Results from Numerical General Relativity
Baker, John G.
2011-01-01
For several years numerical simulations have been revealing the details of general relativity's predictions for the dynamical interactions of merging black holes. I will review what has been learned of the rich phenomenology of these mergers and the resulting gravitational wave signatures. These wave forms provide a potentially observable record of the powerful astronomical events, a central target of gravitational wave astronomy. Asymmetric radiation can produce a thrust on the system which may accelerate the single black hole resulting from the merger to high relative velocity.
Numerical Model based Reliability Estimation of Selective Laser Melting Process
Mohanty, Sankhya; Hattel, Jesper Henri
2014-01-01
Selective laser melting is developing into a standard manufacturing technology with applications in various sectors. However, the process is still far from being at par with conventional processes such as welding and casting, the primary reason of which is the unreliability of the process. While...... of the selective laser melting process. A validated 3D finite-volume alternating-direction-implicit numerical technique is used to model the selective laser melting process, and is calibrated against results from single track formation experiments. Correlation coefficients are determined for process input...... parameters such as laser power, speed, beam profile, etc. Subsequently, uncertainties in the processing parameters are utilized to predict a range for the various outputs, using a Monte Carlo method based uncertainty analysis methodology, and the reliability of the process is established....
1983-09-01
Industry Australian Atomic Energy Commission, Director CSIROj Materials Science Division, Library Trans-Australia Airlines, Library Qantas Airways ...designed to evaluate the reliability functions that result from the application of reliability analysis to the fatigue of aircraft structures, in particular...Messages 60+ A.4. Program Assembly 608 DISTRIBUTION DOCUMENT CONTROL DATA II 1. INTRODUCTION The application of reliability analysis to the fatigue
A Numerical Simulation Approach for Reliability Evaluation of CFRP Composite
Liu, D. S.-C.; Jenab, K.
2013-02-01
Due to the superior mechanical properties of carbon fiber reinforced plastic (CFRP) materials, they are vastly used in industries such as aircraft manufacturers. The aircraft manufacturers are switching metal to composite structures while studying reliability (R-value) of CFRP. In this study, a numerical simulation method to determine the reliability of Multiaxial Warp Knitted (MWK) textiles used to make CFRP composites is proposed. This method analyzes the distribution of carbon fiber angle misalignments, from a chosen 0° direction, caused by the sewing process of the textile, and finds the R-value, a value between 0 and 1. The application of this method is demonstrated by an illustrative example.
Reliability of numerical wind tunnels for VAWT simulation
Raciti Castelli, M.; Masi, M.; Battisti, L.; Benini, E.; Brighenti, A.; Dossena, V.; Persico, G.
2016-09-01
Computational Fluid Dynamics (CFD) based on the Unsteady Reynolds Averaged Navier Stokes (URANS) equations have long been widely used to study vertical axis wind turbines (VAWTs). Following a comprehensive experimental survey on the wakes downwind of a troposkien-shaped rotor, a campaign of bi-dimensional simulations is presented here, with the aim of assessing its reliability in reproducing the main features of the flow, also identifying areas needing additional research. Starting from both a well consolidated turbulence model (k-ω SST) and an unstructured grid typology, the main simulation settings are here manipulated in a convenient form to tackle rotating grids reproducing a VAWT operating in an open jet wind tunnel. The dependence of the numerical predictions from the selected grid spacing is investigated, thus establishing the less refined grid size that is still capable of capturing some relevant flow features such as integral quantities (rotor torque) and local ones (wake velocities).
Notes on numerical reliability of several statistical analysis programs
Landwehr, J.M.; Tasker, Gary D.
1999-01-01
This report presents a benchmark analysis of several statistical analysis programs currently in use in the USGS. The benchmark consists of a comparison between the values provided by a statistical analysis program for variables in the reference data set ANASTY and their known or calculated theoretical values. The ANASTY data set is an amendment of the Wilkinson NASTY data set that has been used in the statistical literature to assess the reliability (computational correctness) of calculated analytical results.
Krause, M.; Camenzind, M.
2001-12-01
In the present paper, we examine the convergence behavior and inter-code reliability of astrophysical jet simulations in axial symmetry. We consider both pure hydrodynamic jets and jets with a dynamically significant magnetic field. The setups were chosen to match the setups of two other publications, and recomputed with the MHD code NIRVANA. We show that NIRVANA and the two other codes give comparable, but not identical results. We explain the differences by the different application of artificial viscosity in the three codes and numerical details, which can be summarized in a resolution effect, in the case without magnetic field: NIRVANA turns out to be a fair code of medium efficiency. It needs approximately twice the resolution as the code by Lind (Lind et al. 1989) and half the resolution as the code by Kössl (Kössl & Müller 1988). We find that some global properties of a hydrodynamical jet simulation, like e.g. the bow shock velocity, converge at 100 points per beam radius (ppb) with NIRVANA. The situation is quite different after switching on the toroidal magnetic field: in this case, global properties converge even at 10 ppb. In both cases, details of the inner jet structure and especially the terminal shock region are still insufficiently resolved, even at our highest resolution of 70 ppb in the magnetized case and 400 ppb for the pure hydrodynamic jet. The magnetized jet even suffers from a fatal retreat of the Mach disk towards the inflow boundary, which indicates that this simulation does not converge, in the end. This is also in definite disagreement with earlier simulations, and challenges further studies of the problem with other codes. In the case of our highest resolution simulation, we can report two new features: first, small scale Kelvin-Helmholtz instabilities are excited at the contact discontinuity next to the jet head. This slows down the development of the long wavelength Kelvin-Helmholtz instability and its turbulent cascade to smaller
Reliable Damping of Free Surface Waves in Numerical Simulations
Peric, Robinson
2015-01-01
This paper generalizes existing approaches for free-surface wave damping via momentum sinks for flow simulations based on the Navier-Stokes equations. It is shown in 2D flow simulations that, to obtain reliable wave damping, the coefficients in the damping functions must be adjusted to the wave parameters. A scaling law for selecting these damping coefficients is presented, which enables similarity of the damping in model- and full-scale. The influence of the thickness of the damping layer, the wave steepness, the mesh fineness and the choice of the damping coefficients are examined. An efficient approach for estimating the optimal damping setup is presented. Results of 3D ship resistance computations show that the scaling laws apply to such simulations as well, so the damping coefficients should be adjusted for every simulation to ensure convergence of the solution in both model and full scale. Finally, practical recommendations for the setup of reliable damping in flow simulations with regular and irregular...
Krause, M.; M. Camenzind
2001-01-01
In the present paper, we examine the convergence behavior and inter-code reliability of astrophysical jet simulations in axial symmetry. We consider both, pure hydrodynamic jets and jets with a dynamically significant magnetic field. The setups were chosen to match the setups of two other publications, and recomputed with the MHD code NIRVANA. We show that NIRVANA and the two other codes give comparable, but not identical results. We find that some global properties of a hydrodynamical jet si...
Reliability Distribution of Numerical Control Lathe Based on Correlation Analysis
Xiaoyan Qi; Guixiang Shen; Yingzhi Zhang; Shuguang Sun; Bingkun Chen
2016-01-01
Combined Reliability distribution with correlation analysis, a new method has been proposed to make Reliability distribution where considering the elements about structure correlation and failure correlation of subsystems. Firstly, we make a sequence for subsystems by means of TOPSIS which comprehends the considerations of Reliability allocation, and introducing a Copula connecting function to set up a distribution model based on structure correlation, failure correlation and target correlation, and then acquiring reliability target area of all subsystems by Matlab. In this method, not only the traditional distribution considerations are concerned, but also correlation influences are involved, to achieve supplementing information and optimizing distribution.
Numerical simulations of catastrophic disruption: Recent results
Benz, W.; Asphaug, E.; Ryan, E. V.
1994-01-01
Numerical simulations have been used to study high velocity two-body impacts. In this paper, a two-dimensional Largrangian finite difference hydro-code and a three-dimensional smooth particle hydro-code (SPH) are described and initial results reported. These codes can be, and have been, used to make specific predictions about particular objects in our solar system. But more significantly, they allow us to explore a broad range of collisional events. Certain parameters (size, time) can be studied only over a very restricted range within the laboratory; other parameters (initial spin, low gravity, exotic structure or composition) are difficult to study at all experimentally. The outcomes of numerical simulations lead to a more general and accurate understanding of impacts in their many forms.
Telomere Q-PNA-FISH--reliable results from stochastic signals.
Andrea Cukusic Kalajzic
Full Text Available Structural and functional analysis of telomeres is very important for understanding basic biological functions such as genome stability, cell growth control, senescence and aging. Recently, serious concerns have been raised regarding the reliability of current telomere measurement methods such as Southern blot and quantitative polymerase chain reaction. Since telomere length is associated with age related pathologies, including cardiovascular disease and cancer, both at the individual and population level, accurate interpretation of measured results is a necessity. The telomere Q-PNA-FISH technique has been widely used in these studies as well as in commercial analysis for the general population. A hallmark of telomere Q-PNA-FISH is the wide variation among telomere signals which has a major impact on obtained results. In the present study we introduce a specific mathematical and statistical analysis of sister telomere signals during cell culture senescence which enabled us to identify high regularity in their variations. This phenomenon explains the reproducibility of results observed in numerous telomere studies when the Q-PNA-FISH technique is used. In addition, we discuss the molecular mechanisms which probably underlie the observed telomere behavior.
Public Perceptions of Reliability in Examination Results in England
He, Qingping; Boyle, Andrew; Opposs, Dennis
2011-01-01
Building on findings from existing qualitative research into public perceptions of reliability in examination results in England, a questionnaire was developed and administered to samples of teachers, students and employers to study their awareness of and opinions about various aspects of reliability quantitatively. Main findings from the study…
Some results on numerical divided difference formulas
Wang; Xinghua; Wang; Heyu; Ming-Jun; Lai
2005-01-01
The remainder estimates of numerical divided difference formula are given for the functions of lower and higher smoothness, respectively. Then several divided difference formulas with super-convergence are derived with their remainder expressions.
Research on assembly reliability control technology for computer numerical control machine tools
Yan Ran
2017-01-01
Full Text Available Nowadays, although more and more companies focus on improving the quality of computer numerical control machine tools, its reliability control still remains as an unsolved problem. Since assembly reliability control is very important in product reliability assurance in China, a new key assembly processes extraction method based on the integration of quality function deployment; failure mode, effects, and criticality analysis; and fuzzy theory for computer numerical control machine tools is proposed. Firstly, assembly faults and assembly reliability control flow of computer numerical control machine tools are studied. Secondly, quality function deployment; failure mode, effects, and criticality analysis; and fuzzy theory are integrated to build a scientific extraction model, by which the key assembly processes meeting both customer functional demands and failure data distribution can be extracted, also an example is given to illustrate the correctness and effectiveness of the method. Finally, the assembly reliability monitoring system is established based on key assembly processes to realize and simplify this method.
A new approach to numerical analysis of reliability indices in electronics
Geniy Kuznetsov
2015-01-01
Full Text Available Spatial modeling of unsteady temperature fields is conducted in a microelectronic printed circuit board (PCB with an account of convective and radiation heat transfer with the environment. The data for numerical modeling of temperature fields serve as a basis for determining the aging characteristics of the polymer material as a structural component of electronic engineering products. The obtained results allow concluding on the necessity to consider spatial nonuniform temperature fields when estimating the degree of polymeric materials degradation at the continuous service of products, as well as on the impact of polymer aging on reliability features of microelectronic devices.
Mixing in modulated turbulence. Numerical results
Yang, Yuyao; Rubinstein, Robert; Bos, Wouter
2016-01-01
Direct numerical simulations are carried out to investigate scalar mixing in an isotropic turbulent flow with a time-periodic forcing. For high amplitudes of the modulation, it is shown that the average mixing rate is negatively affected at low frequencies. In this limit the mixing time scale increases, whereas the typical velocity timescale decreases. We further determine the frequency response of scalar statistics to a periodic scalar-forcing.
Results from the LHC Beam Dump Reliability Run
Uythoven, J; Carlier, E; Castronuovo, F; Ducimetière, L; Gallet, E; Goddard, B; Magnin, N; Verhagen, H
2008-01-01
The LHC Beam Dumping System is one of the vital elements of the LHC Machine Protection System and has to operate reliably every time a beam dump request is made. Detailed dependability calculations have been made, resulting in expected rates for the different system failure modes. A 'reliability run' of the whole system, installed in its final configuration in the LHC, has been made to discover infant mortality problems and to compare the occurrence of the measured failure modes with their calculations.
Online cognition: factors facilitating reliable online neuropsychological test results.
Feenstra, Heleen E M; Vermeulen, Ivar E; Murre, Jaap M J; Schagen, Sanne B
2017-01-01
Online neuropsychological test batteries could allow for large-scale cognitive data collection in clinical studies. However, the few online neuropsychological test batteries that are currently available often still require supervision or lack proper psychometric evaluation. In this paper, we have outlined prerequisites for proper development and use of online neuropsychological tests, with the focus on reliable measurement of cognitive function in an unmonitored setting. First, we identified several technical, contextual, and psychological factors that should be taken into account in order to facilitate reliable test results of online tests in the unmonitored setting. Second, we outlined a methodology of quality assurance needed in order to obtain reliable cognitive data in the long run. Based on factors that distinguish the online unmonitored test setting from the traditional face-to-face setting, we provide a set of basic requirements and suggestions for optimal development and use of unmonitored online neuropsychological tests, including suggestions on acquiring reliability, validity, and norm scores. When properly addressing factors that could hamper reliable test results during development and use, online neuropsychological tests could aid large-scale data collection for clinical studies in the future. Investment in both proper development of online neuropsychological test platforms and the performance of accompanying psychometric studies is currently required.
史训清; John HL Pang; 杨前进; 王志平; 聂景旭
2002-01-01
In the present study, a facility, i.e., a mechanical deflection system(MDS), was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly. It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days, but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests.Based on the MDS and ATC reliability experiments, the acceleration factors (AF)were obtained for different reliability testing conditions. Furthermore, by using the creep constitutive relation and fatigue life model developed in part I, a numerical approach was established for the purpose of virtual life prediction of solder joints.The simulation results were found to be in good agreement with the test results from the MDS. As a result, a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.
Numerical methods for reliability and safety assessment multiscale and multiphysics systems
Hami, Abdelkhalak
2015-01-01
This book offers unique insight on structural safety and reliability by combining computational methods that address multiphysics problems, involving multiple equations describing different physical phenomena, and multiscale problems, involving discrete sub-problems that together describe important aspects of a system at multiple scales. The book examines a range of engineering domains and problems using dynamic analysis, nonlinear methods, error estimation, finite element analysis, and other computational techniques. This book also: · Introduces novel numerical methods · Illustrates new practical applications · Examines recent engineering applications · Presents up-to-date theoretical results · Offers perspective relevant to a wide audience, including teaching faculty/graduate students, researchers, and practicing engineers
Analysis of Numerical Simulation Results of LIPS-200 Lifetime Experiments
Chen, Juanjuan; Zhang, Tianping; Geng, Hai; Jia, Yanhui; Meng, Wei; Wu, Xianming; Sun, Anbang
2016-06-01
Accelerator grid structural and electron backstreaming failures are the most important factors affecting the ion thruster's lifetime. During the thruster's operation, Charge Exchange Xenon (CEX) ions are generated from collisions between plasma and neutral atoms. Those CEX ions grid's barrel and wall frequently, which cause the failures of the grid system. In order to validate whether the 20 cm Lanzhou Ion Propulsion System (LIPS-200) satisfies China's communication satellite platform's application requirement for North-South Station Keeping (NSSK), this study analyzed the measured depth of the pit/groove on the accelerator grid's wall and aperture diameter's variation and estimated the operating lifetime of the ion thruster. Different from the previous method, in this paper, the experimental results after the 5500 h of accumulated operation of the LIPS-200 ion thruster are presented firstly. Then, based on these results, theoretical analysis and numerical calculations were firstly performed to predict the on-orbit lifetime of LIPS-200. The results obtained were more accurate to calculate the reliability and analyze the failure modes of the ion thruster. The results indicated that the predicted lifetime of LIPS-200's was about 13218.1 h which could satisfy the required lifetime requirement of 11000 h very well.
Wimmer, Thomas, E-mail: thomas.wimmer@medunigraz.at; Srimathveeravalli, Govindarajan; Gutta, Narendra [Memorial Sloan-Kettering Cancer Center, Interventional Radiology Service, Department of Radiology (United States); Ezell, Paula C. [The Rockefeller University, Research Animal Resource Center, Memorial Sloan-Kettering Cancer Center, Weill Cornell Medical College (United States); Monette, Sebastien [The Rockefeller University, Laboratory of Comparative Pathology, Memorial Sloan-Kettering Cancer Center, Weill Cornell Medical College (United States); Maybody, Majid; Erinjery, Joseph P.; Durack, Jeremy C. [Memorial Sloan-Kettering Cancer Center, Interventional Radiology Service, Department of Radiology (United States); Coleman, Jonathan A. [Memorial Sloan-Kettering Cancer Center, Urology Service, Department of Surgery (United States); Solomon, Stephen B. [Memorial Sloan-Kettering Cancer Center, Interventional Radiology Service, Department of Radiology (United States)
2015-02-15
PurposeNumerical simulations are used for treatment planning in clinical applications of irreversible electroporation (IRE) to determine ablation size and shape. To assess the reliability of simulations for treatment planning, we compared simulation results with empiric outcomes of renal IRE using computed tomography (CT) and histology in an animal model.MethodsThe ablation size and shape for six different IRE parameter sets (70–90 pulses, 2,000–2,700 V, 70–100 µs) for monopolar and bipolar electrodes was simulated using a numerical model. Employing these treatment parameters, 35 CT-guided IRE ablations were created in both kidneys of six pigs and followed up with CT immediately and after 24 h. Histopathology was analyzed from postablation day 1.ResultsAblation zones on CT measured 81 ± 18 % (day 0, p ≤ 0.05) and 115 ± 18 % (day 1, p ≤ 0.09) of the simulated size for monopolar electrodes, and 190 ± 33 % (day 0, p ≤ 0.001) and 234 ± 12 % (day 1, p ≤ 0.0001) for bipolar electrodes. Histopathology indicated smaller ablation zones than simulated (71 ± 41 %, p ≤ 0.047) and measured on CT (47 ± 16 %, p ≤ 0.005) with complete ablation of kidney parenchyma within the central zone and incomplete ablation in the periphery.ConclusionBoth numerical simulations for planning renal IRE and CT measurements may overestimate the size of ablation compared to histology, and ablation effects may be incomplete in the periphery.
Investigation for Ensuring the Reliability of the MELCOR Analysis Results
Sung, Joonyoung; Maeng, Yunhwan; Lee, Jaeyoung [Handong Global Univ., Pohang (Korea, Republic of)
2015-10-15
Flow rate could be also main factor to be proven because it is in charge of a role which takes thermal balance through heat transfer in inner side of fuel assembly. Some problems about a reliability of MELCOR results could be posed in the 2{sup nd} technical report of NSRC project. In order to confirm whether MELCOR results are dependable, experimental data of Sandia Fuel Project 1 phase were used to be compared to be a reference. In Spent Fuel Pool (SFP) severe accident, especially in case of boil-off, partial loss of coolant accident, and complete loss of coolant accident; heat source and flow rate could be main points to analyze the MELCOR results. Heat source might be composed as decay heat and oxidation heat. Because heat source makes it possible to lead a zirconium fire situation if it is satisfied that heat accumulates in spent fuel rod and then cladding temperature could be raised continuously to be generated an oxidation heat, this might be a main factor to be confirmed. This work was proposed to investigate reliability of MELCOR results in order to confirm physical phenomena if SFP severe accident is occurred. Almost results showed that MELCOR results were significantly different by minute change of main parameter in identical condition. Therefore it could be necessary that oxidation coefficients have to be chosen as value to delineate real phenomena as possible.
Some Results on the Overall Reliability of Undirected Graphs.
1981-02-01
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Assessing the Reliability of Geoelectric Imaging Results for Permafrost Investigations
Marescot, L.; Loke, M.; Abbet, D.; Delaloye, R.; Hauck, C.; Hilbich, C.; Lambiel, C.; Reynard, E.
2007-12-01
The effects of global climate change on mountain permafrost are of increasing concern; warming thaws permafrost, thereby increasing the risk of slope instabilities. Consequently, knowledge of the extent and location of permafrost are important for construction and other geotechnical and land-management activities in mountainous areas. Geoelectric imaging is a useful tool for mapping and characterizing permafrost occurrences. To overcome the generally poor electrical contacts in the active layer, geoelectric surveys usually involve coupling the electrodes to the ground via sponges soaked in salt water. The data are processed and inverted in terms of resistivity models of the subsurface. To monitor the evolution of mountain permafrost, time-lapse geoelectric imaging may be employed. A challenging aspect in geoelectric imaging of permafrost is the very large resistivity contrast between frozen and unfrozen material. Such a contrast makes inversion and interpretation difficult. To assess whether features at depth are required by the data or are artifacts of the inversion process, the reliability of models needs to be evaluated. We use two different approaches to assess the reliability of resistivity images in permafrost investigations: (i) depth of investigation (DOI) and (ii) resolution matrix maps. To compute the DOI, two inversions of the same data set using quite different reference resistivity models are carried out. At locations where the resistivity is well constrained by the data, the inversions yield the same results. At other locations, the inversions yield different values that are controlled by the reference models. The resolution matrix, which is based on the sensitivity matrix calculated during the inversion, quantifies the degree to which each resistivity cell in the model can be resolved by the data. Application of these two approaches to field data acquired in the Swiss Alps and Jura Mountains suggests that it is very difficult to obtain dependable
Pratibha Singh
2014-08-01
Full Text Available A reliability evaluation system for the recognition of Devanagri Numerals is proposed in this paper. Reliability of classification is very important in applications of optical character recognition. As we know that the outliers and ambiguity may affect the performance of recognition system, a rejection measure must be there for the reliable recognition of the pattern. For each character image pre-processing steps like normalization, binarization, noise removal and boundary extraction is performed. After calculating the bounding box features are extracted for each partition of the numeral image. Features are calculated on three different zoning methods. Directional feature is considered which is obtained using chain code and gradient direction quantization of the orientations. The Zoning firstly, is considered made up of uniform partitions and secondly of non-uniform compartments based on the density of the pixels. For classification 1-nearest neighbor based classifier, quadratic bayes classifier and linear bayes classifier are chosen as base classifier. The base classifiers are combined using four decision combination rules namely maximum, Median, Average and Majority Voting. The framework is used to test the reliability of recognition system against ambiguity.
阚英男; 杨兆军; 李国发; 何佳龙; 王彦鹍; 李洪洲
2016-01-01
A new problem that classical statistical methods are incapable of solving is reliability modeling and assessment when multiple numerical control machine tools (NCMTs) reveal zero failures after a reliability test. Thus, the zero-failure data form and corresponding Bayesian model are developed to solve the zero-failure problem of NCMTs, for which no previous suitable statistical model has been developed. An expert−judgment process that incorporates prior information is presented to solve the difficulty in obtaining reliable prior distributions of Weibull parameters. The equations for the posterior distribution of the parameter vector and the Markov chain Monte Carlo (MCMC) algorithm are derived to solve the difficulty of calculating high-dimensional integration and to obtain parameter estimators. The proposed method is applied to a real case; a corresponding programming code and trick are developed to implement an MCMC simulation in WinBUGS, and a mean time between failures (MTBF) of 1057.9 h is obtained. Given its ability to combine expert judgment, prior information, and data, the proposed reliability modeling and assessment method under the zero failure of NCMTs is validated.
Computational uncertainty principle in nonlinear ordinary differential equations--Numerical results
无
2000-01-01
In a majority of cases of long-time numerical integration for initial-value problems, round-off error has received little attention. Using twenty-nine numerical methods, the influence of round-off error on numerical solutions is generally studied through a large number of numerical experiments. Here we find that there exists a strong dependence on machine precision (which is a new kind of dependence different from the sensitive dependence on initial conditions), maximally effective computation time (MECT) and optimal stepsize (OS) in solving nonlinear ordinary differential equations (ODEs) in finite machine precision. And an optimal searching method for evaluating MECT and OS under finite machine precision is presented. The relationships between MECT, OS, the order of numerical method and machine precision are found. Numerical results show that round-off error plays a significant role in the above phenomena. Moreover, we find two universal relations which are independent of the types of ODEs, initial values and numerical schemes. Based on the results of numerical experiments, we present a computational uncertainty principle, which is a great challenge to the reliability of long-time numerical integration for nonlinear ODEs.
Numerical results for extended field method applications. [thin plates
Donaldson, B. K.; Chander, S.
1973-01-01
This paper presents the numerical results obtained when a new method of analysis, called the extended field method, was applied to several thin plate problems including one with non-rectangular geometry, and one problem involving both beams and a plate. The numerical results show that the quality of the single plate solutions was satisfactory for all cases except those involving a freely deflecting plate corner. The results for the beam and plate structure were satisfactory even though the structure had a freely deflecting corner.
Lu, Jinshu; Xu, Zhenfeng; Xu, Song; Xie, Sensen; Wu, Haoxiao; Yang, Zhenbo; Liu, Xueqiang
2015-06-15
Air barriers have been recently developed and employed as a new type of oil containment boom. This paper presents systematic investigations on the reliability of air barriers on oil containments with the involvement of flowing water, which represents the commonly-seen shearing current in reality, by using both laboratory experiments and numerical simulations. Both the numerical and experimental investigations are carried out in a model scale. In the investigations, a submerged pipe with apertures is installed near the bottom of a tank to generate the air bubbles forming the air curtain; and, the shearing water flow is introduced by a narrow inlet near the mean free surface. The effects of the aperture configurations (including the size and the spacing of the aperture) and the location of the pipe on the effectiveness of the air barrier on preventing oil spreading are discussed in details with consideration of different air discharges and velocities of the flowing water. The research outcome provides a foundation for evaluating and/or improve the reliability of a air barrier on preventing spilled oil from further spreading.
Tokamak elongation: how much is too much? II Numerical results
Lee, Jungpyo; Freidberg, Jeffrey P
2015-01-01
The analytic theory presented in Paper I is converted into a form convenient for numerical analysis. A fast and accurate code has been written using this numerical formulation. The results are presented by first defining a reference set of physical parameters based on experimental data from high performance discharges. Numerically obtained scaling relations of maximum achievable elongation versus inverse aspect ratio are obtained for various values of poloidal beta, wall radius and feedback capability parameter in ranges near the reference values. It is also shown that each value of maximum elongation occurs at a corresponding value of optimized triangularity, whose scaling is also determined as a function of inverse aspect ratio. The results show that the theoretical predictions of maximum elongation are slightly higher than experimental observations for high performance discharges as measured by high average pressure. The theoretical optimized triangularity values are noticeably lower. We suggest that the e...
Numerical and analytical results for the two disks capacitor problem
Paffuti, Giampiero
2016-01-01
In this paper we study the two disks capacitor, for equal and different radii. The new results obtained allow a complete characterization of capacity coefficients and forces at short distances. An extensive numerical calculation confirms the theoretical results. The study shows the existence of a hierarchy in the divergent behavior of the capacitance coefficients and this implies some unusual behavior of the forces, strictly related to the dimensionality of the near-contact zone between electrodes.
Credible Mechanism for More Reliable SearchEngine Results
Mohammed Abdel Razek
2015-02-01
Full Text Available the number of websites on the Internet is growing randomly, thanks to HTML language. Consequently, a diversity of information is available on the Web, however, sometimes the content of it may be neither valuable nor trusted. This leads to a problem of a credibility of the existing information on these Websites. This paper investigates aspects affecting on the Websites credibility and then uses them along with dominant meaning of the query for improving information retrieval capabilities and to effectively manage contents. It presents a design and development of a credible mechanism that searches Web search engine and then ranks sites according to its reliability. Our experiments show that the credibility terms on the Websites can affect the ranking of the Web search engine and greatly improves retrieval effectiveness.
Numerical Simulation of Micronozzles with Comparison to Experimental Results
Thornber, B.; Chesta, E.; Gloth, O.; Brandt, R.; Schwane, R.; Perigo, D.; Smith, P.
2004-10-01
A numerical analysis of conical micronozzle flows has been conducted using the commercial software package CFD-RC FASTRAN [13]. The numerical results have been validated by comparison with direct thrust and mass flow measurements recently performed in ESTEC Propulsion Laboratory on Polyflex Space Ltd. 10mN Cold-Gas thrusters in the frame of ESA CryoSat mission. The flow is viscous dominated, with a throat Reynolds number of 5000, and the relatively large length of the nozzle causes boundary layer effects larger than usual for nozzles of this size. This paper discusses in detail the flow physics such as boundary layer growth and structure, and the effects of rarefaction. Furthermore a number of different domain sizes and exit boundary conditions are used to determine the optimum combination of computational time and accuracy.
A consistent modelling methodology for secondary settling tanks: a reliable numerical method.
Bürger, Raimund; Diehl, Stefan; Farås, Sebastian; Nopens, Ingmar; Torfs, Elena
2013-01-01
The consistent modelling methodology for secondary settling tanks (SSTs) leads to a partial differential equation (PDE) of nonlinear convection-diffusion type as a one-dimensional model for the solids concentration as a function of depth and time. This PDE includes a flux that depends discontinuously on spatial position modelling hindered settling and bulk flows, a singular source term describing the feed mechanism, a degenerating term accounting for sediment compressibility, and a dispersion term for turbulence. In addition, the solution itself is discontinuous. A consistent, reliable and robust numerical method that properly handles these difficulties is presented. Many constitutive relations for hindered settling, compression and dispersion can be used within the model, allowing the user to switch on and off effects of interest depending on the modelling goal as well as investigate the suitability of certain constitutive expressions. Simulations show the effect of the dispersion term on effluent suspended solids and total sludge mass in the SST. The focus is on correct implementation whereas calibration and validation are not pursued.
Hierarchy in directed random networks: analytical and numerical results
Mones, Enys
2012-01-01
In recent years, the theory and application of complex networks has been quickly developing in a markable way due to the increasing amount of data from real systems and to the fruitful application of powerful methods used in statistical physics. Many important characteristics of social or biological systems can be described by the study of their underlying structure of interactions. Hierarchy is one of these features that can be formulated in the language of networks. In this paper we present the analytic results on the hierarchical properties of random network models with zero correlations and also investigate the effects of different type of correlations. The behavior of hierarchy is different in the absence and the presence of the giant components. We show that the hierarchical structure can be drastically different if there are one-point correlations in the network. We also show numerical results suggesting that hierarchy does not change monotonously with the correlations and there is an optimal level of ...
Microconfined equiviscous droplet deformation: Comparison of experimental and numerical results
Vananroye, Anja; Janssen, Pieter J. A.; Anderson, Patrick D.; Van Puyvelde, Peter; Moldenaers, Paula
2008-01-01
The dynamics of confined droplets in shear flow is investigated using computational and experimental techniques for a viscosity ratio of unity. Numerical calculations, using a boundary integral method (BIM) in which the Green's functions are modified to include wall effects, are quantitatively compared with the results of confined droplet experiments performed in a counter-rotating parallel plate device. For a viscosity ratio of unity, it is experimentally seen that confinement induces a sigmoidal droplet shape during shear flow. Contrary to other models, this modified BIM model is capable of predicting the correct droplet shape during startup and steady state. The model also predicts an increase in droplet deformation and more orientation toward the flow direction with increasing degree of confinement, which is all experimentally confirmed. For highly confined droplets, oscillatory behavior is seen upon startup of flow, characterized by an overshoot in droplet length followed by droplet retraction. Finally, in the case of a viscosity ratio of unity, a minor effect of confinement on the critical capillary number is observed both numerically and experimentally.
Zhang Liang; Xue Songbai; Lu Fangyan; Han Zongjie; Wang Jianxin
2008-01-01
This paper deals with a study on SnPb and lead-free soldered joint reliability of PLCC devices with different lead counts under three kinds of temperature cycle profiles, which is based on non-linear finite element method. By analyzing the stress of soldered joints, it is found that the largest stress is at the area between the soldered joints and the leads, and analysis results indicate that the von Mises stress at the location slightly increases with the increase of lead counts. For PLCC with 84 leads the soldered joints was modeled for three typical loading (273-398 K, 218-398 K and 198-398 K) in order to study the influence of acceleration factors on the reliability of soldered joints. And the estimation of equivalent plastic strain of three different lead-free solder alloys (Sn3.8Ag0.7Cu, Sn3.5Ag and Sn37Pb) was also carried out.
无
2006-01-01
An efficient importance sampling algorithm is presented to analyze reliability of complex structural system with multiple failure modes and fuzzy-random uncertainties in basic variables and failure modes. In order to improve the sampling efficiency, the simulated annealing algorithm is adopted to optimize the density center of the importance sampling for each failure mode, and results that the more significant contribution the points make to fuzzy failure probability, the higher occurrence possibility the points are sampled. For the system with multiple fuzzy failure modes, a weighted and mixed importance sampling function is constructed. The contribution of each fuzzy failure mode to the system failure probability is represented by the appropriate factors, and the efficiency of sampling is improved furthermore. The variances and the coefficients of variation are derived for the failure probability estimations. Two examples are introduced to illustrate the rationality of the present method. Comparing with the direct Monte-Carlo method, the improved efficiency and the precision of the method are verified by the examples.
Numerical Results of 3-D Modeling of Moon Accumulation
Khachay, Yurie; Anfilogov, Vsevolod; Antipin, Alexandr
2014-05-01
For the last time for the model of the Moon usually had been used the model of mega impact in which the forming of the Earth and its sputnik had been the consequence of the Earth's collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,2] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al26,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone and additionally change the content of Moon forming to silicates. Only after the increasing of the gravitational radius of the Earth, the growing area of the future Earth's core can save also the silicate envelope fragments [3]. For understanding the further system Earth-Moon evolution it is significant to trace the origin and evolution of heterogeneities, which occur on its accumulation stage.In that paper we are modeling the changing of temperature,pressure,velocity of matter flowing in a block of 3d spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach.The numerical algorithm of the problem solution in velocity
Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian
2013-01-01
Reliability analysis of fiber-reinforced composite structures is a relatively unexplored field, and it is therefore expected that engineers and researchers trying to apply such an approach will meet certain challenges until more knowledge is accumulated. While doing the analyses included...... in the present paper, the authors have experienced some of the possible pitfalls on the way to complete a precise and robust reliability analysis for layered composites. Results showed that in order to obtain accurate reliability estimates it is necessary to account for the various failure modes described...... by the composite failure criteria. Each failure mode has been considered in a separate component reliability analysis, followed by a system analysis which gives the total probability of failure of the structure. The Model Correction Factor method used in connection with FORM (First-Order Reliability Method) proved...
Aylott, Benjamin; Boggs, William D; Boyle, Michael; Brady, Patrick R; Brown, Duncan A; Brügmann, Bernd; Buchman, Luisa T; Buonanno, Alessandra; Cadonati, Laura; Camp, Jordan; Campanelli, Manuela; Centrella, Joan; Chatterji, Shourov; Christensen, Nelson; Chu, Tony; Diener, Peter; Dorband, Nils; Etienne, Zachariah B; Faber, Joshua; Fairhurst, Stephen; Farr, Benjamin; Fischetti, Sebastian; Guidi, Gianluca; Goggin, Lisa M; Hannam, Mark; Herrmann, Frank; Hinder, Ian; Husa, Sascha; Kalogera, Vicky; Keppel, Drew; Kidder, Lawrence E; Kelly, Bernard J; Krishnan, Badri; Laguna, Pablo; Lousto, Carlos O; Mandel, Ilya; Marronetti, Pedro; Matzner, Richard; McWilliams, Sean T; Matthews, Keith D; Mercer, R Adam; Mohapatra, Satyanarayan R P; Mroué, Abdul H; Nakano, Hiroyuki; Ochsner, Evan; Pan, Yi; Pekowsky, Larne; Pfeiffer, Harald P; Pollney, Denis; Pretorius, Frans; Raymond, Vivien; Reisswig, Christian; Rezzolla, Luciano; Rinne, Oliver; Robinson, Craig; Röver, Christian; Santamaría, Lucía; Sathyaprakash, Bangalore; Scheel, Mark A; Schnetter, Erik; Seiler, Jennifer; Shapiro, Stuart L; Shoemaker, Deirdre; Sperhake, Ulrich; Stroeer, Alexander; Sturani, Riccardo; Tichy, Wolfgang; Liu, Yuk Tung; van der Sluys, Marc; van Meter, James R; Vaulin, Ruslan; Vecchio, Alberto; Veitch, John; Viceré, Andrea; Whelan, John T; Zlochower, Yosef
2009-01-01
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search algorithms using numerically generated waveforms and to foster closer collaboration between the numerical relativity and data analysis communities. We describe the results of the first NINJA analysis which focused on gravitational waveforms from binary black hole coalescence. Ten numerical relativity groups contributed numerical data which were used to generate a set of gravitational-wave signals. These signals were injected into a simulated data set, designed to mimic the response of the Initial LIGO and Virgo gravitational-wave detectors. Nine groups analysed this data using search and parameter-estimation pipelines. Matched filter algorithms, un-modelled-burst searches and Bayesian parameter-estimation and model-selection algorithms were applied to the da...
Forward and inverse problems in MHD: numerical and experimental results
Stefani, F.; Gerbeth, G.; Gundrum, T.; Xu, M. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany); Gailitis, A. [Inst. of Physics, Latvian Univ., Salaspils (Latvia)
2007-07-01
When a conducting fluid comes under the influence of a magnetic field, electrical currents are induced that give rise to a modification of this magnetic field. The ratio of induced magnetic field to applied magnetic field is characterized by the magnetic Reynolds number Rm of the flow. For large Rm, even self-excitation of a magnetic field can occur. This hydromagnetic dynamo effect is responsible for the maintenance of the magnetic fields of planets, stars and galaxies. In the present paper, we delineate some recent developments in the numerical treatment of induction effects in arbitrary geometry, and their application for dynamo experiments as well as for a ''contactless inductive flow tomography (CIFT).'' (orig.)
Lavarini, C.; Attal, M.; Kirstein, L. A.
2016-12-01
Detrital heavy minerals, particularly zircon, have been used to learn about the early evolution of the Earth and are often the only record we have of events that have affected the geological evolution of rocks at the Earth's surface (Watson and Harrison, 2005). Recently, many studies have focused on the investigation of natural and artificial bias in detrital mineral analysis in order to enhance the technique's reliability (e.g., Moecher and Samson, 2006). However, in spite of the widely-known influence of physical abrasion, no attempts have been made to quantitatively assess how it potentially biases abrasion-driven products such as the mineral assemblages on which geothermochronology relies. Here, through numerical modelling, we explore how varying a series of parameters (rock erodibility, zircon fertility, sediment travel distance, source area lithology, and initial bedload ratio) yields different river loads and zircon signatures over the fluvial system. We assume that pebbles are abraded according to the commonly used Sternberg's law (1875) and that fining due to selective sorting is negligible as well as all abrasion products are in the sand size fraction. Our results highlight that the spatial location of lithologies and variations in erodibility strongly influence the release of zircon grains into the sand fraction. Even in a scenario where a catchment is made of two lithologies with identical properties, the one further from the outlet contributes relatively more zircon to the sand fraction collected at the outlet. The experiments also show the strong influence of fertility on zircon abundance in sands, and that bias increases with basin size due to the exponential nature of abrasion. These results highlight that abrasion must be carefully accounted as a natural bias in the investigation of detrital zircons for provenance research.
Bucknor, Matthew; Grabaskas, David; Brunett, Acacia; Grelle, Austin
2015-04-26
Advanced small modular reactor designs include many advantageous design features such as passively driven safety systems that are arguably more reliable and cost effective relative to conventional active systems. Despite their attractiveness, a reliability assessment of passive systems can be difficult using conventional reliability methods due to the nature of passive systems. Simple deviations in boundary conditions can induce functional failures in a passive system, and intermediate or unexpected operating modes can also occur. As part of an ongoing project, Argonne National Laboratory is investigating various methodologies to address passive system reliability. The Reliability Method for Passive Systems (RMPS), a systematic approach for examining reliability, is one technique chosen for this analysis. This methodology is combined with the Risk-Informed Safety Margin Characterization (RISMC) approach to assess the reliability of a passive system and the impact of its associated uncertainties. For this demonstration problem, an integrated plant model of an advanced small modular pool-type sodium fast reactor with a passive reactor cavity cooling system is subjected to a station blackout using RELAP5-3D. This paper discusses important aspects of the reliability assessment, including deployment of the methodology, the uncertainty identification and quantification process, and identification of key risk metrics.
Reliability Analysis-Based Numerical Calculation of Metal Structure of Bridge Crane
Wenjun Meng
2013-01-01
Full Text Available The study introduced a finite element model of DQ75t-28m bridge crane metal structure and made finite element static analysis to obtain the stress response of the dangerous point of metal structure in the most extreme condition. The simulated samples of the random variable and the stress of the dangerous point were successfully obtained through the orthogonal design. Then, we utilized BP neural network nonlinear mapping function trains to get the explicit expression of stress in response to the random variable. Combined with random perturbation theory and first-order second-moment (FOSM method, the study analyzed the reliability and its sensitivity of metal structure. In conclusion, we established a novel method for accurately quantitative analysis and design of bridge crane metal structure.
Combining forming results via weld models to powerful numerical assemblies
Kose, K.; Rietman, Bert
2004-01-01
Forming simulations generally give satisfying results with respect to thinning, stresses, changed material properties and, with a proper springback calculation, the geometric form. The joining of parts by means of welding yields an extra change of the material properties and the residual stresses.
Combining forming results via weld models to powerful numerical assemblies
Kose, K.; Rietman, B.
2004-01-01
Forming simulations generally give satisfying results with respect to thinning, stresses, changed material properties and, with a proper springback calculation, the geometric form. The joining of parts by means of welding yields an extra change of the material properties and the residual stresses. W
Giovanni Francesco Spatola
2015-04-01
Full Text Available The use of image analysis methods has allowed us to obtain more reliable and repro-ducible immunohistochemistry (IHC results. Wider use of such approaches and sim-plification of software allowing a colorimetric study has meant that these methods are available to everyone, and made it possible to standardize the technique by a reliable systems score. Moreover, the recent introduction of multispectral image acquisition systems methods has further refined these techniques, minimizing artefacts and eas-ing the evaluation of the data by the observer.
Levy, J; Harris, J; Chen, J; Sapoznikov, D; Riley, B; De La Nuez, W; Khaskelberg, A
2001-10-01
Surface electrogastrography (EGG) is a noninvasive technique that detects gastric myoelectrical electric activity, principally the underlying pacemaker activity generated by the specialized interstitial cells of Cajal. Interest in the use of this methodology has grown because of its potential applications in describing functional gastrointestinal disorders, particularly as a tool in the evaluation of nausea, anorexia, and other dyspeptic symptoms. Fifty-five healthy volunteers (27 female), ranging in age from 6 to 18 years (mean, 11.7 years), were studied for a 1-hour baseline preprandial period and a 1-hour postprandial period after consumption of a standard 448-kcal meal. Recordings were obtained with an EGG Digitrapper or modified Polygraph (Medtronic-Synectics, Shoreview, MN). Spectral analysis by an autoregressive moving average method was used to extract numerical data on the power and frequency of gastric electrical activity from the EGG signal. The authors present normative data for healthy children and adolescents studied under a standardized protocol. Mean dominant frequency was found to be 2.9 +/- 0.40 cycles per minute preprandially and 3.1 +/- 0.35 postprandially, with 80% +/- 13% of test time spent in the normogastric range (2-4 cycles per minute) before and 85% +/- 11% after the test meal. The response of several key parameters to meal consumption was considered, and the effects of age, gender, and body mass index (BMI) on the EGG were sought. There is a postprandial increase in the rhythmicity and amplitude of gastric slow waves, as other investigators have shown in adults. Key normative values are not dependent on age, gender, or BMI. The authors discuss limitations in the data set and its interpretability. The authors establish a normative data set after developing a standardized recording protocol and test meal and show that EGG recordings can be obtained reliably in the pediatric population. Development of similar norms by investigators using
WUBTERSTEUBMSTEVEB R.; VEERS,PAUL S.
2000-01-01
Because the fatigue lifetime of wind turbine components depends on several factors that are highly variable, a numerical analysis tool called FAROW has been created to cast the problem of component fatigue life in a probabilistic framework. The probabilistic analysis is accomplished using methods of structural reliability (FORM/SORM). While the workings of the FAROW software package are defined in the user's manual, this theory manual outlines the mathematical basis. A deterministic solution for the time to failure is made possible by assuming analytical forms for the basic inputs of wind speed, stress response, and material resistance. Each parameter of the assumed forms for the inputs can be defined to be a random variable. The analytical framework is described and the solution for time to failure is derived.
A Numerical Round Robin for the Reliability Prediction of Structural Ceramics
Powers, Lynn M.; Janosik, Lesley A.
1993-01-01
A round robin has been conducted on integrated fast fracture design programs for brittle materials. An informal working group (WELFEP-WEakest Link failure probability prediction by Finite Element Postprocessors) was formed to discuss and evaluate the implementation of the programs examined in the study. Results from the study have provided insight on the differences between the various programs examined. Conclusions from the study have shown that when brittle materials are used in design, analysis must understand how to apply the concepts presented herein to failure probability analysis.
SSI on the Dynamic Behaviour of a Historical Masonry Building: Experimental versus Numerical Results
Francesca Ceroni
2014-11-01
Full Text Available A reliable procedure to identify the dynamic behaviour of existing masonry buildings is described in the paper, referring to a representative case study: a historical masonry palace located in Benevento (Italy. Since the building has been equipped with a permanent dynamic monitoring system by the Department of Civil Protection, some of the recorded data, acquired in various operating conditions, have been analysed with basic instruments of the Operational Modal Analysis in order to identify the main eigenfrequencies and vibration modes of the structure. The obtained experimental results have been compared to the numerical outcomes provided by three detailed Finite Element (FE models of the building. The influence of Soil-Structure Interaction (SSI has been also introduced in the FE model by a sub-structure approach where concentrated springs were placed at the base of the building to simulate the effect of soil and foundation on the global dynamic behaviour of the structure. The obtained results evidence that subsoil cannot a priori be disregarded in identifying the dynamic response of the building.
Vonhermann, Pieter; Pintz, Adam
1994-01-01
This manual describes the use of the ANSCARES program to prepare a neutral file of FEM stress results taken from ANSYS Release 5.0, in the format needed by CARES/LIFE ceramics reliability program. It is intended for use by experienced users of ANSYS and CARES. Knowledge of compiling and linking FORTRAN programs is also required. Maximum use is made of existing routines (from other CARES interface programs and ANSYS routines) to extract the finite element results and prepare the neutral file for input to the reliability analysis. FORTRAN and machine language routines as described are used to read the ANSYS results file. Sub-element stresses are computed and written to a neutral file using FORTRAN subroutines which are nearly identical to those used in the NASCARES (MSC/NASTRAN to CARES) interface.
Kreuzmair, Christina; Siegrist, Michael; Keller, Carmen
2016-08-01
In two experiments, we investigated the influence of numeracy on individuals' information processing of pictographs depending on numeracy via an eye-tracker. In two conditions, participants from the general population were presented with a scenario depicting the risk of having cancer and were asked to indicate their perceived risk. The risk level was high (63%) in experiment 1 (N = 70) and low (6%) in experiment 2 (N = 69). In the default condition, participants were free to use their default strategy for information processing. In the guiding-toward-the-number condition, they were prompted to count icons in the pictograph by answering with an explicit number. We used eye-tracking parameters related to the distance between sequential fixations to analyze participants' strategies for processing numerical information. In the default condition, the higher the numeracy was, the shorter the distances traversed in the pictograph were, indicating that participants counted the icons. People lower in numeracy performed increased large-area processing by comparing highlighted and nonhighlighted parts of the pictograph. In the guiding-toward-the-number condition, participants used short distances regardless of their numeracy, supporting the notion that short distances represent counting. Despite the different default processing strategies, participants processed the pictograph with a similar depth and derived similar risk perceptions. The results show that pictographs are beneficial for communicating medical risk. Pictographs make the gist salient by making the part-to-whole relationship visually available, and they facilitate low numerates' non-numeric processing of numerical information. Contemporaneously, pictographs allow high numerates to numerically process and rely on the number depicted in the pictograph.
Gearbox Reliability Collaborative Phase 1 and 2: Testing and Modeling Results; Preprint
Keller, J.; Guo, Y.; LaCava, W.; Link, H.; McNiff, B.
2012-05-01
The Gearbox Reliability Collaborative (GRC) investigates root causes of wind turbine gearbox premature failures and validates design assumptions that affect gearbox reliability using a combined testing and modeling approach. Knowledge gained from the testing and modeling of the GRC gearboxes builds an understanding of how the selected loads and events translate into internal responses of three-point mounted gearboxes. This paper presents some testing and modeling results of the GRC research during Phase 1 and 2. Non-torque loads from the rotor including shaft bending and thrust, traditionally assumed to be uncoupled with gearbox, affect gear and bearing loads and resulting gearbox responses. Bearing clearance increases bearing loads and causes cyclic loading, which could contribute to a reduced bearing life. Including flexibilities of key drivetrain subcomponents is important in order to reproduce the measured gearbox response during the tests using modeling approaches.
Hur, Jin-Huek; Lee, Tae-Gu; Moon, Sun-Ae; Lee, Sang-Jae; Yoo, Hoseon; Moon, Seung-Jae; Lee, Jae-Heon
2008-09-01
The thermal reliability of a closed-type BLDC motor for a high-speed fan is analyzed by an accelerated-life testing and numerical methods in this paper. Since a module and a motor part are integrated in a closed case, heat generated from a rotor in a motor and electronic components in the PCB module cannot be effectively removed to the outside. Therefore, the module will easily fail due to high temperature. The experiment for measuring the temperature and the surface heat flux of the electronic components is carried out to predict their surface temperature distributions and main heat sources. The accelerated-life test is accomplished to formulate the life equation depending on the environmental temperature. Moreover, the temperature of the PCB module is different from the environmental temperature since the heat generated from the motor cannot be effectively dissipated owing to the motor’s structure. Therefore a numerical method is used to predict the temperature of the PCB module, which is one of the life equation parameter, according to the environment. By numerically obtaining the maxima of the thermal stress and strain of the electronic components according to the operation environments with the temperature results, the fatigue cycle can be estimated.
李建平[1; 曾庆存[2; 丑纪范[3
2000-01-01
In a majority of cases of long-time numerical integration for initial-value problems, roundoff error has received little attention. Using twenty-nine numerical methods, the influence of round-off error on numerical solutions is generally studied through a large number of numerical experiments. Here we find that there exists a strong dependence on machine precision (which is a new kind of dependence different from the sensitive dependence on initial conditions), maximally effective computation time (MECT) and optimal stepsize (OS) in solving nonlinear ordinary differential equations (ODEs) in finite machine precision. And an optimal searching method for evaluating MECT and OS under finite machine precision is presented. The relationships between MECT, OS, the order of numerical method and machine precision are found. Numerical results show that round-off error plays a significant role in the above phenomena. Moreover, we find two universal relations which are independent of the types of ODEs, initial val
Numerical and experimental results on the spectral wave transfer in finite depth
Benassai, Guido
2016-04-01
Determination of the form of the one-dimensional surface gravity wave spectrum in water of finite depth is important for many scientific and engineering applications. Spectral parameters of deep water and intermediate depth waves serve as input data for the design of all coastal structures and for the description of many coastal processes. Moreover, the wave spectra are given as an input for the response and seakeeping calculations of high speed vessels in extreme sea conditions and for reliable calculations of the amount of energy to be extracted by wave energy converters (WEC). Available data on finite depth spectral form is generally extrapolated from parametric forms applicable in deep water (e.g., JONSWAP) [Hasselmann et al., 1973; Mitsuyasu et al., 1980; Kahma, 1981; Donelan et al., 1992; Zakharov, 2005). The present paper gives a contribution in this field through the validation of the offshore energy spectra transfer from given spectral forms through the measurement of inshore wave heights and spectra. The wave spectra on deep water were recorded offshore Ponza by the Wave Measurement Network (Piscopia et al.,2002). The field regressions between the spectral parameters, fp and the nondimensional energy with the fetch length were evaluated for fetch-limited sea conditions. These regressions gave the values of the spectral parameters for the site of interest. The offshore wave spectra were transfered from the measurement station offshore Ponza to a site located offshore the Gulf of Salerno. The offshore local wave spectra so obtained were transfered on the coastline with the TMA model (Bouws et al., 1985). Finally the numerical results, in terms of significant wave heights, were compared with the wave data recorded by a meteo-oceanographic station owned by Naples Hydrographic Office on the coastline of Salerno in 9m depth. Some considerations about the wave energy to be potentially extracted by Wave Energy Converters were done and the results were discussed.
Modified Core Wash Cytology: A reliable same day biopsy result for breast clinics.
Bulte, J P; Wauters, C A P; Duijm, L E M; de Wilt, J H W; Strobbe, L J A
2016-12-01
Fine Needle Aspiration Biopsy (FNAB), Core Needle biopsy (CNB) and hybrid techniques including Core Wash Cytology (CWC) are available for same-day diagnosis in breast lesions. In CWC a washing of the biopsy core is processed for a provisional cytological diagnosis, after which the core is processed like a regular CNB. This study focuses on the reliability of CWC in daily practice. All consecutive CWC procedures performed in a referral breast centre between May 2009 and May 2012 were reviewed, correlating CWC results with the CNB result, definitive diagnosis after surgical resection and/or follow-up. Symptomatic as well as screen-detected lesions, undergoing CNB were included. 1253 CWC procedures were performed. Definitive histology showed 849 (68%) malignant and 404 (32%) benign lesions. 80% of CWC procedures yielded a conclusive diagnosis: this percentage was higher amongst malignant lesions and lower for benign lesions: 89% and 62% respectively. Sensitivity and specificity of a conclusive CWC result were respectively 98.3% and 90.4%. The eventual incidence of malignancy in the cytological 'atypical' group (5%) was similar to the cytological 'benign' group (6%). CWC can be used to make a reliable provisional diagnosis of breast lesions within the hour. The high probability of conclusive results in malignant lesions makes CWC well suited for high risk populations. Copyright © 2016 Elsevier Ltd, BASO ~ the Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.
