Sample records for behavior engineering model

  1. A Model-Based Approach to Engineering Behavior of Complex Aerospace Systems

    NASA Technical Reports Server (NTRS)

    Ingham, Michel; Day, John; Donahue, Kenneth; Kadesch, Alex; Kennedy, Andrew; Khan, Mohammed Omair; Post, Ethan; Standley, Shaun

    2012-01-01

    One of the most challenging yet poorly defined aspects of engineering a complex aerospace system is behavior engineering, including definition, specification, design, implementation, and verification and validation of the system's behaviors. This is especially true for behaviors of highly autonomous and intelligent systems. Behavior engineering is more of an art than a science. As a process it is generally ad-hoc, poorly specified, and inconsistently applied from one project to the next. It uses largely informal representations, and results in system behavior being documented in a wide variety of disparate documents. To address this problem, JPL has undertaken a pilot project to apply its institutional capabilities in Model-Based Systems Engineering to the challenge of specifying complex spacecraft system behavior. This paper describes the results of the work in progress on this project. In particular, we discuss our approach to modeling spacecraft behavior including 1) requirements and design flowdown from system-level to subsystem-level, 2) patterns for behavior decomposition, 3) allocation of behaviors to physical elements in the system, and 4) patterns for capturing V&V activities associated with behavioral requirements. We provide examples of interesting behavior specification patterns, and discuss findings from the pilot project.

  2. Uncertainty and sensitivity analysis of fission gas behavior in engineering-scale fuel modeling

    SciTech Connect

    G. Pastore; L.P. Swiler; J.D. Hales; S.R. Novascone; D.M. Perez; B.W. Spencer; L. Luzzi; P. Van Uffelen; R.L. Williamson

    2014-10-01

    The role of uncertainties in fission gas behavior calculations as part of engineering-scale nuclear fuel modeling is investigated using the BISON fuel performance code and a recently implemented physics-based model for the coupled fission gas release and swelling. Through the integration of BISON with the DAKOTA software, a sensitivity analysis of the results to selected model parameters is carried out based on UO2 single-pellet simulations covering different power regimes. The parameters are varied within ranges representative of the relative uncertainties and consistent with the information from the open literature. The study leads to an initial quantitative assessment of the uncertainty in fission gas behavior modeling with the parameter characterization presently available. Also, the relative importance of the single parameters is evaluated. Moreover, a sensitivity analysis is carried out based on simulations of a fuel rod irradiation experiment, pointing out a significant impact of the considered uncertainties on the calculated fission gas release and cladding diametral strain. The results of the study indicate that the commonly accepted deviation between calculated and measured fission gas release by a factor of 2 approximately corresponds to the inherent modeling uncertainty at high fission gas release. Nevertheless, higher deviations may be expected for values around 10% and lower. Implications are discussed in terms of directions of research for the improved modeling of fission gas behavior for engineering purposes.

  3. Qualitative and temporal reasoning in engine behavior analysis

    NASA Technical Reports Server (NTRS)

    Dietz, W. E.; Stamps, M. E.; Ali, M.

    1987-01-01

    Numerical simulation models, engine experts, and experimental data are used to generate qualitative and temporal representations of abnormal engine behavior. Engine parameters monitored during operation are used to generate qualitative and temporal representations of actual engine behavior. Similarities between the representations of failure scenarios and the actual engine behavior are used to diagnose fault conditions which have already occurred, or are about to occur; to increase the surveillance by the monitoring system of relevant engine parameters; and to predict likely future engine behavior.

  4. Through the Use of Gilbert's Behavioral Engineering Model, What Changes Can Management Make to Increase Blood Donations?

    ERIC Educational Resources Information Center

    Russell, Heather Gordy

    2010-01-01

    The mixed method study focused on increasing blood donations from staff who work in a blood collecting organization and relies on Gilbert's Behavior Engineering Model as a framework. The qualitative phase of the study involved focus groups. Information from the focus groups and the literature review were used to create hypotheses. A survey was…

  5. A Microstructurally Motivated Model of the Mechanical Behavior of Tissue Engineered Blood Vessels

    PubMed Central

    Dahl, Shannon L. M.; Vaughn, Megann E.; Hu, Jin-Jia; Driessen, Niels J. B.; Baaijens, Frank P. T.; Humphrey, Jay D.; Niklason, Laura E.

    2008-01-01

    Mechanical models have potential to guide the development and use of engineered blood vessels as well as other engineered tissues. This paper presents a microstructurally motivated, pseudoelastic, mechanical model of the biaxial mechanics of engineered vessels in the physiologic pressure range. The model incorporates experimentally measured densities and alignments of engineered collagen. Specifically, these microstructural and associated mechanical inputs were measured directly from engineered blood vessels that were cultured over periods of 5–7.5 weeks. To the best of our knowledge, this is the first successful application of either a phenomenological or a microstructurally motivated mechanical model to engineered vascular tissues. Model development revealed the need to use novel theoretical configurations to describe the strain history of engineered vessels. The constitutive equations developed herein suggested that collagen remodeled between 5 and 7.5 weeks during a 7.5-week culture period. This remodeling led to strain energies for collagen that differed with alignment, which likely resulted from undulations that varied with alignment. Finally, biaxial data emphasized that axial extensions increase stresses in engineered vessels in the physiologic pressure range, thereby providing a guideline for surgical use: engineered vessels should be implanted at appropriate axial extension to minimize adverse stress responses. PMID:18720007

  6. Behaviorally Engineered Environments. Staff Papers.

    ERIC Educational Resources Information Center

    Morreau, Larry E.; And Others

    This collection of papers represents the developmental research as well as the thrust of the Regional Laboratory's (UMREL) program. UMREL has been developing behaviorally engineered educational environments through a cross-disciplinary effort in education and the behavioral sciences. The program began with the establishment of demonstration…

  7. Modeling the structural behavior of the piston rings under different boundary conditions in internal combustion engines

    E-print Network

    Xu, Dian

    2010-01-01

    In the process of designing internal combustion engine, piston ring plays an important role in fulfilling the requirements of camber gas sealing, friction reduction and lubrication oil consumption. The goal of this thesis ...

  8. Development of Fabric Constitutive Behavior for Use in Modeling Engine Fan Blade-Out Events

    E-print Network

    Mobasher, Barzin

    significant importance in the design of fan-containment systems. Currently, Kevlar is the only fabric approved to quantify the behavior of Kevlar when subjected to high-velocity projectiles. Experi- mental static and high properties of Kevlar fabric. In this paper we discuss the development and verification of a constitutive

  9. A nonlinear model to analyze the behaviors of the idle speed and the liquid fuel film in gasoline engines

    Microsoft Academic Search

    Chuan He

    1996-01-01

    Recent demands for maximum fuel economy, better driveability and minimum exhaust emissions, have placed stringent conditions under which a gasoline engine can operate during idling or transient conditions. To address this problem, a physics based nonlinear model for a four-stroke, multi-point with sequential fueling gasoline engine is developed in this study. The formulation has been structured in such a manner

  10. JOURNAL OF STRUCTURAL ENGINEERING / JANUARY 2001 / 3 MODELING SHEAR BEHAVIOR OF HYBRID RCS

    E-print Network

    Parra-Montesinos, Gustavo J.

    and concrete diagonal struts. The joint model is capable of predicting the shear force, and stirrup in exterior RCS joints, when using the ASCE design guidelines. Therefore, a new model to predict the shear force, and stirrup and concrete strains at any level of shear distortion in RCS joints was developed

  11. Relation of Contextual Supports and Barriers to Choice Behavior in Engineering Majors: Test of Alternative Social Cognitive Models

    ERIC Educational Resources Information Center

    Lent, Robert W.; Brown, Steven D.; Schmidt, Janet; Brenner, Bradley; Lyons, Heather; Treistman, Dana

    2003-01-01

    Social cognitive career theory (SCCT; R. W. Lent, S. D. Brown, and G. Hackett, 1994) and general social cognitive theory (Bandura, 1999, 2000) posit somewhat different relations between contextual variables and choice actions. The authors tested the predictions of these 2 model variations. Participants (328 students in an introductory engineering

  12. Smart Engines Via Advanced Model Based Controls

    SciTech Connect

    Allain, Marc

    2000-08-20

    A ''new'' process for developing control systems - Less engine testing - More robust control system - Shorter development cycle time - ''Smarter'' approach to engine control - On-board models describe engine behavior - Shorter, systematic calibration process - Customer and legislative requirements designed-in.

  13. A game theory-based analysis of search engine non-neutral behavior

    E-print Network

    Paris-Sud XI, Université de

    , a search engine can effectively exclude nascent websites from both advertising and sales revenue. Another and accessed by a search engine user. A simple game theory-based model is presented where both a search engine and a content provider interact strategically, and the aggregated behavior of users is modeled by a demand

  14. Principles of models based engineering

    SciTech Connect

    Dolin, R.M.; Hefele, J.

    1996-11-01

    This report describes a Models Based Engineering (MBE) philosophy and implementation strategy that has been developed at Los Alamos National Laboratory`s Center for Advanced Engineering Technology. A major theme in this discussion is that models based engineering is an information management technology enabling the development of information driven engineering. Unlike other information management technologies, models based engineering encompasses the breadth of engineering information, from design intent through product definition to consumer application.

  15. Mechanical Behavior of Grain Boundary Engineered Copper

    SciTech Connect

    Carter, S B; Hodge, A M

    2006-08-08

    A grain boundary engineered copper sample previously characterized by Electron Backscatter Diffraction (EBSD) has been selected for nanoindentation tests. Given the fact that grain boundaries have thicknesses in the order of 1 micron or less, it is essential to use nanomechanics to test the properties of individual grain boundaries. The Hysitron nanoindenter was selected over the MTS nanoindenter due to its superior optical capabilities that aid the selection and identification of the areas to be tested. An area of 2mm by 2mm with an average grain size of 50 microns has been selected for the study. Given the EBSD mapping, grains and grain boundaries with similar orientations are tested and the hardness and modulus are compared. These results will give a relationship between the mechanical properties and the engineered grain boundaries. This will provide for the first time a correlation between grain boundary orientation and the mechanical behavior of the sample at the nanoscale.

  16. Structural Equation Modeling for Travel Behavior Research

    E-print Network

    Golob, Thomas F.

    2001-01-01

    2 Structural Equation Modeling for Travel Behavior Researchstructural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,

  17. Toward a Web Search Information Behavior Model

    NASA Astrophysics Data System (ADS)

    Knight, S. A.; Spink, A.

    Information retrieval (IR) research in the context of the Web involves a number of complex processes. Some are user-related and include cognitive processes, motivational issues, information needs, technology attitude and adoption; and some are system related and include search engine algorithms and interface design. The field currently lacks a comprehensive model of Web interaction in the information behavior context. This chapter first explores a range of information behavior, and information seeking and retrieval model. Research relating to how users seek out and retrieve information in electronic environments will be examined and these models considered for applicability to the information environment of the Web. The exploration begins at the broadest level, examining information seeking models and then interactive IR models, followed by more recent integrated models. The paper then proposes macro model of Web-based information seeking and searching behavior. Further research areas are also discussed.

  18. COMPUTATIONAL MODELS FOR CIVIL ENGINEERING

    E-print Network

    Fernandez, Thomas

    #12;COMPUTATIONAL MODELS FOR CIVIL ENGINEERING Constantin Ionescu, Alex Horia Brbat, Rodian;Proceedings of the Sixth International Symposium " Computational Civil Engineering 2008" Iai, Romania, May 30, 2008 Descrierea CIP a Bibliotecii Naionale a României Computational models for civil engineering / ed

  19. Efficient Model-Based Diagnosis Engine

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Vatan, Farrokh; Barrett, Anthony; James, Mark; Mackey, Ryan; Williams, Colin

    2009-01-01

    An efficient diagnosis engine - a combination of mathematical models and algorithms - has been developed for identifying faulty components in a possibly complex engineering system. This model-based diagnosis engine embodies a twofold approach to reducing, relative to prior model-based diagnosis engines, the amount of computation needed to perform a thorough, accurate diagnosis. The first part of the approach involves a reconstruction of the general diagnostic engine to reduce the complexity of the mathematical-model calculations and of the software needed to perform them. The second part of the approach involves algorithms for computing a minimal diagnosis (the term "minimal diagnosis" is defined below). A somewhat lengthy background discussion is prerequisite to a meaningful summary of the innovative aspects of the present efficient model-based diagnosis engine. In model-based diagnosis, the function of each component and the relationships among all the components of the engineering system to be diagnosed are represented as a logical system denoted the system description (SD). Hence, the expected normal behavior of the engineering system is the set of logical consequences of the SD. Faulty components lead to inconsistencies between the observed behaviors of the system and the SD (see figure). Diagnosis - the task of finding faulty components - is reduced to finding those components, the abnormalities of which could explain all the inconsistencies. The solution of the diagnosis problem should be a minimal diagnosis, which is a minimal set of faulty components. A minimal diagnosis stands in contradistinction to the trivial solution, in which all components are deemed to be faulty, and which, therefore, always explains all inconsistencies.

  20. Surface Engineering of Liposomes for Stealth Behavior

    PubMed Central

    Nag, Okhil K.; Awasthi, Vibhudutta

    2013-01-01

    Liposomes are used as a delivery vehicle for drug molecules and imaging agents. The major impetus in their biomedical applications comes from the ability to prolong their circulation half-life after administration. Conventional liposomes are easily recognized by the mononuclear phagocyte system and are rapidly cleared from the blood stream. Modification of the liposomal surface with hydrophilic polymers delays the elimination process by endowing them with stealth properties. In recent times, the development of various materials for surface engineering of liposomes and other nanomaterials has made remarkable progress. Poly(ethylene glycol)-linked phospholipids (PEG-PLs) are the best representatives of such materials. Although PEG-PLs have served the formulation scientists amazingly well, closer scrutiny has uncovered a few shortcomings, especially pertaining to immunogenicity and pharmaceutical characteristics (drug loading, targeting, etc.) of PEG. On the other hand, researchers have also begun questioning the biological behavior of the phospholipid portion in PEG-PLs. Consequently, stealth lipopolymers consisting of non-phospholipids and PEG-alternatives are being developed. These novel lipopolymers offer the potential advantages of structural versatility, reduced complement activation, greater stability, flexible handling and storage procedures and low cost. In this article, we review the materials available as alternatives to PEG and PEG-lipopolymers for effective surface modification of liposomes. PMID:24300562

  1. Editor's Roundtable: Model behavior

    NSDL National Science Digital Library

    Inez Liftig

    2010-11-01

    Models are manageable representations of objects, concepts, and phenomena, and are everywhere in science. Models are "thinking tools" for scientists and have always played a key role in the development of scientific knowledge. Models of the solar system,

  2. Rocket engine diagnostics using qualitative modeling techniques

    NASA Astrophysics Data System (ADS)

    Binder, Michael; Maul, William; Meyer, Claudia; Sovie, Amy

    1992-07-01

    Researchers at NASA Lewis Research Center are presently developing qualitative modeling techniques for automated rocket engine diagnostics. A qualitative model of a turbopump interpropellant seal system has been created. The qualitative model describes the effects of seal failures on the system steady-state behavior. This model is able to diagnose the failure of particular seals in the system based on anomalous temperature and pressure values. The anomalous values input to the qualitative model are generated using numerical simulations. Diagnostic test cases include both single and multiple seal failures.

  3. Rocket engine diagnostics using qualitative modeling techniques

    NASA Astrophysics Data System (ADS)

    Binder, Michael; Maul, William; Meyer, Claudia; Sovie, Amy

    1992-07-01

    Researchers at NASA Lewis Research Center are presently developing qualitative modeling techniques for automated rocket engine diagnostics. A qualitative model of a turbopump interpropellant seal system was created. The qualitative model describes the effects of seal failures on the system steady state behavior. This model is able to diagnose the failure of particular seals in the system based on anomalous temperature and pressure values. The anomalous values input to the qualitative model are generated using numerical simulations. Diagnostic test cases include both single and multiple seal failures.

  4. Rocket engine diagnostics using qualitative modeling techniques

    NASA Technical Reports Server (NTRS)

    Binder, Michael; Maul, William; Meyer, Claudia; Sovie, Amy

    1992-01-01

    Researchers at NASA Lewis Research Center are presently developing qualitative modeling techniques for automated rocket engine diagnostics. A qualitative model of a turbopump interpropellant seal system was created. The qualitative model describes the effects of seal failures on the system steady state behavior. This model is able to diagnose the failure of particular seals in the system based on anomalous temperature and pressure values. The anomalous values input to the qualitative model are generated using numerical simulations. Diagnostic test cases include both single and multiple seal failures.

  5. Rocket engine diagnostics using qualitative modeling techniques

    NASA Technical Reports Server (NTRS)

    Binder, Michael; Maul, William; Meyer, Claudia; Sovie, Amy

    1992-01-01

    Researchers at NASA Lewis Research Center are presently developing qualitative modeling techniques for automated rocket engine diagnostics. A qualitative model of a turbopump interpropellant seal system has been created. The qualitative model describes the effects of seal failures on the system steady-state behavior. This model is able to diagnose the failure of particular seals in the system based on anomalous temperature and pressure values. The anomalous values input to the qualitative model are generated using numerical simulations. Diagnostic test cases include both single and multiple seal failures.

  6. Engineering workstation: Sensor modeling

    NASA Technical Reports Server (NTRS)

    Pavel, M; Sweet, B.

    1993-01-01

    The purpose of the engineering workstation is to provide an environment for rapid prototyping and evaluation of fusion and image processing algorithms. Ideally, the algorithms are designed to optimize the extraction of information that is useful to a pilot for all phases of flight operations. Successful design of effective fusion algorithms depends on the ability to characterize both the information available from the sensors and the information useful to a pilot. The workstation is comprised of subsystems for simulation of sensor-generated images, image processing, image enhancement, and fusion algorithms. As such, the workstation can be used to implement and evaluate both short-term solutions and long-term solutions. The short-term solutions are being developed to enhance a pilot's situational awareness by providing information in addition to his direct vision. The long term solutions are aimed at the development of complete synthetic vision systems. One of the important functions of the engineering workstation is to simulate the images that would be generated by the sensors. The simulation system is designed to use the graphics modeling and rendering capabilities of various workstations manufactured by Silicon Graphics Inc. The workstation simulates various aspects of the sensor-generated images arising from phenomenology of the sensors. In addition, the workstation can be used to simulate a variety of impairments due to mechanical limitations of the sensor placement and due to the motion of the airplane. Although the simulation is currently not performed in real-time, sequences of individual frames can be processed, stored, and recorded in a video format. In that way, it is possible to examine the appearance of different dynamic sensor-generated and fused images.

  7. Structural Equation Modeling For Travel Behavior Research

    E-print Network

    Golob, Thomas F.

    2011-01-01

    structural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,Structural equation models, travel behavior, travel demand modeling, Statistical methods, discrete choice models, dynamic models, attitudinal data SEM for travel behavior Research

  8. Structural Equation Modeling For Travel Behavior Research

    E-print Network

    Golob, Thomas F.

    2001-01-01

    structural equation modeling in travel behavior research areStructural equation modeling is becoming widely used in travel behavior research,Structural equation models, travel behavior, travel demand modeling, Statistical methods, discrete choice models, dynamic models, attitudinal data SEM for travel behavior Research

  9. An opinion-driven behavioral dynamics model for addictive behaviors

    NASA Astrophysics Data System (ADS)

    Moore, Thomas W.; Finley, Patrick D.; Apelberg, Benjamin J.; Ambrose, Bridget K.; Brodsky, Nancy S.; Brown, Theresa J.; Husten, Corinne; Glass, Robert J.

    2015-04-01

    We present a model of behavioral dynamics that combines a social network-based opinion dynamics model with behavioral mapping. The behavioral component is discrete and history-dependent to represent situations in which an individual's behavior is initially driven by opinion and later constrained by physiological or psychological conditions that serve to maintain the behavior. Individuals are modeled as nodes in a social network connected by directed edges. Parameter sweeps illustrate model behavior and the effects of individual parameters and parameter interactions on model results. Mapping a continuous opinion variable into a discrete behavioral space induces clustering on directed networks. Clusters provide targets of opportunity for influencing the network state; however, the smaller the network the greater the stochasticity and potential variability in outcomes. This has implications both for behaviors that are influenced by close relationships verses those influenced by societal norms and for the effectiveness of strategies for influencing those behaviors.

  10. Gas-turbine engine steady-state behavior

    NASA Astrophysics Data System (ADS)

    Curnock, Barry

    A set of graphics with explanations illustrating gas turbine engine steady state behavior are presented. Typical combinations of compressors and nozzles which occur in a gas turbine engine are shown. The basic effect of a nozzle is explained by considering a compressor on a test rig: typical compressor, fan, and turbine characteristics are illustrated. The following are discussed: the degrees of freedom of an aeroengine (the flow and the power); the 'working lines' of components (the locus of the off design steady state operating points of a component plotted on a chart of that components characteristics); bleed and whirl; offtakes; P1 effects (performance changes which modify the basic nondimensional behavior an engine (caused by the effect on Reynolds number levels and on engine mechanical configuration of basic engine inlet pressure level)), and T1 effects (performance changes which modify the basic nondimensional behavior of an engine and are caused by the effects of engine inlet temperature level on Reynolds number level, on engine mechanical configuration and on specific heat level); variable nozzles; and turbojet matching.

  11. Workshop on Engineering Turbulence Modeling

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A. (editor); Liou, W. W. (editor); Shabbir, A. (editor); Shih, T.-H. (editor)

    1992-01-01

    Discussed here is the future direction of various levels of engineering turbulence modeling related to computational fluid dynamics (CFD) computations for propulsion. For each level of computation, there are a few turbulence models which represent the state-of-the-art for that level. However, it is important to know their capabilities as well as their deficiencies in order to help engineers select and implement the appropriate models in their real world engineering calculations. This will also help turbulence modelers perceive the future directions for improving turbulence models. The focus is on one-point closure models (i.e., from algebraic models to higher order moment closure schemes and partial differential equation methods) which can be applied to CFD computations. However, other schemes helpful in developing one-point closure models, are also discussed.

  12. Modelling intelligent behavior

    NASA Technical Reports Server (NTRS)

    Green, H. S.; Triffet, T.

    1993-01-01

    An introductory discussion of the related concepts of intelligence and consciousness suggests criteria to be met in the modeling of intelligence and the development of intelligent materials. Methods for the modeling of actual structure and activity of the animal cortex have been found, based on present knowledge of the ionic and cellular constitution of the nervous system. These have led to the development of a realistic neural network model, which has been used to study the formation of memory and the process of learning. An account is given of experiments with simple materials which exhibit almost all properties of biological synapses and suggest the possibility of a new type of computer architecture to implement an advanced type of artificial intelligence.

  13. Behavior model for performance assessment

    SciTech Connect

    Brown-VanHoozer, S.A.

    1999-07-01

    Identifying individual mental mechanisms or processes, organizing the individual strategies of these mechanisms into useful patterns, and formulating these into models for success and knowledge-based outcomes is easily done and can be accomplished through the use of neurological cues. Once identified, analog models can be constructed from the cues, and tree analysis models can be developed and then digitized through such methods as Bayesian concepts or a continuous wavelet transform. The authors are intent upon understanding behavior and constructing models from a macro level of understanding the process. The author has yet to accept the fact that the author needs to understand the how at the micro level of strategy building. Knowing what to observe and how to state questions so as to gather precise information regarding strategies being processed provides the means to refine those models existing today to be more effective in their analysis of human behaviors.

  14. Engine environmental effects on composite behavior

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Smith, G. T.

    1980-01-01

    A series of programs were conducted to investigate and develop the application of composite materials to turbojet engines. A significant part of that effort was directed to establishing the impact resistance and defect growth chracteristics of composite materials over the wide range of environmental conditions found in commercial turbojet engine operations. Both analytical and empirical efforts were involved. The experimental programs and the analytical methodology development as well as an evaluation program for the use of composite materials as fan exit guide vanes are summarized.

  15. An Object Model for a Rocket Engine Numerical Simulator

    NASA Technical Reports Server (NTRS)

    Mitra, D.; Bhalla, P. N.; Pratap, V.; Reddy, P.

    1998-01-01

    Rocket Engine Numerical Simulator (RENS) is a packet of software which numerically simulates the behavior of a rocket engine. Different parameters of the components of an engine is the input to these programs. Depending on these given parameters the programs output the behaviors of those components. These behavioral values are then used to guide the design of or to diagnose a model of a rocket engine "built" by a composition of these programs simulating different components of the engine system. In order to use this software package effectively one needs to have a flexible model of a rocket engine. These programs simulating different components then should be plugged into this modular representation. Our project is to develop an object based model of such an engine system. We are following an iterative and incremental approach in developing the model, as is the standard practice in the area of object oriented design and analysis of softwares. This process involves three stages: object modeling to represent the components and sub-components of a rocket engine, dynamic modeling to capture the temporal and behavioral aspects of the system, and functional modeling to represent the transformational aspects. This article reports on the first phase of our activity under a grant (RENS) from the NASA Lewis Research center. We have utilized Rambaugh's object modeling technique and the tool UML for this purpose. The classes of a rocket engine propulsion system are developed and some of them are presented in this report. The next step, developing a dynamic model for RENS, is also touched upon here. In this paper we will also discuss the advantages of using object-based modeling for developing this type of an integrated simulator over other tools like an expert systems shell or a procedural language, e.g., FORTRAN. Attempts have been made in the past to use such techniques.

  16. Query Based UML Modeling Validation and Verification of the System Model and Behavior for a

    E-print Network

    Austin, Mark

    for a Hydraulic Crane Denny Mathew ENPM 643 Instructor: Dr. Mark Austin #12;Systems Engineering Process for a Hydraulic Crane - Link Belt ATC 3200 - Requirements - Systems Structure - System Behavior - ConstraintsQuery Based UML Modeling Validation and Verification of the System Model and Behavior

  17. Creep rupture behavior of Stirling engine materials

    NASA Technical Reports Server (NTRS)

    Titran, R. H.; Scheuerman, C. M.; Stephens, J. R.

    1985-01-01

    The automotive Stirling engine, being investigated jointly by the Department of Energy and NASA Lewis as an alternate to the internal combustion engine, uses high-pressure hydrogen as the working fluid. The long-term effects of hydrogen on the high temperature strength properties of materials is relatively unknown. This is especially true for the newly developed low-cost iron base alloy NASAUT 4G-A1. This iron-base alloy when tested in air has creep-rupture strengths in the directionally solidified condition comparable to the cobalt base alloy HS-31. The equiaxed (investment cast) NASAUT 4G-A1 has superior creep-rupture to the equiaxed iron-base alloy XF-818 both in air and 15 MPa hydrogen.

  18. Parallel processor engine model program

    NASA Technical Reports Server (NTRS)

    Mclaughlin, P.

    1984-01-01

    The Parallel Processor Engine Model Program is a generalized engineering tool intended to aid in the design of parallel processing real-time simulations of turbofan engines. It is written in the FORTRAN programming language and executes as a subset of the SOAPP simulation system. Input/output and execution control are provided by SOAPP; however, the analysis, emulation and simulation functions are completely self-contained. A framework in which a wide variety of parallel processing architectures could be evaluated and tools with which the parallel implementation of a real-time simulation technique could be assessed are provided.

  19. Model-based Security Engineering

    E-print Network

    Jurjens, Jan

    Design Test plans Code Test results Field feedback Risk-based Security tests Static analysis (tools) Risk analysis Penetration testing Security breaks [McGraw 2003] Secure System Lifecycle Model-based Security2 1 Model-based Security Engineering Jan Jürjens Competence Center for IT Security Software

  20. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Flowers, George T.; Xie, Huajun; Sinha, S. C.

    1995-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness, and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  1. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    NASA Technical Reports Server (NTRS)

    Homaifar, Abdollah (editor); Kelly, John C., Jr. (editor); Flowers, G. T.; Xie, H.; Sinha, S. C.

    1994-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  2. Behavioral/Cognitive Engineered Deafness Reveals That Mouse Courtship

    E-print Network

    Rubel, Edwin

    Behavioral/Cognitive Engineered Deafness Reveals That Mouse Courtship Vocalizations Do Not Require features of each syllable type emitted by hearing and deaf males in the presence of a female. We found that almost all of the vocalization features we examined were similar in hearing and deaf animals

  3. Behavior of tissue-engineered human cartilage after transplantation into nude mice

    Microsoft Academic Search

    N. Rotter; J. Aigner; A. Naumann; C. Hammer; M. Sittinger

    1999-01-01

    Cartilage lacks the ability to regenerate structural defects. Therefore, autologous grafting has been used routinely to replace cartilaginous lesions. Because tissue engineering of human cartilage with the help of bioresorbable polymer scaffolds is possible in experimental models, the demand for the clinical application grows. In this study we present an analysis of the behavior of transplants made of human chondrocyte

  4. Conceptual Models for Search Engines

    NASA Astrophysics Data System (ADS)

    Hendry, D. G.; Efthimiadis, E. N.

    Search engines have entered popular culture. They touch people in diverse private and public settings and thus heighten the importance of such important social matters as information privacy and control, censorship, and equitable access. To fully benefit from search engines and to participate in debate about their merits, people necessarily appeal to their understandings for how they function. In this chapter we examine the conceptual understandings that people have of search engines by performing a content analysis on the sketches that 200 undergraduate and graduate students drew when asked to draw a sketch of how a search engine works. Analysis of the sketches reveals a diverse range of conceptual approaches, metaphors, representations, and misconceptions. On the whole, the conceptual models articulated by these students are simplistic. However, students with higher levels of academic achievement sketched more complete models. This research calls attention to the importance of improving students' technical knowledge of how search engines work so they can be better equipped to develop and advocate policies for how search engines should be embedded in, and restricted from, various private and public information settings.

  5. A behavioral stock market model

    Microsoft Academic Search

    László Gerencsér; Zalán Mátyás

    2008-01-01

    Stock exchanges are modeled as nonlinear closed-loop systems where the plant dynamics is defined by known stock market regulations\\u000a and the actions of agents are based on their beliefs and behavior. The decision of the agents may contain a random element,\\u000a thus we get a nonlinear stochastic feedback system. The market is in equilibrium when the actions of the agents

  6. Process Modeling (Engineering Statistics Handbook)

    NSDL National Science Digital Library

    Filliben, James

    Created by Alan Heckert and James Filliben, this chapter of the National Institute of Standard and Technology (NIST) Engineering Statistics handbook presents information on the statistical modeling of an engineering process. It contains an introduction, discussion of the assumptions, information about data collection and analysis, a discussion of what can be concluded from different process models, and case studies. This final section is quite interesting. It offers four different studies, they consist of: load cell output, the Alaskan Pipeline, ultrasonic reference block and the thermal expansion of copper. Once students go through the theories presented, the case studies allow them to apply this knowledge.

  7. Modeling and Prediction of Human Behavior

    Microsoft Academic Search

    Alex Pentland; Andrew Liu

    1999-01-01

    We propose that many human behaviors can be accurately described as a set of dynamic models (e.g., Kalman élters) sequenced together by a Markov chain. We then use these dynamic Markov models to recognize human behaviors from sensory data and to predict human behaviors over a few seconds time. To test the power of this modeling approach, we report an

  8. An evolutionary behavioral model for decision making

    Microsoft Academic Search

    Oscar Javier Romero López

    2011-01-01

    For autonomous agents the problem of deciding what to do next becomes increasingly complex when acting in unpredictable and dynamic environments while pursuing multiple and possibly conflicting goals. One of the most relevant behavior-based models that tries to deal with this problem is the behavior network model proposed by Maes. This model proposes a set of behaviors as purposive perception–action

  9. Teaching Behavioral Modeling and Simulation Techniques for Power Electronics Courses

    ERIC Educational Resources Information Center

    Abramovitz, A.

    2011-01-01

    This paper suggests a pedagogical approach to teaching the subject of behavioral modeling of switch-mode power electronics systems through simulation by general-purpose electronic circuit simulators. The methodology is oriented toward electrical engineering (EE) students at the undergraduate level, enrolled in courses such as "Power Electronics,"…

  10. Model-Driven Useware Engineering

    NASA Astrophysics Data System (ADS)

    Meixner, Gerrit; Seissler, Marc; Breiner, Kai

    User-oriented hardware and software development relies on a systematic development process based on a comprehensive analysis focusing on the users' requirements and preferences. Such a development process calls for the integration of numerous disciplines, from psychology and ergonomics to computer sciences and mechanical engineering. Hence, a correspondingly interdisciplinary team must be equipped with suitable software tools to allow it to handle the complexity of a multimodal and multi-device user interface development approach. An abstract, model-based development approach seems to be adequate for handling this complexity. This approach comprises different levels of abstraction requiring adequate tool support. Thus, in this chapter, we present the current state of our model-based software tool chain. We introduce the use model as the core model of our model-based process, transformation processes, and a model-based architecture, and we present different software tools that provide support for creating and maintaining the models or performing the necessary model transformations.

  11. NASA/DoD Aerospace Knowledge Diffusion Research Project. Paper 31: The information-seeking behavior of engineers

    NASA Technical Reports Server (NTRS)

    Pinelli, Thomas E.; Bishop, Ann P.; Barclay, Rebecca O.; Kennedy, John M.

    1993-01-01

    Engineers are an extraordinarily diverse group of professionals, but an attribute common to all engineers is their use of information. Engineering can be conceptualized as an information processing system that must deal with work-related uncertainty through patterns of technical communications. Throughout the process, data, information, and tacit knowledge are being acquired, produced, transferred, and utilized. While acknowledging that other models exist, we have chosen to view the information-seeking behavior of engineers within a conceptual framework of the engineer as an information processor. This article uses the chosen framework to discuss information-seeking behavior of engineers, reviewing selected literature and empirical studies from library and information science, management, communications, and sociology. The article concludes by proposing a research agenda designed to extend our current, limited knowledge of the way engineers process information.

  12. Some Measurement Issues Relating to Behavior Modeling.

    ERIC Educational Resources Information Center

    Fox, William M.

    Measurement issues relating to behavior modeling research are discussed. Researchers have successfully demonstrated the ability of behavior modeling to produce significant behavioral change in the training milieu, but have been less successful in showing the transfer of such change to everyday situations, a problem partially caused by measurement…

  13. Models of Attitude-Behavior Relations.

    ERIC Educational Resources Information Center

    Bentler, P. M.; Speckart, George

    1979-01-01

    Three replications of a structural equation model for the prediction of behavior are tested, using a questionnaire assessing undergraduate students' attitudes, subjective norms, intentions, and behavior. The proposed models supersede the Fishbein-Ajzen theory in their ability to reflect the dynamics of attitude-behavior relations. (Author/RD)

  14. Combining Behavior Models to Secure Email Systems

    Microsoft Academic Search

    Salvatore J. Stolfo; Chia-Wei Hu; Wei-Jen Li; Shlomo Hershkop; Ke Wang; Olivier Nimeskern

    2003-01-01

    We int roduce the Email Mining Toolkit (EMT), a system that implements behavior-based methods to improve security of email systems. Behavior models of email flows and email account usage may be used for a variety of detection tasks. Behavior-based models are quite different from \\

  15. Dependability Concerns in Model-Driven Engineering

    Microsoft Academic Search

    Leonardo Montecchi; Paolo Lollini; Andrea Bondavalli

    2011-01-01

    Model-Driven engineering (MDE) aims to elevate models in the engineering process to a central role in the speci- fication, design, integration, validation, and operation of a sys- tem. MDE is becoming a widely used approach within the de- pendability domain: the system, together with its main de- pendability-related characteristics, is represented by engineer- ing language models, while automatic transformations are

  16. Quantitative Modeling of Polymer Scratch Behavior

    E-print Network

    Hossain, Mohammad Motaher

    2013-12-02

    dependent mechanical behavior and pressure dependent frictional behavior in the FEM model, good agreement has been found between FEM simulation and experimental observations. The results suggest that, by including proper constitutive relationship...

  17. Prediction of Fuel Performance and Fission Gas Release Behavior during Normal Operation of the High Temperature Engineering Test Reactor by JAERI and FZJ Modeling Approach

    Microsoft Academic Search

    Kazuhiro SAWA; Shouhei UETA; Junya SUMITA; Karl VERFONDERN

    2001-01-01

    In high temperature gas-cooled reactors (HTGRs), coated fuel particles are employed as fuel to permit high outlet coolant temperature. The essential feature of HTGRs is the role of the coated fuel particles acting as tiny containment and the principal barrier against radionuclide release under any operational and accident condition. For a safe operation of the High Temperature Engineering Test Reactor

  18. Modeling of quality for engineering geodesy processes in civil engineering

    NASA Astrophysics Data System (ADS)

    Schweitzer, Jürgen; Schwieger, Volker

    2011-05-01

    Automation of processes, in combination with quality assurance, is an important development in civil engineering. One of the critical components of quality assurance relates to geometry. In order to determine and control geometric elements, measurement and evaluation processes of engineering geodesy must be integrated with construction processes. The quality of products and processes is a complex, multi-faceted field and this complexity is considered here by a new model that describes quality on the basis of characteristics and parameters. The model that has been developed for engineering geodesy processes in civil engineering has been applied to describe the quality of the geometry of a building.

  19. Thermodynamic modeling of pseudoternary phase behavior

    SciTech Connect

    Rossen, W.R.; Brown, R.G.; Davis, H.T.; Prager, S.; Scriven, L.E.

    1982-12-01

    Phase behavior is the fulcrum at which the chemistry and physics of surfactant and solvent systems govern the engineering and economics of chemical flooding. Salient behavior is represented by pseudoternary diagrams that account for polar, nonpolar, and amphiphilic components. The common 2, 3, 2, phase-split progression--induced, for example, by salinity change in microemulsion systems--is required by thermodynamic principles. Although such progressions can be simulated semiempirically, modeling them with a suitable free energy function or an equation of mixture state is more reliable for interpolating and extrapolating limited data on phase splits and coexisting phase compositions for use in mechanism-based computer simulation of laboratory experiments and field applications. Simple equations of mixture state prove inadequate but lead to the promising new linearly screened. FloryHuggins (LSFH) equation, which accounts for simultaneous association of amphiphile with oil and water and aggregation of surfactant amphiphile into curved sheetlike structures that separate water-rich from oil-rich regions. From this equation for a ternary mixture are calculated representative sets of diagrams with continuous progressions of tielines and binodals, plait points, tie-triangles, and three-phase regions with their critical endpoints. Several overlapping regions of metastable one- and two-phase equilibria are identified. Free-energy surfaces are pictured, and the free-energy factor that jointly controls interfacial tension (IFT) is computed. Ultralow tensions are favored by low-relief free-energy surfaces; so also are long-lived metastable states.

  20. Thermodynamic modeling of pseudoternary phase behavior

    SciTech Connect

    Rossen, W.R.; Brown, R.G.; Davis, H.T.; Prager, S.; Scriven, L.E.

    1982-12-01

    Phase behavior is the fulcrum at which the chemistry and physics of surfactant and solvent systems govern the engineering and economics of chemical flooding. Salient behavior is represented by pseudoternary diagrams that account for polar, nonpolar, and amphiphilic components. The common 2/sub -/, 3, 2/sup -/, phase-split progression--induced, for example, by salinity change in microemulsion systems--is required by thermodynamic principles. Although such progressions can be simulated semiempirically, modeling them with a suitable free energy function or an equation of mixture state is more reliable for interpolating and extrapolating limited data on phase splits and coexisting phase compositions for use in mechanism-based computer simulation of laboratory experiments and field applications. Simple equations of mixture state prove inadequate but lead to the promising new linearly screened FloryHuggins (LSFH) equation, which accounts for simultaneous association of amphiphile with oil and water and aggregation of surfactant amphiphile into curved sheetlike structures that separate water-rich from oil-rich regions.

  1. Model-based Security Engineering for Real

    E-print Network

    Jurjens, Jan

    2 1 Model-based Security Engineering for Real Jan Jürjens Competence Center for IT Security Software & Systems Engineering Informatics, Technical University Munich from 1 Oct: Open University, UK http://www4.in.tum.de/~juerjens Jan Jürjens, TU Munich: Model-based Security Engineering for Real 2

  2. Establishment of Computational Models for Clothing Engineering Design

    Microsoft Academic Search

    MAO AIHUA; WANG RUOMEI; Amo Aihua; Li Yi; Lou Xiaonan

    Clothing design achieved by engineering framework and method is a newly interest in the state of art of textile research, which may create many advantages, such as improving the design efficiency and strengthening the ability to consider more issues. The mathematical models describing the behind physical and chemical mechanisms of the involved various behaviors inside the textile materials and the

  3. Behavioral engineering: postural control by a portable operant apparatus1

    PubMed Central

    Azrin, N.; Rubin, H.; O'Brien, F.; Ayllon, T.; Roll, D.

    1968-01-01

    Recent studies suggested a general behavioral engineering approach to behavioral disorders by portable operant treatment instruments. The approach was applied to the problem of poor posture, specifically rounding of the back or slouching. An apparatus was developed that provided a warning stimulus followed by an aversive tone for the duration of slouching. Slouching was thereby punished by onset of the tone, and non-slouching was reinforced by tone termination and postponement. Twenty-five adults wore the apparatus during their normal working day during alternate periods in which the aversive tone was connected and disconnected experimentally. A miniature time-meter recorded the duration of slouching. The results showed that slouching decreased for each subject during each period in which slouching produced the aversive tone. For two subjects, a second control procedure was applied in which slouching terminated the tone. The result was an increase of slouching, demonstrating that the postural changes were controlled by the scheduled relation between the aversive tone and the response, and not by other factors such as simple response feedback. The substantial changes in posture indicate that the present procedure may prove to be an effective treatment alternative and suggests the general value of the behavioral engineering approach. PMID:16795176

  4. An explicative model of unsafe work behavior

    Microsoft Academic Search

    Dong-Chul Seo

    2005-01-01

    This study attempted to construct and test an explicative model of unsafe work behavior to reveal the mechanisms by which the following contributory factors to unsafe work behavior influence safety behaviors of individuals at workplaces: (a) perceived safety climate, (b) perceived hazard level, (c) perceived work pressure, (d) perceived risk, and (e) perceived barriers. Perceived safety climate was operationalized as

  5. Modeling the internal combustion engine

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

  6. Mathematical modeling of catalytic converter lightoff; Part II: model verification by engine-dynamometer experiments

    Microsoft Academic Search

    S. H. Oh; J. C. Cavendish

    1985-01-01

    A transient mathematical model has been developed which describes the behavior of packed-bed catalytic converters during warmup. Model predictions agree very well with the results of engine-dynamometer experiments for three Pt-alumina catalysts of widely different properties, thus demonstrating the validity of the model.

  7. Coupling of Mechanical Behavior of Cell Components to Electrochemical-Thermal Models for Computer-Aided Engineering of Batteries under Abuse (Presentation)

    SciTech Connect

    Pesaran, A.; Wierzbicki, T.; Sahraei, E.; Li, G.; Collins, L.; Sprague, M.; Kim, G. H.; Santhangopalan, S.

    2014-06-01

    The EV Everywhere Grand Challenge aims to produce plug-in electric vehicles as affordable and convenient for the American family as gasoline-powered vehicles by 2022. Among the requirements set by the challenge, electric vehicles must be as safe as conventional vehicles, and EV batteries must not lead to unsafe situations under abuse conditions. NREL's project started in October 2013, based on a proposal in response to the January 2013 DOE VTO FOA, with the goal of developing computer aided engineering tools to accelerate the development of safer lithium ion batteries.

  8. Modeling of a turbocharged SI engine

    Microsoft Academic Search

    Lars Eriksson; Lars Nielsen; Jan Brugård; Johan Bergström; Fredrik Pettersson; Per Andersson

    2002-01-01

    Turbocharged SI engines are a major possibility in the current trend of down-sized engines with preserved drivability performance. Considering control and supervision it is favorable to have a mean value model to be used e.g. in observer design. Such models of turbo engines are similar to those of naturally aspirated engines, but there are some special characteristics, e.g. the interconnected

  9. Clinician Search Behaviors May Be Influenced by Search Engine Design

    PubMed Central

    Coiera, Enrico; Zrimec, Tatjana; Compton, Paul

    2010-01-01

    Background Searching the Web for documents using information retrieval systems plays an important part in clinicians’ practice of evidence-based medicine. While much research focuses on the design of methods to retrieve documents, there has been little examination of the way different search engine capabilities influence clinician search behaviors. Objectives Previous studies have shown that use of task-based search engines allows for faster searches with no loss of decision accuracy compared with resource-based engines. We hypothesized that changes in search behaviors may explain these differences. Methods In all, 75 clinicians (44 doctors and 31 clinical nurse consultants) were randomized to use either a resource-based or a task-based version of a clinical information retrieval system to answer questions about 8 clinical scenarios in a controlled setting in a university computer laboratory. Clinicians using the resource-based system could select 1 of 6 resources, such as PubMed; clinicians using the task-based system could select 1 of 6 clinical tasks, such as diagnosis. Clinicians in both systems could reformulate search queries. System logs unobtrusively capturing clinicians’ interactions with the systems were coded and analyzed for clinicians’ search actions and query reformulation strategies. Results The most frequent search action of clinicians using the resource-based system was to explore a new resource with the same query, that is, these clinicians exhibited a “breadth-first” search behaviour. Of 1398 search actions, clinicians using the resource-based system conducted 401 (28.7%, 95% confidence interval [CI] 26.37-31.11) in this way. In contrast, the majority of clinicians using the task-based system exhibited a “depth-first” search behavior in which they reformulated query keywords while keeping to the same task profiles. Of 585 search actions conducted by clinicians using the task-based system, 379 (64.8%, 95% CI 60.83-68.55) were conducted in this way. Conclusions This study provides evidence that different search engine designs are associated with different user search behaviors. PMID:20601351

  10. Engine Structures Modeling Software System (ESMOSS)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Engine Structures Modeling Software System (ESMOSS) is the development of a specialized software system for the construction of geometric descriptive and discrete analytical models of engine parts, components, and substructures which can be transferred to finite element analysis programs such as NASTRAN. The NASA Lewis Engine Structures Program is concerned with the development of technology for the rational structural design and analysis of advanced gas turbine engines with emphasis on advanced structural analysis, structural dynamics, structural aspects of aeroelasticity, and life prediction. Fundamental and common to all of these developments is the need for geometric and analytical model descriptions at various engine assembly levels which are generated using ESMOSS.

