WorldWideScience

Sample records for underlying problem structure

  1. Reinforced concrete structures under impact and impulsive loading: recent development, problems and trends

    International Nuclear Information System (INIS)

    Plauk, G.; Herter, J.

    1984-01-01

    Nuclear plant facilities and other reinforced concrete structures have to be regarded as to their safety in design and construction with respect to impact and impulsive loading in order to avoid serious damage to mankind and environment. The paper gives a survey on theoretical and experimental developments currently in progress, in particular regarding airplane crash. Some new results arising out of several research programs relevant to particular problems of impact loading have been reviewed and are presented. Experimental investigation for determination of material properties of plain concrete, reinforcing steel as well as steel-concrete bond under high strain-rates are treated in this paper including theoretical approaches for the respective material laws. An outline of soft missile impact tests performed on structural members, e.g. beams and plates, to determine the load deformation or fracture behaviour is given. Furthermore, numerical models and calculations to analyse structural components and structures under impact loading were discussed. (Author) [pt

  2. Numerical Modeling of Inverse Problems under Uncertainty for Damage Detection in Aircraft Structures

    Science.gov (United States)

    2013-08-01

    the nature of the physics involved, from the point of view of the inverse problem, the direct model is only a “black box ” to obtain numerical...Campos, Brasil . As results directly related to this research, several publications and monographs were published and /or are being prepared, as

  3. Structural Identification Problem

    Directory of Open Access Journals (Sweden)

    Suvorov Aleksei

    2016-01-01

    Full Text Available The identification problem of the existing structures though the Quasi-Newton and its modification, Trust region algorithms is discussed. For the structural problems, which could be represented by means of the mathematical modelling of the finite element code discussed method is extremely useful. The nonlinear minimization problem of the L2 norm for the structures with linear elastic behaviour is solved by using of the Optimization Toolbox of Matlab. The direct and inverse procedures for the composition of the desired function to minimize are illustrated for the spatial 3D truss structure as well as for the problem of plane finite elements. The truss identification problem is solved with 2 and 3 unknown parameters in order to compare the computational efforts and for the graphical purposes. The particular commands of the Matlab codes are present in this paper.

  4. Collaborative problem structuring using MARVEL

    NARCIS (Netherlands)

    Veldhuis, G.A.; Scheepstal, P.G.M. van; Rouwette, E.A.J.A.; Logtens, T.W.A.

    2015-01-01

    When faced with wicked and messy problems, practitioners can rely on a variety of problem structuring methods (PSMs). Although previous efforts have been made to combine such methods with simulation, currently, few exist that integrate a simulation capability within problem structuring. Our

  5. Leximin rules for bankruptcy problems under uncertainty

    Science.gov (United States)

    Hinojosa, M. A.; Mármol, A. M.; Sánchez, F. J.

    2014-01-01

    We model bankruptcy problems under uncertainty under the assumption that there are several possible states of nature, each of which is identified with a different bankruptcy problem. For this multi-dimensional extension of classic bankruptcy problems, we consider situations in which agents exhibit at the same time additive preferences and leximin preferences on their possible results. We propose division rules which combine different rationality principles and guarantee efficiency with respect to leximin preferences.

  6. Problems in structural inorganic chemistry

    CERN Document Server

    Li, Wai-Kee; Mak, Thomas Chung Wai; Mak, Kendrew Kin Wah

    2013-01-01

    This book consists of over 300 problems (and their solutions) in structural inorganic chemistry at the senior undergraduate and beginning graduate level. The topics covered comprise Atomic and Molecular Electronic States, Atomic Orbitals, Hybrid Orbitals, Molecular Symmetry, Molecular Geometry and Bonding, Crystal Field Theory, Molecular Orbital Theory, Vibrational Spectroscopy, and Crystal Structure. The central theme running through these topics is symmetry, molecular or crystalline. The problems collected in this volume originate in examination papers and take-home assignments that have been part of the teaching of the book's two senior authors' at The Chinese University of Hong Kong over the past four decades. The authors' courses include Chemical Bonding, Elementary Quantum Chemistry, Advanced Inorganic Chemistry, X-Ray Crystallography, etc. The problems have been tested by generations of students taking these courses.

  7. Standard problems for structural computer codes

    International Nuclear Information System (INIS)

    Philippacopoulos, A.J.; Miller, C.A.; Costantino, C.J.

    1985-01-01

    BNL is investigating the ranges of validity of the analytical methods used to predict the behavior of nuclear safety related structures under accidental and extreme environmental loadings. During FY 85, the investigations were concentrated on special problems that can significantly influence the outcome of the soil structure interaction evaluation process. Specially, limitations and applicability of the standard interaction methods when dealing with lift-off, layering and water table effects, were investigated. This paper describes the work and the results obtained during FY 85 from the studies on lift-off, layering and water-table effects in soil-structure interaction

  8. Inference problems in structural biology

    DEFF Research Database (Denmark)

    Olsson, Simon

    The structure and dynamics of biological molecules are essential for their function. Consequently, a wealth of experimental techniques have been developed to study these features. However, while experiments yield detailed information about geometrical features of molecules, this information...

  9. Inference problems in structural biology

    DEFF Research Database (Denmark)

    Olsson, Simon

    The structure and dynamics of biological molecules are essential for their function. Consequently, a wealth of experimental techniques have been developed to study these features. However, while experiments yield detailed information about geometrical features of molecules, this information is of...

  10. Problems of structural mechanics in nuclear design

    International Nuclear Information System (INIS)

    Patwardhan, V.M.; Kakodkar, Anil

    1975-01-01

    A very careful and detailed stress analysis of nuclear presure vessels and components is essential for ensuring the safety and integrity of nuclear power plants. The nuclear designer, therefore, relies heavily on structural mechanics for application of the most advanced stress analysis techniques to practical design problems. The paper reviews the inter-relation between structural mechanics and nuclear design and discusses a few of the specific structural mechanics problems faced by the nuclear designers in the Department of Atomic Energy, India. (author)

  11. Generalized production planning problem under interval uncertainty

    Directory of Open Access Journals (Sweden)

    Samir A. Abass

    2010-06-01

    Full Text Available Data in many real life engineering and economical problems suffer from inexactness. Herein we assume that we are given some intervals in which the data can simultaneously and independently perturb. We consider the generalized production planning problem with interval data. The interval data are in both of the objective function and constraints. The existing results concerning the qualitative and quantitative analysis of basic notions in parametric production planning problem. These notions are the set of feasible parameters, the solvability set and the stability set of the first kind.

  12. Structural Damage Assessment under Uncertainty

    Science.gov (United States)

    Lopez Martinez, Israel

    Structural damage assessment has applications in the majority of engineering structures and mechanical systems ranging from aerospace vehicles to manufacturing equipment. The primary goals of any structural damage assessment and health monitoring systems are to ascertain the condition of a structure and to provide an evaluation of changes as a function of time as well as providing an early-warning of an unsafe condition. There are many structural heath monitoring and assessment techniques developed for research using numerical simulations and scaled structural experiments. However, the transition from research to real-world structures has been rather slow. One major reason for this slow-progress is the existence of uncertainty in every step of the damage assessment process. This dissertation research involved the experimental and numerical investigation of uncertainty in vibration-based structural health monitoring and development of robust detection and localization methods. The basic premise of vibration-based structural health monitoring is that changes in structural characteristics, such as stiffness, mass and damping, will affect the global vibration response of the structure. The diagnostic performance of vibration-based monitoring system is affected by uncertainty sources such as measurement errors, environmental disturbances and parametric modeling uncertainties. To address diagnostic errors due to irreducible uncertainty, a pattern recognition framework for damage detection has been developed to be used for continuous monitoring of structures. The robust damage detection approach developed is based on the ensemble of dimensional reduction algorithms for improved damage-sensitive feature extraction. For damage localization, the determination of an experimental structural model was performed based on output-only modal analysis. An experimental model correlation technique is developed in which the discrepancies between the undamaged and damaged modal data are

  13. The overshoot problem and giant structures

    International Nuclear Information System (INIS)

    Itzhaki, Nissan

    2008-01-01

    Models of small-field inflation often suffer from the overshoot problem. A particularly efficient resolution to the problem was proposed recently in the context of string theory. We show that this resolution predicts the existence of giant spherically symmetric overdense regions with radius of at least 110 Mpc. We argue that if such structures will be found they could offer an experimental window into string theory.

  14. On Helmholtz Problem for Plane Periodical Structures

    International Nuclear Information System (INIS)

    Akishin, P.G.; Vinitskij, S.I.

    1994-01-01

    The plane Helmholtz problem of the periodical disc structures with the phase shifts conditions of the solutions along the basis lattice vectors and the Dirichlet conditions on the basic boundaries is considered. The Green function satisfying the quasi periodical conditions on the lattice is constructed. The Helmholtz problem is reduced to the boundary integral equations for the simple layer potentials of this Green function. The methods of the discretization of the arising integral equations are proposed. The procedures of calculation of the matrix elements are discussed. The reality of the spectral parameter of the nonlinear continuous and discretized problems is shown. 8 refs., 2 figs

  15. Structured Sparsity Regularization Approach to the EEG Inverse Problem

    DEFF Research Database (Denmark)

    Montoya-Martinez, Jair; Artes-Rodriguez, Antonio; Hansen, Lars Kai

    2012-01-01

    Localization of brain activity involves solving the EEG inverse problem, which is an undetermined ill-posed problem. We propose a novel approach consisting in estimating, using structured sparsity regularization techniques, the Brain Electrical Sources (BES) matrix directly in the spatio......-temporal source space. We use proximal splitting optimization methods, which are efficient optimization techniques, with good convergence rates and with the ability to handle large nonsmooth convex problems, which is the typical scenario in the EEG inverse problem. We have evaluated our approach under a simulated...

  16. Underlying substance abuse problems in drunk drivers.

    Science.gov (United States)

    Snenghi, Rossella; Forza, Giovanni; Favretto, Donata; Sartore, Daniela; Rodinis, Silvia; Terranova, Claudio; Nalesso, Alessandro; Montisci, Massimo; Ferrara, Santo Davide

    2015-01-01

    The aim of this study was to investigate polydrug use in drunk drivers. The experimental study was conducted on 2,072 drunk drivers undergoing a driving license reissue protocol at the Department of Legal Medicine of Padova University Hospital in the period between January 2011 and December 2012. The study protocol involved anamnesis, clinical examination, toxicological history, and toxicological analyses on multiple biological samples. One thousand eight hundred seventy-seven subjects (90.6%) were assessed as fit to drive, and 195 (9.5%) were declared unfit. Among those unfit, 32 subjects (1.6%) were declared unfit due to recent use of an illicit drug (time span drive after completeness of the protocol was established in 1.2% of cases for alcohol disorders and in 5.7% of cases for illicit drug abuse; only one subject was included in both subgroups. Cocaine was the most widely used substance, followed by cannabis, opiates, and psychotropic pharmaceutical drugs. The application of the protocol presented in this study allowed the identification of underlying polydrug use in drunk drivers. The study led to the identification of 6.8% unfit subjects on the basis of alcohol disorders and/or drug abuse, compared to 1.2% of identifiable unfitness if the protocol were limited to the mere assessment of alcohol consumption. The frequent association of alcohol and cocaine is different from other patterns of use in North Europe countries.

  17. Adiabatic quantum search algorithm for structured problems

    International Nuclear Information System (INIS)

    Roland, Jeremie; Cerf, Nicolas J.

    2003-01-01

    The study of quantum computation has been motivated by the hope of finding efficient quantum algorithms for solving classically hard problems. In this context, quantum algorithms by local adiabatic evolution have been shown to solve an unstructured search problem with a quadratic speedup over a classical search, just as Grover's algorithm. In this paper, we study how the structure of the search problem may be exploited to further improve the efficiency of these quantum adiabatic algorithms. We show that by nesting a partial search over a reduced set of variables into a global search, it is possible to devise quantum adiabatic algorithms with a complexity that, although still exponential, grows with a reduced order in the problem size

  18. Bounds in the generalized Weber problem under locational uncertainty

    DEFF Research Database (Denmark)

    Juel, Henrik

    1981-01-01

    An existing analysis of the bounds on the Weber problem solution under uncertainty is incorrect. For the generalized problem with arbitrary measures of distance, we give easily computable ranges on the bounds and state the conditions under which the exact values of the bounds can be found...... with little computational effort. Numerical examples illustrate the analysis....

  19. Students’ Creativity: Problem Posing in Structured Situation

    Science.gov (United States)

    Amalina, I. K.; Amirudin, M.; Budiarto, M. T.

    2018-01-01

    This is a qualitative research concerning on students’ creativity on problem posing task. The study aimed at describing the students’ creative thinking ability to pose the mathematics problem in structured situations with varied condition of given problems. In order to find out the students’ creative thinking ability, an analysis of mathematics problem posing test based on fluency, novelty, and flexibility and interview was applied for categorizing students’ responses on that task. The data analysis used the quality of problem posing and categorized in 4 level of creativity. The results revealed from 29 secondary students grade 8, a student in CTL (Creative Thinking Level) 1 met the fluency. A student in CTL 2 met the novelty, while a student in CTL 3 met both fluency and novelty and no one in CTL 4. These results are affected by students’ mathematical experience. The findings of this study highlight that student’s problem posing creativity are dependent on their experience in mathematics learning and from the point of view of which students start to pose problem.

  20. Structure problems in the analog computation

    International Nuclear Information System (INIS)

    Braffort, P.L.

    1957-01-01

    The recent mathematical development showed the importance of elementary structures (algebraic, topological, etc.) in abeyance under the great domains of classical analysis. Such structures in analog computation are put in evidence and possible development of applied mathematics are discussed. It also studied the topological structures of the standard representation of analog schemes such as additional triangles, integrators, phase inverters and functions generators. The analog method gives only the function of the variable: time, as results of its computations. But the course of computation, for systems including reactive circuits, introduces order structures which are called 'chronological'. Finally, it showed that the approximation methods of ordinary numerical and digital computation present the same structure as these analog computation. The structure analysis permits fruitful comparisons between the several domains of applied mathematics and suggests new important domains of application for analog method. (M.P.)

  1. Fiscal Policy Problems Under Conditions Of Financial Liberalization

    Directory of Open Access Journals (Sweden)

    Valentina Urazayeva

    2014-01-01

    Full Text Available The article under the title deals with the difficulties in pursuing national fiscal policy in conditions of international financial liberalization. The author analyzes the nature of liberalization of international capital flows and its positive and negative consequences for the economies of the countries which participate in global capital movement. The author especially highlights the fact that international financial liberalization often leads to economic crises and what is even more important to their rapid spread between countries due to their growing financial interdependence. The author distinguishes two groups of fiscal policy problems in conditions of international financial liberalization. The first group includes problems arising due to quick spread of the crises due to eliminating restrictions on crossborder capital flows. These are reduction in taxes and at the same time increase in budget spending, which often happens unexpectedly and substantially impedes fiscal policy. To illustrate these points the author refers to the statistics on Spain, the USA and the OECD as a whole. Moreover countries face another range of problems regardless of the business cycle phase. In the short term it is the necessity of large scale structural economic reforms to achieve the required level of financial liberalization, which often is a heavy burden on the state budget. In the long term the attention is paid to the problem of tax competition between countries, which affects the instruments of fiscal policy. The author notes that the negative consequences of global financial liberalization are relevant not only for recipient countries but for donor countries as well and emphasizes such a burning issue as "capital flight".

  2. FISCAL POLICY PROBLEMS UNDER CONDITIONS OF FINANCIAL LIBERALIZATION

    Directory of Open Access Journals (Sweden)

    Valentina Urazayeva

    2014-01-01

    Full Text Available The article under the title deals with the difficulties in pursuing national fiscal policy in conditions of international financial liberalization. The author analyzes the nature of liberalization of international capital flows and its positive and negative consequences for the economies of the countries which participate in global capital movement. The author especially highlights the fact that international financial liberalization often leads to economic crises and what is even more important to their rapid spread between countries due to their growing financial interdependence. The author distinguishes two groups of fiscal policy problems in conditions of international financial liberalization. The first group includes problems arising due to quick spread of the crises due to eliminating restrictions on crossborder capital flows. These are reduction in taxes and at the same time increase in budget spending, which often happens unexpectedly and substantially impedes fiscal policy. To illustrate these points the author refers to the statistics on Spain, the USA and the OECD as a whole. Moreover countries face another range of problems regardless of the business cycle phase. In the short term it is the necessity of large scale structural economic reforms to achieve the required level of financial liberalization, which often is a heavy burden on the state budget. In the long term the attention is paid to the problem of tax competition between countries, which affects the instruments of fiscal policy. The author notes that the negative consequences of global financial liberalization are relevant not only for recipient countries but for donor countries as well and emphasizes such a burning issue as "capital flight".

  3. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  4. Self-affirmation improves problem-solving under stress.

    Science.gov (United States)

    Creswell, J David; Dutcher, Janine M; Klein, William M P; Harris, Peter R; Levine, John M

    2013-01-01

    High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.

  5. Concrete structures under impact and impulsive loading

    International Nuclear Information System (INIS)

    Plauk, G.

    1982-05-01

    This book contains papers contributed to the RILEM/CEB/IABSE/IASS-Interassociation Symposium on 'Concrete Structures under Impact and Impulsive Loading'. The essential aim of this symposium is to provide an international forum for the exchange of information on existing and current research relating to impact problems as well as to identify areas to which further research activities should be directed. The subject of the symposium is far ranging. Fifty five papers were proposed and arranged in six technical sessions, a task which sometimes posed difficulties for the Organization Committee and the Advisory Group, because some of the papers touched several topics and were difficult to integrate. However, we are confident that these minor difficulties were solved to the satisfaction of everyone involved. Each session of the symposium is devoted to a major subject area and introduced by a distinguished Introductory Reporter. The large international attendance, some 21 countries are represented, and the large number of excellent papers will certainly produce a lively discussion after each session and thus help to further close the gaps in our knowledge about the behaviour of structures and materials under impact and impulsive loading. (orig./RW)

  6. More on the fragility of performance: choking under pressure in mathematical problem solving.

    Science.gov (United States)

    Beilock, Sian L; Kulp, Catherine A; Holt, Lauren E; Carr, Thomas H

    2004-12-01

    In 3 experiments, the authors examined mathematical problem solving performance under pressure. In Experiment 1, pressure harmed performance on only unpracticed problems with heavy working memory demands. In Experiment 2, such high-demand problems were practiced until their answers were directly retrieved from memory. This eliminated choking under pressure. Experiment 3 dissociated practice on particular problems from practice on the solution algorithm by imposing a high-pressure test on problems practiced 1, 2, or 50 times each. Infrequently practiced high-demand problems were still performed poorly under pressure, whereas problems practiced 50 times each were not. These findings support distraction theories of choking in math, which contrasts with considerable evidence for explicit monitoring theories of choking in sensorimotor skills. This contrast suggests a skill taxonomy based on real-time control structures. (c) 2004 APA

  7. Solving graph problems with dynamic computation structures

    Science.gov (United States)

    Babb, Jonathan W.; Frank, Matthew; Agarwal, Anant

    1996-10-01

    We introduce dynamic computation structures (DCS), a compilation technique to produce dynamic code for reconfigurable computing. DCS specializes directed graph instances into user-level hardware for reconfigurable architectures. Several problems such as shortest path and transitive closure exhibit the general properties of closed semirings, an algebraic structure for solving directed paths. Motivating our application domain choice of closed semiring problems is the fact that logic emulation software already maps a special case of directed graphs, namely logic netlists, onto arrays of field programmable gate arrays (FPGA). A certain type of logic emulation software called virtual wires further allows an FPGA array to be viewed as a machine-independent computing fabric. Thus, a virtual wires compiler, coupled with front-end commercial behavioral logic synthesis software, enables automatic behavioral compilation into a multi-FPGA computing fabric. We have implemented a DCS front-end compiler to parallelize the entire inner loop of the classic Bellman-Ford algorithm into synthesizable behavioral verilog. Leveraging virtual wire compilation and behavioral synthesis, we have automatically generated designs of 14 to 261 FPGAs from a single graph instance. We achieve speedups proportional to the number of graph edges - - from 10X to almost 400X versus a 125 SPECint SparcStation 10.

  8. Problems of Collisions Between Adjacent Steel Structures under Earthquake Excitation / Problemy Zderzeń Pomiędzy Sąsiadującymi Konstrukcjami Stalowymi Poddanymi Obciążeniom Sejsmicznym

    Directory of Open Access Journals (Sweden)

    Sołtysik Barbara

    2016-03-01

    Full Text Available Nowadays, the high level of urbanization forces the engineers to design closelyseparated structures and to take into account many factors influencing their response, including collisions between them due to insufficient separation distance during moderate to strong ground motions. Recent observations as well as experimental and numerical investigations have confirmed that interactions between structures may lead to significant damage of structural elements and even to its total collapse. The aim of this paper is to investigate the influence of collisions between three insufficiently separated models of steel structures on structural response under earthquake excitation. The experimental tests as well as numerical analyses have been conducted in the study.

  9. Self-affirmation improves problem-solving under stress.

    Directory of Open Access Journals (Sweden)

    J David Creswell

    Full Text Available High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.

  10. Sleep Problems Under-Reported by Parents in Iranian Children.

    Science.gov (United States)

    Afsharpaiman, Shahla; Bagheri Hagh, Ali; Kolbadi Nejad, Mohammad; Amirsalari, Susan; Torkaman, Mohammad

    2015-01-01

    Sleep problems are common in childhood, but there are limited studies regarding that in Iranian children and awareness of the sleep problems and their complication in Iranian parents. We arranged this study in which parents of children attending for a sick visit or routine growth control to assess whether sleep problems are under-reported at general pediatric visits. In a cross-sectional study from April 2010 to April 2011 in 301 children aged 2-14 years old attending to pediatric clinics were enrolled. To investigate the general orientation of parents about their child sleep problem we asked them a global question at first regarding sleep of their child. After that, the Persian version of BEARS questionnaire was completed by them. Only 30 (9.9%) parents reported sleep problems in their children in response to primary global question but by collecting the data from BEARS questionnaire it was revealed 45.18% (136/301) of children had one or more of sleep disorders at all. As mentioned 136 (45.18%) children had slept problems of which the most frequent complaint (15.28%) was related to bedtime problems. The second complaint (11.96%) was awakening during the night children. A significant association between sleep problems and child gender was not found. Co-sleeping with parents was found in 55.48% of all children in this study. Despite the high prevalence and adverse effects of sleep disorders, the present study suggests that parents underreport sleep problems at consultation. We suggest children should be assessed for sleep disorders in monitoring and health screening visits.

  11. Distributionally Robust Joint Chance Constrained Problem under Moment Uncertainty

    Directory of Open Access Journals (Sweden)

    Ke-wei Ding

    2014-01-01

    Full Text Available We discuss and develop the convex approximation for robust joint chance constraints under uncertainty of first- and second-order moments. Robust chance constraints are approximated by Worst-Case CVaR constraints which can be reformulated by a semidefinite programming. Then the chance constrained problem can be presented as semidefinite programming. We also find that the approximation for robust joint chance constraints has an equivalent individual quadratic approximation form.

  12. Decision making under ambiguity but not under risk is related to problem gambling severity

    NARCIS (Netherlands)

    Brevers, Damien; Cleeremans, Axel; Goudriaan, Anna E.; Bechara, Antoine; Kornreich, Charles; Verbanck, Paul; Noël, Xavier

    2012-01-01

    The aim of the present study was to examine the relationship between problem gambling severity and decision-making situations that vary in two degrees of uncertainty (probability of outcome is known: decision-making under risk; probability of outcome is unknown: decision-making under ambiguity). For

  13. Deep learning and the electronic structure problem

    Science.gov (United States)

    Mills, Kyle; Spanner, Michael; Tamblyn, Isaac

    In the past decade, the fields of artificial intelligence and computer vision have progressed remarkably. Supported by the enthusiasm of large tech companies, as well as significant hardware advances and the utilization of graphical processing units to accelerate computations, deep neural networks (DNN) are gaining momentum as a robust choice for many diverse machine learning applications. We have demonstrated the ability of a DNN to solve a quantum mechanical eigenvalue equation directly, without the need to compute a wavefunction, and without knowledge of the underlying physics. We have trained a convolutional neural network to predict the total energy of an electron in a confining, 2-dimensional electrostatic potential. We numerically solved the one-electron Schrödinger equation for millions of electrostatic potentials, and used this as training data for our neural network. Four classes of potentials were assessed: the canonical cases of the harmonic oscillator and infinite well, and two types of randomly generated potentials for which no analytic solution is known. We compare the performance of the neural network and consider how these results could lead to future advances in electronic structure theory.

  14. Stochastic reduced order models for inverse problems under uncertainty.

    Science.gov (United States)

    Warner, James E; Aquino, Wilkins; Grigoriu, Mircea D

    2015-03-01

    This work presents a novel methodology for solving inverse problems under uncertainty using stochastic reduced order models (SROMs). Given statistical information about an observed state variable in a system, unknown parameters are estimated probabilistically through the solution of a model-constrained, stochastic optimization problem. The point of departure and crux of the proposed framework is the representation of a random quantity using a SROM - a low dimensional, discrete approximation to a continuous random element that permits e cient and non-intrusive stochastic computations. Characterizing the uncertainties with SROMs transforms the stochastic optimization problem into a deterministic one. The non-intrusive nature of SROMs facilitates e cient gradient computations for random vector unknowns and relies entirely on calls to existing deterministic solvers. Furthermore, the method is naturally extended to handle multiple sources of uncertainty in cases where state variable data, system parameters, and boundary conditions are all considered random. The new and widely-applicable SROM framework is formulated for a general stochastic optimization problem in terms of an abstract objective function and constraining model. For demonstration purposes, however, we study its performance in the specific case of inverse identification of random material parameters in elastodynamics. We demonstrate the ability to efficiently recover random shear moduli given material displacement statistics as input data. We also show that the approach remains effective for the case where the loading in the problem is random as well.

  15. Colloidal Aggregate Structure under Shear by USANS

    Science.gov (United States)

    Chatterjee, Tirtha; van Dyk, Antony K.; Ginzburg, Valeriy V.; Nakatani, Alan I.

    2015-03-01

    Paints are complex formulations of polymeric binders, inorganic pigments, dispersants, surfactants, colorants, rheology modifiers, and other additives. A commercially successful paint exhibits a desired viscosity profile over a wide shear rate range from 10-5 s-1 for settling to >104 s-1 for rolling, and spray applications. Understanding paint formulation structure is critical as it governs the paint viscosity profile. However, probing paint formulation structure under shear is a challenging task due to the formulation complexity containing structures with different hierarchical length scales and their alterations under the influence of an external flow field. In this work mesoscale structures of paint formulations under shear are investigated using Ultra Small-Angle Neutron Scattering (rheo-USANS). Contrast match conditions were utilized to independently probe the structure of latex binder particle aggregates and the TiO2 pigment particle aggregates. Rheo-USANS data revealed that the aggregates are fractal in nature and their self-similarity dimensions and correlations lengths depend on the chemistry of the binder particles, the type of rheology modifier present and the shear stress imposed upon the formulation. These results can be explained in the framework of diffusion and reaction limited transient aggregates structure evolution under simple shear.

  16. Flow-shop scheduling problem under uncertainties: Review and trends

    Directory of Open Access Journals (Sweden)

    Eliana María González-Neira

    2017-03-01

    Full Text Available Among the different tasks in production logistics, job scheduling is one of the most important at the operational decision-making level to enable organizations to achieve competiveness. Scheduling consists in the allocation of limited resources to activities over time in order to achieve one or more optimization objectives. Flow-shop (FS scheduling problems encompass the sequencing processes in environments in which the activities or operations are performed in a serial flow. This type of configuration includes assembly lines and the chemical, electronic, food, and metallurgical industries, among others. Scheduling has been mostly investigated for the deterministic cases, in which all parameters are known in advance and do not vary over time. Nevertheless, in real-world situations, events are frequently subject to uncertainties that can affect the decision-making process. Thus, it is important to study scheduling and sequencing activities under uncertainties since they can cause infeasibilities and disturbances. The purpose of this paper is to provide a general overview of the FS scheduling problem under uncertainties and its role in production logistics and to draw up opportunities for further research. To this end, 100 papers about FS and flexible flow-shop scheduling problems published from 2001 to October 2016 were analyzed and classified. Trends in the reviewed literature are presented and finally some research opportunities in the field are proposed.

  17. Problems in the Study of the Concepts of Underlying Categories

    Directory of Open Access Journals (Sweden)

    Guzel R. Faizova

    2017-10-01

    Full Text Available This paper considers the concepts of underlying categories. The economic good is one of such categories. In this regard, we considered such characteristics of an economic good as utility, value, and cost. The public goods, which are the goods that can benefit society and have two distinctive features, are an important category as well. In this regard, we characterized the characteristics and features of public goods and identified the main problems in this category. At present, the actual problem faced by the state is the production and evaluation of the effectiveness of public goods. The difficulty is that it is impossible to accurately determine the production volume of goods necessary for the society. Assessment of the effectiveness of the state activities requires the development of special tools. The existing legislatively defined methods have a number of shortcomings and do not allow obtaining an objective picture. Financing of most public goods occurs at the expense of the state, so it is very important to ensure and increase the efficiency of their spending at the moment. Public-private partnership is the most promising tool for better satisfying the needs of the population. The main goal of this work is to identify and discuss the main characteristics of the concepts of underlying categories and explain possible problems, issues faced by the state and the society.

  18. Portfolio optimization with structured products under return constraint

    Directory of Open Access Journals (Sweden)

    Baweja Meena

    2015-01-01

    Full Text Available A new approach for optimizing risk in a portfolio of financial instruments involving structured products is presented. This paper deals with a portfolio selection model which uses optimization methodology to minimize conditional Value-at-Risk (CVaR under return constraint. It focuses on minimizing CVaR rather than on minimizing value-at-Risk VaR, as portfolios with low CVaR necessarily have low VaR as well. We consider a simple investment problem where besides stocks and bonds, the investor can also include structured products into the investment portfolio. Due to possible intermediate payments from structured product, we have to deal with a re-investment problem modeled as a linear optimization problem.

  19. Mathematics Teaching as Problem Solving: A Framework for Studying Teacher Metacognition Underlying Instructional Practice in Mathematics.

    Science.gov (United States)

    Artzt, Alice F.; Armour-Thomas, Eleanor

    1998-01-01

    Uses a "teaching as problem solving" perspective to examine the components of metacognition underlying the instructional practice of seven experienced and seven beginning secondary-school mathematics teachers. Data analysis of observations, lesson plans, videotapes, and audiotapes of structured interviews suggests that the metacognition of…

  20. Water Demand Under Alternative Price Structures

    OpenAIRE

    Sheila Olmstead; W. Michael Hanemann; Robert N. Stavins

    2007-01-01

    We estimate the price elasticity of water demand with household-level data, structurally modeling the piecewise-linear budget constraints imposed by increasing-block pricing. We develop a mathematical expression for the unconditional price elasticity of demand under increasing-block prices and compare conditional and unconditional elasticities analytically and empirically. We test the hypothesis that price elasticity may depend on price structure, beyond technical differences in elasticity co...

  1. Efficient Bayesian inference under the structured coalescent.

    Science.gov (United States)

    Vaughan, Timothy G; Kühnert, Denise; Popinga, Alex; Welch, David; Drummond, Alexei J

    2014-08-15

    Population structure significantly affects evolutionary dynamics. Such structure may be due to spatial segregation, but may also reflect any other gene-flow-limiting aspect of a model. In combination with the structured coalescent, this fact can be used to inform phylogenetic tree reconstruction, as well as to infer parameters such as migration rates and subpopulation sizes from annotated sequence data. However, conducting Bayesian inference under the structured coalescent is impeded by the difficulty of constructing Markov Chain Monte Carlo (MCMC) sampling algorithms (samplers) capable of efficiently exploring the state space. In this article, we present a new MCMC sampler capable of sampling from posterior distributions over structured trees: timed phylogenetic trees in which lineages are associated with the distinct subpopulation in which they lie. The sampler includes a set of MCMC proposal functions that offer significant mixing improvements over a previously published method. Furthermore, its implementation as a BEAST 2 package ensures maximum flexibility with respect to model and prior specification. We demonstrate the usefulness of this new sampler by using it to infer migration rates and effective population sizes of H3N2 influenza between New Zealand, New York and Hong Kong from publicly available hemagglutinin (HA) gene sequences under the structured coalescent. The sampler has been implemented as a publicly available BEAST 2 package that is distributed under version 3 of the GNU General Public License at http://compevol.github.io/MultiTypeTree. © The Author 2014. Published by Oxford University Press.

  2. Ab initio nuclear structure - the large sparse matrix eigenvalue problem

    International Nuclear Information System (INIS)

    Vary, James P; Maris, Pieter; Ng, Esmond; Yang, Chao; Sosonkina, Masha

    2009-01-01

    The structure and reactions of light nuclei represent fundamental and formidable challenges for microscopic theory based on realistic strong interaction potentials. Several ab initio methods have now emerged that provide nearly exact solutions for some nuclear properties. The ab initio no core shell model (NCSM) and the no core full configuration (NCFC) method, frame this quantum many-particle problem as a large sparse matrix eigenvalue problem where one evaluates the Hamiltonian matrix in a basis space consisting of many-fermion Slater determinants and then solves for a set of the lowest eigenvalues and their associated eigenvectors. The resulting eigenvectors are employed to evaluate a set of experimental quantities to test the underlying potential. For fundamental problems of interest, the matrix dimension often exceeds 10 10 and the number of nonzero matrix elements may saturate available storage on present-day leadership class facilities. We survey recent results and advances in solving this large sparse matrix eigenvalue problem. We also outline the challenges that lie ahead for achieving further breakthroughs in fundamental nuclear theory using these ab initio approaches.

  3. Particle Swarm Optimization for Structural Design Problems

    Directory of Open Access Journals (Sweden)

    Hamit SARUHAN

    2010-02-01

    Full Text Available The aim of this paper is to employ the Particle Swarm Optimization (PSO technique to a mechanical engineering design problem which is minimizing the volume of a cantilevered beam subject to bending strength constraints. Mechanical engineering design problems are complex activities which are computing capability are more and more required. The most of these problems are solved by conventional mathematical programming techniques that require gradient information. These techniques have several drawbacks from which the main one is becoming trapped in local optima. As an alternative to gradient-based techniques, the PSO does not require the evaluation of gradients of the objective function. The PSO algorithm employs the generation of guided random positions when they search for the global optimum point. The PSO which is a nature inspired heuristics search technique imitates the social behavior of bird flocking. The results obtained by the PSO are compared with Mathematical Programming (MP. It is demonstrated that the PSO performed and obtained better convergence reliability on the global optimum point than the MP. Using the MP, the volume of 2961000 mm3 was obtained while the beam volume of 2945345 mm3 was obtained by the PSO.

  4. Numerical Analysis of Vibrations of Structures under Moving Inertial Load

    CERN Document Server

    Bajer, Czeslaw I

    2012-01-01

    Moving inertial loads are applied to structures in civil engineering, robotics, and mechanical engineering. Some fundamental books exist, as well as thousands of research papers. Well known is the book by L. Frýba, Vibrations of Solids and Structures Under Moving Loads, which describes almost all problems concerning non-inertial loads. This book presents broad description of numerical tools successfully applied to structural dynamic analysis. Physically we deal with non-conservative systems. The discrete approach formulated with the use of the classical finite element method results in elemental matrices, which can be directly added to global structure matrices. A more general approach is carried out with the space-time finite element method. In such a case, a trajectory of the moving concentrated parameter in space and time can be simply defined. We consider structures described by pure hyperbolic differential equations such as strings and structures described by hyperbolic-parabolic differential equations ...

  5. Structuring and assessing large and complex decision problems using MCDA

    DEFF Research Database (Denmark)

    Barfod, Michael Bruhn

    This paper presents an approach for the structuring and assessing of large and complex decision problems using multi-criteria decision analysis (MCDA). The MCDA problem is structured in a decision tree and assessed using the REMBRANDT technique featuring a procedure for limiting the number of pair...

  6. Modeling the Structure and Complexity of Engineering Routine Design Problems

    NARCIS (Netherlands)

    Jauregui Becker, Juan Manuel; Wits, Wessel Willems; van Houten, Frederikus J.A.M.

    2011-01-01

    This paper proposes a model to structure routine design problems as well as a model of its design complexity. The idea is that having a proper model of the structure of such problems enables understanding its complexity, and likewise, a proper understanding of its complexity enables the development

  7. Structured collaboration versus individual learning in solving physics problems

    NARCIS (Netherlands)

    Harskamp, Egbert; Ding, Ning

    2006-01-01

    The research issue in this study is how to structure collaborative learning so that it improves solving physics problems more than individual learning. Structured collaborative learning has been compared with individual learning environments with Schoenfeld's problem-solving episodes. Students took

  8. Writing problems in developmental dyslexia: under-recognized and under-treated.

    Science.gov (United States)

    Berninger, Virginia W; Nielsen, Kathleen H; Abbott, Robert D; Wijsman, Ellen; Raskind, Wendy

    2008-02-01

    The International Dyslexia Association defines dyslexia as unexpected problems of neurobiological origin in accuracy and rate of oral reading of single real words, single pseudowords, or text or of written spelling. However, prior research has focused more on the reading than the spelling problems of students with dyslexia. A test battery was administered to 122 children who met inclusion criteria for dyslexia and qualified their families for participation in a family genetics study that has been ongoing for over a decade. Their parents completed the same test battery. Although a past structural equation modeling study of typically developing children identified a significant path from handwriting to composition quality, the current structural equation modeling study identified a significant path from spelling to composition for children and their parents with dyslexia. Grapho-motor planning did not contribute uniquely to their composition, showing that writing is not just a motor skill. Students with dyslexia do have a problem in automatic letter writing and naming, which was related to impaired inhibition and verbal fluency, and may explain their spelling problems. Results are discussed in reference to the importance of providing explicit instruction in the phonological, orthographic, and morphological processes of spelling and in composition to students with dyslexia and not only offering accommodation for their writing problems.

  9. The consistency problems of large scale structure

    International Nuclear Information System (INIS)

    Schramm, D.N.

    1986-01-01

    Studies of the early universe are reviewed, with emphasis on galaxy formation, dark matter and the generation of large scale structure. The paper was presented at the conference on ''The early universe and its evolution'', Erice, Italy, 1986. Dark matter, Big Bang nucleosynthesis, baryonic halos, flatness arguments, cosmological constant, galaxy formation, neutrinos plus strings or explosions and string models, are all discussed. (U.K.)

  10. The multilevel structure of four adolescent problems.

    Science.gov (United States)

    Smolkowski, Keith; Biglan, Anthony; Dent, Clyde; Seeley, John

    2006-09-01

    This paper examines variability in adolescent self-reported behavior at the individual, cohort, and school levels for 8th and 11th graders. We examine four adolescent behaviors: substance use, antisocial behavior, depression, and academic performance. Research staff collected the data as part of the Oregon Healthy Teens survey of a population-based sample of 60,837 adolescents over three years in 92 communities. The results indicate that schools vary over time, but not necessarily systematically, and grade-level cohorts account for important variance within schools. The school and cohort combined, however, accounted for at most 4% of the overall variance. The results have implications for research and practice in schools and communities. For example, selection of communities for interventions based on high levels of adolescent problems may be unproductive if individuals account for at least 96% of the variance. Furthermore, in non-experimental designs, cohort variability, not an intervention, may account for apparent improvement across

  11. Decision criteria under uncertainty and the climate problem

    Energy Technology Data Exchange (ETDEWEB)

    Bretteville, Camilla

    1999-11-01

    This working paper examines some of the decision criteria suggested by theories on decision making under uncertainty. This is done by applying the criteria to the problem of global warming. It is shown that even if there was a benevolent planner who is both supranational and supra generational and even if he had a well defined inter generational welfare function, there are still remaining problems. The question asked is: If there were a benevolent planner, would he know the best climate policy for the world today. The main discussion abstracts from all other complications and focuses on the lack of certainty regarding impacts of greenhouse gas emissions and the effectiveness of policy. A very simplified example of a game against nature is constructed. It has two possible policy choices. One can either try to prevent global warming, or one can choose to do nothing. The future state of the world is uncertain and the chosen policy might affect the outcome in each state. The framing of the example is such that one should expect a policy of action to be preferred rather than a no-action policy, however this is not always the case. It is shown that the preferred policy choice is very much dependent on the choice of decision criterion, the magnitude of costs and of the framing. 3 tabs., 23 refs

  12. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  13. Fatigue in Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    1999-01-01

    test results. Both the fracture mechanics analysis and the fatigue test results indicate that Miner's rule, which is normally used in the design against fatigue in steel structures, may give results, which are unconservative, and that the validity of the results obtained from Miner's rule will depend......Fatigue damage accumulation in steel structures under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series have been carried through on various...... types of welded plate test specimens and full-scale offshore tubular joints. The materials that have been used are either conventional structural steel with a yield stress of ~ 360-410 MPa or high-strength steel with a yield stress of ~ 810-1010 MPa. The fatigue tests and the fracture mechanics analyses...

  14. STABILITY OF UNDERWATER STRUCTURE UNDER WAVE ATTACK

    Directory of Open Access Journals (Sweden)

    C. Paotonan

    2012-02-01

    Full Text Available Geotube is, among others, a type of coastal structure that is increasingly accepted for coastal protection especially underwater breakwater. Besides its relatively low cost, it has other advantages such as flexibility, ease of construction and the fact that it can be filled with local sand material. Similar to all other coastal structures, it should also be stable under wave attack. A simple theoretical approach based on linear wave was adopted to estimate the stability of such structure. The theoretical solution was then compared with an experimental study. The experimental study was conducted at the Hydraulics and Hydrology Laboratory of Universitas Gadjah Mada. However, instead of a real geotube, PVC pipe was used where the weight of the PVC was varied by adjusting the volume of sand in the pipe. The result indicated that the agreement between the theoretical solution and the experiment was encouraging. The analytical solution may be utilized to predict underwater pipe stability under wave attack with certain degree of accuracy.

  15. Strength of concrete structures under dynamic loading

    Science.gov (United States)

    Kumpyak, O. G.; Galyautdinov, Z. R.; Kokorin, D. N.

    2016-01-01

    The use of elastic supports is one the efficient methods of decreasing the dynamic loading. The paper describes the influence of elastic supports on the stress-strain state of steel concrete structures exposed to one-time dynamic loading resulting in failure. Oblique bending beams on elastic supports and their elastic, elastoplastic, and elastoplastic consolidation behavior are considered in this paper. For numerical calculations the developed computer program is used based on the finite element method. Research findings prove high efficiency of elastic supports under dynamic loading conditions. The most effective behavior of elastic supports is demonstrated at the elastoplastic stage. A good agreement is observed between the theoretical and experimental results.

  16. An optimal multiple switching problem under weak assumptions

    Directory of Open Access Journals (Sweden)

    Imen Hassairi

    2017-10-01

    Full Text Available This work studies the problem of optimal multiple switching in finite horizon, when the switching costs functions are continous and belong to class D. This problem is solved by means of the Snell envelope of processes.

  17. Structural qualia: a solution to the hard problem of consciousness

    Directory of Open Access Journals (Sweden)

    Kristjan eLoorits

    2014-03-01

    Full Text Available The hard problem of consciousness has been often claimed to be unsolvable by the methods of traditional empirical sciences. It has been argued that all the objects of empirical sciences can be fully analyzed in structural terms but that consciousness is (or has something over and above its structure. However, modern neuroscience has introduced a theoretical framework in which also the apparently non-structural aspects of consciousness, namely the so called qualia or qualitative properties, can be analyzed in structural terms. That framework allows us to see qualia as something compositional with internal structures that fully determine their qualitative nature. Moreover, those internal structures can be identified which certain neural patterns. Thus consciousness as a whole can be seen as a complex neural pattern that misperceives some of its own highly complex structural properties as monadic and qualitative. Such neural pattern is analyzable in fully structural terms and thereby the hard problem is solved.

  18. solution of confined seepage problems below hydraulic structures ...

    African Journals Online (AJOL)

    user

    1985-09-01

    Manuscript received April, 1985). ABSTRACT. Confined seepage problems below hydraulic structures using finite element method are investigated. The foundations are assumed to be infinite with homogeneous and isotropic ...

  19. Can a structured checklist prevent problems with laparoscopic equipment?

    NARCIS (Netherlands)

    Verdaasdonk, E.G.G.; Stassen, L.P.S.; Hoffmann, W.F.; Van der Elst, M.; Dankelman, J.

    2008-01-01

    Background A high incidence of problems with the technical equipment is known to occur during routine laparoscopic procedures. Use of a structured checklist of preparatory measures could help to prevent these problems. This study aimed to determine the extent to which a checklist reduced the number

  20. Applicability Problem in Optimum Reinforced Concrete Structures Design

    Directory of Open Access Journals (Sweden)

    Ashara Assedeq

    2016-01-01

    Full Text Available Optimum reinforced concrete structures design is very complex problem, not only considering exactness of calculus but also because of questionable applicability of existing methods in practice. This paper presents the main theoretical mathematical and physical features of the problem formulation as well as the review and analysis of existing methods and solutions considering their exactness and applicability.

  1. Structural behavior of supercritical fluids under confinement

    Science.gov (United States)

    Ghosh, Kanka; Krishnamurthy, C. V.

    2018-01-01

    The existence of the Frenkel line in the supercritical regime of a Lennard-Jones (LJ) fluid shown through molecular dynamics (MD) simulations initially and later corroborated by experiments on argon opens up possibilities of understanding the structure and dynamics of supercritical fluids in general and of the Frenkel line in particular. The location of the Frenkel line, which demarcates two distinct physical states, liquidlike and gaslike within the supercritical regime, has been established through MD simulations of the velocity autocorrelation (VACF) and radial distribution function (RDF). We, in this article, explore the changes in the structural features of supercritical LJ fluid under partial confinement using atomistic walls. The study is carried out across the Frenkel line through a series of MD simulations considering a set of thermodynamics states in the supercritical regime (P =5000 bar, 240 K ≤T ≤1500 K ) of argon well above the critical point. Confinement is partial, with atomistic walls located normal to z and extending to "infinity" along the x and y directions. In the "liquidlike" regime of the supercritical phase, particles are found to be distributed in distinct layers along the z axis with layer spacing less than one atomic diameter and the lateral RDF showing amorphous-like structure for specific spacings (packing frustration) and non-amorphous-like structure for other spacings. Increasing the rigidity of the atomistic walls is found to lead to stronger layering and increased structural order. For confinement with reflective walls, layers are found to form with one atomic diameter spacing and the lateral RDF showing close-packed structure for the smaller confinements. Translational order parameter and excess entropy assessment confirms the ordering taking place for atomistic wall and reflective wall confinements. In the "gaslike" regime of the supercritical phase, particle distribution along the spacing and the lateral RDF exhibit features

  2. Recent advances in numerical analysis of structural eigenvalue problems

    Science.gov (United States)

    Gupta, K. K.

    1973-01-01

    A wide range of eigenvalue problems encountered in practical structural engineering analyses is defined, in which the structures are assumed to be discretized by any suitable technique such as the finite-element method. A review of the usual numerical procedures for the solution of such eigenvalue problems is presented and is followed by an extensive account of recently developed eigenproblem solution procedures. Particular emphasis is placed on the new numerical algorithms and associated computer programs based on the Sturm sequence method. Eigenvalue algorithms developed for efficient solution of natural frequency and buckling problems of structures are presented, as well as some eigenvalue procedures formulated in connection with the solution of quadratic matrix equations associated with free vibration analysis of structures. A new algorithm is described for natural frequency analysis of damped structural systems.

  3. Structural pounding of concrete frame structure with masonry infill wall under seismic loading

    Science.gov (United States)

    Ismail, Rozaina; Hasnan, Mohd Hafizudin; Shamsudin, Nurhanis

    2017-10-01

    Structural pounding is additional problem than the other harmful damage that may occurs due to the earthquake vibrations. A lot of study has been made by past researcher but most of them did not include the walls. The infill masonry walls are rarely involved analysis of structural systems but it does contribute to earthquake response of the structures. In this research, a comparison between adjacent building of 10-storey and 7-storey concrete frame structure without of masonry infill walls and the same dynamic properties of buildings. The diagonal strut approach is adopted for modeling masonry infill walls. This research also focused on finding critical building separation in order to prevent the adjacent structures from pounding. LUSAS FEA v14.03 software has been used for modeling analyzing the behavior of structures due to seismic loading and the displacement each floor of the building has been taken in order to determine the critical separation distance between the buildings. From the analysis that has been done, it is found that masonry infill walls do affect the structures behavior under seismic load. Structures without masonry infill walls needs more distance between the structures to prevent structural pounding due to higher displacement of the buildings when it sways under seismic load compared to structures with masonry infill walls. This shows that contribution of masonry infill walls to the analysis of structures cannot be neglected.

  4. Problems in classical and quantum mechanics extracting the underlying concepts

    CERN Document Server

    Kelley, J Daniel

    2017-01-01

    This book is a collection of problems intended to aid students in their graduate courses in physics and in preparing for the PhD qualifying exam. Thus, the included problems are of the type that could be on a qualifying exam or are problems that are meant to elucidate a principle that is important for the exam. Unlike other compilations of problems, the problems in this text are placed in the broader context of the subject. The goal of the book is to develop the problem solving skills of the reader to insure a complete understanding of the physics. Problems and solutions are presented in detail, and, additionally, their significance is discussed within the context of the physical principle(s) that they illustrate. The solution of the problem is only the beginning of the learning process--it is in manipulating the solution and changing the parameters that a great deal of insight can be gleaned. This technique is referred to by the authors as "massaging the problem," and it is a technique that the authors have ...

  5. The Liner Shipping Routing and Scheduling Problem Under Environmental Considerations

    DEFF Research Database (Denmark)

    Dithmer, Philip; Reinhardt, Line Blander; Kontovas, Christos

    2017-01-01

    This paper deals with the Liner Shipping Routing and Scheduling Problem (LSRSP), which consists of designing the time schedule for a vessel to visit a fixed set of ports while minimizing costs. We extend the classical problem to include the external cost of ship air emissions and we present some ...

  6. Structural modifications of spinels under radiation

    International Nuclear Information System (INIS)

    Quentin, A.

    2010-12-01

    This work is devoted to the study of spinel structure materials under radiation. For that purpose, samples of polycrystalline ZnAl 2 O 4 and monocrystalline MgAl 2 O 4 were irradiated by different heavy ions with different energies. Samples of ZnAl 2 O 4 were studied par electron transmission microscopy, and by grazing incidence X-Ray diffraction and Rietveld analysis. Samples of MgAl 2 O 4 were studied by optical spectroscopy. Most of the results concern amorphization and crystalline structure modification of ZnAl 2 O 4 especially the inversion. We were able to determine a stopping power threshold for amorphization, between 11 keV/nm and 12 keV/nm, and also the amorphization process, which is a multiple impacts process. We studied the evolution of the amorphous phase by TEM and showed a nano-patterning phenomenon. Concerning the inversion, we determined that it did happen by a single impact process, and the saturation value did not reach the random cation distribution value. Inversion and amorphization have different, but close, stopping power threshold. However, amorphization seems to be conditioned by a pre-damage of the material which consists in inversion. (author)

  7. Variational structure of inverse problems in wave propagation and vibration

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    1995-03-01

    Practical algorithms for solving realistic inverse problems may often be viewed as problems in nonlinear programming with the data serving as constraints. Such problems are most easily analyzed when it is possible to segment the solution space into regions that are feasible (satisfying all the known constraints) and infeasible (violating some of the constraints). Then, if the feasible set is convex or at least compact, the solution to the problem will normally lie on the boundary of the feasible set. A nonlinear program may seek the solution by systematically exploring the boundary while satisfying progressively more constraints. Examples of inverse problems in wave propagation (traveltime tomography) and vibration (modal analysis) will be presented to illustrate how the variational structure of these problems may be used to create nonlinear programs using implicit variational constraints.

  8. Optimal infrastructure maintenance scheduling problem under budget uncertainty.

    Science.gov (United States)

    2010-05-01

    This research addresses a general class of infrastructure asset management problems. Infrastructure : agencies usually face budget uncertainties that will eventually lead to suboptimal planning if : maintenance decisions are made without taking the u...

  9. On structural design optimization under uncertainty and risk

    International Nuclear Information System (INIS)

    Teofilo Beck, Andre; Santana Gomes, Wellison Jose de

    2010-01-01

    In this paper, the effects of uncertainty and risk on structural design optimization are investigated, by comparing results of Deterministic Design Optimization (DDO), Reliability-based Design Optimization (RBDO) and Reliability-based Risk Optimization (RBRO). DDO yields a structural topology (or shape) which is optimum in terms of mechanics, but does not explicitly address parameter uncertainties and their effects on structural safety. RBDO properly models safety-under-uncertainty, allowing the optimum structure to maintain an acceptable level of safety. Results, however, are dependent on the failure probability used as constraint. Risk optimization (RBRO) increases the scope of the problem, by addressing the compromising goals of economy and safety. This is accomplished by quantifying the costs associated to construction, operation and maintenance, as well as the monetary consequences of failure. RBRO yields the optimum topology and the optimum point of balance between economy and safety. Results are compared for some example problems. The broader RBRO solution is found first, and optimum results are used as constraints in DDO and RBDO. Results show that even when the optimum safety coefficients are used as constraint in DDO, the formulation leads to optimum configurations which respect these design constraints, reduce manufacturing costs but increase total expected costs (including expected cost of failure). If the (optimum) system failure probability is used as constraint in RBDO, the optimum solution reduces manufacturing costs, but by increasing total expected costs. This happens when the costs associated to different failure modes are distinct.

  10. Newsvendor problem with random shortage cost under a risk criterion

    NARCIS (Netherlands)

    Wu, Meng; Zhu, Stuart X.; Teunter, Ruud H.