M. Boumaza
2015-07-01
Full Text Available Transient convection heat transfer is of fundamental interest in many industrial and environmental situations, as well as in electronic devices and security of energy systems. Transient fluid flow problems are among the more difficult to analyze and yet are very often encountered in modern day technology. The main objective of this research project is to carry out a theoretical and numerical analysis of transient convective heat transfer in vertical flows, when the thermal field is due to different kinds of variation, in time and space of some boundary conditions, such as wall temperature or wall heat flux. This is achieved by the development of a mathematical model and its resolution by suitable numerical methods, as well as performing various sensitivity analyses. These objectives are achieved through a theoretical investigation of the effects of wall and fluid axial conduction, physical properties and heat capacity of the pipe wall on the transient downward mixed convection in a circular duct experiencing a sudden change in the applied heat flux on the outside surface of a central zone.
Milk urea analytical result reliability and its methodical possibilities in the Czech Republic
Jan Říha
2013-01-01
Full Text Available Control of milk urea concentration (MUC can be used in diagnosis of the energy–nitrogen metabolism of cows. There are more analytical methods for MUC estimation and there are also discussions about their result reliability. Aim of this work was to obtain information for MUC result reliability improvement. MUC and MUN (milk urea nitrogen were investigated in 5 milk sample sets and in 7 calibration/comparison experiments. The positions of reference and indirect methods were changed in experiments. There were following analytical methods for MUC or MUN (in mg.100 ml−1: – photometric method (PH, as reference based on paradimethylaminobenzaldehyde reaction; – method Ureakvant (UK, as reference based on difference measurement of the electrical conductivity change during ureolysis; – method Chemspec (CH based on photometrical measurement of ammonia concentration after ureolysis (as reference; – spectroscopic method in mid infrared range of spectrum (FT–MIR; indirect routine method. In all methodical combinations the correlation coefficients (r varied from 0.8803 to 0.9943 (P −1 and comparable values of repeatability (from 0.65 to 1.83 mg.100 ml−1 as compared to FT–MIR MUC or MUN methods (from 1.39 to 5.6 and from 0.76 to 1.92 mg.100 ml−1 in performed experiments.
Hardikar, Kedar Y.; Liu, Bill J. J.; Bheemreddy, Venkata
2016-09-01
Gaining an understanding of degradation mechanisms and their characterization are critical in developing relevant accelerated tests to ensure PV module performance warranty over a typical lifetime of 25 years. As newer technologies are adapted for PV, including new PV cell technologies, new packaging materials, and newer product designs, the availability of field data over extended periods of time for product performance assessment cannot be expected within the typical timeframe for business decisions. In this work, to enable product design decisions and product performance assessment for PV modules utilizing newer technologies, Simulation and Mechanism based Accelerated Reliability Testing (SMART) methodology and empirical approaches to predict field performance from accelerated test results are presented. The method is demonstrated for field life assessment of flexible PV modules based on degradation mechanisms observed in two accelerated tests, namely, Damp Heat and Thermal Cycling. The method is based on design of accelerated testing scheme with the intent to develop relevant acceleration factor models. The acceleration factor model is validated by extensive reliability testing under different conditions going beyond the established certification standards. Once the acceleration factor model is validated for the test matrix a modeling scheme is developed to predict field performance from results of accelerated testing for particular failure modes of interest. Further refinement of the model can continue as more field data becomes available. While the demonstration of the method in this work is for thin film flexible PV modules, the framework and methodology can be adapted to other PV products.
Koo John
2003-10-01
Full Text Available Abstract Background Two Phase III randomized controlled clinical trials were conducted to assess the efficacy, safety, and tolerability of weekly subcutaneous administration of efalizumab for the treatment of psoriasis. Patient reported measures of psoriasis-related functionality and health-related quality of life and of psoriasis-related symptom assessments were included as part of the trials. Objective To assess the reliability, validity, and responsiveness of the patient reported outcome measures that were used in the trials – the Dermatology Life Quality Index (DLQI, the Psoriasis Symptom Assessment (PSA Scale, and two itch measures, a Visual Analog Scale (VAS and the National Psoriasis Foundation (NPF itch measure. Methods Subjects aged 18 to 70 years with moderate to severe psoriasis for at least 6 months were recruited into the two clinical trials (n = 1095. Internal consistency reliability was evaluated for all patient reported outcomes at baseline and at 12 weeks. Construct validity was evaluated by relations among the different patient reported outcomes and between the patient reported outcomes and the clinical assessments (Psoriasis Area and Severity Index; Overall Lesion Severity Scale; Physician's Global Assessment of Change assessed at baseline and at 12 weeks, as was the change over the course of the 12 week portion of the trial. Results Internal consistency reliability ranged from 0.86 to 0.95 for the patient reported outcome measures. The patient reported outcome measures were all shown to have significant construct validity with respect to each other and with respect to the clinical assessments. The four measures also demonstrated significant responsiveness to change in underlying clinical status of the patients over the course of the trial, as measured by the independently assessed clinical outcomes. Conclusions The DLQI, the PSA, VAS, and the NPF are considered useful tools for the measurement of dermatology
Test results of reliable and very high capillary multi-evaporators / condenser loop
Van Oost, S.; Dubois, M.; Bekaert, G. [Societe Anonyme Belge de Construction Aeronautique - SABCA (Belgium)
1996-12-31
The paper present the results of various SABCA activities in the field of two-phase heat transport system. These results have been based on a critical review and analysis of the existing two-phase loop and of the future loop needs in space applications. The research and the development of a high capillary wick (capillary pressure up to 38 000 Pa) are described. These activities have led towards the development of a reliable high performance capillary loop concept (HPCPL), which is discussed in details. Several loop configurations mono/multi-evaporators have been ground tested. The presented results of various tests clearly show the viability of this concept for future applications. Proposed flight demonstrations as well as potential applications conclude this paper. (authors) 7 refs.
Heike Horn
Full Text Available Few data are available regarding the reliability of fluorescence in-situ hybridization (FISH, especially for chromosomal deletions, in high-throughput settings using tissue microarrays (TMAs. We performed a comprehensive FISH study for the detection of chromosomal translocations and deletions in formalin-fixed and paraffin-embedded (FFPE tumor specimens arranged in TMA format. We analyzed 46 B-cell lymphoma (B-NHL specimens with known karyotypes for translocations of IGH-, BCL2-, BCL6- and MYC-genes. Locus-specific DNA probes were used for the detection of deletions in chromosome bands 6q21 and 9p21 in 62 follicular lymphomas (FL and six malignant mesothelioma (MM samples, respectively. To test for aberrant signals generated by truncation of nuclei following sectioning of FFPE tissue samples, cell line dilutions with 9p21-deletions were embedded into paraffin blocks. The overall TMA hybridization efficiency was 94%. FISH results regarding translocations matched karyotyping data in 93%. As for chromosomal deletions, sectioning artefacts occurred in 17% to 25% of cells, suggesting that the proportion of cells showing deletions should exceed 25% to be reliably detectable. In conclusion, FISH represents a robust tool for the detection of structural as well as numerical aberrations in FFPE tissue samples in a TMA-based high-throughput setting, when rigorous cut-off values and appropriate controls are maintained, and, of note, was superior to quantitative PCR approaches.
Horn, Heike; Bausinger, Julia; Staiger, Annette M; Sohn, Maximilian; Schmelter, Christopher; Gruber, Kim; Kalla, Claudia; Ott, M Michaela; Rosenwald, Andreas; Ott, German
2014-01-01
Few data are available regarding the reliability of fluorescence in-situ hybridization (FISH), especially for chromosomal deletions, in high-throughput settings using tissue microarrays (TMAs). We performed a comprehensive FISH study for the detection of chromosomal translocations and deletions in formalin-fixed and paraffin-embedded (FFPE) tumor specimens arranged in TMA format. We analyzed 46 B-cell lymphoma (B-NHL) specimens with known karyotypes for translocations of IGH-, BCL2-, BCL6- and MYC-genes. Locus-specific DNA probes were used for the detection of deletions in chromosome bands 6q21 and 9p21 in 62 follicular lymphomas (FL) and six malignant mesothelioma (MM) samples, respectively. To test for aberrant signals generated by truncation of nuclei following sectioning of FFPE tissue samples, cell line dilutions with 9p21-deletions were embedded into paraffin blocks. The overall TMA hybridization efficiency was 94%. FISH results regarding translocations matched karyotyping data in 93%. As for chromosomal deletions, sectioning artefacts occurred in 17% to 25% of cells, suggesting that the proportion of cells showing deletions should exceed 25% to be reliably detectable. In conclusion, FISH represents a robust tool for the detection of structural as well as numerical aberrations in FFPE tissue samples in a TMA-based high-throughput setting, when rigorous cut-off values and appropriate controls are maintained, and, of note, was superior to quantitative PCR approaches.
Haber, Ralph Norman; Haber, Lyn
2014-09-01
Our purpose in this article is to determine whether the results of the published experiments on the accuracy and reliability of fingerprint comparison can be generalized to fingerprint laboratory casework, and/or to document the error rate of the Analysis-Comparison-Evaluation (ACE) method. We review the existing 13 published experiments on fingerprint comparison accuracy and reliability. These studies comprise the entire corpus of experimental research published on the accuracy of fingerprint comparisons since criminal courts first admitted forensic fingerprint evidence about 120years ago. We start with the two studies by Ulery, Hicklin, Buscaglia and Roberts (2011, 2012), because they are recent, large, designed specifically to provide estimates of the accuracy and reliability of fingerprint comparisons, and to respond to the criticisms cited in the National Academy of Sciences Report (2009). Following the two Ulery et al. studies, we review and evaluate the other eleven experiments, considering problems that are unique to each. We then evaluate the 13 experiments for the problems common to all or most of them, especially with respect to the generalizability of their results to laboratory casework. Overall, we conclude that the experimental designs employed deviated from casework procedures in critical ways that preclude generalization of the results to casework. The experiments asked examiner-subjects to carry out their comparisons using different responses from those employed in casework; the experiments presented the comparisons in formats that differed from casework; the experiments enlisted highly trained examiners as experimental subjects rather than subjects drawn randomly from among all fingerprint examiners; the experiments did not use fingerprint test items known to be comparable in type and especially in difficulty to those encountered in casework; and the experiments did not require examiners to use the ACE method, nor was that method defined
Comparison of results of experimental research with numerical calculations of a model one-sided seal
Joachimiak Damian
2015-06-01
Full Text Available 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.
Experimental results and numerical simulations for transonic flow over the ONERA M4R model
Marius Gabriel COJOCARU
2013-06-01
Full Text Available This paper presents a comparison between experimental results of transonic flow over the ONERA M4R calibration model obtained in the INCAS Trisonic wind tunnel and the numerical results. The first purpose, emphasized in this paper is to compare and validate the computational fluid dynamics (CFD techniques for internal transonic flows and to try to find the most suitable numerical methodology for these flows in both accuracy and computational resources. The second purpose is to develop a general method in experimental data correction and flight Reynolds extrapolation, using numerical simulations for both global and local pressure coefficients, as a replacement for the classical vortex lattices based method. That will be developed in a future paper. Besides the computational work, the periodic wind tunnel calibration is required as a quality insurance operation and a numerical model is developed such that future hardware modifications to be included and their impact to be properly considered.
Phan, Ngoc Quan; Blome, Christine; Fritz, Fleur; Gerss, Joachim; Reich, Adam; Ebata, Toshiya; Augustin, Matthias; Szepietowski, Jacek C; Ständer, Sonja
2012-09-01
The most commonly used tool for self-report of pruritus intensity is the visual analogue scale (VAS). Similar tools are the numerical rating scale (NRS) and verbal rating scale (VRS). In the present study, initiated by the International Forum for the Study of Itch assessing reliability of these tools, 471 randomly selected patients with chronic itch (200 males, 271 females, mean age 58.44 years) recorded their pruritus intensity on VAS (100-mm line), NRS (0-10) and VRS (four-point) scales. Re-test reliability was analysed in a subgroup of 250 patients after one hour. Statistical analysis showed a high reliability and concurrent validity (r>0.8; pscales showed a high correlation. In conclusion, high reliability and concurrent validity was found for VAS, NRS and VRS. On re-test, higher correlation and less missing values were observed. A training session before starting a clinical trial is recommended.
MEASURING RESULTS NUMERAL TREATMENT OF IMPULSIVE CURRENTS BY MEANS OF ROGOVSKY BELT APPLICATION
U. Batygin
2009-01-01
Full Text Available The technique of numerical processing of measurement results of pulse currents by means of Rogovsky belt application is offered in the given work. It is shown that at measurement of signals by digital oscillographs and further numerical transformation of target signals, the possibilities of Rogovsky belt without the application of additional devices that in turn allows to define parameters of pulse currents with any peak-time characteristics essentially expand.
Height of burst explosions: a comparative study of numerical and experimental results
Omang, M.; Christensen, S. O.; Børve, S.; Trulsen, J.
2009-06-01
In the current work, we use the Constant Volume model and the numerical method, Regularized Smoothed Particle Hydrodynamics (RSPH) to study propagation and reflection of blast waves from detonations of the high explosives C-4 and TNT. The results from simulations of free-field TNT explosions are compared to previously published data, and good agreement is found. Measurements from height of burst tests performed by the Norwegian Defence Estates Agency are used to compare against numerical simulations. The results for shock time of arrival and the pressure levels are well represented by the numerical results. The results are also found to be in good agreement with results from a commercially available code. The effect of allowing different ratios of specific heat capacities in the explosive products are studied. We also evaluate the effect of changing the charge shape and height of burst on the triple point trajectory.
Role of numerical scheme choice on the results of mathematical modeling of combustion and detonation
Yakovenko, I. S.; Kiverin, A. D.; Pinevich, S. G.; Ivanov, M. F.
2016-11-01
The present study discusses capabilities of dissipation-free CABARET numerical method application to unsteady reactive gasdynamic flows modeling. In framework of present research the method was adopted for reactive flows governed by real gas equation of state and applied for several typical problems of unsteady gas dynamics and combustion modeling such as ignition and detonation initiation by localized energy sources. Solutions were thoroughly analyzed and compared with that derived by using of the modified Euler-Lagrange method of “coarse” particles. Obtained results allowed us to distinguish range of phenomena where artificial effects of numerical approach may counterfeit their physical nature and to develop guidelines for numerical approach selection appropriate for unsteady reactive gasdynamic flows numerical modeling.
Strong coupling results from the numerical solution of the quantum spectral curve
Hegedus, Arpad
2016-01-01
In this paper, we solved numerically the Quantum Spectral Curve (QSC) equations corresponding to some twist-2 single trace operators with even spin from the $sl(2)$ sector of $AdS_5/CFT_4$ correspondence. We describe all technical details of the numerical method which are necessary to implement it in C++ language. In the $S=2,4,6,8$ cases, our numerical results confirm the analytical results, known in the literature for the first 4 coefficients of the strong coupling expansion for the anomalous dimensions of twist-2 operators. In the case of the Konishi operator, due to the high precision of the numerical data we could give numerical predictions to the values of two further coefficients, as well. The strong coupling behaviour of the coefficients $c_{a,n}$ in the power series representation of the ${\\bf P}_{\\!a}$-functions is also investigated. Based on our numerical data, in the regime, where the index of the coefficients is much smaller than $\\lambda^{1/4}$, we conjecture that the coefficients have polynomia...
Beerens, J.C.; Ooms, G.; Pourquie, M.J.B.M.; Westerweel, J.
2014-01-01
high-viscosity liquid core surrounded by a laminar low-viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is
Aly, Sharif S; Zhao, Jianyang; Li, Ben; Jiang, Jiming
2014-01-01
The Intraclass Correlation Coefficient (ICC) is commonly used to estimate the similarity between quantitative measures obtained from different sources. Overdispersed data is traditionally transformed so that linear mixed model (LMM) based ICC can be estimated. A common transformation used is the natural logarithm. The reliability of environmental sampling of fecal slurry on freestall pens has been estimated for Mycobacterium avium subsp. paratuberculosis using the natural logarithm transformed culture results. Recently, the negative binomial ICC was defined based on a generalized linear mixed model for negative binomial distributed data. The current study reports on the negative binomial ICC estimate which includes fixed effects using culture results of environmental samples. Simulations using a wide variety of inputs and negative binomial distribution parameters (r; p) showed better performance of the new negative binomial ICC compared to the ICC based on LMM even when negative binomial data was logarithm, and square root transformed. A second comparison that targeted a wider range of ICC values showed that the mean of estimated ICC closely approximated the true ICC.
Health search engine with e-document analysis for reliable search results.
Gaudinat, Arnaud; Ruch, Patrick; Joubert, Michel; Uziel, Philippe; Strauss, Anne; Thonnet, Michèle; Baud, Robert; Spahni, Stéphane; Weber, Patrick; Bonal, Juan; Boyer, Celia; Fieschi, Marius; Geissbuhler, Antoine
2006-01-01
After a review of the existing practical solution available to the citizen to retrieve eHealth document, the paper describes an original specialized search engine WRAPIN. WRAPIN uses advanced cross lingual information retrieval technologies to check information quality by synthesizing medical concepts, conclusions and references contained in the health literature, to identify accurate, relevant sources. Thanks to MeSH terminology [1] (Medical Subject Headings from the U.S. National Library of Medicine) and advanced approaches such as conclusion extraction from structured document, reformulation of the query, WRAPIN offers to the user a privileged access to navigate through multilingual documents without language or medical prerequisites. The results of an evaluation conducted on the WRAPIN prototype show that results of the WRAPIN search engine are perceived as informative 65% (59% for a general-purpose search engine), reliable and trustworthy 72% (41% for the other engine) by users. But it leaves room for improvement such as the increase of database coverage, the explanation of the original functionalities and an audience adaptability. Thanks to evaluation outcomes, WRAPIN is now in exploitation on the HON web site (http://www.healthonnet.org), free of charge. Intended to the citizen it is a good alternative to general-purpose search engines when the user looks up trustworthy health and medical information or wants to check automatically a doubtful content of a Web page.
Experimental and numerical results of a high frequency rotating active magnetic refrigerator
Lozano, Jaime; Engelbrecht, Kurt; Bahl, Christian
2012-01-01
Experimental results for a recently developed prototype magnetic refrigeration device at The Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators...... experimentally and implemented in a one-dimensional numerical AMR model that includes also the parasitic losses from the prototype. The temperature span for a thermal load of 200 W as a function of frequency was measured and modelled. Moreover, the temperature span dependence on the cooling capacity...
Experimental and numerical results of a high frequency rotating active magnetic refrigerator
Lozano, Jaime; Engelbrecht, Kurt; Bahl, Christian R.H.
2014-01-01
Experimental results for a recently developed prototype magnetic refrigeration device at the Technical University of Denmark (DTU) were obtained and compared with numerical simulation results. A continuously rotating active magnetic regenerator (AMR) using 2.8 kg packed sphere regenerators...... and implemented in a one-dimensional numerical AMR model that includes also the parasitic losses from the prototype. The temperature span for a thermal load of 200 W as a function of frequency was measured and modelled. Moreover, the temperature span dependence on the cooling capacity as a function of cycle...
Cane, M. A.
1979-01-01
A time-dependent, primitive equation, beta plane model that is two-dimensional in the horizontal has been developed to model wind-driven equatorial ocean circulation. A simple vertical structure consisting of two layers above the thermocline with the same constant density permits a steady-state undercurrent in the model. An analytical study of the linear dynamics of the model suggests that the addition of inertial effects is needed to simulate the undercurrent properly. Also, both linear and nonlinear dynamics of the model are investigated numerically. Such nonlinear response to wind stress as a strong eastward equatorial undercurrent and an intense eastward 'countercurrent' at three deg N are noted in the numerical results.
Gore, B.R.; Dukelow, J.S. Jr.; Mitts, T.M.; Nicholson, W.L. [Pacific Northwest Lab., Richland, WA (United States)
1995-10-01
This report presents a limited assessment of the conservatism of the Accident Sequence Evaluation Program (ASEP) human reliability analysis (HRA) procedure described in NUREG/CR-4772. In particular, the, ASEP post-accident, post-diagnosis, nominal HRA procedure is assessed within the context of an individual`s performance of critical tasks on the simulator portion of requalification examinations administered to nuclear power plant operators. An assessment of the degree to which operator perforn:Lance during simulator examinations is an accurate reflection of operator performance during actual accident conditions was outside the scope of work for this project; therefore, no direct inference can be made from this report about such performance. The data for this study are derived from simulator examination reports from the NRC requalification examination cycle. A total of 4071 critical tasks were identified, of which 45 had been failed. The ASEP procedure was used to estimate human error probability (HEP) values for critical tasks, and the HEP results were compared with the failure rates observed in the examinations. The ASEP procedure was applied by PNL operator license examiners who supplemented the limited information in the examination reports with expert judgment based upon their extensive simulator examination experience. ASEP analyses were performed for a sample of 162 critical tasks selected randomly from the 4071, and the results were used to characterize the entire population. ASEP analyses were also performed for all of the 45 failed critical tasks. Two tests were performed to assess the bias of the ASEP HEPs compared with the data from the requalification examinations. The first compared the average of the ASEP HEP values with the fraction of the population actually failed and it found a statistically significant factor of two bias on the average.
Arnold tongues for a resonant injection-locked frequency divider: analytical and numerical results
Bartuccelli, Michele V; Gentile, Guido; Schilder, Frank
2009-01-01
In this paper we consider a resonant injection-locked frequency divider which is of interest in electronics, and we investigate the frequency locking phenomenon when varying the amplitude and frequency of the injected signal. We study both analytically and numerically the structure of the Arnold tongues in the frequency-amplitude plane. In particular, we provide exact analytical formulae for the widths of the tongues, which correspond to the plateaux of the devil's staircase picture. The results account for numerical and experimental findings presented in the literature for special driving terms and, additionally, extend the analysis to a more general setting.
Numerical simulations of dynamical gluinos in SU(3) Yang-Mills theory: first results
Feo, Alessandra; Kirchner, Robert; Luckmann, Silke; Montvay, Istvan; Muenster, Gernot
2000-03-01
In a numerical Monte Carlo simulation of SU(3) Yang-Mills theory with dynamical gluinos we have investigated the behaviour of the expectation value of the scalar and pseudoscalar gluino condensates in order to determine the phase structure. Preliminary results are presented as a function of the hopping parameter.
Numerical simulations of dynamical gluinos in SU(3) Yang-Mills theory first results
Feo, A; Luckmann, S; Montvay, István; Münster, G; Feo, Alessandra; Kirchner, Robert; Luckmann, Silke; Montvay, Istvan; Münster, Gernot
2000-01-01
In a numerical Monte Carlo simulation of SU(3) Yang-Mills theory with dynamical gluinos we have investigated the behaviour of the expectation value of the scalar and pseudoscalar gluino condensates in order to determine the phase structure. Preliminary results are presented as a function of the hopping parameter.
Numerical simulations of dynamical gluinos in SU (3) Yang-Mills theory: first results
Feo, Alessandra; Kirchner, Robert; Luckmann, Silke; Montvay, István; Münster, Gernot; DESY-Münster Collaboration
In a numerical Monte Carlo simulation of SU(3) Yang-Mills theory with dynamical gluinos we have investigated the behaviour of the expectation value of the scalar and pseudoscalar gluino condensates in order to determine the phase structure. Preliminary results are presented as a function of the hopping parameter.
Precise Numerical Results of IR-vertex and box integration with Extrapolation Method
Yuasa, F; Fujimoro, J; Hamaguchi, N; Ishikawa, T; Shimizu, Y
2007-01-01
We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision library, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as $10^{-150}$ GeV in the infrared vertex diagram.
Numerical Studies of Magnetohydrodynamic Activity Resulting from Inductive Transients Final Report
Sovinec, Carl R.
2005-08-29
This report describes results from numerical studies of transients in magnetically confined plasmas. The work has been performed by University of Wisconsin graduate students James Reynolds and Giovanni Cone and by the Principal Investigator through support from contract DE-FG02-02ER54687, a Junior Faculty in Plasma Science award from the DOE Office of Science. Results from the computations have added significantly to our knowledge of magnetized plasma relaxation in the reversed-field pinch (RFP) and spheromak. In particular, they have distinguished relaxation activity expected in sustained configurations from transient effects that can persist over a significant fraction of the plasma discharge. We have also developed the numerical capability for studying electrostatic current injection in the spherical torus (ST). These configurations are being investigated as plasma confinement schemes in the international effort to achieve controlled thermonuclear fusion for environmentally benign energy production. Our numerical computations have been performed with the NIMROD code (http://nimrodteam.org) using local computing resources and massively parallel computing hardware at the National Energy Research Scientific Computing Center. Direct comparisons of simulation results for the spheromak with laboratory measurements verify the effectiveness of our numerical approach. The comparisons have been published in refereed journal articles by this group and by collaborators at Lawrence Livermore National Laboratory (see Section 4). In addition to the technical products, this grant has supported the graduate education of the two participating students for three years.
Kargul T.
2015-04-01
Full Text Available Measurement of thermophysical properties of steel is possible by using different thermal analysis techniques. In the field of metallurgy the most relevant methods are Differential Thermal Analysis (DTA and Differential Scanning Calorimetry (DSC. The paper presents the results of thermophysical properties which are necessary to carry out numerical simulation of continuous casting of steel. The study was performed for two steel grades S320GD and S235JR. The main aim of the research was to determine the dependence of specific heat on temperature. On the basis of obtained results the thermal effects of phase transformations and characteristic transition temperatures were also identified. Both the specific heat of steel and thermal effects of phase transformations are included in the Fourier-Kirchhoff equation, as the material properties necessary to obtain the numerical solution. The paper presents the research methodology, analysis of results and method of determining the specific heat of steel based on the results of DSC analysis.
Schindler, Birgit Karin; Esteban, Marta; Koch, Holger Martin; Castano, Argelia; Koslitz, Stephan; Cañas, Ana; Casteleyn, Ludwine; Kolossa-Gehring, Marike; Schwedler, Gerda; Schoeters, Greet; Hond, Elly Den; Sepai, Ovnair; Exley, Karen; Bloemen, Louis; Horvat, Milena; Knudsen, Lisbeth E; Joas, Anke; Joas, Reinhard; Biot, Pierre; Aerts, Dominique; Lopez, Ana; Huetos, Olga; Katsonouri, Andromachi; Maurer-Chronakis, Katja; Kasparova, Lucie; Vrbík, Karel; Rudnai, Peter; Naray, Miklos; Guignard, Cedric; Fischer, Marc E; Ligocka, Danuta; Janasik, Beata; Reis, M Fátima; Namorado, Sónia; Pop, Cristian; Dumitrascu, Irina; Halzlova, Katarina; Fabianova, Eleonora; Mazej, Darja; Tratnik, Janja Snoj; Berglund, Marika; Jönsson, Bo; Lehmann, Andrea; Crettaz, Pierre; Frederiksen, Hanne; Nielsen, Flemming; McGrath, Helena; Nesbitt, Ian; De Cremer, Koen; Vanermen, Guido; Koppen, Gudrun; Wilhelm, Michael; Becker, Kerstin; Angerer, Jürgen
2014-07-01
between 18.9 and 45.3% for the phthalate metabolites. Plausibility control of the HBM results of all participating countries disclosed analytical shortcomings in the determination of Cd when using certain ICP/MS methods. Results were corrected by reanalyzes. The COPHES/DEMOCOPHES project for the first time succeeded in performing a harmonized pan-European HBM project. All data raised have to be regarded as utmost reliable according to the highest international state of the art, since highly renowned laboratories functioned as reference laboratories. The procedure described here, that has shown its success, can be used as a blueprint for future transnational, multicentre HBM projects.
Lazić Vukić N.
2014-01-01
Full Text Available The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code_Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results.
Nuclear Reactor Component Code CUPID-I: Numerical Scheme and Preliminary Assessment Results
Cho, Hyoung Kyu; Jeong, Jae Jun; Park, Ik Kyu; Kim, Jong Tae; Yoon, Han Young
2007-12-15
A component scale thermal hydraulic analysis code, CUPID (Component Unstructured Program for Interfacial Dynamics), is being developed for the analysis of components of a nuclear reactor, such as reactor vessel, steam generator, containment, etc. It adopted three-dimensional, transient, two phase and three-field model. In order to develop the numerical schemes for the three-field model, various numerical schemes have been examined including the SMAC, semi-implicit ICE, SIMPLE, Row Scheme and so on. Among them, the ICE scheme for the three-field model was presented in the present report. The CUPID code is utilizing unstructured mesh for the simulation of complicated geometries of the nuclear reactor components. The conventional ICE scheme that was applied to RELAP5 and COBRA-TF, therefore, were modified for the application to the unstructured mesh. Preliminary calculations for the unstructured semi-implicit ICE scheme have been conducted for a verification of the numerical method from a qualitative point of view. The preliminary calculation results showed that the present numerical scheme is robust and efficient for the prediction of phase changes and flow transitions due to a boiling and a flashing. These calculation results also showed the strong coupling between the pressure and void fraction changes. Thus, it is believed that the semi-implicit ICE scheme can be utilized for transient two-phase flows in a component of a nuclear reactor.
He, Qingping; Opposs, Dennis
2012-01-01
National tests, public examinations, and vocational qualifications in England are used for a variety of purposes, including the certification of individual learners in different subject areas and the accountability of individual professionals and institutions. However, there has been ongoing debate about the reliability and validity of their…
Buche, D. L.
2008-06-01
This report describes Northern Indiana Public Service Co. project efforts to develop an automated energy distribution and reliability system. The purpose of this project was to implement a database-driven GIS solution that would manage all of the company's gas, electric, and landbase objects. This report is second in a series of reports detailing this effort.
Test-Retest Reliability and Validity Results of the Youth Physical Activity Supports Questionnaire
Sandy Slater
2015-05-01
Full Text Available As youth obesity rates remain at unacceptably high levels, particularly across underserved populations, the promotion of physical activity has become a focus of youth obesity prevention across the United States. Thus, the purpose of this study was to develop and test the reliability and validity of a self-reported questionnaire on home, school, and neighborhood physical activity environments for youth located in low-income urban minority neighborhoods and rural areas. Third-, fourth-, and fifth-grade students and their parents were recruited from six purposively selected elementary schools (three urban and three rural. A total of 205 parent/child dyads completed two waves of a 160-item take-home survey. Test-retest reliability was calculated for the student survey and validity was determined through a combination of parental and school administrator responses, and environmental audits. The majority (90% of measures had good reliability and validity (74%; defined as ≥70% agreement. These measures collected information on the presence of electronic and play equipment in youth participants’ bedrooms and homes, and outdoor play equipment at schools, as well as who youth are active with, and what people close to them think about being active. Measures that consistently had poor reliability and validity (≤70% agreement were weekly activities youth participated in and household rules. Principal components analysis was also used to identify 11 sub-scales. This survey can be used to help identify opportunities and develop strategies to encourage underserved youth to be more physically active.
Improving the trust in results of numerical simulations and scientific data analytics
Cappello, Franck [Argonne National Lab. (ANL), Argonne, IL (United States); Constantinescu, Emil [Argonne National Lab. (ANL), Argonne, IL (United States); Hovland, Paul [Argonne National Lab. (ANL), Argonne, IL (United States); Peterka, Tom [Argonne National Lab. (ANL), Argonne, IL (United States); Phillips, Carolyn [Argonne National Lab. (ANL), Argonne, IL (United States); Snir, Marc [Argonne National Lab. (ANL), Argonne, IL (United States); Wild, Stefan [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-04-30
This white paper investigates several key aspects of the trust that a user can give to the results of numerical simulations and scientific data analytics. In this document, the notion of trust is related to the integrity of numerical simulations and data analytics applications. This white paper complements the DOE ASCR report on Cybersecurity for Scientific Computing Integrity by (1) exploring the sources of trust loss; (2) reviewing the definitions of trust in several areas; (3) providing numerous cases of result alteration, some of them leading to catastrophic failures; (4) examining the current notion of trust in numerical simulation and scientific data analytics; (5) providing a gap analysis; and (6) suggesting two important research directions and their respective research topics. To simplify the presentation without loss of generality, we consider that trust in results can be lost (or the results’ integrity impaired) because of any form of corruption happening during the execution of the numerical simulation or the data analytics application. In general, the sources of such corruption are threefold: errors, bugs, and attacks. Current applications are already using techniques to deal with different types of corruption. However, not all potential corruptions are covered by these techniques. We firmly believe that the current level of trust that a user has in the results is at least partially founded on ignorance of this issue or the hope that no undetected corruptions will occur during the execution. This white paper explores the notion of trust and suggests recommendations for developing a more scientifically grounded notion of trust in numerical simulation and scientific data analytics. We first formulate the problem and show that it goes beyond previous questions regarding the quality of results such as V&V, uncertainly quantification, and data assimilation. We then explore the complexity of this difficult problem, and we sketch complementary general
Results of Numerical Modeling and Experimental Activities in Preparation of the Maxus-5 Experiment
Bassano, Edmondo; Castagnolo, Dario; Albano, Floriana; Fortezza, Raimondo
2002-01-01
The present paper describes numerical and experimental research activities carried out at MARS center for the preparation of an experiment on the Marangoni migration of a dissolving drop, composed by a liquid binary mixture having a miscibility gap. The paper integrates the results already presented in the previous congress, the emphasis is set on the determination of the parameters to be used for the MAXUS 5 sounding rocket mission, which is scheduled for spring 2003. Level set technique has been used for the calculation of the non-steady thermo-solutal capillary flow evolution in a bounded medium.Migration velocities and volume variation are calculated for different Marangoni numbers. The results of the numerical simulations provide the determination of drop radii and temperature gradients to be used during 12 minutes of low gravity, as provided by a MAXUS rocket. Experimental results provide accurate information on the refraction index gradient variation, due to the improvement of the interpretation of the fringe pattern. These results have allowed us to determine the optical parameters that optimize the Wollaston interferometer features. Comparison between numerical and experimental results shows a good agreement.
Bozzoli, F.; Cattani, L.; Rainieri, S.; Zachár, A.
2015-11-01
In the last years, the attention of heat transfer equipments manufacturers turned toward helically coiled-tube heat exchangers, especially with regards to applications for viscous and/or particulate products. The recent progress achieved in numerical simulation motivated many research groups to develop numerical models for this kind of apparatuses. These models, intended both to improve the knowledge of the fundamental heat transfer mechanisms in curved geometries and to support the industrial design of this kind of apparatuses, are usually validated throughout the comparison with either theoretical or experimental evidences by considering average heat transfer performances. However, this approach doesn't guarantee that the validated models are able to reproduce local effects in details, which are so important in this kind of non-standard geometries. In the present paper a numerical model of convective heat transfer in coiled tubes for laminar flow regime was formulated and discussed. Its goodness was checked throughout the comparison with the latest experimental outcomes of Bozzoli et al. [1] in terms of convective heat flux distribution along the boundary of the duct, by ensuring the effectiveness of the model also in the description of local behaviours. Although the present paper reports only preliminary results of this simulation/validation process, it could be of interest for the research community because it proposes a novel approach that could be useful to validate many numerical models for nonstandard geometries.
[A systematic social observation tool: methods and results of inter-rater reliability].
Freitas, Eulilian Dias de; Camargos, Vitor Passos; Xavier, César Coelho; Caiaffa, Waleska Teixeira; Proietti, Fernando Augusto
2013-10-01
Systematic social observation has been used as a health research methodology for collecting information from the neighborhood physical and social environment. The objectives of this article were to describe the operationalization of direct observation of the physical and social environment in urban areas and to evaluate the instrument's reliability. The systematic social observation instrument was designed to collect information in several domains. A total of 1,306 street segments belonging to 149 different neighborhoods in Belo Horizonte, Minas Gerais, Brazil, were observed. For the reliability study, 149 segments (1 per neighborhood) were re-audited, and Fleiss kappa was used to access inter-rater agreement. Mean agreement was 0.57 (SD = 0.24); 53% had substantial or almost perfect agreement, and 20.4%, moderate agreement. The instrument appears to be appropriate for observing neighborhood characteristics that are not time-dependent, especially urban services, property characterization, pedestrian environment, and security.
Dragna, Didier; Blanc-Benon, Philippe; Poisson, Franck
2014-03-01
Results from outdoor acoustic measurements performed in a railway site near Reims in France in May 2010 are compared to those obtained from a finite-difference time-domain solver of the linearized Euler equations. During the experiments, the ground profile and the different ground surface impedances were determined. Meteorological measurements were also performed to deduce mean vertical profiles of wind and temperature. An alarm pistol was used as a source of impulse signals and three microphones were located along a propagation path. The various measured parameters are introduced as input data into the numerical solver. In the frequency domain, the numerical results are in good accordance with the measurements up to a frequency of 2 kHz. In the time domain, except a time shift, the predicted waveforms match the measured waveforms with a close agreement.
Numerical modelling of radon-222 entry into houses: An outline of techniques and results
Andersen, C.E.
2001-01-01
Numerical modelling is a powerful tool for studies of soil gas and radon-222 entry into houses. It is the purpose of this paper to review some main techniques and results. In the past, modelling has focused on Darcy flow of soil gas (driven by indoor–outdoor pressure differences) and combined...... diffusive and advective transport of radon. Models of different complexity have been used. The simpler ones are finite-difference models with one or two spatial dimensions. The more complex models allow for full three-dimensional and time dependency. Advanced features include: soil heterogeneity, anisotropy......, fractures, moisture, non-uniform soil temperature, non-Darcy flow of gas, and flow caused by changes in the atmospheric pressure. Numerical models can be used to estimate the importance of specific factors for radon entry. Models are also helpful when results obtained in special laboratory or test structure...
Koo John; Thompson Christine; Stone Stephen P; Bresnahan Brian W; Shikiar Richard; Revicki Dennis A
2003-01-01
Abstract Background Two Phase III randomized controlled clinical trials were conducted to assess the efficacy, safety, and tolerability of weekly subcutaneous administration of efalizumab for the treatment of psoriasis. Patient reported measures of psoriasis-related functionality and health-related quality of life and of psoriasis-related symptom assessments were included as part of the trials. Objective To assess the reliability, validity, and responsiveness of the patient reported outcome m...
Mazza, Fabio; Vulcano, Alfonso
2008-07-01
For a widespread application of dissipative braces to protect framed buildings against seismic loads, practical and reliable design procedures are needed. In this paper a design procedure based on the Direct Displacement-Based Design approach is adopted, assuming the elastic lateral storey-stiffness of the damped braces proportional to that of the unbraced frame. To check the effectiveness of the design procedure, presented in an associate paper, a six-storey reinforced concrete plane frame, representative of a medium-rise symmetric framed building, is considered as primary test structure; this structure, designed in a medium-risk region, is supposed to be retrofitted as in a high-risk region, by insertion of diagonal braces equipped with hysteretic dampers. A numerical investigation is carried out to study the nonlinear static and dynamic responses of the primary and the damped braced test structures, using step-by-step procedures described in the associate paper mentioned above; the behaviour of frame members and hysteretic dampers is idealized by bilinear models. Real and artificial accelerograms, matching EC8 response spectrum for a medium soil class, are considered for dynamic analyses.
Improved blasting results with precise initiation:Numerical simulation of sublevel caving blasting
Yi, Changping
2013-01-01
A series of numerical simulations of rock blasting using LS-DYNA software havebeen conducted to investigate the effect of short delay time on the fragmentation inunderground mines. The purpose was to test the hypothesis proposed by Rossmaniththat stress wave interaction could result in finer fragmentation by controlling theinitiation times. The blasted rock was simulated with RHT material model. After thecalculation, the elements with damage level above 0.6 were removed to simulate thefractur...
Kitaygorsky, J.; Amburgey, C.; Elliott, J. R.; Fisher, R.; Perala, R. A.
A broadband (100 MHz-1.2 GHz) plane wave electric field source was used to evaluate electric field penetration inside a simplified Boeing 707 aircraft model with a finite-difference time-domain (FDTD) method using EMA3D. The role of absorption losses inside the simplified aircraft was investigated. It was found that, in this frequency range, none of the cavities inside the Boeing 707 model are truly reverberant when frequency stirring is applied, and a purely statistical electromagnetics approach cannot be used to predict or analyze the field penetration or shielding effectiveness (SE). Thus it was our goal to attempt to understand the nature of losses in such a quasi-statistical environment by adding various numbers of absorbing objects inside the simplified aircraft and evaluating the SE, decay-time constant τ, and quality factor Q. We then compare our numerical results with experimental results obtained by D. Mark Johnson et al. on a decommissioned Boeing 707 aircraft.
A method for data handling numerical results in parallel OpenFOAM simulations
Anton, Alin [Faculty of Automatic Control and Computing, Politehnica University of Timişoara, 2" n" d Vasile Pârvan Ave., 300223, TM Timişoara, Romania, alin.anton@cs.upt.ro (Romania); Muntean, Sebastian [Center for Advanced Research in Engineering Science, Romanian Academy – Timişoara Branch, 24" t" h Mihai Viteazu Ave., 300221, TM Timişoara (Romania)
2015-12-31
Parallel computational fluid dynamics simulations produce vast amount of numerical result data. This paper introduces a method for reducing the size of the data by replaying the interprocessor traffic. The results are recovered only in certain regions of interest configured by the user. A known test case is used for several mesh partitioning scenarios using the OpenFOAM toolkit{sup ®}[1]. The space savings obtained with classic algorithms remain constant for more than 60 Gb of floating point data. Our method is most efficient on large simulation meshes and is much better suited for compressing large scale simulation results than the regular algorithms.
Numerical and Experimental Results of a Passive Free Yawing Downwind Wind Turbine
Verelst, David Robert; Van Wingerden, Jan-Willem
by coning angle, blade sweep, and blade flexibility using both numerical and experimental methods. The wind tunnel tests were organized in the Open Jet Facility of the TU Delft, and the thesis discusses the experiment’s design, construction, operation, and gives an analysis of the results. It provides...... the PhD study is a parametric blade sweep investigation for the NREL 5MW turbine, and a detailed study on load extrapolation methods based on aeroelastic simulations. It is concluded that the 3 bladed, free yawing, and downwind wind turbine can operate in a stable manner. However, numerical studies...... downwind concept is pursued in an attempt to increase the robustness of a wind turbine by eliminating the traditionally actively controlled, and sometimes failure prone yawing mechanism. Under certain conditions, such as for remote (off shore) and off grid applications, a decreased failure rate can...
Formation of surfactant-laden drops: comparison of experimental and numerical results
Kovalchuk, Nina; Kahouadji, Lyes; Simmons, Mark; Craster, Richard; Matar, Omar; Juric, Damir; Chergui, Jalel; Shin, Seungwon
2016-11-01
Drop formation is ubiquitous in many industrial processes, with surfactants being commonly used to stabilise drops. Thus, understanding the regularities of drop formation and accompanying processes, such as formation of satellite droplets in the presence of surfactant is of high importance. Here we present the results of a comparative experimental and numerical study on formation of surfactant-laden drops over a range of flow rates and surfactant concentrations. The precise parameters of the surface tension isotherm for surfactants used in the experimental study are implemented in the numerical code enabling quantitative comparison between the two approaches. It is shown that the effect of surfactant depends not only on concentration, but also on the value of critical micellar concentration (cmc). The transition to the regime where satellite droplets are no longer released was observed when the flow rate exceeded a threshold value depending on surfactant concentration and cmc value. EPSRC UK Programme Grant MEMPHIS (EP/K003976/1).
Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experiment Results
Kujawska, Tamara; Wójcik, Janusz; Nowicki, Andrzej
2010-03-01
Recent research has shown that beneficial therapeutic effects in soft tissues can be induced by the low power ultrasound (LPUS). For example, increasing of cells immunity to stress (among others thermal stress) can be obtained through the enhanced heat shock proteins (Hsp) expression induced by the low intensity ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo stimulated by ultrasound can be the potential new therapeutic approach to the neurodegenerative diseases which utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting of exposure level to ultrasound energy would allow to evaluate and optimize the ultrasound-mediated treatment efficiency. Ultrasonic regimes are controlled by adjusting the pulsed ultrasound waves intensity, frequency, duration, duty cycle and exposure time. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced by a circular focused transducer generating tone bursts in multilayer nonlinear attenuating media and to compare the numerically calculated results with the experimental data in vitro. The acoustic pressure field in multilayer biological media was calculated using our original numerical solver. For prediction of temperature fields the Pennes' bio-heat transfer equation was employed. Temperature field measurements in vitro were carried out in a fresh rat liver using the 15 mm diameter, 25 mm focal length and 2 MHz central frequency transducer generating tone bursts with the spatial peak temporal average acoustic intensity varied between 0.325 and 1.95 W/cm2, duration varied from 20 to 500 cycles at the same 20% duty cycle and the exposure time varied up to 20 minutes. The measurement data were compared with numerical simulation results obtained under experimental boundary conditions. Good agreement between the
Zemlyanaya, E. V.; Bashashin, M. V.; Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Volokhova, A. V.
2016-10-01
We consider a model of system of long Josephson junctions (LJJ) with inductive and capacitive coupling. Corresponding system of nonlinear partial differential equations is solved by means of the standard three-point finite-difference approximation in the spatial coordinate and utilizing the Runge-Kutta method for solution of the resulting Cauchy problem. A parallel algorithm is developed and implemented on a basis of the MPI (Message Passing Interface) technology. Effect of the coupling between the JJs on the properties of LJJ system is demonstrated. Numerical results are discussed from the viewpoint of effectiveness of parallel implementation.
Solving the Helmholtz equation for membranes of arbitrary shape: numerical results
Amore, Paolo [Facultad de Ciencias CUICBAS, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Physics Department, University of Texas at El Paso, El Paso, TX (United States)], E-mail: paolo.amore@gmail.google.com
2008-07-04
I calculate the modes of vibration of membranes of arbitrary shape using a collocation approach based on little sinc functions. The matrix representation of the PDE obtained using this method is explicit and does not require the calculation of integrals. To illustrate the virtues of this approach, I have considered a large number of examples, part of them are taken from the literature, and part of them new. When possible, I have tested the accuracy of these results by comparing them with the exact results (when available) or with results from the literature. In particular, in the case of the L-shaped membrane, the first example discussed in the paper, I show that it is possible to extrapolate the results obtained with different grid sizes to obtain highly precise results. Finally, I also show that the present collocation technique can be easily combined with conformal mapping to provide numerical approximations to the energies which quite rapidly converge to the exact results.
Nassar, Ahmed; Liu, Qiang; Farias, Kevin; D'Amico, Giuseppe; Tom, Cynthia; Grady, Patrick; Bennett, Ana; Diago Uso, Teresa; Eghtesad, Bijan; Kelly, Dympna; Fung, John; Abu-Elmagd, Kareem; Miller, Charles; Quintini, Cristiano
2015-02-01
Normothermic machine perfusion (NMP) is an emerging preservation modality that holds the potential to prevent the injury associated with low temperature and to promote organ repair that follows ischemic cell damage. While several animal studies have showed its superiority over cold storage (CS), minimal studies in the literature have focused on safety, feasibility, and reliability of this technology, which represent key factors in its implementation into clinical practice. The aim of the present study is to report safety and performance data on NMP of DCD porcine livers. After 60 minutes of warm ischemia time, 20 pig livers were preserved using either NMP (n = 15; physiologic perfusion temperature) or CS group (n = 5) for a preservation time of 10 hours. Livers were then tested on a transplant simulation model for 24 hours. Machine safety was assessed by measuring system failure events, the ability to monitor perfusion parameters, sterility, and vessel integrity. The ability of the machine to preserve injured organs was assessed by liver function tests, hemodynamic parameters, and histology. No system failures were recorded. Target hemodynamic parameters were easily achieved and vascular complications were not encountered. Liver function parameters as well as histology showed significant differences between the 2 groups, with NMP livers showing preserved liver function and histological architecture, while CS livers presenting postreperfusion parameters consistent with unrecoverable cell injury. Our study shows that NMP is safe, reliable, and provides superior graft preservation compared to CS in our DCD porcine model. © The Author(s) 2014.
Zueco, Joaquín; López-González, Luis María
2016-04-01
We have studied decompression processes when pressure changes that take place, in blood and tissues using a technical numerical based in electrical analogy of the parameters that involved in the problem. The particular problem analyzed is the behavior dynamics of the extravascular bubbles formed in the intercellular cavities of a hypothetical tissue undergoing decompression. Numerical solutions are given for a system of equations to simulate gas exchanges of bubbles after decompression, with particular attention paid to the effect of bubble size, nitrogen tension, nitrogen diffusivity in the intercellular fluid and in the tissue cell layer in a radial direction, nitrogen solubility, ambient pressure and specific blood flow through the tissue over the different molar diffusion fluxes of nitrogen per time unit (through the bubble surface, between the intercellular fluid layer and blood and between the intercellular fluid layer and the tissue cell layer). The system of nonlinear equations is solved using the Network Simulation Method, where the electric analogy is applied to convert these equations into a network-electrical model, and a computer code (electric circuit simulator, Pspice). In this paper, numerical results new (together to a network model improved with interdisciplinary electrical analogies) are provided.
Experimental and numerical results on the fluid flow driven by a traveling magnetic field
Lantzsch, R.; Galindo, V.; Grants, I.; Zhang, C.; Pätzold, O.; Gerbeth, G.; Stelter, M.
2007-07-01
A traveling magnetic field (TMF) driven flow and its transition from a laminar to a time-dependent flow is studied by means of ultrasonic Doppler velocimetry and numerical simulations. The experimental setup comprises a cylindrical cavity containing the electrically conducting model fluid GaInSn and a system of six equidistant coils, which are fed by an out-of-phase current to create an up- or downward directed TMF. Hence, a Lorentz force is induced in the melt which leads to meridional flow patterns. For numerical simulations commercial codes (Opera/Fidap) and a spectral code are used. The characteristic parameters of the magnetohydrodynamic model system are chosen close to the conditions used for vertical gradient freeze (VGF) crystal growth. The axisymmetric basic flow and its dependence on the dimensionless shielding parameter S are examined. It is shown that, for S>10, the flow velocity decreases significantly, whereas almost no influence is found for a smaller shielding parameter. The critical Reynolds number for the onset of instability is found in the range of 300-450. Good agreement between experimental results and the numerical simulations is achieved.
Adaptive cyclically dominating game on co-evolving networks: Numerical and analytic results
Choi, Chi Wun; Hui, Pak Ming
2016-01-01
A co-evolving and adaptive Rock (R)-Paper (P)-Scissors (S) game (ARPS) in which an agent uses one of three cyclically dominating strategies is proposed and studied numerically and analytically. An agent takes adaptive actions to achieve a neighborhood to his advantage by rewiring a dissatisfying link with a probability $p$ or switching strategy with a probability $1-p$. Numerical results revealed two phases in the steady state. An active phase for $pp_{\\text{cri}}$ has three separate clusters of agents using only R, P, and S, respectively with terminated adaptive actions. A mean-field theory of link densities in co-evolving network is formulated in a general way that can be readily modified to other co-evolving network problems of multiple strategies. The analytic results agree with simulation results on ARPS well. We point out the different probabilities of winning, losing, and drawing a game among the agents as the origin of the small discrepancy between analytic and simulation results. As a result of the a...
O' Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert
2002-08-01
A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.
Chesnut, D.A.
1991-09-01
Waste packages for a US nuclear waste repository are required to provide reasonable assurance of maintaining substantially complete containment of radionuclides for 300 to 1000 years after closure. The waiting time to failure for complex failure processes affecting engineered or manufactured systems is often found to be an exponentially-distributed random variable. Assuming that this simple distribution can be used to describe the behavior of a hypothetical single barrier waste package, calculations presented in this paper show that the mean time to failure (the only parameter needed to completely specify an exponential distribution) would have to be more than 10{sub 7} years in order to provide reasonable assurance of meeting this requirement. With two independent barriers, each would need to have a mean time to failure of only 10{sup 5} years to provide the same reliability. Other examples illustrate how multiple barriers can provide a strategy for not only achieving but demonstrating regulatory compliance.
Testing of Subgrid—Scale Stress Models by Using Results from Direct Numerical SImulations
HongruiGONG
1998-01-01
The most commonly used dynamic subgrid models,Germano's model and dynamic kinetic energy model,and their base models-the Smagorinsky model and the kinetic energy model,were tested using results from direct numerical simulations of various turbulent flows.In germano's dynamic model,the model coefficient was treated as a constant within the test filter,This treatment is conceptually inconsistent.An iteration procedure was proposed to calculate the model coefficient and an improved correlation coefficient was found.
Islam, Saiful; Belmans, Ronnie [Department of Electrical Engineering, Katholieke Universiteit Leuven, ESAT/ELECTA, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Woyte, Achim [Verenigingsstraat 39, B-1000 Brussel (Belgium); Heskes, P.J.M.; Rooij, P.M. [Energy Research Centre of the Netherlands ECN, P.O. Box 1, 1755 ZG Petten (Netherlands)
2006-07-15
Reliability, safety and quality requirements for a new type of photovoltaic module inverter have been identified and its performance has been evaluated for prototypes. The laboratory tests have to show whether the so-called second generation photovoltaic module inverter can comply with the expectations and where improvements are still necessary. Afterwards, the test results have been compared with the internationals standards. (author)
Comparative analysis of results from experimental and numerical studies on concrete strength
Mkrtychev Oleg
2017-01-01
Full Text Available Some results of numerical experiments of testing concrete cubes and prisms on unconfined compression, and the comparison of results obtained with experimental and specified data, are presented in the article. When performing calculations of structures in a nonlinear setting, it is very important to choose adequate deformation diagrams or material models. Because of the fact that there are no instructions how to use the diagrams of concrete and armature deformation in collaboration of steel and concrete, the simulation of reinforced concrete structures by finite elements of the same type without any assumptions is impossible. Numerical experiments have been performed in the LS-DYNA software package. This software package allows simulating the collaboration of concrete and steeling with the help of three-dimensional (for concrete and rod (for the reinforcement finite elements. As samples, a cube and a prism with dimensions of 150×150×150 mm and 150×150×600 mm, respectively, have been taken. The samples are simulated by solid finite elements. For the simulation of concrete, the non-linear CSCM (Continuous Surface Cap Model material is used. The tests were carried out with samples of the following classes of concrete as for cylinder compressive strength: C12, C16, C20, C25, C30, C35. This corresponds to the following classes of cube compression strength: B15, B20, B25, B30, B37, B45. The tests have been carried out considering the friction coefficients between the plates of a testing machine, and a sample. The performed researches have shown that the destruction nature of the samples in a numerical experiment corresponds to the failure nature in real tests. The investigated model of CSCM concrete can be used in the calculation of concrete and reinforced concrete structures with acceptable accuracy for main classes of concrete.