  11. Modeling the mechanics of tissue-engineered human heart valve leaflets

    Microsoft Academic Search

    Niels J. B. Driessen; A Driessen-Mol; Carlijn V. C. Bouten; Frank P. T. Baaijens

    2005-01-01

    Mathematical models can provide valuable information to assess and evaluate the mechanical behavior of tissue-engineered constructs. In this study, a structurally based model is applied to describe and analyze the mechanics of tissue-engineered human heart valve leaflets. The results from two orthogonal uniaxial tensile tests are used to determine the model parameters of the constructs after two, three and four

  12. Progress toward life modeling of thermal barrier coatings for aircraft gas turbine engines

    NASA Technical Reports Server (NTRS)

    Miller, R. A.

    1987-01-01

    Progress toward developing life models for simulating the behavior of thermal barrier coatings in aircraffft gas turbine engines is discussed. A preliminary laboratory model is described as are current efforts to develop engine-capable models. Current understanding of failure mechanisms is also summarized.

  13. The Limits of Phenomenology: From Behaviorism to Drug Testing and Engineering Design

    E-print Network

    Bar-Yam, Yaneer

    2013-01-01

    It is widely believed that theory is useful in physics because it describes simple systems and that strictly empirical phenomenological approaches are necessary for complex biological and social systems. Here we prove based upon an analysis of the information that can be obtained from experimental observations that theory is even more essential in the understanding of complex systems. Implications of this proof revise the general understanding of how we can understand complex systems including the behaviorist approach to human behavior, problems with testing engineered systems, and medical experimentation for evaluating treatments and the FDA approval of medications. Each of these approaches are inherently limited in their ability to characterize real world systems due to the large number of conditions that can affect their behavior. Models are necessary as they can help to characterize behavior without requiring observations for all possible conditions. The testing of models by empirical observations enhance...

  14. Modeling Driver Behavior in a Cognitive Architecture

    Microsoft Academic Search

    Dario D. Salvucci

    2006-01-01

    Objective: This paper explores the development of a rigorous computational model of driver behavior in a cognitive architecture--a computational framework with underlying psychological theories that incorporate basic properties and limitations of the human system. Background: Computational modeling has emerged as a powerful tool for studying the complex task of driving, allowing researchers to simulate driver behavior and explore the parameters

  15. Algorithms for Reverse Engineering Boundary Representation Models

    E-print Network

    Martin, Ralph R.

    by CAD/CAM systems. There is a wide diversity of reverse engineering methods for converting measured data CAD/CAM sys- tems. The current situation in reverse engineering is somewhat similar. For free of these cannot directly be applied to building CAD/CAM models for mechanical engineering. Some produce fair

  16. An engineering model for coal devolatilization

    SciTech Connect

    Lau, Chun Wei; Niksa, S.

    1991-02-01

    There are three different modeling projects in this program: (1) an expedient reaction model for coal devolatilization for large scale combustor simulators; (2) a theoretical framework to explain the behavior of different coal types; and (3) an analysis of the chemistry, heat and mass transport in the vicinity of individual coal particles, to begin to describe the initial stages of the combustion of entrained coal particles. The engineering model, called FLASHTWO, was developed before this program began, and has been validated against several wire-grid studies of HVA bituminous coals. Parameters for FLASHTWO for various coal types have been assigned to reproduce the predictions from the full depolymerization model developed in Task 2, and used in the simulations of the initial stages of pulverized coal combustion in Task 3. A depolymerization model has been developed which rationalizes all aspects of coal type effects on rapid coal devolatilization. The theory is called FLASHCHAIN. Task 3, the analysis of the initial stages of pulverized coal combustion, was pursued in two stages. One study omits homogenous chemistry entirely, and focuses on the transport analysis including primary devolatilization, convective heat and mass transport, heterogeneous oxidation at the particle surface. The second study illustrates volatiles combustion in the limit of diffusion-limited combustion rates. This rate analysis if formulated in terms or primary devolatilization, convective heat and mass transport, homogeneous combustion of tar and noncendensibles in a flame sheet, and heterogeneous oxidation at the particle surface.

  17. An engineering model for coal devolatilization

    SciTech Connect

    Lau, Chun Wei; Niksa, S.

    1989-11-01

    There are three distinct modeling projects in this program: (1) an expedient reaction model for coal devolatilization for large scale combustor simulators; (2) a theoretical framework to explain the behavior of different coal types; and (3) an analysis of the chemistry, heat and mass transport in the vicinity of individual coal particles, to begin to describe the initial stages of the combustion of entrained coal particles. The engineering model was developed before this program began, and has now been validated against several wire-grid studies of HVA bituminous coals. The transport analysis of devolatilizing and oxidizing coal particles, a two-component devolatilization model which resolves tar and noncondensibles was supplemented with a single heterogeneous combustion reaction at the particle surface. A transport analysis of the initial stages of pulverized coal combustion is formulated in terms of primary devolatilization, convective heat and mass transport, and heterogeneous oxidation at the particle surface. No homogeneous chemistry is included. Consequently this study aims to clarify the impact of the outward flux of volatiles on the heterogeneous ignition of individual coal particles. Primary devolatilization is represented by FLASHTWO, a recent model which predicts the yields and evolution rates of tar and a single noncondensible gaseous product, as well as the molecular weight distribution of tar. The transport analysis also includes oxygen and inert gas. Oxidation at the particle surface is described with a single nth-order global reaction, and the exotherm for CO production. 12 refs., 12 figs., 2 tabs.

  18. Models of motivation in software engineering

    Microsoft Academic Search

    Helen Sharp; Nathan Baddoo; Sarah Beecham; Tracy Hall; Hugh Robinson

    2009-01-01

    Motivation in software engineering is recognized as a key success factor for software projects, but although there are many papers written about motivation in software engineering, the field lacks a comprehensive overview of the area. In particular, several models of motivation have been proposed, but they either rely heavily on one particular model (the job characteristics model), or are quite

  19. Simulation Model Driven Engineering for Manufacturing Cell

    E-print Network

    Paris-Sud XI, Université de

    Simulation Model Driven Engineering for Manufacturing Cell Hironori Hibino1 , Toshihiro Inukai2 Abstract. In our research, the simulation model driven engineering for manufacturing cell (SMDE on the simulation model and to extend the range of control applications and simulation applications using the PC

  20. Modeling and simulation: tools for metabolic engineering

    Microsoft Academic Search

    Wolfgang Wiechert

    2002-01-01

    Mathematical modeling is one of the key methodologies of metabolic engineering. Based on a given metabolic model different computational tools for the simulation, data evaluation, systems analysis, prediction, design and optimization of metabolic systems have been developed. The currently used metabolic modeling approaches can be subdivided into structural models, stoichiometric models, carbon flux models, stationary and nonstationary mechanistic models and

  1. Applying the Health Belief Model to college students' health behavior

    PubMed Central

    Kim, Hak-Seon; Ahn, Joo

    2012-01-01

    The purpose of this research was to investigate how university students' nutrition beliefs influence their health behavioral intention. This study used an online survey engine (Qulatrics.com) to collect data from college students. Out of 253 questionnaires collected, 251 questionnaires (99.2%) were used for the statistical analysis. Confirmatory Factor Analysis (CFA) revealed that six dimensions, "Nutrition Confidence," "Susceptibility," "Severity," "Barrier," "Benefit," "Behavioral Intention to Eat Healthy Food," and "Behavioral Intention to do Physical Activity," had construct validity; Cronbach's alpha coefficient and composite reliabilities were tested for item reliability. The results validate that objective nutrition knowledge was a good predictor of college students' nutrition confidence. The results also clearly showed that two direct measures were significant predictors of behavioral intentions as hypothesized. Perceived benefit of eating healthy food and perceived barrier for eat healthy food to had significant effects on Behavioral Intentions and was a valid measurement to use to determine Behavioral Intentions. These findings can enhance the extant literature on the universal applicability of the model and serve as useful references for further investigations of the validity of the model within other health care or foodservice settings and for other health behavioral categories. PMID:23346306

  2. Integrated behavior models for factory automation systems

    Microsoft Academic Search

    Jewgenij Botaschanjan; Benjamin Hummel; Thomas Hensel; Alexander Lindworsky

    2009-01-01

    Despite the large amount of models for different aspects of factory automation systems, many of these models target at individual and in most cases static aspects of the system, such as the geometry or its electric parts. There is a lack of suitable description methods, which integrate these individual models to a behavior model including spatial aspects and the handling

  3. Modeling Collaborative Behavior: Foundations for Collaboration Technologies

    Microsoft Academic Search

    Steven E. Poltrock; Mark Handel

    2009-01-01

    Can models of collaboration serve as a foundation for development of collaborative technologies in much the same way that engineers use models when developing complex systems? We explore this issue by investigating how eight approaches to understanding or modeling collaboration could be used to improve technologies that support a change management process. Some approaches are ostensive, defining how collaboration should

  4. Financial Models for Integrated Behavioral Health Care

    Microsoft Academic Search

    Blake Chaffee

    Integrated behavioral health care or “integrated care” is a distinct service delivery model aimed at early identification and appropriate intervention with that portion of medical\\/surgical patients presenting with behavioral health issues. The clinical rationale for integrated care and the potential for medical cost offset savings have been clearly substantiated in available research (Cummings, 2007; O’Donohue, Ferguson & Cummings, 2002), but

  5. Modeling Ant Behavior Under a Variable Environment

    E-print Network

    Theraulaz, Guy

    Modeling Ant Behavior Under a Variable Environment Karla Vittori1 , Jacques Gautrais2 , Aluizio F.61.55.67.31, Fax: (033) 5.61.55. 61.54 theraula@cict.fr Abstract. This paper studies the behavior of ants when source. The ant responses when temporarily blocking the access to some branches of the maze were observed

  6. Optimization of a model internal combustion engine

    Microsoft Academic Search

    Boris M. Aizenbud; Yehuda B. Band; Oded Kafri

    1982-01-01

    We optimize the operating conditions of a model internal combustion engine to obtain maximal efficiency. The model engine consists of a cylinder equipped with a piston containing a working fluid, coupled to a heat bath and heated by internal combustion with a rate of heating that is very weakly dependent on the temperature and pressure of the working fluid. We

  7. Applied Mathematics and Computational Modeling in Engineering

    Microsoft Academic Search

    Zuzana Krivá; Karol Mikula

    In many countries of European community, USA, Japan etc., study programs entitled Technomathematik, Applied and computational mathematics, Computational science and engineering, Scientific computing or Mathematical and computational modeling can be studied. All these names try to characterize a connection of applied mathematics, computational modeling and scientific, engineering and\\/or economic applications. Two years ago, a new study program Mathematical and computational

  8. A crankshaft system model for structural dynamic analysis of internal combustion engines

    Microsoft Academic Search

    Zissimos P. Mourelatos

    2001-01-01

    A system model for analyzing the dynamic behavior of an internal combustion engine crankshaft is described. The model couples the crankshaft structural dynamics, the main bearing hydrodynamic lubrication and the engine block stiffness using a system approach. A two-level dynamic substructuring technique is used to predict the crankshaft dynamic response based on the finite-element method. The dynamic substructuring uses a

  9. Cognitive engineering models in space systems

    NASA Technical Reports Server (NTRS)

    Mitchell, Christine M.

    1993-01-01

    NASA space systems, including mission operations on the ground and in space, are complex, dynamic, predominantly automated systems in which the human operator is a supervisory controller. Models of cognitive functions in complex systems are needed to describe human performance and form the theoretical basis of operator workstation design, including displays, controls, and decision aids. Currently, there several candidate modeling methodologies. They include the Rasmussen abstraction/aggregation hierarchy and decision ladder, the goal-means network, the problem behavior graph, and the operator function model. The research conducted under the sponsorship of this grant focuses on the extension of the theoretical structure of the operator function model and its application to NASA Johnson mission operations and space station applications. The initial portion of this research consists of two parts. The first is a series of technical exchanges between NASA Johnson and Georgia Tech researchers. The purpose is to identify candidate applications for the current operator function model; prospects include mission operations and the Data Management System Testbed. The second portion will address extensions of the operator function model to tailor it to the specific needs of Johnson applications. At this point, we have accomplished two things. During a series of conversations with JSC researchers, we have defined the technical goal of the research supported by this grant to be the structural definition of the operator function model and its computer implementation, OFMspert. Both the OFM and OFMspert have matured to the point that they require infrastructure to facilitate use by researchers not involved in the evolution of the tools. The second accomplishment this year was the identification of the Payload Deployment and Retrieval System (PDRS) as a candidate system for the case study. In conjunction with government and contractor personnel in the Human-Computer Interaction Lab, the PDRS was identified as the most accessible system for the demonstration. Pursuant to this a PDRS simulation was obtained from the HCIL and an initial knowledge engineering effort was conducted to understand the operator's tasks in the PDRS application. The preliminary results of the knowledge engineering effort and an initial formulation of an operator function model (OFM) are contained in the appendices.

  10. Micromechanical modeling of rough interface behavior

    E-print Network

    Huang, Shiping

    2011-07-28

    In this dissertation, the interface behavior of contacting rough surfaces was studied systematically based upon micromechanical modeling. Firstly, asperity contact mechanics was further developed. It was found that tangential tractions, displacement...

  11. Sociobiology (I): Models of Social Behavior

    ERIC Educational Resources Information Center

    Kolata, Gina Bari

    1975-01-01

    Presents models that ascribe social behavior, such as altruism and parental sacrifices for the young, to a kind of genetic imperative wherein individuals maximize their genetic contribution to the next generation. (GS)

  12. A new technique for thermodynamic engine modeling

    NASA Astrophysics Data System (ADS)

    Matthews, R. D.; Peters, J. E.; Beckel, S. A.; Shizhi, M.

    1983-12-01

    Reference is made to the equations given by Matthews (1983) for piston engine performance, which show that this performance depends on four fundamental engine efficiencies (combustion, thermodynamic cycle or indicated thermal, volumetric, and mechanical) as well as on engine operation and design parameters. This set of equations is seen to suggest a different technique for engine modeling; that is, that each efficiency should be modeled individually and the efficiency submodels then combined to obtain an overall engine model. A simple method for predicting the combustion efficiency of piston engines is therefore required. Various methods are proposed here and compared with experimental results. These combustion efficiency models are then combined with various models for the volumetric, mechanical, and indicated thermal efficiencies to yield three different engine models of varying degrees of sophistication. Comparisons are then made of the predictions of the resulting engine models with experimental data. It is found that combustion efficiency is almost independent of load, speed, and compression ratio and is not strongly dependent on fuel type, at least so long as the hydrogen-to-carbon ratio is reasonably close to that for isooctane.

  13. CONFIG: Qualitative simulation tool for analyzing behavior of engineering devices

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.; Basham, Bryan D.; Harris, Richard A.

    1987-01-01

    To design failure management expert systems, engineers mentally analyze the effects of failures and procedures as they propagate through device configurations. CONFIG is a generic device modeling tool for use in discrete event simulation, to support such analyses. CONFIG permits graphical modeling of device configurations and qualitative specification of local operating modes of device components. Computation requirements are reduced by focussing the level of component description on operating modes and failure modes, and specifying qualitative ranges of variables relative to mode transition boundaries. Simulation processing occurs only when modes change or variables cross qualitative boundaries. Device models are built graphically, using components from libraries. Components are connected at ports by graphical relations that define data flow. The core of a component model is its state transition diagram, which specifies modes of operation and transitions among them.

  14. Cognitive Architectures for Modeling Driver Behavior

    Microsoft Academic Search

    Dario D. Salvucci

    Abstract The Problem. The driving task involves a host of relevant cognitive, perceptual, and motor abilities. Cognitive architectures—frameworks,for modeling human,cognition and behavior—have evolved to integrate known,theories of human cognition into unified theories that account for a wide range of cognitive phenomena. Role of Driving Simulators. Models of driver behavior based on cognitive architectures can be linked into driving simulators to

  15. A systemic model of doping behavior.

    PubMed

    Johnson, Michael B

    2011-01-01

    Human behavior occurs within a system, and as such, so do behaviors in performance-related domains (e.g., athletics, academics). Doping is a performance enhancement behavior that can be problematic because of the negative physical and psychological effects associated with the use of some substances and the common argument that doping is unfair. However, doping continues and may be increasing. Because a firm theoretical or empirical understanding of doping does not exist, this article proposes a conceptual, comprehensive, and innovative systemic model of doping behavior. The model is built from relevant empiricism supporting the idea that contemporary doping behavior is a function of systemic transactions between historical doping practices, the present environment, current antidoping interventions, one's genetic makeup, developmental milestones, social factors, and epigenetics. PMID:21834401

  16. A behavioral two?sex marriage model

    Microsoft Academic Search

    John K. Dagsvik; Helge Brunborg; Ane S. Flaatten

    2001-01-01

    In this paper we propose a particular marriage model, i.e., a model for the number of marriages for each age combination as a function of the vectors of the number of single men and women in each age group. The model is based on Dagsvik (2000) where it is demonstrated that a general type of matching behavior imply, under specific

  17. URGENT DRIVER BEHAVIOR MODELING IN COGNITIVE ARCHITECTURE

    Microsoft Academic Search

    YANFEI LIU; ZHAOHUI WU

    The paper construct the driver behavior model in cognitive architecture of the urgent circumstance based on ACT-R theory, it strive to delineate the cognitive procedure of the driver's motor under urgent situation, and find the key cognitive factors of traffic accident avoidance, and then applying the model to the driver's training and instruction, and in the end the modeling method

  18. Structural equation modeling for travel behavior research

    Microsoft Academic Search

    Thomas F. Golob

    2003-01-01

    Structural equation modeling (SEM) is an extremely flexible linear-in-parameters multivariate statistical modeling technique. It has been used in modeling travel behavior and values since about 1980, and its use is rapidly accelerating, partially due to the availability of improved software. The number of published studies, now known to be more than 50, has approximately doubled in the past three years.

  19. Modeling Off-Nominal Behavior in SysML

    NASA Technical Reports Server (NTRS)

    Day, John; Donahue, Kenny; Ingham, Mitch; Kadesch, Alex; Kennedy, Kit; Post, Ethan

    2012-01-01

    Fault Management is an essential part of the system engineering process that is limited in its effectiveness by the ad hoc nature of the applied approaches and methods. Providing a rigorous way to develop and describe off-nominal behavior is a necessary step in the improvement of fault management, and as a result, will enable safe, reliable and available systems even as system complexity increases... The basic concepts described in this paper provide a foundation to build a larger set of necessary concepts and relationships for precise modeling of off-nominal behavior, and a basis for incorporating these ideas into the overall systems engineering process.. The simple FMEA example provided applies the modeling patterns we have developed and illustrates how the information in the model can be used to reason about the system and derive typical fault management artifacts.. A key insight from the FMEA work was the utility of defining failure modes as the "inverse of intent", and deriving this from the behavior models.. Additional work is planned to extend these ideas and capabilities to other types of relevant information and additional products.

  20. Information Needs and Information-Gathering Behavior of Research Engineers.

    ERIC Educational Resources Information Center

    Siess, Judith A.

    Research into both the information needs of engineers engaged in research and development, and the means chosen by engineers to fulfill their information needs are summarized in this condensation of a Master's thesis. Parallel questionnaires were administered in 1981 to 78 engineers at the U.S. Army Corps of Engineers Construction Engineering

  1. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHTI multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  2. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHT multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  3. Hierarchical representation and machine learning from faulty jet engine behavioral examples to detect real time abnormal conditions

    NASA Technical Reports Server (NTRS)

    Gupta, U. K.; Ali, M.

    1988-01-01

    The theoretical basis and operation of LEBEX, a machine-learning system for jet-engine performance monitoring, are described. The behavior of the engine is modeled in terms of four parameters (the rotational speeds of the high- and low-speed sections and the exhaust and combustion temperatures), and parameter variations indicating malfunction are transformed into structural representations involving instances and events. LEBEX extracts descriptors from a set of training data on normal and faulty engines, represents them hierarchically in a knowledge base, and uses them to diagnose and predict faults on a real-time basis. Diagrams of the system architecture and printouts of typical results are shown.

  4. Tissue Engineering Approaches for Studying the Effect of Biochemical and Physiological Stimuli on Cell Behavior 

    E-print Network

    Jimenez Vergara, Andrea

    2012-10-19

    TISSUE ENGINEERING APPROACHES FOR STUDYING THE EFFECT OF BIOCHEMICAL AND PHYSIOLOGICAL STIMULI ON CELL BEHAVIOR A Dissertation by ANDREA CAROLINA JIMENEZ VERGARA Submitted to the Office of Graduate Studies of Texas A... the Effect of Biochemical and Physiological Stimuli on Cell Behavior Copyright August 2012 Andrea Carolina Jimenez Vergara TISSUE ENGINEERING APPROACHES FOR STUDYING THE EFFECT OF BIOCHEMICAL AND PHYSIOLOGICAL STIMULI ON CELL BEHAVIOR A Dissertation...

  5. Combustion Modeling in Internal Combustion Engines

    Microsoft Academic Search

    FRANK J. ZELEZNIK

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to

  6. Engineering of Framework-Specific Modeling Languages

    Microsoft Academic Search

    Michal Antkiewicz; Krzysztof Czarnecki; Matthew Stephan

    2009-01-01

    Framework-specific modeling languages (FSMLs) help developers build applications based on object-oriented frameworks. FSMLs model abstractions and rules of application programming interfaces (APIs) exposed by frameworks and can express models of how applications use APIs. Such models aid developers in understanding, creating, and evolving application code. We present four exemplar FSMLs and a method for engineering new FSMLs. The method was

  7. Consistency Stability, Convergence Of Stirling Engine Models

    Microsoft Academic Search

    L. Bauwans

    1990-01-01

    Stirling engine modeling can be diided into two main steps. First, an idealization of the engine that can be translated into a complete and unique mathematical problem must be chosen. Then, a computer code that provides a numerical, approximate solution to that problem must be written. The solution Is meaningful if the error due to its approximate nature can be

  8. Reverse Engineering Goal Models from Legacy Code

    Microsoft Academic Search

    Yijun Yu; Yiqiao Wang; John Mylopoulos; Sotirios Liaskos; Alexei Lapouchnian; Julio Cesar Sampaio Do Prado Leite

    2005-01-01

    A reverse engineering process aims at reconstructing high-level abstractions from source code. This paper presents a novel reverse engineering methodology for re- covering stakeholder goal models from both structured and unstructured legacy code. The methodology consists of the following major steps: 1) Refactoring source code by extracting methods based on comments; 2) Convert- ing the refactored code into an abstract

  9. Model-based Security Engineering Jan Jurjens

    E-print Network

    Jurjens, Jan

    Model-based Security Engineering (Keynote) Jan J¨urjens Software & Systems Engineering Dep. of Informatics, TU Munich, Germany http://www4.in.tum.de/~juerjens Abstract The current state of the art in security-critical software is far from sat- isfactory: New security vulnerabilities are discovered

  10. Neurobiological constraints on behavioral models of motivation.

    PubMed

    Nader, K; Bechara, A; van der Kooy, D

    1997-01-01

    The application of neurobiological tools to behavioral questions has produced a number of working models of the mechanisms mediating the rewarding and aversive properties of stimuli. The authors review and compare three models that differ in the nature and number of the processes identified. The dopamine hypothesis, a single system model, posits that the neurotransmitter dopamine plays a fundamental role in mediating the rewarding properties of all classes of stimuli. In contrast, both nondeprived/deprived and saliency attribution models claim that separate systems make independent contributions to reward. The former identifies the psychological boundary defined by the two systems as being between states of nondeprivation (e.g. food sated) and deprivation (e.g. hunger). The latter identifies a boundary between liking and wanting systems. Neurobiological dissociations provide tests of and explanatory power for behavioral theories of goal-directed behavior. PMID:9046556

  11. Models of iodine behavior in reactor containments

    SciTech Connect

    Weber, C.F.; Beahm, E.C.; Kress, T.S.

    1992-10-01

    Models are developed for many phenomena of interest concerning iodine behavior in reactor containments during severe accidents. Processes include speciation in both gas and liquid phases, reactions with surfaces, airborne aerosols, and other materials, and gas-liquid interface behavior. Although some models are largely empirical formulations, every effort has been made to construct mechanistic and rigorous descriptions of relevant chemical processes. All are based on actual experimental data generated at the Oak Ridge National Laboratory (ORNL) or elsewhere, and, hence, considerable data evaluation and parameter estimation are contained in this study. No application or encoding is attempted, but each model is stated in terms of rate processes, with the intention of allowing mechanistic simulation. Taken together, this collection of models represents a best estimate iodine behavior and transport in reactor accidents.

  12. Behavior of shell-model configuration moments

    E-print Network

    Edgar Teran; Calvin W. Johnson

    2005-08-22

    An important input into reaction theory is the density of states or the level density. Spectral distribution theory (also known as nuclear statistical spectroscopy) characterizes the secular behavior of the density of states through moments of the Hamiltonian. One particular approach is to partition the model space into subspaces and find the moments in those subspaces; a convenient choice of subspaces are spherical shell-model configurations. We revisit these configuration moments and find, for complete $0\\hbar\\omega$ many-body spaces, the following behaviors: (a) the configuration width is nearly constant for all configurations; (b) the configuration asymmetry or third moment is strongly correlated with the configuration centroid; (c) the configuration fourth moment, or excess is linearly related to the square to the configuration asymmetry. Such universal behavior may allow for more efficient modeling of the density of states in a shell-model framework.

  13. Laser docking sensor engineering model

    NASA Technical Reports Server (NTRS)

    Dekome, Kent; Barr, Joseph M.

    1991-01-01

    NASA JSC has been involved in the development of Laser sensors for the past ten years in order to support future rendezvous and docking missions, both manned and unmanned. Although many candidate technologies have been breadboarded and evaluated, no sensor hardware designed specifically for rendezvous and docking applications has been demonstrated on-orbit. It has become apparent that representative sensors need to be flown and demonstrated as soon as possible, with minimal cost, to provide the capability of the technology in meeting NASA's future AR&C applications. Technology and commercial component reliability have progressed to where it is now feasible to fly hardware as a detailed test objective minimizing the overall cost and development time. This presentation will discuss the ongoing effort to convert an existing in-house developed breadboard to an engineering model configuration suitable for flight. The modifications include improving the ranger resolution and stability with an in-house design, replacing the rack mounted galvanometric scanner drivers with STD-bus cards, replacing the system controlling personal computer with a microcontroller, and repackaging the subsystems as appropriate. The sensor will use the performance parameters defined in previous JSC requirements working groups as design goals and be built to withstand the space environment where fiscally feasible. Testing of the in-house ranger design is expected to be completed in October. The results will be included in the presentation. Preliminary testing of the ranging circuitry indicates a range resolution of 4mm is possible. The sensor will be mounted in the payload bay on a shelf bracket and have command, control, and display capabilities using the payload general support computer via an RS422 data line.

  14. Modeling behavioral considerations related to information security.

    SciTech Connect

    Martinez-Moyano, I. J.; Conrad, S. H.; Andersen, D. F. (Decision and Information Sciences); (SNL); (Univ. at Albany)

    2011-01-01

    The authors present experimental and simulation results of an outcome-based learning model for the identification of threats to security systems. This model integrates judgment, decision-making, and learning theories to provide a unified framework for the behavioral study of upcoming threats.

  15. Systems engineering in the Large Synoptic Survey Telescope project: an application of model based systems engineering

    NASA Astrophysics Data System (ADS)

    Claver, C. F.; Selvy, Brian M.; Angeli, George; Delgado, Francisco; Dubois-Felsmann, Gregory; Hascall, Patrick; Lotz, Paul; Marshall, Stuart; Schumacher, German; Sebag, Jacques

    2014-08-01

    The Large Synoptic Survey Telescope project was an early adopter of SysML and Model Based Systems Engineering practices. The LSST project began using MBSE for requirements engineering beginning in 2006 shortly after the initial release of the first SysML standard. Out of this early work the LSST's MBSE effort has grown to include system requirements, operational use cases, physical system definition, interfaces, and system states along with behavior sequences and activities. In this paper we describe our approach and methodology for cross-linking these system elements over the three classical systems engineering domains - requirement, functional and physical - into the LSST System Architecture model. We also show how this model is used as the central element to the overall project systems engineering effort. More recently we have begun to use the cross-linked modeled system architecture to develop and plan the system verification and test process. In presenting this work we also describe "lessons learned" from several missteps the project has had with MBSE. Lastly, we conclude by summarizing the overall status of the LSST's System Architecture model and our plans for the future as the LSST heads toward construction.

  16. Thrust modeling for hypersonic engines

    NASA Technical Reports Server (NTRS)

    Riggins, D. W.; Mcclinton, C. R.

    1995-01-01

    Expressions for the thrust losses of a scramjet engine are developed in terms of irreversible entropy increases and the degree of incomplete combustion. A method is developed which allows the calculation of the lost vehicle thrust due to different loss mechanisms within a given flow-field. This analysis demonstrates clearly the trade-off between mixing enhancement and resultant increased flow losses in scramjet combustors. An engine effectiveness parameter is defined in terms of thrust loss. Exergy and the thrust-potential method are related and compared.

  17. Emergent collective decision-making: Control, model and behavior

    NASA Astrophysics Data System (ADS)

    Shen, Tian

    In this dissertation we study emergent collective decision-making in social groups with time-varying interactions and heterogeneously informed individuals. First we analyze a nonlinear dynamical systems model motivated by animal collective motion with heterogeneously informed subpopulations, to examine the role of uninformed individuals. We find through formal analysis that adding uninformed individuals in a group increases the likelihood of a collective decision. Secondly, we propose a model for human shared decision-making with continuous-time feedback and where individuals have little information about the true preferences of other group members. We study model equilibria using bifurcation analysis to understand how the model predicts decisions based on the critical threshold parameters that represent an individual's tradeoff between social and environmental influences. Thirdly, we analyze continuous-time data of pairs of human subjects performing an experimental shared tracking task using our second proposed model in order to understand transient behavior and the decision-making process. We fit the model to data and show that it reproduces a wide range of human behaviors surprisingly well, suggesting that the model may have captured the mechanisms of observed behaviors. Finally, we study human behavior from a game-theoretic perspective by modeling the aforementioned tracking task as a repeated game with incomplete information. We show that the majority of the players are able to converge to playing Nash equilibrium strategies. We then suggest with simulations that the mean field evolution of strategies in the population resemble replicator dynamics, indicating that the individual strategies may be myopic. Decisions form the basis of control and problems involving deciding collectively between alternatives are ubiquitous in nature and in engineering. Understanding how multi-agent systems make decisions among alternatives also provides insight for designing decentralized control laws for engineering applications from mobile sensor networks for environmental monitoring to collective construction robots. With this dissertation we hope to provide additional methodology and mathematical models for understanding the behavior and control of collective decision-making in multi-agent systems.

  18. Animal models of restricted repetitive behavior in autism

    Microsoft Academic Search

    Mark H. Lewis; Yoko Tanimura; Linda W. Lee; James W. Bodfish

    2007-01-01

    Restricted, repetitive behavior, along with deficits in social reciprocity and communication, is diagnostic of autism. Animal models relevant to this domain generally fall into three classes: repetitive behavior associated with targeted insults to the CNS; repetitive behavior induced by pharmacological agents; and repetitive behavior associated with restricted environments and experience. The extant literature provides potential models of the repetitive behavioral

  19. Combustion modeling in internal combustion engines

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to be significant in the applications of the model.

  20. Psychological Models of Engineering Careers.

    ERIC Educational Resources Information Center

    Winer, Jane L.; And Others

    An interdisciplinary effort by Texas Tech University to help undergraduate civil engineering students make better-informed occupational choices is the subject of this paper. The theoretical and empirical bases of the project, which is designed to improve counseling of freshmen students for both inter- and intra-occupational decision making, are…

  1. Adaptive human behavior in epidemiological models

    PubMed Central

    Fenichel, Eli P.; Castillo-Chavez, Carlos; Ceddia, M. G.; Chowell, Gerardo; Parra, Paula A. Gonzalez; Hickling, Graham J.; Holloway, Garth; Horan, Richard; Morin, Benjamin; Perrings, Charles; Springborn, Michael; Velazquez, Leticia; Villalobos, Cristina

    2011-01-01

    The science and management of infectious disease are entering a new stage. Increasingly public policy to manage epidemics focuses on motivating people, through social distancing policies, to alter their behavior to reduce contacts and reduce public disease risk. Person-to-person contacts drive human disease dynamics. People value such contacts and are willing to accept some disease risk to gain contact-related benefits. The cost–benefit trade-offs that shape contact behavior, and hence the course of epidemics, are often only implicitly incorporated in epidemiological models. This approach creates difficulty in parsing out the effects of adaptive behavior. We use an epidemiological–economic model of disease dynamics to explicitly model the trade-offs that drive person-to-person contact decisions. Results indicate that including adaptive human behavior significantly changes the predicted course of epidemics and that this inclusion has implications for parameter estimation and interpretation and for the development of social distancing policies. Acknowledging adaptive behavior requires a shift in thinking about epidemiological processes and parameters. PMID:21444809

  2. Impact fracture behavior of model system modified polypropylene

    E-print Network

    Estrada, Albert Jesse

    2000-01-01

    magnification of crack tip region in b, and (f) ind. 76 5. 9 SEM micrographs for 90% PP copolymer/10% EOR blend: (a-b) pacted at O'C and (c-d) impacted at room temperature. (a, c) taken near the crack tip. (b, d) taken away fi om the crack tip. Crack... OF SCIENCE December 2000 Major Subject: Mechanical Engineering IMPACT FRACTURE BEHAVIOR OF MODEL SYSTEM MODIFIED POLYPROPYLENE A Thesis by ALBERT JESSE ESTRADA Submitted to the Office of Graduate Studies of Texas A&M University in partial...

  3. Modeling of Agent Behavior Using Behavioral Specifications Alexei Sharpanskykh (sharp@few.vu.nl)

    E-print Network

    Treur, Jan

    used for modeling relatively simple types of behavior (e.g., stimulus- response behavior (Hunter, 1912; Skinner, 1935)). For less simple types of behavior (e.g., adaptive behavior based on conditioning states of the agent, based on which an externally observable behavioral pattern is generated

  4. Modified Linear Parameter Varying modeling for turbofan engine

    Microsoft Academic Search

    Li Shu-qing; Zhang Sheng-xiu

    2010-01-01

    A modified LPV (Linear Parameter Varying) modeling method for nonlinear system was put forward and is applied in modeling a turbofan engine system. First, a quasi-LPV model of a turbofan engine is designed at various engine operating points using linearized models of the engine dynamics and the scheduling variable is the low-pressure compressor speed. Then, according to the feedback method,

  5. A Theoretical Foundation for Software Engineering: A Model Calculus

    E-print Network

    Perry, Dewayne E.

    , complexity. Index Terms--Theories and Models of Software Engineering, Model Calculus, Model Composition IA Theoretical Foundation for Software Engineering: A Model Calculus Dewayne E. Perry Advanced Research in Software Engineering (ARiSE) Electrical and Computer Engineering The University of Texas

  6. Modeling and Prediction of Human Behavior

    Microsoft Academic Search

    Alex Pentland; Andrew Lin

    1995-01-01

    We describe our research toward building systemsthat include a complex, multi-state model of humandynamic behavior. This can allow us to predict humanbehavior over short periods of time, in order tocreate control systems that intelligently complementthe human's action. To accomplish this requires inferringthe internal state of the human, and thencorrectly adapting the remainder of the system toachieve optimal performance. We describe

  7. Automatic Generation of Agent Behavior Models from Raw Observational Data

    E-print Network

    Vidal, Jose M.

    to simulate human behaviors in different fields. The process of building believable models of human behavior- ulation models involving human decision processes are created using observed behavior sequences of building a model of human behavior is by deep analysis of the human decision process and human cognition

  8. Behavior Preservation in Model Refactoring using DPO Transformations with Borrowed

    E-print Network

    Baldan, Paolo

    Behavior Preservation in Model Refactoring using DPO Transformations with Borrowed Contexts, Italy baldan@math.unipd.it Abstract. Behavior preservation, namely the fact that the behavior of a model to behavior preservation rely basically on checking given models and their refactored versions. In this paper

  9. OCL and Model Driven Engineering

    Microsoft Academic Search

    Jean Bézivin; Thomas Baar; Tracy Gardner; Martin Gogolla; Reiner Hähnle; Heinrich Hussmann; Octavian Patrascoiu; Peter H. Schmitt; Jos Warmer

    2004-01-01

    Abstract Precise modeling is essential to the success of the OMG's Model Driven Architecture initiative At the modeling level (M1) OCL allows for the precision needed to write executable models Can OCL be extended to become a full high - level executable language with side - effects? At the meta - level (M2), queries, views and transformations are subjects that

  10. Numerical modeling of the transient behavior of a thermoelectric Electromagnetic Self-Induced Pump 

    E-print Network

    Djordjevic, Vladimir

    1988-01-01

    NUMERICAL MODELING OF THE TRANSIENT BEHAVIOR OF A THERMOELECTRIC ELECTROMAGNETIC SELF-INDUCED PUMP A Thesis by VLADIMIR DJORDJEVIC Submitted to the Graduate College of Texas A&M University in partial fulfilment of of the requirements... for the degree of MASTER OF SCIENCE May 1988 Major Subject: Nuclear Engineering NUMERICAL MODELING OF THE TRANSIENT BEHAVIOR OF A THERMOELECTRIC ELECTROMAGNETIC SELF-INDUCED PUMP A Thesis by VLADIMIR DJORDJEVIC Approved as to style and content by: Carl...

  11. Evaluation of TexSIM for modeling traffic behavior at diamond interchanges

    E-print Network

    Meadors, Allison Christine Cherry

    1995-01-01

    EVALUATION OF TEXSIM FOR MODELING TRAFFIC BEHAVIOR AT DIAMOND INTERCHANGES A Thesis by ALLISON CHRISTINE CHERRY MEADORS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1995 Major Subject: Civil Engineering EVALUATION OF TEXSIM FOR MODELING TRAFFIC BEHAVIOR AT DIAMOND INTERCHANGES A Thesis by ALLISON CHRISTINE CHERRY MEADORS Submitted to the Office of Graduate Studies...

  12. Exploring cognitive modelling in engineering usability design

    Microsoft Academic Search

    Xiangyang Li; Melih Gunal

    2012-01-01

    Engineering practice moves towards user-centred product design. Without effective computer-aided design tools, relying only on subjective guidelines in design and user testing in prototyping has made usability design expensive and time-consuming. This paper explores how modern cognitive modelling (CogM) can systematically address the challenges facing engineering usability design. A CogM-aided design paradigm is investigated for the different requirements of conceptual

  13. Animal Models for Adipose Tissue Engineering

    PubMed Central

    Uthamanthil, Rajesh; Beahm, Elisabeth; Frye, Cindy

    2008-01-01

    Abstract There is a critical need for adequate reconstruction of soft tissue defects resulting from tumor resection, trauma, and congenital abnormalities. To be sure, adipose tissue engineering strategies offer promising solutions. However, before clinical translation can occur, efficacy must be proven in animal studies. The aim of this review is to provide an overview of animal models currently employed for adipose tissue engineering. PMID:18544014

  14. Performance Engineering in the Community Atmosphere Model

    SciTech Connect

    Worley, P; Mirin, A; Drake, J; Sawyer, W

    2006-05-30

    The Community Atmosphere Model (CAM) is the atmospheric component of the Community Climate System Model (CCSM) and is the primary consumer of computer resources in typical CCSM simulations. Performance engineering has been an important aspect of CAM development throughout its existence. This paper briefly summarizes these efforts and their impacts over the past five years.

  15. Discrete time modelization of human pilot behavior

    NASA Technical Reports Server (NTRS)

    Cavalli, D.; Soulatges, D.

    1975-01-01

    This modelization starts from the following hypotheses: pilot's behavior is a time discrete process, he can perform only one task at a time and his operating mode depends on the considered flight subphase. Pilot's behavior was observed using an electro oculometer and a simulator cockpit. A FORTRAN program has been elaborated using two strategies. The first one is a Markovian process in which the successive instrument readings are governed by a matrix of conditional probabilities. In the second one, strategy is an heuristic process and the concepts of mental load and performance are described. The results of the two aspects have been compared with simulation data.

  16. Exploring Behavioral Markers of Long-Term Physical Activity Maintenance: A Case Study of System Identification Modeling within a Behavioral Intervention

    ERIC Educational Resources Information Center

    Hekler, Eric B.; Buman, Matthew P.; Poothakandiyil, Nikhil; Rivera, Daniel E.; Dzierzewski, Joseph M.; Aiken Morgan, Adrienne; McCrae, Christina S.; Roberts, Beverly L.; Marsiske, Michael; Giacobbi, Peter R., Jr.

    2013-01-01

    Efficacious interventions to promote long-term maintenance of physical activity are not well understood. Engineers have developed methods to create dynamical system models for modeling idiographic (i.e., within-person) relationships within systems. In behavioral research, dynamical systems modeling may assist in decomposing intervention effects…

  17. 76 FR 44245 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-25

    ...Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine Stoppage AGENCY: Federal...include engine size and the potential torque load imposed by sudden engine stoppage. These...envisioned when Sec. 25.361, which addresses loads imposed by engine seizure, was...

  18. Next-Generation Software Engineering: Function Extraction for Computation of Software Behavior

    Microsoft Academic Search

    Richard C. Linger; Mark G. Pleszkoch; Luanne Burns; Alan R. Hevner; Gwendolyn H. Walton

    2007-01-01

    The ultra-large-scale systems of the future require the transformation of software engineering into a computational discipline capable of fast and depend - able software development. This paper discusses an emerging next-generation software engineering re- search area: function extraction (FX) technology fo r automated computation to the maximum extent possi- ble of the behavior, correctness, and quality attri butes of software

  19. Chain modeling for life cycle systems engineering

    SciTech Connect

    Rivera, J.J. [Sandia National Lab., Albuquerque, NM (United States); Shapiro, V. [Univ. of Wisconsin, Madison, WI (United States). Spatial Automation Lab.

    1997-12-01

    Throughout Sandia`s history, products have been represented by drawings. Solid modeling systems have recently replaced drawings as the preferred means for representing product geometry. These systems are used for product visualization, engineering analysis and manufacturing planning. Unfortunately, solid modeling technology is inadequate for life cycle systems engineering, which requires maintenance of technical history, efficient management of geometric and non-geometric data, and explicit representation of engineering and manufacturing characteristics. Such information is not part of the mathematical foundation of solid modeling. The current state-of-the-art in life cycle engineering is comprised of painstakingly created special purpose tools, which often are incompatible. New research on {open_quotes}chain modeling{close_quotes} provides a method of chaining the functionality of a part to the geometric representation. Chain modeling extends classical solid modeling to include physical, manufacturing, and procedural information required for life cycle engineering. In addition, chain modeling promises to provide the missing theoretical basis for Sandia`s parent/child product realization paradigm. In chain modeling, artifacts and systems are characterized in terms of their combinatorial properties: cell complexes, chains, and their operators. This approach is firmly rooted in algebraic topology and is a natural extension of current technology. The potential benefits of this approach include explicit hierarchical and combinatorial representation of physics, geometry, functionality, test, and legacy data in a common computational framework that supports a rational decision process and partial design automation. Chain modeling will have a significant impact on design preservation, system identification, parameterization, system reliability, and design simplification.

  20. Genetically Engineered Pig Models for Human Diseases

    PubMed Central

    Prather, Randall S.; Lorson, Monique; Ross, Jason W.; Whyte, Jeffrey J.; Walters, Eric

    2015-01-01

    Although pigs are used widely as models of human disease, their utility as models has been enhanced by genetic engineering. Initially, transgenes were added randomly to the genome, but with the application of homologous recombination, zinc finger nucleases, and transcription activator-like effector nuclease (TALEN) technologies, now most any genetic change that can be envisioned can be completed. To date these genetic modifications have resulted in animals that have the potential to provide new insights into human diseases for which a good animal model did not exist previously. These new animal models should provide the preclinical data for treatments that are developed for diseases such as Alzheimer's disease, cystic fibrosis, retinitis pigmentosa, spinal muscular atrophy, diabetes, and organ failure. These new models will help to uncover aspects and treatments of these diseases that were otherwise unattainable. The focus of this review is to describe genetically engineered pigs that have resulted in models of human diseases. PMID:25387017

  1. 1106 / JOURNAL OF ENGINEERING MECHANICS / NOVEMBER 2001 DRAINED CYCLIC BEHAVIOR OF SAND WITH FABRIC DEPENDENCE

    E-print Network

    Wan, Richard G.