    2013-01-01

    We study profit maximization vs risk approaches for the standard newsvendor problem with uncertainty in demand as well as a generalized version with uncertainty in the shortage cost (as often applies in practice). We consider two well-known risk approaches: Value-at-Risk (VaR) included as a

  11. Environmental problems indicator under environmental modeling toward sustainable development

    OpenAIRE

    P. Sutthichaimethee; W. Tanoamchard; P. Sawangwong; P Pachana; N. Witit-Anun

    2015-01-01

    This research aims to apply a model to the study and analysis of environmental and natural resource costs created in supply chains of goods and services produced in Thailand, and propose indicators for environmental problem management, caused by goods and services production, based on concepts of sustainable production and consumer behavior. The research showed that the highest environmental cost in terms of Natural Resource Materials was from pipelines and gas distribution, while the lowest ...

  12. Magnetic structures of erbium under high pressure

    DEFF Research Database (Denmark)

    Kawano, S.; Lebech, B.; Achiwa, N.

    1993-01-01

    Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists...

  13. Electronic structure of Ca, Sr, and Ba under pressure.

    Science.gov (United States)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  14. 34 CFR 356.11 - What types of problems may be researched under the fellowship program?

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false What types of problems may be researched under the... (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION DISABILITY AND... Program? § 356.11 What types of problems may be researched under the fellowship program? Problems...

  15. Solution of Confined Seepage Problems below Hydraulic Structures ...

    African Journals Online (AJOL)

    Confined seepage problems below hydraulic structures using finite element method are investigated. The foundations are assumed to be infinite with homogeneous and isotropic conditions. Three different types of elements with varying mesh sizes are used for comparing the finite element results with those of exact ...

  16. Fatigue life prediction of mechanical structures under stochastic loading

    Directory of Open Access Journals (Sweden)

    Leitner Bohuš

    2018-01-01

    Full Text Available Problems of fatigue life prediction of materials and structures are discussed in the paper. Service loading is assumed as a continuous loading process with possible discontinuous events, which are caused by various operating conditions. The damage in a material is due to a cumulative degradation process. The damaging process is then represented either by rain-flow matrices or by a fatigue damage function which is derived using some hypothesis of a fatigue failure criterion. Presented theoretical procedure enables a very effective estimation of a service life and/or reliable evaluation of residual life of any structures under various types of loading and environmental conditions. This approach creates a good basis for powerful expert systems in structural and mechanical engineering. The aim of the paper is to present briefly some results of analysis of load-bearing steel structure loads of special railway crane PKP 25/20i which was utilized in some specific ad relatively hard operating conditions. Virtual models of the structure were being used in an analysis of acting working dynamics loads influence to be able to forecast fatigue life of load-bearing of the crane jib.

  17. Historicising the budgetary problems of Ghana and Nigeria under ...

    African Journals Online (AJOL)

    The 1990s were periods in the history of Africa that many states on the continent which had hitherto been governed by military dictatorships began to embrace democracy. Under the military dictatorship and their similar civilian variants, the economies of these states had witnessed utter ruination partly as a result of IMF or ...

  18. Prospects and problems of vegetable production under irrigation in ...

    African Journals Online (AJOL)

    FUAs) in the State were randomly selected. Three categories of farmers were formed for easy analyses, namely: below 1.0ha, 1-2.99ha and 3-4.99ha, farmers. Primary data were collected using structured questionnaire supplemented with ...

  19. The structure of spectral problems and geometry: hyperbolic surfaces in E sup 3

    CERN Document Server

    Cieslinski, J L

    2003-01-01

    Working in the framework of Sym's soliton surfaces approach we point out that some simple assumptions about the structure of linear (spectral) problems of the theory of solitons lead uniquely to the geometry of some special immersions. In this paper we consider general su(2) spectral problems. Under some very weak assumptions they turn out to be associated with hyperbolic surfaces (surfaces of negative Gaussian curvature) immersed in three-dimensional Euclidean space, and especially with the so-called Bianchi surfaces.

  20. Response of masonry structure under impact load

    International Nuclear Information System (INIS)

    Makovicka, D.

    1993-01-01

    The paper deals with interaction of a short gaseous impact wave with a plate structure. Analyses of dynamic bending, depending on the parameters of the structure and the impact wave (i.e. the stress and displacement field produced by the resulting incident and reflected wave) have been made by FEM. The calculated data was based on the real material properties of this structure. Pressures greater than computed limit pressures result in the failure of the structure. The calculated and experimental data are compared. (author)

  1. MSClique: Multiple Structure Discovery through the Maximum Weighted Clique Problem.

    Directory of Open Access Journals (Sweden)

    Gerard Sanroma

    Full Text Available We present a novel approach for feature correspondence and multiple structure discovery in computer vision. In contrast to existing methods, we exploit the fact that point-sets on the same structure usually lie close to each other, thus forming clusters in the image. Given a pair of input images, we initially extract points of interest and extract hierarchical representations by agglomerative clustering. We use the maximum weighted clique problem to find the set of corresponding clusters with maximum number of inliers representing the multiple structures at the correct scales. Our method is parameter-free and only needs two sets of points along with their tentative correspondences, thus being extremely easy to use. We demonstrate the effectiveness of our method in multiple-structure fitting experiments in both publicly available and in-house datasets. As shown in the experiments, our approach finds a higher number of structures containing fewer outliers compared to state-of-the-art methods.

  2. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    determination of the appropriate laminate thickness and the material choice in the structure. The optimal design problems that arise are stated as nonconvex mixed integer programming problems. We resort to different reformulation techniques to state the optimization problems as either linear or nonlinear convex....... The continuous relaxation of the mixed integer programming problems is being solved by an implementation of a primal–dual interior point method for nonlinear programming that updates the barrier parameter adaptively. The method is chosen for its excellent convergence properties and the ability of the method...... design phase results in structures with better structural performance reducing the need of manually post–processing the found designs....

  3. From poor performance to success under stress: working memory, strategy selection, and mathematical problem solving under pressure.

    Science.gov (United States)

    Beilock, Sian L; Decaro, Marci S

    2007-11-01

    Two experiments demonstrate how individual differences in working memory (WM) impact the strategies used to solve complex math problems and how consequential testing situations alter strategy use. In Experiment 1, individuals performed multistep math problems under low- or high-pressure conditions and reported their problem-solving strategies. Under low-pressure conditions, the higher individuals' WM, the more likely they were to use computationally demanding algorithms (vs. simpler shortcuts) to solve the problems, and the more accurate their math performance. Under high-pressure conditions, higher WM individuals used simpler (and less efficacious) problem-solving strategies, and their performance accuracy suffered. Experiment 2 turned the tables by using a math task for which a simpler strategy was optimal (produced accurate performance in few problem steps). Now, under low-pressure conditions, the lower individuals' WM, the better their performance (the more likely they relied on a simple, but accurate, problem strategy). And, under pressure, higher WM individuals performed optimally by using the simpler strategies lower WM individuals employed. WM availability influences how individuals approach math problems, with the nature of the task performed and the performance environment dictating skill success or failure. PsycINFO Database Record (c) 2007 APA, all rights reserved.

  4. [The contamination under polymerase chain reaction studies: problems and solutions].

    Science.gov (United States)

    Titov, V N; Ameliushkina, V A; Rozhkova, T A

    2015-01-01

    The study was carried out to determine risk factors of false positive and false negative results under polymerase chain reaction-analysis of clinical material. The samples with high viral load can be the source of false positive results. The contamination with nucleic acids can occur at any section of polymerase chain reaction analysis. The study data permitted to establish that the most sensitive stage is isolation and purification of nucleic acids especially under manual mode of operation. The detection of positive signal in most samples of one setting indicates total contamination. The cases when only several samples are polluted are special challenge. The presence of sample with high concentration of viral nucleic acid and several samples with low concentration in one setting means necessity of repeated analysis beginning with stage of isolation of nucleic acid. The analysis of curves of accumulation of products of amplification, their forms and positioning on chart is the obligatory stage of polymerase chain reaction study in real time regimen. These actions permit to exclude the readouts of false negative testing results to departments. The study conclusions are equipotent for polymerase chain reaction testing of any nucleic acid targets.

  5. Electrolyte imbalance and sleep problems during anti-retroviral therapy: an under-recognized problem

    Directory of Open Access Journals (Sweden)

    Md Dilshad Manzar

    Full Text Available Human immunodeficiency virus (HIV infection, and the anti-retroviral therapy (ART associated complications necessitate that the medical care system keeps evolving for proper management of this group of patients. Electrolyte imbalance and sleep problems are common in patients on ART. Both of these conditions are associated with increased morbidity (such as acute kidney injury, chronic kidney disease, low CD4 count, non-adherence and depression and mortality. Therefore, screening for both sleep problems and electrolytes imbalance may help to decrease the risk of complications in patients on ART.

  6. Electrolyte imbalance and sleep problems during anti-retroviral therapy: an under-recognized problem.

    Science.gov (United States)

    Manzar, Md Dilshad; Sony, Peter; Salahuddin, Mohammed; Kumalo, Abera; Geneto, Mathewos; Pandi-Perumal, Seithikurippu R; Moscovitch, Adam; BaHammam, Ahmed S

    2017-01-01

    Human immunodeficiency virus (HIV) infection, and the anti-retroviral therapy (ART) associated complications necessitate that the medical care system keeps evolving for proper management of this group of patients. Electrolyte imbalance and sleep problems are common in patients on ART. Both of these conditions are associated with increased morbidity (such as acute kidney injury, chronic kidney disease, low CD4 count, non-adherence and depression) and mortality. Therefore, screening for both sleep problems and electrolytes imbalance may help to decrease the risk of complications in patients on ART.

  7. Geriatric oncology: problems with under-treatment within this population.

    Science.gov (United States)

    Swaminathan, Divya; Swaminathan, Vikram

    2015-12-01

    We are currently faced with an aging population, which is rapidly growing worldwide. Two thirds of cancer occurs in the over 65-year age group. Societal conceptions from the past have created ageist stereotypes; old age is associated with frailty and the elderly are perceived to be destined for deterioration and loss of independence. Cancer within the elderly is also subject to these stereotypes, with elderly cancer patients considered by some not as likely to recover as younger patients with cancer. We summarise and review the current concerns regarding elderly management and treatments utilised for the management of oncological disease in the elderly, and discuss the impact of under-treatment within this population.

  8. An algebraic approach to scattering and band structure problems

    International Nuclear Information System (INIS)

    Alhassid, Y.

    1984-01-01

    It is shown that both bound and scattering states of a class of potentials are related to the unitary representations of certain groups. For such systems the scattering matrix can be calculated in a completely algebraic way through the use of the Euclidean group to describe asymptotic behaviour. The band structures associated with a family of periodic potentials can also be obtained from the group theory. These results suggest that an algebraic approach to scattering and band structure problems similar to that applied to bound states is possible

  9. Potential structural material problems in a hydrogen energy system

    Science.gov (United States)

    Gray, H. R.; Nelson, H. G.; Johnson, R. E.; Mcpherson, W. B.; Howard, F. S.; Swisher, J. H.

    1976-01-01

    Potential structural material problems that may be encountered in the three components of a hydrogen energy system - production, transmission/storage, and utilization - have been identified. Hydrogen embrittlement, corrosion, oxidation, and erosion may occur during the production of hydrogen. Hydrogen embrittlement is of major concern during both transmission and utilization of hydrogen. Specific materials research and development programs necessary to support a hydrogen energy system are described. An awareness of probable shortages of strategic materials has been maintained in these suggested programs.

  10. Integrated Force Method Solution to Indeterminate Structural Mechanics Problems

    Science.gov (United States)

    Patnaik, Surya N.; Hopkins, Dale A.; Halford, Gary R.

    2004-01-01

    Strength of materials problems have been classified into determinate and indeterminate problems. Determinate analysis primarily based on the equilibrium concept is well understood. Solutions of indeterminate problems required additional compatibility conditions, and its comprehension was not exclusive. A solution to indeterminate problem is generated by manipulating the equilibrium concept, either by rewriting in the displacement variables or through the cutting and closing gap technique of the redundant force method. Compatibility improvisation has made analysis cumbersome. The authors have researched and understood the compatibility theory. Solutions can be generated with equal emphasis on the equilibrium and compatibility concepts. This technique is called the Integrated Force Method (IFM). Forces are the primary unknowns of IFM. Displacements are back-calculated from forces. IFM equations are manipulated to obtain the Dual Integrated Force Method (IFMD). Displacement is the primary variable of IFMD and force is back-calculated. The subject is introduced through response variables: force, deformation, displacement; and underlying concepts: equilibrium equation, force deformation relation, deformation displacement relation, and compatibility condition. Mechanical load, temperature variation, and support settling are equally emphasized. The basic theory is discussed. A set of examples illustrate the new concepts. IFM and IFMD based finite element methods are introduced for simple problems.

  11. Structure of polymer chains under confinement

    Indian Academy of Sciences (India)

    cluded volume interactions (so-called regime of “semi-dilute cigars”). For confined charged polymers, a peak is observed whose intensity increases with molecular weight and the asymptotic 1/q scattering region is extended compared to the bulk. We infer that the chains are sufficiently extended, under the influence of ...

  12. Concurrent Structural Fatigue Damage Prognosis Under Uncertainty

    Science.gov (United States)

    2014-04-30

    same experiment is carried on AISI 4340 steel. AISI 4340 steel is a heat treatable, low alloy steel containing nickel, chromium and molybdenum. The...but after the unstable crack growth after the overload, it is 82 83 hard to measure the crack growth per cycle which is smaller than 20...structural and macro materials level. The extension to include material microstructure effect for the fatigue prognosis needs further investigations

  13. Robustness Assessment of Building Structures under Explosion

    Directory of Open Access Journals (Sweden)

    Mark Waggoner

    2012-12-01

    Full Text Available Over the past decade, much research has focused on the behaviour of structures following the failure of a key structural component. Particular attention has been given to sudden column loss, though questions remain as to whether this event-independent scenario is relevant to actual extreme events such as explosion. Few studies have been conducted to assess the performance of floor slabs above a failed column, and the computational tools used have not been validated against experimental results. The research program presented in this paper investigates the adequacy of sudden column loss as an idealisation of local damage caused by realistic explosion events, and extends prior work by combining the development of accurate computational models with large-scale testing of a typical floor system in a prototypical steel-framed structure. The floor system consists of corrugated decking topped by a lightly reinforced concrete slab that is connected to the floor beams through shear studs. The design is consistent with typical building practices in the US. The first test has been completed, and subsequent tests are currently being planned. This paper addresses the importance of robustness design for localized damage and includes a detailed description regarding how the research program advances the current state of knowledge for assessing robustness of compositely constructed steel-framed buildings.

  14. Use of Lanczos vectors in fluid/structure interaction problems

    International Nuclear Information System (INIS)

    Jeans, R.; Mathews, I.C.

    1992-01-01

    The goals of any numerical computational technique used for the solution of structural acoustics problems in the exterior infinite domain should be of accuracy with rapid convergence, robustness, and computational efficiency. A computer program has been developed to achieve each of these three goals. Accuracy and robustness in the numerical representation of the integral equations used to represent the infinite fluid was attained through the use of boundary element implementations of the surface Helmholtz integral equations. The computational efficiency was resolved through the use of Lanczos vectors to model the deformation characteristics of the structure. The authors have developed collocation and variational techniques to overcome the difficulties previously encountered in the numerical implementation of the hypersingular integral operator. The Cauchy singularity present in the integral formulation is made numerically amenable through the use of tangential derivatives in both the collocation and variational techniques. The variational approach has the advantage that the resulting added fluid mass term is symmetric and combines efficiently with a finite element approximation of the structural elastic response. Several different strategies making use of the Lanczos vectors have been investigated. The first involved the use of Lanczos vectors solely to characterize the structural response. This reduced form of the structural dynamical matrix was then substituted back into a Burton and Miller formulation of the acoustic problem. The second strategy investigated involved forming the complex Lanzcos vectors of the dynamical matrix formed from the addition of a symmetrical added fluid matrix to the structural mass matrix. The size of resultant matrix equation set solved at each frequency for this strategy is determined by the number of Lanczos vectors used. 19 refs., 10 figs., 2 tabs

  15. Writing Problems in Developmental Dyslexia: Under-Recognized and Under-Treated2,3

    OpenAIRE

    Berninger, Virginia W.; Nielsen, Kathleen H.; Abbott, Robert D.; Wijsman, Ellen; Raskind, Wendy

    2008-01-01

    The International Dyslexia Association defines dyslexia as unexpected problems of neurobiological origin in accuracy and rate of oral reading of single real words, single pseudowords, or text or of written spelling. However, prior research has focused more on the reading than the spelling problems of students with dyslexia. A test battery was administered to 122 children who met inclusion criteria for dyslexia and qualified their families for participation in a family genetics study that has ...

  16. Materials and structures under shock and impact

    CERN Document Server

    Bailly, Patrice

    2013-01-01

    In risk studies, engineers often have to consider the consequences of an accident leading to a shock on a construction. This can concern the impact of a ground vehicle or aircraft, or the effects of an explosion on an industrial site.This book presents a didactic approach starting with the theoretical elements of the mechanics of materials and structures, in order to develop their applications in the cases of shocks and impacts. The latter are studied on a local scale at first. They lead to stresses and strains in the form of waves propagating through the material, this movement then extending

  17. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    sequence of well–posed optimization problems. They provide us with a discrete feasible solution or correctly determine problem infeasibility. Our aim is to solve the considered problems to proven global optimality. We propose a combination of the convergent Outer Approximation and Local Branching......This thesis considers discrete multi material and thickness optimization of laminated composite structures including local failure criteria and manufacturing constraints. Our models closely follow an immediate extension of the Discrete Material Optimization scheme, which allows simultaneous...... determination of the appropriate laminate thickness and the material choice in the structure. The optimal design problems that arise are stated as nonconvex mixed integer programming problems. We resort to different reformulation techniques to state the optimization problems as either linear or nonlinear convex...

  18. Factor structure underlying components of allostatic load.

    Directory of Open Access Journals (Sweden)

    Jeanne M McCaffery

    Full Text Available Allostatic load is a commonly used metric of health risk based on the hypothesis that recurrent exposure to environmental demands (e.g., stress engenders a progressive dysregulation of multiple physiological systems. Prominent indicators of response to environmental challenges, such as stress-related hormones, sympatho-vagal balance, or inflammatory cytokines, comprise primary allostatic mediators. Secondary mediators reflect ensuing biological alterations that accumulate over time and confer risk for clinical disease but overlap substantially with a second metric of health risk, the metabolic syndrome. Whether allostatic load mediators covary and thus warrant treatment as a unitary construct remains to be established and, in particular, the relation of allostatic load parameters to the metabolic syndrome requires elucidation. Here, we employ confirmatory factor analysis to test: 1 whether a single common factor underlies variation in physiological systems associated with allostatic load; and 2 whether allostatic load parameters continue to load on a single common factor if a second factor representing the metabolic syndrome is also modeled. Participants were 645 adults from Allegheny County, PA (30-54 years old, 82% non-Hispanic white, 52% female who were free of confounding medications. Model fitting supported a single, second-order factor underlying variance in the allostatic load components available in this study (metabolic, inflammatory and vagal measures. Further, this common factor reflecting covariation among allostatic load components persisted when a latent factor representing metabolic syndrome facets was conjointly modeled. Overall, this study provides novel evidence that the modeled allostatic load components do share common variance as hypothesized. Moreover, the common variance suggests the existence of statistical coherence above and beyond that attributable to the metabolic syndrome.

  19. Structure of Matter An Introductory Course with Problems and Solutions

    CERN Document Server

    Rigamonti, Attilio

    2007-01-01

    This is the second edition of this textbook, the original of which was published in 2007. Initial undergraduate studies in physics are usually in an organized format devoted to elementary aspects, which is then followed by advanced programmes in specialized fields. A difficult task is to provide a formative introduction in the early period, suitable as a base for courses more complex, thus bridging the wide gap between elementary physics and topics pertaining to research activities. This textbook remains an endeavour toward that goal, and is based on a mixture of simplified institutional theory and solved problems. In this way, the hope is to provide physical insight, basic knowledge and motivation, without impeding advanced learning. The choice has been to limit the focus to key concepts and to those aspects most typical of atoms, molecules and compounds, by looking at the basic, structural components, without paying detailed attention to the properties possessed by them. Problems are intertwined with formal...

  20. Structure of Matter An Introductory Course with Problems and Solutions

    CERN Document Server

    Rigamonti, Attilio

    2009-01-01

    This is the second edition of this textbook, the original of which was published in 2007. Initial undergraduate studies in physics are usually in an organized format devoted to elementary aspects, which is then followed by advanced programmes in specialized fields. A difficult task is to provide a formative introduction in the early period, suitable as a base for courses more complex, thus bridging the wide gap between elementary physics and topics pertaining to research activities. This textbook remains an endeavour toward that goal, and is based on a mixture of simplified institutional theory and solved problems. In this way, the hope is to provide physical insight, basic knowledge and motivation, without impeding advanced learning. The choice has been to limit the focus to key concepts and to those aspects most typical of atoms, molecules and compounds, by looking at the basic, structural components, without paying detailed attention to the properties possessed by them. Problems are intertwined with formal...

  1. The problem of helium in structural materials for fusion reactor

    International Nuclear Information System (INIS)

    Nikiforov, A.S.; Zakharov, A.P.; Chuev, V.I.

    1982-01-01

    The processes of helium buildup in some metals and alloys at different energy neutron flux irradiation under thermonuclear reactor conditions are considered. The data on high temperature helium embrittlement of a number of stainless steels, titanium and aluminium alloys etc. are given A review of experiments concerning the implanted helium behaviour is presented. Possible reactions between helium atoms and point defects or their clusters are discussed. Analysed are material structure variations upon buildup in them up to 1 at % of helium

  2. State vector labelling problem: a review of structural principles

    International Nuclear Information System (INIS)

    Louck, J.D.

    1976-01-01

    The technique of labeling state vectors by use of the simultaneous eigenvalues of a complete set of commuting Hermitian operators stems from the early days of quantum theory. In sharp contrast to the classical method, there stands the nonorthogonal bases methods of Moshinsky and Bargmann and the null space methods of Biedenharn and Louck. The structural principles underlying these various methods are presented and discussed. 2 figures

  3. Structure of matter an introductory course with problems and solutions

    CERN Document Server

    Rigamonti, Attilio

    2015-01-01

    This textbook, now in its third edition, provides a formative introduction to the structure of matter that will serve as a sound basis for students proceeding to more complex courses, thus bridging the gap between elementary physics and topics pertaining to research activities. The focus is deliberately limited to key concepts of atoms, molecules and solids, examining the basic structural aspects without paying detailed attention to the related properties. For many topics the aim has been to start from the beginning and to guide the reader to the threshold of advanced research. This edition includes four new chapters dealing with relevant phases of solid matter (magnetic, electric and superconductive) and the related phase transitions. The book is based on a mixture of theory and solved problems that are integrated into the formal presentation of the arguments. Readers will find it invaluable in enabling them to acquire basic knowledge in the wide and wonderful field of condensed matter and to understand how ...

  4. On the problem of studying physical properties of rock collectors under conditions modelling layer ones

    Energy Technology Data Exchange (ETDEWEB)

    Petkevich, G.I.

    1972-01-01

    A review is given of the state in studying physical properties of rock collectors under conditions modelling the layer ones. From the theoretical point of view, this direction is determined as petrophysics of multiphase systems and from the practical, as oil field petrophysics. The following aspects of the problem are considered: models of porous media, thermodynamic conditions of deformation process, parameters of stressed state of porous deformed media, and analysis of experimental data. To describe collector behavior under thermodynamic conditions of natural occurrence, it is necessary to construct the model of the porous deformed medium. In connection with heterogeneity and multiphase character of rock collectors, they may be considered as differential-elastic media, and to characterize the stressed state such indices as coefficients of compressibility of skeleton, solid and liquid phase, as well as coefficients of pore compressibility, relaxation, structural parameter, etc. may be used. It is emphasized that only reversable (elastic) parameter changes are studied under laboratory conditions. The results of laboratory measurements of collector parameters are summarized on the basis of different researcher data. (54 refs.)

  5. Empirical Analysis of Farm Credit Risk under the Structure Model

    Science.gov (United States)

    Yan, Yan

    2009-01-01

    The study measures farm credit risk by using farm records collected by Farm Business Farm Management (FBFM) during the period 1995-2004. The study addresses the following questions: (1) whether farm's financial position is fully described by the structure model, (2) what are the determinants of farm capital structure under the structure model, (3)…

  6. Skin problems in children under five years old at a rural hospital in Southern Ethiopia

    Directory of Open Access Journals (Sweden)

    José Manuel Ramos

    2016-07-01

    Conclusions: Skin problems, mainly scabies, impetigo, and eczema were common in young children attended at a rural hospital in Southern Ethiopia. Children under 5 years should be examined thoroughly to rule out skin diseases, especially scabies.

  7. Quaternionic contact Einstein structures and the quaternionic contact Yamabe problem

    International Nuclear Information System (INIS)

    Ivanov, S.; Minchev, I.; Vassilev, D.

    2006-12-01

    The paper is a study of the conformal geometry of quaternionic contact manifolds with the associated Biquard connection. We give a partial solution of the quaternionic contact Yamabe problem on the quaternionic sphere. It is shown that the torsion of the Biquard connection vanishes exactly when the trace-free part of the horizontal Ricci tensor of the Biquard connection is zero and this occurs precisely on 3-Sasakian manifolds. In particular, the scalar curvature of the Biquard connection with vanishing torsion is a global constant. We consider interesting classes of functions on hypercomplex manifold and their restrictions to hypersurfaces. We show a '3-Hamiltonian form' of infinitesimal automorphisms of quaternionic contact structures and transformations preserving the trace-free part of the horizontal Ricci tensor of the Biquard connection. All conformal deformations sending the standard flat torsion-free quaternionic contact structure on the quaternionic Heisenberg group to a quaternionic contact structure with vanishing trace-free part of the horizontal Ricci tensor of the Biquard connection are explicitly described. (author)

  8. Topographic mapping of oral structures - problems and applications in prosthodontics

    Science.gov (United States)

    Young, John M.; Altschuler, Bruce R.

    1981-10-01

    The diagnosis and treatment of malocclusion, and the proper design of restorations and prostheses, requires the determination of surface topography of the teeth and related oral structures. Surface contour measurements involve not only affected teeth, but adjacent and opposing surface contours composing a complexly interacting occlusal system. No a priori knowledge is predictable as dental structures are largely asymmetrical, non-repetitive, and non-uniform curvatures in 3-D space. Present diagnosis, treatment planning, and fabrication relies entirely on the generation of physical replicas during each stage of treatment. Fabrication is limited to materials that lend themselves to casting or coating, and to hand fitting and finishing. Inspection is primarily by vision and patient perceptual feedback. Production methods are time-consuming. Prostheses are entirely custom designed by manual methods, require costly skilled technical labor, and do not lend themselves to centralization. The potential improvement in diagnostic techniques, improved patient care, increased productivity, and cost-savings in material and man-hours that could result, if rapid and accurate remote measurement and numerical (automated) fabrication methods were devised, would be significant. The unique problems of mapping oral structures, and specific limitations in materials and methods, are reviewed.

  9. The Orienteering Problem under Uncertainty Stochastic Programming and Robust Optimization compared

    NARCIS (Netherlands)

    Evers, L.; Glorie, K.; Ster, S. van der; Barros, A.I.; Monsuur, H.

    2012-01-01

    The Orienteering Problem (OP) is a generalization of the well-known traveling salesman problem and has many interesting applications in logistics, tourism and defense. To reflect real-life situations, we focus on an uncertain variant of the OP. Two main approaches that deal with optimization under

  10. Thermal behavior of spatial structures under solar irradiation

    International Nuclear Information System (INIS)

    Liu, Hongbo; Liao, Xiangwei; Chen, Zhihua; Zhang, Qian

    2015-01-01

    The temperature, particularly the non-uniform temperature under solar irradiation, is the main load for large-span steel structures. Due the shortage of in-site temperature test in previous studies, an in-site test was conducted on the large-span steel structures under solar irradiation, which was covered by glass roof and light roof, to gain insight into the temperature distribution of steel members under glass roof or light roof. A numerical method also was presented and verified to forecast the temperature of steel member under glass roof or light roof. Based on the on-site measurement and numerical analyses conducted, the following conclusions were obtained: 1) a remarkable temperature difference exists between the steel member under glass roof and that under light roof, 2) solar irradiation has a significant effect on the temperature distribution and thermal behavior of large-span spatial structures, 3) negative thermal load is the controlling factor for member stress, and the positive thermal load is the controlling factor for nodal displacement. - Highlights: • Temperature was measured for a steel structures under glass roof and light roof. • Temperature simulation method was presented and verified. • The thermal behavior of steel structures under glass or light roof was presented

  11. Sleep disturbances and memory impairment among pregnant women consuming khat: An under-recognized problem

    Directory of Open Access Journals (Sweden)

    Md. Dilshad Manzar

    2017-01-01

    Full Text Available Khat (Catha edulis is a evergreen flowering shrub that is cultivated at high altitudes, especially in East Africa and the southwest of the Arabian Peninsula. The plant contains alkaloids, of which cathinone and cathine have structural similarity and pharmacological action similar to amphetamines. The leaves are, therefore, consumed in some regions as a psychoactive stimulant due to cultural beliefs and misperceptions on the health benefits of khat consumption. This resulted in a growing prevalence of khat consumption among pregnant women. The myriad of physiological changes associated with pregnancy impairs sleep and memory. Moreover, khat has also been shown to have adverse effects on memory and sleep. Therefore, its use during pregnancy may further aggravate those impairments. The purpose of this mini-review is to summarize the changes in sleep and memory during pregnancy and the evidence supporting a relationship between khat consumption and neurocognitive deficits and sleep dysfunctions. The misperceptions of beneficial effects of khat, the high prevalence of consumption among pregnant women, and the possibility of under-reporting of khat abuse do necessitate the development of alternative methodologies to identify cases of unreported khat abuse in pregnant women. It is proposed that screening for sleep problems and memory deficits may help identify under-reported cases of khat abuse in pregnant women.

  12. Sleep disturbances and memory impairment among pregnant women consuming khat: An under-recognized problem.

    Science.gov (United States)

    Manzar, Md Dilshad; Salahuddin, Mohammed; Sony, Peter; Maru, Tarekegn Tesfaye; Pandi-Perumal, Seithikurippu R; Moscovitch, Adam; Bahammam, Ahmed S

    2017-01-01

    Khat ( Catha edulis ) is a evergreen flowering shrub that is cultivated at high altitudes, especially in East Africa and the southwest of the Arabian Peninsula. The plant contains alkaloids, of which cathinone and cathine have structural similarity and pharmacological action similar to amphetamines. The leaves are, therefore, consumed in some regions as a psychoactive stimulant due to cultural beliefs and misperceptions on the health benefits of khat consumption. This resulted in a growing prevalence of khat consumption among pregnant women. The myriad of physiological changes associated with pregnancy impairs sleep and memory. Moreover, khat has also been shown to have adverse effects on memory and sleep. Therefore, its use during pregnancy may further aggravate those impairments. The purpose of this mini-review is to summarize the changes in sleep and memory during pregnancy and the evidence supporting a relationship between khat consumption and neurocognitive deficits and sleep dysfunctions. The misperceptions of beneficial effects of khat, the high prevalence of consumption among pregnant women, and the possibility of under-reporting of khat abuse do necessitate the development of alternative methodologies to identify cases of unreported khat abuse in pregnant women. It is proposed that screening for sleep problems and memory deficits may help identify under-reported cases of khat abuse in pregnant women.

  13. The problems of material pairs under the specific conditions of high-temperature reactors

    International Nuclear Information System (INIS)

    Schoening, J.

    1981-01-01

    This dissertation gives a detailed descirption of the problems of friction and solid lubrication of slide and ball bearings under HTR conditions. The first part is concerned with an analysis of established approaches for determining the friction factor and the development of a mathematical model on this basis, taking particular account of the following parameters. (1) Surface characteristics (peak-to-valley height, pressure angles of roughness elevations) and, (2) material properties of the friction partner (ductility, brittleness, crystal structure). The formula for friction factor thus arrived at incorporates the microscopic and sub-microscopic influence of the surface grain structure. In addition, the effects of elastic and plastic properties at the region of contact was studied. The derived equation is used to characterise frictional properties and enables a suitable and economic friction pair to be selected. The second part deals with the application of solid lubrication and the effect of the solid lubricant film on the mechanicsm and kinematics of ball bearings. In the final part of this investigation an evaluation of experimental results is carried out on the basis of the preceding theoretical studies in order to confirm the theoretical approach and to provide information of practical use on limits of application, cost details and aids to construction. (orig./IHOE) [de

  14. Problem statement for optimal design of steel structures

    Directory of Open Access Journals (Sweden)

    Ginzburg Aleksandr Vital'evich

    2014-07-01

    Full Text Available The presented article considers the following complex of tasks. The main stages of the life cycle of a building construction with the indication of process entrance and process exit are described. Requirements imposed on steel constructions are considered. The optimum range of application for steel designs is specified, as well as merits and demerits of a design material. The nomenclature of metal designs is listed - the block diagram is constructed. Possible optimality criteria of steel designs, offered by various authors for various types of constructions are considered. It is established that most often the criterion of a minimum of design mass is accepted as criterion of optimality; more rarely - a minimum of the given expenses, a minimum of a design cost in business. In the present article special attention is paid to a type of objective function of optimization problem. It is also established that depending on the accepted optimality criterion, the use of different types of functions is possible. This complexity of objective function depends on completeness of optimality criterion application. In the work the authors consider the following objective functions: the mass of the main element of a design; objective function by criterion of factory cost; objective function by criterion of cost in business. According to these examples it can be seen that objective functions by the criteria of labor expenses for production of designs are generally non-linear, which complicates solving the optimization problem. Another important factor influencing the problem of optimal design solution for steel designs, which is analyzed, is account for operating restrictions. In the article 8 groups of restrictions are analyzed. Attempts to completely account for the parameters of objective function optimized by particular optimality criteria, taking into account all the operating restrictions, considerably complicates the problem of designing. For solving this

  15. Structuring students’ analogical reasoning in solving algebra problem

    Science.gov (United States)

    Lailiyah, S.; Nusantara, T.; Sa'dijah, C.; Irawan, E. B.; Kusaeri; Asyhar, A. H.

    2018-01-01

    The average achievement of Indonesian students’ mathematics skills according to Benchmark International Trends in Mathematics and Science Study (TIMSS) is ranked at the 38th out of 42 countries and according to the survey result in Program for International Student Assessment (PISA) is ranked at the 64th out of 65 countries. The low mathematics skill of Indonesian student has become an important reason to research more deeply about reasoning and algebra in mathematics. Analogical reasoning is a very important component in mathematics because it is the key to creativity and it can make the learning process in the classroom become effective. The major part of the analogical reasoning is about structuring including the processes of inferencing and decision-making happens. Those processes involve base domain and target domain. Methodologically, the subjects of this research were 42 students from class XII. The sources of data were derived from the results of thinks aloud, the transcribed interviews, and the videos taken while the subject working on the instruments and interviews. The collected data were analyzed using qualitative techniques. The result of this study described the structuring characteristics of students’ analogical reasoning in solving algebra problems from all the research subjects.

  16. The future demand for and structural problems of Japanese Radiotherapy

    International Nuclear Information System (INIS)

    Imai, Atsushi; Inoue, Toshihiko; Teshima, Teruki; Ohno, Yuko; Yamashita, Takashi; Mitsuhashi, Norio; Hiraoka, Masahiro; Sumi, Minako

    2001-01-01

    Recently, as the number of elderly people in Japan is growing, so is the number of new cancer cases. The number of patients treated with radiotherapy is therefore also on the increase, so that it is important to estimate the future demand for radiotherapy and to make preparations for it. All the surveys were conducted for 106 facilities selected randomly out of 556 radiotherapy facilities in Japan. To obtain trends in the number of new cancer patients treated with radiotherapy in Japan, we conducted a survey with a self-administered mail questionnaire designed to obtain the number of new patients treated with radiotherapy for each year of the past decade (1990-99). The future number of new patients treated with radiotherapy was estimated from the data thus obtained. To investigate structural problems of Japanese radiotherapy, surveys about the number of treatment machines and full-time equivalent (FTE) radiation oncologists were conducted according to data from the Japanese Society for Therapeutic Radiology and Oncology (JASTRO) structure survey and the Patterns of Care Study (PCS). We also compared the structure of Japanese radiotherapy with that in the USA. The number of patients treated with radiotherapy has increased for every institutional stratum, with an overall increase of 1.4-fold over the past 10 years in Japan. It is estimated that the number of cancer patients treated with radiotherapy will reach 190000 in 2015. In Japanese non-academic institutions, less than one FTE radiation oncologist has been managing many of these patients. In both equipment and manpower, academic institutions exceed non-academic institutions. The future demand for Japanese radiotherapy will grow substantially, so that it is of vital importance to prepare for it. Specifically, the number of FTE radiation oncologists must be increased. (author)

  17. Research Projects in Physics: A Mechanism for Teaching Ill-Structured Problem Solving

    Science.gov (United States)

    Milbourne, Jeff; Bennett, Jonathan

    2017-10-01

    Physics education research has a tradition of studying problem solving, exploring themes such as physical intuition and differences between expert and novice problem solvers. However, most of this work has focused on traditional, or well-structured, problems, similar to what might appear in a textbook. Less work has been done with open-ended, or ill-structured, problems, similar to the types of problems students might face in their professional lives. Given the national discourse on educational system reform aligned with 21st century skills, including problem solving, it is critical to provide educational experiences that help students learn to solve all types of problems, including ill-structured problems.

  18. NASA Langley's Approach to the Sandia's Structural Dynamics Challenge Problem

    Science.gov (United States)

    Horta, Lucas G.; Kenny, Sean P.; Crespo, Luis G.; Elliott, Kenny B.

    2007-01-01

    The objective of this challenge is to develop a data-based probabilistic model of uncertainty to predict the behavior of subsystems (payloads) by themselves and while coupled to a primary (target) system. Although this type of analysis is routinely performed and representative of issues faced in real-world system design and integration, there are still several key technical challenges that must be addressed when analyzing uncertain interconnected systems. For example, one key technical challenge is related to the fact that there is limited data on target configurations. Moreover, it is typical to have multiple data sets from experiments conducted at the subsystem level, but often samples sizes are not sufficient to compute high confidence statistics. In this challenge problem additional constraints are placed as ground rules for the participants. One such rule is that mathematical models of the subsystem are limited to linear approximations of the nonlinear physics of the problem at hand. Also, participants are constrained to use these models and the multiple data sets to make predictions about the target system response under completely different input conditions. Our approach involved initially the screening of several different methods. Three of the ones considered are presented herein. The first one is based on the transformation of the modal data to an orthogonal space where the mean and covariance of the data are matched by the model. The other two approaches worked solutions in physical space where the uncertain parameter set is made of masses, stiffnesses and damping coefficients; one matches confidence intervals of low order moments of the statistics via optimization while the second one uses a Kernel density estimation approach. The paper will touch on all the approaches, lessons learned, validation 1 metrics and their comparison, data quantity restriction, and assumptions/limitations of each approach. Keywords: Probabilistic modeling, model validation

  19. Factors limiting the operation of structures under high gradient

    International Nuclear Information System (INIS)

    Schriber, S.O.

    1986-01-01

    Factors limiting the operation of rf structures under high-gradient conditions are described. Included are recent rf measurements at laboratories in Europe, Asia, and North America and how these measurements relate to earlier data as exemplified by the use of the Kilpatrick criterion (Kp). Operation limitations will cover mechanical, geometry, thermal, and surface constraints and the associated impact on structure design, fabrication, and material selection. Generally, structures operating continuous wave (100% duty factor) appear to be limited to peak surface fields at about twice the Kilpatrick limit, whereas pulsed structures operating with pulse lengths less than a millisecond can attain peak surface fields five times the Kilpatrick limit

  20. Detangling the Interrelationships between Self- Regulation and Ill-Structured Problem Solving in Problem-Based Learning

    Science.gov (United States)

    Ge, Xun; Law, Victor; Huang, Kun

    2016-01-01

    One of the goals for problem-based learning (PBL) is to promote self-regulation. Although self-regulation has been studied extensively, its interrelationships with ill-structured problem solving have been unclear. In order to clarify the interrelationships, this article proposes a conceptual framework illustrating the iterative processes among…

  1. On Advice Complexity of the k-server Problem under Sparse Metrics

    DEFF Research Database (Denmark)

    Gupta, S.; Kamali, S.; López-Ortiz, A.

    2013-01-01

    We consider the k-Server problem under the advice model of computation when the underlying metric space is sparse. On one side, we introduce Θ (1)-competitive algorithms for a wide range of sparse graphs, which require advice of (almost) linear size. Namely, we show that for graphs of size N...... for the 2-server problem on a path metric of size N ≥ 5. Through another lower bound argument, we show that at least n/2 (log α - 1.22) bits of advice is required to obtain an optimal solution for metric spaces of treewidth α, where 4 ≤ α

  2. Optimal Shakedown of the Thin-Wall Metal Structures Under Strength and Stiffness Constraints

    Directory of Open Access Journals (Sweden)

    Alawdin Piotr

    2017-06-01

    Full Text Available Classical optimization problems of metal structures confined mainly with 1st class cross-sections. But in practice it is common to use the cross-sections of higher classes. In this paper, a new mathematical model for described shakedown optimization problem for metal structures, which elements are designed from 1st to 4th class cross-sections, under variable quasi-static loads is presented. The features of limited plastic redistribution of forces in the structure with thin-walled elements there are taken into account. Authors assume the elastic-plastic flexural buckling in one plane without lateral torsional buckling behavior of members. Design formulae for Methods 1 and 2 for members are analyzed. Structures stiffness constrains are also incorporated in order to satisfy the limit serviceability state requirements. With the help of mathematical programming theory and extreme principles the structure optimization algorithm is developed and justified with the numerical experiment for the metal plane frames.

  3. The Lunar Internal Structure Model: Problems and Solutions

    Science.gov (United States)

    Nefedyev, Yuri; Gusev, Alexander; Petrova, Natalia; Varaksina, Natalia

    The report is devoted the problems of the internal structure and gravitational field of the Moon. New data received from 14 newest instruments installed on low-orbit satellite Kaguya essentially enriched our knowledge of the Moon. Chinese satellite ChagE-1 and Indian Chandrayan-1 have demonstrated strong potential of China and India in the field of lunar research and obtained new data on gravitational field, mascons, crust, and geochemical composition of the circumlunar space. Internal structure of the Moon: There are some essential arguments in favor of existence of a small-sized Moon’s core made of metallic iron alloyed with a small amount of sulfur and/or oxygen, and availability of hot viscous lower mantle. Structure of gravitational field of the Moon, determined by the comparison of high-precision trajectory measurements by Lunar Prospector (1998- 1999) with the results of laser altimetry obtained by Clementine (1994), as well as with data sets of laser ranging of the Moon (1970-2006), assumes the presence of a metal core. Interpretation of the polar moment value within the framework of chemical, thermal and density models of lunar crust and mantle informed conclusions about the weight and size of the core. LLR analysis of dissipation of rotation of the Moon points at two possible sources of dissipation: monthly solid-state inflows and liquid core, rotation of which differs from viscous-elastic mantle. Liquid (melted) core has its unique impact on the Moon’s rotation. In particular, there are two force moments due to topographical and phase interaction at the boundary between liquid core and elastic mantle (CMB). Liquid core can rotate independently from solid mantle Selenoid satellites (SS) open new and most perspective opportunities in the study of gravitational field and the Moon’s figure. SSs “Moon 10”, “Apollo”, “Clementine”, “Lunar Prospector” trajectory tracking data processing has allowed for identification of coefficients in

  4. Homotopy Method for a General Multiobjective Programming Problem under Generalized Quasinormal Cone Condition

    Directory of Open Access Journals (Sweden)

    X. Zhao

    2012-01-01

    Full Text Available A combined interior point homotopy continuation method is proposed for solving general multiobjective programming problem. We prove the existence and convergence of a smooth homotopy path from almost any interior initial interior point to a solution of the KKT system under some basic assumptions.

  5. Health Problems of the Under-Five Children in an Urban Slum in ...

    African Journals Online (AJOL)

    Objective: To determine the health problems common among under-five children in a typical urban slum in Nigeria and assess the treatment patterns commonly offered to these children. Methods: A community-based, cross-sectional survey was conducted in May-July 2010. A cluster sampling technique was used to select ...

  6. On the Structure of the Fixed Charge Transportation Problem

    Science.gov (United States)

    Kowalski, K.

    2005-01-01

    This work extends the theory of the fixed charge transportation problem (FCTP), currently based mostly on a forty-year-old publication by Hirsch and Danzig. This paper presents novel properties that need to be considered by those using existing, or those developing new methods for optimizing FCTP. It also defines the problem in an easier way,…

  7. Topology optimization of fluid-structure-interaction problems in poroelasticity

    DEFF Research Database (Denmark)

    Andreasen, Casper Schousboe; Sigmund, Ole

    2013-01-01

    with the deformation of the elastic skeleton through a macroscopic Darcy-type flow law. The method allows to impose pressure loads for static problems through a one way coupling, while transient problems are fully coupled modeling the interaction between fluid and solid. The material distribution is determined...

  8. Influence of Number Size, Problem Structure and Response Mode on Children's Solutions of Multiplication Word Problems.

    Science.gov (United States)

    De Corte, E.; And Others

    One important finding from recent research on multiplication word problems is that children's performances are strongly affected by the nature of the multiplier (whether it is an integer, decimal larger than 1 or a decimal smaller than 1). On the other hand, the size of the multiplicand has little or no effect on problem difficulty. The aim of the…

  9. Locally self-consistent Green’s function approach to the electronic structure problem

    DEFF Research Database (Denmark)

    Abrikosov, I.A.; Simak, S.I.; Johansson, B.

    1997-01-01

    The locally self-consistent Green's function (LSGF) method is an order-N method for calculation of the electronic structure of systems with an arbitrary distribution of atoms of different kinds on an underlying crystal lattice. For each atom Dyson's equation is used to solve the electronic multiple...... scattering problem in a local interaction zone (LIZ) embedded in an effective medium judiciously chosen to minimize the size of the, LIZ. The excellent real-space convergence of the LSGF calculations and the reliability of its results are demonstrated for a broad spectrum of metallic alloys with different...

  10. The Parity of Set Systems under Random Restrictions with Applications to Exponential Time Problems

    DEFF Research Database (Denmark)

    Björklund, Andreas; Dell, Holger; Husfeldt, Thore

    2015-01-01

    We reduce the problem of detecting the existence of an object to the problem of computing the parity of the number of objects in question. In particular, when given any non-empty set system, we prove that randomly restricting elements of its ground set makes the size of the restricted set system...... an odd number with significant probability. When compared to previously known reductions of this type, ours excel in their simplicity: For graph problems, restricting elements of the ground set usually corresponds to simple deletion and contraction operations, which can be encoded efficiently in most...... and Husfeldt (FOCS 2013) that computes the parity of the number of Hamiltonian cycles in time 1.619^n. 2. A new result in the framework of Cygan et al. (CCC 2012) for analyzing the complexity of NP-hard problems under the Strong Exponential Time Hypothesis: If the parity of the number of Set Covers can...

  11. Mathematical Abstraction in the Solving of Ill-Structured Problems by Elementary School Students in Korea

    Science.gov (United States)

    Hong, Jee Yun; Kim, Min Kyeong

    2016-01-01

    Ill-structured problems can be regarded as one of the measures that meet recent social needs emphasizing students' abilities to solve real-life problems. This study aimed to analyze the mathematical abstraction process in solving such problems, and to identify the mathematical abstraction level ([I] Recognition of mathematical structure through…

  12. Characterizing Thematized Derivative Schema by the Underlying Emergent Structures

    Science.gov (United States)

    Garcia, Mercedes; Llinares, Salvador; Sanchez-Matamoros, Gloria

    2011-01-01

    This paper reports on different underlying structures of the derivative schema of three undergraduate students that were considered to be at the trans level of development of the derivative schema (action-process-object-schema). The derivative schema is characterized in terms of the students' ability to explicitly transfer the relationship between…

  13. Colloidal hard dumbbells under gravity: structure and crystallization

    NARCIS (Netherlands)

    Marechal, M.A.T.; Dijkstra, M.

    2011-01-01

    We study the structure and phase behavior of hard dumbbells under gravity. The fluid shows layering near the wall, where subsequent layers of dumbbells align alternatingly parallel or perpendicular to the wall. We observe coexistence of a fluid with a plastic crystal (PC) and an aligned crystal

  14. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2009-01-01

    Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...

  15. The Fatigue Behavior of Steel Structures under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning

    2008-01-01

    Fatigue damage accumulation in steel structures under random loading has been studied in a number of investigations at the Technical University of Denmark. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part...

  16. Structural composite panel performance under long-term load

    Science.gov (United States)

    Theodore L. Laufenberg

    1988-01-01

    Information on the performance of wood-based structural composite panels under long-term load is currently needed to permit their use in engineered assemblies and systems. A broad assessment of the time-dependent properties of panels is critical for creating databases and models of the creep-rupture phenomenon that lead to reliability-based design procedures. This...

  17. On the latent structure of problem gambling: a taxometric analysis.

    Science.gov (United States)

    James, Richard J E; O'Malley, Claire; Tunney, Richard J

    2014-10-01

    To test whether problem gambling is a categorical or dimensional disorder on the basis of two problem gambling assessments. This distinction discriminates between two different conceptualizations of problem gambling: one that problem gambling is defined by its addictive properties, the other that it is a continuum of harm. Using The British Gambling Prevalence Survey 2010, a nationally representative sample of the United Kingdom conducted by the National Centre for Social Research, five different taxometric analyses were carried out on cases from two problem gambling screens: the Problem Gambling Severity Index (PGSI) and a measure derived from the DSM-IV Pathological Gambling criteria. Two further analyses were conducted on the total scores for these measures. There was strong evidence that both scales were measuring a categorical construct. Fit indices consistently supported a categorical interpretation [comparison curve fit index (CCFI) > 0.6]. The PGSI analysis indicated the presence of a taxon (CCFIs = 0.633, 0.756). The analysis conducted on the adapted DSM-IV criteria indicated stronger quantitative support for a taxon (CCFIs = 0.717, 0.811 and 0.756) but items probing a loss of control were inconsistent. The taxometric analyses of both scales support a categorical interpretation (CCFIs = 0.628, 0.567), but extreme caution should be used due to high nuisance covariance. Two problem gambling screens (the Problem Gambling Severity Index and a measure derived from the DSM-IV Pathological Gambling criteria) appear to measure a categorical construct that taps into a categorical, loss of control model of problem gambling. There is some evidence that the two screens measure different aspects of an addiction construct. © 2014 Society for the Study of Addiction.

  18. A regularized matrix factorization approach to induce structured sparse-low-rank solutions in the EEG inverse problem

    DEFF Research Database (Denmark)

    Montoya-Martinez, Jair; Artes-Rodriguez, Antonio; Pontil, Massimiliano

    2014-01-01

    We consider the estimation of the Brain Electrical Sources (BES) matrix from noisy electroencephalographic (EEG) measurements, commonly named as the EEG inverse problem. We propose a new method to induce neurophysiological meaningful solutions, which takes into account the smoothness, structured...... matrix and the squared Frobenius norm of the latent source matrix. We develop an alternating optimization algorithm to solve the resulting nonsmooth-nonconvex minimization problem. We analyze the convergence of the optimization procedure, and we compare, under different synthetic scenarios...

  19. Features for Exploiting Black-Box Optimization Problem Structure

    DEFF Research Database (Denmark)

    Tierney, Kevin; Malitsky, Yuri; Abell, Tinus

    2013-01-01

    Black-box optimization (BBO) problems arise in numerous scientic and engineering applications and are characterized by compu- tationally intensive objective functions, which severely limit the number of evaluations that can be performed. We present a robust set of features that analyze the tness...... landscape of BBO problems and show how an algorithm portfolio approach can exploit these general, problem indepen- dent features and outperform the utilization of any single minimization search strategy. We test our methodology on data from the GECCO Workshop on BBO Benchmarking 2012, which contains 21...

  20. Propagation of uncertainties in problems of structural reliability

    International Nuclear Information System (INIS)

    Mazumdar, M.; Marshall, J.A.; Chay, S.C.

    1978-01-01

    The problem of controlling a variable Y such that the probability of its exceeding a specified design limit L is very small, is treated. This variable is related to a set of random variables Xsub(i) by means of a known function Y=f(Xsub(i)). The following approximate methods are considered for estimating the propagation of error in the Xsub(i)'s through the function f(-): linearization; method of moments; Monte Carlo methods; numerical integration. Response surface and associated design of experiments problems as well as statistical inference problems are discussed. (Auth.)

  1. Antibody Modeling and Structure Analysis. Application to biomedical problems.

    OpenAIRE

    Chailyan, Anna

    2013-01-01

    Background The usefulness of antibodies and antibody derived artificial constructs in various medical and biochemical applications has made them a prime target for protein engineering, modelling, and structure analysis. The huge number of known antibody sequences, that far outpaces the number of solved structures, raises the need for reliable automatic methods of antibody structure prediction. Antibodies have a very characteristic molecular structure that is reflected in their modelli...