Lahaye, Noé; Paci, Alexandre; Smith, Stefan Llewellyn
2016-04-01
We examine the instability of lenticular vortices -- or lenses -- in a stratified rotating fluid. The simplest configuration is one in which the lenses overlay a deep layer and have a free surface, and this can be studied using a two-layer rotating shallow water model. We report results from laboratory experiments and high-resolution direct numerical simulations of the destabilization of vortices with constant potential vorticity, and compare these to a linear stability analysis. The stability properties of the system are governed by two parameters: the typical upper-layer potential vorticity and the size (depth) of the vortex. Good agreement is found between analytical, numerical and experimental results for the growth rate and wavenumber of the instability. The nonlinear saturation of the instability is associated with conversion from potential to kinetic energy and weak emission of gravity waves, giving rise to the formation of coherent vortex multipoles with trapped waves. The impact of flow in the lower layer is examined. In particular, it is shown that the growth rate can be strongly affected and the instability can be suppressed for certain types of weak co-rotating flow.
APG eCastro
2014-11-01
Full Text Available The Loaded Disc Culture System (LDCS is an Intervertebral Disc (IVD-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands, which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, 8 goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Detiger et al., 2013; Paul et al., 2013, 2012, 4 of these IVDs were kept in physiological condition (control and the other 4 were previously injected with chondroitinase ABC (CABC, in order to promote Degenerative Disc Disease (DDD. The loading profile intercalated 16h of activity loading with 8h of loading recovery to express the standard circadian variations.The displacement behavior of these 8 IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced Finite Element (FE model. The simulations were run on a custom FE solver (Castro et al., 2014.The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in 2 of the 4 IVDs. The 4 control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected. However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly describe the recovery
Wu, Jian-Ying; Cervera, Miguel
2017-04-20
Damage-induced strain softening is of vital importance for the modeling of localized failure in frictional-cohesive materials. This paper addresses strain localization of damaging solids and the resulting consistent frictional-cohesive crack models. As a supplement to the framework recently established for stress-based continuum material models in rate form (Wu and Cervera 2015, 2016), several classical strain-based damage models, expressed usually in total and secant format, are considered. Upon strain localization of such damaging solids, Maxwell's kinematics of a strong (or regularized) discontinuity has to be reproduced by the inelastic damage strains, which are defined by a bounded characteristic tensor and an unbounded scalar related to the damage variable. This kinematic constraint yields a set of nonlinear equations from which the discontinuity orientation and damage-type localized cohesive relations can be derived. It is found that for the "Simó and Ju 1987" isotropic damage model, the localization angles and the resulting cohesive model heavily depend on lateral deformations usually ignored in classical crack models for quasi-brittle solids. To remedy this inconsistency, a modified damage model is proposed. Its strain localization analysis naturally results in a consistent frictional-cohesive crack model of damage type, which can be regularized as a classical smeared crack model. The analytical results are numerically verified by the recently-proposed mixed stabilized finite element method, regarding a singly-perforated plate under uniaxial tension. Remarkably, for all of the damage models discussed in this work, the numerically-obtained localization angles agree almost exactly with the closed-form results. This agreement, on the one hand, consolidates the strain localization analysis based on Maxwell's kinematics and, on the other hand, illustrates versatility of the mixed stabilized finite element method.
Achtziger, Wolfgang; Stolpe, Mathias
2009-01-01
-and-bound search all have the same feasible set and differ from each other only in the objective function. This is one reason for making the resulting branch-and-bound method very efficient. The paper closes with several large-scale numerical examples. These examples are, to the knowledge of the authors, by far...... we use the theory developed in Part I to design a convergent nonlinear branch-and-bound method tailored to solve large-scale instances of the original discrete problem. The problem formulation and the needed theoretical results from Part I are repeated such that this paper is self-contained. We focus...... on the implementation details but also establish finite convergence of the branch-and-bound method. The algorithm is based on solving a sequence of continuous non-convex relaxations which can be formulated as quadratic programs according to the theory in Part I. The quadratic programs to be treated within the branch...
Chaoticity threshold in magnetized plasmas: Numerical results in the weak coupling regime
Carati, A., E-mail: andrea.carati@unimi.it; Benfenati, F.; Maiocchi, A.; Galgani, L. [Università degli Studi di Milano, Milano (Italy); Zuin, M., E-mail: matteo.zuin@igi.cnr.it [Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Padova (Italy)
2014-03-15
The present paper is a numerical counterpart to the theoretical work [Carati et al., Chaos 22, 033124 (2012)]. We are concerned with the transition from order to chaos in a one-component plasma (a system of point electrons with mutual Coulomb interactions, in a uniform neutralizing background), the plasma being immersed in a uniform stationary magnetic field. In the paper [Carati et al., Chaos 22, 033124 (2012)], it was predicted that a transition should take place when the electron density is increased or the field decreased in such a way that the ratio ω{sub p}/ω{sub c} between plasma and cyclotron frequencies becomes of order 1, irrespective of the value of the so-called Coulomb coupling parameter Γ. Here, we perform numerical computations for a first principles model of N point electrons in a periodic box, with mutual Coulomb interactions, using as a probe for chaoticity the time-autocorrelation function of magnetization. We consider two values of Γ (0.04 and 0.016) in the weak coupling regime Γ ≪ 1, with N up to 512. A transition is found to occur for ω{sub p}/ω{sub c} in the range between 0.25 and 2, in fairly good agreement with the theoretical prediction. These results might be of interest for the problem of the breakdown of plasma confinement in fusion machines.
Investigation of film boiling thermal hydraulics under FCI conditions. Results of a numerical study
Dinh, T.N.; Dinh, A.T.; Nourgaliev, R.R.; Sehgal, B.R. [Div. of Nuclear Power Safety Royal Inst. of Tech. (RIT), Brinellvaegen 60, 10044 Stockholm (Sweden)
1998-01-01
Film boiling on the surface of a high-temperature melt jet or of a melt particle is one of key phenomena governing the physics of fuel-coolant interactions (FCIs) which may occur during the course of a severe accident in a light water reactor (LWR). A number of experimental and analytical studies have been performed, in the past, to address film boiling heat transfer and the accompanying hydrodynamic aspects. Most of the experiments have, however, been performed for temperature and heat flux conditions, which are significantly lower than the prototypic conditions. For ex-vessel FCIs, high liquid subcooling can significantly affect the FCI thermal hydraulics. Presently, there are large uncertainties in predicting natural-convection film boiling of subcooled liquids on high-temperature surfaces. In this paper, research conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning film-boiling thermal hydraulics under FCI condition is presented. Notably, the focus is placed on the effects of (1) water subcooling, (2) high-temperature steam properties, (3) the radiation heat transfer and (4) mixing zone boiling dynamics, on the vapor film characteristics. Numerical investigations are performed using a novel CFD modeling concept named as the local-homogeneous-slip model (LHSM). Results of the analytical and numerical studies are discussed with respect to boiling dynamics under FCI conditions. (author)
Carrano, Charles S.; Rino, Charles L.
2016-06-01
We extend the power law phase screen theory for ionospheric scintillation to account for the case where the refractive index irregularities follow a two-component inverse power law spectrum. The two-component model includes, as special cases, an unmodified power law and a modified power law with spectral break that may assume the role of an outer scale, intermediate break scale, or inner scale. As such, it provides a framework for investigating the effects of a spectral break on the scintillation statistics. Using this spectral model, we solve the fourth moment equation governing intensity variations following propagation through two-dimensional field-aligned irregularities in the ionosphere. A specific normalization is invoked that exploits self-similar properties of the structure to achieve a universal scaling, such that different combinations of perturbation strength, propagation distance, and frequency produce the same results. The numerical algorithm is validated using new theoretical predictions for the behavior of the scintillation index and intensity correlation length under strong scatter conditions. A series of numerical experiments are conducted to investigate the morphologies of the intensity spectrum, scintillation index, and intensity correlation length as functions of the spectral indices and strength of scatter; retrieve phase screen parameters from intensity scintillation observations; explore the relative contributions to the scintillation due to large- and small-scale ionospheric structures; and quantify the conditions under which a general spectral break will influence the scintillation statistics.
Ultimate tensile strength of embedded I-sections: a comparison of experimental and numerical results
Heristchian, Mahmoud; Pourakbar, Pouyan; Imeni, Saeed; Ramezani, M. Reza Adib
2014-12-01
Exposed baseplates together with anchor bolts are the customary method of connection of steel structures to the concrete footings. Post-Kobe studies revealed that the embedded column bases respond better to the earthquake uplift forces. The embedded column bases also, offer higher freedom in achieving the required strength, rigidity and ductility. The paper presents the results of the pullout failure of three embedded IPE140 sections, tested under different conditions. The numerical models are then, generated in Abaqus 6.10-1 software. It is concluded that, the steel profiles could be directly anchored in concrete without using anchor bolts as practiced in the exposed conventional column bases. Such embedded column bases can develop the required resistance against pullout forces at lower constructional costs.
Marom, Gil; Bluestein, Danny
2016-01-01
This paper evaluated the influence of various numerical implementation assumptions on predicting blood damage in cardiovascular devices using Lagrangian methods with Eulerian computational fluid dynamics. The implementation assumptions that were tested included various seeding patterns, stochastic walk model, and simplified trajectory calculations with pathlines. Post processing implementation options that were evaluated included single passage and repeated passages stress accumulation and time averaging. This study demonstrated that the implementation assumptions can significantly affect the resulting stress accumulation, i.e., the blood damage model predictions. Careful considerations should be taken in the use of Lagrangian models. Ultimately, the appropriate assumptions should be considered based the physics of the specific case and sensitivity analysis, similar to the ones presented here, should be employed.
Interacting steps with finite-range interactions: Analytical approximation and numerical results
Jaramillo, Diego Felipe; Téllez, Gabriel; González, Diego Luis; Einstein, T. L.
2013-05-01
We calculate an analytical expression for the terrace-width distribution P(s) for an interacting step system with nearest- and next-nearest-neighbor interactions. Our model is derived by mapping the step system onto a statistically equivalent one-dimensional system of classical particles. The validity of the model is tested with several numerical simulations and experimental results. We explore the effect of the range of interactions q on the functional form of the terrace-width distribution and pair correlation functions. For physically plausible interactions, we find modest changes when next-nearest neighbor interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.
Cotel, Aline; Junghans, Lars; Wang, Xiaoxiang
2014-11-01
In recent years, a recognition of the scope of the negative environmental impact of existing buildings has spurred academic and industrial interest in transforming existing building design practices and disciplinary knowledge. For example, buildings alone consume 72% of the electricity produced annually in the United States; this share is expected to rise to 75% by 2025 (EPA, 2009). Significant reductions in overall building energy consumption can be achieved using green building methods such as natural ventilation. An office was instrumented on campus to acquire CO2 concentrations and temperature profiles at multiple locations while a single occupant was present. Using openFOAM, numerical calculations were performed to allow for comparisons of the CO2 concentration and temperature profiles for different ventilation strategies. Ultimately, these results will be the inputs into a real time feedback control system that can adjust actuators for indoor ventilation and utilize green design strategies. Funded by UM Office of Vice President for Research.
Numerical results in a vertical wind axis turbine with relative rotating blades
Bayeul-Laine, Annie-Claude; Dockter, Aurore; Simonet, Sophie; Bois, Gerard [Arts et Metiers PARISTECH (France)
2011-07-01
The use of wind energy to produce electricity through wind turbines has spread world-wide. The quantity of electricity produced is affected by numerous factors such as wind speed and direction and turbine design; the aim of this paper is to assess the influence of different blades on the performance of a turbine. This study was performed on a turbine in which the blades have a rotating movement, each around its own axis and around the turbine's axis. Unsteady simulations were carried out with several blade stagger angles and one wind speed and 2 different blade geometries were used for 4 rotational speeds. Results showed that the studied turbine gave better performance than vertical axis wind turbines and that blade sketch, blade speed ratios, and blade stagger angle were important influences on the performance. This study showed that this kind of turbine has the potential to achieve good performance but that further work needs to be done.
Milošević, M.; Dimitrijević, D. D.; Djordjević, G. S.; Stojanović, M. D.
2016-06-01
The role tachyon fields may play in evolution of early universe is discussed in this paper. We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index (n), and tensor-scalar ratio (r) for the given potentials. We pay special attention to the inverse power potential, first of all to V(x)˜ x^{-4}, and compare the available results obtained by analytical and numerical methods with those obtained by observation. It is shown that the computed values of the observational parameters and the observed ones are in a good agreement for the high values of the constant X_0. The possibility that influence of the radion field can extend a range of the acceptable values of the constant X_0 to the string theory motivated sector of its values is briefly considered.
Barbati, Alexander C; Kirby, Brian J
2016-07-01
We derive an approximate analytical representation of the conductivity for a 1D system with porous and charged layers grafted onto parallel plates. Our theory improves on prior work by developing approximate analytical expressions applicable over an arbitrary range of potentials, both large and small as compared to the thermal voltage (RTF). Further, we describe these results in a framework of simplifying nondimensional parameters, indicating the relative dominance of various physicochemical processes. We demonstrate the efficacy of our approximate expression with comparisons to numerical representations of the exact analytical conductivity. Finally, we utilize this conductivity expression, in concert with other components of the electrokinetic coupling matrix, to describe the streaming potential and electroviscous effect in systems with porous and charged layers.
Lima da Silva, M.; Sauvage, E.; Brun, P. [CEA-Marcoule, BP 17171, 30207 Bagnols sur Ceze (France); Gagnoud, A.; Fautrelle, Y. [SIMaP, Grenoble INP, UJF, CNRS, BP 75, 38402 Saint Martin D' Heres (France); Riva, R. [CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble (France)
2013-07-01
The process of vitrification in a cold crucible heated by direct induction is used in the fusion of oxides. Its feature is the production of high-purity materials. The high-level of purity of the molten is achieved because this melting technique excludes the contamination of the charge by the crucible. The aim of the present paper is to analyze the hydrodynamic of the vitrification process by direct induction, with the focus in the effects associated with the interaction between the mechanical stirrer and bubbling. Considering the complexity of the analyzed system and the goal of the present work, we simplified the system by not taking into account the thermal and electromagnetic phenomena. Based in the concept of hydraulic similitude, we performed an experimental study and a numerical modeling of the simplified model. The results of these two studies were compared and showed a good agreement. The results presented in this paper in conjunction with the previous work contribute to a better understanding of the hydrodynamics effects resulting from the interaction between the mechanical stirrer and air bubbling in the cold crucible heated by direct induction. Further works will take into account thermal and electromagnetic phenomena in the presence of mechanical stirrer and air bubbling. (authors)
Kim, Kyung Cho; Kim, Jin Gyum; Kang, Sung Sik; Jhung, Myung Jo [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2017-04-15
The Korea Institute of Nuclear Safety, as a representative organization of Korea, in February 2012 participated in an international Program to Assess the Reliability of Emerging Nondestructive Techniques initiated by the U.S. Nuclear Regulatory Commission. The goal of the Program to Assess the Reliability of Emerging Nondestructive Techniques is to investigate the performance of emerging and prospective novel nondestructive techniques to find flaws in nickel-alloy welds and base materials. In this article, Korean round-robin test results were evaluated with respect to the test blocks and various nondestructive examination techniques. The test blocks were prepared to simulate large-bore dissimilar metal welds, small-bore dissimilar metal welds, and bottom-mounted instrumentation penetration welds in nuclear power plants. Also, lessons learned from the Korean round-robin test were summarized and discussed.
Kyung Cho Kim
2017-04-01
Full Text Available The Korea Institute of Nuclear Safety, as a representative organization of Korea, in February 2012 participated in an international Program to Assess the Reliability of Emerging Nondestructive Techniques initiated by the U.S. Nuclear Regulatory Commission. The goal of the Program to Assess the Reliability of Emerging Nondestructive Techniques is to investigate the performance of emerging and prospective novel nondestructive techniques to find flaws in nickel-alloy welds and base materials. In this article, Korean round-robin test results were evaluated with respect to the test blocks and various nondestructive examination techniques. The test blocks were prepared to simulate large-bore dissimilar metal welds, small-bore dissimilar metal welds, and bottom-mounted instrumentation penetration welds in nuclear power plants. Also, lessons learned from the Korean round-robin test were summarized and discussed.
Kowalski, Julia; Francke, Gero; Feldmann, Marco; Espe, Clemens; Heinen, Dirk; Digel, Ilya; Clemens, Joachim; Schüller, Kai; Mikucki, Jill; Tulaczyk, Slawek M.; Pettit, Erin; Berry Lyons, W.; Dachwald, Bernd
2017-04-01
results of its deployment at Blood Falls. In contrast to conventional melting-probe applications, which can only melt vertically, the IceMole realized an oblique melting path to penetrate the englacial conduit. Experimental and numerical results on melting at oblique angles are rare. Besides reporting on the IceMole technology and the field deployment itself, we will compare and discuss the observed melting behavior with re-analysis results in the context of a recently developed numerical model. Finally, we will present our first steps in utilizing the model to infer on the ambient cryo-environment.
Nakayachi, Kazuya; Watabe, Motoki
2005-08-01
This research examined the effects of providing a monitoring and self-sanctioning system, called "hostage posting" in economics, on the improvement of trustworthiness. We conducted two questionnaire-type experiments to compare the trust-improving effects among the three conditions, (a) a voluntary provision of a monitoring and self-sanction system by the manager, (b) an imposed provision, and (c) an achievement of satisfactory management without any types of provisions. Total of 561 undergraduate students participated in the experiments. Results revealed that perceived integrity and competence were improved to almost the same level in both conditions (a) and (c), whereas these were not improved in condition (b). Consistent with our previous research, these results showed that the voluntary hostage posting improved trustworthiness level as well as a good performance did. The estimation of necessity of the system, however, was not different across these conditions. The implications for management practice and directions for future research were discussed.
Resazurin Live Cell Assay: Setup and Fine-Tuning for Reliable Cytotoxicity Results.
Rodríguez-Corrales, José Á; Josan, Jatinder S
2017-01-01
In vitro cytotoxicity tests allow for fast and inexpensive screening of drug efficacy prior to in vivo studies. The resazurin assay (commercialized as Alamar Blue(®)) has been extensively utilized for this purpose in 2D and 3D cell cultures, and high-throughput screening. However, improper or lack of assay validation can generate unreliable results and limit reproducibility. Herein, we report a detailed protocol for the optimization of the resazurin assay to determine relevant analytical (limits of detection, quantification, and linear range) and biological (growth kinetics) parameters, and, thus, provide accurate cytotoxicity results. Fine-tuning of the resazurin assay will allow accurate and fast quantification of cytotoxicity for drug discovery. Unlike more complicated methods (e.g., mass spectrometry), this assay utilizes fluorescence spectroscopy and, thus, provides a less costly alternative to observe changes in the reductase proteome of the cells.
Naredo, ee.; Møller, I.; Moragues, C.
2006-01-01
: The shoulder, wrist/hand, ankle/foot, or knee of 24 patients with rheumatic diseases were evaluated by 23 musculoskeletal ultrasound experts from different European countries randomly assigned to six groups. The participants did not reach consensus on scanning method or diagnostic criteria before......, tendon lesions, bursitis, and power Doppler signal. Afterwards they compared the ultrasound findings and re-examined the patients together while discussing their results. RESULTS: Overall agreements were 91% for joint effusion/synovitis and tendon lesions, 87% for cortical abnormalities, 84......% for tenosynovitis, 83.5% for bursitis, and 83% for power Doppler signal; kappa values were good for the wrist/hand and knee (0.61 and 0.60) and fair for the shoulder and ankle/foot (0.50 and 0.54). The principal differences in scanning method and diagnostic criteria between experts were related to dynamic...
Hrubý J.
2013-04-01
Full Text Available The paper describes new results for an experimental heat exchanger equipped with a single corrugated capillary tube, basic information about the measurements and the experimental setup. Some of the results were compared with numerical simulations.
Beniaiche, Ahmed; Ghenaiet, Adel; Carcasci, Carlo; Facchini, Bruno
2017-02-01
This paper presents a numerical validation of the aero-thermal study of a 30:1 scaled model reproducing an innovative trailing edge with one row of enlarged pedestals under stationary and rotating conditions. A CFD analysis was performed by means of commercial ANSYS-Fluent modeling the isothermal air flow and using k- ω SST turbulence model and an isothermal air flow for both static and rotating conditions (Ro up to 0.23). The used numerical model is validated first by comparing the numerical velocity profiles distribution results to those obtained experimentally by means of PIV technique for Re = 20,000 and Ro = 0-0.23. The second validation is based on the comparison of the numerical results of the 2D HTC maps over the heated plate to those of TLC experimental data, for a smooth surface for a Reynolds number = 20,000 and 40,000 and Ro = 0-0.23. Two-tip conditions were considered: open tip and closed tip conditions. Results of the average Nusselt number inside the pedestal ducts region are presented too. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.
Numerical results on the contribution of an earthworm hole to infiltration
Pezzotti, Dario; Barontini, Stefano; Casali, Federico; Comincini, Mattia; Peli, Marco; Ranzi, Roberto; Rizzo, Gabriele; Tomirotti, Massimo; Vitale, Paolo
2017-04-01
On 9 March 2016 the WormEx I experiment was launched at the experimental site of Cividate Camuno (274ma.s.l., Oglio river basin, Central Italian Alps), aiming at contributing to understand how the soil-fauna digging activity affects soil-water flow. Particularly the experiment investigates the effects of earthworms holes on the soil-water constitutive laws, in the uppermost layers of a shallow anthropized soil. In this framework a set of simulations of the water flow in presence of an earthworm hole was preliminarily performed. The FV-FD numerical code AdHydra was used to solve the Richards equation in an axis-symmetric 2D domain around a vertical earthworm hole. The hole was represented both as a void cylinder and as a virtual porous domain with typical constitutive laws of a Δ-soil. The hypothesis of Poiseuille flow and the Jourin-Borelli law applied to determine its conductivity and soil-water retention relationship. Different scenarios of hole depth and infiltration rate were explored. As a result a meaningful change in the downflow condition was observed when burrows intersect a layered soil, both in saturated and partially unsaturated soils, in case a perched water table onsets at the interface between an upper and more conductive soil layer and a lower and less conductive one. These results may contribute to a better understanding of the streamflow generation processes and soil-water movement in shallow layered soils.
Numerical computation of the EOB potential q using self-force results
Akcay, Sarp
2015-01-01
The effective-one-body theory (EOB) describes the conservative dynamics of compact binary systems in terms of an effective Hamiltonian approach. The Hamiltonian for moderately eccentric motion of two non-spinning compact objects in the extreme mass-ratio limit is given in terms of three potentials: $a(v), \\bar{d}(v), q(v)$. By generalizing the first law of mechanics for (non-spinning) black hole binaries to eccentric orbits, [\\prd{\\bf92}, 084021 (2015)] recently obtained new expressions for $\\bar{d}(v)$ and $q(v)$ in terms of quantities that can be readily computed using the gravitational self-force approach. Using these expressions we present a new computation of the EOB potential $q(v)$ by combining results from two independent numerical self-force codes. We determine $q(v)$ for inverse binary separations in the range $1/1200 \\le v \\lesssim 1/6$. Our computation thus provides the first-ever strong-field results for $q(v)$. We also obtain $\\bar{d}(v)$ in our entire domain to a fractional accuracy of $\\gtrsim...
Popov V.V
2016-01-01
Full Text Available In this paper, a numerical study of the formation of nitrogen oxides in the combustion chamber based on the model created by Mitchellom and Terbellom. The distribution of furnace temperature and the concentration of nitrogen oxides, as well as a comparison of numerical results with the data of field experiment.
Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.
2011-01-01
Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.
Xing, H. L.; Ding, R. W.; Yuen, D. A.
2015-08-01
Australia is surrounded by the Pacific Ocean and the Indian Ocean and, thus, may suffer from tsunamis due to its proximity to the subduction earthquakes around the boundary of Australian Plate. Potential tsunami risks along the eastern coast, where more and more people currently live, are numerically investigated through a scenario-based method to provide an estimation of the tsunami hazard in this region. We have chosen and calculated the tsunami waves generated at the New Hebrides Trench and the Puysegur Trench, and we further investigated the relevant tsunami hazards along the eastern coast and their sensitivities to various sea floor frictions and earthquake parameters (i.e. the strike, the dip and the slip angles and the earthquake magnitude/rupture length). The results indicate that the Puysegur trench possesses a seismic threat causing wave amplitudes over 1.5 m along the coast of Tasmania, Victoria, and New South Wales, and even reaching over 2.6 m at the regions close to Sydney, Maria Island, and Gabo Island for a certain worse case, while the cities along the coast of Queensland are potentially less vulnerable than those on the southeastern Australian coast.
Milošević M.
2016-01-01
Full Text Available The role tachyon fields may play in evolution of early universe is discussed in this paper. We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index (n, and tensor-scalar ratio (r for the given potentials. We pay special attention to the inverse power potential, first of all to V (x ~ x−4, and compare the available results obtained by analytical and numerical methods with those obtained by observation. It is shown that the computed values of the observational parameters and the observed ones are in a good agreement for the high values of the constant X0. The possibility that influence of the radion field can extend a range of the acceptable values of the constant X0 to the string theory motivated sector of its values is briefly considered. [Projekat Ministarstva nauke Republike Srbije, br. 176021, br. 174020 i br. 43011
Klapp, J.; Cervantes-Cota, J.; Chauvet, P.
1990-11-01
RESUMEN. A nivel cosmol6gico pensamos que se ha estado prodticiendo radiaci6n gravitacional en cantidades considerables dentro de las galaxias. Si los eventos prodnctores de radiaci6n gravitatoria han venido ocurriendo desde Ia epoca de Ia formaci6n de las galaxias, cuando menos, sus efectos cosmol6gicos pueden ser tomados en cuenta con simplicidad y elegancia al representar la producci6n de radiaci6n y, por consiguiente, su interacci6n con materia ordinaria fenomenol6gicamente a trave's de una ecuaci6n de estado politr6pica, como lo hemos mostrado en otros trabajos. Presentamos en este articulo resultados nunericos de este modelo. ABSTRACT A common believe in cosmology is that gravitational radiation in considerable quantities is being produced within the galaxies. Ifgravitational radiation production has been running since the galaxy formation epoch, at least, its cosmological effects can be assesed with simplicity and elegance by representing the production of radiation and, therefore, its interaction with ordinary matter phenomenologically through a polytropic equation of state as shown already elsewhere. We present in this paper the numerical results of such a model. K words: COSMOLOGY - GRAVITATION
Gorczyk, W.; Vogt, K.; Gerya, T.; Hobbs, B. E.
2012-12-01
It is becoming increasingly apparent that intense deformation, metamorphism and metasomatism occur within continental cratonic blocks far removed form subducting margins Such changes may occur intra-cratonically arising from lithospheric thickening and the development of gravitational instabilities, but mostly occur at the boundary of cratonic blocks. The contact of two cratons is characterized by rheological lateral variations within mantle-lithosphere and overlying crust. Tectonic stresses acting on craton/craton boundaries may lead to thinning or thickening due to delamination of the mantle lithosphere. This is reflected in tectonic deformation, topography evolution, melting and crustal metamorphism. To understand the controls on these processes a number of 2D, coupled petrological thermo-mechanical numerical experiments has been performed to test the response of a laterally weakened zone to a compressional regime. The results indicate that the presence of water-bearing minerals in the lithosphere and lower crust is essential to initiate melting, which in the later stages may expand to dry melting of crust and mantle. In the case of anhydrous crust and lithosphere, no melting occurs. Thus a variety of instabilities, melting behaviour and topographic responses occurs at the base of the lithosphere as well as intensive faulting and buckling in the crust dependent on the strength and "water" content of the lithosphere.
Sprenger, Lisa, E-mail: Lisa.Sprenger@tu-dresden.de; Lange, Adrian; Odenbach, Stefan [Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Measuring and Automation Technology, TU Dresden, 01062 Dresden (Germany)
2014-02-15
Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: S{sub T‖} = −0.152 K{sup −1} and S{sub T⊥} = −0.257 K{sup −1} at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ{sub ‖} and ξ{sub ⊥} used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field
A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers. 2; Numerical Results
Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)
2001-01-01
We present numerical results of the diffusion coefficients (DCs) in the coupled diffusion model derived in the preceding paper for a semiconductor quantum well. These include self and mutual DCs in the general two-component case, as well as density- and temperature-related DCs under the single-component approximation. The results are analyzed from the viewpoint of free Fermi gas theory with many-body effects incorporated. We discuss in detail the dependence of these DCs on densities and temperatures in order to identify different roles played by the free carrier contributions including carrier statistics and carrier-LO phonon scattering, and many-body corrections including bandgap renormalization and electron-hole (e-h) scattering. In the general two-component case, it is found that the self- and mutual- diffusion coefficients are determined mainly by the free carrier contributions, but with significant many-body corrections near the critical density. Carrier-LO phonon scattering is dominant at low density, but e-h scattering becomes important in determining their density dependence above the critical electron density. In the single-component case, it is found that many-body effects suppress the density coefficients but enhance the temperature coefficients. The modification is of the order of 10% and reaches a maximum of over 20% for the density coefficients. Overall, temperature elevation enhances the diffusive capability or DCs of carriers linearly, and such an enhancement grows with density. Finally, the complete dataset of various DCs as functions of carrier densities and temperatures provides necessary ingredients for future applications of the model to various spatially inhomogeneous optoelectronic devices.
Reliability prediction techniques
Whittaker, B.; Worthington, B.; Lord, J.F.; Pinkard, D.
1986-01-01
The paper demonstrates the feasibility of applying reliability assessment techniques to mining equipment. A number of techniques are identified and described and examples of their use in assessing mining equipment are given. These techniques include: reliability prediction; failure analysis; design audit; maintainability; availability and the life cycle costing. Specific conclusions regarding the usefulness of each technique are outlined. The choice of techniques depends upon both the type of equipment being assessed and its stage of development, with numerical prediction best suited for electronic equipment and fault analysis and design audit suited to mechanical equipment. Reliability assessments involve much detailed and time consuming work but it has been demonstrated that the resulting reliability improvements lead to savings in service costs which more than offset the cost of the evaluation.
Steven D. Shirk
2017-06-01
Full Text Available The processing of EEG data routinely involves subjective removal of artifacts during a preprocessing stage. Preprocessing inter-rater reliability (IRR and how differences in preprocessing may affect outcomes of primary event-related potential (ERP analyses has not been previously assessed. Three raters independently preprocessed EEG data of 16 cognitively healthy adult participants (ages 18–39 years who performed a memory task. Using intraclass correlations (ICCs, IRR was assessed for Early-frontal, Late-frontal, and Parietal Old/new memory effects contrasts across eight regions of interest (ROIs. IRR was good to excellent for all ROIs; 22 of 26 ICCs were above 0.80. Raters were highly consistent in preprocessing across ROIs, although the frontal pole ROI (ICC range 0.60–0.90 showed less consistency. Old/new parietal effects had highest ICCs with the lowest variability. Rater preprocessing differences did not alter primary ERP results. IRR for EEG preprocessing was good to excellent, and subjective rater-removal of EEG artifacts did not alter primary memory-task ERP results. Findings provide preliminary support for robustness of cognitive/memory task-related ERP results against significant inter-rater preprocessing variability and suggest reliability of EEG to assess cognitive-neurophysiological processes multiple preprocessors are involved.
Rotariu, O; Rezlescu, Nicolae; Murariu, V.; Bădescu, V.
1998-01-01
In this paper we discuss some numerical and experimental results obtained for a magnetic filtration cell with bounded flow field which works in the HGMF-transversal configuration. The numerical results have been obtained by analyzing the particle trajectories in very diluted suspensions, for which the inertia of the particles and the magnetic and hydrodynamic interactions between particles were neglected. The experimental data were obtained by using suspensions of fine particles with magnetic...
Bräutigam, Klaus-Rainer; Jörissen, Juliane; Priefer, Carmen
2014-08-01
The reduction of food waste is seen as an important societal issue with considerable ethical, ecological and economic implications. The European Commission aims at cutting down food waste to one-half by 2020. However, implementing effective prevention measures requires knowledge of the reasons and the scale of food waste generation along the food supply chain. The available data basis for Europe is very heterogeneous and doubts about its reliability are legitimate. This mini-review gives an overview of available data on food waste generation in EU-27 and discusses their reliability against the results of own model calculations. These calculations are based on a methodology developed on behalf of the Food and Agriculture Organization of the United Nations and provide data on food waste generation for each of the EU-27 member states, broken down to the individual stages of the food chain and differentiated by product groups. The analysis shows that the results differ significantly, depending on the data sources chosen and the assumptions made. Further research is much needed in order to improve the data stock, which builds the basis for the monitoring and management of food waste.
U—Series Dating of Fossil Bones：Results from Chinese Sites and Discussions on Its Reliability
沈冠军
1996-01-01
Calculations,according to some open-system models,point out that while a statistically significant discrepancy between the results of two U-series methods,230Th/234U and 227Th/220Th(or 231Pa/235U),attests a relatively recent and important uranium migration,concordant dates cannot guarantee closes-system behavior of sample.The results of 20 fossil bones from 10 Chinese sites,19 of which are determined by two U-series methods,are given,Judging from independent age controls,8 out of the 11 concordant age sets are unacceptable,The results in this paper suggest that uranium may cycle into or out of fossil bones,such geochemical events may take place at any time and no known preserving condition may securely protect them from being affected.So for the sitew we have studied,the U-series dating of fossil bones is of limited reliability.
Heinze, Thomas; Galvan, Boris; Miller, Stephen
2013-04-01
Fluid-rock interactions are mechanically fundamental to many earth processes, including fault zones and hydrothermal/volcanic systems, and to future green energy solutions such as enhanced geothermal systems and carbon capture and storage (CCS). Modeling these processes is challenging because of the strong coupling between rock fracture evolution and the consequent large changes in the hydraulic properties of the system. In this talk, we present results of a numerical model that includes poro-elastic plastic rheology (with hardening, softening, and damage), and coupled to a non-linear diffusion model for fluid pressure propagation and two-phase fluid flow. Our plane strain model is based on the poro- elastic plastic behavior of porous rock and is advanced with hardening, softening and damage using the Mohr- Coulomb failure criteria. The effective stress model of Biot (1944) is used for coupling the pore pressure and the rock behavior. Frictional hardening and cohesion softening are introduced following Vermeer and de Borst (1984) with the angle of internal friction and the cohesion as functions of the principal strain rates. The scalar damage coefficient is assumed to be a linear function of the hardening parameter. Fluid injection is modeled as a two phase mixture of water and air using the Richards equation. The theoretical model is solved using finite differences on a staggered grid. The model is benchmarked with experiments on the laboratory scale in which fluid is injected from below in a critically-stressed, dry sandstone (Stanchits et al. 2011). We simulate three experiments, a) the failure a dry specimen due to biaxial compressive loading, b) the propagation a of low pressure fluid front induced from the bottom in a critically stressed specimen, and c) the failure of a critically stressed specimen due to a high pressure fluid intrusion. Comparison of model results with the fluid injection experiments shows that the model captures most of the experimental
Farrar, John T; Troxel, Andrea B; Stott, Colin; Duncombe, Paul; Jensen, Mark P
2008-05-01
The measurement of spasticity as a symptom of neurologic disease is an area of growing interest. Clinician-rated measures of spasticity purport to be objective but do not measure the patient's experience and may not be sensitive to changes that are meaningful to the patient. In a patient with clinical spasticity, the best judge of the perceived severity of the symptom is the patient. The aim of this study was to assess the validity and reliability, and determine the clinical importance, of change on a 0-10 numeric rating scale (NRS) as a patient-rated measure of the perceived severity of spasticity. Using data from a large,randomized, doubleblind, placebo-controlled study of an endocannabinoid system modulator in patients with multiple sclerosis-related spasticity, we evaluated the test-retest reliability and comparison-based validity of a patient-reported 0-10 NRS measure of spasticity severity with the Ashworth Scale and Spasm Frequency Scale. We estimated the level of change from baseline on the 0-10 NRS spasticity scale that constituted a clinically important difference (CID) and a minimal CID (MCID) as anchored to the patient's global impression of change (PGIC). Data from a total of 189 patients were included in this assessment (114 women, 75 men; mean age, 49.1 years). The test-retest reliability analysis found an interclass correlation coefficient of 0.83 (P change on 0-10 NRS and change in the Spasm Frequency Scale (r = 0.63; P change on 0-10 NRS and the PGIC (r = 0.47; P change of 18% the MCID. The measurement of the symptom of spasticity using a patient-rated 0-10 NRS was found to be both reliable and valid. The definitions of CID and MCID will facilitate the use of appropriate responder analyses and help clinicians interpret the significance of future results.
Water-waves on linear shear currents. A comparison of experimental and numerical results.
Simon, Bruno; Seez, William; Touboul, Julien; Rey, Vincent; Abid, Malek; Kharif, Christian
2016-04-01
Propagation of water waves can be described for uniformly sheared current conditions. Indeed, some mathematical simplifications remain applicable in the study of waves whether there is no current or a linearly sheared current. However, the widespread use of mathematical wave theories including shear has rarely been backed by experimental studies of such flows. New experimental and numerical methods were both recently developed to study wave current interactions for constant vorticity. On one hand, the numerical code can simulate, in two dimensions, arbitrary non-linear waves. On the other hand, the experimental methods can be used to generate waves with various shear conditions. Taking advantage of the simplicity of the experimental protocol and versatility of the numerical code, comparisons between experimental and numerical data are discussed and compared with linear theory for validation of the methods. ACKNOWLEDGEMENTS The DGA (Direction Générale de l'Armement, France) is acknowledged for its financial support through the ANR grant N° ANR-13-ASTR-0007.
Arnol'd tongues for a resonant injection-locked frequency divider: analytical and numerical results
Bartuccelli, Michele; Deane, Jonathan H.B.; Gentile, Guido;
2010-01-01
In this paper we consider a resonant injection-locked frequency divider which is of interest in electronics, and we investigate the frequency locking phenomenon when varying the amplitude and frequency of the injected signal. We study both analytically and numerically the structure of the Arnol’d...
Marom, Gil; Bluestein, Danny
2016-01-01
This paper evaluated the influence of various numerical implementation assumptions on predicting blood damage in cardiovascular devices using Lagrangian methods with Eulerian computational fluid dynamics. The implementation assumptions that were tested included various seeding patterns, stochastic walk model, and simplified trajectory calculations with pathlines. Post processing implementation options that were evaluated included single passage and repeated passages stress accumulation and ti...
Sathyachandran, S. K.; Roy, D. P.; Boschetti, L.
2014-12-01
The Fire Radiative Power (FRP) [MW] is a measure of the rate of biomass combustion and can be retrieved from ground based and satellite observations using middle infra-red measurements. The temporal integral of FRP is the Fire Radiative Energy (FRE) [MJ] and is related linearly to the total biomass consumption and so pyrogenic emissions. Satellite derived biomass consumption and emissions estimates have been derived conventionally by computing the summed total FRP, or the average FRP (arithmetic average of FRP retrievals), over spatial geographic grids for fixed time periods. These two methods are prone to estimation bias, especially under irregular sampling conditions such as provided by polar-orbiting satellites, because the FRP can vary rapidly in space and time as a function of the fire behavior. Linear temporal integration of FRP taking into account when the FRP values were observed and using the trapezoidal rule for numerical integration has been suggested as an alternate FRE estimation method. In this study FRP data measured rapidly with a dual-band radiometer over eight prescribed fires are used to compute eight FRE values using the sum, mean and trapezoidal estimation approaches under a variety of simulated irregular sampling conditions. The estimated values are compared to biomass consumed measurements for each of the eight fires to provide insights into which method provides more accurate and precise biomass consumption estimates. The three methods are also applied to continental MODIS FRP data to study their differences using polar orbiting satellite data. The research findings indicate that trapezoidal FRP numerical integration provides the most reliable estimator.
Yamada, T.
1978-01-01
Cooling ponds receive large amounts of waste heat from industrial sources and release the heat to the atmosphere. These large area sources of warm and moist air may have significant inadvertent effects. This paper is a preliminary step in the development of a method for estimating the perturbations in the atmosphere produced by a cooling pond. A three-dimensional numerical model based on turbulence second-moment closure equations and Gaussian cloud relations has been developed. A simplified version of the model, in which only turbulent energy and length-scale equations are solved prognostically, is used. Numerical simulations are conducted using as boundary conditions the data from a cooling pond study conducted in northern Illinois during the winter of 1976-1977. Preliminary analyses of these simulations indicate that formation of clouds over a cooling pond is sensitive to the moisture content in the ambient atmosphere.
A model of modulated diffusion. II. Numerical results on statistical properties
Bazzani, A.; Siboni, S.; Turchetti, G. [dell`Universita Bologna (Italy)] [and others
1994-08-01
We investigate numerically the statistical properties of a model of modulated diffusion for which we have already computed analytically the diffusion coefficient D. Our model is constructed by adding a deterministic or random noise to the frequency of an integrable isochronous system. We consider in particular the central limit theorem and the invariance principle and we show that they follow whenever D is positive and for any magnitude of the noise; we also investigate the asymptotic distribution in a case when D=0.
The Dynamics of Nonequilibrium Transitions Induced By the Cross-Correlated Noises: Numerical Results
A.N. Vitrenko
2010-01-01
Full Text Available The dynamic system described by the Langevin equation with two cross-correlated Gaussian white noises is considered. The non-equilibrium probability distribution function of the system is calculated by the numerical methods. The time of change of the initially unimodal distribution to the bimodal one is determined for different values of the control parameter. A critical slowing down in the transition dynamics is demonstrated.
Chaotic structures of nonlinear magnetic fields. I - Theory. II - Numerical results
Lee, Nam C.; Parks, George K.
1992-01-01
A study of the evolutionary properties of nonlinear magnetic fields in flowing MHD plasmas is presented to illustrate that nonlinear magnetic fields may involve chaotic dynamics. It is shown how a suitable transformation of the coupled equations leads to Duffing's form, suggesting that the behavior of the general solution can also be chaotic. Numerical solutions of the nonlinear magnetic field equations that have been cast in the form of Duffing's equation are presented.
ZHANG Zhe; ZHANG Gui-Zhong; XIANG Wang-Kua; W. T. Hill
2006-01-01
We present a numerical result of photoionization rate for the one-dimensional molecular hydrogen ion model exposed to intense light of 1×1016-2×1016 W/cm2, 55-as pulse duration, and 800nm wavelength. In contrast to the previous calculation result of charge-resonance-enhanced ionization for lower intensity and much longer pulse, our result exhibits an ionization saturation. The numerical results are interpreted in the field-dressed potential picture as over-the-barrier liberation of electrons. This extremely short pulsewidth and relatively high field phenomenon requests experimental demonstration.
Joanna E Klopotowska
Full Text Available BACKGROUND: Older patients are at high risk for experiencing Adverse Drug Events (ADEs during hospitalization. To be able to reduce ADEs in these vulnerable patients, hospitals first need to measure the occurrence of ADEs, especially those that are preventable. However, data on preventable ADEs (pADEs occurring during hospitalization in older patients are scarce, and no 'gold standard' for the identification of ADEs exists. METHODOLOGY: The study was conducted in three hospitals in the Netherlands in 2007. ADEs were retrospectively identified by a team of experts using a comprehensive and structured patient chart review (PCR combined with a trigger-tool as an aid. This ADE identification strategy was applied to a cohort of 250 older hospitalized patients. To estimate the intra- and inter-rater reliabilities, Cohen's kappa values were calculated. PRINCIPAL FINDINGS: In total, 118 ADEs were detected which occurred in 62 patients. This ADE yield was 1.1 to 2.7 times higher in comparison to other ADE studies in older hospitalized patients. Of the 118 ADEs, 83 (70.3% were pADEs; 51 pADEs (43.2% of all ADEs identified caused serious patient harm. Patient harm caused by ADEs resulted in various events. The overall intra-rater agreement of the developed strategy was substantial (κ = 0.74; the overall inter-rater agreement was only fair (κ = 0.24. CONCLUSIONS/SIGNIFICANCE: The ADE identification strategy provided a detailed insight into the scope of ADEs occurring in older hospitalized patients, and showed that the majority of (serious ADEs can be prevented. Several strategy related aspects, as well as setting/study specific aspects, may have contributed to the results gained. These aspects should be considered whenever ADE measurements need to be conducted. The results regarding pADEs can be used to design tailored interventions to effectively reduce harm caused by medication errors. Improvement of the inter-rater reliability of a PCR remains
Jay C Fournier
Full Text Available Functional Magnetic Resonance Imagine (fMRI is an important assessment tool in longitudinal studies of mental illness and its treatment. Understanding the psychometric properties of fMRI-based metrics, and the factors that influence them, will be critical for properly interpreting the results of these efforts. The current study examined whether the choice among alternative model specifications affects estimates of test-retest reliability in key emotion processing regions across a 6-month interval. Subjects (N = 46 performed an emotional-faces paradigm during fMRI in which neutral faces dynamically morphed into one of four emotional faces. Median voxelwise intraclass correlation coefficients (mvICCs were calculated to examine stability over time in regions showing task-related activity as well as in bilateral amygdala. Four modeling choices were evaluated: a default model that used the canonical hemodynamic response function (HRF, a flexible HRF model that included additional basis functions, a modified CompCor (mCompCor model that added corrections for physiological noise in the global signal, and a final model that combined the flexible HRF and mCompCor models. Model residuals were examined to determine the degree to which each pipeline met modeling assumptions. Results indicated that the choice of modeling approaches impacts both the degree to which model assumptions are met and estimates of test-retest reliability. ICC estimates in the visual cortex increased from poor (mvICC = 0.31 in the default pipeline to fair (mvICC = 0.45 in the full alternative pipeline - an increase of 45%. In nearly all tests, the models with the fewest assumption violations generated the highest ICC estimates. Implications for longitudinal treatment studies that utilize fMRI are discussed.
Fanselau, R.W.; Thakkar, J.G.; Hiestand, J.W.; Cassell, D.
1981-03-01
The Comparative Thermal-Hydraulic Evaluation of Steam Generators program represents an analytical investigation of the thermal-hydraulic characteristics of four PWR steam generators. The analytical tool utilized in this investigation is the CALIPSOS code, a three-dimensional flow distribution code. This report presents the steady state thermal-hydraulic characteristics on the secondary side of a Westinghouse Model 51 steam generator. Details of the CALIPSOS model with accompanying assumptions, operating parameters, and transport correlations are identified. Comprehensive graphical and numerical results are presented to facilitate the desired comparison with other steam generators analyzed by the same flow distribution code.
De Marco, Rossana; Marcucci, Maria Federica; Brienza, Daniele; Bruno, Roberto; Consolini, Giuseppe; Perrone, Denise; Valentini, Franceso; Servidio, Sergio; Stabile, Sara; Pezzi, Oreste; Sorriso-Valvo, Luca; Lavraud, Benoit; De Keyser, Johan; Retinò, Alessandro; Fazakerley, Andrew; Wicks, Robert; Vaivads, Andris; Salatti, Mario; Veltri, Pierliugi
2017-04-01
Turbulence Heating ObserveR (THOR) is the first mission devoted to study energization, acceleration and heating of turbulent space plasmas, and designed to perform field and particle measurements at kinetic scales in different near-Earth regions and in the solar wind. Solar Orbiter (SolO), together with Solar Probe Plus, will provide the first comprehensive remote and in situ measurements which are critical to establish the fundamental physical links between the Sun's dynamic atmosphere and the turbulent solar wind. The fundamental process of turbulent dissipation is mediated by physical mechanism that occur at a variety of temporal and spatial scales, and most efficiently at the kinetics scales. Hybrid Vlasov-Maxwell simulations of solar-wind turbulence show that kinetic effects manifest as particle beams, production of temperature anisotropies and ring-like modulations, preferential heating of heavy ions. We use a numerical code able to reproduce the response of a typical electrostatic analyzer of top-hat type starting from velocity distribution functions (VDFs) generated by Hybrid Vlasov-Maxwell (HVM) numerical simulations. Here, we show how optimized particle measurements by top-hat analysers can capture the kinetic features injected by turbulence in the VDFs.
Nonlinear instability and chaos in plasma wave-wave interactions. II. Numerical methods and results
Kueny, C.S.; Morrison, P.J.
1995-05-01
In Part I of this work and Physics of Plasmas, June 1995, the behavior of linearly stable, integrable systems of waves in a simple plasma model was described using a Hamiltonian formulation. It was shown that explosive instability arises from nonlinear coupling between modes of positive and negative energy, with well-defined threshold amplitudes depending on the physical parameters. In this concluding paper, the nonintegrable case is treated numerically. Several sets of waves are considered, comprising systems of two and three degrees of freedom. The time evolution is modelled with an explicit symplectic integration algorithm derived using Lie algebraic methods. When initial wave amplitudes are large enough to support two-wave decay interactions, strongly chaotic motion destroys the separatrix bounding the stable region for explosive triplets. Phase space orbits then experience diffusive growth to amplitudes that are sufficient for explosive instability, thus effectively reducing the threshold amplitude. For initial amplitudes too small to drive decay instability, small perturbations might still grow to arbitrary size via Arnold diffusion. Numerical experiments do not show diffusion in this case, although the actual diffusion rate is probably underestimated due to the simplicity of the model.
van Iterson, Loretta; Augustijn, Paul B.; de Jong, Peter F.; van der Leij, Aryan
2013-01-01
The goal of this study was to investigate reliable cognitive change in epilepsy by developing computational procedures to determine reliable change index scores (RCIs) for the Dutch Wechsler Intelligence Scales for Children. First, RCIs were calculated based on stability coefficients from a reference sample. Then, these RCIs were applied to a…
van Iterson, L.; Augustijn, P.B.; de Jong, P.F.; van der Leij, A.
2013-01-01
The goal of this study was to investigate reliable cognitive change in epilepsy by developing computational procedures to determine reliable change index scores (RCIs) for the Dutch Wechsler Intelligence Scales for Children. First, RCIs were calculated based on stability coefficients from a referenc
van Iterson, Loretta; Augustijn, Paul B.; de Jong, Peter F.; van der Leij, Aryan
2013-01-01
The goal of this study was to investigate reliable cognitive change in epilepsy by developing computational procedures to determine reliable change index scores (RCIs) for the Dutch Wechsler Intelligence Scales for Children. First, RCIs were calculated based on stability coefficients from a reference sample. Then, these RCIs were applied to a…
Basu, Asit P; Basu, Sujit K
1998-01-01
This volume presents recent results in reliability theory by leading experts in the world. It will prove valuable for researchers, and users of reliability theory. It consists of refereed invited papers on a broad spectrum of topics in reliability. The subjects covered include Bayesian reliability, Bayesian reliability modeling, confounding in a series system, DF tests, Edgeworth approximation to reliability, estimation under random censoring, fault tree reduction for reliability, inference about changes in hazard rates, information theory and reliability, mixture experiment, mixture of Weibul
Blecka, Maria I.
2010-05-01
The passive remote spectrometric methods are important in examinations the atmospheres of planets. The radiance spectra inform us about values of thermodynamical parameters and composition of the atmospheres and surfaces. The spectral technology can be useful in detection of the trace aerosols like biological substances (if present) in the environments of the planets. We discuss here some of the aspects related to the spectroscopic search for the aerosols and dust in planetary atmospheres. Possibility of detection and identifications of biological aerosols with a passive InfraRed spectrometer in an open-air environment is discussed. We present numerically simulated, based on radiative transfer theory, spectroscopic observations of the Earth atmosphere. Laboratory measurements of transmittance of various kinds of aerosols, pollens and bacterias were used in modeling.
Distribution of Steps with Finite-Range Interactions: Analytic Approximations and Numerical Results
GonzáLez, Diego Luis; Jaramillo, Diego Felipe; TéLlez, Gabriel; Einstein, T. L.
2013-03-01
While most Monte Carlo simulations assume only nearest-neighbor steps interact elastically, most analytic frameworks (especially the generalized Wigner distribution) posit that each step elastically repels all others. In addition to the elastic repulsions, we allow for possible surface-state-mediated interactions. We investigate analytically and numerically how next-nearest neighbor (NNN) interactions and, more generally, interactions out to q'th nearest neighbor alter the form of the terrace-width distribution and of pair correlation functions (i.e. the sum over n'th neighbor distribution functions, which we investigated recently.[2] For physically plausible interactions, we find modest changes when NNN interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.
Sørensen, Jens Nørkær; Gelfgat, A. Yu; Naumov, I. V.;
2009-01-01
The three-dimensional axisymmetry-breaking instability of axisymmetric flow between a rotating lid and a stationary cylinder is analyzed both numerically and experimentally for the case of tall cylinders with the height/radius aspect ratio between 3.3 and 5.5. A complete stability diagram...... for each mode. The onset of three-dimensional flow behavior is measured by combining the high spatial resolution of particle image velocimetry and the temporal accuracy of laser Doppler anemometry. The results are compared to the numerical stability analysis. The measured onset of three dimensionality...... is in a good agreement with the numerical results. Disagreements observed in supercritical regimes can be explained by secondary bifurcations that are not accounted for by linear stability analysis of the primary base flow. ©2009 American Institute of Physics...
