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1

Updating the Behavior Engineering Model.  

ERIC Educational Resources Information Center

Considers Thomas Gilbert's Behavior Engineering Model as a tool for systematically identifying barriers to individual and organizational performance. Includes a detailed case study and a performance aid that incorporates gap analysis, cause analysis, and force field analysis to update the original model. (Author/LRW)

Chevalier, Roger

2003-01-01

2

Gilbert's Behavior Engineering Model: Contemporary Support for an Established Theory  

ERIC Educational Resources Information Center

This study was an effort to add to the body of research surrounding Gilbert's Behavior Engineering Model (BEM). The model was tested to determine its ability to explain factor relationships of organizational safety culture in a high-risk work environment. Three contextual variables were measured: communication, resource availability, and…

Crossman, Donna Cangelosi

2010-01-01

3

The Virtual Office: A Behavior Engineering Model (BEM) Perspective.  

ERIC Educational Resources Information Center

Discusses issues associated with the virtual office. Summarizes advantages and disadvantages from employees' and employers' perspectives. Uses the behavior engineering model (Thomas Gilbert, 1996) as a framework to analyze different factors related to performance, and suggests the application of other concepts from human performance technology and…

Austin, John; Garnier, Luis

1998-01-01

4

Chain models of physical behavior for engineering analysis and design  

Microsoft Academic Search

The relationship between geometry (form) and physical behavior (function) dominates many engineering activities. The lack of uniform and rigorous computational models for this relationship has resulted in a plethora of inconsistent (and thus usually incompatible) computer-aided design (CAD) tools and systems, causing unreasonable overhead in time, effort, and cost, and limiting the extent to which CAD tools are used in

Richard S. Palmer; Vadim Shapiro

1993-01-01

5

The Theory of Planned Behavior as a Model of Academic Dishonesty in Engineering and Humanities Undergraduates  

Microsoft Academic Search

This study examines the use of a modified form of the theory of planned behavior in understanding the decisions of undergraduate students in engineering and humanities to engage in cheating. We surveyed 527 randomly selected students from three academic institutions. Results supported the use of the model in predicting ethical decision-making regarding cheating. In particular, the model demonstrated how certain

Trevor S. Harding; Matthew J. Mayhew; Cynthia J. Finelli; Donald D. Carpenter

2007-01-01

6

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

Microsoft Academic Search

The development of a robust and reliable material model for fabrics used to prevent fan blade-out events in propulsion engines has significant importance in the design of fan-containment systems. Currently, Kevlar is the only fabric approved by the Federal Aviation Administration to be used in fan-containment systems. However, very little work has been done in building a mechanistic-based material behavior

S. Bansal; B. Mobasher; S. D. Rajan; I. Vintilescu

2009-01-01

7

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

Microsoft Academic Search

Mechanical models have potential to guide the development and use of engineered blood vessels as well as other engineered\\u000a tissues. This paper presents a microstructurally motivated, pseudoelastic, mechanical model of the biaxial mechanics of engineered\\u000a vessels in the physiologic pressure range. The model incorporates experimentally measured densities and alignments of engineered\\u000a collagen. Specifically, these microstructural and associated mechanical inputs were

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

2008-01-01

8

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

PubMed Central

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.

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

9

Health Behaviors of Operating Engineers  

PubMed Central

RESEARCH ABSTRACT Operating Engineers (heavy equipment operators in construction) may be at particular risk for heart disease and cancer related to their exposure to environmental dust and smoking, the sedentary nature of their job, and long hours of exposure to the sun. The aim of this study was to characterize the health behaviors of Operating Engineers. This cross-sectional survey from a convenience sample of Operating Engineers (N = 498) used validated instruments to measure smoking, drinking, diet, exercise, sleep, and sun exposure. Univariate and bivariate analyses to detect differences by age were conducted. The sample scored significantly worse on all five health behaviors compared to population norms. Those who were older were less likely to smoke and chew tobacco and more likely to eat fruits and vegetables. Many were interested in services to improve their health behaviors. Health behavior interventions are needed and wanted by Operating Engineers.