  2. Design of mild steel structures under unequal cyclic loads

    International Nuclear Information System (INIS)

    In this paper a method is proposed to investigate the behavior and life of structural components under unequal cyclic loading conditions. Appropriate cyclic moment-curvature relations and life information, in the form of life versus extreme fiber strain, are developed from tests on beams under pure bending conditions. Theoretical predictions of behavior are based on structural geometry and the cyclic moment-curvature relations used in association with the simple curvature-area method. Structural life is also predicted using the life information developed and the theoretical strain history at the critical section in conjunction with a linear damage summation criterion. Theoretical predictions of behavior and life compare reasonably well with the experiments. Based on this study, a design procedure is proposed for mild steel components subjected to unequal cyclic loading conditions. The loads on the tested components were such that they failed due to low cyclic fatigue (i.e., at less than 10 5 cycles)

  3. The Role of Content Knowledge in Ill-Structured Problem Solving for High School Physics Students

    Science.gov (United States)

    Milbourne, Jeff; Wiebe, Eric

    2018-01-01

    While Physics Education Research has a rich tradition of problem-solving scholarship, most of the work has focused on more traditional, well-defined problems. Less work has been done with ill-structured problems, problems that are better aligned with the engineering and design-based scenarios promoted by the Next Generation Science Standards. This…

  4. A novel modeling approach for job shop scheduling problem under uncertainty

    Directory of Open Access Journals (Sweden)

    Behnam Beheshti Pur

    2013-11-01

    Full Text Available When aiming on improving efficiency and reducing cost in manufacturing environments, production scheduling can play an important role. Although a common workshop is full of uncertainties, when using mathematical programs researchers have mainly focused on deterministic problems. After briefly reviewing and discussing popular modeling approaches in the field of stochastic programming, this paper proposes a new approach based on utility theory for a certain range of problems and under some practical assumptions. Expected utility programming, as the proposed approach, will be compared with the other well-known methods and its meaningfulness and usefulness will be illustrated via a numerical examples and a real case.

  5. Modulation of endothelial glycocalyx structure under inflammatory conditions.

    Science.gov (United States)

    Kolářová, Hana; Ambrůzová, Barbora; Svihálková Šindlerová, Lenka; Klinke, Anna; Kubala, Lukáš

    2014-01-01

    The glycocalyx of the endothelium is an intravascular compartment that creates a barrier between circulating blood and the vessel wall. The glycocalyx is suggested to play an important role in numerous physiological processes including the regulation of vascular permeability, the prevention of the margination of blood cells to the vessel wall, and the transmission of shear stress. Various theoretical models and experimental approaches provide data about changes to the structure and functions of the glycocalyx under various types of inflammatory conditions. These alterations are suggested to promote inflammatory processes in vessels and contribute to the pathogenesis of number of diseases. In this review we summarize current knowledge about the modulation of the glycocalyx under inflammatory conditions and the consequences for the course of inflammation in vessels. The structure and functions of endothelial glycocalyx are briefly discussed in the context of methodological approaches regarding the determination of endothelial glycocalyx and the uncertainty and challenges involved in glycocalyx structure determination. In addition, the modulation of glycocalyx structure under inflammatory conditions and the possible consequences for pathogenesis of selected diseases and medical conditions (in particular, diabetes, atherosclerosis, ischemia/reperfusion, and sepsis) are summarized. Finally, therapeutic strategies to ameliorate glycocalyx dysfunction suggested by various authors are discussed.

  6. Modulation of Endothelial Glycocalyx Structure under Inflammatory Conditions

    Directory of Open Access Journals (Sweden)

    Hana Kolářová

    2014-01-01

    Full Text Available The glycocalyx of the endothelium is an intravascular compartment that creates a barrier between circulating blood and the vessel wall. The glycocalyx is suggested to play an important role in numerous physiological processes including the regulation of vascular permeability, the prevention of the margination of blood cells to the vessel wall, and the transmission of shear stress. Various theoretical models and experimental approaches provide data about changes to the structure and functions of the glycocalyx under various types of inflammatory conditions. These alterations are suggested to promote inflammatory processes in vessels and contribute to the pathogenesis of number of diseases. In this review we summarize current knowledge about the modulation of the glycocalyx under inflammatory conditions and the consequences for the course of inflammation in vessels. The structure and functions of endothelial glycocalyx are briefly discussed in the context of methodological approaches regarding the determination of endothelial glycocalyx and the uncertainty and challenges involved in glycocalyx structure determination. In addition, the modulation of glycocalyx structure under inflammatory conditions and the possible consequences for pathogenesis of selected diseases and medical conditions (in particular, diabetes, atherosclerosis, ischemia/reperfusion, and sepsis are summarized. Finally, therapeutic strategies to ameliorate glycocalyx dysfunction suggested by various authors are discussed.

  7. Low parental tolerance for infant crying: an underlying factor in infant sleep problems?

    Science.gov (United States)

    Sadeh, Avi; Juda-Hanael, Michal; Livne-Karp, Efrat; Kahn, Michal; Tikotzky, Liat; Anders, Thomas F; Calkins, Susan; Sivan, Yakov

    2016-10-01

    Parenting behaviours play a major role in the evolution of infant sleep. Sleep problems in infancy have been associated with excessive parental involvement at night-time, and with shorter delays in response to infant night wakings and signalling. Infant crying and sleep problems are linked, yet little is known about the impact of parental responses to crying on infant sleep patterns. This study examined the hypothesis that lower parental tolerance for crying is associated with infant sleep problems. We studied 144 married couples divided into three groups: parents of infants suffering from night-waking problems (i.e. the clinical group), parents of infants without sleep problems and childless couples. Crying tolerance was assessed using questionnaires, audio recordings of crying infants and using a novel paradigm, in which participants were shown a video of a crying infant and asked when they would intervene. Parents in the clinical group demonstrated shorter intervention delays in the crying infant clip (group effect: P sleep-disturbed infants appear to have lower tolerance for infant crying, which may be a predisposition underlying their excessive involvement in soothing their infants to sleep which may lead to the development of sleep problems. These preliminary findings should be explored further to assess their clinical validity and utility. © 2016 European Sleep Research Society.

  8. Safety margins of containment structures under impulsive loading

    International Nuclear Information System (INIS)

    Lu, S.C.H.

    1978-01-01

    Containment structures for nuclear power plants are designed to a large extent to satisfy the various stress limits specified by ASME Boiler and Pressure Vessel Code. For short-duration impulsive loads, the common practice of meeting the Code stress limits based on a quasi-static approach is a poor measure of the reserve load-carrying capacity of a structure and always results in a conservative design with a greater than desired margin of safety. There are situations, however, where one might wish to quantify this additional conservatism to avoid excessive or unnecessary field modification. Typical examples were found in re-evaluation studies of MARK I Boiling Water Reactor containment structures under the hydrodynamic loads expected during a postulated loss-of-coolant accident. The paper is based on the results of a plane strain, large displacement, elastic-plastic, finite-element analysis of a thin cylindrical shell subjected to external pressure pulses. An analytical procedure is presented for estimating the ultimate load capacity of the thin shell structure and, subsequently, for quantifying the design margins of safety for the type of loads under consideration. For defining failure of structures, a finite strain failure criterion is derived that accounts for multiaxiality effects

  9. Effect of support conditions on structural response under dynamic loading

    International Nuclear Information System (INIS)

    Akram, T.; Memon, S.A.

    2008-01-01

    In design practice, dynamic structural analysis is carried out with base of structure considered as fixed; this means that foundation is placed on rock like soil material. While conducting this type of analyses the role of foundation and soil behaviour is totally neglected. The actions in members and loads transferred at foundation level obtained in this manner do not depict the true structural behaviour. FEM (Finite Element Methods) analysis where both superstructure and foundation soil are coupled together is quite complicated and expensive for design environments. A simplified model is required to depict dynamic response of structures with foundations based on flexible soils. The primary purpose of this research is to compare the superstructure dynamic responses of structural systems with fixed base to that of simple soil model base. The selected simple soil model is to be suitable for use in a design environment to give more realistic results. For this purpose building models are idealized with various heights and structural systems in both 2D (Two Dimensional) and 3D (Three Dimensional) space. These models are then provided with visco-elastic supports representing three soil bearing capacities and the analysis results are compared to that of fixed supports models. The results indicate that fixed support system underestimates natural time period of the structures. Dynamic behavior and force response of visco-elastic support is different from fixed support model. Fixed support models result in over designed base columns and under designed beams. (author)

  10. Generalized Minimum Variance Control for MDOF Structures under Earthquake Excitation

    Directory of Open Access Journals (Sweden)

    Lakhdar Guenfaf

    2016-01-01

    Full Text Available Control of a multi-degree-of-freedom structural system under earthquake excitation is investigated in this paper. The control approach based on the Generalized Minimum Variance (GMV algorithm is developed and presented. Our approach is a generalization to multivariable systems of the GMV strategy designed initially for single-input-single-output (SISO systems. Kanai-Tajimi and Clough-Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method.

  11. Applied problems of the identification and regression analysis in stochastic structures with multimodal properties

    Directory of Open Access Journals (Sweden)

    Kulikov Vladimir

    2016-01-01

    Full Text Available We have been elaborating an approach founded on the identification of multimodal laws of the complex structure distribution in medicine, biology, chemistry of ultrapure materials and membrane technology as well as in technical applications. The method is based on the formulation and solution of inverse problems in mathematical physics for the respective probability density functions. The verification of the used algorithmic tools is carried out on model limited-scope samples. For stochastic structures and systems under study the method is supplemented with an original option of a regression analysis taking into account the identified stochastic laws displaying numerical parameters into the binary space. The proposed approach has been tested on clinical material in practical medicine.

  12. Heuristics for the Economic Production Quantity Problem under Restrictions on Production and Maintenance Time

    Directory of Open Access Journals (Sweden)

    Qi Xu

    2016-01-01

    Full Text Available This paper proposes an economic production quantity problem with the maximal production run time and minimal preventive maintenance time over a finite planning horizon. The objective is to find the efficient production and maintenance policy to minimize the total cost composed of production, maintenance, shortages, and holding costs under the restriction on the production run time and the preventive maintenance time. The production and maintenance decisions include the production and maintenance frequencies and the production run and the maintenance time. The variability and the boundedness of the production run and maintenance time make the problem difficult to solve. Two heuristic algorithms are developed using different techniques based on the optimal properties of the relaxed problem. The performance comparison between the two algorithms is illustrated by numerical examples. The numerical results show that, for the most part, there exists a heuristic algorithm which is more effective than the other.

  13. Dynamic Network Design Problem under Demand Uncertainty: An Adjustable Robust Optimization Approach

    Directory of Open Access Journals (Sweden)

    Hua Sun

    2014-01-01

    Full Text Available This paper develops an adjustable robust optimization approach for a network design problem explicitly incorporating traffic dynamics and demand uncertainty. In particular, a cell transmission model based network design problem of linear programming type is considered to describe dynamic traffic flows, and a polyhedral uncertainty set is used to characterize the demand uncertainty. The major contribution of this paper is to formulate such an adjustable robust network design problem as a tractable linear programming model and justify the model which is less conservative by comparing its solution performance with the robust solution from the usual robust model. The numerical results using one network from the literature demonstrate the modeling advantage of the adjustable robust optimization and provided strategic managerial insights for enacting capacity expansion policies under demand uncertainty.

  14. The solution of location problems with certain existing facility structures

    DEFF Research Database (Denmark)

    Juel, Henrik; Love, Robert F.

    1983-01-01

    It is known that in the Euclidean distance case, the optimal minisum location of a new facility in relation to four existing facilities is at the intersection of the two lines joining two pairs of the facilities. The authors extend this concept to minisum problems having any even number of existing...

  15. Structured pigeonhole principle, search problems and hard tautologies

    Czech Academy of Sciences Publication Activity Database

    Krajíček, Jan

    2005-01-01

    Roč. 70, č. 2 (2005), s. 619-630 ISSN 0022-4812 R&D Projects: GA AV ČR(CZ) IAA1019401; GA MŠk(CZ) LN00A056 Institutional research plan: CEZ:AV0Z10190503 Keywords : proof complexity * pigeonhole principle * serch problems Subject RIV: BA - General Mathematics Impact factor: 0.470, year: 2005

  16. solution of confined seepage problems below hydraulic structures ...

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... profiles of complicated boundary forms. The numerical results obtained are compared with those from experimental and other methods. 1. INTRODUCTION. The study of flow through porous media has a wide range of applications in many facets of water resources management. The problem of confined.

  17. Generalized transmission line method to study the far-zone radiation of antennas under a multilayer structure

    CERN Document Server

    Wu, Xuan Hui

    2008-01-01

    This book gives a step-by-step presentation of a generalized transmission line method to study the far-zone radiation of antennas under a multilayer structure. Normally, a radiation problem requires a full wave analysis which may be time consuming. The beauty of the generalized transmission line method is that it transforms the radiation problem for a specific type of structure, say the multilayer structure excited by an antenna, into a circuit problem that can be efficiently analyzed. Using the Reciprocity Theorem and far-field approximation, the method computes the far-zone radiation due to

  18. Structural Evaluation on HIC Transport Packaging under Accident Conditions

    International Nuclear Information System (INIS)

    Chung, Sung Hwan; Kim, Duck Hoi; Jung, Jin Se; Yang, Ke Hyung; Lee, Heung Young

    2005-01-01

    HIC transport packaging to transport a high integrity container(HIC) containing dry spent resin generated from nuclear power plants is to comply with the regulatory requirements of Korea and IAEA for Type B packaging due to the high radioactivity of the content, and to maintain the structural integrity under normal and accident conditions. It must withstand 9 m free drop impact onto an unyielding surface and 1 m drop impact onto a mild steel bar in a position causing maximum damage. For the conceptual design of a cylindrical HIC transport package, three dimensional dynamic structural analysis to ensure that the integrity of the package is maintained under all credible loads for 9 m free drop and 1 m puncture conditions were carried out using ABAQUS code.

  19. Structural optimization under overhang constraints imposed by additive manufacturing technologies

    Science.gov (United States)

    Allaire, G.; Dapogny, C.; Estevez, R.; Faure, A.; Michailidis, G.

    2017-12-01

    This article addresses one of the major constraints imposed by additive manufacturing processes on shape optimization problems - that of overhangs, i.e. large regions hanging over void without sufficient support from the lower structure. After revisiting the 'classical' geometric criteria used in the literature, based on the angle between the structural boundary and the build direction, we propose a new mechanical constraint functional, which mimics the layer by layer construction process featured by additive manufacturing technologies, and thereby appeals to the physical origin of the difficulties caused by overhangs. This constraint, as well as some variants, is precisely defined; their shape derivatives are computed in the sense of Hadamard's method, and numerical strategies are extensively discussed, in two and three space dimensions, to efficiently deal with the appearance of overhang features in the course of shape optimization processes.

  20. Optimal Tuned Mass Damper for Nonlinear Structure under Different Earthquakes

    Directory of Open Access Journals (Sweden)

    K. Shakeri

    2015-07-01

    Full Text Available Since there is no closed-form formula for designing TMD (Tuned Mass Damper for nonlinear structures, some researchers have proposed numerical optimization procedures such as a genetic algorithm to obtain the optimal values of TMD parameters for nonlinear structures. These methods are based on determining the optimal values of TMD parameters to minimize the maximum response (e.g. inter story drift of the controlled structure subjected to a specific earthquake record. Therefore, the performance of TMD that has been designed using a specific record strongly depends on the characteristics of the earthquake record. By changing the characteristics of the input earthquake record, the efficiency of TMD is changed and in some cases, it is possible that the response of the controlled structure is increased. To overcome the shortcomings of the previous researches, in this paper, an efficient method for designing optimal TMD on nonlinear structures is proposed, in which the effect of different ground motion records is considered in the design procedure. In the proposed method, the optimal value of the TMD parameters are determined so that the average maximum response (e.g. inter story drift resulting from different records in the controlled structure is minimized. To illustrate the procedure of the propose method, the method is used to design optimal TMD for a sample structure. The results of numerical simulations show that the average maximum response of controlled structure resulting from different records is reduced significantly. Hence, it can be concluded that the proposed method for designing optimal TMD under different earthquakes is effective.

  1. Crystalline structures of poly(L-lactide) formed under pressure and structure transitions with heating

    DEFF Research Database (Denmark)

    Huang, Shaoyong; Li, Hongfei; Yu, Donghong

    2013-01-01

    The isothermally crystallized poly(L-lactide) (PLLA) samples were obtained at 135 °C under pressures (Pc) ranging from 1 bar to 2.5 kbar. The crystalline structures, the structure transition, and thermal properties of the prepared samples were investigated by wide-angle X-ray diffraction (WAXD...

  2. Utilizing Problem Structure in Optimization of Radiation Therapy

    International Nuclear Information System (INIS)

    Carlsson, Fredrik

    2008-04-01

    In this thesis, optimization approaches for intensity-modulated radiation therapy are developed and evaluated with focus on numerical efficiency and treatment delivery aspects. The first two papers deal with strategies for solving fluence map optimization problems efficiently while avoiding solutions with jagged fluence profiles. The last two papers concern optimization of step-and-shoot parameters with emphasis on generating treatment plans that can be delivered efficiently and accurately. In the first paper, the problem dimension of a fluence map optimization problem is reduced through a spectral decomposition of the Hessian of the objective function. The weights of the eigenvectors corresponding to the p largest eigenvalues are introduced as optimization variables, and the impact on the solution of varying p is studied. Including only a few eigenvector weights results in faster initial decrease of the objective value, but with an inferior solution, compared to optimization of the bixel weights. An approach combining eigenvector weights and bixel weights produces improved solutions, but at the expense of the pre-computational time for the spectral decomposition. So-called iterative regularization is performed on fluence map optimization problems in the second paper. The idea is to find regular solutions by utilizing an optimization method that is able to find near-optimal solutions with non-jagged fluence profiles in few iterations. The suitability of a quasi-Newton sequential quadratic programming method is demonstrated by comparing the treatment quality of deliverable step-and-shoot plans, generated through leaf sequencing with a fixed number of segments, for different number of bixel-weight iterations. A conclusion is that over-optimization of the fluence map optimization problem prior to leaf sequencing should be avoided. An approach for dynamically generating multileaf collimator segments using a column generation approach combined with optimization of

  3. Fusion proteins as alternate crystallization paths to difficult structure problems

    Science.gov (United States)

    Carter, Daniel C.; Rueker, Florian; Ho, Joseph X.; Lim, Kap; Keeling, Kim; Gilliland, Gary; Ji, Xinhua

    1994-01-01

    The three-dimensional structure of a peptide fusion product with glutathione transferase from Schistosoma japonicum (SjGST) has been solved by crystallographic methods to 2.5 A resolution. Peptides or proteins can be fused to SjGST and expressed in a plasmid for rapid synthesis in Escherichia coli. Fusion proteins created by this commercial method can be purified rapidly by chromatography on immobilized glutathione. The potential utility of using SjGST fusion proteins as alternate paths to the crystallization and structure determination of proteins is demonstrated.

  4. Denaturation of collagen structures and their transformation under the physical and chemical effects

    Science.gov (United States)

    Ivankin, A.; Boldirev, V.; Fadeev, G.; Baburina, M.; Kulikovskii, A.; Vostrikova, N.

    2017-11-01

    The process of denaturation of collagen structures under the influence of physical and chemical factors play an important role in the manufacture of food technology and the production of drugs for medicine and cosmetology. The paper discussed the problem of the combined effects of heat treatment, mechanical dispersion and ultrasonic action on the structural changes of the animal collagen in the presence of weak protonated organic acids. Algorithm combined effects of physical and chemical factors as a result of the formation of the technological properties of products containing collagen has been shown.

  5. Parallel Evolution of Chromatin Structure Underlying Metabolic Adaptation.

    Science.gov (United States)

    Cheng, Jian; Guo, Xiaoxian; Cai, Pengli; Cheng, Xiaozhi; Piškur, Jure; Ma, Yanhe; Jiang, Huifeng; Gu, Zhenglong

    2017-11-01

    Parallel evolution occurs when a similar trait emerges in independent evolutionary lineages. Although changes in protein coding and gene transcription have been investigated as underlying mechanisms for parallel evolution, parallel changes in chromatin structure have never been reported. Here, Saccharomyces cerevisiae and a distantly related yeast species, Dekkera bruxellensis, are investigated because both species have independently evolved the capacity of aerobic fermentation. By profiling and comparing genome sequences, transcriptomic landscapes, and chromatin structures, we revealed that parallel changes in nucleosome occupancy in the promoter regions of mitochondria-localized genes led to concerted suppression of mitochondrial functions by glucose, which can explain the metabolic convergence in these two independent yeast species. Further investigation indicated that similar mutational processes in the promoter regions of these genes in the two independent evolutionary lineages underlay the parallel changes in chromatin structure. Our results indicate that, despite several hundred million years of separation, parallel changes in chromatin structure, can be an important adaptation mechanism for different organisms. Due to the important role of chromatin structure changes in regulating gene expression and organism phenotypes, the novel mechanism revealed in this study could be a general phenomenon contributing to parallel adaptation in nature. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Structural dialectical approach in psychology: problems and research results

    Directory of Open Access Journals (Sweden)

    Veraksa, Nikolay E.

    2013-06-01

    Full Text Available In this article dialectical thinking is regarded as one of the central cognitive processes. Because of this cognitive function we can analyze the development of processes and objects. It also determines the possibilities for the creative transformation of some content and for solving problems. The article presents a description and the results of experimental studies. This evidence proves that dialectical thinking is a specific line of cognitive development in children and adults. This line can degrade during school time if the educational program follows formal logical principles, or it can become significantly stronger if the pedagogy is based on dialectical methodology.

  7. Computational Structure of the N-Body Problem

    Science.gov (United States)

    1988-04-01

    14 I MONITORING AGENCY N4AME A AOORESS(II dhifeent Orson Conrolln Office) it. SECU ITY CLASS. tot #his report) Office of Naval Research UCASFE...is called the "many- body" or the "N-body" problem. Such studies are conducted in celestial mechanics, plasma physics, fluid mechanics as well as in...the source of the message). Since messages are function descriptions, all mes- sages are of equal length and the concept of message time is well

  8. A combinatorial enumeration problem of RNA secondary structures

    African Journals Online (AJOL)

    use

    2011-12-21

    Dec 21, 2011 ... connection between Discrete Mathematics and Compu- tational Molecular Biology (Chen et al, 2005; Hofacker et ... in Computational Molecular Biology. An RNA molecule is described by its sequences of bases ... Here, a mathematical definition of secondary structure is given (Stein and Waterman 1978).

  9. Applications of Asymptotic Sampling on High Dimensional Structural Dynamic Problems

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Bucher, Christian

    2011-01-01

    The paper represents application of the asymptotic sampling on various structural models subjected to random excitations. A detailed study on the effect of different distributions of the so-called support points is performed. This study shows that the distribution of the support points has consid...

  10. A combinatorial enumeration problem of RNA secondary structures

    African Journals Online (AJOL)

    use

    2011-12-21

    Dec 21, 2011 ... interesting combinatorial questions (Chen et al., 2005;. Liu, 2006; Schmitt and Waterman 1994; Stein and. Waterman 1978). The research on the enumeration of. RNA secondary structures becomes one of the hot topics in Computational Molecular Biology. An RNA molecule is described by its sequences of.

  11. Solving nonconvex SDP problems of structural optimization with stability control

    Czech Academy of Sciences Publication Activity Database

    Kočvara, Michal; Stingl, M.

    2004-01-01

    Roč. 19, č. 5 (2004), s. 595-609 ISSN 1055-6788 R&D Projects: GA AV ČR IAA1075005 Grant - others:BMBF(DE) 03ZOM3ER Institutional research plan: CEZ:AV0Z1075907 Keywords : structural optimization * stability control * nonconvex semidefinite programming Subject RIV: BA - General Mathematics Impact factor: 0.273, year: 2004

  12. Research Projects in Physics: A Mechanism for Teaching Ill-Structured Problem Solving

    Science.gov (United States)

    Milbourne, Jeff; Bennett, Jonathan

    2017-01-01

    Physics education research has a tradition of studying problem solving, exploring themes such as physical intuition and differences between expert and novice problem solvers. However, most of this work has focused on traditional, or well-structured, problems, similar to what might appear in a textbook. Less work has been done with open-ended, or…

  13. Using Jigsaw-Style Spectroscopy Problem-Solving to Elucidate Molecular Structure through Online Cooperative Learning

    Science.gov (United States)

    Winschel, Grace A.; Everett, Renata K.; Coppola, Brian P.; Shultz, Ginger V.

    2015-01-01

    Cooperative learning was employed as an instructional approach to facilitate student development of spectroscopy problem solving skills. An interactive online environment was used as a framework to structure weekly discussions around spectroscopy problems outside of class. Weekly discussions consisted of modified jigsaw-style problem solving…

  14. [Problems impeding the introduction of care services under the long-term care insurance system].

    Science.gov (United States)

    Suzuki, Hiroko; Yamanaka, Katsuo; Fujita, Yoshio; Hirano, Yasuyuki; Iijima, Setsu

    2012-03-01

    To identify problems currently impeding the introduction of care services to seniors who are not yet taking advantage of such services despite the need for some kind of in-home care, and to examine effective solutions by creating a model that clarifies relationships among these problems based on covariance structural analysis. An anecdotal self-completion questionnaire was sent by mail to public health nurses who provide consultations to seniors in 657 locations throughout the mainland Japan, Honshu. The cases targeted in this survey were seniors for whom the introduction of care services was perceived to be difficult. Respondents were asked to relate one particularly memorable case encountered since April 2000 in which intervention assistance was provided through home visits. The survey consisted of 43 questions, including demographic information, basic case data, the outcome of intervention assistance in the case cited, and obstacles to introducing nursing services. We analyzed the 311 valid responses received (valid response rate: 47.3%). After performing factor analysis on the problems that were considered to impede the introduction of care services, we examined the relationships among these problems using covariance structural analysis and selected the model that best fit the data. 1) Problems that were considered to impede the introduction of care services were extracted from the results of an item analysis and factor analysis as follows. Factor 1: "Resistance to changing lifestyle." Factor 2: "Relative's lack of understanding or cooperation." Factor 3: "Lack of ability to handle procedures and contracts." Factor 4: "Lack of informal support." Factor 5: "Resistance to undergoing medical exams." 2) We performed a covariance structural analysis using the five factors derived from the factor analysis as the latent variables, and selected the best-fitting model, in which GFI = 0.929, AGFI = 0.901, and CFI = 0.950. The model showed that factors 3, 4, and 5

  15. Undocumented Immigration, Drug Problems, and Driving Under the Influence in the United States, 1990-2014.

    Science.gov (United States)

    Light, Michael T; Miller, Ty; Kelly, Brian C

    2017-09-01

    To examine the influence of undocumented immigration in the United States on 4 different metrics of drug and alcohol problems: drug arrests, drug overdose fatalities, driving under the influence (DUI) arrests, and DUI deaths. We combined newly developed state-level estimates of the undocumented population between 1990 and 2014 from the Center for Migration Studies with arrest data from the Federal Bureau of Investigation Uniform Crime Reports and fatality information from the Fatality Analysis Reporting System and the Centers for Disease Control and Prevention Underlying Cause of Death database. We used fixed-effects regression models to examine the longitudinal association between increased undocumented immigration and drug problems and drunk driving. Increased undocumented immigration was significantly associated with reductions in drug arrests, drug overdose deaths, and DUI arrests, net of other factors. There was no significant relationship between increased undocumented immigration and DUI deaths. This study provides evidence that undocumented immigration has not increased the prevalence of drug or alcohol problems, but may be associated with reductions in these public health concerns.

  16. Obstacles Related to Structuring for Mathematization Encountered by Students when Solving Physics Problems

    DEFF Research Database (Denmark)

    Niss, Martin

    2017-01-01

    This paper studies the cognitive obstacles related to one aspect of mathematization in physics problem-solving, namely, what might be called structuring for mathematization, where the problem situation is structured in such a way that a translation to a mathematical universe can be done. We report...... the results of an analysis of four protocols from task-based interviews with university students working on physics problems in pairs who fail when solving the problems. The obstacles encountered by the students are shown to be related to how the students approach the structuring for mathematization...

  17. Obstacles Related to Structuring for Mathematization Encountered by Students When Solving Physics Problems

    Science.gov (United States)

    Niss, Martin

    2017-01-01

    This paper studies the cognitive obstacles related to one aspect of mathematization in physics problem-solving, namely, what might be called "structuring for mathematization," where the problem situation is structured in such a way that a translation to a mathematical universe can be done. We report the results of an analysis of four…

  18. STRUCTURAL SAFETY ANALYSIS OF STADIUMS FOR THE 2018 FIFA WORLD CUP IN RUSSIA. FORMULATION OF PROBLEMS OF STRUCTURAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Alexander M. Belostotsky

    2018-03-01

    Full Text Available The article presents structural safety analysis of the three-dimensional long-span systems “ground base – reinforced concrete foundation structures and stands - metal structures of the coating and facades” of football stadiums for the 2018 World Cup in Russia with basic and special combinations of loads and formulation problems of future in-vestigations.

  19. A New Computational Methodology for Structural Dynamics Problems

    Science.gov (United States)

    2008-04-01

    method, least-squares formulation, plates and shells, nonlinear analysis, FGM J. N. Reddy Texas A&M University-College Station Administration Building...of thermal loading and uniform pressure on the bending response of FGM plates ; and Yang and Shen (2003a,b), who analyzed the nonlinear bending and...postbuckling behavior for FGM plates under thermomechanical load with various boundary conditions. Woo and Meghid (2001) provided an analytical

  20. Thermal shock problems of bonded structure for plasma facing components

    International Nuclear Information System (INIS)

    Shibui, M.; Kuroda, T.; Kubota, Y.

    1991-01-01

    Thermal shock tests have been performed on W(Re)/Cu and Mo/Cu duplex structures with a particular emphasis on two failure modes: failure on the heated surface and failure near the bonding interface. The results indicate that failure of the duplex structure largely depends on the constraint of thermal strain on the heated surface and on the ductility changes of armour materials. Rapid debonding of the bonding interface may be attributed to the yielding of armour materials. This leads to a residual bending deformation when the armour cools down. Arguments are also presented in this paper on two parameter characterization of the failure of armour materials and on stress distribution near the free edge of the bonding interface. (orig.)

  1. Finite Element Solution of Fluid-Structure Interaction Problems

    Science.gov (United States)

    1976-10-01

    N7AMEKSAD11111 rinouui seeu 11010A M aifel "l~ina lide.) IS. SECUR1YT CLASS. (of I%#l IOlWJ UNCLASSIFIED S-ITRSTON ITT-N .. APPIROVED FOR PUBLIC RELLA1SE...et al 2 to determine the acoustic radiation from a piezoelectric cylinder. "Everstine et al3 reviewed this and other methods for fluid-structure

  2. SPH Simulation of Fluid-Structure Interaction Problems with Application to Hovercraft

    OpenAIRE

    Yang, Qing

    2011-01-01

    A Computational Fluid Dynamics (CFD) tool is developed in this thesis to solve complex fluid-structure interaction (FSI) problems. The fluid domain is based on Smoothed Particle Hydro-dynamics (SPH) and the structural domain employs large-deformation Finite Element Method (FEM). Validation tests of SPH and FEM are first performed individually. A loosely-coupled SPH-FEM model is then proposed for solving FSI problems. Validation results of two benchmark FSI problems are illustrated (Antoci et ...

  3. REVIEWS OF TOPICAL PROBLEMS Small-angle neutron scattering in structure research of magnetic fluids

    Science.gov (United States)

    Avdeev, Mikhail V.; Aksenov, Viktor L.

    2011-01-01

    A magnetic fluid (MF) is a liquid dispersion of magnetic nanoparticles coated by surfactants for stabilization. The MF research reviewed in this paper is primarily aimed at investigating the atomic and magnetic structure of MF particles and the way they interact under various conditions by means of small-angle neutron scattering (SANS). The presence of a liquid carrier in the structure and the magnetic properties of MFs, which are very close to those of an ideal superparamagnetic system, allow the effective use of the major neutron scattering features: the strong effect of hydrogen-deuterium isotopic substitution and magnetic scattering. An extension of the contrast variation technique to the structure research on polydisperse and superparamagnetic systems is proposed. The cases of noninteracting and interacting particles, the latter with cluster formation taken into account, are considered for non-magnetized and magnetized MFs. The polarized neutron scattering analysis of the structure of magnetized MFs is illustrated by examples. Topical problems in further developing the method to study multiparameter systems are identified.

  4. Sun oscillations and the problem of its internal structure

    International Nuclear Information System (INIS)

    Severnyj, A.B.; Kotov, V.A.; Tsap, T.T.

    1979-01-01

    Analysis of global solar oscillation measurements for five years (1974-1978, more than 1000 hours of observations, 215 days) is given. It is shown that the period of oscillations is 160sup(m)x0.10+-0sup(m)x004 and the amplitude is 1 m/s. The phases of oscillations, obtained at the Crimea, Stanford, Kitt Peak and Pic du Midi, are in good agreement, thus making the assumption on ''telluric origin'' of the oscillations improbable. It has been found: 1) slow, synchronous (at Crimea and Stanford) drift of the phase of velocity maximum from year to year and 2) the dependence of amplitude on the phase of 27-day rotational period of the Sun which favours the assumption on the quadrupole character of oscillations. It is pointed out that these facts, as well as the absence of oscillation waves in the telluric line observed simultaneously with the solar line, exclude the possibility of explaining the results as a statistical artifact. It has also been shown that the differential extinction effect produces an oscillation effect which is by an order of magnitude lower than the observed one. The following preliminary results are noted: a) the appearance of synchronous oscillations of the mean solar magnetic field of the brightness of the Sun and of the solar radio emission; b) the disappearance of the oscillations from time to time, possibly due to the effect of the supergranulation passage across the solar disk. The oscillations observed imply new important restrictions on the problem of the internal constitution of the Sun, and point to the possibility of non-radiative heat-transfer inside the Sun which might help the solution of the low neutrino flux problem

  5. Anti-plane problem analysis for icosahedral quasicrystals under shear loadings

    International Nuclear Information System (INIS)

    Li Wu; Chai Yu-Zhen

    2014-01-01

    The present paper is concerned with the longitudinal shear elasticity of three-dimensional icosahedral quasicrystals. By virtue of the Dugdale hypothesis along with the method of complex potential theory, it involves two defect problems of the icosahedral quasicrystals. The first one is the calculation of stress intensity factors and the size of the cohesive force zone in a half-infinite crack. Meanwhile, the crack tip tearing displacements can be exactly derived. The other is the demonstration of the generalized stress intensity factors induced by a sharp V-notch as an extension of a crack. The generalized E-integral around the notch tip gives the energy release rate when the V-notch degenerates into a crack. Apart from their own usefulness in carrying out some simplified crack analyses, the results obtained in this work can particularly serve as a basis for fracture mechanics of anti-plane defect problems of icosahedral quasicrystals. (condensed matter: structural, mechanical, and thermal properties)

  6. CARIBBEAN OFFSHORE CORPORATE STRUCTURES UNDER A SWOT ANALYSIS

    Directory of Open Access Journals (Sweden)

    Ana-Maria GEAMÃNU

    2015-04-01

    Full Text Available Tax havens have long been under the attention of numerous Governments and International Organizations which triggered the concern of an uneven playing field in the taxation area. As a result numerous amendments have been made to both their commercial and tax legislations in order to be in line with the internationally agreed tax standards. The aim of this article is to conduct a SWOT analysis on the offshore corporate structures found in the Caribbean landscape. Based on a selection process of the most commonly recognized tax havens in the Caribbean region and an analysis of their offshore companies at the level of incorporation, administration, activities conducted and costs, a set of frequently met characteristics have been identified which stand at the basis of the SWOT analysis. The results stand to present a comprehensive four dimension framework of the offshore corporate structures in regards to their strengths, weaknesses, opportunities and threats.

  7. Capital Structure Arbitrage under a Risk-Neutral Calibration

    Directory of Open Access Journals (Sweden)

    Peter J. Zeitsch

    2017-01-01

    Full Text Available By reinterpreting the calibration of structural models, a reassessment of the importance of the input variables is undertaken. The analysis shows that volatility is the key parameter to any calibration exercise, by several orders of magnitude. To maximize the sensitivity to volatility, a simple formulation of Merton’s model is proposed that employs deep out-of-the-money option implied volatilities. The methodology also eliminates the use of historic data to specify the default barrier, thereby leading to a full risk-neutral calibration. Subsequently, a new technique for identifying and hedging capital structure arbitrage opportunities is illustrated. The approach seeks to hedge the volatility risk, or vega, as opposed to the exposure from the underlying equity itself, or delta. The results question the efficacy of the common arbitrage strategy of only executing the delta hedge.

  8. Structural characterization of lipidic systems under nonequilibrium conditions

    DEFF Research Database (Denmark)

    Yaghmur, Anan; Rappolt, Michael

    2012-01-01

    manipulation techniques including, for instance, stop-flow mixing or rapid temperature-jump perturbation is given. Second, our recent synchrotron SAXS findings on the dynamic structural response of gold nanoparticle-loaded vesicles upon exposure to an ultraviolet light source, the impact of rapidly mixing...... and the possible formation of intermediate states in the millisecond to second range. The need for investigating self-assembled systems, mainly stimuli-responsive drug nanocarriers, under nonequilibrium conditions is discussed. For pharmaceutically relevant applications, it is essential to combine...

  9. Structural Behavior of SC and RC Panels under Impact Loading

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyuk-Kee; Kim, Seung-Eock [Sejong University, Seoul (Korea, Republic of)

    2015-05-15

    NPP structures have been generally constructed using reinforced concrete (RC) structures. In recent studies, however, it has been confirmed that a steel-plate concrete (SC) structures has a much better impact resistance than an RC structure. In this paper, the impact resistance of SC and RC panels is evaluated using the commercial software LS-DYNA. To verify finite element (FE) models, the analysis results for SC and half steel-plate concrete panels under impact loading are compared with the test results conducted in other research. The impact analysis according to the different steel ratios with four different concrete thicknesses is performed in order to compare the impact resistance of SC and RC panels. To compare the impact resistance of SC and RC panels, the impact analysis was performed according to the different steel ratios with four different concrete thicknesses. Based on this study, the following conclusions have been obtained: (1) The rear face steel plate of SC panel plays more important role than the rear rebar of RC panel in preventing perforation. (2) When the perforation failure occurs, RC panel is more effective than SC panel to reduce the velocity of the missile.

  10. The problems of hygienic classification of radioactive waste under restoration of contaminated areas

    International Nuclear Information System (INIS)

    Savkin, M.; Shandala, N.; Novikova, N.; Petukhova, E.; Shishkin, V.; Egorov, B.; Ziborov, A.

    2002-01-01

    Experience on restoration of contaminated areas in the past ten years reveals a specific problem in the general problem of solid radioactive waste management as a result of decontamination of the settlements. That specific problem concerns conventionally radioactive waste (CRW), which might be to some extent dangerous for human being. In the documents of IAEA and ICRP the approaches aimed at exemption or exclusion insignificant amount of radioactive wastes from regulatory control are actively being developed. In turn, Russia does not have so far either methodic or regulatory documents on management of very low level radioactive waste. Two approaches are considered in the paper under development of derived levels for CRW in case of restoration of contaminated areas. The first one is based on restriction of individual risk at level about 10 -6 per year (negligible level). The second one accounts for global man-made background and uses acceptable factor of excess of that background as a criterion.Under the first approach (restriction of individual risk) the lowest boundary of CRW is estimated to be equal to 3 Bq kg -1 for 239 Pu; 30 Bq kg -1 for 90 Sr; and 300 Bq kg -1 for 137 Cs, respectively. Those levels of specific activity approximately correspond to the areas contaminated by the above mentioned radionuclides 0.3 kBq m -2 , 3 kBq m -2 , and 30 kBq m -2 , respectively. Under the second approach if one accepts factor of 3 of excess of global man-made background, than the levels of specific activity will be 0.05 kBq m -2 for 239 Pu; 2.5 kBq m -2 for 90 Sr, and 7.2 kBq m -2 for 137 Cs. Comparison of the levels obtained according to the second approach shows that they will be several times lower than that according to the first approach. (author)

  11. Topological spin-singlet superconductors with underlying sublattice structure

    Science.gov (United States)

    Dutreix, C.

    2017-07-01

    Majorana boundary quasiparticles may naturally emerge in a spin-singlet superconductor with Rashba spin-orbit interactions when a Zeeman magnetic field breaks time-reversal symmetry. Their existence and robustness against adiabatic changes is deeply related, via a bulk-edge correspondence, to topological properties of the band structure. The present paper shows that the spin-orbit may be responsible for topological transitions when the superconducting system has an underlying sublattice structure, as it appears in a dimerized Peierls chain, graphene, and phosphorene. These systems, which belong to the Bogoliubov-de Gennes class D, are found to have an extra symmetry that plays the role of the parity. It enables the characterization of the topology of the particle-hole symmetric band structure in terms of band inversions. The topological phase diagrams this leads to are then obtained analytically and exactly. They reveal that, because of the underlying sublattice structure, the existence of topological superconducting phases requires a minimum doping fixed by the strength of the Rashba spin orbit. Majorana boundary quasiparticles are finally predicted to emerge when the Fermi level lies in the vicinity of the bottom (top) of the conduction (valence) band in semiconductors such as the dimerized Peierls chain and phosphorene. In a two-dimensional topological superconductor based on (stretched) graphene, which is semimetallic, Majorana quasiparticles cannot emerge at zero and low doping, that is, when the Fermi level is close to the Dirac points. Nevertheless, they are likely to appear in the vicinity of the van Hove singularities.

  12. Adjoint Techniques for Topology Optimization of Structures Under Damage Conditions

    Science.gov (United States)

    Akgun, Mehmet A.; Haftka, Raphael T.

    2000-01-01

    The objective of this cooperative agreement was to seek computationally efficient ways to optimize aerospace structures subject to damage tolerance criteria. Optimization was to involve sizing as well as topology optimization. The work was done in collaboration with Steve Scotti, Chauncey Wu and Joanne Walsh at the NASA Langley Research Center. Computation of constraint sensitivity is normally the most time-consuming step of an optimization procedure. The cooperative work first focused on this issue and implemented the adjoint method of sensitivity computation (Haftka and Gurdal, 1992) in an optimization code (runstream) written in Engineering Analysis Language (EAL). The method was implemented both for bar and plate elements including buckling sensitivity for the latter. Lumping of constraints was investigated as a means to reduce the computational cost. Adjoint sensitivity computation was developed and implemented for lumped stress and buckling constraints. Cost of the direct method and the adjoint method was compared for various structures with and without lumping. The results were reported in two papers (Akgun et al., 1998a and 1999). It is desirable to optimize topology of an aerospace structure subject to a large number of damage scenarios so that a damage tolerant structure is obtained. Including damage scenarios in the design procedure is critical in order to avoid large mass penalties at later stages (Haftka et al., 1983). A common method for topology optimization is that of compliance minimization (Bendsoe, 1995) which has not been used for damage tolerant design. In the present work, topology optimization is treated as a conventional problem aiming to minimize the weight subject to stress constraints. Multiple damage configurations (scenarios) are considered. Each configuration has its own structural stiffness matrix and, normally, requires factoring of the matrix and solution of the system of equations. Damage that is expected to be tolerated is local

  13. A multiple ship routing and speed optimization problem under time, cost and environmental objectives

    DEFF Research Database (Denmark)

    Wen, M.; Pacino, Dario; Kontovas, C.A.

    2017-01-01

    The purpose of this paper is to investigate a multiple ship routing and speed optimization problem under time, cost and environmental objectives. A branch and price algorithm as well as a constraint programming model are developed that consider (a) fuel consumption as a function of payload, (b......) fuel price as an explicit input, (c) freight rate as an input, and (d) in-transit cargo inventory costs. The alternative objective functions are minimum total trip duration, minimum total cost and minimum emissions. Computational experience with the algorithm is reported on a variety of scenarios....

  14. A model for the inverse 1-median problem on trees under uncertain costs

    Directory of Open Access Journals (Sweden)

    Kien Trung Nguyen

    2016-01-01

    Full Text Available We consider the problem of justifying vertex weights of a tree under uncertain costs so that a prespecified vertex become optimal and the total cost should be optimal in the uncertainty scenario. We propose a model which delivers the information about the optimal cost which respect to each confidence level \\(\\alpha \\in [0,1]\\. To obtain this goal, we first define an uncertain variable with respect to the minimum cost in each confidence level. If all costs are independently linear distributed, we present the inverse distribution function of this uncertain variable in \\(O(n^{2}\\log n\\ time, where \\(n\\ is the number of vertices in the tree.

  15. Stability assessment of structures under earthquake hazard through GRID technology

    Science.gov (United States)

    Prieto Castrillo, F.; Boton Fernandez, M.

    2009-04-01

    This work presents a GRID framework to estimate the vulnerability of structures under earthquake hazard. The tool has been designed to cover the needs of a typical earthquake engineering stability analysis; preparation of input data (pre-processing), response computation and stability analysis (post-processing). In order to validate the application over GRID, a simplified model of structure under artificially generated earthquake records has been implemented. To achieve this goal, the proposed scheme exploits the GRID technology and its main advantages (parallel intensive computing, huge storage capacity and collaboration analysis among institutions) through intensive interaction among the GRID elements (Computing Element, Storage Element, LHC File Catalogue, federated database etc.) The dynamical model is described by a set of ordinary differential equations (ODE's) and by a set of parameters. Both elements, along with the integration engine, are encapsulated into Java classes. With this high level design, subsequent improvements/changes of the model can be addressed with little effort. In the procedure, an earthquake record database is prepared and stored (pre-processing) in the GRID Storage Element (SE). The Metadata of these records is also stored in the GRID federated database. This Metadata contains both relevant information about the earthquake (as it is usual in a seismic repository) and also the Logical File Name (LFN) of the record for its later retrieval. Then, from the available set of accelerograms in the SE, the user can specify a range of earthquake parameters to carry out a dynamic analysis. This way, a GRID job is created for each selected accelerogram in the database. At the GRID Computing Element (CE), displacements are then obtained by numerical integration of the ODE's over time. The resulting response for that configuration is stored in the GRID Storage Element (SE) and the maximum structure displacement is computed. Then, the corresponding

  16. Integration of QFD, AHP, and LPP methods in supplier development problems under uncertainty

    Science.gov (United States)

    Shad, Zahra; Roghanian, Emad; Mojibian, Fatemeh

    2014-04-01

    Quality function deployment (QFD) is a customer-driven approach, widely used to develop or process new product to maximize customer satisfaction. Last researches used linear physical programming (LPP) procedure to optimize QFD; however, QFD issue involved uncertainties, or fuzziness, which requires taking them into account for more realistic study. In this paper, a set of fuzzy data is used to address linguistic values parameterized by triangular fuzzy numbers. Proposed integrated approach including analytic hierarchy process (AHP), QFD, and LPP to maximize overall customer satisfaction under uncertain conditions and apply them in the supplier development problem. The fuzzy AHP approach is adopted as a powerful method to obtain the relationship between the customer requirements and engineering characteristics (ECs) to construct house of quality in QFD method. LPP is used to obtain the optimal achievement level of the ECs and subsequently the customer satisfaction level under different degrees of uncertainty. The effectiveness of proposed method will be illustrated by an example.

  17. A Decision Optimization Model for Leased Manufacturing Equipment with Warranty under Forecasting Production/Maintenance Problem

    Directory of Open Access Journals (Sweden)

    Zied Hajej

    2015-01-01

    Full Text Available Due to the expensive production equipment, many manufacturers usually lease production equipment with a warranty period during a finite leasing horizon, rather than purchasing them. The lease contract contains the possibility of obtaining an extended warranty for a given additional cost. In this paper, based on the forecasting production/maintenance optimization problem, we develop a mathematical model to study the lease contract with basic and extended warranty based on win-win relationship between the lessee and the lessor. The influence of the production rates in the equipment degradation consequently on the total cost by each side during the finite leasing horizon is stated in order to determine a theoretical condition under which a compromise-pricing zone exists under different possibilities of maintenance policies.

  18. Bi-Objective Flexible Job-Shop Scheduling Problem Considering Energy Consumption under Stochastic Processing Times.

    Science.gov (United States)

    Yang, Xin; Zeng, Zhenxiang; Wang, Ruidong; Sun, Xueshan

    2016-01-01

    This paper presents a novel method on the optimization of bi-objective Flexible Job-shop Scheduling Problem (FJSP) under stochastic processing times. The robust counterpart model and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are used to solve the bi-objective FJSP with consideration of the completion time and the total energy consumption under stochastic processing times. The case study on GM Corporation verifies that the NSGA-II used in this paper is effective and has advantages to solve the proposed model comparing with HPSO and PSO+SA. The idea and method of the paper can be generalized widely in the manufacturing industry, because it can reduce the energy consumption of the energy-intensive manufacturing enterprise with less investment when the new approach is applied in existing systems.

  19. Explicit Solution of Reinsurance-Investment Problem for an Insurer with Dynamic Income under Vasicek Model

    Directory of Open Access Journals (Sweden)

    De-Lei Sheng

    2016-01-01

    Full Text Available Unlike traditionally used reserves models, this paper focuses on a reserve process with dynamic income to study the reinsurance-investment problem for an insurer under Vasicek stochastic interest rate model. The insurer’s dynamic income is given by the remainder after a dynamic reward budget being subtracted from the insurer’s net premium which is calculated according to expected premium principle. Applying stochastic control technique, a Hamilton-Jacobi-Bellman equation is established and the explicit solution is obtained under the objective of maximizing the insurer’s power utility of terminal wealth. Some economic interpretations of the obtained results are explained in detail. In addition, numerical analysis and several graphics are given to illustrate our results more meticulous.

  20. [Power in the hospital. Considerations on a structural problem].

    Science.gov (United States)

    Pillen, A

    1997-04-01

    This article tries to establish elements for an analysis of the power relations in hospital. After an explanation of the notion of power with recurrence to Max Weber, it presents different forms of the exercise of power. The traditional authoritarian form of power is compared with modern forms that are less personal and more anonymous. Then, the article tries to explain the special relationship between power and medicine. The basis for the analysis of this relationship is taken from Michel Foucault's analysis of power who describes medicine as the switch position of modern forms of exercise of power. He defines this under two different points of view: firstly, medicine works as an institution of disciplinary power, secondly, medicine is the sustainer of the bio-power, a kind of power that works by giving life.

  1. Structural Health Monitoring under Nonlinear Environmental or Operational Influences

    Directory of Open Access Journals (Sweden)

    Jyrki Kullaa

    2014-01-01

    Full Text Available Vibration-based structural health monitoring is based on detecting changes in the dynamic characteristics of the structure. It is well known that environmental or operational variations can also have an influence on the vibration properties. If these effects are not taken into account, they can result in false indications of damage. If the environmental or operational variations cause nonlinear effects, they can be compensated using a Gaussian mixture model (GMM without the measurement of the underlying variables. The number of Gaussian components can also be estimated. For the local linear components, minimum mean square error (MMSE estimation is applied to eliminate the environmental or operational influences. Damage is detected from the residuals after applying principal component analysis (PCA. Control charts are used for novelty detection. The proposed approach is validated using simulated data and the identified lowest natural frequencies of the Z24 Bridge under temperature variation. Nonlinear models are most effective if the data dimensionality is low. On the other hand, linear models often outperform nonlinear models for high-dimensional data.

  2. Effects of a Problem-based Structure of Physics Contents on Conceptual Learning and the Ability to Solve Problems

    Science.gov (United States)

    Becerra-Labra, Carlos; Gras-Martí, Albert; Martínez Torregrosa, Joaquín

    2012-05-01

    A model of teaching/learning is proposed based on a 'problem-based structure' of the contents of the course, in combination with a training in paper and pencil problem solving that emphasizes discussion and quantitative analysis, rather than formulae plug-in. The aim is to reverse the high failure and attrition rate among engineering undergraduates taking physics. A number of tests and questionnaires were administered to a group of students following a traditional lecture-based instruction, as well as to another group that was following an instruction scheme based on the proposed approach and the teaching materials developed ad hoc. The results show that students following the new method can develop scientific reasoning habits in problem-solving skills, and show gains in conceptual learning, attitudes and interests, and that the effects of this approach on learning are noticeable several months after the course is over.

  3. A new fluid-solid interface algorithm for simulating fluid structure problems in FGM plates

    Science.gov (United States)

    Eghtesad, A.; Shafiei, A. R.; Mahzoon, M.

    2012-04-01

    The capability to track material interfaces, especially in fluid structure problems, is among the advantages of meshless methods. In the present paper, the Smoothed Particle Hydrodynamics (SPH) method is used to investigate elastic-plastic deformation of AL and ceramic-metal FGM (Functionally Graded Materials) plates under the impact of water in a fluid-solid interface. Instead of using an accidental repulsive force which is not stable at higher pressures, a new scheme is proposed to improve the interface contact behavior between fluid and solid structure. This treatment not only prevents the interpenetration of fluid and solid particles significantly, but also maintains the gap distance between fluid and solid boundary particles in a reasonable range. A new scheme called corrected smooth particle method (CSPM) is applied to both fluid and solid particles to improve the free surface behavior. In order to have a more realistic free surface behavior in fluid, a technique is used to detect the free surface boundary particles during the solution process. The results indicate that using the proposed interface algorithm together with CSPM correction, one can predict the dynamic behavior of FGM plates under the impact of fluid very promisingly.

  4. Modeling and solving the dynamic patient admission scheduling problem under uncertainty.

    Science.gov (United States)

    Ceschia, Sara; Schaerf, Andrea

    2012-11-01

    Our goal is to propose and solve a new formulation of the recently-formalized patient admission scheduling problem, extending it by including several real-world features, such as the presence of emergency patients, uncertainty in the length of stay, and the possibility of delayed admissions. We devised a metaheuristic approach that solves both the static (predictive) and the dynamic (daily) versions of this new problem, which is based on simulated annealing and a complex neighborhood structure. The quality of our metaheuristic approach is compared with an exact method based on integer linear programming. The main outcome is that our method is able to solve large cases (up to 4000 patients) in a reasonable time, whereas the exact method can solve only small/medium-size instances (up to 250 patients). For such datasets, the two methods obtain results at the same level of quality. In addition, the gap between our (dynamic) solver and the static one, which has all information available in advance, is only 4-5%. Finally, we propose (and publish on the web) a large set of new instances, and we discuss the impact of their features in the solution process. The metaheuristic approach proved to be a valid search method to solve dynamic problems in the healthcare domain. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Anatomical position of the asterion and its underlying structure.