戈道川; 杨燕华; 张若兴; 丑强
2015-01-01
To analyze the reliability of safety system having multi‐failure behavior ,such as sequence‐,redundancy‐ and function‐dependent failure behaviors ,in nuclear power plant ,a dynamic fault tree model based on numerical simulation approach was proposed in this paper .It is implemented to analyze the reliability of safety system having multi‐failure behavior in nuclear power reactor through randomly simulating the multi‐failure behavior of component and judging the success rule of dynamic logic gate .T he results of the case study indicate the proposed method is applicable for evaluating the reliability of complicated system with multi‐failure behavior ,and offers great generality .%为分析含有顺序、冗余及功能相关等多失效行为的核电厂安全系统的可靠性，提出了基于动态故障树模型的可靠性数值仿真方法。通过对部件多失效行为的随机模拟及动态逻辑门成功准则的判定，实现了对含有多失效行为的核电厂安全系统的可靠性数值模拟。案例分析结果表明，该方法能对多失效行为的复杂系统进行可靠性分析，具有较强的适应性。
Klopotowska, Joanna E.; Wierenga, Peter C.; Stuijt, Clementine C. M.; Arisz, Lambertus; Dijkgraaf, Marcel G. W.; Kuks, Paul F. M.; Asscheman, Henk; de Rooij, Sophia E.; Lie-A-Huen, Loraine; Smorenburg, Susanne M.
2013-01-01
Background Older patients are at high risk for experiencing Adverse Drug Events (ADEs) during hospitalization. To be able to reduce ADEs in these vulnerable patients, hospitals first need to measure the occurrence of ADEs, especially those that are preventable. However, data on preventable ADEs (pADEs) occurring during hospitalization in older patients are scarce, and no ‘gold standard’ for the identification of ADEs exists. Methodology The study was conducted in three hospitals in the Netherlands in 2007. ADEs were retrospectively identified by a team of experts using a comprehensive and structured patient chart review (PCR) combined with a trigger-tool as an aid. This ADE identification strategy was applied to a cohort of 250 older hospitalized patients. To estimate the intra- and inter-rater reliabilities, Cohen’s kappa values were calculated. Principal Findings In total, 118 ADEs were detected which occurred in 62 patients. This ADE yield was 1.1 to 2.7 times higher in comparison to other ADE studies in older hospitalized patients. Of the 118 ADEs, 83 (70.3%) were pADEs; 51 pADEs (43.2% of all ADEs identified) caused serious patient harm. Patient harm caused by ADEs resulted in various events. The overall intra-rater agreement of the developed strategy was substantial (κ = 0.74); the overall inter-rater agreement was only fair (κ = 0.24). Conclusions/Significance The ADE identification strategy provided a detailed insight into the scope of ADEs occurring in older hospitalized patients, and showed that the majority of (serious) ADEs can be prevented. Several strategy related aspects, as well as setting/study specific aspects, may have contributed to the results gained. These aspects should be considered whenever ADE measurements need to be conducted. The results regarding pADEs can be used to design tailored interventions to effectively reduce harm caused by medication errors. Improvement of the inter-rater reliability of a PCR remains
Poklad, A.; Pal, J.; Galindo, V.; Grants, I.; Heinze, V.; Meier, D.; Pätzold, O.; Stelter, M.; Gerbeth, G.
2017-07-01
A novel, vertical Bridgman-type technique for growing multi-crystalline silicon ingots in an induction furnace is described. In contrast to conventional growth, a modified setup with a cone-shaped crucible and susceptor is used. A detailed numerical simulation of the setup is presented. It includes a global thermal simulation of the furnace and a local simulation of the melt, which aims at the influence of the melt flow on the temperature and concentration fields. Furthermore, seeded growth of cone-shaped Si ingots using either a monocrystalline seed or a seed layer formed by pieces of poly-Si is demonstrated and compared to growth without seeds. The influences of the seed material on the grain structure and the dislocation density of the ingots are discussed. The second part addresses model experiments for the Czochralski technique using the room temperature liquid metal GaInSn. The studies were focused on the influence of a rotating and a horizontally static magnetic field on the melt flow and the related heat transport in crucibles being heated from bottom and/or side, and cooled by a crystal model covering about 1/3 of the upper melt surface.
Nitric oxide emissions from a coal-fueled engine: Numerical results
Caton, J.A.; Schmidt, J.; Roth, J.; Bachman, F.
1988-01-01
A cycle simulation for coal-fueled, reciprocating, internal combustion engines has been expanded to include calculations of nitric oxide exhaust emissions. Calculations have been completed for a diesel oil and a coal-water slurry fuel. The fuels were assumed to be direct injected and compression ignited. The numerical simulation was based on a thermodynamic analysis with models for the injection, ignition, mixing, combustion, and heat transfer. The calculations of the nitric oxide formation and reduction reactions were based on the Zel'dovich mechanism. The engine performance parameters were in good agreement with published values in the literature. The computed exhaust nitric oxide concentrations for both the diesel and coal-water slurry fuels were in fair agreement with recent preliminary experimental values from the literature. In general, the exhaust nitric oxide concentrations were lower for the coal-water slurry fuel relative to the diesel fuel. The thermal nitric oxide production for the coal-water slurry fuel was a strong function of the coal/water mass ratio for the conditions examined. Also, rough estimates indicated that the nitric oxide from fuel-bound nitrogen could be significant for typical coal-water slurry fuels.
Alastuey, A. [Laboratoire de Physique, ENS Lyon, CNRS, Lyon (France); Ballenegger, V. [Institut UTINAM, Universite de Franche-Comte, CNRS, Besancon (France)
2010-01-15
We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first.ve leading corrections to the ideal Saha equation of state have been derived[A. Alastuey, V. Ballenegger et al., J. Stat. Phys. 130, 1119 (2008)]. Those corrections account for all effects of interactions and thermal excitations up to order exp(E{sub H} /kT) included, where E{sub H} {approx_equal} -13.6 eV is the ground state energy of the hydrogen atom. Among the.ve leading corrections, three are easy to evaluate, while the remaining ones involve suitably truncated internal partition functions of H{sub 2} molecules and H{sup -} and H{sub 2}{sup +} ions, for which no analytical formulae are available in closed form. We estimate those partitions functions at.nite temperature via a simple phenomenology based on known values of rotational and vibrational energies. This allows us to compute numerically the leading deviations to the Saha pressure along several isotherms and isochores. Our values are compared with those of the OPAL tables (for pure hydrogen) calculated within the ACTEX method (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Porch, W.M.; Lange, R.
1982-11-01
Recent studies in The Geysers region of Northern California have concentrated on drainage wind effects on tracer transport and diffusion in complex terrain, as part of the Atmospheric Studies in Complex Terrain (ASCOT) project. These studies combined tracer measurements, conventional tower and remote sensing meteorological measurements, and numerical wind field transport and diffusion models. One part of the meteorological measurement support used eight optical cross-path wind sensors across the principle air drainage valleys. These sensors had varying optical path lengths within the drainage layer of approx. 300 m to 3 km. Results of this study indicate that the combination of spatially averaged cross-path optical wind sensor and conventional tower mounted cup-vane anemometer data into a numerical plume transport and diffusion model for complex terrain has provided useful results. The most important of these results is an independent measure of wind data on a spatial scale compatible with necessarily large grid scales in numerical wind field models with topography. This allows assessment of terrain associated exposure problems for tower anemometers in complex terrain. The optical cross wind data can be used to compare necessary averaging times, and spatial distribution of point sensors and provide verification data to improve the logistics of instrument placement in combination with numerical models.
Reliability estimation using kriging metamodel
Cho, Tae Min; Ju, Byeong Hyeon; Lee, Byung Chai [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Jung, Do Hyun [Korea Automotive Technology Institute, Chonan (Korea, Republic of)
2006-08-15
In this study, the new method for reliability estimation is proposed using kriging metamodel. Kriging metamodel can be determined by appropriate sampling range and sampling numbers because there are no random errors in the Design and Analysis of Computer Experiments(DACE) model. The first kriging metamodel is made based on widely ranged sampling points. The Advanced First Order Reliability Method(AFORM) is applied to the first kriging metamodel to estimate the reliability approximately. Then, the second kriging metamodel is constructed using additional sampling points with updated sampling range. The Monte-Carlo Simulation(MCS) is applied to the second kriging metamodel to evaluate the reliability. The proposed method is applied to numerical examples and the results are almost equal to the reference reliability.
Leblanc, James
In this talk we present numerical results for ground state and excited state properties (energies, double occupancies, and Matsubara-axis self energies) of the single-orbital Hubbard model on a two-dimensional square lattice. In order to provide an assessment of our ability to compute accurate results in the thermodynamic limit we employ numerous methods including auxiliary field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock. We illustrate cases where agreement between different methods is obtained in order to establish benchmark results that should be useful in the validation of future results.
Timmel, K.; Kratzsch, C.; Asad, A.; Schurmann, D.; Schwarze, R.; Eckert, S.
2017-07-01
The present paper reports about numerical simulations and model experiments concerned with the fluid flow in the continuous casting process of steel. This work was carried out in the LIMMCAST project in the framework of the Helmholtz alliance LIMTECH. A brief description of the LIMMCAST facilities used for the experimental modeling at HZDR is given here. Ultrasonic and inductive techniques and the X-ray radioscopy were employed for flow measurements or visualizations of two-phase flow regimes occurring in the submerged entry nozzle and the mold. Corresponding numerical simulations were performed at TUBAF taking into account the dimensions and properties of the model experiments. Numerical models were successfully validated using the experimental data base. The reasonable and in many cases excellent agreement of numerical with experimental data allows to extrapolate the models to real casting configurations. Exemplary results will be presented here showing the effect of electromagnetic brakes or electromagnetic stirrers on the flow in the mold or illustrating the properties of two-phase flows resulting from an Ar injection through the stopper rod.
Image restoration by the method of convex projections: part 2 applications and numerical results.
Sezan, M I; Stark, H
1982-01-01
The image restoration theory discussed in a previous paper by Youla and Webb [1] is applied to a simulated image and the results compared with the well-known method known as the Gerchberg-Papoulis algorithm. The results show that the method of image restoration by projection onto convex sets, by providing a convenient technique for utilizing a priori information, performs significantly better than the Gerchberg-Papoulis method.
Multi-Country Experience in Delivering a Joint Course on Software Engineering--Numerical Results
Budimac, Zoran; Putnik, Zoran; Ivanovic, Mirjana; Bothe, Klaus; Zdravkova, Katerina; Jakimovski, Boro
2014-01-01
A joint course, created as a result of a project under the auspices of the "Stability Pact of South-Eastern Europe" and DAAD, has been conducted in several Balkan countries: in Novi Sad, Serbia, for the last six years in several different forms, in Skopje, FYR of Macedonia, for two years, for several types of students, and in Tirana,…
Kirchner, R; Montvay, István; Spanderen, K; Westphalen, J
1999-01-01
We report on our experience with the two-step multi-bosonic algorithm in a large scale Monte Carlo simulation of the SU(2) Yang-Mills theory with dynamical gluinos. First results are described on the low lying spectrum of bound states, the string tension and the gluino condensate.
Kirchner, R.; Luckmann, S.; Montvay, I.; Spanderen, K.; Westphalen, J
1999-03-01
We report on our experience with the two-step multi-bosonic algorithm in a large scale Monte Carlo simulation of the SU(2) Yang-Mills theory with dynamical gluinos. First results are described on the low lying spectrum of bound states, the string tension and the gluino condensate.
An Alternative Approach for Determining Photoionization Rate in H2+: Numerical Results
ZHOU Yu; ZHANG Gui-Zhong; XIANG Wang-Hua; W.T. Hill Ⅲ
2005-01-01
@@ We present an alternative approach for determining the photoionization rate of hydrogen molecules under the interaction of intense light, by calculating the spatial overlap integral between the potential function and the time-dependent wavefunction. The suggested method was applied to varying excitation pulse shapes: square envelope and chirped hyperbolic secant envelope. The computed results confirmed that our method was robust and could be extended to general molecular dynamics calculations.
Pourabdian, Majid; Morad, Mohammad Reza; Javareshkian, Alireza
2016-01-01
This paper considers the influence of nanoparticles on the nonlinear Jeffery-Hamel flow problem. Investigation is performed for three types of nanoparticles namely copper Cu, alumina Al2O3 and titania TiO2 by considering water as a base fluid. The resulting nonlinear governing equations and their associated boundary conditions are solved for both semi-analytical and numerical solutions. The semi-analytical solution is developed by using Homotopy Perturbation Method (HPM) whereas the numerical solution is presented by Runge-Kutta scheme. Dimensionless velocity, temperature, skin friction coefficient and Nusselt number are addressed for the involved pertinent parameters. It is observed that the influence of solid volume fraction of nanoparticles on the heat transfer and fluid flow parameters is more noticeable when compared with the type of nanoparticles. The achieved results reveal that HPM is very effective, convenient and accurate for this problem.
Mikulović Jovan Č.
2014-01-01
Full Text Available A methodology for calculation of overvoltages in transformer windings, based on a numerical method of inverse Laplace transform, is presented. Mathematical model of transformer windings is described by partial differential equations corresponding to distributed parameters electrical circuits. The procedure of calculating overvoltages is applied to windings having either isolated neutral point, or grounded neutral point, or neutral point grounded through impedance. A comparative analysis of the calculation results obtained by the proposed numerical method and by analytical method of calculation of overvoltages in transformer windings is presented. The results computed by the proposed method and measured voltage distributions, when a voltage surge is applied to a three-phase 30 kVA power transformer, are compared. [Projekat Ministartsva nauke Republike Srbije, br. TR-33037 i br. TR-33020
A. C. Silva; Bourles, B; Araujo, M
2009-01-01
High resolution hydrographic observations of temperature and salinity are used to analyse the subsurface circulation along the coast of North Brazil, off the Amazon mouth, between 2° S and 6° N. Observations are presented from four cruises carried out in different periods of the year (March–May 1995, May–June 1999, July–August 2001 and October–November 1997). Numerical model outputs complement the results of the shipboard measurements, and are used to complete the descriptions...
Wang, Zhan-Shan; Pan, Li-Bo
2014-03-01
The emission inventory of air pollutants from the thermal power plants in the year of 2010 was set up. Based on the inventory, the air quality of the prediction scenarios by implementation of both 2003-version emission standard and the new emission standard were simulated using Models-3/CMAQ. The concentrations of NO2, SO2, and PM2.5, and the deposition of nitrogen and sulfur in the year of 2015 and 2020 were predicted to investigate the regional air quality improvement by the new emission standard. The results showed that the new emission standard could effectively improve the air quality in China. Compared with the implementation results of the 2003-version emission standard, by 2015 and 2020, the area with NO2 concentration higher than the emission standard would be reduced by 53.9% and 55.2%, the area with SO2 concentration higher than the emission standard would be reduced by 40.0%, the area with nitrogen deposition higher than 1.0 t x km(-2) would be reduced by 75.4% and 77.9%, and the area with sulfur deposition higher than 1.6 t x km(-2) would be reduced by 37.1% and 34.3%, respectively.
Numerical results for near surface time domain electromagnetic exploration: a full waveform approach
Sun, H.; Li, K.; Li, X., Sr.; Liu, Y., Sr.; Wen, J., Sr.
2015-12-01
Time domain or Transient electromagnetic (TEM) survey including types with airborne, semi-airborne and ground play important roles in applicants such as geological surveys, ground water/aquifer assess [Meju et al., 2000; Cox et al., 2010], metal ore exploration [Yang and Oldenburg, 2012], prediction of water bearing structures in tunnels [Xue et al., 2007; Sun et al., 2012], UXO exploration [Pasion et al., 2007; Gasperikova et al., 2009] etc. The common practice is introducing a current into a transmitting (Tx) loop and acquire the induced electromagnetic field after the current is cut off [Zhdanov and Keller, 1994]. The current waveforms are different depending on instruments. Rectangle is the most widely used excitation current source especially in ground TEM. Triangle and half sine are commonly used in airborne and semi-airborne TEM investigation. In most instruments, only the off time responses are acquired and used in later analysis and data inversion. Very few airborne instruments acquire the on time and off time responses together. Although these systems acquire the on time data, they usually do not use them in the interpretation.This abstract shows a novel full waveform time domain electromagnetic method and our recent modeling results. The benefits comes from our new algorithm in modeling full waveform time domain electromagnetic problems. We introduced the current density into the Maxwell's equation as the transmitting source. This approach allows arbitrary waveforms, such as triangle, half-sine, trapezoidal waves or scatter record from equipment, being used in modeling. Here, we simulate the establishing and induced diffusion process of the electromagnetic field in the earth. The traditional time domain electromagnetic with pure secondary fields can also be extracted from our modeling results. The real time responses excited by a loop source can be calculated using the algorithm. We analyze the full time gates responses of homogeneous half space and two
Numerical and Experimental Results of a Passive Free Yawing Downwind Wind Turbine
Verelst, David Robert; Van Wingerden, Jan-Willem
The background of this PhD study concerns a medium sized 3 bladed wind turbine in a free yawing and downwind configuration. Largely funded by an EU Marie-Curie IAPP grant, the project was jointly setup by the renewable energy consultant 3E, DTU Wind Energy and the TU Delft. The 3 bladed free yawing...... downwind concept is pursued in an attempt to increase the robustness of a wind turbine by eliminating the traditionally actively controlled, and sometimes failure prone yawing mechanism. Under certain conditions, such as for remote (off shore) and off grid applications, a decreased failure rate can...... increase the economical competitiveness significantly compared to more traditional power supplies. This work presents aeroelastic analysis and results of a wind tunnel test campaign for the 3 bladed free yawing downwind concept. The investigated topics concern free yawing stability and how it is affected...
Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results
Hou, Lu-Jing; Shukla, P K
2008-01-01
We perform Brownian dynamics simulations for studying the self-diffusion in two-dimensional (2D) dusty plasma liquids, in terms of both mean-square displacement and velocity autocorrelation function (VAF). Super-diffusion of charged dust particles has been observed to be most significant at infinitely small damping rate $\\gamma$ for intermediate coupling strength, where the long-time asymptotic behavior of VAF is found to be the product of $t^{-1}$ and $\\exp{(-\\gamma t)}$. The former represents the prediction of early theories in 2D simple liquids and the latter the VAF of a free Brownian particle. This leads to a smooth transition from super-diffusion to normal diffusion, and then to sub-diffusion with an increase of the damping rate. These results well explain the seemingly contradictory scattered in recent classical molecular dynamics simulations and experiments of dusty plasmas.
Preliminary results from a numerical study on the appendix gap losses in a Stirling engine
Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove
2005-01-01
with different algorithms for computing the heat transfer in the gap. The results showed higher losses for small gap sizes but smaller losses for large gap sizes when compared to analytical expressions for the appendix gap losses. The appendix gap losses were found to influence both the heat intake and work......Analytical expressions for the losses in the displacer clearance gap, a.k.a. the appendix gap, have been refined during the last decades. But most real life Stirling engines violate the assumptions behind these expressions and hence the expressions may not be applicable. In this study the gap has...... been included directly into a one dimensional Stirling engine model. Practical aspects of the method, such as handling the moving wall in the gap while achieving an energy conserving model formulation and handling discontinuous derivatives in the equations, are discussed. A study on the convergence...
Multi-Country Experience in Delivering a Joint Course on Software Engineering – Numerical Results
Zoran Budimac1, 1, 1, 2, 3, and 3
2014-02-01
Full Text Available A joint course, created as a result of a project under the auspices of the ‘Stability Pact of South-Eastern Europe’ and DAAD, has been conducted in several Balkan countries: in Novi Sad, Serbia, for the last six years in several different forms, in Skopje, FYR of Macedonia, for two years, for several types of students, and in Tirana, Albania, in the form of a crash, seven-day course, for the last two years. In this paper, we will put an emphasis on the assessment methods used within these courses, and compare them with the ‘original’ course that has been conducted at the Humboldt University in Berlin for almost a decade. Having a good environment for comparisons we draw some conclusions about teaching software engineering in different environments.
Enzo Martinelli
2014-03-01
Full Text Available The use of mechanically-fastened fiber-reinforced polymer (MF-FRP systems has recently emerged as a competitive solution for the flexural strengthening of reinforced concrete (RC beams and slabs. An overview of the experimental research has proven the effectiveness and the potentiality of the MF-FRP technique which is particularly suitable for emergency repairs or when the speed of installation and immediacy of use are imperative. A finite-element (FE model has been recently developed by the authors with the aim to simulate the behavior of RC beams strengthened in bending by MF-FRP laminates; such a model has also been validated by using a wide experimental database collected from the literature. By following the previous study, the FE model and the assembled database are considered herein with the aim of better exploring the influence of some specific aspects on the structural response of MF-FRP strengthened members, such as the bearing stress-slip relationship assumed for the FRP-concrete interface, the stress-strain law considered for reinforcing steel rebars and the cracking process in RC members resulting in the well-known tension stiffening effect. The considerations drawn from this study will be useful to researchers for the calibration of criteria and design rules for strengthening RC beams through MF-FRP laminates.
Insight into collision zone dynamics from topography: numerical modelling results and observations
A. D. Bottrill
2012-11-01
Full Text Available Dynamic models of subduction and continental collision are used to predict dynamic topography changes on the overriding plate. The modelling results show a distinct evolution of topography on the overriding plate, during subduction, continental collision and slab break-off. A prominent topographic feature is a temporary (few Myrs basin on the overriding plate after initial collision. This "collisional mantle dynamic basin" (CMDB is caused by slab steepening drawing, material away from the base of the overriding plate. Also, during this initial collision phase, surface uplift is predicted on the overriding plate between the suture zone and the CMDB, due to the subduction of buoyant continental material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the overriding plate cause the uplift to spread further into the overriding plate. This topographic evolution fits the stratigraphy found on the overriding plate of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the overriding plate contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene–Early Miocene the surface of the overriding plate sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. Our modelled topography changes fit well with this observed uplift and subsidence.
Insight into collision zone dynamics from topography: numerical modelling results and observations
Bottrill, A. D.; van Hunen, J.; Allen, M. B.
2012-11-01
Dynamic models of subduction and continental collision are used to predict dynamic topography changes on the overriding plate. The modelling results show a distinct evolution of topography on the overriding plate, during subduction, continental collision and slab break-off. A prominent topographic feature is a temporary (few Myrs) basin on the overriding plate after initial collision. This "collisional mantle dynamic basin" (CMDB) is caused by slab steepening drawing, material away from the base of the overriding plate. Also, during this initial collision phase, surface uplift is predicted on the overriding plate between the suture zone and the CMDB, due to the subduction of buoyant continental material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the overriding plate cause the uplift to spread further into the overriding plate. This topographic evolution fits the stratigraphy found on the overriding plate of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the overriding plate contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the overriding plate sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. Our modelled topography changes fit well with this observed uplift and subsidence.
Insight into collision zone dynamics from topography: numerical modelling results and observations
A. D. Bottrill
2012-07-01
Full Text Available Dynamic models of subduction and continental collision are used to predict dynamic topography changes on the overriding plate. The modelling results show a distinct evolution of topography on the overriding plate, during subduction, continental collision and slab break-off. A prominent topographic feature is a temporary (few Myrs deepening in the area of the back arc-basin after initial collision. This collisional mantle dynamic basin (CMDB is caused by slab steepening drawing material away from the base of the overriding plate. Also during this initial collision phase, surface uplift is predicted on the overriding plate between the suture zone and the CMDB, due to the subduction of buoyant continental material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the overriding plate causes the uplift to spread further into the overriding plate. This topographic evolution fits the stratigraphy found on the overriding plate of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the overriding plate contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the overriding plate sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. This uplift and subsidence pattern correlates well with our modelled topography changes.
An Improvement of Numerical Result of Crashing CPM/PERT Network
Ten Wei Peng
2011-09-01
Full Text Available The research introduces and develops a mathematical modeling technique with linearized Taylor’s first order expansion and solve by using the simplex method. The main objective is to minimize the pessimistic time of the activity which is lie on the critical path by investing additional amounts of money to the project. 7 different amounts of money which is $5000, $10000, $15000, $20000, $25000, $30000 and $35000 will be invest to the project, to show the increase amount of money invest in the project will tend to minimize the pessimistic time to decrease the expected time and project duration. Then at the same time, it is also reduces its variance and standard deviation. As the result of the research, it will bring to the increase of the probability or percentage of completing the project on or before the completion time. The PERT and normal distribution will display the differences between of the amounts of money that will invest to the project.
Chaotic escape from an open vase-shaped cavity. I. Numerical and experimental results
Novick, Jaison; Keeler, Matthew L.; Giefer, Joshua; Delos, John B.
2012-01-01
We present part I in a two-part study of an open chaotic cavity shaped as a vase. The vase possesses an unstable periodic orbit in its neck. Trajectories passing through this orbit escape without return. For our analysis, we consider a family of trajectories launched from a point on the vase boundary. We imagine a vertical array of detectors past the unstable periodic orbit and, for each escaping trajectory, record the propagation time and the vertical detector position. We find that the escape time exhibits a complicated recursive structure. This recursive structure is explored in part I of our study. We present an approximation to the Helmholtz equation for waves escaping the vase. By choosing a set of detector points, we interpolate trajectories connecting the source to the different detector points. We use these interpolated classical trajectories to construct the solution to the wave equation at a detector point. Finally, we construct a plot of the detector position versus the escape time and compare this graph to the results of an experiment using classical ultrasound waves. We find that generally the classical trajectories organize the escaping ultrasound waves.
谢良喜; 孔建益; 万晓红
2009-01-01
建立了矩形截面叶片密封的数值模型,分析了预压缩量、密封油压等对密封表面接触压力和机械效率的影响.结果表明,叶片密封在径向区的压力分布为非线性曲线分布;密封可靠性和密封面机械效率不仅与预压缩量密切相关,还取决于密封油压.同样预压缩量下,密封油压较低时,密封可靠性更容易保证,但摩擦导致的机械效率损失也会相对较多;密封油压较高时,密封可靠性会有所降低,但摩擦对机械效率的影响也会有所减小.%A numerical model was established to study the effects of the initial interference and the seal pressure on the contact pressure and the mechanical efficiency of flexible rectangular section seals for vane. The computing results show that the curves of the contact pressure are nonlinear,the seal reliability and the mechanical efficiency are decided by the initial interference and the seal pressure. With the same initial interference, a vane seal can be reliable under a lower seal pressure, although with a lower mechanical efficiency. When the seal pressure is higher, seal failure can occur at some seal surface. So it may be necessary to modify the initial interference when the seal pressure changes.
数控机床液压系统的可靠性验证试验方法%Reliability Validation Test for Hydraulic System of Numerical Control Machine
尹鹏程
2011-01-01
根据数控机床液压系统的主要故障模式,建立液压系统的可靠性模型,给出液压系统的可靠性特征量；基于可靠性试验的基本思路,提出数控机床液压系统的可靠性试验方法并给出示例,为数控机床液压系统的可靠性验证试验提供技术途径.%The functions, principles and main failure modes of hydraulic system of numerical control machine were introduced. A reliability model for this type of hydraulic system was established. Reliability characteristic parameters of this hydraulic system were given. Based on the idea of characteristic parameter measurement, the reliability test methods of the hydraulic system were put forward. An application example was given. The research work provides technology way for reliability validation test methods of the hydraulic system of numerical control machine.
LaCommare, Kristina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Larsen, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eto, Joseph [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2017-01-01
Policymakers and regulatory agencies are expressing renewed interest in the reliability and resilience of the U.S. electric power system in large part due to growing recognition of the challenges posed by climate change, extreme weather events, and other emerging threats. Unfortunately, there has been little or no consolidated information in the public domain describing how public utility/service commission (PUC) staff evaluate the economics of proposed investments in the resilience of the power system. Having more consolidated information would give policymakers a better understanding of how different state regulatory entities across the U.S. make economic decisions pertaining to reliability/resiliency. To help address this, Lawrence Berkeley National Laboratory (LBNL) was tasked by the U.S. Department of Energy Office of Energy Policy and Systems Analysis (EPSA) to conduct an initial set of interviews with PUC staff to learn more about how proposed utility investments in reliability/resilience are being evaluated from an economics perspective. LBNL conducted structured interviews in late May-early June 2016 with staff from the following PUCs: Washington D.C. (DCPSC), Florida (FPSC), and California (CPUC).
Martins, Emerson Fachin; de Menezes, Lidiane Teles; de Sousa, Pedro Henrique Côrtes; de Araujo Barbosa, Paulo Henrique Ferreira; Costa, Abraão Souza
2012-01-01
First designed as an alternative method of assessing balance and susceptibility to falls among elderly, the Functional Reach Test (FR) has also been used among patients with hemiparesis. Then this study aimed to describe the intra- and inter-rater and the test/re-test reliability of the FR measure in subjects with and without hemiparesis while verifying anthropometric influences on the measurements. The FR was administered to a sample of subjects with hemiparesis and to a control group that was matched by gender and age. A two-way analysis of variance was used to verify the intra-rater reliability. It was calculated using the differences between the averages of the measures obtained during single, double or triple trials. The intra-class correlation coefficient (ICC) was utilized and data plotted using the Bland-Altman method. Associations were analyzed using Pearson's correlation coefficient. In general, the intra-rater analysis did not show significant differences between the measures for the single, double or triple trials. Excellent ICC values were observed, and there were no significant associations with anthropometric parameters for the hemiparesis and control subjects. FR showed good reliability for patients with and without hemiparesis and the test measurements were not significantly associated with the anthropometric characteristics of the subjects.
Doroshkevich, A. A.; Bryukhanova, V. V.; Samokhvalov, I. V.; Stykon, A. P.
2014-11-01
The task of laser sensing of droplet clouds by coaxial lidar is considered. Lidar return due to single scattering is formed in the volume bounded by the radiation pattern of the transmitter, while the double-scattering is determined by a receiving system field of view. The volume of the scattering medium exceeding a receiving system field of view forms the signal higher scattering orders ( < 2). The results of the numerical modeling of the distribution (in the recording plane) polarization characteristics of lidar signal from droplet clouds in the double scattering approximation in comparison with the results of the physical model experiment simulating sounding of a droplet cloud are discussed in this paper.
Numerical Modeling of Anti-icing Systems and Comparison to Test Results on a NACA 0012 Airfoil
Al-Khalil, Kamel M.; Potapczuk, Mark G.
1993-01-01
A series of experimental tests were conducted in the NASA Lewis IRT on an electro-thermally heated NACA 0012 airfoil. Quantitative comparisons between the experimental results and those predicted by a computer simulation code were made to assess the validity of a recently developed anti-icing model. An infrared camera was utilized to scan the instantaneous temperature contours of the skin surface. Despite some experimental difficulties, good agreement between the numerical predictions and the experiment results were generally obtained for the surface temperature and the possibility for each runback to freeze. Some recommendations were given for an efficient operation of a thermal anti-icing system.
Gilmore, M.; Desjardins, T. R.; Fisher, D. M.
2016-10-01
Ongoing experiments and numerical modeling on the effects of flow shear on electrostatic turbulence in the presence of electrode biasing are being conducted in helicon plasmas in the linear HelCat (Helicon-Cathode) device. It is found that changes in flow shear, affected by electrode biasing through Er x Bz rotation, can strongly affect fluctuation dynamics, including fully suppressing the fluctuations or inducing chaos. The fundamental underlying instability, at least in the case of low magnetic field, is identified as a hybrid resistive drift-Kelvin-Helmholtz mode. At higher magnetic fields, multiple modes (resistive drift, rotation-driven interchange and/or Kelvin-Helmholtz) are present, and interact nonlinearly. At high positive electrode bias (V >10Te), a large amplitude, global instability, identified as the potential relaxation instability is observed. Numerical modeling is also being conducted, using a 3 fluid global Braginskii solver for no or moderate bias cases, and a 1D PIC code for high bias cases. Recent experimental and numerical results will be presented. Supported by U.S. National Science Foundation Award 1500423.
Fitzgibbons, Megan; Meert, Deborah
2010-01-01
The use of bibliographic management software and its internal search interfaces is now pervasive among researchers. This study compares the results between searches conducted in academic databases' search interfaces versus the EndNote search interface. The results show mixed search reliability, depending on the database and type of search…
Fitzgibbons, Megan; Meert, Deborah
2010-01-01
The use of bibliographic management software and its internal search interfaces is now pervasive among researchers. This study compares the results between searches conducted in academic databases' search interfaces versus the EndNote search interface. The results show mixed search reliability, depending on the database and type of search…
Marco Panero
2006-11-01
Full Text Available We review some recent progress in quantum field theory in non-commutative space, focusing onto the fuzzy sphere as a non-perturbative regularisation scheme. We first introduce the basic formalism, and discuss the limits corresponding to different commutative or non-commutative spaces. We present some of the theories which have been investigated in this framework, with a particular attention to the scalar model. Then we comment on the results recently obtained from Monte Carlo simulations, and show a preview of new numerical data, which are consistent with the expected transition between two phases characterised by the topology of the support of a matrix eigenvalue distribution.
Sang Dong Kim; Byeong Chun Shin; Seokchan Kim; Gyungsoo Woo
2003-01-01
This paper studies the discrete minus one norm least-squares methods for the stress formulation of pure displacement linear elasticity in two dimensions. The proposed leastsquares functional is defined as the sum of the L2- and H-1-norms of the residual equations weighted appropriately. The minus one norm in the functional is replaced by the discrete minus one norm and then the discrete minus one norm least-squares methods are analyzed with various numerical results focusing on the finite element accuracy and multigrid convergence performances.
Haseroth, H; Langbein, K; Shirkov, G D
1995-01-01
A new library of the computer codes for the mathematical simulation of heavy ion production in the ECR ion source is presented. These codes are based on the equations of model of ion confinement and losses in ECR ion sources. The ECR4 developed at GANIL is now used for lead ion production for the accelerator complex at CERN. An ion pulse with a current of up to 100 emA of Pb27+ has been regularly injected into the linac since May 1994. The results of numerical simulation with these computer codes and interpretation of experimental data of lead ion production in the ECR source at CERN are presented.
LeBlanc, J. P. F.; Antipov, Andrey E.; Becca, Federico; Bulik, Ireneusz W.; Chan, Garnet Kin-Lic; Chung, Chia-Min; Deng, Youjin; Ferrero, Michel; Henderson, Thomas M.; Jiménez-Hoyos, Carlos A.; Kozik, E.; Liu, Xuan-Wen; Millis, Andrew J.; Prokof'ev, N. V.; Qin, Mingpu; Scuseria, Gustavo E.; Shi, Hao; Svistunov, B. V.; Tocchio, Luca F.; Tupitsyn, I. S.; White, Steven R.; Zhang, Shiwei; Zheng, Bo-Xiao; Zhu, Zhenyue; Gull, Emanuel; Simons Collaboration on the Many-Electron Problem
2015-10-01
Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.
Bertozzi, Denis A.; Rabi, Jose A. [Pontificia Univ. Catolica de Minas Gerais, Pocos de Caldas, MG (Brazil); Silva, Nivaldo C. da [Pontificia Univ. Catolica de Minas Gerais, Pocos de Caldas, MG (Brazil)]|[Comissao Nacional de Energia Nuclear (CNEN), Pocos de Caldas, MG (Brazil). Laboratorio
2002-07-01
As shown in the first part of this paper, equations for an attempt to simulate {sup 222} Rn activity along the axial distance in phosphogypsum-based embankments were presented. For that, an existing one-dimension diffusive model with source and sink terms was applied. Knowledge of the {sup 222} Rn concentration activity profile enables the assessment of the corresponding exhalation rate. In this second part of the paper, a preliminary version of the corresponding computational simulation program was tested against the analytical solution and steady-state experimental data. The numerical solution method followed a finite volume discretization on a structured orthogonal mesh. Grid points were located according to a cell-centered scheme and variables were stored in a collocated arrangement. The resulting algebraic equation system was relaxed by either the Tri-Diagonal Matrix Algorithm or Gauss-Seidel method. Grid size independence was observed as well. Numerical results are discussed upon and new developments and extensions of this first approach are pointed out. (author)
Belsey, R; Goitein, R K; Baer, D M
1987-07-17
The accuracy and precision of the Kodak DT-60 tabletop chemistry analyzer were evaluated in the clinical laboratory at the Portland (Ore) Veterans Administration Medical Center, and its operational throughout and cost were estimated. All DT-60 tests that were studied exhibited clinically acceptable precision and, except for the glucose method, accuracy. The accuracy of the glucose method was indeterminate with the available data. Throughput under field conditions was found to be less than half of the manufacturer's claim. The estimated supply cost per test could vary from $1.20 to $5.49 per test, depending on the test type and the number of assays expected to be performed daily. The instrument seems to be accurate, precise, and generally reliable when operated by professional medical technologists.
Bogdanović-Jovanović Jasmina B.
2012-01-01
Full Text Available In the increasing need for energy saving worldwide, the designing process of turbomachinery, as an essential part of thermal and hydroenergy systems, goes in the direction of enlarging efficiency. Therefore, the optimization of turbomachinery designing strongly affects the energy efficiency of the entire system. In the designing process of turbomachinery blade profiling, the model of axisymmetric fluid flows is commonly used in technical practice, even though this model suits only the profile cascades with infinite number of infinitely thin blades. The actual flow in turbomachinery profile cascades is not axisymmetric, and it can be fictively derived into the axisymmetric flow by averaging flow parameters in the blade passages according to the circular coordinate. Using numerical simulations of flow in turbomachinery runners, its operating parameters can be preliminarily determined. Furthermore, using the numerically obtained flow parameters in the blade passages, averaged axisymmetric flow surfaces in blade profile cascades can also be determined. The method of determination of averaged flow parameters and averaged meridian streamlines is presented in this paper, using the integral continuity equation for averaged flow parameters. With thus obtained results, every designer can be able to compare the obtained averaged flow surfaces with axisymmetric flow surfaces, as well as the specific work of elementary stages, which are used in the procedure of blade designing. Numerical simulations of flow in an exemplary axial flow pump, used as a part of the thermal power plant cooling system, were performed using Ansys CFX. [Projekat Ministarstva nauke Republike Srbije, br. TR33040: Revitalization of existing and designing new micro and mini hydropower plants (from 100 kW to 1000 kW in the territory of South and Southeast Serbia
A. C. Silva
2009-05-01
Full Text Available High resolution hydrographic observations of temperature and salinity are used to analyse the subsurface circulation along the coast of North Brazil, off the Amazon mouth, between 2° S and 6° N. Observations are presented from four cruises carried out in different periods of the year (March–May 1995, May–June 1999, July–August 2001 and October–November 1997. Numerical model outputs complement the results of the shipboard measurements, and are used to complete the descriptions of mesoscale circulation. The Salinity Maximum Waters are here analyzed, principally in order to describe the penetration of waters originating in the Southern Hemisphere toward the Northern Hemisphere through the North Brazil Current (NBC/North Brazil Undercurrent (NBUC. Our results show that, if the Equatorial Undercurrent (EUC is fed by Northern Atlantic Waters, this contribution may only occur in the ocean interior, east of the western boundary around 100 m depth. Modeling results indicate a southward penetration of the Western Boundary Undercurrent (WBUC below the thermocline, along the North Brazilian coast into the EUC or the North Equatorial Undercurrent (NEUC (around 48° W–3° N. The WBUC in the region does not flow more south than 3° N. The northern waters are diverted eastward either by the NBC retroflection or by the northern edge of the associated clockwise rings. The existence of subsurface mesoscale rings associated to the NBC retroflection is evidenced, without any signature in the surface layer, so confirming earlier numerical model outputs. These subsurface anticyclones, linked to the NBC/NBUC retroflection into the North Equatorial Undercurrent and the EUC, contribute to the transport of South Atlantic high salinity water into the Northern Hemisphere.
Silva, A.C. [Universidade Federal do Ceara, Fortaleza, CE (Brazil). Inst. de Ciencias do Mar; Bourles, B. [Inst. de Recherche pour le Developpement, Cotonou (Benin); Araujo, M. [UFPE, Recife, PE (Brazil). Lab. de Oceanografia Fisica Estuarina e Costeira
2009-07-01
High resolution hydrographic observations of temperature and salinity are used to analyse the subsurface circulation along the coast of North Brazil, off the Amazon mouth, between 2 S and 6 N. Observations are presented from four cruises carried out in different periods of the year (March-May 1995, May-June 1999, July-August 2001 and October-November 1997). Numerical model outputs complement the results of the shipboard measurements, and are used to complete the descriptions of mesoscale circulation. The Salinity Maximum Waters are here analyzed, principally in order to describe the penetration of waters originating in the Southern Hemisphere toward the Northern Hemisphere through the North Brazil Current (NBC)/North Brazil Undercurrent (NBUC). Our results show that, if the Equatorial Undercurrent (EUC) is fed by Northern Atlantic Waters, this contribution may only occur in the ocean interior, east of the western boundary around 100 m depth. Modeling results indicate a southward penetration of the Western Boundary Undercurrent (WBUC) below the thermocline, along the North Brazilian coast into the EUC or the North Equatorial Undercurrent (NEUC) (around 48 W-3 N). The WBUC in the region does not flow more south than 3 N. The northern waters are diverted eastward either by the NBC retroflection or by the northern edge of the associated clockwise rings. The existence of subsurface mesoscale rings associated to the NBC retroflection is evidenced, without any signature in the surface layer, so confirming earlier numerical model outputs. These subsurface anticyclones, linked to the NBC/NBUC retroflection into the North Equatorial Undercurrent and the EUC, contribute to the transport of South Atlantic high salinity water into the Northern Hemisphere. (orig.)
Støre-Valen, Jakob; Ryum, Truls; Pedersen, Geir A F; Pripp, Are H; Jose, Paul E; Karterud, Sigmund
2015-09-01
The Global Assessment of Functioning (GAF) Scale is used in routine clinical practice and research to estimate symptom and functional severity and longitudinal change. Concerns about poor interrater reliability have been raised, and the present study evaluated the effect of a Web-based GAF training program designed to improve interrater reliability in routine clinical practice. Clinicians rated up to 20 vignettes online, and received deviation scores as immediate feedback (i.e., own scores compared with expert raters) after each rating. Growth curves of absolute SD scores across the vignettes were modeled. A linear mixed effects model, using the clinician's deviation scores from expert raters as the dependent variable, indicated an improvement in reliability during training. Moderation by content of scale (symptoms; functioning), scale range (average; extreme), previous experience with GAF rating, profession, and postgraduate training were assessed. Training reduced deviation scores for inexperienced GAF raters, for individuals in clinical professions other than nursing and medicine, and for individuals with no postgraduate specialization. In addition, training was most beneficial for cases with average severity of symptoms compared with cases with extreme severity. The results support the use of Web-based training with feedback routines as a means to improve the reliability of GAF ratings performed by clinicians in mental health practice. These results especially pertain to clinicians in mental health practice who do not have a masters or doctoral degree.
Belsey, R; Vandenbark, M; Goitein, R K; Baer, D M
1987-07-17
The Kodak DT-60 tabletop chemistry analyzer was evaluated with standardized protocols to determine the system's precision and accuracy when operated by four volunteers (a secretary, a licensed practical nurse, and two family medicine residents) in a simulated office laboratory. The variability of the results was found to be significantly greater than the variability of results produced by medical technologists who analyzed the same samples during the same study period with another DT-60 placed in the hospital laboratory. The source(s) of increased variance needs to be identified so the system can be modified or new control procedures can be developed to ensure the reliability of results used in patient care. Prospective purchasers, manufacturers, and patients need this kind of objective information about the reliability of results produced by systems intended for use in physicians' office laboratories.
Andreani, Roberto; Friedlander, Ana; Mello, Margarida P.; Santos, Sandra A.
2005-06-01
In this work we show that the mixed nonlinear complementarity problem may be formulated as an equivalent nonlinear bound-constrained optimization problem that preserves the smoothness of the original data. One may thus take advantage of existing codes for bound-constrained optimization. This approach is implemented and tested by means of an extensive set of numerical experiments, showing promising results. The mixed nonlinear complementarity problems considered in the tests arise from the discretization of a motion planning problem concerning a set of rigid 3D bodies in contact in the presence of friction. We solve the complementarity problem associated with a single time frame, thus calculating the contact forces and accelerations of the bodies involved.
de'Michieli Vitturi, M.; Todesco, M.; Neri, A.; Esposti Ongaro, T.; Tola, E.; Rocco, G.
2011-12-01
We present a new DVD of the INGV outreach series, aimed at illustrating our research work on pyroclastic flow modeling. Pyroclastic flows (or pyroclastic density currents) are hot, devastating clouds of gas and ashes, generated during explosive eruptions. Understanding their dynamics and impact is crucial for a proper hazard assessment. We employ a 3D numerical model which describes the main features of the multi-phase and multi-component process, from the generation of the flows to their propagation along complex terrains. Our numerical results can be translated into color animations, which describe the temporal evolution of flow variables such as temperature or ash concentration. The animations provide a detailed and effective description of the natural phenomenon which can be used to present this geological process to a general public and to improve the hazard perception in volcanic areas. In our DVD, the computer animations are introduced and commented by professionals and researchers who deals at various levels with the study of pyroclastic flows and their impact. Their comments are taken as short interviews, mounted in a short video (about 10 minutes), which describes the natural process, as well as the model and its applications to some explosive volcanoes like Vesuvio, Campi Flegrei, Mt. St. Helens and Soufriere Hills (Montserrat). The ensemble of different voices and faces provides a direct sense of the multi-disciplinary effort involved in the assessment of pyroclastic flow hazard. The video also introduces the people who address this complex problem, and the personal involvement beyond the scientific results. The full, uncommented animations of the pyroclastic flow propagation on the different volcanic settings are also provided in the DVD, that is meant to be a general, flexible outreach tool.
2015-12-01
Full Text Available Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.
G. L. Hawkes; J. E. O' Brien; B. A. Haberman; A. J. Marquis; C. M. Baca; D. Tripepi; P. Costamagna
2008-06-01
A numerical study of the thermal and electrochemical performance of a single-tube Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) has been performed. Results obtained from two finite-volume computational fluid dynamics (CFD) codes FLUENT and SOHAB and from a two-dimensional inhouse developed finite-volume GENOA model are presented and compared. Each tool uses physical and geometric models of differing complexity and comparisons are made to assess their relative merits. Several single-tube simulations were run using each code over a range of operating conditions. The results include polarization curves, distributions of local current density, composition and temperature. Comparisons of these results are discussed, along with their relationship to the respective imbedded phenomenological models for activation losses, fluid flow and mass transport in porous media. In general, agreement between the codes was within 15% for overall parameters such as operating voltage and maximum temperature. The CFD results clearly show the effects of internal structure on the distributions of gas flows and related quantities within the electrochemical cells.
Devnagari numeral recognition by combining decision of multiple connectionist classiﬁers
Reena Bajaj; Lipika Dey; Santanu Chaudhury
2002-02-01
This paper is concerned with recognition of handwritten Devnagari numerals. The basic objective of the present work is to provide an efﬁcient and reliable technique for recognition of handwritten numerals. Three different types of features have been used for classiﬁcation of numerals. A multi-classiﬁer connectionist architecture has been proposed for increasing reliability of the recognition results. Experimental results show that the technique is effective and reliable.
Wild, S. C.; Georgen, J. E.
2012-12-01
In the southern Andes, the downgoing Nazca plate has adjacent zones with slab dip angles of 10° and 30°. To better understand the nature of mantle flow and plate deformation across the transition region between the juxtaposed angles, we calculate a steady-state, three-dimensional finite element numerical model. The overall three-dimensional model domain contains a rigid overlying plate, two subducting slabs (with dips of 10° and 30°), and a mantle wedge with a geometry that changes in the trench-parallel direction. The model space is generated by using two-dimensional solutions as boundary conditions for the trench-perpendicular "endcaps" of the numerical domain. Models solve the conservation equations of mass, momentum, and energy, neglecting heat production and thermal buoyancy and assuming isoviscous mantle flow. The sensitivity of the model to overriding plate thickness, coupling between the downgoing and overriding plates in the wedge corner region, and convergence velocity is also investigated. Temperature solutions from the three-dimensional models are used in calculations to delineate the brittle and ductile zones of the model domain. Models predict a significant amount of trench-parallel flow, as a result of the juxtaposition of the two slab angles. Also, the uppermost portion of the model space shows a continuous brittle section for trench-perpendicular distances of up to ~240 km, implying that the formation of a slab tear is relatively unlikely for the conditions and parameters simulated in this investigation. Future work will focus on different treatments of mantle viscosity and examining the sensitivity of the three-dimensional model to the selection of slab dip angle.
E. G. Merzlyakov
2004-06-01
Full Text Available Based on numerical calculations we demonstrate that small changes in the smooth climatological background atmosphere may lead to an unstable mean zonal wind distribution in the summer middle atmosphere. We relate these changes to small ones because locations and power of the main circulation structures are conserved, except for the acceleration of the easterly jet in the stratosphere/mesosphere. The instability forces oscillations propagating westward with a period of about 2 days and zonal wave numbers s=3 and/or 4. There are variations in the mean zonal wind distribution due to the excitation and transient propagation of these waves, and the numerical results correspond to features of these variations observed in experimental studies. The growing waves tend to remove the source of excitation. This process is effective enough to reduce the strong easterly jet and to remove the strong negative gradient of the zonal mean potential vorticity in the region of the instability. Therefore, when these parameters are calculated as mean values over a long time interval, the obtained values are too small to provide the instability. Strong 2-day waves, in turn, are unstable and can generate secondary waves with longer periods and lower zonal wave numbers. This effect is only significant for extremely strong 2-day waves. Another process is found to be more effective to produce secondary waves. We demonstrated that the 2-day wave with s=3 forced by nonlinear interaction between the 10-14 day planetary waves and the 2-day wave of zonal wave number 4 is unstable. This wave instability generates secondary waves with amplitudes that are large enough to be observed by ground-based radars, for example.
Hand, J W; Li, Y; Hajnal, J V [Imaging Sciences Department, Imperial College London (Hammersmith Campus), London W12 0NN (United Kingdom)], E-mail: j.hand@imperial.ac.uk
2010-02-21
Numerical simulations of specific absorption rate (SAR) and temperature changes in a 26-week pregnant woman model within typical birdcage body coils as used in 1.5 T and 3 T MRI scanners are described. Spatial distributions of SAR and the resulting spatial and temporal changes in temperature are determined using a finite difference time domain method and a finite difference bio-heat transfer solver that accounts for discrete vessels. Heat transfer from foetus to placenta via the umbilical vein and arteries as well as that across the foetal skin/amniotic fluid/uterine wall boundaries is modelled. Results suggest that for procedures compliant with IEC normal mode conditions (maternal whole-body averaged SAR{sub MWB} {<=} 2 W kg{sup -1} (continuous or time-averaged over 6 min)), whole foetal SAR, local foetal SAR{sub 10g} and average foetal temperature are within international safety limits. For continuous RF exposure at SAR{sub MWB} = 2 W kg{sup -1} over periods of 7.5 min or longer, a maximum local foetal temperature >38 deg. C may occur. However, assessment of the risk posed by such maximum temperatures predicted in a static model is difficult because of frequent foetal movement. Results also confirm that when SAR{sub MWB} = 2 W kg{sup -1}, some local SAR{sub 10g} values in the mother's trunk and extremities exceed recommended limits.
Hand, J. W.; Li, Y.; Hajnal, J. V.
2010-02-01
Numerical simulations of specific absorption rate (SAR) and temperature changes in a 26-week pregnant woman model within typical birdcage body coils as used in 1.5 T and 3 T MRI scanners are described. Spatial distributions of SAR and the resulting spatial and temporal changes in temperature are determined using a finite difference time domain method and a finite difference bio-heat transfer solver that accounts for discrete vessels. Heat transfer from foetus to placenta via the umbilical vein and arteries as well as that across the foetal skin/amniotic fluid/uterine wall boundaries is modelled. Results suggest that for procedures compliant with IEC normal mode conditions (maternal whole-body averaged SARMWB 38 °C may occur. However, assessment of the risk posed by such maximum temperatures predicted in a static model is difficult because of frequent foetal movement. Results also confirm that when SARMWB = 2 W kg-1, some local SAR10g values in the mother's trunk and extremities exceed recommended limits.
Reliability based design optimization: Formulations and methodologies
Agarwal, Harish
Modern products ranging from simple components to complex systems should be designed to be optimal and reliable. The challenge of modern engineering is to ensure that manufacturing costs are reduced and design cycle times are minimized while achieving requirements for performance and reliability. If the market for the product is competitive, improved quality and reliability can generate very strong competitive advantages. Simulation based design plays an important role in designing almost any kind of automotive, aerospace, and consumer products under these competitive conditions. Single discipline simulations used for analysis are being coupled together to create complex coupled simulation tools. This investigation focuses on the development of efficient and robust methodologies for reliability based design optimization in a simulation based design environment. Original contributions of this research are the development of a novel efficient and robust unilevel methodology for reliability based design optimization, the development of an innovative decoupled reliability based design optimization methodology, the application of homotopy techniques in unilevel reliability based design optimization methodology, and the development of a new framework for reliability based design optimization under epistemic uncertainty. The unilevel methodology for reliability based design optimization is shown to be mathematically equivalent to the traditional nested formulation. Numerical test problems show that the unilevel methodology can reduce computational cost by at least 50% as compared to the nested approach. The decoupled reliability based design optimization methodology is an approximate technique to obtain consistent reliable designs at lesser computational expense. Test problems show that the methodology is computationally efficient compared to the nested approach. A framework for performing reliability based design optimization under epistemic uncertainty is also developed
Dadaczynski, Kevin; Boye, Jutta
2015-12-01
The aim of the present study was to examine the usability and reliability of the HEPS quality checklist (Healthy Eating and Physical Activity in Schools), an instrument developed to assess the quality of school-based programmes on healthy eating and physical activity. With regard to usability, health promotion experts (n = 15) were asked to apply the HEPS quality checklist and to fill out a questionnaire about its comprehensibility and usability. To examine inter-rater reliability (IRR) a criteria-based selection of German school programmes on healthy eating and physical activity (n = 14) was randomly allocated to two programme pools and assessed independently by the authors. Results of the pilot testing revealed a high overall satisfaction with the HEPS quality checklist and a high willingness to use it or to recommend it to others. Furthermore, the checklist was perceived to be comprehensive and clearly structured. The assessment results of programme pool 1 revealed unsatisfactory Cohen's Kappa coefficients (IRR) and moderate intra-class correlations (ICC). After the HEPS manual guide had been amended with regard to its anchoring, the results of programme pool 2 showed substantial improvements with regard to IRR and ICC. In summary, the adapted HEPS quality checklist is a usable and reliable instrument for the quality assessment of school-based programmes on healthy eating and physical activity. The findings suggest that the HEPS checklist should be applied by two sufficiently trained raters.