Duffy, Sonia A.; Missel, Amanda L.; Waltje, Andrea H.; Ronis, David L.; Fowler, Karen E.; Hong, OiSaeng

2013-01-01

10

The use of mathematical models to predict beach behavior for U.S. coastal engineering: A critical review  

USGS Publications Warehouse

A number of assumed empirical relationships (e.g., the Bruun Rule, the equilibrium shoreface profile, longshore transport rate equation, beach length: durability relationship, and the renourishment factor) and deterministic numerical models (e.g., GENESIS, SBEACH) have become important tools for investigating coastal processes and for coastal engineering design in the U.S. They are also used as the basis for making public policy decisions, such as the feasibility of nourishing recreational beaches. A review of the foundations of these relationships and models, however, suggests that they are inadequate for the tasks for which they are used. Many of the assumptions used in analytical and numerical models are not valid in the context of modern oceanographic and geologic principles. We believe the models are oversimplifications of complex systems that are poorly understood. There are several reasons for this, including: (1) poor assumptions and important omissions in model formulation; (2) the use of relationships of questionable validity to predict the morphologic response to physical forcing; (3) the lack of hindsighting and objective evaluation of beach behavior predictions for engineering projects; (4) the incorrect use of model calibration and verification as assertions of model veracity; and (5) the fundamental inability to predict coastal evolution quantitatively at the engineering and planning time and space scales our society assumes and demands. It is essential that coastal geologists, beach designers and coastal modelers understand these model limitations. Each important model assumption must be examined in isolation; incorporating them into a model does not improve their validity. It is our belief that the models reviewed here should not be relied on as a design tool until they have been substantially modified and proven in real-world situations. The 'solution,' however, is not to increase the complexity of a model by increasing the number of variables. What is needed is a thoughtful review of what beach behavior questions should or could be answered by modeling. Viable alternatives to the use of models do exist to predict the behavior of beaches. Three such alternatives to models are discussed for nourished beach design.

Thieler, E. R.; Pilkey, Jr. , O. H.; Young, R. S.; Bush, D. M.; Chai, F.

2000-01-01

11

Model Behavior  

ERIC Educational Resources Information Center

There are dozens of books and hundreds of resources that address the issue of character development in students: how to raise them to be good people, how to teach them to be good citizens, how to help them to make good decisions. Little is written, however, about the character development of principals and school leaders, whose behavior is a model

Holloway, John

2006-01-01

12

The Behavior Engineering Model at Work on a Small Scale: Using Task Clarification, Self-Monitoring, and Public Posting To Improve Customer Service.  

ERIC Educational Resources Information Center

Explains Gilbert's Behavior Engineering Model that can enable the success of novice performance engineers by prompting appropriate front-end analysis and describes a performance improvement project conducted in the customer service department at an insurance agency. Discusses task clarification, employee self-monitoring, and public posting of…

Austin, John; Olson, Ryan; Wellisley, Julie Ann

2001-01-01

13

Characterizing and predicting search engine switching behavior  

Microsoft Academic Search

Search engine switching describes the voluntarily transition from one Web search engine to another. In this paper we present a study of search engine switching behavior that combines large- scale log-based analysis and survey data. We characterize aspects of switching behavior, and develop and evaluate predictive mod- els of switching behavior using features of the active query, the current session,

Ryen W. White; Susan T. Dumais

2009-01-01

14

Behavioral Misconceptions Facing the Software Engineer.  

National Technical Information Service (NTIS)

The paper discusses common misconceptions of a software engineer in the design of a practical information system. These misconceptions concern the usage and behavioral patterns of the scientists, engineers, and managers for whom the system is designed.

1970-01-01

15

Mathematical Model For Engineering Analysis And Optimization  

NASA Technical Reports Server (NTRS)

Computational support for engineering design process reveals behavior of designed system in response to external stimuli; and finds out how behavior modified by changing physical attributes of system. System-sensitivity analysis combined with extrapolation forms model of design complementary to model of behavior, capable of direct simulation of effects of changes in design variables. Algorithms developed for this method applicable to design of large engineering systems, especially those consisting of several subsystems involving many disciplines.

