and Random Acoustic Response Prediction Using a Nonlinear Modal Simulation

NASA Technical Reports Server (NTRS)

Rizzi, Stephen A.; Przekop, Adam

2005-01-01

An investigation of the effect of basis selection on geometric nonlinear response prediction using a reduced-order nonlinear modal simulation is presented. The accuracy is dictated by the selection of the basis used to determine the nonlinear modal stiffness. This study considers a suite of available bases including bending modes only, bending and membrane modes, coupled bending and companion modes, and uncoupled bending and companion modes. The nonlinear modal simulation presented is broadly applicable and is demonstrated for nonlinear quasi-static and random acoustic response of flat beam and plate structures with isotropic material properties. Reduced-order analysis predictions are compared with those made using a numerical simulation in physical degrees-of-freedom to quantify the error associated with the selected modal bases. Bending and membrane responses are separately presented to help differentiate the bases.

ZrCuAl Bulk Metallic Glass spall induced by laser shock

NASA Astrophysics Data System (ADS)

Jodar, Benjamin; Loison, Didier; Yokoyama, Yoshihiko; Lescoute, Emilien; Berthe, Laurent; Sangleboeuf, Jean-Christophe

2017-06-01

To face High Velocity Impacts, the aerospace industry is always seeking for innovative materials usable as debris shielding components. Bulk Metallic Glasses (BMG) revealed interesting mechanical properties in case of static and quasi-static loading conditions: high elasticity, high tenacity, low density and high fracture threshold... The department of Mechanics and Glass of the Institut of Physics Rennes conducted on the ELFIE facility, laser shock experiments to study the behavior of a ternary ZrCuAl BMG under high strain rate, up-to fragmentation process. On the one hand, in-situ diagnostics were used to measure ejection velocities with PDV and debris morphologies were observed by Shadowgraphy. On the other hand, spalled areas (dimensions and features) were characterized through post-mortem analysis (optical observations, profilometry and SEM). These results are compared to experimental and numerical data on the crystalline forms of the ZrCuAl basic compounds.

An approximate theoretical method for modeling the static thrust performance of non-axisymmetric two-dimensional convergent-divergent nozzles. M.S. Thesis - George Washington Univ.

NASA Technical Reports Server (NTRS)

Hunter, Craig A.

1995-01-01

An analytical/numerical method has been developed to predict the static thrust performance of non-axisymmetric, two-dimensional convergent-divergent exhaust nozzles. Thermodynamic nozzle performance effects due to over- and underexpansion are modeled using one-dimensional compressible flow theory. Boundary layer development and skin friction losses are calculated using an approximate integral momentum method based on the classic karman-Polhausen solution. Angularity effects are included with these two models in a computational Nozzle Performance Analysis Code, NPAC. In four different case studies, results from NPAC are compared to experimental data obtained from subscale nozzle testing to demonstrate the capabilities and limitations of the NPAC method. In several cases, the NPAC prediction matched experimental gross thrust efficiency data to within 0.1 percent at a design NPR, and to within 0.5 percent at off-design conditions.

Resolution of structural heterogeneity in dynamic crystallography

PubMed Central

Ren, Zhong; Chan, Peter W. Y.; Moffat, Keith; Pai, Emil F.; Royer, William E.; Šrajer, Vukica; Yang, Xiaojing

2013-01-01

Dynamic behavior of proteins is critical to their function. X-­ray crystallography, a powerful yet mostly static technique, faces inherent challenges in acquiring dynamic information despite decades of effort. Dynamic ‘structural changes’ are often indirectly inferred from ‘structural differences’ by comparing related static structures. In contrast, the direct observation of dynamic structural changes requires the initiation of a biochemical reaction or process in a crystal. Both the direct and the indirect approaches share a common challenge in analysis: how to interpret the structural heterogeneity intrinsic to all dynamic processes. This paper presents a real-space approach to this challenge, in which a suite of analytical methods and tools to identify and refine the mixed structural species present in multiple crystallographic data sets have been developed. These methods have been applied to representative scenarios in dynamic crystallography, and reveal structural information that is otherwise difficult to interpret or inaccessible using conventional methods. PMID:23695239

Estimation of Rotary Stability Derivatives at Subsonic and Transonic Speeds

NASA Technical Reports Server (NTRS)

Tobak, Murray; Lessing, Henry C.

1961-01-01

The first part of this paper pertains to the estimation of subsonic rotary stability derivatives of wings. The unsteady potential flow problem is solved by a superposition of steady flow solutions. Numerical results for the damping coefficients of triangular wings are presented as functions of aspect ratio and Mach number, and are compared with experimental results over the Mach number range 0 to 1. In the second part, experimental results are used. to point out a close correlation between the nonlinear variations with angle of attack of the static pitching-moment curve slope and the damping-in-pitch coefficient. The underlying basis for the correlation is found as a result of an analysis in which the indicial function concept and. the principle of super-position are adapted to apply to the nonlinear problem. The form of the result suggests a method of estimating nonlinear damping coefficients from results of static wind-tunnel measurements.

Implementation of the block-Krylov boundary flexibility method of component synthesis

NASA Technical Reports Server (NTRS)

Carney, Kelly S.; Abdallah, Ayman A.; Hucklebridge, Arthur A.

1993-01-01

A method of dynamic substructuring is presented which utilizes a set of static Ritz vectors as a replacement for normal eigenvectors in component mode synthesis. This set of Ritz vectors is generated in a recurrence relationship, which has the form of a block-Krylov subspace. The initial seed to the recurrence algorithm is based on the boundary flexibility vectors of the component. This algorithm is not load-dependent, is applicable to both fixed and free-interface boundary components, and results in a general component model appropriate for any type of dynamic analysis. This methodology was implemented in the MSC/NASTRAN normal modes solution sequence using DMAP. The accuracy is found to be comparable to that of component synthesis based upon normal modes. The block-Krylov recurrence algorithm is a series of static solutions and so requires significantly less computation than solving the normal eigenspace problem.

Comparison of results of experimental research with numerical calculations of a model one-sided seal

NASA Astrophysics Data System (ADS)

Joachimiak, Damian; Krzyślak, Piotr

2015-06-01

Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.

Resolution of structural heterogeneity in dynamic crystallography.

PubMed

Ren, Zhong; Chan, Peter W Y; Moffat, Keith; Pai, Emil F; Royer, William E; Šrajer, Vukica; Yang, Xiaojing

2013-06-01

Dynamic behavior of proteins is critical to their function. X-ray crystallography, a powerful yet mostly static technique, faces inherent challenges in acquiring dynamic information despite decades of effort. Dynamic `structural changes' are often indirectly inferred from `structural differences' by comparing related static structures. In contrast, the direct observation of dynamic structural changes requires the initiation of a biochemical reaction or process in a crystal. Both the direct and the indirect approaches share a common challenge in analysis: how to interpret the structural heterogeneity intrinsic to all dynamic processes. This paper presents a real-space approach to this challenge, in which a suite of analytical methods and tools to identify and refine the mixed structural species present in multiple crystallographic data sets have been developed. These methods have been applied to representative scenarios in dynamic crystallography, and reveal structural information that is otherwise difficult to interpret or inaccessible using conventional methods.

Results of PBX 9501 and PBX 9502 Round-Robin Quasi-Static Tension Tests from JOWOG-9/39 Focused Exchange.

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

Thompson, D. G.

2002-01-01

A round-robin study was conducted with the participation of three laboratory facilities: Los Alamos National Laboratory (LANL), BWXT Pantex Plant (PX), and Lawrence Livermore National Laboratory (LLNL). The study involved the machining and quasi-static tension testing of two plastic-bonded high explosive (PBX) composites, PBX 9501 and PBX 9502. Nine tensile specimens for each type of PBX were to be machined at each of the three facilities; 3 of these specimens were to be sent to each of the participating materials testing facilities for tensile testing. The resultant data was analyzed to look for trends associated with specimen machining location and/ormore » trends associated with materials testing location. The analysis provides interesting insights into the variability and statistical nature of mechanical properties testing on PBX composites. Caution is warranted when results are compared/exchanged between testing facilities.« less

Recent advances in the modelling of crack growth under fatigue loading conditions

NASA Technical Reports Server (NTRS)

Dekoning, A. U.; Tenhoeve, H. J.; Henriksen, T. K.

1994-01-01

Fatigue crack growth associated with cyclic (secondary) plastic flow near a crack front is modelled using an incremental formulation. A new description of threshold behaviour under small load cycles is included. Quasi-static crack extension under high load excursions is described using an incremental formulation of the R-(crack growth resistance)- curve concept. The integration of the equations is discussed. For constant amplitude load cycles the results will be compared with existing crack growth laws. It will be shown that the model also properly describes interaction effects of fatigue crack growth and quasi-static crack extension. To evaluate the more general applicability the model is included in the NASGRO computer code for damage tolerance analysis. For this purpose the NASGRO program was provided with the CORPUS and the STRIP-YIELD models for computation of the crack opening load levels. The implementation is discussed and recent results of the verification are presented.

Deformation behavior of welded steel sandwich panels under quasi-static loading

DOT National Transportation Integrated Search

2011-03-16

This paper summarizes basic research (i.e., testing and analysis) : conducted to examine the deformation behavior of flat-welded : steel sandwich panels under two types of quasi-static loading: : (1) uniaxial compression; and (2) bending through an i...

Commuter rail seat testing and analysis of facing seats

DOT National Transportation Integrated Search

2003-12-01

Tests have been conducted on the Bombardier back-to-back commuter rail car seat in a facing-seat configuration to evaluate its performance under static and dynamic loading conditions. Quasi-static tests have been conducted to establish the load defle...

The Comparison Of In-Flight Pitot Static Calibration Method By Using Radio Altimeter As Reference with GPS and Tower Fly By Methods On CN235-100 MPA

NASA Astrophysics Data System (ADS)

Derajat; Hariowibowo, Hindawan

2018-04-01

The new proposed In-Flight Pitot Static Calibration Method has been carried out during Development and Qualification of CN235-100 MPA (Military Patrol Aircraft). This method is expected to reduce flight hours, less human resources required, no additional special equipment, simple analysis calculation and finally by using this method it is expected to automatically minimized operational cost. At The Indonesian Aerospace (IAe) Flight Test Center Division, the development and updating of new flight test technique and data analysis method as specially for flight physics test subject are still continued to be developed as long as it safety for flight and give additional value for the industrial side. More than 30 years, Flight Test Data Engineers at The Flight Test center Division work together with the Air Crew (Test Pilots, Co-Pilots, and Flight Test Engineers) to execute the flight test activity with standard procedure for both the existance or development test techniques and test data analysis. In this paper the approximation of mathematical model, data reduction and flight test technique of The In-Flight Pitot Static Calibration by using Radio Altimeter as reference will be described and the test results had been compared with another methods ie. By using Global Position System (GPS) and the traditional method (Tower Fly By Method) which were used previously during this Flight Test Program (Ref. [10]). The flight test data case are using CN235-100 MPA flight test data during development and Qualification Flight Test Program at Cazaux Airport, France, in June-November 2009 (Ref. [2]).

A structural and theoretical study of the alkylammonium nitrates forefather: Liquid methylammonium nitrate

NASA Astrophysics Data System (ADS)

Gontrani, Lorenzo; Caminiti, Ruggero; Salma, Umme; Campetella, Marco

2017-09-01

We present here a structural and vibrational analysis of melted methylammonium nitrate, the simplest compound of the family of alkylammonium nitrates. The static and dynamical features calculated were endorsed by comparing the experimental X-ray data with the theoretical ones. A reliable description cannot be obtained with classical molecular dynamics owing to polarization effects. Contrariwise, the structure factor and the vibrational frequencies obtained from ab initio molecular dynamics trajectories are in very good agreement with the experiment. A careful analysis has provided additional information on the complex hydrogen bonding network that exists in this liquid.

Thermoviscoplastic response of thin plates subjected to intense local heating

NASA Technical Reports Server (NTRS)

Byrom, Ted G.; Allen, David H.; Thornton, Earl A.

1992-01-01

A finite element method is employed to investigate the thermoviscoplastic response of a half-cylinder to intense localized transient heating. Thermoviscoplastic material behavior is characterized by the Bodner-Partom constitutive model. Structure geometry is modeled with a three-dimensional assembly of CST-DKT plate elements incorporating the large deflection von Karman assumptions. The paper compares the results of a dynamic analysis with a quasi-static analysis for the half-cylinder structure with a step-function transient temperature loading similar to that which may be encountered with shock wave interference on a hypersonic leading edge.

Entrance and exit region friction factor models for annular seal analysis. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Elrod, David Alan

1988-01-01

The Mach number definition and boundary conditions in Nelson's nominally-centered, annular gas seal analysis are revised. A method is described for determining the wall shear stress characteristics of an annular gas seal experimentally. Two friction factor models are developed for annular seal analysis; one model is based on flat-plate flow theory; the other uses empirical entrance and exit region friction factors. The friction factor predictions of the models are compared to experimental results. Each friction model is used in an annular gas seal analysis. The seal characteristics predicted by the two seal analyses are compared to experimental results and to the predictions of Nelson's analysis. The comparisons are for smooth-rotor seals with smooth and honeycomb stators. The comparisons show that the analysis which uses empirical entrance and exit region shear stress models predicts the static and stability characteristics of annular gas seals better than the other analyses. The analyses predict direct stiffness poorly.

Effect of cyclic and static tensile loading on water content and solute diffusion in canine flexor tendons: an in vitro study.

PubMed

Hannafin, J A; Arnoczky, S P

1994-05-01

This study was designed to determine the effects of various loading conditions (no load and static and cyclic tensile load) on the water content and pattern of nutrient diffusion of canine flexor tendons in vitro. Region D (designated by Okuda et al.) of the flexor digitorum profundus was subjected to a cyclic or static tensile load of 100 g for times ranging from 5 minutes to 24 hours. The results demonstrated a statistically significant loss of water in tendons subjected to both types of load as compared with the controls (no load). This loss appeared to progress with time. However, neither static nor cyclic loading appeared to alter the diffusion of 3H-glucose into the tendon over a 24-hour period compared with the controls. These results suggest that any benefit in tendon repair derived from intermittent passive motion is probably not a result of an increase in the diffusion of small nutrients in response to intermittent tensile load.

Human thermal responses during leg-only exercise in cold water.

PubMed

Golden, F S; Tipton, M J

1987-10-01

1. Exercise during immersion in cold water has been reported by several authors to accelerate the rate of fall of core temperature when compared with rates seen during static immersion. The nature of the exercise performed, however, has always been whole-body in nature. 2. In the present investigation fifteen subjects performed leg exercise throughout a 40 min head-out immersion in water at 15 degrees C. The responses obtained were compared with those seen when the subjects performed an identical static immersion. 3. Aural and rectal temperatures were found to fall by greater amounts during static immersion. 4. It is concluded that 'the type of exercise performed' should be included in the list of factors which affect core temperature during cold water immersion.

Comparative evaluation of woven graphite-epoxy composites

NASA Technical Reports Server (NTRS)

Hanagud, S.; Tayebi, A.; Clinton, R. G., Jr.; Nayak, B. M.

1979-01-01

A comparative evaluation of some of the mechanical properties of woven graphite-epoxy composites are discussed. In particular, the types of weaves and the resin contents were chosen for comparison. The types of weaves selected are plain weave, satin weave, and tridirectional weave. The composites made of the fabrics are compared to composites made from unidirectional tapes under static and fatigue loading. During static loading, acoustic emission events were monitored. Also, examinations of fracture surfaces and polished sections both away from the fracture surface, and of virgin specimens under an electron microscope are discussed.

Flow cytometric cell cycle analysis of muscle precursor cells cultured within 3D scaffolds in a perfusion bioreactor.

PubMed

Flaibani, Marina; Luni, Camilla; Sbalchiero, Elisa; Elvassore, Nicola

2009-01-01

It has been widely demonstrated that perfusion bioreactors improve in vitro three-dimensional (3D) cultures in terms of high cell density and uniformity of cell distribution; however, the studies reported in literature were primarily based on qualitative analysis (histology, immunofluorescent staining) or on quantitative data averaged on the whole population (DNA assay, PCR). Studies on the behavior, in terms of cell cycle, of a cell population growing in 3D scaffolds in static or dynamic conditions are still absent. In this work, a perfusion bioreactor suitable to culture C(2)C(12) muscle precursor cells within 3D porous collagen scaffolds was designed and developed and a method based on flowcytometric analyses for analyzing the cell cycle in the cell population was established. Cells were extracted by enzymatic digestion of the collagen scaffolds after 4, 7, and 10 days of culture, and flow cytometric live/dead and cell cycle analyses were performed with Propidium Iodide. A live/dead assay was used for validating the method for cell extraction and staining. Moreover, to investigate spatial heterogeneity of the cell population under perfusion conditions, two stacked scaffolds in the 3D domain, of which only the upstream layer was seeded, were analyzed separately. All results were compared with those obtained from static 3D cultures. The live/dead assay revealed the presence of less than 20% of dead cells, which did not affect the cell cycle analysis. Cell cycle analyses highlighted the increment of cell fractions in proliferating phases (S/G(2)/M) owing to medium perfusion in long-term cultures. After 7-10 days, the percentage of proliferating cells was 8-12% for dynamic cultures and 3-5% for the static controls. A higher fraction of proliferating cells was detected in the downstream scaffold. From a general perspective, this method provided data with a small standard deviation and detected the differences between static and dynamic cultures and between upper and lower scaffolds. Our methodology can be extended to other cell types to investigate the influence of 3D culture conditions on the expression of other relevant cell markers.

An Analysis of the Effects of Wing Aspect Ratio and Tail Location on Static Longitudinal Stability Below the Mach Number of Lift Divergence

NASA Technical Reports Server (NTRS)

Axelson, John A.; Crown, J. Conrad

1948-01-01

An analysis is presented of the influence of wing aspect ratio and tail location on the effects of compressibility upon static longitudinal stability. The investigation showed that the use of reduced wing aspect ratios or short tail lengths leads to serious reductions in high-speed stability and the possibility of high-speed instability.

Static Analysis Alert Audits: Lexicon and Rules

DTIC Science & Technology

2016-11-04

collaborators • Includes a standard set of well-defined determinations for static analysis alerts • Includes a set of auditing rules to help auditors make...consistent decisions in commonly-encountered situations Different auditors should make the same determination for a given alert! Improve the quality and...scenarios • Establish assumptions auditors can make • Overall: help make audit determinations more consistent We developed 12 rules • Drew on our own

Performance characteristics of axisymmetric convergent-divergent exhaust nozzles with longitudinal slots in the divergent

NASA Technical Reports Server (NTRS)

Leavitt, L. D.; Bangert, L. S.

1982-01-01

An investigation was conducted in the Langley 16 foot Transonic Tunnel and in the static test facility of that tunnel to determine the effects of divergent flap ventilation of an axisymmetric nozzle on nozzle internal (static) and wind on performance. Tests were conducted at 0 deg angle of attack at static conditions and at Mach numbers from 0.6 to 1.2. Ratios of jet total pressure to free stream static pressure were varied from 1.0 (jet off) to approximately 14.0 depending on Mach number. The results of this study indicate that divergent flap ventilation generally provided large performance benefits at overexpanded nozzle conditions and performance reductions at underexpanded nozzle conditions when compared to the baseline (unventilated) nozzles. Ventilation also reduced the peak static and wind on performance levels.

Hyperfine interactions in titanates: Study of orbital ordering and local magnetic properties

NASA Astrophysics Data System (ADS)

Agzamova, P. A.; Leskova, Yu. V.; Nikiforov, A. E.

2013-05-01

Hyperfine magnetic fields induced on the nuclei of nonmagnetic ions 139La and 89Y in LaTiO3 and YTiO3, respectively, have been microscopically calculated. The dependence of the hyperfine fields on the orbital and magnetic structures of the compounds under study has been analyzed. The comparative analysis of the calculated and known experimental data confirms the existence of the static orbital structure in lanthanum and yttrium titanates.

Analytical Method Used to Calculate Pile Foundations with the Widening Up on a Horizontal Static Impact

NASA Astrophysics Data System (ADS)

Kupchikova, N. V.; Kurbatskiy, E. N.

2017-11-01

This paper presents a methodology for the analytical research solutions for the work pile foundations with surface broadening and inclined side faces in the ground array, based on the properties of Fourier transform of finite functions. The comparative analysis of the calculation results using the suggested method for prismatic piles, piles with surface broadening prismatic with precast piles and end walls with precast wedges on the surface is described.

Comparison of Space Shuttle Hot Gas Manifold analysis to air flow data

NASA Technical Reports Server (NTRS)

Mcconnaughey, P. K.

1988-01-01

This paper summarizes several recent analyses of the Space Shuttle Main Engine Hot Gas Manifold and compares predicted flow environments to air flow data. Codes used in these analyses include INS3D, PAGE, PHOENICS, and VAST. Both laminar (Re = 250, M = 0.30) and turbulent (Re = 1.9 million, M = 0.30) results are discussed, with the latter being compared to data for system losses, outer wall static pressures, and manifold exit Mach number profiles. Comparison of predicted results for the turbulent case to air flow data shows that the analysis using INS3D predicted system losses within 1 percent error, while the PHOENICS, PAGE, and VAST codes erred by 31, 35, and 47 percent, respectively. The INS3D, PHOENICS, and PAGE codes did a reasonable job of predicting outer wall static pressure, while the PHOENICS code predicted exit Mach number profiles with acceptable accuracy. INS3D was approximately an order of magnitude more efficient than the other codes in terms of code speed and memory requirements. In general, it is seen that complex internal flows in manifold-like geometries can be predicted with a limited degree of confidence, and further development is necessary to improve both efficiency and accuracy of codes if they are to be used as design tools for complex three-dimensional geometries.

Comparison of the performance of the activPAL Professional physical activity logger to a discrete accelerometer-based activity monitor.

PubMed

Godfrey, A; Culhane, K M; Lyons, G M

2007-10-01

The aim of this study was to assess the accuracy of the 'activPAL Professional' physical activity logger by comparing its output to that of a proven discrete accelerometer-based activity monitor during extended measurements on healthy subjects while performing activities of daily living (ADL). Ten healthy adults, with unrestricted mobility, wore both the activPAL and the discrete dual accelerometer (Analog Devices ADXL202)-based activity monitor that recorded in synchronization with each other. The accelerometer derived data were then compared to that generated by the activPAL and a complete statistical and error analysis was performed using a Matlab program. This program determined trunk and thigh inclination angles to distinguish between sitting/lying, standing and stepping for the discrete accelerometer device and amount of time spent on each activity. Analysis was performed on a second-by-second basis and then categorized at 15s intervals in direct comparison with the activPAL generated data. Of the total time monitored (approximately 60 h) the detection accuracies for static and dynamic activities were approximately 98%. In a population of healthy adults, the data obtained from the activPAL Professional physical activity logger for both static and dynamic activities showed a close match to a proven discrete accelerometer data with an offset of approximately 2% between the two systems.

Cyclic Fatigue Resistance of Novel Rotary Files Manufactured from Different Thermal Treated Nickel-Titanium Wires in Artificial Canals.