LMI approach to reliable H∞ control of linear systems
Yao Bo; Wang Fuzhong
2006-01-01
The reliable design problem for linear systems is concerned with. A more practical model of actuator faults than outage is considered. An LMI approach of designing reliable controller is presented for the case of actuator faults that can be modeled by a scaling factor. The resulting control systems are reliable in that they provide guaranteed asymptotic stability and H∞ performance when some control component (actuator) faults occur. A numerical example is also given to illustrate the design procedure and their effectiveness. Furthermore, the optimal standard controller and the optimal reliable controller are compared to show the necessity of reliable control.
Blast-cooling of beef-in-sauce catering meals: numerical results based on a dynamic zero-order model
Jose A. Rabi
2014-10-01
Full Text Available Beef-in-sauce catering meals under blast-cooling have been investigated in a research project which aims at quantitative HACCP (hazard analysis critical control point. In view of its prospective coupling to a predictive microbiology model proposed in the project, zero-order spatial dependence has proved to suitably predict meal temperatures in response to temperature variations in the cooling air. This approach has modelled heat transfer rates via the a priori unknown convective coefficient hc which is allowed to vary due to uncertainty and variability in the actual modus operandi of the chosen case study hospital kitchen. Implemented in MS Excel®, the numerical procedure has successfully combined the 4th order Runge-Kutta method, to solve the governing equation, with non-linear optimization, via the built-in Solver, to determine the coefficient hc. In this work, the coefficient hc was assessed for 119 distinct recently-cooked meal samples whose temperature-time profiles were recorded in situ after 17 technical visits to the hospital kitchen over a year. The average value and standard deviation results were hc = 12.0 ± 4.1 W m-2 K-1, whilst the lowest values (associated with the worst cooling scenarios were about hc » 6.0 W m-2 K-1.
Perez-Poch, Antoni
Computer simulations are becoming a promising research line of work, as physiological models become more and more sophisticated and reliable. Technological advances in state-of-the-art hardware technology and software allow nowadays for better and more accurate simulations of complex phenomena, such as the response of the human cardiovascular system to long-term exposure to microgravity. Experimental data for long-term missions are difficult to achieve and reproduce, therefore the predictions of computer simulations are of a major importance in this field. Our approach is based on a previous model developed and implemented in our laboratory (NELME: Numercial Evaluation of Long-term Microgravity Effects). The software simulates the behaviour of the cardiovascular system and different human organs, has a modular archi-tecture, and allows to introduce perturbations such as physical exercise or countermeasures. The implementation is based on a complex electrical-like model of this control system, using inexpensive development frameworks, and has been tested and validated with the available experimental data. The objective of this work is to analyse and simulate long-term effects and gender differences when individuals are exposed to long-term microgravity. Risk probability of a health impairement which may put in jeopardy a long-term mission is also evaluated. . Gender differences have been implemented for this specific work, as an adjustment of a number of parameters that are included in the model. Women versus men physiological differences have been therefore taken into account, based upon estimations from the physiology bibliography. A number of simulations have been carried out for long-term exposure to microgravity. Gravity varying continuosly from Earth-based to zero, and time exposure are the two main variables involved in the construction of results, including responses to patterns of physical aerobic ex-ercise and thermal stress simulating an extra
Trzaska, S.; Moron, V.; Fontaine, B.
1996-10-01
This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST) patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP) climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder) than the long-term mean in the southern hemisphere (northern hemisphere)]. Atlantic SSTAs may also play a significant role. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->
Kurz, Jochen H. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren (IZEP), Saarbruecken (Germany); Dugan, Sandra; Juengert, Anne [Stuttgart Univ. (Germany). Materialpruefungsanstalt (MPA)
2013-07-01
Reliable assessment procedures are an important aspect of maintenance concepts. Non-destructive testing (NDT) methods are an essential part of a variety of maintenance plans. Fracture mechanical assessments require knowledge of flaw dimensions, loads and material parameters. NDT methods are able to acquire information on all of these areas. However, it has to be considered that the level of detail information depends on the case investigated and therefore on the applicable methods. Reliability aspects of NDT methods are of importance if quantitative information is required. Different design concepts e.g. the damage tolerance approach in aerospace already include reliability criteria of NDT methods applied in maintenance plans. NDT is also an essential part during construction and maintenance of nuclear power plants. In Germany, type and extent of inspection are specified in Safety Standards of the Nuclear Safety Standards Commission (KTA). Only certified inspections are allowed in the nuclear industry. The qualification of NDT is carried out in form of performance demonstrations of the inspection teams and the equipment, witnessed by an authorized inspector. The results of these tests are mainly statements regarding the detection capabilities of certain artificial flaws. In other countries, e.g. the U.S., additional blind tests on test blocks with hidden and unknown flaws may be required, in which a certain percentage of these flaws has to be detected. The knowledge of the probability of detection (POD) curves of specific flaws in specific testing conditions is often not present. This paper shows the results of a research project designed for POD determination of ultrasound phased array inspections of real and artificial cracks. The continuative objective of this project was to generate quantitative POD results. The distribution of the crack sizes of the specimens and the inspection planning is discussed, and results of the ultrasound inspections are presented. In
Owen, S. E.; Simons, M.; Hua, H.; Yun, S.; Cruz, J.; Webb, F.; Rosen, P. A.; Fielding, E. J.; Moore, A. W.; Polet, J.; Liu, Z.; Agram, P. S.; Lundgren, P.
2013-12-01
ARIA is a joint JPL/Caltech coordinated project to automate InSAR and GPS imaging capabilities for scientific understanding, hazard response, and societal benefit. Geodetic imaging's unique ability to capture surface deformation in high spatial and temporal resolution allows us to resolve the fault geometry and distribution of slip associated with earthquakes in high spatial & temporal detail. In certain cases, it can be complementary to seismic data, providing constraints on location, geometry, or magnitude that is difficult to determine with seismic data alone. In addition, remote sensing with SAR provides change detection and damage assessment capabilities for earthquakes, floods and other disasters that can image even at night or through clouds. We have built an end-to-end prototype geodetic imaging data system that forms the foundation for a hazard response and science analysis capability that integrates InSAR, high-rate GPS, seismology, and modeling to deliver monitoring, science, and situational awareness products. This prototype incorporates state-of-the-art InSAR and GPS analysis algorithms from technologists and scientists. The products have been designed and a feasibility study conducted in collaboration with USGS scientists in the earthquake and volcano science programs. We will present results that show the capabilities of this data system in terms of latency, data processing capacity, quality of automated products, and feasibility of use for analysis of large SAR and GPS data sets and for earthquake response activities.
Boughebri, Omar; Maqdes, Ali; Moraiti, Constantina; Dib, Choukry; Leclère, Franck Marie; Valenti, Philippe
2015-05-01
The Instability Severity Index Score (ISIS) includes preoperative clinical and radiological risk factors to select patients who can benefit from an arthroscopic Bankart procedure with a low rate of recurrence. Patients who underwent an arthroscopic Bankart for anterior shoulder instability with an ISIS lower than or equal to four were assessed after a minimum of 5-year follow-up. Forty-five shoulders were assessed at a mean of 79 months (range 60-118 months). Average age was 29.4 years (range 17-58 years) at the time of surgery. Postoperative functions were assessed by the Walch and Duplay and the Rowe scores for 26 patients; an adapted telephonic interview was performed for the 19 remaining patients who could not be reassessed clinically. A failure was defined by the recurrence of an anterior dislocation or subluxation. Patients were asked whether they were finally very satisfied, satisfied or unhappy. The mean Walch and Duplay score at last follow-up was 84.3 (range 35-100). The final result for these patients was excellent in 14 patients (53.8 %), good in seven cases (26.9 %), poor in three patients (11.5 %) and bad in two patients (7.7 %). The mean Rowe score was 82.6 (range 35-100). Thirty-nine patients (86.7 %) were subjectively very satisfied or satisfied, and six (13.3 %) were unhappy. Four patients (8.9 %) had a recurrence of frank dislocation with a mean delay of 34 months (range 12-72 months). Three of them had a Hill-Sachs lesion preoperatively. Two patients had a preoperative ISIS at 4 points and two patients at 3 points. The selection based on the ISIS allows a low rate of failure after an average term of 5 years. Lowering the limit for indication to 3 points allows to avoid the association between two major risk factors for recurrence, which are valued at 2 points. The existence of a Hill-Sachs lesion is a stronger indicator for the outcome of instability repair. Level IV, Retrospective Case Series, Treatment Study.
Yin, Xiaohong; Huang, Zhijiong; Zheng, Junyu; Yuan, Zibing; Zhu, Wenbo; Huang, Xiaobo; Chen, Duohong
2017-04-01
As one of the most populous and developed provinces in China, Guangdong province (GD) has been experiencing regional haze problems. Identification of source contributions to ambient PM2.5 level is essential for developing effective control strategies. In this study, using the most up-to-date emission inventory and validated numerical model, source contributions to ambient PM2.5 from eight emission source sectors (agriculture, biogenic, dust, industry, power plant, residential, mobile and others) in GD in 2012 were quantified. Results showed that mobile sources are the dominant contributors to the ambient PM2.5 (24.0%) in the Pearl River Delta (PRD) region, the central and most developed area of GD, while industry sources are the major contributors (21.5% 23.6%) to those in the Northeastern GD (NE-GD) region and the Southwestern GD (SW-GD) region. Although many industries have been encouraged to move from the central GD to peripheral areas such as NE-GD and SW-GD, their emissions still have an important impact on the PM2.5 level in the PRD. In addition, agriculture sources are responsible for 17.5% to ambient PM2.5 in GD, indicating the importance of regulations on agricultural activities, which has been largely ignored in the current air quality management. Super-regional contributions were also quantified and their contributions to the ambient PM2.5 in GD are significant with notable seasonal differences. But they might be overestimated and further studies are needed to better quantify the transport impacts.
Hartzell, Allyson L; Shea, Herbert R
2010-01-01
This book focuses on the reliability and manufacturability of MEMS at a fundamental level. It demonstrates how to design MEMs for reliability and provides detailed information on the different types of failure modes and how to avoid them.
Reliability Evaluation of Slopes Using Particle Swarm Optimization
Mohammad Khajehzadeh
2011-01-01
Full Text Available The objective of this research is to develop a numerical procedure to reliability evaluation of earth slope and locating the critical probabilistic slip surface. The performance function is formulated using simplified Bishop’s limit equilibrium method to calculate the reliability index. The reliability index defined by Hasofer and Lind is used as an index of safety measure. Searching the critical probabilistic surface that is associated with the lowest reliability index will be formulated as an optimization problem. In this paper, particle swarm optimization is applied to calculate the minimum Hasofer and Lind reliability index and critical probabilistic failure surface. To demonstrate the applicability and to investigate the effectiveness of the algorithm, two numerical examples from literature are illustrated. Results show that the proposed method is capable to achieve better solutions for reliability analysis of slope if compared with those reported in the literature.
Bassam A. Hassan
2010-01-01
Full Text Available Objectives: The purpose of the present study was to investigate the reliability of both periapical radiographs and orthopantomograms for exact detection of tooth root protrusion in the maxillary sinus by correlating the results with cone beam computed tomography.Material and methods: A database of 1400 patients scanned with cone beam computed tomography (CBCT was searched for matching periapical (PA radiographs and orthopantogram (OPG images of maxillary premolars and molars. Matching OPG images datasets of 101 patients with 628 teeth and PA radiographs datasets of 93 patients with 359 teeth were identified. Four observers assessed the relationship between the apex of tooth root and the maxillary sinus per tooth on PA radiographs, OPG and CBCT images using the following classification: root tip is in the sinus (class 1, root tip is against the sinus wall (class 2 and root tip is not in the sinus (class 3.Results: Overall correlation between OPG and CBCT images scores was 50%, 26% and 56.1% for class 1, class 2 and class 3, respectively (Cohen’s kappa [weighted] = 0.1. Overall correlation between PA radiographs and CBCT images was 75.8%, 15.8% and 56.9% for class 1, class 2 and class 3, respectively (Cohen’s kappa [weighted] = 0.24. In both the OPG images and the PA radiographs datasets, class 1 correlation was most frequently observed with the first and second molars.Conclusions: The results demonstrated that both periapical radiographs and orthopantomograms are not reliable in determination of exact relationship between the apex of tooth root and the maxillary sinus floor. Periapical radiography is slightly more reliable than orthopantomography in determining this relationship.
一种雷达质量评估结果可信度分析方法%Analytic method for result reliability of radar quality assessment
王涛; 欧阳林涛; 毕增军; 侯晓东
2015-01-01
For achieving the reliable result of radar equipment quality assessment, setting about the inefficiency of traditional quality assessment and the reality of quality assessment of radar equipment system, this paper proposes a measurement method for the reliability of assessment results, based on the combination of weighted DS evidence theory with experts’evaluation, and performs its testing by taking some examples. Test results show that the proposed method is of feasibility and effectiveness for the assessment results of radar equipment quality, thus providing a powerful technical support for the robustness assessment of the radar equipment system.%为了得到雷达装备质量评估的可靠结果，从传统质量评估的不足和雷达装备系统质量评估的实际出发，提出了基于权重的DS证据理论与专家评定相结合的方法来对评估结果的可信度进行测度，并通过实例进行了验证。验证结果表明了该方法在雷达装备质量评估结果中的可行性和有效性，为雷达装备系统稳健评估提供了一种有力的技术支撑。
任丽娜; 芮执元; 李建华
2014-01-01
In minimal repair, in order to describe the failure process of numerical control(NC) machine tools experiencing both early failures and deterioration phenomena, and operating so long that the intensity function approaches a finite asymptote as the system operating time grows, a new four-parameter non-homogeneous Poisson process model is proposed. The characteristics of the model are discussed, and the physical meaning of its parameters is given, calculating formula of point estimation for model parameters and reliability indices such as the minimum intensity value and the time of minimum intensity are all derived, then a method of model selection for reliability assessment of two NC machine tools is provided based on the likelihood ratio statistic, and the model evaluation criterion is given based on the index of goodness-of-fit test. The real failure data of two NC machine tools are analyzed by using the proposed method, the results show that this method can quantitatively evaluate the machine tools’ lasting time of early failure period, it is suitable for describing the failure process of NC machine tools with bounded and bathtub shaped failure trend, and can provide a theoretical basis for eliminating as much early failures as possible before the NC machine tools leave the factory.%最小维修情况下，为描述经历早期故障和耗损故障且故障强度随工作时间增加而趋近于某一常数的数控机床故障过程，提出一种新的4参数非齐次泊松过程模型。讨论模型的特性，给出模型中各参数的物理意义，推导计算模型参数及诸如最小故障强度、最小故障强度对应的故障时刻等重要可靠性指标点估计的计算公式，基于似然比检验理论，给出两台数控机床可靠性评估的模型选择方法，并基于拟合优度检验指标R，给出模型评价准则。对两台数控机床故障数据进行分析，结果表明，该模型可定量评估机床的早期故障期
Bendell, A
1986-01-01
Software Reliability reviews some fundamental issues of software reliability as well as the techniques, models, and metrics used to predict the reliability of software. Topics covered include fault avoidance, fault removal, and fault tolerance, along with statistical methods for the objective assessment of predictive accuracy. Development cost models and life-cycle cost models are also discussed. This book is divided into eight sections and begins with a chapter on adaptive modeling used to predict software reliability, followed by a discussion on failure rate in software reliability growth mo
Hassan, Bassam A
2010-01-01
The purpose of the present study was to investigate the reliability of both periapical radiographs and orthopantomograms for exact detection of tooth root protrusion in the maxillary sinus by correlating the results with cone beam computed tomography. A database of 1400 patients scanned with cone beam computed tomography (CBCT) was searched for matching periapical (PA) radiographs and orthopantogram (OPG) images of maxillary premolars and molars. Matching OPG images datasets of 101 patients with 628 teeth and PA radiographs datasets of 93 patients with 359 teeth were identified. Four observers assessed the relationship between the apex of tooth root and the maxillary sinus per tooth on PA radiographs, OPG and CBCT images using the following classification: root tip is in the sinus (class 1), root tip is against the sinus wall (class 2) and root tip is not in the sinus (class 3). Overall correlation between OPG and CBCT images scores was 50%, 26% and 56.1% for class 1, class 2 and class 3, respectively (Cohen's kappa [weighted] = 0.1). Overall correlation between PA radiographs and CBCT images was 75.8%, 15.8% and 56.9% for class 1, class 2 and class 3, respectively (Cohen's kappa [weighted] = 0.24). In both the OPG images and the PA radiographs datasets, class 1 correlation was most frequently observed with the first and second molars. The results demonstrated that both periapical radiographs and orthopantomograms are not reliable in determination of exact relationship between the apex of tooth root and the maxillary sinus floor. Periapical radiography is slightly more reliable than orthopantomography in determining this relationship.
Declair, Stefan; Stephan, Klaus; Potthast, Roland
2015-04-01
Determining the amount of weather dependent renewable energy is a demanding task for transmission system operators (TSOs). In the project EWeLiNE funded by the German government, the German Weather Service and the Fraunhofer Institute on Wind Energy and Energy System Technology strongly support the TSOs by developing innovative weather- and power forecasting models and tools for grid integration of weather dependent renewable energy. The key in the energy prediction process chain is the numerical weather prediction (NWP) system. With focus on wind energy, we face the model errors in the planetary boundary layer, which is characterized by strong spatial and temporal fluctuations in wind speed, to improve the basis of the weather dependent renewable energy prediction. Model data can be corrected by postprocessing techniques such as model output statistics and calibration using historical observational data. On the other hand, latest observations can be used in a preprocessing technique called data assimilation (DA). In DA, the model output from a previous time step is combined such with observational data, that the new model data for model integration initialization (analysis) fits best to the latest model data and the observational data as well. Therefore, model errors can be already reduced before the model integration. In this contribution, the results of an impact study are presented. A so-called OSSE (Observation Simulation System Experiment) is performed using the convective-resoluted COSMO-DE model of the German Weather Service and a 4D-DA technique, a Newtonian relaxation method also called nudging. Starting from a nature run (treated as the truth), conventional observations and artificial wind observations at hub height are generated. In a control run, the basic model setup of the nature run is slightly perturbed to drag the model away from the beforehand generated truth and a free forecast is computed based on the analysis using only conventional
Power electronics reliability analysis.
Smith, Mark A.; Atcitty, Stanley
2009-12-01
This report provides the DOE and industry with a general process for analyzing power electronics reliability. The analysis can help with understanding the main causes of failures, downtime, and cost and how to reduce them. One approach is to collect field maintenance data and use it directly to calculate reliability metrics related to each cause. Another approach is to model the functional structure of the equipment using a fault tree to derive system reliability from component reliability. Analysis of a fictitious device demonstrates the latter process. Optimization can use the resulting baseline model to decide how to improve reliability and/or lower costs. It is recommended that both electric utilities and equipment manufacturers make provisions to collect and share data in order to lay the groundwork for improving reliability into the future. Reliability analysis helps guide reliability improvements in hardware and software technology including condition monitoring and prognostics and health management.
Günes, Ülkü Yapucu; Efteli, Elçin
2015-04-01
Multiple pressure ulcer (PU) risk assessment instruments have been developed and tested, but there is no general consensus on which instrument to use for specific patient populations and care settings. The purpose of this study was to determine the reliability and predictive validity of the Turkish version of the Risk Assessment Pressure Sore (RAPS) instrument, which includes 12 variables--5 from the modified Norton Scale, 3 from the Braden Scale, and 3 from other research results--for use in intensive care unit (ICU) patients. The English version of the RAPS instrument was translated into Turkish and tested for internal consistency and predictive validity (sensitivity, specificity, positive predictive value, and negative predictive value) using a convenience sample of 122 patients consecutively admitted to an ICU unit in Turkey. The patients were assessed within 24 hours of admission, and after that, once a week until the development of a PU or discharge from the unit. The incidence of PUs in this population was 23%. The majority of ulcers that developed were Stage I. Internal consistency of the RAPS tool was adequate (Cronbach's α = 0.81). The best balance between sensitivity and specificity for ICU patients was reached at a cut-off point of ≤ 27 (ie, sensitivity = 74.2%, specificity = 31.8%, positive predictive value = 38.7%, and negative predictive value 91.3%). This is lower than the cut-off point reported in other studies of the RAPS scale. In this population of ICU patients, the RAPS scale was found to have acceptable reliability and poor validity. Additional studies to evaluate the predictive validity and reliability of the RAPS scale in other patient populations and care settings are needed.
Urai J.L.
2010-06-01
Full Text Available We compare analogue and numerical models of dilatational fractures at low confining stress. These structures form an effective conduit for fluid flow in the field, but are difficult to model since they form in cohesive materials at low stresses. We use a truly cohesive powder for the analogue models and a Discrete Element Model (DEM with brittle-elastic bonds for the numerical modelling. We show that despite variations in the model type, small differences in the location of initial fractures and the way these structures link-up to control the evolution of the model, the observed structures are robust. Three structural zones develop where different fault types dominate. In 3D numerical models we show an increase of the porosity on the fault zone with increasing deformation. The progradation direction is shown to be controlled by the position of the fracture. The combination of analogue models with cohesive powder and DEMs with internal cohesion is an excellent tool to study the evolution of open fractures.
Reliability of tactile tools for pain assessment in blind athletes.
Leite, Ana Claudia de Souza; Pagliuca, Lorita M Freitag; Almeida, Paulo Cesar P; Dallaire, Clemence C
2008-06-01
Health professionals have numerous visual and reporting scales at their disposal to assess pain. In recent years new tactile tools have been created (Pain Texture Scale and Tactile Pain Scale). This study validates these scales compared with the Numerical Rating Scale in 36 blind athletes who were assessed before and after competitions in the World Paralympics Games organized by the International Blind Sports Federation (IBSA) in Quebec, Canada. The reliability of these scales was analyzed through the intraclass correlation coefficient. Results showed good reliability for the Tactile Pain Scale and satisfactory reliability for the Pain Texture Scale.
Sprenger, Lisa, E-mail: Lisa.Sprenger@tu-dresden.de; Lange, Adrian; Odenbach, Stefan [Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, Measuring and Automation Technology, TU Dresden, 01062 Dresden (Germany)
2013-12-15
Ferrofluids are colloidal suspensions consisting of magnetic nanoparticles dispersed in a carrier liquid. Their thermodiffusive behaviour is rather strong compared to molecular binary mixtures, leading to a Soret coefficient (S{sub T}) of 0.16 K{sup −1}. Former experiments with dilute magnetic fluids have been done with thermogravitational columns or horizontal thermodiffusion cells by different research groups. Considering the horizontal thermodiffusion cell, a former analytical approach has been used to solve the phenomenological diffusion equation in one dimension assuming a constant concentration gradient over the cell's height. The current experimental work is based on the horizontal separation cell and emphasises the comparison of the concentration development in different concentrated magnetic fluids and at different temperature gradients. The ferrofluid investigated is the kerosene-based EMG905 (Ferrotec) to be compared with the APG513A (Ferrotec), both containing magnetite nanoparticles. The experiments prove that the separation process linearly depends on the temperature gradient and that a constant concentration gradient develops in the setup due to the separation. Analytical one dimensional and numerical three dimensional approaches to solve the diffusion equation are derived to be compared with the solution used so far for dilute fluids to see if formerly made assumptions also hold for higher concentrated fluids. Both, the analytical and numerical solutions, either in a phenomenological or a thermodynamic description, are able to reproduce the separation signal gained from the experiments. The Soret coefficient can then be determined to 0.184 K{sup −1} in the analytical case and 0.29 K{sup −1} in the numerical case. Former theoretical approaches for dilute magnetic fluids underestimate the strength of the separation in the case of a concentrated ferrofluid.
Koch, S; Harlander, U; Egbers, C [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Hollerbach, R, E-mail: uwe.harlander@tu-cottbus.de [Institute of Geophysics, ETH Zuerich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)
2013-06-15
We begin with an experimental investigation of the flow induced in a rotating spherical shell. The shell globally rotates with angular velocity {Omega}. A further periodic oscillation with angular velocity 0 Less-Than-Or-Slanted-Equal-To {omega} Less-Than-Or-Slanted-Equal-To 2{Omega}, a so-called longitudinal libration, is added on the inner sphere's rotation. The primary response is inertial waves spawned at the critical latitudes on the inner sphere, and propagating throughout the shell along inclined characteristics. For sufficiently large libration amplitudes, the higher harmonics also become important. Those harmonics whose frequencies are still less than 2{Omega} behave as inertial waves themselves, propagating along their own characteristics. The steady component of the flow consists of a prograde zonal jet on the cylinder tangent to the inner sphere and parallel to the axis of rotation, and increases with decreasing Ekman number. The jet becomes unstable for larger forcing amplitudes as can be deduced from the preliminary particle image velocimetry observations. Finally, a wave attractor is experimentally detected in the spherical shell as the pattern of largest variance. These findings are reproduced in a two-dimensional numerical investigation of the flow, and certain aspects can be studied numerically in greater detail. One aspect is the scaling of the width of the inertial shear layers and the width of the steady jet. Another is the partitioning of the kinetic energy between the forced wave, its harmonics and the mean flow. Finally, the numerical simulations allow for an investigation of instabilities, too local to be found experimentally. For strong libration amplitudes, the boundary layer on the inner sphere becomes unstable, triggering localized Goertler vortices during the prograde phase of the forcing. This instability is important for the transition to turbulence of the spherical shell flow. (paper)
Kaiser, B. O.; Scheck-Wenderoth, M.; Cacace, M.; Przybycin, A.; Lewerenz, B.
2012-04-01
Sedimentary basins provide a significant portion of geothermal energy. Making geothermal heat an effective source for sustainable energy supply requires a quantitative reserve assessment. Numerical (mathematical) models of sedimentary basins are useful tools for first-order approximations of the geothermal potential on a regional scale. The challenge for numerical investigations within complex geological sedimentary basins is that the thermal field contains superposed signals originating from several heat transport processes, different in nature but physically coupled. An additional difficulty arising from numerical simulations is the error introduced by discretizing a continuous physical system into its numerical counterpart. Different mesh resolutions may lead to different and sometimes contrasting computational findings, thus making the reliability of coupled numerical simulations at least questionable. By means of 3D numerical simulations we discriminate conductive, forced convective and free thermal convective heat transport within a complex geological setting, the Northeast German Basin. As a second step we explore the sensitivity of each heat transport process with regard to the spatial discretization. The internal geological structure of the NEGB is characterized by the presence of a highly structured Zechstein salt sequence piercing the sedimentary overburden locally. Moreover, the Zechstein salt is impervious to fluid flow and has a relative high thermal conductivity compared to the surrounding clastic sediments. Computational results show that these hydrogeological conditions exerts primary constraints on the internal hydrothermal setting of the basin. The impervious nature of the Zechstein salt inhibits groundwater flow to be effective. Accordingly, conduction is the main heat transport mechanism within the salt. In contrast, forced convective heat transport triggerd by topographic gradients affects mainly the temperature distribution within the post
Mohamed Yousef Ahmed Abou-Hussein
2014-01-01
Full Text Available In this study, the central radio propagation laboratory (CRPL method of ionospheric prediction of the National Bureau of Standards (NBS in U.S.A was used in practical calculations of the optimal working frequencies for reliable high frequency (HF radio communication links between Benghazi-Libya and Cairo-Egypt. The results were drawn in the form of curves by using the computer. The computer was used to measure the received signal level variation of frequencies 11.980 MHz, 11.785 MHz which were transmitted with a power of 250 KW, 100 KW respectively from the Egypt Arabic Republic Broadcasting station in Cairo city, directed to the North Africa and South Europe regions. The measurements were taken during daytime's for winter (December, January& February and summer (June, July & August seasons.
John V. Ringwood
2013-08-01
Full Text Available Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model.
RELIABLE VALIDATION BASED ON OPTICAL FLOW VISUALIZATION FOR CFD SIMULATIONS
姜宗林
2003-01-01
A reliable validation based on the optical flow visualization for numerical simula-tions of complex flowfields is addressed in this paper. Several test cases, including two-dimensional,axisymmetric and three-dimensional flowfields, were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields. In the validation, imagesof these flowfields were constructed from numerical results based on the principle of the optical flowvisualization, and compared directly with experimental interferograms. Because both experimental and numerical results axe of identical physical representation, the agreement between them can be evaluatedeffectively by examining flow structures as well as checking discrepancies in density. The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.
RELIABLE VALIDATION BASED ON OPTICAL FLOW VISUALIZATION FOR CFD SIMULATIONS
姜宗林
2003-01-01
A reliable validation based on the optical flow visualization for numerical simulations of complex flowfields is addressed in this paper.Several test cases,including two-dimensional,axisymmetric and three-dimensional flowfields,were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields.In the validation,images of these flowfields were constructed from numerical results based on the principle of the optical flow visualization,and compared directly with experimental interferograms.Because both experimental and numerical results are of identical physical representation,the agreement between them can be evaluated effectively by examining flow structures as well as checking discrepancies in density.The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.
Sergeev, E. N.; Grach, S. M.
2017-07-01
The data on measured dynamic characteristics of diagnostic stimulated electromagnetic emission (SEE) of the ionosphere are presented. Numerical simulations of the SEE evolution within the framework of a theoretical model of the broad-continuum SEE feature with the use of improved (3D) empirical model of the spatial spectrum of artificial irregularities of the HF pumped ionospheric plasma are performed and compared with the measurement data. Possible applications of such a comparison for determining the spectrum parameters and studying the evolution of the geomagnetic field-aligned artificial irregularities (striations) are discussed. It is concluded that changes in the intensity and spectrum shape of the striations, mainly for transverse scales l ⊥ 2-18 m, play the decisive role in the observed variations of the magnitude and temporal characteristics of the overshoot effect (formation of the intensity maximum followed by the suppression of the ionospheric SEE intensity).
Donmez, Orhan
The shocked wave created on the accretion disk after different physical phenomena (accretion flows with pressure gradients, star-disk interaction etc.) may be responsible observed Quasi Periodic Oscillations (QPOs) in X-ray binaries. We present the set of characteristics frequencies associated with accretion disk around the rotating and non-rotating black holes for one particle case. These persistent frequencies are results of the rotating pattern in an accretion disk. We compare the frequency's from two different numerical results for fluid flow around the non-rotating black hole with one particle case. The numerical results are taken from Refs. 1 and 2 using fully general relativistic hydrodynamical code with non-selfgravitating disk. While the first numerical result has a relativistic tori around the black hole, the second one includes one-armed spiral shock wave produced from star-disk interaction. Some physical modes presented in the QPOs can be excited in numerical simulation of relativistic tori and spiral waves on the accretion disk. The results of these different dynamical structures on the accretion disk responsible for QPOs are discussed in detail.
Gröne Jörn
2010-11-01
Full Text Available Abstract Background Treatment of non-small cell lung cancer with novel targeted therapies is a major unmet clinical need. Alternative splicing is a mechanism which generates diverse protein products and is of functional relevance in cancer. Results In this study, a genome-wide analysis of the alteration of splicing patterns between lung cancer and normal lung tissue was performed. We generated an exon array data set derived from matched pairs of lung cancer and normal lung tissue including both the adenocarcinoma and the squamous cell carcinoma subtypes. An enhanced workflow was developed to reliably detect differential splicing in an exon array data set. In total, 330 genes were found to be differentially spliced in non-small cell lung cancer compared to normal lung tissue. Microarray findings were validated with independent laboratory methods for CLSTN1, FN1, KIAA1217, MYO18A, NCOR2, NUMB, SLK, SYNE2, TPM1, (in total, 10 events and ADD3, which was analysed in depth. We achieved a high validation rate of 69%. Evidence was found that the activity of FOX2, the splicing factor shown to cause cancer-specific splicing patterns in breast and ovarian cancer, is not altered at the transcript level in several cancer types including lung cancer. Conclusions This study demonstrates how alternatively spliced genes can reliably be identified in a cancer data set. Our findings underline that key processes of cancer progression in NSCLC are affected by alternative splicing, which can be exploited in the search for novel targeted therapies.
Klin, Ami; Lang, Jason; Cicchetti, Domenic V.; Volkmar, Fred R.
2000-01-01
This study examined the inter-rater reliability of clinician-assigned diagnosis of autism using or not using the criteria specified in the Diagnostic and Statistical Manual IV (DSM-IV). For experienced raters there was little difference in reliability in the two conditions. However, a clinically significant improvement in diagnostic reliability…
Lazzaroni, Massimo
2012-01-01
This book gives a practical guide for designers and users in Information and Communication Technology context. In particular, in the first Section, the definition of the fundamental terms according to the international standards are given. Then, some theoretical concepts and reliability models are presented in Chapters 2 and 3: the aim is to evaluate performance for components and systems and reliability growth. Chapter 4, by introducing the laboratory tests, puts in evidence the reliability concept from the experimental point of view. In ICT context, the failure rate for a given system can be
Diaz-Espinosa, O
2006-01-01
We study the effect of noise on one--dimensional critical dynamical systems (that is, maps with a renormalization theory). We consider in detail two examples of such dynamical systems: unimodal maps of the interval at the accumulation of period--doubling and smooth homeomorphisms of the circle with a critical point and with golden mean rotation number. We show that, if we scale the space and the time, several properties of the noise (the cumulants or Wick--ordered moments) satisfy some scaling relations. A consequence of the scaling relations is that a version of the central limit theorem holds. Irrespective of the shape of the initial noise, if the bare noise is weak enough, the effective noise becomes close to Gaussian in several senses that we can make precise. We notice that the conclusions are false for maps with positive Lyapunov exponents. The method of analysis is close in spirit to the study of scaling limits in renormalization theory. We also perform several numerical experiments that confirm the ri...
Nothnagel H
2017-08-01
Full Text Available Helen Nothnagel,1,2,* Christian Puta,1,3,* Thomas Lehmann,4 Philipp Baumbach,5 Martha B Menard,6,7 Brunhild Gabriel,1 Holger H W Gabriel,1 Thomas Weiss,8 Frauke Musial2 1Department of Sports Medicine and Health Promotion, Friedrich Schiller University, Jena, Germany; 2Department of Community Medicine, National Research Center in Complementary and Alternative Medicine, UiT, The Arctic University of Norway, Tromsø, Norway; 3Center for Interdisciplinary Prevention of Diseases Related to Professional Activities, 4Department of Medical Statistics, Computer Sciences and Documentation, Friedrich Schiller University, 5Department of Anesthesiology and Intensive Care Medicine, University Hospital Jena, Germany; 6Crocker Institute, Kiawah Island, SC, 7School of Integrative Medicine and Health Sciences, Saybrook University, Oakland, CA, USA; 8Department of Biological and Clinical Psychology, Friedrich Schiller University, Jena, Germany *These authors contributed equally to this work Background: Quantitative sensory testing (QST is a diagnostic tool for the assessment of the somatosensory system. To establish QST as an outcome measure for clinical trials, the question of how similar the measurements are over time is crucial. Therefore, long-term reliability and limits of agreement of the standardized QST protocol of the German Research Network on Neuropathic Pain were tested. Methods: QST on the lower back and hand dorsum (dominant hand were assessed twice in 22 healthy volunteers (10 males and 12 females; mean age: 46.6±13.0 years, with sessions separated by 10.0±2.9 weeks. All measurements were performed by one investigator. To investigate long-term reliability and agreement of QST, differences between the two measurements, correlation coefficients, intraclass correlation coefficients (ICCs, Bland–Altman plots (limits of agreement, and standard error of measurement were used. Results: Most parameters of the QST were reliable over 10 weeks in
第五婷婷
2014-01-01
From the definition, purpose and the basic principle of rounding off for numerical values, and combined with the cases of rounding off for numerical values of each performance determination result in the GB/T 228.1-2010 "Metallic Materials Tensile Test 1st Part: Room Temperature Test Method", this paper explains the method of the rounding interval of rounding off for numerical values.%文章从数值修约的定义、目的及修约的基本原则出发，结合GB/T 228.1-2010《金属材料拉伸试验第1部分：室温试验方法》中各性能测定结果的数值修约实例，详细对各种数值修约间隔的修约方法做逐一说明。
Losiak, Anna; Czechowski, Leszek; Velbel, Michael A.
2015-12-01
Gypsum, a mineral that requires water to form, is common on the surface of Mars. Most of it originated before 3.5 Gyr when the Red Planet was more humid than now. However, occurrences of gypsum dune deposits around the North Polar Residual Cap (NPRC) seem to be surprisingly young: late Amazonian in age. This shows that liquid water was present on Mars even at times when surface conditions were as cold and dry as the present-day. A recently proposed mechanism for gypsum formation involves weathering of dust within ice (e.g., Niles, P.B., Michalski, J. [2009]. Nat. Geosci. 2, 215-220.). However, none of the previous studies have determined if this process is possible under current martian conditions. Here, we use numerical modelling of heat transfer to show that during the warmest days of the summer, solar irradiation may be sufficient to melt pure water ice located below a layer of dark dust particles (albedo ⩽ 0.13) lying on the steepest sections of the equator-facing slopes of the spiral troughs within martian NPRC. During the times of high irradiance at the north pole (every 51 ka; caused by variation of orbital and rotational parameters of Mars e.g., Laskar, J. et al. [2002]. Nature 419, 375-377.) this process could have taken place over larger parts of the spiral troughs. The existence of small amounts of liquid water close to the surface, even under current martian conditions, fulfils one of the main requirements necessary to explain the formation of the extensive gypsum deposits around the NPRC. It also changes our understanding of the degree of current geological activity on Mars and has important implications for estimating the astrobiological potential of Mars.
Deplano, V.; Pelissier, R.; Rieu, R.; Bontoux, P.
1994-01-01
Bifurcations are vascular singularities of interest because they are the privileged sites of atherosclerosis deposits, particularly the sites corresponding to wall shear stress extrema. The purpose of this paper is to compare the two- and three-dimensional characteristics of the velocity fields, the shear stress distributions and the secondary flows in a symmetrical aortic bifurcation. The branching angle is equal to 60^{circ} and the branch-to-trunk area ratio to 0.8. The numerical simulations are performed using the FIDAP programme. Although restrictive by the hypotheses of steady flow and rigid channel, with rectangular cross-sections, this study shows the importance of the three-dimensional effects in particular as far as concerned the wall shear stress behaviours. Les bifurcations sont des singularités vasculaires présentant un intérêt particulier car elles sont le site privilégié de dépôts athéromateux ; la localisation de ces dépôts dépendant des valeurs maximum du cisaillement en paroi. L'objectif de cette étude est de comparer les caractéristiques bidimensionnels et tridimensionnels des champs de vitesse, de la distribution du cisaillement pariétal et des écoulements secondaires dans un modèle de bifurcation aortique. L'angle de bifurcation est de 60^{circ} et le rapport des sections branche fille branche mère est de 0,8. Les simulations numériques sont effectuées sur la base du logiciel FIDAP. Bien que restrictifs de part certaines hypothèses, écoulement permanent dans un modèle de bifurcation rigide avec des sections rectangulaires, ces travaux montrent l'importance des effets tridimensionnels notamment au niveau du cisaillement pariétal.
Wallis John
2006-11-01
Full Text Available Abstract Background Cross-clamp fibrillation is a well established method of performing coronary grafting, but its clinical effect on the myocardium is unknown. We sought to measure these effects clinically using the Khuri Intramyocardial pH monitor. Methods 50 episodes of cross-clamping were recorded in 16 patients who underwent CABG with crossclamp-fibrillation. An Intramyocardial pH probe measured the level of acidosis in the anterior and posterior myocardium in real-time. The pH at the start and end of each period of cross-clamping was recorded. Results It became very apparent that the pH of some patients recovered quickly while others entirely failed to recover. Thus the patients were split into 2 groups according to whether the pH recovered to above 6.8 after the first crossclamp-release (N = 8 in each group. Initial pH was 7.133 (range 6.974–7.239. After the first period of crossclamping the pH dropped to 6.381 (range 6.034–6.684. The pH in recoverers prior to the second XC application was 6.990(range 6.808–7.222 compared to only 6.455 (range 6.200–6.737 in patient's whose myocardium did not recover (P Conclusion Crossclamp fibrillation does not result in reliable reperfusion of the myocardium between periods of crossclamping.
Rawat, A.; Aucan, J.; Ardhuin, F.
2012-12-01
All sea level variations of the order of 1 cm at scales under 30 km are of great interest for the future Surface Water Ocean Topography (SWOT) satellite mission. That satellite should provide high-resolution maps of the sea surface height for analysis of meso to sub-mesoscale currents, but that will require a filtering of all gravity wave motions in the data. Free infragravity waves (FIGWs) are generated and radiate offshore when swells and/or wind seas and their associated bound infragravity waves impact exposed coastlines. Free infragravity waves have dominant periods comprised between 1 and 10 minutes and horizontal wavelengths of up to tens of kilometers. Given the length scales of the infragravity waves wavelength and amplitude, the infragravity wave field will can a significant fraction the signal measured by the future SWOT mission. In this study, we analyze the data from recovered bottom pressure recorders of the Deep-ocean Assessment and Reporting of Tsunami (DART) program. This analysis includes data spanning several years between 2006 and 2010, from stations at different latitudes in the North and South Pacific, the North Atlantic, the Gulf of Mexico and the Caribbean Sea. We present and discuss the following conclusions: (1) The amplitude of free infragravity waves can reach several centimeters, higher than the precision sought for the SWOT mission. (2) The free infragravity signal is higher in the Eastern North Pacific than in the Western North Pacific, possibly due to smaller incident swell and seas impacting the nearby coastlines. (3) Free infragravity waves are higher in the North Pacific than in the North Atlantic, possibly owing to different average continental shelves configurations in the two basins. (4) There is a clear seasonal cycle at the high latitudes North Atlantic and Pacific stations that is much less pronounced or absent at the tropical stations, consistent with the generation mechanism of free infragravity waves. Our numerical model
Lane, J.W.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.
2000-01-01
The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons
任丽娜; 任帅; 王先芝; 刘宇
2014-01-01
This paper presented a reliability assessment method for numerical control machine tool based on bounded bathtub in-tensity process (BBIP)model.The method can assess the whole lifecycle reliability of numerical control (NC)machine tools in minimal repair.Bounded bathtub intensity function of failure times was built,and a formula for calculating the lasting time of ear-ly failure period was derived.The maximum likelihood estimation (MLE)for model parameters and reliability indices were given. The failure process of a single NC machine tool with failure truncation was analyzed.The results show that the lasting time of early failure period for NC machine tool is about 5 months.The estimated time is basically consistent with the actual situation.It is demonstrated that BBIP model can accurately evaluate the lasting time of early failure period and can provide a theoretical basis for improving the reliability of NC machine tools.%在最小维修情况下，为实现数控机床的全寿命周期可靠性评估，提出基于边界浴盆强度过程（bounded bathtub intensity process，BBIP）模型的数控机床可靠性评估方法。建立了故障时间的边界浴盆强度函数式，推导了早期故障期持续时间的计算公式，并给出了模型参数和可靠性指标的极大似然点估计。采用该评估方法分析了单台数控机床故障截尾的故障过程，结果表明：该数控机床早期故障期的持续时间大约为5个月，与机床的实际情况基本一致，说明BBIP模型可准确地评估早期故障期的持续时间，为提高机床可靠性提供了一定的理论依据。
Bøyesen, Pernille; McQueen, Fiona M; Gandjbakhch, Frédérique;
2011-01-01
The aim of this multireader exercise was to assess the reliability and sensitivity to change of the psoriatic arthritis magnetic resonance imaging score (PsAMRIS) in PsA patients followed for 1 year.......The aim of this multireader exercise was to assess the reliability and sensitivity to change of the psoriatic arthritis magnetic resonance imaging score (PsAMRIS) in PsA patients followed for 1 year....
Corrections to "Connectivity-Based Reliable Multicast MAC Protocol for IEEE 802.11 Wireless LANs"
Choi Woo-Yong
2010-01-01
Full Text Available We have found the errors in the throughput formulae presented in our paper "Connectivity-based reliable multicast MAC protocol for IEEE 802.11 wireless LANs". We provide the corrected formulae and numerical results.
Multidisciplinary System Reliability Analysis
Mahadevan, Sankaran; Han, Song; Chamis, Christos C. (Technical Monitor)
2001-01-01
The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code, developed under the leadership of NASA Glenn Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multidisciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.
Large scale experiments as a tool for numerical model development
Kirkegaard, Jens; Hansen, Erik Asp; Fuchs, Jesper;
2003-01-01
for improvement of the reliability of physical model results. This paper demonstrates by examples that numerical modelling benefits in various ways from experimental studies (in large and small laboratory facilities). The examples range from very general hydrodynamic descriptions of wave phenomena to specific......Experimental modelling is an important tool for study of hydrodynamic phenomena. The applicability of experiments can be expanded by the use of numerical models and experiments are important for documentation of the validity of numerical tools. In other cases numerical tools can be applied...... hydrodynamic interaction with structures. The examples also show that numerical model development benefits from international co-operation and sharing of high quality results....
Jurjiu, Aurel; Galiceanu, Mircea; Farcasanu, Alexandru; Chiriac, Liviu; Turcu, Flaviu
2016-12-01
In this paper, we focus on the relaxation dynamics of Sierpinski hexagon fractal polymer. The relaxation dynamics of this fractal polymer is investigated in the framework of the generalized Gaussian structure model using both Rouse and Zimm approaches. In the Rouse-type approach, by performing real-space renormalization transformations, we determine analytically the complete eigenvalue spectrum of the connectivity matrix. Based on the eigenvalues obtained through iterative algebraic relations we calculate the averaged monomer displacement and the mechanical relaxation moduli (storage modulus and loss modulus). The evaluation of the dynamical properties in the Rouse-type approach reveals that they obey scaling in the intermediate time/frequency domain. In the Zimm-type approach, which includes the hydrodynamic interactions, the relaxation quantities do not show scaling. The theoretical findings with respect to scaling in the intermediate domain of the relaxation quantities are well supported by experimental results.
Mashhour, M., E-mail: m.mashhour@ee.kntu.ac.i [Electrical Engineering Department of K.N. Toosi University of Technology, Tehran 16315-1355 (Iran, Islamic Republic of); Golkar, M.A., E-mail: Golkar@kntu.ac.i [The Electrical Engineering Department of K.N. Toosi University of Technology, Tehran 16315-1355 (Iran, Islamic Republic of); Moghaddas-Tafreshi, S.M., E-mail: tafreshi@eetd.kntu.ac.i [Electrical Engineering Department of K.N. Toosi University of Technology, Tehran 16315-1355 (Iran, Islamic Republic of)
2011-01-15
The present work is to show the application and implementation of the algorithms and models proposed in part I. It also represents the simulation results of (a) extracting a lumped financial model (the aggregated model) of the distribution system with distributed generations (DGs) and interruptible loads (ILs), (b) distribution company's (DISCO's) process of decision-making, based on the created financial model, on allocating its generating capability for internal usage and proposing to the hourly-ahead energy and reserve markets, and (c) a profit-based network reconfiguration methodology that increases the DISCO's technical ability and directs its financial affairs towards more profitable transactions in the upcoming markets. The function of the algorithms used for detecting unfeasible configurations, namely loop path and/or isolated part in the network are shown and well exemplified. Influential factors in DISCO's generating capability and in the coefficients of DISCO's internal cost function (ICF) are investigated. The present study substantiates the ICF-based optimization method by comparing the relevant results with the results obtained based on the use of total cost function (TCF). Several scenarios on market prices of energy and reserve and on the contingency probability factor pertaining to the real-time generation in reserve market are considered. Simulation results indicate that getting more economical benefits, DISCO may necessarily play different roles in the market and change the network configuration, at different hours.
Donmez, O
2006-01-01
The shocked wave created on the accretion disk after different physical phenomena (accretion flows with pressure gradients, star-disk interaction etc.) may be responsible observed Quasi Periodic Oscillations (QPOs) in $X-$ray binaries. We present the set of characteristics frequencies associated with accretion disk around the rotating and non-rotating black holes for one particle case. These persistent frequencies are results of the rotating pattern in an accretion disk. We compare the frequency's from two different numerical results for fluid flow around the non-rotating black hole with one particle case. The numerical results are taken from our papers Refs.\\refcite{Donmez2} and \\refcite{Donmez3} using fully general relativistic hydrodynamical code with non-selfgravitating disk. While the first numerical result has a relativistic tori around the black hole, the second one includes one-armed spiral shock wave produced from star-disk interaction. Some physical modes presented in the QPOs can be excited in nume...
Wang, Huihui; Sukhomlinov, Vladimir S.; Kaganovich, Igor D.; Mustafaev, Alexander S.
2017-02-01
Using the Monte Carlo collision method, we have performed simulations of ion velocity distribution functions (IVDF) taking into account both elastic collisions and charge exchange collisions of ions with atoms in uniform electric fields for argon and helium background gases. The simulation results are verified by comparison with the experiment data of the ion mobilities and the ion transverse diffusion coefficients in argon and helium. The recently published experimental data for the first seven coefficients of the Legendre polynomial expansion of the ion energy and angular distribution functions are used to validate simulation results for IVDF. Good agreement between measured and simulated IVDFs shows that the developed simulation model can be used for accurate calculations of IVDFs.
Ji, B.; Peng, X. X.; Long, X. P.; Luo, X. W.; Wu, Y. L.
2015-12-01
Results of cavitating turbulent flow simulation around a twisted hydrofoil were presented in the paper using the Partially-Averaged Navier-Stokes (PANS) method (Ji et al. 2013a), Large-Eddy Simulation (LES) (Ji et al. 2013b) and Reynolds-Averaged Navier-Stokes (RANS). The results are compared with available experimental data (Foeth 2008). The PANS and LES reasonably reproduce the cavitation shedding patterns around the twisted hydrofoil with primary and secondary shedding, while the RANS model fails to simulate the unsteady cavitation shedding phenomenon and yields an almost steady flow with a constant cavity shape and vapor volume. Besides, it is noted that the predicted shedding vapor cavity by PANS is more turbulent and the shedding vortex is stronger than that by LES, which is more consistent with experimental photos.
Influence of the quantum well models on the numerical simulation of planar InGaN/GaN LED results
Podgórski, J.; Woźny, J.; Lisik, Z.
2016-04-01
Within this paper, we present electric model of a light emitting diode (LED) made of gallium nitride (GaN) followed by examples of simulation results obtained by means of Sentaurus software, which is the part of the TCAD package. The aim of this work is to answer the question of whether physical models of quantum wells used in commercial software are suitable for a correct analysis of the lateral LEDs made of GaN.
Cao, Xinhua; Xu, Xiaoyin; Voss, Stephan
2017-03-01
In this paper, we describe an enhanced DICOM Secondary Capture (SC) that integrates Image Quantification (IQ) results, Regions of Interest (ROIs), and Time Activity Curves (TACs) with screen shots by embedding extra medical imaging information into a standard DICOM header. A software toolkit of DICOM IQSC has been developed to implement the SC-centered information integration of quantitative analysis for routine practice of nuclear medicine. Primary experiments show that the DICOM IQSC method is simple and easy to implement seamlessly integrating post-processing workstations with PACS for archiving and retrieving IQ information. Additional DICOM IQSC applications in routine nuclear medicine and clinic research are also discussed.
Alexey Petrunin; Stephan V. Sobolev; Z. Garfunkel; [Child, Sir Josiah, bart.]
2004-01-01
The continental transform boundary between the Arabian and African plates marked by the Dead Sea Transform (DST) accommodated ca 105 km of relative transform displacement during the last 15-20 Myr. The strike-slip deformation resulted in a string of the pull-apart basins along the DST, with up to 10 km thick sedimentary cover. The reconstruction of the pre-DST basement topography indicates that there was a crystalline basement high close to the DST trace between the Red Sea and the Dead Sea, ...