Sobieski, Jaroslaw

1992-01-01

16

Behavior of engineered nanoparticles in landfill leachate.  

PubMed

This research sought to understand the behavior of engineered nanoparticles in landfill leachate by examining the interactions between nanoparticles and leachate components. The primary foci of this paper are the effects of ZnO, TiO2, and Ag nanoparticles on biological landfill processes and the form of Zn, Ti, and Ag in leachate following the addition of nanoparticles. Insight into the behavior of nanoparticles in landfill leachate was gained from the observed increase in the aqueous concentrations over background for Zn, Ti, and Ag in some tested leachates attributed to leachate components interacting with the nanoparticle coatings resulting in dispersion, dissolution/dissociation, and/or agglomeration. Coated nanoparticles did not affect biological processes when added to leachate; five-day biochemical oxygen demand and biochemical methane potential results were not statistically different when exposed to nanoparticles, presumably due to the low concentration of dissolved free ionic forms of the associated metals resulting from the interaction with leachate components. Chemical speciation modeling predicted that dissolved Zn in leachate was primarily associated with dissolved organic matter, Ti with hydroxide, and Ag with hydrogen sulfide and ammonia; less than 1% of dissolved Zn and Ag was in the free ionic form, and free ionic Ti and Ag concentrations were negligible. PMID:23799646

Bolyard, Stephanie C; Reinhart, Debra R; Santra, Swadeshmukul

2013-08-01

17

Principles of models based engineering  

SciTech Connect

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.

Dolin, R.M.; Hefele, J.

1996-11-01

18

Statistical model for the mechanical behavior of the tissue engineering non-woven fibrous matrices under large deformation.  

PubMed

The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues due to their structural and mechanical similarities with the fibrous components of the extracellular matrix. These scaffolds not only provide the appropriate microenvironment for the residing cells but also act as medium for the transmission of the mechanical stimuli, essential for the tissue regeneration, from macroscopic scale of the scaffolds to the microscopic scale of cells. The requirement of the mechanical loading for the tissue regeneration requires the fibrous scaffolds to be able to sustain the complex three-dimensional mechanical loading conditions. In order to gain insight into the mechanical behavior of the fibrous matrices under large amount of elongation as well as shear, a statistical model has been formulated to study the macroscopic mechanical behavior of the electrospun fibrous matrix and the transmission of the mechanical stimuli from scaffolds to the cells via the constituting fibers. The study establishes the load-deformation relationships for the fibrous matrices for different structural parameters. It also quantifies the changes in the fiber arrangement and tension generated in the fibers with the deformation of the matrix. The model reveals that the tension generated in the fibers on matrix deformation is not homogeneous and hence the cells located in different regions of the fibrous scaffold might experience different mechanical stimuli. The mechanical response of fibrous matrices was also found to be dependent on the aspect ratio of the matrix. Therefore, the model establishes a structure-mechanics interdependence of the fibrous matrices under large deformation, which can be utilized in identifying the appropriate structure and external mechanical loading conditions for the regeneration of load-bearing tissues. PMID:24956158

Rizvi, Mohd Suhail; Pal, Anupam

2014-09-01

19

A review of Continuum Electrochemical Engineering Models and a Novel Monte Carlo Approach to Understand Electrochemical Behavior of Lithium-Ion Batteries  

NASA Astrophysics Data System (ADS)

Electrochemical phenomenon associated with systems from electrochemical energy (Batteries, Fuel cells and capacitors) to electro deposition are multistep and multi-phenomena processes and hence can be very tedious to simulate. The multi-phenomena characteristics of the processes involved in electro deposition and other electrochemical systems including electrochemical power sources pose inherent difficulties in writing efficient algorithms. These processes also encompass varied length and time scales again posing barriers to efficient simulation. Traditionally, continuum models have been used to simulate electrochemical systems and have been the chief tool for researchers in this field. The behavior of battery systems for example have been sufficiently described by continuum models for the last two decades. Continuum modeling is an attractive tool for battery systems design and optimization studies apart from its ability to predict transport and thermal behavior. In this chapter, a brief review of continuum electrochemical engineering models for lithium-ion batteries is provided. The capabilities and limitations of these models are discussed. Next, a continuum Monte Carlo approach is proposed to characterize the cathode material of lithium-ion batteries.