PubMed

Karataşlıoglu, E; Aydın, U; Yıldırım, C

2018-02-01

The aim of this in vitro study was to compare the static cyclic fatigue resistance of thermal treated rotary files with a conventional nickel-titanium (NiTi) rotary file. Four groups of 60 rotary files with similar file dimensions, geometries, and motion were selected. Groups were set as HyFlex Group [controlled memory wire (CM-Wire)], ProfileVortex Group (M-Wire), Twisted File Group (R-Phase Wire), and OneShape Group (conventional NiTi wire)] and tested using a custom-made static cyclic fatigue testing apparatus. The fracture time and fragment length of the each file was also recorded. Statistical analysis was performed using one-way analysis of variance and Tukey's test at the 95% confidence level (P = 0.05). The HyFlex group had a significantly higher mean cyclic fatigue resistance than the other three groups (P < 0.001). The OneShape groups had the least fatigue resistance. CM-Wire alloy represented the best performance in cyclic fatigue resistance, and NiTi alloy in R-Phase had the second highest fatigue resistance. CM and R-Phase manufacturing technology processed to the conventional NiTi alloy enhance the cyclic fatigue resistance of files that have similar design and size. M-wire alloy did not show any superiority in cyclic fatigue resistance when compared with conventional NiTi wire.

Analysis for lateral deflection of railroad track under quasi-static loading

DOT National Transportation Integrated Search

2013-10-15

This paper describes analyses to examine the lateral : deflection of railroad track subjected to quasi-static loading. : Rails are assumed to behave as beams in bending. Movement : of the track in the lateral plane is constrained by idealized : resis...

Static Analysis of Large-Scale Multibody System Using Joint Coordinates and Spatial Algebra Operator

PubMed Central

Omar, Mohamed A.

2014-01-01

Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations. PMID:25045732

Static analysis of large-scale multibody system using joint coordinates and spatial algebra operator.

PubMed

Omar, Mohamed A

2014-01-01

Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations.

Investigation of Gearbox Vibration Transmission Paths on Gear Condition Indicator Performance

NASA Technical Reports Server (NTRS)

Dempsey, Paula J.; Islam, AKM Anwarul; Feldman, Jason; Larsen, Chris

2013-01-01

Helicopter health monitoring systems use vibration signatures generated from damaged components to identify transmission faults. For damaged gears, these signatures relate to changes in dynamics due to the meshing of the damaged tooth. These signatures, referred to as condition indicators (CI), can perform differently when measured on different systems, such as a component test rig, or a full-scale transmission test stand, or an aircraft. These differences can result from dissimilarities in systems design and environment under dynamic operating conditions. The static structure can also filter the response between the vibration source and the accelerometer, when the accelerometer is installed on the housing. To assess the utility of static vibration transfer paths for predicting gear CI performance, measurements were taken on the NASA Glenn Spiral Bevel Gear Fatigue Test Rig. The vibration measurements were taken to determine the effect of torque, accelerometer location and gearbox design on accelerometer response. Measurements were taken at the housing and compared while impacting the gear set near mesh. These impacts were made at gear mesh to simulate gear meshing dynamics. Data measured on a helicopter gearbox installed in a static fixture were also compared to the test rig. The behavior of the structure under static conditions was also compared to CI values calculated under dynamic conditions. Results indicate that static vibration transfer path measurements can provide some insight into spiral bevel gear CI performance by identifying structural characteristics unique to each system that can affect specific CI response.

Improving agreement between static method and dynamic formula for driven cast-in-place piles.

DOT National Transportation Integrated Search

2013-06-01

This study focuses on comparing the capacities and lengths of piling necessary as determined with a static method and with a dynamic formula. Pile capacities and their required lengths are determined two ways: 1) using a design and computed method, s...

Comparative evaluation of fracture resistance under static and fatigue loading of endodontically treated teeth restored with carbon fiber posts, glass fiber posts, and an experimental dentin post system: an in vitro study.

PubMed

Ambica, Khetarpal; Mahendran, Kavitha; Talwar, Sangeeta; Verma, Mahesh; Padmini, Govindaswamy; Periasamy, Ravishankar

2013-01-01

This investigation sought to compare the fracture resistance under static and fatigue loading of endodontically treated teeth restored with fiber-reinforced composite posts and experimental dentin posts milled from human root dentin by using computer-aided design/computer-aided manufacturing. Seventy maxillary central incisors were obturated and divided into 4 groups: control group without any post (n = 10), carbon fiber post group (n = 20), glass fiber post group (n = 20), and dentin post group (n = 20). Control group teeth were prepared to a height of 5 mm. In all other teeth, post space was prepared; a post was cemented, and a core build-up was provided. Half the samples from each group were statistically loaded until failure, and the remaining half were subjected to cyclic loading, followed by monostatic load until fracture. One-way analysis of variance and Bonferroni multiple comparisons revealed a significant difference among test groups. The control group demonstrated highest fracture resistance (935.03 ± 33.53 N), followed by the dentin post group (793.12 ± 33.69 N), glass fiber post group (603.44 ± 46.67 N), and carbon fiber post group (497.19 ± 19.27 N) under static loading. These values reduced to 786.69 ± 29.64 N, 646.34 ± 26.56 N, 470 ± 36.34 N, and 379.71 ± 13.95 N, respectively, after cyclic loading. Results suggest that human dentin can serve as post material under static and fatigue loading. Although at an early stage in research, the use of dentin posts in root-filled teeth looks promising. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Pelvic Static Magnetic Stimulation to Control Urinary Incontinence in Older Women: A Randomized Controlled Trial

PubMed Central

Wallis, Marianne C.; Davies, Elizabeth A.; Thalib, Lukman; Griffiths, Susan

2012-01-01

Objectives To determine the efficacy of non-invasive static magnetic stimulation (SMS) of the pelvic floor compared to placebo in the treatment of women aged 60 years and over with urinary incontinence for 6 months or more. Subjects and Methods A single-blinded randomized, placebo-controlled, parallel-group trial. Subjects were excluded if they had an implanted electronic device, had experienced a symptomatic urinary tract infection, or had commenced pharmacotherapy for the same in the previous 4 weeks, or if they were booked for pelvic floor or gynecological surgery within the next 3 months. Once written consent was obtained, subjects were randomly assigned to the active SMS group (n=50) or the placebo group (n=51). Treatment was an undergarment incorporating 15 static magnets of 800–1200 Gauss anterior, posterior, and inferior to the pelvis for at least 12 hours a day for 3 months. Placebo was the same protocol with inert metal disks replacing the magnets. Primary outcome measure was cessation of incontinence as measured by a 24-hour pad test. Secondary outcomes were frequency and severity of symptoms as measured by the Bristol Female Lower Urinary Tract Symptoms questionnaire (BFLUTS-SF), the Incontinence Severity Index, a Bothersomeness Visual Analog scale, and a 24-hour bladder diary. Data were collected at baseline and 12 weeks later. Results There were no statistically significant differences between groups in any of the outcome measures from baseline to 12 weeks. Initial evidence of subjective improvement in the treatment group compared to the placebo group was not sustained with sensitivity analysis. Conclusion This study found no evidence that static magnets cure or decrease the symptoms of urinary incontinence. Additional work into the basic physics of the product and garment design is recommended prior to further clinical trials research. PMID:21817123

A mechanism to explain the variations of tropopause and tropopause inversion layer in the Arctic region during a sudden stratospheric warming in 2009

NASA Astrophysics Data System (ADS)

Wang, Rui; Tomikawa, Yoshihiro; Nakamura, Takuji; Huang, Kaiming; Zhang, Shaodong; Zhang, Yehui; Yang, Huigen; Hu, Hongqiao

2016-10-01

The mechanism to explain the variations of tropopause and tropopause inversion layer (TIL) in the Arctic region during a sudden stratospheric warming (SSW) in 2009 was studied with the Modern-Era Retrospective analysis for Research and Applications reanalysis data and GPS/Constellation Observing system for Meteorology, Ionosphere, and Climate (COSMIC) temperature data. During the prominent SSW in 2009, the cyclonic system changed to the anticyclonic system due to the planetary wave with wave number 2 (wave2). The GPS/COSMIC temperature data showed that during the SSW in 2009, the tropopause height in the Arctic decreased accompanied with the tropopause temperature increase and the TIL enhancement. The variations of the tropopause and TIL were larger in higher latitudes. A static stability analysis showed that the variations of the tropopause and TIL were associated with the variations of the residual circulation and the static stability due to the SSW. Larger static stability appeared in the upper stratosphere and moved downward to the narrow region just above the tropopause. The descent of strong downward flow was faster in higher latitudes. The static stability tendency analysis showed that the strong downward residual flow induced the static stability change in the stratosphere and around the tropopause. The strong downwelling in the stratosphere was mainly induced by wave2, which led to the tropopause height and temperature changes due to the adiabatic heating. Around the tropopause, a pair of downwelling above the tropopause and upwelling below the tropopause due to wave2 contributed to the enhancement of static stability in the TIL immediately after the SSW.

Airflow accelerates bovine and human articular cartilage drying and chondrocyte death.

PubMed

Paterson, S I; Amin, A K; Hall, A C

2015-02-01

Exposure of articular cartilage to static air results in changes to the extracellular matrix (ECM) and stimulates chondrocyte death, which may cause joint degeneration. However during open orthopaedic surgery, cartilage is often exposed to laminar airflow, which may exacerbate these damaging effects. We compared drying in static and moving air in terms of cartilage appearance, hydration and chondrocyte viability, and tested the ability of saline-saturated gauze to limit the detrimental effects of air exposure. Articular cartilage from bovine metatarsophalangeal joints (N = 50) and human femoral heads (N = 6) was exposed for 90 min to (1) static air (2) airflow (up to 0.34 m/s), or (3) airflow (0.18 m/s), covered with gauze. Following air exposure, cartilage was also rehydrated (0.9% saline; 120 min) to determine the reversibility of drying effects. The influence of airflow was assessed by studying macroscopic appearance, and quantifying superficial zone (SZ) chondrocyte viability and cartilage hydration. Airflow caused advanced changes to cartilage appearance, accelerated chondrocyte death, and increased dehydration compared to static air. These effects were prevented if cartilage was covered by saline-saturated gauze. Cartilage rehydration reversed macroscopic changes associated with drying but the chondrocyte death was not altered. Chondrocytes at the cut edge of cartilage were more sensitive to drying compared to cells distant from the edge. Airflow significantly increased articular cartilage dehydration and chondrocyte death compared to static air. As laminar airflow is routinely utilised in operating theatres, it is essential that articular cartilage is kept wet via irrigation or by covering with saline-saturated gauze to prevent chondrocyte death. Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Static Holdup of Liquid Slag in Simulated Packed Coke Bed Under Oxygen Blast Furnace Ironmaking Conditions

NASA Astrophysics Data System (ADS)

Wang, Guang; Liu, Yingli; Zhou, Zhenfeng; Wang, Jingsong; Xue, Qingguo

2018-01-01

The liquid-phase flow behavior of slag in the lower zone of a blast furnace affects the furnace permeability, performance, and productivity. The effects of pulverized coal injection (PCI) on the behavior of simulated primary slag flow were investigated by quantifying the effect of key variables including Al/Si ratio [Al2O3 (wt.%) to SiO2 (wt.%)] and the amount of unburnt pulverized coal (UPC) at 1500°C. Viscosity analysis demonstrated that the slag fluidity decreased as the Al/Si ratio was increased (from 0.35 to 0.50), resulting in gradual increase of the static holdup. Increasing the amount of UPC resulted in a significant increase of the static holdup. Flooding analysis was applied to determine the maximum static holdup, which was found to be 11.5%. It was inferred that the burnout rates of pulverized coal should exceed 78.6% and 83.9% in traditional and oxygen blast furnaces, respectively.

Characterization of Triaxial Braided Composite Material Properties for Impact Simulation

NASA Technical Reports Server (NTRS)

Roberts, Gary D.; Goldberg, Robert K.; Biniendak, Wieslaw K.; Arnold, William A.; Littell, Justin D.; Kohlman, Lee W.

2009-01-01

The reliability of impact simulations for aircraft components made with triaxial braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Improvements to standard quasi-static test methods are needed to account for the large unit cell size and localized damage within the unit cell. The deformation and damage of a triaxial braided composite material was examined using standard quasi-static in-plane tension, compression, and shear tests. Some modifications to standard test specimen geometries are suggested, and methods for measuring the local strain at the onset of failure within the braid unit cell are presented. Deformation and damage at higher strain rates is examined using ballistic impact tests on 61- by 61- by 3.2-mm (24- by 24- by 0.125-in.) composite panels. Digital image correlation techniques were used to examine full-field deformation and damage during both quasi-static and impact tests. An impact analysis method is presented that utilizes both local and global deformation and failure information from the quasi-static tests as input for impact simulations. Improvements that are needed in test and analysis methods for better predictive capability are examined.

Comparison of dual-phase and static changeable message signs to convey airline information on interstate freeways.

DOT National Transportation Integrated Search

2010-01-01

The authors used a fully interactive PC-based STISIM driving simulator to compare dual-phase Changeable Message Signs (CMSs) and static CMSs. The participants were 120 licensed drivers from three age groups: 18-24, 32-47, and 55-65 years of age. They...

Comparison of static and dynamic computer-assisted guidance methods in implantology.

PubMed

Mischkowski, R A; Zinser, M J; Neugebauer, J; Kübler, A C; Zöller, J E

2006-01-01

The planning of dental implant position and its transfer to the operation site can be considered as one of the most important factors for the long-term success of implant-supported prosthetic and epithetic restorations. This study compares computer-assisted fabricated surgical templates as the static method with intro-operative image guided navigation as the dynamic method for transfer of three-dimensional pre-operative planning. For the static method, the systems Med3D, coDiagnostix/ gonyX, and SimPlant were used. For the dynamic method, the systems RoboDent und VectorVision2 were applied. A total of 746 implants were inserted between August 1999 and December 2005 in 206 patients. The static approach was used most frequently, accounting for 611 fixtures in 168 patients. The failure ratios within the first 6 months were 1.31% in the statically controlled insertion group compared to 2.96% in the dynamically controlled insertion group. Complications related to an incorrect position of the implants have not been observed so far in either group. All computer-assisted methods included in this study were successfully applied in a clinical setting after a certain start-up period. The indications for application of computer-assisted methods in implantology are currently given in difficult anatomical situations. Due to uncomplicated handling and low resource demands, the static template technique can be recommended as the method of choice for the majority of all cases falling into this category.

Refraction traveltime tomography based on damped wave equation for irregular topographic model

NASA Astrophysics Data System (ADS)

Park, Yunhui; Pyun, Sukjoon

2018-03-01

Land seismic data generally have time-static issues due to irregular topography and weathered layers at shallow depths. Unless the time static is handled appropriately, interpretation of the subsurface structures can be easily distorted. Therefore, static corrections are commonly applied to land seismic data. The near-surface velocity, which is required for static corrections, can be inferred from first-arrival traveltime tomography, which must consider the irregular topography, as the land seismic data are generally obtained in irregular topography. This paper proposes a refraction traveltime tomography technique that is applicable to an irregular topographic model. This technique uses unstructured meshes to express an irregular topography, and traveltimes calculated from the frequency-domain damped wavefields using the finite element method. The diagonal elements of the approximate Hessian matrix were adopted for preconditioning, and the principle of reciprocity was introduced to efficiently calculate the Fréchet derivative. We also included regularization to resolve the ill-posed inverse problem, and used the nonlinear conjugate gradient method to solve the inverse problem. As the damped wavefields were used, there were no issues associated with artificial reflections caused by unstructured meshes. In addition, the shadow zone problem could be circumvented because this method is based on the exact wave equation, which does not require a high-frequency assumption. Furthermore, the proposed method was both robust to an initial velocity model and efficient compared to full wavefield inversions. Through synthetic and field data examples, our method was shown to successfully reconstruct shallow velocity structures. To verify our method, static corrections were roughly applied to the field data using the estimated near-surface velocity. By comparing common shot gathers and stack sections with and without static corrections, we confirmed that the proposed tomography algorithm can be used to correct the statics of land seismic data.

Numerical analysis of stiffened shells of revolution. Volume 1: Theory manual for STARS-2S, 2B, 2V digital computer programs

NASA Technical Reports Server (NTRS)

Svalbonas, V.

1973-01-01

The theoretical analysis background for the STARS-2 (shell theory automated for rotational structures) program is presented. The theory involved in the axisymmetric nonlinear and unsymmetric linear static analyses, and the stability and vibrations (including critical rotation speed) analyses involving axisymmetric prestress are discussed. The theory for nonlinear static, stability, and vibrations analyses, involving shells with unsymmetric loadings are included.

Benchmark of FDNS CFD Code For Direct Connect RBCC Test Data

NASA Technical Reports Server (NTRS)

Ruf, J. H.

2000-01-01

Computational Fluid Dynamics (CFD) analysis results are compared with experimental data from the Pennsylvania State University's (PSU) Propulsion Engineering Research Center (PERC) rocket based combined cycle (RBCC) rocket-ejector experiments. The PERC RBCC experimental hardware was in a direct-connect configuration in diffusion and afterburning (DAB) operation. The objective of the present work was to validate the Finite Difference Navier Stokes (FDNS) CFD code for the rocket-ejector mode internal fluid mechanics and combustion phenomena. A second objective was determine the best application procedures to use FDNS as a predictive/engineering tool. Three-dimensional CFD analysis was performed. Solution methodology and grid requirements are discussed. CFD results are compared to experimental data for static pressure, Raman Spectroscopy species distribution data and RBCC net thrust and specified impulse.

Estimation of Handgrip Force from SEMG Based on Wavelet Scale Selection.

PubMed

Wang, Kai; Zhang, Xianmin; Ota, Jun; Huang, Yanjiang

2018-02-24

This paper proposes a nonlinear correlation-based wavelet scale selection technology to select the effective wavelet scales for the estimation of handgrip force from surface electromyograms (SEMG). The SEMG signal corresponding to gripping force was collected from extensor and flexor forearm muscles during the force-varying analysis task. We performed a computational sensitivity analysis on the initial nonlinear SEMG-handgrip force model. To explore the nonlinear correlation between ten wavelet scales and handgrip force, a large-scale iteration based on the Monte Carlo simulation was conducted. To choose a suitable combination of scales, we proposed a rule to combine wavelet scales based on the sensitivity of each scale and selected the appropriate combination of wavelet scales based on sequence combination analysis (SCA). The results of SCA indicated that the scale combination VI is suitable for estimating force from the extensors and the combination V is suitable for the flexors. The proposed method was compared to two former methods through prolonged static and force-varying contraction tasks. The experiment results showed that the root mean square errors derived by the proposed method for both static and force-varying contraction tasks were less than 20%. The accuracy and robustness of the handgrip force derived by the proposed method is better than that obtained by the former methods.

Design and Electro-Thermo-Mechanical Behavior Analysis of Au/Si₃N₄ Bimorph Microcantilevers for Static Mode Sensing.

PubMed

Kang, Seok-Won; Fragala, Joe; Kim, Su-Ho; Banerjee, Debjyoti

2017-11-01

This paper presents a design optimization method based on theoretical analysis and numerical calculations, using a commercial multi-physics solver (e.g., ANSYS and ESI CFD-ACE+), for a 3D continuous model, to analyze the bending characteristics of an electrically heated bimorph microcantilever. The results from the theoretical calculation and numerical analysis are compared with those measured using a CCD camera and magnification lenses for a chip level microcantilever array fabricated in this study. The bimorph microcantilevers are thermally actuated by joule heating generated by a 0.4 μm thin-film Au heater deposited on 0.6 μm Si₃N₄ microcantilevers. The initial deflections caused by residual stress resulting from the thermal bonding of two metallic layers with different coefficients of thermal expansion (CTEs) are additionally considered, to find the exact deflected position. The numerically calculated total deflections caused by electrical actuation show differences of 10%, on average, with experimental measurements in the operating current region (i.e., ~25 mA) to prevent deterioration by overheating. Bimorph microcantilevers are promising components for use in various MEMS (Micro-Electro-Mechanical System) sensing applications, and their deflection characteristics in static mode sensing are essential for detecting changes in thermal stress on the surface of microcantilevers.

Design and Electro-Thermo-Mechanical Behavior Analysis of Au/Si3N4 Bimorph Microcantilevers for Static Mode Sensing

PubMed Central

Kim, Su-Ho; Banerjee, Debjyoti

2017-01-01

This paper presents a design optimization method based on theoretical analysis and numerical calculations, using a commercial multi-physics solver (e.g., ANSYS and ESI CFD-ACE+), for a 3D continuous model, to analyze the bending characteristics of an electrically heated bimorph microcantilever. The results from the theoretical calculation and numerical analysis are compared with those measured using a CCD camera and magnification lenses for a chip level microcantilever array fabricated in this study. The bimorph microcantilevers are thermally actuated by joule heating generated by a 0.4 μm thin-film Au heater deposited on 0.6 μm Si3N4 microcantilevers. The initial deflections caused by residual stress resulting from the thermal bonding of two metallic layers with different coefficients of thermal expansion (CTEs) are additionally considered, to find the exact deflected position. The numerically calculated total deflections caused by electrical actuation show differences of 10%, on average, with experimental measurements in the operating current region (i.e., ~25 mA) to prevent deterioration by overheating. Bimorph microcantilevers are promising components for use in various MEMS (Micro-Electro-Mechanical System) sensing applications, and their deflection characteristics in static mode sensing are essential for detecting changes in thermal stress on the surface of microcantilevers. PMID:29104265

Driver hand activity analysis in naturalistic driving studies: challenges, algorithms, and experimental studies

NASA Astrophysics Data System (ADS)

Ohn-Bar, Eshed; Martin, Sujitha; Trivedi, Mohan Manubhai

2013-10-01

We focus on vision-based hand activity analysis in the vehicular domain. The study is motivated by the overarching goal of understanding driver behavior, in particular as it relates to attentiveness and risk. First, the unique advantages and challenges for a nonintrusive, vision-based solution are reviewed. Next, two approaches for hand activity analysis, one relying on static (appearance only) cues and another on dynamic (motion) cues, are compared. The motion-cue-based hand detection uses temporally accumulated edges in order to maintain the most reliable and relevant motion information. The accumulated image is fitted with ellipses in order to produce the location of the hands. The method is used to identify three hand activity classes: (1) two hands on the wheel, (2) hand on the instrument panel, (3) hand on the gear shift. The static-cue-based method extracts features in each frame in order to learn a hand presence model for each of the three regions. A second-stage classifier (linear support vector machine) produces the final activity classification. Experimental evaluation with different users and environmental variations under real-world driving shows the promise of applying the proposed systems for both postanalysis of captured driving data as well as for real-time driver assistance.