K. A. Trukhanov
2014-01-01
Full Text Available State-of-the-art machinery development enables people with lost lower limb to continue their previous life despite a loss. International companies dealing with this area pursue a minimization of human behaviour problems because of amputation. Researches to create an optimal design of the artificial knee joint are under way.The work task was to define analytical relationships of changing kinematic parameters of the human walking on the flat surface such as an angle of the knee joint, knee point (moment, definition of reduced knee actuator (A load, as well as to compare obtained results with experimental data.As an A in created design, the article proposes to use a controlled shock absorber based on the hydraulic cylinder.A knee unit is a kinematic two-tier mechanism. One of the mechanism links performs rotational motion, and the other is rotation-translational to provide a rotation of the first one.When studying the hydraulic actuator device dynamics, as a generalized coordinate a coordinate of the piston x (or ρ position is chosen while in the study of link movements an angle β is preferable.Experimental data are obtained for a human with the body weight of 57.6 kg walking on the flat surface to estimate a value of the knee joint angle, speed, acceleration, torque, and capacity in the knee joint and are taken from the published works of foreign authors.A trigonometric approximation was used for fitting the experimental data. The resulting dependence of the reduced load on the stock of A is necessary to perform the synthesis of A. The criterion for linear mechanisms mentioned in the D.N. Popov’s work is advisable to use as a possible criterion for optimization of A.The results obtained are as follows:1. Kinematics linkage mechanism is described using relationships for dependencies of its geometrical parameters, namely a cylinder piston stroke x (or ρ and a links angle β.2. Obtained polynomials of kinematic relationships allow a synthesis of
Renard, Francois; Hellmann, Roland; Collombet, Marielle; Guen, Yvi Le
2008-01-01
When carbon dioxide (CO2) is injected into an aquifer or a depleted geological reservoir, its dissolution into solution results in acidification of the pore waters. As a consequence, the pore waters become more reactive, which leads to enhanced dissolution-precipitation processes and a modification of the mechanical and hydrological properties of the rock. This effect is especially important for limestones given that the solubility and reactivity of carbonates is strongly dependent on pH and the partial pressure of CO2. The main mechanism that couples dissolution, precipitation and rock matrix deformation is commonly referred to as intergranular pressure solution creep (IPS) or pervasive pressure solution creep (PSC). This process involves dissolution at intergranular grain contacts subject to elevated stress, diffusion of dissolved material in an intergranular fluid, and precipitation in pore spaces subject to lower stress. This leads to an overall and pervasive reduction in porosity due to both grain indent...
Ndiaye, L G; Caillat, S; Chinnayya, A; Gambier, D; Baudoin, B
2010-07-01
In order to simulate granular materials structure in a rotary kiln under the steady-state regime, a mathematical model has been developed by Saeman (1951). This model enables the calculation of the bed profiles, the axial velocity and solids flow rate along the kiln. This model can be coupled with a thermochemical model, in the case of a reacting moving bed. This dynamic model was used to calculate the bed profile for an industrial size kiln and the model projections were validated by measurements in a 4 m diameter by 16 m long industrial rotary kiln. The effect of rotation speed under solids bed profile and the effect of the feed rate under filling degree were established. On the basis of the calculations and the experimental results a phenomenological relation for the residence time estimation was proposed for the rotary kiln.
Tamiya, K.; Tamagaki, R.
1981-10-01
Results obtained by applying a formulation based on the reaction matrix theory developed in I are given. Calculations by making use of a modified realistic potential, the Reid soft-core potential with the OPEP-part enhanced due to the isobar (Δ)-mixing, show that the transition to the [ALS] phase of quasi-neutrons corresponding to a typical π0 condensation occurs in the region of (2 ˜ 3) times the nuclear density. The most important ingredients responsible for this transition are the growth of the attractive 3P2 + 3F2 contribution mainly from the spin-parallel pairs in the same leyers and the reduction of the repulsive 3P1 contribution mainly from the spin-antiparallel pairs in the nearest layers; these mainfest themselves as the [ALS]-type localization develops. Properties of the matter under the new phase thus obtained such as the shape of the Fermi surface and the effective mass are discussed.
Humeau, Anne; Buard, Benjamin; Chapeau-Blondeau, Francois; Rousseau, David [Laboratoire d' Ingenierie des Systemes Automatises (LISA), Universite d' Angers, 62 avenue Notre Dame du Lac, 49000 Angers (France); Mahe, Guillaume; Abraham, Pierre, E-mail: anne.humeau@univ-angers.f [Laboratoire de Physiologie et d' Explorations Vasculaires, UMR CNRS 6214-INSERM 771, Centre Hospitalier Universitaire d' Angers, 49033 Angers cedex 01 (France)
2010-10-21
To contribute to the understanding of the complex dynamics in the cardiovascular system (CVS), the central CVS has previously been analyzed through multifractal analyses of heart rate variability (HRV) signals that were shown to bring useful contributions. Similar approaches for the peripheral CVS through the analysis of laser Doppler flowmetry (LDF) signals are comparatively very recent. In this direction, we propose here a study of the peripheral CVS through a multifractal analysis of LDF fluctuations, together with a comparison of the results with those obtained on HRV fluctuations simultaneously recorded. To perform these investigations concerning the biophysics of the CVS, first we have to address the problem of selecting a suitable methodology for multifractal analysis, allowing us to extract meaningful interpretations on biophysical signals. For this purpose, we test four existing methodologies of multifractal analysis. We also present a comparison of their applicability and interpretability when implemented on both simulated multifractal signals of reference and on experimental signals from the CVS. One essential outcome of the study is that the multifractal properties observed from both the LDF fluctuations (peripheral CVS) and the HRV fluctuations (central CVS) appear very close and similar over the studied range of scales relevant to physiology.
Humeau, Anne; Buard, Benjamin; Mahé, Guillaume; Chapeau-Blondeau, François; Rousseau, David; Abraham, Pierre
2010-10-01
To contribute to the understanding of the complex dynamics in the cardiovascular system (CVS), the central CVS has previously been analyzed through multifractal analyses of heart rate variability (HRV) signals that were shown to bring useful contributions. Similar approaches for the peripheral CVS through the analysis of laser Doppler flowmetry (LDF) signals are comparatively very recent. In this direction, we propose here a study of the peripheral CVS through a multifractal analysis of LDF fluctuations, together with a comparison of the results with those obtained on HRV fluctuations simultaneously recorded. To perform these investigations concerning the biophysics of the CVS, first we have to address the problem of selecting a suitable methodology for multifractal analysis, allowing us to extract meaningful interpretations on biophysical signals. For this purpose, we test four existing methodologies of multifractal analysis. We also present a comparison of their applicability and interpretability when implemented on both simulated multifractal signals of reference and on experimental signals from the CVS. One essential outcome of the study is that the multifractal properties observed from both the LDF fluctuations (peripheral CVS) and the HRV fluctuations (central CVS) appear very close and similar over the studied range of scales relevant to physiology.
G-A. Tselentis
2010-05-01
Full Text Available In spite of the fact that the great majority of seismic tsunami is generated in ocean domains, smaller basins like the Ionian Sea sometimes experience this phenomenon. In this investigation, we study the tsunami hazard associated with the Ionian Sea fault system.
A scenario-based method is used to provide an estimation of the tsunami hazard in this region for the first time. Realistic faulting parameters related to four probable seismic sources, with tsunami potential, are used to model expected coseismic deformation, which is translated directly to the water surface and used as an initial condition for the tsunami propagation.
We calculate tsunami propagation snapshots and mareograms for the four seismic sources in order to estimate the expected values of tsunami maximum amplitudes and arrival times at eleven tourist resorts along the Ionian shorelines.
The results indicate that, from the four examined sources, only one possesses a seismic threat causing wave amplitudes up to 4 m at some tourist resorts along the Ionian shoreline.
Howard, Melissa M.; Weiler, Robert M.; Haddox, J. David
2009-01-01
Background: The purpose of this study was to develop and test the reliability of self-report survey items designed to monitor the nonmedical use of prescription drugs among adolescents. Methods: Eighteen nonmedical prescription drug items designed to be congruent with the substance abuse items in the US Centers for Disease Control and Prevention's…
Baker, John G.
2009-01-01
Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.
Baker, John G.
2009-01-01
Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.
Reliability sensitivity-based correlation coefficient calculation in structural reliability analysis
Yang, Zhou; Zhang, Yimin; Zhang, Xufang; Huang, Xianzhen
2012-05-01
The correlation coefficients of random variables of mechanical structures are generally chosen with experience or even ignored, which cannot actually reflect the effects of parameter uncertainties on reliability. To discuss the selection problem of the correlation coefficients from the reliability-based sensitivity point of view, the theory principle of the problem is established based on the results of the reliability sensitivity, and the criterion of correlation among random variables is shown. The values of the correlation coefficients are obtained according to the proposed principle and the reliability sensitivity problem is discussed. Numerical studies have shown the following results: (1) If the sensitivity value of correlation coefficient ρ is less than (at what magnitude 0.000 01), then the correlation could be ignored, which could simplify the procedure without introducing additional error. (2) However, as the difference between ρ s, that is the most sensitive to the reliability, and ρ R , that is with the smallest reliability, is less than 0.001, ρ s is suggested to model the dependency of random variables. This could ensure the robust quality of system without the loss of safety requirement. (3) In the case of | E abs|>0.001 and also | E rel|>0.001, ρ R should be employed to quantify the correlation among random variables in order to ensure the accuracy of reliability analysis. Application of the proposed approach could provide a practical routine for mechanical design and manufactory to study the reliability and reliability-based sensitivity of basic design variables in mechanical reliability analysis and design.
2017-01-17
convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report was cleared for public release...testing for reliability prediction of devices exhibiting multiple failure mechanisms. Also presented was an integrated accelerating and measuring ...13 Table 2 T, V, F and matrix versus measured FIT
Reliability Impacts in Life Support Architecture and Technology Selection
Lange Kevin E.; Anderson, Molly S.
2012-01-01
Quantitative assessments of system reliability and equivalent system mass (ESM) were made for different life support architectures based primarily on International Space Station technologies. The analysis was applied to a one-year deep-space mission. System reliability was increased by adding redundancy and spares, which added to the ESM. Results were thus obtained allowing a comparison of the ESM for each architecture at equivalent levels of reliability. Although the analysis contains numerous simplifications and uncertainties, the results suggest that achieving necessary reliabilities for deep-space missions will add substantially to the life support ESM and could influence the optimal degree of life support closure. Approaches for reducing reliability impacts were investigated and are discussed.
Westphalen, H.; Spjeldvik, W. N.
1982-01-01
A theoretical method by which the energy dependence of the radial diffusion coefficient may be deduced from spectral observations of the particle population at the inner edge of the earth's radiation belts is presented. This region has previously been analyzed with numerical techniques; in this report an analytical treatment that illustrates characteristic limiting cases in the L shell range where the time scale of Coulomb losses is substantially shorter than that of radial diffusion (L approximately 1-2) is given. It is demonstrated both analytically and numerically that the particle spectra there are shaped by the energy dependence of the radial diffusion coefficient regardless of the spectral shapes of the particle populations diffusing inward from the outer radiation zone, so that from observed spectra the energy dependence of the diffusion coefficient can be determined. To insure realistic simulations, inner zone data obtained from experiments on the DIAL, AZUR, and ESRO 2 spacecraft have been used as boundary conditions. Excellent agreement between analytic and numerical results is reported.
N. A. Nayak
1960-05-01
Full Text Available The reliability aspect of electronic equipment's is discussed. To obtain optimum results, close cooperation between the components engineer, the design engineer and the production engineer is suggested.
Fatigue reliability based on residual strength model with hybrid uncertain parameters
Jun Wang; Zhi-Ping Qiu
2012-01-01
The aim of this paper is to evaluate the fatigue reliability with hybrid uncertain parameters based on a residual strength model.By solving the non-probabilistic setbased reliability problem and analyzing the reliability with randomness,the fatigue reliability with hybrid parameters can be obtained.The presented hybrid model can adequately consider all uncertainties affecting the fatigue reliability with hybrid uncertain parameters.A comparison among the presented hybrid model,non-probabilistic set-theoretic model and the conventional random model is made through two typical numerical examples.The results show that the presented hybrid model,which can ensure structural security,is effective and practical.
水力喷砂射流器切割效果数值模拟%Numerical Simulation on Cutting Results of Sandblast Perforation
李朝阳; 马贵阳; 田丽
2011-01-01
为了有效地保持油田的稳产增产,科学工作者提出了用于切割、破岩和清洗的水力喷砂射流技术.它能增加弹道的穿透深度,减少压实伤害,改善压裂效果.因为对水力喷砂射流机理、影响因素研究的不够深入及成本高等因素,在很长一段时间内水力喷砂射流技术未能得到广泛应用.迅速发展的计算机技术与日益成熟的计算流体力学,为水力喷砂器的数值研究提供了可靠途径.采用计算流体力学的方法,利用仿真软件,对不同磨料密度、粒径和喷射速度下的喷砂器工作情况进行了数值研究.切割口处的压力随颗粒直径和射流速度的增加而增加,随粒径的增加而减少.这一研究结果,可为水力喷砂射流器优化方案的研究提供理论基础.%In order to effectively maintain a stable crude oil production, scientific workers put forward a hydraulic sandblasting jet technology for cutting, rock fragmentation and cleaning. It can increase the penetration depth, reduce ballistic compaction damage, and improve the fracturing effect. Due to the factors of superficial study and high cost, it failed to get extensive application over a long period of time. Rapid development of computer technology and increasingly mature computational fluid dynamics for hydraulic provides a reliable way to injection desander numerical study. Using computational fluid dynamics method and simulation software, the different abrasive density, size and jet speed spray desander working conditions were on the numerical researched. Pressure of cutting sewing place increases with particle diameter and jet speed ,but decreases with particle size. It provides the improvement of sandblast Perforation with basis theory.
HAN Guijun; LI Wei; HE Zhongjie; LIU Kexiu; MA Jirui
2006-01-01
In order to obtain an accurate tide description in the China Seas, the 2-dimensional nonlinear numerical Princeton Ocean Model (POM) is employed to incorporate in situ tidal measurements both from tide gauges and TOPEX/POSEIDON (T/P) derived datasets by means of the variational adjoint approach in such a way that unknown internal model parameters, bottom topography, friction coefficients and open boundary conditions, for example, are adjusted during the process. The numerical model is used as a forward model. After the along-track T/P data are processed, two classical methods, i.e. harmonic and response analysis, are implemented to estimate the tide from such datasets with a domain covering the model area extending from 0° to 41°N in latitude and from 99°E to 142°E in longitude. And the results of these two methods are compared and interpreted. The numerical simulation is performed for 16 major constituents. In the data assimilation experiments, three types of unknown parameters (water depth, bottom friction and tidal open boundary conditions in the model equations) are chosen as control variables. Among the various types of data assimilation experiments, the calibration of water depth brings the most promising results. By comparing the results with selected tide gauge data, the average absolute errors are decreased from 7.9 cm to 6.8 cm for amplitude and from 13.0° to 9.0° for phase with respect to the semidiurnal tide M2 constituent, which is the largest tidal constituent in the model area. After the data assimilation experiment is performed, the comparison between model results and tide gauge observation for water levels shows that the RMS errors decrease by 9 cm for a total of 14 stations, mostly selected along the coast of Mainland China, when a one-month period is considered, and the correlation coefficients improve for most tidal stations among these stations.
Gaidies, F.; de Capitani, C.; Abart, R.; Schuster, R.
2008-06-01
Garnet in metapelites from the Wölz Complex of the Austroalpine crystalline basement east of the Tauern Window characteristically consists of two growth phases, which preserve a comprehensive record of the geothermal history during polymetamorphism. From numerical modelling of garnet formation, detailed information on the pressure temperature time ( P T t) evolution during prograde metamorphism is obtained. In that respect, the combined influences of chemical fractionation associated with garnet growth, modification of the original growth zoning through intragranular diffusion and the nucleation history on the chemical zoning of garnet as P and T change during growth are considered. The concentric chemical zoning observed in garnet and the homogenous rock matrix, which is devoid of chemical segregation, render the simulation of garnet growth through successive equilibrium states reliable. Whereas the first growth phase of garnet was formed at isobaric conditions of ˜3.8 kbar at low heating/cooling rates, the second growth phase grew along a Barrovian P T path marked with a thermal peak of ˜625°C at ˜10 kbar and a maximum in P of ˜10.4 kbar at ˜610°C. For the heating rate during the growth of the second phase of garnet, average rates faster than 50°C Ma-1 are obtained. From geochronological investigations the first growth phase of garnet from the Wölz Complex pertains to the Permian metamorphic event. The second growth phase grew in the course of Eo-Alpine metamorphism during the Cretaceous.
曹宇男; 张辉; 叶佩青; 王田苗
2011-01-01
As a distributed computing system, a CNC system needs to be operated reliably, dependably and safely. How to design reliable and dependable software and perform effective verification for CNC systems becomes an important research problem. A new modeling method called TTM/ATRTTL (Timed Transition Models/All-Time Real-Time Temporal Logics) for specifying CNC systems was proposed. TTM/ATRTTL provided full support for specifying hard real-time and feedback that were needed for modeling CNC systems. A verification framework was proposed with verification rules and theorems and it was implemented with STeP and SF2STeP. The proposed verification framework could check reliability, dependability and safety of systems specified by the TTM/ATRTTL method. The modeling and verification techniques on an open architecture CNC (OAC) system were applied and comprehensive studies on modeling and verifying a logical controller were conducted that was the key part of OAC. The results show that the method can effectively model and verify CNC systems and generate CNC software that can satisfy system requirements in reliability, dependability and safety.%作为一个典型的离散计算机控制系统,CNC(数字控制)系统在运行中需要满足可靠性和安全性.因此如何设计出安全可靠的系统软件以及如何有效地对CNC系统的安全性和可靠性进行验证成为一个非常重要的问题.基于此给出一个新的建模方法TTM/ATRTTL (时间转化模型/全时轴实时时态逻辑)来描述和验证CNC系统.TTM/ATRTTL提供了一整套方法用于描述CNC系统建模的硬实时特性和反馈特性,也提供了一个包括一整套验征规则和定理的验证模型并且应用工具STeP和SF2STeP来实现之.这个验证模型可以用于对TTM/ATRTTL表达的系统的可靠性,安全性进行验证.使用该建模和验证方法可以对OAC(开放式体系结构CNC)系统进行分析和验证,并设计出OAC的逻辑控制器,该控制器是OAC系
丁皓江; 徐荣桥; 国凤林
1999-01-01
Emphasis is placed on purely elastic circular plates. Let the piezoelectric coefficients be equal to zero. Then two sets of uncoupled mechanical and electric equations are obtained and they can be solved independently. Two three-dimensional exact solutions of laminated transversely isotropic circular plate are derived under two boundary conditions, i.e. rigid slipping support and elastic simple support. For isotropic circular plates, the problem of multiple root is treated. At last, some numerical results of piezoelectric and purely elastic circular plates are presented and the applicability of classical plate theory is discussed.
Wachowicz-Pyzik, A.; Sowiżdżał, A.; Pająk, L.
2016-09-01
The numerical modeling enables us to reduce the risk related to the selection of best localization of wells. Moreover, at the stage of production, modeling is a suitable tool for optimization of well operational parameters, which guarantees the long life of doublets. The thorough selection of software together with relevant methodology applied to generation of numerical models significantly improve the quality of obtained results. In the following paper, we discuss the impact of density of calculation grid on the results of geothermal doublet simulation with the TOUGH2 code, which applies the finite-difference method. The study area is located between the Szczecin Trough and the Fore-sudetic Monocline, where the Choszczno IG-1 well has been completed. Our research was divided into the two stages. At the first stage, we examined the changes of density of polygon calculation grids used in computations of operational parameters of geothermal doublets. At the second stage, we analyzed the influence of distance between the production and the injection wells on variability in time of operational parameters. The results demonstrated that in both studied cases, the largest differences occurred in pressures measured in production and injection wells whereas the differences in temperatures were less pronounced.
Reliability Analysis and Modeling of ZigBee Networks
Lin, Cheng-Min
The architecture of ZigBee networks focuses on developing low-cost, low-speed ubiquitous communication between devices. The ZigBee technique is based on IEEE 802.15.4, which specifies the physical layer and medium access control (MAC) for a low rate wireless personal area network (LR-WPAN). Currently, numerous wireless sensor networks have adapted the ZigBee open standard to develop various services to promote improved communication quality in our daily lives. The problem of system and network reliability in providing stable services has become more important because these services will be stopped if the system and network reliability is unstable. The ZigBee standard has three kinds of networks; star, tree and mesh. The paper models the ZigBee protocol stack from the physical layer to the application layer and analyzes these layer reliability and mean time to failure (MTTF). Channel resource usage, device role, network topology and application objects are used to evaluate reliability in the physical, medium access control, network, and application layers, respectively. In the star or tree networks, a series system and the reliability block diagram (RBD) technique can be used to solve their reliability problem. However, a division technology is applied here to overcome the problem because the network complexity is higher than that of the others. A mesh network using division technology is classified into several non-reducible series systems and edge parallel systems. Hence, the reliability of mesh networks is easily solved using series-parallel systems through our proposed scheme. The numerical results demonstrate that the reliability will increase for mesh networks when the number of edges in parallel systems increases while the reliability quickly drops when the number of edges and the number of nodes increase for all three networks. More use of resources is another factor impact on reliability decreasing. However, lower network reliability will occur due to
Migliore, Juan
2012-01-01
An unpublished example due to Joe Harris from 1983 (or earlier) gave two smooth space curves with the same Hilbert function, but one of the curves was arithmetically Cohen-Macaulay (ACM) and the other was not. Starting with an arbitrary homogeneous ideal in any number of variables, we give two constructions, each of which produces, in a finite number of steps, an ideal with the Hilbert function of a codimension two ACM subscheme. We call the subscheme associated to such an ideal "numerically ACM." We study the connections between these two constructions, and in particular show that they produce ideals with the same Hilbert function. We call the resulting ideal from either construction a "numerical Macaulification" of the original ideal. Specializing to the case where the ideals are unmixed of codimension two, we show that (a) every even liaison class, $\\mathcal L$, contains numerically ACM subschemes, (b) the subset, $\\mathcal M$, of numerically ACM subschemes in $\\mathcal L$ has, by itself, a Lazarsfeld-Rao ...
da Silva, R A; Larivière, C; Arsenault, A B; Nadeau, S; Plamondon, A
2008-01-01
The purpose of this study was to compare the electromyographic (EMG) fatigue indices computed from short-time Fourier transform (STFT) and wavelet transform (WAV), by analyzing their criterion validity and test-retest reliability. The effect of averaging spectral estimates within and between repeated contractions (cycles) on EMG fatigue indices was also demonstrated. Thirty-one healthy subjects performed trunk flexion-extension cycles until exhaustion on a Biodex dynamometer. The load was determined theoretically as twice the L5-S1 moment produced by the trunk mass. To assess reliability, 10 subjects performed the same experimental protocol after a two-week interval. EMG signals were recorded bilaterally with 12 pairs of electrodes placed on the back muscles (at L4, L3, L1 and T10 levels), as well as on the gluteus maximus and biceps femoris. The endurance time and perceived muscle fatigue (Borg CR-10 scale) were used as fatigue criteria. EMG signals were processed using STFT and WAV to extract global (e.g, median frequency and instantaneous median frequency, respectively) or local (e.g., intensity contained in 8 frequency bands) information from the power spectrum. The slope values of these variables over time, obtained from regression analyses, were retained as EMG fatigue indices. EMG fatigue indices (STFT vs. WAV) were not significantly different within each muscle, had a variable association (Pearson's r range.: 0.06 to 0.68) with our fatigue criteria, and showed comparable reliability (Intra-class correlation range: 0.00 to 0.88), although they varied between muscles. The effect of averaging, within and between cycles, contributed to the strong association between EMG fatigue indices computed from STFT and WAV. As for EMG spectral indices of muscle fatigue, the conclusion is that both transforms carry essentially the same information.
Perrin, G; Goutelle, A; Pierluca, P; Chacornac, R; Allegre, G E
1977-01-01
The Doppler ultrasound diagnosis of carotid artery stenosis (asymetrical systolic and diastolic flows; elevated resistance index: ratio of flow pulse amplitude to systolic and diastolic values; flow reversal in the ophtalmic artery) is compared, in 52 patients, to the clinical, angiographic (40 patients) an surgical findings and to the peroperative measure of intra-arterial pressure and flow (30 patients). Its reliability is proved as a guide for angiographic exploration and for postoperative watching, but it is restricted to great vessels (cervical carotid artery) and is unable to detect ulcerated plate without stenosis.
孔祥雄; 史铁花; 程绍革; 王军; 周健; 陈锴; 施红军; 汤捷; 蔡涛
2013-01-01
In order to study the seismic behavior of Wuhan Center,a 1/40 scale structural model was made and tested on a shaking table.Based on the test results,numerical simulation study of modal analysis and dynamic response analysis were done by using two finite element models which were built by ETABS and ABAQUS.The simulation results and shaking table results including natural vibration period,vibrational modes,acceleration responses and displacement responses were compared.The strain of critical members of finite element models and test model were also discussed.Study results indicate that the parameters of finite element model are rational,and the numerical simulation results are basically identical with the test results.So the simulation results can prove the reliability of test results.%为研究武汉中心结构的抗震性能,按照1∶40的缩尺比例制作了结构缩尺模型并进行了振动台试验.根据振动台试验结果,采用ETABS和ABAQUS软件针对试验缩尺模型建立有限元模型,进行了包括模态分析和动力时程分析在内的数值模拟研究.将有限元模型的周期、振型、加速度反应和位移反应等结果与试验实测结果做比较,并探讨了有限元模型构件应变与试验实测应变的规律.研究结果显示,有限元模型参数取值准确,数值模拟分析结果与振动台试验结果基本一致,具有相似的规律性,同时也验证了试验结果的可靠性.
Reliability models of belt drive systems under slipping failure mode
Peng Gao
2017-01-01
Full Text Available Conventional reliability assessment and reliability-based optimal design of belt drive are based on the stress–strength interference model. However, the stress–strength interference model is essentially a static model, and the sensitivity analysis of belt drive reliability with respect to design parameters needs further investigations. In this article, time-dependent factors that contribute the dynamic characteristics of reliability are pointed out. Moreover, dynamic reliability models and failure rate models of belt drive systems under the failure mode of slipping are developed. Furthermore, dynamic sensitivity models of belt drive reliability based on the proposed dynamic reliability models are proposed. In addition, numerical examples are given to illustrate the proposed models and analyze the influences of design parameters on dynamic characteristics of reliability, failure rate, and sensitivity functions. The results show that the statistical properties of design parameters have different influences on reliability and failure rate of belt drive in cases of different values of design parameters and different operational durations.
Paweł WRONA
2016-07-01
Full Text Available The paper presents the results of numerical simulations into the distribution of methane concentration at the intersec-tion of two excavations with a fan (turned on giving the air stream to the area of the crossing. Assumed case represents emergency situation related to the unexpected flow of methane from an excavation and its mixing with fresh air. It is possible when sudden gas outburst takes place, methane leaks from methane drainage system or gas leaks out the pipelines of underground coal gasification devices. Three options were considered – corresponding to three different speeds of the jet fan. They represent three stages of fan work. First – low air speed is forced by a pneumatic fan, when electricity is cut off after high methane concentration detection. Medium speed can be forced by pneumatic-electric device when methane concentration allows to turn on the electricity. Third, the highest speed is for electric fans. Simula-tions were carried out in the Fire Dynamics Simulator (FDS belongs to the group of programs Computational Fluid Dy-namics (CFD. The governing equations are being solved in a numerical way. It was shown that proposed solution allows partial dilution of methane in every variant of speed what should allow escape of the miners from hazardous area.
Saiz, P; Rocha, R; Andreeva, J
2007-01-01
We are offering a system to track the efficiency of different components of the GRID. We can study the performance of both the WMS and the data transfers At the moment, we have set different parts of the system for ALICE, ATLAS, CMS and LHCb. None of the components that we have developed are VO specific, therefore it would be very easy to deploy them for any other VO. Our main goal is basically to improve the reliability of the GRID. The main idea is to discover as soon as possible the different problems that have happened, and inform the responsible. Since we study the jobs and transfers issued by real users, we see the same problems that users see. As a matter of fact, we see even more problems than the end user does, since we are also interested in following up the errors that GRID components can overcome by themselves (like for instance, in case of a job failure, resubmitting the job to a different site). This kind of information is very useful to site and VO administrators. They can find out the efficien...
Buras, R; Janka, H T; Kifonidis, K
2005-01-01
Supernova models with a full spectral treatment of the neutrino transport are presented, employing the Prometheus/Vertex neutrino-hydrodynamics code with a ``ray-by-ray plus'' approximation for treating two- (or three-) dimensional problems. The method is described in detail and critically assessed with respect to its capabilities, limitations, and inaccuracies in the context of supernova simulations. In this first paper of a series, 1D and 2D core-collapse calculations for a (nonrotating) 15 M_sun star are discussed, uncertainties in the treatment of the equation of state -- numerical and physical -- are tested, Newtonian results are compared with simulations using a general relativistic potential, bremsstrahlung and interactions of neutrinos of different flavors are investigated, and the standard approximation in neutrino-nucleon interactions with zero energy transfer is replaced by rates that include corrections due to nucleon recoil, thermal motions, weak magnetism, and nucleon correlations. Models with t...
The rating reliability calculator
Solomon David J
2004-04-01
Full Text Available Abstract Background Rating scales form an important means of gathering evaluation data. Since important decisions are often based on these evaluations, determining the reliability of rating data can be critical. Most commonly used methods of estimating reliability require a complete set of ratings i.e. every subject being rated must be rated by each judge. Over fifty years ago Ebel described an algorithm for estimating the reliability of ratings based on incomplete data. While his article has been widely cited over the years, software based on the algorithm is not readily available. This paper describes an easy-to-use Web-based utility for estimating the reliability of ratings based on incomplete data using Ebel's algorithm. Methods The program is available public use on our server and the source code is freely available under GNU General Public License. The utility is written in PHP, a common open source imbedded scripting language. The rating data can be entered in a convenient format on the user's personal computer that the program will upload to the server for calculating the reliability and other statistics describing the ratings. Results When the program is run it displays the reliability, number of subject rated, harmonic mean number of judges rating each subject, the mean and standard deviation of the averaged ratings per subject. The program also displays the mean, standard deviation and number of ratings for each subject rated. Additionally the program will estimate the reliability of an average of a number of ratings for each subject via the Spearman-Brown prophecy formula. Conclusion This simple web-based program provides a convenient means of estimating the reliability of rating data without the need to conduct special studies in order to provide complete rating data. I would welcome other researchers revising and enhancing the program.
Beniaiche, Ahmed; Ghenaiet, Adel; Facchini, Bruno
2017-02-01
The aero-thermal behavior of the flow field inside 30:1 scaled model reproducing an innovative smooth trailing edge of shaped wedge discharge duct with one row of enlarged pedestals have been investigated in order to determine the effect of rotation, inlet velocity and blowing conditions effects, for Re = 20,000 and 40,000 and Ro = 0-0.23. Two configurations are presented: with and without open tip configurations. Thermo-chromic liquid crystals technique is used to ensure a local measurement of the heat transfer coefficient on the blade suction side under stationary and rotation conditions. Results are reported in terms of detailed 2D HTC maps on the suction side surface as well as the averaged Nusselt number inside the pedestal ducts. Two correlations are proposed, for both closed and open tip configurations, based on the Re, Pr, Ro and a new non-dimensional parameter based on the position along the radial distance, to assess a reliable estimation of the averaged Nusselt number at the inter-pedestal region. A good agreement is found between prediction and experimental data with about ±10 to ±12 % of uncertainty, for the simple form correlation, and about ±16 % using a complex form. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.
Mazoyer, Johan; Pueyo, Laurent; Norman, Colin; N'Diaye, Mamadou; van der Marel, Roeland P.; Soummer, Rémi
2016-03-01
The new frontier in the quest for the highest contrast levels in the focal plane of a coronagraph is now the correction of the large diffraction artifacts introduced at the science camera by apertures of increasing complexity. Indeed, the future generation of space- and ground-based coronagraphic instruments will be mounted on on-axis and/or segmented telescopes; the design of coronagraphic instruments for such observatories is currently a domain undergoing rapid progress. One approach consists of using two sequential deformable mirrors (DMs) to correct for aberrations introduced by secondary mirror structures and segmentation of the primary mirror. The coronagraph for the WFIRST-AFTA mission will be the first of such instruments in space with a two-DM wavefront control system. Regardless of the control algorithm for these multiple DMs, they will have to rely on quick and accurate simulation of the propagation effects introduced by the out-of-pupil surface. In the first part of this paper, we present the analytical description of the different approximations to simulate these propagation effects. In Appendix A, we prove analytically that in the special case of surfaces inducing a converging beam, the Fresnel method yields high fidelity for simulations of these effects. We provide numerical simulations showing this effect. In the second part, we use these tools in the framework of the active compensation of aperture discontinuities (ACAD) technique applied to pupil geometries similar to WFIRST-AFTA. We present these simulations in the context of the optical layout of the high-contrast imager for complex aperture telescopes, which will test ACAD on a optical bench. The results of this analysis show that using the ACAD method, an apodized pupil Lyot coronagraph, and the performance of our current DMs, we are able to obtain, in numerical simulations, a dark hole with a WFIRST-AFTA-like. Our numerical simulation shows that we can obtain contrast better than 2×10-9 in
Cram, Jennifer M.; Pielke, Roger A.; Cotton, William R.
1992-01-01
Results of an observational and numerical study of the squall line that occurred on June 17-18, 1978, are presented. This squall line was initially triggered by the strong surface convergence along a cold front and stretched from Illinois to the Texas Panhandle. The squall line was aligned with the surface front during its initial development, but then propagated faster than the front, resulting in a separation of approximately 200 km by 0300 UTC and 300-400 km by 0600 UTC. The Colorado State University Regional Atmospheric Modeling System is used to model the squall-line development and propagation. Results are described from several experiments that tested the sensitivity to the use of the Kuo-type cumulus parameterization scheme and grid-scale microphysical processes. The movement of the squall line in the model is shown to be due to the propagation of a deep tropospheric internal gravity wave in a CISK-like process. The thermal and dynamic perturbations associated with the hypothesized wave are shown to be consistent with internal gravity wave theory.
Bagdasaryan, Gevorg Y.
2016-06-01
Full Text Available A comprehensive theoretical analysis of a dynamic thermo-ferro-electric pre-stressed bimorph energy harvester is performed. The analysis also takes into account pyroelectric and thermal expansion effects. The most general analytical expression for the energy conversation coefficients are presented for bi-layer. These coefficients we derive for more general situation when mechanical, electrical, thermal fields are present. We derive coefficients (transformation coefficients for sensing, actuating, and energy harvesting. As a particular case, we derive an analytical expression for the energy harvesting coefficient due to pyroelectric and thermal expansion effects in a rater general situation. This is a function of material properties, location of boundary conditions, vibration frequency, and in plane compressive/tensile follower force. Numerical simulations of the analytical results are presented. Effects of volume fraction, material properties, applied mechanical loads, and boundary conditions on the harvesting coefficients are introduced in the figures. The results for a cantilever and a simply-supported plate-layer are obtained as particular cases. The result for a low frequency (static system is obtained as a particular case by approaching the vibration frequency to zero. It is shown that volume fraction, material properties, plain compressive/tensile follower force, the location of the boundary conditions, and the vibrational frequency of the bimorph strongly influence the strain distribution, and this in effect influences the charge coefficient and the generation of energy. The proposed model can be extended to thermal energy harvesters of piezoelectric-shape memory alloy (SMA composites.
Measuring Service Reliability Using Automatic Vehicle Location Data
Zhenliang Ma
2014-01-01
Full Text Available Bus service reliability has become a major concern for both operators and passengers. Buffer time measures are believed to be appropriate to approximate passengers' experienced reliability in the context of departure planning. Two issues with regard to buffer time estimation are addressed, namely, performance disaggregation and capturing passengers’ perspectives on reliability. A Gaussian mixture models based method is applied to disaggregate the performance data. Based on the mixture models distribution, a reliability buffer time (RBT measure is proposed from passengers’ perspective. A set of expected reliability buffer time measures is developed for operators by using different spatial-temporal levels combinations of RBTs. The average and the latest trip duration measures are proposed for passengers that can be used to choose a service mode and determine the departure time. Using empirical data from the automatic vehicle location system in Brisbane, Australia, the existence of mixture service states is verified and the advantage of mixture distribution model in fitting travel time profile is demonstrated. Numerical experiments validate that the proposed reliability measure is capable of quantifying service reliability consistently, while the conventional ones may provide inconsistent results. Potential applications for operators and passengers are also illustrated, including reliability improvement and trip planning.
Gregoire, C.; Joesten, P.K.; Lane, J.W.
2006-01-01
Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature
Qin, Mingpu; Shi, Hao; Zhang, Shiwei
2017-08-01
Optical lattice experiments with ultracold fermion atoms and quantum gas microscopy have recently realized direct measurements of magnetic correlations at the site-resolved level. We calculate the short-range spin-correlation functions in the ground state of the two-dimensional repulsive Hubbard model with the auxiliary-field quantum Monte Carlo (AFQMC) method. The results are numerically exact at half filling where the fermion sign problem is absent. Away from half filling, we employ the constrained path AFQMC approach to eliminate the exponential computational scaling from the sign problem. The constraint employs unrestricted Hartree-Fock trial wave functions with an effective interaction strength U , which is optimized self-consistently within AFQMC. Large supercells are studied, with twist averaged boundary conditions as needed, to reach the thermodynamic limit. We find that the nearest-neighbor spin correlation always increases with the interaction strength U , contrary to the finite-temperature behavior where a maximum is reached at a finite U value. We also observe a change of sign in the next-nearest-neighbor spin correlation with increasing density, which is a consequence of the buildup of the long-range antiferromagnetic correlation. We expect the results presented in this paper to serve as a benchmark as lower temperatures are reached in ultracold atom experiments.
Benyo, Theresa L.
2011-01-01
Flow matching has been successfully achieved for an MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment helped perform a thermodynamic cycle analysis to properly match the flows from an inlet employing a MHD energy bypass system (consisting of an MHD generator and MHD accelerator) on a supersonic turbojet engine. Working with various operating conditions (such as the applied magnetic field, MHD generator length and flow conductivity), interfacing studies were conducted between the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis. This paper further describes the analysis of a supersonic turbojet engine with an MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to a range of 0 to 7.0 Mach with specific net thrust range of 740 N-s/kg (at ambient Mach = 3.25) to 70 N-s/kg (at ambient Mach = 7). These results were achieved with an applied magnetic field of 2.5 Tesla and conductivity levels in a range from 2 mhos/m (ambient Mach = 7) to 5.5 mhos/m (ambient Mach = 3.5) for an MHD generator length of 3 m.
A Novel Analytic Technique for the Service Station Reliability in a Discrete-Time Repairable Queue
Renbin Liu
2013-01-01
Full Text Available This paper presents a decomposition technique for the service station reliability in a discrete-time repairable GeomX/G/1 queueing system, in which the server takes exhaustive service and multiple adaptive delayed vacation discipline. Using such a novel analytic technique, some important reliability indices and reliability relation equations of the service station are derived. Furthermore, the structures of the service station indices are also found. Finally, special cases and numerical examples validate the derived results and show that our analytic technique is applicable to reliability analysis of some complex discrete-time repairable bulk arrival queueing systems.
Synthesis of Reliable Telecommunication Networks
Dusan Trstensky
2005-01-01
Full Text Available In many application, the network designer may to know to senthesise a reliable telecommunication network. Assume that a network, denoted Gm,e has the number of nodes n and the number of edges e, and the operational probability of each edge is known. The system reliability of the network is defined to be the reliability that every pair of nodes can communicate with each other. A network synthesis problem considered in this paper is to find a network G*n,e, that maximises system reliability over the class of all networks for the classes of networks Gn,n-1, Gn,m and Gn,n+1 respectively. In addition an upper bound of maximum reliability for the networks with n-node and e-edge (e>n+2 is derived in terms of node. Computational experiments for the reliability upper are also presented. the results show, that the proposed reliability upper bound is effective.
Shapiro, Andrew A.
2006-01-01
Ultra reliable systems are critical to NASA particularly as consideration is being given to extended lunar missions and manned missions to Mars. NASA has formulated a program designed to improve the reliability of NASA systems. The long term goal for the NASA ultra reliability is to ultimately improve NASA systems by an order of magnitude. The approach outlined in this presentation involves the steps used in developing a strategic plan to achieve the long term objective of ultra reliability. Consideration is given to: complex systems, hardware (including aircraft, aerospace craft and launch vehicles), software, human interactions, long life missions, infrastructure development, and cross cutting technologies. Several NASA-wide workshops have been held, identifying issues for reliability improvement and providing mitigation strategies for these issues. In addition to representation from all of the NASA centers, experts from government (NASA and non-NASA), universities and industry participated. Highlights of a strategic plan, which is being developed using the results from these workshops, will be presented.
Reliability Analysis for Tunnel Supports System by Using Finite Element Method
E. Bukaçi
2016-09-01
Full Text Available Reliability analysis is a method that can be used in almost any geotechnical engineering problem. Using this method requires the knowledge of parameter uncertainties, which can be expressed by their standard deviation value. By performing reliability analysis to tunnel supports design, can be obtained a range of safety factors and by using them, probability of failure can be calculated. Problem becomes more complex when this analysis is performed for numerical methods, such as Finite Element Method. This paper gives a solution to how reliability analysis can be performed to design tunnel supports, by using Point Estimate Method to calculate reliability index. As a case study, is chosen one of the energy tunnels at Fan Hydropower plant, in Rrëshen Albania. As results, values of factor of safety and probability of failure are calculated. Also some suggestions using reliability analysis with numerical methods are given.
Tarao, Hiroo; Korpinen, Leena H; Kuisti, Harri A; Hayashi, Noriyuki; Elovaara, Jarmo A; Isaka, Katsuo
2013-01-01
An ungrounded human, such as a substation worker, receives contact currents when touching a grounded object in electric fields. In this article, contact currents and internal electric fields induced in the human when exposed to non-uniform electric fields at 50 Hz are numerically calculated. This is done using a realistic human model standing at a distance of 0.1-0.5 m from the grounded conductive object. We found that the relationship between the external electric field strength and the contact current obtained by calculation is in good agreement with previous measurements. Calculated results show that the contact currents largely depend on the distance, and that the induced electric fields in the tissues are proportional to the contact current regardless of the non-uniformity of the external electric field. Therefore, it is concluded that the contact current, rather than the spatial average of the external electric field, is more suitable for evaluating electric field dosimetry of tissues. The maximum induced electric field appears in the spinal cord in the central nervous system tissues, with the induced electric field in the spinal cord approaching the basic restriction (100 mV/m) of the new 2010 International Commission on Non-Ionizing Radiation Protection guidelines for occupational exposure, if the contact current is 0.5 mA. Copyright © 2012 Wiley Periodicals, Inc.
F. Budillon
2006-01-01
Full Text Available Seismic stratigraphy and core litho-stratigraphy in the Salerno Bay inner shelf (Southern Tyrrhenian Sea reveal significant storm deposition episodes over the last 1 ky. Three major events are preserved as decimetre thick silt/sand layers bounded at their base by erosional surfaces and sealed in the muddy marine sequences between 25 and 60 m of depth. Geochronology and chrono-stratigraphy on core sediment point towards a recurrence of major sea storms between 0.1 and 0.3 ky and put the last significant event in the 19th century, when no local meteorological time series is available. A modelling of extreme sea-storms with a return period of about 0.1 ky is here proposed based on historical hindcast and aims at explaining the occurrence of such unusual deep and thick sand deposits in the northern sector of the bay. Results highlight the vulnerability of the northern coast of the Salerno Bay to the south western sea storms which can drive waves up to about 8 m high and wave period of about 13 s. With these conditions an intense combined flow current is formed and might account for winnowing fine sand down to the depth of 40 m at least. The numerical model thus confirms a possible sand transport in the bottom boundary layer due to wave-current interaction and could corroborate the interpretation of the most recent sand layers, included in the cores, as being generated under extreme sea storm conditions.
Benyo, Theresa L.
2010-01-01
Preliminary flow matching has been demonstrated for a MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment was used to perform a thermodynamic cycle analysis to properly match the flows from an inlet to a MHD generator and from the exit of a supersonic turbojet to a MHD accelerator. Working with various operating conditions such as the enthalpy extraction ratio and isentropic efficiency of the MHD generator and MHD accelerator, interfacing studies were conducted between the pre-ionizers, the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis and describes the NPSS analysis of a supersonic turbojet engine with a MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to an explored and desired range of 0 to 7.0 Mach.
Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S
2016-05-01
The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures.
Maximally reliable Markov chains under energy constraints.
Escola, Sean; Eisele, Michael; Miller, Kenneth; Paninski, Liam
2009-07-01
Signal-to-noise ratios in physical systems can be significantly degraded if the outputs of the systems are highly variable. Biological processes for which highly stereotyped signal generations are necessary features appear to have reduced their signal variabilities by employing multiple processing steps. To better understand why this multistep cascade structure might be desirable, we prove that the reliability of a signal generated by a multistate system with no memory (i.e., a Markov chain) is maximal if and only if the system topology is such that the process steps irreversibly through each state, with transition rates chosen such that an equal fraction of the total signal is generated in each state. Furthermore, our result indicates that by increasing the number of states, it is possible to arbitrarily increase the reliability of the system. In a physical system, however, an energy cost is associated with maintaining irreversible transitions, and this cost increases with the number of such transitions (i.e., the number of states). Thus, an infinite-length chain, which would be perfectly reliable, is infeasible. To model the effects of energy demands on the maximally reliable solution, we numerically optimize the topology under two distinct energy functions that penalize either irreversible transitions or incommunicability between states, respectively. In both cases, the solutions are essentially irreversible linear chains, but with upper bounds on the number of states set by the amount of available energy. We therefore conclude that a physical system for which signal reliability is important should employ a linear architecture, with the number of states (and thus the reliability) determined by the intrinsic energy constraints of the system.
Khabaza, I M
1960-01-01
Numerical Analysis is an elementary introduction to numerical analysis, its applications, limitations, and pitfalls. Methods suitable for digital computers are emphasized, but some desk computations are also described. Topics covered range from the use of digital computers in numerical work to errors in computations using desk machines, finite difference methods, and numerical solution of ordinary differential equations. This book is comprised of eight chapters and begins with an overview of the importance of digital computers in numerical analysis, followed by a discussion on errors in comput
Analysis on Some of Software Reliability Models
无
2001-01-01
Software reliability & maintainability evaluation tool (SRMET 3.0) is introducted in detail in this paper,which was developed by Software Evaluation and Test Center of China Aerospace Mechanical Corporation. SRMET 3.0is supported by seven soft ware reliability models and four software maintainability models. Numerical characteristicsfor all those models are deeply studied in this paper, and corresponding numerical algorithms for each model are alsogiven in the paper.
Sarkadi, N.; Geresdi, I.; Thompson, G.
2016-11-01
In this study, results of bulk and bin microphysical schemes are compared in the case of idealized simulations of pre-frontal orographic clouds with enhanced embedded convection. The description graupel formation by intensive riming of snowflakes was improved compared to prior versions of each scheme. Two methods of graupel melting coincident with collisions with water drops were considered: (1) all simulated melting and collected water drops increase the amount of melted water on the surface of graupel particles with no shedding permitted; (2) also no shedding permitted due to melting, but the collision with the water drops can induce shedding from the surface of the graupel particles. The results of the numerical experiments show: (i) The bin schemes generate graupel particles more efficiently by riming than the bulk scheme does; the intense riming of snowflakes was the most dominant process for the graupel formation. (ii) The collision-induced shedding significantly affects the evolution of the size distribution of graupel particles and water drops below the melting level. (iii) The three microphysical schemes gave similar values for the domain integrated surface precipitation, but the patterns reveal meaningful differences. (iv) Sensitivity tests using the bulk scheme show that the depth of the melting layer is sensitive to the description of the terminal velocity of the melting snow. (v) Comparisons against Convair-580 flight measurements suggest that the bin schemes simulate well the evolution of the pristine ice particles and liquid drops, while some inaccuracy can occur in the description of snowflakes riming. (vi) The bin scheme with collision-induced shedding reproduced well the quantitative characteristics of the observed bright band.
Gomberg, Joan; Ellis, Michael
1994-01-01
We present results of a series of numerical experiments designed to test hypothetical mechanisms that derive deformation in the New Madrid seismic zone. Experiments are constrained by subtle topography and the distribution of seismicity in the region. We use a new boundary element algorithm that permits calcuation of the three-dimensional deformation field. Surface displacement fields are calculated for the New Madrid zone under both far-field (plate tectonics scale) and locally derived driving strains. Results demonstrate that surface displacement fields cannot distinguish between either a far-field simple or pure shear strain field or one that involves a deep shear zone beneath the upper crustal faults. Thus, neither geomorphic nor geodetic studies alone are expected to reveal the ultimate driving mechanism behind the present-day deformation. We have also tested hypotheses about strain accommodation within the New Madrid contractional step-over by including linking faults, two southwest dipping and one vertical, recently inferred from microearthquake data. Only those models with step-over faults are able to predict the observed topography. Surface displacement fields for long-term, relaxed deformation predict the distribution of uplift and subsidence in the contractional step-over remarkably well. Generation of these displacement fields appear to require slip on both the two northeast trending vertical faults and the two dipping faults in the step-over region, with very minor displacements occurring during the interseismic period when the northeast trending vertical faults are locked. These models suggest that the gently dippling central step-over fault is a reverse fault and that the steeper fault, extending to the southeast of the step-over, acts as a normal fault over the long term.
Edwards, E.; Washburn, B.; Harter, T.; Fogg, G. E.; Nelson, C.; Lock, B.; Li, X.
2016-12-01
Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas with low permeability soils or cover. Stormwater runoff that would otherwise be routed to streams or drains in urban areas can be used as a source of aquifer recharge, potentially mitigating the effects of drought and harm to natural water bodies. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil and near surface sediment attenuation processes has prevented more widespread use of drywells as a recharge mechanism. A field study was conducted in Elk Grove, CA, to determine the effects of drywell-induced stormwater infiltration on the local hydrogeologic system. Two drywells 13.5 meters in depth were constructed for the project: one in a preexisting drainage basin fed by residential lots, and one at an industrial site. Both sites were outfitted with vegetated pretreatments, and upgradient and downgradient groundwater monitoring wells. Site stormwater and groundwater were sampled between November, 2014, and May, 2016, and analyzed for contaminants. Results of water quality sampling have been statistically analyzed for trends and used to determine the contaminants of interest and the concentrations of these contaminants in influent stormwater. The fate and transport of these contaminants have been simulated using a 1D variably saturated flow and transport model and site specific parameters to predict long-term effects of stormwater infiltration on the surrounding hydrogeologic system. The potential for remobilization of geogenic heavy metals from changes in subsurface hydrochemistry caused by drywell infiltration have also been assessed. The results of the field study and numerical modeling assessment indicate that the study's drywells do not pose a long-term threat to groundwater quality and may be an effective source of aquifer recharge and tool for urban stormwater management.
Gomberg, Joan; Ellis, Michael
1994-01-01
We present results of a series of numerical experiments designed to test hypothetical mechanisms that derive deformation in the New Madrid seismic zone. Experiments are constrained by subtle topography and the distribution of seismicity in the region. We use a new boundary element algorithm that permits calcuation of the three-dimensional deformation field. Surface displacement fields are calculated for the New Madrid zone under both far-field (plate tectonics scale) and locally derived driving strains. Results demonstrate that surface displacement fields cannot distinguish between either a far-field simple or pure shear strain field or one that involves a deep shear zone beneath the upper crustal faults. Thus, neither geomorphic nor geodetic studies alone are expected to reveal the ultimate driving mechanism behind the present-day deformation. We have also tested hypotheses about strain accommodation within the New Madrid contractional step-over by including linking faults, two southwest dipping and one vertical, recently inferred from microearthquake data. Only those models with step-over faults are able to predict the observed topography. Surface displacement fields for long-term, relaxed deformation predict the distribution of uplift and subsidence in the contractional step-over remarkably well. Generation of these displacement fields appear to require slip on both the two northeast trending vertical faults and the two dipping faults in the step-over region, with very minor displacements occurring during the interseismic period when the northeast trending vertical faults are locked. These models suggest that the gently dippling central step-over fault is a reverse fault and that the steeper fault, extending to the southeast of the step-over, acts as a normal fault over the long term.
Pruschke, T.; Bulla, R. [Institute fuer Theoretische Physik der Universitaet, Regensburg (Germany)
1995-05-01
The numerical renormalization group method is applied to an Anderson impurity with an energy dependent coupling to the conduction band. We describe how the discrete spectra resulting from the numerical calculation can be reliably smoothed using a continued fraction expansion. The investigations are connected with the study of models in infinite spatial dimensions.
Eugster, P.; Guerraoui, R.; Kouznetsov, P.
2001-01-01
This paper presents a new, non-binary measure of the reliability of broadcast algorithms, called Delta-Reliability. This measure quantifies the reliability of practical broadcast algorithms that, on the one hand, were devised with some form of reliability in mind, but, on the other hand, are not considered reliable according to the ``traditional'' notion of broadcast reliability [HT94]. Our specification of Delta-Reliability suggests a further step towards bridging the gap between theory and...
Reliability computation from reliability block diagrams
Chelson, P. O.; Eckstein, E. Y.
1975-01-01
Computer program computes system reliability for very general class of reliability block diagrams. Four factors are considered in calculating probability of system success: active block redundancy, standby block redundancy, partial redundancy, and presence of equivalent blocks in the diagram.
A numerical approach for solving an extended Fisher-Kolomogrov-Petrovskii-Piskunov equation
Khuri, S. A.; Sayfy, A.
2010-02-01
In the present paper a numerical method, based on finite differences and spline collocation, is presented for the numerical solution of a generalized Fisher integro-differential equation. A composite weighted trapezoidal rule is manipulated to handle the numerical integrations which results in a closed-form difference scheme. A number of test examples are solved to assess the accuracy of the method. The numerical solutions obtained, indicate that the approach is reliable and yields results compatible with the exact solutions and consistent with other existing numerical methods. Convergence and stability of the scheme have also been discussed.
Jacques, Ian
1987-01-01
This book is primarily intended for undergraduates in mathematics, the physical sciences and engineering. It introduces students to most of the techniques forming the core component of courses in numerical analysis. The text is divided into eight chapters which are largely self-contained. However, with a subject as intricately woven as mathematics, there is inevitably some interdependence between them. The level of difficulty varies and, although emphasis is firmly placed on the methods themselves rather than their analysis, we have not hesitated to include theoretical material when we consider it to be sufficiently interesting. However, it should be possible to omit those parts that do seem daunting while still being able to follow the worked examples and to tackle the exercises accompanying each section. Familiarity with the basic results of analysis and linear algebra is assumed since these are normally taught in first courses on mathematical methods. For reference purposes a list of theorems used in the t...