Diwakar, Vinten D.; Harinipriya, S.; Subramanian, Venkat R.

20

Modeling User Click Behavior in Sponsored Search  

Microsoft Academic Search

There has been significant recent interest in studying consumer behavior in sponsored search en- vironments. Researchers have typically used aggregate data provided to advertisers by search engines to model consumer behavior. The data typically catalogue advertiser's bid, average position and total impressions, clicks and cost on a daily basis for keywords in the advertisers sponsored search campaign. Random utility models

Vibhanshu Abhishek; Peter S. Fader; Kartik Hosanagar

21

Advancements in engineering turbulence modeling  

NASA Technical Reports Server (NTRS)

Some new developments in two-equation models and second order closure models are presented. Two-equation models (k-epsilon models) have been widely used in computational fluid dynamics (CFD) for engineering problems. Most of low-Reynolds number two-equation models contain some wall-distance damping functions to account for the effect of wall on turbulence. However, this often causes the confusion and difficulties in computing flows with complex geometry and also needs an ad hoc treatment near the separation and reattachment points. A set of modified two-equation models is proposed to remove the aforementioned shortcomings. The calculations using various two-equation models are compared with direct numerical simulations of channel flow and flat boundary layers. Development of a second order closure model is also discussed with emphasis on the modeling of pressure related correlation terms and dissipation rates in the second moment equations. All the existing models poorly predict the normal stresses near the wall and fail to predict the 3-D effect of mean flow on the turbulence (e.g. decrease in the shear stress caused by the cross flow in the boundary layer). The newly developed second order near-wall turbulence model is described and is capable of capturing the near-wall behavior of turbulence as well as the effect of 3-D mean flow on the turbulence.

Shih, T.-H.

1991-01-01

22

MODEL OF TOXICANT RESPONSE IN ENGINEERED LIVER  

EPA Science Inventory

This project proposes to: engineer a tissue to mimic liver behavior (a so-called 3-Dimensional or 3D liver model); simulate liver toxicity by exposing the 3D liver model to two known toxicants ( carbon tetrachloride and 1,2 dichloroethylene); and ...

23

Towards Behavioral Reflexion Models  

NASA Technical Reports Server (NTRS)

Software architecture has become essential in the struggle to manage today s increasingly large and complex systems. Software architecture views are created to capture important system characteristics on an abstract and, thus, comprehensible level. As the system is implemented and later maintained, it often deviates from the original design specification. Such deviations can have implication for the quality of the system, such as reliability, security, and maintainability. Software architecture compliance checking approaches, such as the reflexion model technique, have been proposed to address this issue by comparing the implementation to a model of the systems architecture design. However, architecture compliance checking approaches focus solely on structural characteristics and ignore behavioral conformance. This is especially an issue in Systems-of- Systems. Systems-of-Systems (SoS) are decompositions of large systems, into smaller systems for the sake of flexibility. Deviations of the implementation to its behavioral design often reduce the reliability of the entire SoS. An approach is needed that supports the reasoning about behavioral conformance on architecture level. In order to address this issue, we have developed an approach for comparing the implementation of a SoS to an architecture model of its behavioral design. The approach follows the idea of reflexion models and adopts it to support the compliance checking of behaviors. In this paper, we focus on sequencing properties as they play an important role in many SoS. Sequencing deviations potentially have a severe impact on the SoS correctness and qualities. The desired behavioral specification is defined in UML sequence diagram notation and behaviors are extracted from the SoS implementation. The behaviors are then mapped to the model of the desired behavior and the two are compared. Finally, a reflexion model is constructed that shows the deviations between behavioral design and implementation. This paper discusses the approach and shows how it can be applied to investigate reliability issues in SoS.