Advanced Wastewater Treatment Engineering—Investigating Membrane Fouling in both Rotational and Static Membrane Bioreactor Systems Using Empirical Modelling

PubMed Central

Paul, Parneet; Jones, Franck Anderson

2016-01-01

Advanced wastewater treatment using membranes are popular environmental system processes since they allow reuse and recycling. However, fouling is a key limiting factor and so proprietary systems such as Avanti’s RPU-185 Flexidisks membrane bioreactor (MBR) use novel rotating membranes to assist in ameliorating it. In earlier research, this rotating process was studied by creating a simulation model based on first principles and traditional fouling mechanisms. In order to directly compare the potential benefits of this rotational system, this follow-up study was carried out using Avanti’s newly developed static (non-rotating) Flexidisks MBR system. The results from operating the static pilot unit were simulated and modelled using the rotational fouling model developed earlier however with rotational switching functions turned off and rotational parameters set to a static mode. The study concluded that a rotating MBR system could increase flux throughput when compared against a similar static system. It is thought that although the slowly rotating spindle induces a weak crossflow shear, it is still able to even out cake build up across the membrane surface, thus reducing the likelihood of localised critical flux being exceeded at the micro level and lessening the potential of rapid trans-membrane pressure increases at the macro level. PMID:26742053

Transient analysis using conical shell elements

NASA Technical Reports Server (NTRS)

Yang, J. C. S.; Goeller, J. E.; Messick, W. T.

1973-01-01

The use of the NASTRAN conical shell element in static, eigenvalue, and direct transient analyses is demonstrated. The results of a NASTRAN static solution of an externally pressurized ring-stiffened cylinder agree well with a theoretical discontinuity analysis. Good agreement is also obtained between the NASTRAN direct transient response of a uniform cylinder to a dynamic end load and one-dimensional solutions obtained using a method of characteristics stress wave code and a standing wave solution. Finally, a NASTRAN eigenvalue analysis is performed on a hydroballistic model idealized with conical shell elements.

NASA LeRC/Akron University Graduate Cooperative Fellowship Program and Graduate Student Researchers Program

NASA Technical Reports Server (NTRS)

Fertis, D. G.; Simon, A. L.

1981-01-01

The requisite methodology to solve linear and nonlinear problems associated with the static and dynamic analysis of rotating machinery, their static and dynamic behavior, and the interaction between the rotating and nonrotating parts of an engine is developed. Linear and nonlinear structural engine problems are investigated by developing solution strategies and interactive computational methods whereby the man and computer can communicate directly in making analysis decisions. Representative examples include modifying structural models, changing material, parameters, selecting analysis options and coupling with interactive graphical display for pre- and postprocessing capability.

Cardiorespiratory deconditioning with static and dynamic leg exercise during bed rest

NASA Technical Reports Server (NTRS)

Stremel, R. W.; Convertino, V. A.; Bernauer, E. M.; Greenleaf, J. E.

1976-01-01

Results are presented for an experimental study designed to compare the effects of heavy static and dynamic exercise training during 14 days of bed rest on the cardiorespiratory responses to submaximal and maximal exercise performed by seven healthy men aged 19-22 yr. The parameters measured were submaximal and maximal oxygen uptake, minute ventilation, heart rate, and plasma volume. The results indicate that exercise alone during bed rest reduces but does not eliminate the reduction in maximal oxygen uptake. An additional positive hydrostatic effect is therefore necessary to restore maximal oxygen uptake to ambulatory control levels. The greater protective effect of static exercise on maximal oxygen uptake is probably due to a greater hydrostatic component from the isometric muscular contraction. Neither the static nor the dynamic exercise training regimes are found to minimize the changes in all the variables studied, thereby suggesting a combination of static and dynamic exercises.

A study on independently using static and dynamic light scattering methods to determine the coagulation rate

NASA Astrophysics Data System (ADS)

Zhou, Hongwei; Xu, Shenghua; Mi, Li; Sun, Zhiwei; Qin, Yanming

2014-09-01

Absolute coagulation rate constants were determined by independently, instead of simultaneously, using static and dynamic light scattering with the requested optical factors calculated by T-matrix method. The aggregating suspensions of latex particles with diameters of 500, 700, and 900 nm, that are all beyond validity limit of the traditional Rayleigh-Debye-Gans approximation, were adopted. The results from independent static and dynamic light scattering measurements were compared with those by simultaneously using static and dynamic light scattering; and three of them show good consistency. We found, theoretically and experimentally, that for independent static light scattering measurements there are blind scattering angles at that the scattering measurements become impossible and the number of blind angles increases rapidly with particle size. For independent dynamic light scattering measurements, however, there is no such a blind angle at all. A possible explanation of the observed phenomena is also presented.

An examination of the interrater reliability between practitioners and researchers on the static-99.

PubMed

Quesada, Stephen P; Calkins, Cynthia; Jeglic, Elizabeth L

2014-11-01

Many studies have validated the psychometric properties of the Static-99, the most widely used measure of sexual offender recidivism risk. However much of this research relied on instrument coding completed by well-trained researchers. This study is the first to examine the interrater reliability (IRR) of the Static-99 between practitioners in the field and researchers. Using archival data from a sample of 1,973 formerly incarcerated sex offenders, field raters' scores on the Static-99 were compared with those of researchers. Overall, clinicians and researchers had excellent IRR on Static-99 total scores, with IRR coefficients ranging from "substantial" to "outstanding" for the individual 10 items of the scale. The most common causes of discrepancies were coding manual errors, followed by item subjectivity, inaccurate item scoring, and calculation errors. These results offer important data with regard to the frequency and perceived nature of scoring errors. © The Author(s) 2013.

Carbohydrate-protein interactions investigated on plastic chips statically coated with hydrophobically modified hydroxyethylcellulose.

PubMed

Dang, Fuquan; Maeda, Eiki; Osafune, Tomo; Nakajima, Kazuki; Kakehi, Kazuaki; Ishikawa, Mitsuru; Baba, Yoshinobu

2009-12-15

We developed a novel method for rapid screening of carbohydrate-protein interactions using poly(methyl methacrylate) (PMMA) channels statically coated with hydrophobically modified hydroxyethylcellulose (HM-HEC). We found that a self-assembled monolayer (SAM) of HM-HEC on a PMMA surface intact by water allows rapid and reproducible separations of glycan samples using a 20 mM phosphate without HM-HEC. The underlying mechanism for dynamic and static coatings on the PMMA surface is discussed. Simultaneous analysis of the molecular interaction between a complex mixture of carbohydrates from alpha1-acid glycoprotein and proteins has been successfully achieved in PMMA channels statically coated with a SAM of HM-HEC.

Response, analysis, and design of pile groups subjected to static & dynamic lateral loads.

DOT National Transportation Integrated Search

2003-06-01

Static and dynamic lateral load tests were performed on four full-scale pile groups driven at four different spacings. P-multipliers to account for group : interaction effects were back-calculated for each test. P-multipliers were found to be a funct...

Elastic facial movement influences part-based but not holistic processing

PubMed Central

Xiao, Naiqi G.; Quinn, Paul C.; Ge, Liezhong; Lee, Kang

2013-01-01

Face processing has been studied for decades. However, most of the empirical investigations have been conducted using static face images as stimuli. Little is known about whether static face processing findings can be generalized to real world contexts, in which faces are constantly moving. The present study investigates the nature of face processing (holistic vs. part-based) in elastic moving faces. Specifically, we focus on whether elastic moving faces, as compared to static ones, can facilitate holistic or part-based face processing. Using the composite paradigm, participants were asked to remember either an elastic moving face (i.e., a face that blinks and chews) or a static face, and then tested with a static composite face. The composite effect was (1) significantly smaller in the dynamic condition than in the static condition, (2) consistently found with different face encoding times (Experiments 1–3), and (3) present for the recognition of both upper and lower face parts (Experiment 4). These results suggest that elastic facial motion facilitates part-based processing, rather than holistic processing. Thus, while previous work with static faces has emphasized an important role for holistic processing, the current work highlights an important role for featural processing with moving faces. PMID:23398253

Static properties and moisture content properties of polyester fabrics modified by plasma treatment and chemical finishing

NASA Astrophysics Data System (ADS)

Kan, C. W.; Yuen, C. W. M.

2008-01-01

Low temperature plasma treatment has been conducted in textile industry and has some success in the dyeing and finishing processes. In this paper, an attempt was made to apply low temperature plasma treatment to improve the anti-static property of polyester fabric. The polyester fabrics were treated under different conditions using low temperature plasma. An Orthogonal Array Testing Strategy was employed to determine the optimum treatment condition. After low temperature plasma treatment, the polyester fabrics were evaluated with different characterisation methods. Under the observation of scanning electron microscope, the surface structure of low temperature plasma-treated polyester fabric was seriously altered. This provided more capacity for polyester to capture moisture and hence increase the dissipation of static charges. The relationship between moisture content and half-life decay time for static charges was studied and the results showed that the increment of moisture content would result in shortening the time for the dissipation of static charges. Moreover, there was a great improvement in the anti-static property of the low temperature plasma-treated polyester fabric after comparing with that of the polyester fabric treated with commercial anti-static finishing agent.

Lattice QCD static potentials of the meson-meson and tetraquark systems computed with both quenched and full QCD

NASA Astrophysics Data System (ADS)

Bicudo, P.; Cardoso, M.; Oliveira, O.; Silva, P. J.

2017-10-01

We revisit the static potential for the Q Q Q ¯Q ¯ system using SU(3) lattice simulations, studying both the color singlets' ground state and first excited state. We consider geometries where the two static quarks and the two antiquarks are at the corners of rectangles of different sizes. We analyze the transition between a tetraquark system and a two-meson system with a two by two correlator matrix. We compare the potentials computed with quenched QCD and with dynamical quarks. We also compare our simulations with the results of previous studies and analyze quantitatively fits of our results with Ansätze inspired in the string flip-flop model and in its possible color excitations.

Static aeroelastic analysis of wings using Euler/Navier-Stokes equations coupled with improved wing-box finite element structures

NASA Technical Reports Server (NTRS)

Guruswamy, Guru P.; MacMurdy, Dale E.; Kapania, Rakesh K.

1994-01-01

Strong interactions between flow about an aircraft wing and the wing structure can result in aeroelastic phenomena which significantly impact aircraft performance. Time-accurate methods for solving the unsteady Navier-Stokes equations have matured to the point where reliable results can be obtained with reasonable computational costs for complex non-linear flows with shock waves, vortices and separations. The ability to combine such a flow solver with a general finite element structural model is key to an aeroelastic analysis in these flows. Earlier work involved time-accurate integration of modal structural models based on plate elements. A finite element model was developed to handle three-dimensional wing boxes, and incorporated into the flow solver without the need for modal analysis. Static condensation is performed on the structural model to reduce the structural degrees of freedom for the aeroelastic analysis. Direct incorporation of the finite element wing-box structural model with the flow solver requires finding adequate methods for transferring aerodynamic pressures to the structural grid and returning deflections to the aerodynamic grid. Several schemes were explored for handling the grid-to-grid transfer of information. The complex, built-up nature of the wing-box complicated this transfer. Aeroelastic calculations for a sample wing in transonic flow comparing various simple transfer schemes are presented and discussed.

Stability analysis and trend study of a balloon tethered in a wind, with experimental comparisons

NASA Technical Reports Server (NTRS)

Redd, L. T.; Bland, S. R.; Bennett, R. M.

1973-01-01

A stability analysis and trend study for a balloon tethered in a steady wind are presented. The linearized, stability-derivative type analysis includes balloon aerodynamics, buoyancy, mass (including apparent mass), and static forces resulting from the tether cable. The analysis has been applied to a balloon 7.64 m in length, and the results are compared with those from tow tests of this balloon. This comparison shows that the analysis gives reasonable predictions for the damping, frequencies, modes of motion, and stability boundaries exhibited by the balloon. A trend study for the 7.64-m balloon was made to illustrate how the stability boundaries are affected by changes in individual stability parameters. The trends indicated in this study may also be applicable to many other tethered-balloon systems.

Short-term predictive validity of the static-99 and static-99-R for indigenous and nonindigenous Australian sexual offenders.

PubMed

Smallbone, Stephen; Rallings, Mark

2013-06-01

Actuarial risk assessment (Static-99 and Static-99-R) scores were obtained for 399 Australian adult sexual offenders who were subsequently released from prison and followed up with searches of police arrest records (mean follow-up period = 29 months; range = 15-53 months). Indigenous offenders (n = 67; 16.8%) scored significantly higher on both the Static-99 (M = 4.04 vs. 2.89, p < .001) and Static-99-R (M = 3.72 vs. 2.22, p < .001), were more than twice as likely to be arrested for sexual offenses (9.0% vs. 4.1%, ns), and were significantly more likely to be arrested for nonsexual violent (28.4% vs. 1.9%, p < .001), any violent (including sexual; 37% vs. 5.9%, p < .001), and any offenses (58.2% vs. 21.6%, p < .001). For the combined groups, predictive accuracy of both instruments was comparable to results reported elsewhere. Predictive accuracy of the Static-99 was similar for indigenous and nonindigenous offenders. The Static-99-R was only marginally predictive of any violent recidivism (AUC = .65, 95% CI = [.52, .79]), and did not predict sexual (AUC = .61, 95% CI = [.45, .77]) or nonsexual violent recidivism (AUC = .65, 95% CI = [.48, .78]), for indigenous offenders. Higher risk scores, indigenous race, and unsupervised release all contributed unique variance to any violent recidivism. Results suggest that the Static-99 may be appropriate for assessing Australian indigenous sexual offenders, but more research is needed to test the validity of the Static-99-R for this population. We conclude that practitioners should consider the potential effects of racial differences and postrelease factors, as well as static risk factors, in their assessments.

[Demographic processes in the countries of Eastern Europe 1945-1990].

PubMed

Shchepin, O P; Vladimirova, L I

1990-01-01

An analysis is made of changes in the demographic processes in the countries of Eastern Europe over the period from 1945 to 1990 within both the general regularities and national peculiarities according to the parameters of statics and dynamics of population movement. The positive tendencies in the demographic processes are pointed out, first of all in infant mortality rates and mean expectation of life at birth in Eastern European countries by decades reflecting the peculiarities of changes as compared with developed countries.

Estimates of tropical analysis differences in daily values produced by two operational centers

NASA Technical Reports Server (NTRS)

Kasahara, Akira; Mizzi, Arthur P.

1992-01-01

To assess the uncertainty of daily synoptic analyses for the atmospheric state, the intercomparison of three First GARP Global Experiment level IIIb datasets is performed. Daily values of divergence, vorticity, temperature, static stability, vertical motion, mixing ratio, and diagnosed diabatic heating rate are compared for the period of 26 January-11 February 1979. The spatial variance and mean, temporal mean and variance, 2D wavenumber power spectrum, anomaly correlation, and normalized square difference are employed for comparison.

Pretest Round Robin Analysis of 1:4-Scale Prestressed Concrete Containment Vessel Model

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

HESSHEIMER,MICHAEL F.; LUK,VINCENT K.; KLAMERUS,ERIC W.

The purpose of the program is to investigate the response of representative scale models of nuclear containment to pressure loading beyond the design basis accident and to compare analytical predictions to measured behavior. This objective is accomplished by conducting static, pneumatic overpressurization tests of scale models at ambient temperature. This research program consists of testing two scale models: a steel containment vessel (SCV) model (tested in 1996) and a prestressed concrete containment vessel (PCCV) model, which is the subject of this paper.

Static-stress analysis of dual-axis safety vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

An 8 ft diameter safety vessel, made of HSLA-100 steel, is evaluated to determine its ability to contain the quasi-static residual pressure from a high explosive (HE) blast. The safety vessel is designed for use with the Dual-Axis Radiographic Hydrotest (DARHT) facility being developed at Los Alamos National Laboratory. A smaller confinement vessel fits inside the safety vessel and contains the actual explosion, and the safety vessel functions as a second layer of containment in the unlikely case of a confinement vessel leak. The safety vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC107. Combined stresses that result from internal pressure and external loads on nozzles are calculated and compared to the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzle components are adequately designed for a static pressure of 830 psi, plus the maximum expected external loads. Shell stresses at the 'shell to nozzle' interface, produced from external loads on the nozzles, were less than 700 psi. The maximum combined stress resulting from the internal pressure plus external loads was 17,384 psi, which is significantly less than the allowable stress of 42,375 psi for HSLA-100 steel.

Mixed aqueous solutions as dilution media in the determination of residual solvents by static headspace gas chromatography.

PubMed

D'Autry, Ward; Zheng, Chao; Wolfs, Kris; Yarramraju, Sitaramaraju; Hoogmartens, Jos; Van Schepdael, Ann; Adams, Erwin

2011-06-01

Static headspace (HS) sampling has been commonly used to test for volatile organic chemicals, usually referred to as residual solvents (RS) in pharmaceuticals. If the sample is not soluble in water, organic solvents are used. However, these seriously reduce the sensitivity in the determination of some RS. Here, mixed aqueous dilution media (a mixture of water and an organic solvent like dimethyl formamide, dimethyl sulfoxide or dimethyl acetamide) were studied as alternative media for static HS-gas chromatographic analysis. Although it has been known that mixed aqueous dilution media can often improve sensitivity for many RS, this study used a systematic approach to investigate phase volumes and the organic content in the HS sampling media. Reference solutions using 18 different class 1, 2 and 3 RS were evaluated. The effect of salt addition was also studied in this work. A significant increase in the peak area was observed for all RS using mixed aqueous dilution media, when compared with organic solvents alone. Matrix effects related to the mixed aqueous dilution media were also investigated and reported. Repeatability and linearity obtained with mixed aqueous dilution media were found to be similar to those observed with pure organic solvents. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vitro degradation behavior and cytocompatibility of Mg–Zn–Zr alloys

PubMed Central

Huan, Z. G.; Leeflang, M. A.; Fratila-Apachitei, L. E.; Duszczyk, J.

2010-01-01

Zinc and zirconium were selected as the alloying elements in biodegradable magnesium alloys, considering their strengthening effect and good biocompatibility. The degradation rate, hydrogen evolution, ion release, surface layer and in vitro cytotoxicity of two Mg–Zn–Zr alloys, i.e. ZK30 and ZK60, and a WE-type alloy (Mg–Y–RE–Zr) were investigated by means of long-term static immersion testing in Hank’s solution, non-static immersion testing in Hank’s solution and cell-material interaction analysis. It was found that, among these three magnesium alloys, ZK30 had the lowest degradation rate and the least hydrogen evolution. A magnesium calcium phosphate layer was formed on the surface of ZK30 sample during non-static immersion and its degradation caused minute changes in the ion concentrations and pH value of Hank’s solution. In addition, the ZK30 alloy showed insignificant cytotoxicity against bone marrow stromal cells as compared with biocompatible hydroxyapatite (HA) and the WE-type alloy. After prolonged incubation for 7 days, a stimulatory effect on cell proliferation was observed. The results of the present study suggested that ZK30 could be a promising material for biodegradable orthopedic implants and worth further investigation to evaluate its in vitro and in vivo degradation behavior. PMID:20532960

Annatto tocotrienol improves indices of bone static histomorphometry in osteoporosis due to testosterone deficiency in rats.

PubMed

Chin, Kok-Yong; Abdul-Majeed, Saif; Fozi, Nur Farhana Mohd; Ima-Nirwana, Soelaiman

2014-11-10

This study aimed to evaluate the effects of annatto tocotrienol on indices of bone static histomorphometry in orchidectomized rats. Forty male rats were randomized into baseline (BL), sham (SH), orchidectomized (ORX), annatto tocotrienol-treated (AnTT) and testosterone enanthate-treated (TE) groups. The BL group was sacrificed upon receipt. All rats except the SH group underwent bilateral orchidectomy. Annatto tocotrienol at 60 mg/kg body weight was administered orally daily to the AnTT group for eight weeks. Testosterone enanthate at 7 mg/kg body weight was administered intramuscularly once weekly for eight weeks to the TE group. The rat femurs were collected for static histomorphometric analysis upon necropsy. The results indicated that the ORX group had significantly higher osteoclast surface and eroded surface, and significantly lower osteoblast surface, osteoid surface and osteoid volume compared to the SH group (p < 0.05). Annatto tocotrienol and testosterone enanthate intervention prevented all these changes (p < 0.05). The efficacy of annatto tocotrienol was on par with testosterone enanthate. In conclusion, annatto tocotrienol at 60 mg/kg can prevent the imbalance in bone remodeling caused by increased osteoclast and bone resorption, and decreased osteoblast and bone formation. This serves as a basis for the application of annatto tocotrienol in hypogonadal men as an antiosteoporotic agent.

Annatto Tocotrienol Improves Indices of Bone Static Histomorphometry in Osteoporosis Due to Testosterone Deficiency in Rats

PubMed Central

Chin, Kok-Yong; Abdul-Majeed, Saif; Mohd. Fozi, Nur Farhana; Ima-Nirwana, Soelaiman

2014-01-01

This study aimed to evaluate the effects of annatto tocotrienol on indices of bone static histomorphometry in orchidectomized rats. Forty male rats were randomized into baseline (BL), sham (SH), orchidectomized (ORX), annatto tocotrienol-treated (AnTT) and testosterone enanthate-treated (TE) groups. The BL group was sacrificed upon receipt. All rats except the SH group underwent bilateral orchidectomy. Annatto tocotrienol at 60 mg/kg body weight was administered orally daily to the AnTT group for eight weeks. Testosterone enanthate at 7 mg/kg body weight was administered intramuscularly once weekly for eight weeks to the TE group. The rat femurs were collected for static histomorphometric analysis upon necropsy. The results indicated that the ORX group had significantly higher osteoclast surface and eroded surface, and significantly lower osteoblast surface, osteoid surface and osteoid volume compared to the SH group (p < 0.05). Annatto tocotrienol and testosterone enanthate intervention prevented all these changes (p < 0.05). The efficacy of annatto tocotrienol was on par with testosterone enanthate. In conclusion, annatto tocotrienol at 60 mg/kg can prevent the imbalance in bone remodeling caused by increased osteoclast and bone resorption, and decreased osteoblast and bone formation. This serves as a basis for the application of annatto tocotrienol in hypogonadal men as an antiosteoporotic agent. PMID:25389899

Electron acceleration by a focused laser pulse in a static magnetic field

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

Huang Shihua; Wu Fengmin; Zhao Xianghao

2007-12-15

The model given by K. P. Singh [Phys. Rev. E 69, 056410 (2004)] for vacuum laser acceleration in a static magnetic field is revisited by including the effects of diffraction and the longitudinal electric field of a focused laser beam. Compared with a similar model without a static magnetic field, a simulation shows that electrons can gain much more net energy in this model even using the fifth-order corrected equations for the field of a focused laser beam. The acceleration mechanism and the acceleration efficiency are also investigated.

3D Optical Investigation of 2 Nail Systems Used in Tibiotalocalcaneal Arthrodesis: A Biomechanical Study.