    Science.gov (United States)

    Sripairojkul, B; Adultrakoon, A

    2000-09-01

    Surface anatomy is important for surgical planning. The asterion has been believed and used for locating the underlying posterior fossa dura. To prove whether this landmark is reliable or not, forty-three fixed heads of cadaver were dissected. A burr hole was made on the asterion and its underlying structure was examined. Seventy-four point four per cent (74.4%) of the asterion on the right side were adjacent to the transverse-sigmoid sinus complex when compared to 58.1 per cent on the left. Twenty-three point three per cent (23.3%) of the asterion on the right side were found over the infratentorial dura while that on the left side were 32.6 per cent. Two point three per cent (2.3%) of the asterion were located over the supratentorial dura on the right and 9.3 per cent on the left side. It is concluded, therefore, that the asterion is not an appropriate landmark to locate the underlying posterior fossa dura.

  6. Size-dependent structure of silver nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Koski, Kristie Jo [Univ. of California, Berkeley, CA (United States)

    2008-12-31

    Silver noble metal nanoparticles that are<10 nm often possess multiply twinned grains allowing them to adopt shapes and atomic structures not observed in bulk materials. The properties exhibited by particles with multiply twinned polycrystalline structures are often far different from those of single-crystalline particles and from the bulk. I will present experimental evidence that silver nanoparticles<10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. Results for nanoparticles in the intermediate size range of 5 to 10 nm suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. I propose a mechanism for this transitiion that considers the bond-length distribution in idealized multiply twinned icosahedral particles. Results for nanoparticles of 3.9 nm suggest a reversible linear pressure-dependent orthorhombic distortion. This distortion is interpreted in the context of idealized decahedral particles. In addition, given these size-dependent measurements of silver nanoparticle compression with pressure, we have constructed a pressure calibration curve. Encapsulating these silver nanoparticles in hollow metal oxide nanospheres then allows us to measure the pressure inside a nanoshell using x-ray diffraction. We demonstrate the measurement of pressure gradients across nanoshells and show that these nanoshells have maximum resolved shear strengths on the order of 500 MPa to IGPa.

  7. Study of patient satisfaction and self-expressed problems after emergency caesarean delivery under subarachnoid block

    Directory of Open Access Journals (Sweden)

    V R Hemanth Kumar

    2014-01-01

    Full Text Available Background and Aims: Subarachnoid block is one of the common modes of anaesthesia opted for emergency caesarean section, if the maternal and foetal conditions are favourable. Various factors influence the quality of care administered during the procedure. This questionnaire based study was undertaken to look for self-expressed problems in peri-operative period in patients undergoing emergency caesarean surgery under subarachnoid block. Methods: All the parturients who underwent emergency caesarean section under subarachnoid block during 6 months period were distributed a questionnaire in post-operative period. They were encouraged to fill and return the form within 15 days. Patient satisfaction and the self-expressed problems were analysed at the end of 6 months. Results: One hundred and seventy five out of 220 parturients responded. 58.3% of them said that they were explained about the anaesthesia prior to surgery and 85.3% overall remained anxious. With people around them, 93.1% of them felt comfortable and 91.4% expressed that they were made comfortable inside the theatre. The self-expressed problems were shivering (43.4%, breathlessness (21.7%, pain (20%, post-operative headache (15.4% and backache (19.4%. Parturients who heard their babies cry was 85.1%. After their babies were shown after delivery, 77.1% mothers slept well; 86.9% fed their babies within 4 h of delivery. Conclusion: Pre-operative communication in emergency caesarean section by health personnel did not reduce the anxiety level, which shows that communication was ineffective. Intra-operative psychological support like making the patient comfortable, showing baby to mother and early breast feeding improve bonding between child and mother and essentially contribute to patient satisfaction.

  8. Design of a Generic and Flexible Data Structure for Efficient Formulation of Large Scale Network Problems

    DEFF Research Database (Denmark)

    Quaglia, Alberto; Sarup, Bent; Sin, Gürkan

    2013-01-01

    The formulation of Enterprise-Wide Optimization (EWO) problems as mixed integer nonlinear programming requires collecting, consolidating and systematizing large amount of data, coming from different sources and specific to different disciplines. In this manuscript, a generic and flexible data...... structure for efficient formulation of enterprise-wide optimization problems is presented. Through the integration of the described data structure in our synthesis and design framework, the problem formulation workflow is automated in a software tool, reducing time and resources needed to formulate large...... problems, while ensuring at the same time data consistency and quality at the application stage....

  9. A Multi-Model Reduction Technique for Optimization of Coupled Structural-Acoustic Problems

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas

    2016-01-01

    Finite Element models of structural-acoustic coupled systems can become very large for complex structures with multiple connected parts. Optimization of the performance of the structure based on harmonic analysis of the system requires solving the coupled problem iteratively and for several...... frequencies, which can become highly time consuming. Several modal-based model reduction techniques for structure-acoustic interaction problems have been developed in the literature. The unsymmetric nature of the pressure-displacement formulation of the problem poses the question of how the reduction modal...... base should be formed, given that the modal vectors are not orthogonal due to the asymmetry of the system matrices. In this paper, a multi-model reduction (MMR) technique for structure-acoustic interaction problems is developed. In MMR, the reduction base is formed with the modal vectors of a family...

  10. The effect of neighborhood structures on tabu search algorithm in solving university course timetabling problem

    Science.gov (United States)

    Shakir, Ali; AL-Khateeb, Belal; Shaker, Khalid; Jalab, Hamid A.

    2014-12-01

    The design of course timetables for academic institutions is a very difficult job due to the huge number of possible feasible timetables with respect to the problem size. This process contains lots of constraints that must be taken into account and a large search space to be explored, even if the size of the problem input is not significantly large. Different heuristic approaches have been proposed in the literature in order to solve this kind of problem. One of the efficient solution methods for this problem is tabu search. Different neighborhood structures based on different types of move have been defined in studies using tabu search. In this paper, different neighborhood structures on the operation of tabu search are examined. The performance of different neighborhood structures is tested over eleven benchmark datasets. The obtained results of every neighborhood structures are compared with each other. Results obtained showed the disparity between each neighborhood structures and another in terms of penalty cost.

  11. A Multi-Model Reduction Technique for Optimization of Coupled Structural-Acoustic Problems

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas

    2016-01-01

    Finite Element models of structural-acoustic coupled systems can become very large for complex structures with multiple connected parts. Optimization of the performance of the structure based on harmonic analysis of the system requires solving the coupled problem iteratively and for several...

  12. Topological Design for Acoustic-Structure Interaction Problems with a Mixed Finite Element Method

    DEFF Research Database (Denmark)

    Yoon, Gil Ho; Jensen, Jakob Søndergaard; Sigmund, Ole

    2006-01-01

    We propose a gradient based topology optimization algorithm for acoustic-structure (Vibro-acoustic) interaction problems without an explicit interfacing boundary representation. In acoustic-structure interaction problems, the pressure field and the displacement field are governed by the Helmholtz...... to subdomain interfaces evolving during the optimization process. In this paper, we propose to use a mixed finite element formulation with displacements and pressure as primary variables (u/p formulation) which eliminates the need for explicit boundary representation. In order to describe the Helmholtz...... acoustic-structure interaction problems are optimized to show the validity of the proposed method....

  13. Problem drinking's associations with social structure and mental health care: race/ethnicity differences.

    Science.gov (United States)

    Lo, Celia C; Cheng, Tyrone C; Howell, Rebecca J

    2014-01-01

    This research used a nationally representative sample of 12,756 respondents self-identified as White, Black, Hispanic, or Asian to examine problem drinking in relationship to social structure and mental healthcare factors. Associations between problem drinking and particular factors varied by racial/ethnic group. Results also indicated that Whites' problem-drinking rates were higher than those of Hispanics, Blacks, and Asians. Americans sometimes use alcohol to manage stress stemming from social disadvantage and inadequate material resources. Across racial/ethnic groups, drinking level was associated with the type and degree of such disadvantage. Additionally, the presence of a mental health problem was associated with problem drinking.

  14. Pre-service mathematics teachers’ ability in solving well-structured problem

    Science.gov (United States)

    Paradesa, R.

    2018-01-01

    This study aimed to describe the mathematical problem-solving ability of undergraduate students of mathematics education in solving the well-structured problem. The type of this study was qualitative descriptive. The subjects in this study were 100 undergraduate students of Mathematics Education at one of the private universities in Palembang city. The data in this study was collected through two test items with essay form. The results of this study showed that, from the first problem, only 8% students can solve it, but do not check back again to validate the process. Based on a scoring rubric that follows Polya strategy, their answer satisfied 2 4 2 0 patterns. But, from the second problem, 45% students satisfied it. This is because the second problem imitated from the example that was given in learning process. The average score of undergraduate students mathematical problem-solving ability in solving well-structured problems showed 56.00 with standard deviation was 13.22. It means that, from 0 – 100 scale, undergraduate students mathematical problem-solving ability can be categorized low. From this result, the conclusion was undergraduate students of mathematics education in Palembang still have a problem in solving mathematics well-structured problem.

  15. Instrumental variables estimation under a structural Cox model

    DEFF Research Database (Denmark)

    Martinussen, Torben; Nørbo Sørensen, Ditte; Vansteelandt, Stijn

    2017-01-01

    Instrumental variable (IV) analysis is an increasingly popular tool for inferring the effect of an exposure on an outcome, as witnessed by the growing number of IV applications in epidemiology, for instance. The majority of IV analyses of time-to-event endpoints are, however, dominated by heuristic...... and instruments. We propose a novel class of estimators and derive their asymptotic properties. The methodology is illustrated using two real data applications, and using simulated data....... approaches. More rigorous proposals have either sidestepped the Cox model, or considered it within a restrictive context with dichotomous exposure and instrument, amongst other limitations. The aim of this article is to reconsider IV estimation under a structural Cox model, allowing for arbitrary exposure...

  16. Graded Geometric Structures Underlying F-Theory Related Defect Theories

    Science.gov (United States)

    Oikonomou, V. K.

    2013-08-01

    In the context of F-theory, we study the related eight-dimensional super-Yang-Mills theory and reveal the underlying supersymmetric quantum mechanics algebra that the fermionic fields localized on the corresponding defect theory are related to. Particularly, the localized fermionic fields constitute a graded vector space, and in turn this graded space enriches the geometric structures that can be built on the initial eight-dimensional space. We construct the implied composite fiber bundles, which include the graded affine vector space and demonstrate that the composite sections of this fiber bundle are in one-to-one correspondence to the sections of the square root of the canonical bundle corresponding to the submanifold on which the zero modes are localized.

  17. Behavior of grid-stiffened composite structures under transverse loading

    Science.gov (United States)

    Gan, Changsheng

    The energy absorption characteristics and failure modes of grid-stiffened composite plates under transverse load were studied in detail. Several laboratory scale composite grid plates were fabricated by using co-mingled E-glass fiber/polypropylene matrix and carbon/nylon composites in a thermoplastic stamping process. Both experimental and finite element approaches were used to evaluate and understand the role of major failure modes on the performance of damaged grid-stiffened composite plates under transverse load. The load-deflection responses of grid-stiffened composite plates were determined and compared with those of sandwich composite plates of the same size. The failure modes of grid-stiffened composite plates under different load conditions were investigated and used as the basis for FEA models. The intrinsic strength properties of constituent composite materials were measured by using either three point bending or tensile test and were used as input data to the FEA models. Several FEA models including the major failure modes based on the experimental results were built to simulate the damage processes of grid-stiffened composite plates under transverse load. A FORTRAN subroutine was implemented within the ABAQUS code to incorporate the material failure models. Effects of damage on the modal frequencies and loss factors of grid-stiffened composite plates were also investigated experimentally. Experimental and simulation results showed that sandwich composite specimens failed catastrophically with the load dropping sharply at the displacement corresponding to initial and final failure. However, grid-stiffened composite specimens failed in a more gradual and forgiving way in a sequence of relatively small load drops. No catastrophic load drops were observed in the grid structures over the range of displacements investigated here. The SEA values of the grid composite specimens are typically higher than those of the sandwich specimens with the same boundary

  18. Structural evolution of zirconium carbide under ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gosset, D. [CEA Saclay, DEN/DMN/SRMA, F-91191 Gif/Yvette cedex (France)], E-mail: dominique.gosset@cea.fr; Dolle, M. [CEMES-CNRS (UPR 8011), BP 94347, F-31055 Toulouse cedex 4 (France); Simeone, D. [CEA Saclay, DEN/DMN/SRMA, F-91191 Gif/Yvette cedex (France); Baldinozzi, G. [SPMS, Ecole Centrale Paris, F-92295 Chatenay-Malabry cedex (France); Thome, L. [CSNSM, bat. 108, F-91405 Orsay (France)

    2008-02-15

    Zirconium carbide is one of the candidate materials to be used for some fuel components of the high temperature nuclear reactors planned in the frame of the Gen-IV project. Few data exist regarding its behaviour under irradiation. We have irradiated ZrC samples at room temperature with slow heavy ions (4 MeV Au, fluence from 10{sup 11} to 5 x 10{sup 15} cm{sup -2}) in order to simulate neutron irradiations. Grazing incidence X-Ray diffraction (GIXRD) and transmission electron microscopy (TEM) analysis have been performed in order to study the microstructural evolution of the material versus ion fluence. A high sensitivity to oxidation is observed with the formation of zirconia precipitates during the ion irradiations. Three damage stages are observed. At low fluence (<10{sup 12} cm{sup -2}), low modifications are observed. At intermediate fluence, high micro-strains appear together with small faulted dislocation loops. At the highest fluence (>10{sup 14} cm{sup -2}), the micro-strains saturate and the loops coalesce to form a dense dislocation network. No other structural modification is observed. The material shows a moderate cell parameter increase, corresponding to a 0.6 vol.% swelling, which saturates around 10{sup 14} ions/cm{sup 2}, i.e., a few Zr dpa. As a result, in spite of a strong covalent bonding component, ZrC seems to have a behaviour under irradiation close to cubic metals.

  19. The numeric visual evaluation of subsoil structure (SubVESS) under agricultural production

    DEFF Research Database (Denmark)

    Ball, B.C.; Batey, Tom; Munkholm, Lars Juhl

    2015-01-01

    Subsoil degradation in agriculture is an increasing problem worldwide, particularly due to compaction caused by heavy machinery. Here, we describe a numeric assessment of subsoil structural quality in relation to soil as a crop growth medium and illustrate its utility with results from compaction...... experiments and from fields under minimum tillage. The scoring scheme resembles the topsoil visual evaluation of soil structure (VESS) (Guimarães et al., 2011) with more emphasis on examination of the profile wall and of soil fragments. The focus is on identification and evaluation of the anthropic...... forest or long-term grassland helped to distinguish whether subsoil structural quality resulted from the natural soil composition or from degradation by land management. The derived scores may be used to judge the requirement for amelioration by subsoil loosening by mechanical inputs (e.g. deep tillage...

  20. Analysis of Dynamic Properties of Piezoelectric Structure under Impact Load

    Directory of Open Access Journals (Sweden)

    Taotao Zhang

    2015-10-01

    Full Text Available An analytical model of the dynamic properties is established for a piezoelectric structure under impact load, without considering noise and perturbations in this paper. Based on the general theory of piezo-elasticity and impact mechanics, the theoretical solutions of the mechanical and electrical fields of the smart structure are obtained with the standing and traveling wave methods, respectively. The comparisons between the two methods have shown that the standing wave method is better for studying long-time response after an impact load. In addition, good agreements are found between the theoretical and the numerical results. To simulate the impact load, both triangle and step pulse loads are used and comparisons are given. Furthermore, the influence of several parameters is discussed so as to provide some advices for practical use. It can be seen that the proposed analytical model would benefit, to some extent, the design and application (especially the airport runway of the related smart devices by taking into account their impact load performance.

  1. BACKSTEPPING ALGORITHM FOR LINEAR SISO PLANTS UNDER STRUCTURAL UNCERTAINTIES

    Directory of Open Access Journals (Sweden)

    I. B. Furtat

    2016-01-01

    Full Text Available The robust algorithm is proposed for parametric and structurally uncertain linear plants under external bounded disturbances. The structural uncertainty is an unknown dynamic order of the model of plants. The developed algorithm provides plant output tracking for a smooth bounded reference signal with a required accuracy at a finite time. It is assumed that only scalar input and output of the plants are available for measurement, but not their derivatives. For the synthesis of the control algorithm we use a modified backstepping algorithm. The synthesis of control algorithm is separated into rsteps, where ris an upper bound of the relative degree of control plant model. At each step we synthesize auxiliary controls that stabilize each subsystem about a zero. At the last step we synthesize a basic control law, which provides output tracking for smooth reference signal. It is shown that for the implementation of the algorithm we need to use only one filter of the control signal and the simplified control laws obtained by application of the real derivative elements. It allows simplifying significantly the calculation and implementation of the control system. Numerical examples and results of computer simulation are given, illustrating the operation of the proposed scheme.

  2. On the underlying gauge group structure of D=11 supergravity

    International Nuclear Information System (INIS)

    Bandos, I.A.; Azcarraga, J.A. de; Izquierdo, J.M.; Picon, M.; Varela, O.

    2004-01-01

    The underlying gauge group structure of D=11 supergravity is revisited. It may be described by a one-parametric family of Lie supergroups Σ-bar (s)x-bar SO(1,10), s 0. The family of superalgebras E-bar (s) associated to Σ-bar (s) is given by a family of extensions of the M-algebra {Pa,Qα,Zab,Za1...a5} by an additional fermionic central charge Qα'. The Chevalley-Eilenberg four-cocycle ω4∼Πα-bar Πβ-bar Πa-bar ΠbΓabαβ on the standard D=11 supersymmetry algebra may be trivialized on E-bar (s), and this implies that the three-form field A3 of D=11 supergravity may be expressed as a composite of the Σ-bar (s) one-form gauge fields ea, ψα, Bab, Ba1...a5 and ηα. Two superalgebras of E-bar (s) recover the two earlier D'Auria and Fre decompositions of A3. Another member of E-bar (s) allows for a simpler composite structure for A3 that does not involve the Ba1...a5 field. Σ-bar (s) is a deformation of Σ-bar (0), which is singularized by having an enhanced Sp(32) (rather than just SO(1,10)) automorphism symmetry and by being an expansion of OSp(1 vertical bar 32)

  3. A hierarchical method for structural topology design problems with local stress and displacement constraints

    DEFF Research Database (Denmark)

    Stolpe, Mathias; Stidsen, Thomas K.

    2005-01-01

    In this paper we present a hierarchical optimization method for finding feasible true 0-1 solutions to finite element based topology design problems. The topology design problems are initially modeled as non-convex mixed 0-1 programs. The hierarchical optimization method is applied to the problem...... from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented.......In this paper we present a hierarchical optimization method for finding feasible true 0-1 solutions to finite element based topology design problems. The topology design problems are initially modeled as non-convex mixed 0-1 programs. The hierarchical optimization method is applied to the problem...... of minimizing the weight of a structure subject to displacement and local design-dependent stress constraints. The method iteratively solves a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse...

  4. The Lie–Poisson structure of the reduced n-body problem

    International Nuclear Information System (INIS)

    Dullin, Holger R

    2013-01-01

    The classical n-body problem in d-dimensional space is invariant under the Galilean symmetry group. We reduce by this symmetry group using the method of polynomial invariants. One novelty of our approach is that we do not fix the centre of mass but rather use a momentum shifting trick to change the kinetic part of the Hamiltonian to arrive at a new, dynamically equivalent Hamiltonian which is easier to reduce. As a result we obtain a reduced system with a Lie–Poisson structure which is isomorphic to sp(2n-2), independently of d. The reduction preserves the natural form of the Hamiltonian as a sum of kinetic energy that depends on velocities only and a potential that depends on positions only. This splitting allows us to construct a Poisson integrator for the reduced n-body problem which is efficient away from collisions for n = 3. In particular, we could integrate the figure eight orbit in 18 time steps. (paper)

  5. Reliability prediction for structures under cyclic loads and recurring inspections

    Directory of Open Access Journals (Sweden)

    Alberto W. S. Mello Jr

    2009-06-01

    Full Text Available This work presents a methodology for determining the reliability of fracture control plans for structures subjected to cyclic loads. It considers the variability of the parameters involved in the problem, such as initial flaw and crack growth curve. The probability of detection (POD curve of the field non-destructive inspection method and the condition/environment are used as important factors for structural confidence. According to classical damage tolerance analysis (DTA, inspection intervals are based on detectable crack size and crack growth rate. However, all variables have uncertainties, which makes the final result totally stochastic. The material properties, flight loads, engineering tools and even the reliability of inspection methods are subject to uncertainties which can affect significantly the final maintenance schedule. The present methodology incorporates all the uncertainties in a simulation process, such as Monte Carlo, and establishes a relationship between the reliability of the overall maintenance program and the proposed inspection interval, forming a “cascade” chart. Due to the scatter, it also defines the confidence level of the “acceptable” risk. As an example, the damage tolerance analysis (DTA results are presented for the upper cockpit longeron splice bolt of the BAF upgraded F-5EM. In this case, two possibilities of inspection intervals were found: one that can be characterized as remote risk, with a probability of failure (integrity nonsuccess of 1 in 10 million, per flight hour; and other as extremely improbable, with a probability of nonsuccess of 1 in 1 billion, per flight hour, according to aviation standards. These two results are compared with the classical military airplane damage tolerance requirements.

  6. Solving the Phase Problem in Crystal Structure Determination: A Simple Introduction to Direct Methods.

    Science.gov (United States)

    Schenk, H.

    1979-01-01

    Presents a simple way to introduce Direct Methods program systems to solve phase problems in x-ray crystal structure determination. It is intended for the undergraduate chemistry student laboratory. (Author/SA)

  7. Assessment of complex environmental health problems: framing the structures and structuring the frameworks.

    Science.gov (United States)

    Knol, Anne B; Briggs, David J; Lebret, Erik

    2010-06-15

    Many environmental risks are multi-faceted and their health consequences can be far-ranging in both time and space. It can be a challenging task to develop informed policies for such risks. Integrated environmental health impact assessment aims to support policy by assessing environmental health effects in ways that take into account the complexities and uncertainties involved. For such assessment to be successful, a clear and agreed conceptual framework is needed, which defines the issue under consideration and sets out the principles on which the assessment is based. Conceptual frameworks facilitate involvement of stakeholders, support harmonized discussions, help to make assumptions explicit, and provide a framework for data analysis and interpretation. Various conceptual frameworks have been developed for different purposes, but as yet no clear taxonomy exists. We propose a three-level taxonomy of conceptual frameworks for use in environmental health impact assessment. At the first level of the taxonomy, structural frameworks show the wide context of the issues at hand. At the second level, relational frameworks describe how the assessment variables are causally related. At the third level, this causal structure is translated into an operational model, which serves as a basis for analysis. The different types of frameworks are complementary and all play a role in the assessment process. The taxonomy is illustrated using a hypothetical assessment of urban brownfield development for residential uses. We suggest that a better understanding of types of conceptual frameworks and their potential roles in the different phases of assessment will contribute to more informed assessments and policies. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Modeling Soil Sodicity Problems under Dryland and Irrigated Conditions: Case Studies in Argentina and Colombia

    Science.gov (United States)

    Pla-Sentís, Ildefonso

    2014-05-01

    Salt-affected soils, both saline and sodic, my develop both under dryland and irrigated conditions, affecting negatively the physical and chemical soil properties, the crop production and the animal and human health.Among the development processes of salt-affected soils, the processes of sodification have been generally received less attention and is less understood than the development of saline soils. Although in both of them, hydrological processes are involved in their development, in the case of sodic soils we have to consider some additional chemical and physicochemical reactions, making more difficult their modeling and prediction. In this contribution we present two case studies: one related to the development of sodic soils in the lowlands of the Argentina Pampas, under dryland conditions and sub-humid temperate climate, with pastures for cattle production; the other deals with the development of sodic soils in the Colombia Cauca Valley, under irrigated conditions and tropical sub-humid climate, in lands used for sugarcane cropping dedicated to sugar and ethanol production. In both cases the development of sodicity in the surface soil is mainly related to the effects of the composition and level of groundwater, affected in the case of Argentina Pampas by the off-site changes in dryland use and management in the upper zones and by the drainage conditions in the lowlands, and in the case of the Cauca Valley, by the on-site irrigation and drainage management in lands with sugarcane. There is shown how the model SALSODIMAR, developed by the main author, based on the balance of water and soluble componentes of both the irrigation water and groundwater under different water and land management conditions, may be adapted for the diagnosis and prediction of both problems, and for the selection of alternatives for their management and amelioration.

  9. Stochastic Benders decomposition for the supply chain investment planning problem under demand uncertainty

    Directory of Open Access Journals (Sweden)

    Fabricio Oliveira

    2012-12-01

    Full Text Available This paper presents the application of a stochastic Benders decomposition algorithm for the problem of supply chain investment planning under uncertainty applied to the petroleum byproducts supply chain. The uncertainty considered is related with the unknown demand levels for oil products. For this purpose, a model was developed based on two-stage stochastic programming. It is proposed two different solution methodologies, one based on the classical cutting plane approach presented by Van Slyke & Wets (1969, and other, based on a multi cut extension of it, firstly introduced by Birge & Louveaux (1988. The methods were evaluated on a real sized case study. Preliminary numerical results obtained from computational experiments are encouraging.

  10. Stochastic thermoelastic problem of a functionally graded plate under random temperature load

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, R. [Miyagi National College of Technology, Department of Mechanical Engineering, Natori (Japan); Sugano, Y. [Iwate University, Department of Mechanical Engineering, Morioka (Japan)

    2007-04-15

    This study attempts to derive the statistics of temperature and thermal stress in functionally graded material (FGM) plates exposed to random external temperatures. The thermomechanical properties of the FGM plates are assumed to vary arbitrarily only in the plate thickness direction. The external temperatures are expressed as random functions with respect to time. The transient temperature field in the FGM plate is determined by solving a nonhomogeneous heat conduction problem for a multilayered plate with linear nonhomogeneous thermal conductivity and different homogeneous heat capacity in each layer. The autocorrelations and power spectrum densities (PSDs) of temperature and thermal stress are derived analytically. These statistics for FGM plates composed of partially stabilised zirconia (PSZ) and austenitic stainless steel (SUS304) are computed under the condition that the fluctuation in the external temperature can be considered as white noise or a stationary Markov process. (orig.)

  11. Motions of Kepler circumbinary planets in restricted three-body problem under radiating primaries

    Energy Technology Data Exchange (ETDEWEB)

    Dermawan, B., E-mail: budider@as.itb.ac.id; Hidayat, T., E-mail: taufiq@as.itb.ac.id [Astronomy Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Jalan Ganesha 10, Bandung 40132 (Indonesia); Huda, I. N., E-mail: ibnu.nurul@students.itb.ac.id; Mandey, D., E-mail: mandey.de@gmail.com; Utama, J. A., E-mail: judhistira@yahoo.com; Tampubolon, I., E-mail: ihsan.tampubolon@gmail.com [Department of Astronomy, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Jalan Ganesha 10, Bandung 40132 (Indonesia); Wibowo, R. W., E-mail: ridlo.w.wibowo@gmail.com [Department of Computational Science, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    By observing continuously a single field of view in the sky, Kepler mission reveals outstanding results on discoveries of exoplanets. One of its recent progress is the discoveries of circumbinary planets. A circumbinary planet is an exoplanet that moves around a binary system. In this study we investigate motions of Kepler circumbinary planets belong to six binary systems, namely Kepler-16, -34, -35, -38, -47, and -413. The motions are considered to follow the Restricted Three-Body Problem (RTBP). Because the primaries (central massive objects) are stars, they are both radiatives, while the planet is an infinitesimal object. The primaries move in nearly circular and elliptic orbits with respect to their center of masses. We describe, in general, motions of the circumbinary planets in RTBP under radiating primaries. With respect to the averaged zero velocity curves, we show that motions of the exoplanets are stable, in accordance with their Hill stabilities.

  12. Normal Mode Analysis to a Poroelastic Half-Space Problem under Generalized Thermoelasticity

    Directory of Open Access Journals (Sweden)

    Chunbao Xiong

    Full Text Available Abstract The thermo-hydro-mechanical problems associated with a poroelastic half-space soil medium with variable properties under generalized thermoelasticity theory were investigated in this study. By remaining faithful to Biot’s theory of dynamic poroelasticity, we idealized the foundation material as a uniform, fully saturated, poroelastic half-space medium. We first subjected this medium to time harmonic loads consisting of normal or thermal loads, then investigated the differences between the coupled thermohydro-mechanical dynamic models and the thermo-elastic dynamic models. We used normal mode analysis to solve the resulting non-dimensional coupled equations, then investigated the effects that non-dimensional vertical displacement, excess pore water pressure, vertical stress, and temperature distribution exerted on the poroelastic half-space medium and represented them graphically.

  13. What Is Robustness?: Problem Framing Challenges for Water Systems Planning Under Change

    Science.gov (United States)

    Herman, J. D.; Reed, P. M.; Zeff, H. B.; Characklis, G. W.

    2014-12-01

    Water systems planners have long recognized the need for robust solutions capable of withstanding deviations from the conditions for which they were designed. Faced with a set of alternatives to choose from—for example, resulting from a multi-objective optimization—existing analysis frameworks offer competing definitions of robustness under change. Robustness analyses have moved from expected utility to exploratory "bottom-up" approaches in which vulnerable scenarios are identified prior to assigning likelihoods; examples include Robust Decision Making (RDM), Decision Scaling, Info-Gap, and Many-Objective Robust Decision Making (MORDM). We propose a taxonomy of robustness frameworks to compare and contrast these approaches, based on their methods of (1) alternative selection, (2) sampling of states of the world, (3) quantification of robustness measures, and (4) identification of key uncertainties using sensitivity analysis. Using model simulations from recent work in multi-objective urban water supply portfolio planning, we illustrate the decision-relevant consequences that emerge from each of these choices. Results indicate that the methodological choices in the taxonomy lead to substantially different planning alternatives, underscoring the importance of an informed definition of robustness. We conclude with a set of recommendations for problem framing: that alternatives should be searched rather than prespecified; dominant uncertainties should be discovered rather than assumed; and that a multivariate satisficing measure of robustness allows stakeholders to achieve their problem-specific performance requirements. This work highlights the importance of careful problem formulation, and provides a common vocabulary to link the robustness frameworks widely used in the field of water systems planning.

  14. Perceptual Learning in Early Mathematics: Interacting with Problem Structure Improves Mapping, Solving and Fluency

    Science.gov (United States)

    Thai, Khanh-Phuong; Son, Ji Y.; Hoffman, Jessica; Devers, Christopher; Kellman, Philip J.

    2014-01-01

    Mathematics is the study of structure but students think of math as solving problems according to rules. Students can learn procedures, but they often have trouble knowing when to apply learned procedures, especially to problems unlike those they trained with. In this study, the authors rely on the psychological mechanism of perceptual learning…

  15. Single Machine Problem with Multi-Rate-Modifying Activities under a Time-Dependent Deterioration

    Directory of Open Access Journals (Sweden)

    M. Huang

    2013-01-01

    Full Text Available The single machine scheduling problem with multi-rate-modifying activities under a time-dependent deterioration to minimize makespan is studied. After examining the characteristics of the problem, a number of properties and a lower bound are proposed. A branch and bound algorithm and a heuristic algorithm are used in the solution, and two special cases are also examined. The computational experiments show that, for the situation with a rate-modifying activity, the proposed branch and bound algorithm can solve situations with 50 jobs within a reasonable time, and the heuristic algorithm can obtain the near-optimal solution with an error percentage less than 0.053 in a very short time. In situations with multi-rate-modifying activities, the proposed branch and bound algorithm can solve the case with 15 jobs within a reasonable time, and the heuristic algorithm can obtain the near-optimal with an error percentage less than 0.070 in a very short time. The branch and bound algorithm and the heuristic algorithm are both shown to be efficient and effective.

  16. Cascading peer dynamics underlying the progression from problem behavior to violence in early to late adolescence.

    Science.gov (United States)

    Dishion, Thomas J; Véronneau, Marie-Hélène; Myers, Michael W

    2010-08-01

    This study examined the peer dynamics linking early adolescent problem behavior, school marginalization, and low academic performance to multiple indices of late adolescent violence (arrests, parent report, and youth report) in an ethnically diverse sample of 998 males and females. A cascade model was proposed in which early adolescent risk factors assessed at age 11 to 12 predict gang involvement at age 13 to 14, which in turn, predicts deviancy training with friends at age 16 to 17, which then predicts violence by age 18 to 19. Each construct in the model was assessed with multiple measures and methods. Structural equation modeling revealed that the cascade model fit the data well, with problem behavior, school marginalization, and low academic performance significantly predicting gang involvement 2 years later. Gang involvement, in turn, predicted deviancy training with a friend, which predicted violence. The best fitting model included an indirect and direct path between early adolescent gang involvement and later violence. These findings suggest the need to carefully consider peer clustering into gangs in efforts to prevent individual and aggregate levels of violence, especially in youths who may be disengaged, marginalized, or academically unsuccessful in the public school context.

  17. Unraveling the Molecular Mechanisms Underlying the Nasopharyngeal Bacterial Community Structure

    Directory of Open Access Journals (Sweden)

    Wouter A. A. de Steenhuijsen Piters

    2016-03-01

    Full Text Available The upper respiratory tract is colonized by a diverse array of commensal bacteria that harbor potential pathogens, such as Streptococcus pneumoniae. As long as the local microbial ecosystem—also called “microbiome”—is in balance, these potentially pathogenic bacterial residents cause no harm to the host. However, similar to macrobiological ecosystems, when the bacterial community structure gets perturbed, potential pathogens can overtake the niche and cause mild to severe infections. Recent studies using next-generation sequencing show that S. pneumoniae, as well as other potential pathogens, might be kept at bay by certain commensal bacteria, including Corynebacterium and Dolosigranulum spp. Bomar and colleagues are the first to explore a specific biological mechanism contributing to the antagonistic interaction between Corynebacterium accolens and S. pneumoniae in vitro [L. Bomar, S. D. Brugger, B. H. Yost, S. S. Davies, K. P. Lemon, mBio 7(1:e01725-15, 2016, doi:10.1128/mBio.01725-15]. The authors comprehensively show that C. accolens is capable of hydrolyzing host triacylglycerols into free fatty acids, which display antipneumococcal properties, suggesting that these bacteria might contribute to the containment of pneumococcus. This work exemplifies how molecular epidemiological findings can lay the foundation for mechanistic studies to elucidate the host-microbe and microbial interspecies interactions underlying the bacterial community structure. Next, translation of these results to an in vivo setting seems necessary to unveil the magnitude and importance of the observed effect in its natural, polymicrobial setting.

  18. The Role of Content Knowledge in Ill-Structured Problem Solving for High School Physics Students

    Science.gov (United States)

    Milbourne, Jeff; Wiebe, Eric

    2018-02-01

    While Physics Education Research has a rich tradition of problem-solving scholarship, most of the work has focused on more traditional, well-defined problems. Less work has been done with ill-structured problems, problems that are better aligned with the engineering and design-based scenarios promoted by the Next Generation Science Standards. This study explored the relationship between physics content knowledge and ill-structured problem solving for two groups of high school students with different levels of content knowledge. Both groups of students completed an ill-structured problem set, using a talk-aloud procedure to narrate their thought process as they worked. Analysis of the data focused on identifying students' solution pathways, as well as the obstacles that prevented them from reaching "reasonable" solutions. Students with more content knowledge were more successful reaching reasonable solutions for each of the problems, experiencing fewer obstacles. These students also employed a greater variety of solution pathways than those with less content knowledge. Results suggest that a student's solution pathway choice may depend on how she perceives the problem.

  19. Using a Semantic Diagram to Structure a Collaborative Problem Solving Process in the Classroom

    Science.gov (United States)

    Cai, Huiying; Lin, Lin; Gu, Xiaoqing

    2016-01-01

    This study provides an in-depth look into the implementation process of visualization-based tools for structuring collaborative problem solving (CPS) in the classroom. A visualization-based learning platform--the semantic diagram for structuring CPS in a real classroom was designed and implemented. Metafora, the preliminary vehicle of the semantic…

  20. A Hamiltonian perturbation theory for coherent structures illustrated to wave problems

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Mielke, A.; Kirchgässner, K.

    1995-01-01

    In wave problems with a Hamiltonian structure and some symmetry property, the relative equilibria are the physical coherent structures. They appear as families of states, parameterized by physical observables connected to the symmetry. A new abstract (and general) result about the relation between

  1. Opportunity Structure for Gambling and Problem Gambling among Employees in the Transport Industry

    Science.gov (United States)

    Revheim, Tevje; Buvik, Kristin

    2009-01-01

    Working conditions for employees in the transport sector might present an opportunity structure for gambling by providing access to gambling during the workday. This study investigates connections between opportunity structure, gambling during the workday, and gambling problems among employees in the transport sector. Data has been collected from…

  2. From childhood adversity to problem behaviors: Role of psychological and structural social integration.

    Science.gov (United States)

    Chao, Lo-Hsin; Tsai, Meng-Che; Liang, Ya-Lun; Strong, Carol; Lin, Chung-Ying

    2018-01-01

    Childhood adversity (CA) is associated with problem behaviors in adolescence, but the mediators, that is, those factors that help build resilience and prevent some children who experience CA from engaging in problem behaviors, await more exploration, including social integration. The aim of this study was to identify the association between CA and adolescent problem behaviors, and to further examine the mediating role of social integration distinctly as psychological and structural integration. Data used were from the Taiwan Education Panel Survey, a core panel of 4,261 students (age 13) surveyed in 2001 and followed for three more waves until age 18. For psychological integration, an average score was calculated to represent adolescents' feelings about their school. Structural integration was constructed using several items about adolescents' school and extracurricular activities. We used structural equation modeling with the diagonally weighted least squares method to examine the effect of CA on the primary outcome: adolescent problem behaviors via social integration. The hypothesized structural equation model specifying the path from CA to adolescent problem behavior had good fit. Respondents with one CA were indirectly linked to problem behaviors via psychological but not structural integration (e.g. the level of participation in school and non-school activities). On mediation analysis, psychological integration significantly mediated the paths from one CA to all six problem behaviors (all P integration; two or more CA were not associated with significant paths to problem behaviors. The contribution of social integration is crucial to an adolescent's development from CA to problem behaviors. To form supportive social relationships to achieve better health, we suggest that those adolescents who have been exposed to CA should be helped to join more teams and take part in more activities, thereby increasing their opportunities for social interaction, and improving

  3. The Network Structure Underlying the Earth Observation Assessment

    Science.gov (United States)

    Vitkin, S.; Doane, W. E. J.; Mary, J. C.

    2017-12-01

    The Earth Observations Assessment (EOA 2016) is a multiyear project designed to assess the effectiveness of civil earth observation data sources (instruments, sensors, models, etc.) on societal benefit areas (SBAs) for the United States. Subject matter experts (SMEs) provided input and scored how data sources inform products, product groups, key objectives, SBA sub-areas, and SBAs in an attempt to quantify the relationships between data sources and SBAs. The resulting data were processed by Integrated Applications Incorporated (IAI) using MITRE's PALMA software to create normalized relative impact scores for each of these relationships. However, PALMA processing obscures the natural network representation of the data. Any network analysis that might identify patterns of interaction among data sources, products, and SBAs is therefore impossible. Collaborating with IAI, we cleaned and recreated a network from the original dataset. Using R and Python we explore the underlying structure of the network and apply frequent itemset mining algorithms to identify groups of data sources and products that interact. We reveal interesting patterns and relationships in the EOA dataset that were not immediately observable from the EOA 2016 report and provide a basis for further exploration of the EOA network dataset.

  4. Structure activity relationships to assess new chemicals under TSCA

    Energy Technology Data Exchange (ETDEWEB)

    Auletta, A.E. [Environmental Protection Agency, Washington, DC (United States)

    1990-12-31

    Under Section 5 of the Toxic Substances Control Act (TSCA), manufacturers must notify the US Environmental Protection Agency (EPA) 90 days before manufacturing, processing, or importing a new chemical substance. This is referred to as a premanufacture notice (PMN). The PMN must contain certain information including chemical identity, production volume, proposed uses, estimates of exposure and release, and any health or environmental test data that are available to the submitter. Because there is no explicit statutory authority that requires testing of new chemicals prior to their entry into the market, most PMNs are submitted with little or no data. As a result, EPA has developed special techniques for hazard assessment of PMN chemicals. These include (1) evaluation of available data on the chemical itself, (2) evaluation of data on analogues of the PMN, or evaluation of data on metabolites or analogues of metabolites of the PMN, (3) use of quantitative structure activity relationships (QSARs), and (4) knowledge and judgement of scientific assessors in the interpretation and integration of the information developed in the course of the assessment. This approach to evaluating potential hazards of new chemicals is used to identify those that are most in need of addition review of further testing. It should not be viewed as a replacement for testing. 4 tabs.

  5. Interevent relationships and judgment under uncertainty: structure determines strategy.

    Science.gov (United States)

    Sanfey, Alan G; Hastie, Reid

    2002-09-01

    A fundamental empirical question regarding judgments about events is whether experienced absolute frequencies or relative frequencies are relied on when the likelihood of a particular occurrence is judged. The present research explicates the conditions under which people rely on remembered raw absolute frequencies versus on inferred relative frequencies or proportions when making predictions. Participants saw opinion poll results for candidates prior to an election and, on the basis of these, made judgments concerning the likelihood of each candidate's winning this election. Certain candidates demonstrated a high absolute frequency of winning in the polls, whereas other candidates had high relative win frequencies. The results indicated that adults are cognitively flexible with regard to the inputs used in this judgment. Certain stimulus event configurations induced reasoning by way of absolute frequencies, whereas other configurations elicited judgments based on relative frequencies. More specifically, as the relational complexity of the event structure increased and more inferences were required to make predictions, the tendency to rely on absolute, as opposed to relative, frequencies also increased.

  6. Sub-fragmentation of structural reactive material casings under explosion

    Science.gov (United States)

    Zhang, Fan; Gauthier, Maxime; Cojocaru, Cristian

    2017-01-01

    A concept of reactive hot spots intruded in a thick, structural reactive material casing was investigated to generate fine fragments for efficient energy release from casing material under explosive loading. This was achieved through distributing micro MoO3 particles into a granular Al casing, made by hot isostatic pressing, in a fuel-rich ratio of 10Al+MoO3. Reaction of Al and MoO3 during casing primary or secondary fragmentation creates heat and gas products to form micro-scale hot spots, whose expansion initiates local fractures leading to fine fragments of the rest of Al. Explosion experiments, using a 4.4 cm diameter cased charge with a casing-to-explosive mass ratio of 1.78 in a 2.1 m3 cylindrical chamber, demonstrated the presence of fine fragments and more efficient fragment combustion to augment air blast, as compared to a baseline pure Al-cased charge, thus indicating the feasibility of the concept.

  7. Sexual dysfunction and the underlying medical problems in post-menopausal women

    Directory of Open Access Journals (Sweden)

    Soheila Nazarpour

    2016-02-01

    Full Text Available Background: Sexual dysfunction could be under the influence of some underlying medical problems. The purpose of this study is to examine the relationship between medical problems and sexual function in post-menopausal women. Methods: This is a community-based, descriptive-correlation study of 405 post-menopausal women residing in Chalus and Nowshahr cities, North of Iran, aged 40 to 65 years old from October 2013 to May 2014. A multistage, randomized sampling was conducted. The data was acquired through interviews using the Female Sexual Function Index (FSFI questionnaire and a researcher-made questionnaire, and was analyzed using descriptive and analytical tests such as multiple linear regression and logistic regression models. Results: 51.4% of the subjects had medical conditions. Cardiovascular disorders were the most common diseases among the subjects. 61% of the women were suffering from female sexual dysfunction (FSD. Sexual dysfunction in patients with medical conditions was significantly higher (P= 0.037. Scores of arousal (P= 0.000, orgasm (P= 0.018, and satisfaction (P= 0.026, as well as the FSFI total score (P= 0.005, were significantly lower in subjects with cardiovascular disorders. Scores of desire (P= 0.001, arousal (P= 0.006, lubrication (P= 0.010, orgasm (P= 0.004, and satisfaction (P= 0.022, as well as the FSFI total score (P= 0.017, were significantly lower in subjects with diabetes. Scores of pain were significantly lower in subjects with musculoskeletal disorders (P= 0.041, they experienced more pain during intercourse. In domains of arousal (P= 0.030, satisfaction (P= 0.040, and pain (P= 0.044, the scores of those taking antihypertensive medications were significantly lower than the scores of the rest of the subjects. Scores of desire (P= 0.001, arousal (P= 0.006, orgasm (P= 0.006, and satisfaction (P= 0.048, as well as the FSFI total score (P= 0.006, were significantly lower in those taking antidiabetic drugs. And lastly

  8. An ALE formulation of embedded boundary methods for tracking boundary layers in turbulent fluid-structure interaction problems

    Science.gov (United States)

    Farhat, Charbel; Lakshminarayan, Vinod K.

    2014-04-01

    Embedded Boundary Methods (EBMs) for Computational Fluid Dynamics (CFD) are usually constructed in the Eulerian setting. They are particularly attractive for complex Fluid-Structure Interaction (FSI) problems characterized by large structural motions and deformations. They are also critical for flow problems with topological changes and FSI problems with cracking. For all of these problems, the alternative Arbitrary Lagrangian-Eulerian (ALE) methods are often unfeasible because of the issue of mesh crossovers. However for viscous flows, Eulerian EBMs for CFD do not track the boundary layers around dynamic rigid or flexible bodies. Consequently, the application of these methods to viscous FSI problems requires either a high mesh resolution in a large part of the computational fluid domain, or adaptive mesh refinement. Unfortunately, the first option is computationally inefficient, and the second one is labor intensive. For these reasons, an alternative approach is proposed in this paper for maintaining all moving boundary layers resolved during the simulation of a turbulent FSI problem using an EBM for CFD. In this approach, which is simple and computationally reasonable, the underlying non-body-fitted mesh is rigidly translated and/or rotated in order to track the rigid component of the motion of the dynamic obstacle. Then, the flow computations away from the embedded surface are performed using the ALE framework, and the wall boundary conditions are treated by the chosen Eulerian EBM for CFD. Hence, the solution of the boundary layer tracking problem proposed in this paper can be described as an ALE implementation of a given EBM for CFD. Its basic features are illustrated with the Large Eddy Simulation using a non-body-fitted mesh of a turbulent flow past an airfoil in heaving motion. Its strong potential for the solution of challenging FSI problems at reasonable computational costs is also demonstrated with the simulation of turbulent flows past a family of

  9. Responses of discretized systems under narrow band nonstationary random excitations. Part 1: linear problems

    Science.gov (United States)

    Chen, Z.; To, C. W. S.

    2005-10-01

    The extended stochastic central difference (ESCD) method is proposed as a viable alternative for computing linear responses of discretized multi-degrees-of-freedom (mdof) systems under narrow band stationary and nonstationary random disturbances. The method provides a means of controlling the center frequencies and bandwidths of narrow band stationary and nonstationary random excitation processes. It is suitable for larger-scale random response analysis of complicated structures idealized by the finite element method. Its additional important feature is that application of normal mode or complex normal mode analysis or direct numerical integration algorithms such as the fourth-order Runge-Kutta scheme is not required. Examples, including one of flow-induced vibration of a pipe containing a moving fluid are included to demonstrate: (1) the capability of the proposed method and difference between responses of discretized systems under narrow band and wide band random excitations, and (2) its accuracy and efficiency by way of comparison to the Monte Carlo simulation data. Generalization of the ESCD method for computation of responses of nonlinear mdof systems is presented in a companion paper.

  10. Problems and their solutions in practical application of Eurocodes in seismic design of RC structures

    Directory of Open Access Journals (Sweden)

    Milev Jordan

    2016-01-01

    Full Text Available The main purpose of the paper is to present practical application of Eurocodes in the field of RC structures design. The selected examples represent the main problems in practical application of Eurocodes for seismic analysis and design of RC Structures in Bulgarian construction practice. The analysis is focused on some structural and economic problems as well as on some contradictions in Eurocode 8 itself. Special attention is paid to the practical solution of the following problems: recognition of torsionally flexible systems, stiffness reduction of RC elements for linear analysis dimensions and detailing of confined boundary areas of shear walls, detailing of wall structures, etc. Those problems appear during the practical design of some buildings in Bulgaria. Several proposals for solving some problems defined in the paper are presented through some practical examples. Some conclusions are made for further application of Eurocode 8 in the design and construction practice. The importance of some rules and procedures in Eurocode 8 is supported by the examples of damaged RC members during the past earthquakes. The problems of Eurocode 8 and their solutions are illustrated through the experience of Bulgarian construction practice.

  11. Go East: Differences between Poland and Western European countries in the motivational structures underlying seafood consumption

    DEFF Research Database (Denmark)

    Scholderer, Joachim; Brunsø, Karen; Olsen, Svein Ottar

    Central Europe is an emerging market for seafood products, with rapidly developing opportunities for foreign direct investment and export. Although Poland in particular is widely regarded as a land of opportunity in the seafood business, surprisingly little effort has been made until now to gain...... and compared in terms of the motivational structures underlying seafood consumption. In Poland, intentions to consume seafood in the near future were mainly determined by the perceived difficulty of preparing fish dishes (problems with bone handling and smells) and the degree to which consumers believed...... they had the necessary cooking skills. The preferences of consumers and their household members had a much weaker but still significant impact on intentions. In the comparison samples from Western Europe, motivational structures varied considerably. The highest degree of similarity with Poland was found...

  12. MOQPSO-D/S for Air and Missile Defense WTA Problem under Uncertainty

    Directory of Open Access Journals (Sweden)

    Hao Xu

    2017-01-01

    Full Text Available Aiming at the shortcomings of single objective optimization for solving weapon target assignment (WTA and the existing multiobjective optimization based WTA method having problems being applied in air and missile defense combat under uncertainty, a fuzzy multiobjective programming based WTA method was proposed to enhance the adaptability of WTA decision to the changes of battlefield situation. Firstly, a multiobjective quantum-behaved particle swarm optimization with double/single-well (MOQPSO-D/S algorithm was proposed by adopting the double/single-well based position update method, the hybrid random mutation method, and the two-stage based guider particles selection method. Secondly, a fuzzy multiobjective programming WTA model was constructed with consideration of air and missile defense combat’s characteristics. And, the uncertain WTA model was equivalently clarified based on the necessity degree principle of uncertainty theory. Thirdly, with particles encoding and illegal particles adjusting, the MOQPSO-D/S algorithm was adopted to solve the fuzzy multiobjective programming based WTA model. Finally, example simulation was conducted, and the result shows that the WTA model constructed is rational and MOQPSO-D/S algorithm is efficient.

  13. Rewarding Multitasking: Negative Effects of an Incentive on Problem Solving under Divided Attention

    Science.gov (United States)

    Wieth, Mareike B.; Burns, Bruce D.

    2014-01-01

    Research has consistently shown negative effects of multitasking on tasks such as problem solving. This study was designed to investigate the impact of an incentive when solving problems in a multitasking situation. Incentives have generally been shown to increase problem solving (e.g., Wieth & Burns, 2006), however, it is unclear whether an…

  14. An Examination of the Personality Constructs Underlying Dimensions of Creative Problem-Solving Style

    Science.gov (United States)

    Isaksen, Scott G.; Kaufmann, Astrid H.; Bakken, Bjørn T.

    2016-01-01

    This study investigated the personality facets that underpin the construct of problem-solving style, particularly when approaching more creative kinds of problem-solving. Cattell's Sixteen Personality Factors Questionnaire and VIEW--An Assessment of Problem Solving Style were administered to 165 students from the Norwegian Business School. We…

  15. Studies on Pounding Response Considering Structure-Soil-Structure Interaction under Seismic Loads

    Directory of Open Access Journals (Sweden)

    Peizhen Li

    2017-12-01

    Full Text Available Pounding phenomena considering structure–soil–structure interaction (SSSI under seismic loads are investigated in this paper. Based on a practical engineering project, this work presents a three-dimensional finite element numerical simulation method using ANSYS software. According to Chinese design code, the models of adjacent shear wall structures on Shanghai soft soil with the rigid foundation, box foundation and pile foundation are built respectively. In the simulation, the Davidenkov model of the soil skeleton curve is assumed for soil behavior, and the contact elements with Kelvin model are adopted to simulate pounding phenomena between adjacent structures. Finally, the dynamic responses of adjacent structures considering the pounding and SSSI effects are analyzed. The results show that pounding phenomena may occur, indicating that the seismic separation requirement for adjacent buildings of Chinese design code may not be enough to avoid pounding effect. Pounding and SSSI effects worsen the adjacent buildings’ conditions because their acceleration and shear responses are amplified after pounding considering SSSI. These results are significant for studying the effect of pounding and SSSI phenomena on seismic responses of structures and national sustainable development, especially in earthquake prevention and disaster reduction.

  16. Reconstruction of ancestral RNA sequences under multiple structural constraints

    OpenAIRE

    Tremblay-Savard, Olivier; Reinharz, Vladimir; Waldisp?hl, J?r?me

    2016-01-01

    Background Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA) families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. Methods In this paper, we introduce achARNement, a maximum parsimony approach that, given...

  17. Interface stability of granular filter structures under currents

    NARCIS (Netherlands)

    Verheij, H.J.; Hoffmans, G.; Dorst, K.; Van de Sande, S.

    2012-01-01

    Granular filters are used for protection of structures against scour and erosion. For a proper functioning it is necessary that the interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil

  18. Optimization and anti-optimization of structures under uncertainty

    National Research Council Canada - National Science Library

    Elishakoff, Isaac; Ohsaki, Makoto

    2010-01-01

    .... The necessity of anti-optimization approach is first demonstrated, then the anti-optimization techniques are applied to static, dynamic and buckling problems, thus covering the broadest possible set of applications...

  19. Site response - a critical problem in soil-structure interaction analyses for embedded structures

    International Nuclear Information System (INIS)

    Seed, H.B.; Lysmer, J.