    1106 / JOURNAL OF ENGINEERING MECHANICS / NOVEMBER 2001 DRAINED CYCLIC BEHAVIOR OF SAND WITH FABRIC DEPENDENCE By Richard G. Wan1 and Pei J. Guo2 ABSTRACT: The behavior of sand is characterized by dilatancy, an increase in overall volume as particles move over each other when the sand assembly is subjected to shear

  2. Modeling and simulation of dust behaviors behind a moving vehicle

    NASA Astrophysics Data System (ADS)

    Wang, Jingfang

    Simulation of physically realistic complex dust behaviors is a difficult and attractive problem in computer graphics. A fast, interactive and visually convincing model of dust behaviors behind moving vehicles is very useful in computer simulation, training, education, art, advertising, and entertainment. In my dissertation, an experimental interactive system has been implemented for the simulation of dust behaviors behind moving vehicles. The system includes physically-based models, particle systems, rendering engines and graphical user interface (GUI). I have employed several vehicle models including tanks, cars, and jeeps to test and simulate in different scenarios and conditions. Calm weather, winding condition, vehicle turning left or right, and vehicle simulation controlled by users from the GUI are all included. I have also tested the factors which play against the physical behaviors and graphics appearances of the dust particles through GUI or off-line scripts. The simulations are done on a Silicon Graphics Octane station. The animation of dust behaviors is achieved by physically-based modeling and simulation. The flow around a moving vehicle is modeled using computational fluid dynamics (CFD) techniques. I implement a primitive variable and pressure-correction approach to solve the three dimensional incompressible Navier Stokes equations in a volume covering the moving vehicle. An alternating- direction implicit (ADI) method is used for the solution of the momentum equations, with a successive-over- relaxation (SOR) method for the solution of the Poisson pressure equation. Boundary conditions are defined and simplified according to their dynamic properties. The dust particle dynamics is modeled using particle systems, statistics, and procedure modeling techniques. Graphics and real-time simulation techniques, such as dynamics synchronization, motion blur, blending, and clipping have been employed in the rendering to achieve realistic appearing dust behaviors. In addition, I introduce a temporal smoothing technique to eliminate the jagged effect caused by large simulation time. Several algorithms are used to speed up the simulation. For example, pre-calculated tables and display lists are created to replace some of the most commonly used functions, scripts and processes. The performance study shows that both time and space costs of the algorithms are linear in the number of particles in the system. On a Silicon Graphics Octane, three vehicles with 20,000 particles run at 6-8 frames per second on average. This speed does not include the extra calculations of convergence of the numerical integration for fluid dynamics which usually takes about 4-5 minutes to achieve steady state.

  3. An RL10A-3-3A rocket engine model using the rocket engine transient simulator (ROCETS) software

    NASA Technical Reports Server (NTRS)

    Binder, Michael

    1993-01-01

    Steady-state and transient computer models of the RL10A-3-3A rocket engine have been created using the Rocket Engine Transient Simulation (ROCETS) code. These models were created for several purposes. The RL10 engine is a critical component of past, present, and future space missions; the model will give NASA an in-house capability to simulate the performance of the engine under various operating conditions and mission profiles. The RL10 simulation activity is also an opportunity to further validate the ROCETS program. The ROCETS code is an important tool for modeling rocket engine systems at NASA Lewis. ROCETS provides a modular and general framework for simulating the steady-state and transient behavior of any desired propulsion system. Although the ROCETS code is being used in a number of different analysis and design projects within NASA, it has not been extensively validated for any system using actual test data. The RL10A-3-3A has a ten year history of test and flight applications; it should provide sufficient data to validate the ROCETS program capability. The ROCETS models of the RL10 system were created using design information provided by Pratt & Whitney, the engine manufacturer. These models are in the process of being validated using test-stand and flight data. This paper includes a brief description of the models and comparison of preliminary simulation output against flight and test-stand data.

  4. Prerequisites: Control Systems I+II, System Modeling, Engine Class (Introduction to Modeling and Control of

    E-print Network

    Lygeros, John

    Thesis IDSC-LG-FZ-05 Gas Diesel Engine Modeling and Control The gas diesel engine is a natural gas enginePrerequisites: Control Systems I+II, System Modeling, Engine Class (Introduction to Modeling and Control of Internal Combustion Engine Systems, IC Engines, ...), Optimization Course, Matlab

  5. Transient behavior in the Lorenz model

    NASA Astrophysics Data System (ADS)

    Kravtsov, S.; Sugiyama, N.; Tsonis, A. A.

    2014-12-01

    Dynamical systems like the one described by the three-variable Lorenz model may serve as metaphors for complexity in nature. When natural systems are perturbed by external forcing factors, they tend to relax back to their equilibrium conditions after the forcing has shut off. Here we investigate the behavior of such transients in the Lorenz model by studying its trajectories initialized far away from the asymptotic attractor. Perhaps somewhat surprisingly, these transient trajectories exhibit complex routes and, among other things, sensitivity to initial conditions akin to that of the asymptotic behavior on the attractor. Thus, similar extreme events may lead to widely different variations before the perturbed system returns back to its statistical equilibrium.

  6. Tissue-Engineered Kidney Disease Models

    PubMed Central

    DesRochers, Teresa M.; Palma, Erica; Kaplan, David L.

    2014-01-01

    Renal disease represents a major health problem that often results in end-stage renal failure necessitating dialysis and eventually transplantation. Historically these diseases have been studied with patient observation and screening, animal models, and two-dimensional cell culture. In this review, we focus on recent advances in tissue engineered kidney disease models that have the capacity to compensate for the limitations of traditional modalities. The cells and materials utilized to develop these models are discussed and tissue engineered models of polycystic kidney disease, drug-induced nephrotoxicity, and the glomerulus are examined in detail. The application of these models has the potential to direct future disease treatments and preclinical drug development. PMID:24361391

  7. A novel tissue-engineered trachea with a mechanical behavior similar to native trachea.

    PubMed

    Park, Jeong Hun; Hong, Jung Min; Ju, Young Min; Jung, Jin Woo; Kang, Hyun-Wook; Lee, Sang Jin; Yoo, James J; Kim, Sung Won; Kim, Soo Hyun; Cho, Dong-Woo

    2015-09-01

    A novel tissue-engineered trachea was developed with appropriate mechanical behavior and substantial regeneration of tracheal cartilage. We designed hollow bellows scaffold as a framework of a tissue-engineered trachea and demonstrated a reliable method for three-dimensional (3D) printing of monolithic bellows scaffold. We also functionalized gelatin sponge to allow sustained release of TGF-?1 for stimulating tracheal cartilage regeneration and confirmed that functionalized gelatin sponge induces cartilaginous tissue formation in vitro. A tissue-engineered trachea was then created by assembling chondrocytes-seeded functionalized gelatin sponges into the grooves of bellows scaffold and it showed very similar mechanical behavior to that of native trachea along with substantial regeneration of tracheal cartilage in vivo. The tissue-engineered trachea developed here represents a novel concept of tracheal substitute with appropriate mechanical behavior similar to native trachea for use in reconstruction of tracheal stenosis. PMID:26041482

  8. Animal Models of Compulsive Eating Behavior

    PubMed Central

    Di Segni, Matteo; Patrono, Enrico; Patella, Loris; Puglisi-Allegra, Stefano; Ventura, Rossella

    2014-01-01

    Eating disorders are multifactorial conditions that can involve a combination of genetic, metabolic, environmental, and behavioral factors. Studies in humans and laboratory animals show that eating can also be regulated by factors unrelated to metabolic control. Several studies suggest a link between stress, access to highly palatable food, and eating disorders. Eating “comfort foods” in response to a negative emotional state, for example, suggests that some individuals overeat to self-medicate. Clinical data suggest that some individuals may develop addiction-like behaviors from consuming palatable foods. Based on this observation, “food addiction” has emerged as an area of intense scientific research. A growing body of evidence suggests that some aspects of food addiction, such as compulsive eating behavior, can be modeled in animals. Moreover, several areas of the brain, including various neurotransmitter systems, are involved in the reinforcement effects of both food and drugs, suggesting that natural and pharmacological stimuli activate similar neural systems. In addition, several recent studies have identified a putative connection between neural circuits activated in the seeking and intake of both palatable food and drugs. The development of well-characterized animal models will increase our understanding of the etiological factors of food addiction and will help identify the neural substrates involved in eating disorders such as compulsive overeating. Such models will facilitate the development and validation of targeted pharmacological therapies. PMID:25340369

  9. Modeling microdamage behavior of cortical bone.

    PubMed

    Donaldson, Finn; Ruffoni, Davide; Schneider, Philipp; Levchuk, Alina; Zwahlen, Alexander; Pankaj, Pankaj; Müller, Ralph

    2014-11-01

    Bone is a complex material which exhibits several hierarchical levels of structural organization. At the submicron-scale, the local tissue porosity gives rise to discontinuities in the bone matrix which have been shown to influence damage behavior. Computational tools to model the damage behavior of bone at different length scales are mostly based on finite element (FE) analysis, with a range of algorithms developed for this purpose. Although the local mechanical behavior of bone tissue is influenced by microstructural features such as bone canals and osteocyte lacunae, they are often not considered in FE damage models due to the high computational cost required to simulate across several length scales, i.e., from the loads applied at the organ level down to the stresses and strains around bone canals and osteocyte lacunae. Hence, the aim of the current study was twofold: First, a multilevel FE framework was developed to compute, starting from the loads applied at the whole bone scale, the local mechanical forces acting at the micrometer and submicrometer level. Second, three simple microdamage simulation procedures based on element removal were developed and applied to bone samples at the submicrometer-scale, where cortical microporosity is included. The present microdamage algorithm produced a qualitatively analogous behavior to previous experimental tests based on stepwise mechanical compression combined with in situ synchrotron radiation computed tomography. Our results demonstrate the feasibility of simulating microdamage at a physiologically relevant scale using an image-based meshing technique and multilevel FE analysis; this allows relating microdamage behavior to intracortical bone microstructure. PMID:24622917

  10. Modeling the model Characteristics and behavior of genetic algorithms

    E-print Network

    Modeling the model Characteristics and behavior of genetic algorithms Author. Janeen Neri Progress in data files containing the fitness distribution and genetic algorithm specifications to be tested, and normalizes the fitness data for easier manipulation. A de- tailed pseudocode outline of the genetic algorithm

  11. Modeling of thermo-mechanical and irradiation behavior of mixed oxide fuel for sodium fast reactors

    Microsoft Academic Search

    Aydin Karahan; Jacopo Buongiorno

    2010-01-01

    An engineering code to model the irradiation behavior of UO2–PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named fuel engineering and structural analysis tool (FEAST-OXIDE). FEAST-OXIDE has several modules working in coupled form with an explicit numerical algorithm. These modules describe: (1) fission gas release and swelling, (2) fuel chemistry and restructuring, (3) temperature

  12. APPLICATION OF CENTRIFUGE MODELING IN GEOTECHNICAL ENGINEERING

    E-print Network

    Kamat, Vineet R.

    APPLICATION OF CENTRIFUGE MODELING IN GEOTECHNICAL ENGINEERING Dr. Liming Li Manager of Centrifuge, Dec 5, 2012 4:00 PM GG Brown 2355 ABSTRACT: This seminar addresses the application of centrifuge may be obtained by substituting a centrifugal force to form the gravitational field, i.e., placing

  13. Model-Based Security Engineering for Real

    Microsoft Academic Search

    Jan Jürjens

    2006-01-01

    We give an overview over a soundly based secure software en- gineering methodology and associated tool-support developed over the last few years under the name of Model-based Security Engineering (MBSE). We focus in particular on applications in industry. The difficulty of designing security mechanisms correctly has motivated very successful research using mathematical concepts and tools to ensure correct de- sign

  14. Comparison of Recent Engineering Problem-Solving Models

    Microsoft Academic Search

    E. E. Anderson; R. Taraban

    Models of the cognitions used by engineering students to solve problems have always been a part of engineering education. Many, such as the engineering mechanics model (select free-body, draw vector diagram, write equilibrium equations, and solve equilibrium equations), have been part of the introduction of students to engineering topics for a long time. More recently, student problem-solving processes are being

  15. A stirling engine computer model for performance calculations

    NASA Technical Reports Server (NTRS)

    Tew, R.; Jefferies, K.; Miao, D.

    1978-01-01

    To support the development of the Stirling engine as a possible alternative to the automobile spark-ignition engine, the thermodynamic characteristics of the Stirling engine were analyzed and modeled on a computer. The modeling techniques used are presented. The performance of an existing rhombic-drive Stirling engine was simulated by use of this computer program, and some typical results are presented. Engine tests are planned in order to evaluate this model.

  16. Modeling the Information Seeking of Professionals: A General Model Derived from Research on Engineers, Health Care Professionals, and Lawyers.

    ERIC Educational Resources Information Center

    Leckie, Gloria J.; And Others

    1996-01-01

    Presents an overview of the literature concerning the information-seeking behavior of engineers, health care professionals, and lawyers and examines professional information-seeking models. Proposes an original model of information-seeking processes that would be applicable to professionals working in any field. Contains 90 references. (JMV)

  17. Modeling potentiometric titration behavior of glauconite

    NASA Astrophysics Data System (ADS)

    Lu, Weiping; Smith, Edward H.

    1996-09-01

    Potentiometric titration behavior and the effects of dissolution on the titration experiment of a complex natural clay mineral, glauconite, were investigated and interpreted according to surface complexation theory. Considerable dissolution was detected in the time frame of the titration experiments, with the amount of individual cations released from glauconite a function of solution variables and dissolution kinetics. Dissolution effects can be accounted for in model simulations of titration behavior by considering hydrolysis of these cations. Proton surface charge can be calculated by subtracting supernatant titration curves from those of glauconite suspension. Surface complexation models were used to describe titration data. The nonelectrostatic model (NEM) and constant capacitance model (CCM) were implemented using single-site, single-site with dissolution correction, and multi-site with dissolution correction approaches. CCM typically produced better fits of experimental data than NEM based on a statistical fitting parameter. In general, model descriptions are good for background electrolyte concentration ? 0.01 M. In most instances, the correction for dissolution effects yielded a modest improvement in model simulation of experimental data over that obtained by a simple single-site model, but complexity of the model calculations increases greatly when the numerous additional chemical reactions are considered. Incorporation of ion exchange interactions produced no substantive improvement over the other approaches. Consistent with these results, speciation calculations indicate that the > XOH group dominates over other surface species in the pH range of interest, and surface protonation-deprotonation are the most influential reactions with respect to the surface chemistry of the mineral.

  18. Evolution of Reference: A New Service Model for Science and Engineering Libraries

    ERIC Educational Resources Information Center

    Bracke, Marianne Stowell; Chinnaswamy, Sainath; Kline, Elizabeth

    2008-01-01

    This article explores the different steps involved in adopting a new service model at the University of Arizona Science-Engineering Library. In a time of shrinking budgets and changing user behavior the library was forced to rethink it reference services to be cost effective and provide quality service at the same time. The new model required…

  19. The Internet as recommendation engine : implications of online behavioral targeting

    E-print Network

    Smith-Grieco, Anthony Nicoll

    2010-01-01

    This thesis discusses the economic implications of Internet behavioral advertising, which targets ads to individuals based on extensive detailed data about the specific websites users have visited. Previous literature on ...

  20. Genome-scale modeling for metabolic engineering

    PubMed Central

    Simeonidis, Evangelos

    2015-01-01

    We focus on the application of constraint-based methodologies and, more specifically, flux balance analysis in the field of metabolic engineering, and enumerate recent developments and successes of the field. We also review computational frameworks that have been developed with the express purpose of automatically selecting optimal gene deletions for achieving improved production of a chemical of interest. The application of flux balance analysis methods in rational metabolic engineering requires a metabolic network reconstruction and a corresponding in silico metabolic model for the microorganism in question. For this reason, we additionally present a brief overview of automated reconstruction techniques. Finally, we emphasize the importance of integrating metabolic networks with regulatory information—an area which we expect will become increasingly important for metabolic engineering—and present recent developments in the field of metabolic and regulatory integration. PMID:25578304

  1. Tissue-engineered models of human tumors for cancer research

    PubMed Central

    Villasante, Aranzazu; Vunjak-Novakovic, Gordana

    2015-01-01

    Introduction Drug toxicity often goes undetected until clinical trials, which are the most costly and dangerous phase of drug development. Both the cultures of human cells and animal studies have limitations that cannot be overcome by incremental improvements in drug-testing protocols. A new generation of bioengineered tumors is now emerging in response to these limitations, with potential to transform drug screening by providing predictive models of tumors within their tissue context, for studies of drug safety and efficacy. An area that could greatly benefit from these models is cancer research. Areas covered In this review, the authors first describe the engineered tumor systems, using Ewing's sarcoma as an example of human tumor that cannot be predictably studied in cell culture and animal models. Then, they discuss the importance of the tissue context for cancer progression and outline the biomimetic principles for engineering human tumors. Finally, they discuss the utility of bioengineered tumor models for cancer research and address the challenges in modeling human tumors for use in drug discovery and testing. Expert opinion While tissue models are just emerging as a new tool for cancer drug discovery, they are already demonstrating potential for recapitulating, in vitro, the native behavior of human tumors. Still, numerous challenges need to be addressed before we can have platforms with a predictive power appropriate for the pharmaceutical industry. Some of the key needs include the incorporation of the vascular compartment, immune system components, and mechanical signals that regulate tumor development and function. PMID:25662589

  2. Shape-memory alloys: modelling and numerical simulations of the finite-strain superelastic behavior

    Microsoft Academic Search

    Ferdinando Auricchio; Robert L. Taylor

    1997-01-01

    Shape-memory alloys (SMA) show features not present in materials traditionally used in engineering; as a consequence, they are the basis for innovative applications. The present work proposes a step toward the development of a computation tool to be used during the design of SMA-based devices. To reach this goal, we develop a constitutive model which reproduce the superelastic behavior of

  3. Micromechanical Modeling of Multiphysical Behavior of Smart Materials Using the Variational

    E-print Network

    Yu, Wenbin

    of Mechanical and Aerospace Engineering. Presently, Research Fellow at the Center of Advanced Vehicular SystemsMicromechanical Modeling of Multiphysical Behavior of Smart Materials Using the Variational to predict the effective properties as well as the local fields of periodic smart materials responsive

  4. Potency of Animal Models in KANSEI Engineering

    NASA Astrophysics Data System (ADS)

    Ozaki, Shigeru; Hisano, Setsuji; Iwamoto, Yoshiki

    Various species of animals have been used as animal models for neuroscience and provided critical information about the brain functions. Although it seems difficult to elucidate a highly advanced function of the human brain, animal models have potency to clarify the fundamental mechanisms of emotion, decision-making and social behavior. In this review, we will pick up common animal models and point to both the merits and demerits caused by the characteristics. We will also mention that wide-ranging approaches from animal models are advantageous to understand KANSEI as well as mind in humans.

  5. Voraussetzungen: Control Systems I & II, System Modeling, Engine Class (IC Engines and Propulsion Systems,

    E-print Network

    Lygeros, John

    Systems, Introduction to Modeling and Control of Internal Combustion Engine Systems,...), MATLAB Design for a Novel Engine Concept Position Control for an Internal Combustion Engine (Simulation) German. The control task is to make an internal combustion engine piston follow a reference position trajectory

  6. A model of wine tourist behavior: A festival approach

    Microsoft Academic Search

    Jingxue Yuan

    2004-01-01

    The study constructs a temporal model of wine tourist behavior on the basis of the social psychologist' theory of consumer attitudes and related concepts with regard to past behavior, satisfaction, perceived value, and behavioral intentions. This study proposed that wine festival attendees' intentions to revisit the festival would be affected by their satisfaction with, perceived value of, and past behavior

  7. Teaching Structural Behavior with a Physics Engine Kirk Martini1

    E-print Network

    Martini, Kirk

    structural topics ranging from elementary statics to plastic analysis of beams, and frame buckling structures, elastic column buckling, and kinematic mechanisms that result from unstable configurations the perspective of structural analysis, the physics engine approach has two key features: · Large displacements

  8. Dynamics of macroautophagy: Modeling and oscillatory behavior

    NASA Astrophysics Data System (ADS)

    Han, Kyungreem; Kwon, Hyun Woong; Kang, Hyuk; Kim, Jinwoong; Lee, Myung-Shik; Choi, M. Y.

    2012-02-01

    We propose a model for macroautophagy and study the resulting dynamics of autophagy in a system isolated from its extra-cellular environment. It is found that the intracellular concentrations of autophagosomes and autolysosomes display oscillations with their own natural frequencies. Such oscillatory behaviors, which are interrelated to the dynamics of intracellular ATP, amino acids, and proteins, are consistent with the very recent biological observations. Implications of this theoretical study of autophagy are discussed, with regard to the possibility of guiding molecular studies of autophagy.

  9. Modeling creep behavior of fiber composites

    NASA Technical Reports Server (NTRS)

    Chen, J. L.; Sun, C. T.

    1988-01-01

    A micromechanical model for the creep behavior of fiber composites is developed based on a typical cell consisting of a fiber and the surrounding matrix. The fiber is assumed to be linearly elastic and the matrix nonlinearly viscous. The creep strain rate in the matrix is assumed to be a function of stress. The nominal stress-strain relations are derived in the form of differential equations which are solved numerically for off-axis specimens under uniaxial loading. A potential function and the associated effective stress and effective creep strain rates are introduced to simplify the orthotropic relations.

  10. Theoretical models of health behavior and workplace self-protective behavior

    Microsoft Academic Search

    David M. DeJoy

    1996-01-01

    This paper provides a critical review of the applicability of theoretical models of health behavior to workplace self-protective behavior. Value-expectancy, environmental\\/contextual, and behavior change models are reviewed. On this basis, an integrative framework is proposed that conceptualizes self-protective behavior as consisting of four stages or phases: hazard appraisal, decision making, initiation, and adherence. In addition, five general constructs are identified

  11. Cycle Engine Modelling Of Spark Ignition Engine Processes during Wide-Open Throttle (WOT) Engine Operation Running By Gasoline Fuel

    NASA Astrophysics Data System (ADS)

    Rahim, M. F. Abdul; Rahman, M. M.; Bakar, R. A.

    2012-09-01

    One-dimensional engine model is developed to simulate spark ignition engine processes in a 4-stroke, 4 cylinders gasoline engine. Physically, the baseline engine is inline cylinder engine with 3-valves per cylinder. Currently, the engine's mixture is formed by external mixture formation using piston-type carburettor. The model of the engine is based on one-dimensional equation of the gas exchange process, isentropic compression and expansion, progressive engine combustion process, and accounting for the heat transfer and frictional losses as well as the effect of valves overlapping. The model is tested for 2000, 3000 and 4000 rpm of engine speed and validated using experimental engine data. Results showed that the engine is able to simulate engine's combustion process and produce reasonable prediction. However, by comparing with experimental data, major discrepancy is noticeable especially on the 2000 and 4000 rpm prediction. At low and high engine speed, simulated cylinder pressures tend to under predict the measured data. Whereas the cylinder temperatures always tend to over predict the measured data at all engine speed. The most accurate prediction is obtained at medium engine speed of 3000 rpm. Appropriate wall heat transfer setup is vital for more precise calculation of cylinder pressure and temperature. More heat loss to the wall can lower cylinder temperature. On the hand, more heat converted to the useful work mean an increase in cylinder pressure. Thus, instead of wall heat transfer setup, the Wiebe combustion parameters are needed to be carefully evaluated for better results.

  12. 3D Modeling Engine Representation Summary Report

    SciTech Connect

    Steven Prescott; Ramprasad Sampath; Curtis Smith; Timothy Yang

    2014-09-01

    Computers have been used for 3D modeling and simulation, but only recently have computational resources been able to give realistic results in a reasonable time frame for large complex models. This summary report addressed the methods, techniques, and resources used to develop a 3D modeling engine to represent risk analysis simulation for advanced small modular reactor structures and components. The simulations done for this evaluation were focused on external events, specifically tsunami floods, for a hypothetical nuclear power facility on a coastline.

  13. Software-Engineering Process Simulation (SEPS) model

    NASA Technical Reports Server (NTRS)

    Lin, C. Y.; Abdel-Hamid, T.; Sherif, J. S.

    1992-01-01

    The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments.

  14. Subject: [roboms] [jobs] Motion Behavior Engineer & Software Developer Date: Tue, 16 Jun 2009 17:47:15 0400

    E-print Network

    Plotkin, Joshua B.

    Subject: [roboms] [jobs] Motion Behavior Engineer & Software Developer positions Date: Tue, 16 and facilitate what is necessary to blend smoothly from > behaviors into canned animations with the game. > > > > Requirements: > > > > * At least 2 years of programming experience with emphasis on > animation

  15. 3D Engineered Models for Construction Support & Available Tools

    E-print Network

    3D Engineered Models for Construction Support & Available Tools #12;3D Engineered Models for Construction · New web page www.fhwa.dot.gov/3d (search "fhwa 3D") ­ Specs, Standards, Details, Tech Briefs ­ Provides initial response within 24 hours of inquiry National Website and TSSC 2 #12;3D Engineered Models

  16. Modeling of an internal combustion engine for control analysis

    Microsoft Academic Search

    Jeffrey A. Cook; Barry K. Powell

    1988-01-01

    Recent activity in nonthermodynamic modeling of automotive internal combustion engines with spark ignition, which are inherently nonlinear, is reviewed. A fundamental nonlinear model of the engine is presented, and a linear control-oriented model is derived from the nonlinear process. Techniques for experimental verification are examined, and a practical linear engine example incorporating multirate sampling is illustrated

  17. State-Based Behavior Modeling of the Integrated SLS-MPCV System

    NASA Technical Reports Server (NTRS)

    Bonanne, Kevin H.

    2012-01-01

    In NASA's effort to foster a human spaceflight capability beyond Earth's orbit, two space systems are being developed - the Space Launch System (SLS) and the Multi-Purpose Crew Vehicle (MPCV). As of this time, the interactions between the two systems during launch are not fully detailed. To remedy this situation, a Systems Engineering approach utilizing models was developed to investigate the behavior of the integrated SLS-MPCV stack during ascent and abort situations. Specifically, this innovative approach combines aspects of Model-Based Systems Engineering (MBSE) and state analysis to simultaneously model the physical, functional, and behavioral aspects of systems. This approach focuses solely on the interactions between the systems, leaving much of the internal workings of either system at a logical level (i.e., black box). By utilizing this newly defined approach, a behavior model for the integrated SLS-MPCV stack was developed, emphasizing only the subset of interactions between the systems that impact behavior. Finally, analysis is performed within the model to investigate requirements gaps and examine the execution times of key behaviors related to various ascent phases and abort scenarios. The work described in this paper is merely a portion of the outlined effort being undertaken for this project; only a segment of the SLS-MPCV system behavior will be described.

  18. Unified constitutive model for single crystal deformation behavior with applications

    NASA Technical Reports Server (NTRS)

    Walker, K. P.; Meyer, T. G.; Jordan, E. H.

    1988-01-01

    Single crystal materials are being used in gas turbine airfoils and are candidates for other hot section components because of their increased temperature capabilities and resistance to thermal fatigue. Development of a constitutive model which assesses the inelastic behavior of these materials has been studied in 2 NASA programs: Life Prediction and Constitutive Models for Engine Hot Section Anisotropic Materials and Biaxial Constitutive Equation Development for Single Crystals. The model has been fit to a large body of constitutive data for single crystal PWA 1480 material. The model uses a unified approach for computing total inelastic strains (creep plus plasticity) on crystallographic slip systems reproducing observed directional and strain rate effects as a natural consequence of the summed slip system quantities. The model includes several of the effects that have been reported to influence deformation in single crystal materials, such as shear stress, latent hardening, and cross slip. The model is operational in a commercial Finite Element code and is being installed in a Boundary Element Method code.

  19. Modeling Impact Behavior of Glass with Peridynamics

    NASA Astrophysics Data System (ADS)

    Satapathy, S.; Dawson, A.; Bless, S.; Polyzois, I.; Rodin, G.

    2009-06-01

    Glass is being considered for various transparent armor applications due to its high compressive strength. However, its low tensile properties lead to cracks and fractures if significant tensile stresses are present. Presence of surface cracks in combination with high tensile stresses lead to dynamic failure, sometimes in an explosive manner. We have conducted bar impact experiments as well as ballistic tests to study their penetration behavior. Numerical simulation of these experiments is a challenge. The existing hydrocodes do not provide satisfactory results for brittle materials. This can be attributed to significant differences in constitutive behavior between brittle and ductile materials and the need to account for many fracture surfaces. A new numerical method, peridynamics---a meshless Lagrangian method solving the equation of motion in integral form---has been proposed by Stewart Silling that appears to be more suitable for modeling brittle materials. We use this method to examine the response of glass to impact loads in both bar impact and penetration experiments. This paper will discuss advantages and difficulties in modeling glass with peridynamics.

  20. Animal Models for Bone Tissue Engineering Purposes

    Microsoft Academic Search

    Véronique Viateau; Delphine Logeart-Avramoglou; Geneviève Guillemin; Hervé Petite

    To assess the efficacy of engineered tissues, it is necessary to have (1) appropriate large animal models that mimic the clinical\\u000a setting and (2) relevant methods of monitoring the biofuntionality of these tissues. However, developing these tissue constructs\\u000a is a step-by-step process in which numerous variables such as scaffold design, source of stem cells and mode of growth factor\\u000a application

  1. BIOMASS REBURNING - MODELING/ENGINEERING STUDIES

    SciTech Connect

    Vladimir Zamansky; Chris Lindsey

    1999-10-29

    This project is designed to develop engineering and modeling tools for a family of NO{sub x}control technologies utilizing biomass as a reburning fuel. During the eighth reporting period (July 1--September 26, 1999), Antares Group Inc, under contract to Niagara Mohawk Power Corporation, evaluated the economic feasibility of biomass reburning options for Dunkirk Station. This report includes summary of the findings; complete information will be submitted in the next Quarterly Report.

  2. Learning-Based Modeling of Multimodal Behaviors for Humanlike Robots

    E-print Network

    Mutlu, Bilge

    on stud- ies of human interactions to build models of humanlike behavior and to achieve such integration (DBN) for modeling how humans coordinate speech, gaze, and gesture behaviors in narration and providing a probabilistic representation of the dynamics of human behavior. We discuss the implications

  3. CSEM WP 125 Testing Strategic Models of Firm Behavior in

    E-print Network

    California at Berkeley. University of

    CSEM WP 125 Testing Strategic Models of Firm Behavior in Restructured Electricity Markets: A Case;Testing Strategic Models of Firm Behavior in Restructured Electricity Markets: A Case Study of ERCOT Ali in an electricity auction submit bids that approximate a benchmark for optimal behavior. First, we derive

  4. A Markov Chain Model of Temporal Behavior for Anomaly Detection

    Microsoft Academic Search

    Nong Ye

    2000-01-01

    This paper presents an anomaly detection technique to detect intrusions into computer and network systems. In this technique, a Markov chain model is used to represent a temporal profile of normal behavior in a computer and network system. The Markov chain model of the norm profile is learned from historic data of the system's normal behavior. The observed behavior of

  5. A Conceptual Model of Leisure-Time Choice Behavior.

    ERIC Educational Resources Information Center

    Bergier, Michel J.

    1981-01-01

    Methods of studying the gap between predisposition and actual behavior of consumers of spectator sports is discussed. A model is drawn from the areas of behavioral sciences, consumer behavior, and leisure research. The model is constructed around the premise that choice is primarily a function of personal, product, and environmental factors. (JN)

  6. LEADER - An integrated engine behavior and design analyses based real-time fault diagnostic expert system for Space Shuttle Main Engine (SSME)

    NASA Technical Reports Server (NTRS)

    Gupta, U. K.; Ali, M.

    1989-01-01

    The LEADER expert system has been developed for automatic learning tasks encompassing real-time detection, identification, verification, and correction of anomalous propulsion system operations, using a set of sensors to monitor engine component performance to ascertain anomalies in engine dynamics and behavior. Two diagnostic approaches are embodied in LEADER's architecture: (1) learning and identifying engine behavior patterns to generate novel hypotheses about possible abnormalities, and (2) the direction of engine sensor data processing to perform resoning based on engine design and functional knowledge, as well as the principles of the relevant mechanics and physics.

  7. Reverse Engineering MAC: A Non-Cooperative Game Model

    E-print Network

    Huang, Jianwei

    Reverse Engineering MAC: A Non-Cooperative Game Model Jianwei Huang Information Engineering. Huang (CUHK) Reverse Engineering MAC Nov. 2007 1 / 21 #12;Summary Reverse engineering: Given the missing piece (on MAC) for existing layers 2-4 protocols on rigorous mathematical foundation J. Huang

  8. Tailoring the software engineering Institute's (SEI) Capability Maturity Model (CMM) to a software sustaining engineering organization

    Microsoft Academic Search

    D. W. Drew

    1992-01-01

    The Software Engineering Institute's Softwares Process Maturity Model was developed to provide a basis for assessing an organization's ability to perform software engineering activities. It also provides a guide for improving an organization's software engineering capability. The maturity model was designed on the basis of concepts associated with developing new, large, complex systems. This has led to difficulties in applying

  9. Behavioral Model Equivalence Checking for Large Analog Mixed Signal Systems 

    E-print Network

    Singh, Amandeep

    2012-07-16

    /O) circuits. I propose to verify the equivalence between a behavioral model and its electrical implementation over a limited, but highly likely, input space defined as the Constrained Behavioral Input Space. Furthermore, I clearly distinguish between...

  10. Animal models of restricted repetitive behavior in autism.

    PubMed

    Lewis, Mark H; Tanimura, Yoko; Lee, Linda W; Bodfish, James W

    2007-01-10

    Restricted, repetitive behavior, along with deficits in social reciprocity and communication, is diagnostic of autism. Animal models relevant to this domain generally fall into three classes: repetitive behavior associated with targeted insults to the CNS; repetitive behavior induced by pharmacological agents; and repetitive behavior associated with restricted environments and experience. The extant literature provides potential models of the repetitive behavioral phenotype in autism rather than attempts to model the etiology or pathophysiology of restricted, repetitive behavior, as these are poorly understood. This review focuses on our work with deer mice which exhibit repetitive behaviors associated with environmental restriction. Repetitive behaviors are the most common category of abnormal behavior observed in confined animals and larger, more complex environments substantially reduce the development and expression of such behavior. Studies with this model, including environmental enrichment effects, suggest alterations in cortical-basal ganglia circuitry in the development and expression of repetitive behavior. Considerably more work needs to be done in this area, particularly in modeling the development of aberrant repetitive behavior. As mutant mouse models continue to proliferate, there should be a number of promising genetic models to pursue. PMID:16997392

  11. Kinetic modelling of a surrogate diesel fuel applied to 3D auto-ignition in HCCI engines

    Microsoft Academic Search

    Roda Bounaceur; Pierre-Alexandre Glaude; René Fournet; Frédérique Battin-Leclerc; S. Jay; A. Pires Da Cruz

    2007-01-01

    The prediction of auto-ignition delay times in HCCI engines has risen interest on detailed chemical models. This paper described a validated kinetic mechanism for the oxidation of a model Diesel fuel (n-decane and ?-methylnaphthalene). The 3D model for the description of low and high temperature auto-ignition in engines is presented. The behavior of the model fuel is compared with that

  12. Modeling the effect of engine assembly mass on engine friction and vehicle fuel economy

    NASA Astrophysics Data System (ADS)

    An, Feng; Stodolsky, Frank

    An analytical model is developed to estimate the impact of reducing engine assembly mass (the term engine assembly refers to the moving components of the engine system, including crankshafts, valve train, pistons, and connecting rods) on engine friction and vehicle fuel economy. The relative changes in frictional mean effective pressure and fuel economy are proportional to the relative change in assembly mass. These changes increase rapidly as engine speed increases. Based on the model, a 25% reduction in engine assembly mass results in a 2% fuel economy improvement for a typical mid-size passenger car over the EPA Urban and Highway Driving Cycles.

  13. Hydrologic Behavior of Two Engineered Barriers Following Extreme Wetting

    SciTech Connect

    Porro, I.

    2000-09-30

    Many engineered barriers are expected to function for hundreds of years or longer. Over the course of time, it is likely that some barriers will experience infiltration to the point of breakthrough. This study compares the recovery from breakthrough of two storage- evapotranspiration type engineered barriers. Replicates of test plots comprising thick soil and capillary/biobarrier covers were wetted to breakthrough in 1997. Test plots were kept cleared of vegetation to maximize hydrologic stress during recovery. Following cessation of drainage resulting from the wetting irrigations, water storage levels in all plots were at elevated levels compared to pre-irrigation levels. As a result, infiltration of melting snow during the subsequent spring overloaded the storage capacity and produced drainage in all plots. Relatively rapid melting of accumulated snowfall produced the most significant infiltration events each year during the study. Capillary barriers yielded less total drainage than thick soil barriers. By limiting drainage, capillary barriers increased water storage in the upper portions of the test plots, which led to increased evaporation from the capillary barrier plots compared to thick soil plots. Increased evaporation in the capillary barrier plots allowed more water to infiltrate in the second season following the wetting tests without triggering drainage. All thick soil plots again yielded drainage in the second season. Within two years of intentionally induced breakthrough, evaporation alone (without transpiration) restored the capability of the capillary barrier covers to function as intended, although water storage in these covers remained at elevated levels.

  14. Kinetic modelling of a surrogate diesel fuel applied to 3D auto-ignition in HCCI engines

    E-print Network

    Bounaceur, Roda; Fournet, René; Battin-Leclerc, Frédérique; Jay, S; Da Cruz, A Pires

    2007-01-01

    The prediction of auto-ignition delay times in HCCI engines has risen interest on detailed chemical models. This paper described a validated kinetic mechanism for the oxidation of a model Diesel fuel (n-decane and ?-methylnaphthalene). The 3D model for the description of low and high temperature auto-ignition in engines is presented. The behavior of the model fuel is compared with that of n-heptane. Simulations show that the 3D model coupled with the kinetic mechanism can reproduce experimental HCCI and Diesel engine results and that the correct modeling of auto-ignition in the cool flame region is essential in HCCI conditions.

  15. Using GOMS and Bayesian plan recognition to develop recognition models of operator behavior

    NASA Astrophysics Data System (ADS)

    Zaientz, Jack D.; DeKoven, Elyon; Piegdon, Nicholas; Wood, Scott D.; Huber, Marcus J.

    2006-05-01

    Trends in combat technology research point to an increasing role for uninhabited vehicles in modern warfare tactics. To support increased span of control over these vehicles human responsibilities need to be transformed from tedious, error-prone and cognition intensive operations into tasks that are more supervisory and manageable, even under intensely stressful conditions. The goal is to move away from only supporting human command of low-level system functions to intention-level human-system dialogue about the operator's tasks and situation. A critical element of this process is developing the means to identify when human operators need automated assistance and to identify what assistance they need. Toward this goal, we are developing an unmanned vehicle operator task recognition system that combines work in human behavior modeling and Bayesian plan recognition. Traditionally, human behavior models have been considered generative, meaning they describe all possible valid behaviors. Basing behavior recognition on models designed for behavior generation can offers advantages in improved model fidelity and reuse. It is not clear, however, how to reconcile the structural differences between behavior recognition and behavior modeling approaches. Our current work demonstrates that by pairing a cognitive psychology derived human behavior modeling approach, GOMS, with a Bayesian plan recognition engine, ASPRN, we can translate a behavior generation model into a recognition model. We will discuss the implications for using human performance models in this manner as well as suggest how this kind of modeling may be used to support the real-time control of multiple, uninhabited battlefield vehicles and other semi-autonomous systems.

  16. Energy Efficient Engine Exhaust Mixer Model Technology

    NASA Technical Reports Server (NTRS)

    Kozlowski, H.; Larkin, M.

    1981-01-01

    An exhaust mixer test program was conducted to define the technology required for the Energy Efficient Engine Program. The model configurations of 1/10 scale were tested in two phases. A parametric study of mixer design options, the impact of residual low pressure turbine swirl, and integration of the mixer with the structural pylon of the nacelle were investigated. The improvement of the mixer itself was also studied. Nozzle performance characteristics were obtained along with exit profiles and oil smear photographs. The sensitivity of nozzle performance to tailpipe length, lobe number, mixer penetration, and mixer modifications like scalloping and cutbacks were established. Residual turbine swirl was found detrimental to exhaust system performance and the low pressure turbine system for Energy Efficient Engine was designed so that no swirl would enter the mixer. The impact of mixer/plug gap was also established, along with importance of scalloping, cutbacks, hoods, and plug angles on high penetration mixers.

  17. Quantum critical behavior in a graphenelike model

    NASA Astrophysics Data System (ADS)

    Hands, Simon; Strouthos, Costas

    2008-10-01

    We present the results of numerical simulations of a (2+1) -dimensional fermion field theory based on a recent proposal for a model of graphene consisting of Nf four-component Dirac fermions moving in the plane and interacting via an instantaneous Coulomb interaction. In the strong-coupling limit we identify a critical number of flavors Nfc=4.8(2) separating an insulating from a conducting phase. This transition corresponds to the location of a quantum critical point, and we use a fit to the equation of state for the chiral order parameter to estimate the critical exponents. Next we simulate Nf=2 corresponding to real graphene and approximately locate a transition from strong- to weak-coupling behavior. Strong correlations are evident in the weak-coupling regime.

  18. Experimental and analytical tools for evaluation of Stirling engine rod seal behavior

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.; Cheng, H. S.

    1979-01-01

    The first year of a two year experimental and analytical program is reported. The program is directed at the elastohydrodynamic behavior of sliding elastomeric rod seals for the Stirling engine. During the year, experimental and analytical tools were developed for evaluating seal leakage, seal friction, and the fluid film thickness at the seal/cylinder interface.

  19. On the Postbuckling Behavior ofJ. W. HUTCHINSON Divisionof Engineering

    E-print Network

    Hutchinson, John W.

    On the Postbuckling Behavior ofJ. W. HUTCHINSON Professor, Divisionof Engineering and Applied for publication (without presentation) in the JOURNAL OF ApPLIED MECHANICS. Discussion on this paper should 4, 1970. Paper No. 71-APM-FF. Journal of Applied Mechanics asymptotic results relating the buckling

  20. A Physical Model for the Engine Oil Condition Sensor

    Microsoft Academic Search

    Simon S. Wang

    2001-01-01

    The engine oil condition sensor has the capability of detecting three oil degradation stages: good, rapid increase of acidic decomposition products, and rapid increase of viscosity. In this work, a model was developed to correlate the sensor output with key engine oil parameters. Based on this model, the sensor output measured from a degraded engine oil should be linearly proportional

  1. Neuro-fuzzy model of superelastic shape memory alloys with application to seismic engineering

    E-print Network

    Ozbulut, Osman Eser

    2009-05-15

    of SMAs in seismic engineering applications a soft computing approach, namely a neurofuzzy technique is used to model dynamic behavior of CuAlBe shape memory alloy wires. Experimental data are collected from two test programs that have been performed...

  2. Semantically-Rigorous Systems Engineering Modeling Using Sysml and OWL

    NASA Technical Reports Server (NTRS)

    Jenkins, J. Steven; Rouquette, Nicolas F.

    2012-01-01

    The Systems Modeling Language (SysML) has found wide acceptance as a standard graphical notation for the domain of systems engineering. SysML subsets and extends the Unified Modeling Language (UML) to define conventions for expressing structural, behavioral, and analytical elements, and relationships among them. SysML-enabled modeling tools are available from multiple providers, and have been used for diverse projects in military aerospace, scientific exploration, and civil engineering. The Web Ontology Language (OWL) has found wide acceptance as a standard notation for knowledge representation. OWL-enabled modeling tools are available from multiple providers, as well as auxiliary assets such as reasoners and application programming interface libraries, etc. OWL has been applied to diverse projects in a wide array of fields. While the emphasis in SysML is on notation, SysML inherits (from UML) a semantic foundation that provides for limited reasoning and analysis. UML's partial formalization (FUML), however, does not cover the full semantics of SysML, which is a substantial impediment to developing high confidence in the soundness of any conclusions drawn therefrom. OWL, by contrast, was developed from the beginning on formal logical principles, and consequently provides strong support for verification of consistency and satisfiability, extraction of entailments, conjunctive query answering, etc. This emphasis on formal logic is counterbalanced by the absence of any graphical notation conventions in the OWL standards. Consequently, OWL has had only limited adoption in systems engineering. The complementary strengths and weaknesses of SysML and OWL motivate an interest in combining them in such a way that we can benefit from the attractive graphical notation of SysML and the formal reasoning of OWL. This paper describes an approach to achieving that combination.