Antczak, K; Wilczyńska, U
1980-01-01
Part II presents a statistical model devised by the authors for evaluating toxicological analyses results. The model includes: 1. Establishment of a reference value, basing on our own measurements taken by two independent analytical methods. 2. Selection of laboratories -- basing on the deviation of the obtained values from reference ones. 3. On consideration of variance analysis, t-student's test and differences test, subsequent quality controls and particular laboratories have been evaluated.
Classification using least squares support vector machine for reliability analysis
Zhi-wei GUO; Guang-chen BAI
2009-01-01
In order to improve the efficiency of the support vector machine (SVM) for classification to deal with a large amount of samples,the least squares support vector machine (LSSVM) for classification methods is introduced into the reliability analysis.To reduce the computational cost,the solution of the SVM is transformed from a quadratic programming to a group of linear equations.The numerical results indicate that the reliability method based on the LSSVM for classification has higher accuracy and requires less computational cost than the SVM method.
Fattorini, Paolo; Previderè, Carlo; Sorçaburu-Cigliero, Solange; Marrubini, Giorgio; Alù, Milena; Barbaro, Anna M; Carnevali, Eugenia; Carracedo, Angel; Casarino, Lucia; Consoloni, Lara; Corato, Silvia; Domenici, Ranieri; Fabbri, Matteo; Giardina, Emiliano; Grignani, Pierangela; Baldassarra, Stefania Lonero; Moratti, Marco; Nicolin, Vanessa; Pelotti, Susi; Piccinini, Andrea; Pitacco, Paola; Plizza, Laura; Resta, Nicoletta; Ricci, Ugo; Robino, Carlo; Salvaderi, Luca; Scarnicci, Francesca; Schneider, Peter M; Seidita, Gregorio; Trizzino, Lucia; Turchi, Chiara; Turrina, Stefania; Vatta, Paolo; Vecchiotti, Carla; Verzeletti, Andrea; De Stefano, Francesco
2014-11-01
The role of DNA damage in PCR processivity/fidelity is a relevant topic in molecular investigation of aged/forensic samples. In order to reproduce one of the most common lesions occurring in postmortem tissues, a new protocol based on aqueous hydrolysis of the DNA was developed in vitro. Twenty-five forensic laboratories were then provided with 3.0 μg of a trial sample (TS) exhibiting, in mean, the loss of 1 base of 20, and a molecular weight below 300 bp. Each participating laboratory could freely choose any combination of methods, leading to the quantification and to the definition of the STR profile of the TS, through the documentation of each step of the analytical approaches selected. The results of the TS quantification by qPCR showed significant differences in the amount of DNA recorded by the participating laboratories using different commercial kits. These data show that only DNA quantification "relative" to the used kit (probe) is possible, being the "absolute" amount of DNA inversely related to the length of the target region (r(2) = 0.891). In addition, our results indicate that the absence of a shared stable and certified reference quantitative standard is also likely involved. STR profiling was carried out selecting five different commercial kits and amplifying the TS for a total number of 212 multiplex PCRs, thus representing an interesting overview of the different analytical protocols used by the participating laboratories. Nine laboratories decided to characterize the TS using a single kit, with a number of amplifications varying from 2 to 12, obtaining only partial STR profiles. Most of the participants determined partial or full profiles using a combination of two or more kits, and a number of amplifications varying from 2 to 27. The performance of each laboratory was described in terms of number of correctly characterized loci, dropped-out markers, unreliable genotypes, and incorrect results. The incidence of unreliable and incorrect
Park, Jun-Hyub; Shin, Myung-Soo
2011-09-01
This paper describes the results of tensile tests for a beryllium-copper (BeCu) alloy thin film and the application of the results to the design of a probe. The copper alloy films were fabricated by electroplating. To obtain the tensile characteristics of the film, the dog-bone type specimen was fabricated by the etching method. The tensile tests were performed with the specimen using a test machine developed by the authors. The BeCu alloy has an elastic modulus of 119 GPa and the 0.2% offset yield and ultimate tensile strengths of 1078 MPa and 1108 MPa, respectively. The design and manufacture of a smaller probe require higher pad density and smaller pad-pitch chips. It should be effective in high-frequency testing. For the design of a new micro-probe, we investigated several design parameters that may cause problems, such as the contact force and life, using the tensile properties and the design of experiment method in conjunction with finite element analysis. The optimal dimensions of the probe were found using the response surface method. The probe with optimal dimensions was manufactured by a precision press process. It was verified that the manufactured probe satisfied the life, the contact force and the over drive through the compression tests and the life tests of the probes.
Reliability engineering theory and practice
Birolini, Alessandro
2014-01-01
This book shows how to build in, evaluate, and demonstrate reliability and availability of components, equipment, systems. It presents the state-of-theart of reliability engineering, both in theory and practice, and is based on the author's more than 30 years experience in this field, half in industry and half as Professor of Reliability Engineering at the ETH, Zurich. The structure of the book allows rapid access to practical results. This final edition extend and replace all previous editions. New are, in particular, a strategy to mitigate incomplete coverage, a comprehensive introduction to human reliability with design guidelines and new models, and a refinement of reliability allocation, design guidelines for maintainability, and concepts related to regenerative stochastic processes. The set of problems for homework has been extended. Methods & tools are given in a way that they can be tailored to cover different reliability requirement levels and be used for safety analysis. Because of the Appendice...
Sabrina de Stefani
2008-02-01
Full Text Available FUNDAMENTOS: A ocorrência da dermatite de contato alérgica em pacientes soropositivos para o HIV foi pouco estudada até o momento (apenas relatos de caso. Os testes de contato são considerados o exame complementar padrão para a investigação diagnóstica desse tipo de reação alérgica e não foram avaliados cientificamente nesse grupo de pacientes. OBJETIVO: Avaliar a aplicabilidade dos testes de contato em pacientes soropositivos para o HIV. MÉTODO: Estudo transversal, descritivo, com controles. Um grupo com 16 pacientes soropositivos para o HIV foi comparado a um grupo com 32 pacientes com sorologia desconhecida para o HIV com relação à positividade aos testes. Foi realizada análise estatística bivariada com nível de significância p BACKGROUND: Allergic contact dermatitis in HIV-positive patients has not been thoroughly studied (there are only case reports. Patch tests are the gold standard for diagnosis of this type of allergic reaction and have not been scientifically assessed in such patients. OBJECTIVE: To evaluate the applicability of patch tests in HIV-positive patients. METHODS: A cross-sectional, controlled and descriptive study. A group of 16 HIV-positive patients was compared to a group of 32 patients with unknown HIV sorology results. Bivariate statistical analysis was performed with significance level of p<0.05. RESULTS: Seven patients (43.75% in the HIV-positive group and 18 (56.25% in the unknown sorology group had patch positive tests. CONCLUSIONS: Regardless of immunodeficiency, the findings of this study suggest that specific immunologic memory and the ability to positively respond to tests may remain active. Therefore, this standard and important diagnostic method for allergic contact dermatitis is valid when applied to a group of HIV patients.
Expert system aids reliability
Johnson, A.T. [Tennessee Gas Pipeline, Houston, TX (United States)
1997-09-01
Quality and Reliability are key requirements in the energy transmission industry. Tennessee Gas Co. a division of El Paso Energy, has applied Gensym`s G2, object-oriented Expert System programming language as a standard tool for maintaining and improving quality and reliability in pipeline operation. Tennessee created a small team of gas controllers and engineers to develop a Proactive Controller`s Assistant (ProCA) that provides recommendations for operating the pipeline more efficiently, reliably and safely. The controller`s pipeline operating knowledge is recreated in G2 in the form of Rules and Procedures in ProCA. Two G2 programmers supporting the Gas Control Room add information to the ProCA knowledge base daily. The result is a dynamic, constantly improving system that not only supports the pipeline controllers in their operations, but also the measurement and communications departments` requests for special studies. The Proactive Controller`s Assistant development focus is in the following areas: Alarm Management; Pipeline Efficiency; Reliability; Fuel Efficiency; and Controller Development.
ZHOU Tianjun; SONG Fengfei; CHEN Xiaolong
2013-01-01
In order to assess the performance of two versions of the IAP/LASG Flexible Global Ocean-Atmosphere-Land System (FGOALS) model,simulated changes in surface air temperature (SAT),from natural and anthropogenic forcings,were compared to observations for the period 1850-2005 at global,hemispheric,continental and regional scales.The global and hemispheric averages of SAT and their land and ocean components during 1850 2005 were well reproduced by FGOALS-g2,as evidenced by significant correlation coefficients and small RMSEs.The significant positive correlations were firstly determined by the warming trends,and secondly by interdecadal fluctuations.The abilities of the models to reproduce interdecadal SAT variations were demonstrated by both wavelet analysis and significant positive correlations for detrended data.The observed land-sea thermal contrast change was poorly simulated.The major weakness of FGOALS-s2 was an exaggerated warming response to anthropogenic forcing,with the simulation showing results that were far removed from observations prior to the 1950s.The observations featured warming trends (1906-2005)of 0.71,0.68 and 0.79℃ (100 yr) 1 for global,Northern and Southern Hemispheric averages,which were overestimated by FGOALS-s2 [1.42,1.52 and 1.13℃ (100 yr)-1] but underestimated by FGOALS-g2 [0.69,0.68 and 0.73℃ (100 yr)-1].The polar amplification of the warming trend was exaggerated in FGOALS-s2 but weakly reproduced in FGOALS-g2.The stronger response of FGOALS-s2 to anthropogenic forcing was caused by strong sea-ice albedo feedback and water vapor feedback.Examination of model results in 15 selected subcontinental-scale regions showed reasonable performance for FGOALS-g2 over most regions.However,the observed warming trends were overestimated by FGOALS-s2 in most regions.Over East Asia,the meridional gradient of the warming trend simulated by FGOALS-s2 (FGOALS-g2) was stronger (weaker)than observed.
Antonio Piacentino
2016-12-01
Full Text Available Cogeneration and trigeneration plants are widely recognized as promising technologies for increasing energy efficiency in buildings. However, their overall potential is scarcely exploited, due to the difficulties in achieving economic viability and the risk of investment related to uncertainties in future energy loads and prices. Several stochastic optimization models have been proposed in the literature to account for uncertainties, but these instruments share in a common reliance on user-defined probability functions for each stochastic parameter. Being such functions hard to predict, in this paper an analysis of the influence of erroneous estimation of the uncertain energy loads and prices on the optimal plant design and operation is proposed. With reference to a hotel building, a number of realistic scenarios is developed, exploring all the most frequent errors occurring in the estimation of energy loads and prices. Then, profit-oriented optimizations are performed for the examined scenarios, by means of a deterministic mixed integer linear programming algorithm. From a comparison between the achieved results, it emerges that: (i the plant profitability is prevalently influenced by the average “spark-spread” (i.e., ratio between electricity and fuel price and, secondarily, from the shape of the daily price profiles; (ii the “optimal sizes” of the main components are scarcely influenced by the daily load profiles, while they are more strictly related with the average “power to heat” and “power to cooling” ratios of the building.
Verweij, Jan F.
1993-01-01
Several issue's regarding VLSI reliability research in Europe are discussed. Organizations involved in stimulating the activities on reliability by exchanging information or supporting research programs are described. Within one such program, ESPRIT, a technical interest group on IC reliability was
Olchev, Alexander; Kuzmina, Ekaterina; Rozinkina, Inna; Nikitin, Mikhail; Rivin, Gdaly S.
2017-04-01
The forests have a significant effect on the climatic system. They capture CO2 from the atmosphere, regulate the surface evaporation and runoff, and influence the radiation and thermal conditions of the land surface. It is obvious, that their influence depends on many different factors including regional climate conditions, land use and vegetation structure, surface topography, etc. The main goal of the study is to assess the possible influence of forest cover changes (under deforestation and/or afforestation) on regional weather conditions in the central part of European Russia using the results of modeling experiments provided by the meso-scale COSMO-CLM model. The need of the study lies in a lack of the experimental and modeling data characterizing the influence of the forest and land-use changes on regional weather conditions in European part of Russia. The forest ecosystems in the study region play a very important biosphere role that is significantly increased in the last decades due to considerable strengthening of anthropogenic activity in the area of European Russia. The area selected for the study is located in the central part of European Russia between 55 and 59N and 28 and 37E. It comprises several geographical zones including dark-coniferous forests of the South-European taiga in the north, the mixed forests in the central part and the broad-leaved forests in the south. The forests within the study area are very heterogeneous. The total area covered by forests according to recent remote sensing data is about 50%. The numerical experiments were provided using the COSMO-CLM model with the spatial resolution 13.2 km. As initial and boundary conditions for the numerical experiments the global reanalysis ERA Interim (with the 6-hour resolution in time and 0.75° × 0.75° in space) were used. The weather conditions were simulated in a continuous cycle for several months for the entire area of European Russia using the results of global reanalysis on
Rao, G Shanker
2006-01-01
About the Book: This book provides an introduction to Numerical Analysis for the students of Mathematics and Engineering. The book is designed in accordance with the common core syllabus of Numerical Analysis of Universities of Andhra Pradesh and also the syllabus prescribed in most of the Indian Universities. Salient features: Approximate and Numerical Solutions of Algebraic and Transcendental Equation Interpolation of Functions Numerical Differentiation and Integration and Numerical Solution of Ordinary Differential Equations The last three chapters deal with Curve Fitting, Eigen Values and Eigen Vectors of a Matrix and Regression Analysis. Each chapter is supplemented with a number of worked-out examples as well as number of problems to be solved by the students. This would help in the better understanding of the subject. Contents: Errors Solution of Algebraic and Transcendental Equations Finite Differences Interpolation with Equal Intervals Interpolation with Unequal Int...
Pereira, Gilmar Ferreira
and structural health monitoring of wind turbine blades. The work presented sets the required framework to develop a monitoring system based on fibre Bragg gratings (FBG), which can be applied to the different life stages of a wind turbine blade. In this concept, the different measured physical parameters...... turbine as long as it is monitored. Thus, a novel crack/damage detection method using FBG sensors is presented, and software/tools are developed for signal simulation and post-processing. The first part of the thesis is an introduction to the multi-life-stage monitoring system based on FBG sensors...... and the damage tolerant design of fibre reinforced materials, where the different theory and numerical models used are presented. The second part of the thesis is a compilation of scientific journal papers, in which the use of FBG sensors to monitor the different life-stages of the wind turbine rotor blade...
爆炸抛撤粒子群数值模拟%Numerical simulation of the particle dissipation as a result of strong explosion
刘意; 白春华; 王仲琦
2011-01-01
The paper is aimed to propose a numerically simulated model to imitate the particle dissipation as the result of strong explosion based on the discrete the particle dissipation method. For our research purpose, we have calculated and discussed the influence of the particle size and particle layers to the process of particle dissipation along with the particle velocity and the number of particles in conformity with the normal distribution. The thickness of the particle cloud can be said in some ways similar to the linear growth with time. When dissipated by the explosion, the particle size may have a great influence on the rate of the particles, because different particle sizes mean different amounts of particle mass and particle drag, which tend to lead to the different dissipation velocities of the particles. The particles velocity and the number of particles conform to the normal distribution. The thickness of particle cloud is similar to linear growth with time while the layers of particle are the same and radius of particle is different. At the early stages of the process, both the thickness of the cloud and the number of the particles are similar to each other; while at the end of the process, the smaller particles of the cloud would become slightly larger than the larger ones. When experimented with the particle dissipation caused by the explosion, we have formulated a rule of the particle dissipation boundary velocities, which may have impact on the target plate by using high-speed camera, deep craters on the target plates and so on. Through simulated experiment by calculating the code, this rule proves to be in conformity with the results of the calculation and experiment. At the same time, it also helps to verify the accuracy of the particle model and calculating code. And finally a particle model has been proposed to describe the issue of particles' dissipation model as a result of the detonation products detonated. The interaction progress between the
Chavanis, P H
2011-01-01
We develop the suggestion that dark matter could be a Bose-Einstein condensate. We determine the mass-radius relation of a Newtonian self-gravitating Bose-Einstein condensate with short-range interactions described by the Gross-Pitaevskii-Poisson system. We numerically solve the equation of hydrostatic equilibrium describing the balance between the gravitational attraction and the pressure due to quantum effects (Heisenberg's uncertainty principle) and short-range interactions (scattering). We connect the non-interacting limit to the Thomas-Fermi limit. We also consider the case of attractive self-interaction. We compare the exact mass-radius relation obtained numerically with the approximate analytical relation obtained with a Gaussian ansatz. An overall good agreement is found.
Lifetimes and Reliabilities of Bevel-Gear Drive Trains
Lewicki, D.; Cox, J.; Savage, M.; Brikmanis, C.
1986-01-01
Statistical methods used to predict system lifetimes from component lifetimes. Report shows how to use information to determine system life of drive train, using methods of probability and statistics. Presents life and reliability model for bevel-gear drive trains. Bevel-gear and support-bearing lives analyzed for each gear and bearing in drive train, with results statistically combined to produce system life for entire drive train. Numerical example included.
Predicting Reliability of Tactical Network Using RBFNN
WANG Xiao-kai; HOU Chao-zhen
2005-01-01
A description of the reliability evaluation of tactical network is given, which reflects not only the non-reliable factors of nodes and links but also the factors of network topological structure. On the basis of this description, a reliability prediction model and its algorithms are put forward based on the radial basis function neural network (RBFNN) for the tactical network. This model can carry out the non-linear mapping relationship between the network topological structure, the nodes reliabilities, the links reliabilities and the reliability of network. The results of simulation prove the effectiveness of this method in the reliability and the connectivity prediction for tactical network.
Unnikrishnan, A; Manoj, N.T.
Various numerical models used to study the dynamics and horizontal distribution of salinity in Mandovi-Zuari estuaries, Goa, India is discussed in this chapter. Earlier, a one-dimensional network model was developed for representing the complex...
Reliability and construction control
Sherif S. AbdelSalam
2016-06-01
Full Text Available The goal of this study was to determine the most reliable and efficient combination of design and construction methods required for vibro piles. For a wide range of static and dynamic formulas, the reliability-based resistance factors were calculated using EGYPT database, which houses load test results for 318 piles. The analysis was extended to introduce a construction control factor that determines the variation between the pile nominal capacities calculated using static versus dynamic formulae. From the major outcomes, the lowest coefficient of variation is associated with Davisson’s criterion, and the resistance factors calculated for the AASHTO method are relatively high compared with other methods. Additionally, the CPT-Nottingham and Schmertmann method provided the most economic design. Recommendations related to a pile construction control factor were also presented, and it was found that utilizing the factor can significantly reduce variations between calculated and actual capacities.
Scott, L Ridgway
2011-01-01
Computational science is fundamentally changing how technological questions are addressed. The design of aircraft, automobiles, and even racing sailboats is now done by computational simulation. The mathematical foundation of this new approach is numerical analysis, which studies algorithms for computing expressions defined with real numbers. Emphasizing the theory behind the computation, this book provides a rigorous and self-contained introduction to numerical analysis and presents the advanced mathematics that underpin industrial software, including complete details that are missing from m
Antczak, K; Wilczyńska, U
1980-01-01
2 statistical models for evaluation of toxicological studies results have been presented. Model I. after R. Hoschek and H. J. Schittke (2) involves: 1. Elimination of the values deviating from most results-by Grubbs' method (2). 2. Analysis of the differences between the results obtained by the participants of the action and tentatively assumed value. 3. Evaluation of significant differences between the reference value and average value for a given series of measurements. 4. Thorough evaluation of laboratories based on evaluation coefficient fx. Model II after Keppler et al. As a criterion for evaluating the results the authors assumed the median. Individual evaluation of laboratories was performed on the basis of: 1. Adjusted test "t" 2. Linear regression test.
Reliability Generalization: "Lapsus Linguae"
Smith, Julie M.
2011-01-01
This study examines the proposed Reliability Generalization (RG) method for studying reliability. RG employs the application of meta-analytic techniques similar to those used in validity generalization studies to examine reliability coefficients. This study explains why RG does not provide a proper research method for the study of reliability,…
Reliability-Based Control Design for Uncertain Systems
Crespo, Luis G.; Kenny, Sean P.
2005-01-01
This paper presents a robust control design methodology for systems with probabilistic parametric uncertainty. Control design is carried out by solving a reliability-based multi-objective optimization problem where the probability of violating design requirements is minimized. Simultaneously, failure domains are optimally enlarged to enable global improvements in the closed-loop performance. To enable an efficient numerical implementation, a hybrid approach for estimating reliability metrics is developed. This approach, which integrates deterministic sampling and asymptotic approximations, greatly reduces the numerical burden associated with complex probabilistic computations without compromising the accuracy of the results. Examples using output-feedback and full-state feedback with state estimation are used to demonstrate the ideas proposed.
Park, Bu S; Rajan, Sunder S; Guag, Joshua W; Angelone, Leonardo M
2015-04-01
Materials with high dielectric constant (HDC) have been used in high field MRI to decrease specific absorption rate (SAR), increase magnetic field intensity, and increase signal-to-noise ratio. In previous studies, the HDC materials were placed inside the RF coil decreasing the space available. This study describes an alternative approach that considers an HDC-based sleeve placed outside the RF coil. The effects of an HDC on the electromagnetic (EM) field were studied using numerical simulations with a coil unloaded and loaded with a human head model. In addition, experimental EM measurements at 128 MHz were performed inside a custom-made head coil, fitted with a distilled water sleeve. The numerical simulations showed up to 40% decrease in maximum 10 g-avg. SAR on the surface of the head model with an HDC material of barium titanate. Experimental measurements also showed up to 20% decrease of maximum electric field using an HDC material of distilled water. The proposed method can be incorporated in the design of high field transmit RF coils.
Reliability-Based Code Calibration
Faber, M.H.; Sørensen, John Dalsgaard
2003-01-01
The present paper addresses fundamental concepts of reliability based code calibration. First basic principles of structural reliability theory are introduced and it is shown how the results of FORM based reliability analysis may be related to partial safety factors and characteristic values....... Thereafter the code calibration problem is presented in its principal decision theoretical form and it is discussed how acceptable levels of failure probability (or target reliabilities) may be established. Furthermore suggested values for acceptable annual failure probabilities are given for ultimate...... and serviceability limit states. Finally the paper describes the Joint Committee on Structural Safety (JCSS) recommended procedure - CodeCal - for the practical implementation of reliability based code calibration of LRFD based design codes....
Reliability Estimation of the Pultrusion Process Using the First-Order Reliability Method (FORM)
Baran, Ismet; Tutum, Cem C.; Hattel, Jesper H.
2013-01-01
In the present study the reliability estimation of the pultrusion process of a flat plate is analyzed by using the first order reliability method (FORM). The implementation of the numerical process model is validated by comparing the deterministic temperature and cure degree profiles with correspond
Reliability optimization problems with multiple constraints under fuzziness
Gupta, Neha; Haseen, Sanam; Bari, Abdul
2016-06-01
In reliability optimization problems diverse situation occurs due to which it is not always possible to get relevant precision in system reliability. The imprecision in data can often be represented by triangular fuzzy numbers. In this manuscript, we have considered different fuzzy environment for reliability optimization problem of redundancy. We formulate a redundancy allocation problem for a hypothetical series-parallel system in which the parameters of the system are fuzzy. Two different cases are then formulated as non-linear programming problem and the fuzzy nature is defuzzified into crisp problems using three different defuzzification methods viz. ranking function, graded mean integration value and α-cut. The result of the methods is compared at the end of the manuscript using a numerical example.
Reliability-Based Design of Wind Turbine Components
Toft, Henrik Stensgaard; Sørensen, John Dalsgaard
2010-01-01
wind turbine design a deterministic design approach based on partial safety factors is normally used. In the present paper a numerical example demonstrates how information from tests with wind turbine blades can be used to establish a probabilistic basis for reliabilitybased design. It is also......Application of reliability-based design for wind turbines requires a definition of the probabilistic basis for the individual components of the wind turbine. In the present paper reliability-based design of structural wind turbine components is considered. A framework for the uncertainties which...... demonstrated how partial safety factors can be derived for reliability-based design and how the partial safety factors changes dependent on the uncertainty in the test results....
Bourlier, C.; Berginc, G.
2004-07-01
This second part presents illustrative examples of the model developed in the companion paper, which is based on the first- and second-order optics approximation. The surface is assumed to be Gaussian and the correlation height is chosen as anisotropic Gaussian. The incoherent scattering coefficient is computed for a height rms range from 0.5lgr to 1lgr (where lgr is the electromagnetic wavelength), for a slope rms range from 0.5 to 1 and for an incidence angle range from 0 to 70°. In addition, simulations are presented for an anisotropic Gaussian surface and when the receiver is not located in the plane of incidence. For a metallic and dielectric isotropic Gaussian surfaces, the cross- and co-polarizations are also compared with a numerical approach obtained from the forward-backward method with a novel spectral acceleration algorithm developed by Torrungrueng and Johnson (2001, JOSA A 18).
Brezinski, C
2012-01-01
Numerical analysis has witnessed many significant developments in the 20th century. This book brings together 16 papers dealing with historical developments, survey papers and papers on recent trends in selected areas of numerical analysis, such as: approximation and interpolation, solution of linear systems and eigenvalue problems, iterative methods, quadrature rules, solution of ordinary-, partial- and integral equations. The papers are reprinted from the 7-volume project of the Journal of Computational and Applied Mathematics on '/homepage/sac/cam/na2000/index.html<
Numerical wave interaction with tetrapods breakwater
Dentale, Fabio; Donnarumma, Giovanna; Carratelli, Eugenio Pugliese
2014-12-01
The paper provides some results of a new procedure to analyze the hydrodynamic aspects of the interactions between maritime emerged breakwaters and waves by integrating CAD and CFD. The structure is modeled in the numerical domain by overlapping individual three-dimensional elements (Tetrapods), very much like the real world or physical laboratory testing. Flow of the fluid within the interstices among concrete blocks is evaluated by integrating the RANS equations. The aim is to investigate the reliability of this approach as a design tool. Therefore, for the results' validation, the numerical run-up and reflection effects on virtual breakwater were compared with some empirical formulae and some similar laboratory tests. Here are presented the results of a first simple validation procedure. The validation shows that, at present, this innovative approach can be used in the breakwater design phase for comparison between several design solutions with a significant minor cost.
Discrete Reliability Projection
2014-12-01
trials and that failures from individual failure modes are statistically independent and binomially distributed . The probability of success...such that p ∗ n is constant = λ, the binomial distribution approximates the Poisson distribution with parameter λ. 4.1.2 Unsurfaced Failure Modes Given...line (dark blue) is the result of numerical integration of beta and binomial distributions . It shows a theoretical prediction of the outcome of the 27
Assuring reliability program effectiveness.
Ball, L. W.
1973-01-01
An attempt is made to provide simple identification and description of techniques that have proved to be most useful either in developing a new product or in improving reliability of an established product. The first reliability task is obtaining and organizing parts failure rate data. Other tasks are parts screening, tabulation of general failure rates, preventive maintenance, prediction of new product reliability, and statistical demonstration of achieved reliability. Five principal tasks for improving reliability involve the physics of failure research, derating of internal stresses, control of external stresses, functional redundancy, and failure effects control. A final task is the training and motivation of reliability specialist engineers.
The Accelerator Reliability Forum
Lüdeke, Andreas; Giachino, R
2014-01-01
A high reliability is a very important goal for most particle accelerators. The biennial Accelerator Reliability Workshop covers topics related to the design and operation of particle accelerators with a high reliability. In order to optimize the over-all reliability of an accelerator one needs to gather information on the reliability of many different subsystems. While a biennial workshop can serve as a platform for the exchange of such information, the authors aimed to provide a further channel to allow for a more timely communication: the Particle Accelerator Reliability Forum [1]. This contribution will describe the forum and advertise it’s usage in the community.
秦飞; 夏国峰; 高察; 安彤; 朱文辉
2014-01-01
A design of experiment (DOE) methodology based on numerical simulation is presented to improve thermal fatigue reliability of multi-row quad flat non-lead (QFN) packages. The influences of material properties, structural geometries and temperature cycling profiles on thermal fatigue life are evaluated. Anand constitutive model is adopted to describe the viscoplastic behavior of lead-free solder Sn3.0Ag0.5Cu. The stress and strain in solder joints under temperature cycling are studied by 3D finite element model. Coffin-Manson model is employed to predict the fatigue life. A L27(38) orthogonal array is built based on Taguchi method to figure out optimized factor combination design for improving thermal fatigue reliability. The optimized factor combination design derived from DOE methodology is verified by finite element analysis. Results indicate that the coefficients of thermal expansion (CTE) of printed circuit board (PCB), the height of solder joints and CTE of epoxy molding compound (EMC) have critical influence on thermal fatigue life. The fatigue life of multi-row QFN package with original design is 767 cycles, which can be substantially improved by 5.43 times to 4 165 cycles after the optimized factor combination design based on the presented method.%提出一种基于数值模拟的试验设计方法，研究材料属性和几何结构对多圈四边扁平无引脚(Quad flat no-lead，QFN)封装热疲劳寿命的影响，并进行最优因子的组合设计，以提升热疲劳可靠性。采用 Anand 黏塑性本构模型描述无铅钎料Sn3.0Ag0.5Cu的力学行为，建立三维有限元模型分析焊点在温度循环过程中的应力应变，采用Coffin-Manson寿命预测模型计算多圈QFN封装的热疲劳寿命。采用Taguchi试验设计(Design of experiment，DOE)方法建立L27(38)正交试验表进行最优因子的组合设计。采用有限元分析方法对最优因子组合设计结果进行验证。结
1992-12-01
fisica matematica. ABSTRACT - We consider a new method for the numerical solution both of non- linear systems of equations and of cornplementauity...8217 Universith di Rama "La Sapienza- 00185 Roma, Italy Maria Cristina Recchioni Istituto Nazionale di Alta Matematica "’F. Severi" pia.ale Aldo Moro 5 00185
Sozio, Gerry
2009-01-01
Senior secondary students cover numerical integration techniques in their mathematics courses. In particular, students would be familiar with the "midpoint rule," the elementary "trapezoidal rule" and "Simpson's rule." This article derives these techniques by methods which secondary students may not be familiar with and an approach that…
The macular mapping test: a reliability study
Davies Leon N
2005-08-01
Full Text Available Abstract Background Age-related macular degeneration (ARMD is the leading cause of visual disability in people over 60 years of age in the developed world. The success of treatment deteriorates with increased latency of diagnosis. The purpose of this study was to determine the reliability of the macular mapping test (MMT, and to investigate its potential as a screening tool. Methods The study population comprised of 31 healthy eyes of 31 participants. To assess reliability, four macular mapping test (MMT measurements were taken in two sessions separated by one hour by two practitioners, with reversal of order in the second session. MMT readings were also taken from 17 age-related maculopathy (ARM, and 12 AMD affected eyes. Results For the normal cohort, average MMT scores ranged from 85.5 to 100.0 MMT points. Scores ranged from 79.0 to 99.0 for the ARM group and from 9.0 to 92.0 for the AMD group. MMT scores were reliable to within ± 7.0 points. The difference between AMD affected eyes and controls (z = 3.761, p = Conclusion The reliability data shows that a change of 14 points or more is required to indicate a clinically significant change. This value is required for use of the MMT as an outcome measure in clinical trials. Although there was no difference between MMT scores from ARM affected eyes and controls, the MMT has the advantage over the Amsler grid in that it uses a letter target, has a peripheral fixation aid, and it provides a numerical score. This score could be beneficial in office and home monitoring of AMD progression, as well as an outcome measure in clinical research.
Enlightenment on Computer Network Reliability From Transportation Network Reliability
Hu Wenjun; Zhou Xizhao
2011-01-01
Referring to transportation network reliability problem, five new computer network reliability definitions are proposed and discussed. They are computer network connectivity reliability, computer network time reliability, computer network capacity reliability, computer network behavior reliability and computer network potential reliability. Finally strategies are suggested to enhance network reliability.
Mazoyer, Johan; Norman, Colin; N'Diaye, Mamadou; van der Marel, Roeland P; Soummer, Rémi
2015-01-01
The new frontier in the quest for the highest contrast levels in the focal plane of a coronagraph is now the correction of the large diffractive artifacts effects introduced at the science camera by apertures of increasing complexity. The coronagraph for the WFIRST/AFTA mission will be the first of such instruments in space with a two Deformable Mirrors wavefront control system. Regardless of the control algorithm for these multi Deformable Mirrors, they will have to rely on quick and accurate simulation of the propagation effects introduced by the out-of-pupil surface. In the first part of this paper, we present the analytical description of the different approximations to simulate these propagation effects. In Annex A, we prove analytically that, in the special case of surfaces inducing a converging beam, the Fresnel method yields high fidelity for simulations of these effects. We provide numerical simulations showing this effect. In the second part, we use these tools in the framework of the Active Compens...
von Holst, Hans; Li, Xiaogai
2013-07-01
Although the consequences of traumatic brain injury (TBI) and its treatment have been improved, there is still a substantial lack of understanding the mechanisms. Numerical simulation of the impact can throw further lights on site and mechanism of action. A finite element model of the human head and brain tissue was used to simulate TBI. The consequences of gradually increased kinetic energy transfer was analyzed by evaluating the impact intracranial pressure (ICP), strain level, and their potential influences on binding forces in folded protein structures. The gradually increased kinetic energy was found to have the potential to break apart bonds of Van der Waals in all impacts and hydrogen bonds at simulated impacts from 6 m/s and higher, thereby superseding the energy in folded protein structures. Further, impacts below 6 m/s showed none or very slight increase in impact ICP and strain levels, whereas impacts of 6 m/s or higher showed a gradual increase of the impact ICP and strain levels reaching over 1000 KPa and over 30%, respectively. The present simulation study shows that the free kinetic energy transfer, impact ICP, and strain levels all have the potential to initiate cytotoxic brain tissue edema by unfolding protein structures. The definition of mild, moderate, and severe TBI should thus be looked upon as the same condition and separated only by a gradual severity of impact.
Derivation of Reliability Index Vector Formula for Series System and Its Application
KANG Hai-gui; ZHANG Jing; SUN Ying-wei; GUO Wei
2013-01-01
In this study,a reliability index vector formula is proposed for series system with two failure modes in term of the concept of reliability index vector and equivalent failure modes.Firstly,the reliability index vector is introduced to determine the correlation coefficient between two failure modes,and then,the reliability index vector of a series system can be obtained.Several numerical cases and an analysis on offshore platform are performed,and the results show that this scheme provided here has better computational accuracy,and its calculation process is simpler for the series systems reliability calculations compared with the other methods.Also this scheme is more convenient for the engineering applications.
Reliability-based design optimization using a moment method and a kriging metamodel
Ju, Byeong Hyeon; Chai Lee, Byung
2008-05-01
Reliability-based design optimization (RBDO) has been used for optimizing engineering systems with uncertainties in design variables and system parameters. RBDO involves reliability analysis, which requires a large amount of computational effort, so it is important to select an efficient method for reliability analysis. Of the many methods for reliability analysis, a moment method, which is called the fourth moment method, is known to be less expensive for moderate size problems and requires neither iteration nor the computation of derivatives. Despite these advantages, previous research on RBDO has been mainly based on the first-order reliability method and relatively little attention has been paid to moment-based RBDO. This article considers difficulties in implementing the moment method into RBDO; they are solved using a kriging metamodel with an active constraint strategy. Three numerical examples are tested and the results show that the proposed method is efficient and accurate.
Stochastic modeling for reliability shocks, burn-in and heterogeneous populations
Finkelstein, Maxim
2013-01-01
Focusing on shocks modeling, burn-in and heterogeneous populations, Stochastic Modeling for Reliability naturally combines these three topics in the unified stochastic framework and presents numerous practical examples that illustrate recent theoretical findings of the authors. The populations of manufactured items in industry are usually heterogeneous. However, the conventional reliability analysis is performed under the implicit assumption of homogeneity, which can result in distortion of the corresponding reliability indices and various misconceptions. Stochastic Modeling for Reliability fills this gap and presents the basics and further developments of reliability theory for heterogeneous populations. Specifically, the authors consider burn-in as a method of elimination of ‘weak’ items from heterogeneous populations. The real life objects are operating in a changing environment. One of the ways to model an impact of this environment is via the external shocks occurring in accordance with some stocha...
Chen, Qing; Zhang, Jinxiu; Hu, Ze
2017-02-23
This article investigates the dynamic topology control problemof satellite cluster networks (SCNs) in Earth observation (EO) missions by applying a novel metric of stability for inter-satellite links (ISLs). The properties of the periodicity and predictability of satellites' relative position are involved in the link cost metric which is to give a selection criterion for choosing the most reliable data routing paths. Also, a cooperative work model with reliability is proposed for the situation of emergency EO missions. Based on the link cost metric and the proposed reliability model, a reliability assurance topology control algorithm and its corresponding dynamic topology control (RAT) strategy are established to maximize the stability of data transmission in the SCNs. The SCNs scenario is tested through some numeric simulations of the topology stability of average topology lifetime and average packet loss rate. Simulation results show that the proposed reliable strategy applied in SCNs significantly improves the data transmission performance and prolongs the average topology lifetime.
solveME: fast and reliable solution of nonlinear ME models
Yang, Laurence; Ma, Ding; Ebrahim, Ali
2016-01-01
reconstructions (M models), are multiscale, and growth maximization is a nonlinear programming (NLP) problem, mainly due to macromolecule dilution constraints. Results: Here, we address these computational challenges. We develop a fast and numerically reliable solution method for growth maximization in ME models...
Human Reliability Program Overview
Bodin, Michael
2012-09-25
This presentation covers the high points of the Human Reliability Program, including certification/decertification, critical positions, due process, organizational structure, program components, personnel security, an overview of the US DOE reliability program, retirees and academia, and security program integration.
Berg, Melanie; LaBel, Kenneth A.
2016-01-01
This presentation focuses on reliability and trust for the users portion of the FPGA design flow. It is assumed that the manufacturer prior to hand-off to the user tests FPGA internal components. The objective is to present the challenges of creating reliable and trusted designs. The following will be addressed: What makes a design vulnerable to functional flaws (reliability) or attackers (trust)? What are the challenges for verifying a reliable design versus a trusted design?
Software Reliability Experimentation and Control
Kai-Yuan Cai
2006-01-01
This paper classifies software researches as theoretical researches, experimental researches, and engineering researches, and is mainly concerned with the experimental researches with focus on software reliability experimentation and control. The state-of-the-art of experimental or empirical studies is reviewed. A new experimentation methodology is proposed, which is largely theory discovering oriented. Several unexpected results of experimental studies are presented to justify the importance of software reliability experimentation and control. Finally, a few topics that deserve future investigation are identified.
Viking Lander reliability program
Pilny, M. J.
1978-01-01
The Viking Lander reliability program is reviewed with attention given to the development of the reliability program requirements, reliability program management, documents evaluation, failure modes evaluation, production variation control, failure reporting and correction, and the parts program. Lander hardware failures which have occurred during the mission are listed.
Boolean networks with reliable dynamics
Peixoto, Tiago P
2009-01-01
We investigated the properties of Boolean networks that follow a given reliable trajectory in state space. A reliable trajectory is defined as a sequence of states which is independent of the order in which the nodes are updated. We explored numerically the topology, the update functions, and the state space structure of these networks, which we constructed using a minimum number of links and the simplest update functions. We found that the clustering coefficient is larger than in random networks, and that the probability distribution of three-node motifs is similar to that found in gene regulation networks. Among the update functions, only a subset of all possible functions occur, and they can be classified according to their probability. More homogeneous functions occur more often, leading to a dominance of canalyzing functions. Finally, we studied the entire state space of the networks. We observed that with increasing systems size, fixed points become more dominant, moving the networks close to the frozen...
Load Control System Reliability
Trudnowski, Daniel [Montana Tech of the Univ. of Montana, Butte, MT (United States)
2015-04-03
This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”
Numerical Ultimate Ruin Probabilities under Interest Force
Juma Kasozi
2005-01-01
Full Text Available This work addresses the issue of ruin of an insurer whose portfolio is exposed to insurance risk arising from the classical surplus process. Availability of a positive interest rate in the financial world forces the insurer to invest into a risk free asset. We derive a linear Volterra integral equation of the second kind and apply an order four Block-by-block method in conjuction with the Simpson rule to solve the Volterra equation for ultimate ruin. This probability is arrived at by taking a linear combination of some two solutions to the Volterra integral equation. The several numerical examples given show that our results are excellent and reliable.
Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.
2017-05-01
In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and deformation of the shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron aortic prosthesis is modelled as an orthotropic circular cylindrical shell described by means of the Novozhilov nonlinear shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. For the first time in literature, coupled fluid-structure Lagrange equations of motion for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron aortic graft conveying blood flow. A pulsatile time-dependent blood flow model is considered by applying the first harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure, considering the propagation of pressure and velocity changes inside the shell, is here presented via frequency-response curves, time histories, bifurcation
Reliability and validity in medical research
2012-01-01
Scientists commonly refer to study instruments duringmedical research. In fact, the reliability and validity issuesgo beyond psychometric studies and can be linked withany kind measurements. In this study we aimed to explainthe reliability and validity concepts by giving examples.It is possible to evaluate the reliability and validity of aninstrument by scientific methods. If we speak of reliability,we have to mention stability (having the same results inrepeated measurements from the same sa...
Introduction to quality and reliability engineering
Jiang, Renyan
2015-01-01
This book presents the state-of-the-art in quality and reliability engineering from a product life cycle standpoint. Topics in reliability include reliability models, life data analysis and modeling, design for reliability and accelerated life testing, while topics in quality include design for quality, acceptance sampling and supplier selection, statistical process control, production tests such as screening and burn-in, warranty and maintenance. The book provides comprehensive insights into two closely related subjects, and includes a wealth of examples and problems to enhance reader comprehension and link theory and practice. All numerical examples can be easily solved using Microsoft Excel. The book is intended for senior undergraduate and post-graduate students in related engineering and management programs such as mechanical engineering, manufacturing engineering, industrial engineering and engineering management programs, as well as for researchers and engineers in the quality and reliability fields. D...
Reliability analysis in intelligent machines
Mcinroy, John E.; Saridis, George N.
1990-01-01
Given an explicit task to be executed, an intelligent machine must be able to find the probability of success, or reliability, of alternative control and sensing strategies. By using concepts for information theory and reliability theory, new techniques for finding the reliability corresponding to alternative subsets of control and sensing strategies are proposed such that a desired set of specifications can be satisfied. The analysis is straightforward, provided that a set of Gaussian random state variables is available. An example problem illustrates the technique, and general reliability results are presented for visual servoing with a computed torque-control algorithm. Moreover, the example illustrates the principle of increasing precision with decreasing intelligence at the execution level of an intelligent machine.
VCSEL reliability: a user's perspective
McElfresh, David K.; Lopez, Leoncio D.; Melanson, Robert; Vacar, Dan
2005-03-01
VCSEL arrays are being considered for use in interconnect applications that require high speed, high bandwidth, high density, and high reliability. In order to better understand the reliability of VCSEL arrays, we initiated an internal project at SUN Microsystems, Inc. In this paper, we present preliminary results of an ongoing accelerated temperature-humidity-bias stress test on VCSEL arrays from several manufacturers. This test revealed no significant differences between the reliability of AlGaAs, oxide confined VCSEL arrays constructed with a trench oxide and mesa for isolation. This test did find that the reliability of arrays needs to be measured on arrays and not be estimated with the data from singulated VCSELs as is a common practice.
Reliability Equivalence Factors of a System with 2 Non-identical Mixed Lifetimes and Delayed Time
Abdelfattah Mustafa
2011-01-01
Full Text Available Problem statement: In reliability theory and operations research, there are many methods and techniques to improve the performance of a system. The aim of this study is to generalize reliability equivalence technique to apply it to a mixed failure lifetimes system f1 (t, f2 (t with delayed time. Approach: We shall improve the system by using some reliability techniques: (i reducing the failure for some lifetimes; (ii add hot duplication components; (iii add cold duplication components; (iv add cold duplication components with imperfect switches. We start by establishing two different types of reliability equivalence factors, the Survival Reliability Equivalence (SRE and Mean Reliability Equivalence (MRE factors. Also, we introduced some numerical results. Results: The system reliability function and mean time to failure will be used as reference of the system performances. For this reason, we obtain the reliability functions and mean time to failures of the original and improved systems using each improving methods. Conclusion: The results can be used to distinguish between the original and improved systems performances and calculate the equivalent between different cases of improving methods.
Remarks on numerical semigroups
Torres, F
1995-01-01
We extend results on Weierstrass semigroups at ramified points of double covering of curves to any numerical semigroup whose genus is large enough. As an application we strengthen the properties concerning Weierstrass weights in \\cited{To}.
Supply chain reliability modelling
Eugen Zaitsev
2012-03-01
Full Text Available Background: Today it is virtually impossible to operate alone on the international level in the logistics business. This promotes the establishment and development of new integrated business entities - logistic operators. However, such cooperation within a supply chain creates also many problems related to the supply chain reliability as well as the optimization of the supplies planning. The aim of this paper was to develop and formulate the mathematical model and algorithms to find the optimum plan of supplies by using economic criterion and the model for the probability evaluating of non-failure operation of supply chain. Methods: The mathematical model and algorithms to find the optimum plan of supplies were developed and formulated by using economic criterion and the model for the probability evaluating of non-failure operation of supply chain. Results and conclusions: The problem of ensuring failure-free performance of goods supply channel analyzed in the paper is characteristic of distributed network systems that make active use of business process outsourcing technologies. The complex planning problem occurring in such systems that requires taking into account the consumer's requirements for failure-free performance in terms of supply volumes and correctness can be reduced to a relatively simple linear programming problem through logical analysis of the structures. The sequence of the operations, which should be taken into account during the process of the supply planning with the supplier's functional reliability, was presented.
MING Zhimao; TAO Junyong; ZHANG Yunan; YI Xiaoshan; CHEN Xun
2009-01-01
New armament systems are subjected to the method for dealing with multi-stage system reliability-growth statistical problems of diverse population in order to improve reliability before starting mass production. Aiming at the test process which is high expense and small sample-size in the development of complex system, the specific methods are studied on how to process the statistical information of Bayesian reliability growth regarding diverse populations. Firstly, according to the characteristics of reliability growth during product development, the Bayesian method is used to integrate the testing information of multi-stage and the order relations of distribution parameters. And then a Gamma-Beta prior distribution is proposed based on non-homogeneous Poisson process(NHPP) corresponding to the reliability growth process. The posterior distribution of reliability parameters is obtained regarding different stages of product, and the reliability parameters are evaluated based on the posterior distribution. Finally, Bayesian approach proposed in this paper for multi-stage reliability growth test is applied to the test process which is small sample-size in the astronautics filed. The results of a numerical example show that the presented model can make use of the diverse information synthetically, and pave the way for the application of the Bayesian model for multi-stage reliability growth test evaluation with small sample-size. The method is useful for evaluating multi-stage system reliability and making reliability growth plan rationally.
On reliability optimization for power generation systems
无
2005-01-01
The reliability level of a power generation system is an important problem which is concerned by both electricity producers and electricity consumers. Why? It is known that the high reliability level may result in additional utility cost, and the low reliability level may result in additional consumer's cost, so the optimum reliability level should be determined such that the total cost can reach its minimum. Four optimization models for power generation system reliability are constructed, and the proven efficient solutions for these models are also given.
Ultra High Performance, Highly Reliable, Numeric Intensive Processors and Systems
1989-10-01
to design high-performance DSP/IP systems using either off-the-shelf components or application specific integrated circuitry [ ASIC ]. -9 - HSDAL . ARO...are the chirp-z transform ( CZT ) [13] and (Rader’s) Prime Factor Transform (PFT) [11]. The RNS/ CZT is being studied by a group a MITRE [14] and is given...PFT RNS/CRNS/QRNS implementation has dynamic range requirements on the order of NQ2 (vs NQ4 for the CZT and much higher for the FFT). Therefore, the
Efficient Numerical Evaluation of Feynman Integral
Li, Zhao; Yan, Qi-Shu; Zhao, Xiaoran
2016-01-01
Feynman loop integral is the key ingredient of high order radiation effect, which is responsible for reliable and accurate theoretical prediction. We improve the efficiency of numerical integration in sector decomposition by implementing quasi-Monte Carlo method associated with the technique of CUDA/GPU. For demonstration we present the results of several Feynman integrals up to two loops in both Euclidean and physical kinematic regions in comparison with those obtained from FIESTA3. It is shown that both planar and non-planar two-loop master integrals in physical kinematic region can be evaluated in less than half minute with $\\mathcal{O}(10^{-3})$ accuracy, which makes the direct numerical approach viable for the precise investigation on the high order effect in multi-loop processes, e.g. the next-to-leading order QCD effect in Higgs pair production via gluon fusion with finite top quark mass.
Tang, Y.; Kriebitzsch, S.H.L.; van der Hoef, Martin Anton; Peters, E.A.J.F.; Kuipers, J.A.M.
2014-01-01
Simulations with an iterative immersed boundary method (IBM) are performed to predict the drag force for gas–solid flows at intermediate Reynolds number (Re). A methodology is developed to obtain highly accurate IBM results at relatively low computational cost. First of all, “resolution-free” gas–so
Numerical and physical model study of a vertical slot fishway
Bombač Martin
2014-06-01
Full Text Available This paper presents the results of an experimental and numerical study of a vertical slot fishway (VSF. A 2-D depth-averaged shallow water numerical model PCFLOW2D coupled with three different turbulent models (constant eddy viscosity, Smagorinsky and k - ε was used. A detailed analysis of numerical parameters needed for a correct simulation of the phenomenon was carried out. Besides the velocity field, attention was paid to important hydraulic parameters such as maximum velocity in the slot region and energy dissipation rate ε in order to evaluate the performance of VSF. A scaled physical hydraulic model was built to ensure reliable experimental data for the validation of the numerical model. Simulations of variant configurations of VSF showed that even small changes in geometry can produce more fishfriendly flow characteristics in pools. The present study indicates that the PCFLOW2D program is an appropriate tool to meet the main demands of the VSF design.
Reliability and safety engineering
Verma, Ajit Kumar; Karanki, Durga Rao
2016-01-01
Reliability and safety are core issues that must be addressed throughout the life cycle of engineering systems. Reliability and Safety Engineering presents an overview of the basic concepts, together with simple and practical illustrations. The authors present reliability terminology in various engineering fields, viz.,electronics engineering, software engineering, mechanical engineering, structural engineering and power systems engineering. The book describes the latest applications in the area of probabilistic safety assessment, such as technical specification optimization, risk monitoring and risk informed in-service inspection. Reliability and safety studies must, inevitably, deal with uncertainty, so the book includes uncertainty propagation methods: Monte Carlo simulation, fuzzy arithmetic, Dempster-Shafer theory and probability bounds. Reliability and Safety Engineering also highlights advances in system reliability and safety assessment including dynamic system modeling and uncertainty management. Cas...
Jianwen Liang; Zhongxian Liu
2009-01-01
This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated (either drained or undrained) cases. There are large phase shift between the dry case and the saturated cases, as well as slightly longer resultant wavelengths for the undrained case than those for the drained case and longer resultant wavelengths for the drained case than those for the dry case. For small porosity the surface displacement amplitudes for the saturated cases are almost identical to those for the dry case; while for large porosity, the effect of drainage condition becomes significant, and the surface displacement amplitudes for the undrained case are larger than those for the drained case. As the incident frequency increases, the effect of porosity becomes significant, and more significant for the undrained case than that for the drained case. As the porosity increases, the pore pressures increase significantly but their oscillations become smoother. As the incident frequency increases, the pore pressures become more complicated.
ZHENG Changling; WANG Chunyi
2006-01-01
With the rapid development of industrialization and urbanization, the enrichment of tropospheric ozone and carbon dioxide concentration at striking rates has caused effects on biosphere, especially on crops. It is generally accepted that the increase of CO2 concentration will have obverse effects on plant productivity while ozone is reported as the air pollutant most damaging to agricultural crops and other plants. The Model of Carbon and Nitrogen Biogeochemistry in Agroecosystems (DNDC) was adapted to evaluate simultaneously impacts of climate change on winter wheat.Growth development and yield formation of winter wheat under different Os and CO2 concentration conditions are simulated with the improved DNDC model whose structure has been described in another paper. Through adjusting the DNDC model applicability, winter wheat growth and development in Gucheng Station were simulated well in 1993 and 1999, which is in favor of modifying the model further. The model was validated against experiment observation, including development stage data, leaf area index, each organ biomass, and total aboveground biomass. Sensitivity tests demonstrated that the simulated results in development stage and biomass were sensitive to temperature change. The main conclusions of the paper are the following: 1) The growth and yield of winter wheat under CO2 concentration of 500 ppmv, 700 ppmv and the current ozone concentration are simulated respectively by the model. The results are well fitted with the observed data of OTCs experiments. The results show that increase of CO2 concentration may improve the growth of winter wheat and elevate the yield. 2) The growth and yield of winter wheat under O3 concentration of 50 ppbv, 100 ppbv, 200 ppbv and the based concentration CO2 are simulated respectively by the model. The simulated curves of stem, leaf, and spike organs growth as well as leaf area index are well accounted with the observed data. The results reveal that ozone has negative
Measurement System Reliability Assessment
Kłos Ryszard
2015-06-01
Full Text Available Decision-making in problem situations is based on up-to-date and reliable information. A great deal of information is subject to rapid changes, hence it may be outdated or manipulated and enforce erroneous decisions. It is crucial to have the possibility to assess the obtained information. In order to ensure its reliability it is best to obtain it with an own measurement process. In such a case, conducting assessment of measurement system reliability seems to be crucial. The article describes general approach to assessing reliability of measurement systems.