Ackermann, Christopher; Lindvall, Mikael; Cleaveland, Rance

2009-01-01

24

Behavioral economics in software quality engineering  

Microsoft Academic Search

This article describes empirical research results regarding the “history effect” in software quality evaluation processes.\\u000a Most software quality models and evaluation processes models assume that software quality may be deterministically evaluated,\\u000a especially when it is evaluated by experts. Consequently, software developers focus on the technical characteristics of the\\u000a software product. A similar assumption is common in most engineering disciplines. However,

Radoslaw Hofman

2011-01-01

25

Frameworks and Models in Engineering Systems / Engineering System Design  

NSDL National Science Digital Library

This class, created by Prof. Joseph Sussman of the Massachusetts Institute of Technology, provides an introduction to quantitative models and qualitative frameworks for studying complex engineering systems. Also taught is the art of abstracting a complex system into a model for purposes of analysis and design while dealing with complexity, emergent behavior, stochasticity, non-linearities and the requirements of many stakeholders with divergent objectives. The successful completion of the class requires a semester-long class project that deals with critical contemporary issues which require an integrative, interdisciplinary approach using the above models and frameworks.

Sussman, Joseph

2011-01-20

26

Efficient Model-Based Diagnosis Engine  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

27

Pedestrian travel behavior modeling  

Microsoft Academic Search

This paper presents a dynamic mixed discrete-continuous choice approach to modeling pedes- trian travel and activity choice behavior in public facilities. The approach views revealed behav- ior as a manifestation of pedestrians' preferences by assuming that pedestrians choose the alter- native that maximizes expected (subjective) utility, while taking into account the uncertainty in expected traffic conditions. The choice dimensions are

Serge P. Hoogendoorn

2003-01-01

28

Workshop on Engineering Turbulence Modeling  

Microsoft Academic Search

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

Louis A. Povinelli; W. W. Liou; A. Shabbir; T.-H. Shih

1992-01-01

29

Cyclic behavior modelling  

NASA Astrophysics Data System (ADS)

An extension of a basic model, initially made for sand modeling is developed with the object of using it for clays. The formal principles of elastoplasticity as well as the origin of plasticity surface forms that are commonly used for soils are reviewed. This basic model was applied to study the behavior of clay by cyclic torsion experiments. The results show that it is not possible to reproduce dilatancy appearance in undrained cyclic experiments if the clay is normally consolidated. An analysis on how to introduce a Cam-Clay type closed surface into the basic model is given. The consolidation mechanisms as well as the deviatoric mechanisms of the proposed model extension are described. The identification process of the parameters for the proposed model is summarized. An analytical process of identification from drained and undrained experiments is given. The analysis of the simulation results conducted is included.

Dubujet, Philippe

1992-07-01

30

Pulse Detonation Engine Modeled.  

National Technical Information Service (NTIS)

Pulse Detonation Engine Technology is currently being investigated at Glenn for both airbreathing and rocket propulsion applications. The potential for both mechanical simplicity and high efficiency due to the inherent near-constant-volume combustion proc...

D. E. Paxson

2001-01-01

31

Rocket engine diagnostics using qualitative modeling techniques  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

32

Rocket engine diagnostics using qualitative modeling techniques  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

33

Advancements in Engineering Turbulence Modeling.  

National Technical Information Service (NTIS)

Some new developments in two-equation models and second order closure models are presented. Two-equation models (k-epsilon models) have been widely used in computational fluid dynamics (CFD) for engineering problems. Most of low-Reynolds number two-equati...

T. Shih

1991-01-01

34

Workshop on Engineering Turbulence Modeling  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

35

Workshop on Engineering Turbulence Modeling  

SciTech Connect

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.