    1986-01-01

    Soil-structure interaction analyses for embedded structures must necessarily be based on a knowledge of the manner in which the soil would behave in the absence of any structure - that is on a knowledge and understanding of the spatial distribution of motions in the ground within the depth of embedment of the structure. The nature of these spatial variations is discussed and illustrated by examples of recorded motions. It is shown that both the amplitude of peak acceleration and the form of the acceleration response spectrum for earthquake motions will necessarily vary with depth and failure to take these variations into account may introduce an unwarranted degree of conservatism into the soil-structure interaction analysis procedure

  20. Psychosocial Problems Among Truant Youth: A Multi-Group, Exploratory Structural Equation Modeling Analysis.

    Science.gov (United States)

    Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

    2012-01-01

    Truant youth represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining co-morbid problem behaviors. The present study addresses the need to examine the interrelationships of multiple domains of psychosocial functioning, including substance involvement, mental health, and delinquency, among truant youth. Exploratory structural equation modeling on baseline data collected on 219 truant youths identified two major factors reflecting psychosocial functioning, and found the factor structure was similar across major sociodemographic subgroups. Further analyses supported the validity of the factor structure. The research and service delivery implications of the findings are discussed.

  1. Sex differences in the interacting roles of impulsivity and positive alcohol expectancy in problem drinking: A structural brain imaging study

    Directory of Open Access Journals (Sweden)

    Jaime S. Ide

    2017-01-01

    Full Text Available Alcohol expectancy and impulsivity are implicated in alcohol misuse. However, how these two risk factors interact to determine problem drinking and whether men and women differ in these risk processes remain unclear. In 158 social drinkers (86 women assessed for Alcohol Use Disorder Identification Test (AUDIT, positive alcohol expectancy, and Barratt impulsivity, we examined sex differences in these risk processes. Further, with structural brain imaging, we examined the neural bases underlying the relationship between these risk factors and problem drinking. The results of general linear modeling showed that alcohol expectancy best predicted problem drinking in women, whereas in men as well as in the combined group alcohol expectancy and impulsivity interacted to best predict problem drinking. Alcohol expectancy was associated with decreased gray matter volume (GMV of the right posterior insula in women and the interaction of alcohol expectancy and impulsivity was associated with decreased GMV of the left thalamus in women and men combined and in men alone, albeit less significantly. These risk factors mediated the correlation between GMV and problem drinking. Conversely, models where GMV resulted from problem drinking were not supported. These new findings reveal distinct psychological factors that dispose men and women to problem drinking. Although mediation analyses did not determine a causal link, GMV reduction in the insula and thalamus may represent neural phenotype of these risk processes rather than the consequence of alcohol consumption in non-dependent social drinkers. The results add to the alcohol imaging literature which has largely focused on dependent individuals and help elucidate alterations in brain structures that may contribute to the transition from social to habitual drinking.

  2. THE PROBLEM OF THE FEASIBILITY STUDY IN RESPECT OF DESIGN OF JOINTS OF METAL STRUCTURES

    Directory of Open Access Journals (Sweden)

    Morozova Dina Vol'demarovna

    2012-12-01

    It is noteworthy that this problem enjoyed much attention back in the past when the country suffered from steel deficit, and metal processing plants could not keep up with the needs of consumers. This problem was dealt with by Y.M. Lihtarnikov, a Soviet scientist, who published his work "Variant design and optimization of steel structures" in 1979. The authors employ the theoretical base developed by the scientist to perform their research into the optimum solutions to the problems of several types of metal joints.

  3. Concrete Mix Design for Service Life of RC Structures under Carbonation Using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Seung-Jun Kwon

    2014-01-01

    Full Text Available Steel corrosion in reinforced concrete (RC structure is such a critical problem to structural safety that many researches have been performed for maintaining required performance during intended service life. This paper is for a numerical technique for obtaining optimum concrete mix proportions through genetic algorithm (GA for RC structures under carbonation which is considered as a serious deterioration in underground sites and big cities. For this study, mix proportions and CO2 diffusion coefficients are analyzed through the previous studies, and then the fitness function of CO2 diffusion coefficient is derived through regression analysis. The fitness function from 69 test results includes 5 variables of mix proportions such as w/c (water to cement ratio, cement content, sand content percentage, coarse aggregate content, and R.H. (relative humidity. Through GA technique, simulated mix proportions are obtained for 12 cases of verification and they show reasonable results with average relative error of 4.6%. Assuming intended service life and design parameters, intended CO2 diffusion coefficients and cement contents are determined and then related mix proportions are simulated. The proposed technique can provide initial concrete mix proportions which satisfy service life under carbonation.

  4. A vorticity based approach to handle the fluid-structure interaction problems

    Energy Technology Data Exchange (ETDEWEB)

    Farahbakhsh, Iman; Ghassemi, Hassan [Department of Ocean Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sabetghadam, Fereidoun, E-mail: i.farahbakhsh@aut.ac.ir [Mechanical and Aerospace Engineering Department, Science and Research Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of)

    2016-02-15

    A vorticity based approach for the numerical solution of the fluid-structure interaction problems is introduced in which the fluid and structure(s) can be viewed as a continuum. Retrieving the vorticity field and recalculating a solenoidal velocity field, specially at the fluid-structure interface, are the kernel of the proposed algorithm. In the suggested method, a variety of constitutive equations as a function of left Cauchy–Green deformation tensor can be applied for modeling the structure domain. A nonlinear Mooney–Rivlin and Saint Venant–Kirchhoff model are expressed in terms of the left Cauchy–Green deformation tensor and the presented method is able to model the behavior of a visco-hyperelastic structure in the incompressible flow. Some numerical experiments, with considering the neo-Hookean model for structure domain, are executed and the results are validated via the available results from literature. (paper)

  5. Exploring Interface Problems in Taiwan’s Construction Projects Using Structural Equation Modeling

    Directory of Open Access Journals (Sweden)

    Chien-Liang Lin

    2017-05-01

    Full Text Available Construction projects are complex systems that inherently contain complex interface problems. This study explored the root causes of interface problems in construction projects using structural equation modeling. This technique is a systematic approach that combines factor analysis and path analysis to investigate the causal relationships among multidimensional factors. The literature on construction interface problems was reviewed, and a questionnaire survey was conducted in Taiwan to identify 27 initial factors that cause interface problems in three dimensions: owner, design, and construction. Then, a series of structural equation models (SEMs was developed to further explore the root causes of the interface problems and their causal relationships. This study has three main findings: (1 poor design causes interface problems; (2 ineffective communication and coordination among the owner, design, and construction dimensions are the main factors that cause construction interface problems; and (3 a lack of communication and coordination has a greater influence on the construction dimension than on the owner and design dimensions. The above findings can be used as important references and sustainable management strategies for academia and decision-makers in the construction industry.

  6. Optimization and anti-optimization of structures under uncertainty

    National Research Council Canada - National Science Library

    Elishakoff, Isaac; Ohsaki, Makoto

    2010-01-01

    The volume presents a collaboration between internationally recognized experts on anti-optimization and structural optimization, and summarizes various novel ideas, methodologies and results studied over 20 years...

  7. Severe childhood obesity: an under-recognised and growing health problem.

    Science.gov (United States)

    Bass, Rosara; Eneli, Ihuoma

    2015-11-01

    Childhood obesity is a serious and urgent public health problem. In the last 10 years, there has been a concerted effort in the USA and globally to develop and implement educational, medical and public health interventions designed to attenuate its growth. The success of these efforts was probably responsible for the plateau in the prevalence rate of childhood obesity noted in the last two years. While the attenuation of the overall prevalence of childhood obesity is promising, data from the same cohort reveal a concerning upward trend in the number of children with severe obesity. The consequences of severe childhood obesity can be devastating. When compared to their moderately obese peers, children with severe obesity are at greater risk for adult obesity, early atherosclerosis, hypertension, type 2 diabetes, metabolic syndrome, fatty liver disease and premature death. The determinants for severe obesity include the same lifestyle, environmental, familial and societal risk factors reported for overweight or obesity. While all these risk factors must be screened for, genetic influences are distinct considerations that may have greater bearing especially with early-onset obesity. Treatments for severe childhood obesity include lifestyle intervention, specialised low-calorie diets and bariatric surgery. Outcomes of these treatments vary, with bariatric surgery clearly the most successful of the three for both short-term and long-term weight loss. Severe obesity in children and adolescents remains a challenging health condition. The enormous medical, emotional and financial burden these children and their families endure signals an urgent need to further investigate and standardise treatment modalities and improve outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  8. Event-based home safety problem detection under the CPS home safety architecture

    OpenAIRE

    Yang, Zhengguo; Lim, Azman Osman; Tan, Yasuo

    2013-01-01

    This paper presents a CPS(Cyber-physical System) home safety architecture for home safety problem detection and reaction and shows some example cases. In order for home safety problem detection, there are three levels of events defined: elementary event, semantic event and entire event, which representing the meaning from parameter to single safety problem, and then the whole safety status of a house. For the relationship between these events and raw data, a Finite State Machine (FSM) based m...

  9. Peak earthquake response of structures under multi-component excitations

    Science.gov (United States)

    Song, Jianwei; Liang, Zach; Chu, Yi-Lun; Lee, George C.

    2007-12-01

    Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multi-directional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artificial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.

  10. Structural convergence under reversible and irreversible monetary unification

    NARCIS (Netherlands)

    Beetsma, R.M.W.J.; Jensen, H.

    2003-01-01

    We explore endogenous monetary unification in the context of a model in which a country with serious structural distortions (and, hence, high inflation) is admitted into a monetary union once its economic structure has converged sufficiently towards that of the existing participants. If unification

  11. Structural convergence under reversible and irreversible monetary unification

    NARCIS (Netherlands)

    Beetsma, R.M.W.J.; Jensen, H.

    1999-01-01

    We explore endogenous monetary unification in the context of a model in which a country with serious structural distortions (and, hence, high inflation) is admitted into a monetary union once its economic structure has converged sufficiently towards that of the existing participants. If unification

  12. Analysis Of Masonry Infilled RC Frame Structures Under Lateral Loading

    Directory of Open Access Journals (Sweden)

    Barnaure Mircea

    2015-03-01

    Full Text Available Partition walls are often made of masonry in Romania. Although they are usually considered non-structural elements in the case of reinforced concrete framed structures, the infill panels contribute significantly to the seismic behaviour of the building. Their impact is difficult to assess, mainly because the interaction between the bounding frame and the infill is an intricate issue. This paper analyses the structural behaviour of a masonry infilled reinforced concrete frame system subjected to in - plane loading. Three numerical models are proposed and their results are compared in terms of stiffness and strength of the structure. The role of the openings in the infill panel on the behaviour is analysed and discussed. The effect of gaps between the frame and the infill on the structural behaviour is also investigated. Comparisons are made with the in-force Romanian and European regulations provisions.

  13. Electric Car Users’ Time of Charging Problem under Peak Load Pricing When Delay in Charging Time Involves Uncertain Cost

    DEFF Research Database (Denmark)

    Fetene, Gebeyehu Manie

    ). Peak load pricing (PLP) is an attempt to shift demand, or consumption of the good, to accommodate supply. While peak load problem and PLP are well documented in the literature, this paper, to the authors’ knowledge, is the first to analyze the EV users time of charg- ing decision problem under PLP...... such as electricity, transport (con- gestion), water and telecommunication. Linear and non-linear peak load pricing alternatives have been suggested to curb this problem, particularly when demand is cyclical (Mohsenian-Rad and Leon-Garcia, 2010; Tan and Varaiya, 1993; Chao et al., 1986; Finsinger; Roberts, 1979...... the battery becomes flat (which usually occurs when EV users return back to home from work at which energy consumption is also at its peak, and thus worsen the peak load problem) under uniform pricing of electricity even when they do not have planned trips. 2) Unless either the duration of time at which...

  14. A computational domain decomposition approach for solving coupled flow-structure-thermal interaction problems

    OpenAIRE

    Eugenio Aulisa; Sandro Manservisi; Padmanabhan Seshaiyer

    2009-01-01

    Solving complex coupled processes involving fluid-structure-thermal interactions is a challenging problem in computational sciences and engineering. Currently there exist numerous public-domain and commercial codes available in the area of Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD) and Computational Thermodynamics (CTD). Different groups specializing in modelling individual process such as CSD, CFD, CTD often come together to solve a complex coupled ap...

  15. Computational Error Estimates and Adaptive Processes for Some Nonlinear Structural Problems.

    Science.gov (United States)

    1981-07-01

    24] H. B. Keller, Global Homotopies and Newton Methods ,in "Recent Advances in Numerical Analysis " ed. by C. deBoor, G. H. Golub, Academic Press...649-662. [34] W. Rheinboldt, Numerical Analysis of Continuation Methods for Nonlinear Structural Problems, Computers and Structures 13, 1981, 103-114...type interest centers on an analysis of the shape and features of the equilibrium surface. After some general remarks about such surfaces and the

  16. Social problem solving among depressed adolescents is enhanced by structured psychotherapies

    Science.gov (United States)

    Dietz, Laura J.; Marshal, Michael P.; Burton, Chad M.; Bridge, Jeffrey A.; Birmaher, Boris; Kolko, David; Duffy, Jamira N.; Brent, David A.

    2014-01-01

    Objective Changes in adolescent interpersonal behavior before and after an acute course of psychotherapy were investigated as outcomes and mediators of remission status in a previously described treatment study of depressed adolescents. Maternal depressive symptoms were examined as moderators of the association between psychotherapy condition and changes in adolescents’ interpersonal behavior. Method Adolescents (n = 63, mean age = 15.6 years, 77.8% female, 84.1% Caucasian) engaged in videotaped interactions with their mothers before randomization to cognitive behavior therapy (CBT), systemic behavior family therapy (SBFT), or nondirective supportive therapy (NST), and after 12–16 weeks of treatment. Adolescent involvement, problem solving and dyadic conflict were examined. Results Improvements in adolescent problem solving were significantly associated with CBT and SBFT. Maternal depressive symptoms moderated the effect of CBT, but not SBFT, on adolescents’ problem solving; adolescents experienced increases in problem solving only when their mothers had low or moderate levels of depressive symptoms. Improvements in adolescents’ problem solving were associated with higher rates of remission across treatment conditions, but there were no significant indirect effects of SBFT on remission status through problem solving. Exploratory analyses revealed a significant indirect effect of CBT on remission status through changes in adolescent problem solving, but only when maternal depressive symptoms at study entry were low. Conclusions Findings provide preliminary support for problem solving as an active treatment component of structured psychotherapies for depressed adolescents and suggest one Pathway by which maternal depression may disrupt treatment efficacy for depressed adolescents treated with CBT. PMID:24491077

  17. Content-based music recommendation using underlying music preference structure

    NARCIS (Netherlands)

    Soleymani, Mohammad; Aljanaki, A.; Wiering, F.; Veltkamp, R.C.

    2015-01-01

    The cold start problem for new users or items is a great challenge for recommender systems. New items can be positioned within the existing items using a similarity metric to estimate their ratings. However, the calculation of similarity varies by domain and available resources. In this paper, we

  18. ZERO-2 - a general purpose computer program for fluid-structure interaction problems

    International Nuclear Information System (INIS)

    Brusa, L.; Ciacci, R.; Greco, A.

    1983-01-01

    The objective of this paper is to present a description of the main features of the finite element code ZERO-2, which allows the static and dynamic analysis of axisymmetric structures with non symmetrical loads, taking into account dynamic fluid-structure interaction effects. The structure is assumed to have an elastic behaviour and the acoustic approximation is made for the fluid. The liquid is considered as compressible and sloshing effects may be taken into account. The structural displacement field, the fluid pressure distribution and the applied loads are expanded as a Fourier series to describe circumferential variations, so that the problem is reduced to the solution of decoupled equations for the amplitude for the harmonic terms. The structure may be composed of thin and thick elements characterized by different nodal degrees of freedom. The static analysis may be performed with thermal loads and distributed or concentrated froces on the structure. The dynamic loading may consist of distributed or concentrated forces on the structure, prescribed pressures on some part of the fluid surface, prescribed forces on the structure, prescribed pressures on some part of the fluid surface, prescribed nodal displacements and seismic ground acceleration. The seismic response may be computed taking into account multiple support excitations acting both on the structure and on the fluid. The dynamic equilibrium equations are solved by means of the modal superposition method and in the case of fluid-structure interaction problems, the normal modes of the coupled system are used. One of the major problems to be considered when using modal superposition method, is the choice of an appropriate number of modes to have accurate results. (orig./GL)

  19. Audit in Belarus under new law and in new environment: first results, problems, prospects

    Directory of Open Access Journals (Sweden)

    S.L. Korotayev

    2016-07-01

    Full Text Available The article analyzes the first results of application of the new law of the Republic of Belarus «On audit activity» since the 01.01.2014. The authors identify the problems inherent in auditing, propose specific measures to solve these problems, and to create the necessary conditions for the further development of audit.

  20. Ground Liquefaction and Deformation Analysis of Breakwater Structures Under Earthquakes

    Directory of Open Access Journals (Sweden)

    Zhao Jie

    2016-10-01

    Full Text Available Ground liquefaction and deformation is one of the important causes that damage engineering structures. Chinese current code for seismic design of breakwater is based on the single-level seismic design method as well as code for port and water-way engineering. However, this code can not exactly reflect the seismic performance of breakwater structures which experience different seismic intensities. In this paper, the author used a finite difference software, namely, FLAC3D, to analyze the state and compute seismic responses of breakwater structure. The breakwater foundation’s pore pressure ratio and displacement due to different earthquake have been studied. And the result show that: Smaller earthquakes have little influence on serviceability of the foundation, and severe earthquakes can liquefy some parts of the foundation; In the latter case , obvious changes of pores and foundation displaces can be found. Particularly, when seismic peak acceleration reachs 0.2g, Liquefaction appears in the foundation and mainly concentrated in the upper right side of the structure. In addition, the survey of ultra-hole pressure and displacement values of sand layers of the breakwater, manifests when the ultra pore pressure near 1.0, displacement and overturning structure is relatively large, resulting in varying degrees of damage to the structure. This paper’s research can provide theoretical and designable reference for similar engineering structures

  1. DDeveloping and solving a bi-objective joint replenishment problem under storing space constraint

    Directory of Open Access Journals (Sweden)

    ommolbanin yousefi

    2011-03-01

    Full Text Available In this research, a bi-objective joint replenishment problem has been developed and solved with the assumption of one restricted resource. The proposed model has a storing space constraint and tries to optimize two objective functions simultaneously. They include minimizing annual holding and setup costs and minimizing annual inventory investment. Then, for solving this problem, a multi-objective genetic algorithm (MOGA has been developed. In order to analyze the algorithm efficiency, its performance has been examined in solving 1600 randomly produced problems using parameters extracted from literature. The findings imply that the proposed algorithm is capable of producing a good set of Pareto optimal solutions. Finally, the application of the problem solving approach and the findings of the proposed algorithm have been illustrated for a special problem, which has been randomly produced.

  2. The Examining Mathematical Word Problems Solving Ability under Efficient Representation Aspect

    Directory of Open Access Journals (Sweden)

    Maryam Sajadi

    2013-02-01

    Full Text Available Word problem solving is complex process for students. Efficient instruction of word problem solving needed to efficient strategies. One of these strategies is using representation. Some students apply key words or numbers only but when they face complex word problems then they cannot apply the keywords. Therefore teachers have to teach efficient strategy such as representation. In this research is tried whether using efficient representation can lead to efficient solution. Through cluster sampling method, forty one students are selected at girly elementary school. Through math exam, their solutions are studied. Through Spearman test, results indicate that there is significant relation between efficient representation and efficient word problem solving ability. At second grade, students have used of representation, have gotten to high means and inverse, students have not used of representation, have not gotten to high means. Therefore there is significant and direct relation between efficient representation and efficient word problem solving ability.

  3. Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack

    Science.gov (United States)

    Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

    2013-03-01

    Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

  4. Harvesting Energy from Vibrations of the Underlying Structure

    DEFF Research Database (Denmark)

    Han, Bo; Vssilaras, S; Papadias, C.B.

    2013-01-01

    The use of wireless sensors for structural health monitoring offers several advantages such as small size, easy installation and minimal intervention on existing structures. However the most significant concern about such wireless sensors is the lifetime of the system, which depends heavily...... to the long-term structural health of a building or bridge, but at the same time they can be exploited as a power source to power the wireless sensors that are monitoring this structural health. This paper presents a new energy harvesting method based on a vibration driven electromagnetic harvester. By using...... on the type of power supply. No matter how energy efficient the operation of a battery operated sensor is, the energy of the battery will be exhausted at some point. In order to achieve a virtually unlimited lifetime, the sensor node should be able to recharge its battery in an easy way. Energy harvesting...

  5. Localized Damage Process in Metal Structures Under High Velocity Deformation

    National Research Council Canada - National Science Library

    Vodenicharov, Stefan

    1999-01-01

    The ASB initiation and growth in high strength steel are investigated. An integrated energy theoretical approach is suggested for modeling ASB development and identifying post critical structure state in the bands...

  6. Determining wildlife use of wildlife crossing structures under different scenarios.

    Science.gov (United States)

    2012-05-01

    This research evaluated Utahs wildlife crossing structures to help UDOT and the Utah Division of Wildlife Resources assess crossing efficacy. In this study, remote motion-sensed cameras were used at 14 designated wildlife crossing culverts and bri...

  7. Performance based investigations of structural systems under fire

    DEFF Research Database (Denmark)

    Gentili, Filippo; Crosti, Chiara; Giuliani, Luisa

    2010-01-01

    Prescriptive measures and procedures developed over the past here are mostly aimed at preventing structural failures of single elements for the time required for the evacuation. The response to fire and fire effects of the structural system as a whole remains often unknown and the survival of the...... structures are presented and discussed, with particular attention to methodological aspects. The effects of different assumptions in the modeling and in the definition of the collapse are highlighted, as critical aspects of a performance-based investigation....... these kinds of events, the mitigation of possible collapse induced by fire should be achieved. In this respect, a performance-based investigation of the structure aimed at highlight fire effects and fire-induced collapse mechanisms becomes of interest. In the paper collapse mechanisms of some simple...

  8. Electric Car Users’ Time of Charging Problem under Peak Load Pricing When Delay in Charging Time Involves Uncertain Cost

    DEFF Research Database (Denmark)

    Fetene, Gebeyehu Manie

    such as electricity, transport (con- gestion), water and telecommunication. Linear and non-linear peak load pricing alternatives have been suggested to curb this problem, particularly when demand is cyclical (Mohsenian-Rad and Leon-Garcia, 2010; Tan and Varaiya, 1993; Chao et al., 1986; Finsinger; Roberts, 1979......). Peak load pricing (PLP) is an attempt to shift demand, or consumption of the good, to accommodate supply. While peak load problem and PLP are well documented in the literature, this paper, to the authors’ knowledge, is the first to analyze the EV users time of charg- ing decision problem under PLP...

  9. Structural analysis of reinforced concrete structures under monotonous and cyclic loadings: numerical aspects

    International Nuclear Information System (INIS)

    Lepretre, C.; Millard, A.; Nahas, G.

    1989-01-01

    The structural analysis of reinforced concrete structures is usually performed either by means of simplified methods of strength of materials type i.e. global methods, or by means of detailed methods of continuum mechanics type, i.e. local methods. For this second type, some constitutive models are available for concrete and rebars in a certain number of finite element systems. These models are often validated on simple homogeneous tests. Therefore, it is important to appraise the validity of the results when applying them to the analysis of a reinforced concrete structure, in order to be able to make correct predictions of the actual behaviour, under normal and faulty conditions. For this purpose, some tests have been performed at I.N.S.A. de Lyon on reinforced concrete beams, subjected to monotonous and cyclic loadings, in order to generate reference solutions to be compared with the numerical predictions given by two finite element systems: - CASTEM, developed by C.E.A./.D.E.M.T. - ELEFINI, developed by I.N.S.A. de Lyon

  10. Grid synchronization structure for wind converters under grid fault conditions

    OpenAIRE

    Garcia, Jose Ignacio; Candela García, José Ignacio; Luna Alloza, Álvaro; Catalan, Pedro

    2016-01-01

    This paper presents a grid synchronization structure for three-phase electric power systems based on the use of a filtered quadrature signal generator (FQSG) and a phase-locked loop (PLL) structure, named Adaptive Vector Grid Synchronization system (AVGS). This system estimates the magnitude, frequency and phase of a signal, specially three-phase voltages and currents, and allows fast and accurate detection of the symmetrical components meet with the transient operating requirements imposed b...

  11. Behavior of auxetic structures under compression and impact forces

    Science.gov (United States)

    Yang, Chulho; Vora, Hitesh D.; Chang, Young

    2018-02-01

    In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilize normal materials that follow Hooke’s law but still show the properties of negative Poisson’s ratios (NPR). One potential application is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industrial workers, law enforcement and military personnel, and athletes. This paper reports an integrated theoretical, computational, and experimental investigation conducted for typical auxetic materials that exhibit NPR properties. Parametric 3D CAD models of auxetic structures such as re-entrant hexagonal cells and arrowheads were developed. Then, key structural characteristics of protection pads were evaluated through static analyses of FEA models. Finally, impact analyses were conducted through dynamic simulations of FEA models to validate the results obtained from the static analyses. Efforts were also made to relate the individual and/or combined effect of auxetic structures and materials to the overall stiffness and shock-absorption performance of the protection pads. An advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic structures. Three different materials typically used for fused deposition modeling technology, namely polylactic acid (PLA) and thermoplastic polyurethane material (NinjaFlex® and SemiFlex®), were used for different stiffness and shock-absorption properties. The 3D printed prototypes were then tested and the results were compared to the computational predictions. The results showed that the auxetic material could be effective in reducing the shock forces. Each structure and material combination demonstrated unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Auxetic structures showed better shock

  12. An Optimization Problem for Predicting the Maximal Effect of Degradation of Mechanical Structures

    DEFF Research Database (Denmark)

    Achtziger, W.; Bendsøe, Martin P.; Taylor, J. E.

    2000-01-01

    This paper deals with a nonlinear nonconvex optimization problem that models prediction of degradation in discrete or discretized mechanical structures. The mathematical difficulty lies in equality constraints of the form Σ(i=1)(m) 1/yi A(i) x=b, where A(i) are symmetric and positive semidefinite...

  13. Finding the Optimal Scaffoldings for Learners' Epistemological Beliefs during Ill-Structured Problem Solving

    Science.gov (United States)

    Shin, Suhkyung; Song, Hae-Deok

    2016-01-01

    This study investigates how scaffolding type and learners' epistemological beliefs influence ill-structured problem solving. The independent variables in this study include the type of scaffolding (task-supported, self-monitoring) and the student's epistemological belief level (more advanced, less advanced). The dependent variables include three…

  14. On evaluating the performance of problem structuring methods : an attempt at formulating a conceptual model

    NARCIS (Netherlands)

    Rouwette, E.A.J.A.; Vennix, J.A.M.; Felling, A.J.A.

    2009-01-01

    In the past decade there has been a discussion on the need for and degree of empirical evidence for the effectiveness of problem structuring methods (PSMs). Some authors propose that PSMs are used in unique situations which are difficult to study, both from a methodological and a practical

  15. Earthworms (Aporrectodea spp.; Lumbricidae) cause soil structure problems in young Dutch polders

    NARCIS (Netherlands)

    Ester, A.; Rozen, van K.

    2002-01-01

    The presence of earthworms in relation to clay soil structure problems in arable fields in the Flevopolders (the Netherlands) was studied. Recently, farmers in this area have had difficulty in harvesting potatoes in predominantly wet years. After a dry period, soil particles in the top layer of the

  16. Structured Medication Review to Improve Pharmacotherapy in People with Intellectual Disability and Behavioural Problems

    Science.gov (United States)

    Scheifes, Arlette; Egberts, Toine C. G.; Stolker, Joost Jan; Nijman, Henk. L. I.; Heerdink, Eibert R.

    2016-01-01

    Background: Polypharmacy and chronic drug use are common in people with intellectual disability and behavioural problems, although evidence of effectiveness and safety in this population is lacking. This study examined the effects of a structured medication review and aimed to improve pharmacotherapy in inpatients with intellectual disability.…

  17. Case Designs for Ill-Structured Problems: Analysis and Implications for Practice

    Science.gov (United States)

    Dabbagh, Nada; Blijd, Cecily Williams

    2009-01-01

    This study is a third in a series of studies that examined students' information seeking and problem solving behaviors while interacting with one of two types of web-based representations of an ill-structured instructional design case: hierarchical (tree-like) and heterarchical (network-like). A Java program was used to track students' hypermedia…

  18. Solving the Problems of Iowa Food Deserts: Food Insecurity and Civic Structure

    Science.gov (United States)

    Morton, Lois Wright; Bitto, Ella Annette; Oakland, Mary Jane; Sand, Mary

    2005-01-01

    Rural regions include places where food sources are not evenly distributed, leading to areas of concentration and food desert--places where few or no grocery stores exist. Individuals are hypothesized to depend on personal connections and the civic structure of where they live to help them solve the problem of food insecurity. We find that…

  19. Photonic Band Structure of Dispersive Metamaterials Formulated as a Hermitian Eigenvalue Problem

    KAUST Repository

    Raman, Aaswath

    2010-02-26

    We formulate the photonic band structure calculation of any lossless dispersive photonic crystal and optical metamaterial as a Hermitian eigenvalue problem. We further show that the eigenmodes of such lossless systems provide an orthonormal basis, which can be used to rigorously describe the behavior of lossy dispersive systems in general. © 2010 The American Physical Society.

  20. Addressing special structure in the relevance feedback learning problem through aspect-based image search

    NARCIS (Netherlands)

    M.J. Huiskes (Mark)

    2004-01-01

    textabstractIn this paper we focus on a number of issues regarding special structure in the relevance feedback learning problem, most notably the effects of image selection based on partial relevance on the clustering behavior of examples. We propose a simple scheme, aspect-based image search, which

  1. Problem-Based Learning and Structural Redesign in a Choral Methods Course

    Science.gov (United States)

    Freer, Patrick

    2017-01-01

    This article describes the process of structural redesign of an undergraduate music education choral methods course. A framework incorporating Problem-based Learning was developed to promote individualized student learning. Ten students participated in the accompanying research study, contributing an array of written and spoken comments as well as…

  2. Topology optimization of acoustic-structure interaction problems using a mixed finite element formulation

    DEFF Research Database (Denmark)

    Yoon, Gil Ho; Jensen, Jens Stissing; Sigmund, Ole

    2007-01-01

    The paper presents a gradient-based topology optimization formulation that allows to solve acoustic-structure (vibro-acoustic) interaction problems without explicit boundary interface representation. In acoustic-structure interaction problems, the pressure and displacement fields are governed...... given during the optimization process. In this paper we circumvent the explicit boundary representation by using a mixed finite element formulation with displacements and pressure as primary variables (a u/p-formulation). The Helmholtz equation is obtained as a special case of the mixed formulation...... for the elastic shear modulus equating to zero. Hence, by spatial variation of the mass density, shear and bulk moduli we are able to solve the coupled problem by the mixed formulation. Using this modelling approach, the topology optimization procedure is simply implemented as a standard density approach. Several...

  3. Oxide glass structure evolution under swift heavy ion irradiation

    International Nuclear Information System (INIS)

    Mendoza, C.; Peuget, S.; Charpentier, T.; Moskura, M.; Caraballo, R.; Bouty, O.; Mir, A.H.; Monnet, I.; Grygiel, C.; Jegou, C.

    2014-01-01

    Highlights: • Structure of SHI irradiated glass is similar to the one of a hyper quenched glass. • D2 Raman band associated to 3 members ring is only observed in irradiated glass. • Irradiated state seems slightly different to an equilibrated liquid quenched rapidly. - Abstract: The effects of ion tracks on the structure of oxide glasses were examined by irradiating a silica glass and two borosilicate glass specimens containing 3 and 6 oxides with krypton ions (74 MeV) and xenon ions (92 MeV). Structural changes in the glass were observed by Raman and nuclear magnetic resonance spectroscopy using a multinuclear approach ( 11 B, 23 Na, 27 Al and 29 Si). The structure of irradiated silica glass resembles a structure quenched at very high temperature. Both borosilicate glass specimens exhibited depolymerization of the borosilicate network, a lower boron coordination number, and a change in the role of a fraction of the sodium atoms after irradiation, suggesting that the final borosilicate glass structures were quenched from a high temperature state. In addition, a sharp increase in the concentration of three membered silica rings and the presence of large amounts of penta- and hexacoordinate aluminum in the irradiated 6-oxide glass suggest that the irradiated glass is different from a liquid quenched at equilibrium, but it is rather obtained from a nonequilibrium liquid that is partially relaxed by very rapid quenching within the ion tracks

  4. Reconstruction of ancestral RNA sequences under multiple structural constraints

    Directory of Open Access Journals (Sweden)

    Olivier Tremblay-Savard

    2016-11-01

    Full Text Available Abstract Background Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. Methods In this paper, we introduce achARNement, a maximum parsimony approach that, given two alignments of homologous ncRNA families with consensus secondary structures and a phylogenetic tree, simultaneously calculates ancestral RNA sequences for these two families. Results We test our methodology on simulated data sets, and show that achARNement outperforms classical maximum parsimony approaches in terms of accuracy, but also reduces by several orders of magnitude the number of candidate sequences. To conclude this study, we apply our algorithms on the Glm clan and the FinP-traJ clan from the Rfam database. Conclusions Our results show that our methods reconstruct small sets of high-quality candidate ancestors with better agreement to the two target structures than with classical approaches. Our program is freely available at: http://csb.cs.mcgill.ca/acharnement .

  5. Structural integrity analysis of an INPP building under external loading

    International Nuclear Information System (INIS)

    Dundulis, G.; Karalevicius, R.; Uspuras, E.; Kulak, R.F.; Marchertas, A.

    2005-01-01

    After the terrorist attacks in New York and Washington D. C. using civil airplanes, the evaluation of civil airplane crashes into civil and NPP structures has become very important. The interceptions of many terrorists' communications reveal that the use of commandeered commercial aircraft is still a major part of their plans for destruction. Aircraft crash or other flying objects in the territory of the Ignalina Nuclear Power Plant (INPP) represents a concern to the plant. Aircraft traveling at high velocity have a destructive potential. The aircraft crash may damage the roof and walls of buildings, pipelines, electric motors, cases of power supplies, power cables of electricity transmission and other elements and systems, which are important for safety. Therefore, the evaluation of the structural response to an of aircraft crash is important and was selected for analysis. The structural integrity analysis due to the effects of an aircraft crash on an NPP building structure is the subject of this paper. The finite element method was used for the structural analysis of a typical Ignalina NPP building. The structural integrity analysis was performed for a portion of the ALS using the dynamic loading of an aircraft crash impact model. The computer code NEPTUNE was used for this analysis. The local effects caused by impact of the aircraft's engine on the building wall were evaluated independently by using an empirical formula. (authors)

  6. Training set optimization under population structure in genomic selection.

    Science.gov (United States)

    Isidro, Julio; Jannink, Jean-Luc; Akdemir, Deniz; Poland, Jesse; Heslot, Nicolas; Sorrells, Mark E

    2015-01-01

    Population structure must be evaluated before optimization of the training set population. Maximizing the phenotypic variance captured by the training set is important for optimal performance. The optimization of the training set (TRS) in genomic selection has received much interest in both animal and plant breeding, because it is critical to the accuracy of the prediction models. In this study, five different TRS sampling algorithms, stratified sampling, mean of the coefficient of determination (CDmean), mean of predictor error variance (PEVmean), stratified CDmean (StratCDmean) and random sampling, were evaluated for prediction accuracy in the presence of different levels of population structure. In the presence of population structure, the most phenotypic variation captured by a sampling method in the TRS is desirable. The wheat dataset showed mild population structure, and CDmean and stratified CDmean methods showed the highest accuracies for all the traits except for test weight and heading date. The rice dataset had strong population structure and the approach based on stratified sampling showed the highest accuracies for all traits. In general, CDmean minimized the relationship between genotypes in the TRS, maximizing the relationship between TRS and the test set. This makes it suitable as an optimization criterion for long-term selection. Our results indicated that the best selection criterion used to optimize the TRS seems to depend on the interaction of trait architecture and population structure.

  7. Reconstruction of ancestral RNA sequences under multiple structural constraints.

    Science.gov (United States)

    Tremblay-Savard, Olivier; Reinharz, Vladimir; Waldispühl, Jérôme

    2016-11-11

    Secondary structures form the scaffold of multiple sequence alignment of non-coding RNA (ncRNA) families. An accurate reconstruction of ancestral ncRNAs must use this structural signal. However, the inference of ancestors of a single ncRNA family with a single consensus structure may bias the results towards sequences with high affinity to this structure, which are far from the true ancestors. In this paper, we introduce achARNement, a maximum parsimony approach that, given two alignments of homologous ncRNA families with consensus secondary structures and a phylogenetic tree, simultaneously calculates ancestral RNA sequences for these two families. We test our methodology on simulated data sets, and show that achARNement outperforms classical maximum parsimony approaches in terms of accuracy, but also reduces by several orders of magnitude the number of candidate sequences. To conclude this study, we apply our algorithms on the Glm clan and the FinP-traJ clan from the Rfam database. Our results show that our methods reconstruct small sets of high-quality candidate ancestors with better agreement to the two target structures than with classical approaches. Our program is freely available at: http://csb.cs.mcgill.ca/acharnement .

  8. Content-based music recommendation using underlying music preference structure

    OpenAIRE

    Soleymani M.; Aljanaki A.; Wiering F.; Veltkamp R.C.

    2015-01-01

    The cold start problem for new users or items is a great challenge for recommender systems. New items can be positioned within the existing items using a similarity metric to estimate their ratings. However, the calculation of similarity varies by domain and available resources. In this paper, we propose a content-based music recommender system which is based on a set of attributes derived from psychological studies of music preference. These five attributes, namely, Mellow, Unpretentious, So...

  9. [Prevention of alcoholism as a social, communicational and structural problem in industry].

    Science.gov (United States)

    König, R

    1991-08-01

    To promote effective aid to alcohol-dependents in a company it is essential to treat the problem "alcohol in the office, workshops and plant" not only as a problem concerning the alcohol-dependents and addicts, but as a problem that has to be jointly tackled by all the company divisions involved and by all the echelons of the firm. It has become evident that the multiplicator directly involved in helping alcohol-dependents must take into consideration the structure and group dynamics within the company before they can work efficiently. The following report deals with the difficulties within a company that are linked to this problem area. Examples serve to show how poorly efficient any aid to alcohol-dependents can be if the persons involved fail to see clearly which prerequisites and approaches are essential. Advice is given how to avoid such pitfalls and misunderstandings.

  10. Solving the Bilevel Facility Location Problem under Preferences by a Stackelberg-Evolutionary Algorithm

    Directory of Open Access Journals (Sweden)

    José-Fernando Camacho-Vallejo

    2014-01-01

    Full Text Available This research highlights the use of game theory to solve the classical problem of the uncapacitated facility location optimization model with customer order preferences through a bilevel approach. The bilevel model provided herein consists of the classical facility location problem and an optimization of the customer preferences, which are the upper and lower level problems, respectively. Also, two reformulations of the bilevel model are presented, reducing it into a mixed-integer single-level problem. An evolutionary algorithm based on the equilibrium in a Stackelberg’s game is proposed to solve the bilevel model. Numerical experimentation is performed in this study and the results are compared to benchmarks from the existing literature on the subject in order to emphasize the benefits of the proposed approach in terms of solution quality and estimation time.

  11. Adaptive solution of some steady-state fluid-structure interaction problems

    International Nuclear Information System (INIS)

    Etienne, S.; Pelletier, D.

    2003-01-01

    This paper presents a general integrated and coupled formulation for modeling the steady-state interaction of a viscous incompressible flow with an elastic structure undergoing large displacements (geometric non-linearities). This constitutes an initial step towards developing a sensitivity analysis formulation for this class of problems. The formulation uses velocity and pressures as unknowns in a flow domain and displacements in the structural components. An interface formulation is presented that leads to clear and simple finite element implementation of the equilibrium conditions at the fluid-solid interface. Issues of error estimation and mesh adaptation are discussed. The adaptive formulation is verified on a problem with a closed form solution. It is then applied to a sample case for which the structure undergoes large displacements induced by the flow. (author)

  12. Response of structural elements under non-uniformly distributed dynamic loads

    NARCIS (Netherlands)

    Westerhof, T.A.T.; Huebner, M.; Ferretti, D.L.; Doormaal, J.C.A.M. van; Gebbeken, N.

    2016-01-01

    Determination of the structural response of a structural element under blast loading is of interest to vulnerability / lethality (V/L) studies of military operations in urban terrain. These studies require a quick and easy to use method to simulate the structural response of e.g. a wall under

  13. Modeling of fracture of protective concrete structures under impact loads

    Science.gov (United States)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-01

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  14. The cortical topography of tonal structures underlying Western music.

    Science.gov (United States)

    Janata, Petr; Birk, Jeffrey L; Van Horn, John D; Leman, Marc; Tillmann, Barbara; Bharucha, Jamshed J

    2002-12-13

    Western tonal music relies on a formal geometric structure that determines distance relationships within a harmonic or tonal space. In functional magnetic resonance imaging experiments, we identified an area in the rostromedial prefrontal cortex that tracks activation in tonal space. Different voxels in this area exhibited selectivity for different keys. Within the same set of consistently activated voxels, the topography of tonality selectivity rearranged itself across scanning sessions. The tonality structure was thus maintained as a dynamic topography in cortical areas known to be at a nexus of cognitive, affective, and mnemonic processing.

  15. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    Science.gov (United States)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

  16. Analysis of NPP protection structure reliability under impact of a falling aircraft

    International Nuclear Information System (INIS)

    Shul'man, G.S.

    1996-01-01

    Methodology for evaluation of NPP protection structure reliability by impact of aircraft fall down is considered. The methodology is base on the probabilistic analysis of all potential events. The problem is solved in three stages: determination of loads on structural units, calculation of local reliability of protection structures by assigned loads and estimation of the structure reliability. The methodology proposed may be applied at the NPP design stage and by determination of reliability of already available structures

  17. Interevent relationships and judgment under uncertainty: Structure determines strategy

    NARCIS (Netherlands)

    Sanfey, A.G.; Hastie, R.

    2002-01-01

    A fundamental empirical question regarding judgments about events is whether experienced absolute frequencies or relative. frequencies are relied on when the likelihood of a particular occurrence is judged. The present research explicates the conditions under which people rely on remembered raw

  18. Influence of amendments on soil structure and soil loss under ...

    African Journals Online (AJOL)

    Macromolecule polymers are significant types of chemical amendments because of their special structure, useful functions and low cost. Macromolecule polymers as soil amendment provide new territory for studying China's agricultural practices and for soil and water conservation, because polymers have the ability to ...

  19. Structural performance of HEPA filters under simulated tornado conditions

    International Nuclear Information System (INIS)

    Horak, H.L.; Gregory, W.S.; Ricketts, C.I.; Smith, P.R.

    1982-02-01

    This report contains the results of structural tests to determine the response of High Efficiency Particulate Air filters to simulated tornado conditions. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The type of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 m 3 /s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, faceguards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits

  20. Structure Formation of Thermoresponsive Microgels Suspensions Under Shear Flow

    NARCIS (Netherlands)

    Stieger, M.A.; Lindner, P.; Richtering, W.

    2004-01-01

    Shear-induced structures of concentrated temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) microgel suspensions have been studied employing small angle neutron scattering (rheo-SANS). The interaction potential of swollen PNiPAM microgels could be varied from repulsive at temperatures below

  1. Sustainability assessment of concrete structure durability under reinforcement corrosion

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    In the present paper a parametric study is conducted based on an existing finite element based model. The influence of cover layer, reinforcement diameter and water-to-cement ratio is compared to a possible scatter in the results due to insufficient knowledge about the distribution of the corrosi...... and predict the durability of a given structure....

  2. Optimization and anti-optimization of structures under uncertainty

    National Research Council Canada - National Science Library

    Elishakoff, Isaac; Ohsaki, Makoto

    2010-01-01

    ..., architecture, civil, mechanical or ocean engineering, invariably adopt the either/or style. Namely, they devote themselves either to linear or to nonlinear analysis of the structure they are dealing with, they are engaged in analyzing it either in the elastic or in the inelastic range; they deal either with its static or with its dynamic behavior. Al...

  3. Occupational structure in the Czech lands under the second serfdom

    Czech Academy of Sciences Publication Activity Database

    Klein, Alexander; Ogilvie, S.

    2016-01-01

    Roč. 69, č. 2 (2016), s. 493-521 ISSN 0013-0117 R&D Projects: GA ČR GA13-13848S Institutional support: RVO:67985998 Keywords : occupational structure * Czech lands * Bohemia Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 1.233, year: 2016

  4. Electrostatic point charge fitting as an inverse problem: Revealing the underlying ill-conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Maxim V.; Talipov, Marat R.; Timerghazin, Qadir K., E-mail: qadir.timerghazin@marquette.edu [Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881 (United States)

    2015-10-07

    Atom-centered point charge (PC) model of the molecular electrostatics—a major workhorse of the atomistic biomolecular simulations—is usually parameterized by least-squares (LS) fitting of the point charge values to a reference electrostatic potential, a procedure that suffers from numerical instabilities due to the ill-conditioned nature of the LS problem. To reveal the origins of this ill-conditioning, we start with a general treatment of the point charge fitting problem as an inverse problem and construct an analytical model with the point charges spherically arranged according to Lebedev quadrature which is naturally suited for the inverse electrostatic problem. This analytical model is contrasted to the atom-centered point-charge model that can be viewed as an irregular quadrature poorly suited for the problem. This analysis shows that the numerical problems of the point charge fitting are due to the decay of the curvatures corresponding to the eigenvectors of LS sum Hessian matrix. In part, this ill-conditioning is intrinsic to the problem and is related to decreasing electrostatic contribution of the higher multipole moments, that are, in the case of Lebedev grid model, directly associated with the Hessian eigenvectors. For the atom-centered model, this association breaks down beyond the first few eigenvectors related to the high-curvature monopole and dipole terms; this leads to even wider spread-out of the Hessian curvature values. Using these insights, it is possible to alleviate the ill-conditioning of the LS point-charge fitting without introducing external restraints and/or constraints. Also, as the analytical Lebedev grid PC model proposed here can reproduce multipole moments up to a given rank, it may provide a promising alternative to including explicit multipole terms in a force field.

  5. Electrostatic point charge fitting as an inverse problem: Revealing the underlying ill-conditioning

    International Nuclear Information System (INIS)

    Ivanov, Maxim V.; Talipov, Marat R.; Timerghazin, Qadir K.

    2015-01-01

    Atom-centered point charge (PC) model of the molecular electrostatics—a major workhorse of the atomistic biomolecular simulations—is usually parameterized by least-squares (LS) fitting of the point charge values to a reference electrostatic potential, a procedure that suffers from numerical instabilities due to the ill-conditioned nature of the LS problem. To reveal the origins of this ill-conditioning, we start with a general treatment of the point charge fitting problem as an inverse problem and construct an analytical model with the point charges spherically arranged according to Lebedev quadrature which is naturally suited for the inverse electrostatic problem. This analytical model is contrasted to the atom-centered point-charge model that can be viewed as an irregular quadrature poorly suited for the problem. This analysis shows that the numerical problems of the point charge fitting are due to the decay of the curvatures corresponding to the eigenvectors of LS sum Hessian matrix. In part, this ill-conditioning is intrinsic to the problem and is related to decreasing electrostatic contribution of the higher multipole moments, that are, in the case of Lebedev grid model, directly associated with the Hessian eigenvectors. For the atom-centered model, this association breaks down beyond the first few eigenvectors related to the high-curvature monopole and dipole terms; this leads to even wider spread-out of the Hessian curvature values. Using these insights, it is possible to alleviate the ill-conditioning of the LS point-charge fitting without introducing external restraints and/or constraints. Also, as the analytical Lebedev grid PC model proposed here can reproduce multipole moments up to a given rank, it may provide a promising alternative to including explicit multipole terms in a force field

  6. The electronic structure of core states under extreme compressions

    International Nuclear Information System (INIS)

    Straub, G.K.

    1992-01-01

    At normal density and for modest compressions, the electronic structure of a metal can be accurately described by treating the conduction electrons and their interactions with the usual methods of band theory. The core electrons remain essentially the same as for an isolated free atom and do not participate in the bonding forces responsible for creating a condensed phase. As the density increases, the core electrons begin to ''see'' one another as the overlap of the tails of wave functions can no longer be neglected. The electronic structure of the core electrons is responsible for an effective repulsive interaction that eventually becomes free-electron-like at very high compressions. The electronic structure of the interacting core electrons may be treated in a simple manner using the Atomic Surface Method (ASM). The ASM is a first-principles treatment of the electronic structure involving a rigorous integration of the Schroedinger equation within the atomic-sphere approximation. Solid phase wave functions are constructed from isolated atom wave functions and the band width W l and the center of gravity of the band C l are obtained from simple formulas. The ASM can also utilize analytic forms of the atomic wave functions and thus provide direct functional dependence of various aspects of the electronic structure. Of particular use in understanding the behavior of the core electrons, the ASM provides the ability to analytically determine the density dependence of the band widths and positions. The process whereby core states interact with one another is best viewed as the formation of narrow electron bands formed from atomic states. As the core-core overlap increases, the bands increase in width and mean energy. In Sec.3 this picture is further developed and from the ASM one obtains the analytic dependence on density of the relative motion of the different bands. Also in Sec. 3 is a discussion of the transition to free electron bands

  7. Structured Medication Review to Improve Pharmacotherapy in People with Intellectual Disability and Behavioural Problems.

    Science.gov (United States)

    Scheifes, Arlette; Egberts, Toine C G; Stolker, Joost Jan; Nijman, Henk L I; Heerdink, Eibert R

    2016-07-01

    Polypharmacy and chronic drug use are common in people with intellectual disability and behavioural problems, although evidence of effectiveness and safety in this population is lacking. This study examined the effects of a structured medication review and aimed to improve pharmacotherapy in inpatients with intellectual disability. In a treatment facility for people with mild to borderline intellectual disability and severe behavioural problems, a structured medication review was performed. Prevalence and type of drug-related problems (DRPs) and of the recommended and executed actions were calculated. In a total of 55 patients with intellectual disability and behavioural problems, 284 medications were prescribed, in which a DRP was seen in 106 (34%). No indication/unclear indication was the most prevalent DRP (70). Almost 60% of the recommended actions were also executed. This high prevalence of DRPs is worrying. The structured medication review is a valuable instrument to optimize pharmacotherapy and to support psychiatrists in adequate prescribing of both psychotropic and somatic drugs. © 2015 John Wiley & Sons Ltd.

  8. Effect of Physics Problem Solving on Structures Schemes and Knowledge Associations

    Science.gov (United States)

    Setyowidodo, I.; Jatmiko, B.; Susantini, E.; Widodo, S.; Shofwan, A.

    2017-09-01

    This study aims to develop learners’ thinking structures through associations, case based, and schematic method so that different knowledge structures have a role in influencing the structure of creative thinking. The learners have low mastery of physics materials since they are not given sufficient opportunity to build their own knowledge. They should be directed to approach each new problem or task with their prior knowledge, assimilate new information, and construct their own understanding. The design of this research was a quasi-experiment using purposive sampling. Data were analyzed using variance analysis. The design of this research was a quasi-experiment using purposive sampling. Data were analyzed using variance analysis. The learning process of problemsolving consists of: 1) identifying problems, 2) planning projects, 3) creating projects, 4) presenting projects, and 5) evaluating projects. From the results of this research, it can be concluded that problem-solving method can provide strong supports in developing the learners’ creative thinking skills as they can share their knowledge and interact with their friends and the environment. This learning activity also constitutes an appropriate technique to help the learners to develop problem solving knowledge and skills.

  9. Elaborating the Structures of a Science Discipline to Improve Problem-Solving Instruction: An Account of Classical Genetics' Theory Structure, Function, and Development.

    Science.gov (United States)

    Hafner, Robert; Culp, Sylvia

    1996-01-01

    Provides further details regarding a philosophical reconstruction of the structure of Classical Genetics Theory that can facilitate problem-solving instruction. Describes how that reconstruction can facilitate realistic problem solving on the part of students. Contains 60 references. (DDR)

  10. Inverse problem for a physiologically structured population model with variable-effort harvesting

    Directory of Open Access Journals (Sweden)

    Andrusyak Ruslan V.

    2017-04-01

    Full Text Available We consider the inverse problem of determining how the physiological structure of a harvested population evolves in time, and of finding the time-dependent effort to be expended in harvesting, so that the weighted integral of the density, which may be, for example, the total number of individuals or the total biomass, has prescribed dynamics. We give conditions for the existence of a unique, global, weak solution to the problem. Our investigation is carried out using the method of characteristics and a generalization of the Banach fixed-point theorem.

  11. Co-simulation coupling spectral/finite elements for 3D soil/structure interaction problems

    Science.gov (United States)

    Zuchowski, Loïc; Brun, Michael; De Martin, Florent

    2018-05-01

    The coupling between an implicit finite elements (FE) code and an explicit spectral elements (SE) code has been explored for solving the elastic wave propagation in the case of soil/structure interaction problem. The coupling approach is based on domain decomposition methods in transient dynamics. The spatial coupling at the interface is managed by a standard coupling mortar approach, whereas the time integration is dealt with an hybrid asynchronous time integrator. An external coupling software, handling the interface problem, has been set up in order to couple the FE software Code_Aster with the SE software EFISPEC3D.

  12. Algebraic structures in generalized Clifford analysis and applications to boundary value problems

    Directory of Open Access Journals (Sweden)

    José Játem

    2015-12-01

    Full Text Available The present article has a threefold purpose: First it is a survey of the algebraic structures of generalized Clifford-type algebras and shows the main results of the corresponding Clifford-type analysis and its application to boundary value problems known so far. Second it is aimed to implement algorithms to provide the fast and accurate computation of boundary value problems for inhomogeneous equations in the framework of the generalized Clifford analysis. Finally it is also aimed to encourage the development of a generalized discrete Clifford analysis.