  3. On the Thermomechanical Behavior of Epoxy Polymers: Experiments and Modeling

    E-print Network

    Poulain, Xavier Marc Nicolas

    2012-02-14

    epoxy is characterized experimentally for temperatures below Tg. The intrinsic behavior of the polymer is obtained using a new methodology based on digital image correlation (DIC) in combination with video-monitored extensometry. In particular...% of the total engine weight whereas the more recent 9:5 bypass ratio GEnx-1B represents a weight ratio of 33%. Therefore, it was natural for polymer matrix composites to be selected as materials for the new generation of jet 7 engine fan cases. GEnx...

  4. Modeling Driving Behavior at Traffic Control Devices

    Microsoft Academic Search

    Abhisek Mudgal

    2011-01-01

    Transportation is a major source of many major air pollutants as well as greenhouse gas emissions. The four common factors responsible for vehicular emissions are vehicle, road characteristics, traffic conditions and driving behavior. The objective of this dissertation was to study driving behavior since it is highly correlated to emissions as shown by previous studies. Understanding driving behavior is likely

  5. Operating strategy for a hydrogen engine for improved drive-cycle efficiency and emissions behavior.

    SciTech Connect

    Wallner, T.; Lohse-Busch, H.; Shidore, N.; Energy Systems

    2009-05-01

    Due to their advanced state of development and almost immediate availability, hydrogen internal combustion engines could act as a bridging technology toward a wide-spread hydrogen infrastructure. Extensive research, development and steady-state testing of hydrogen internal combustion engines has been conducted to improve efficiency, emissions behavior and performance. This paper summarizes the steady-state test results of the supercharged hydrogen-powered four-cylinder engine operated on an engine dynamometer. Based on these results a shift strategy for optimized fuel economy is established and engine control strategies for various levels of hybridization are being discussed. The strategies are evaluated on the Urban drive cycle, differences in engine behavior are investigated and the estimated fuel economy and NO{sub x} emissions are calculated. Future work will include dynamic testing of these strategies and powertrain configurations as well as individual powertrain components on a vehicle platform, called 'Mobile Advanced Technology Testbed' (MATT), that was developed and built at Argonne National Laboratory.

  6. Operating strategy for a hydrogen engine for improved drive-cycle efficiency and emissions behavior.

    SciTech Connect

    Wallner, T.; Lohse-Busch, H.; Shidore, N.; Energy Systems

    2009-05-01

    Due to their advanced state of development and almost immediate availability, hydrogen internal combustion engines could act as a bridging technology toward a wide-spread hydrogen infrastructure. Extensive research, development and steady-state testing of hydrogen internal combustion engines has been conducted to improve efficiency, emissions behavior and performance. This paper summarizes the steady-state test results of the supercharged hydrogen-powered four-cylinder engine operated on an engine dynamometer. Based on these results a shift strategy for optimized fuel economy is established and engine control strategies for various levels of hybridization are being discussed. The strategies are evaluated on the Urban drive cycle, differences in engine behavior are investigated and the estimated fuel economy and NO{sub x} emissions are calculated. Future work will include dynamic testing of these strategies and powertrain configurations as well as individual powertrain components on a vehicle platform, called Mobile Advanced Technology Testbed (MATT), that was developed and built at Argonne National Laboratory.

  7. Behavior-based Modeling and its Application to Email Analysis

    E-print Network

    Yang, Junfeng

    Behavior-based Modeling and its Application to Email Analysis SALVATORE J. STOLFO, SHLOMO HERSHKOP ________________________________________________________________________ The Email Mining Toolkit (EMT) is a data mining system that computes behavior profiles or models of user email accounts. These models may be used for a multitude of tasks including forensic analyses

  8. Large Time Behavior of Nonlocal Aggregation Models with Nonlinear Diffusion

    E-print Network

    Soatto, Stefano

    Large Time Behavior of Nonlocal Aggregation Models with Nonlinear Diffusion Martin Burger Marco Di behavior of non- local models for aggregation, including the possible presence of nonlinear diffusion terms modeling local repulsions. We show that, as expected from the practical motivation as well as from

  9. Dynamic and Structural Gas Turbine Engine Modeling

    NASA Technical Reports Server (NTRS)

    Turso, James A.

    2003-01-01

    Model the interactions between the structural dynamics and the performance dynamics of a gas turbine engine. Generally these two aspects are considered separate, unrelated phenomena and are studied independently. For diagnostic purposes, it is desirable to bring together as much information as possible, and that involves understanding how performance is affected by structural dynamics (if it is) and vice versa. This can involve the relationship between thrust response and the excitation of structural modes, for instance. The job will involve investigating and characterizing these dynamical relationships, generating a model that incorporates them, and suggesting and/or developing diagnostic and prognostic techniques that can be incorporated in a data fusion system. If no coupling is found, at the least a vibration model should be generated that can be used for diagnostics and prognostics related to blade loss, for instance.

  10. Modeling of Suppliers' Learning Behaviors in an Electricity Market Environment

    E-print Network

    Tesfatsion, Leigh

    Modeling of Suppliers' Learning Behaviors in an Electricity Market Environment Nanpeng Yu* Chen on the learning behavior of electricity suppliers will provide insights into gaming on the market and the power suppliers' behavior. The learning configuration for suppliers in [2] is a version of a stochastic reactive

  11. SPECIAL ISSUE PAPER Modeling social behaviors in an evacuation simulator

    E-print Network

    Stanford University

    the effects of human and social behaviors on egress perfor- mance and the emergent crowd movement patterns. WeSPECIAL ISSUE PAPER Modeling social behaviors in an evacuation simulator Mei Ling Chu1 *, Paolo significantly impact egress performance. By simulating different occupants' behaviors, architects and facility

  12. Formalized Behavior Models for MOUT OPFOR Individual Combatant Weapon Firing

    Microsoft Academic Search

    Richard Stottler; Stephanie Lackey; John Brian Kirby

    2004-01-01

    This paper describes techniques to augment the behavioral models of automated Opposing Forces (OPFOR) Individual Combatants (ICs) with a realistic, practical set of weapon firing behaviors for virtual Military Operations in Urban Terrain (MOUT) training environments. These behaviors represent a formalization of target acquisition and firing execution tactics and techniques based on doctrine, input from subject matter experts, and observations

  13. BIOMASS REBURNING - MODELING/ENGINEERING STUDIES

    SciTech Connect

    Vladimir Zamansky; David Moyeda; Mark Sheldon

    2000-04-28

    This project is designed to develop engineering and modeling tools for a family of NO{sub x} control technologies utilizing biomass as a reburning fuel. During the tenth reporting period (January 1-March 31, 2000), EER and NETL R and D group continued to work on Tasks 2, 3, 4, and 5. Information regarding these tasks will be included in the next Quarterly Report. This report includes (Appendix 1) a conceptual design study for the introduction of biomass reburning in a working coal-fired utility boiler. This study was conducted under the coordinated SBIR program funded by the U. S. Department of Agriculture.

  14. Mixed Phase Modeling in GlennICE with Application to Engine Icing

    NASA Technical Reports Server (NTRS)

    Wright, William B.; Jorgenson, Philip C. E.; Veres, Joseph P.

    2011-01-01

    A capability for modeling ice crystals and mixed phase icing has been added to GlennICE. Modifications have been made to the particle trajectory algorithm and energy balance to model this behavior. This capability has been added as part of a larger effort to model ice crystal ingestion in aircraft engines. Comparisons have been made to four mixed phase ice accretions performed in the Cox icing tunnel in order to calibrate an ice erosion model. A sample ice ingestion case was performed using the Energy Efficient Engine (E3) model in order to illustrate current capabilities. Engine performance characteristics were supplied using the Numerical Propulsion System Simulation (NPSS) model for this test case.

  15. Behavior of human chondrocytes in engineered porous bacterial cellulose scaffolds.

    PubMed

    Andersson, Jessica; Stenhamre, Hanna; Bäckdahl, Henrik; Gatenholm, Paul

    2010-09-15

    Regeneration of articular cartilage damage is an area of great interest due to the limited ability of cartilage to self-repair. The latest cartilage repair strategies are dependent on access to biomaterials to which chondrocytes can attach and in which they can migrate and proliferate, producing their own extracellular matrix. In the present study, engineered porous bacterial cellulose (BC) scaffolds were prepared by fermentation of Acetobacter xylinum (A. xylinum) in the presence of slightly fused wax particles with a diameter of 150-300 microm, which were then removed by extrusion. This porous material was evaluated as a scaffold for cartilage regeneration. Articular chondrocytes from young adult patients as well as neonatal articular chondrocytes were seeded with various seeding techniques onto the porous BC scaffolds. Scanning electron microscopy (SEM) analysis and confocal microscopy analysis showed that cells entered the pores of the scaffolds and that they increasingly filled out the pores over time. Furthermore, DNA analysis implied that the chondrocytes proliferated within the porous BC. Alcian blue van Gieson staining revealed glycosaminoglycan (GAG) production by chondrocytes in areas where cells were clustered together. With some further development, this novel biomaterial can be a suitable candidate for cartilage regeneration applications. PMID:20694979

  16. Re-engineering of computer engineering education based on CDIO Education Model

    Microsoft Academic Search

    Chao Yi; Hongzhi Liao; Wei Zhou; Tony Chen; Jie Qin

    2010-01-01

    Solving the main problems of the disconnect between computer application talent cultivation and real world marketplace demands and the existing deficiency in engineering and innovation ability of higher education programs. This paper gives an analysis of current engineering programs, the reengineering effort of computer engineering programs and the CDIO Model, describes a new refined program based on applying CDIO principles

  17. Modeling the flows of engineered nanomaterials during waste handling.

    PubMed

    Mueller, Nicole C; Buha, Jelena; Wang, Jing; Ulrich, Andrea; Nowack, Bernd

    2013-01-01

    Little is known about the behavior of engineered nanomaterials (ENM) at the interface from the technosphere to the ecosphere. Previous modeling of ENM flows to the environment revealed that significant amounts of ENM enter the waste stream and therefore waste incineration plants and landfills. It is the aim of this study to model the flows of ENM during waste incineration and landfilling in greater depth by including a more detailed description of the different processes and considering ENM-specific transformation reactions. Four substances were modeled: nano-TiO2, nano-ZnO, nano-Ag and carbon nanotube (CNT). These ENM are representative for commonly used materials and products, illustrating a variety of ENM with different behavior. The modeling was performed for Switzerland where almost 100% of the municipal waste and sewage sludge are burned. The mass-based modeling showed that – despite several differences among the models for nano-TiO2, nano-ZnO and nano-Ag (e.g. partial dissolution of nano-ZnO in acid washing of exhaust air or fly ash) – the major ENM flows go from the waste incineration plant to the landfill as bottom ash. All other flows within the system boundary (e.g. with the fly ash) were predicted to be about one magnitude smaller than the bottom ash flow. A different ENM distribution was found for CNTs that are expected to burn to a large extent (94%) so that only insignificant amounts remain in the system. The results of the modeling show that waste incineration can have a strong influence on some ENM but that still the majority of the ENM-mass is expected to end up in landfills. PMID:24592442

  18. Prerequisites: Control Systems I+II, System Modeling, Engine Class (Introduction to Modeling and Control of

    E-print Network

    Daraio, Chiara

    , florianz@ethz.ch Semester Project IDSC-CO-RH-02 DPF Regeneration in the Gas-Diesel Engine Modeling and Control The gas-diesel engine is a natural gas engine, where the combustion is initiated by a smallPrerequisites: Control Systems I+II, System Modeling, Engine Class (Introduction to Modeling

  19. Engineering model for low-velocity impacts of multi-material cylinder on a rigid boundary

    NASA Astrophysics Data System (ADS)

    Buchely, M. F.; Maranon, A.; Delvare, F.

    2012-08-01

    Modern ballistic problems involve the impact of multi-material projectiles. In order to model the impact phenomenon, different levels of analysis can be developed: empirical, engineering and simulation models. Engineering models are important because they allow the understanding of the physical phenomenon of the impact materials. However, some simplifications can be assumed to reduce the number of variables. For example, some engineering models have been developed to approximate the behavior of single cylinders when impacts a rigid surface. However, the cylinder deformation depends of its instantaneous velocity. At this work, an analytical model is proposed for modeling the behavior of a unique cylinder composed of two different metals cylinders over a rigid surface. Material models are assumed as rigid-perfectly plastic. Differential equation systems are solved using a numerical Runge-Kutta method. Results are compared with computational simulations using AUTODYN 2D hydrocode. It was found a good agreement between engineering model and simulation results. Model is limited by the impact velocity which is transition at the interface point given by the hydro dynamical pressure proposed by Tate.

  20. Cognitive engineering models in space systems

    NASA Technical Reports Server (NTRS)

    Mitchell, Christine M.

    1992-01-01

    NASA space systems, including mission operations on the ground and in space, are complex, dynamic, predominantly automated systems in which the human operator is a supervisory controller. The human operator monitors and fine-tunes computer-based control systems and is responsible for ensuring safe and efficient system operation. In such systems, the potential consequences of human mistakes and errors may be very large, and low probability of such events is likely. Thus, models of cognitive functions in complex systems are needed to describe human performance and form the theoretical basis of operator workstation design, including displays, controls, and decision support aids. The operator function model represents normative operator behavior-expected operator activities given current system state. The extension of the theoretical structure of the operator function model and its application to NASA Johnson mission operations and space station applications is discussed.

  1. Phase behavior of model ABC triblock copolymers

    NASA Astrophysics Data System (ADS)

    Chatterjee, Joon

    The phase behavior of poly(isoprene-b-styrene- b-ethylene oxide) (ISO), a model ABC triblock copolymer has been studied. This class of materials exhibit self-assembly, forming a large array of ordered morphologies at length scales of 5-100 nm. The formation of stable three-dimensionally continuous network morphologies is of special interest in this study. Since these nanostructures considerably impact the material properties, fundamental knowledge for designing ABC systems have high technological importance for realizing applications in the areas of nanofabrication, nanoporous media, separation membranes, drug delivery and high surface area catalysts. A comprehensive framework was developed to describe the phase behavior of the ISO triblock copolymers at weak to intermediate segregation strengths spanning a wide range of composition. Phases were characterized through a combination of characterization techniques, including small angle x-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with previous investigations on ISO, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O70), double gyroid (Q230), alternating gyroid (Q214), hexagonal (HEX), and body-centered cubic (BCC). The phase map was found to be somewhat asymmetric around the fI = fO isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation. Strategies of blending homopolymers with ISO triblock copolymer were employed for studying the swelling properties of a lamellar state. Results demonstrate that lamellar domains swell or shrink depending upon the type of homopolymer that was mixed. The results provide insight into the chain conformation of ABC triblock copolymers, where the B blocks are completely bridged across the adjacent A and C domains. In the final part of the thesis, the swelling properties were used to study the directed assembly of ABC triblock copolymers on chemically nanopatterned surfaces.

  2. Modeling search engine effectiveness for federated search

    Microsoft Academic Search

    Luo Si; Jamie Callan

    2005-01-01

    Federated search links multiple search engines into a single, virtual search system. Most prior research of federated search focused on selecting search engines that have the most relevant contents, but ignored the retrieval effectiveness of individual search engines. This omission can cause serious problems when federating search engines of different qualities.This paper proposes a federated search technique that uses utility

  3. Earth systems engineering management: human behavior, technology and sustainability

    Microsoft Academic Search

    Michael E. Gorman

    2005-01-01

    This paper describes a framework for collaboration on environmental thinking and management, including three types of multi-disciplinary trading zones and three types of shared expertise. Getting agreement among multiple stakeholders requires the exercise of moral imagination, which involves:•Perceiving one's own mental model of a system, both as it exists (descriptive) and as one would like it to be (normative).•Comparing different

  4. ZMOTTO- MODELING THE INTERNAL COMBUSTION ENGINE

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.

    1994-01-01

    The ZMOTTO program was developed to model mathematically a spark-ignited internal combustion engine. ZMOTTO is a large, general purpose program whose calculations can be established at five levels of sophistication. These five models range from an ideal cycle requiring only thermodynamic properties, to a very complex representation demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. ZMOTTO is a flexible and computationally economical program based on a system of ordinary differential equations for cylinder-averaged properties. The calculations assume that heat transfer is expressed in terms of a heat transfer coefficient and that the cylinder average of kinetic plus potential energies remains constant. During combustion, the pressures of burned and unburned gases are assumed equal and their heat transfer areas are assumed proportional to their respective mass fractions. Even the simplest ZMOTTO model provides for residual gas effects, spark advance, exhaust gas recirculation, supercharging, and throttling. In the more complex models, 1) finite rate chemistry replaces equilibrium chemistry in descriptions of both the flame and the burned gases, 2) poppet valve formulas represent fluid flow instead of a zero pressure drop flow, and 3) flame propagation is modeled by mass burning equations instead of as an instantaneous process. Input to ZMOTTO is determined by the model chosen. Thermodynamic data is required for all models. Transport properties and chemical kinetics data are required only as the model complexity grows. Other input includes engine geometry, working fluid composition, operating characteristics, and intake/exhaust data. ZMOTTO accommodates a broad spectrum of reactants. The program will calculate many Otto cycle performance parameters for a number of consecutive cycles (a cycle being an interval of 720 crankangle degrees). A typical case will have a number of initial ideal cycles and progress through levels of nonideal cycles. ZMOTTO has restart capabilities and permits multicycle calculations with parameters varying from cycle to cycle. ZMOTTO is written in FORTRAN IV (IBM Level H) but has also been compiled with IBM VSFORTRAN (1977 standard). It was developed on an IBM 3033 under the TSS operating system and has also been implemented under MVS. Approximately 412K of 8 bit bytes of central memory are required in a nonpaging environment. ZMOTTO was developed in 1985.

  5. Software Engineering Laboratory (SEL) cleanroom process model

    NASA Technical Reports Server (NTRS)

    Green, Scott; Basili, Victor; Godfrey, Sally; Mcgarry, Frank; Pajerski, Rose; Waligora, Sharon

    1991-01-01

    The Software Engineering Laboratory (SEL) cleanroom process model is described. The term 'cleanroom' originates in the integrated circuit (IC) production process, where IC's are assembled in dust free 'clean rooms' to prevent the destructive effects of dust. When applying the clean room methodology to the development of software systems, the primary focus is on software defect prevention rather than defect removal. The model is based on data and analysis from previous cleanroom efforts within the SEL and is tailored to serve as a guideline in applying the methodology to future production software efforts. The phases that are part of the process model life cycle from the delivery of requirements to the start of acceptance testing are described. For each defined phase, a set of specific activities is discussed, and the appropriate data flow is described. Pertinent managerial issues, key similarities and differences between the SEL's cleanroom process model and the standard development approach used on SEL projects, and significant lessons learned from prior cleanroom projects are presented. It is intended that the process model described here will be further tailored as additional SEL cleanroom projects are analyzed.

  6. 17. YAZOO BACKWATER PUMPING STATION MODEL, YAZOO RIVER BASIN. ENGINEERS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. YAZOO BACKWATER PUMPING STATION MODEL, YAZOO RIVER BASIN. ENGINEERS EXAMINING MODEL PUMPS, VIEW FROM MODEL BED. - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

  7. Exploiting Models of Molecular Evolution to Efficiently Direct Protein Engineering

    E-print Network

    Gaucher, Eric

    Exploiting Models of Molecular Evolution to Efficiently Direct Protein Engineering Megan F. Cole Ó Springer Science+Business Media, LLC 2010 Abstract Directed evolution and protein engineering evolution and protein engineering that exploits phylogenetic and sequence analyses to identify amino acid

  8. MODELING AND CONTROL OF A DIESEL HCCI ENGINE

    E-print Network

    Paris-Sud XI, Université de

    MODELING AND CONTROL OF A DIESEL HCCI ENGINE J. Chauvin A. Albrecht G. Corde N. Petit Institut Abstract: This article focuses on the control of a Diesel engine airpath. We propose a detailed description of the airpath of a Diesel HCCI engine supported by experimental results. Moreover, we propose a simple, yet

  9. Polynomial control of nonlinear turbocharged diesel engine model

    Microsoft Academic Search

    M. Ayadi; Nicolas Langlois; H. Chafouk

    2004-01-01

    In this paper, a polynomial controller based on the flatness property is designed for a diesel engine equipped with a variable geometry turbocharger (VGT) and an exhaust gas recirculation (EGR) valve. These two components have widely contributed to reduce the pollutant emission and to improve engine performance. For the control design, a simplified nonlinear model of the diesel engine is

  10. Enforcing Strict Model-View Separation in Template Engines

    E-print Network

    Rollins, Sami

    Enforcing Strict Model-View Separation in Template Engines Nominated for best paper Terence Parr: thou shalt separate business logic from display. Ironically, almost all template engines allow violation of this separation prin- ciple, which is the very impetus for HTML template engine devel- opment

  11. Future Modeling Needs in Pulse Detonation Rocket Engine Design

    NASA Technical Reports Server (NTRS)

    Meade, Brian; Talley, Doug; Mueller, Donn; Tew, Dave; Guidos, Mike; Seymour, Dave

    2001-01-01

    This paper presents a performance model rocket engine design that takes advantage of pulse detonation to generate thrust. The contents include: 1) Introduction to the Pulse Detonation Rocket Engine (PDRE); 2) PDRE modeling issues and options; 3) Discussion of the PDRE Performance Workshop held at Marshall Space Flight Center; and 4) Identify needs involving an open performance model for Pulse Detonation Rocket Engines. This paper is in viewgraph form.

  12. Physical modelling in Geotechnical Earthquake Engineering – 2: Session Report

    E-print Network

    Madabhushi, Gopal

    2015-01-01

    International Journal of Physical Modelling in Geotechnics Physical modelling in Geotechnical Earthquake Engineering --Manuscript Draft-- Manuscript Number: IJPMG-D-14-00033R1 Full Title: Physical modelling in Geotechnical Earthquake Engineering... an important role in Geotechnical Earthquake Engineering. It is used to understand failure mechanisms and study the dynamic behaviour of a wide variety of dynamic problems with earthquake and other dynamic loading. As in the previous ICPMG conferences, Perth...

  13. [The contagious behavior model on the basis of rat drinking behavior].

    PubMed

    Ivanov, D G; Semenov, A N; Krupina, N A

    2014-01-01

    In work, the attempt of contagious behavior modeling on the basis of rat drinking behavior was made. Rats' behavior was observed in home cage with two bottles. The rat without drinking motivation (viewer) was placed in the cage for adaptation. The rat-demonstrator was placed into the same cage 3 minutes later. If the viewer was tested with drink-motivated demonstrator, it had less latency of approach to bottles, higher frequency of approaches and increased drinking behavior time than the rat tested with unmotivated demonstrator or the rat tested without demonstrator. The intragastric infusion of coffee increased frequency of approaches to demonstrated bottle. Phenazepam intragastric injection decreased frequency of approaches and drinking behavior time at demonstrated bottle. The results suggest that drugs may affect rat contagious behavior based on drinking behavior. PMID:25975147

  14. Computational modeling and experimental validation of odor detection behaviors of classically conditioned parasitic wasp, Microplitis croceipes.

    PubMed

    Zhou, Zhongkun; Kulasiri, Don; Samarasinghe, Sandhya; Rains, Glen; Olson, Dawn M

    2015-03-01

    A prototype chemical sensor named Wasp hound® that utilizes five classically conditioned parasitoid wasps, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), to detect volatile odors was successfully implemented in a previous study. To improve the odor-detecting ability of Wasp Hound®, searching behaviors of an individual wasp in a confined area are studied and modeled through stochastic differential equations in this paper. The wasps are conditioned to 20 mg of coffee when associated with food and subsequently, tested to 5, 10, 20, and 40 mg of coffee. A stochastic model is developed and validated based on three positive behavioral responses (walking, rotation around odor source, and self-rotation) from conditioned wasps at four different test dosages. The model is capable to reproducing the behaviors of conditioned wasps, and can be used to improve the ability of Wasp Hound® to assess changes in odor concentration. The model simulation results show the behaviors of conditioned wasps are significantly different when tested at different coffee dosages. We conjecture that the searching behaviors of conditioned wasps are based on the temporal and spatial neuron activity of olfactory receptor neurons and glomeruli, which are strongly correlated to the training dosages. The overall results demonstrate the utility of mathematical models for interpreting experimental observations, gaining novel insights into the dynamic behavior of classically conditioned wasps, as well as broadening the practical uses of Wasp Hound. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 31:596-606, 2015. PMID:25482381

  15. Generating Phenotypical Erroneous Human Behavior to Evaluate Human-automation Interaction Using Model Checking

    PubMed Central

    Bolton, Matthew L.; Bass, Ellen J.; Siminiceanu, Radu I.

    2012-01-01

    Breakdowns in complex systems often occur as a result of system elements interacting in unanticipated ways. In systems with human operators, human-automation interaction associated with both normative and erroneous human behavior can contribute to such failures. Model-driven design and analysis techniques provide engineers with formal methods tools and techniques capable of evaluating how human behavior can contribute to system failures. This paper presents a novel method for automatically generating task analytic models encompassing both normative and erroneous human behavior from normative task models. The generated erroneous behavior is capable of replicating Hollnagel’s zero-order phenotypes of erroneous action for omissions, jumps, repetitions, and intrusions. Multiple phenotypical acts can occur in sequence, thus allowing for the generation of higher order phenotypes. The task behavior model pattern capable of generating erroneous behavior can be integrated into a formal system model so that system safety properties can be formally verified with a model checker. This allows analysts to prove that a human-automation interactive system (as represented by the model) will or will not satisfy safety properties with both normative and generated erroneous human behavior. We present benchmarks related to the size of the statespace and verification time of models to show how the erroneous human behavior generation process scales. We demonstrate the method with a case study: the operation of a radiation therapy machine. A potential problem resulting from a generated erroneous human action is discovered. A design intervention is presented which prevents this problem from occurring. We discuss how our method could be used to evaluate larger applications and recommend future paths of development. PMID:23105914

  16. Modelling of diesel engine fuelled with biodiesel using engine simulation software

    NASA Astrophysics Data System (ADS)

    Said, Mohd Farid Muhamad; Said, Mazlan; Aziz, Azhar Abdul

    2012-06-01

    This paper is about modelling of a diesel engine that operates using biodiesel fuels. The model is used to simulate or predict the performance and combustion of the engine by simplified the geometry of engine component in the software. The model is produced using one-dimensional (1D) engine simulation software called GT-Power. The fuel properties library in the software is expanded to include palm oil based biodiesel fuels. Experimental works are performed to investigate the effect of biodiesel fuels on the heat release profiles and the engine performance curves. The model is validated with experimental data and good agreement is observed. The simulation results show that combustion characteristics and engine performances differ when biodiesel fuels are used instead of no. 2 diesel fuel.

  17. Towards a detailed soot model for internal combustion engines

    Microsoft Academic Search

    Sebastian Mosbach; Matthew S. Celnik; Abhijeet Raj; Markus Kraft; Hongzhi R. Zhang; Shuichi Kubo; Kyoung-Oh Kim

    2009-01-01

    In this work, we present a detailed model for the formation of soot in internal combustion engines describing not only bulk quantities such as soot mass, number density, volume fraction, and surface area but also the morphology and chemical composition of soot aggregates. The new model is based on the Stochastic Reactor Model (SRM) engine code, which uses detailed chemistry

  18. Expanding the Use of Solid Modeling throughout the Engineering Curriculum.

    ERIC Educational Resources Information Center

    Baxter, Douglas H.

    2001-01-01

    Presents the initial work that Rensselaer Polytechnic Institute has done to integrate solid modeling throughout the engineering curriculum. Aims to provide students the opportunity to use their solid modeling skills in several courses and show students how solid modeling tools can be used to help solve a variety of engineering problems.…

  19. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    ERIC Educational Resources Information Center

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  20. The Efficacy of a New Model to Explain Exercise Behavior.

    ERIC Educational Resources Information Center

    Noland, Melody Powers; And Others

    An attempt was made to determine what factors are important in a person's decision to engage in regular, vigorous activity. An Exercise Behavior Model was developed for the purpose of explaining exercise behavior. The model assumes that a person has four major predispositions or inclinations, which influence a readiness to exercise: (1) locus of…

  1. Chaotic behavior observations in a power system model

    Microsoft Academic Search

    X. Li; C. A. Cañizares

    2009-01-01

    Chaotic behavior in power systems has been studied in relatively simple and theoretical system models, where some particular assumptions are made to represent the system as a set of ordinary differential equations (ODE), using ldquospecialrdquo nonlinear system analysis tools. In this paper, chaotic behavior on the IEEE 14-bus benchmark system, using a transient stability model and its associated differential-algebraic equations

  2. Combustion system CFD modeling at GE Aircraft Engines

    NASA Technical Reports Server (NTRS)

    Burrus, D.; Mongia, H.; Tolpadi, Anil K.; Correa, S.; Braaten, M.

    1995-01-01

    This viewgraph presentation discusses key features of current combustion system CFD modeling capabilities at GE Aircraft Engines provided by the CONCERT code; CONCERT development history; modeling applied for designing engine combustion systems; modeling applied to improve fundamental understanding; CONCERT3D results for current production combustors; CONCERT3D model of NASA/GE E3 combustor; HYBRID CONCERT CFD/Monte-Carlo modeling approach; and future modeling directions.

  3. The role of behavior in translational models for psychopathology: functionality and dysfunctional behaviors.

    PubMed

    Blanchard, D Caroline; Summers, Cliff H; Blanchard, Robert J

    2013-09-01

    The history of science has frequently included a problem-based impetus toward research that can be translated expeditiously into solutions. A current problem is that psychopathologies, typically chronic, contribute hugely to the economic and social burden of medical care, especially in the United States. For behavioral neuroscientists a psychopathology-aimed translational research emphasis particularly involves animal models to facilitate the experimental and invasive work necessary to an understanding of the biology of normal and aberrant behavior. When the etiology of a particular psychopathology is unknown, and there are no specific biomarkers, behavioral parallels between the focal disorder and its putative models become crucial elements in assessing model validity. Evaluation of these parallels is frequently neglected, reflecting in part the lack of a systematic conceptualization of the organization of behavior and how this may be conserved across species. Recent work specifically attempting to bridge this gap suggests that analysis of behaviors that are functional - adaptive in crucial situations such as danger or social contexts - can facilitate an understanding of the parallels between behaviors of human and nonhuman species, including the dysfunctional behaviors of psycho pathologies. As research with animal models comes to provide a more systematic analysis of particular behaviors and their adaptive functions, cross-talk between model and focal psychopathology may be advantageous to understanding both. PMID:23791787

  4. MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 1 Modeling and Simulating Human Teamwork

    E-print Network

    MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 1 Modeling and Simulating Human Teamwork Behaviors #12;MODELING AND SIMULATING HUMAN TEAMWORK BEHAVIORS 2 Abstract Among researchers in multi-agent systems there has been growing interest in using intelligent agents to model and simulate human teamwork

  5. Predictive models of human supervisory control behavioral patterns using hidden semi-Markov models

    E-print Network

    Cummings, Mary "Missy"

    Predictive models of human supervisory control behavioral patterns using hidden semi-Markov models Unmanned vehicles Operator model Pattern recognition Human behavioral patterns a b s t r a c t Behavioral 31 March 2011 Accepted 21 April 2011 Keywords: Hidden semi-Markov models Human supervisory control

  6. Modular Neural Networks for Model-Free Behavioral Learning

    Microsoft Academic Search

    Johane Takeuchi; Osamu Shouno; Hiroshi Tsujino

    2008-01-01

    Future robots\\/agents will need to perform situation specific behaviors for each user. To cope with diverse and unexpected\\u000a situations, model-free behavioral learning is required. We have constructed a modular neural network model based on reinforcement\\u000a learning and demonstrated that the model can learn multiple kinds of state transitions with the same architectures and parameter\\u000a values, and without pre-designed models of

  7. Testing variations of Fishbein's behavioral intention model within a consumer behavior context

    Microsoft Academic Search

    William O. Bearden; Arch G. Woodside

    1977-01-01

    Tested variations of M. Fishbein's (1967, 1975) extended behavioral intention model across 4 brands of beer for 172 males and across 5 brands of soft drinks for 184 females. Respondents were members of the University of South Carolina Consumer Panel. Multiple regression and correlation analyses were employed to assess the hypothesized relationships between behavioral intentions, attitudes, normative beliefs, and beliefs

  8. Theory development for HIV behavioral health: empirical validation of behavior health models specific to HIV risk

    Microsoft Academic Search

    Dorian E. Traube; Ian W. Holloway; Lana Smith

    2011-01-01

    In the presence of numerous health behavior theories, it is difficult to determine which of the many theories is most precise in explaining health-related behavior. New models continue to be introduced to the field, despite already existing disparity, overlap, and lack of unification among health promotion theories. This paper will provide an overview of current arguments and frameworks for testing

  9. Calibrating Bayesian Network Representations of Social-Behavioral Models

    SciTech Connect

    Whitney, Paul D.; Walsh, Stephen J.

    2010-04-08

    While human behavior has long been studied, recent and ongoing advances in computational modeling present opportunities for recasting research outcomes in human behavior. In this paper we describe how Bayesian networks can represent outcomes of human behavior research. We demonstrate a Bayesian network that represents political radicalization research – and show a corresponding visual representation of aspects of this research outcome. Since Bayesian networks can be quantitatively compared with external observations, the representation can also be used for empirical assessments of the research which the network summarizes. For a political radicalization model based on published research, we show this empirical comparison with data taken from the Minorities at Risk Organizational Behaviors database.

  10. Engineering Glass Passivation Layers -Model Results

    SciTech Connect

    Skorski, Daniel C.; Ryan, Joseph V.; Strachan, Denis M.; Lepry, William C.

    2011-08-08

    The immobilization of radioactive waste into glass waste forms is a baseline process of nuclear waste management not only in the United States, but worldwide. The rate of radionuclide release from these glasses is a critical measure of the quality of the waste form. Over long-term tests and using extrapolations of ancient analogues, it has been shown that well designed glasses exhibit a dissolution rate that quickly decreases to a slow residual rate for the lifetime of the glass. The mechanistic cause of this decreased corrosion rate is a subject of debate, with one of the major theories suggesting that the decrease is caused by the formation of corrosion products in such a manner as to present a diffusion barrier on the surface of the glass. Although there is much evidence of this type of mechanism, there has been no attempt to engineer the effect to maximize the passivating qualities of the corrosion products. This study represents the first attempt to engineer the creation of passivating phases on the surface of glasses. Our approach utilizes interactions between the dissolving glass and elements from the disposal environment to create impermeable capping layers. By drawing from other corrosion studies in areas where passivation layers have been successfully engineered to protect the bulk material, we present here a report on mineral phases that are likely have a morphological tendency to encrust the surface of the glass. Our modeling has focused on using the AFCI glass system in a carbonate, sulfate, and phosphate rich environment. We evaluate the minerals predicted to form to determine the likelihood of the formation of a protective layer on the surface of the glass. We have also modeled individual ions in solutions vs. pH and the addition of aluminum and silicon. These results allow us to understand the pH and ion concentration dependence of mineral formation. We have determined that iron minerals are likely to form a complete incrustation layer and we plan to look more closely at Vivianite [Fe3(PO4)2-8(H2O)] and Siderite [FeCO3] in the next stage of the project.

  11. Reliable software systems via chains of object models with provably correct behavior

    SciTech Connect

    Yakhnis, A.; Yakhnis, V.

    1996-05-17

    This work addresses specification and design of reliable safety-critical systems, such as nuclear reactor control systems. Reliability concerns are addressed in complimentary fashion by different fields. Reliability engineers build software reliability models, etc. Safety engineers focus on prevention of potential harmful effects of systems on environment. Software/hardware correctness engineers focus on production of reliable systems on the basis of mathematical proofs. The authors think that correctness may be a crucial guiding issue in the development of reliable safety-critical systems. However, purely formal approaches are not adequate for the task, because they neglect the connection with the informal customer requirements. They alleviate that as follows. First, on the basis of the requirements, they build a model of the system interactions with the environment, where the system is viewed as a black box. They will provide foundations for automated tools which will (a) demonstrate to the customer that all of the scenarios of system behavior are presented in the model, (b) uncover scenarios not present in the requirements, and (c) uncover inconsistent scenarios. The developers will work with the customer until the black box model will not possess scenarios (b) and (c) above. Second, the authors will build a chain of several increasingly detailed models, where the first model is the black box model and the last model serves to automatically generated proved executable code. The behavior of each model will be proved to conform to the behavior of the previous one. They build each model as a cluster of interactive concurrent objects, thus they allow both top-down and bottom-up development.

  12. Modeling of hybrid vehicle fuel economy and fuel engine efficiency

    NASA Astrophysics Data System (ADS)

    Wu, Wei

    "Near-CV" (i.e., near-conventional vehicle) hybrid vehicles, with an internal combustion engine, and a supplementary storage with low-weight, low-energy but high-power capacity, are analyzed. This design avoids the shortcoming of the "near-EV" and the "dual-mode" hybrid vehicles that need a large energy storage system (in terms of energy capacity and weight). The small storage is used to optimize engine energy management and can provide power when needed. The energy advantage of the "near-CV" design is to reduce reliance on the engine at low power, to enable regenerative braking, and to provide good performance with a small engine. The fuel consumption of internal combustion engines, which might be applied to hybrid vehicles, is analyzed by building simple analytical models that reflect the engines' energy loss characteristics. Both diesel and gasoline engines are modeled. The simple analytical models describe engine fuel consumption at any speed and load point by describing the engine's indicated efficiency and friction. The engine's indicated efficiency and heat loss are described in terms of several easy-to-obtain engine parameters, e.g., compression ratio, displacement, bore and stroke. Engine friction is described in terms of parameters obtained by fitting available fuel measurements on several diesel and spark-ignition engines. The engine models developed are shown to conform closely to experimental fuel consumption and motored friction data. A model of the energy use of "near-CV" hybrid vehicles with different storage mechanism is created, based on simple algebraic description of the components. With powertrain downsizing and hybridization, a "near-CV" hybrid vehicle can obtain a factor of approximately two in overall fuel efficiency (mpg) improvement, without considering reductions in the vehicle load.

  13. Neural Modeling and Control of Diesel Engine with Pollution Constraints

    E-print Network

    Ouladsine, Mustapha; Dovifaaz, Xavier; 10.1007/s10846-005-3806-y

    2009-01-01

    The paper describes a neural approach for modelling and control of a turbocharged Diesel engine. A neural model, whose structure is mainly based on some physical equations describing the engine behaviour, is built for the rotation speed and the exhaust gas opacity. The model is composed of three interconnected neural submodels, each of them constituting a nonlinear multi-input single-output error model. The structural identi?cation and the parameter estimation from data gathered on a real engine are described. The neural direct model is then used to determine a neural controller of the engine, in a specialized training scheme minimising a multivariable criterion. Simulations show the effect of the pollution constraint weighting on a trajectory tracking of the engine speed. Neural networks, which are ?exible and parsimonious nonlinear black-box models, with universal approximation capabilities, can accurately describe or control complex nonlinear systems, with little a priori theoretical knowledge. The present...

  14. Animal Models for the Evaluation of Tissue Engineering Constructs

    Microsoft Academic Search

    Daniel A. W. Oortgiesen; Gert J. Meijer; Rob B. M. Vries; X. Frank Walboomers; John A. Jansen

    \\u000a In the last decade, tissue engineering has attracted a considerable amount of attention in medical research. Obviously, tissue-engineered\\u000a constructs need to be tested for their safety and efficacy before they can be used in the daily clinic. At present, animal\\u000a models offer the best possibility to do so. Each medical specialty favors its own specific model to test tissue-engineered\\u000a constructs.

  15. A behavior-based circuit model of how outcome expectations organize learned behavior in larval Drosophila.

    PubMed

    Schleyer, Michael; Saumweber, Timo; Nahrendorf, Wiebke; Fischer, Benjamin; von Alpen, Désirée; Pauls, Dennis; Thum, Andreas; Gerber, Bertram

    2011-10-01

    Drosophila larvae combine a numerically simple brain, a correspondingly moderate behavioral complexity, and the availability of a rich toolbox for transgenic manipulation. This makes them attractive as a study case when trying to achieve a circuit-level understanding of behavior organization. From a series of behavioral experiments, we suggest a circuitry of chemosensory processing, odor-tastant memory trace formation, and the "decision" process to behaviorally express these memory traces--or not. The model incorporates statements about the neuronal organization of innate vs. conditioned chemosensory behavior, and the types of interaction between olfactory and gustatory pathways during the establishment as well as the behavioral expression of odor-tastant memory traces. It in particular suggests that innate olfactory behavior is responsive in nature, whereas conditioned olfactory behavior is captured better when seen as an action in pursuit of its outcome. It incorporates the available neuroanatomical and behavioral data and thus should be useful as scaffold for the ongoing investigations of the chemo-behavioral system in larval Drosophila. PMID:21946956

  16. A model reduction case study: Automotive engine air path

    Microsoft Academic Search

    Oskar Nilsson; Anders Rantzer; Jonathan Chauvin

    2006-01-01

    Low complexity plant models are essential for model based control design. Often a detailed high order model is available and simplification to a low order approximative model is needed. This paper presents a case study of two model reduction methodologies applied on the automotive engine air path. The first methodology is based on balanced truncation of models obtained by linearization

  17. Formal Model Engineering for Embedded Systems Using Real-Time Maude

    E-print Network

    Ölveczky, Peter Csaba

    2011-01-01

    This paper motivates why Real-Time Maude should be well suited to provide a formal semantics and formal analysis capabilities to modeling languages for embedded systems. One can then use the code generation facilities of the tools for the modeling languages to automatically synthesize Real-Time Maude verification models from design models, enabling a formal model engineering process that combines the convenience of modeling using an informal but intuitive modeling language with formal verification. We give a brief overview six fairly different modeling formalisms for which Real-Time Maude has provided the formal semantics and (possibly) formal analysis. These models include behavioral subsets of the avionics modeling standard AADL, Ptolemy II discrete-event models, two EMF-based timed model transformation systems, and a modeling language for handset software.

  18. Behavior-Based Credit Card Fraud Detecting Model

    Microsoft Academic Search

    Yongbin Zhang; Fucheng You; Huaqun Liu

    2009-01-01

    Credit card frauds,which always cause great loss for credit card holder, is also a big problem for financial banks. A credit card fraud detecting model is established based on the behavior patterns of the credit card holder.Different with traditional models which were based on demographic and economic information,this model detects credit card fraud with historical behavior patterns of the credit

  19. Traffic Behavior Recognition Using the Pachinko Allocation Model.

    PubMed

    Huynh-The, Thien; Banos, Oresti; Le, Ba-Vui; Bui, Dinh-Mao; Yoon, Yongik; Lee, Sungyoung

    2015-01-01

    CCTV-based behavior recognition systems have gained considerable attention in recent years in the transportation surveillance domain for identifying unusual patterns, such as traffic jams, accidents, dangerous driving and other abnormal behaviors. In this paper, a novel approach for traffic behavior modeling is presented for video-based road surveillance. The proposed system combines the pachinko allocation model (PAM) and support vector machine (SVM) for a hierarchical representation and identification of traffic behavior. A background subtraction technique using Gaussian mixture models (GMMs) and an object tracking mechanism based on Kalman filters are utilized to firstly construct the object trajectories. Then, the sparse features comprising the locations and directions of the moving objects are modeled by PAMinto traffic topics, namely activities and behaviors. As a key innovation, PAM captures not only the correlation among the activities, but also among the behaviors based on the arbitrary directed acyclic graph (DAG). The SVM classifier is then utilized on top to train and recognize the traffic activity and behavior. The proposed model shows more flexibility and greater expressive power than the commonly-used latent Dirichlet allocation (LDA) approach, leading to a higher recognition accuracy in the behavior classification. PMID:26151213

  20. The Advanced Modeling, Simulation and Analysis Capability Roadmap Vision for Engineering

    NASA Technical Reports Server (NTRS)

    Zang, Thomas; Lieber, Mike; Norton, Charles; Fucik, Karen

    2006-01-01

    This paper summarizes a subset of the Advanced Modeling Simulation and Analysis (AMSA) Capability Roadmap that was developed for NASA in 2005. The AMSA Capability Roadmap Team was chartered to "To identify what is needed to enhance NASA's capabilities to produce leading-edge exploration and science missions by improving engineering system development, operations, and science understanding through broad application of advanced modeling, simulation and analysis techniques." The AMSA roadmap stressed the need for integration, not just within the science, engineering and operations domains themselves, but also across these domains. Here we discuss the roadmap element pertaining to integration within the engineering domain, with a particular focus on implications for future observatory missions. The AMSA products supporting the system engineering function are mission information, bounds on information quality, and system validation guidance. The Engineering roadmap element contains 5 sub-elements: (1) Large-Scale Systems Models, (2) Anomalous Behavior Models, (3) advanced Uncertainty Models, (4) Virtual Testing Models, and (5) space-based Robotics Manufacture and Servicing Models.