PubMed

Evers, Julia; Lakemeier, Martin; Wähnert, Dirk; Schulze, Martin; Richter, Martinus; Raschke, Michael J; Ochman, Sabine

2017-05-01

Although retrograde intramedullary nails for tibiotalocalcaneal arthrodesis (TTCA) are an established fixation method, few studies have evaluated the stability of the available nail systems. The purpose of this study was to compare biomechanically the primary stability of 2 nail-systems, A3 (Small Bone Innovations) and HAN (Synthes), in human cadavers and analyze the exact point of instability in TTCA by means of optical measurement. In 6 pairs of lower legs (n = 12) of fresh-frozen human cadavers with osteoporotic bone structure, bone mineral density (BMD) was determined. Pairwise randomized implantation of either an HAN or A3 nail was executed. Performance and stability were measured by quasi-static tests using 3D motion tracking (NDI Optotrak-Certus) followed by cyclic loading tests during dorsi- and plantarflexion. 3D optical analysis in quasi-static tests showed a significantly lower degree of movement for the HAN nail in rotational and dorsi-/plantarflexion, especially in the subtalar joint. Cyclic loading tests were consistent with quasi-static tests. The A3 nail offered lower stability during axial torsion in the ankle and subtalar joints and during plantar- and dorsiflexion in the subtalar joint in osteoporotic bones. This study was the first to examine the primary stability of different arthrodesis nails in TTCA and their bony parts with a 3D motion analysis. The better stability of the locking-only HAN nail in this osteoporotic test setup could lead to more favorable results in comparison to the A3 nail in clinical use.

[Design and verification of Luo-Ye pump-based stress formation for cultivation of tissue-engineered blood vessel].

PubMed

Liao, Wen-Jun; Chen, Wan-Wen; Wen, Zhang; Wu, Yue-Heng; Li, Dong-Feng; Zhou, Jia-Hui; Zheng, Jian-Yi; Lin, Zhan-Yi

2016-06-20

To improve Luo-Ye pump-based stress-forming system and optimize the stimulating effect on smooth muscle cells during cultivation of tissue-engineered blood vessels (TEBV). A new Luo-Ye pump-based TEBV 3D culture system was developed by adding an air pump to the output of the bioreactor. A pressure guide wire was used to measure the stress at different points of the silicone tube inside the TEBV bio-reactor, and fitting curves of the stress changes over time was created using Origin 8.0 software. The TEBVs were constructed by seeding vascular smooth muscle cells (VSMCs) isolated from human umbilical artery on polyglycolic acid (PGA) and cultured under dynamic conditions with 40 mmHg resistance (improved group), dynamic conditions without resistance (control group) or static condition (static group) for 4 weeks. The harvested TEBVs were then examined with HE staining, masson staining, α-SMA immunohistochemical staining, and scanning and transmission electron microscopy with semi-quantitative analysis of collagen content and α-SMA expression. The measured stress values and the fitting curves showed that the stress stimuli from the Luo-Ye pump were enhanced by adding an air pump to the output of the bioreactor. Histological analysis revealed improved VSMC density, collagen content and α-SMA expression in the TEBVs constructed with the improved method as compared with those in the control and static groups. Adding an air pump to the Luo-Ye pump significantly enhances the stress stimulation in the TEBV 3-D culture system to promote the secretion function of VSMCs.

Nondestructive Measurement of Dynamic Modulus for Cellulose Nanofibril Films

Treesearch

Yan Qing; Robert J. Ross; Zhiyong Cai; Yiqiang Wu

2013-01-01

Nondestructive evaluation of cellulose nanofibril (CNF) films was performed using cantilever beam vibration (CBV) and acoustic methods to measure dynamic modulus. Static modulus was tested using tensile tension method. Correlation analysis shows the data measured by CBV has little linear relationship with static modulus, possessing a correlation coefficient (R

Analysis of the Static Strength and Relative Endurance of Women Athletes

ERIC Educational Resources Information Center

Heyward, Vivian; McCreary, Leslie

1977-01-01

Investigations of static strength and relative endurance of the grip muscles of women athletes revealed that mean endurance time was significantly greater than for men. Results were discussed in light of evidence suggesting possible sex differences in muscle hypertrophy, capillarization of muscle tissue, critical occluding tension level, and…

Temporal variability of spectro-temporal receptive fields in the anesthetized auditory cortex.

PubMed

Meyer, Arne F; Diepenbrock, Jan-Philipp; Ohl, Frank W; Anemüller, Jörn

2014-01-01

Temporal variability of neuronal response characteristics during sensory stimulation is a ubiquitous phenomenon that may reflect processes such as stimulus-driven adaptation, top-down modulation or spontaneous fluctuations. It poses a challenge to functional characterization methods such as the receptive field, since these often assume stationarity. We propose a novel method for estimation of sensory neurons' receptive fields that extends the classic static linear receptive field model to the time-varying case. Here, the long-term estimate of the static receptive field serves as the mean of a probabilistic prior distribution from which the short-term temporally localized receptive field may deviate stochastically with time-varying standard deviation. The derived corresponding generalized linear model permits robust characterization of temporal variability in receptive field structure also for highly non-Gaussian stimulus ensembles. We computed and analyzed short-term auditory spectro-temporal receptive field (STRF) estimates with characteristic temporal resolution 5-30 s based on model simulations and responses from in total 60 single-unit recordings in anesthetized Mongolian gerbil auditory midbrain and cortex. Stimulation was performed with short (100 ms) overlapping frequency-modulated tones. Results demonstrate identification of time-varying STRFs, with obtained predictive model likelihoods exceeding those from baseline static STRF estimation. Quantitative characterization of STRF variability reveals a higher degree thereof in auditory cortex compared to midbrain. Cluster analysis indicates that significant deviations from the long-term static STRF are brief, but reliably estimated. We hypothesize that the observed variability more likely reflects spontaneous or state-dependent internal fluctuations that interact with stimulus-induced processing, rather than experimental or stimulus design.

Static balance function in children with a history of preterm birth

PubMed Central

Eshaghi, Zahra; Jafari, Zahra; Jalaie, Shohreh

2015-01-01

Background: The incomplete maturation of brain in preterm children results in long-term neurodevelopmental impairment. This study aimed to investigate the static balance function in children with a history of preterm birth. Methods: Participants were 31 preterm children including 21 moderately preterm (MPT), 10 very preterm (VPT), and 20 term children aged 5.5 and 6.5 years. The cervical vestibular-evoked myogenic potential (cVEMP) test and four static balance subscales of BOT-2 were performed. Results: The VPT children showed a significant increase in P1 and N1 wave latencies in cVEMP test compared to those in the term children (p= 0.041). Mean scores in the four static balance subscales of BOT-2 were significantly lower in the preterm children compared to those in the term children (p= 0.025). The P1 wave latency (p= 0.003) and mean score of standing on a balance beam with open eyes (p= 0.039) were significantly lower in the VPT children compared to those in the MPT children. A significant correlation was observed between the mean score in exercise 4 (standing on one leg on a balance beam with closed eyes) of static balance subscales of BOT-2 and P1 (r= -0.267, p= 0.036) and N1 (r= -0.304, p= 0.016) wave latencies of cVEMP. Conclusion: The longer latency of cVEMP waves along with a poor performance of children with a history of preterm birth suggests a possible defect in central vestibular pathway. PMID:26913273

Structure-activity relationships of pyrethroid insecticides. Part 2. The use of molecular dynamics for conformation searching and average parameter calculation

NASA Astrophysics Data System (ADS)

Hudson, Brian D.; George, Ashley R.; Ford, Martyn G.; Livingstone, David J.

1992-04-01

Molecular dynamics simulations have been performed on a number of conformationally flexible pyrethroid insecticides. The results indicate that molecular dynamics is a suitable tool for conformational searching of small molecules given suitable simulation parameters. The structures derived from the simulations are compared with the static conformation used in a previous study. Various physicochemical parameters have been calculated for a set of conformations selected from the simulations using multivariate analysis. The averaged values of the parameters over the selected set (and the factors derived from them) are compared with the single conformation values used in the previous study.

30 CFR 784.16 - Reclamation plan: Siltation structures, impoundments, and refuse piles.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Resources Conservation Service's Web site athttp://www.info.usda.gov/scripts/lpsiis.dll/TR/TR_210_60.htm... State program approval process engineering design standards that ensure stability comparable to a 1.3 minimum static safety factor in lieu of engineering tests to establish compliance with the minimum static...

Comparative Demonstration and Evaluation of Classification Technologies: Closed Castner Range, Fort Bliss, Texas

DTIC Science & Technology

2017-01-23

of classification technologies for Munitions Response (MR). This demonstration was designed to evaluate advanced classification methodology at the...advanced electromagnetic induction sensors and static, cued surveys to classify anomalies as either targets of interest (TOI) or non -TOI. Static data...17  5.1  Conceptual Experimental Design

Relationships between acoustic variables and different measures of stiffness in standing Pinus taeda trees

Treesearch

Christian R. Mora; Laurence R. Schimleck; Fikret Isik; Jerry M. Mahon Jr.; Alexander Clark III; Richard F. Daniels

2009-01-01

Acoustic tools are increasingly used to estimate standing-tree (dynamic) stiffness; however, such techniques overestimate static stiffness, the standard measurement for determining modulus of elasticity (MOE) of wood. This study aimed to identify correction methods for standing-tree estimates making dynamic and static stiffness comparable. Sixty Pinus taeda L...

Do Dynamic Work Instructions Provide an Advantage over Static Instructions in a Small Scale Assembly Task?

ERIC Educational Resources Information Center

Watson, Gareth; Butterfield, Joe; Curran, Ricky; Craig, Cathy

2010-01-01

Recent studies exploring the effects of instructional animations on learning compared to static graphics have yielded mixed results. Few studies have explored their effectiveness in portraying procedural-motor information. Opportunities exist within an applied (manufacturing) context for instructional animations to be used to facilitate build…

Use of Static Picture Prompts Versus Video Modeling during Simulation Instruction

ERIC Educational Resources Information Center

Alberto, Paul A.; Cihak, David F.; Gama, Robert I.

2005-01-01

The purpose of this study was to compare the effectiveness and efficiency of static picture prompts and video modeling as classroom simulation strategies in combination with in vivo community instruction. Students with moderate intellectual disabilities were instructed in the tasks of withdrawing money from an ATM and purchasing items using a…

Stress Distribution Around Single Short Dental Implants: A Finite Element Study.

PubMed

Vidya Bhat, S; Premkumar, Priyanka; Kamalakanth Shenoy, K

2014-12-01

Bone height restrictions are more common in the posterior regions of the mandible, because of either bone resorption resulting from tooth loss or even anatomic limitations, such as the position of the inferior alveolar nerve. In situations where adequate bone height is not available in the posterior mandible region, smaller lengths of implants may have to be used but it has been reported that the use of long implants (length ≥10 mm) is a positive factor in osseointegration and authors have reported failures with short implants. Hence knowledge about the stress generated on the bone with different lengths of implants needs scientific evaluation. The purpose of this study was to compare and evaluate the influence of different lengths of implants on stress upon bone in mandibular posterior area. A 3 D finite element model was made of the posterior mandible using the details from a CT scan, using computer software (ANSYS 12). Four simulated implants with lengths 6 mm, 8 mm, 10 mm and 13 mm were placed in the centre of the bone. A static vertical force of 250 N and a static horizontal force of 100 N were applied. The stress generated in the cortical and cancellous bone around the implant were recorded and evaluated with the help of ANSYS. In this study, Von Mises stress on a 6 mm implant under a static vertical load of 250 N appeared to be almost in the same range of 8 and 10 mm implant which were more as compared to 13 mm implant. Von Mises stress on a 6mm implant under a static horizontal load of 100 N appeared to be less when compared to 8, 10 and 13 mm implants. From the results obtained it may be inferred that under static horizontal loading conditions, shorter implants receive lesser load and thus may tend to transfer more stresses to the surrounding bone. While under static vertical loading the shorter implants bear more loads and comparatively transmit lesser load to the surrounding bone.

A Comparative Study of Some Dynamic Stall Models

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Kaza, K. R. V.

1987-01-01

Three semi-empirical aerodynamic stall models are compared with respect to their lift and moment hysteresis loop prediction, limit cycle behavior, easy implementation, and feasibility in developing the parameters required for stall flutter prediction of advanced turbines. For the comparison of aeroelastic response prediction including stall, a typical section model and a plate structural model are considered. The response analysis includes both plunging and pitching motions of the blades. In model A, a correction to the angle of attack is applied when the angle of attack exceeds the static stall angle. In model B, a synthesis procedure is used for angles of attack above static stall angles and the time history effects are accounted through the Wagner function. In both models the life and moment coefficients for angle of attack below stall are obtained from tabular data for a given Mach number and angle of attack. In model C, referred to an the ONERA model, the life and moment coefficients are given in the form of two differential equations, one for angles below stall, and the other for angles above stall. The parameters of those equations are nonlinear functions of the angle of attack.

Tumor Delineation and Quantitative Assessment of Glucose Metabolic Rate within Histologic Subtypes of Non-Small Cell Lung Cancer by Using Dynamic 18F Fluorodeoxyglucose PET.

PubMed

Meijer, Tineke W H; de Geus-Oei, Lioe-Fee; Visser, Eric P; Oyen, Wim J G; Looijen-Salamon, Monika G; Visvikis, Dimitris; Verhagen, Ad F T M; Bussink, Johan; Vriens, Dennis

2017-05-01

Purpose To assess whether dynamic fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) positron emission tomography (PET) has added value over static 18 F-FDG PET for tumor delineation in non-small cell lung cancer (NSCLC) radiation therapy planning by using pathology volumes as the reference standard and to compare pharmacokinetic rate constants of 18 F-FDG metabolism, including regional variation, between NSCLC histologic subtypes. Materials and Methods The study was approved by the institutional review board. Patients gave written informed consent. In this prospective observational study, 1-hour dynamic 18 F-FDG PET/computed tomographic examinations were performed in 35 patients (36 resectable NSCLCs) between 2009 and 2014. Static and parametric images of glucose metabolic rate were obtained to determine lesion volumes by using three delineation strategies. Pathology volume was calculated from three orthogonal dimensions (n = 32). Whole tumor and regional rate constants and blood volume fraction (V B ) were computed by using compartment modeling. Results Pathology volumes were larger than PET volumes (median difference, 8.7-25.2 cm 3 ; Wilcoxon signed rank test, P < .001). Static fuzzy locally adaptive Bayesian (FLAB) volumes corresponded best with pathology volumes (intraclass correlation coefficient, 0.72; P < .001). Bland-Altman analyses showed the highest precision and accuracy for static FLAB volumes. Glucose metabolic rate and 18 F-FDG phosphorylation rate were higher in squamous cell carcinoma (SCC) than in adenocarcinoma (AC), whereas V B was lower (Mann-Whitney U test or t test, P = .003, P = .036, and P = .019, respectively). Glucose metabolic rate, 18 F-FDG phosphorylation rate, and V B were less heterogeneous in AC than in SCC (Friedman analysis of variance). Conclusion Parametric images are not superior to static images for NSCLC delineation. FLAB-based segmentation on static 18 F-FDG PET images is in best agreement with pathology volume and could be useful for NSCLC autocontouring. Differences in glycolytic rate and V B between SCC and AC are relevant for research in targeting agents and radiation therapy dose escalation. © RSNA, 2016 Online supplemental material is available for this article.

Comparison of Static and Dynamic Elastic Modules of Different Strength Concretes

NASA Astrophysics Data System (ADS)

Uyanık, Osman; Sabbaǧ, Nevbahar

2016-04-01

In this study, the static and dynamic elastic (Young) modules of concrete with different strength was intended to compare. For this purpose 150mm dimensions 9 for each design cubic samples prepared and they were subjected to water cure during 28 days. After Seismic Ultrasonic P and S wave travel time measurements of samples, P and S wave velocities and taking advantage of elasticity theory the dynamic elastic modules were calculated. Concrete strength was obtained from the uniaxial compression tests in order to calculate the static elastic modules of the samples. The static elastic modulus is calculated by using the empirical relationships used in international standards. The obtained static and dynamic elastic modules have been associated. A curve was obtained from this association result that approximately similar to the stress-strain curve of obtaining at failure criterion of the sample. This study was supported with OYP05277-DR-14 Project No. by SDU and State Hydraulic Works 13th Regional/2012-01 Project No. Keywords: Concrete Strength, P and S wave Velocities, Static, Dynamic, Young Modules

New insight in spiral drawing analysis methods - Application to action tremor quantification.

PubMed

Legrand, André Pierre; Rivals, Isabelle; Richard, Aliénor; Apartis, Emmanuelle; Roze, Emmanuel; Vidailhet, Marie; Meunier, Sabine; Hainque, Elodie

2017-10-01

Spiral drawing is one of the standard tests used to assess tremor severity for the clinical evaluation of medical treatments. Tremor severity is estimated through visual rating of the drawings by movement disorders experts. Different approaches based on the mathematical signal analysis of the recorded spiral drawings were proposed to replace this rater dependent estimate. The objective of the present study is to propose new numerical methods and to evaluate them in terms of agreement with visual rating and reproducibility. Series of spiral drawings of patients with essential tremor were visually rated by a board of experts. In addition to the usual velocity analysis, three new numerical methods were tested and compared, namely static and dynamic unraveling, and empirical mode decomposition. The reproducibility of both visual and numerical ratings was estimated, and their agreement was evaluated. The statistical analysis demonstrated excellent agreement between visual and numerical ratings, and more reproducible results with numerical methods than with visual ratings. The velocity method and the new numerical methods are in good agreement. Among the latter, static and dynamic unravelling both display a smaller dispersion and are easier for automatic analysis. The reliable scores obtained through the proposed numerical methods allow considering that their implementation on a digitized tablet, be it connected with a computer or independent, provides an efficient automatic tool for tremor severity assessment. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Experimental study of geotextile as plinth beam in a pile group-supported modeled building frame

NASA Astrophysics Data System (ADS)

Ravi Kumar Reddy, C.; Gunneswara Rao, T. D.

2017-12-01

This paper presents the experimental results of static vertical load tests on a model building frame with geotextile as plinth beam supported by pile groups embedded in cohesionless soil (sand). The experimental results have been compared with those obtained from the nonlinear FEA and conventional method of analysis. The results revealed that the conventional method of analysis gives a shear force of about 53%, bending moment at the top of the column about 17% and at the base of the column about 50-98% higher than that by the nonlinear FEA for the frame with geotextile as plinth beam.

Constrained posture in dentistry - a kinematic analysis of dentists.

PubMed

Ohlendorf, Daniela; Erbe, Christina; Nowak, Jennifer; Hauck, Imke; Hermanns, Ingo; Ditchen, Dirk; Ellegast, Rolf; Groneberg, David A

2017-07-05

How a dentist works, such as the patterns of movements performed daily, is also largely affected by the workstation Dental tasks are often executed in awkward body positions, thereby causing a very high degree of strain on the corresponding muscles. The objective of this study is to detect those dental tasks, during which awkward postures occur most frequently. The isolated analysis of static postures will examine the duration for which these postures are maintained during the corresponding dental, respectively non-dental, activities. 21 (11f/10 m) dentists (age: 40.1 ± 10.4 years) participated in this study. An average dental workday was collected for every subject. To collect kinematic data of all activities, the CUELA system was used. Parallel to the kinematic examination, a detailed computer-based task analysis was conducted. Afterwards, both data sets were synchronized based on the chronological order of the postures assumed in the trunk and the head region. All tasks performed were assigned to the categories "treatment" (I), "office" (II) and "other activities" (III). The angle values of each body region (evaluation parameter) were examined and assessed corresponding to ergonomic standards. Moreover, this study placed a particular focus on static positions, which are held statically for 4 s and longer. For "treatment" (I), the entire head and trunk area is anteriorly tilted while the back is twisted to the right, in (II) and (III) the back is anteriorly tilted and twisted to the right (non-neutral position). Static positions in (I) last for 4-10s, static postures (approx. 60%) can be observed while in (II) and (III) in the back area static positions for more than 30 s are most common. Moreover, in (II) the back is twisted to the right for more than 60 s in 26.8%. Awkward positions are a major part of a dentists' work. This mainly pertains to static positions of the trunk and head in contrast to "office work." These insights facilitate the quantitative description of the dentist profession with regard to the related physical load along with the health hazards to the musculoskeletal system. Moreover, the results allow for a selective extraction of the most unfavorable static body positions that dentists assume for each of the activities performed.

Night Orthosis After Surgical Correction of Dupuytren Contractures: A Systematic Review.

PubMed

Samargandi, Osama A; Alyouha, Sarah; Larouche, Patricia; Corkum, Joseph P; Kemler, Marius A; Tang, David T

2017-10-01

To determine the role of night orthosis use after surgical correction of Dupuytren contracture. We searched MEDLINE, EMBASE, CINAHL, AMED, OTSeeker, and CENTRAL for articles published from inception of the databases to August 2015. Assessment was undertaken by 2 independent reviewers (O.A.S. and S.A.). Methodological quality of randomized controlled trials was assessed using the Cochrane risk of bias tool and the Newcastle-Ottawa instrument. Seven studies met the standard for inclusion in this review. A total of 659 patients across these 7 studies were included in the analysis, with follow-up ranging from 3 to 72 months. None of the included studies assessed recurrence. The analysis revealed no significant improvement in range of motion of hand joints for patients who received a static night orthosis after Dupuytren surgery compared with patients without an orthosis. Similarly, no differences were found in patient-reported functional status across the 2 groups. The current literature does not appear to support the use of static night orthosis in addition to hand therapy after surgical correction of Dupuytren contracture. Therapeutic IV. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Static Light Scattering from Concentrated Protein Solutions, I: General Theory for Protein Mixtures and Application to Self-Associating Proteins

PubMed Central

Minton, Allen P.

2007-01-01

Exact expressions for the static light scattering of a solution containing up to three species of point-scattering solutes in highly nonideal solutions at arbitrary concentration are obtained from multicomponent scattering theory. Explicit expressions for thermodynamic interaction between solute molecules, required to evaluate the scattering relations, are obtained using an equivalent hard particle approximation similar to that employed earlier to interpret scattering of a single protein species at high concentration. The dependence of scattering intensity upon total protein concentration is calculated for mixtures of nonassociating proteins and for a single self-associating protein over a range of concentrations up to 200 g/l. An approximate semiempirical analysis of the concentration dependence of scattering intensity is proposed, according to which the contribution of thermodynamic interaction to scattering intensity is modeled as that of a single average hard spherical species. Simulated data containing pseudo-noise comparable in magnitude to actual experimental uncertainty are modeled using relations obtained from the proposed semiempirical analysis. It is shown that by using these relations one can extract from the data reasonably reliable information about underlying weak associations that are manifested only at very high total protein concentration. PMID:17526566

Kicking modality during erratic-dynamic and static condition effects the muscular co-activation of attacker.

PubMed

Kim, Tae-Whan; Lee, Sang-Cheol; Kil, Se-Kee; Kang, Sung-Chul; Lim, Young-Tae; Kim, Ki-Tae; Panday, Siddhartha Bikram

2017-05-01

The purpose of the study was to investigate the effect of different kicking modality, i.e., erratic-dynamic target (EDT) versus static target (ST) on the performance of the roundhouse kick in two groups of taekwondo athletes of different skill level. Three-dimensional analysis and surface electromyography (SEMG) analysis were performed on 12 (Group A: six sub-elite, Group B: six elite) athletes to investigate muscle co-activation pattern under two conditions, i.e., EDT versus ST. In the results, the muscle recruitment ratio of the agonistic muscles was higher for Group A, whereas Group B had higher recruitment ratio for antagonist muscles. Overall, the co-activation index (CI) of hip joints appeared higher in the extensors for Group A, whereas higher CI was observed in flexor muscles for Group B with comparatively higher CI during EDT condition than ST condition. Higher value of CI was observed in flexor muscles of the knee joints among Group A during EDT conditions, in contrast, higher CI in the extensor muscles was observed among Group B during ST conditions. In conclusion, the study confirmed that erratic-dynamic movements of target could change the movement coordination pattern to maintain the joint stability of participants.