  13. Coupled problems in transient fluid and structural dynamics in nuclear engineering

    International Nuclear Information System (INIS)

    Krieg, R.

    1978-01-01

    Some important problems in coupled fluid-structural dynamics which occur in safety investigations of liquid metal fast breeder reactors (LMFBR). light water reactors and nuclear reprocessing plants are discussed and a classification of solution methods is introduced. A distinction is made between the step by step solution procedure, where available computer codes in fluid and structural dynamics are coupled, and advanced simultaneous solution methods, where the coupling is carried out at the level of the fundamental equations. Results presented include the transient deformation of a two-row pin bundle surrounded by an infinite fluid field, vapour explosions in a fluid container and containment distortions due to bubble collapse in the pressure suppression system of a boiling water reactor. A recently developed simultaneous solution method is presented in detail. Here the fluid dynamics (inviscid, incompressible fluid) is described by a singularity method which reduces the three-dimensional fluid dynamics problems to a two-dimensional formulation. In this way the three-dynamics fluid dynamics as well as the structural (shell) dynamics can be described essentially by common unknowns at the fluid-structural interface. The resulting equations for the coupled fluid-structural dynamics are analogous to to the equations of motion of the structural dynamics alone. (author)

  14. Structural stability and theoretical strength of Cu crystal under equal ...

    Indian Academy of Sciences (India)

    The results indicate that, under sufficient tension, there exists a stress-free BCC phase which is unstable and slips spontaneously to a stress-free metastable BCT phase by consuming internal energy. The stable region ranges from −15.131 GPa to 2.803 GPa in the theoretical strength or from −5.801% to 4.972% in the strain ...

  15. An efficient heuristic method for dynamic portfolio selection problem under transaction costs and uncertain conditions

    Science.gov (United States)

    Najafi, Amir Abbas; Pourahmadi, Zahra

    2016-04-01

    Selecting the optimal combination of assets in a portfolio is one of the most important decisions in investment management. As investment is a long term concept, looking into a portfolio optimization problem just in a single period may cause loss of some opportunities that could be exploited in a long term view. Hence, it is tried to extend the problem from single to multi-period model. We include trading costs and uncertain conditions to this model which made it more realistic and complex. Hence, we propose an efficient heuristic method to tackle this problem. The efficiency of the method is examined and compared with the results of the rolling single-period optimization and the buy and hold method which shows the superiority of the proposed method.

  16. Analysis of ADU structure obtained under different precipitation conditions

    International Nuclear Information System (INIS)

    Ramella, Jose L.; Esteban, Adolfo; Mendez De Leo, Lucia P.; Sassone, Ariel; Novara, Oscar E.; Boero, Norma L.; Leyva, Ana G.

    1999-01-01

    ADU is the nominal name for ammonium poly uranate. It is a very complex compound of polymeric structure, which may have, according to precipitation conditions, different chemical composition and crystallographic structure. ADU is used as uranium oxide precursor in the manufacture of fuel elements. In former papers it was proved that if ultrasound is applied during precipitation and digestion the characteristics of the final product (U 3 O 8 UO 2 ) improve. By studying ADU thermal decomposition obtained by ultrasonic application, it was intended to obtain its composition. Therefore, differential thermal gravimetric and differential thermal analyses were performed. Samples were taken from special points and analyzed by X-ray diffraction, infra-red spectroscopy and scanning. An experiment was also designed to identify the products released during heating. Results and conclusions obtained are presented in this work. (author)

  17. Fiscal reaction under endogenous structural changes in Brazil

    Directory of Open Access Journals (Sweden)

    Andrei G. Simonassi

    2014-01-01

    Full Text Available Regarding the importance of fiscal policy in smoothing the impact of shocks such as the international financial and economic crises, the paper analyzes the sustainability of the Brazilian fiscal policy by taking into consideration the possibility of multiple endogenous structural breaks on the coefficients of government reaction function. From monthly data in the period 1991–2008, tests on the reliable estimates dictate the occurrence of structural change in May 1994, and another in February 2003. There has been a situation of fiscal solvency in Brazil, but only from May 1994 the hitherto innocuous actions of government to formulate policies on public debt turn out to be significant, as it rose twofold after February 2003. This reinforces the existence of a more flexible alternative to implement strategic policy in Brazil, if an eventual alternative for increasing public spending is a way of hindering the effects of international financial crises without compromising the fiscal targets.

  18. A homogenization method for the analysis of a coupled fluid-structure interaction problem with inner solid structure

    International Nuclear Information System (INIS)

    Sigrist, Jean-Francois; Laine, Christian; Broc, Daniel

    2006-01-01

    . The paper has the following contents: Introduction; A homogenization method; Validation of the method; Conclusion. In conclusion, a homogenization method has been exposed in the present paper to deal with the modal analysis of a coupled fluid-structure problem that takes into account the presence of solid inner inclusions on the fluid domain. The basic theory of the developed homogenization method has been recalled. The fluid-structure interaction is described in terms of pressure-displacement with the corrective terms taking into account the confinement effect induced by the inclusion. From the theoretical point of view, the method is furthermore demonstrated to be physically consistent in terms of total mass conservation. The method is validated on a generic 2D case, by a comparison of calculation performed on the fluid-structure system with inclusions and on the fluid-structure modified problem without inclusions. The numerical results are identical both in terms of Eigen-frequencies, Eigenmodes and modal masses. The method can be applied to the modal analysis of a nuclear reactor

  19. Structure and morphology of mythimna pupa under diffraction enhanced imaging

    International Nuclear Information System (INIS)

    Huang Wanxia; Yuan Qingxi; Zhu Peiping; Wang Junyue; Liu Yijin; Chen Bo; Shu Hang; Hu Tiandou; Wu Ziyu; Ge Siqin

    2007-01-01

    As a technique of X-ray phase contrast imaging, the diffraction enhanced imaging (DEI) attracts much interest due to its high resolution and contrast. The top images of DEI were used to study the growth of a complete metamorphic mythimna in the period of pupa. Clear images about the pupa structure were obtained. The entire growth process of the pupa was observed, including the evolvement of part of organs and tissues from larva to imago. (authors)

  20. Structural performance of HEPA filters under simulated tornado conditions

    Science.gov (United States)

    Horak, H. L.; Gregory, W. S.; Ricketts, C. I.; Smith, P. R.

    1982-02-01

    The response of high efficiency particulate air filters to simulated tornado conditions was determined. The data include the structural limits of the filters, their resistance at high flow rates, and the effects of filter design features and tornado parameters. Considering all the filters tested, the mean break pressure or structural limit was found to be 2.35 pse (16.2 kPa). The maximum value was 2.87 psi (19.8 kPa), and the low value found was 1.31 psi (9.0 kPa). The type of failure was usually a medium break of the downstream filter fold. The types of filters that were evaluated were nuclear grade with design flow rates of 1000 cfm (0.472 cu m/s), standard separators, and folded medium design. The parameters evaluated that are characteristic of the filter included manufacturer, separator type, face-guards, pack tightness, and aerosol loading. Manufacturer and medium properties were found to have a large effect on the structural limits.

  1. Disrupted white matter structure underlies cognitive deficit in hypertensive patients

    International Nuclear Information System (INIS)

    Li, Xin; Ma, Chao; Zhang, Junying; Chen, Yaojing; Zhang, Zhanjun; Sun, Xuan; Chen, Kewei

    2016-01-01

    Hypertension is considered a risk factor of cognitive impairments and could result in white matter changes. Current studies on hypertension-related white matter (WM) changes focus only on regional changes, and the information about global changes in WM structure network is limited. We assessed the cognitive function in 39 hypertensive patients and 37 healthy controls with a battery of neuropsychological tests. The WM structural networks were constructed by utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. The direct and indirect correlations among cognitive impairments, brain WM network disruptions and hypertension were analyzed with structural equation modelling (SEM). Hypertensive patients showed deficits in executive function, memory and attention compared with controls. An aberrant connectivity of WM networks was found in the hypertensive patients (P Eglob = 0.005, P Lp = 0.005), especially in the frontal and parietal regions. Importantly, SEM analysis showed that the decline of executive function resulted from aberrant WM networks in hypertensive patients (p = 0.3788, CFI = 0.99). These results suggest that the cognitive decline in hypertensive patients was due to frontal and parietal WM disconnections. Our findings highlight the importance of brain protection in hypertension patients. (orig.)

  2. The Response of Simple Polymer Structures Under Dynamic Loading

    Science.gov (United States)

    Proud, William; Ellison, Kay; Yapp, Su; Cole, Cloe; Galimberti, Stefano; Institute of Shock Physics Team

    2017-06-01

    The dynamic response of polymeric materials has been widely studied with the effects of degree of crystallinity, strain rate, temperature and sample size being commonly reported. This study uses a simple PMMA structure, a right cylindrical sample, with structural features such as holes. The features are added an varied in a systematic fashion. Samples were dynamically loaded using a Split Hopkinson Pressure Bar up to failure. The resulting stress-strain curves are presented showing the change in sample response. The strain to failure is shown to increase initially with the presence of holes, while failure stress is relatively unaffected. The fracture patterns seen in the failed samples change, with tensile cracks, Hertzian cones, shear effects being dominant for different holes sizes and geometries. The sample were prepared by laser cutting and checked for residual stress before experiment. The data is used to validate predictive model predictions where material, structure and damage are included.. The Institute of Shock Physics acknowledges the support of Imperial College London and the Atomic Weapons Establishment.

  3. THE RELATIONSHIP BETWEEN INDUSTRIAL PRODUCTION AND EMPLOYMENT UNDER STRUCTURAL BREAK

    Directory of Open Access Journals (Sweden)

    Umut HALAÇ

    2017-12-01

    Full Text Available For the economies which aim for the sustainable economic growth, one of the most important topic is industrialization. It is thought that it effects employability positively, by increasing the manufacturing. This study investigates the long-term relationship between industrial production and total employment, industrial employment and youth employment in Turkey using monthly data for the period from 2005:01 to 2017:06. Since the period involving structural changes, the stability of series was tested by standart Augmented Dickey Fuller unit root test and Zivot Andrews unit root test with structural breaks. Estimates of the cointegrating relation are obtained using Engle-Granger test procedure and Gregory Hansen test procedure taking structural breaks into account. The results of cointegration tests show that there is no long run relationship among the variables. The findings of the study indicate that the connections between industrial production and employment have been disappeared, during the time period examined for Turkey. This also suggests that the rise in the industrial production is still far from creating employability.

  4. An adaptive large neighborhood search heuristic for solving the reliable multiple allocation hub location problem under hub disruptions

    Directory of Open Access Journals (Sweden)

    S. K. Chaharsooghi

    2017-04-01

    Full Text Available The hub location problem (HLP is one of the strategic planning problems encountered in different contexts such as supply chain management, passenger and cargo transportation industries, and telecommunications. In this paper, we consider a reliable uncapacitated multiple allocation hub location problem under hub disruptions. It is assumed that every open hub facility can fail during its use and in such a case, the customers originally assigned to that hub, are either reassigned to other operational hubs or they do not receive service in which case a penalty must be paid. The problem is modeled as two-stage stochastic program and a metaheuristic algorithm based on the adaptive large neighborhood search (ALNS is proposed. Extensive computational experiments based on the CAB and TR data sets are conducted. Results show the high efficiency of the proposed solution method.

  5. Electron spin transition causing structure transformations of earth's interiors under high pressure

    Science.gov (United States)

    Yamanaka, T.; Kyono, A.; Kharlamova, S.; Alp, E.; Bi, W.; Mao, H.

    2012-12-01

    To elucidate the correlation between structure transitions and spin state is one of the crucial problems for understanding the geophysical properties of earth interiors under high pressure. High-pressure studies of iron bearing spinels attract extensive attention in order to understand strong electronic correlation such as the charge transfer, electron hopping, electron high-low spin transition, Jahn-Teller distortion and charge disproponation in the lower mantle or subduction zone [1]. Experiment Structure transitions of Fe3-xSixO4, Fe3-xTixO4 Fe3-xCrxO4 spinel solid solution have been investigated at high pressure up to 60 GPa by single crystal and powder diffraction studies using synchrotron radiation with diamond anvil cell. X-ray emission experiment (XES) at high pressure proved the spin transition of Fe-Kβ from high spin (HS) to intermediate spin state (IS) or low spin state (LS). Mössbauer experiment and Raman spectra study have been also conducted for deformation analysis of Fe site and confirmation of the configuration change of Fe atoms. Jahn-Teller effect A cubic-to-tetragonal transition under pressure was induced by Jahn-Teller effect of IVFe2+ (3d6) in the tetrahedral site of Fe2TiO4 and FeCr2O4, providing the transformation from 43m (Td) to 42m (D2d). Tetragonal phase is formed by the degeneracy of e orbital of Fe2+ ion. Their c/a ratios are c/adisordered in the M2 site. At pressures above 53 GPa, Fe2TiO4 structure further transforms to Pmma. This structure change results in the order-disorder transition [2]. New structure of Fe2SiO4 The spin transition exerts an influence to Fe2SiO4 spinel structure and triggers two distinct curves of the lattice constant in the spinel phase. The reversible structure transition from cubic to pseudo-rhombohedral phase was observed at about 45 GPa. This transition is induced by the 20% shrinkage of ionic radius of VIFe2+at the low sin state. Laser heating experiment at 1500 K has confirmed the decomposition from the

  6. Term Structure of Credit Spreads of A Firm When Its Underlying Assets are Discontinuous

    Directory of Open Access Journals (Sweden)

    Budhi Arta Surya

    2012-01-01

    Full Text Available We revisit the previous works of Leland [12], Leland and Toft [11] andHilberink and Rogers [7] on optimal capital structure and show that thecredit spreads of short-maturity corporate bonds can have nonzero valueswhen the underlying of the firm’s assets value has downward jumps. We givean analytical treatment of this fact under a general Levy process and discusssome numerical examples under pure jump processes.Keywords: Optimal capital structure, credit risk, term structure of creditspread

  7. Distribution of hydrogen within the HDR-containment under severe accident conditions. OECD standard problem. Final comparison report

    International Nuclear Information System (INIS)

    Karwat, H.

    1992-08-01

    The present report summarizes the results of the International Standard Problem Exercise ISP-29, based on the HDR Hydrogen Distribution Experiment E11.2. Post-test analyses are compared to experimentally measured parameters, well-known to the analysis. This report has been prepared by the Institute for Reactor Dynamics and Reactor Safety of the Technical University Munich under contract with the Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) which received funding for this activity from the German Ministry for Research and Technology (BMFT) under the research contract RS 792. The HDR experiment E11.2 has been performed by the Kernforschungszentrum Karlsruhe (KfK) in the frame of the project 'Projekt HDR-Sicherheitsprogramm' sponsored by the BMFT. Ten institutions from eight countries participated in the post-test analysis exercise which was focussing on the long-lasting gas distribution processes expected inside a PWR containment under severe accident conditions. The gas release experiment was coupled to a long-lasting steam release into the containment typical for an unmitigated small break loss-of-coolant accident. In lieu of pure hydrogen a gas mixture consisting of 15% hydrogen and 85% helium has been applied in order to avoid reaching flammability during the experiment. Of central importance are common overlay plots comparing calculated transients with measurements of the global pressure, the local temperature-, steam- and gas concentration distributions throughout the entire HDR containment. The comparisons indicate relatively large margins between most calculations and the experiment. Having in mind that this exercise was specified as an 'open post-test' analysis of well-known measured data the reasons for discrepancies between measurements and simulations were extensively discussed during a final workshop. It was concluded that analytical shortcomings as well as some uncertainties of experimental boundary conditions may be responsible for deviations

  8. Problems of training chemical engineers of the European model under Bologna process

    Directory of Open Access Journals (Sweden)

    S. Rakhmadiyeva

    2012-03-01

    Full Text Available Article deals with problems of training for chemical and petrochemical industries in the western three-stage model of the Bologna process and curriculum development of educational programs in chemical engineering in the framework of the EU Tempus.

  9. About the linear-quadratic regulator problem under a fractional Brownian perturbation and complete observation

    OpenAIRE

    Kleptsyna, Marina; Le Breton, Alain; Viot, Michel

    2002-01-01

    In this report we solve the basic fractional analogue of the classical linear-quadratic Gaussian regulator problem in continuous-time. For a completely observable controlled linear system driven by a fractional Brownian motion, we describe explicitely the optimal control policy which minimizes a quadratic performance criterion.

  10. What underlies succesful word problem solving: A path analysis in sixth grade students

    NARCIS (Netherlands)

    Boonen, A.J.H.; van der Schoot, M.; van Wesel, F.; de Vries, M.H.; Jolles, J.

    2013-01-01

    Two component skills are thought to be necessary for successful word problem solving: (1) the production of visual-schematic representations and (2) the derivation of the correct relations between the solution-relevant elements from the text base. The first component skill is grounded in the

  11. CDC Vital Signs: Binge Drinking a Serious, Under-Recognized Problem Among Women and Girls

    Science.gov (United States)

    ... frequently – about 3 times a month – and have about 6 drinks per binge. There are effective actions communities can take to prevent binge drinking among women and girls. *Binge drinking for women is defined as consuming 4 ormore alcohol drinks (beer, wine, or liquor) on an occasion. Problem Drinking too ...

  12. Modeling and Optimization of the Multiobjective Stochastic Joint Replenishment and Delivery Problem under Supply Chain Environment

    Directory of Open Access Journals (Sweden)

    Lin Wang

    2013-01-01

    Full Text Available As a practical inventory and transportation problem, it is important to synthesize several objectives for the joint replenishment and delivery (JRD decision. In this paper, a new multiobjective stochastic JRD (MSJRD of the one-warehouse and n-retailer systems considering the balance of service level and total cost simultaneously is proposed. The goal of this problem is to decide the reasonable replenishment interval, safety stock factor, and traveling routing. Secondly, two approaches are designed to handle this complex multi-objective optimization problem. Linear programming (LP approach converts the multi-objective to single objective, while a multi-objective evolution algorithm (MOEA solves a multi-objective problem directly. Thirdly, three intelligent optimization algorithms, differential evolution algorithm (DE, hybrid DE (HDE, and genetic algorithm (GA, are utilized in LP-based and MOEA-based approaches. Results of the MSJRD with LP-based and MOEA-based approaches are compared by a contrastive numerical example. To analyses the nondominated solution of MOEA, a metric is also used to measure the distribution of the last generation solution. Results show that HDE outperforms DE and GA whenever LP or MOEA is adopted.

  13. Statics and buckling problems of aircraft structurally-anisotropic composite panels with the influence of production technology

    Science.gov (United States)

    Gavva, L. M.; Endogur, A. I.

    2018-02-01

    The mathematical model relations for stress-strain state and for buckling investigation of structurally-anisotropic panels made of composite materials are presented. The mathematical model of stiffening rib being torsioned under one-side contact with the skin is refined. One takes into account the influence of panel production technology: residual thermal stresses and reinforcing fibers preliminary tension. The resolved eight order equation and natural boundary conditions are obtained with variation Lagrange procedure. Exact analytical solutions for edge problems are considered. Computer program package is developed using operating MATLAB environment. The influence of the structure parameters on the level of stresses, displacements, of critical buckling forces for bending and for torsion modes has analyzed.

  14. Managing the endogeneity problem of the market structure: a study on banking competition

    Directory of Open Access Journals (Sweden)

    Tri Mulyaningsih

    2015-10-01

    Full Text Available Recent literature suggests that the market structure is an endogenous variable that is determined by a firm’s behaviour and the competitive environment of the industry. This study examines the relation between the market structure and the banks’ behaviour in Indonesian banking by considering the endogeneity problem of them as variables. The estimations using the Vector-Error-Correction approach suggest that the structural approach provides a valid prediction of the relationship between market structure and bank behaviour by recognizing the endogeneity issue between those two variables. The banking industry would be more competitive if the market was less concentrated.

  15. Structural modification of aluminium oxynitride phases under stresses at high temperatures, high pressures and under irradiation by fast neutrons

    International Nuclear Information System (INIS)

    Labbe, J.C.; Jeanne, A.; Roult, G.

    1990-01-01

    The structural modifications of the aluminium oxynitride phases under stresses are studied by the time of flight neutron diffraction method, at high temperatures (up to 1375degC), at high pressures (up to 2.4 GPa), and under irradiation by fast neutrons (up to 3.2 X 10 20 n/cm 2 ). In each case the evolutions of cell parameter, interatomic bond angles, bond lengths and atomic positions are given. (orig.)

  16. Structural behavior of human lumbar intervertebral disc under direct shear.

    Science.gov (United States)

    Schmidt, Hendrik; Häussler, Kim; Wilke, Hans-Joachim; Wolfram, Uwe

    2015-03-18

    The intervertebral disc (IVD) is a complex, flexible joint between adjacent vertebral bodies that provides load transmission while permitting movements of the spinal column. Finite element models can be used to help clarify why and how IVDs fail or degenerate. To do so, it is of importance to validate those models against controllable experiments. Due to missing experimental data, shear properties are not used thus far in validating finite element models. This study aimed to investigate the structural shear properties of human lumbar IVDs in posteroanterior (PA) and laterolateral (LL) loading directions. Fourteen lumbar IVDs (median age: 49 years) underwent direct shear in PA and LL loading directions. A custom-build shear device was used in combination with a materials testing machine to load the specimens until failure. Shear stiffness, ultimate shear force and displacement, and work to failure were determined. Each specimen was tested until complete or partial disruption. Median stiffness in PA direction was 490 N/mm and in LL direction 568 N/mm. Median ultimate shear force in the PA direction was 2,877 N and in the LL direction 3,199 N. Work to failure was 12 Nm in the PA and 9 Nm in the LL direction. This study was an experiment to subject IVDs to direct shear. The results could help us to understand the structure and function of IVDs with regard to mechanical spinal stability, and they can be used to validate finite element models of the IVD.

  17. Heuristic algorithms for feature selection under Bayesian models with block-diagonal covariance structure.

    Science.gov (United States)

    Foroughi Pour, Ali; Dalton, Lori A

    2018-03-21

    Many bioinformatics studies aim to identify markers, or features, that can be used to discriminate between distinct groups. In problems where strong individual markers are not available, or where interactions between gene products are of primary interest, it may be necessary to consider combinations of features as a marker family. To this end, recent work proposes a hierarchical Bayesian framework for feature selection that places a prior on the set of features we wish to select and on the label-conditioned feature distribution. While an analytical posterior under Gaussian models with block covariance structures is available, the optimal feature selection algorithm for this model remains intractable since it requires evaluating the posterior over the space of all possible covariance block structures and feature-block assignments. To address this computational barrier, in prior work we proposed a simple suboptimal algorithm, 2MNC-Robust, with robust performance across the space of block structures. Here, we present three new heuristic feature selection algorithms. The proposed algorithms outperform 2MNC-Robust and many other popular feature selection algorithms on synthetic data. In addition, enrichment analysis on real breast cancer, colon cancer, and Leukemia data indicates they also output many of the genes and pathways linked to the cancers under study. Bayesian feature selection is a promising framework for small-sample high-dimensional data, in particular biomarker discovery applications. When applied to cancer data these algorithms outputted many genes already shown to be involved in cancer as well as potentially new biomarkers. Furthermore, one of the proposed algorithms, SPM, outputs blocks of heavily correlated genes, particularly useful for studying gene interactions and gene networks.

  18. THE APPLICATION OF WAVELET-MULTIFRACTAL ANALYSIS IN PROBLEMS OF METAL STRUCTURE

    Directory of Open Access Journals (Sweden)

    VOLCHUK V. N.

    2015-09-01

    Full Text Available Raising of problem. In order to obtain acceptable results of the evaluation of the metal structure developed methodology should include the use of both classical and modern methods of its evaluation and the properties of the produced goods. Thus, to establish the relationship between mechanical properties and structural elements of metal to use multifractal theory. The proposed method is the most appropriate to quantify the majority of real structures, which are integral approximation figures Euclid introduces some uncertainty, and therefore not always acceptable in practical problems of modern materials science. According to the proposed method, each of heterogeneous objects, which are the structures most metals can be characterized by variety of statistical Renyi dimensions. The range of dimensions multifractals interpreted as some of the physical laws, which have a separate statistical properties that make it possible to their financial performance. Application of statistical dimensions of the structural elements for the assessment of qualitative characteristics of metal contributes to their formalization as a function of the fractal dimension. This in turn makes it possible to identify and anticipate the physical and mechanical properties of the metal without producing special mechanical tests. Purpose  obtain information about the possible application of wavelet-multifractal analysis to assess the microstructure of the metal. Conclusion. Using the methods of wavelet multifractal analysis, a statistical evaluation of the structural elements of steel St3ps. An analysis of the characteristics of uniformity, consistency and regularity of the structural elements has shown that most of the change observed in the samples subjected to accelerated cooling water in the temperature range of the intermediate (bainitic conversion 550 – 4500С, less - in samples cooled in the temperature range 650 pearlite transformation  6000С and the smallest

  19. A tabu search approach for the NMR protein structure-based assignment problem.

    Science.gov (United States)

    Cavuşlar, Gizem; Çatay, Bülent; Apaydın, Mehmet Serkan

    2012-01-01

    Spectroscopy is an experimental technique which exploits the magnetic properties of specific nuclei and enables the study of proteins in solution. The key bottleneck of NMR studies is to map the NMR peaks to corresponding nuclei, also known as the assignment problem. Structure-Based Assignment (SBA) is an approach to solve this computationally challenging problem by using prior information about the protein obtained from a homologous structure. NVR-BIP used the Nuclear Vector Replacement (NVR) framework to model SBA as a binary integer programming problem. In this paper, we prove that this problem is NP-hard and propose a tabu search (TS) algorithm (NVR-TS) equipped with a guided perturbation mechanism to efficiently solve it. NVR-TS uses a quadratic penalty relaxation of NVR-BIP where the violations in the Nuclear Overhauser Effect constraints are penalized in the objective function. Experimental results indicate that our algorithm finds the optimal solution on NVRBIP’s data set which consists of seven proteins with 25 templates (31 to 126 residues). Furthermore, it achieves relatively high assignment accuracies on two additional large proteins, MBP and EIN (348 and 243 residues, respectively), which NVR-BIP failed to solve. The executable and the input files are available for download at http://people.sabanciuniv.edu/catay/NVR-TS/NVR-TS.html.

  20. On the structure of 3-dimensional 2-body problem solutions in Wheeler-Feynman electrodynamics

    International Nuclear Information System (INIS)

    Klimenko, S.; Nikitin, I.

    2001-01-01

    The problem of the relativistic 3-dimensional motion of 2 oppositely charged equally massive particles in classical electrodynamics with half-retarded/half-advanced interactions is investigated. It is shown that at a certain critical energy value the topological structure of phase space is changed, leading to bifurcation (splitting) of solutions, appearance of extra non-Newtonian degrees of freedom and break of reflectional symmetries

  1. On optimal upgrade level for used products under given cost structures

    International Nuclear Information System (INIS)

    Shafiee, Mahmood; Finkelstein, Maxim; Chukova, Stefanka

    2011-01-01

    In spite of the growing share of the second-hand market, often customers of used products encounter the following three problems: (a) they are uncertain regarding the durability and performance of these products due to lack of information on the item's past usage and maintenance history, (b) they are uncertain about the accurate pricing of warranties and the post-warranty repair costs, and (c) sometimes, right after the sale, used items may have high failure rate and could be harmful to their new owner. Due to these problems, the dealers are currently carrying out actions such as overhaul and upgrade of the used products before their release. Reliability improvement, which is closely related to the concept of warranty, for used products is a relatively new concept and has received very limited attention. This paper also develops a stochastic model which results in the derivation of the optimal expected upgrade level under given structures of the profit and failure rate functions. We provide a numerical study to illustrate our results.

  2. Structural evaluation of electrosleeved tubes under severe accident transients

    International Nuclear Information System (INIS)

    Majumdar, S.

    1999-01-01

    A flow stress model was developed for predicting failure of Electrosleeved PWR steam generator tubing under severe accident transients. The Electrosleeve, which is nanocrystalline pure nickel, loses its strength at temperatures greater than 400 C during severe accidents because of grain growth. A grain growth model and the Hall-Petch relationship were used to calculate the loss of flow stress as a function of time and temperature during the accident. Available tensile test data as well as high temperature failure tests on notched Electrosleeved tube specimens were used to derive the basic parameters of the failure model. The model was used to predict the failure temperatures of Electrosleeved tubes with axial cracks in the parent tube during postulated severe accident transients

  3. Nonequilibrium structure of colloidal dumbbells under oscillatory shear.

    Science.gov (United States)

    Heptner, Nils; Chu, Fangfang; Lu, Yan; Lindner, Peter; Ballauff, Matthias; Dzubiella, Joachim

    2015-11-01

    We investigate the nonequilibrium behavior of dense, plastic-crystalline suspensions of mildly anisotropic colloidal hard dumbbells under the action of an oscillatory shear field by employing Brownian dynamics computer simulations. In particular, we extend previous investigations, where we uncovered nonequilibrium phase transitions, to other aspect ratios and to a larger nonequilibrium parameter space, that is, a wider range of strains and shear frequencies. We compare and discuss selected results in the context of scattering and rheological experiments. Both simulations and experiments demonstrate that the previously found transitions from the plastic crystal phase with increasing shear strain also occur at other aspect ratios. We explore the transition behavior in the strain-frequency phase and summarize it in a nonequilibrium phase diagram. Additionally, the experimental rheology results hint at a slowing down of the colloidal dynamics with higher aspect ratio.

  4. Finite element modeling of Balsa wood structures under severe loadings

    International Nuclear Information System (INIS)

    Toson, B.; Pesque, J.J.; Viot, P.

    2014-01-01

    In order to compute, in various situations, the requirements for transporting packages using Balsa wood as an energy absorber, a constitutive model is needed that takes into account all of the specific characteristics of the wood, such as its anisotropy, compressibility, softening, densification, and strain rate dependence. Such a model must also include the treatment of rupture of the wood when it is in traction. The complete description of wood behavior is not sufficient: robustness is also necessary because this model has to work in presence of large deformations and of many other external nonlinear phenomena in the surrounding structures. We propose such a constitutive model that we have developed using the commercial finite element package ABAQUS. The necessary data were acquired through an extensive compilation of the existing literature with the augmentation of personal measurements. Numerous validation tests are presented that represent different impact situations that a transportation cask might endure. (authors)

  5. Structural attributes of stand overstory and light under the canopy

    Directory of Open Access Journals (Sweden)

    Alice Angelini

    2015-02-01

    Full Text Available  This paper reviews the literature relating to the relationship between light availability in the understory and the main qualitative and quantitative attributes of stand overstory usually considered in forest management and planning (species composition, density, tree sizes, etc. as well as their changes as consequences of harvesting. The paper is divided in two sections: the first one reviews studies which investigated the influence of species composition on understory light conditions; the second part examines research on the relationships among stand parameters determined from dendrometric field data and the radiation on understory layer. The objective was to highlight which are the most significant stand traits and management features to build more practical models for predicting light regimes in any forest stand and, in more general terms, to support forest managers in planning and designing silvicultural treatments that retain structure in different way in order to meet different objectives.

  6. Durability reliability analysis for corroding concrete structures under uncertainty

    Science.gov (United States)

    Zhang, Hao

    2018-02-01

    This paper presents a durability reliability analysis of reinforced concrete structures subject to the action of marine chloride. The focus is to provide insight into the role of epistemic uncertainties on durability reliability. The corrosion model involves a number of variables whose probabilistic characteristics cannot be fully determined due to the limited availability of supporting data. All sources of uncertainty, both aleatory and epistemic, should be included in the reliability analysis. Two methods are available to formulate the epistemic uncertainty: the imprecise probability-based method and the purely probabilistic method in which the epistemic uncertainties are modeled as random variables. The paper illustrates how the epistemic uncertainties are modeled and propagated in the two methods, and shows how epistemic uncertainties govern the durability reliability.

  7. Chemical Structures of Novel Maillard Reaction Products under Hyperglycemic Conditions.

    Science.gov (United States)

    Imahori, Daisuke; Matsumoto, Takahiro; Kojima, Naoto; Hasei, Tomohiro; Sumii, Megumi; Sumida, Taishi; Yamashita, Masayuki; Watanabe, Tetsushi

    2018-01-01

    Two novel and two known compounds, 4-quinolylaldoxime and indole-3-aldehyde, were isolated from a reaction mixture consisting of D-glucose and L-tryptophan at physiological temperature and pH. The chemical structures of the two novel compounds were elucidated by spectroscopic analysis such as X-ray crystallography. One of the novel compound and the indole-3-aldehyde showed mutagenicity toward Salmonella typhimurium YG1024 with S9 mix. Furthermore, 4-quinolylaldoxime was detected from streptozotocin-induced diabetic rat plasma by LC-MS/MS analysis; however, the isolated compounds were not detected in rat diet extracts. To our knowledge, this is the first report in which 4-quinolylaldoxime was detected in rat plasma. These results suggest that amino-carbonyl reaction products may be formed in diabetic condition and induce genetic damage.

  8. Anti-plane problem analysis for icosahedral quasicrystals under shear loadings

    Science.gov (United States)

    Li, Wu; Chai, Yu-Zhen

    2014-11-01

    The present paper is concerned with the longitudinal shear elasticity of three-dimensional icosahedral quasicrystals. By virtue of the Dugdale hypothesis along with the method of complex potential theory, it involves two defect problems of the icosahedral quasicrystals. The first one is the calculation of stress intensity factors and the size of the cohesive force zone in a half-infinite crack. Meanwhile, the crack tip tearing displacements can be exactly derived. The other is the demonstration of the generalized stress intensity factors induced by a sharp V-notch as an extension of a crack. The generalized E-integral around the notch tip gives the energy release rate when the V-notch degenerates into a crack. Apart from their own usefulness in carrying out some simplified crack analyses, the results obtained in this work can particularly serve as a basis for fracture mechanics of anti-plane defect problems of icosahedral quasicrystals.

  9. Action minimizers under topological constraints in the planar equal-mass four-body problem

    Science.gov (United States)

    Yan, Duokui

    2018-04-01

    It is shown that in the planar equal-mass four-body problem, there exist two sets of action minimizers connecting two planar boundary configurations with fixed symmetry axes and specific order constraints: a double isosceles configuration and an isosceles trapezoid configuration, while order constraints are introduced on the boundary configurations. By applying the level estimate method, these minimizers are shown to be collision-free and they can be extended to two new sets of periodic or quasi-periodic orbits.

  10. Anticipating students' reasoning and planning prompts in structured problem-solving lessons

    Science.gov (United States)

    Vale, Colleen; Widjaja, Wanty; Doig, Brian; Groves, Susie

    2018-02-01

    Structured problem-solving lessons are used to explore mathematical concepts such as pattern and relationships in early algebra, and regularly used in Japanese Lesson Study research lessons. However, enactment of structured problem-solving lessons which involves detailed planning, anticipation of student solutions and orchestration of whole-class discussion of solutions is an ongoing challenge for many teachers. Moreover, primary teachers have limited experience in teaching early algebra or mathematical reasoning actions such as generalising. In this study, the critical factors of enacting the structured problem-solving lessons used in Japanese Lesson Study to elicit and develop primary students' capacity to generalise are explored. Teachers from three primary schools participated in two Japanese Lesson Study teams for this study. The lesson plans and video recordings of teaching and post-lesson discussion of the two research lessons along with students' responses and learning are compared to identify critical factors. The anticipation of students' reasoning together with preparation of supporting and challenging prompts was critical for scaffolding students' capacity to grasp and communicate generality.

  11. A Hybrid Optimization Method for Solving Bayesian Inverse Problems under Uncertainty.

    Directory of Open Access Journals (Sweden)

    Kai Zhang

    Full Text Available In this paper, we investigate the application of a new method, the Finite Difference and Stochastic Gradient (Hybrid method, for history matching in reservoir models. History matching is one of the processes of solving an inverse problem by calibrating reservoir models to dynamic behaviour of the reservoir in which an objective function is formulated based on a Bayesian approach for optimization. The goal of history matching is to identify the minimum value of an objective function that expresses the misfit between the predicted and measured data of a reservoir. To address the optimization problem, we present a novel application using a combination of the stochastic gradient and finite difference methods for solving inverse problems. The optimization is constrained by a linear equation that contains the reservoir parameters. We reformulate the reservoir model's parameters and dynamic data by operating the objective function, the approximate gradient of which can guarantee convergence. At each iteration step, we obtain the relatively 'important' elements of the gradient, which are subsequently substituted by the values from the Finite Difference method through comparing the magnitude of the components of the stochastic gradient, which forms a new gradient, and we subsequently iterate with the new gradient. Through the application of the Hybrid method, we efficiently and accurately optimize the objective function. We present a number numerical simulations in this paper that show that the method is accurate and computationally efficient.

  12. Fractionating the neural correlates of individual working memory components underlying arithmetic problem solving skills in children.

    Science.gov (United States)

    Metcalfe, Arron W S; Ashkenazi, Sarit; Rosenberg-Lee, Miriam; Menon, Vinod

    2013-10-01

    Baddeley and Hitch's multi-component working memory (WM) model has played an enduring and influential role in our understanding of cognitive abilities. Very little is known, however, about the neural basis of this multi-component WM model and the differential role each component plays in mediating arithmetic problem solving abilities in children. Here, we investigate the neural basis of the central executive (CE), phonological (PL) and visuo-spatial (VS) components of WM during a demanding mental arithmetic task in 7-9 year old children (N=74). The VS component was the strongest predictor of math ability in children and was associated with increased arithmetic complexity-related responses in left dorsolateral and right ventrolateral prefrontal cortices as well as bilateral intra-parietal sulcus and supramarginal gyrus in posterior parietal cortex. Critically, VS, CE and PL abilities were associated with largely distinct patterns of brain response. Overlap between VS and CE components was observed in left supramarginal gyrus and no overlap was observed between VS and PL components. Our findings point to a central role of visuo-spatial WM during arithmetic problem-solving in young grade-school children and highlight the usefulness of the multi-component Baddeley and Hitch WM model in fractionating the neural correlates of arithmetic problem solving during development. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Statistical structure of intrinsic climate variability under global warming

    Science.gov (United States)

    Zhu, Xiuhua; Bye, John; Fraedrich, Klaus

    2017-04-01

    Climate variability is often studied in terms of fluctuations with respect to the mean state, whereas the dependence between the mean and variability is rarely discussed. We propose a new climate metric to measure the relationship between means and standard deviations of annual surface temperature computed over non-overlapping 100-year segments. This metric is analyzed based on equilibrium simulations of the Max Planck Institute-Earth System Model (MPI-ESM): the last millennium climate (800-1799), the future climate projection following the A1B scenario (2100-2199), and the 3100-year unforced control simulation. A linear relationship is globally observed in the control simulation and thus termed intrinsic climate variability, which is most pronounced in the tropical region with negative regression slopes over the Pacific warm pool and positive slopes in the eastern tropical Pacific. It relates to asymmetric changes in temperature extremes and associates fluctuating climate means with increase or decrease in intensity and occurrence of both El Niño and La Niña events. In the future scenario period, the linear regression slopes largely retain their spatial structure with appreciable changes in intensity and geographical locations. Since intrinsic climate variability describes the internal rhythm of the climate system, it may serve as guidance for interpreting climate variability and climate change signals in the past and the future.

  14. Structural changes in elastically stressed crystallites under irradiation

    International Nuclear Information System (INIS)

    Zolnikov, K.P.; Korchuganov, A.V.; Kryzhevich, D.S.; Chernov, V.M.; Psakhie, S.G.

    2015-01-01

    The response of elastically stressed iron and vanadium crystallites to atomic displacement cascades was investigated by molecular dynamics simulation. Interatomic interaction in vanadium was described by a many-body potential calculated in the Finnis–Sinclair approximation of the embedded atom method. Interatomic interaction in iron was described by a many-body potential constructed in the approximation of valence-electron gas. The crystallite temperature in the calculations was varied from 100 to 600 K. The elastically stressed state in the crystallites was formed through uniaxial tension by 4–8% such that their volume remained unchanged. The energy of a primary knock-on atom was varied from 0.5 to 50 keV. It is shown that the lower the temperature and the higher the strain degree of an initial crystallite, the lower the threshold primary knock-on atom energy for plastic deformation generation in the crystallite. The structural rearrangements induced in the crystallites by an atomic displacement cascade are similar to those induced by mechanical loading. It is found that the rearrangements are realized through twinning

  15. Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

    Science.gov (United States)

    Flaga, Kazimierz; Furtak, Kazimierz

    2015-03-01

    Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life). The most commonly found in practice are composite girder bridges, particularly in highway bridges of small and medium spans, but the spans may reach over 200 m. In larger spans steel truss girders are applied. Bridge composite structures are also employed in cable-stayed bridge decks of the main girder spans of the order of 600, 800 m. The aim of the article is to present the cionstruction process and strength analysis problems concerning of this type of structures. Much attention is paid to the design and calculation of the shear connectors characteristic for the discussed objects. The authors focused mainly on the issues of single composite structures. The effect of assembly states on the stresses and strains in composite members are highlighted. A separate part of problems is devoted to the influence of rheological factors, i.e. concrete shrinkage and creep, as well as thermal factors on the stresses and strains and redistribution of internal forces.

  16. The Privacy Problem: Although School Librarians Seldom Discuss It, Students' Privacy Rights Are under Attack

    Science.gov (United States)

    Adams, Helen R.

    2011-01-01

    Every day in school libraries nationwide, students' privacy rights are under attack, but many principals, teachers, parents, and community members do not know much about these rights. Even though school librarians are among the strongest proponents of privacy, the subject is rarely discussed, probably because state and federal laws can be…

  17. Lifetime Reliability Prediction of Ceramic Structures Under Transient Thermomechanical Loads

    Science.gov (United States)

    Nemeth, Noel N.; Jadaan, Osama J.; Gyekenyesi, John P.

    2005-01-01

    An analytical methodology is developed to predict the probability of survival (reliability) of ceramic components subjected to harsh thermomechanical loads that can vary with time (transient reliability analysis). This capability enables more accurate prediction of ceramic component integrity against fracture in situations such as turbine startup and shutdown, operational vibrations, atmospheric reentry, or other rapid heating or cooling situations (thermal shock). The transient reliability analysis methodology developed herein incorporates the following features: fast-fracture transient analysis (reliability analysis without slow crack growth, SCG); transient analysis with SCG (reliability analysis with time-dependent damage due to SCG); a computationally efficient algorithm to compute the reliability for components subjected to repeated transient loading (block loading); cyclic fatigue modeling using a combined SCG and Walker fatigue law; proof testing for transient loads; and Weibull and fatigue parameters that are allowed to vary with temperature or time. Component-to-component variation in strength (stochastic strength response) is accounted for with the Weibull distribution, and either the principle of independent action or the Batdorf theory is used to predict the effect of multiaxial stresses on reliability. The reliability analysis can be performed either as a function of the component surface (for surface-distributed flaws) or component volume (for volume-distributed flaws). The transient reliability analysis capability has been added to the NASA CARES/ Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code. CARES/Life was also updated to interface with commercially available finite element analysis software, such as ANSYS, when used to model the effects of transient load histories. Examples are provided to demonstrate the features of the methodology as implemented in the CARES/Life program.

  18. Portfolio selection problem with liquidity constraints under non-extensive statistical mechanics

    International Nuclear Information System (INIS)

    Zhao, Pan; Xiao, Qingxian

    2016-01-01

    In this study, we consider the optimal portfolio selection problem with liquidity limits. A portfolio selection model is proposed in which the risky asset price is driven by the process based on non-extensive statistical mechanics instead of the classic Wiener process. Using dynamic programming and Lagrange multiplier methods, we obtain the optimal policy and value function. Moreover, the numerical results indicate that this model is considerably different from the model based on the classic Wiener process, the optimal strategy is affected by the non-extensive parameter q, the increase in the investment in the risky asset is faster at a larger parameter q and the increase in wealth is similar.

  19. An Optimization Approach for Hazardous Waste Management Problem under Stochastic Programming

    International Nuclear Information System (INIS)

    Abass, S.A.; Abdallah, A.S.; Gomaa, M.A.

    2008-01-01

    Hazardous waste is the waste which, due to their nature and quantity, is potentially hazardous to human health and/or the environment. This kind of waste requires special disposal techniques to eliminate or reduce thc hazardous. Hazardous waste management (HWM) problem is concerned in the basic with the disposal method. hi this paper we focus on incineration as an effective to dispose the waste. For this type of disposal, there arc air pollution standards imposed by the government. We will propose an optimization model satisfied the air pollution standards and based on the model of Emek and Kara with using random variable coefficients in the constraint

  20. Conjugate problems of transport phenomena under quasi-steady microaccelerations in realistic spaceflight.

    Science.gov (United States)

    Polezhaev, V I; Nikitin, S A

    2009-04-01

    A new model for spatial convective transport processes conjugated with the measured or calculated realistic quasi-steady microaccelerations is presented. Rotation around the mass center, including accelerated rotation, gravity gradient, and aerodynamical drag are taken into account. New results of the effect on mixing and concentration inhomogeneities of the elementary convective processes are presented. The mixing problem in spacecraft enclosures, concentration inhomogeneities due to convection induced by body forces in realistic spaceflight, and the coupling of this kind of convection with thermocapillary convection on the basis of this model are discussed.

  1. Toward the Soundness of Sense Structure Definitions in Thesaurus-Dictionaries. Parsing Problems and Solutions

    Directory of Open Access Journals (Sweden)

    Neculai Curteanu

    2012-10-01

    Full Text Available In this paper we point out some difficult problems of thesaurus-dictionary entry parsing, relying on the parsing technology of SCD (Segmentation-Cohesion-Dependency configurations, successfully applied on six largest thesauri -- Romanian (2, French, German (2, and Russian. \\textbf{Challenging Problems:} \\textbf{(a}~Intricate and~/~or recursive structures of the lexicographic segments met in the entries of certain thesauri; \\textbf{(b}~Cyclicity (recursive calls of some sense marker classes on marker sequences; \\textbf{(c}~Establishing the hypergraph-driven dependencies between all the atomic and non-atomic sense definitions. Classical approach to solve these parsing problems is hard mainly because of depth-first search of sense definitions and markers, the substantial complexity of entries, and the sense tree dynamic construction embodied within these parsers. \\textbf{SCD-based Parsing Solutions:} \\textbf{(a}~The SCD parsing method is a procedural tool, completely formal grammar-free, handling the recursive structure of the lexicographic segments by procedural non-recursive calls performed on the SCD parsing configurations of the entry structure. \\textbf{(b}~For dealing with cyclicity (recursive calls between secondary sense markers and the sense enumeration markers, we proposed the Enumeration Closing Condition, sometimes coupled with New{\\_}Paragraphs typographic markers transformed into numeral sense enumeration. \\textbf{(c}~These problems, their lexicographic modeling and parsing solutions are addressed to both dictionary parser programmers to experience the SCD-based parsing method, as well as to lexicographers and thesauri designers for tailoring balanced lexical-semantics granularities and sounder sense tree definitions of the dictionary entries.

  2. Optimizing decentralized production-distribution planning problem in a multi-period supply chain network under uncertainty

    Science.gov (United States)

    Nourifar, Raheleh; Mahdavi, Iraj; Mahdavi-Amiri, Nezam; Paydar, Mohammad Mahdi

    2017-09-01

    Decentralized supply chain management is found to be significantly relevant in today's competitive markets. Production and distribution planning is posed as an important optimization problem in supply chain networks. Here, we propose a multi-period decentralized supply chain network model with uncertainty. The imprecision related to uncertain parameters like demand and price of the final product is appropriated with stochastic and fuzzy numbers. We provide mathematical formulation of the problem as a bi-level mixed integer linear programming model. Due to problem's convolution, a structure to solve is developed that incorporates a novel heuristic algorithm based on Kth-best algorithm, fuzzy approach and chance constraint approach. Ultimately, a numerical example is constructed and worked through to demonstrate applicability of the optimization model. A sensitivity analysis is also made.

  3. Identifying the number of population clusters with structure: problems and solutions.

    Science.gov (United States)

    Gilbert, Kimberly J

    2016-05-01

    The program structure has been used extensively to understand and visualize population genetic structure. It is one of the most commonly used clustering algorithms, cited over 11,500 times in Web of Science since its introduction in 2000. The method estimates ancestry proportions to assign individuals to clusters, and post hoc analyses of results may indicate the most likely number of clusters, or populations, on the landscape. However, as has been shown in this issue of Molecular Ecology Resources by Puechmaille (), when sampling is uneven across populations or across hierarchical levels of population structure, these post hoc analyses can be inaccurate and identify an incorrect number of population clusters. To solve this problem, Puechmaille () presents strategies for subsampling and new analysis methods that are robust to uneven sampling to improve inferences of the number of population clusters. © 2016 John Wiley & Sons Ltd.

  4. INDICATOR OF ENVIRONMENTAL PROBLEMS OF AGRICULTURAL SECTORS UNDER THE ENVIRONMENTAL MODELING

    Directory of Open Access Journals (Sweden)

    Pruethsan Sutthichaimethee

    2016-04-01

    Full Text Available The objective of this research is to propose an indicator to deal with environmental problems for agricultural sectors caused by goods and services production. The aspects to calculate the real benefit of agricultural sectors and environmental cost for analyzing are natural resources materials, energy and transportation, fertilizer and pesticides, and sanitary and similar service. From the research it was found that the highest environmental cost of natural resources materials was 026: charcoal and fire-wood, while the lowest was 010 coconut. The highest environmental cost for energy and transportation was 024: agricultural services, while the highest environmental cost for fertilizer and pesticides was 011: palm oil. lastly, 017: other agricultural products was found as the highest environmental cost for sanitary and similar service. As a result, 010: coconut gained the highest real benefit, while 024: agricultural services presented as the lowest read benefit for the company. If Thailand using environmental problem indicator, especially with the agricultural sector, it can help to formulate efficient policies and strategies for the country in 3 development areas, which are social, economic, and environmental development.

  5. Generalized stochastic target problems for pricing and partial hedging under loss constraints - Application in optimal book liquidation

    OpenAIRE

    Bouchard , Bruno; Dang , Ngoc Minh

    2013-01-01

    International audience; We consider a singular with state constraints version of the stochastic target problems studied in Soner and Touzi (2002) and more recently Bouchard, Elie and Touzi (2008), among others. This provides a general framework for the pricing of contingent claims under risk constraints. Our extended version perfectly suits to market models with proportional transaction costs and to order book liquidation issues. Our main result is a PDE characterization of the associated pri...

  6. Using concept mapping to evaluate knowledge structure in problem-based learning.

    Science.gov (United States)

    Hung, Chia-Hui; Lin, Chen-Yung

    2015-11-27

    Many educational programs incorporate problem-based learning (PBL) to promote students' learning; however, the knowledge structure developed in PBL remains unclear. The aim of this study was to use concept mapping to generate an understanding of the use of PBL in the development of knowledge structures. Using a quasi-experimental study design, we employed concept mapping to illustrate the effects of PBL by examining the patterns of concepts and differences in the knowledge structures of students taught with and without a PBL approach. Fifty-two occupational therapy undergraduates were involved in the study and were randomly divided into PBL and control groups. The PBL group was given two case scenarios for small group discussion, while the control group continued with ordinary teaching and learning. Students were asked to make concept maps after being taught about knowledge structure. A descriptive analysis of the morphology of concept maps was conducted in order to compare the integration of the students' knowledge structures, and statistical analyses were done to understand the differences between groups. Three categories of concept maps were identified as follows: isolated, departmental, and integrated. The students in the control group constructed more isolated maps, while the students in the PBL group tended toward integrated mapping. Concept Relationships, Hierarchy Levels, and Cross Linkages in the concept maps were significantly greater in the PBL group; however, examples of concept maps did not differ significantly between the two groups. The data indicated that PBL had a strong effect on the acquisition and integration of knowledge. The important properties of PBL, including situational learning, problem spaces, and small group interactions, can help students to acquire more concepts, achieve an integrated knowledge structure, and enhance clinical reasoning.

  7. Possibilities of the particle finite element method for fluid-soil-structure interaction problems

    Science.gov (United States)

    Oñate, Eugenio; Celigueta, Miguel Angel; Idelsohn, Sergio R.; Salazar, Fernando; Suárez, Benjamín

    2011-09-01

    We present some developments in the particle finite element method (PFEM) for analysis of complex coupled problems in mechanics involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in both the fluid and the solid domains (the later including soil/rock and structures). A mesh connects the particles (nodes) defining the discretized domain where the governing equations for each of the constituent materials are solved as in the standard FEM. The stabilization for dealing with an incompressibility continuum is introduced via the finite calculus method. An incremental iterative scheme for the solution of the non linear transient coupled FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present several examples of application of the PFEM to solve FSSI problems such as the motion of rocks by water streams, the erosion of a river bed adjacent to a bridge foundation, the stability of breakwaters and constructions sea waves and the study of landslides.

  8. Self-interacting inelastic dark matter: a viable solution to the small scale structure problems

    Energy Technology Data Exchange (ETDEWEB)

    Blennow, Mattias; Clementz, Stefan; Herrero-Garcia, Juan, E-mail: emb@kth.se, E-mail: scl@kth.se, E-mail: juan.herrero-garcia@adelaide.edu.au [Department of Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm (Sweden)

    2017-03-01

    Self-interacting dark matter has been proposed as a solution to the small-scale structure problems, such as the observed flat cores in dwarf and low surface brightness galaxies. If scattering takes place through light mediators, the scattering cross section relevant to solve these problems may fall into the non-perturbative regime leading to a non-trivial velocity dependence, which allows compatibility with limits stemming from cluster-size objects. However, these models are strongly constrained by different observations, in particular from the requirements that the decay of the light mediator is sufficiently rapid (before Big Bang Nucleosynthesis) and from direct detection. A natural solution to reconcile both requirements are inelastic endothermic interactions, such that scatterings in direct detection experiments are suppressed or even kinematically forbidden if the mass splitting between the two-states is sufficiently large. Using an exact solution when numerically solving the Schrödinger equation, we study such scenarios and find regions in the parameter space of dark matter and mediator masses, and the mass splitting of the states, where the small scale structure problems can be solved, the dark matter has the correct relic abundance and direct detection limits can be evaded.