  1. State variable modeling of the integrated engine and aircraft dynamics

    NASA Astrophysics Data System (ADS)

    Rotaru, Constantin; Sprinţu, Iuliana

    2014-12-01

    This study explores the dynamic characteristics of the combined aircraft-engine system, based on the general theory of the state variables for linear and nonlinear systems, with details leading first to the separate formulation of the longitudinal and the lateral directional state variable models, followed by the merging of the aircraft and engine models into a single state variable model. The linearized equations were expressed in a matrix form and the engine dynamics was included in terms of variation of thrust following a deflection of the throttle. The linear model of the shaft dynamics for a two-spool jet engine was derived by extending the one-spool model. The results include the discussion of the thrust effect upon the aircraft response when the thrust force associated with the engine has a sizable moment arm with respect to the aircraft center of gravity for creating a compensating moment.

  2. Analysis of radical behavior under knocking operation in a spark ignition engine

    SciTech Connect

    Ota, Yasushi; Komuro, Katsunori; Matsushima, Toshiyuki; Yoshida, Koji; Shoji, Hideo; Saima, Atsushi

    1999-07-01

    There are strong demands today to improve the thermal efficiency of internal combustion engines in order to promote energy conservation and the resolution of environmental issues. A major factor impeding further improvement of the thermal efficiency of spark-ignition engines is knocking. If knocking could be suppressed, it would allow the use of a higher compression ratio for improved thermal efficiency, and thereby reduce fuel consumption. As a result, atmospheric emissions of CO{sub 2} would also be reduced. The behavior of the end gas in an actual engine during the process from the onset of preflame reactions to the occurrence of knocking, including the chemical reactions involved, is still not clearly understood. This study focused on light emission behavior at wavelengths corresponding to the spectra of the formaldehyde, (HCHO, characteristic spectrum of 395.2 nm), HCO (329.8 nm) and OH (306.4 nm) radicals. Investigations were made of the role of low-temperature flames in the preflame reaction region of a spark-ignition engine under the occurrence of autoignition leading to knocking. The measurements obtained for HCHO when the blended fuel (20 RON) was used as the test fuel showed an increase in emission intensity in the early period of the preflame reactions under normal combustion, followed by a decline in intensity. Under a condition of severe knock induced by an overheated cylinder head, it was observed that the maximum emission intensity decreased. These tendencies are thought to correspond to the passage and degeneracy of a cool flame. When isooctane (100 RON) was used as the test fuel, the measurements obtained for HCHO showed an increase in emission intensity in the preflame reaction period, behavior thought to indicate the passage of a cool flame, but the characteristics associated with the degeneracy of a cool flame were not observed.

  3. Stepwise elastic behavior in a model elastomer.

    PubMed

    Bhawe, Dhananjay M; Cohen, Claude; Escobedo, Fernando A

    2004-12-17

    Monte Carlo simulations of an entanglement-free cross-linked polymer network of semiflexible chains reveal a peculiar stepwise elastic response. For increasing stress, step jumps in strain are observed that do not correlate with changes in the number of aligned chains. We show that this unusual behavior stems from the ability of the system to form multiple ordered chain domains that exclude the cross-linking species. This novel elastomer shows a toughening behavior similar to that observed in biological structural materials, such as muscle proteins and abalone shell adhesive. PMID:15697945

  4. Terrain and Behavior Modeling for Projecting Multistage Cyber Attacks

    E-print Network

    Jay Yang, Shanchieh

    Terrain and Behavior Modeling for Projecting Multistage Cyber Attacks Daniel Fava Jared Holsopple of intrusion alerts occurring on computer networks. Traced or tracked cyber attacks are the bases for threat likely next targets and predicting attacker behavior. A virtual cyber terrain is proposed for identifying

  5. Modeling the Antecedents of Proactive Behavior at Work

    Microsoft Academic Search

    Sharon K. Parker; Helen M. Williams; Nick Turner

    2006-01-01

    Using a sample of U.K. wire makers (N = 282), the authors tested a model in which personality and work environment antecedents affect proactive work behavior via cognitive-motivational mechanisms. Self-reported proactive work behaviors (proactive idea implementation and proactive problem solving) were validated against rater assessments for a subsample (n = 60) of wire makers. With the exception of supportive supervision,

  6. A Meta-Analytic Review of Behavior Modeling Training

    ERIC Educational Resources Information Center

    Taylor, Paul J.; Russ-Eft, Darlene F.; Chan, Daniel W. L.

    2005-01-01

    A meta-analysis of 117 studies evaluated the effects of behavior modeling training (BMT) on 6 training outcomes, across characteristics of training design. BMT effects were largest for learning outcomes, smaller for job behavior, and smaller still for results outcomes. Although BMT effects on declarative knowledge decayed over time, training…

  7. On a Multistable Dynamic Model of Behavioral and

    E-print Network

    Cottrell, Garrison W.

    On a Multistable Dynamic Model of Behavioral and Perceptual Infant Development T.D. Frank1 J. van development from the perspective of multistable competitive dynamic systems. Accordingly, behavioral modes or perceptual state is not predefined. Rather, we argue that during particular stages of maturation multiple

  8. Modeling Pollutant Emissions of Diesel Engine based on Kriging Models: a

    E-print Network

    Paris-Sud XI, Université de

    supply precious information for the engine tuning in the design stage. Keywords: Modelling, OptimizationModeling Pollutant Emissions of Diesel Engine based on Kriging Models: a Comparison between engine subject to legislative constraints on pollutant emissions, it is necessary to improve their design

  9. Modeling Browsing Behavior at Multiple Websites

    Microsoft Academic Search

    Young-Hoon Park; Peter S. Fader

    2004-01-01

    While there is a growing literature on investigating the Internet clickstream data collected for a single site, such datasets are inherently incomplete because they generally do not capture shopping behavior across multiple websites. A customer's visit patterns at one or more other sites may provide relevant information about the timing and frequency of his or her future visit patterns at

  10. Modeling crawling cell movement on soft engineered substrates

    NASA Astrophysics Data System (ADS)

    Aronson, Igor

    2014-03-01

    Self-propelled motion, emerging spontaneously or in response to external cues, is a hallmark of living organisms. Systems of self-propelled synthetic particles are also relevant for multiple applications, from targeted drug delivery to the design of self-healing materials. Self-propulsion relies on the force transfer to the surrounding. While self-propelled swimming in the bulk of liquids is fairly well characterized, many open questions remain in our understanding of self-propelled motion along substrates, such as in the case of crawling cells or related biomimetic objects. How is the force transfer organized and how does it interplay with the deformability of the moving object and the substrate? How do the spatially dependent traction distribution and adhesion dynamics give rise to complex cell behavior? How can we engineer a specific cell response on synthetic compliant substrates? Here we present a phase-field model for a crawling cell by incorporating locally resolved traction forces and substrate deformations. The model captures the generic structure of the traction force distribution and faithfully reproduces experimental observations, like the response of a cell on a gradient in substrate elasticity (durotaxis). It also exhibits complex modes of cell movement such as ``bipedal'' motion. Our work may guide experiments on cell traction force microscopy and substrate-based cell sorting and can be helpful for the design of biomimetic ``crawlers'' and active and reconfigurable self-healing materials. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Contract DE-AC02-06CH11357.

  11. A VARIATIONAL PROBLEM MODELLING BEHAVIOR OF UNORTHODOX SILICON CRYSTALS

    E-print Network

    of heavily boron-doped Silicon crystals revealed that these crystals were quite unorthodox A VARIATIONAL PROBLEM MODELLING BEHAVIOR OF UNORTHODOX SILICON CRYSTALS-terrace"] type surface [for a recent review see[JW99

  12. Some considerations for modeling the creep behavior of composite materials

    SciTech Connect

    Lara-Curzio, E.; Ferber, M.K.

    1994-05-01

    A simple treatment of the mechanics of creep in unidirectional composites is presented with the objective of stressing the need for using appropriate constitutive equations when modeling the behavior of the constituents. It is demonstrated that pseudo-constitutive relations, such as those obtained from constant stress creep experiments for example, can not be used to describe the mechanical behavior of the constituents when modeling the creep of composites. By describing the mechanical behavior of the composite constituents using linear viscoelastic models, an analysis is presented to assess the type of errors which are incurred when inappropriate constitutive relations are used. Other considerations for modeling the creep behavior of ceramic matrix composites are discussed.

  13. Data-driven models for uncertainty and behavior

    E-print Network

    Gupta, Vishal, Ph. D. Massachusetts Institute of Technology

    2014-01-01

    The last decade has seen an explosion in the availability of data. In this thesis, we propose new techniques to leverage these data to tractably model uncertainty and behavior. Specifically, this thesis consists of three ...

  14. A Robot Model of Function Behavior in C/C++.

    ERIC Educational Resources Information Center

    Molluzzo, John C.

    2002-01-01

    Discussion of students' difficulties in C and C++ courses focuses on the function concept. Discusses function behavior through a model that uses a robot and its specially constructed environment, and distinguishes between the terms argument and parameter. (Author/LRW)

  15. A simple generative model of collective online behavior.

    PubMed

    Gleeson, James P; Cellai, Davide; Onnela, Jukka-Pekka; Porter, Mason A; Reed-Tsochas, Felix

    2014-07-22

    Human activities increasingly take place in online environments, providing novel opportunities for relating individual behaviors to population-level outcomes. In this paper, we introduce a simple generative model for the collective behavior of millions of social networking site users who are deciding between different software applications. Our model incorporates two distinct mechanisms: one is associated with recent decisions of users, and the other reflects the cumulative popularity of each application. Importantly, although various combinations of the two mechanisms yield long-time behavior that is consistent with data, the only models that reproduce the observed temporal dynamics are those that strongly emphasize the recent popularity of applications over their cumulative popularity. This demonstrates--even when using purely observational data without experimental design--that temporal data-driven modeling can effectively distinguish between competing microscopic mechanisms, allowing us to uncover previously unidentified aspects of collective online behavior. PMID:25002470

  16. Human Performance Models of Pilot Behavior

    NASA Technical Reports Server (NTRS)

    Foyle, David C.; Hooey, Becky L.; Byrne, Michael D.; Deutsch, Stephen; Lebiere, Christian; Leiden, Ken; Wickens, Christopher D.; Corker, Kevin M.

    2005-01-01

    Five modeling teams from industry and academia were chosen by the NASA Aviation Safety and Security Program to develop human performance models (HPM) of pilots performing taxi operations and runway instrument approaches with and without advanced displays. One representative from each team will serve as a panelist to discuss their team s model architecture, augmentations and advancements to HPMs, and aviation-safety related lessons learned. Panelists will discuss how modeling results are influenced by a model s architecture and structure, the role of the external environment, specific modeling advances and future directions and challenges for human performance modeling in aviation.

  17. An approach towards building human behavior models automatically by observation

    Microsoft Academic Search

    Hans K. Fernlund; Avelino J. Gonzalez

    Abstract Modeling human behavior could be complicated and expensive. To be able to reduce these costs, new methodologies,and tools must be developed that automate the creation of building human,behavior models. We describe in this paper one way to accomplish this through the use of Genetic Programming,in conjunction with Context-Based Reasoning (CxBR). Context-Based Reasoning is based on the ,concept that humans

  18. Comparing Learning Techniques for Hidden Markov Models of Human Supervisory Control Behavior

    E-print Network

    Cummings, M. L.

    Models of human behaviors have been built using many different frameworks. In this paper, we make use of Hidden Markov Models (HMMs) applied to human supervisory control behaviors. More specifically, we model the behavior ...

  19. Methodologies for statistical behavioral modeling and simulation of complex analog integrated circuits 

    E-print Network

    Swidzinski, Jan

    1997-01-01

    transistors, statistical i-nodeling techniques for integrated circuits, statistical behavioral modeling of analog functional blocks, and finally statistical behavioral system level modeling and simulation. A full statistical model for the behavioral parameters...

  20. Engineering English: A Lexical Frequency Instructional Model

    ERIC Educational Resources Information Center

    Mudraya, Olga

    2006-01-01

    This paper argues for the integration of the lexical approach with a data-driven corpus-based methodology in English teaching for technical students, particularly students of Engineering. It presents the findings of the author's computer-aided research, which aimed to establish a frequency-based corpus of student engineering lexis. The Student…

  1. On the Limiting Behavior of MIMO Directional Models

    E-print Network

    Müller, Ralf R.

    On the Limiting Behavior of MIMO Directional Models M´erouane Debbah and Ralf R. M¨uller Vienna the distribution. · The proof uses tools of random matrix theory. 2 MIMO Model 2.1 Frequency MIMO Representation Tx, a model will be called capacity complying if it minimizes: 0 | F(IM ) - Fempirical(IM , f) |2 dIM Here

  2. A Model of a Mercury Arc Lamp's Terminal VI Behavior

    Microsoft Academic Search

    Edward L. Laskowski; John F. Donoghue

    1981-01-01

    A nonlinear dynamic model of the terminal voltagecurrent (V-I) characteristics of a mercury arc lamp operating at various power levels which can be used in the computer design of lamp ballast circuits is described. An experimental and efficient computational procedure is developed which determines the values for six model constants that cause the model to duplicate actual lamp behavior. This

  3. Mathematical Models and the Experimental Analysis of Behavior

    Microsoft Academic Search

    JAMES E. MAZUR

    2006-01-01

    The use of mathematical models in the experimental analysis of behavior has increased over the years, and they offer several advantages. Mathematical models require theorists to be precise and unambiguous, often allowing comparisons of competing theories that sound similar when stated in words. Sometimes different mathematical models may make equally accurate predictions for a large body of data. In such

  4. Modeling the dynamic behavior of supercapacitors using impedance spectroscopy

    Microsoft Academic Search

    S. Buller; E. Karden; D. Kok; R. W. De Doncker

    2002-01-01

    This paper presents a new approach of modeling the dynamic behavior of supercapacitors using impedance spectroscopy. The new Matlab\\/Simulink model can be used in simulating the voltage response and energy efficiency, e.g., for automotive power systems. The model in the frequency domain, the parameter calculation, as well as the inverse transformation into the time domain are discussed. Furthermore, simulation results

  5. Cascading Behavior in Large Blog Graphs Patterns and a model

    E-print Network

    Pratt, Vaughan

    Cascading Behavior in Large Blog Graphs Patterns and a model Jure Leskovec, Mary McGlohon, Christos of the questions that we address in this work. Our goal is to build a model that generates realistic cascades, so? What can we say about the size distribution of cascades? Finally, how can we build models that generate

  6. Cascading Behavior in Large Blog Graphs Patterns and a model

    E-print Network

    Cascading Behavior in Large Blog Graphs Patterns and a model Jure Leskovec, Mary McGlohon, Christos goal is to build a model that generates realistic cascades, so that it can help us with link prediction, how can we build models that generate realistic cascades? 1.1 Summary of findings and contributions

  7. Nonequilibrium thermodynamic models for the dynamic behavior of polycrystalline solids

    Microsoft Academic Search

    Xia Lu

    2002-01-01

    An approach to the modelling of the dynamic behavior of selected polycrystalline solids is presented. The approach is applied to model the heterogeneous plastic flow, viscous processes, thermal processes and nonequilibrium phase transition of metallic projectile materials like steel under high-strain rate conditions. Another application area is to model the linear dissipation (including mechanical, dielectric and piezoelectric dissipation) of piezoceramic

  8. Automatic Generation of Behavioral Hard Disk Drive Access Time Models

    E-print Network

    Maltzahn, Carlos

    Automatic Generation of Behavioral Hard Disk Drive Access Time Models Adam Crume, Carlos Maltzahn is a crucial part of pre- dicting hard disk drive performance. Existing approaches use white-box modeling assumptions, and less time. While previous research has created black-box models of hard disk drive

  9. Stepwise Elastic Behavior in a Model Elastomer

    Microsoft Academic Search

    Dhananjay M. Bhawe; Claude Cohen; Fernando A. Escobedo

    2004-01-01

    MonteCarlo simulations of an entanglement-free cross-linked polymer network of semiflexible chains reveal a peculiar stepwise elastic response. For increasing stress, step jumps in strain are observed that do not correlate with changes in the number of aligned chains. We show that this unusual behavior stems from the ability of the system to form multiple ordered chain domains that exclude the

  10. Using GP to Model Contextual Human Behavior Competitive with Human Modeling Performance

    E-print Network

    Fernandez, Thomas

    tactical human performance within simulated agents, with the Genetic Programming machine learning algorithmUsing GP to Model Contextual Human Behavior ­ Competitive with Human Modeling Performance Hans simulations require simulated agents with human behavior pattern. Creating such agents with realistic behavior

  11. A Model of Resurgence Based on Behavioral Momentum Theory

    PubMed Central

    Shahan, Timothy A; Sweeney, Mary M

    2011-01-01

    Resurgence is the reappearance of an extinguished behavior when an alternative behavior reinforced during extinction is subsequently placed on extinction. Resurgence is of particular interest because it may be a source of relapse to problem behavior following treatments involving alternative reinforcement. In this article we develop a quantitative model of resurgence based on the augmented model of extinction provided by behavioral momentum theory. The model suggests that alternative reinforcement during extinction of a target response acts as both an additional source of disruption during extinction and as a source of reinforcement in the context that increases the future strength of the target response. The model does a good job accounting for existing data in the resurgence literature and makes novel and testable predictions. Thus, the model appears to provide a framework for understanding resurgence and serves to integrate the phenomenon into the existing theoretical account of persistence provided by behavioral momentum theory. In addition, we discuss some potential implications of the model for further development of behavioral momentum theory. PMID:21541118

  12. Model-based observer: a gas turbine engine case study

    Microsoft Academic Search

    Oliver F. Qi; P. J. Gawthrop; N. R. L. Maccallum

    1992-01-01

    A model-based control approach to synthesizing a nonlinear controller for a single-spool gas turbine engine is described. Since the main control variable, engine thrust, cannot be directly measured, a model-based observer is considered to provide online estimation of the thrust for feedback control. Both proportional and proportional-integral (PI) observers have been used in the model-based observer design. The latter is

  13. Use of transport models for wildfire behavior simulations

    SciTech Connect

    Linn, R.R.; Harlow, F.H.

    1998-01-01

    Investigators have attempted to describe the behavior of wildfires for over fifty years. Current models for numerical description are mainly algebraic and based on statistical or empirical ideas. The authors have developed a transport model called FIRETEC. The use of transport formulations connects the propagation rates to the full conservation equations for energy, momentum, species concentrations, mass, and turbulence. In this paper, highlights of the model formulation and results are described. The goal of the FIRETEC model is to describe most probable average behavior of wildfires in a wide variety of conditions. FIRETEC represents the essence of the combination of many small-scale processes without resolving each process in complete detail.

  14. Premixed ignition behavior of C{sub 9} fatty acid esters: A motored engine study

    SciTech Connect

    Zhang, Yu.; Yang, Yi; Boehman, Andre L. [EMS Energy Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

    2009-06-15

    An experimental study on the premixed ignition behavior of C{sub 9} fatty acid esters has been conducted in a motored CFR engine. For each test fuel, the engine compression ratio was gradually increased from the lowest point (4.43) to the point where significant high temperature heat release (HTHR) was observed. The engine exhaust was sampled and analyzed through GC-FID/TCD and GC-MS. Combustion analysis showed that the four C{sub 9} fatty acid esters tested in this study exhibited evidently different ignition behavior. The magnitude of low temperature heat release (LTHR) follows the order, ethyl nonanoate > methyl nonanoate >> methyl 2-nonenoate > methyl 3-nonenoate. The lower oxidation reactivity for the unsaturated fatty acid esters in the low temperature regime can be explained by the reduced amount of six- or seven-membered transition state rings formed during the oxidation of the unsaturated esters due to the presence of a double bond in the aliphatic chain of the esters. The inhibition effect of the double bond on the low temperature oxidation reactivity of fatty acid esters becomes more pronounced as the double bond moves toward the central position of the aliphatic chain. GC-MS analysis of exhaust condensate collected under the engine conditions where only LTHR occurred showed that the alkyl chain of the saturated fatty acid esters participated in typical paraffin-like low temperature oxidation sequences. In contrast, for unsaturated fatty acid esters, the autoignition can undergo olefin ignition pathways. For all test compounds, the ester functional group remains largely intact during the early stage of oxidation. (author)

  15. Modeling synchronized calling behavior of Japanese tree frogs

    NASA Astrophysics Data System (ADS)

    Aihara, Ikkyu

    2009-07-01

    We experimentally observed synchronized calling behavior of male Japanese tree frogs Hyla japonica; namely, while isolated single frogs called nearly periodically, a pair of interacting frogs called synchronously almost in antiphase or inphase. In this study, we propose two types of phase-oscillator models on different degrees of approximations, which can quantitatively explain the phase and frequency properties in the experiment. Moreover, it should be noted that, although the second model is obtained by fitting to the experimental data of the two synchronized states, the model can also explain the transitory dynamics in the interactive calling behavior, namely, the shift from a transient inphase state to a stable antiphase state. We also discuss the biological relevance of the estimated parameter values to calling behavior of Japanese tree frogs and the possible biological meanings of the synchronized calling behavior.

  16. Case-Based Model Selection for Engineering Diagnosis

    Microsoft Academic Search

    Benny Raphael; Ian F. C. Smith

    1998-01-01

    This paper describes an approach to selecting appropriate causal models for engineering diagnosis. We have chosen a hybrid\\u000a approach which is a combination of model composition and model reuse. Model composition permits reasoning with multiple models\\u000a that contain explicit assumptions. Difficulties related to intractability during model composition are reduced by model reuse.\\u000a We are currently validating and testing the system

  17. Unnotched Charpy Impact Energy Transition Behavior of Austempered Engineering Grade Ductile Iron Castings

    NASA Astrophysics Data System (ADS)

    Kisakurek, Sukru Ergin; Ozel, Ahmet

    2014-04-01

    Unnotched Charpy impact energy transition behavior of five different engineering grade ductile iron castings, as specified by EN 1563 Standards, were examined in as-cast, as well as in austempered states. ADIs were produced with the maximum impact energy values permissible for the grades. Austempering treatment detrimented the sub-zero impact properties of the ferritic castings, but considerably enhanced those of the pearlitic-ferritic irons. The impact energy transition behavior of the austempered states of all the grades examined were noted to be determined by the progressive transformation of the unavoidable carbon-unsaturated and untransformed regions of the austenite remaining in the matrix of the austempered ductile iron to martensite with decreasing temperature.

  18. Modeling engine oil vaporization and transport of the oil vapor in the piston ring pack on internal combustion engines

    E-print Network

    Cho, Yeunwoo, 1973-

    2004-01-01

    A model was developed to study engine oil vaporization and oil vapor transport in the piston ring pack of internal combustion engines. With the assumption that the multi-grade oil can be modeled as a compound of several ...

  19. From transformation traces to transformation rules: Assisting Model Driven Engineering

    E-print Network

    Paris-Sud XI, Université de

    From transformation traces to transformation rules: Assisting Model Driven Engineering approach. In this paper we are interested in semi-automatically gen- erating labelled graph (model) transformations conform to a particu- lar syntax (meta-model). Those transformations are basic operations in model driven

  20. Controlling reactive behavior with consistent world modeling and reasoning

    NASA Astrophysics Data System (ADS)

    Bou-Ghannam, Akram A.

    1992-03-01

    Based on the philosophical view of reflexive behaviors and cognitive modules working in a complementary fashion, this paper proposes a hybrid decomposition of the control architecture for an intelligent, fully autonomous mobile robot. This architecture follows a parallel distributed decomposition and supports a hierarchy of control with lower-level reflexive type behaviors working in parallel with higher-level planning and map building modules. The behavior-based component of the system provides the basic instinctive competences for the robot while the cognitive part performs higher machine intelligence functions such as planning. The interface between the two components utilizes motivated behaviors implemented as part of the behavior-based system. A motivated behavior is one whose response is dictated mainly by the internal state (or the motivation state) of the robot. Thus, the cognitive planning activity can execute its plans by merely setting the motivation state of the robot and letting the behavior-based subsystem worry about the details of plan execution. The goal of such a hybrid architecture is to gain the real-time performance of a behavior-based system without losing the effectiveness of a general purpose world model and planner. We view world models as essential to intelligent interaction with the environment, providing a `bigger picture' for the robot when reactive behaviors encounter difficulty. We describe a live experimental run of our robot under hybrid control in an unknown and unstructured lab environment. This experiment demonstrated the validity of the proposed hybrid control architecture and the sensory knowledge integrator (the underlying model for the map-builder module) for the task of mapping the environment. Results of the emergent robot behavior and different map representations of the environment are presented and discussed.

  1. Model-Based Control of HCCI Engines Using Exhaust Recompression

    Microsoft Academic Search

    Nikhil Ravi; Matthew J. Roelle; Hsien-Hsin Liao; Adam F. Jungkunz; Chen-Fang Chang; J. Christian Gerdes

    2010-01-01

    Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling an HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the

  2. Modeling Student Interest in Science, Technology, Engineering and Mathematics

    Microsoft Academic Search

    Brian H. Wells; H. Alex Sanchez; Joanne M. Attridge

    2007-01-01

    This paper presents preliminary results of a Raytheon project that uses systems engineering techniques to understand the intricacies of the U.S. educational system and to assist in the evaluation of proposed system changes with a goal of doubling the numbers of science, technology, engineering and mathematics (STEM) college graduates by 2015. Specifically, a system dynamics model has been developed, the

  3. Building a search engine model with morphological normalization support

    Microsoft Academic Search

    Jure Mijic; J. Snajder

    2008-01-01

    Searching a collection of documents can seem like an easy task, but manipulating textual data can be difficult because the data are mostly unstructured. We undertook the task of building an effective search engine for a collection of Croatian legislative documents. The developed search engine model supports multiple modules for information retrieval. To improve the effectiveness of the retrieval, we

  4. Enabler 1 and 2 engine system design modeling and comparisons

    NASA Technical Reports Server (NTRS)

    Pelaccio, Dennis G.; Scheil, Christine M.

    1993-01-01

    Viewgraphs on Enabler 1 and 2 engine system design modeling and comparisons are presented. The objective of this research was to define a near-term solid-core nuclear thermal propulsion (NTP) engine system scaling database. A unified set of performance, weight, and size scaling data are identified and documented. Results should be useful to meet initial mission and concept design study requirements.

  5. On Gear Modelling in Multistage Rotary Vane Engines

    Microsoft Academic Search

    B. Librovich; R. W. Tucker; C. Wang

    2004-01-01

    A discussion of the dynamics of a multistage rotary vane engine is given in terms of a simplified model for combustion driving torques, power dissipation, and torque transmission. Torque transmission is effected by conjugate gear pairs attached to each unit of the engine. An argument for the design of such pairs is presented so that unwanted torque fluctuations in a

  6. Modeling and control of internal combustion engines using intelligent techniques

    Microsoft Academic Search

    Shaun H. Lee; Robert J. Howlett; Simon D. Walters; Cyril Crua

    2007-01-01

    This article will compare two different fuzzy-derived techniques for controlling small internal combustion engine and modeling fuel spray penetration in the cylinder of a diesel internal combustion engine. The first case study is implemented using conventional fuzzy-based paradigm, where human expertise and operator knowledge were used to select the parameters for the system. The second case study used an adaptive

  7. Development and testing of diesel engine CFD models

    Microsoft Academic Search

    R. D. Reitz; C. J. Rutland

    1995-01-01

    The development and validation of Computational Fluid Dynamic (CFD) models for diesel engine combustion and emissions is described. The complexity of diesel combustion requires simulations with many complex, interacting submodels in order to be successful. The review focuses on the current status of work at the University of Wisconsin Engine Research Center. The research program, which has been ongoing for

  8. Model-based Security Engineering for Real Jan Jurjens

    E-print Network

    Jurjens, Jan

    of bounded size such as security protocols, including [BAN89, KMM94, Low96, Pau98]. Unfortunately, dueModel-based Security Engineering for Real Jan J¨urjens Software & Systems Engineering, Dep based secure software en- gineering methodology and associated tool-support developed over the last few

  9. Use of genome-scale microbial models for metabolic engineering

    Microsoft Academic Search

    Kiran Raosaheb Patil; Mats Åkesson; Jens Nielsen

    2004-01-01

    Metabolic engineering serves as an integrated approach to design new cell factories by providing rational design procedures and valuable mathematical and experimental tools. Mathematical models have an important role for phenotypic analysis, but can also be used for the design of optimal metabolic network structures. The major challenge for metabolic engineering in the post-genomic era is to broaden its design

  10. The effect of a nematode parasite on feeding and dung-burying behavior of an ecosystem engineer.

    PubMed

    Boze, Broox G V; Moore, Janice

    2014-07-01

    Dung beetles (genus Phanaeus) consume feces in both their larval and adults forms and because of their unique dietary niche, and behaviors associated with the burial of feces, are considered ecosystem engineers. In addition, because these insects subsist on a diet composed exclusively of feces, it is likely they encounter parasitic propagules more frequently than other animals do. Parasites often alter their host's behavior, so we set out to test whether Physocephalus sexalatus (a cosmopolitan nematode parasite of ungulates) does so in ways that affect the dung beetle's role as an ecosystem engineer and/or its predator-prey relationships (transmission of the parasite). Classic tests of anti-predator behavior did not reveal behavioral differences based on the beetles' infection status. However, this parasite did alter the beetles' behaviors in ways that could be critical for its role in fecal processing and therefore ecosystem engineering. Infected beetles exhibited anorexic behavior and consumed only half the amount of feces ingested by similar uninfected beetles. Infected beetles also buried less feces and did so in tunnels that were significantly shorter than those created by uninfected beetles. Fecal burial is naturally beneficial because it aerates the soil, incorporates nitrogenous compounds, and increases the flow of water thereby making soil and pastureland more productive. We showed that the nematode parasite P. sexalatus itself becomes an ecosystem engineer as it modifies the behavior of its already influential intermediate host. PMID:24737785

  11. Augmented Network Model For Engineering System Design

    E-print Network

    de Weck, Olivier L.

    research (supply chains), electrical engineering (circuit (controls) theory), and more recently systems the components of a vehicle, the parts (or subsystems) of an airplane or the states of a formation of flying

  12. Iterative procedures for space shuttle main engine performance models

    NASA Technical Reports Server (NTRS)

    Santi, L. Michael

    1989-01-01

    Performance models of the Space Shuttle Main Engine (SSME) contain iterative strategies for determining approximate solutions to nonlinear equations reflecting fundamental mass, energy, and pressure balances within engine flow systems. Both univariate and multivariate Newton-Raphson algorithms are employed in the current version of the engine Test Information Program (TIP). Computational efficiency and reliability of these procedures is examined. A modified trust region form of the multivariate Newton-Raphson method is implemented and shown to be superior for off nominal engine performance predictions. A heuristic form of Broyden's Rank One method is also tested and favorable results based on this algorithm are presented.

  13. COMPBRN3. Modeling Compartment Fires Behavior

    SciTech Connect

    Ho, V.; Siu, N.; Apostolakis, G.; Flanagan, G. [Oak Ridge National Lab., TN (United States)

    1986-07-01

    COMPBRN3 is a deterministic fire hazards program designed for use in probabilistic analysis of fire growth in a particular room. This analysis is required when assessing the risk associated with fires in nuclear power plants. An air entrainment model is included which consists of a plume entrainment model, a wall jet entrainment model, and a model for the doorway mixing effect. Output available includes the total heat release rate of the fire, the temperature and thickness of the hot gas layer formed near the compartment ceiling, the mass burning rate for individual fuel elements, the surface temperature of the elements, and the thermal heat flux at user-specified locations.

  14. The effect of tissue-engineered cartilage biomechanical and biochemical properties on its post-implantation mechanical behavior.

    PubMed

    Khoshgoftar, Mehdi; Wilson, Wouter; Ito, Keita; van Donkelaar, Corrinus C

    2013-01-01

    The insufficient load-bearing capacity of today's tissue-engineered (TE) cartilage limits its clinical application. Focus has been on engineering cartilage with enhanced mechanical stiffness by reproducing native biochemical compositions. More recently, depth dependency of the biochemical content and the collagen network architecture has gained interest. However, it is unknown whether the mechanical performance of TE cartilage would benefit more from higher content of biochemical compositions or from achieving an appropriate collagen organization. Furthermore, the relative synthesis rate of collagen and proteoglycans during the TE process may affect implant performance. Such insights would assist tissue engineers to focus on those aspects that are most important. The aim of the present study is therefore to elucidate the relative importance of implant ground substance stiffness, collagen content, and collagen architecture of the implant, as well as the synthesis rate of the biochemical constituents for the post-implantation mechanical behavior of the implant. We approach this by computing the post-implantation mechanical conditions using a composition-based fibril-reinforced poro-viscoelastic swelling model of the medial tibia plateau. Results show that adverse implant composition and ultrastructure may lead to post-implantation excessive mechanical loads, with collagen orientation being the most critical variable. In addition, we predict that a faster synthesis rate of proteoglycans compared to that of collagen during TE culture may result in excessive loads on collagen fibers post-implantation. This indicates that even with similar final contents, constructs may behave differently depending on their development. Considering these aspects may help to engineer TE cartilage implants with improved survival rates. PMID:22389193

  15. Engine System Model Development for Nuclear Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Nelson, Karl W.; Simpson, Steven P.

    2006-01-01

    In order to design, analyze, and evaluate conceptual Nuclear Thermal Propulsion (NTP) engine systems, an improved NTP design and analysis tool has been developed. The NTP tool utilizes the Rocket Engine Transient Simulation (ROCETS) system tool and many of the routines from the Enabler reactor model found in Nuclear Engine System Simulation (NESS). Improved non-nuclear component models and an external shield model were added to the tool. With the addition of a nearly complete system reliability model, the tool will provide performance, sizing, and reliability data for NERVA-Derived NTP engine systems. A new detailed reactor model is also being developed and will replace Enabler. The new model will allow more flexibility in reactor geometry and include detailed thermal hydraulics and neutronics models. A description of the reactor, component, and reliability models is provided. Another key feature of the modeling process is the use of comprehensive spreadsheets for each engine case. The spreadsheets include individual worksheets for each subsystem with data, plots, and scaled figures, making the output very useful to each engineering discipline. Sample performance and sizing results with the Enabler reactor model are provided including sensitivities. Before selecting an engine design, all figures of merit must be considered including the overall impacts on the vehicle and mission. Evaluations based on key figures of merit of these results and results with the new reactor model will be performed. The impacts of clustering and external shielding will also be addressed. Over time, the reactor model will be upgraded to design and analyze other NTP concepts with CERMET and carbide fuel cores.

  16. Modeling User Behavior in Computer Learning Tasks.

    ERIC Educational Resources Information Center

    Mantei, Marilyn M.

    Model building techniques from Artifical Intelligence and Information-Processing Psychology are applied to human-computer interface tasks to evaluate existing interfaces and suggest new and better ones. The model is in the form of an augmented transition network (ATN) grammar which is built by applying grammar induction heuristics on a sequential…

  17. Engineered Barrier System: Physical and Chemical Environment Model

    SciTech Connect

    D. M. Jolley; R. Jarek; P. Mariner

    2004-02-09

    The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming by deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.

  18. Integration of engineering models in computer-aided preliminary design

    E-print Network

    Lajoie, Ronnie M.

    The problems of the integration of engineering models in computer-aided preliminary design are reviewed. This paper details the research, development, and testing of modifications to Paper Airplane, a LISP-based computer ...

  19. The Sikorsky Twin Engined Amphibian, Type S-38, Model 1928

    NASA Technical Reports Server (NTRS)

    1928-01-01

    The S-38, model 28 is a nine passenger Sesquiplane powered by two Pratt and Whitney Wasp 410 HP engines and is intended for routes where the ability to take off and land from both land and water is essential.

  20. Modeling Pedestrian's Conformity Violation Behavior: A Complex Network Based Approach

    PubMed Central

    Zhou, Zhuping; Hu, Qizhou; Wang, Wei

    2014-01-01

    Pedestrian injuries and fatalities present a problem all over the world. Pedestrian conformity violation behaviors, which lead to many pedestrian crashes, are common phenomena at the signalized intersections in China. The concepts and metrics of complex networks are applied to analyze the structural characteristics and evolution rules of pedestrian network about the conformity violation crossings. First, a network of pedestrians crossing the street is established, and the network's degree distributions are analyzed. Then, by using the basic idea of SI model, a spreading model of pedestrian illegal crossing behavior is proposed. Finally, through simulation analysis, pedestrian's illegal crossing behavior trends are obtained in different network structures and different spreading rates. Some conclusions are drawn: as the waiting time increases, more pedestrians will join in the violation crossing once a pedestrian crosses on red firstly. And pedestrian's conformity violation behavior will increase as the spreading rate increases. PMID:25530755

  1. Modeling pedestrian's conformity violation behavior: a complex network based approach.

    PubMed

    Zhou, Zhuping; Hu, Qizhou; Wang, Wei

    2014-01-01

    Pedestrian injuries and fatalities present a problem all over the world. Pedestrian conformity violation behaviors, which lead to many pedestrian crashes, are common phenomena at the signalized intersections in China. The concepts and metrics of complex networks are applied to analyze the structural characteristics and evolution rules of pedestrian network about the conformity violation crossings. First, a network of pedestrians crossing the street is established, and the network's degree distributions are analyzed. Then, by using the basic idea of SI model, a spreading model of pedestrian illegal crossing behavior is proposed. Finally, through simulation analysis, pedestrian's illegal crossing behavior trends are obtained in different network structures and different spreading rates. Some conclusions are drawn: as the waiting time increases, more pedestrians will join in the violation crossing once a pedestrian crosses on red firstly. And pedestrian's conformity violation behavior will increase as the spreading rate increases. PMID:25530755

  2. A Neurobehavioral Model of Flexible Spatial Language Behaviors

    PubMed Central

    Lipinski, John; Schneegans, Sebastian; Sandamirskaya, Yulia; Spencer, John P.; Schöner, Gregor

    2012-01-01

    We propose a neural dynamic model that specifies how low-level visual processes can be integrated with higher level cognition to achieve flexible spatial language behaviors. This model uses real-word visual input that is linked to relational spatial descriptions through a neural mechanism for reference frame transformations. We demonstrate that the system can extract spatial relations from visual scenes, select items based on relational spatial descriptions, and perform reference object selection in a single unified architecture. We further show that the performance of the system is consistent with behavioral data in humans by simulating results from 2 independent empirical studies, 1 spatial term rating task and 1 study of reference object selection behavior. The architecture we present thereby achieves a high degree of task flexibility under realistic stimulus conditions. At the same time, it also provides a detailed neural grounding for complex behavioral and cognitive processes. PMID:21517224

  3. Continuous-valued probabilistic behavior in a VLSI generative model.

    PubMed

    Chen, Hsin; Fleury, Patrice C D; Murray, Alan F

    2006-05-01

    This paper presents the VLSI implementation of the continuous restricted Boltzmann machine (CRBM), a probabilistic generative model that is able to model continuous-valued data with a simple and hardware-amenable training algorithm. The full CRBM system consists of stochastic neurons whose continuous-valued probabilistic behavior is mediated by injected noise. Integrating on-chip training circuits, the full CRBM system provides a platform for exploring computation with continuous-valued probabilistic behavior in VLSI. The VLSI CRBM's ability both to model and to regenerate continuous-valued data distributions is examined and limitations on its performance are highlighted and discussed. PMID:16722178

  4. Predicted vs. scale model and flight test UDF engine noise

    NASA Astrophysics Data System (ADS)

    Whitfield, C. E.; Gliebe, P. R.

    1990-10-01

    This paper presents an overview of the development of a frequency-domain, noncompact-source noise prediction model for the unducted fan (UDF) engine. A brief description of the acoustic modeling approach and basic equations employed is given, together with a summary of the aerodynamic characteristics utilized in the noise prediction model. Scale model test results obtained from both low-speed and high-speed wind tunnel measurements are compared with the prediction model, and comparisons of predicted vs measured flight noise characteristics for the full-scale engine are also discussed.

  5. Modeling of Particulate Behavior in Pinhole Breaches

    SciTech Connect

    Casella, Andrew M.; Loyalka, Sudarshan K.; Hanson, Brady D.

    2014-04-01

    A model is presented for calculating depressurization time for and particulate release from used nuclear fuel dry storage containers that have developed a pinhole breach. Particular attention is given to particulate deposition and transmission within the breach pathway. The model is modular in nature and is developed in a way that allows for more advanced treatments of internal temperature, internal component geometry, or aerosol flow to be readily incorporated. The model can be treated as a basis for addressing concerns associated with monitoring and verification efforts during long-term dry cask storage

  6. Modeling release behavior in shocked tantalum

    SciTech Connect

    Steinberg, D.J.

    1995-08-01

    Using Johnson`s anelastic release model for metals (3,4), hydrocode simulation of four Ta plate-impact experiments were performed. These calculations agree well with the data as long as the complete non-linear version of the model is used and the yield surface is itself made asymmetric, i.e., different on loading and unloading. From the parameters in the model it is possible to determine the drag coefficient, mobile dislocation density, and characteristic length of a dislocation, and to obtain reasonable values.

  7. A Neurobehavioral Model of Flexible Spatial Language Behaviors

    ERIC Educational Resources Information Center

    Lipinski, John; Schneegans, Sebastian; Sandamirskaya, Yulia; Spencer, John P.; Schoner, Gregor

    2012-01-01

    We propose a neural dynamic model that specifies how low-level visual processes can be integrated with higher level cognition to achieve flexible spatial language behaviors. This model uses real-word visual input that is linked to relational spatial descriptions through a neural mechanism for reference frame transformations. We demonstrate that…

  8. Evolving Tools for Information Literacy from Models of Information Behavior

    Microsoft Academic Search

    Andrew K. Shenton; Naomi V. Hay-Gibson

    2012-01-01

    Although models are often assumed to constitute the end product of a research project, it is not unusual for them to be refined after subsequent study or thought. Having presented a model of young people's information behavior in a previous paper elsewhere, the authors here offer a more compact version and explore the possibilities for its application in a teaching

  9. Modeling Weather Conditions Consequences on Road Trafficking Behaviors

    E-print Network

    Paris-Sud XI, Université de

    1 Modeling Weather Conditions Consequences on Road Trafficking Behaviors Guillaume Allain´ematiques de Toulouse Abstract--We provide a model to understand how adverse weather conditions modify traffic network and provides accurate unbiased forecasted speed using live or short term forecasted weather data

  10. Complex Systems for Human Body Biomechanical Behavior Modeling

    Microsoft Academic Search

    Mihaela Baritz; Luciana Cristea; Liliana Rogozea; Diana Cotoros; Balcu Ion

    2009-01-01

    In this paper, we will explore the way we are able to obtain some information about human body behavior during gait or stability actions using video and tracking capture and transpose these data on a virtual model for the simulation process. In the first part of the paper we presented some considerations about the problems developed by human body modeling

  11. BEHAVIOR OF A SAND RIDGE MODEL Juan Mario Restrepo

    E-print Network

    Soatto, Stefano

    BEHAVIOR OF A SAND RIDGE MODEL Juan Mario Restrepo Mathematics Department University of California, Los Angeles Los Angeles, CA 90095 Abstract. A model for the formation and evolution of longshore sand waves, which are represented by wave packets, and a sandy bottom topography, conspire to produce sand

  12. A conceptual model for cognitive-behavior therapy with children

    Microsoft Academic Search

    W. Edward Craighead; Andrew W. Meyers; Linda Wilcoxon Craighead

    1985-01-01

    This paper briefly reviews the historical and conceptual developments that produced the cognitive-behavioral model for clinical interventions with children. It is suggested that this model should be expanded by including the person variables of emotion and developmental level and by broadening the scope of environmental variables to include the family, school, and other social\\/community contexts. The implications of this expansion

  13. Behavior-based modeling and its application to Email analysis

    Microsoft Academic Search

    Salvatore J. Stolfo; Shlomo Hershkop; Chia-wei Hu; Wei-jen Li; Olivier Nimeskern; Ke Wang

    2006-01-01

    The Email Mining Toolkit (EMT) is a data mining system that computes behavior profiles or models of user email accounts. These models may be used for a multitude of tasks including forensic analyses and detection tasks of value to law enforcement and intelligence agencies, as well as other typical tasks such as virus and spam detection. To demonstrate the power

  14. A Bayesian framework for simultaneously modeling neural and behavioral data?

    PubMed Central

    Turner, Brandon M.; Forstmann, Birte U.; Wagenmakers, Eric-Jan; Brown, Scott D.; Sederberg, Per B.; Steyvers, Mark

    2013-01-01

    Scientists who study cognition infer underlying processes either by observing behavior (e.g., response times, percentage correct) or by observing neural activity (e.g., the BOLD response). These two types of observations have traditionally supported two separate lines of study. The first is led by cognitive modelers, who rely on behavior alone to support their computational theories. The second is led by cognitive neuroimagers, who rely on statistical models to link patterns of neural activity to experimental manipulations, often without any attempt to make a direct connection to an explicit computational theory. Here we present a flexible Bayesian framework for combining neural and cognitive models. Joining neuroimaging and computational modeling in a single hierarchical framework allows the neural data to influence the parameters of the cognitive model and allows behavioral data, even in the absence of neural data, to constrain the neural model. Critically, our Bayesian approach can reveal interactions between behavioral and neural parameters, and hence between neural activity and cognitive mechanisms. We demonstrate the utility of our approach with applications to simulated fMRI data with a recognition model and to diffusion-weighted imaging data with a response time model of perceptual choice. PMID:23370060

  15. Thermal behavior of an electrical motor through a reduced model

    Microsoft Academic Search

    Yves Bertin; Etienne Videcoq; Sophie Thieblin; Daniel Petit

    2000-01-01

    The aim of this study is to obtain quickly thermal information on some sensitive components of an electrical motor in a short lapse of time. The thermal behavior of this complex system is modeled and validated. The corresponding detailed model leads to the resolution of a linear system of differential equations of high order, but is not easy to handle

  16. Toward a Self-Evaluation Maintenance Model of Social Behavior.

    ERIC Educational Resources Information Center

    Tesser, Abraham

    This paper describes the Self-Evaluation Maintenance (SEM) model of social behavior which consists of three variables: the psychological closeness of another, the relative performance of that other, and the relevance of the performance dimension to one's self-definition. The SEM model is described as involving two processes, the reflection process…

  17. Can behavioral finance models account for historical asset prices?

    Microsoft Academic Search

    Rhys ap Gwilym

    2010-01-01

    I construct a behavioral model of asset pricing in which agents choose whether to base their expectations on chartist or fundamental forecasts. I find that the model cannot be rejected as the data generating process for the FTSE All-Share Index.