Mathematics and morphogenesis of cities: A geometrical approach

NASA Astrophysics Data System (ADS)

Courtat, Thomas; Gloaguen, Catherine; Douady, Stephane

2011-03-01

Cities are living organisms. They are out of equilibrium, open systems that never stop developing and sometimes die. The local geography can be compared to a shell constraining its development. In brief, a city’s current layout is a step in a running morphogenesis process. Thus cities display a huge diversity of shapes and none of the traditional models, from random graphs, complex networks theory, or stochastic geometry, takes into account the geometrical, functional, and dynamical aspects of a city in the same framework. We present here a global mathematical model dedicated to cities that permits describing, manipulating, and explaining cities’ overall shape and layout of their street systems. This street-based framework conciliates the topological and geometrical sides of the problem. From the static analysis of several French towns (topology of first and second order, anisotropy, streets scaling) we make the hypothesis that the development of a city follows a logic of division or extension of space. We propose a dynamical model that mimics this logic and that, from simple general rules and a few parameters, succeeds in generating a large diversity of cities and in reproducing the general features the static analysis has pointed out.

Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

NASA Technical Reports Server (NTRS)

Bragg-Sitton, S. M.; Farmer, J.; Dixon, D.; Kapernick, R.; Dickens, R.; Adams, M.

2007-01-01

Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Work at the NASA Marshall Space Flight Center seeks to develop high fidelity thermal simulators that not only match the static power profile that would be observed in an operating, fueled nuclear reactor, but to also match the dynamic fuel pin performance during feasible transients. Comparison between the fuel pins and thermal simulators is made at the fuel clad surface, which corresponds to the sheath surface in the thermal simulator. Static and dynamic fuel pin performance was determined using SINDA-FLUINT analysis, and the performance of conceptual thermal simulator designs was compared to the expected nuclear performance. Through a series of iterative analysis, a conceptual high fidelity design will be developed, followed by engineering design, fabrication, and testing to validate the overall design process. Although the resulting thermal simulator will be designed for a specific reactor concept, establishing this rigorous design process will assist in streamlining the thermal simulator development for other reactor concepts.

Investigating the Sensitivity of Model Intraseasonal Variability to Minimum Entrainment

NASA Astrophysics Data System (ADS)

Hannah, W. M.; Maloney, E. D.

2008-12-01

Previous studies have shown that using a Relaxed Arakawa-Schubert (RAS) convective parameterization with appropriate convective triggers and assumptions about rain re-evaporation produces realistic intraseasonal variability. RAS represents convection with an ensemble of clouds detraining at different heights, each with different entrainment rate, the highest clouds having the lowest entrainment rates. If tropospheric temperature gradients are weak and boundary layer moist static energy is relatively constant, then by limiting the minimum entrainment rate deep convection is suppressed in the presence of dry tropospheric air. This allows moist static energy to accumulate and be discharged during strong intraseasonal convective events, which is consistent with the discharge/recharge paradigm. This study will examine the sensitivity of intra-seasonal variability to changes in minimum entrainment rate in the NCAR-CAM3 with the RAS scheme. Simulations using several minimum entrainment rate thresholds will be investigated. A frequency-wavenumber analysis will show the improvement of the MJO signal as minimum entrainment rate is increased. The spatial and vertical structure of MJO-like disturbances will be examined, including an analysis of the time evolution of vertical humidity distribution for each simulation. Simulated results will be compared to observed MJO events in NCEP-1 reanalysis and CMAP precipitation.

Static sign language recognition using 1D descriptors and neural networks

NASA Astrophysics Data System (ADS)

Solís, José F.; Toxqui, Carina; Padilla, Alfonso; Santiago, César

2012-10-01

A frame work for static sign language recognition using descriptors which represents 2D images in 1D data and artificial neural networks is presented in this work. The 1D descriptors were computed by two methods, first one consists in a correlation rotational operator.1 and second is based on contour analysis of hand shape. One of the main problems in sign language recognition is segmentation; most of papers report a special color in gloves or background for hand shape analysis. In order to avoid the use of gloves or special clothing, a thermal imaging camera was used to capture images. Static signs were picked up from 1 to 9 digits of American Sign Language, a multilayer perceptron reached 100% recognition with cross-validation.

Static magnetotherapy for the treatment of insomnia.

PubMed

Shieh, Yao Y; Tsai, Fong Y

2008-01-01

Magnets have been used for centuries to treat a number of physical disorders. The vast majority of research, however, on static magnet therapy for insomnia has been confined to the auricular type of therapy, with publications limited to Chinese journals. Most of these studies have depended on the subjective self-assessment of participants rather than objective scientific measurements. In this study, the authors report the positive preliminary results of insomnia treatment using pillows with embedded magnets, magnetic insoles and TriPhase bracelets. The analysis is based on objective actigraphic and polysomnographic data. A theory of accelerated transition from wakefulness to sleep is proposed to explain the process of insomnia relief through low-strength static magnetic fields. Analysis by functional Magnetic Resonance Imaging (fMRI) is used to further investigate the theory.

Modeling of composite beams and plates for static and dynamic analysis

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Atilgan, Ali R.; Lee, Bok Woo

1990-01-01

A rigorous theory and corresponding computational algorithms was developed for a variety of problems regarding the analysis of composite beams and plates. The modeling approach is intended to be applicable to both static and dynamic analysis of generally anisotropic, nonhomogeneous beams and plates. Development of a theory for analysis of the local deformation of plates was the major focus. Some work was performed on global deformation of beams. Because of the strong parallel between beams and plates, the two were treated together as thin bodies, especially in cases where it will clarify the meaning of certain terminology and the motivation behind certain mathematical operations.

Analysis of dynamics and fit of diving suits

NASA Astrophysics Data System (ADS)

Mahnic Naglic, M.; Petrak, S.; Gersak, J.; Rolich, T.

2017-10-01

Paper presents research on dynamical behaviour and fit analysis of customised diving suits. Diving suits models are developed using the 3D flattening method, which enables the construction of a garment model directly on the 3D computer body model and separation of discrete 3D surfaces as well as transformation into 2D cutting parts. 3D body scanning of male and female test subjects was performed with the purpose of body measurements analysis in static and dynamic postures and processed body models were used for construction and simulation of diving suits prototypes. All necessary parameters, for 3D simulation were applied on obtained cutting parts, as well as parameters values for mechanical properties of neoprene material. Developed computer diving suits prototypes were used for stretch analysis on areas relevant for body dimensional changes according to dynamic anthropometrics. Garment pressures against the body in static and dynamic conditions was also analysed. Garments patterns for which the computer prototype verification was conducted were used for real prototype production. Real prototypes were also used for stretch and pressure analysis in static and dynamic conditions. Based on the obtained results, correlation analysis between body changes in dynamic positions and dynamic stress, determined on computer and real prototypes, was performed.

A Comparison of Quasi-Static Indentation Testing to Low Velocity Impact Testing

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Douglas, Michael J.

2001-01-01

The need for a static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low velocity impact tests were carried out and compared. Square specimens of many sizes and thickness were utilized to cover the array of types of low velocity impact events. Laminates with a n/4 stacking sequence were employed since this is by the most common type of engineering laminate. Three distinct flexural rigidities under two different boundary conditions were tested in order to obtain damage due to large deflections, contact stresses and both to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area and to a limited extent, load-deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low velocity impact tests, indicating that static indentation can be used to represent a low velocity impact event.

A Comparison of Quasi-Static Indentation to Low-Velocity Impact

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Douglas, M. J.

2000-01-01

A static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low-velocity impact tests were carried out and compared. Square specimens of many sizes and thicknesses were utilized to cover the array of types of low velocity impact events. Laminates with a pi/4 stacking sequence were employed since this is by far the most common type of engineering laminate. Three distinct flexural rigidities -under two different boundary conditions were tested in order to obtain damage ranging from that due to large deflection to contact stresses and levels in-between to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low-velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area, and to a limited extent, load-deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low-velocity impact tests, indicating that static indentation can be used to represent a low-velocity impact event.

The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata.

PubMed

Brzonkalik, Katrin; Herrling, Tanja; Syldatk, Christoph; Neumann, Anke

2011-05-27

The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28°C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production, various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides, disaccharides, complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose, fructose, sucrose, acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on mycotoxin production by A. alternata. Copyright © 2011 Elsevier B.V. All rights reserved.

Under conditions of large geometric miss, tumor control probability can be higher for static gantry intensity-modulated radiation therapy compared to volume-modulated arc therapy for prostate cancer.

PubMed

Balderson, Michael; Brown, Derek; Johnson, Patricia; Kirkby, Charles

2016-01-01

The purpose of this work was to compare static gantry intensity-modulated radiation therapy (IMRT) with volume-modulated arc therapy (VMAT) in terms of tumor control probability (TCP) under scenarios involving large geometric misses, i.e., those beyond what are accounted for when margin expansion is determined. Using a planning approach typical for these treatments, a linear-quadratic-based model for TCP was used to compare mean TCP values for a population of patients who experiences a geometric miss (i.e., systematic and random shifts of the clinical target volume within the planning target dose distribution). A Monte Carlo approach was used to account for the different biological sensitivities of a population of patients. Interestingly, for errors consisting of coplanar systematic target volume offsets and three-dimensional random offsets, static gantry IMRT appears to offer an advantage over VMAT in that larger shift errors are tolerated for the same mean TCP. For example, under the conditions simulated, erroneous systematic shifts of 15mm directly between or directly into static gantry IMRT fields result in mean TCP values between 96% and 98%, whereas the same errors on VMAT plans result in mean TCP values between 45% and 74%. Random geometric shifts of the target volume were characterized using normal distributions in each Cartesian dimension. When the standard deviations were doubled from those values assumed in the derivation of the treatment margins, our model showed a 7% drop in mean TCP for the static gantry IMRT plans but a 20% drop in TCP for the VMAT plans. Although adding a margin for error to a clinical target volume is perhaps the best approach to account for expected geometric misses, this work suggests that static gantry IMRT may offer a treatment that is more tolerant to geometric miss errors than VMAT. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

A Categorization of Dynamic Analyzers

NASA Technical Reports Server (NTRS)

Lujan, Michelle R.

1997-01-01

Program analysis techniques and tools are essential to the development process because of the support they provide in detecting errors and deficiencies at different phases of development. The types of information rendered through analysis includes the following: statistical measurements of code, type checks, dataflow analysis, consistency checks, test data,verification of code, and debugging information. Analyzers can be broken into two major categories: dynamic and static. Static analyzers examine programs with respect to syntax errors and structural properties., This includes gathering statistical information on program content, such as the number of lines of executable code, source lines. and cyclomatic complexity. In addition, static analyzers provide the ability to check for the consistency of programs with respect to variables. Dynamic analyzers in contrast are dependent on input and the execution of a program providing the ability to find errors that cannot be detected through the use of static analysis alone. Dynamic analysis provides information on the behavior of a program rather than on the syntax. Both types of analysis detect errors in a program, but dynamic analyzers accomplish this through run-time behavior. This paper focuses on the following broad classification of dynamic analyzers: 1) Metrics; 2) Models; and 3) Monitors. Metrics are those analyzers that provide measurement. The next category, models, captures those analyzers that present the state of the program to the user at specified points in time. The last category, monitors, checks specified code based on some criteria. The paper discusses each classification and the techniques that are included under them. In addition, the role of each technique in the software life cycle is discussed. Familiarization with the tools that measure, model and monitor programs provides a framework for understanding the program's dynamic behavior from different, perspectives through analysis of the input/output data.

The effect of visuals on non-native English students' learning of the basic principles and laws of motion

NASA Astrophysics Data System (ADS)

Yang, Quan

2001-10-01

This study, involving 154 undergraduate college students in China, was conducted to determine whether the surface structure of visual graphics affect content learning when the learner was a non-native English speaker and learning took place in a non-English speaking environment. Instruction with concrete animated graphics resulted in significantly higher achievement, when compared to instruction with concrete static, abstract static, abstract animated graphics or text only without any graphical illustrations. It was also found, unexpectedly, the text-only instruction resulted in the second best achievement, significantly higher than instruction with concrete static, abstract static, and abstract animated graphics. In addition, there was a significant interaction with treatment and test item, which indicated that treatment effects on graphic-specific items differed from those on definitional items. Additional findings indicated that relation to graphics directly or indirectly from the text that students studied had little impact on their performance in the posttests. Further, 51% of the participants indicated that they relied on some graphical images to answer the test questions and 19% relied heavily on graphics when completing the tests. In conclusion, concrete graphics when combined with animation played a significant role in enhancing ESL student performance and enabled the students to achieve the best learning outcomes as compared to abstract animated, concrete static, and abstract static graphics. This result suggested a significant innovation in the design and development of ESL curriculum in computer-based instruction, which would enable ESL students to perform better and achieve the expected outcomes in content area learning.

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility

PubMed Central

Wong, Del P.; Chaouachi, Anis; Lau, Patrick W.C.; Behm, David G.

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key points The duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). No significant differences in RSA and COD between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. PMID:24149890

Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility.

PubMed

Wong, Del P; Chaouachi, Anis; Lau, Patrick W C; Behm, David G

2011-01-01

This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments. Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.

A nonlinear auxetic structural vibration damper with metal rubber particles

NASA Astrophysics Data System (ADS)

Ma, Yanhong; Scarpa, Fabrizio; Zhang, Dayi; Zhu, Bin; Chen, Lulu; Hong, Jie

2013-08-01

The work describes the mechanical performance of a metal rubber particles (MRP) damper design based on an auxetic (negative Poisson’s ratio) cellular configuration. The auxetic damper configuration is constituted by an anti-tetrachiral honeycomb, where the cylinders are filled with the MRP material. The MRP samples have been subjected to quasi-static loading to measure the stiffness and loss factor from the static hysteresis curve. A parametric experimental analysis has been carried out to investigate the effect of relative density and filling percentage on the static performance of the MRP, and to identify design guidelines for best use of MRP devices. An experimental assessment of the integrated auxetic-MRP damper concept has been provided through static and dynamic force response techniques.

Design Trade Study for a 4-Meter Off-Axis Primary Mirror Substrate and Mount for the Habitable-Zone Exoplanet Direct Imaging Mission

NASA Technical Reports Server (NTRS)

Arnold, William R.; Stahl, H. Philip

2017-01-01

An extensive trade study was conducted to evaluate primary mirror substrate design architectures for the HabEx mission baseline 4-meter off-axis telescope. The study’s purpose is not to produce a final design, but rather to established a design methodology for matching the mirror’s properties (mass and stiffness) with the mission’s optical performance specifications (static dynamic wavefront error, WFE). The study systematically compares the effect of proven design elements (closed-back vs. open-back vs. partial-back; meniscus vs. flat back vs. shaped back; etc.), which can be implemented with proven space mirror materials (ULE and Zerodur), on static and dynamic WFE. Additionally, the study compares static and dynamic WFE of each substrate point design integrated onto three and six point mounts.

Design trade study for a 4-meter off-axis primary mirror substrate and mount for the Habitable-zone Exoplanet Direct Imaging Mission

NASA Astrophysics Data System (ADS)

Arnold, William R.; Stahl, H. Philip

2017-09-01

An extensive trade study was conducted to evaluate primary mirror substrate design architectures for the HabEx mission baseline 4-meter off-axis telescope. The study's purpose is not to produce a final design, but rather to established a design methodology for matching the mirror's properties (mass and stiffness) with the mission's optical performance specifications (static dynamic wavefront error, WFE). The study systematically compares the effect of proven design elements (closed-back vs open-back vs partial-back; meniscus vs flat back vs shaped back; etc.), which can be implemented with proven space mirror materials (ULE and Zerodur), on static and dynamic WFE. Additionally, the study compares static and dynamic WFE of each substrate point design integrated onto three and six point mounts.

Dynamic hardness of metals

NASA Astrophysics Data System (ADS)

Liang, Xuecheng

Dynamic hardness (Pd) of 22 different pure metals and alloys having a wide range of elastic modulus, static hardness, and crystal structure were measured in a gas pulse system. The indentation contact diameter with an indenting sphere and the radius (r2) of curvature of the indentation were determined by the curve fitting of the indentation profile data. r 2 measured by the profilometer was compared with that calculated from Hertz equation in both dynamic and static conditions. The results indicated that the curvature change due to elastic recovery after unloading is approximately proportional to the parameters predicted by Hertz equation. However, r 2 is less than the radius of indenting sphere in many cases which is contradictory to Hertz analysis. This discrepancy is believed due to the difference between Hertzian and actual stress distributions underneath the indentation. Factors which influence indentation elastic recovery were also discussed. It was found that Tabor dynamic hardness formula always gives a lower value than that directly from dynamic hardness definition DeltaE/V because of errors mainly from Tabor's rebound equation and the assumption that dynamic hardness at the beginning of rebound process (Pr) is equal to kinetic energy change of an impact sphere over the formed crater volume (Pd) in the derivation process for Tabor's dynamic hardness formula. Experimental results also suggested that dynamic to static hardness ratio of a material is primarily determined by its crystal structure and static hardness. The effects of strain rate and temperature rise on this ratio were discussed. A vacuum rotating arm apparatus was built to measure Pd at 70, 127, and 381 mum sphere sizes, these results exhibited that Pd is highly depended on the sphere size due to the strain rate effects. P d was also used to substitute for static hardness to correlate with abrasion and erosion resistance of metals and alloys. The particle size effects observed in erosion were also explained in terms of Pd change caused by sphere size change.

Influence of Mixed Mode I-Mode II Loading on Fatigue Delamination Growth Characteristics of a Graphite Epoxy Tape Laminate

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.; Johnston, William M., Jr.

2014-01-01

Mixed mode I-mode II interlaminar tests were conducted on IM7/8552 tape laminates using the mixed-mode bending test. Three mixed mode ratios, G(sub II)/G(sub T) = 0.2, 0.5, and 0.8, were considered. Tests were performed at all three mixed-mode ratios under quasi-static and cyclic loading conditions, where the former static tests were used to determine initial loading levels for the latter fatigue tests. Fatigue tests at each mixed-mode ratio were performed at four loading levels, Gmax, equal to 0.5G(sub c), 0.4G(sub c), 0.3G(sub c), and 0.2G(sub c), where G(sub c) is the interlaminar fracture toughness of the corresponding mixed-mode ratio at which a test was performed. All fatigue tests were performed using constant-amplitude load control and delamination growth was automatically documented using compliance solutions obtained from the corresponding quasi-static tests. Static fracture toughness data yielded a mixed-mode delamination criterion that exhibited monotonic increase in Gc with mixed-mode ratio, G(sub II)/G(sub T). Fatigue delamination onset parameters varied monotonically with G(sub II)/G(sub T), which was expected based on the fracture toughness data. Analysis of non-normalized data yielded a monotonic change in Paris law exponent with mode ratio. This was not the case when normalized data were analyzed. Fatigue data normalized by the static R-curve were most affected in specimens tested at G(sub II)/G(sub T)=0.2 (this process has little influence on the other data). In this case, the normalized data yielded a higher delamination growth rate compared to the raw data for a given loading level. Overall, fiber bridging appeared to be the dominant mechanism, affecting delamination growth rates in specimens tested at different load levels and differing mixed-mode ratios.

Structural Finite Element Model Updating Using Vibration Tests and Modal Analysis for NPL footbridge - SHM demonstrator

NASA Astrophysics Data System (ADS)

Barton, E.; Middleton, C.; Koo, K.; Crocker, L.; Brownjohn, J.

2011-07-01

This paper presents the results from collaboration between the National Physical Laboratory (NPL) and the University of Sheffield on an ongoing research project at NPL. A 50 year old reinforced concrete footbridge has been converted to a full scale structural health monitoring (SHM) demonstrator. The structure is monitored using a variety of techniques; however, interrelating results and converting data to knowledge are not possible without a reliable numerical model. During the first stage of the project, the work concentrated on static loading and an FE model of the undamaged bridge was created, and updated, under specified static loading and temperature conditions. This model was found to accurately represent the response under static loading and it was used to identify locations for sensor installation. The next stage involves the evaluation of repair/strengthening patches under both static and dynamic loading. Therefore, before deliberately introducing significant damage, the first set of dynamic tests was conducted and modal properties were estimated. The measured modal properties did not match the modal analysis from the statically updated FE model; it was clear that the existing model required updating. This paper introduces the results of the dynamic testing and model updating. It is shown that the structure exhibits large non-linear, amplitude dependant characteristics. This creates a difficult updating process, but we attempt to produce the best linear representation of the structure. A sensitivity analysis is performed to determine the most sensitive locations for planned damage/repair scenarios and is used to decide whether additional sensors will be necessary.

Flight-test data on the static fore-and-aft stability of various German airplanes

NASA Technical Reports Server (NTRS)

Hubner, Walter

1933-01-01

The static longitudinal stability of an airplane with locked elevator is usually determined by analysis and model tests. The present report proposes to supply the results of such measurements. The method consisted of recording the dynamic pressure versus elevator displacement at different center-of-gravity positions in unaccelerated flight.

Experience patterns: capturing the dynamic nature of a recreation experience

Treesearch

R.B., IV Hull; William P. Stewart; Young K. Yi

1992-01-01

A recreation experience is not static, it varies over the course of an engagement. Yet, most recreation research operationalizes recreation benefits andoutcomes as essentially static in nature (i.e., satisfaction). "Experience patterns" capture the dynamic nature of a recreation experience and thus might prove useful as units of analysis in the management and...

Study of Geometric Porosity on Static Stability and Drag Using Computational Fluid Dynamics for Rigid Parachute Shapes

NASA Technical Reports Server (NTRS)

Greathouse, James S.; Schwing, Alan M.

2015-01-01

This paper explores use of computational fluid dynamics to study the e?ect of geometric porosity on static stability and drag for NASA's Multi-Purpose Crew Vehicle main parachute. Both of these aerodynamic characteristics are of interest to in parachute design, and computational methods promise designers the ability to perform detailed parametric studies and other design iterations with a level of control previously unobtainable using ground or flight testing. The approach presented here uses a canopy structural analysis code to define the inflated parachute shapes on which structured computational grids are generated. These grids are used by the computational fluid dynamics code OVERFLOW and are modeled as rigid, impermeable bodies for this analysis. Comparisons to Apollo drop test data is shown as preliminary validation of the technique. Results include several parametric sweeps through design variables in order to better understand the trade between static stability and drag. Finally, designs that maximize static stability with a minimal loss in drag are suggested for further study in subscale ground and flight testing.

Tilted orthodontic micro implants: a photoelastic stress analysis.