  9. using fuzzy-robust approach for minimizing transportation and fuel costs in location problem under uncertainty

    Directory of Open Access Journals (Sweden)

    hasan hosseini nasab

    2016-02-01

    Full Text Available Operations research is a commonly used method in many subjects nowadays. One applicable domain of operation research is the problem of facility layout and location. In this paper, a new mathematical programing model is developed for an optimal facility location and assignment. The model includes two objective functions. The first one minimizes the total material handling and fixed costs of facility location. Because of the importance of energy and the main role of fossil fuel in transportation, the second objective function, minimizes the total cost of fuel consumption. To consider the real condition in the proposed model, the cost of fuel, is considered to increase stepwise gradually. In the proposed model the coefficients of objective function are considered to be probabilistic and some of constraints to be fuzzy variables. Using a new approach, this model can be changed to a robust model. To prove the applicability of the model, it is examined for a real condition of facility location.

  10. Periodic boundary-value problems and the Dancer-Fucik spectrum under conditions of resonance

    Directory of Open Access Journals (Sweden)

    David A. Bliss

    2011-08-01

    Full Text Available We prove the existence of solutions to the nonlinear $2 pi$-periodic problem $$displaylines{ u''(x+mu u^+(x-u u^-(x+g(x,u(x=f(x,,quad xin (0,2pi,,cr u(0-u(2pi =0 ,, quad u'(0 - u'(2pi=0, }$$ where the point $(mu,u$ lies in the Dancer-Fucik spectrum, with $$ 0< frac{4}{9}mu leqslant u

  11. Eigenvalue perturbation theory of structured matrices under generic structured rank one perturbations: Symplectic, orthogonal, and unitary matrices.

    NARCIS (Netherlands)

    Ran, A.C.M.; Mehl, Chr.; Mehrmann, V.; Rodman, L.

    2014-01-01

    We study the perturbation theory of structured matrices under structured rank one perturbations, with emphasis on matrices that are unitary, orthogonal, or symplectic with respect to an indefinite inner product. The rank one perturbations are not necessarily of arbitrary small size (in the sense of

  12. Factor structure and psychometric properties of the Fertility Problem Inventory–Short Form

    Directory of Open Access Journals (Sweden)

    Maria Clelia Zurlo

    2017-11-01

    Full Text Available The study analyses factor structure and psychometric properties of the Italian version of the Fertility Problem Inventory–Short Form. A sample of 206 infertile couples completed the Italian version of Fertility Problem Inventory (46 items with demographics, State Anxiety Scale of State-Trait Anxiety Inventory (Form Y, Edinburgh Depression Scale and Dyadic Adjustment Scale, used to assess convergent and discriminant validity. Confirmatory factor analysis was unsatisfactory (comparative fit index = 0.87; Tucker-Lewis Index = 0.83; root mean square error of approximation = 0.17, and Cronbach’s α (0.95 revealed a redundancy of items. Exploratory factor analysis was carried out deleting cross-loading items, and Mokken scale analysis was applied to verify the items homogeneity within the reduced subscales of the questionnaire. The Fertility Problem Inventory–Short Form consists of 27 items, tapping four meaningful and reliable factors. Convergent and discriminant validity were confirmed. Findings indicated that the Fertility Problem Inventory–Short Form is a valid and reliable measure to assess infertility-related stress dimensions.

  13. Conceptions of perfectionism and interpersonal problems: evaluating groups using the structural summary method for circumplex data.

    Science.gov (United States)

    Slaney, Robert B; Pincus, Aaron L; Uliaszek, Amanda A; Wang, Kenneth T

    2006-06-01

    This study examined two conceptions of perfectionism in relation to interpersonal problems. Two hundred and seventy-nine undergraduate participants completed the Almost Perfect Scale-Revised (APS-R) and the Dyadic Almost Perfect Scale (DAPS). The authors used empirically derived discriminant functions (APS-R) and cluster analysis (DAPS) to identify three groups for both measures: adaptive and maladaptive perfectionists and nonperfectionists. Analyses of group profiles were performed on the Inventory of Interpersonal Problems Circumplex (IIP-C) scales using the structural summary method for circumplex data. APS-R and DAPS groups were compared on interpersonal problems endorsement and IIP-C profile characteristics. For both measures, results supported the hypotheses that maladaptive perfectionists would exhibit elevated profiles reflecting hostile-dominant and friendly-submissive interpersonal problems, whereas the adaptive perfectionists would exhibit low profile elevation indicative of interpersonal adjustment. Overall, results supported Slaney and colleagues' (2001) model of perfectionism and provided evidence for the validity of the APS-R and DAPS.

  14. Some problems of biological effects under the combined action of nitrogen oxides, their metabolites and radiation

    International Nuclear Information System (INIS)

    Malenchenko, A.F.

    1985-01-01

    The progress of power engineering envisages the intensive construction of nuclear-energy plants, where an organic or nuclear fuel is used. Nowadays the concept of nuclear-energy plant with the coolant based on dissociating N 2 O 4 is being developed. A great deal of radioactive and chemical products escapes into surroundings as the result of the power plants being in service. Their action on organisms is performed simultaneously, that could have an essential effect on the quantitative and qualitative regularities of response. The estimation of the combined effect of nitrogen oxides, sodium nitrite and nitrate and radiation has been carried out on the base of the investigation into methemoglobin formation, genetic effects and the pathomorphological changes in lungs. The formation of methemoglobin has been studied on rats in 1, 3, 7 and 15 days after the single total irradiation of 300 and 700 R doses at the gamma-installation (UGU-420) using a radioactive 60 Co. Methemoglobin was determined in the interval of 15-180 min after NaNO 2 administration in the dosage of 7.0 mg per 100 g body weight. The irradiation essentially affects the process of methemoglobin formation and its reduction. The methemoglobin content in the blood of radiation exposed animals exceeds the value, that could be expected to obtain by summing up its concentration under the separate effects of nitrite and irradiation. The genetic effects of sodium nitrite and nitrate and X-radiation have been studied on the Drosophila. The one-day flies were exposed to the radiation dose of 1500 R in the medium with the sodium nitrite or nitrate contents of 0.1 or 1.0 g/l, respectively. The combined action estimated through the frequency of the dominant lethal mutation, recessive coupled with a lethal mutation sex, viability and fecundity definitely differs from the expected summing values of the separate effect indices of radiation and toxic factors. The morpho- and functional changes in the rat lungs (the

  15. A computational domain decomposition approach for solving coupled flow-structure-thermal interaction problems

    Directory of Open Access Journals (Sweden)

    Eugenio Aulisa

    2009-04-01

    Full Text Available Solving complex coupled processes involving fluid-structure-thermal interactions is a challenging problem in computational sciences and engineering. Currently there exist numerous public-domain and commercial codes available in the area of Computational Fluid Dynamics (CFD, Computational Structural Dynamics (CSD and Computational Thermodynamics (CTD. Different groups specializing in modelling individual process such as CSD, CFD, CTD often come together to solve a complex coupled application. Direct numerical simulation of the non-linear equations for even the most simplified fluid-structure-thermal interaction (FSTI model depends on the convergence of iterative solvers which in turn rely heavily on the properties of the coupled system. The purpose of this paper is to introduce a flexible multilevel algorithm with finite elements that can be used to study a coupled FSTI. The method relies on decomposing the complex global domain, into several local sub-domains, solving smaller problems over these sub-domains and then gluing back the local solution in an efficient and accurate fashion to yield the global solution. Our numerical results suggest that the proposed solution methodology is robust and reliable.

  16. Traveling salesman problems with PageRank Distance on complex networks reveal community structure

    Science.gov (United States)

    Jiang, Zhongzhou; Liu, Jing; Wang, Shuai

    2016-12-01

    In this paper, we propose a new algorithm for community detection problems (CDPs) based on traveling salesman problems (TSPs), labeled as TSP-CDA. Since TSPs need to find a tour with minimum cost, cities close to each other are usually clustered in the tour. This inspired us to model CDPs as TSPs by taking each vertex as a city. Then, in the final tour, the vertices in the same community tend to cluster together, and the community structure can be obtained by cutting the tour into a couple of paths. There are two challenges. The first is to define a suitable distance between each pair of vertices which can reflect the probability that they belong to the same community. The second is to design a suitable strategy to cut the final tour into paths which can form communities. In TSP-CDA, we deal with these two challenges by defining a PageRank Distance and an automatic threshold-based cutting strategy. The PageRank Distance is designed with the intrinsic properties of CDPs in mind, and can be calculated efficiently. In the experiments, benchmark networks with 1000-10,000 nodes and varying structures are used to test the performance of TSP-CDA. A comparison is also made between TSP-CDA and two well-established community detection algorithms. The results show that TSP-CDA can find accurate community structure efficiently and outperforms the two existing algorithms.

  17. Under-Researched Demographics: Heavy Episodic Drinking and Alcohol-Related Problems Among Asian Americans.

    Science.gov (United States)

    Iwamoto, Derek Kenji; Kaya, Aylin; Grivel, Margaux; Clinton, Lauren

    2016-01-01

    Asian Americans represent the fastest- growing population in the United States (Le 2010). At the same time, there is evidence that problematic drinking rates are increasing among young-adult Asian Americans (Grant et al. 2004). Accordingly, it is essential to understand the etiological determinants and mechanisms of risk that may help explain this growth in problematic alcohol use among this group. The high prevalence of the ALDH2*2 and ADH1B*2 alleles in a large percentage of Asian subgroups has been studied as a potential protective factors against alcohol abuse, yet some individuals who possess these genes still engage in problematic alcohol use (Wall et al. 2001). Other social and psychological factors may account for this discrepancy. Thus, some factors, such as negative physiological alcohol expectancies, are protective against alcohol abuse in this population (Hendershot et al. 2009). Sociocultural factors such as acculturation and nativity also may help explain drinking patterns among this group. The literature suggests that vast and significant within-group differences exist among Asian Americans, such that individuals who were born in the United States and/or are more acculturated are at elevated risk for alcohol abuse and related problems (Hahm et al. 2003). Differences also have been observed among Asian-American ethnic subgroups, with some groups (e.g., Japanese, Korean, and multi-Asian Americans) reporting higher rates of drinking compared with others (e.g., Chinese and Vietnamese Americans) (Iwamoto et al. 2012). Furthermore, Asian Americans who report higher levels of depressive symptoms, psychological distress, and perceived discrimination seem to be at a heightened risk for abusing alcohol (Iwamoto et al. 2011a; Nishimura et al. 2005; Yoo et al. 2010). Finally, an emerging body of research examining gender-relevant factors, including feminine and masculine norms, may help explain within-group differences among Asian-American women and men. Thus

  18. Perspectives of experimental and theoretical studies of self-organized dust structures in complex plasmas under microgravity conditions

    International Nuclear Information System (INIS)

    Tsytovich, V N

    2015-01-01

    We review research aimed at understanding the phenomena occurring in a complex plasma under microgravity conditions. Some aspects of the work already performed are considered that have not previously been given sufficient attention but which are potentially crucial for future work. These aspects, in particular, include the observation of compact dust structures that are estimated to be capable of confining all components of a dust plasma in a bounded spatial volume; experimental evidence of the nonlinear screening of dust particles; and experimental evidence of the excitation of collective electric fields. In theoretical terms, novel collective attraction processes between likely charged dust particles are discussed and all schemes of the shadowy attraction between dust particles used earlier, including in attempts to interpret observations, are reviewed and evaluated. Dust structures are considered from the standpoint of the current self-organization theory. It is emphasized that phase transitions between states of self-organized systems differ significantly from those in homogeneous states and that the phase diagrams should be constructed in terms of the parameters of a self-organized structure and cannot be constructed in terms of the temperature and density or similar parameters of homogeneous structures. Using the existing theoretical approaches to modeling self-organized structures in dust plasmas, the parameter distribution of a structure is recalculated for a simpler model that includes the quasineutrality condition and neglects diffusion. These calculations indicate that under microgravity conditions, any self-organized structure can contain a limited number of dust particles and is finite in size. The maximum possible number of particles in a structure determines the characteristic inter-grain distance in dust crystals that can be created under microgravity conditions. Crystallization criteria for the structures are examined and the quasispherical

  19. The Emergency Vehicle Routing Problem with Uncertain Demand under Sustainability Environments

    Directory of Open Access Journals (Sweden)

    Jin Qin

    2017-02-01

    Full Text Available The reasonable utilization of limited resources is critical to realize the sustainable developments. In the initial 72-h crucial rescue period after the disaster, emergency supplies have always been insufficient and the demands in the affected area have always been uncertain. In order to improve timeliness, utilization and sustainability of emergency service, the allocation of the emergency supplies and the emergency vehicle routes should be determined simultaneously. Assuming the uncertain demands follow normal distribution, an optimization model for the emergency vehicle routing, by considering the insufficient supplies and the uncertain demands, is developed. The objective function is applied to minimize the total costs, including the penalty costs induced by more or less supplies than the actual demands at all demand points, as well as the constraints of the time windows and vehicle load capacity taken into account. In more details, a solution method for the model, based on the genetic algorithm, is proposed, which solves the problem in two stages. A numerical example is presented to demonstrate the efficiency and validity of the proposed model and algorithm.

  20. Two-Stage Multiobjective Optimization for Emergency Supplies Allocation Problem under Integrated Uncertainty

    Directory of Open Access Journals (Sweden)

    Xuejie Bai

    2016-01-01

    Full Text Available This paper proposes a new two-stage optimization method for emergency supplies allocation problem with multisupplier, multiaffected area, multirelief, and multivehicle. The triplet of supply, demand, and the availability of path is unknown prior to the extraordinary event and is descriptive with fuzzy random variable. Considering the fairness, timeliness, and economical efficiency, a multiobjective expected value model is built for facility location, vehicle routing, and supply allocation decisions. The goals of proposed model aim to minimize the proportion of demand nonsatisfied and response time of emergency reliefs and the total cost of the whole process. When the demand and the availability of path are discrete, the expected values in the objective functions are converted into their equivalent forms. When the supply amount is continuous, the equilibrium chance in the constraint is transformed to its equivalent one. To overcome the computational difficulty caused by multiple objectives, a goal programming model is formulated to obtain a compromise solution. Finally, an example is presented to illustrate the validity of the proposed model and the effectiveness of the solution method.

  1. Source selection problem of competitive power plants under government intervention: a game theory approach

    Science.gov (United States)

    Mahmoudi, Reza; Hafezalkotob, Ashkan; Makui, Ahmad

    2014-06-01

    Pollution and environmental protection in the present century are extremely significant global problems. Power plants as the largest pollution emitting industry have been the cause of a great deal of scientific researches. The fuel or source type used to generate electricity by the power plants plays an important role in the amount of pollution produced. Governments should take visible actions to promote green fuel. These actions are often called the governmental financial interventions that include legislations such as green subsidiaries and taxes. In this paper, by considering the government role in the competition of two power plants, we propose a game theoretical model that will help the government to determine the optimal taxes and subsidies. The numerical examples demonstrate how government could intervene in a competitive market of electricity to achieve the environmental objectives and how power plants maximize their utilities in each energy source. The results also reveal that the government's taxes and subsidiaries effectively influence the selected fuel types of power plants in the competitive market.

  2. Optimization of Production-Distribution Problem in Supply Chain Management under Stochastic and Fuzzy Uncertainties

    Directory of Open Access Journals (Sweden)

    Umit Sami Sakalli

    2017-01-01

    Full Text Available Production-Distribution Problem (PDP in Supply Chain Management (SCM is an important tactical decision. One of the challenges in this decision is the size and complexity of supply chain system (SCS. On the other side, a tactical operation is a mid-term plan for 6–12 months; therefore, it includes different types of uncertainties, which is the second challenge. In the literature, the uncertain parameters were modeled as stochastic or fuzzy. However, there are a few studies in the literature that handle stochastic and fuzzy uncertainties simultaneously in PDP. In this paper, the modeling and solution approaches of PDP which contain stochastic and fuzzy uncertainties simultaneously are investigated for a SCS that includes multiple suppliers, multiple products, multiple plants, multiple warehouses, multiple retailers, multiple transport paths, and multiple time periods, which, to the best of the author’s knowledge, is not handled in the literature. The PDP contains deterministic, fuzzy, fuzzy random, and random fuzzy parameters. To the best of the author’s knowledge, there is no study in the literature which considers all of them simultaneously in PDP. An analytic solution approach has been developed by using possibilistic programming and chance-constrained programming approaches. The proposed modeling and solution approaches are implemented in a numerical example. The solution has shown that the proposed approaches successfully handled uncertainties and produce robust solutions for PDP.

  3. Solution to a gene divergence problem under arbitrary stable nucleotide transition probabilities

    Science.gov (United States)

    Holmquist, R.

    1976-01-01

    A nucleic acid chain, L nucleotides in length, with the specific base sequence B(1)B(2) ... B(L) is defined by the L-dimensional vector B = (B(1), B(2), ..., B(L)). For twelve given constant non-negative transition probabilities that, in a specified position, the base B is replaced by the base B' in a single step, an exact analytical expression is derived for the probability that the position goes from base B to B' in X steps. Assuming that each base mutates independently of the others, an exact expression is derived for the probability that the initial gene sequence B goes to a sequence B' = (B'(1), B'(2), ..., B'(L)) after X = (X(1), X(2), ..., X(L)) base replacements. The resulting equations allow a more precise accounting for the effects of Darwinian natural selection in molecular evolution than does the idealized (biologically less accurate) assumption that each of the four nucleotides is equally likely to mutate to and be fixed as one of the other three. Illustrative applications of the theory to some problems of biological evolution are given.

  4. The operating room case-mix problem under uncertainty and nurses capacity constraints.

    Science.gov (United States)

    Yahia, Zakaria; Eltawil, Amr B; Harraz, Nermine A

    2016-12-01

    Surgery is one of the key functions in hospitals; it generates significant revenue and admissions to hospitals. In this paper we address the decision of choosing a case-mix for a surgery department. The objective of this study is to generate an optimal case-mix plan of surgery patients with uncertain surgery operations, which includes uncertainty in surgery durations, length of stay, surgery demand and the availability of nurses. In order to obtain an optimal case-mix plan, a stochastic optimization model is proposed and the sample average approximation method is applied. The proposed model is used to determine the number of surgery cases to be weekly served, the amount of operating rooms' time dedicated to each specialty and the number of ward beds dedicated to each specialty. The optimal case-mix selection criterion is based upon a weighted score taking into account both the waiting list and the historical demand of each patient category. The score aims to maximizing the service level of the operating rooms by increasing the total number of surgery cases that could be served. A computational experiment is presented to demonstrate the performance of the proposed method. The results show that the stochastic model solution outperforms the expected value problem solution. Additional analysis is conducted to study the effect of varying the number of ORs and nurses capacity on the overall ORs' performance.

  5. Probability evaluation in problems of structural safety and quality assurance through oriented simulation

    International Nuclear Information System (INIS)

    Puppo, A.H.

    1990-01-01

    The procedure described in this work may be considered to improve the Harbitz method by a limitation of the directions corresponding to the sampling points. By the introduction of polar coordinates n-dimensional system, these directions may be limited to those contained in an hypercone, whose axis contains the design point. Some problems with strongly convex failure domain presented in some structural systems (Igusa and Der Kiureghian, 1988; Nadim, 1990) and also in the acceptance probability of analysis and rejection of quality assurance methods may be efficiently treated. (Author) [es

  6. Analysis of factors affecting satisfaction level on problem based learning approach using structural equation modeling

    Science.gov (United States)

    Hussain, Nur Farahin Mee; Zahid, Zalina

    2014-12-01

    Nowadays, in the job market demand, graduates are expected not only to have higher performance in academic but they must also be excellent in soft skill. Problem-Based Learning (PBL) has a number of distinct advantages as a learning method as it can deliver graduates that will be highly prized by industry. This study attempts to determine the satisfaction level of engineering students on the PBL Approach and to evaluate their determinant factors. The Structural Equation Modeling (SEM) was used to investigate how the factors of Good Teaching Scale, Clear Goals, Student Assessment and Levels of Workload affected the student satisfaction towards PBL approach.

  7. Teaching ill-structured problem solving using occupational therapy practice epistemology.

    Science.gov (United States)

    Mitchell, Anita Witt

    2013-01-01

    ABSTRACT Epistemic and ontological cognition (EOC) have to do with an individual's beliefs about knowledge and knowing. Research has shown that EOC have an influence on learning and achievement. EOC may be discipline-specific with a profession being defined by its practice epistemology. If an individual's EOC is inconsistent with the profession's practice epistemology, the student or practitioner may struggle with effectively solving ill-structured occupational performance problems. The purpose of this paper is to increase awareness of the constructs of EOC, to describe its importance to occupational therapy education and practice, and to provide recommendations for educators and researchers. Specific examples are detailed and recommendations for future research are proposed.

  8. Genetic Algorithm for Multiuser Discrete Network Design Problem under Demand Uncertainty

    Directory of Open Access Journals (Sweden)

    Wu Juan

    2012-01-01

    Full Text Available Discrete network design is an important part of urban transportation planning. The purpose of this paper is to present a bilevel model for discrete network design. The upper-level model aims to minimize the total travel time under a stochastic demand to design a discrete network. In the lower-level model, demands are assigned to the network through a multiuser traffic equilibrium assignment. Generally, discrete network could affect path selections of demands, while the results of the multiuser traffic equilibrium assignment need to reconstruct a new discrete network. An iterative approach including an improved genetic algorithm and Frank-Wolfe algorithm is used to solve the bi-level model. The numerical results on Nguyen Dupuis network show that the model and the related algorithms were effective for discrete network design.

  9. Scaffolding Middle School Students' Content Knowledge and Ill-Structured Problem Solving in a Problem-Based Hypermedia Learning Environment

    Science.gov (United States)

    Bulu, Saniye Tugba; Pedersen, Susan

    2010-01-01

    This study investigated the effects of domain-general and domain-specific scaffolds with different levels of support, continuous and faded, on learning of scientific content and problem-solving. Students' scores on a multiple-choice pretest, posttest, and four recommendation forms were analyzed. Students' content knowledge in all conditions…

  10. Band connectivity for topological quantum chemistry: Band structures as a graph theory problem

    Science.gov (United States)

    Bradlyn, Barry; Elcoro, L.; Vergniory, M. G.; Cano, Jennifer; Wang, Zhijun; Felser, C.; Aroyo, M. I.; Bernevig, B. Andrei

    2018-01-01

    The conventional theory of solids is well suited to describing band structures locally near isolated points in momentum space, but struggles to capture the full, global picture necessary for understanding topological phenomena. In part of a recent paper [B. Bradlyn et al., Nature (London) 547, 298 (2017), 10.1038/nature23268], we have introduced the way to overcome this difficulty by formulating the problem of sewing together many disconnected local k .p band structures across the Brillouin zone in terms of graph theory. In this paper, we give the details of our full theoretical construction. We show that crystal symmetries strongly constrain the allowed connectivities of energy bands, and we employ graph theoretic techniques such as graph connectivity to enumerate all the solutions to these constraints. The tools of graph theory allow us to identify disconnected groups of bands in these solutions, and so identify topologically distinct insulating phases.

  11. An inverse problem approach for structural damage detection - Finite element model refinement

    Science.gov (United States)

    Zimmerman, D. C.; Kaouk, M.

    1992-01-01

    In this work, a methodology for incorporating measured modal data into an existing refined finite element model is examined with the objective of detecting and locating structural damage. This same algorithm is also useful in terms of finite element model refinement. The algorithm is based on the partial inverse problem, in that only partial spectral information is required. The technique utilizes a symmetric eigenstructure assignment algorithm to perform the partial spectral assignment. Algorithms to enhance mode shape assignability and to preserve sparsity in the updated model are developed. The sparsity preservation is of particular importance when considering damage detection in truss-like structures. Several examples are presented which highlight the key points made within the paper.

  12. Structural damage detection based on stochastic subspace identification and statistical pattern recognition: II. Experimental validation under varying temperature

    Science.gov (United States)

    Lin, Y. Q.; Ren, W. X.; Fang, S. E.

    2011-11-01

    Although most vibration-based damage detection methods can acquire satisfactory verification on analytical or numerical structures, most of them may encounter problems when applied to real-world structures under varying environments. The damage detection methods that directly extract damage features from the periodically sampled dynamic time history response measurements are desirable but relevant research and field application verification are still lacking. In this second part of a two-part paper, the robustness and performance of the statistics-based damage index using the forward innovation model by stochastic subspace identification of a vibrating structure proposed in the first part have been investigated against two prestressed reinforced concrete (RC) beams tested in the laboratory and a full-scale RC arch bridge tested in the field under varying environments. Experimental verification is focused on temperature effects. It is demonstrated that the proposed statistics-based damage index is insensitive to temperature variations but sensitive to the structural deterioration or state alteration. This makes it possible to detect the structural damage for the real-scale structures experiencing ambient excitations and varying environmental conditions.

  13. Wettability, soil organic matter and structure-properties of typical chernozems under the forest and under the arable land

    Science.gov (United States)

    Bykova, Galina; Umarova, Aminat; Tyugai, Zemfira; Milanovskiy, Evgeny; Shein, Evgeny

    2017-04-01

    Intensive tillage affects the properties of soil: decrease in content of soil organic matter and in hydrophobicity of the soil's solid phase, the reduction of amount of water stable aggregates - all this leads to deterioration of the structure of the soil and affects the process of movement of moisture in the soil profile. One of the hypotheses of soil's structure formation ascribes the formation of water stable aggregates with the presence of hydrophobic organic substances on the surface of the soil's solid phase. The aim of this work is to study the effect of tillage on properties of typical chernozems (pachic Voronic Chernozems, Haplic Chernozems) (Russia, Kursk region), located under the forest and under the arable land. The determination of soil-water contact angle was performed by a Drop Shape Analyzer DSA100 (Krüss GmbH, Germany) by the static sessile drop method. For all samples the content of total and organic carbon by dry combustion in oxygen flow and the particle size distribution by the laser diffraction method on the device Analysette 22 comfort, FRITCH, Germany were determined. The estimation of aggregate composition was performed by dry sieving (AS 200, Retsch, Germany), the content of water stable aggregates was estimated by the Savvinov method. There was a positive correlation between the content of organic matter and soil's wettability in studied soils, a growth of contact angle with the increasing the content of organic matter. Under the forest the content of soil organic matter was changed from 6,41% on the surface up to 1,9% at the depth of 100 cm. In the Chernozem under the arable land the organic carbon content in arable horizon is almost two times less. The maximum of hydrophobicity (78.1o) was observed at the depth of 5 cm under the forest. In the profile under the arable land the contact angle value at the same depth was 50o. The results of the structure analysis has shown a decrease in the content of agronomically valuable and water

  14. STUDY THE PROBLEMS OF OPTIMIZING THE CAPITAL STRUCTURE OF THE COMPANY

    Directory of Open Access Journals (Sweden)

    Olga Gaydarzhyyska

    2016-11-01

    Full Text Available The aim of this work is to study the problem of optimizing the capital structure of the company. Optimization of capital structure is a necessary condition of adaptation the enterprises regardless of the branch of economy to which a company belongs, to changes in the economy in its development. Methods and criteria of optimisation of the capital structure of the enterprise. The method of determining the optimal capital structure of the enterprise according to the criteria of maximizing financial profitability. Technique. The study is based on the theoretical analysis of scientific works and practical activity of enterprises. Results. It is proved that in the process of optimizing the capital structure necessary to take into account the predictable result of economic activity of the enterprise, that is, financial result from usual activity before taxation. The study of problems of optimization of capital structure aimed at opening opportunities for the effective organization of business enterprises, providing conditions for disclosure for businesses achieving the goals of any order, and the creation of opportunities for enterprise maximum level of profit. The principle of optimization is to select the solution that best would take into account internal possibilities and external terms of activity of the enterprise. Optimization is the choice of a certain economic indicator that would allow to compare the effectiveness of any solutions. Also it is advisable to pay attention to the use of different types of loan capital to business enterprises, to know that helps to speed up circulation of funds and increase returns on invested capital, increase the efficiency of financial activities of a business entity. Value. Today, the economic activities of enterprises has a significant impact on the development of trade and economy. The achievement of dynamic growth of the basic indicators of work of enterprises of any sector of the economy, is the basic

  15. Multi-stage approach for structural damage detection problem using basis pursuit and particle swarm optimization

    Science.gov (United States)

    Gerist, Saleheh; Maheri, Mahmoud R.

    2016-12-01

    In order to solve structural damage detection problem, a multi-stage method using particle swarm optimization is presented. First, a new spars recovery method, named Basis Pursuit (BP), is utilized to preliminarily identify structural damage locations. The BP method solves a system of equations which relates the damage parameters to the structural modal responses using the sensitivity matrix. Then, the results of this stage are subsequently enhanced to the exact damage locations and extents using the PSO search engine. Finally, the search space is reduced by elimination of some low damage variables using micro search (MS) operator embedded in the PSO algorithm. To overcome the noise present in structural responses, a method known as Basis Pursuit De-Noising (BPDN) is also used. The efficiency of the proposed method is investigated by three numerical examples: a cantilever beam, a plane truss and a portal plane frame. The frequency response is used to detect damage in the examples. The simulation results demonstrate the accuracy and efficiency of the proposed method in detecting multiple damage cases and exhibit its robustness regarding noise and its advantages compared to other reported solution algorithms.

  16. Emergence of problem areas in the urban structure of post-socialist Zagreb

    Directory of Open Access Journals (Sweden)

    Slavuj Lana

    2009-01-01

    Full Text Available The period of economic transition has resulted in complex social, functional and morphological transformations which have left their mark in the urban structure of Zagreb. At the beginning of 2000' fundamental planning acts have been passed - Zagreb spatial plan and the City Master Plan - to serve as concrete strategies and guidelines in developing the city area. However, none of the regulatory rules and acts have been completely successful in managing the city development. Significant changes and problems the city is facing in the post-socialist era serve as a research framework and are discussed in this paper. The main goal is to register and explain crucial causes of these spatial transformations. Based on the research of cartographic sources and conducted fieldwork four representative types of problem areas of the city are recognized. According to their functional and morphological characteristics, they are: converted urban land areas, derelict areas, newly built areas and densified areas. Each of these four types of problem areas is individually analyzed in the context of possible negative consequences on the urban environment.

  17. A memory structure adapted simulated annealing algorithm for a green vehicle routing problem.

    Science.gov (United States)

    Küçükoğlu, İlker; Ene, Seval; Aksoy, Aslı; Öztürk, Nursel

    2015-03-01

    Currently, reduction of carbon dioxide (CO2) emissions and fuel consumption has become a critical environmental problem and has attracted the attention of both academia and the industrial sector. Government regulations and customer demands are making environmental responsibility an increasingly important factor in overall supply chain operations. Within these operations, transportation has the most hazardous effects on the environment, i.e., CO2 emissions, fuel consumption, noise and toxic effects on the ecosystem. This study aims to construct vehicle routes with time windows that minimize the total fuel consumption and CO2 emissions. The green vehicle routing problem with time windows (G-VRPTW) is formulated using a mixed integer linear programming model. A memory structure adapted simulated annealing (MSA-SA) meta-heuristic algorithm is constructed due to the high complexity of the proposed problem and long solution times for practical applications. The proposed models are integrated with a fuel consumption and CO2 emissions calculation algorithm that considers the vehicle technical specifications, vehicle load, and transportation distance in a green supply chain environment. The proposed models are validated using well-known instances with different numbers of customers. The computational results indicate that the MSA-SA heuristic is capable of obtaining good G-VRPTW solutions within a reasonable amount of time by providing reductions in fuel consumption and CO2 emissions.

  18. Structuring policy problems for plastics, the environment and human health: reflections from the UK

    Science.gov (United States)

    Shaxson, Louise

    2009-01-01

    How can we strengthen the science–policy interface for plastics, the environment and human health? In a complex policy area with multiple stakeholders, it is important to clarify the nature of the particular plastics-related issue before trying to understand how to reconcile the supply and demand for evidence in policy. This article proposes a simple problem typology to assess the fundamental characteristics of a policy issue and thus identify appropriate processes for science–policy interactions. This is illustrated with two case studies from one UK Government Department, showing how policy and science meet over the environmental problems of plastics waste in the marine environment and on land. A problem-structuring methodology helps us understand why some policy issues can be addressed through relatively linear flows of science from experts to policymakers but why others demand a more reflexive approach to brokering the knowledge between science and policy. Suggestions are given at the end of the article for practical actions that can be taken on both sides. PMID:19528061

  19. Wolves, dogs, rearing and reinforcement: complex interactions underlying species differences in training and problem-solving performance.

    Science.gov (United States)

    Frank, Harry

    2011-11-01

    Frank and Frank et al. (1982-1987) administered a series of age-graded training and problem-solving tasks to samples of Eastern timber wolf (C. lupus lycaon) and Alaskan Malamute (C. familiaris) pups to test Frank's (Zeitschrift für Tierpsychologie 53:389-399, 1980) model of the evolution of information processing under conditions of natural and artificial selection. Results confirmed the model's prediction that wolves should perform better than dogs on problem-solving tasks and that dogs should perform better than wolves on training tasks. Further data collected at the University of Connecticut in 1983 revealed a more complex and refined picture, indicating that species differences can be mediated by a number of factors influencing wolf performance, including socialization regimen (hand-rearing vs. mother-rearing), interactive effects of socialization on the efficacy of both rewards and punishments, and the flexibility to select learning strategies that experimenters might not anticipate.

  20. Prolonged hypogonadism in males following withdrawal from anabolic-androgenic steroids: an under-recognized problem.

    Science.gov (United States)

    Kanayama, Gen; Hudson, James I; DeLuca, James; Isaacs, Stephanie; Baggish, Aaron; Weiner, Rory; Bhasin, Shalender; Pope, Harrison G

    2015-05-01

    To assess the frequency and severity of hypogonadal symptoms in male long-term anabolic-androgenic steroid (AAS) misusers who have discontinued AAS use. Cross-sectional, naturalistic. Out-patient facility. Twenty-four male former long-term AAS users and 36 non-AAS-using weightlifters, recruited by advertisement in Massachusetts, USA. Five of the former users were currently receiving treatment with physiological testosterone replacement, leaving 19 untreated users for the numerical comparisons below. The Structured Clinical Interview for DSM-IV, questions regarding history of AAS use, physical examination, serum hormone determinations and the International Index of Erectile Function (IIEF). Compared with the 36 non-AAS-using weightlifters, the 19 untreated former AAS users displayed significantly smaller testicular volumes [estimated difference, 95% confidence interval (CI) = 2.3 (0.1, 4.5) ml; P = 0.042] and lower serum testosterone levels [estimated difference: 95% CI = 131 (25, 227) dl; P = 0.009], with five users showing testosterone levels below 200 ng/dl despite abstinence from AAS for 3-26 months. Untreated former users also displayed significantly lower scores on the IIEF sexual desire subscale [estimated difference: 95% CI = 2.4 (1.3, 3.4) points on a 10-point scale; P anabolic-androgenic steroid misusers, anabolic-androgenic steroid-withdrawal hypogonadism appears to be common, frequently prolonged and associated with substantial morbidity. © 2015 Society for the Study of Addiction.

  1. [D-cells of the gastroenteropancreatic system: development, structure, function and regeneration (history and current state of the problem)].

    Science.gov (United States)

    Ivanova, V F; Kostiukevich, S V

    2015-01-01

    The present review summarizes the literature data and the results of authors' own research on the development, structure, function and regeneration of D-endocrinocytes of gastroenteropancreatic (GEP) system. The history of the research of these cells is reviewed and its current state of the problem is discussed. The information on the difference of somatostatin-producing D-endocrinocytes from other types of endocrine cells of GAP system is presented, namely, the prevalence of these cells in all the organs of the digestive system (stomach, small and large intestine, pancreas) and other systems of the body, the peculiarities of their structure and regeneration in various species of vertebrate animals and humans in embryonic development, under conditions of normal functioning and in various types of pathology. On the basis of the data on the early differentiation of D-endocrinocytes and their secretion of hormones during embryonic development, structure, cytophysiology and relationships within the general endocrinocyte population, it is suggested that D-endocrinocytes play an important role in the morpho-functional state of GEP system.

  2. Seismodynamics of extended underground structures and soils: Statement of the problem and self-similar solutions

    Science.gov (United States)

    Georgievskii, D. V.; Israilov, M. Sh.

    2015-07-01

    In the problems of common vibrations of extended underground structures (pipelines and tunnels) and soil, an approach of the one-dimensional deformation of the medium is developed; this approach is based on the assumption that the soil deformation in the direction of seismic wave propagation coinciding with the pipeline axis is prevailing. The analytic solutions are obtained in the cases where the wave velocity in the soil is respectively less or greater than the wave velocity in the pipeline. The parameters influencing the pipeline fracture are revealed and methods for increasing the seismic stability of such structures are given. The possibility of the pipeline fatigue fracture is pointed out. The statements and solutions of parabolic problems modeling the physical phenomena in soils in the case of discontinuous velocity on the boundaries at the initial time are given. The notion of generalized vorticity diffusion is introduced and the cases of self-similarity existence are classified. A detailed analysis is performed for the non-Newtonian polynomial fluid, the medium close in properties to the rigidly ideally plastic body, and the viscoplastic Shvedov—Bingham body. In the case of physically linear medium, new self-similar solutions are obtained which describe the process of unsteady axially symmetric shear in spherical coordinates. The first approximation to the asymptotic solution of the problem of the vortex sheet diffusion is constructed in a medium with small polynomial nonlinearity. The solutions polynomially decreasing to zero as the self-similar variable increases are proposed in the class of two-constant fluids.

  3. Optimal Topology of Aircraft Rib and Spar Structures under Aeroelastic Loads

    Science.gov (United States)

    Stanford, Bret K.; Dunning, Peter D.

    2014-01-01

    Several topology optimization problems are conducted within the ribs and spars of a wing box. It is desired to locate the best position of lightening holes, truss/cross-bracing, etc. A variety of aeroelastic metrics are isolated for each of these problems: elastic wing compliance under trim loads and taxi loads, stress distribution, and crushing loads. Aileron effectiveness under a constant roll rate is considered, as are dynamic metrics: natural vibration frequency and flutter. This approach helps uncover the relationship between topology and aeroelasticity in subsonic transport wings, and can therefore aid in understanding the complex aircraft design process which must eventually consider all these metrics and load cases simultaneously.

  4. Novel stable structure of Li3PS4 predicted by evolutionary algorithm under high-pressure

    Directory of Open Access Journals (Sweden)

    S. Iikubo

    2018-01-01

    Full Text Available By combining theoretical predictions and in-situ X-ray diffraction under high pressure, we found a novel stable crystal structure of Li3PS4 under high pressures. At ambient pressure, Li3PS4 shows successive structural transitions from γ-type to β-type and from β-type to α type with increasing temperature, as is well established. In this study, an evolutionary algorithm successfully predicted the γ-type crystal structure at ambient pressure and further predicted a possible stable δ-type crystal structures under high pressure. The stability of the obtained structures is examined in terms of both static and dynamic stability by first-principles calculations. In situ X-ray diffraction using a synchrotron radiation revealed that the high-pressure phase is the predicted δ-Li3PS4 phase.

  5. An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions

    Science.gov (United States)

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

    2016-01-01

    Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack

  6. An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions.

    Science.gov (United States)

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

    2016-02-26

    Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack

  7. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    OpenAIRE

    Escaler, X; De La Torre, O; Farhat, M

    2015-01-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to thei r surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at t...

  8. Problem structuring in interactive decision-making processes : How interaction, problem perceptions and knowledge contribute to a joint formulation of a problem and solutions

    NARCIS (Netherlands)

    De Kruijf, J.

    2007-01-01

    Water management issues are often complex, unstructured problems. They are complex, because they are part of a natural and human system wich consists of many diverse, interdependent elements, e.g. upstream events influence the water system downstream, different interdependent goverment layers,

  9. Use of three-dimensional parameters in the analysis of crystal structures under compression

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci

    2007-01-01

    . For a complete understanding of structural changes, the behaviour of all coordination polyhedra plus the voids that separate them must be investigated. The structural voids in a framework are identified by a Voronoi tessellation. It can be performed e.g. on the anionic framework alone to find the centres...... of the coordination polyhedra of cations and the voids that separate them. Analysis of individual compressional characteristics of structural components gives clues for the strong and weak parts of structures under high pressures and paths for structural transformations. The expected behaviour of distortion...

  10. Electronic Structures of MgB{$_2$} under Uniaxial and Hydrostatic Compression

    OpenAIRE

    Kobayashi, K.; Yamamoto, K.

    2001-01-01

    Electronic and lattice properties of MgB{$_2$} under uniaxial and hydrostatic compression are calculated. Lattice properties are optimized automatically by using the first-principles molecular dynamics (FPMD) method. Features of the electronic band structures under uniaxial and hydrostatic compression are quite different each other.

  11. Is structural sensitivity a problem of oversimplified biological models? Insights from nested Dynamic Energy Budget models.

    Science.gov (United States)

    Aldebert, Clement; Kooi, Bob W; Nerini, David; Poggiale, Jean-Christophe

    2018-03-14

    Many current issues in ecology require predictions made by mathematical models, which are built on somewhat arbitrary choices. Their consequences are quantified by sensitivity analysis to quantify how changes in model parameters propagate into an uncertainty in model predictions. An extension called structural sensitivity analysis deals with changes in the mathematical description of complex processes like predation. Such processes are described at the population scale by a specific mathematical function taken among similar ones, a choice that can strongly drive model predictions. However, it has only been studied in simple theoretical models. Here, we ask whether structural sensitivity is a problem of oversimplified models. We found in predator-prey models describing chemostat experiments that these models are less structurally sensitive to the choice of a specific functional response if they include mass balance resource dynamics and individual maintenance. Neglecting these processes in an ecological model (for instance by using the well-known logistic growth equation) is not only an inappropriate description of the ecological system, but also a source of more uncertain predictions. Copyright © 2018. Published by Elsevier Ltd.

  12. Structural Evolution of Human Recombinant alfaB-Crystallin under UV Irradiation

    DEFF Research Database (Denmark)

    Sugiyama, Masaaki; Fujii, Noriko; Morimoto, Yukio

    2008-01-01

    External stresses cause certain proteins to lose their regular structure and aggregate. In order to clarify this abnormal aggregation process, a structural evolution of human recombinant aB-crystallin under UV irradiation was observed with in situ small-angle neutron scattering. The abnormal...

  13. Problematic Alcohol Use and Problem Gambling: Associations to Structural and Functional aspects of Social Ties in a Finnish Population Sample

    Directory of Open Access Journals (Sweden)

    Nordmyr Johanna

    2016-09-01

    Full Text Available AIMS – This study aims to explore associations between structural and functional aspects of social networks and relationships (here labelled social ties among individuals exhibiting problematic alcohol use and problem gambling, respectively.

  14. Community facilitation of problem structuring and decision making processes: Experiences from the EU LEADER+ programme

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui

    2009-01-01

    This paper reports on the work carried out supporting a rural community in Denmark under the LEADER+ programme. This is a programme that supports development in particularly vulnerable rural regions of the European countries members of EU. It supports creative and innovative projects that can...... contribute to long-term and sustainable development in these regions. The main tasks have been the organisation and facilitation of conferences and workshops to structure the problematic situation of identifying and designing innovative projects for the development of the community and to support decision...

  15. Evaluation of Lagrangian, Eulerian, and arbitrary Lagrangian-Eulerian methods for fluid-structure interaction problems in HCDA analysis

    International Nuclear Information System (INIS)

    Chang, Y.W.; Chu, H.Y.; Gvildys, J.; Wang, C.Y.

    1979-01-01

    The analysis of fluid-structure interaction involves the calculation of both fluid transient and structure dynamics. In the structural analysis, Lagrangian meshes have been used exclusively, whereas for the fluid transient, Lagrangian, Eulerian, and arbitrary Lagrangian-Eulerian (quasi-Eulerian) meshes have been used. This paper performs an evaluation on these three types of meshes. The emphasis is placed on the applicability of the method in analyzing fluid-structure interaction problems in HCDA analysis

  16. 3D non-linear time domain FEM–BEM approach to soil–structure interaction problems

    OpenAIRE

    Romero Ordóñez, Antonio; Galvín, Pedro; Domínguez Abascal, José

    2013-01-01

    Dynamic soil-structure interaction is concerned with the study of structures supported on flexible soils and subjected to dynamic actions. Methods combining the finite element method (FEM) and the boundary element method (BEM) are well suited to address dynamic soil-structure interaction problems. Hence, FEM-BEM models have been widely used. However, non-linear contact conditions and non-linear behaviour of the structures have not usually been considered in the analyses. This paper ...

  17. Design of a Dual-Mapping Learning Approach for Problem Solving and Knowledge Construction in Ill-Structured Domains

    Science.gov (United States)

    Wu, Bian; Wang, Minhong; Spector, J. Michael; Yang, Stephen J. H.

    2013-01-01

    Problem solving has been increasingly used as an important approach to learning especially in ill-structured domains. It is assumed that knowledge can be better consolidated and extended through problem-solving experience. However, many learners do not have the ability to separate general knowledge from specific cases, which inhibits successful…

  18. Analysis on complex structure stability under different bar angle with BIM technology

    Directory of Open Access Journals (Sweden)

    Wang Xiongjue

    2016-03-01

    Full Text Available Sun Valley, the landmark building of World Expo in Shanghai, which has free surface with single-layer reticulated shell structure, is a typical complex structure. CAD/CAM integrated information system to design is used for the complex structure; however, it is a very rigorous process to be used widely. The relevant technology of the Sun Valley is not open to the public at present, so we try to use BIM technology to model the Sun Valley, including architecture modelling and structure analysis. By analysis of the Sun Valley structure using this method, it is proved that the problems in modelling may be solved by writing some script codes in Rhino software and the stability of the model can also be analyzed. The new approach is viable and effective in combination with different softwares such as Rhino, Revit, and Midas in solution of the complex shaped surfaces’ structure for modelling and calculation.

  19. Graph theory approach to the eigenvalue problem of large space structures

    Science.gov (United States)

    Reddy, A. S. S. R.; Bainum, P. M.

    1981-01-01

    Graph theory is used to obtain numerical solutions to eigenvalue problems of large space structures (LSS) characterized by a state vector of large dimensions. The LSS are considered as large, flexible systems requiring both orientation and surface shape control. Graphic interpretation of the determinant of a matrix is employed to reduce a higher dimensional matrix into combinations of smaller dimensional sub-matrices. The reduction is implemented by means of a Boolean equivalent of the original matrices formulated to obtain smaller dimensional equivalents of the original numerical matrix. Computation time becomes less and more accurate solutions are possible. An example is provided in the form of a free-free square plate. Linearized system equations and numerical values of a stiffness matrix are presented, featuring a state vector with 16 components.

  20. Structure of Pareto Solutions of Generalized Polyhedral-Valued Vector Optimization Problems in Banach Spaces

    Directory of Open Access Journals (Sweden)

    Qinghai He

    2013-01-01

    Full Text Available In general Banach spaces, we consider a vector optimization problem (SVOP in which the objective is a set-valued mapping whose graph is the union of finitely many polyhedra or the union of finitely many generalized polyhedra. Dropping the compactness assumption, we establish some results on structure of the weak Pareto solution set, Pareto solution set, weak Pareto optimal value set, and Pareto optimal value set of (SVOP and on connectedness of Pareto solution set and Pareto optimal value set of (SVOP. In particular, we improved and generalize, Arrow, Barankin, and Blackwell’s classical results in Euclidean spaces and Zheng and Yang’s results in general Banach spaces.

  1. An Objective Structured Clinical Examination to Assess Problem-Based Learning

    Science.gov (United States)

    O'Connell, Mary Beth; Garwood, Candice L.; Lehr, Victoria Tutag; Abdallah, Karina

    2012-01-01

    Objectives. To compare pharmacy students’ performance on an objective structured clinical examination (OSCE) to their performance on a written examination for the assessment of problem-based learning (PBL); and to determine students’ and faculty members’ perceptions of OSCEs for PBL evaluations. Design. Four OSCEs were added to the written examination to assess 4 PBL cases in a third-year pharmacotherapy course. OSCE scores were compared to written examination scores. Faculty members evaluated student performance. Assessment. OSCE performance did not correlate with the written-examination scores. Most students (≥ 75%) agreed that OSCEs reflected their learning from PBL and measured knowledge, communication, and clinical skills. A majority of faculty members (≥75%) agreed that OSCEs should be part of PBL assessment. Conclusions. Addition of an OSCE to written examinations was valued and provided a more comprehensive assessment of the PBL experience. PMID:22544961

  2. School Attendance Problems and Youth Psychopathology: Structural Cross-Lagged Regression Models in Three Longitudinal Datasets

    Science.gov (United States)

    Wood, Jeffrey J.; Lynne, Sarah D.; Langer, David A.; Wood, Patricia A.; Clark, Shaunna L.; Eddy, J. Mark; Ialongo, Nicholas

    2011-01-01

    This study tests a model of reciprocal influences between absenteeism and youth psychopathology using three longitudinal datasets (Ns= 20745, 2311, and 671). Participants in 1st through 12th grades were interviewed annually or bi-annually. Measures of psychopathology include self-, parent-, and teacher-report questionnaires. Structural cross-lagged regression models were tested. In a nationally representative dataset (Add Health), middle school students with relatively greater absenteeism at study year 1 tended towards increased depression and conduct problems in study year 2, over and above the effects of autoregressive associations and demographic covariates. The opposite direction of effects was found for both middle and high school students. Analyses with two regionally representative datasets were also partially supportive. Longitudinal links were more evident in adolescence than in childhood. PMID:22188462

  3. Major health problems and their economic impact on beef cattle under two different feedlot systems in Brazil

    Directory of Open Access Journals (Sweden)

    Pedro Malafaia

    Full Text Available Abstract: This study aimed to describe the diagnosis of health problems and to evaluate the cost of their treatment for cattle raised in feedlots to be slaughtered or to be sold as sires for cow-calf systems. Bovine respiratory disease and digestive disorders were the main problems diagnosed in the feedlot for slaughter; the cost for treatment was high, accounting for 9.7 to 20.9 kg of live weight (LW or the equivalent of 7 to 15% of total LW gained over the days on feed. Due to the high intake of starch-rich concentrate, rumen and fecal pH was lower, whilst rumen osmolarity and blood lactate were higher in cattle fed for slaughter. Cattle affected by digestive disorders spent on average four additional days in the feedlot. Diseases and cost of treatments were associated with lower average daily gain and considerable economic losses. Health problems commonly observed in the feedlots for slaughter were not observed in the feedlots for males to be sold as sires. The most likely reason for this observation was the more careful nutrition and prophylactic health management in sire production systems, which produce animals of much higher selling price. Results from this study suggest that health problems found in feedlots for slaughter may not only reduce animal productivity and profitability, but also the welfare of the animals. The systemic understaffing of livestock cattle workers and veterinarians in large feedlots in Brazil results in under reporting of diseases and lack to understand epidemiological context and disease prevention.

  4. Covariance Structure Model Fit Testing under Missing Data: An Application of the Supplemented EM Algorithm

    Science.gov (United States)

    Cai, Li; Lee, Taehun

    2009-01-01

    We apply the Supplemented EM algorithm (Meng & Rubin, 1991) to address a chronic problem with the "two-stage" fitting of covariance structure models in the presence of ignorable missing data: the lack of an asymptotically chi-square distributed goodness-of-fit statistic. We show that the Supplemented EM algorithm provides a…

  5. Legislative Provisions Underlying Trade Unions' Right to Define Their Organizational Structure

    Science.gov (United States)

    Korobchenko, Victoria V.; Penov, Yury V.; Safonov, Valery A.

    2016-01-01

    The article contains a comparative analysis of constitutional and other legislative provisions that ensure a trade union's right to define its own administrative structure in European states. The aim of the study is to reveal the management's problems of European trade unions, declarative and empirical mass-character legislative provisions, which…

  6. Algorithm for Solution of Direct Kinematic Problem of Multi-sectional Manipulator with Parallel Structure

    Directory of Open Access Journals (Sweden)

    A. L. Lapikov

    2014-01-01

    Full Text Available The article is aimed at creating techniques to study multi-sectional manipulators with parallel structure. To solve this task the analysis in the field concerned was carried out to reveal both advantages and drawbacks of such executive mechanisms and main problems to be encountered in the course of research. The work shows that it is inefficient to create complete mathematical models of multisectional manipulators, which in the context of solving a direct kinematic problem are to derive a functional dependence of location and orientation of the end effector on all the generalized coordinates of the mechanism. The structure of multisectional manipulators was considered, where the sections are platform manipulators of parallel kinematics with six degrees of freedom. The paper offers an algorithm to define location and orientation of the end effector of the manipulator by means of iterative solution of analytical equation of the moving platform plane for each section. The equation for the unknown plane is derived using three points, which are attachment points of the moving platform joints. To define the values of joint coordinates a system of nine non-linear equations is completed. It is necessary to mention that for completion of the equation system are used the equations with the same type of non-linearity. The physical sense of all nine equations of the system is Euclidean distance between the points of the manipulator. The result of algorithm execution is a matrix of homogenous transformation for each section. The correlations describing transformations between adjoining sections of the manipulator are given. An example of the mechanism consisting of three sections is examined. The comparison of theoretical calculations with results obtained on a 3D-prototype is made. The next step of the work is to conduct research activities both in the field of dynamics of platform parallel kinematics manipulators with six degrees of freedom and in the

  7. Structural capacity assessment of a generic pre-stressed concrete containment structure under aircraft impact

    International Nuclear Information System (INIS)

    Iliev, Alexander

    2013-01-01

    The studied containment expressed adequate capacity to resist impact loads in the upper range of the studied diapason. The aircraft impact capacity of the containment for impact in the upper part of the cylindrical shell is about 25‐30% higher than the capacity for impact in the middle part of the cylindrical shell. The obtained fragility curves reefed to MoA can be then used for various additional calculations in the safety assessment of nuclear facilities under aircraft impact

  8. Problems of natural lighting for deepened buildings and underground premises under screen effect of high-rise construction

    Science.gov (United States)

    Larionova, Kira; Stetsky, Sergey

    2018-03-01

    The main rationale and objective of the submitted research work is to create a quality lighting environment in the premises of deepened buildings and below-ground structures under screen effect of high-rise construction (high-rise buildings). It is noted, that in modern megapolises, a deficiency of vacant urban territories leads to the increased density of urban development with increased amount of high-rise construction and tendency to increase efficiency in the use of underground space. The natural lighting of premises in underground buildings and structures is the most efficient way, but it can be implemented only under use of roof lighting system in the form of roof monitors or skylights. In this case the levels of indoor natural lighting will be affected with serious screening effect of high-rise buildings in surrounding development. Such an situation is not regulated, or even considered by the contemporary building Codes and Regulations on natural lighting of interiors. The authors offered a new formula for a daylight factor calculation with roof lighting system in the described cases. The results of theoretical calculations and experimental studies showed very similar values. This proved the truth of the offered formula and elaborated method of calculation on the basis of an offered hypothesis. It prooves, that it is possible to use some factor and guide points in the daylight factors design under system of side natural lighting in the same design for a system of roof lighting.