  18. Modeling of plasma behavior in a plasma electrode Pockels cell

    Microsoft Academic Search

    Charles D. Boley; Mark A. Rhodes

    1999-01-01

    We present three interrelated models of plasma behavior in a plasma electrode Pockels cell (PEPC). In a PEPC, plasma discharges are formed on both sides of a thin, large-aperture electro-optic crystal (typically KDP). The plasmas act as optically transparent, highly conductive electrodes, allowing uniform application of a longitudinal field to induce birefringence in the crystal. First, we model the plasma

  19. Modeling size effects on the transformation behavior of shape memory alloy micropillars

    NASA Astrophysics Data System (ADS)

    Peraza Hernandez, Edwin A.; Lagoudas, Dimitris C.

    2015-07-01

    The size dependence of the thermomechanical response of shape memory alloys (SMAs) at the micro and nano-scales has gained increasing attention in the engineering community due to existing and potential uses of SMAs as solid-state actuators and components for energy dissipation in small scale devices. Particularly, their recent uses in microelectromechanical systems (MEMS) have made SMAs attractive options as active materials in small scale devices. One factor limiting further application, however, is the inability to effectively and efficiently model the observed size dependence of the SMA behavior for engineering applications. Therefore, in this work, a constitutive model for the size-dependent behavior of SMAs is proposed. Experimental observations are used to motivate the extension of an existing thermomechanical constitutive model for SMAs to account for the scale effects. It is proposed that such effects can be captured via characteristic length dependent material parameters in a power-law manner. The size dependence of the transformation behavior of NiFeGa micropillars is investigated in detail and used as model prediction cases. The constitutive model is implemented in a finite element framework and used to simulate and predict the response of SMA micropillars with different sizes. The results show a good agreement with experimental data. A parametric study performed using the calibrated model shows that the influence of micropillar aspect ratio and taper angle on the compression response is significantly smaller than that of the micropillar average diameter. It is concluded that the model is able to capture the size dependent transformation response of the SMA micropillars. In addition, the simplicity of the calibration and implementation of the proposed model make it practical for the design and numerical analysis of small scale SMA components that exhibit size dependent responses.

  20. Synergistic verification and validation of systems and software engineering models

    Microsoft Academic Search

    Yosr Jarraya; Andrei Soeanu; Luay Alawneh; Mourad Debbabi; Fawzi Hassaïne

    2009-01-01

    In this paper, we present a unified approach for the verification and validation of software and systems engineering design models expressed in UML 2.0 and SysML 1.0. The approach is based on three well-established techniques, namely formal analysis, programme analysis and software engineering (SwE) techniques. More precisely, our contribution consists of the synergistic combination of model checking, static analysis and

  1. GEO-ENGINEERING MODELING THROUGH INTERNET INFORMATICS (GEMINI)

    Microsoft Academic Search

    W. Lynn Watney; John H. Doveton

    2004-01-01

    GEMINI (Geo-Engineering Modeling through Internet Informatics) is a public-domain web application focused on analysis and modeling of petroleum reservoirs and plays (http:\\/\\/www.kgs.ukans.edu\\/Gemini\\/index.html). GEMINI creates a virtual project by ''on-the-fly'' assembly and analysis of on-line data either from the Kansas Geological Survey or uploaded from the user. GEMINI's suite of geological and engineering web applications for reservoir analysis include: (1) petrofacies-based

  2. Creep-rupture behavior of candidate Stirling engine iron supperalloys in high-pressure hydrogen. Volume 2: Hydrogen creep-rupture behavior

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.; Peterman, W.; Hales, C.

    1984-01-01

    The creep rupture behavior of nine iron base and one cobalt base candidate Stirling engine alloys is evaluated. Rupture life, minimum creep rate, and time to 1% strain data are analyzed. The 3500 h rupture life stress and stress to obtain 1% strain in 3500 h are also estimated.

  3. Modeling choice behavior for new pharmaceutical products.

    PubMed

    Bingham, M F; Johnson, F R; Miller, D

    2001-01-01

    This paper presents a dynamic generalization of a model often used to aid marketing decisions relating to conventional products. The model uses stated-preference data in a random-utility framework to predict adoption rates for new pharmaceutical products. In addition, this paper employs a Markov model of patient learning in drug selection. While the simple learning rule presented here is only a rough approximation to reality, this model nevertheless systematically incorporates important features including learning and the influence of shifting preferences on market share. Despite its simplifications, the integrated framework of random-utility and product attribute updating presented here is capable of accommodating a variety of pharmaceutical marketing and development problems. This research demonstrates both the strengths of stated-preference market research and some of its shortcomings for pharmaceutical applications. PMID:11704970

  4. Asymptotic behavior in a deterministic epidemic model

    Microsoft Academic Search

    Herbert W. Hethcote

    1973-01-01

    The effects of a periodic contact rate and of carriers are considered for a generalization of Bailey's simple epidemic model.\\u000a In this model it is assumed that individuals become susceptible again as soon as they recover from the infection so that a\\u000a fixed population can be divided into a class of infectives and a class of susceptibles which vary with

  5. A comparative study of oral health attitudes and behavior using the Hiroshima University-Dental Behavioral Inventory (HU-DBI) between dental and civil engineering students in Colombia.

    PubMed

    Jaramillo, Jorge A; Jaramillo, Fredy; Kador, Itzjak; Masuoka, David; Tong, Liyue; Ahn, Chul; Komabayashi, Takashi

    2013-03-01

    The aim of this study was to use the Hiroshima University - Dental Behavioral Inventory (HU-DBI) to compare oral health attitudes and behavior of dental and civil engineering students in Colombia. The HU-DBI's survey consisting of twenty dichotomous responses (agree-disagree) regarding tooth brushing, was completed at University Antonio Narino for the dental students and the University of Cauca for the civil engineering students. The Spanish version of the HU-DBI questionnaire was taken by 182 of 247 dental students and 411 of 762 engineering students. The data was-statistically analyzed by the chi-square test and backward logistic regression. Compared to the engineering students, the dental students were more likely to agree with questions such as "I am bothered by the color of my gums"(OR = 2.2, 95% CI: 1.3-3.7),"I think I can clean my teeth well without using toothpaste" (OR = 3.0, 95% CI: 1.5-5.9), "I have used a dye to see how clean my teeth are" (OR = 2.9, 95% CI: 1.9-4.3), and "I have had my dentist tell me that I brush very well" (OR = 2.0, 95% CI: 1.3-3.1). The dental education curriculum in a dental school compared to a civil engineering school in Colombia indicated that a three-phase curriculum in didactics and clinics increased oral health attitudes and behavior from entry to graduation. PMID:23485597

  6. A comparative study of oral health attitudes and behavior using the Hiroshima University - Dental Behavioral Inventory (HU-DBI) between dental and civil engineering students in Colombia

    PubMed Central

    Jaramillo, Jorge A.; Jaramillo, Fredy; Kador, Itzjak; Masuoka, David; Tong, Liyue; Ahn, Chul; Komabayashi, Takashi

    2014-01-01

    The aim of this study was to use the Hiroshima University - Dental Behavioral Inventory (HU-DBI) to compare oral health attitudes and behavior of dental and civil engineering students in Colombia. The HU-DBI's survey consisting of twenty dichotomous responses (agree-disagree) regarding tooth brushing, was completed at University Antonio Narino for the dental students and the University of Cauca for the civil engineering students. The Spanish version of the HU-DBI questionnaire was taken by 182 of 247 dental students and 411 of 762 engineering students. The data was-statistically analyzed by the chi-square test and backward logistic regression. Compared to the engineering students, the dental students were more likely to agree with questions such as “I am bothered by the color of my gums”(OR = 2.2, 95% CI: 1.3-3.7),“I think I can clean my teeth well without using toothpaste” (OR = 3.0, 95% CI: 1.5-5.9), “I have used a dye to see how clean my teeth are” (OR = 2.9, 95% CI: 1.9-4.3), and “I have had my dentist tell me that I brush very well” (OR = 2.0, 95% CI: 1.3-3.1). The dental education curriculum in a dental school compared to a civil engineering school in Colombia indicated that a three-phase curriculum in didactics and clinics increased oral health attitudes and behavior from entry to graduation. PMID:23485597

  7. Formal modeling of robot behavior with learning.

    PubMed

    Kirwan, Ryan; Miller, Alice; Porr, Bernd; Di Prodi, P

    2013-11-01

    We present formal specification and verification of a robot moving in a complex network, using temporal sequence learning to avoid obstacles. Our aim is to demonstrate the benefit of using a formal approach to analyze such a system as a complementary approach to simulation. We first describe a classical closed-loop simulation of the system and compare this approach to one in which the system is analyzed using formal verification. We show that the formal verification has some advantages over classical simulation and finds deficiencies our classical simulation did not identify. Specifically we present a formal specification of the system, defined in the Promela modeling language and show how the associated model is verified using the Spin model checker. We then introduce an abstract model that is suitable for verifying the same properties for any environment with obstacles under a given set of assumptions. We outline how we can prove that our abstraction is sound: any property that holds for the abstracted model will hold in the original (unabstracted) model. PMID:23777520

  8. Small fatigue crack growth in metallic materials: A model and its application to engineering alloys

    SciTech Connect

    Shyam, Amit [ORNL

    2007-01-01

    Characterization of the growth behavior of small fatigue cracks is important for materials used in structurally demanding applications such as aircraft turbine discs and some automotive engine components. Here, we present a general, dislocation-based fracture mechanics approach to predict the growth rate of small fatigue cracks in metallic materials. The applicability of the model to the small fatigue crack growth behavior of four engineering alloys was examined. Small fatigue cracks were initiated and propagated, in a controlled manner, from micronotches fabricated by femtosecond pulsed laser micromachining. The results suggest that a methodology consisting of crack-tip damage accumulation and fracture provides a common framework to estimate the fatigue crack propagation lifetime of structural materials.

  9. The Marshall Engineering Thermosphere (MET) Model. Volume 1; Technical Description

    NASA Technical Reports Server (NTRS)

    Smith, R. E.

    1998-01-01

    Volume 1 presents a technical description of the Marshall Engineering Thermosphere (MET) model atmosphere and a summary of its historical development. Various programs developed to augment the original capability of the model are discussed in detail. The report also describes each of the individual subroutines developed to enhance the model. Computer codes for these subroutines are contained in four appendices.

  10. 3D Engineered Models for Stringless Paving Workshop

    E-print Network

    3D Engineered Models for Stringless Paving Workshop As the highway industry looks for greater productivity through electronic tools and methods, 3D modeling is fast becoming a standard for project delivery quality, cost, and time benefits from using 3D modeling. For construction, this includes more accurate

  11. Harnessing genetically engineered mouse models for preclinical testing

    Microsoft Academic Search

    Ana I. Robles; Lyuba Varticovski

    2008-01-01

    Recent studies cast doubt on the value of traditionally used models as tools for testing therapies for human cancer. Although the standard practice of xenografting tumors into immunocompromised mice generates reproducible tumors, drug testing in these models has low predictive power when compared to the clinical responses in Phase II trials. The use of tumor-bearing genetically engineered mouse models holds

  12. Systems modeling at the Idaho National Engineering Laboratory

    NASA Astrophysics Data System (ADS)

    Bray, Michael A.

    1994-12-01

    This paper describes two experiences in systems modeling at the Idaho National Engineering Laboratory. These experiences reinforce key points that bear on the use of systems modeling in analyzing health-care issues. The first point is that mental models are a crucial part of systems. The second point is that simulation uncovers long-term consequences of existing assumptions.

  13. Unifying Computer Forensics Modeling Approaches: A Software Engineering Perspective

    Microsoft Academic Search

    A. Chris Bogen; David A. Dampier

    2005-01-01

    As an effort to introduce formalism into computer forensics, researchers have presented various modeling techniques for planning, analysis, and documentation of forensics activities. These modeling techniques provide representations of various forensics subjects such as investigative processes, chain of events, and evidence tests. From a software engineering perspective, it seems that several of these computer forensics modeling approaches may be unified

  14. Numerical modeling of hydrogen-fueled internal combustion engines

    SciTech Connect

    Johnson, N.L.; Amsden, A.A.; Butler, T.D. [Los Alamos National Lab., NM (United States). Theoretical Div.

    1996-07-01

    Major progress was achieved in the last year in advancing the modeling capabilities of hydrogen-fueled engines, both in support of the multi-laboratory project with SNL and LLNL to develop a high-efficiency, low emission powerplant and to provide the engine design tools to industry and research laboratories for hydrogen-fueled engines and stationary power generators. The culmination of efforts on many fronts was the excellent comparison of the experimental data from the Onan engine, operated by SNL.These efforts include the following. An extensive study of the intake flow culminated in a major understanding of the interdependence of the details of the intake port design and the engine operating condition on the emissions and efficiency. This study also resulted in design suggestions for future engines and general scaling laws for turbulence that enables the KIVA results to be applied to a wide variety of operating conditions. The research on the turbulent combustion of hydrogen brought into perspective the effect of the unique aspects of hydrogen combustion and their influence on possible models of turbulent combustion. The effort culminated in a proposed model for turbulent hydrogen combustion that is in agreement with available literature. Future work will continue the development in order to provide a generally predictive model for hydrogen combustion. The application of the combustion model to the Onan experiments elucidated the observed improvement of the efficiency of the engine with the addition of a shroud on the intake valve. This understanding will give guidance to future engine design for optimal efficiency. Finally, a brief summary is given of the extensions and refinements of the KIVA-3 code, in support of future designers of hydrogen-fueled engines.

  15. Modeling emergent border-crossing behaviors during pandemics

    NASA Astrophysics Data System (ADS)

    Santos, Eunice E.; Santos, Eugene; Korah, John; Thompson, Jeremy E.; Gu, Qi; Kim, Keum Joo; Li, Deqing; Russell, Jacob; Subramanian, Suresh; Zhang, Yuxi; Zhao, Yan

    2013-06-01

    Modeling real-world scenarios is a challenge for traditional social science researchers, as it is often hard to capture the intricacies and dynamisms of real-world situations without making simplistic assumptions. This imposes severe limitations on the capabilities of such models and frameworks. Complex population dynamics during natural disasters such as pandemics is an area where computational social science can provide useful insights and explanations. In this paper, we employ a novel intent-driven modeling paradigm for such real-world scenarios by causally mapping beliefs, goals, and actions of individuals and groups to overall behavior using a probabilistic representation called Bayesian Knowledge Bases (BKBs). To validate our framework we examine emergent behavior occurring near a national border during pandemics, specifically the 2009 H1N1 pandemic in Mexico. The novelty of the work in this paper lies in representing the dynamism at multiple scales by including both coarse-grained (events at the national level) and finegrained (events at two separate border locations) information. This is especially useful for analysts in disaster management and first responder organizations who need to be able to understand both macro-level behavior and changes in the immediate vicinity, to help with planning, prevention, and mitigation. We demonstrate the capabilities of our framework in uncovering previously hidden connections and explanations by comparing independent models of the border locations with their fused model to identify emergent behaviors not found in either independent location models nor in a simple linear combination of those models.

  16. Modeling of Bolt Joint Behavior of Cast Aluminum Alloy (A380-T5) by Coupling Creep and Plasticity in Finite Element Analysis

    Microsoft Academic Search

    Cherng-Chi Chang; Q. G. Wang

    2007-01-01

    Aluminum casting alloys exhibit creep behavior when the materials are exposed to high temperature and load. In this article,\\u000a the stress- and temperature-dependent creep behavior of a die casting A380-T5 aluminum alloy was simulated using a classical\\u000a constitutive model. The bolt-load retention behavior of the material was analyzed in a head bolt joint in an aluminum engine\\u000a under thermal cycle

  17. Using a cognitive-behavioral family model in conjunction with systems and behavioral family therapy models

    Microsoft Academic Search

    Gregory B. Smith; Andrew I. Schwebel

    1995-01-01

    Practitioners and family scientists can use cognitive-behavioral family theory (CBF), along with systems and behavioral theories, to gain deeper understandings of and to facilitate change in the family unit. CBF states that every individual has a family schema. This construct contains the complete set of cognitions that guide individuals as they behave, react, perceive, and process information in the family

  18. Model-based diagnostics of gas turbine engine lubrication systems

    SciTech Connect

    Byington, C.S.

    1998-09-01

    The objective of the current research was to develop improved methodology for diagnosing anomalies and maintaining oil lubrication systems for gas turbine engines. The effort focused on the development of reasoning modules that utilize the existing, inexpensive sensors and are applicable to on-line monitoring within the full-authority digital engine controller (FADEC) of the engine. The target application is the Enhanced TF-40B gas turbine engine that powers the Landing Craft Air Cushion (LCAC) platform. To accomplish the development of the requisite data fusion algorithms and automated reasoning for the diagnostic modules, Penn State ARL produced a generic Turbine Engine Lubrication System Simulator (TELSS) and Data Fusion Workbench (DFW). TELSS is a portable simulator code that calculates lubrication system parameters based upon one-dimensional fluid flow resistance network equations. Validation of the TF- 40B modules was performed using engineering and limited test data. The simulation model was used to analyze operational data from the LCAC fleet. The TELSS, as an integral portion of the DFW, provides the capability to experiment with combinations of variables and feature vectors that characterize normal and abnormal operation of the engine lubrication system. The model-based diagnostics approach is applicable to all gas turbine engines and mechanical transmissions with similar pressure-fed lubrication systems.

  19. Modeling the behavior of the computer-assisted instruction user

    SciTech Connect

    Stoddard, M.L.

    1983-01-01

    The field of computer-assisted instruction CAI contains abundant studies on effectiveness of particular programs or systems. However, the nature of the field is such that the computer is the focus of research, not the users. Few research studies have focused on the behavior of the individual CAI user. Morgan (1981) stated that descriptive studies are needed to clarify what the important phenomena of user behavior are. The need for such studies is particularly acute in computer-assisted instruction. Building a behavioral model would enable us to understand problem-solving strategies and rules applied by the user during a CAI experience. Also, courseware developers could use this information to design tutoring systems that are more responsive to individual differences than our present CAI is. This paper proposes a naturalistic model for evaluating both affective and cognitive characteristics of the CAI user. It begins with a discussion of features of user behavior, followed by a description of evaluation methodology that can lead to modeling user behavior. The paper concludes with a discussion of how implementation of this model can contribute to the fields of CAI and cognitive psychology.

  20. A Novel Behavioral Fish Model of Nociception for Testing Analgesics

    PubMed Central

    Correia, Ana D.; Cunha, Sérgio R.; Scholze, Martin; Stevens, E. Don

    2011-01-01

    Pain is a major symptom in many medical conditions, and often interferes significantly with a person's quality of life. Although a priority topic in medical research for many years, there are still few analgesic drugs approved for clinical use. One reason is the lack of appropriate animal models that faithfully represent relevant hallmarks associated with human pain. Here we propose zebrafish (Danio rerio) as a novel short-term behavioral model of nociception, and analyse its sensitivity and robustness. Firstly, we injected two different doses of acetic acid as the noxious stimulus. We studied individual locomotor responses of fish to a threshold level of nociception using two recording systems: a video tracking system and an electric biosensor (the MOBS system). We showed that an injection dose of 10% acetic acid resulted in a change in behavior that could be used to study nociception. Secondly, we validated our behavioral model by investigating the effect of the analgesic morphine. In time-course studies, first we looked at the dose-response relationship of morphine and then tested whether the effect of morphine could be modulated by naloxone, an opioid antagonist. Our results suggest that a change in behavioral responses of zebrafish to acetic acid is a reasonable model to test analgesics. The response scales with stimulus intensity, is attenuated by morphine, and the analgesic effect of morphine is blocked with naloxone. The change in behavior of zebrafish associated with the noxious stimulus can be monitored with an electric biosensor that measures changes in water impedance.

  1. Modeling uncertainty in requirements engineering decision support

    NASA Technical Reports Server (NTRS)

    Feather, Martin S.; Maynard-Zhang, Pedrito; Kiper, James D.

    2005-01-01

    One inherent characteristic of requrements engineering is a lack of certainty during this early phase of a project. Nevertheless, decisions about requirements must be made in spite of this uncertainty. Here we describe the context in which we are exploring this, and some initial work to support elicitation of uncertain requirements, and to deal with the combination of such information from multiple stakeholders.

  2. An introductory model of a one-piston engine

    NASA Astrophysics Data System (ADS)

    Glaría, Jaime; Wendler, Thomas; Goodwin, Graham

    2005-11-01

    Reciprocating internal combustion engine models have the antithetical goals of accurately describing complex nonlinear behaviour and being simple enough for such purposes as automatic control and online diagnosis. A one-piston four-stroke engine is modelled here by recursively stating simple physical equations. To do that, the domestic ideas of domination and dependence are called as methodological tools for modelling, since they hand out necessary and sufficient equations with few manoeuvres, allocate simulations with the same characteristic and, hopefully, provide a fine way to understanding. The resulting model reveals both steady cycles and transient behaviour.

  3. Behavioral modeling of nonlinear RF power amplifiers considering memory effects

    Microsoft Academic Search

    Hyunchul Ku; J. Stevenson Kenney

    2003-01-01

    This paper proposes a new behavioral model to treat memory effects in nonlinear power amplifiers (PAs). Phenomena such as asymmetries in lower and upper intermodulation terms, and variation of AM\\/AM and AM\\/PM, depending on signal history, are often observed in high-power PAs. To treat these phenomena, this paper presents a model based on the previously developed memory polynomial model. The

  4. A comparative analysis of behavioral models for RF power amplifiers

    Microsoft Academic Search

    M. Isaksson; D. Wisell; D. Ronnow

    2006-01-01

    A comparative study of nonlinear behavioral models with memory for radio-frequency power amplifier (PAs) is presented. The models are static polynomial, parallel Hammerstein (PH), Volterra, and radial basis-function neural network (RBFNN). Two PAs were investigated: one was designed for the third-generation (3G) mobile telecommunication systems and one was designed for the second-generation (2G). The RBFNN reduced the total model error

  5. Crossover behavior in a mixed-mode fiber bundle model

    Microsoft Academic Search

    Srutarshi Pradhan; Bikas K. Chakrabarti; Alex Hansen

    2005-01-01

    We introduce a mixed-mode load sharing scheme in a fiber bundle model. This model reduces exactly to equal-load-sharing (ELS) and local-load-sharing (LLS) models at the two extreme limits of a single-load-sharing parameter. We identify two distinct regimes: (a) the mean-field regime where the ELS mode dominates and (b) the short-range regime dominated by the LLS mode. The crossover behavior is

  6. Applying Model Based Systems Engineering to NASA's Space Communications Networks

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul; Barnes, Patrick; Reinert, Jessica; Golden, Bert

    2013-01-01

    System engineering practices for complex systems and networks now require that requirement, architecture, and concept of operations product development teams, simultaneously harmonize their activities to provide timely, useful and cost-effective products. When dealing with complex systems of systems, traditional systems engineering methodology quickly falls short of achieving project objectives. This approach is encumbered by the use of a number of disparate hardware and software tools, spreadsheets and documents to grasp the concept of the network design and operation. In case of NASA's space communication networks, since the networks are geographically distributed, and so are its subject matter experts, the team is challenged to create a common language and tools to produce its products. Using Model Based Systems Engineering methods and tools allows for a unified representation of the system in a model that enables a highly related level of detail. To date, Program System Engineering (PSE) team has been able to model each network from their top-level operational activities and system functions down to the atomic level through relational modeling decomposition. These models allow for a better understanding of the relationships between NASA's stakeholders, internal organizations, and impacts to all related entities due to integration and sustainment of existing systems. Understanding the existing systems is essential to accurate and detailed study of integration options being considered. In this paper, we identify the challenges the PSE team faced in its quest to unify complex legacy space communications networks and their operational processes. We describe the initial approaches undertaken and the evolution toward model based system engineering applied to produce Space Communication and Navigation (SCaN) PSE products. We will demonstrate the practice of Model Based System Engineering applied to integrating space communication networks and the summary of its results and impact. We will highlight the insights gained by applying the Model Based System Engineering and provide recommendations for its applications and improvements.

  7. Quantitative Modeling of Polymer Scratch Behavior 

    E-print Network

    Hossain, Mohammad Motaher

    2013-12-02

    the scratch process, FEM modeling along with the ASTM/ISO standard scratch tests was carried out by Jiang et al. [7]. The primary focus of the study was to investigate the evolution of scratch-induced deformation features in the scratch groove, i.e...-scale in TPO; (d) Pseudo fish-scale pattern mixed with crazes/voids in PS; (e) Parabolic crack pattern in Epoxy [7]. .................................................................................... 8 1.6 Polymer scratch damage evolution map [7...

  8. Modeling the Behavior of HTS Terahertz RSQUIDs

    Microsoft Academic Search

    Colin M. Pegrum; John C. Macfarlane; Jia Du

    2011-01-01

    In previous work we looked in detail at simulations of our HTS Resistive DC SQUIDs (RSQUIDs) using a lumped-com- ponentmodelandneglectingstep-edgejunctioncapacitance.These can nowbemade withjunctions that haveahigh product of critical current and normal resistance and so the Josephson fre- quency can be above 1 THz. This calls for a more refined model of the device, which we will present here. The RSQUID

  9. Mean Line Pump Flow Model in Rocket Engine System Simulation

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.; Lavelle, Thomas M.

    2000-01-01

    A mean line pump flow modeling method has been developed to provide a fast capability for modeling turbopumps of rocket engines. Based on this method, a mean line pump flow code PUMPA has been written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The pump code can model axial flow inducers, mixed-flow and centrifugal pumps. The code can model multistage pumps in series. The code features rapid input setup and computer run time, and is an effective analysis and conceptual design tool. The map generation capability of the code provides the map information needed for interfacing with a rocket engine system modeling code. The off-design and multistage modeling capabilities of the code permit parametric design space exploration of candidate pump configurations and provide pump performance data for engine system evaluation. The PUMPA code has been integrated with the Numerical Propulsion System Simulation (NPSS) code and an expander rocket engine system has been simulated. The mean line pump flow code runs as an integral part of the NPSS rocket engine system simulation and provides key pump performance information directly to the system model at all operating conditions.

  10. Integrating sensorimotor systems in a robot model of cricket behavior

    NASA Astrophysics Data System (ADS)

    Webb, Barbara H.; Harrison, Reid R.

    2000-10-01

    The mechanisms by which animals manage sensorimotor integration and coordination of different behaviors can be investigated in robot models. In previous work the first author has build a robot that localizes sound based on close modeling of the auditory and neural system in the cricket. It is known that the cricket combines its response to sound with other sensorimotor activities such as an optomotor reflex and reactions to mechanical stimulation for the antennae and cerci. Behavioral evidence suggests some ways these behaviors may be integrated. We have tested the addition of an optomotor response, using an analog VLSI circuit developed by the second author, to the sound localizing behavior and have shown that it can, as in the cricket, improve the directness of the robot's path to sound. In particular it substantially improves behavior when the robot is subject to a motor disturbance. Our aim is to better understand how the insect brain functions in controlling complex combinations of behavior, with the hope that this will also suggest novel mechanisms for sensory integration on robots.

  11. Collective signaling behavior in a networked-oscillator model

    NASA Astrophysics Data System (ADS)

    Liu, Z.-H.; Hui, P. M.

    2007-09-01

    We propose and study the collective behavior of a model of networked signaling objects that incorporates several ingredients of real-life systems. These ingredients include spatial inhomogeneity with grouping of signaling objects, signal attenuation with distance, and delayed and impulsive coupling between non-identical signaling objects. Depending on the coupling strength and/or time-delay effect, the model exhibits completely, partially, and locally collective signaling behavior. In particular, a correlated signaling (CS) behavior is observed in which there exist time durations when nearly a constant fraction of oscillators in the system are in the signaling state. These time durations are much longer than the duration of a spike when a single oscillator signals, and they are separated by regular intervals in which nearly all oscillators are silent. Such CS behavior is similar to that observed in biological systems such as fireflies, cicadas, crickets, and frogs. The robustness of the CS behavior against noise is also studied. It is found that properly adjusting the coupling strength and noise level could enhance the correlated behavior.

  12. Triadic model of the neurobiology of motivated behavior in adolescence

    PubMed Central

    ERNST, MONIQUE; PINE, DANIEL S.; HARDIN, MICHAEL

    2009-01-01

    Background Risk-taking behavior is a major cause of morbidity and mortality in adolescence. In the context of decision theory and motivated (goal-directed) behavior, risk-taking reflects a pattern of decision-making that favors the selection of courses of action with uncertain and possibly harmful consequences. We present a triadic, neuroscience systems-based model of adolescent decision-making. Method We review the functional role and neurodevelopmental findings of three key structures in the control of motivated behavior, i.e. amygdala, nucleus accumbens, and medial/ventral prefrontal cortex. We adopt a cognitive neuroscience approach to motivated behavior that uses a temporal fragmentation of a generic motivated action. Predictions about the relative contributions of the triadic nodes to the three stages of a motivated action during adolescence are proposed. Results The propensity during adolescence for reward/novelty seeking in the face of uncertainty or potential harm might be explained by a strong reward system (nucleus accumbens), a weak harm-avoidant system (amygdala), and/or an inefficient supervisory system (medial/ventral prefrontal cortex). Perturbations in these systems may contribute to the expression of psychopathology, illustrated here with depression and anxiety. Conclusions A triadic model, integrated in a temporally organized map of motivated behavior, can provide a helpful framework that suggests specific hypotheses of neural bases of typical and atypical adolescent behavior. PMID:16472412

  13. Modeling of Commercial Turbofan Engine With Ice Crystal Ingestion: Follow-On

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.; Coennen, Ryan

    2014-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which is ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in flight. The computational tool was utilized to help guide a portion of the PSL testing, and was used to predict ice accretion could also occur at significantly lower altitudes. The predictions were qualitatively verified by subsequent testing of the engine in the PSL. In a previous study, analysis of select PSL test data points helped to calibrate the engine icing computational tool to assess the risk of ice accretion. This current study is a continuation of that data analysis effort. The study focused on tracking the variations in wet bulb temperature and ice particle melt ratio through the engine core flow path. The results from this study have identified trends, while also identifying gaps in understanding as to how the local wet bulb temperature and melt ratio affects the risk of ice accretion and subsequent engine behavior.

  14. An Extended Combustion Model for the Aircraft Turbojet Engine

    NASA Astrophysics Data System (ADS)

    Rotaru, Constantin; Andres-Mih?il?, Mihai; Matei, Pericle Gabriel

    2014-08-01

    The paper consists in modelling and simulation of the combustion in a turbojet engine in order to find optimal characteristics of the burning process and the optimal shape of combustion chambers. The main focus of this paper is to find a new configuration of the aircraft engine combustion chambers, namely an engine with two main combustion chambers, one on the same position like in classical configuration, between compressor and turbine and the other, placed behind the turbine but not performing the role of the afterburning. This constructive solution could allow a lower engine rotational speed, a lower temperature in front of the first stage of the turbine and the possibility to increase the turbine pressure ratio by extracting the flow stream after turbine in the inner nozzle. Also, a higher thermodynamic cycle efficiency and thrust in comparison to traditional constant-pressure combustion gas turbine engines could be obtained.

  15. Asymptotic behavior of solutions of the renormalization group K-epsilon turbulence model

    NASA Technical Reports Server (NTRS)

    Yakhot, A.; Staroselsky, I.; Orszag, S. A.

    1994-01-01

    Presently, the only efficient way to calculate turbulent flows in complex geometries of engineering interest is to use Reynolds-average Navier-Stokes (RANS) equations. As compared to the original Navier-Stokes problem, these RANS equations posses much more complicated nonlinear structure and may exhibit far more complex nonlinear behavior. In certain cases, the asymptotic behavior of such models can be studied analytically which, aside from being an interesting fundamental problem, is important for better understanding of the internal structure of the models as well as to improve their performances. The renormalization group (RNG) K-epsilon turbulence model, derived directly from the incompresible Navier-Stokes equations, is analyzed. It has already been used to calculate a variety of turbulent and transitional flows in complex geometries. For large values of the RNG viscosity parameter, the model may exhibit singular behavior. In the form of the RNG K-epsilon model that avoids the use of explicit wall functions, a = 1, so the RNG viscosity parameter must be smaller than 23.62 to avoid singularities.

  16. Modeling of thermo-mechanical and irradiation behavior of mixed oxide fuel for sodium fast reactors

    NASA Astrophysics Data System (ADS)

    Karahan, Ayd?n; Buongiorno, Jacopo

    2010-01-01

    An engineering code to model the irradiation behavior of UO2-PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named fuel engineering and structural analysis tool (FEAST-OXIDE). FEAST-OXIDE has several modules working in coupled form with an explicit numerical algorithm. These modules describe: (1) fission gas release and swelling, (2) fuel chemistry and restructuring, (3) temperature distribution, (4) fuel-clad chemical interaction and (5) fuel-clad mechanical analysis. Given the fuel pin geometry, composition and irradiation history, FEAST-OXIDE can analyze fuel and cladding thermo-mechanical behavior at both steady-state and design-basis transient scenarios. The code was written in FORTRAN-90 program language. The mechanical analysis module implements the LIFE algorithm. Fission gas release and swelling behavior is described by the OGRES and NEFIG models. However, the original OGRES model has been extended to include the effects of joint oxide gain (JOG) formation on fission gas release and swelling. A detailed fuel chemistry model has been included to describe the cesium radial migration and JOG formation, oxygen and plutonium radial distribution and the axial migration of cesium. The fuel restructuring model includes the effects of as-fabricated porosity migration, irradiation-induced fuel densification, grain growth, hot pressing and fuel cracking and relocation. Finally, a kinetics model is included to predict the clad wastage formation. FEAST-OXIDE predictions have been compared to the available FFTF, EBR-II and JOYO databases, as well as the LIFE-4 code predictions. The agreement was found to be satisfactory for steady-state and slow-ramp over-power accidents.

  17. Modeling Candle Flame Behavior In Variable Gravity

    NASA Technical Reports Server (NTRS)

    Alsairafi, A.; Tien, J. S.; Lee, S. T.; Dietrich, D. L.; Ross, H. D.

    2003-01-01

    The burning of a candle, as typical non-propagating diffusion flame, has been used by a number of researchers to study the effects of electric fields on flame, spontaneous flame oscillation and flickering phenomena, and flame extinction. In normal gravity, the heat released from combustion creates buoyant convection that draws oxygen into the flame. The strength of the buoyant flow depends on the gravitational level and it is expected that the flame shape, size and candle burning rate will vary with gravity. Experimentally, there exist studies of candle burning in enhanced gravity (i.e. higher than normal earth gravity, g(sub e)), and in microgravity in drop towers and space-based facilities. There are, however, no reported experimental data on candle burning in partial gravity (g < g(sub e)). In a previous numerical model of the candle flame, buoyant forces were neglected. The treatment of momentum equation was simplified using a potential flow approximation. Although the predicted flame characteristics agreed well with the experimental results, the model cannot be extended to cases with buoyant flows. In addition, because of the use of potential flow, no-slip boundary condition is not satisfied on the wick surface. So there is some uncertainty on the accuracy of the predicted flow field. In the present modeling effort, the full Navier-Stokes momentum equations with body force term is included. This enables us to study the effect of gravity on candle flames (with zero gravity as the limiting case). In addition, we consider radiation effects in more detail by solving the radiation transfer equation. In the previous study, flame radiation is treated as a simple loss term in the energy equation. Emphasis of the present model is on the gas-phase processes. Therefore, the detailed heat and mass transfer phenomena inside the porous wick are not treated. Instead, it is assumed that a thin layer of liquid fuel coated the entire wick surface during the burning process. This is the limiting case that the mass transfer process in the wick is much faster than the evaporation process at the wick surface.

  18. ENGINE REAL TIME MODELS - WAY TO A MODEL BASED PREDICTIVE CONTROL

    Microsoft Academic Search

    Milos Polasek; Vit Dolecek; Zbynek Sika; Michael Valasek

    The paper deals with a model-based predictive control of a DI diesel engine with Variable Geometry Turbine (VGT). The paper is based on an integrated approach which purpose is to propose a procedure for designing con trol algorithms. A real-time engine model is the essential part of the work. The model and wa y how to employ experimental data is

  19. Alterations in choice behavior by manipulations of world model

    PubMed Central

    Green, C. S.; Benson, C.; Kersten, D.; Schrater, P.

    2010-01-01

    How to compute initially unknown reward values makes up one of the key problems in reinforcement learning theory, with two basic approaches being used. Model-free algorithms rely on the accumulation of substantial amounts of experience to compute the value of actions, whereas in model-based learning, the agent seeks to learn the generative process for outcomes from which the value of actions can be predicted. Here we show that (i) “probability matching”—a consistent example of suboptimal choice behavior seen in humans—occurs in an optimal Bayesian model-based learner using a max decision rule that is initialized with ecologically plausible, but incorrect beliefs about the generative process for outcomes and (ii) human behavior can be strongly and predictably altered by the presence of cues suggestive of various generative processes, despite statistically identical outcome generation. These results suggest human decision making is rational and model based and not consistent with model-free learning. PMID:20805507

  20. Answering questions about consciousness by modeling perception as covert behavior.

    PubMed

    Markkula, Gustav

    2015-01-01

    Two main open questions in current consciousness research concern (i) the neural correlates of consciousness (NCC) and (ii) the relationship between neural activity and first-person, subjective experience. Here, possible answers are sketched for both of these, by means of a model-based analysis of what is required for one to admit having a conscious experience. To this end, a model is proposed that allows reasoning, albeit necessarily in a simplistic manner, about all of the so called "easy problems" of consciousness, from discrimination of stimuli to control of behavior and language. First, it is argued that current neuroscientific knowledge supports the view of perception and action selection as two examples of the same basic phenomenon, such that one can meaningfully refer to neuronal activations involved in perception as covert behavior. Building on existing neuroscientific and psychological models, a narrative behavior model is proposed, outlining how the brain selects covert (and sometimes overt) behaviors to construct a complex, multi-level narrative about what it is like to be the individual in question. It is hypothesized that we tend to admit a conscious experience of X if, at the time of judging consciousness, we find ourselves acceptably capable of performing narrative behavior describing X. It is argued that the proposed account reconciles seemingly conflicting empirical results, previously presented as evidence for competing theories of consciousness, and suggests that well-defined, experiment-independent NCCs are unlikely to exist. Finally, an analysis is made of what the modeled narrative behavior machinery is and is not capable of. It is discussed how an organism endowed with such a machinery could, from its first-person perspective, come to adopt notions such as "subjective experience," and of there being "hard problems," and "explanatory gaps" to be addressed in order to understand consciousness. PMID:26136704

  1. Answering questions about consciousness by modeling perception as covert behavior

    PubMed Central

    Markkula, Gustav

    2015-01-01

    Two main open questions in current consciousness research concern (i) the neural correlates of consciousness (NCC) and (ii) the relationship between neural activity and first-person, subjective experience. Here, possible answers are sketched for both of these, by means of a model-based analysis of what is required for one to admit having a conscious experience. To this end, a model is proposed that allows reasoning, albeit necessarily in a simplistic manner, about all of the so called “easy problems” of consciousness, from discrimination of stimuli to control of behavior and language. First, it is argued that current neuroscientific knowledge supports the view of perception and action selection as two examples of the same basic phenomenon, such that one can meaningfully refer to neuronal activations involved in perception as covert behavior. Building on existing neuroscientific and psychological models, a narrative behavior model is proposed, outlining how the brain selects covert (and sometimes overt) behaviors to construct a complex, multi-level narrative about what it is like to be the individual in question. It is hypothesized that we tend to admit a conscious experience of X if, at the time of judging consciousness, we find ourselves acceptably capable of performing narrative behavior describing X. It is argued that the proposed account reconciles seemingly conflicting empirical results, previously presented as evidence for competing theories of consciousness, and suggests that well-defined, experiment-independent NCCs are unlikely to exist. Finally, an analysis is made of what the modeled narrative behavior machinery is and is not capable of. It is discussed how an organism endowed with such a machinery could, from its first-person perspective, come to adopt notions such as “subjective experience,” and of there being “hard problems,” and “explanatory gaps” to be addressed in order to understand consciousness.

  2. GETRAN: A generic, modularly structured computer code for simulation of dynamic behavior of aero- and power generation gas turbine engines

    SciTech Connect

    Schobeiri, M.T.; Attia, M.; Lippke, C. (Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering)

    1994-07-01

    The design concept, the theoretical background essential for the development of the modularly structured simulation code GETRAN, and several critical simulation cases are presented in this paper. The code being developed under contract with NASA Lewis Research Center is capable of simulating the nonlinear dynamic behavior of single- and multispool core engines, turbofan engines, and power generation gas turbine engines under adverse dynamic operating conditions. The modules implemented into GETRAN correspond to components of existing and new-generation aero- and stationary gas turbine engines with arbitrary configuration and arrangement. For precise simulation of turbine and compressor components, row-by-row diabatic and adiabatic calculation procedures are implemented that account for the specific turbine and compressor cascade, blade geometry, and characteristics. The nonlinear, dynamic behavior of the subject engine is calculated solving a number of systems of partial differential equations, which describe the unsteady behavior of each component individually. To identify each differential equation system unambiguously, special attention is paid to the addressing of each component. The code is capable of executing the simulation procedure at four levels, which increase with the degree of complexity of the system and dynamic event. As representative simulations, four different transient cases with single- and multispool thrust and power generation engines were simulated. These transient cases vary from throttling the exit nozzle area, operation with fuel schedule, rotor speed control, to rotating stall and surge.

  3. Development of CFD model for augmented core tripropellant rocket engine

    NASA Technical Reports Server (NTRS)

    Jones, Kenneth M.

    1994-01-01

    The Space Shuttle era has made major advances in technology and vehicle design to the point that the concept of a single-stage-to-orbit (SSTO) vehicle appears more feasible. NASA presently is conducting studies into the feasibility of certain advanced concept rocket engines that could be utilized in a SSTO vehicle. One such concept is a tripropellant system which burns kerosene and hydrogen initially and at altitude switches to hydrogen. This system will attain a larger mass fraction because LOX-kerosene engines have a greater average propellant density and greater thrust-to-weight ratio. This report describes the investigation to model the tripropellant augmented core engine. The physical aspects of the engine, the CFD code employed, and results of the numerical model for a single modular thruster are discussed.

  4. Part power modeling of gas turbine engine systems

    SciTech Connect

    Morchower, S. [Univ. of Washington, Seattle, WA (United States). Dept. of Mechanical Engineering

    1995-12-31

    A method is developed for modeling the part power operation of the two-spool gas turbine engine using the simple and regenerative cycles. The approach is to replace the compressor map with a simple functional relation between the cycle pressure ratio and the peak temperature based on obtaining a reasonable operating line. In this way, the part power characteristics can be developed for cycles whose design parameters are varied. For engine systems for which part power operation is very important. The operation of multiple engines in combination is described.

  5. A meta-analytic review of behavior modeling training.

    PubMed

    Taylor, Paul J; Russ-Eft, Darlene F; Chan, Daniel W L

    2005-07-01

    A meta-analysis of 117 studies evaluated the effects of behavior modeling training (BMT) on 6 training outcomes, across characteristics of training design. BMT effects were largest for learning outcomes, smaller for job behavior, and smaller still for results outcomes. Although BMT effects on declarative knowledge decayed over time, training effects on skills and job behavior remained stable or even increased. Skill development was greatest when learning points were used and presented as rule codes and when training time was longest. Transfer was greatest when mixed (negative and positive) models were presented, when practice included trainee-generated scenarios, when trainees were instructed to set goals, when trainees' superiors were also trained, and when rewards and sanctions were instituted in trainees' work environments. PMID:16060787

  6. Human Modeling For Ground Processing Human Factors Engineering Analysis

    NASA Technical Reports Server (NTRS)

    Tran, Donald; Stambolian, Damon; Henderson, Gena; Barth, Tim

    2011-01-01

    There have been many advancements and accomplishments over that last few years using human modeling for human factors engineering analysis for design of spacecraft and launch vehicles. The key methods used for this are motion capture and computer generated human models. The focus of this paper is to explain the different types of human modeling used currently and in the past at Kennedy Space Center (KSC) currently, and to explain the future plans for human modeling for future spacecraft designs.