PubMed

Çehreli, Seçil; Özçırpıcı, Ayça Arman; Yılmaz, Alev

2013-10-01

The aim of this study was to examine peri-implant stresses around orthodontic micro implants upon torque-tightening and static load application by quasi-three-dimensional photoelastic stress analysis. Self-tapping orthodontic micro implants were progressively inserted into photoelastic models at 30, 45, 70, and 90 degrees and insertion torques were measured. Stress patterns (isochromatic fringe orders) were recorded by the quasi-three-dimensional photoelastic method using a circular polariscope after insertion and 250 g static force application. Torque-tightening of implants generated peri-implant stresses. Upon insertion, 90 degree placed implants displayed the lowest and homogeneous stress distribution followed by 30, 70, and 45 degree tilted implants. Static loading did not dramatically alter stress fields around the implants tested. The highest alteration in stress distribution was observed for the 90 degree placed implant, while 70 degree tilted implant had the lowest stresses among tilted implants. Torque-tightening of orthodontic micro implants creates a stress field that is not dramatically altered after application of static lateral moderate orthodontic loads, particularly at the cervical region of tilted implants.

Influence of Installation Effects on Pile Bearing Capacity in Cohesive Soils - Large Deformation Analysis Via Finite Element Method

NASA Astrophysics Data System (ADS)

Konkol, Jakub; Bałachowski, Lech

2017-03-01

In this paper, the whole process of pile construction and performance during loading is modelled via large deformation finite element methods such as Coupled Eulerian Lagrangian (CEL) and Updated Lagrangian (UL). Numerical study consists of installation process, consolidation phase and following pile static load test (SLT). The Poznań site is chosen as the reference location for the numerical analysis, where series of pile SLTs have been performed in highly overconsolidated clay (OCR ≈ 12). The results of numerical analysis are compared with corresponding field tests and with so-called "wish-in-place" numerical model of pile, where no installation effects are taken into account. The advantages of using large deformation numerical analysis are presented and its application to the pile designing is shown.

Penetration analysis of projectile with inclined concrete target

NASA Astrophysics Data System (ADS)

Kim, S. B.; Kim, H. W.; Yoo, Y. H.

2015-09-01

This paper presents numerical analysis result of projectile penetration with concrete target. We applied dynamic material properties of 4340 steels, aluminium and explosive for projectile body. Dynamic material properties were measured with static tensile testing machine and Hopkinson pressure bar tests. Moreover, we used three concrete damage models included in LS-DYNA 3D, such as SOIL_CONCRETE, CSCM (cap model with smooth interaction) and CONCRETE_DAMAGE (K&C concrete) models. Strain rate effect for concrete material is important to predict the fracture deformation and shape of concrete, and penetration depth for projectiles. CONCRETE_DAMAGE model with strain rate effect also applied to penetration analysis. Analysis result with CSCM model shows good agreement with penetration experimental data. The projectile trace and fracture shapes of concrete target were compared with experimental data.

Numerical study on the aerodynamic characteristics of both static and flapping wing with attachments

NASA Astrophysics Data System (ADS)

Xie, Lingwang; Zhang, Xingwei; Luo, Pan; Huang, Panpan

2017-10-01

The purpose of this paper is to investigate the aerodynamic mechanism of airfoils under different icing situations which are different icing type, different icing time, and different icing position. Numerical simulation is carried out by using the finite volume method for both static and flapping airfoils, when Reynolds number is kept at 135000. The difference of aerodynamic performance between the airfoil with attachments and without attachments are be investigated by comparing the force coefficients, lift-to-drag ratios and flow field contour. The present simulations reveal that some influences of attachment are similar in the static airfoil and the flapping airfoil. Specifically, the airfoil with the attachment derived from glaze ice type causes the worse aerodynamic performance than that derived from rime ice type. The longer the icing time, the greater influence of aerodynamic performance the attachment causes. The attachments on the leading-edge have the greater influence of aerodynamic performance than other positions. Moreover, there are little differences between the static airfoil and the flapping airfoil. Compared with the static airfoil, the flapping airfoil which attachment located on the trailing edge causes a worse aerodynamic performance. Both attachments derived from rime ice type and glaze ice type all will deteriorate the aerodynamic performance of the asymmetrical airfoils. Present work provides the systematic and comprehensive study about icing blade which is conducive to the development of the wind power generation technology.

Three Dimensional Compressible Turbulent Flow Computations for a Diffusing S-Duct With/Without Vortex Generators

NASA Technical Reports Server (NTRS)

Cho, Soo-Yong; Greber, Isaac

1994-01-01

Numerical investigations on a diffusing S-duct with/without vortex generators and a straight duct with vortex generators are presented. The investigation consists of solving the full three-dimensional unsteady compressible mass averaged Navier-Stokes equations. An implicit finite volume lower-upper time marching code (RPLUS3D) has been employed and modified. A three-dimensional Baldwin-Lomax turbulence model has been modified in conjunction with the flow physics. A model for the analysis of vortex generators in a fully viscous subsonic internal flow is evaluated. A vortical structure for modeling the shed vortex is used as a source term in the computation domain. The injected vortex paths in the straight duct are compared with the analysis by two kinds of prediction models. The flow structure by the vortex generators are investigated along the duct. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with the experimental wall static-pressure, static- and total-pressure field, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and velocity profiles in wall coordinates are presented. In order to investigate the effect of vortex generators, various vortex strengths are examined in this study. The total-pressure recovery and distortion coefficients are obtained at the exit of the S-duct. The numerical results clearly depict the interaction between the low velocity flow by the flow separation and the injected vortices.

Effect of moderate magnetic annealing on the microstructure, quasi-static and viscoelastic mechanical behavior of a structural epoxy

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

Tehrani, Mehran; Al-Haik, Marwan; Garmestani, Hamid

2012-01-01

In this study the effect of moderate magnetic fields on the microstructure of a structural epoxy system was investigated. The changes in the microstructure have been quantitatively investigated using wide angle x-ray diffraction (WAXD) and pole figure analysis. The mechanical properties (modulus, hardness and strain rate sensitivity parameter) of the epoxy system annealed in the magnetic field were probed with the aid of instrumented nanoindentation and the results are compared to the reference epoxy sample. To further examine the creep response of the magnetically annealed and reference samples, short 45 min duration creep tests were carried out. An equivalent tomore » the macro scale creep compliance was calculated using the aforementioned nano-creep data. Using the continuous complex compliance (CCC) analysis, the phase lag angle, tan (δ), between the displacement and applied force in an oscillatory nanoindentation test was measured for both neat and magnetically annealed systems through which the effect of low magnetic fields on the viscoelastic properties of the epoxy was invoked. The comparison of the creep strain rate sensitivity parameter , A/d(0), from short term(80 ), creep tests and the creep compliance J(t) from the long term(2700 s) creep tests with the tan(δ) suggests that former parameter is a more useful comparative creep parameter than the creep compliance. The results of this investigation reveal that under low magnetic fields both the quasi-static and viscoelastic mechanical properties of the epoxy have been improved.« less

Effects of static orientation upon human optokinetic afternystagmus

NASA Technical Reports Server (NTRS)

Wall, C. 3rd; Merfeld, D. M.; Zupan, L.

1999-01-01

"Normal" human subjects were placed in a series of 5 static orientations with respect to gravity and were asked to view an optokinetic display moving at a constant angular velocity. The axis of rotation coincided with the subject's rostro-caudal axis and produced horizontal optokinetic nystagmus and afternystagmus. Wall (1) previously reported that these optokinetic afternystagmus responses were not well characterized by parametric fits to slow component velocity. The response for nose-up, however, was larger than for nose-down. This suggested that the horizontal eye movements measured during optokinetic stimulation might include an induced linear VOR component as presented in the body of this paper. To investigate this hypothesis, another analysis of these data has been made using cumulative slow component eye position. Some subjects' responses had reversals in afternystagmus direction. These reversals were "filled in" by a zero slow component velocity. This method of analysis gives a much more consistent result across subjects and shows that, on average, responses from the nose-down horizontal (prone) orientation are greatly reduced (p < 0.05) compared to other horizontal and vertical orientations. Average responses are compared to responses predicted by a model previously used to predict successfully the responses to post-rotatory nystagmus after earth horizontal axis rotation. Ten of 11 subjects had larger responses in their supine than their prone orientation. Application of horizontal axis optokinetic afternystagmus for clinical otolith function testing, and implications for altered gravity experiments are discussed.

Static Balance: A Comparative Study of Primary Age Boys and Girls.

ERIC Educational Resources Information Center

DiNucci, James M.

The ability to attain and maintain a body position or balance is considered important in learning and performing motor skills. Static balance is defined as balance in which the body maintains equilibrium for one position; dynamic balance is described as maintaining equilibrium while the body is in motion or changing from one balanced position to…

The Influences of Static and Interactive Dynamic Facial Stimuli on Visual Strategies in Persons with Asperger Syndrome

ERIC Educational Resources Information Center

Falkmer, Marita; Bjallmark, Anna; Larsson, Matilda; Falkmer, Torbjorn

2011-01-01

Several studies, using eye tracking methodology, suggest that different visual strategies in persons with autism spectrum conditions, compared with controls, are applied when viewing facial stimuli. Most eye tracking studies are, however, made in laboratory settings with either static (photos) or non-interactive dynamic stimuli, such as video…

When static media promote active learning: annotated illustrations versus narrated animations in multimedia instruction.

PubMed

Mayer, Richard E; Hegarty, Mary; Mayer, Sarah; Campbell, Julie

2005-12-01

In 4 experiments, students received a lesson consisting of computer-based animation and narration or a lesson consisting of paper-based static diagrams and text. The lessons used the same words and graphics in the paper-based and computer-based versions to explain the process of lightning formation (Experiment 1), how a toilet tank works (Experiment 2), how ocean waves work (Experiment 3), and how a car's braking system works (Experiment 4). On subsequent retention and transfer tests, the paper group performed significantly better than the computer group on 4 of 8 comparisons, and there was no significant difference on the rest. These results support the static media hypothesis, in which static illustrations with printed text reduce extraneous processing and promote germane processing as compared with narrated animations.

Kinks in higher derivative scalar field theory

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Guo, Rong-Zhen; Fu, Chun-E.; Liu, Yu-Xiao

2018-07-01

We study static kink configurations in a type of two-dimensional higher derivative scalar field theory whose Lagrangian contains second-order derivative terms of the field. The linear fluctuation around arbitrary static kink solutions is analyzed. We find that, the linear spectrum can be described by a supersymmetric quantum mechanics problem, and the criteria for stable static solutions can be given analytically. We also construct a superpotential formalism for finding analytical static kink solutions. Using this formalism we first reproduce some existed solutions and then offer a new solution. The properties of our solution is studied and compared with those preexisted. We also show the possibility in constructing twinlike model in the higher derivative theory, and give the consistency conditions for twinlike models corresponding to the canonical scalar field theory.

A domain decomposition approach to implementing fault slip in finite-element models of quasi-static and dynamic crustal deformation

USGS Publications Warehouse

Aagaard, Brad T.; Knepley, M.G.; Williams, C.A.

2013-01-01

We employ a domain decomposition approach with Lagrange multipliers to implement fault slip in a finite-element code, PyLith, for use in both quasi-static and dynamic crustal deformation applications. This integrated approach to solving both quasi-static and dynamic simulations leverages common finite-element data structures and implementations of various boundary conditions, discretization schemes, and bulk and fault rheologies. We have developed a custom preconditioner for the Lagrange multiplier portion of the system of equations that provides excellent scalability with problem size compared to conventional additive Schwarz methods. We demonstrate application of this approach using benchmarks for both quasi-static viscoelastic deformation and dynamic spontaneous rupture propagation that verify the numerical implementation in PyLith.

In-plane stability analysis of non-uniform cross-sectioned curved beams

NASA Astrophysics Data System (ADS)

Öztürk, Hasan; Yeşilyurt, İsa; Sabuncu, Mustafa

2006-09-01

In this study, in-plane stability analysis of non-uniform cross-sectioned thin curved beams under uniformly distributed dynamic loads is investigated by using the Finite Element Method. The first and second unstable regions are examined for dynamic stability. In-plane vibration and in-plane buckling are also studied. Two different finite element models, representing variations of cross-section, are developed by using simple strain functions in the analysis. The results obtained from this study are compared with the results of other investigators in existing literature for the fundamental natural frequency and critical buckling load. The effects of opening angle, variations of cross-section, static and dynamic load parameters on the stability regions are shown in graphics.

Hemodynamic analysis of intracranial aneurysms using phase-contrast magnetic resonance imaging and computational fluid dynamics

NASA Astrophysics Data System (ADS)

Zhao, Xuemei; Li, Rui; Chen, Yu; Sia, Sheau Fung; Li, Donghai; Zhang, Yu; Liu, Aihua

2017-04-01

Additional hemodynamic parameters are highly desirable in the clinical management of intracranial aneurysm rupture as static medical images cannot demonstrate the blood flow within aneurysms. There are two ways of obtaining the hemodynamic information—by phase-contrast magnetic resonance imaging (PCMRI) and computational fluid dynamics (CFD). In this paper, we compared PCMRI and CFD in the analysis of a stable patient's specific aneurysm. The results showed that PCMRI and CFD are in good agreement with each other. An additional CFD study of two stable and two ruptured aneurysms revealed that ruptured aneurysms have a higher statistical average blood velocity, wall shear stress, and oscillatory shear index (OSI) within the aneurysm sac compared to those of stable aneurysms. Furthermore, for ruptured aneurysms, the OSI divides the positive and negative wall shear stress divergence at the aneurysm sac.

Experimental and Numerical Analysis of Notched Composites Under Tension Loading

NASA Astrophysics Data System (ADS)

Aidi, Bilel; Case, Scott W.

2015-12-01

Experimental quasi-static tests were performed on center notched carbon fiber reinforced polymer (CFRP) composites having different stacking sequences made of G40-600/5245C prepreg. The three-dimensional Digital Image Correlation (DIC) technique was used during quasi-static tests conducted on quasi-isotropic notched samples to obtain the distribution of strains as a function of applied stress. A finite element model was built within Abaqus to predict the notched strength and the strain profiles for comparison with measured results. A user-material subroutine using the multi-continuum theory (MCT) as a failure initiation criterion and an energy-based damage evolution law as implemented by Autodesk Simulation Composite Analysis (ASCA) was used to conduct a quantitative comparison of strain components predicted by the analysis and obtained in the experiments. Good agreement between experimental data and numerical analyses results are observed. Modal analysis was carried out to investigate the effect of static damage on the dominant frequencies of the notched structure using the resulted degraded material elements. The first in-plane mode was found to be a good candidate for tracking the level of damage.

Prediction of future falls in a community dwelling older adult population using instrumented balance and gait analysis.

PubMed

Bauer, C M; Gröger, I; Rupprecht, R; Marcar, V L; Gaßmann, K G

2016-04-01

The role of instrumented balance and gait assessment when screening for prospective fallers is currently a topic of controversial discussion. This study analyzed the association between variables derived from static posturography, instrumented gait analysis and clinical assessments with the occurrence of prospective falls in a sample of community dwelling older people. In this study 84 older people were analyzed. Based on a prospective occurrence of falls, participants were categorized into fallers and non-fallers. Variables derived from clinical assessments, static posturography and instrumented gait analysis were evaluated with respect to the association with the occurrence of prospective falls using a forward stepwise, binary, logistic regression procedure. Fallers displayed a significantly shorter single support time during walking while counting backwards, increased mediolateral to anteroposterior sway amplitude ratio, increased fast mediolateral oscillations and a larger coefficient (Coeff) of sway direction during various static posturography tests. Previous falls were insignificantly associated with the occurrence of prospective falls. Variables derived from posturography and instrumented gait analysis showed significant associations with the occurrence of prospective falls in a sample of community dwelling older adults.

Degradation of learned skills. Static practice effectiveness for visual approach and landing skill retention

NASA Technical Reports Server (NTRS)

Sitterley, T. E.

1974-01-01

The effectivess of an improved static retraining method was evaluated for a simulated space vehicle approach and landing under instrument and visual flight conditions. Experienced pilots were trained and then tested after 4 months without flying to compare their performance using the improved method with three methods previously evaluated. Use of the improved static retraining method resulted in no practical or significant skill degradation and was found to be even more effective than methods using a dynamic presentation of visual cues. The results suggested that properly structured open loop methods of flight control task retraining are feasible.

Control Surface Interaction Effects of the Active Aeroelastic Wing Wind Tunnel Model

NASA Technical Reports Server (NTRS)

Heeg, Jennifer

2006-01-01

This paper presents results from testing the Active Aeroelastic Wing wind tunnel model in NASA Langley s Transonic Dynamics Tunnel. The wind tunnel test provided an opportunity to study aeroelastic system behavior under combined control surface deflections, testing for control surface interaction effects. Control surface interactions were observed in both static control surface actuation testing and dynamic control surface oscillation testing. The primary method of evaluating interactions was examination of the goodness of the linear superposition assumptions. Responses produced by independently actuating single control surfaces were combined and compared with those produced by simultaneously actuating and oscillating multiple control surfaces. Adjustments to the data were required to isolate the control surface influences. Using dynamic data, the task increases, as both the amplitude and phase have to be considered in the data corrections. The goodness of static linear superposition was examined and analysis of variance was used to evaluate significant factors influencing that goodness. The dynamic data showed interaction effects in both the aerodynamic measurements and the structural measurements.

Dynamic Response of a Planetary Gear System Using a Finite Element/Contact Mechanics Model

NASA Technical Reports Server (NTRS)

Parker, Robert G.; Agashe, Vinayak; Vijayakar, Sandeep M.

2000-01-01

The dynamic response of a helicopter planetary gear system is examined over a wide range of operating speeds and torques. The analysis tool is a unique, semianalytical finite element formulation that admits precise representation of the tooth geometry and contact forces that are crucial in gear dynamics. Importantly, no a priori specification of static transmission error excitation or mesh frequency variation is required; the dynamic contact forces are evaluated internally at each time step. The calculated response shows classical resonances when a harmonic of mesh frequency coincides with a natural frequency. However, peculiar behavior occurs where resonances expected to be excited at a given speed are absent. This absence of particular modes is explained by analytical relationships that depend on the planetary configuration and mesh frequency harmonic. The torque sensitivity of the dynamic response is examined and compared to static analyses. Rotation mode response is shown to be more sensitive to input torque than translational mode response.

FASOR - A second generation shell of revolution code

NASA Technical Reports Server (NTRS)

Cohen, G. A.

1978-01-01

An integrated computer program entitled Field Analysis of Shells of Revolution (FASOR) currently under development for NASA is described. When completed, this code will treat prebuckling, buckling, initial postbuckling and vibrations under axisymmetric static loads as well as linear response and bifurcation under asymmetric static loads. Although these modes of response are treated by existing programs, FASOR extends the class of problems treated to include general anisotropy and transverse shear deformations of stiffened laminated shells. At the same time, a primary goal is to develop a program which is free of the usual problems of modeling, numerical convergence and ill-conditioning, laborious problem setup, limitations on problem size and interpretation of output. The field method is briefly described, the shell differential equations are cast in a suitable form for solution by this method and essential aspects of the input format are presented. Numerical results are given for both unstiffened and stiffened anisotropic cylindrical shells and compared with previously published analytical solutions.

Characterization of high-dose and high-energy implanted gate and source diode and analysis of lateral spreading of p gate profile in high voltage SiC static induction transistors

NASA Astrophysics Data System (ADS)

Onose, Hidekatsu; Kobayashi, Yutaka; Onuki, Jin

2017-03-01

The effect of the p gate dose on the characteristics of the gate-source diode in SiC static induction transistors (SIT) was investigated. It was found that a dose of 1.5 × 1014 cm-2 yields a pn junction breakdown voltage higher than 60 V and good forward characteristics. A normally on SiC SIT was fabricated and demonstrated. A blocking voltage higher than 2.0 kV at a gate-source voltage of -50 V and on-resistance of 70 mΩ cm2 were obtained. Device simulations were performed to investigate the effect of the lateral spreading. By comparing the measured I-V curves with simulation results, the lateral spreading factor was estimated to be about 0.5. The lateral spreading detrimentally affected the electrical properties of the SIT made using implantations at energies higher than 1 MeV.

A novel approach to assess temporal sensory perception of muscle foods: application of a time-intensity technique to diverse Iberian meat products.

PubMed

Lorido, Laura; Estévez, Mario; Ventanas, Sonia

2014-01-01

Although dynamic sensory techniques such as time-intensity (TI) have been applied to certain meat products, existing knowledge regarding the temporal sensory perception of muscle foods is still limited. The objective of the present study was to apply TI to the flavour and texture perception of three different Iberian meat products: liver pâté, dry-cured sausages ("salchichon") and dry-cured loin. Moreover, the advantages of using dynamic versus static sensory techniques were explored by subjecting the same products to a quantitative descriptive analysis (QDA). TI was a suitable technique to assess the impact of composition and structure of the three meat products on flavour and texture perception from a dynamic perspective. TI parameters extracted from the TI-curves and related to temporal perception enabled the detection of clear differences in sensory temporal perception between the meat products and provided additional insight on sensory perception compared to the conventional static sensory technique (QDA). © 2013.

Numerical Exposure Assessment Method for Low Frequency Range and Application to Wireless Power Transfer.

PubMed

Park, SangWook; Kim, Minhyuk

2016-01-01

In this paper, a numerical exposure assessment method is presented for a quasi-static analysis by the use of finite-difference time-domain (FDTD) algorithm. The proposed method is composed of scattered field FDTD method and quasi-static approximation for analyzing of the low frequency band electromagnetic problems. The proposed method provides an effective tool to compute induced electric fields in an anatomically realistic human voxel model exposed to an arbitrary non-uniform field source in the low frequency ranges. The method is verified, and excellent agreement with theoretical solutions is found for a dielectric sphere model exposed to a magnetic dipole source. The assessment method serves a practical example of the electric fields, current densities, and specific absorption rates induced in a human head and body in close proximity to a 150-kHz wireless power transfer system for cell phone charging. The results are compared to the limits recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the IEEE standard guidelines.

Analysis of operational limit of an aircraft: An aeroelastic approach

NASA Astrophysics Data System (ADS)

Hasan, Md. Mehedi; Hassan, M. D. Mehedi; Sarrowar, S. M. Bayazid; Faisal, Kh. Md.; Ahmed, Sheikh Reaz, Dr.

2017-06-01

In classical theory of elasticity, external loading acting on the body is independent of deformation of the body. But, in aeroelasticity, aerodynamic forces depend on the attitude of the body relative to the flow. Aircraft's are subjected to a range of static loads resulting from equilibrium or steady flight maneuvers such as coordinated level turn, steady pitch and bank rate, steady and level flight. Interaction of these loads with elastic forces of aircraft structure creates some aeroelastic phenomena. In this paper, we have summarized recent developments in the area of aeroelasticity. A numerical approach has been applied for finding divergence speed, a static aeroelastic phenomena, of a typical aircraft. This paper also involves graphical representations of constraints on load factor and bank angle during different steady flight maneuvers taking flexibility into account and comparing it with the value without flexibility. Effect of wing skin thickness, spar web thickness and position of flexural axis of wing on this divergence speed as well as load factor and bank angle has also been observed using MATLAB.