Dai, Honghua; Smirnov, Evgueni
2012-01-01
Reliable Knowledge Discovery focuses on theory, methods, and techniques for RKDD, a new sub-field of KDD. It studies the theory and methods to assure the reliability and trustworthiness of discovered knowledge and to maintain the stability and consistency of knowledge discovery processes. RKDD has a broad spectrum of applications, especially in critical domains like medicine, finance, and military. Reliable Knowledge Discovery also presents methods and techniques for designing robust knowledge-discovery processes. Approaches to assessing the reliability of the discovered knowledge are introduc
Kopáček Jaroslav
2016-01-01
Full Text Available This paper focuses on the importance of detection reliability, especially in complex fluid systems for demanding production technology. The initial criterion for assessing the reliability is the failure of object (element, which is seen as a random variable and their data (values can be processed using by the mathematical methods of theory probability and statistics. They are defined the basic indicators of reliability and their applications in calculations of serial, parallel and backed-up systems. For illustration, there are calculation examples of indicators of reliability for various elements of the system and for the selected pneumatic circuit.
Circuit design for reliability
Cao, Yu; Wirth, Gilson
2015-01-01
This book presents physical understanding, modeling and simulation, on-chip characterization, layout solutions, and design techniques that are effective to enhance the reliability of various circuit units. The authors provide readers with techniques for state of the art and future technologies, ranging from technology modeling, fault detection and analysis, circuit hardening, and reliability management. Provides comprehensive review on various reliability mechanisms at sub-45nm nodes; Describes practical modeling and characterization techniques for reliability; Includes thorough presentation of robust design techniques for major VLSI design units; Promotes physical understanding with first-principle simulations.
Macario Galang, Jan Albert; Narod Eco, Rodrigo; Mahar Francisco Lagmay, Alfredo
2015-04-01
The M 7.2 October 15, 2013 Bohol earthquake is the most destructive earthquake to hit the Philippines since 2012. The epicenter was located in Sagbayan municipality, central Bohol and was generated by a previously unmapped reverse fault called the "Inabanga Fault". Its name, taken after the barangay (village) where the fault is best exposed and was first seen. The earthquake resulted in 209 fatalities and over 57 billion USD worth of damages. The earthquake generated co-seismic landslides most of which were related to fault structures. Unlike rainfall induced landslides, the trigger for co-seismic landslides happen without warning. Preparedness against this type of landslide therefore, relies heavily on the identification of fracture-related unstable slopes. To mitigate the impacts of co-seismic landslide hazards, morpho-structural orientations or discontinuity sets were mapped in the field with the aid of a 2012 IFSAR Digital Terrain Model (DTM) with 5-meter pixel resolution and landslide inventory of 456 landslides. Out the total number of landslides identified from post-earthquake high-resolution imagery, 366 or 80% intersect the structural-controlled hazard areas of Bohol. The results show the potential of this method to identify co-seismic landslide hazard areas for disaster mitigation. Along with computer methods to simulate shallow landslides, and debris flow paths, located structurally-controlled unstable zones can be used to mark unsafe areas for settlement. The method can be further improved with the use of Lidar DTMs, which has better accuracy than the IFSAR DTM. A nationwide effort under DOST-Project NOAH (DREAM-LIDAR) is underway, to map the Philippine archipelago using Lidar.
Status of numerical relativity
Masaru Shibata
2004-10-01
I describe the current status of numerical relativity from my personal point of view. Here, I focus mainly on explaining the numerical implementations necessary for simulating general relativistic phenomena such as the merger of compact binaries and stellar collapse, emphasizing the well-developed current status of such implementations that enable simulations for several astrophysical phenomena. Some of our latest results for simulation of binary neutron star mergers are briefly presented.
Reliability of the NINDS Myotatic Reflex Scale.
Litvan, I; Mangone, C A; Werden, W; Bueri, J A; Estol, C J; Garcea, D O; Rey, R C; Sica, R E; Hallett, M; Bartko, J J
1996-10-01
The assessment of deep tendon reflexes is useful for localization and diagnosis of neurologic disorders, but only a few studies have evaluated their reliability. We assessed the reliability of four neurologists, instructed in two different countries, in using the National Institute of Neurological Disorders and Stroke (NINDS) Myotatic Reflex Scale. To evaluate the role of training in using the scale, the neurologists randomly and blindly evaluated a total of 80 patients, 40 before and 40 after a training session. Inter- and intraobserver reliability were measured with kappa statistics. Our results showed substantial to near-perfect intraobserver reliability, and moderate-to-substantial interobserver reliability of the NINDS Myotatic Reflex Scale. The reproducibility was better for reflexes in the lower than in the upper extremities. Neither educational background nor the training session influenced the reliability of our results. The NINDS Myotatic Reflex Scale has sufficient reliability to be adopted as a universal scale.
Bordogna, Clelia Maria [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), UNLP, CONICET Casilla de Correo 16, Sucursal 4 (1900) La Plata (Argentina); Albano, Ezequiel V [Instituto de Investigaciones FisicoquImicas Teoricas y Aplicadas (INIFTA), UNLP, CONICET Casilla de Correo 16, Sucursal 4 (1900) La Plata (Argentina)
2007-02-14
The aim of this paper is twofold. On the one hand we present a brief overview on the application of statistical physics methods to the modelling of social phenomena focusing our attention on models for opinion formation. On the other hand, we discuss and present original results of a model for opinion formation based on the social impact theory developed by Latane. The presented model accounts for the interaction among the members of a social group under the competitive influence of a strong leader and the mass media, both supporting two different states of opinion. Extensive simulations of the model are presented, showing that they led to the observation of a rich scenery of complex behaviour including, among others, critical behaviour and phase transitions between a state of opinion dominated by the leader and another dominated by the mass media. The occurrence of interesting finite-size effects reveals that, in small communities, the opinion of the leader may prevail over that of the mass media. This observation is relevant for the understanding of social phenomena involving a finite number of individuals, in contrast to actual physical phase transitions that take place in the thermodynamic limit. Finally, we give a brief outlook of open questions and lines for future work.
Matang, Rex A. S.; Owens, Kay
2014-09-01
The Government of Papua New Guinea undertook a significant step in developing curriculum reform policy that promoted the use of Indigenous knowledge systems in teaching formal school subjects in any of the country's 800-plus Indigenous languages. The implementation of the Elementary Cultural Mathematics Syllabus is in line with the above curriculum emphasis. Given the aims of the reform, the research reported here investigated the influence of children's own mother tongue (Tok Ples) and traditional counting systems on their development of early number knowledge formally taught in schools. The study involved 272 school children from 22 elementary schools in four provinces. Each child participated in a task-based assessment interview focusing on eight task groups relating to early number knowledge. The results obtained indicate that, on average, children learning their traditional counting systems in their own language spent shorter time and made fewer mistakes in solving each task compared to those taught without Tok Ples (using English and/or the lingua franca, Tok Pisin). Possible reasons accounting for these differences are also discussed.
Maranzana, G.; Chupin, S.; Colinart, T.; Lottin, O.; Didierjean, S. [Nancy-Univ., Vandoeuvre (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee
2007-07-01
The electrodes of proton membrane exchange (PEM) fuel cells are fed by gases, whose properties are changing during their transition from the inlet to the outlet of the channels. For example, the reactant concentration decreases and the water concentration increases, the total pressure diminishes, the temperature is dependent on the local current density, and liquid water may appear or disappear. The electrode performances are not uniform, which can have impacts on the entire performances of the cell or on its durability. In order to observe and model these non-homogeneities, this paper presented an experimental study that involved designing, building, and testing a single PEM fuel cell that allowed measurement of both current density and temperature fields along the gas channels. The fuel cell was made of transparent polymethyl methacrylate (PMMA) so that the location of liquid water appearance in the channels could be observed. The first experimental results were compared with the predictions of a pseudo-2D model which assumed mass transfer to occur in the direction perpendicular to the membrane, but took into account the variations in concentrations, in total pressure, and in temperatures along the gas channels. It was concluded that the current density distribution depended greatly on water management. 10 refs., 3 figs.
Metrological Reliability of Medical Devices
Costa Monteiro, E.; Leon, L. F.
2015-02-01
The prominent development of health technologies of the 20th century triggered demands for metrological reliability of physiological measurements comprising physical, chemical and biological quantities, essential to ensure accurate and comparable results of clinical measurements. In the present work, aspects concerning metrological reliability in premarket and postmarket assessments of medical devices are discussed, pointing out challenges to be overcome. In addition, considering the social relevance of the biomeasurements results, Biometrological Principles to be pursued by research and innovation aimed at biomedical applications are proposed, along with the analysis of their contributions to guarantee the innovative health technologies compliance with the main ethical pillars of Bioethics.
Reliability Based Ship Structural Design
Dogliani, M.; Østergaard, C.; Parmentier, G.;
1996-01-01
with developments of models of load effects and of structural collapse adopted in reliability formulations which aim at calibrating partial safety factors for ship structural design. New probabilistic models of still-water load effects are developed both for tankers and for containerships. New results are presented......This paper deals with the development of different methods that allow the reliability-based design of ship structures to be transferred from the area of research to the systematic application in current design. It summarises the achievements of a three-year collaborative research project dealing...... structure of several tankers and containerships. The results of the reliability analysis were the basis for the definition of a target safety level which was used to asses the partial safety factors suitable for in a new design rules format to be adopted in modern ship structural design. Finally...
Reliability Characteristics of Power Plants
Zbynek Martinek
2017-01-01
Full Text Available This paper describes the phenomenon of reliability of power plants. It gives an explanation of the terms connected with this topic as their proper understanding is important for understanding the relations and equations which model the possible real situations. The reliability phenomenon is analysed using both the exponential distribution and the Weibull distribution. The results of our analysis are specific equations giving information about the characteristics of the power plants, the mean time of operations and the probability of failure-free operation. Equations solved for the Weibull distribution respect the failures as well as the actual operating hours. Thanks to our results, we are able to create a model of dynamic reliability for prediction of future states. It can be useful for improving the current situation of the unit as well as for creating the optimal plan of maintenance and thus have an impact on the overall economics of the operation of these power plants.
Driel, W.D. van; Yuan, C.A.; Koh, S.; Zhang, G.Q.
2011-01-01
This paper presents our effort to predict the system reliability of Solid State Lighting (SSL) applications. A SSL system is composed of a LED engine with micro-electronic driver(s) that supplies power to the optic design. Knowledge of system level reliability is not only a challenging scientific ex
Principles of Bridge Reliability
Thoft-Christensen, Palle; Nowak, Andrzej S.
The paper gives a brief introduction to the basic principles of structural reliability theory and its application to bridge engineering. Fundamental concepts like failure probability and reliability index are introduced. Ultimate as well as serviceability limit states for bridges are formulated...
Improving machinery reliability
Bloch, Heinz P
1998-01-01
This totally revised, updated and expanded edition provides proven techniques and procedures that extend machinery life, reduce maintenance costs, and achieve optimum machinery reliability. This essential text clearly describes the reliability improvement and failure avoidance steps practiced by best-of-class process plants in the U.S. and Europe.
Hawaii Electric System Reliability
Loose, Verne William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Silva Monroy, Cesar Augusto [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2012-08-01
This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.
Hawaii electric system reliability.
Silva Monroy, Cesar Augusto; Loose, Verne William
2012-09-01
This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers' views of reliability %E2%80%9Cworth%E2%80%9D and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers' views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.
Validation of Land Cover Products Using Reliability Evaluation Methods
Wenzhong Shi
2015-06-01
Full Text Available Validation of land cover products is a fundamental task prior to data applications. Current validation schemes and methods are, however, suited only for assessing classification accuracy and disregard the reliability of land cover products. The reliability evaluation of land cover products should be undertaken to provide reliable land cover information. In addition, the lack of high-quality reference data often constrains validation and affects the reliability results of land cover products. This study proposes a validation schema to evaluate the reliability of land cover products, including two methods, namely, result reliability evaluation and process reliability evaluation. Result reliability evaluation computes the reliability of land cover products using seven reliability indicators. Process reliability evaluation analyzes the reliability propagation in the data production process to obtain the reliability of land cover products. Fuzzy fault tree analysis is introduced and improved in the reliability analysis of a data production process. Research results show that the proposed reliability evaluation scheme is reasonable and can be applied to validate land cover products. Through the analysis of the seven indicators of result reliability evaluation, more information on land cover can be obtained for strategic decision-making and planning, compared with traditional accuracy assessment methods. Process reliability evaluation without the need for reference data can facilitate the validation and reflect the change trends of reliabilities to some extent.
Algora, Carlos; Espinet-Gonzalez, Pilar; Vazquez, Manuel; Bosco, Nick; Miller, David; Kurtz, Sarah; Rubio, Francisca; McConnell,Robert
2016-04-15
This chapter describes the accumulated knowledge on CPV reliability with its fundamentals and qualification. It explains the reliability of solar cells, modules (including optics) and plants. The chapter discusses the statistical distributions, namely exponential, normal and Weibull. The reliability of solar cells includes: namely the issues in accelerated aging tests in CPV solar cells, types of failure and failures in real time operation. The chapter explores the accelerated life tests, namely qualitative life tests (mainly HALT) and quantitative accelerated life tests (QALT). It examines other well proven and experienced PV cells and/or semiconductor devices, which share similar semiconductor materials, manufacturing techniques or operating conditions, namely, III-V space solar cells and light emitting diodes (LEDs). It addresses each of the identified reliability issues and presents the current state of the art knowledge for their testing and evaluation. Finally, the chapter summarizes the CPV qualification and reliability standards.
Reliability of plantar pressure platforms.
Hafer, Jocelyn F; Lenhoff, Mark W; Song, Jinsup; Jordan, Joanne M; Hannan, Marian T; Hillstrom, Howard J
2013-07-01
Plantar pressure measurement is common practice in many research and clinical protocols. While the accuracy of some plantar pressure measuring devices and methods for ensuring consistency in data collection on plantar pressure measuring devices have been reported, the reliability of different devices when testing the same individuals is not known. This study calculated intra-mat, intra-manufacturer, and inter-manufacturer reliability of plantar pressure parameters as well as the number of plantar pressure trials needed to reach a stable estimate of the mean for an individual. Twenty-two healthy adults completed ten walking trials across each of two Novel emed-x(®) and two Tekscan MatScan(®) plantar pressure measuring devices in a single visit. Intraclass correlation (ICC) was used to describe the agreement between values measured by different devices. All intra-platform reliability correlations were greater than 0.70. All inter-emed-x(®) reliability correlations were greater than 0.70. Inter-MatScan(®) reliability correlations were greater than 0.70 in 31 and 52 of 56 parameters when looking at a 10-trial average and a 5-trial average, respectively. Inter-manufacturer reliability including all four devices was greater than 0.70 for 52 and 56 of 56 parameters when looking at a 10-trial average and a 5-trial average, respectively. All parameters reached a value within 90% of an unbiased estimate of the mean within five trials. Overall, reliability results are encouraging for investigators and clinicians who may have plantar pressure data sets that include data collected on different devices.
Yingjun Jiang
2015-04-01
Full Text Available In order to better understand the mechanical properties of graded crushed rocks (GCRs and to optimize the relevant design, a numerical test method based on the particle flow modeling technique PFC2D is developed for the California bearing ratio (CBR test on GCRs. The effects of different testing conditions and micro-mechanical parameters used in the model on the CBR numerical results have been systematically studied. The reliability of the numerical technique is verified. The numerical results suggest that the influences of the loading rate and Poisson's ratio on the CBR numerical test results are not significant. As such, a loading rate of 1.0–3.0 mm/min, a piston diameter of 5 cm, a specimen height of 15 cm and a specimen diameter of 15 cm are adopted for the CBR numerical test. The numerical results reveal that the CBR values increase with the friction coefficient at the contact and shear modulus of the rocks, while the influence of Poisson's ratio on the CBR values is insignificant. The close agreement between the CBR numerical results and experimental results suggests that the numerical simulation of the CBR values is promising to help assess the mechanical properties of GCRs and to optimize the grading design. Besides, the numerical study can provide useful insights on the mesoscopic mechanism.
Measuring reliability under epistemic uncertainty:Review on non-probabilistic reliability metrics
Kang Rui; Zhang Qingyuan; Zeng Zhiguo; Enrico Zio; Li Xiaoyang
2016-01-01
In this paper, a systematic review of non-probabilistic reliability metrics is conducted to assist the selection of appropriate reliability metrics to model the influence of epistemic uncertainty. Five frequently used non-probabilistic reliability metrics are critically reviewed, i.e., evidence-theory-based reliability metrics, interval-analysis-based reliability metrics, fuzzy-interval-analysis-based reliability metrics, possibility-theory-based reliability metrics (posbist reliability) and uncertainty-theory-based reliability metrics (belief reliability). It is pointed out that a qualified reli-ability metric that is able to consider the effect of epistemic uncertainty needs to (1) compensate the conservatism in the estimations of the component-level reliability metrics caused by epistemic uncertainty, and (2) satisfy the duality axiom, otherwise it might lead to paradoxical and confusing results in engineering applications. The five commonly used non-probabilistic reliability metrics are compared in terms of these two properties, and the comparison can serve as a basis for the selection of the appropriate reliability metrics.
Software reliability models for critical applications
Pham, H.; Pham, M.
1991-12-01
This report presents the results of the first phase of the ongoing EG&G Idaho, Inc. Software Reliability Research Program. The program is studying the existing software reliability models and proposes a state-of-the-art software reliability model that is relevant to the nuclear reactor control environment. This report consists of three parts: (1) summaries of the literature review of existing software reliability and fault tolerant software reliability models and their related issues, (2) proposed technique for software reliability enhancement, and (3) general discussion and future research. The development of this proposed state-of-the-art software reliability model will be performed in the second place. 407 refs., 4 figs., 2 tabs.
Software reliability models for critical applications
Pham, H.; Pham, M.
1991-12-01
This report presents the results of the first phase of the ongoing EG G Idaho, Inc. Software Reliability Research Program. The program is studying the existing software reliability models and proposes a state-of-the-art software reliability model that is relevant to the nuclear reactor control environment. This report consists of three parts: (1) summaries of the literature review of existing software reliability and fault tolerant software reliability models and their related issues, (2) proposed technique for software reliability enhancement, and (3) general discussion and future research. The development of this proposed state-of-the-art software reliability model will be performed in the second place. 407 refs., 4 figs., 2 tabs.
On the reliability of Seasonal Climate Forecasts
Weisheimer, Antje
2013-01-01
Seasonal climate forecasts are being used increasingly across a range of application sectors. A recent UK governmental report asked: How good are seasonal climate forecasts on a scale of 1-5 (where 5 is very good), and how good can we expect them to be in 30 years time? Seasonal climate forecasts are made from ensembles of integrations of numerical models of climate. We argue that goodness should be assessed primarily in terms of the probabilistic reliability of these ensemble-based forecasts and that a 5 should be reserved for systems which are not only reliable overall, but where, in particular, small ensemble spread is a reliable indicator of low ensemble forecast error. We study the reliability of regional temperature and precipitation forecasts of the current operational seasonal forecast system of the European Centre for Medium-Range Weather Forecasts, universally regarded as a world leading operational institute producing seasonal climate forecasts. A wide range of goodness rankings, depending on regio...
Numerical Value Results OF Guassian Beam Focussing
K.X. He; Alan Chow; Jiada Mo; Wang Zhuo
2003-01-01
@@ 1Lens is placed in beam waist We consider the case of a Gaussian beam that is incident at its waist on a thin lens of focal length f.To find the location of the waist of the output beam and the beam radius at that point,we start with the ABCD law.
Reliability Allocation of Underwater Experiment System Based on Particle Swarm Optimization
Lu Xiong
2013-06-01
Full Text Available The problem of system reliability allocation is often solved by direct search method. The shortage, which affects the application of this method, is the large calculation amount of complex system architecture. Particle Swarm Optimization (PSO is a popular and bionic algorithm based on the social behavior associated with bird flocking for optimization problems. The particle swarm optimization, which attracted the interest of researchers. In this paper, a kind of PSO algorithm is proposed to solve underwater experimental system reliability problems. In addition, the reliability of the system model is established as well, the model is numerically simulated by PSO algorithm and examples are provided. The results show that compared to other algorithms, PSO has a better adaptability and can solve the optimal solution more stably without the precocious weakness, which is more suitable for reliability optimization of a system underwater with a more complex structure.
System reliability analysis for kinematic performance of planar mechanisms
ZHANG YiMin; HUANG XianZhen; ZHANG XuFang; HE XiangDong; WEN BangChun
2009-01-01
Based on the reliability and mechanism kinematic accuracy theories, we propose a general methodology for system reliability analysis of kinematic performance of planar mechanisms. The loop closure equations are used to estimate the kinematic performance errors of planar mechanisms. Reliability and system reliability theories are introduced to develop the limit state functions (LSF) for failure of kinematic performance qualities. The statistical fourth moment method and the Edgeworth series technique are used on system reliability analysis for kinematic performance of planar mechanisms, which relax the restrictions of probability distribution of design variables. Finally, the practicality, efficiency and accuracy of the proposed method are demonstrated by numerical examples.
Reliability Based Optimization of Composite Laminates for Frequency Constraint
Wu Hao; Yan Ying; Liu Yujia
2008-01-01
The reliability based optimization (RBO) issue of composite laminates under fundamental frequency constraint is studied. Considering the uncertainties of material properties, the frequency constraint reliability of the structure is evaluated by the combination of response surface method (RSM) and finite element method. An optimization algorithm is developed based on the mechanism of laminate frequency characteristics, to optimize the laminate in terms of the ply amount and orientation angles. Numerical examples of composite laminates and cylindrical shell illustrate the advantages of the present optimization algorithm on the efficiency and applicability respects.The optimal solutions of RBO are obviously different from the deterministic optimization results, and the necessity of considering material property uncertainties in the composite srtuctural frequency constraint optimization is revealed.
Gupta, P.P.; Sharma, R.K.
1986-01-01
The reliability behaviour of a non-repairable parallel redundant complex system which is nothing but a power plant is investigated. The object of the system is to supply power generated by three generators from a power house to a very critical consumer, connected by cables and switches etc. The reliability of the power supply to the critical consumer has been obtained by using the Boolean Function technique. Moreover, an important parameter of reliability, viz. M.T.T.F. (mean time to failure), has also been computed for exponential failure rates of components. A numerical example with graphs has also been appended in the end to highlight the important results.
Reliability Modeling of Wind Turbines
Kostandyan, Erik
Cost reductions for offshore wind turbines are a substantial requirement in order to make offshore wind energy more competitive compared to other energy supply methods. During the 20 – 25 years of wind turbines useful life, Operation & Maintenance costs are typically estimated to be a quarter...... the actions should be made and the type of actions requires knowledge on the accumulated damage or degradation state of the wind turbine components. For offshore wind turbines, the action times could be extended due to weather restrictions and result in damage or degradation increase of the remaining...... for Operation & Maintenance planning. Concentrating efforts on development of such models, this research is focused on reliability modeling of Wind Turbine critical subsystems (especially the power converter system). For reliability assessment of these components, structural reliability methods are applied...
Numerical Solution of Parabolic Equations
Østerby, Ole
These lecture notes are designed for a one-semester course on finite-difference methods for parabolic equations. These equations which traditionally are used for describing diffusion and heat-conduction problems in Geology, Physics, and Chemistry have recently found applications in Finance Theory....... Among the special features of this book can be mentioned the presentation of a practical approach to reliable estimates of the global error, including warning signals if the reliability is questionable. The technique is generally applicable for estimating the discretization error in numerical...... approximations which depend on a step size, such as numerical integration and solution of ordinary and partial differential equations. An integral part of the error estimation is the estimation of the order of the method and can thus satisfy the inquisitive mind: Is the order what we expect it to be from theopry...
Reliability of quantitative content analyses
Enschot-van Dijk, R. van
2014-01-01
Reliable coding of stimuli is a daunting task that often yields unsatisfactory results. This paper discusses a case study in which tropes (e.g., metaphors, puns) in TV commercials were analyzed as well the extent and location of verbal and visual anchoring (i.e., explanation) of these tropes. After
Reliability Analysis of Money Habitudes
Delgadillo, Lucy M.; Bushman, Brittani S.
2015-01-01
Use of the Money Habitudes exercise has gained popularity among various financial professionals. This article reports on the reliability of this resource. A survey administered to young adults at a western state university was conducted, and each Habitude or "domain" was analyzed using Cronbach's alpha procedures. Results showed all six…
The Reliability of College Grades
Beatty, Adam S.; Walmsley, Philip T.; Sackett, Paul R.; Kuncel, Nathan R.; Koch, Amanda J.
2015-01-01
Little is known about the reliability of college grades relative to how prominently they are used in educational research, and the results to date tend to be based on small sample studies or are decades old. This study uses two large databases (N > 800,000) from over 200 educational institutions spanning 13 years and finds that both first-year…
Reliability Analysis of Money Habitudes
Delgadillo, Lucy M.; Bushman, Brittani S.
2015-01-01
Use of the Money Habitudes exercise has gained popularity among various financial professionals. This article reports on the reliability of this resource. A survey administered to young adults at a western state university was conducted, and each Habitude or "domain" was analyzed using Cronbach's alpha procedures. Results showed all six…
High reliable internet hosting : a case study of handling unanticipated threats to reliability
Wijnhoven, A.B.J.M.; Ehrenhard, M.L.; Alink, T.
2012-01-01
Internet hosting is pivotal for reliable access to internet resources. Yet, little research has been done on what threatens a hosting service’s reliability. Our analysis of reliability threatening incidents results in four causes of unreliability: the service’s technical architecture, service employ
Reliability design method for steam turbine blades
Jinyuan SHI
2008-01-01
Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliabil-ity design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical cal-culation of test data. The fatigue strength and the vibra-tion design reliability of turbine blades are determined with the aid of a probabilistic design method and by inter-ference models for stress distribution and strength distri-bution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades.
Photovoltaic system reliability
Maish, A.B.; Atcitty, C. [Sandia National Labs., NM (United States); Greenberg, D. [Ascension Technology, Inc., Lincoln Center, MA (United States)] [and others
1997-10-01
This paper discusses the reliability of several photovoltaic projects including SMUD`s PV Pioneer project, various projects monitored by Ascension Technology, and the Colorado Parks project. System times-to-failure range from 1 to 16 years, and maintenance costs range from 1 to 16 cents per kilowatt-hour. Factors contributing to the reliability of these systems are discussed, and practices are recommended that can be applied to future projects. This paper also discusses the methodology used to collect and analyze PV system reliability data.
Structural Reliability Methods
Ditlevsen, Ove Dalager; Madsen, H. O.
of structural reliability, including the theoretical basis for these methods. Partial safety factor codes under current practice are briefly introduced and discussed. A probabilistic code format for obtaining a formal reliability evaluation system that catches the most essential features of the nature......The structural reliability methods quantitatively treat the uncertainty of predicting the behaviour and properties of a structure given the uncertain properties of its geometry, materials, and the actions it is supposed to withstand. This book addresses the probabilistic methods for evaluation...
Generating function approach to reliability analysis of structural systems
无
2009-01-01
The generating function approach is an important tool for performance assessment in multi-state systems. Aiming at strength reliability analysis of structural systems, generating function approach is introduced and developed. Static reliability models of statically determinate, indeterminate systems and fatigue reliability models are built by constructing special generating functions, which are used to describe probability distributions of strength (resistance), stress (load) and fatigue life, by defining composite operators of generating functions and performance structure functions thereof. When composition operators are executed, computational costs can be reduced by a big margin by means of collecting like terms. The results of theoretical analysis and numerical simulation show that the generating function approach can be widely used for probability modeling of large complex systems with hierarchical structures due to the unified form, compact expression, computer program realizability and high universality. Because the new method considers twin loads giving rise to component failure dependency, it can provide a theoretical reference and act as a powerful tool for static, dynamic reliability analysis in civil engineering structures and mechanical equipment systems with multi-mode damage coupling.
Cuba: Multidimensional numerical integration library
Hahn, Thomas
2016-08-01
The Cuba library offers four independent routines for multidimensional numerical integration: Vegas, Suave, Divonne, and Cuhre. The four algorithms work by very different methods, and can integrate vector integrands and have very similar Fortran, C/C++, and Mathematica interfaces. Their invocation is very similar, making it easy to cross-check by substituting one method by another. For further safeguarding, the output is supplemented by a chi-square probability which quantifies the reliability of the error estimate.
An integrated reliability-based design optimization of offshore towers
Karadeniz, Halil [Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft (Netherlands)], E-mail: h.karadeniz@tudelft.nl; Togan, Vedat [Department of Civil Engineering, Karadeniz Technical University, Trabzon (Turkey); Vrouwenvelder, Ton [Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft (Netherlands)
2009-10-15
After recognizing the uncertainty in the parameters such as material, loading, geometry and so on in contrast with the conventional optimization, the reliability-based design optimization (RBDO) concept has become more meaningful to perform an economical design implementation, which includes a reliability analysis and an optimization algorithm. RBDO procedures include structural analysis, reliability analysis and sensitivity analysis both for optimization and for reliability. The efficiency of the RBDO system depends on the mentioned numerical algorithms. In this work, an integrated algorithms system is proposed to implement the RBDO of the offshore towers, which are subjected to the extreme wave loading. The numerical strategies interacting with each other to fulfill the RBDO of towers are as follows: (a) a structural analysis program, SAPOS, (b) an optimization program, SQP and (c) a reliability analysis program based on FORM. A demonstration of an example tripod tower under the reliability constraints based on limit states of the critical stress, buckling and the natural frequency is presented.
Analytical and numerical simulations of a hydraulic fracturing experiment
Zhou, M.Z.; Namiq, M.A.; Zhou, L.; Gou, Y. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Petroleum Engineering
2008-10-23
Based on simulations of a previously published hydraulic fracturing experiment performed by Casas et al. (2006), this paper presents the performance assessment of the famous analytical fracture 2D-models (PKN and KGD) and a 3D numerical model (FDM program FLAC3D of the ITASCA Inc.). Strain-softening models are used in the FLAC3D to describe the fracture creation and propagation as well as to present the material softening properties (permeability, tensile strength, cohesion, friction and dilation angel) as functions of the plastic strain. The results show that the numerical simulator has a much better performance and produces more reliable results than the analytical fracture models. However, numerical models have limitations and thus potential for further development. (orig.)
Reliability Estimation of the Pultrusion Process Using the First-Order Reliability Method (FORM)
Baran, Ismet; Tutum, Cem C.; Hattel, Jesper H.
2013-08-01
In the present study the reliability estimation of the pultrusion process of a flat plate is analyzed by using the first order reliability method (FORM). The implementation of the numerical process model is validated by comparing the deterministic temperature and cure degree profiles with corresponding analyses in the literature. The centerline degree of cure at the exit (CDOCE) being less than a critical value and the maximum composite temperature ( T max) during the process being greater than a critical temperature are selected as the limit state functions (LSFs) for the FORM. The cumulative distribution functions of the CDOCE and T max as well as the correlation coefficients are obtained by using the FORM and the results are compared with corresponding Monte-Carlo simulations (MCS). According to the results obtained from the FORM, an increase in the pulling speed yields an increase in the probability of T max being greater than the resin degradation temperature. A similar trend is also seen for the probability of the CDOCE being less than 0.8.
Reliability of power connections
BRAUNOVIC Milenko
2007-01-01
Despite the use of various preventive maintenance measures, there are still a number of problem areas that can adversely affect system reliability. Also, economical constraints have pushed the designs of power connections closer to the limits allowed by the existing standards. The major parameters influencing the reliability and life of Al-Al and Al-Cu connections are identified. The effectiveness of various palliative measures is determined and the misconceptions about their effectiveness are dealt in detail.
Reliability-Based Optimization of Series Systems of Parallel Systems
Enevoldsen, I.; Sørensen, John Dalsgaard
Reliability-based design of structural systems is considered. Especially systems where the reliability model is a series system of parallel systems are analysed. A sensitivity analysis for this class of problems is presented. Direct and sequential optimization procedures to solve the optimization...... problems are described. Numerical tests indicate that a sequential technique called the bounds iteration method (BIM) is particularly fast and stable....
罗善明; 缪协兴
2002-01-01
The matching relationship between coal cutting and caving in fully mechanized top-coal caving face is analyzed in detail from the angle of reliability. The coupling equation of reliability is established correspondingly, and the mathematical equation of the coefficient of velocity matching of coal cutting and caving is obtained, which meets a certain reliability demand for making the working procedure of coal caving not influence coal cutting of coal-cutter. The results show that the relationship between the coefficient of the velocity matching and the reliability of coal cutting and caving system is linear on the whole when R<0.9. It is pointed out that different numerical value should be selected for different coal face according to different demand for reliability.
Reliability Analysis of Slope Stability by Central Point Method
Li, Chunge; WU Congliang
2015-01-01
Given uncertainty and variability of the slope stability analysis parameter, the paper proceed from the perspective of probability theory and statistics based on the reliability theory. Through the central point method of reliability analysis, performance function about the reliability of slope stability analysis is established. What’s more, the central point method and conventional limit equilibrium methods do comparative analysis by calculation example. The approach’s numerical ...
Sensitivity Analysis of Component Reliability
ZhenhuaGe
2004-01-01
In a system, Every component has its unique position within system and its unique failure characteristics. When a component's reliability is changed, its effect on system reliability is not equal. Component reliability sensitivity is a measure of effect on system reliability while a component's reliability is changed. In this paper, the definition and relative matrix of component reliability sensitivity is proposed, and some of their characteristics are analyzed. All these will help us to analyse or improve the system reliability.
Fundamental mechanisms of micromachine reliability
DE BOER,MAARTEN P.; SNIEGOWSKI,JEFFRY J.; KNAPP,JAMES A.; REDMOND,JAMES M.; MICHALSKE,TERRY A.; MAYER,THOMAS K.
2000-01-01
Due to extreme surface to volume ratios, adhesion and friction are critical properties for reliability of Microelectromechanical Systems (MEMS), but are not well understood. In this LDRD the authors established test structures, metrology and numerical modeling to conduct studies on adhesion and friction in MEMS. They then concentrated on measuring the effect of environment on MEMS adhesion. Polycrystalline silicon (polysilicon) is the primary material of interest in MEMS because of its integrated circuit process compatibility, low stress, high strength and conformal deposition nature. A plethora of useful micromachined device concepts have been demonstrated using Sandia National Laboratories' sophisticated in-house capabilities. One drawback to polysilicon is that in air the surface oxidizes, is high energy and is hydrophilic (i.e., it wets easily). This can lead to catastrophic failure because surface forces can cause MEMS parts that are brought into contact to adhere rather than perform their intended function. A fundamental concern is how environmental constituents such as water will affect adhesion energies in MEMS. The authors first demonstrated an accurate method to measure adhesion as reported in Chapter 1. In Chapter 2 through 5, they then studied the effect of water on adhesion depending on the surface condition (hydrophilic or hydrophobic). As described in Chapter 2, they find that adhesion energy of hydrophilic MEMS surfaces is high and increases exponentially with relative humidity (RH). Surface roughness is the controlling mechanism for this relationship. Adhesion can be reduced by several orders of magnitude by silane coupling agents applied via solution processing. They decrease the surface energy and render the surface hydrophobic (i.e. does not wet easily). However, only a molecular monolayer coats the surface. In Chapters 3-5 the authors map out the extent to which the monolayer reduces adhesion versus RH. They find that adhesion is
Numerical Investigation of Boiling
Sagan, Michael; Tanguy, Sebastien; Colin, Catherine
2012-11-01
In this work, boiling is numerically investigated, using two phase flow direct numerical simulation based on a level set / Ghost Fluid method. Nucleate boiling implies both thermal issue and multiphase dynamics issues at different scales and at different stages of bubble growth. As a result, the different phenomena are investigated separately, considering their nature and the scale at which they occur. First, boiling of a static bubble immersed in an overheated liquid is analysed. Numerical simulations have been performed at different Jakob numbers in the case of strong density discontinuity through the interface. The results show a good agreement on bubble radius evolution between the theoretical evolution and numerical simulation. After the validation of the code for the Scriven test case, interaction of a bubble with a wall is studied. A numerical method taking into account contact angle is evaluated by comparing simulations of the spreading of a liquid droplet impacting on a plate, with experimental data. Then the heat transfer near the contact line is investigated, and simulations of nucleate boiling are performed considering different contact angles values. Finally, the relevance of including a model to take into account the evaporation of the micro layer is discussed.
Is quantitative electromyography reliable?
Cecere, F; Ruf, S; Pancherz, H
1996-01-01
The reliability of quantitative electromyography (EMG) of the masticatory muscles was investigated in 14 subjects without any signs or symptoms of temporomandibular disorders. Integrated EMG activity from the anterior temporalis and masseter muscles was recorded bilaterally by means of bipolar surface electrodes during chewing and biting activities. In the first experiment, the influence of electrode relocation was investigated. No influence of electrode relocation on the recorded EMG signal could be detected. In a second experiment, three sessions of EMG recordings during five different chewing and biting activities were performed in the morning (I); 1 hour later without intermediate removal of the electrodes (II); and in the afternoon, using new electrodes (III). The method errors for different time intervals (I-II and I-III errors) for each muscle and each function were calculated. Depending on the time interval between the EMG recordings, the muscles considered, and the function performed, the individual errors ranged from 5% to 63%. The method error increased significantly (P masseter (mean 27.2%) was higher than for the temporalis (mean 20.0%). The largest function error was found during maximal biting in intercuspal position (mean 23.1%). Based on the findings, quantitative electromyography of the masticatory muscles seems to have a limited value in diagnostics and in the evaluation of individual treatment results.
Optimal Reliability-Based Code Calibration
Sørensen, John Dalsgaard; Kroon, I. B.; Faber, M. H.
1994-01-01
Calibration of partial safety factors is considered in general, including classes of structures where no code exists beforehand. The partial safety factors are determined such that the difference between the reliability for the different structures in the class considered and a target reliability...... level is minimized. Code calibration on a decision theoretical basis is also considered and it is shown how target reliability indices can be calibrated. Results from code calibration for rubble mound breakwater designs are shown....
Frontiers in Numerical Relativity
Evans, Charles R.; Finn, Lee S.; Hobill, David W.
2011-06-01
Preface; Participants; Introduction; 1. Supercomputing and numerical relativity: a look at the past, present and future David W. Hobill and Larry L. Smarr; 2. Computational relativity in two and three dimensions Stuart L. Shapiro and Saul A. Teukolsky; 3. Slowly moving maximally charged black holes Robert C. Ferrell and Douglas M. Eardley; 4. Kepler's third law in general relativity Steven Detweiler; 5. Black hole spacetimes: testing numerical relativity David H. Bernstein, David W. Hobill and Larry L. Smarr; 6. Three dimensional initial data of numerical relativity Ken-ichi Oohara and Takashi Nakamura; 7. Initial data for collisions of black holes and other gravitational miscellany James W. York, Jr.; 8. Analytic-numerical matching for gravitational waveform extraction Andrew M. Abrahams; 9. Supernovae, gravitational radiation and the quadrupole formula L. S. Finn; 10. Gravitational radiation from perturbations of stellar core collapse models Edward Seidel and Thomas Moore; 11. General relativistic implicit radiation hydrodynamics in polar sliced space-time Paul J. Schinder; 12. General relativistic radiation hydrodynamics in spherically symmetric spacetimes A. Mezzacappa and R. A. Matzner; 13. Constraint preserving transport for magnetohydrodynamics John F. Hawley and Charles R. Evans; 14. Enforcing the momentum constraints during axisymmetric spacelike simulations Charles R. Evans; 15. Experiences with an adaptive mesh refinement algorithm in numerical relativity Matthew W. Choptuik; 16. The multigrid technique Gregory B. Cook; 17. Finite element methods in numerical relativity P. J. Mann; 18. Pseudo-spectral methods applied to gravitational collapse Silvano Bonazzola and Jean-Alain Marck; 19. Methods in 3D numerical relativity Takashi Nakamura and Ken-ichi Oohara; 20. Nonaxisymmetric rotating gravitational collapse and gravitational radiation Richard F. Stark; 21. Nonaxisymmetric neutron star collisions: initial results using smooth particle hydrodynamics
Mohanty, Sankhya; Hattel, Jesper Henri
2015-01-01
to generate optimized cellular scanning strategies and processing parameters, with an objective of reducing thermal asymmetries and mechanical deformations. The optimized scanning strategies are used for selective laser melting of the standard samples, and experimental and numerical results are compared....... gradients that occur during the process. While process monitoring and control of selective laser melting is an active area of research, establishing the reliability and robustness of the process still remains a challenge.In this paper, a methodology for generating reliable, optimized scanning paths...
Robust reliable H∞ control for discrete-time Markov jump linear systems with actuator failures
Chen Jiaorong; Liu Fei
2008-01-01
The robust reliable H∞ control problem for discrete-time Markovian jump systems with actuator failures is studied.A more practical model of actuator failures than outage is considered.Based on the state feedback method,the resulting closed-loop systems are reliable in that they remain robust stochastically stable and satisfy a certain level of Hex disturbance attenuation not only when all actuators are operational,but also in case of some actuator failures.The solvability condition of controllers can be equivalent to a feasibility problem of coupled linear matrix inequalities (LMIs).A numerical example is also given to illustrate the design procedures and their effectiveness.
Estimation and enhancement of real-time software reliability through mutation analysis
Geist, Robert; Offutt, A. J.; Harris, Frederick C., Jr.
1992-01-01
A simulation-based technique for obtaining numerical estimates of the reliability of N-version, real-time software is presented. An extended stochastic Petri net is employed to represent the synchronization structure of N versions of the software, where dependencies among versions are modeled through correlated sampling of module execution times. Test results utilizing specifications for NASA's planetary lander control software indicate that mutation-based testing could hold greater potential for enhancing reliability than the desirable but perhaps unachievable goal of independence among N versions.
Structural Reliability of Wind Turbine Blades
Dimitrov, Nikolay Krasimirov
by developing new models and standards or carrying out tests The following aspects are covered in detail: ⋅ The probabilistic aspects of ultimate strength of composite laminates are addressed. Laminated plates are considered as a general structural reliability system where each layer in a laminate is a separate...... system component. Methods for solving the system reliability are discussed in an example problem. ⋅ Probabilistic models for fatigue life of laminates and sandwich core are developed and calibrated against measurement data. A modified, nonlinear S-N relationship is formulated where the static strength...... the reliability against several modes of failure in two different structures. This includes reliability against blade-tower collision, and the reliability against ultimate and fatigue failure of a sandwich panel. The results from the reliability analyses are then used for calibrating partial safety factors...
Creating Highly Reliable Accountable Care Organizations.
Vogus, Timothy J; Singer, Sara J
2016-12-01
Accountable Care Organizations' (ACOs) pursuit of the triple aim of higher quality, lower cost, and improved population health has met with mixed results. To improve the design and implementation of ACOs we look to organizations that manage similarly complex, dynamic, and tightly coupled conditions while sustaining exceptional performance known as high-reliability organizations. We describe the key processes through which organizations achieve reliability, the leadership and organizational practices that enable it, and the role that professionals can play when charged with enacting it. Specifically, we present concrete practices and processes from health care organizations pursuing high-reliability and from early ACOs to illustrate how the triple aim may be met by cultivating mindful organizing, practicing reliability-enhancing leadership, and identifying and supporting reliability professionals. We conclude by proposing a set of research questions to advance the study of ACOs and high-reliability research.
Parmeggiani, Stefano; Muliawan, Made Jaya; Gao, Zhen;
2012-01-01
to be carried out numerically, through coupled analyses of alternative solutions. The present study deals with the preliminary hydrodynamic characterization of Wave Dragon needed in order to calibrate the numerical model to be used for the mooring design. A hydrodynamic analysis of the small scale model......, with experimental results derived from tank tests of a small scale model. Due to the complex geometry of the device, a sensitivity analysis is performed to discuss the influence of the mean position on the quality of the numerical predictions. Good correspondence is achieved between the experimental and numerical...... model. The numerical model is hence considered reliable for future design applications....
THE AIRLINE'S RELIABILITY PROGRAM
Тамаргазін, О. А.; Національний авіаційний університет; Власенко, П. О.; Національний авіаційний університет
2013-01-01
Airline's operational structure for Reliability program implementation — engineering division, reliability division, reliability control division, aircraft maintenance division, quality assurance division — was considered. Airline's Reliability program structure is shown. Using of Reliability program for reducing costs on aircraft maintenance is proposed. Рассмотрена организационная структура авиакомпании по выполнению Программы надежности - инженерный отдел, отделы по надежности авиацио...
Photovoltaic module reliability workshop
Mrig, L. (ed.)
1990-01-01
The paper and presentations compiled in this volume form the Proceedings of the fourth in a series of Workshops sponsored by Solar Energy Research Institute (SERI/DOE) under the general theme of photovoltaic module reliability during the period 1986--1990. The reliability Photo Voltaic (PV) modules/systems is exceedingly important along with the initial cost and efficiency of modules if the PV technology has to make a major impact in the power generation market, and for it to compete with the conventional electricity producing technologies. The reliability of photovoltaic modules has progressed significantly in the last few years as evidenced by warranties available on commercial modules of as long as 12 years. However, there is still need for substantial research and testing required to improve module field reliability to levels of 30 years or more. Several small groups of researchers are involved in this research, development, and monitoring activity around the world. In the US, PV manufacturers, DOE laboratories, electric utilities and others are engaged in the photovoltaic reliability research and testing. This group of researchers and others interested in this field were brought together under SERI/DOE sponsorship to exchange the technical knowledge and field experience as related to current information in this important field. The papers presented here reflect this effort.
Numerical modelling of elastic space tethers
Kristiansen, Kristian Uldall; Palmer, P. L.; Roberts, R. M.
2012-01-01
In this paper the importance of the ill-posedness of the classical, non-dissipative massive tether model on an orbiting tether system is studied numerically. The computations document that via the regularisation of bending resistance a more reliable numerical integrator can be produced. Furthermore......, the numerical experiments of an orbiting tether system show that bending may introduce significant forces in some regions of phase space. Finally, numerical evidence for the existence of an almost invariant slow manifold of the singularly perturbed, regularised, non-dissipative massive tether model is provided...
Photovoltaic performance and reliability workshop
Kroposki, B
1996-10-01
This proceedings is the compilation of papers presented at the ninth PV Performance and Reliability Workshop held at the Sheraton Denver West Hotel on September 4--6, 1996. This years workshop included presentations from 25 speakers and had over 100 attendees. All of the presentations that were given are included in this proceedings. Topics of the papers included: defining service lifetime and developing models for PV module lifetime; examining and determining failure and degradation mechanisms in PV modules; combining IEEE/IEC/UL testing procedures; AC module performance and reliability testing; inverter reliability/qualification testing; standardization of utility interconnect requirements for PV systems; need activities to separate variables by testing individual components of PV systems (e.g. cells, modules, batteries, inverters,charge controllers) for individual reliability and then test them in actual system configurations; more results reported from field experience on modules, inverters, batteries, and charge controllers from field deployed PV systems; and system certification and standardized testing for stand-alone and grid-tied systems.
Multi-Disciplinary System Reliability Analysis
Mahadevan, Sankaran; Han, Song
1997-01-01
The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code developed under the leadership of NASA Lewis Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multi-disciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.
Reliability Centered Maintenance - Methodologies
Kammerer, Catherine C.
2009-01-01
Journal article about Reliability Centered Maintenance (RCM) methodologies used by United Space Alliance, LLC (USA) in support of the Space Shuttle Program at Kennedy Space Center. The USA Reliability Centered Maintenance program differs from traditional RCM programs because various methodologies are utilized to take advantage of their respective strengths for each application. Based on operational experience, USA has customized the traditional RCM methodology into a streamlined lean logic path and has implemented the use of statistical tools to drive the process. USA RCM has integrated many of the L6S tools into both RCM methodologies. The tools utilized in the Measure, Analyze, and Improve phases of a Lean Six Sigma project lend themselves to application in the RCM process. All USA RCM methodologies meet the requirements defined in SAE JA 1011, Evaluation Criteria for Reliability-Centered Maintenance (RCM) Processes. The proposed article explores these methodologies.
Numerical and experimental investigations on supersonic ejectors
Bartosiewicz, Y.; Aidoun, Z. [CETC-Varennes, Natural Resources Canada (Canada); Desevaux, P. [CREST-UMR 6000, Belfort (France); Mercadier, Y. [Sherbrooke Univ. (Canada). THERMAUS
2005-02-01
Supersonic ejectors are widely used in a range of applications such as aerospace, propulsion and refrigeration. The primary interest of this study is to set up a reliable hydrodynamics model of a supersonic ejector, which may be extended to refrigeration applications. The first part of this work evaluated the performance of six well-known turbulence models for the study of supersonic ejectors. The validation concentrated on the shock location, shock strength and the average pressure recovery prediction. Axial pressure measurements with a capillary probe performed previously [Int. J. Turbo Jet Engines 19 (2002) 71; Conference Proc., 10th Int. Symp. Flow Visualization, Kyoto, Japan, 2002], were compared with numerical simulations while laser tomography pictures were used to evaluate the non-mixing length. The capillary probe has been included in the numerical model and the non-mixing length has been numerically evaluated by including an additional transport equation for a passive scalar, which acted as an ideal colorant in the flow. At this point, the results show that the k-omega-sst model agrees best with experiments. In the second part, the tested model was used to reproduce the different operation modes of a supersonic ejector, ranging from on-design point to off-design. In this respect, CFD turned out to be an efficient diagnosis tool of ejector analysis (mixing, flow separation), for design, and performance optimization (optimum entrainment and recompression ratios). (Author)
Gearbox Reliability Collaborative Update (Presentation)
Sheng, S.; Keller, J.; Glinsky, C.
2013-10-01
This presentation was given at the Sandia Reliability Workshop in August 2013 and provides information on current statistics, a status update, next steps, and other reliability research and development activities related to the Gearbox Reliability Collaborative.
System Reliability Analysis: Foundations.
1982-07-01
performance formulas for systems subject to pre- ventive maintenance are given. V * ~, , 9 D -2 SYSTEM RELIABILITY ANALYSIS: FOUNDATIONS Richard E...reliability in this case is V P{s can communicate with the terminal t = h(p) Sp2(((((p p)p) p)p)gp) + p(l -p)(((pL p)p)(p 2 JLp)) + p(l -p)((p(p p...For undirected networks, the basic reference is A. Satyanarayana and Kevin Wood (1982). For directed networks, the basic reference is Avinash
Reliability of a Novel Model for Drug Release from 2D HPMC-Matrices
Rumiana Blagoeva
2010-04-01
Full Text Available A novel model of drug release from 2D-HPMC matrices is considered. Detailed mathematical description of matrix swelling and the effect of the initial drug loading are introduced. A numerical approach to solution of the posed nonlinear 2D problem is used on the basis of finite element domain approximation and time difference method. The reliability of the model is investigated in two steps: numerical evaluation of the water uptake parameters; evaluation of drug release parameters under available experimental data. The proposed numerical procedure for fitting the model is validated performing different numerical examples of drug release in two cases (with and without taking into account initial drug loading. The goodness of fit evaluated by the coefficient of determination is presented to be very good with few exceptions. The obtained results show better model fitting when accounting the effect of initial drug loading (especially for larger values.
HDMR methods to assess reliability in slope stability analyses
Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna
2014-05-01
-soil masses) resulting in sliding mechanisms have been investigated in this study. The reliability indices values drawn from the HDRM method have been compared with conventional approaches as neural networks: the efficiency of HDRM is shown in the case studied. References Chowdhury R., Rao B.N. and Prasad A.M. 2009. High-dimensional model representation for structural reliability analysis. Commun. Numer. Meth. Engng, 25: 301-337. Chowdhury R. and Rao B. 2010. Probabilistic Stability Assessment of Slopes Using High Dimensional Model Representation. Computers and Geotechnics, 37: 876-884.
Disjoint sum forms in reliability theory
B. Anrig
2014-01-01
Full Text Available The structure function f of a binary monotone system is assumed to be known and given in a disjunctive normal form, i.e. as the logical union of products of the indicator variables of the states of its subsystems. Based on this representation of f, an improved Abraham algorithm is proposed for generating the disjoint sum form of f. This form is the base for subsequent numerical reliability calculations. The approach is generalized to multivalued systems. Examples are discussed.
Reliability of Arctic offshore installations
Bercha, F.G. [Bercha Group, Calgary, AB (Canada); Gudmestad, O.T. [Stavanger Univ., Stavanger (Norway)]|[Statoil, Stavanger (Norway)]|[Norwegian Univ. of Technology, Stavanger (Norway); Foschi, R. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Civil Engineering; Sliggers, F. [Shell International Exploration and Production, Rijswijk (Netherlands); Nikitina, N. [VNIIG, St. Petersburg (Russian Federation); Nevel, D.
2006-11-15
Life threatening and fatal failures of offshore structures can be attributed to a broad range of causes such as fires and explosions, buoyancy losses, and structural overloads. This paper addressed the different severities of failure types, categorized as catastrophic failure, local failure or serviceability failure. Offshore tragedies were also highlighted, namely the failures of P-36, the Ocean Ranger, the Piper Alpha, and the Alexander Kieland which all resulted in losses of human life. P-36 and the Ocean Ranger both failed ultimately due to a loss of buoyancy. The Piper Alpha was destroyed by a natural gas fire, while the Alexander Kieland failed due to fatigue induced structural failure. The mode of failure was described as being the specific way in which a failure occurs from a given cause. Current reliability measures in the context of offshore installations only consider the limited number of causes such as environmental loads. However, it was emphasized that a realistic value of the catastrophic failure probability should consider all credible causes of failure. This paper presented a general method for evaluating all credible causes of failure of an installation. The approach to calculating integrated reliability involves the use of network methods such as fault trees to combine the probabilities of all factors that can cause a catastrophic failure, as well as those which can cause a local failure with the potential to escalate to a catastrophic failure. This paper also proposed a protocol for setting credible reliability targets such as the consideration of life safety targets and escape, evacuation, and rescue (EER) success probabilities. A set of realistic reliability targets for both catastrophic and local failures for representative safety and consequence categories associated with offshore installations was also presented. The reliability targets were expressed as maximum average annual failure probabilities. The method for converting these annual