  7. Fatigue behavior of two alloys for Space Shuttle applications. [Inconel 903 and 718 for main engine

    NASA Technical Reports Server (NTRS)

    Adsit, N. R.; Block, S. J.

    1978-01-01

    Two superalloys used extensively in the Space Shuttle main engine are Incoloy 903 and Inconel 718. The fatigue behavior of the two alloys under varying conditions is considered. Three heats of Incoloy 903 and two of Inconel 718 were used in the study. Material was tested in several conditions, including mill polish, longitudinal mill polish, transverse mill polish, chemically milled, chemically milled plus shotpeened on one side and on both sides, gas tungsten arc welded, and electron beam welded. Both round and flat tensile specimens were tested in universal test machines. It was found that surface condition influences test results. Transverse scratches resulting from polishing and rougher surfaces lower the stress at runout in relation to that obtained on longitudinally polished and/or smooth-surfaced specimens.

  8. NTP system simulation and detailed nuclear engine modeling

    NASA Astrophysics Data System (ADS)

    Anghaie, Samim

    The topics are presented in viewgraph form and include the following: nuclear thermal propulsion (NTP) & detailed nuclear engine modeling; modeling and engineering simulation of nuclear thermal rocket systems; nuclear thermal rocket simulation system; INSPI-NTVR core axial flow profiles; INSPI-NTRV core axial flow profiles; specific impulse vs. chamber pressure; turbine pressure ratio vs. chamber pressure; NERVA core axial flow profiles; P&W XNR2000 core axial flow profiles; pump pressure rise vs. chamber pressure; streamline of jet-induced flow in cylindrical chamber; flow pattern of a jet-induced flow in a chamber; and radiative heat transfer models.

  9. Systems Model for Improving Standards and Retention In Engineering Education

    NSDL National Science Digital Library

    Owusu, Yaw A. (Yaw Akyeaw-Brimpon)

    This paper describes a systems model for improving standards in engineering education and at the same time maintaining high retention rate for all engineering students in the educational system. A systems approach methodology adopted for this research is a technique of taking into account all relevant factors affecting quality education and student retention. A four-step procedure has been adopted for the model, namely: problem diagnosis, evaluation and analysis, system model design, and design implementation. Target Audience: 2-4 Year College Faculty/Administrators

  10. Case Studies in Process Modeling (Engineering Statistics Handbook)

    NSDL National Science Digital Library

    Filliben, James

    The online Engineering Statistics Handbook provides a section (4.6 Case Studies in Process Modeling) using detailed realistic examples from physical science and engineering applications. Examples in load cell calibration, Alaska Pipeline ultrasonic calibration, ultrasonic reference block study, and thermal expansion of copper case study are presented in a step-by-step manner. This is a great collection of studies showing real world uses of statistics.

  11. Mathematical Model of the Jet Engine Fuel System

    NASA Astrophysics Data System (ADS)

    Klimko, Marek

    2015-05-01

    The paper discusses the design of a simplified mathematical model of the jet (turbo-compressor) engine fuel system. The solution will be based on the regulation law, where the control parameter is a fuel mass flow rate and the regulated parameter is the rotational speed. A differential equation of the jet engine and also differential equations of other fuel system components (fuel pump, throttle valve, pressure regulator) will be described, with respect to advanced predetermined simplifications.

  12. Apparent Transition Behavior of Widely-Used Turbulence Models

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.

    2006-01-01

    The Spalart-Allmaras and the Menter SST kappa-omega turbulence models are shown to have the undesirable characteristic that, for fully turbulent computations, a transition region can occur whose extent varies with grid density. Extremely fine two-dimensional grids over the front portion of an airfoil are used to demonstrate the effect. As the grid density is increased, the laminar region near the nose becomes larger. In the Spalart-Allmaras model this behavior is due to convergence to a laminar-behavior fixed point that occurs in practice when freestream turbulence is below some threshold. It is the result of a feature purposefully added to the original model in conjunction with a special trip function. This degenerate fixed point can also cause nonuniqueness regarding where transition initiates on a given grid. Consistent fully turbulent results can easily be achieved by either using a higher freestream turbulence level or by making a simple change to one of the model constants. Two-equation kappa-omega models, including the SST model, exhibit strong sensitivity to numerical resolution near the area where turbulence initiates. Thus, inconsistent apparent transition behavior with grid refinement in this case does not appear to stem from the presence of a degenerate fixed point. Rather, it is a fundamental property of the kappa-omega model itself, and is not easily remedied.

  13. MODELS OF CYBERINFRASTRUCTURE-BASED ENTERPRISES AND THEIR ENGINEERING

    E-print Network

    Hsu, Cheng

    the elements that integrate persons and the environment with the enterprises. Computerized manufacturing, e-commerce of profit. More telling is, perhaps, the principles revealed for I and O. They define the modelsChapter 8 MODELS OF CYBERINFRASTRUCTURE-BASED ENTERPRISES AND THEIR ENGINEERING An Evolutionary

  14. Form Follows Function Model-Driven Engineering for Clinical Trials

    E-print Network

    Jeavons, Peter

    tools to support clinical trials. A domain metamodel captures the community's best practice in trialForm Follows Function Model-Driven Engineering for Clinical Trials Jim Davies1 , Jeremy Gibbons1 variety of information-modelling domains: not just clinical tri- als, but also electronic public sector

  15. Virtual Prototypes and Product Models in Mechanical Engineering

    Microsoft Academic Search

    Michael J. Pratt

    1995-01-01

    This paper gives an overview of some of the modelling and virtual prototyping techniquesused in product realization, with emphasis on the mechanical engineering eld.It is pointed out that virtual prototypes, in the commonly accepted sense of computermodels permitting realistic graphical simulation, represent only one class amongst themany types of computer models used in design and planning for manufacture. Each suchmodel

  16. Three and more dimensional modelling in geo-engineering

    Microsoft Academic Search

    Robert Hack; Bogdan Orlic; Senol Ozmutlu; Sicai Zhu; Niek Rengers

    2006-01-01

    Full three-dimensional modelling has been developed and is implemented for many sites where engineering structures are built. Such computer models of the subsurface allow for a more sophisticated handling of subsurface data leading to, for example, better dimensioning of geotechnical units, the evaluation of hazard and risk, foundation design, tunnel routing, planning and building, etc. Other applications are the back-analysis

  17. AP233: An Information Model for Systems Engineering

    NASA Technical Reports Server (NTRS)

    Siebes, Georg

    2009-01-01

    In today's world, information is abundant. We have no problems generating it. But we are challenged to find, organize, and exchange information. center dot A standardized model of information can help. Such a model nearly completed its development for Systems Engineering. It is referred to as AP233 (AP = Application Protocol).

  18. A VARIATIONAL PROBLEM MODELLING BEHAVIOR OF UNORTHODOX SILICON CRYSTALS

    E-print Network

    a series of experimental obser- vations on vicinal defects of heavily boron-doped Silicon crystals revealedA VARIATIONAL PROBLEM MODELLING BEHAVIOR OF UNORTHODOX SILICON CRYSTALS J. HANNON, IBM, YORKTOWN-terrace"] type surface [for a recent review see[JW99

  19. Applying a Component Behavior Model to MVC Pattern

    Microsoft Academic Search

    Fangyuan Zheng; Hao Hu; Lü Jian

    2008-01-01

    With the component-based development becoming the mainstream of software development, original component technologies focusing on describing the static information of components like interfaces and interactions seems to be weak in today's distributed and open software environment. In this paper we propose a new component model with component's behavior introduced in, supporting a flexible and extendable development mechanism in the new

  20. Behavioral impairments in animal models for zinc deficiency

    PubMed Central

    Hagmeyer, Simone; Haderspeck, Jasmin Carmen; Grabrucker, Andreas Martin

    2015-01-01

    Apart from teratogenic and pathological effects of zinc deficiency such as the occurrence of skin lesions, anorexia, growth retardation, depressed wound healing, altered immune function, impaired night vision, and alterations in taste and smell acuity, characteristic behavioral changes in animal models and human patients suffering from zinc deficiency have been observed. Given that it is estimated that about 17% of the worldwide population are at risk for zinc deficiency and that zinc deficiency is associated with a variety of brain disorders and disease states in humans, it is of major interest to investigate, how these behavioral changes will affect the individual and a putative course of a disease. Thus, here, we provide a state of the art overview about the behavioral phenotypes observed in various models of zinc deficiency, among them environmentally produced zinc deficient animals as well as animal models based on a genetic alteration of a particular zinc homeostasis gene. Finally, we compare the behavioral phenotypes to the human condition of mild to severe zinc deficiency and provide a model, how zinc deficiency that is associated with many neurodegenerative and neuropsychological disorders might modify the disease pathologies. PMID:25610379

  1. Anger in Children's Tantrums: A New, Quantitative, Behaviorally Based Model

    E-print Network

    Qiu, Peihua

    Chapter 12 Anger in Children's Tantrums: A New, Quantitative, Behaviorally Based Model Michael Potegal and Peihua Qiu Abstract Because excessive anger in early childhood can predict later psychopathology, quanti- fying its intensity and time course is clinically important. Anger consists of a set

  2. RESEARCH Open Access Modeling bee swarming behavior through

    E-print Network

    Sayed, Ali

    RESEARCH Open Access Modeling bee swarming behavior through diffusion adaptation with asymmetric bees or uninformed bees, where the informed bees have some information about the destination while the uninformed bees follow the informed bees. The swarm's movement can be viewed as a network of mobile nodes

  3. Models for Interacting Populations of Memes: Competition and Niche Behavior

    E-print Network

    Models for Interacting Populations of Memes: Competition and Niche Behavior Michael L. Best Media on Latent Semantic Indexing, to study the dynamics of memes on the Net. Our analysis discovers replicating memes within posts to the USENET News (or NetNews) system. We cluster the posts to NetNews into clouds

  4. Determinants of Academic Entrepreneurship Behavior: A Multilevel Model

    ERIC Educational Resources Information Center

    Llano, Joseph Anthony

    2010-01-01

    It is well established that universities encourage the acquisition and dissemination of new knowledge among university community members and beyond. However, what is less well understood is how universities encourage entrepreneurial (opportunity discovery, evaluation, and exploiting) behavior. This research investigated a multilevel model of the…

  5. Using Utility Information to Calibrate Customer Demand Management Behavior Models

    E-print Network

    Using Utility Information to Calibrate Customer Demand Management Behavior Models Murat Fahrio calibration, load curtailment, system security. Introduction The best resource for a utility to solve its]. Mechanism design theory [6] has been utilized to optimize the contracts to maximize utility benefit

  6. Testing the Behavioral Intentions Model of Online Shopping for Clothing

    Microsoft Academic Search

    Youn-Kyung Kim; Eun Young Kim; Shefali Kumar

    2003-01-01

    This study tested the predictability of modified Fishbein’s behavioral intentions model in the context of online shopping for clothing. Specifically, the study examined the relative importance of attitude and subjective norm in influencing consumer intention to shop for clothing online. A mailing survey was conducted with 303 adults who had a computer at home and had access to the Internet

  7. Activity-Travel Behavior Analysis Based on Structural Equation Model

    Microsoft Academic Search

    Wu Wenjing; Juan Zhicai

    2009-01-01

    Traveler' process of decision-making is very complicated, which influenced by many factors. Based on the analysis of activity based travel demand theory, the path diagram is given, which describes the decision processes of travelers. Analysis the influence factors from the aspects of socio-demographics, activities participation and travel behaviors, the endogenous and exogenous variables of model are defined and structural equation

  8. Modeling Decision Points in User Search Behavior Paul Thomas

    E-print Network

    Thomas, Paul

    evaluations, predict how users would respond to changes in systems or interfaces, and suggest ideas]: Information Search and Retrieval--Search process. Keywords Retrieval experiment; evaluation; system Understanding and modeling user behavior is critical to designing search systems: it allows us to drive batch

  9. Extensions to the time lag models for practical application to rocket engine stability design

    NASA Astrophysics Data System (ADS)

    Casiano, Matthew J.

    The combustion instability problem in liquid-propellant rocket engines (LREs) has remained a tremendous challenge since their discovery in the 1930s. Improvements are usually made in solving the combustion instability problem primarily using computational fluid dynamics (CFD) and also by testing demonstrator engines. Another approach is to use analytical models. Analytical models can be used such that design, redesign, or improvement of an engine system is feasible in a relatively short period of time. Improvements to the analytical models can greatly aid in design efforts. A thorough literature review is first conducted on liquid-propellant rocket engine (LRE) throttling. Throttling is usually studied in terms of vehicle descent or ballistic missile control however there are many other cases where throttling is important. It was found that combustion instabilities are one of a few major issues that occur during deep throttling (other major issues are heat transfer concerns, performance loss, and pump dynamics). In the past and again recently, gas injected into liquid propellants has shown to be a viable solution to throttle engines and to eliminate some forms of combustion instability. This review uncovered a clever solution that was used to eliminate a chug instability in the Common Extensible Cryogenic Engine (CECE), a modified RL10 engine. A separate review was also conducted on classic time lag combustion instability models. Several new stability models are developed by incorporating important features to the classic and contemporary models, which are commonly used in the aerospace rocket industry. The first two models are extensions of the original Crocco and Cheng concentrated combustion model with feed system contributions. A third new model is an extension to the Wenzel and Szuch double-time lag model also with feed system contributions. The first new model incorporates the appropriate injector acoustic boundary condition which is neglected in contemporary models. This new feature shows that the injector boundary can play a significant role for combustion stability, especially for gaseous injection systems or a system with an injector orifice on the order of the size of the chamber. The second new model additionally accounts for resistive effects. Advanced signal analysis techniques are used to extract frequency-dependent damping from a gas generator component data set. The damping values are then used in the new stability model to more accurately represent the chamber response of the component. The results show a more realistic representation of stability margin by incorporating the appropriate damping effects into the chamber response from data. The original Crocco model, a contemporary model, and the two new models are all compared and contrasted to a marginally stable test case showing their applicability. The model that incorporates resistive aspects shows the best comparison to the test data. Parametrics are also examined to show the influence of the new features and their applicability. The new features allow a more accurate representation of stability margin to be obtained. The third new model is an extension to the Wenzel and Szuch double-time lag chug model. The feed system chug model is extended to account for generic propellant flow rates. This model is also extended to incorporate aspects due to oxygen boiling and helium injection in the feed system. The solutions to the classic models, for the single-time lag and the double-time lag models, are often plotted on a practical engine operating map, however the models have presented some difficulties for numerical algorithms for several reasons. Closed-form solutions for use on these practical operating maps are formulated and developed. These models are incorporated in a graphical user interface tool and the new model is compared to an extensive data set. It correctly predicts the stability behavior at various operating conditions incorporating the influence of injected helium and boiling oxygen in the feed system.

  10. A verification and validation process for model-driven engineering

    NASA Astrophysics Data System (ADS)

    Delmas, R.; Pires, A. F.; Polacsek, T.

    2013-12-01

    Model Driven Engineering practitioners already benefit from many well established verification tools, for Object Constraint Language (OCL), for instance. Recently, constraint satisfaction techniques have been brought to Model-Driven Engineering (MDE) and have shown promising results on model verification tasks. With all these tools, it becomes possible to provide users with formal support from early model design phases to model instantiation phases. In this paper, a selection of such tools and methods is presented, and an attempt is made to define a verification and validation process for model design and instance creation centered on UML (Unified Modeling Language) class diagrams and declarative constraints, and involving the selected tools. The suggested process is illustrated with a simple example.

  11. Modeling the behavior of an earthquake base-isolated building

    Microsoft Academic Search

    V. A. Coveney; S. Jamil; D. E. Johnson; R. F. Kulak; R. A. Uras

    1997-01-01

    Protecting a structure against earthquake excitation by supporting it on laminated elastomeric bearings has become a widely accepted practice. The ability to perform accurate simulation of the system, including FEA of the bearings, would be desirable--especially for key installations. In this paper attempts to model the behavior of elastomeric earthquake bearings are outlined. Attention is focused on modeling highly-filled, low-modulus,

  12. Voting Behavior in Proportional Elections from Agent - Based Models

    NASA Astrophysics Data System (ADS)

    Palombi, Filippo; Toti, Simona

    In the talk we reviewed universal aspects of voting behavior in proportional elections and universality breaking patterns, as established in the existing literature. Focus was made on the Brazilian elections, which are characterized by compulsory voting. We showed how agent-based models can qualitatively and/or quantitatively reproduce the observed empirical distributions. As an example, we discussed the multi-state voter model over a network based on interacting cliques and zealot candidates.

  13. Unified viscoplastic models for low cycle fatique behavior of Waspaloy

    Microsoft Academic Search

    Jong-Taek Yeom; S. J. Williams; In-Soo Kim; Nho-Kwang Park

    2001-01-01

    The deformation behavior of Waspaloy during strain-controlled fatigue tests and creep tests is investigated based on the Chaboche\\u000a viscoplastic model. Material parameters were determined using the least square fit to uniaxial strain-controlled low-cycle\\u000a fatique and creep test results. A standard viscoplastic model using nonlinear kinematic and isotropic hardening rules gave\\u000a a good description for the cyclic hardening or softening observed

  14. Three Studies Testing the Effects of Role Models on Product Users' Safety Behavior

    Microsoft Academic Search

    Mark A. deTurck; I-Hua Chih; Ya-Ping Hsu

    1999-01-01

    Three studies were conducted to determine the effect of a role model's safety behavior on observers' safety behavior. In Studies 1 and 2, role models (confederates) used a cleaning product requiring them to wear safety gloves. Study 1 examined observers' safety behavior after they witnessed a friendly (unfriendly) role model's safety behavior in one of four conditions: 1) wearing rubber

  15. Model Curriculum For Civil Engineering Technology

    NSDL National Science Digital Library

    This project, a project of NSF's Advanced Technological Education program, has developed a civil engineering technology/surveying curriculum for two-year colleges based on an industry survey and review of CET programs around the country. The curriculum integrates new technologies such as GIS, GPS, CADD and computer-aided problem solving into the curriculum. The project is involved in teaching material development, dissemination, and implementation. On the site, visitors will find curriculum documents which include information on developing new course materials, GPS Multimedia Courseware for those using Windows operating systems, as well as information about the project, its partners and sponsors.

  16. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in flight. The computational tool was utilized to help guide a portion of the PSL testing, and was used to predict ice accretion could also occur at significantly lower altitudes. The predictions were qualitatively verified by subsequent testing of the engine in the PSL. The PSL test has helped to calibrate the engine icing computational tool to assess the risk of ice accretion. The results from the computer simulation identified prevalent trends in wet bulb temperature, ice particle melt ratio, and engine inlet temperature as a function of altitude for predicting engine icing risk due to ice crystal ingestion.

  17. Generic domain models in software engineering

    NASA Technical Reports Server (NTRS)

    Maiden, Neil

    1992-01-01

    This paper outlines three research directions related to domain-specific software development: (1) reuse of generic models for domain-specific software development; (2) empirical evidence to determine these generic models, namely elicitation of mental knowledge schema possessed by expert software developers; and (3) exploitation of generic domain models to assist modelling of specific applications. It focuses on knowledge acquisition for domain-specific software development, with emphasis on tool support for the most important phases of software development.

  18. Modeling Temporal Behavior in Large Networks: A Dynamic Mixed-Membership Model

    SciTech Connect

    Rossi, R; Gallagher, B; Neville, J; Henderson, K

    2011-11-11

    Given a large time-evolving network, how can we model and characterize the temporal behaviors of individual nodes (and network states)? How can we model the behavioral transition patterns of nodes? We propose a temporal behavior model that captures the 'roles' of nodes in the graph and how they evolve over time. The proposed dynamic behavioral mixed-membership model (DBMM) is scalable, fully automatic (no user-defined parameters), non-parametric/data-driven (no specific functional form or parameterization), interpretable (identifies explainable patterns), and flexible (applicable to dynamic and streaming networks). Moreover, the interpretable behavioral roles are generalizable, computationally efficient, and natively supports attributes. We applied our model for (a) identifying patterns and trends of nodes and network states based on the temporal behavior, (b) predicting future structural changes, and (c) detecting unusual temporal behavior transitions. We use eight large real-world datasets from different time-evolving settings (dynamic and streaming). In particular, we model the evolving mixed-memberships and the corresponding behavioral transitions of Twitter, Facebook, IP-Traces, Email (University), Internet AS, Enron, Reality, and IMDB. The experiments demonstrate the scalability, flexibility, and effectiveness of our model for identifying interesting patterns, detecting unusual structural transitions, and predicting the future structural changes of the network and individual nodes.

  19. Tailoring surface phase transition and magnetic behaviors in BiFeO3 via doping engineering

    PubMed Central

    Yan, Feng; Xing, Guozhong; Wang, Rongming; Li, Lin

    2015-01-01

    The charge-spin interactions in multiferroic materials (e.g., BiFeO3) have attracted enormous attention due to their high potential for next generation information electronics. However, the weak and deficient manipulation of charge-spin coupling notoriously limits their commercial applications. To tailor the spontaneous charge and the spin orientation synergistically in BiFeO3 (BFO), in this report, the 3d element of Mn doping engineering is employed and unveils the variation of surface phase transition and magnetic behaviors by introducing chemical strain. The spontaneous ferroelectric response and the corresponding domain structures, magnetic behaviors and spin dynamics in Mn-doped BFO ceramics have been investigated systematically. Both the surface phase transition and magnetization were enhanced in BFO via Mn doping. The interaction between the spontaneous polarization charge and magnetic spin reorientation in Mn-doped BFO are discussed in detail. Moreover, our extensive electron paramagnetic resonance (EPR) results demonstrate that the 3d dopant plays a paramount role in the surface phase transition, which provides an alternative route to tune the charge-spin interactions in multiferroic materials. PMID:25774619

  20. Tailoring surface phase transition and magnetic behaviors in BiFeO3 via doping engineering.

    PubMed

    Yan, Feng; Xing, Guozhong; Wang, Rongming; Li, Lin

    2015-01-01

    The charge-spin interactions in multiferroic materials (e.g., BiFeO3) have attracted enormous attention due to their high potential for next generation information electronics. However, the weak and deficient manipulation of charge-spin coupling notoriously limits their commercial applications. To tailor the spontaneous charge and the spin orientation synergistically in BiFeO3 (BFO), in this report, the 3d element of Mn doping engineering is employed and unveils the variation of surface phase transition and magnetic behaviors by introducing chemical strain. The spontaneous ferroelectric response and the corresponding domain structures, magnetic behaviors and spin dynamics in Mn-doped BFO ceramics have been investigated systematically. Both the surface phase transition and magnetization were enhanced in BFO via Mn doping. The interaction between the spontaneous polarization charge and magnetic spin reorientation in Mn-doped BFO are discussed in detail. Moreover, our extensive electron paramagnetic resonance (EPR) results demonstrate that the 3d dopant plays a paramount role in the surface phase transition, which provides an alternative route to tune the charge-spin interactions in multiferroic materials. PMID:25774619

  1. Tailoring surface phase transition and magnetic behaviors in BiFeO3 via doping engineering

    NASA Astrophysics Data System (ADS)

    Yan, Feng; Xing, Guozhong; Wang, Rongming; Li, Lin

    2015-03-01

    The charge-spin interactions in multiferroic materials (e.g., BiFeO3) have attracted enormous attention due to their high potential for next generation information electronics. However, the weak and deficient manipulation of charge-spin coupling notoriously limits their commercial applications. To tailor the spontaneous charge and the spin orientation synergistically in BiFeO3 (BFO), in this report, the 3d element of Mn doping engineering is employed and unveils the variation of surface phase transition and magnetic behaviors by introducing chemical strain. The spontaneous ferroelectric response and the corresponding domain structures, magnetic behaviors and spin dynamics in Mn-doped BFO ceramics have been investigated systematically. Both the surface phase transition and magnetization were enhanced in BFO via Mn doping. The interaction between the spontaneous polarization charge and magnetic spin reorientation in Mn-doped BFO are discussed in detail. Moreover, our extensive electron paramagnetic resonance (EPR) results demonstrate that the 3d dopant plays a paramount role in the surface phase transition, which provides an alternative route to tune the charge-spin interactions in multiferroic materials.

  2. DEFINING THE PLAYERS IN HIGHER-ORDER NETWORKS: PREDICTIVE MODELING FOR REVERSE ENGINEERING FUNCTIONAL INFLUENCE NETWORKS

    SciTech Connect

    McDermott, Jason E.; Costa, Michelle N.; Stevens, S.L.; Stenzel-Poore, Mary; Sanfilippo, Antonio P.

    2011-01-20

    A difficult problem that is currently growing rapidly due to the sharp increase in the amount of high-throughput data available for many systems is that of determining useful and informative causative influence networks. These networks can be used to predict behavior given observation of a small number of components, predict behavior at a future time point, or identify components that are critical to the functioning of the system under particular conditions. In these endeavors incorporating observations of systems from a wide variety of viewpoints can be particularly beneficial, but has often been undertaken with the objective of inferring networks that are generally applicable. The focus of the current work is to integrate both general observations and measurements taken for a particular pathology, that of ischemic stroke, to provide improved ability to produce useful predictions of systems behavior. A number of hybrid approaches have recently been proposed for network generation in which the Gene Ontology is used to filter or enrich network links inferred from gene expression data through reverse engineering methods. These approaches have been shown to improve the biological plausibility of the inferred relationships determined, but still treat knowledge-based and machine-learning inferences as incommensurable inputs. In this paper, we explore how further improvements may be achieved through a full integration of network inference insights achieved through application of the Gene Ontology and reverse engineering methods with specific reference to the construction of dynamic models of transcriptional regulatory networks. We show that integrating two approaches to network construction, one based on reverse-engineering from conditional transcriptional data, one based on reverse-engineering from in situ hybridization data, and another based on functional associations derived from Gene Ontology, using probabilities can improve results of clustering as evaluated by a predictive model of transcriptional expression levels.

  3. Mathematical Modeling of Uniaxial Mechanical Properties of Collagen Gel Scaffolds for Vascular Tissue Engineering

    PubMed Central

    Irastorza, Ramiro M.; Drouin, Bernard; Blangino, Eugenia; Mantovani, Diego

    2015-01-01

    Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffolds in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modeling of such a material is not a trivial task, mainly for its viscoelastic nature. Computational and experimental methods for developing a suitable model for collagen gels are of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification. Several models are evaluated and two nonlinear models are proposed: Mooney-Rivlin inspired and Hammerstein models. The results suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behavior of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, resp.). When Akaike criterion is used, the best is the Mooney-Rivlin inspired model. PMID:25834840

  4. A Material Model for the Cyclic Behavior of Nitinol

    NASA Astrophysics Data System (ADS)

    Rebelo, Nuno; Zipse, Achim; Schlun, Martin; Dreher, Gael

    2011-07-01

    The uniaxial behavior of Nitinol in different forms and at different temperatures has been well documented in the literature. Mathematical models for the three-dimensional behavior of this class of materials, covering superelasticity, plasticity, and shape memory effects have been previously developed. Phenomenological models embedded in FEA analysis are part of common practice today in the development of devices made out of Nitinol. In vivo loading of medical devices has cyclic characteristics. There have been some indications in the literature that cyclic loading of Nitinol modifies substantially its behavior. A consortium of several stent manufacturers, Safe Technology and Dassault Systèmes Simulia Corp., dedicated to the development of fatigue laws suitable for life prediction of Nitinol devices, has conducted an extensive experimental study of the modifications in uniaxial behavior of both Nitinol wire and tubing due to cyclic loading. The Abaqus Nitinol material model has been extended to capture some of the phenomena observed and is described in this article. Namely, a preload beyond 6% strain alters the transformation plateaus; if the cyclic load amplitude is large enough, permanent deformations (residual martensite) are observed; the lower plateau increases; and the upper plateau changes. The modifications to the upper plateau are very interesting in the sense that it appears broken: its start stress gets lowered creating a new plateau up to the highest level of cyclic strain, followed by resuming the original plateau until full transformation. Since quite often the geometry of a device at the point at which it is subjected to cyclic loading is very much dependent on the manufacturing, deployment, and preloading sequence, it is important that analyses be conducted with the original material behavior up to that point, and then with the cyclic behavior thereafter.

  5. Dynamical regimes in neural network models of matching behavior.

    PubMed

    Iigaya, Kiyohito; Fusi, Stefano

    2013-12-01

    The matching law constitutes a quantitative description of choice behavior that is often observed in foraging tasks. According to the matching law, organisms distribute their behavior across available response alternatives in the same proportion that reinforcers are distributed across those alternatives. Recently a few biophysically plausible neural network models have been proposed to explain the matching behavior observed in the experiments. Here we study systematically the learning dynamics of these networks while performing a matching task on the concurrent variable interval (VI) schedule. We found that the model neural network can operate in one of three qualitatively different regimes depending on the parameters that characterize the synaptic dynamics and the reward schedule: (1) a matching behavior regime, in which the probability of choosing an option is roughly proportional to the baiting fractional probability of that option; (2) a perseverative regime, in which the network tends to make always the same decision; and (3) a tristable regime, in which the network can either perseverate or choose the two targets randomly approximately with the same probability. Different parameters of the synaptic dynamics lead to different types of deviations from the matching law, some of which have been observed experimentally. We show that the performance of the network depends on the number of stable states of each synapse and that bistable synapses perform close to optimal when the proper learning rate is chosen. Because our model provides a link between synaptic dynamics and qualitatively different behaviors, this work provides us with insight into the effects of neuromodulators on adaptive behaviors and psychiatric disorders. PMID:24047324

  6. Universal Free School Breakfast: A Qualitative Model for Breakfast Behaviors

    PubMed Central

    Harvey-Golding, Louise; Donkin, Lynn Margaret; Blackledge, John; Defeyter, Margaret Anne

    2015-01-01

    In recent years, the provision of school breakfast has increased significantly in the UK. However, research examining the effectiveness of school breakfast is still within relative stages of infancy, and findings to date have been rather mixed. Moreover, previous evaluations of school breakfast schemes have been predominantly quantitative in their methodologies. Currently, there are few qualitative studies examining the subjective perceptions and experiences of stakeholders, and thereby an absence of knowledge regarding the sociocultural impacts of school breakfast. The purpose of this study was to investigate the beliefs, views and attitudes, and breakfast consumption behaviors, among key stakeholders, served by a council-wide universal free school breakfast initiative, within the North West of England, UK. A sample of children, parents, and school staff were recruited from three primary schools, participating in the universal free school breakfast scheme, to partake in semi-structured interviews and small focus groups. A Grounded Theory analysis of the data collected identified a theoretical model of breakfast behaviors, underpinned by the subjective perceptions and experiences of these key stakeholders. The model comprises of three domains relating to breakfast behaviors, and the internal and external factors that are perceived to influence breakfast behaviors, among children, parents, and school staff. Findings were validated using triangulation methods, member checks, and inter-rater reliability measures. In presenting this theoretically grounded model for breakfast behaviors, this paper provides a unique qualitative insight into the breakfast consumption behaviors and barriers to breakfast consumption, within a socioeconomically deprived community, participating in a universal free school breakfast intervention program.

  7. A Data-Driven Approach to Reverse Engineering Customer Engagement Models: Towards Functional Constructs

    PubMed Central

    de Vries, Natalie Jane; Carlson, Jamie; Moscato, Pablo

    2014-01-01

    Online consumer behavior in general and online customer engagement with brands in particular, has become a major focus of research activity fuelled by the exponential increase of interactive functions of the internet and social media platforms and applications. Current research in this area is mostly hypothesis-driven and much debate about the concept of Customer Engagement and its related constructs remains existent in the literature. In this paper, we aim to propose a novel methodology for reverse engineering a consumer behavior model for online customer engagement, based on a computational and data-driven perspective. This methodology could be generalized and prove useful for future research in the fields of consumer behaviors using questionnaire data or studies investigating other types of human behaviors. The method we propose contains five main stages; symbolic regression analysis, graph building, community detection, evaluation of results and finally, investigation of directed cycles and common feedback loops. The ‘communities’ of questionnaire items that emerge from our community detection method form possible ‘functional constructs’ inferred from data rather than assumed from literature and theory. Our results show consistent partitioning of questionnaire items into such ‘functional constructs’ suggesting the method proposed here could be adopted as a new data-driven way of human behavior modeling. PMID:25036766

  8. Measuring and modeling behavioral decision dynamics in collective evacuation.

    PubMed

    Carlson, Jean M; Alderson, David L; Stromberg, Sean P; Bassett, Danielle S; Craparo, Emily M; Guiterrez-Villarreal, Francisco; Otani, Thomas

    2014-01-01

    Identifying and quantifying factors influencing human decision making remains an outstanding challenge, impacting the performance and predictability of social and technological systems. In many cases, system failures are traced to human factors including congestion, overload, miscommunication, and delays. Here we report results of a behavioral network science experiment, targeting decision making in a natural disaster. In a controlled laboratory setting, our results quantify several key factors influencing individual evacuation decision making in a controlled laboratory setting. The experiment includes tensions between broadcast and peer-to-peer information, and contrasts the effects of temporal urgency associated with the imminence of the disaster and the effects of limited shelter capacity for evacuees. Based on empirical measurements of the cumulative rate of evacuations as a function of the instantaneous disaster likelihood, we develop a quantitative model for decision making that captures remarkably well the main features of observed collective behavior across many different scenarios. Moreover, this model captures the sensitivity of individual- and population-level decision behaviors to external pressures, and systematic deviations from the model provide meaningful estimates of variability in the collective response. Identification of robust methods for quantifying human decisions in the face of risk has implications for policy in disasters and other threat scenarios, specifically the development and testing of robust strategies for training and control of evacuations that account for human behavior and network topologies. PMID:24520331

  9. Role of gene therapy in tissue engineering procedures in rheumatology: the use of animal models

    Microsoft Academic Search

    Peter M. van der Kraan; Wim B. van den Berg

    2004-01-01

    Tissue engineering is not only the application of cells and scaffolds to generate a new tissue but should also bring into play biological principles to guide cellular behavior. A way to modify cellular behavior is genetic modification of the cells used for tissue engineering (gene therapy). In the field of rheumatic diseases, cellular modification by overexpressing anabolic factors, such as

  10. Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions

    SciTech Connect

    Mehl, M; Pitz, W J; Westbrook, C K; Curran, H J

    2010-01-11

    Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. It is generally agreed that their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. In this work, an improved version of the kinetic model by the authors is used to analyze the combustion behavior of several components relevant to gasoline surrogate formulation. Particular attention is devoted to linear and branched saturated hydrocarbons (PRF mixtures), olefins (1-hexene) and aromatics (toluene). Model predictions for pure components, binary mixtures and multicomponent gasoline surrogates are compared with recent experimental information collected in rapid compression machine, shock tube and jet stirred reactors covering a wide range of conditions pertinent to internal combustion engines (3-50 atm, 650-1200K, stoichiometric fuel/air mixtures). Simulation results are discussed focusing attention on the mixing effects of the fuel components.

  11. New Integrated Modeling Capabilities: MIDAS' Recent Behavioral Enhancements

    NASA Technical Reports Server (NTRS)

    Gore, Brian F.; Jarvis, Peter A.

    2005-01-01

    The Man-machine Integration Design and Analysis System (MIDAS) is an integrated human performance modeling software tool that is based on mechanisms that underlie and cause human behavior. A PC-Windows version of MIDAS has been created that integrates the anthropometric character "Jack (TM)" with MIDAS' validated perceptual and attention mechanisms. MIDAS now models multiple simulated humans engaging in goal-related behaviors. New capabilities include the ability to predict situations in which errors and/or performance decrements are likely due to a variety of factors including concurrent workload and performance influencing factors (PIFs). This paper describes a new model that predicts the effects of microgravity on a mission specialist's performance, and its first application to simulating the task of conducting a Life Sciences experiment in space according to a sequential or parallel schedule of performance.

  12. A PROPOSED MODEL FOR AN UNDERGRADUATE ENGINEERING PROGRAM IN MODELING AND SIMULATION

    Microsoft Academic Search

    Sumit Ghosh

    This paper examines the needs, opportunities, requirements, and competing approaches to developing an undergraduate engineering program in modeling and simulation. The paper is the result of a synergistic partnership between Arizona State University, East Campus (ASU East), where a new undergraduate engineering program is under consideration and the Society for Modeling and Simulation International (SCS) that is committed to providing

  13. Engineering Workshop 3D Modeling Using TinkerCAD

    E-print Network

    Ohta, Shigemi

    using TinkerCAD · TinkerCad is used for online 3D modeling · Learn how to print the clip on a 3D printer the hole and the clip #12;Congratulations! You made a 3D model! #12;Now To Print It... Our Printers · MakerEngineering Workshop 3D Modeling Using TinkerCAD Sci-Ed Day 2014 Brookhaven National Laboratory

  14. Models and metrics for software management and engineering

    NASA Technical Reports Server (NTRS)

    Basili, V. R.

    1988-01-01

    This paper attempts to characterize and present a state of the art view of several quantitative models and metrics of the software life cycle. These models and metrics can be used to aid in managing and engineering software projects. They deal with various aspects of the software process and product, including resources allocation and estimation, changes and errors, size, complexity and reliability. Some indication is given of the extent to which the various models have been used and the success they have achieved.

  15. Quasi-One-Dimensional Modeling of Pulse Detonation Rocket Engines

    NASA Technical Reports Server (NTRS)

    Morris, Christopher I.

    2003-01-01

    Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs, but represent a challenging modeling task. A quasi 1-D, finite-rate chemistry CFD model for a PDRE & described and implemented. A parametric study of the effect of blowdown pressure ratio on the performance of an optimized, fixed PDRE nozzle configuration is reported. The results are compared to a steady-state rocket system using similar modeling assumptions.

  16. Modeling reacting gases and aftertreatment devices for internal combustion engines

    NASA Astrophysics Data System (ADS)

    Depcik, Christopher David

    As more emphasis is placed worldwide on reducing greenhouse gas emissions, automobile manufacturers have to create more efficient engines. Simultaneously, legislative agencies want these engines to produce fewer problematic emissions such as nitrogen oxides and particulate matter. In response, newer combustion methods, like homogeneous charge compression ignition and fuel cells, are being researched alongside the old standard of efficiency, the compression ignition or diesel engine. These newer technologies present a number of benefits but still have significant challenges to overcome. As a result, renewed interest has risen in making diesel engines cleaner. The key to cleaning up the diesel engine is the placement of aftertreatment devices in the exhaust. These devices have shown great potential in reducing emission levels below regulatory levels while still allowing for increased fuel economy versus a gasoline engine. However, these devices are subject to many flow control issues. While experimental evaluation of these devices helps to understand these issues better, it is impossible to solve the problem through experimentation alone because of time and cost constraints. Because of this, accurate models are needed in conjunction with the experimental work. In this dissertation, the author examines the entire exhaust system including reacting gas dynamics and aftertreatment devices, and develops a complete numerical model for it. The author begins by analyzing the current one-dimensional gas-dynamics simulation models used for internal combustion engine simulations. It appears that more accurate and faster numerical method is available, in particular, those developed in aeronautical engineering, and the author successfully implements one for the exhaust system. The author then develops a comprehensive literature search to better understand the aftertreatment devices. A number of these devices require a secondary injection of fuel or reductant in the exhaust stream. Accordingly, the author develops a simple post-cylinder injection model which can be easily tuned to match experimental findings. In addition, the author creates a general catalyst model which can be used to model virtually all of the different aftertreatment devices. Extensive validation of this model with experimental data is presented along with all of the numerical algorithms needed to reproduce the model.

  17. 30 cm Engineering Model thruster design and qualification tests

    NASA Technical Reports Server (NTRS)

    Schnelker, D. E.; Collett, C. R.

    1975-01-01

    Development of a 30-cm mercury electron bombardment Engineering Model ion thruster has successfully brought the thruster from the status of a laboratory experimental device to a point approaching flight readiness. This paper describes the development progress of the Engineering Model (EM) thruster in four areas: (1) design features and fabrication approaches, (2) performance verification and thruster to thruster variations, (3) structural integrity, and (4) interface definition. The design of major subassemblies, including the cathode-isolator-vaporizer (CIV), main isolator-vaporizer (MIV), neutralizer isolator-vaporizer (NIV), ion optical system, and discharge chamber/outer housing is discussed along with experimental results.

  18. Hysteretic Behavior of Prestressed Concrete Bridge Pier with Fiber Model

    PubMed Central

    Hui-li, Wang; Guang-qi, Feng; Si-feng, Qin

    2014-01-01

    The hysteretic behavior and seismic characteristics of the prestressed concrete bridge pier were researched. The effects of the prestressed tendon ratio, the longitudinal reinforcement ratio, and the stirrup reinforcement ratio on the hysteretic behavior and seismic characteristics of the prestressed concrete bridge pier have been obtained with the fiber model analysis method. The analysis show some results about the prestressed concrete bridge pier. Firstly, greater prestressed tendon ratio and more longitudinal reinforcement can lead to more obvious pier's hysteresis loop “pinching effect,” smaller residual displacement, and lower energy dissipation capacity. Secondly, the greater the stirrup reinforcement ratio is, the greater the hysteresis loop area is. That also means that bridge piers will have better ductility and stronger shear capacity. The results of the research will provide a theoretical basis for the hysteretic behavior analysis of the prestressed concrete pier. PMID:24578635

  19. Modeling of high homologous temperature deformation behavior for stress and life-time analyses

    SciTech Connect

    Krempl, E. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1997-12-31

    Stress and lifetime analyses need realistic and accurate constitutive models for the inelastic deformation behavior of engineering alloys at low and high temperatures. Conventional creep and plasticity models have fundamental difficulties in reproducing high homologous temperature behavior. To improve the modeling capabilities {open_quotes}unified{close_quotes} state variable theories were conceived. They consider all inelastic deformation rate-dependent and do not have separate repositories for creep and plasticity. The viscoplasticity theory based on overstress (VBO), one of the unified theories, is introduced and its properties are delineated. At high homologous temperature where secondary and tertiary creep are observed modeling is primarily accomplished by a static recovery term and a softening isotropic stress. At low temperatures creep is merely a manifestation of rate dependence. The primary creep modeled at low homologous temperature is due to the rate dependence of the flow law. The model is unaltered in the transition from low to high temperature except that the softening of the isotropic stress and the influence of the static recovery term increase with an increase of the temperature.

  20. Simplifying modeling of nanoparticle aggregation-sedimentation behavior in environmental systems: a theoretical analysis.

    PubMed

    Quik, Joris T K; van De Meent, Dik; Koelmans, Albert A

    2014-10-01

    Parameters and simplified model approaches for describing the fate of engineered nanoparticles (ENPs) are crucial to advance the risk assessment of these materials. Sedimentation behavior of ENPs in natural waters has been shown to follow apparent first order behavior, a 'black box' phenomenon that is insufficiently understood and therefore of limited applicability. Here we use a detailed Smoluchowski-Stokes model that accounts for homo- and heteroaggregation and sedimentation of ENPs and natural colloids (NCs), to simulate and interpret experimental ENP aggregation-sedimentation data. The model adequately simulated the observed time and initial concentration dependence of CeO2 settling data, and also predicted the conditions for aggregation rate-limitations of overall removal. Heteroaggregation with natural colloids was identified as the dominating removal process. Finally, the empirical apparent first order model data were calibrated against the mechanistic Smoluchowski-Stokes model simulation data, showing excellent fits for a range of NC initial concentrations. Using first order removal rates thus can be considered a valid and informed approximation when modeling ENP fate in the aquatic environment. PMID:24956601

  1. GTP-based integral real-3D spatial model for engineering excavation GIS

    Microsoft Academic Search

    Wu Lixin; Shi Wenzhong

    2004-01-01

    Engineering excavation GIS (E2 GIS) is a real-3D GIS serving for geosciences related to geo-engineering, civil engineering and mining engineering based\\u000a on generalized tri-prism (GTP) model. As two instances of GTP model, G-GTP is used for the real-3D modeling of subsurface\\u000a geological bodies, and E-GTP is used for the real-3D modeling of subsurface engineering excavations. In the light of the

  2. A transport model for prediction of wildfire behavior

    SciTech Connect

    Linn, R.R.

    1997-07-01

    Wildfires are a threat to human life and property, yet they are an unavoidable part of nature. In the past people have tried to predict wildfire behavior through the use of point functional models but have been unsuccessful at adequately predicting the gross behavior of the broad spectrum of fires that occur in nature. The majority of previous models do not have self-determining propagation rates. The author uses a transport approach to represent this complicated problem and produce a model that utilizes a self-determining propagation rate. The transport approach allows one to represent a large number of environments including transition regions such as those with nonhomogeneous vegetation and terrain. Some of the most difficult features to treat are the imperfectly known boundary conditions and the fine scale structure that is unresolvable, such as the specific location of the fuel or the precise incoming winds. The author accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts similar to what is done in traditional turbulence modelling. The author develops a complicated model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model the author also forms a simplified local burning model with which he performs a number of simulations for the purpose of demonstrating the properties of a self-determining transport-based wildfire model.

  3. Nonlinear finite element modeling of dental composite polymerization behavior

    NASA Astrophysics Data System (ADS)

    Laughlin, Gayle A.