Numerical Exposure Assessment Method for Low Frequency Range and Application to Wireless Power Transfer

PubMed Central

Kim, Minhyuk

2016-01-01

In this paper, a numerical exposure assessment method is presented for a quasi-static analysis by the use of finite-difference time-domain (FDTD) algorithm. The proposed method is composed of scattered field FDTD method and quasi-static approximation for analyzing of the low frequency band electromagnetic problems. The proposed method provides an effective tool to compute induced electric fields in an anatomically realistic human voxel model exposed to an arbitrary non-uniform field source in the low frequency ranges. The method is verified, and excellent agreement with theoretical solutions is found for a dielectric sphere model exposed to a magnetic dipole source. The assessment method serves a practical example of the electric fields, current densities, and specific absorption rates induced in a human head and body in close proximity to a 150-kHz wireless power transfer system for cell phone charging. The results are compared to the limits recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the IEEE standard guidelines. PMID:27898688

Quasi-Static Calibration Method of a High-g Accelerometer

PubMed Central

Wang, Yan; Fan, Jinbiao; Zu, Jing; Xu, Peng

2017-01-01

To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration. These signals are used to drive the calibrated accelerometer. By comparing the excitation acceleration signal and the output responses of the calibrated accelerometer to the excitation signals, the impact sensitivity of the calibrated accelerometer is obtained. As indicated by the calibration test results, this calibration system produces excitation acceleration signals with a pulse width of less than 1000 μs, and realize the quasi-static calibration of high-g accelerometers with a resonant frequency above 20 kHz when the calibration error was 3%. PMID:28230743

A Static Burst Test for Composite Flywheel Rotors

NASA Astrophysics Data System (ADS)

Hartl, Stefan; Schulz, Alexander; Sima, Harald; Koch, Thomas; Kaltenbacher, Manfred

2016-06-01

High efficient and safe flywheels are an interesting technology for decentralized energy storage. To ensure all safety aspects, a static test method for a controlled initiation of a burst event for composite flywheel rotors is presented with nearly the same stress distribution as in the dynamic case, rotating with maximum speed. In addition to failure prediction using different maximum stress criteria and a safety factor, a set of tensile and compressive tests is carried out to identify the parameters of the used carbon fiber reinforced plastics (CFRP) material. The static finite element (FE) simulation results of the flywheel static burst test (FSBT) compare well to the quasistatic FE-simulation results of the flywheel rotor using inertia loads. Furthermore, it is demonstrated that the presented method is a very good controllable and observable possibility to test a high speed flywheel energy storage system (FESS) rotor in a static way. Thereby, a much more expensive and dangerous dynamic spin up test with possible uncertainties can be substituted.

Static headspace analysis using polyurethane phases--application to roasted coffee volatiles characterization.

PubMed

Rodrigues, C; Portugal, F C M; Nogueira, J M F

2012-01-30

Static headspace sorptive extraction using polyurethane foams (HSSE(PU)) followed by gas chromatography coupled to mass spectrometry is proposed for volatile analysis. The application of this novel analytical approach to characterize the volatiles profile from roasted coffee samples, selected as model system, revealed remarkable advantages under convenient experimental conditions. The comparison of HSSE(PU) with other well-established procedures, such as headspace sorptive extraction using polydimethylsiloxane (HSSE(PDMS)) and headspace solid phase microextraction using carboxen/polydimethylsiloxane fibers (HS-SPME(CAR/PDMS)), showed that the former presented much higher capacity, sensitivity and even selectivity, where larger abundance and number of roasted coffee volatile compounds (e.g. furans, pyrazines, ketones, acids and pyrroles) could be achieved, under similar experimental conditions. The data presented herein proved, for the first time, that PU foams present great performance for static headspace sorption-based procedures, showing to be an alternative polymeric phase for volatile analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

A new rational-based optimal design strategy of ship structure based on multi-level analysis and super-element modeling method

NASA Astrophysics Data System (ADS)

Sun, Li; Wang, Deyu

2011-09-01

A new multi-level analysis method of introducing the super-element modeling method, derived from the multi-level analysis method first proposed by O. F. Hughes, has been proposed in this paper to solve the problem of high time cost in adopting a rational-based optimal design method for ship structural design. Furthermore, the method was verified by its effective application in optimization of the mid-ship section of a container ship. A full 3-D FEM model of a ship, suffering static and quasi-static loads, was used as the analyzing object for evaluating the structural performance of the mid-ship module, including static strength and buckling performance. Research results reveal that this new method could substantially reduce the computational cost of the rational-based optimization problem without decreasing its accuracy, which increases the feasibility and economic efficiency of using a rational-based optimal design method in ship structural design.

Alterations in knee kinematics after partial medial meniscectomy are activity dependent.

PubMed

Edd, Shannon N; Netravali, Nathan A; Favre, Julien; Giori, Nicholas J; Andriacchi, Thomas P

2015-06-01

Alterations in knee kinematics after partial meniscectomy have been linked to the increased risk of osteoarthritis in this population. Understanding differences in kinematics during static versus dynamic activities of increased demand can provide important information regarding the possible underlying mechanisms of these alterations. Differences in the following 2 kinematics measures will increase with activity demand: (1) the offset toward external tibial rotation for the meniscectomized limb compared with the contralateral limb during stance and (2) the difference in knee flexion angle at initial foot contact between the meniscectomized and contralateral limbs. Controlled laboratory study. This study compared side-to-side differences in knee flexion and rotation angles during static and dynamic activities. Thirteen patients (2 female) were tested in a motion capture laboratory at 6 ± 2 months after unilateral, arthroscopic, partial medial meniscectomy during a static reference pose and during 3 dynamic activities: walking, stair ascent, and stair descent. The meniscectomized limb demonstrated more external tibial rotation compared with the contralateral limb during dynamic activities, and there was a trend that this offset increased with activity demand (repeated-measures analysis of variance [ANOVA] for activity, P = .07; mean limb difference: static pose, -0.1° ± 3.3°, P = .5; walking, 1.2° ± 3.8°, P = .1; stair ascent, 2.0° ± 3.2°, P = .02; stair descent, 3.0° ± 3.5°, P = .005). Similarly, the meniscectomized knee was more flexed at initial contact than the contralateral limb during dynamic activities (repeated-measures ANOVA for activity P = .006; mean limb difference: reference pose, 1.0° ± 2.5°, P = .09; walking, 2.0° ± 3.9°, P = .05; stair ascent, 5.9° ± 5.3°, P = .009; stair descent, 3.5° ± 4.0°, P = .004). These results suggest both a structural element and a potential muscular element for the differences in kinematics after partial medial meniscectomy and highlight the importance of challenging the knee with activities of increased demands to detect differences in kinematics from the contralateral limb. With further investigation, these findings could help guide clinical rehabilitation of patients with torn meniscus tissue, especially in the context of the patients' increased risk of joint degeneration. © 2015 The Author(s).

Development of an integrated aeroservoelastic analysis program and correlation with test data

NASA Technical Reports Server (NTRS)

Gupta, K. K.; Brenner, M. J.; Voelker, L. S.

1991-01-01

The details and results are presented of the general-purpose finite element STructural Analysis RoutineS (STARS) to perform a complete linear aeroelastic and aeroservoelastic analysis. The earlier version of the STARS computer program enabled effective finite element modeling as well as static, vibration, buckling, and dynamic response of damped and undamped systems, including those with pre-stressed and spinning structures. Additions to the STARS program include aeroelastic modeling for flutter and divergence solutions, and hybrid control system augmentation for aeroservoelastic analysis. Numerical results of the X-29A aircraft pertaining to vibration, flutter-divergence, and open- and closed-loop aeroservoelastic controls analysis are compared to ground vibration, wind-tunnel, and flight-test results. The open- and closed-loop aeroservoelastic control analyses are based on a hybrid formulation representing the interaction of structural, aerodynamic, and flight-control dynamics.

Validation of a pretreatment delivery quality assurance method for the CyberKnife Synchrony system.

PubMed

Mastella, E; Vigorito, S; Rondi, E; Piperno, G; Ferrari, A; Strata, E; Rozza, D; Jereczek-Fossa, B A; Cattani, F

2016-08-01

To evaluate the geometric and dosimetric accuracies of the CyberKnife Synchrony respiratory tracking system (RTS) and to validate a method for pretreatment patient-specific delivery quality assurance (DQA). An EasyCube phantom was mounted on the ExacTrac gating phantom, which can move along the superior-inferior (SI) axis of a patient to simulate a moving target. The authors compared dynamic and static measurements. For each case, a Gafchromic EBT3 film was positioned between two slabs of the EasyCube, while a PinPoint ionization chamber was placed in the appropriate space. There were three steps to their evaluation: (1) the field size, the penumbra, and the symmetry of six secondary collimators were measured along the two main orthogonal axes. Dynamic measurements with deliberately simulated errors were also taken. (2) The delivered dose distributions (from step 1) were compared with the planned ones, using the gamma analysis method. The local gamma passing rates were evaluated using three acceptance criteria: 3% local dose difference (LDD)/3 mm, 2%LDD/2 mm, and 3%LDD/1 mm. (3) The DQA plans for six clinical patients were irradiated in different dynamic conditions, to give a total of 19 cases. The measured and planned dose distributions were evaluated with the same gamma-index criteria used in step 2 and the measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber. (1) A very slight enlargement of the field size and of the penumbra was observed in the SI direction (on average <1 mm), in line with the overall average CyberKnife system error for tracking treatments. (2) Comparison between the planned and the correctly delivered dose distributions confirmed the dosimetric accuracy of the RTS for simple plans. The multicriteria gamma analysis was able to detect the simulated errors, proving the robustness of their method of analysis. (3) All of the DQA clinical plans passed the tests, both in static and dynamic conditions. No statistically significant differences were found between static and dynamic cases, confirming the high degree of accuracy of the Synchrony RTS. The presented methods and measurements verified the mechanical and dosimetric accuracy of the Synchrony RTS. Their method confirms the fact that the RTS, if used properly, is able to treat a moving target with great precision. By combining PinPoint ion chamber, EBT3 films, and gamma evaluation of dose distributions, their DQA method robustly validated the effectiveness of CyberKnife and Synchrony system.

Digital microarray analysis for digital artifact genomics

NASA Astrophysics Data System (ADS)

Jaenisch, Holger; Handley, James; Williams, Deborah

2013-06-01

We implement a Spatial Voting (SV) based analogy of microarray analysis for digital gene marker identification in malware code sections. We examine a famous set of malware formally analyzed by Mandiant and code named Advanced Persistent Threat (APT1). APT1 is a Chinese organization formed with specific intent to infiltrate and exploit US resources. Manidant provided a detailed behavior and sting analysis report for the 288 malware samples available. We performed an independent analysis using a new alternative to the traditional dynamic analysis and static analysis we call Spatial Analysis (SA). We perform unsupervised SA on the APT1 originating malware code sections and report our findings. We also show the results of SA performed on some members of the families associated by Manidant. We conclude that SV based SA is a practical fast alternative to dynamics analysis and static analysis.

A dynamic analysis of the radiation excitation from the activation of a current collecting system in space

NASA Technical Reports Server (NTRS)

Wang, J.; Hastings, D. E.

1991-01-01

Current collecting systems moving in the ionosphere will induce electromagnetic wave radiation. The commonly used static analysis is incapable of studying the situation when such systems undergo transient processes. A dynamic analysis has been developed, and the radiation excitation processes are studied. This dynamic analysis is applied to study the temporal wave radiation from the activation of current collecting systems in space. The global scale electrodynamic interactions between a space-station-like structure and the ionospheric plasma are studied. The temporal evolution and spatial propagation of the electric wave field after the activation are described. The wave excitations by tethered systems are also studied. The dependencies of the temporal Alfven wave and lower hybrid wave radiation on the activation time and the space system structure are discussed. It is shown that the characteristics of wave radiation are determined by the matching of two sets of characteristic frequencies, and a rapid change in the current collection can give rise to substantial transient radiation interference. The limitations of the static and linear analysis are examined, and the condition under which the static assumption is valid is obtained.

Wind Tunnel Testing of Various Disk-Gap-Band Parachutes

NASA Technical Reports Server (NTRS)

Cruz, Juan R.; Mineck, Raymond E.; Keller, Donald F.; Bobskill, Maria V.

2003-01-01

Two Disk-Gap-Band model parachute designs were tested in the NASA Langley Transonic Dynamics Tunnel. The purposes of these tests were to determine the drag and static stability coefficients of these two model parachutes at various subsonic Mach numbers in support of the Mars Exploration Rover mission. The two model parachute designs were designated 1.6 Viking and MPF. These model parachute designs were chosen to investigate the tradeoff between drag and static stability. Each of the parachute designs was tested with models fabricated from MIL-C-7020 Type III or F-111 fabric. The reason for testing model parachutes fabricated with different fabrics was to evaluate the effect of fabric permeability on the drag and static stability coefficients. Several improvements over the Viking-era wind tunnel tests were implemented in the testing procedures and data analyses. Among these improvements were corrections for test fixture drag interference and blockage effects, and use of an improved test fixture for measuring static stability coefficients. The 1.6 Viking model parachutes had drag coefficients from 0.440 to 0.539, while the MPF model parachutes had drag coefficients from 0.363 to 0.428. The 1.6 Viking model parachutes had drag coefficients 18 to 22 percent higher than the MPF model parachute for equivalent fabric materials and test conditions. Model parachutes of the same design tested at the same conditions had drag coefficients approximately 11 to 15 percent higher when manufactured from F-111 fabric as compared to those fabricated from MIL-C-7020 Type III fabric. The lower fabric permeability of the F-111 fabric was the source of this difference. The MPF model parachutes had smaller absolute statically stable trim angles of attack as compared to the 1.6 Viking model parachutes for equivalent fabric materials and test conditions. This was attributed to the MPF model parachutes larger band height to nominal diameter ratio. For both designs, model parachutes fabricated from F-111 fabric had significantly greater statically stable absolute trim angles of attack at equivalent test conditions as compared to those fabricated from MILC-7020 Type III fabric. This reduction in static stability exhibited by model parachutes fabricated from F-111 fabric was attributed to the lower permeability of the F-111 fabric. The drag and static stability coefficient results were interpolated to obtain their values at Mars flight conditions using total porosity as the interpolating parameter.

Augmenting Traditional Static Analysis With Commonly Available Metadata

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

Cook, Devin

Developers and security analysts have been using static analysis for a long time to analyze programs for defects and vulnerabilities with some success. Generally a static analysis tool is run on the source code for a given program, flagging areas of code that need to be further inspected by a human analyst. These areas may be obvious bugs like potential bu er over flows, information leakage flaws, or the use of uninitialized variables. These tools tend to work fairly well - every year they find many important bugs. These tools are more impressive considering the fact that they only examinemore » the source code, which may be very complex. Now consider the amount of data available that these tools do not analyze. There are many pieces of information that would prove invaluable for finding bugs in code, things such as a history of bug reports, a history of all changes to the code, information about committers, etc. By leveraging all this additional data, it is possible to nd more bugs with less user interaction, as well as track useful metrics such as number and type of defects injected by committer. This dissertation provides a method for leveraging development metadata to find bugs that would otherwise be difficult to find using standard static analysis tools. We showcase two case studies that demonstrate the ability to find 0day vulnerabilities in large and small software projects by finding new vulnerabilities in the cpython and Roundup open source projects.« less

The Effects of Comprehensive Warm-Up Programs on Proprioception, Static and Dynamic Balance on Male Soccer Players

PubMed Central

Daneshjoo, Abdolhamid; Mokhtar, Abdul Halim; Rahnama, Nader; Yusof, Ashril

2012-01-01

Purpose The study investigated the effects of FIFA 11+ and HarmoKnee, both being popular warm-up programs, on proprioception, and on the static and dynamic balance of professional male soccer players. Methods Under 21 year-old soccer players (n = 36) were divided randomly into 11+, HarmoKnee and control groups. The programs were performed for 2 months (24 sessions). Proprioception was measured bilaterally at 30°, 45° and 60° knee flexion using the Biodex Isokinetic Dynamometer. Static and dynamic balances were evaluated using the stork stand test and Star Excursion Balance Test (SEBT), respectively. Results The proprioception error of dominant leg significantly decreased from pre- to post-test by 2.8% and 1.7% in the 11+ group at 45° and 60° knee flexion, compared to 3% and 2.1% in the HarmoKnee group. The largest joint positioning error was in the non-dominant leg at 30° knee flexion (mean error value = 5.047), (p<0.05). The static balance with the eyes opened increased in the 11+ by 10.9% and in the HarmoKnee by 6.1% (p<0.05). The static balance with eyes closed significantly increased in the 11+ by 12.4% and in the HarmoKnee by 17.6%. The results indicated that static balance was significantly higher in eyes opened compared to eyes closed (p = 0.000). Significant improvements in SEBT in the 11+ (12.4%) and HarmoKnee (17.6%) groups were also found. Conclusion Both the 11+ and HarmoKnee programs were proven to be useful warm-up protocols in improving proprioception at 45° and 60° knee flexion as well as static and dynamic balance in professional male soccer players. Data from this research may be helpful in encouraging coaches or trainers to implement the two warm-up programs in their soccer teams. PMID:23251579

Dynamic augmentation restores anterior tibial translation in ACL suture repair: a biomechanical comparison of non-, static and dynamic augmentation techniques.

PubMed

Hoogeslag, Roy A G; Brouwer, Reinoud W; Huis In 't Veld, Rianne; Stephen, Joanna M; Amis, Andrew A

2018-02-03

There is a lack of objective evidence investigating how previous non-augmented ACL suture repair techniques and contemporary augmentation techniques in ACL suture repair restrain anterior tibial translation (ATT) across the arc of flexion, and after cyclic loading of the knee. The purpose of this work was to test the null hypotheses that there would be no statistically significant difference in ATT after non-, static- and dynamic-augmented ACL suture repair, and they will not restore ATT to normal values across the arc of flexion of the knee after cyclic loading. Eleven human cadaveric knees were mounted in a test rig, and knee kinematics from 0° to 90° of flexion were recorded by use of an optical tracking system. Measurements were recorded without load and with 89-N tibial anterior force. The knees were tested in the following states: ACL-intact, ACL-deficient, non-augmented suture repair, static tape augmentation and dynamic augmentation after 10 and 300 loading cycles. Only static tape augmentation and dynamic augmentation restored ATT to values similar to the ACL-intact state directly postoperation, and maintained this after cyclic loading. However, contrary to dynamic augmentation, the ATT after static tape augmentation failed to remain statistically less than for the ACL-deficient state after cyclic loading. Moreover, after cyclic loading, ATT was significantly less with dynamic augmentation when compared to static tape augmentation. In contrast to non-augmented ACL suture repair and static tape augmentation, only dynamic augmentation resulted in restoration of ATT values similar to the ACL-intact knee and decreased ATT values when compared to the ACL-deficient knee immediately post-operation and also after cyclic loading, across the arc of flexion, thus allowing the null hypotheses to be rejected. This may assist healing of the ruptured ACL. Therefore, this study would support further clinical evaluation of dynamic augmentation of ACL repair.

Stress Analysis of Columns and Beam Columns by the Photoelastic Method

NASA Technical Reports Server (NTRS)

Ruffner, B F

1946-01-01

Principles of similarity and other factors in the design of models for photoelastic testing are discussed. Some approximate theoretical equations, useful in the analysis of results obtained from photoelastic tests are derived. Examples of the use of photoelastic techniques and the analysis of results as applied to uniform and tapered beam columns, circular rings, and statically indeterminate frames, are given. It is concluded that this method is an effective tool for the analysis of structures in which column action is present, particularly in tapered beam columns, and in statically indeterminate structures in which the distribution of loads in the structures is influenced by bending moments due to axial loads in one or more members.

An eight-legged tactile sensor to estimate coefficient of static friction.

PubMed

Wei Chen; Rodpongpun, Sura; Luo, William; Isaacson, Nathan; Kark, Lauren; Khamis, Heba; Redmond, Stephen J

2015-08-01

It is well known that a tangential force larger than the maximum static friction force is required to initiate the sliding motion between two objects, which is governed by a material constant called the coefficient of static friction. Therefore, knowing the coefficient of static friction is of great importance for robot grippers which wish to maintain a stable and precise grip on an object during various manipulation tasks. Importantly, it is most useful if grippers can estimate the coefficient of static friction without having to explicitly explore the object first, such as lifting the object and reducing the grip force until it slips. A novel eight-legged sensor, based on simplified theoretical principles of friction is presented here to estimate the coefficient of static friction between a planar surface and the prototype sensor. Each of the sensor's eight legs are straight and rigid, and oriented at a specified angle with respect to the vertical, allowing it to estimate one of five ranges (5 = 8/2 + 1) that the coefficient of static friction can occupy. The coefficient of friction can be estimated by determining whether the legs have slipped or not when pressed against a surface. The coefficients of static friction between the sensor and five different materials were estimated and compared to a measurement from traditional methods. A least-squares linear fit of the sensor estimated coefficient showed good correlation with the reference coefficient with a gradient close to one and an r(2) value greater than 0.9.

Low dose dynamic myocardial CT perfusion using advanced iterative reconstruction

NASA Astrophysics Data System (ADS)

Eck, Brendan L.; Fahmi, Rachid; Fuqua, Christopher; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

2015-03-01

Dynamic myocardial CT perfusion (CTP) can provide quantitative functional information for the assessment of coronary artery disease. However, x-ray dose in dynamic CTP is high, typically from 10mSv to >20mSv. We compared the dose reduction potential of advanced iterative reconstruction, Iterative Model Reconstruction (IMR, Philips Healthcare, Cleveland, Ohio) to hybrid iterative reconstruction (iDose4) and filtered back projection (FBP). Dynamic CTP scans were obtained using a porcine model with balloon-induced ischemia in the left anterior descending coronary artery to prescribed fractional flow reserve values. High dose dynamic CTP scans were acquired at 100kVp/100mAs with effective dose of 23mSv. Low dose scans at 75mAs, 50mAs, and 25mAs were simulated by adding x-ray quantum noise and detector electronic noise to the projection space data. Images were reconstructed with FBP, iDose4, and IMR at each dose level. Image quality in static CTP images was assessed by SNR and CNR. Blood flow was obtained using a dynamic CTP analysis pipeline and blood flow image quality was assessed using flow-SNR and flow-CNR. IMR showed highest static image quality according to SNR and CNR. Blood flow in FBP was increasingly over-estimated at reduced dose. Flow was more consistent for iDose4 from 100mAs to 50mAs, but was over-estimated at 25mAs. IMR was most consistent from 100mAs to 25mAs. Static images and flow maps for 100mAs FBP, 50mAs iDose4, and 25mAs IMR showed comparable, clear ischemia, CNR, and flow-CNR values. These results suggest that IMR can enable dynamic CTP at significantly reduced dose, at 5.8mSv or 25% of the comparable 23mSv FBP protocol.