  9. DSM-5 Posttraumatic Stress Disorder Symptom Structure in Disaster-Exposed Adolescents: Stability across Gender and Relation to Behavioral Problems.

    Science.gov (United States)

    Cao, Xing; Wang, Li; Cao, Chengqi; Zhang, Jianxin; Elhai, Jon D

    2017-05-01

    Given the significant modifications to posttraumatic stress disorder (PTSD) symptom criteria from DSM-IV to DSM-5, a better understanding of the dimensionality underlying DSM-5 PTSD symptoms among adolescents is needed. However, to date, whether gender moderates the latent structure of DSM-5 PTSD symptoms in youth remains unclear. Meanwhile, little is known about how distinct PTSD dimensions relate to adolescent behavioral problems. The aim of this study was to fill these gaps. A sample of 1184 disaster-exposed Chinese adolescents (53.8 % girls) with age ranging from 13 to 17 years (M = 14.3, SD = 0.8) completed the PTSD Checklist for DSM-5, and the Withdrawn, Aggressive Behavior, and Delinquent Behavior subscales of the Youth Self-Report. Confirmatory factor analyses revealed that the seven-factor hybrid PTSD model provided the best fit to the data for both girls and boys. Measurement equivalence of this model held across gender, although girls had higher mean scores than boys on some factors. Differential patterns of associations emerged between PTSD dimensions and behavioral problems, with anhedonia symptoms most strongly relating to social withdrawal, and externalizing behavior symptoms most strongly relating to aggression and delinquency. These findings further support the gender invariance and external criterion validity of the newly refined hybrid model that best represents DSM-5 PTSD symptom structure in youth, and carry implications for accurate assessment, diagnosis, and gender comparison of DSM-5 PTSD symptomatology, and potential symptom targets for PTSD intervention among adolescent disaster survivors.

  10. A Direct Kinematics Problem Solution for the Three-degree-of-freedom Parallel Structure Manipulator Based on Crank Mechanism

    Directory of Open Access Journals (Sweden)

    V. N. Paschenko

    2015-01-01

    Full Text Available The paper describes a mechanism representing a kind of mechanisms of parallel kinematics with three degrees of freedom based on the crank mechanism. This mechanism consists of two platforms, namely: the lower fixed and the upper movable. The upper platform is connected to the lower one by six movable elements, three of which are rods attached to the bases by means of spherical joints, and another three have a crank structure.The paper shows an approach to the solution of a direct task of kinematics based on mathematical modeling. The inverse problem of kinematics is formulated as follows: at specified angles of rotation drive (the values of generalized coordinates to determine the position of the top mobile platform.To solve this problem has been used a mathematical model describing the proposed system. On the basis of the constructed model were made the necessary calculations that allowed us using the values of crank angles connected with the engines to determine the position of the platform in space. To solve the problem we used the method of virtual points to reduce the number of equations and unknowns, which determine the position of the upper platform in space, at a crucial system from eighteen to nine, thus simplifying the solution.To check the solution correctness was carried out numerical experiment. Each generalized coordinate took on values in the range from -30 ° to 30 °; for them a direct positional problem was solved, and its result was inserted, as initial data, in the previous solved and proven inverse problem on the position of the platform under study.The paper presents comparative results of measurements with the calculated values of the generalized coordinates and draws the appropriate conclusions, that this model is in good compliance with the results observed in practice. One of the distinctive features of the proposed approach is that rotation angles of engines are used as the generalized coordinates. This allowed us

  11. Influence of the membrane structure plan shape on the displacements under point load

    Directory of Open Access Journals (Sweden)

    Milošević Vuk S.

    2016-01-01

    Full Text Available Deformations of membrane structures under external loads are much more prominent compared to other structures and structural materials. External area loads cause large displacements and redistribution of internal tension forces. Point loads have a less significant impact on changes of internal forces, but a more significant role in creation of local deformations. Previous researches have shown the influence of position and intensity of point loads on the deformations of membrane structures. The aim of this research is to investigate the influence of plan shape of the membrane structure on the displacements under point load. The influence of rhombic shaped plans with different diagonal lengths and ratios is explored. The research is conducted on numerical models in the specialized software Sofistik. Models are loaded with point loads in the point where diagonals intersect and the results are compared.

  12. The Crystal Structure and Behavior of Fenamic Acid-Acridine Complex Under High Pressure.

    Science.gov (United States)

    Jerzykiewicz, Lucjan; Sroka, Adam; Majerz, Irena

    2016-12-01

    The crystal structure of fenamic acid-acridine complex is determined by X-ray diffraction. The strong OHN hydrogen bond linking the complex components and other interactions responsible for packing of the molecules into a crystal are investigated within the Quantum Theory of Atom in Molecule theory. The crystal structure is compared with the structure optimized at B3LYP/6-311++G** level and with the theoretical structures optimized under systematically changed pressure. Analysis of the lattice constants, hydrogen bond lengths, and angles of the inter- and intramolecular hydrogen bond under compression is performed. The structural transformation observed at 5 GPa is connected with a change in the intermolecular OHN hydrogen bond. The proton shifts to acceptor and a new interaction in the crystal appears. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  13. Similarity between community structures of different online social networks and its impact on underlying community detection

    Science.gov (United States)

    Fan, W.; Yeung, K. H.

    2015-03-01

    As social networking services are popular, many people may register in more than one online social network. In this paper we study a set of users who have accounts of three online social networks: namely Foursquare, Facebook and Twitter. Community structure of this set of users may be reflected in these three online social networks. Therefore, high correlation between these reflections and the underlying community structure may be observed. In this work, community structures are detected in all three online social networks. Also, we investigate the similarity level of community structures across different networks. It is found that they show strong correlation with each other. The similarity between different networks may be helpful to find a community structure close to the underlying one. To verify this, we propose a method to increase the weights of some connections in networks. With this method, new networks are generated to assist community detection. By doing this, value of modularity can be improved and the new community structure match network's natural structure better. In this paper we also show that the detected community structures of online social networks are correlated with users' locations which are identified on Foursquare. This information may also be useful for underlying community detection.

  14. Distributed primal–dual interior-point methods for solving tree-structured coupled convex problems using message-passing

    DEFF Research Database (Denmark)

    Khoshfetrat Pakazad, Sina; Hansson, Anders; Andersen, Martin S.

    2017-01-01

    In this paper, we propose a distributed algorithm for solving coupled problems with chordal sparsity or an inherent tree structure which relies on primal–dual interior-point methods. We achieve this by distributing the computations at each iteration, using message-passing. In comparison to existing...... distributed algorithms for solving such problems, this algorithm requires far fewer iterations to converge to a solution with high accuracy. Furthermore, it is possible to compute an upper-bound for the number of required iterations which, unlike existing methods, only depends on the coupling structure...... in the problem. We illustrate the performance of our proposed method using a set of numerical examples....

  15. Environmental problem-solving and land-use management: A proposed structure for Australia

    Science.gov (United States)

    Conacher, Arthur

    1980-09-01

    A three-tiered structure of land-use and environmental management is here proposed for Australia. The structure is based on the idea that “environment” means the environment of people, and that “environmental problems” arise when a change in the interaction between people and their environment leads to conflicts about the use of land and resources. The heterogeneity of society means that a range of human aspirations and value systems must be satisfied by environmental managers. Existing methods of environmental management fail to achieve these objectives, due to inadequate perception of environmental problems by decision-makers, and the inability of currently available impact assessment techniques to resolve human conflicts associated with the use of land and resources. The main work of planning and managing land use and the environment would be carried out by regional authorities, supported by federal and state policy. Examples are given of moves towards regional administration in England and Wales, Western Australia, Australia and New Zealand. Community participation in the decision-making process is essential and can be achieved by electoral representation to the authoritative bodies and through procedures that ensure informed public comment on planning proposals.

  16. Matching experimental and three dimensional numerical models for structural vibration problems with uncertainties

    Science.gov (United States)

    Langer, P.; Sepahvand, K.; Guist, C.; Bär, J.; Peplow, A.; Marburg, S.

    2018-03-01

    The simulation model which examines the dynamic behavior of real structures needs to address the impact of uncertainty in both geometry and material parameters. This article investigates three-dimensional finite element models for structural dynamics problems with respect to both model and parameter uncertainties. The parameter uncertainties are determined via laboratory measurements on several beam-like samples. The parameters are then considered as random variables to the finite element model for exploring the uncertainty effects on the quality of the model outputs, i.e. natural frequencies. The accuracy of the output predictions from the model is compared with the experimental results. To this end, the non-contact experimental modal analysis is conducted to identify the natural frequency of the samples. The results show a good agreement compared with experimental data. Furthermore, it is demonstrated that geometrical uncertainties have more influence on the natural frequencies compared to material parameters and material uncertainties are about two times higher than geometrical uncertainties. This gives valuable insights for improving the finite element model due to various parameter ranges required in a modeling process involving uncertainty.

  17. Novel models and algorithms of load balancing for variable-structured collaborative simulation under HLA/RTI

    Science.gov (United States)

    Yue, Yingchao; Fan, Wenhui; Xiao, Tianyuan; Ma, Cheng

    2013-07-01

    High level architecture(HLA) is the open standard in the collaborative simulation field. Scholars have been paying close attention to theoretical research on and engineering applications of collaborative simulation based on HLA/RTI, which extends HLA in various aspects like functionality and efficiency. However, related study on the load balancing problem of HLA collaborative simulation is insufficient. Without load balancing, collaborative simulation under HLA/RTI may encounter performance reduction or even fatal errors. In this paper, load balancing is further divided into static problems and dynamic problems. A multi-objective model is established and the randomness of model parameters is taken into consideration for static load balancing, which makes the model more credible. The Monte Carlo based optimization algorithm(MCOA) is excogitated to gain static load balance. For dynamic load balancing, a new type of dynamic load balancing problem is put forward with regards to the variable-structured collaborative simulation under HLA/RTI. In order to minimize the influence against the running collaborative simulation, the ordinal optimization based algorithm(OOA) is devised to shorten the optimization time. Furthermore, the two algorithms are adopted in simulation experiments of different scenarios, which demonstrate their effectiveness and efficiency. An engineering experiment about collaborative simulation under HLA/RTI of high speed electricity multiple units(EMU) is also conducted to indentify credibility of the proposed models and supportive utility of MCOA and OOA to practical engineering systems. The proposed research ensures compatibility of traditional HLA, enhances the ability for assigning simulation loads onto computing units both statically and dynamically, improves the performance of collaborative simulation system and makes full use of the hardware resources.

  18. Effects of structural and dynamic family characteristics on the development of depressive and aggressive problems during adolescence. The TRAILS study.

    Science.gov (United States)

    Sijtsema, J J; Oldehinkel, A J; Veenstra, R; Verhulst, F C; Ormel, J

    2014-06-01

    Both structural (i.e., SES, familial psychopathology, family composition) and dynamic (i.e., parental warmth and rejection) family characteristics have been associated with aggressive and depressive problem development. However, it is unclear to what extent (changes in) dynamic family characteristics have an independent effect on problem development while accounting for stable family characteristics and comorbid problem development. This issue was addressed by studying problem development in a large community sample (N = 2,230; age 10-20) of adolescents using Linear Mixed models. Paternal and maternal warmth and rejection were assessed via the Egna Minnen Beträffande Uppfostran for Children (EMBU-C). Aggressive and depressive problems were assessed via subscales of the Youth/Adult Self-Report. Results showed that dynamic family characteristics independently affected the development of aggressive problems. Moreover, maternal rejection in preadolescence and increases in paternal rejection were associated with aggressive problems, whereas decreases in maternal rejection were associated with decreases in depressive problems over time. Paternal and maternal warmth in preadolescence was associated with fewer depressive problems during adolescence. Moreover, increases in paternal warmth were associated with fewer depressive problems over time. Aggressive problems were a stable predictor of depressive problems over time. Finally, those who increased in depressive problems became more aggressive during adolescence, whereas those who decreased in depressive problems became also less aggressive. Besides the effect of comorbid problems, problem development is to a large extent due to dynamic family characteristics, and in particular to changes in parental rejection, which leaves much room for parenting-based interventions.

  19. Experimental Study on Temperature Behavior of SC Structures under Pure Bending

    International Nuclear Information System (INIS)

    Ham, K. W.; Lee, K. J.; Park, D. S.; Jeon, J. H.

    2006-01-01

    SC(Steel plate Concrete) module method uses steel plate instead of reinforcing bar and mold in existing RC structure. Steel plate modules are fabricated in advance, installed and poured with concrete in construction field, so construction period is remarkably shortened by SC module technique. In case of existence of temperature gap between internal and external structure surface such as spent fuel storage pool, thermal stress is taken place and as a result of it, structural strength is deteriorated. In this study, we designed three test specimens and several tests with or without temperature heating were conducted to evaluate temperature behavior of SC structures under pure bending loading condition

  20. Cognitive Structures of Good and Poor Novice Problem Solvers in Physics

    NARCIS (Netherlands)

    de Jong, Anthonius J.M.; Ferguson-Hessler, Monica G.M.

    1986-01-01

    The way knowledge is organized in memory is generally expected to relate to the degree of success in problem solving. In the present study, we investigated whether good novice problem solvers have their knowledge arranged around problem types to a greater extent than poor problem solvers have. In

  1. Non-stationary random vibration analysis of structures under multiple correlated normal random excitations

    Science.gov (United States)

    Li, Yanbin; Mulani, Sameer B.; Kapania, Rakesh K.; Fei, Qingguo; Wu, Shaoqing

    2017-07-01

    An algorithm that integrates Karhunen-Loeve expansion (KLE) and the finite element method (FEM) is proposed to perform non-stationary random vibration analysis of structures under excitations, represented by multiple random processes that are correlated in both time and spatial domains. In KLE, the auto-covariance functions of random excitations are discretized using orthogonal basis functions. The KLE for multiple correlated random excitations relies on expansions in terms of correlated sets of random variables reflecting the cross-covariance of the random processes. During the response calculations, the eigenfunctions of KLE used to represent excitations are applied as forcing functions to the structure. The proposed algorithm is applied to a 2DOF system, a 2D cantilever beam and a 3D aircraft wing under both stationary and non-stationary correlated random excitations. Two methods are adopted to obtain the structural responses: a) the modal method and b) the direct method. Both the methods provide the statistics of the dynamic response with sufficient accuracy. The structural responses under the same type of correlated random excitations are bounded by the response obtained by perfectly correlated and uncorrelated random excitations. The structural response increases with a decrease in the correlation length and with an increase in the correlation magnitude. The proposed methodology can be applied for the analysis of any complex structure under any type of random excitation.

  2. Key Problems in Organizing and Structuring University Research in Vietnam: The Lack of an Effective Research "Behaviour Formalization" System

    Science.gov (United States)

    Nguyen, Huong Thi Lan; Meek, Vincent Lynn

    2016-01-01

    Structure and organization seems to be at the root of many of the questions raised about institutional behaviour; however, with respect to research on university capacity building, few studies have examined research organizational problems, particularly in developing countries. This study investigates academic reactions to the structure and…

  3. Crack formation of steel reinforced concrete structure under stress in construction period

    Directory of Open Access Journals (Sweden)

    Hua Zhu

    2016-03-01

    Full Text Available To obtain deformation rules of steel reinforced concrete structure under stress, this study explored the crack formation in construction period. A novel structure system – steel reinforced concrete structure with shear wall and truss at the bottom was analyzed using on-the-spot test in combination with theoretical simulation analysis with SAP2000 software. It was found that, factors influencing crack formation of steel reinforced concrete structure in construction period included construction load, creep of concrete, shrinkage of concrete, displacement of bond of section steel and concrete as well as leveling. In the construction period, the simulated results and the measured results were highly fitted under the influence of time-variant characteristics such as compressive strength, elasticity modulus, creep and shrinkage. Through processing and analyzing the measured data, we obtained the development rules of crack formation of steel reinforced concrete structure with different strength grades as well as deformation rules of time-varying structure system in construction period, figured out the reason for the difference between the simulated results and the measured results, analyzed the deformation of structural components under stress in construction period and proposed some suggestions. This work is beneficial to ensure safe and high-efficient operation of construction

  4. A Heuristic Algorithm for Constrained Multi-Source Location Problem with Closest Distance under Gauge: The Variational Inequality Approach

    Directory of Open Access Journals (Sweden)

    Jian-Lin Jiang

    2013-01-01

    Full Text Available This paper considers the locations of multiple facilities in the space , with the aim of minimizing the sum of weighted distances between facilities and regional customers, where the proximity between a facility and a regional customer is evaluated by the closest distance. Due to the fact that facilities are usually allowed to be sited in certain restricted areas, some locational constraints are imposed to the facilities of our problem. In addition, since the symmetry of distances is sometimes violated in practical situations, the gauge is employed in this paper instead of the frequently used norms for measuring both the symmetric and asymmetric distances. In the spirit of the Cooper algorithm (Cooper, 1964, a new location-allocation heuristic algorithm is proposed to solve this problem. In the location phase, the single-source subproblem with regional demands is reformulated into an equivalent linear variational inequality (LVI, and then, a projection-contraction (PC method is adopted to find the optimal locations of facilities, whereas in the allocation phase, the regional customers are allocated to facilities according to the nearest center reclassification (NCR. The convergence of the proposed algorithm is proved under mild assumptions. Some preliminary numerical results are reported to show the effectiveness of the new algorithm.

  5. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    International Nuclear Information System (INIS)

    Escaler, X; De La Torre, O; Farhat, M

    2015-01-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed. (paper)

  6. Review of parameters influencing the structural response of a submerged body under cavitation conditions

    Science.gov (United States)

    Escaler, X.; De La Torre, O.; Farhat, M.

    2015-12-01

    Submerged structures that operate under extreme flows are prone to suffer large scale cavitation attached to their surfaces. Under such conditions the added mass effects differ from the expected ones in pure liquids. Moreover, the existence of small gaps between the structure and surrounding bodies filled with fluid also influence the dynamic response. A series of experiments and numerical simulations have been carried out with a truncated NACA0009 hydrofoil mounted as a cantilever beam at the LMH-EPFL cavitation tunnel. The three first modes of vibration have been determined and analysed under various hydrodynamic conditions ranging from air and still water to partial cavitation and supercavitation. A remote nonintrusive excitation system with piezoelectric patches has been used for the experiments. The effects of the cavity properties and the lateral gap size on the natural frequencies and mode shapes have been determined. As a result, the significance of several parameters in the design of such structures is discussed.

  7. On Newton-Raphson formulation and algorithm for displacement based structural dynamics problem with quadratic damping nonlinearity

    Directory of Open Access Journals (Sweden)

    Koh Kim Jie

    2017-01-01

    Full Text Available Quadratic damping nonlinearity is challenging for displacement based structural dynamics problem as the problem is nonlinear in time derivative of the primitive variable. For such nonlinearity, the formulation of tangent stiffness matrix is not lucid in the literature. Consequently, ambiguity related to kinematics update arises when implementing the time integration-iterative algorithm. In present work, an Euler-Bernoulli beam vibration problem with quadratic damping nonlinearity is addressed as the main source of quadratic damping nonlinearity arises from drag force estimation, which is generally valid only for slender structures. Employing Newton-Raphson formulation, tangent stiffness components associated with quadratic damping nonlinearity requires velocity input for evaluation purpose. For this reason, two mathematically equivalent algorithm structures with different kinematics arrangement are tested. Both algorithm structures result in the same accuracy and convergence characteristic of solution.

  8. Development of a coupled lattice Boltzmann and finite element method for fluid-structure interaction problems

    International Nuclear Information System (INIS)

    Jo, Jong Chull; Roh, Kyung Wan; Jhung, Myung Jo

    2006-12-01

    During this work period, a preliminary research has been conducted in the three different and related areas as stated in the proposal: literature survey, preliminary feasibility study of LBM and FEM coupling for FSI problems, and benchmark problems. As far as the literature review was concerned, approximately one hundred articles were found for the LBM techniques and critical review has been performed. The reviewed articles were classified into several topics that are useful for a subsequent development of the proposed computer program. Those topics included immiscible multicomponent flows, flow with energy transport, coupled multi-physics applications, application of the boundary conditions, irregular lattices, and turbulence. Furthermore, some fundamental review of the LBM was also included in this report. Secondly, a description of the LBM and FEM coupling program, which has been developed so far, was described here along with some demonstration examples. The preliminary study showed a great potential of the proposed technique for FSI application. A sample computer program list is also attached as Appendix A. As a future benchmark study, a set of test cases were proposed so that experimental data would be obtained in the next phase of the study. These data would be beneficial to understand the fundamental physics of the FSI nature under different basic conditions, and also provide benchmark results against which the developed program at a later stage could be validated. Finally, the future research direction as the extension of the present work is provided with emphasis on its goal, as well as merits and benefits resulting from the proposed research for the regulatory evaluation activities of KINS and the associated technical activities of industries such as design, manufacturing, fabrication, operation and maintenance

  9. Review. Supporting problem structuring with computer-based tools in participatory forest planning

    Energy Technology Data Exchange (ETDEWEB)

    Hujala, T.; Khadka, C.; Wolfslehner, B.; Vacik, H.

    2013-09-01

    Aim of study: This review presents the state-of-art of using computerized techniques for problem structuring (PS) in participatory forest planning. Frequency and modes of using different computerized tool types and their contribution for planning processes as well as critical observations are described, followed by recommendations on how to better integrate PS with the use of forest decision support systems. Area of study: The reviewed research cases are from Asia, Europe, North-America, Africa and Australia. Material and methods: Via Scopus search and screening of abstracts, 32 research articles from years 2002-2011 were selected for review. Explicit and implicit evidence of using computerized tools for PS was recorded and assessed with content-driven qualitative analysis. Main results: GIS and forest-specific simulation tools were the most prevalent software types whereas cognitive modelling software and spreadsheet and calculation tools were less frequently used, followed by multi-criteria and interactive tools. The typical use type was to provide outputs of simulation–optimization or spatial analysis to negotiation situations or to compile summaries or illustrations afterwards; using software during group negotiation to foster interaction was observed only in a few cases. Research highlights: Expertise in both decision support systems and group learning is needed to better integrate PS and computerized decision analysis. From the knowledge management perspective, it is recommended to consider how the results of PS —e.g. conceptual models— could be stored into a problem perception database, and how PS and decision making could be streamlined by retrievals from such systems. (Author)

  10. Thermomechanics of Inelastic Thin-Walled Structural Members with Piezoelectric Sensors and Actuators Under Harmonic Loading (Review)

    Science.gov (United States)

    Karnaukhov, V. G.; Kirichok, I. F.; Kozlov, V. I.

    2017-01-01

    Models, combined numerical-analytical methods, and results related to study of the forced resonance vibrations and self-heating of thin-walled inelastic structural members with piezoelectric sensors and actuators under monoharmonic mechanical and electric loading are presented. The thermomechanical behavior of passive and piezoactive materials is described using the concept of complex characteristics that are assumed to depend on temperature and invariants of the strain tensor. The classical and refined thermomechanical theories are used to model the vibrations and self-heating of thin-walled structural members with sensors and actuators. Nonlinear coupled thermoelastic problems for thin-walled structural members are solved by iteration and numerical methods. The thermal failure of structural members is considered. Methods for determining the critical electrical and mechanical monoharmonic loads and methods of postcritical analysis are described. The effect of various factors on the effectiveness of active damping of the resonance vibrations of inelastic thin-walled structural members by piezoelectric sensors and actuators is studied

  11. Theoretical analysis, infrared and structural investigations of energy dissipation in metals under cyclic loading

    International Nuclear Information System (INIS)

    Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.

    2007-01-01

    The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data

  12. Structural changes and degradation of Red Latosols under different management systems for 20 years

    Directory of Open Access Journals (Sweden)

    João Tavares Filho

    2014-08-01

    Full Text Available Soils are the foundation of terrestrial ecosystems and their role in food production is fundamental, although physical degradation has been observed in recent years, caused by different cultural practices that modify structures and consequently the functioning of soils. The objective of this study was to evaluate possible structural changes and degradation in an Oxisol under different managements for 20 years: no-tillage cultivation with and without crop rotation, perennial crop and conventional tillage, plus a forested area (reference. Initially, the crop profile was described and subsequently, 10 samples per management system and forest soil were collected to quantify soil organic matter, flocculation degree, bulk density, and macroporosity. The results indicated structural changes down to a soil depth of 50 cm, with predominance of structural units ∆μ (intermediate compaction level under perennial crop and no-tillage crop rotation, and of structural units ∆ (compacted under conventional tillage and no-tillage. The soil was increasingly degraded in the increasing order: forest => no-tillage crop rotation => perennial crop => no-tillage without crop rotation => conventional tillage. In all managements, the values of organic matter and macroporosity were always below and bulk density always above those of the reference area (forest and, under no-tillage crop rotation and perennial crop, the flocculation degree was proportionally equal to that of the reference area.

  13. Multi-stage identification scheme for detecting damage in structures under ambient excitations

    International Nuclear Information System (INIS)

    Bao, Chunxiao; Li, Zhong-Xian; Hao, Hong

    2013-01-01

    Structural damage identification methods are critical to the successful application of structural health monitoring (SHM) systems to civil engineering structures. The dynamic response of civil engineering structures is usually characterized by high nonlinearity and non-stationarity. Accordingly, an improved Hilbert–Huang transform (HHT) method which is adaptive, output-only and applicable to system identification of in-service structures under ambient excitations is developed in this study. Based on this method, a multi-stage damage detection scheme including the detection of damage occurrence, damage existence, damage location and the estimation of damage severity is developed. In this scheme, the improved HHT method is used to analyse the structural acceleration response, the obtained instantaneous frequency detects the instant of damage occurrence, the instantaneous phase is sensitive to minor damage and provides reliable damage indication, and the damage indicator developed based on statistical analysis of the Hilbert marginal spectrum detects damage locations. Finally, the response sampled at the detected damage location is continuously analysed to estimate the damage severity. Numerical and experimental studies of frame structures under ambient excitations are performed. The results demonstrate that this scheme accomplishes the above damage detection functions within one flow. It is robust, time efficient, simply implemented and applicable to the real-time SHM of in-service structures. (paper)

  14. Chromosome structures: reduction of certain problems with unequal gene content and gene paralogs to integer linear programming.

    Science.gov (United States)

    Lyubetsky, Vassily; Gershgorin, Roman; Gorbunov, Konstantin

    2017-12-06

    Chromosome structure is a very limited model of the genome including the information about its chromosomes such as their linear or circular organization, the order of genes on them, and the DNA strand encoding a gene. Gene lengths, nucleotide composition, and intergenic regions are ignored. Although highly incomplete, such structure can be used in many cases, e.g., to reconstruct phylogeny and evolutionary events, to identify gene synteny, regulatory elements and promoters (considering highly conserved elements), etc. Three problems are considered; all assume unequal gene content and the presence of gene paralogs. The distance problem is to determine the minimum number of operations required to transform one chromosome structure into another and the corresponding transformation itself including the identification of paralogs in two structures. We use the DCJ model which is one of the most studied combinatorial rearrangement models. Double-, sesqui-, and single-operations as well as deletion and insertion of a chromosome region are considered in the model; the single ones comprise cut and join. In the reconstruction problem, a phylogenetic tree with chromosome structures in the leaves is given. It is necessary to assign the structures to inner nodes of the tree to minimize the sum of distances between terminal structures of each edge and to identify the mutual paralogs in a fairly large set of structures. A linear algorithm is known for the distance problem without paralogs, while the presence of paralogs makes it NP-hard. If paralogs are allowed but the insertion and deletion operations are missing (and special constraints are imposed), the reduction of the distance problem to integer linear programming is known. Apparently, the reconstruction problem is NP-hard even in the absence of paralogs. The problem of contigs is to find the optimal arrangements for each given set of contigs, which also includes the mutual identification of paralogs. We proved that these

  15. Uniqueness of First Order Post-Newtonian Collinear Solutions for Three-Body Problem under a Scalar-Tensor Theory

    Science.gov (United States)

    Cao, Wei-Guang; Zhou, Tian-Yi; Xie, Yi

    2017-10-01

    As a continuing investigation of an earlier work that establishes the collinear solutions to the three-body problem with general masses under a scalar-tensor theory, we study these solutions and prove their uniqueness up to the first order post-Newtonian approximation. With the help of observed bounds on the scalar field in the Solar System, we show that the seventh-order polynomial equation determining the distance ratio among the three masses has either one or three positive roots. However, in the case with three positive roots, it is found that two positive roots break down the slow-motion condition for the post-Newtonian approximation so that only one positive root is physically valid. The resulting uniqueness suggests that the locations of the three masses are very close to their Newtonian positions with post-Newtonian corrections of general relativity and the scalar field. We also prove that, in the framework of the scalar-tensor theory, the angular velocity of the collinear configuration is always less than the Newtonian one when all other parameters are fixed. These results are valid only for three-body systems where upper-bounds on the scalar field are compatible with those of the Solar System. Supported by the National Natural Science Foundation of China under Grant Nos. 11573015 and J1210039, and the Innovation Training Project for Undergraduates of Nanjing University, China

  16. First Principles Prediction of Structure, Structure Selectivity, and Thermodynamic Stability under Realistic Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ceder, Gerbrand [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials and Engineering

    2018-01-28

    Novel materials are often the enabler for new energy technologies. In ab-initio computational materials science, method are developed to predict the behavior of materials starting from the laws of physics, so that properties can be predicted before compounds have to be synthesized and tested. As such, a virtual materials laboratory can be constructed, saving time and money. The objectives of this program were to develop first-principles theory to predict the structure and thermodynamic stability of materials. Since its inception the program focused on the development of the cluster expansion to deal with the increased complexity of complex oxides. This research led to the incorporation of vibrational degrees of freedom in ab-initio thermodynamics, developed methods for multi-component cluster expansions, included the explicit configurational degrees of freedom of localized electrons, developed the formalism for stability in aqueous environments, and culminated in the first ever approach to produce exact ground state predictions of the cluster expansion. Many of these methods have been disseminated to the larger theory community through the Materials Project, pymatgen software, or individual codes. We summarize three of the main accomplishments.

  17. Factor structure and item level psychometrics of the Social Problem Solving Inventory-Revised: Short Form in traumatic brain injury.

    Science.gov (United States)

    Li, Chih-Ying; Waid-Ebbs, Julia; Velozo, Craig A; Heaton, Shelley C

    2016-01-01

    Social problem-solving deficits characterise individuals with traumatic brain injury (TBI), and poor social problem solving interferes with daily functioning and productive lifestyles. Therefore, it is of vital importance to use the appropriate instrument to identify deficits in social problem solving for individuals with TBI. This study investigates factor structure and item-level psychometrics of the Social Problem Solving Inventory-Revised: Short Form (SPSI-R:S), for adults with moderate and severe TBI. Secondary analysis of 90 adults with moderate and severe TBI who completed the SPSI-R:S was performed. An exploratory factor analysis (EFA), principal components analysis (PCA) and Rasch analysis examined the factor structure and item-level psychometrics of the SPSI-R:S. The EFA showed three dominant factors, with positively worded items represented as the most definite factor. The other two factors are negative problem-solving orientation and skills; and negative problem-solving emotion. Rasch analyses confirmed the three factors are each unidimensional constructs. It was concluded that the total score interpretability of the SPSI-R:S may be challenging due to the multidimensional structure of the total measure. Instead, we propose using three separate SPSI-R:S subscores to measure social problem solving for the TBI population.

  18. Factor Structure and Item Level Psychometrics of the Social Problem Solving Inventory Revised-Short Form in Traumatic Brain Injury

    Science.gov (United States)

    Li, Chih-Ying; Waid-Ebbs, Julia; Velozo, Craig A.; Heaton, Shelley C.

    2016-01-01

    Primary Objective Social problem solving deficits characterize individuals with traumatic brain injury (TBI). Poor social problem solving interferes with daily functioning and productive lifestyles. Therefore, it is of vital importance to use the appropriate instrument to identify deficits in social problem solving for individuals with TBI. This study investigates factor structure and item-level psychometrics of the Social Problem Solving Inventory-Revised Short Form (SPSI-R:S), for adults with moderate and severe TBI. Research Design Secondary analysis of 90 adults with moderate and severe TBI who completed the SPSI-R:S. Methods and Procedures An exploratory factor analysis (EFA), principal components analysis (PCA) and Rasch analysis examined the factor structure and item-level psychometrics of the SPSI-R:S. Main Outcomes and Results The EFA showed three dominant factors, with positively worded items represented as the most definite factor. The other two factors are negative problem solving orientation and skills; and negative problem solving emotion. Rasch analyses confirmed the three factors are each unidimensional constructs. Conclusions The total score interpretability of the SPSI-R:S may be challenging due to the multidimensional structure of the total measure. Instead, we propose using three separate SPSI-R:S subscores to measure social problem solving for the TBI population. PMID:26052731

  19. Numerical simulation of a nonlinear coupled fluid-structure problem. Application to the design of naval nuclear propulsion structures; Modelisation et simulation numerique d'un probleme couple fluide/structure non lineaire: application au dimensionnement de structures nucleaires de propulsion navale

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, J.F

    2004-11-15

    The present work deals with the numerical simulation of a coupled fluid/structure problem with fluid free surface. A generic coupled fluid/structure system is defined, on which a linear problem (modal analysis) and a non-linear problem (temporal analysis) are stated. In the linear case, a strong coupled method is used. It is based on a finite element approach of the structure problem and a finite or a boundary element approach of the fluid problem. The coupled problem is formulated in terms of pressure and displacement, leading to a non-symmetric problem which is solved with an appropriate algorithm. In the non-linear case, the structure problem is described with non-linear equations of motion, whereas the fluid problem is modeled with the Stokes equations. The numerical resolution of the coupled problem is based on a weak coupling procedure. The fluid problem is solved with a finite volume technique, using a moving mesh technique to adjust the structure motion, a VOF method for the description of the free surface and the PISO algorithm for the time integration. The structure problem is solved with a finite element technique, using an explicit/implicit time integration algorithm. A procedure is developed in order to handle the coupling in space (fluid forces and structure displacement exchanges between fluid and structure mesh, fluid re-meshing) and in time (staggered explicit algorithm, dynamic filtering of numerical oscillations). The non linear coupled problem is solved using a CFD code, whose use for FSI problem is validated with a benchmark presented in this work. A comparison is proposed between numerical results and analytical solution for two elementary fluid problems. The validation process can be applied for any CFD numerical code. A numerical study is then proposed on the generic coupled case in order to describe the fluid/structure interaction phenomenon (added mass, displaced mass, mode coupling, influence of structural non-linearity). An industrial

  20. Economic analysis of a Japanese air pollution regulation : an optimal retirement problem under vehicle type regulation in the NOx-particulate matter law

    Science.gov (United States)

    2008-06-01

    This paper empirically examines the vehicle type regulation that was introduced under the : Automobile Nitrogen OxidesParticulate Matter Law to mitigate air pollution problems in Japanese metropolitan areas. The vehicle type regulation effectively...

  1. “Markhi” spatial design structure: numerical study of its work under static load

    Directory of Open Access Journals (Sweden)

    Alpatov Vadim

    2016-01-01

    Full Text Available There is a problem of internal stress volume existing for some types of spatial structures and their joint connections. The problem occurs when a massive body is used as a joint connector. It is quite simple to determine tension on this joint connector surface using electric resistive tensometry method. It is not simple though to empirically determine internal tension in the massive body of the connector. To determine internal tension we can use modern calculation systems, such as Ansys, Abaqus, CosmosWorks, Nastran, Autodesk Inventor, Robot Structural Analysis, Bentley STAAD, CSI SAP2000; etc: Internal tension analysis in a massive joint connector makes possible to select both surplus stock parts and shortage stock parts. In this paper the authors base their analysis on both surface and internal tension of MARKHI connector and come up with solutions for its improvement.

  2. A new modal-based approach for modelling the bump foil structure in the simultaneous solution of foil-air bearing rotor dynamic problems

    Science.gov (United States)

    Bin Hassan, M. F.; Bonello, P.

    2017-05-01

    Recently-proposed techniques for the simultaneous solution of foil-air bearing (FAB) rotor dynamic problems have been limited to a simple bump foil model in which the individual bumps were modelled as independent spring-damper (ISD) subsystems. The present paper addresses this limitation by introducing a modal model of the bump foil structure into the simultaneous solution scheme. The dynamics of the corrugated bump foil structure are first studied using the finite element (FE) technique. This study is experimentally validated using a purpose-made corrugated foil structure. Based on the findings of this study, it is proposed that the dynamics of the full foil structure, including bump interaction and foil inertia, can be represented by a modal model comprising a limited number of modes. This full foil structure modal model (FFSMM) is then adapted into the rotordynamic FAB problem solution scheme, instead of the ISD model. Preliminary results using the FFSMM under static and unbalance excitation conditions are proven to be reliable by comparison against the corresponding ISD foil model results and by cross-correlating different methods for computing the deflection of the full foil structure. The rotor-bearing model is also validated against experimental and theoretical results in the literature.

  3. Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2012-01-01

    This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either...... be performed on the basis of different materials, and/or consist of discrete selection of the same orthotropic material with different orientations of the fibers. The problem considered is the optimization of a general laminated composite shell structure with respect to maximum stiffness (minimum compliance...

  4. Assessing Nursing Students' Clinical Competencies Using a Problem-Focused Objective Structured Clinical Examination.

    Science.gov (United States)

    Zhu, Xuemei; Yang, Li; Lin, Ping; Lu, Guizhi; Xiao, Ningning; Yang, Shufen; Sui, Shujie

    2016-09-01

    The objectives of this study were to develop, implement, and evaluate an innovative modified Objective Structured Clinical Examination (OSCE) model, and to compare students' performance of different clinical skills as assessed by standardized patients and OSCE examiners. Data were obtained from final year undergraduate students undergoing the modified OSCE as a graduation examination. Seventy-seven students rotated through four stations (nine substations). Standardized patients scored students higher than examiners in history taking (9.14 ± 0.92 vs. 8.42 ± 0.85), response to emergency event (8.88 ± 1.12 vs. 7.62 ± 1.54), executive medical orders (8.77 ± 0.96 vs. 8.25 ± 1.43), technical operation (18.21 ± 1.26 vs. 16.91 ± 1.35), nursing evaluation (4.53 ± 0.28 vs. 4.29 ± 0.52), and health education stations (13.79 ± 1.31 vs. 11.93 ± 2.25; p physical examination skills was nonsignificant (8.70 ± 1.18 vs. 8.80 ± 1.27; p > .05). The modified, problem-focused, and nursing process-driven OSCE model effectively assessed nursing students' clinical competencies, and clinical and critical thinking. © The Author(s) 2016.

  5. Psychosocial Problems among Truant Youths: A Multi-Group, Exploratory Structural Equation Modeling Analysis

    Science.gov (United States)

    Dembo, Richard; Briones-Robinson, Rhissa; Barrett, Kimberly; Winters, Ken C.; Ungaro, Rocio; Karas, Lora; Wareham, Jennifer; Belenko, Steven

    2012-01-01

    Truant youths represent a critical group needing problem-oriented research and involvement in effective services. The limited number of studies on the psychosocial functioning of truant youths have focused on one or a few problem areas, rather than examining comorbid problem behaviors. The present study addresses the need to examine the…

  6. Structural Changes of International Trade Flows under the Impact of Globalization

    Directory of Open Access Journals (Sweden)

    Anca Dachin

    2006-08-01

    Full Text Available Structural changes of international trade flows indicate modifications in competitiveness of countries, in terms of production, technological upgrading and exports under the pressure of globalization. The paper aims to point out sources of competitive advantages especially in manufacturing exports of different groups of countries. The focus is on the shifts in the structure of manufacturing in the European Union and their effects on international rankings in export performances. An important issue refers to the opportunities given by the enlargement of the European Union and their impact on EU trade structures.

  7. Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

    Directory of Open Access Journals (Sweden)

    Shi-Jian Zhu

    2014-01-01

    Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

  8. Railway crossings: driving the structure under the railway by means of oleodinamic jacks

    OpenAIRE

    Escribano Méndez, Ramón; López Palomar, Rafael; Ruiz Viedma, Andrés J.

    1991-01-01

    "The best level crossing is a dead crossing", those involved are accustomed to say Yet, until a short time ago, eliminating these conflictive crossings not only implied a great deal of money but prolonged building work, with the all too familiar sequel of precautions, speed restrictions and problems for rail traffic. However, a brand new system, based on using hydraulic jacks to drive the concrete structure of the crossing to a different level in the track embankment, allows the execution in ...

  9. Two-leaf wall structures under 'soft' impact load - aircraft crash

    International Nuclear Information System (INIS)

    Eibl, J.; Block, K.

    1982-01-01

    The article describes a mechanical model with which the load conditions associated with aircraft crash on a two-leaf wall or roof structure can be analysed quite simply. The necessary assumptions for the material behaviour governing the contact of the two slabs and, in general, the maximum limit deformations of reinforced concrete slabs are more particularly dealt with. Treating the problem the authors make use, inter alia, of some of their own experimental results. (orig.)

  10. Multi-walled carbon nanotube structural instability with/without metal nanoparticles under electron beam irradiation

    Science.gov (United States)

    Khan, Imran; Huang, Shengli; Wu, Chenxu

    2017-12-01

    The structural transformation of multi-walled carbon nanotubes (MWCNT) under electron beam (e-beam) irradiation at room temperature is studied, with respect to a novel passivation effect due to gold nanoparticles (Au NPs). MWCNT structural evolution induced by energetic e-beam irradiation leads to faster shrinkage, as revealed via in situ transmission electron microscopy, while MWCNT surface modification with Au NPs (Au-MWCNT) slows down the shrinkage by impeding the structural evolution process for a prolonged time under the same irradiation conditions. The new relationship between MWCNT and Au-MWCNT shrinking radii and irradiation time illustrates that the MWCNT shrinkage rate is faster than either theoretical predictions or the same process in Au-MWCNTs. As compared with the outer surface energy (positive curvature), the inner surface energy (negative curvature) of the MWCNT contributes more to the athermal evaporation of tube wall atoms, leading to structural instability and shrinkage under e-beam irradiation. Conversely, Au NPs possess only outer surface energy (positive curvature) compared with the MWCNT. Their presence on MWCNT surfaces retards the dynamics of MWCNT structural evolution by slowing down the evaporation process of carbon atoms, thus restricting Au-MWCNT shrinkage. Au NP interaction and growth evolves athermally on MWCNT surfaces, exhibits increase in their size, and indicates the association of this mechanism with the coalescence induced by e-beam activated electronic excitations. Despite their growth, Au NPs show extreme structural stability, and remain crystalline under prolonged irradiation. It is proposed that the surface energy of MWCNTs and Au NPs, together with e-beam activated soft modes or lattice instability effects, predominantly govern all the above varieties of structural evolution.

  11. Use of three-dimensional parameters in the analysis of crystal structures under compression

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci

    2007-01-01

    Volume-related parameters of atomic coordinations are an important tool for the analysis of structural changes. Unlike usual tables of bond distances and angles they directly depict three-dimensional properties of coordination polyhedra, and in many instances give more profound structural...... data through use of a procrystal model. For non-regular coordination polyhedra a determination of the point with the minimum variation of distances to the vertices (the centroid of coordination) is a necessary prerequisite for a calculation of the volume-related parameters. The three parameters...... of the coordination polyhedra of cations and the voids that separate them. Analysis of individual compressional characteristics of structural components gives clues for the strong and weak parts of structures under high pressures and paths for structural transformations. The expected behaviour of distortion...

  12. Blast Responses and Vibration of Flood-Defense Structures under High-Intensity Blast Loadings

    Directory of Open Access Journals (Sweden)

    Yonghee Ryu

    2018-01-01

    Full Text Available This study presented the blast behavior of flood-defense structures subjected to high-intensity loadings such as blast shock waves. In order to understand the blast behavior of weir structures, PHAST program was used to predict blast loadings in consideration of material reactivity and congestion levels. Environment factors such as weather data and atmospheric parameters were also considered in this study. Then, nonlinear dynamic analyses were performed using the ABAQUS platform to evaluate structural responses and blast vibration of concrete weir structures subjected to various types of blast loadings, due to uncertainties of the magnitude and durations of blast loads as a function of distance from the explosion. It was shown that the blast damage to concrete weir structure was significantly influenced by congestion levels or material reactivity. Also, the stress concentration under blast loading was observed at the connection area between the concrete weir body and stilling basin.

  13. Self-Regulation in the Midst of Complexity: A Case Study of High School Physics Students Engaged in Ill-Structured Problem Solving

    Science.gov (United States)

    Milbourne, Jeffrey David

    The purpose of this dissertation study was to explore the experiences of high school physics students who were solving complex, ill-structured problems, in an effort to better understand how self-regulatory behavior mediated the project experience. Consistent with Voss, Green, Post, and Penner's (1983) conception of an ill-structured problem in the natural sciences, the 'problems' consisted of scientific research projects that students completed under the supervision of a faculty mentor. Zimmerman and Campillo's (2003) self-regulatory framework of problem solving provided a holistic guide to data collection and analysis of this multi-case study, with five individual student cases. The study's results are explored in two manuscripts, each targeting a different audience. The first manuscript, intended for the Science Education Research community, presents a thick, rich description of the students' project experiences, consistent with a qualitative, case study analysis. Findings suggest that intrinsic interest was an important self-regulatory factor that helped motivate students throughout their project work, and that the self-regulatory cycle of forethought, performance monitoring, and self-reflection was an important component of the problem-solving process. Findings also support the application of Zimmerman and Campillo's framework to complex, ill-structured problems, particularly the cyclical nature of the framework. Finally, this study suggests that scientific research projects, with the appropriate support, can be a mechanism for improving students' selfregulatory behavior. The second manuscript, intended for Physics practitioners, combines the findings of the first manuscript with the perspectives of the primary, on-site research mentor, who has over a decade's worth of experience mentoring students doing physics research. His experience suggests that a successful research experience requires certain characteristics, including: a slow, 'on-ramp' to the research

  14. Probing the local, electronic and magnetic structure of matter under extreme conditions of temperature and pressure

    DEFF Research Database (Denmark)

    Torchio, R.; Boccato, S.; Cerantola, V.

    2016-01-01

    In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy-dispersive...

  15. 61. International conference NUCLEUS-2011 on problems of nuclear spectroscopy and structure of atomic nucleus. Book of abstracts

    International Nuclear Information System (INIS)

    2011-01-01

    The program of the 61th International conference NUCLEUS-2011 covers almost all actual problems of nuclear physics. The recent results of theoretical and experimental investigations of nuclear structure as well as nuclear reactions are presented. The fundamental problems of nuclear physics are discussed. The current achievements in the field of nuclear instrumentation and experimental techniques are considered. The considerable attention is given to modern nuclear databases as scientific research tools [ru

  16. Iterative solution of multiple radiation and scattering problems in structural acoustics using the BL-QMR algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Malhotra, M. [Stanford Univ., CA (United States)

    1996-12-31

    Finite-element discretizations of time-harmonic acoustic wave problems in exterior domains result in large sparse systems of linear equations with complex symmetric coefficient matrices. In many situations, these matrix problems need to be solved repeatedly for different right-hand sides, but with the same coefficient matrix. For instance, multiple right-hand sides arise in radiation problems due to multiple load cases, and also in scattering problems when multiple angles of incidence of an incoming plane wave need to be considered. In this talk, we discuss the iterative solution of multiple linear systems arising in radiation and scattering problems in structural acoustics by means of a complex symmetric variant of the BL-QMR method. First, we summarize the governing partial differential equations for time-harmonic structural acoustics, the finite-element discretization of these equations, and the resulting complex symmetric matrix problem. Next, we sketch the special version of BL-QMR method that exploits complex symmetry, and we describe the preconditioners we have used in conjunction with BL-QMR. Finally, we report some typical results of our extensive numerical tests to illustrate the typical convergence behavior of BL-QMR method for multiple radiation and scattering problems in structural acoustics, to identify appropriate preconditioners for these problems, and to demonstrate the importance of deflation in block Krylov-subspace methods. Our numerical results show that the multiple systems arising in structural acoustics can be solved very efficiently with the preconditioned BL-QMR method. In fact, for multiple systems with up to 40 and more different right-hand sides we get consistent and significant speed-ups over solving the systems individually.

  17. Analyses of a steel containment vessel with an outer contact structure under severe internal overpressurization conditions

    International Nuclear Information System (INIS)

    Porter, V.L.

    1994-01-01

    Many Mark-I and Mark-II BWR plants are designed with a steel vessel as the primary containment. Typically, the steel containment vessel (SCV) is enclosed within a reinforced concrete shield building with only a small gap (74-90 mm) separating the two structures. This paper describes finite element analyses performed to evaluate the effects of contact and friction between a steel containment vessel and an outer contact structure when the containment vessel is subjected to large internal pressures. These computations were motivated by a joint program on containment integrity involving the Nuclear Power Engineering Corporation (NUPEC) of Japan, the US Nuclear Regulatory Commission (NRC), and Sandia National Laboratories for testing model containments. Under severe accident loading conditions, the steel containment vessel in a typical Mark-I or Mark-II plant may deform under internal pressurization such that it contacts the inner surface of a shield building wall. (Thermal expansion from increasing accident temperatures would also close the gap between the SCV and the shield building, but temperature effects are not considered in these analyses.) The amount and location of contact and the pressure at which it occurs all affect how the combined structure behaves. A preliminary finite element model has been developed to analyze a model of a typical steel containment vessel con-ling into contact with an outer structure. Both the steel containment vessel and the outer contact structure were modelled with axisymmetric shell finite elements. Of particular interest are the influence that the contact structure has on deformation and potential failure modes of the containment vessel. Furthermore, the coefficient of friction between the two structures was varied to study its effects on the behavior of the containment vessel and on the uplift loads transmitted to the contact structure. These analyses show that the material properties of an outer contact structure and the amount

  18. Model-Based Heterogeneous Data Fusion for Reliable Force Estimation in Dynamic Structures under Uncertainties.

    Science.gov (United States)

    Khodabandeloo, Babak; Melvin, Dyan; Jo, Hongki

    2017-11-17

    Direct measurements of external forces acting on a structure are infeasible in many cases. The Augmented Kalman Filter (AKF) has several attractive features that can be utilized to solve the inverse problem of identifying applied forces, as it requires the dynamic model and the measured responses of structure at only a few locations. But, the AKF intrinsically suffers from numerical instabilities when accelerations, which are the most common response measurements in structural dynamics, are the only measured responses. Although displacement measurements can be used to overcome the instability issue, the absolute displacement measurements are challenging and expensive for full-scale dynamic structures. In this paper, a reliable model-based data fusion approach to reconstruct dynamic forces applied to structures using heterogeneous structural measurements (i.e., strains and accelerations) in combination with AKF is investigated. The way of incorporating multi-sensor measurements in the AKF is formulated. Then the formulation is implemented and validated through numerical examples considering possible uncertainties in numerical modeling and sensor measurement. A planar truss example was chosen to clearly explain the formulation, while the method and formulation are applicable to other structures as well.

  19. Proceedings of the CSNI workshop on International Standard Problem 48 - Analysis of 1:4-scale prestressed concrete containment vessel model under severe accident conditions

    International Nuclear Information System (INIS)

    2005-01-01

    At the CSNI meeting in June 2002, the proposal for an International Standard Problem on containment integrity (ISP 48) based on the NRC/NUPEC/Sandia test was approved. Objectives were to extend the understanding of capacities of actual containment structures based on results of the recent PCCV Model test and other previous research. The ISP was sponsored by the USNRC, and results had been made available thanks to NUPEC and to the USNRC. Sandia National Laboratory was contracted to manage the technical aspects of the ISP. At the end of the ISP48, a workshop was organized in Lyon, France on April 6-7, 2005 hosted by Electricite de France. Its overall objective was to present results obtained by participants in the ISP 48 and to assess the current practices and the state of the art with respect to the calculation of concrete structures under severe accident conditions. Experience from other areas in civil engineering related to the modelling of complex structures was greatly beneficial to all. Information obtained as a result of this assessment were utilized to develop a consensus on these calculations and identify issues or 'gaps' in the present knowledge for the primary purpose of formulating and prioritizing research needs on this topic. The ISP48 exercise was published in the report referenced NEA/CSNI/R(2005)5 in 3 volumes. Volume 1 contains the synthesis of the exercise; Volumes 2 and 3 contain individual contributions of participating organizations. The CSNI Working Group on the Integrity and Ageing and in particular its sub-group on the behaviour of concrete structures has produced extensive material over the last few years. The complete list of references is given in this document. These proceedings gather the papers and presentations given by the participants at the Lyon workshop

  20. Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

    Directory of Open Access Journals (Sweden)

    Lifeng Luan

    2015-01-01

    Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.