    2003-07-01

    Polymerization shrinkage has been one of the primary shortcomings preventing the use of resin composites as a universal dental restorative material. This shrinkage of the bonded restoration causes residual stresses in the composite which in turn are transferred to the adhesive interface. The deleterious effects of this stress environment include compromise of the interface itself and the decrease in the mechanical properties of the cured composite. Novel materials which claim to produce less shrinkage have been presented as a new class of restorative materials that could reduce the effects of this problem. One difficulty in assessing the actual in vivo benefits of these new materials is the fact that there is currently no direct way to measure the stress environment at the composite/tooth clinical interface. Computer modeling using finite element analysis (FEA) could provide helpful information regarding the clinical stress performance of dental composites. The purpose of this study was to develop a model that accurately simulates the nonlinear polymerization behavior of light-cured dental composites using a commercial FEA program, which could be accessible for future research. Two phases were needed to accomplish this purpose. First, a data collection phase included volumetric shrinkage, shrinkage stress, tooth analog strain, and dynamic mechanical analysis experiments. Three composites, a standard methacrylate(Z250) and two experimental low stress epoxy-based composites (oxirane and silorane), were tested. The experimental results revealed an intriguing range of polymerization behavior exhibited by the three composites, indicating that the development of a low stress composite is possible. The information gathered from this phase supplied the necessary material input for the computer modeling, and provided empirical validation data for the model solutions. In the second modeling phase, an FEA approach based on a elastic/viscoplastic material model was used to develop models which included the nonlinear constitutive relationships involved in the polymerization behavior of the dental composites. The approach was validated by modeling the curing behavior of the three different composites in the context of two different experiments. Good agreement between model and experimental values indicated that this approach was successful in simulating the polymerization behavior these composites.

  4. Marketing Engineering: Models that Connect with Practice

    Microsoft Academic Search

    Gary L. Lilien; Arvind Rangaswamy

    Other chapters in this book have demonstrated the wide range of marketing problems and the various analytic approaches implemented in decision models to address those problems. We will elaborate on some of those applications, but our main focus here is on how to make those models relevant and useful in practice. We take the perspective that the glass is both

  5. Modeling equine race surface vertical mechanical behaviors in a musculoskeletal modeling environment.

    PubMed

    Symons, Jennifer E; Fyhrie, David P; Hawkins, David A; Upadhyaya, Shrinivasa K; Stover, Susan M

    2015-02-26

    Race surfaces have been associated with the incidence of racehorse musculoskeletal injury, the leading cause of racehorse attrition. Optimal race surface mechanical behaviors that minimize injury risk are unknown. Computational models are an economical method to determine optimal mechanical behaviors. Previously developed equine musculoskeletal models utilized ground reaction floor models designed to simulate a stiff, smooth floor appropriate for a human gait laboratory. Our objective was to develop a computational race surface model (two force-displacement functions, one linear and one nonlinear) that reproduced experimental race surface mechanical behaviors for incorporation in equine musculoskeletal models. Soil impact tests were simulated in a musculoskeletal modeling environment and compared to experimental force and displacement data collected during initial and repeat impacts at two racetracks with differing race surfaces - (i) dirt and (ii) synthetic. Best-fit model coefficients (7 total) were compared between surface types and initial and repeat impacts using a mixed model ANCOVA. Model simulation results closely matched empirical force, displacement and velocity data (Mean R(2)=0.930-0.997). Many model coefficients were statistically different between surface types and impacts. Principal component analysis of model coefficients showed systematic differences based on surface type and impact. In the future, the race surface model may be used in conjunction with previously developed the equine musculoskeletal models to understand the effects of race surface mechanical behaviors on limb dynamics, and determine race surface mechanical behaviors that reduce the incidence of racehorse musculoskeletal injury through modulation of limb dynamics. PMID:25634662

  6. Animal Models for Vascular Tissue-Engineering

    PubMed Central

    Swartz, Daniel D.; Andreadis, Stelios T.

    2013-01-01

    Due to rise in cardiovascular disease throughout the world, there is increasing demand for small diameter blood vessels as replacement grafts. The present review focuses on the animal models that have been used to test small-diameter TEVs with emphasis on the attributes of each model. Small animal models are used to test short-term patency and address mechanistic hypotheses; and large, pre-clinical animal models are employed to test long-term patency, remodeling and function in an environment mimicking human physiology. We also discuss recent clinical trials that employed laboratory fabricated TEVs and showed very promising results. Ultimately, animal models provide a testing platform for optimizing vascular grafts before clinical use in patients without suitable autologous vessels. PMID:23769861

  7. NONHUMAN PRIMATE MODELS OF SOCIAL BEHAVIOR AND COCAINE ABUSE

    PubMed Central

    Nader, Michael A.; Czoty, Paul W.; Nader, Susan H.; Morgan, Drake

    2012-01-01

    Rationale Although cocaine is often abused in social situations, very few animal studies examine the effects of cocaine in the context of social behavior. Objectives This review highlights studies investigating the behavioral effects of cocaine in the context of social housing conditions using nonhuman primates. In addition, this review presents recent findings examining the effects of self-administering cocaine on social behavior and the effects of manipulations hypothesized to be stressful or enriching on the interactions between cocaine reinforcement and social rank. The following dependent variables are examined: 1) cocaine-induced changes in social behavior and 2) cocaine self-administration in cynomolgus monkeys of varying social ranks. The independent variables examined include several environmental and pharmacological manipulations. Conclusions The studies reviewed here indicate that several variables can differentially affect cocaine self-administration when studied in a social context, rather than in individually housed animals. These variables include the social rank and sex of the individual, drug history, the nature of the “fear”-inducing manipulation, and the reliability of cortisol as an appropriate measure of “stress.” While the inclusion of socially housed animals necessitates larger sample sizes, animal models incorporating social behavior are more homologous to the human condition and should be implemented when possible. PMID:22895674

  8. Overview of heat transfer and fluid flow problem areas encountered in Stirling engine modeling

    NASA Technical Reports Server (NTRS)

    Tew, Roy C., Jr.

    1988-01-01

    NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirling engine computer models with test data have demonstrated that engine thermodynamic losses need better characterization. Various Stirling engine thermodynamic losses and efforts that are underway to characterize these losses are discussed.

  9. Modeling the viscoplastic behavior of Inconel 718 at 1200 F

    NASA Technical Reports Server (NTRS)

    Abdel-Kader, M. S.; Eftis, J.; Jones, D. L.

    1988-01-01

    A large number of tests, including tensile, creep, fatigue, and creep-fatigue were performed to characterize the mechanical properties of Inconel 718 (a nickel based superalloy) at 1200 F, the operating temperature for turbine blades. In addition, a few attempts were made to model the behavior of Inconel 718 at 1200 F using viscoplastic theories. The Chaboche theory of viscoplasticity can model a wide variety of mechanical behavior, including monotonic, sustained, and cyclic responses of homogeneous, initially-isotropic, strain hardening (or softening) materials. It is shown how the Chaboche theory can be used to model the viscoplastic behavior of Inconel 718 at 1200 F. First, an algorithm was developed to systematically determine the material parameters of the Chaboche theory from uniaxial tensile, creep, and cyclic data. The algorithm is general and can be used in conjunction with similar high temperature materials. A sensitivity study was then performed and an optimal set of Chaboche's parameters were obtained. This study has also indicated the role of each parameter in modeling the response to different loading conditions.

  10. Enhanced Econometric Model Structures: Application to Travel Behavior and Transportation Modeling

    E-print Network

    Bustamante, Fabián E.

    Enhanced Econometric Model Structures: Application to Travel Behavior and Transportation Modeling Conference Room In this presentation we introduce two innovative econometric model structures that allow us mode and station choice for commuter train users is modeled as a hierarchical choice with mode being

  11. Building a Narrative Based Requirements Engineering Mediation Model

    NASA Astrophysics Data System (ADS)

    Ma, Nan; Hall, Tracy; Barker, Trevor

    This paper presents a narrative-based Requirements Engineering (RE) mediation model to help RE practitioners to effectively identify, define, and resolve conflicts of interest, goals, and requirements. Within the SPI community, there is a common belief that social, human, and organizational issues significantly impact on the effectiveness of software process improvement in general and the requirements engineering process in particularl. Conflicts among different stakeholders are an important human and social issue that need more research attention in the SPI and RE community. By drawing on the conflict resolution literature and IS literature, we argue that conflict resolution in RE is a mediated process, in which a requirements engineer can act as a mediator among different stakeholders. To address socio-psychological aspects of conflict in RE and SPI, Winslade and Monk (2000)'s narrative mediation model is introduced, justified, and translated into the context of RE.

  12. Numerical Modeling of Pulse Detonation Rocket Engine Gasdynamics and Performance

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This paper presents viewgraphs on the numerical modeling of pulse detonation rocket engines (PDRE), with an emphasis on the Gasdynamics and performance analysis of these engines. The topics include: 1) Performance Analysis of PDREs; 2) Simplified PDRE Cycle; 3) Comparison of PDRE and Steady-State Rocket Engines (SSRE) Performance; 4) Numerical Modeling of Quasi 1-D Rocket Flows; 5) Specific PDRE Geometries Studied; 6) Time-Accurate Thrust Calculations; 7) PDRE Performance (Geometries A B C and D); 8) PDRE Blowdown Gasdynamics (Geom. A B C and D); 9) PDRE Geometry Performance Comparison; 10) PDRE Blowdown Time (Geom. A B C and D); 11) Specific SSRE Geometry Studied; 12) Effect of F-R Chemistry on SSRE Performance; 13) PDRE/SSRE Performance Comparison; 14) PDRE Performance Study; 15) Grid Resolution Study; and 16) Effect of F-R Chemistry on SSRE Exit Species Mole Fractions.

  13. Engineering a new mouse model for vitiligo.

    PubMed

    Manga, Prashiela; Orlow, Seth J

    2012-07-01

    Although the precise mechanisms that trigger vitiligo remain elusive, autoimmune responses mediate its progression. The development of therapies has been impeded by a paucity of animal models, since mice lack interfollicular melanocytes, the primary targets in vitiligo. In this issue, Harris et al. describe a mouse model in which interfollicular melanocytes are retained by Kit ligand overexpression and an immune response is initiated by transplanting melanocyte-targeting CD8+ T cells. PMID:22695284

  14. Key Reliability Drivers of Liquid Propulsion Engines and A Reliability Model for Sensitivity Analysis

    NASA Technical Reports Server (NTRS)

    Huang, Zhao-Feng; Fint, Jeffry A.; Kuck, Frederick M.

    2005-01-01

    This paper is to address the in-flight reliability of a liquid propulsion engine system for a launch vehicle. We first establish a comprehensive list of system and sub-system reliability drivers for any liquid propulsion engine system. We then build a reliability model to parametrically analyze the impact of some reliability parameters. We present sensitivity analysis results for a selected subset of the key reliability drivers using the model. Reliability drivers identified include: number of engines for the liquid propulsion stage, single engine total reliability, engine operation duration, engine thrust size, reusability, engine de-rating or up-rating, engine-out design (including engine-out switching reliability, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction), propellant specific hazards, engine start and cutoff transient hazards, engine combustion cycles, vehicle and engine interface and interaction hazards, engine health management system, engine modification, engine ground start hold down with launch commit criteria, engine altitude start (1 in. start), Multiple altitude restart (less than 1 restart), component, subsystem and system design, manufacturing/ground operation support/pre and post flight check outs and inspection, extensiveness of the development program. We present some sensitivity analysis results for the following subset of the drivers: number of engines for the propulsion stage, single engine total reliability, engine operation duration, engine de-rating or up-rating requirements, engine-out design, catastrophic fraction, preventable failure fraction, unnecessary shutdown fraction, and engine health management system implementation (basic redlines and more advanced health management systems).

  15. Modeling bistable behaviors in morphing structures through finite element simulations.

    PubMed

    Guo, Qiaohang; Zheng, Huang; Chen, Wenzhe; Chen, Zi

    2014-01-01

    Bistable structures, exemplified by the Venus flytrap and slap bracelets, can transit between different configurations upon certain external stimulation. Here we study, through three-dimensional finite element simulations, the bistable behaviors in elastic plates in the absence of terminate loads, but with pre-strains in one (or both) of the two composite layers. Both the scenarios with and without a given geometric mis-orientation angle are investigated, the results of which are consistent with recent theoretical and experimental studies. This work can open ample venues for programmable designs of plant/shell structures with large deformations, with applications in designing bio-inspired robotics for biomedical research and morphing/deployable structures in aerospace engineering. PMID:24211939

  16. Long Term Oxidation of Model and Engineering TiAl Alloys

    SciTech Connect

    Locci, IE

    2001-08-24

    The purpose of this research was to characterize the oxidation behavior of several model (TiAl, TiAl-Nb, TiAl-Cr, TiAl-Cr-Nb) and engineering alloys (XD, K5, Alloy 7, WMS) after long-term isothermal exposure ({approx}7000 h) at 704 C, and after shorter time exposure ({approx}1000 h) at 800 C in air. High-resolution field emission and microprobe scanning electron microscopy were used to characterize the scales formed on these alloys. Similarities and differences observed in the scales are correlated with the various ternary and quaternary microalloying additions.

  17. Exploring Host-Microbiome Interactions using an in Silico Model of Biomimetic Robots and Engineered Living Cells.

    PubMed

    Heyde, Keith C; Ruder, Warren C

    2015-01-01

    The microbiome's underlying dynamics play an important role in regulating the behavior and health of its host. In order to explore the details of these interactions, we created an in silico model of a living microbiome, engineered with synthetic biology, that interfaces with a biomimetic, robotic host. By analytically modeling and computationally simulating engineered gene networks in these commensal communities, we reproduced complex behaviors in the host. We observed that robot movements depended upon programmed biochemical network dynamics within the microbiome. These results illustrate the model's potential utility as a tool for exploring inter-kingdom ecological relationships. These systems could impact fields ranging from synthetic biology and ecology to biophysics and medicine. PMID:26178309

  18. Predicting Adolescent Sexual and Contraceptive Behavior: An Application and Test of the Fishbein Model.

    ERIC Educational Resources Information Center

    Jorgensen, Stephen R.; Sonstegard, Janet S.

    1984-01-01

    Presents a test of the Fishbein model of behavior prediction applied to predict the pregnancy risk-taking behavior of adolescent females (N=244). Analyses of data showed that the Fishbein model of attitude-behavior consistency seems to be applicable to the fertility-related behavior of adolescent females. (LLL)

  19. Three-Layer Model for Generation and Recognition of Attention-Drawing Behavior

    E-print Network

    Kanda, Takayuki

    Three-Layer Model for Generation and Recognition of Attention-Drawing Behavior Osamu Sugiyama1 of attention-drawing behavior. The model enables a robot to recognize people's attention-drawing behavior as well as to perform attention-drawing behavior to people. It consists of three layers: the PSM (Pointing

  20. LETTER Communicated by Dean Pomerleau Modeling and Prediction of Human Behavior

    E-print Network

    Liu, Andrew

    LETTER Communicated by Dean Pomerleau Modeling and Prediction of Human Behavior Alex Pentland, Cambridge, MA 02142, U.S.A. We propose that many human behaviors can be accurately described as a set models to recognize human behaviors from sensory data and to predict human behaviors over a few seconds

  1. Characteristics of Behavior of Robots with Emotion Model

    NASA Astrophysics Data System (ADS)

    Sato, Shigehiko; Nozawa, Akio; Ide, Hideto

    Cooperated multi robots system has much dominance in comparison with single robot system. It is able to adapt to various circumstances and has a flexibility for variation of tasks. However it has still problems to control each robot, though methods for control multi robots system have been studied. Recently, the robots have been coming into real scene. And emotion and sensitivity of the robots have been widely studied. In this study, human emotion model based on psychological interaction was adapt to multi robots system to achieve methods for organization of multi robots. The characteristics of behavior of multi robots system achieved through computer simulation were analyzed. As a result, very complexed and interesting behavior was emerged even though it has rather simple configuration. And it has flexiblity in various circumstances. Additional experiment with actual robots will be conducted based on the emotion model.

  2. Modeling of powder behavior: Report for Phase 2 feasibility

    SciTech Connect

    Sinz, K,; Lassila, D.H.; Baum, D.W.

    1996-01-01

    We report on a Phase 2 feasibility study of an effort to compute the mechanical behavior of the incendiary powder RS41 during compaction and release using the experiments conducted at China Lake as a data base. Our simulation, using a prototype material model, develops two-dimensional density gradients in even these simple, uniaxial double-piston experiments. In our view, the computational simulation of the behavior of RS41 while press loading this material into a round and under subsequent launch conditions is feasible within the framework of current technology. For the model development that was conducted as part of this feasibility study, the code of choice was the implicit Lagrangian hydro code NIKE2D. The applicability of the explicit companion code DYNA2D is also discussed.

  3. A Spatial Model of Mosquito Host-Seeking Behavior

    PubMed Central

    Cummins, Bree; Cortez, Ricardo; Foppa, Ivo M.; Walbeck, Justin; Hyman, James M.

    2012-01-01

    Mosquito host-seeking behavior and heterogeneity in host distribution are important factors in predicting the transmission dynamics of mosquito-borne infections such as dengue fever, malaria, chikungunya, and West Nile virus. We develop and analyze a new mathematical model to describe the effect of spatial heterogeneity on the contact rate between mosquito vectors and hosts. The model includes odor plumes generated by spatially distributed hosts, wind velocity, and mosquito behavior based on both the prevailing wind and the odor plume. On a spatial scale of meters and a time scale of minutes, we compare the effectiveness of different plume-finding and plume-tracking strategies that mosquitoes could use to locate a host. The results show that two different models of chemotaxis are capable of producing comparable results given appropriate parameter choices and that host finding is optimized by a strategy of flying across the wind until the odor plume is intercepted. We also assess the impact of changing the level of host aggregation on mosquito host-finding success near the end of the host-seeking flight. When clusters of hosts are more tightly associated on smaller patches, the odor plume is narrower and the biting rate per host is decreased. For two host groups of unequal number but equal spatial density, the biting rate per host is lower in the group with more individuals, indicative of an attack abatement effect of host aggregation. We discuss how this approach could assist parameter choices in compartmental models that do not explicitly model the spatial arrangement of individuals and how the model could address larger spatial scales and other probability models for mosquito behavior, such as Lévy distributions. PMID:22615546

  4. Punitive Parents as Models: Effects of Reward-Incentives and Sex of Model on Recall of Punitive Parental Behaviors.

    ERIC Educational Resources Information Center

    Pittman, Elaine; And Others

    One prediction derived from observational learning theory is that children learn parental-role behaviors by observing parental models. Variables which strongly influence behavior acquisition and performance during observational learning are the behavioral consequences of an action, and the sex of the behavioral model. To evaluate the effects of…

  5. A comprehensive combustion model for biodiesel-fueled engine simulations

    NASA Astrophysics Data System (ADS)

    Brakora, Jessica L.

    Engine models for alternative fuels are available, but few are comprehensive, well-validated models that include accurate physical property data as well as a detailed description of the fuel chemistry. In this work, a comprehensive biodiesel combustion model was created for use in multi-dimensional engine simulations, specifically the KIVA3v R2 code. The model incorporates realistic physical properties in a vaporization model developed for multi-component fuel sprays and applies an improved mechanism for biodiesel combustion chemistry. A reduced mechanism was generated from the methyl decanoate (MD) and methyl-9-decenoate (MD9D) mechanism developed at Lawrence Livermore National Laboratory. It was combined with a multi-component mechanism to include n-heptane in the fuel chemistry. The biodiesel chemistry was represented using a combination of MD, MD9D and n-heptane, which varied for a given fuel source. The reduced mechanism, which contained 63 species, accurately predicted ignition delay times of the detailed mechanism over a range of engine-specific operating conditions. Physical property data for the five methyl ester components of biodiesel were added to the KIVA library. Spray simulations were performed to ensure that the models adequately reproduce liquid penetration observed in biodiesel spray experiments. Fuel composition impacted liquid length as expected, with saturated species vaporizing more and penetrating less. Distillation curves were created to ensure the fuel vaporization process was comparable to available data. Engine validation was performed against a low-speed, high-load, conventional combustion experiments and the model was able to predict the performance and NOx formation seen in the experiment. High-speed, low-load, low-temperature combustion conditions were also modeled, and the emissions (HC, CO, NOx) and fuel consumption were well-predicted for a sweep of injection timings. Finally, comparisons were made between the results of biodiesel composition (palm vs. soy) and fuel blends (neat vs. B20). The model effectively reproduced the trends observed in the experiments.

  6. Numerical modeling of hydrogen-fueled internal combustion engines

    SciTech Connect

    Johnson, N.L.; Amsden, A.A.

    1996-12-31

    The planned use of hydrogen as the energy carrier of the future introduces new challenges and opportunities, especially to the engine design community. Hydrogen is a bio-friendly fuel that can be produced from renewable resources and has no carbon dioxide combustion products; and in a properly designed ICE, almost zero NO{sub x} and hydrocarbon emissions can be achieved. Because of the unique properties of hydrogen combustion - in particular the highly wrinkled nature of the laminar flame front due to the preferential diffusion instability - modeling approaches for hydrocarbon gaseous fuels are not generally applicable to hydrogen combustion. This paper reports on the current progress to develop a engine design capability based on KIVA family of codes for hydrogen-fueled, spark-ignited engines in support of the National Hydrogen Program. A turbulent combustion model, based on a modified eddy-turnover model in conjunction with an intake flow valve model, is found to describe well the efficiency and NO{sub x} emissions of this engine satisfy the Equivalent Zero Emission Vehicle (EZEV) standard established by the California Resource Board. 26 refs., 10 figs., 1 tab.

  7. ORIGINAL PAPER A transgenic mouse model engineered to investigate human

    E-print Network

    Devignes, Marie-Dominique

    ORIGINAL PAPER A transgenic mouse model engineered to investigate human brain-derived neurotrophic to study human BDNF gene expression and permit the screening of compounds capable of stimulating its activity. A 145-kb yeast artificial chromosome carrying the human BDNF gene has been engi- neered

  8. Book chapter for "Computational Models, Software Engineering and

    E-print Network

    Correia, Miguel

    Book chapter for "Computational Models, Software Engineering and Advanced Technologies in Air on controllers' skills, with little or no autonomy for pilots and companies. Moreover, it does not scale up percent per year (Eurocontrol, 1999). Several alternative solutions and complementary approaches

  9. A dynamic network integrated engineering method for traffic congestion model

    Microsoft Academic Search

    Jieyun Xia; Yuxiong Zeng; Yuhuai Zeng

    2011-01-01

    The paper proposes a directed graph model and the selection of appropriate network metrics, the proposed method simulates the city traffic network. Detailed analysis of the traffic flow can be used to derive the volume changes in the city road network. The application of classical graph theory algorithm and transport engineering method makes it feasible to quantify and compute the

  10. CIS 786: Simulation and Modeling for Engineering and Business

    E-print Network

    Lin, Xiaodong

    CIS 786: Simulation and Modeling for Engineering and Business To be offered: Fall 2004 at NJIT.njit.edu/marvin Description Simulation is one of the most widely used tools for analyzing complex processes and systems. Its of the increased power of personal computers and workstations, on which the vast majority of simulations

  11. Passivation design for a turbocharged diesel engine model

    Microsoft Academic Search

    Michael Larsen; P. Kokotovic

    1998-01-01

    We show how master\\/slave combinations of multiple inputs may be used for a single-input analysis to overcome obstacles to passivation. This conceptually simple methodology is illustrated by a passivation design for a simplified model of turbocharged diesel engine

  12. Computer Modeling of Carbon Metabolism Enables Biofuel Engineering (Fact Sheet)

    SciTech Connect

    Not Available

    2011-09-01

    In an effort to reduce the cost of biofuels, the National Renewable Energy Laboratory (NREL) has merged biochemistry with modern computing and mathematics. The result is a model of carbon metabolism that will help researchers understand and engineer the process of photosynthesis for optimal biofuel production.

  13. PBL and CDIO: Complementary Models for Engineering Education Development

    ERIC Educational Resources Information Center

    Edström, Kristina; Kolmos, Anette

    2014-01-01

    This paper compares two models for reforming engineering education, problem/project-based learning (PBL), and conceive-design-implement-operate (CDIO), identifying and explaining similarities and differences. PBL and CDIO are defined and contrasted in terms of their history, community, definitions, curriculum design, relation to disciplines,…

  14. Computerized engineering model for evaporative water cooling towers

    Microsoft Academic Search

    J. E. Park; J. M. Vance; K. E. Cross; N. H. Van Wie

    1978-01-01

    The evaporative cooling tower is often used to reject waste heat from industrial processes, especially power plants and chemical facilities. In particular, huge cooling towers are used for heat rejection from gaseous diffusion plants. The ability to analyze and\\/or predict the performance of these towers is an important process engineering function. A consistent physical model for crossflow and counterflow cooling

  15. Model University-Industry Engineering Programs. An AEA Guidebook.

    ERIC Educational Resources Information Center

    American Electronics Association, Palo Alto, CA.

    This guide presents 37 sample industry-university programs as part of the American Electronics Association's leadership role of encouraging companies to increase investments in engineering education. Model university-industry partnerships in the following areas are presented: faculty assistance grants; faculty loan programs; endowments; graduate…

  16. Engineering Models for Titan's Atmosphere R. V. Yelle1

    E-print Network

    Yelle, Roger V.

    Engineering Models for Titan's Atmosphere R. V. Yelle1 , D. F. Strobell,2 E. Lellouch3 & D. Gautier's atmospheric structure used in the design and analysis of the Huygens Probe and its mission. It supersedes in this volume). There has been significant progress in our under-standing of Titan's atmosphere in the last few

  17. Model-based Security Engineering with UML: Introducing Security Aspects

    E-print Network

    Jurjens, Jan

    . of Informatics, TU Munich, Germany Abstract. Developing security-critical systems is difficult and there are manyModel-based Security Engineering with UML: Introducing Security Aspects Jan J¨urjens Dep well-known examples of security weaknesses exploited in practice. Thus a sound methodology supporting

  18. Model-based Security Engineering of Distributed Information Systems

    E-print Network

    Jurjens, Jan

    Abuse frames Security requirements Risk analysis External review Design Test plans Code Test results Field feedback Risk-based Security tests Static analysis (tools) Risk analysis Penetration testingModel-based Security Engineering of Distributed Information Systems using UMLsec Bastian Best, Jan

  19. Moderate resolution imaging spectroradiometer (MODIS) engineering model development

    Microsoft Academic Search

    Thomas S. Pagano

    1995-01-01

    The moderate resolution imaging spectroradiometer is a space-based imaging spectroradiometer designed to observe small changes in Earth system processes over long periods of time. The first of several MODIS instruments is scheduled to fly on the Earth Observation System (EOS)-AM spacecraft in 1998. The engineering model for the MODIS is well into build and will be in system test later

  20. Velocity and concentration measurements in a model diesel engine

    Microsoft Academic Search

    C. Arcoumanis; H. G. Green; J. H. Whitelaw

    1985-01-01

    Laser Doppler anemometry and Rayleigh scattering have been used to quantify the velocity and concentration fields after the start of injection in a model diesel engine motored at 200 rpm in the absence of compression. Fuel injection was simulated by a transient jet of vapour Freon-12 initiated at 40 degrees before top-dead-centre through a nozzle incorporated into the centre of

  1. A User Behavior Based Trust Model for Mobile Applications

    Microsoft Academic Search

    Zheng Yan; Valtteri Niemi; Yan Dong; Guoliang Yu

    2008-01-01

    A mobile application is a software package that can be installed and executed in a mobile device. Which mobile application\\u000a is more trustworthy for a user to purchase or install becomes a crucial issue that impacts its final success. This paper proposes\\u000a a trust model based on users’ behaviors, which assists the evaluation and management of the mobile application’s trust

  2. Characterizing the Freeze–Drying Behavior of Model Protein Formulations

    Microsoft Academic Search

    Lavinia M. Lewis; Robert E. Johnson; Megan E. Oldroyd; Saleem S. Ahmed; Liji Joseph; Ilie Saracovan; Sandipan Sinha

    2010-01-01

    The freeze–drying behavior of three model proteins, namely, lysozyme, BSA, and IgG, has been studied using a variety of techniques\\u000a under two different primary drying conditions (shelf temperatures of ?25°C and +25°C, respectively) in an amorphous formulation.\\u000a Manometric temperature measurements were used to characterize product temperature (T\\u000a pr), sublimation rates, and product resistance (R\\u000a p) during primary drying. Biophysical techniques

  3. Microstructure observation and mechanical behavior modeling for limnetic nacre

    Microsoft Academic Search

    Shuchun Zuo; Yueguang Wei

    2008-01-01

    In the present research, microstructure of a kind of limnetic shell (Hyriopsis cumingii) is observed and measured by using the scanning electron microscopy, and mechanical behavior experiments of the shell nacre\\u000a are carried out by using bending and tensile tests. The dependence of mechanical properties of the shell nacre on its microstructure\\u000a is analyzed by using a modified shear-lag model,

  4. Modeling fission-gas behavior in metallic fuels

    Microsoft Academic Search

    EUGENE E. GRUBER; JOHN M. KRAMER

    1987-01-01

    The FRAS3 code, developed to model transient fission-gas behavior in oxide fuel, has been modified for application to metallic fuel. The code has been applied to analyze a series of experiments on irradiated uranium fuel, in which fission-gas bubble distributions were measured following isothermal anneals under various pressures. Comparison of the calculated bubble-size distributions to those measured indicates that grain-boundary

  5. Modeling the effect of alcohol on smoking lapse behavior

    Microsoft Academic Search

    Sherry A. McKee; Suchitra Krishnan-Sarin; Julia Shi; Tricia Mase; Stephanie S. O’Malley

    2006-01-01

    Objective  The primary aim of this project was to examine the role of alcohol use in smoking lapse behavior, as alcohol consumption is a known risk factor for poor smoking cessation outcomes.Materials and methods  We have developed a novel human laboratory model to examine two primary aspects of alcohol-mediated tobacco relapse: (1) Does alcohol facilitate the initiation of the first cigarette? (2)

  6. Engineering of Three-Dimensional Microenvironments to Promote Contractile Behavior in Primary Intestinal Organoids

    PubMed Central

    Yan, Kelley S.; Dewi, Ruby; Kuo, Calvin J.; Heilshorn, Sarah C.

    2014-01-01

    Multiple culture techniques now exist for the long-term maintenance of neonatal primary murine intestinal organoids in vitro; however, the achievement of contractile behavior within cultured organoids has thus far been infrequent and unpredictable. Here we combine finite element simulation of oxygen transport and quantitative comparative analysis of cellular microenvironments to elucidate the critical variables that promote reproducible intestinal organoid contraction. Experimentally, oxygen distribution was manipulated by adjusting the ambient oxygen concentration along with the use of semi-permeable membranes to enhance transport. The culture microenvironment was further tailored through variation of collagen type-I matrix density, addition of exogenous R-spondin1, and specification of culture geometry. “Air-liquid interface” cultures resulted in significantly higher numbers of contractile cultures relative to traditional submerged cultures. These interface cultures were confirmed to have enhanced and more symmetric oxygen transport relative to traditional submerged cultures. While oxygen availability was found to impact in vitro contraction rate and the orientation of contractile movement, it was not a key factor in enabling contractility. For all conditions tested, reproducible contractile behavior only occurred within a consistent and narrow range of collagen type-I matrix densities with porosities of approximately 20% and storage moduli near 30 Pa. This suggests that matrix density acts as a “permissive switch” that enables contractions to occur. Similarly, contractions were only observed in cultures with diameters less than 15.5 mm that had relatively large interfacial surface area between the compliant matrix and the rigid culture dish. Taken together, these data suggest that spatial geometry and mechanics of the microenvironment, which includes both the encapsulating matrix as well as the surrounding culture device, may be key determinants of intestinal organoid functionality. As peristaltic contractility is a crucial requirement for normal digestive tract function, this achievement of reproducible organoid contraction marks a pivotal advancement towards engineering physiologically functional replacement tissue constructs. PMID:24343706

  7. An information propagation model considering incomplete reading behavior in microblog

    NASA Astrophysics Data System (ADS)

    Su, Qiang; Huang, Jiajia; Zhao, Xiande

    2015-02-01

    Microblog is one of the most popular communication channels on the Internet, and has already become the third largest source of news and public opinions in China. Although researchers have studied the information propagation in microblog using the epidemic models, previous studies have not considered the incomplete reading behavior among microblog users. Therefore, the model cannot fit the real situations well. In this paper, we proposed an improved model entitled Microblog-Susceptible-Infected-Removed (Mb-SIR) for information propagation by explicitly considering the user's incomplete reading behavior. We also tested the effectiveness of the model using real data from Sina Microblog. We demonstrate that the new proposed model is more accurate in describing the information propagation in microblog. In addition, we also investigate the effects of the critical model parameters, e.g., reading rate, spreading rate, and removed rate through numerical simulations. The simulation results show that, compared with other parameters, reading rate plays the most influential role in the information propagation performance in microblog.

  8. Stochastic Models Predict User Behavior in Social Media

    E-print Network

    Hogg, Tad; Smith, Laura M

    2013-01-01

    User response to contributed content in online social media depends on many factors. These include how the site lays out new content, how frequently the user visits the site, how many friends the user follows, how active these friends are, as well as how interesting or useful the content is to the user. We present a stochastic modeling framework that relates a user's behavior to details of the site's user interface and user activity and describe a procedure for estimating model parameters from available data. We apply the model to study discussions of controversial topics on Twitter, specifically, to predict how followers of an advocate for a topic respond to the advocate's posts. We show that a model of user behavior that explicitly accounts for a user transitioning through a series of states before responding to an advocate's post better predicts response than models that fail to take these states into account. We demonstrate other benefits of stochastic models, such as their ability to identify users who a...

  9. Molecular-level engineering of protein physical hydrogels for predictive sol-gel phase behavior

    PubMed Central

    Mulyasasmita, Widya; Lee, Ji Seok; Heilshorn, Sarah C.

    2011-01-01

    Predictable tuning of bulk mechanics from the molecular level remains elusive in many physical hydrogel systems due to the reliance on non-specific and non-stoichiometric chain interactions for network formation. We describe a Mixing-Induced Two-Component Hydrogel (MITCH) system, in which network assembly is driven by specific and stoichiometric peptide-peptide binding interactions. By integrating protein science methodologies with simple polymer physics model, we manipulate the polypeptide binding interactions and demonstrate the direct ability to predict the resulting effects on network crosslinking density, sol-gel phase behavior, and gel mechanics. PMID:21861461

  10. Behavioral profiles of mouse models for autism spectrum disorders.

    PubMed

    Ey, Elodie; Leblond, Claire S; Bourgeron, Thomas

    2011-02-01

    Autism spectrum disorders (ASD) are characterized by impairments in reciprocal social communication, and stereotyped verbal and nonverbal behaviors. In approximately 10-25% of the affected individuals, a genetic mutation associated with the condition can be identified. Recently, mutations altering synapse formation, cellular/synaptic growth rate and regulation of excitatory and inhibitory currents were identified in patients with intellectual disability, typical autism, Asperger syndrome or neurological syndromes associated with autistic traits. Following these genetic findings, mouse models carrying mutations similar to those identified in patients have been generated. These models offer the opportunity to investigate in vivo the physiological and behavioral consequences of the mutations. Here, we review the existing data on the phenotypes of mice carrying mutations in genes associated with ASD including neuroligin, neurexin and Shank mutant mice as well as the Fmr1, Mecp2, Ube3a, Nf1, Pten and Tsc1/Tsc2 mutant mice. The diversity and complexity of the phenotype of these mouse models reflect the broad range of phenotypes observed in patients with ASD. Remarkably, results from therapeutic approaches (e.g., modulation of gene expression, administration of pharmacological and nonpharmacological substances, enriched environment) are encouraging since some behavioral alterations could be reversed even when treatment was performed on adult mice. These ongoing studies should therefore increase our understanding of the biological alterations associated with ASD as well as the development of knowledge-based treatments. PMID:21328568

  11. A predictive model for the mechanical behavior of particulate composites

    SciTech Connect

    Anderson, L.L.

    1989-01-01

    A method for predicting the stress-strain and volumetric behavior of particulate composites from constituent properties has been developed. These materials exhibit a phenomenon known as debonding in which filler particles pull away from the matrix material, causing ellipsoidal vacuoles to form about each particle. An energy balance derived from the first law of thermodynamics calculates critical strain values at which filler particles will debond when subjected to deformation. The model calculates the changes caused in the material due to the debonding process over each strain increment. The material is assumed to behave as a homogeneous, linear elastic solid over each increment, but the properties are allowed to change as debonding occurs. Calculations of critical strains over the experimental range of strain using reevaluated material properties accounting for the damage give highly nonlinear material properties accounting for the damage give highly nonlinear stress-strain and volumetric curves. Experimentally observed dependencies on particle size, filler concentration, matrix and filler properties, and superimposed pressure are correctly predicted. The method had no adjustable parameters, and can be generalized for any state of stress or particle shape. The model was verified by measuring the stress-strain and volumetric behavior of glass bead-filled polyurethanes over the range of parameters of interest, including particle size, concentration and adhesion. Comparisons of model predictions to both this experimental data and to literature data show good agreement. Additional investigations into the behavior of foams and rubber modified materials to explore the applicability of the approach to those systems were performed.

  12. Chemical kinetics modeling of engine knock: preliminary results

    Microsoft Academic Search

    W. J. Pitz; C. K. Westbrook

    1983-01-01

    A theoretical model, including a detailed kinetic mechanism for propane oxidation, is used to examine the ignition of propane-air mixtures under conditions of pressure and temperature encountered in knocking engines. Purely kinetic calculations are used to evaluate relative time scales for the fuel-air ignition process, varying the initial pressure, temperature, and fuel-air equivalence ratio. A one dimensional model is then

  13. Effective modeling and simulation of internal combustion engine control systems

    Microsoft Academic Search

    C. A. Rabbath; H. Desira; K. Butts

    2001-01-01

    The paper presents an integrated software-hardware solution to effectively model and simulate internal combustion engine control systems. The solution is based on RT-LABTM. The characteristics of the proposed modeling and simulation approach are the preservation of accuracy in the face of relatively large fixed simulation steps and the achievement of real-time and faster than real-time simulation execution. The results of

  14. Using a Phenomenological Computer Model to Investigate Advanced Combustion Trajectories in a CIDI Engine

    SciTech Connect

    Gao, Zhiming [ORNL; Wagner, Robert M [ORNL; Sluder, Scott [ORNL; Daw, C Stuart [ORNL; Green Jr, Johney Boyd [ORNL

    2011-01-01

    This paper summarizes results from simulations of conventional, high-dilution, and high-efficiency clean combustion in a diesel engine based on a two-zone phenomenological model. The two-zone combustion model is derived from a previously published multi-zone model, but it has been further simplified to increase computational speed by a factor of over 100. The results demonstrate that this simplified model is still able to track key aspects of the combustion trajectory responsible for NOx and soot production. In particular, the two-zone model in combination with highly simplified global kinetics correctly predicts the importance of including oxygen mass fraction (in addition to equivalence ratio and temperature) in lowering emissions from high-efficiency clean combustion. The methodology also provides a convenient framework for extracting information directly from in-cylinder pressure measurements. This feature is likely to be useful for on-board combustion diagnostics and controls. Because of the possibility for simulating large numbers of engine cycles in a short time, models of this type can provide insight into multi-cycle and transient combustion behavior not readily accessible to more computationally intensive models. Also the representation of the combustion trajectory in 3D space corresponding to equivalence ratio, flame temperature, and oxygen fraction provides new insight into optimal combustion management.

  15. The Friction Behavior of Individual Components of a Spark-Ignition Engine During Warm-Up

    Microsoft Academic Search

    C. C. Daniels; M. J. Braun

    2006-01-01

    The research presented herein fills a void in the published literature through investigation of transient friction contributions by individual internal combustion engine components during simulated engine warm-up. Currently, engine manufacturers design internal combustion engines primarily for use at steady-state operating conditions with little design consideration for transient engine warm-up. Using the motoring torque waveform and cycle-averaged data of a spark-ignition

  16. The SEM Risk Behavior (SRB) Model: A New Conceptual Model of how Pornography Influences the Sexual Intentions and HIV Risk Behavior of MSM

    PubMed Central

    Wilkerson, J. Michael; Iantaffi, Alex; Smolenski, Derek J.; Brady, Sonya S.; Horvath, Keith J.; Grey, Jeremy A.; Rosser, B. R. Simon

    2012-01-01

    While the effects of sexually explicit media (SEM) on heterosexuals’ sexual intentions and behaviors have been studied, little is known about the consumption and possible influence of SEM among men who have sex with men (MSM). Importantly, conceptual models of how Internet-based SEM influences behavior are lacking. Seventy-nine MSM participated in online focus groups about their SEM viewing preferences and sexual behavior. Twenty-three participants reported recent exposure to a new behavior via SEM. Whether participants modified their sexual intentions and/or engaged in the new behavior depended on three factors: arousal when imagining the behavior, pleasure when attempting the behavior, and trust between sex partners. Based on MSM’s experience, we advance a model of how viewing a new sexual behavior in SEM influences sexual intentions and behaviors. The model includes five paths. Three paths result in the maintenance of sexual intentions and behaviors. One path results in a modification of sexual intentions while maintaining previous sexual behaviors, and one path results in a modification of both sexual intentions and behaviors. With this model, researchers have a framework to test associations between SEM consumption and sexual intentions and behavior, and public health programs have a framework to conceptualize SEM-based HIV/STI prevention programs. PMID:23185126

  17. Predictive models of procedural human supervisory control behavior

    NASA Astrophysics Data System (ADS)

    Boussemart, Yves

    Human supervisory control systems are characterized by the computer-mediated nature of the interactions between one or more operators and a given task. Nuclear power plants, air traffic management and unmanned vehicles operations are examples of such systems. In this context, the role of the operators is typically highly proceduralized due to the time and mission-critical nature of the tasks. Therefore, the ability to continuously monitor operator behavior so as to detect and predict anomalous situations is a critical safeguard for proper system operation. In particular, such models can help support the decision J]l8king process of a supervisor of a team of operators by providing alerts when likely anomalous behaviors are detected By exploiting the operator behavioral patterns which are typically reinforced through standard operating procedures, this thesis proposes a methodology that uses statistical learning techniques in order to detect and predict anomalous operator conditions. More specifically, the proposed methodology relies on hidden Markov models (HMMs) and hidden semi-Markov models (HSMMs) to generate predictive models of unmanned vehicle systems operators. Through the exploration of the resulting HMMs in two distinct single operator scenarios, the methodology presented in this thesis is validated and shown to provide models capable of reliably predicting operator behavior. In addition, the use of HSMMs on the same data scenarios provides the temporal component of the predictions missing from the HMMs. The final step of this work is to examine how the proposed methodology scales to more complex scenarios involving teams of operators. Adopting a holistic team modeling approach, both HMMs and HSMMs are learned based on two team-based data sets. The results show that the HSMMs can provide valuable timing information in the single operator case, whereas HMMs tend to be more robust to increased team complexity. In addition, this thesis discusses the methodological and practical limitations of the proposed approach notably in terms of input data requirements and model complexity. This thesis thus provides theoretical and practical contributions by exploring the validity of using statistical models of operators as the basis for detecting and predicting anomalous conditions. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

  18. Micromechanical modeling of the elasto-viscoplastic behavior of granite

    NASA Astrophysics Data System (ADS)

    Zeng, Tao; Shao, Jian-Fu; Xu, Wei-Ya

    2015-02-01

    We present in this paper a micromechanics-based elasto-viscoplastic approach for modeling the time-dependent deformation of granite. Inspired by the polycrystalline theory of metallic materials, the sliding behavior in an individual grain is regarded as the sole source of plastic deformation, which is characterized by a Mohr-Coulomb-type yield criterion and a non-associated plastic potential. The micro-macro transition is realized within the framework of Hill's self-consistent approach. The performance of the proposed model is evaluated by several case studies and by reproducing experimental data.

  19. Model-Driven Engineering Support for Building C# Applications

    NASA Astrophysics Data System (ADS)

    Derezi?ska, Anna; O?tarzewski, Przemys?aw

    Realization of Model-Driven Engineering (MDE) vision of software development requires a comprehensive and user-friendly tool support. This paper presents a UML-based approach for building trustful C# applications. UML models are refined using profiles for assigning class model elements to C# concepts and to elements of implementation project. Stereotyped elements are verified on life and during model to code transformation in order to prevent creation of an incorrect code. The Transform OCL Fragments into C# system (T.O.F.I.C.) was created as a feature of the Eclipse environment. The system extends the IBM Rational Software Architect tool.

  20. Simplified simulation models for control studies of turbojet engines

    NASA Technical Reports Server (NTRS)

    Brennan, T. C.; Leake, R. J.

    1975-01-01

    The essential dynamical characteristics of a simple single spool turbojet engine were determined through simulation of low order system models on an analog computer. An accurate model was studied and system complexity was reduced through various linearizations and approximations. A derivation of a seventh order simplified simulation model is presented with a derivation of an even simpler third order model, and simulation results from each. The control problem studied is one of getting from zero fuel flow equilibrium to a high thrust equilibrium while taking into account surge margin and turbine inlet temperature constraints.