The role of ensemble-based statistics in variational assimilation of cloud-affected observations from infrared imagers

NASA Astrophysics Data System (ADS)

Hacker, Joshua; Vandenberghe, Francois; Jung, Byoung-Jo; Snyder, Chris

2017-04-01

Effective assimilation of cloud-affected radiance observations from space-borne imagers, with the aim of improving cloud analysis and forecasting, has proven to be difficult. Large observation biases, nonlinear observation operators, and non-Gaussian innovation statistics present many challenges. Ensemble-variational data assimilation (EnVar) systems offer the benefits of flow-dependent background error statistics from an ensemble, and the ability of variational minimization to handle nonlinearity. The specific benefits of ensemble statistics, relative to static background errors more commonly used in variational systems, have not been quantified for the problem of assimilating cloudy radiances. A simple experiment framework is constructed with a regional NWP model and operational variational data assimilation system, to provide the basis understanding the importance of ensemble statistics in cloudy radiance assimilation. Restricting the observations to those corresponding to clouds in the background forecast leads to innovations that are more Gaussian. The number of large innovations is reduced compared to the more general case of all observations, but not eliminated. The Huber norm is investigated to handle the fat tails of the distributions, and allow more observations to be assimilated without the need for strict background checks that eliminate them. Comparing assimilation using only ensemble background error statistics with assimilation using only static background error statistics elucidates the importance of the ensemble statistics. Although the cost functions in both experiments converge to similar values after sufficient outer-loop iterations, the resulting cloud water, ice, and snow content are greater in the ensemble-based analysis. The subsequent forecasts from the ensemble-based analysis also retain more condensed water species, indicating that the local environment is more supportive of clouds. In this presentation we provide details that explain the apparent benefit from using ensembles for cloudy radiance assimilation in an EnVar context.

Whole body vibration training--improving balance control and muscle endurance.

PubMed

Ritzmann, Ramona; Kramer, Andreas; Bernhardt, Sascha; Gollhofer, Albert

2014-01-01

Exercise combined with whole body vibration (WBV) is becoming increasingly popular, although additional effects of WBV in comparison to conventional exercises are still discussed controversially in literature. Heterogeneous findings are attributed to large differences in the training designs between WBV and "control" groups in regard to training volume, load and type. In order to separate the additional effects of WBV from the overall adaptations due to the intervention, in this study, a four-week WBV training setup was compared to a matched intervention program with identical training parameters in both training settings except for the exposure to WBV. In a repeated-measures matched-subject design, 38 participants were assigned to either the WBV group (VIB) or the equivalent training group (CON). Training duration, number of sets, rest periods and task-specific instructions were matched between the groups. Balance, jump height and local static muscle endurance were assessed before and after the training period. The statistical analysis revealed significant interaction effects of group×time for balance and local static muscle endurance (p<0.05). Hence, WBV caused an additional effect on balance control (pre vs. post VIB +13%, p<0.05 and CON +6%, p = 0.33) and local static muscle endurance (pre vs. post VIB +36%, p<0.05 and CON +11%, p = 0.49). The effect on jump height remained insignificant (pre vs. post VIB +3%, p = 0.25 and CON ±0%, p = 0.82). This study provides evidence for the additional effects of WBV above conventional exercise alone. As far as balance and muscle endurance of the lower leg are concerned, a training program that includes WBV can provide supplementary benefits in young and well-trained adults compared to an equivalent program that does not include WBV.

A novel axial-stress bioreactor system combined with a substance exchanger for tissue engineering of 3D constructs.

PubMed

Li, Song-Tao; Liu, Yong; Zhou, Qiang; Lue, Ren-Fa; Song, Lei; Dong, Shi-Wu; Guo, Ping; Kopjar, Branko

2014-03-01

This study introduced a prototype of an axial-stress bioreactor system that supports long-term growth and development of engineered tissues. The main features of this bioreactor are an integrated substance exchanger and feedback control of pH and PO₂. A 21-day study was conducted to validate the system's ability to maintain a stable environment, while remaining sterile. Our results showed that the pH, PO₂, and nutrient (glucose) remained balanced at appropriate levels, while metabolic waste (lactic acid) was removed. No bacteria or fungi were detected in the system or tissue; thus, demonstrating that it was sterile. These data indicate the bioreactor's strong potential for long-term tissue culture. To explore this idea, the effect of dynamic culture, including cyclic compression and automatic substance exchange, on mouse bone-marrow mesenchymal stem cells (BMSCs) seeded in decalcified bone matrix was studied using the bioreactor prototype. Histological sections of the engineered tissues showed higher cell densities in scaffolds in dynamic culture compared to those in static culture, while cell cycle analysis showed that dynamic culture promoted BMSC proliferation (proliferation index, PI=34.02±1.77) more effectively than static culture (PI=26.66±1.81). The results from a methyl thiazolyl tetrazolium assay were consistent with the loading experimental data. Furthermore, elevated alkaline phosphatase activity and calcium content were observed in dynamic condition compared to static culture. In conclusion, this bioreactor system supplies a method of modulating the pH and PO₂ in defined ranges with only small fluctuations; it can be used as a physiological or pathological analog. Automatic control of the environment is a practical solution for long-term, steady-state culture for future commercialization.

Repair of Segmental Bone Defect Using Totally Vitalized Tissue Engineered Bone Graft by a Combined Perfusion Seeding and Culture System

PubMed Central

Feng, Ya-Fei; Li, Xiang; Hu, Yun-Yu; Wang, Zhen; Ma, Zhen-Sheng; Lei, Wei

2014-01-01

Background The basic strategy to construct tissue engineered bone graft (TEBG) is to combine osteoblastic cells with three dimensional (3D) scaffold. Based on this strategy, we proposed the “Totally Vitalized TEBG” (TV-TEBG) which was characterized by abundant and homogenously distributed cells with enhanced cell proliferation and differentiation and further investigated its biological performance in repairing segmental bone defect. Methods In this study, we constructed the TV-TEBG with the combination of customized flow perfusion seeding/culture system and β-tricalcium phosphate (β-TCP) scaffold fabricated by Rapid Prototyping (RP) technique. We systemically compared three kinds of TEBG constructed by perfusion seeding and perfusion culture (PSPC) method, static seeding and perfusion culture (SSPC) method, and static seeding and static culture (SSSC) method for their in vitro performance and bone defect healing efficacy with a rabbit model. Results Our study has demonstrated that TEBG constructed by PSPC method exhibited better biological properties with higher daily D-glucose consumption, increased cell proliferation and differentiation, and better cell distribution, indicating the successful construction of TV-TEBG. After implanted into rabbit radius defects for 12 weeks, PSPC group exerted higher X-ray score close to autograft, much greater mechanical property evidenced by the biomechanical testing and significantly higher new bone formation as shown by histological analysis compared with the other two groups, and eventually obtained favorable healing efficacy of the segmental bone defect that was the closest to autograft transplantation. Conclusion This study demonstrated the feasibility of TV-TEBG construction with combination of perfusion seeding, perfusion culture and RP technique which exerted excellent biological properties. The application of TV-TEBG may become a preferred candidate for segmental bone defect repair in orthopedic and maxillofacial fields. PMID:24728277

Impact of machine perfusion after long static cold storage on delayed graft function incidence and duration and time to hospital discharge.

PubMed

Matos, Ana Cristina C; Requiao Moura, Lúcio Roberto; Borrelli, Milton; Nogueira, Mario; Clarizia, Gabriela; Ongaro, Paula; Durão, Marcelino Souza; Pacheco-Silva, Alvaro

2018-01-01

Delayed graft function (DGF) is very high in our center (70%-80%), and we usually receive a kidney for transplant after more than 22 hours of static cold ischemia time (CIT). Also, there is an inadequate care of the donors, contributing to a high rate of DGF. We decided to test whether machine perfusion (MP) after a CIT improved the outcome of our transplant patients. We analyzed the incidence of DGF, its duration, and the length of hospital stay (LOS) in patients who received a kidney preserved with MP after a CIT (hybrid perfusion-HP). We included 54 deceased donors kidneys preserved with HP transplanted from Feb/13 to Jul/14, and compared them to 101 kidney transplants preserved by static cold storage (CS) from Nov/08 to May/12. The median pumping time was 11 hours. DGF incidence was 61.1% vs 79.2% (P = .02), median DGF duration was 5 vs 11 days (P < .001), and median LOS was 13 vs 18 days (P < .011), for the HP compared to CS group. The observed reduction of DGF with machine perfusion did not occur in donors over 50 years old. In the multivariate analysis, risk factors for DGF, adjusted for CIT, were donor age (OR, 1.04; P = .005) and the absence of use of MP (OR, 1.54; P = .051). In conclusion, the use of HP contributed to faster recovery of renal function and to a shorter length of hospital stay. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Reliability and concurrent validity of the Microsoft Xbox One Kinect for assessment of standing balance and postural control.

PubMed

Clark, Ross A; Pua, Yong-Hao; Oliveira, Cristino C; Bower, Kelly J; Thilarajah, Shamala; McGaw, Rebekah; Hasanki, Ksaniel; Mentiplay, Benjamin F

2015-07-01

The Microsoft Kinect V2 for Windows, also known as the Xbox One Kinect, includes new and potentially far improved depth and image sensors which may increase its accuracy for assessing postural control and balance. The aim of this study was to assess the concurrent validity and reliability of kinematic data recorded using a marker-based three dimensional motion analysis (3DMA) system and the Kinect V2 during a variety of static and dynamic balance assessments. Thirty healthy adults performed two sessions, separated by one week, consisting of static standing balance tests under different visual (eyes open vs. closed) and supportive (single limb vs. double limb) conditions, and dynamic balance tests consisting of forward and lateral reach and an assessment of limits of stability. Marker coordinate and joint angle data were concurrently recorded using the Kinect V2 skeletal tracking algorithm and the 3DMA system. Task-specific outcome measures from each system on Day 1 and 2 were compared. Concurrent validity of trunk angle data during the dynamic tasks and anterior-posterior range and path length in the static balance tasks was excellent (Pearson's r>0.75). In contrast, concurrent validity for medial-lateral range and path length was poor to modest for all trials except single leg eyes closed balance. Within device test-retest reliability was variable; however, the results were generally comparable between devices. In conclusion, the Kinect V2 has the potential to be used as a reliable and valid tool for the assessment of some aspects of balance performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Whole Body Vibration Training - Improving Balance Control and Muscle Endurance

PubMed Central

Ritzmann, Ramona; Kramer, Andreas; Bernhardt, Sascha; Gollhofer, Albert

2014-01-01

Exercise combined with whole body vibration (WBV) is becoming increasingly popular, although additional effects of WBV in comparison to conventional exercises are still discussed controversially in literature. Heterogeneous findings are attributed to large differences in the training designs between WBV and “control” groups in regard to training volume, load and type. In order to separate the additional effects of WBV from the overall adaptations due to the intervention, in this study, a four-week WBV training setup was compared to a matched intervention program with identical training parameters in both training settings except for the exposure to WBV. In a repeated-measures matched-subject design, 38 participants were assigned to either the WBV group (VIB) or the equivalent training group (CON). Training duration, number of sets, rest periods and task-specific instructions were matched between the groups. Balance, jump height and local static muscle endurance were assessed before and after the training period. The statistical analysis revealed significant interaction effects of group×time for balance and local static muscle endurance (p<0.05). Hence, WBV caused an additional effect on balance control (pre vs. post VIB +13%, p<0.05 and CON +6%, p = 0.33) and local static muscle endurance (pre vs. post VIB +36%, p<0.05 and CON +11%, p = 0.49). The effect on jump height remained insignificant (pre vs. post VIB +3%, p = 0.25 and CON ±0%, p = 0.82). This study provides evidence for the additional effects of WBV above conventional exercise alone. As far as balance and muscle endurance of the lower leg are concerned, a training program that includes WBV can provide supplementary benefits in young and well-trained adults compared to an equivalent program that does not include WBV. PMID:24587114

Viscoelastic characterization of soft biological materials

NASA Astrophysics Data System (ADS)

Nayar, Vinod Timothy

Progressive and irreversible retinal diseases are among the primary causes of blindness in the United States, attacking the cells in the eye that transform environmental light into neural signals for the optic pathway. Medical implants designed to restore visual function to afflicted patients can cause mechanical stress and ultimately damage to the host tissues. Research shows that an accurate understanding of the mechanical properties of the biological tissues can reduce damage and lead to designs with improved safety and efficacy. Prior studies on the mechanical properties of biological tissues show characterization of these materials can be affected by environmental, length-scale, time, mounting, stiffness, size, viscoelastic, and methodological conditions. Using porcine sclera tissue, the effects of environmental, time, and mounting conditions are evaluated when using nanoindentation. Quasi-static tests are used to measure reduced modulus during extended exposure to phosphate-buffered saline (PBS), as well as the chemical and mechanical analysis of mounting the sample to a solid substrate using cyanoacrylate. The less destructive nature of nanoindentation tests allows for variance of tests within a single sample to be compared to the variance between samples. The results indicate that the environmental, time, and mounting conditions can be controlled for using modified nanoindentation procedures for biological samples and are in line with averages modulus values from previous studies but with increased precision. By using the quasi-static and dynamic characterization capabilities of the nanoindentation setup, the additional stiffness and viscoelastic variables are measured. Different quasi-static control methods were evaluated along with maximum load parameters and produced no significant difference in reported reduced modulus values. Dynamic characterization tests varied frequency and quasi-static load, showing that the agar could be modeled as a linearly elastic material. The effects of sample stiffness were evaluated by testing both the quasi-static and dynamic mechanical properties of different concentration agar samples, ranging from 0.5% to 5.0%. The dynamic nanoindentation protocol showed some sensitivity to sample stiffness, but characterization remained consistently applicable to soft biological materials. Comparative experiments were performed on both 0.5% and 5.0% agar as well as porcine eye tissue samples using published dynamic macrocompression standards. By comparing these new tests to those obtained with nanoindentation, the effects due to length-scale, stiffness, size, viscoelastic, and methodological conditions are evaluated. Both testing methodologies can be adapted for the environmental and mounting conditions, but the limitations of standardized macro-scale tests are explored. The factors affecting mechanical characterization of soft and thin viscoelastic biological materials are researched and a comprehensive protocol is presented. This work produces material mechanical properties for use in improving future medical implant designs on a wide variety of biological tissue and materials.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak P.; Gump, Jared C.

2006-07-01

Explosive formulations with reduced-sensitivity RDX showed reduced shock sensitivity using Naval Ordnance Laboratory (NOL) Large Scale Gap Test, compared with similar formulations using standard RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light on the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. I-RDX®, a form of reduced- sensitivity RDX was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transform IR (FTIR). The pressure dependence of the Raman mode frequencies of I-RDX® was determined and compared with that of standard RDX. The behavior of I-RDX® near the pressure at which standard RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph is presented.

Prediction of flyover jet noise spectra from static tests

NASA Astrophysics Data System (ADS)

Michel, U.; Michalke, A.

A scaling law for predicting the overall flyover noise of a single stream shock-free circular jet from static experiments is outlined. It is valid for isothermal and hot jets. It assumes that the jet flow and turbulence field are axially stretched in flight. Effects of the boundary layer within the nozzle and along the engine nacelle are neglected. The scaling laws for the power spectral density and spectra with constant relative bandwidth can be derived. In order to compare static and inflight directivities, the far field point relative to the source position must be denoted by the emission angle and the wave normal distance. From the solution of the convective Lighthill equation in a coordinate system fixed to the jet nozzle (wind tunnel case), the power spectral density of sound pressure at a given frequency is found. Predictions for Aerotrain compare well with measured values.

Evidence for impairments in using static line drawings of eye gaze cues to orient visual-spatial attention in children with high functioning autism.

PubMed

Goldberg, Melissa C; Mostow, Allison J; Vecera, Shaun P; Larson, Jennifer C Gidley; Mostofsky, Stewart H; Mahone, E Mark; Denckla, Martha B

2008-09-01

We examined the ability to use static line drawings of eye gaze cues to orient visual-spatial attention in children with high functioning autism (HFA) compared to typically developing children (TD). The task was organized such that on valid trials, gaze cues were directed toward the same spatial location as the appearance of an upcoming target, while on invalid trials gaze cues were directed to an opposite location. Unlike TD children, children with HFA showed no advantage in reaction time (RT) on valid trials compared to invalid trials (i.e., no significant validity effect). The two stimulus onset asynchronies (200 ms, 700 ms) did not differentially affect these findings. The results suggest that children with HFA show impairments in utilizing static line drawings of gaze cues to orient visual-spatial attention.

A reconsideration for forming mechanism of optic fiber probe fabricated by static chemical etching

NASA Astrophysics Data System (ADS)

Chen, Yiru; Shen, Ruiqi

2016-07-01

The studies on the mechanism of static chemical etching are supplemented in this paper. Surface tension and diffusion effect are both taken into account. Theoretical analysis and data fitting show that the slant angle of the liquid-liquid interface leads to the maximum liquid rising, when diffusion effect is negligible.

Joint production and substitution in timber supply: a panel data analysis

Treesearch

Torjus F Bolkesjo; Joseph Buongiorno; Birger Solberg

2010-01-01

Supply equations for sawlog and pulpwood were developed with a panel of data from 102 Norwegian municipalities, observed from 1980 to 2000. Static and dynamic models were estimated by cross-section, time-series andpanel data methods. A static model estimated by first differencing gavethe best overall results in terms of theoretical expectations, pattern ofresiduals,...

Headspace needle-trap analysis of priority volatile organic compounds from aqueous samples: application to the analysis of natural and waste waters.

PubMed

Alonso, Monica; Cerdan, Laura; Godayol, Anna; Anticó, Enriqueta; Sanchez, Juan M

2011-11-11

Combining headspace (HS) sampling with a needle-trap device (NTD) to determine priority volatile organic compounds (VOCs) in water samples results in improved sensitivity and efficiency when compared to conventional static HS sampling. A 22 gauge stainless steel, 51-mm needle packed with Tenax TA and Carboxen 1000 particles is used as the NTD. Three different HS-NTD sampling methodologies are evaluated and all give limits of detection for the target VOCs in the ng L⁻¹ range. Active (purge-and-trap) HS-NTD sampling is found to give the best sensitivity but requires exhaustive control of the sampling conditions. The use of the NTD to collect the headspace gas sample results in a combined adsorption/desorption mechanism. The testing of different temperatures for the HS thermostating reveals a greater desorption effect when the sample is allowed to diffuse, whether passively or actively, through the sorbent particles. The limits of detection obtained in the simplest sampling methodology, static HS-NTD (5 mL aqueous sample in 20 mL HS vials, thermostating at 50 °C for 30 min with agitation), are sufficiently low as to permit its application to the analysis of 18 priority VOCs in natural and waste waters. In all cases compounds were detected below regulated levels. Copyright © 2011 Elsevier B.V. All rights reserved.

The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis.

PubMed

Ouanes, Jean-Pierre P; Bicket, Mark C; Togioka, Brandon; Tomas, Vicente Garcia; Wu, Christopher L; Murphy, Jamie D

2015-03-01

To determine if preoperative gum chewing affects gastric pH and gastric fluid volume. Systematic review and meta-analysis. Data sources included Cochrane, PubMed, and EMBASE databases from inception to June 2012 and reference lists of known relevant articles without language restriction. Randomized controlled trials in which a treatment group that chewed gum was compared to a control group that fasted were included. Relevant data, including main outcomes of gastric fluid volume and gastric pH, were extracted. Four studies involving 287 patients were included. The presence of chewing gum was associated with small but statically significant increases in gastric fluid volume (mean difference = 0.21 mL/kg; 95% confidence interval, 0.02-0.39; P = .03) but not in gastric pH (mean difference = 0.11 mL/kg; 95% confidence interval, -0.14 to 0.36; P = .38). Gastric fluid volume and gastric pH remained unchanged in subgroup analysis by either sugar or sugarless gum type. Chewing gum in the perioperative period causes small but statically significant increases in gastric fluid volume and no change in gastric pH. The increase in gastric fluid most likely is of no clinical significance in terms of aspiration risk for the patient. Elective surgery should not necessarily be canceled or delayed in healthy patients who accidentally chew gum preoperatively. Copyright © 2014 Elsevier Inc. All rights reserved.

Kernel Density Estimation as a Measure of Environmental Exposure Related to Insulin Resistance in Breast Cancer Survivors.

PubMed

Jankowska, Marta M; Natarajan, Loki; Godbole, Suneeta; Meseck, Kristin; Sears, Dorothy D; Patterson, Ruth E; Kerr, Jacqueline

2017-07-01

Background: Environmental factors may influence breast cancer; however, most studies have measured environmental exposure in neighborhoods around home residences (static exposure). We hypothesize that tracking environmental exposures over time and space (dynamic exposure) is key to assessing total exposure. This study compares breast cancer survivors' exposure to walkable and recreation-promoting environments using dynamic Global Positioning System (GPS) and static home-based measures of exposure in relation to insulin resistance. Methods: GPS data from 249 breast cancer survivors living in San Diego County were collected for one week along with fasting blood draw. Exposure to recreation spaces and walkability was measured for each woman's home address within an 800 m buffer (static), and using a kernel density weight of GPS tracks (dynamic). Participants' exposure estimates were related to insulin resistance (using the homeostatic model assessment of insulin resistance, HOMA-IR) controlled by age and body mass index (BMI) in linear regression models. Results: The dynamic measurement method resulted in greater variability in built environment exposure values than did the static method. Regression results showed no association between HOMA-IR and home-based, static measures of walkability and recreation area exposure. GPS-based dynamic measures of both walkability and recreation area were significantly associated with lower HOMA-IR ( P < 0.05). Conclusions: Dynamic exposure measurements may provide important evidence for community- and individual-level interventions that can address cancer risk inequities arising from environments wherein breast cancer survivors live and engage. Impact: This is the first study to compare associations of dynamic versus static built environment exposure measures with insulin outcomes in breast cancer survivors. Cancer Epidemiol Biomarkers Prev; 26(7); 1078-84. ©2017 AACR . ©2017 American Association for Cancer Research.

Remote histology learning from static versus dynamic microscopic images.

PubMed

Mione, Sylvia; Valcke, Martin; Cornelissen, Maria

2016-05-06

Histology is the study of microscopic structures in normal tissue sections. Curriculum redesign in medicine has led to a decrease in the use of optical microscopes during practical classes. Other imaging solutions have been implemented to facilitate remote learning. With advancements in imaging technologies, learning material can now be digitized. Digitized microscopy images can be presented in either a static or dynamic format. This study of remote histology education identifies whether dynamic pictures are superior to static images for the acquisition of histological knowledge. Test results of two cohorts of second-year Bachelor in Medicine students at Ghent University were analyzed in two consecutive academic years: Cohort 1 (n = 190) and Cohort 2 (n = 174). Students in Cohort 1 worked with static images whereas students in Cohort 2 were presented with dynamic images. ANCOVA was applied to study differences in microscopy performance scores between the two cohorts, taking into account any possible initial differences in prior knowledge. The results show that practical histology scores are significantly higher with dynamic images as compared to static images (F (1,361) = 15.14, P < 0.01), regardless of student's gender and performance level. Several reasons for this finding can be explained in accordance with cognitivist learning theory. Since the findings suggest that knowledge construction with dynamic pictures is stronger as compared to static images, dynamic images should be introduced in a remote setting for microscopy education. Further implementation within a larger electronic learning management system needs to be explored in future research. Anat Sci Educ 9: 222-230. © 2015 American Association of Anatomists. © 2015 American Association of Anatomists.