Povinelli, L.A.; Liou, W.W.; Shabbir, A.; Shih, T.H.

1992-03-01

36

Modeling Network Traffic with Multifractal Behavior  

Microsoft Academic Search

Abstract. The traffic engineering of IP networks requires accurate characteriz ation and modeling of network traffic, due to the growing diversity of multimedia application s and the need to efficiently support QoS differentiation in the network. In recent years several types of traffic behavior, that can have significant impact on network performance, were discovered: longrange dependence, self-similarity and, more recently,

António Nogueira; Paulo Salvador; Rui Valadas; António Pacheco

2003-01-01

37

Model Engineering using Multimodeling.  

National Technical Information Service (NTIS)

We study the simultaneous use of multiple modeling techniques in the design of embedded systems. We begin with a pre-existing Statecharts model of a simple case study, a traffic light for a pedestrian crossing. This model combines two distinct models of c...

C. Brooks C. P. Cheng E. A. Lee R. Von Hanxleden T. H. Feng

2008-01-01

38

Parallel processor engine model program  

NASA Technical Reports Server (NTRS)

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.

Mclaughlin, P.

1984-01-01

39

IUTAM Symposium on Multiscale Modeling and Characterization of Elastic-Inelastic Behavior of Engineering Materials : proceedings of the IUTAM Symposium held in Marrakech, Morocco, 20-25 October, 2002. Solid Mechanics and its Applications  

SciTech Connect

The papers in this proceeding are a collection of the works presented at the IUTAM symposium-Marrakech 2002 (October 20-25) which brought together scientists from various countries. These papers cover contemporary topics in multiscale modeling and characterization of materials behavior of engineering materials. They were selected to focus on topics related to deformation and failure in metals, alloys, intermetallics and polymers including: experimental techniques, deformation and failure mechanisms, dislocation-based modeling, microscopic-macroscopic averaging schemes, application to forming processes and to phase transformation, localization and failure phenomena, and computational advances.

Ahzi, Said; Cherkaoui, Mohammed; Khaleel, Mohammad A.; Zbib, Hussein M.; Zikry, M A.; LaMatina, B

2004-03-01

40

Process Modeling (Engineering Statistics Handbook)  

NSDL National Science Digital Library

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.

Filliben, James; Heckert, Alan

2009-02-26

41

Nanoparticle engineering of colloidal suspension behavior  

Microsoft Academic Search

We investigate the effects of highly charged nanoparticles on the phase behavior, structure, and assembly of colloidal microsphere suspensions. Specifically, by selectively tuning the electrostatic interactions between silica microspheres and polystyrene nanoparticles, we study the behavior of four key systems: (i) strongly repulsive, (ii) haloing, (iii) weakly attractive, and (iv) strongly attractive systems. In each system, a combination of nanoparticle

Angel Thanda Chan

2007-01-01

42

Atmospheric Models for Engineering Applications  

NASA Technical Reports Server (NTRS)

This paper will review the historical development of reference and standard atmosphere models and their applications. The evolution of the U.S. Standard Atmosphere will be addressed, along with the Range Reference Atmospheres and, in particular, the NASA Global Reference Atmospheric Model (GRAM). The extensive scope and content of the GRAM will be addressed since it represents the most extensive and complete 'Reference' atmosphere model in use today. Its origin was for engineering applications and that remains today as its principal use.

Johnson, Dale L.; Roberts, Barry C.; Vaughan, William W.; Justus, C. G.

2002-01-01

43

Behavioral styles of engineers in a research and development organization  

Microsoft Academic Search

The purpose of the thesis was twofold. First, it determined if there was a behavioral preference of engineers in a technical expert, project leader and line supervisor\\/manager role. Second, it tested whether there was a correlation between the behavioral preference, job assignment and job satisfaction. 17 refs., 13 tabs.

1988-01-01

44

Stirling Engine Dynamic System Modeling  

NASA Technical Reports Server (NTRS)

The Thermo-Mechanical systems branch at the Glenn Research Center focuses a large amount time on Stirling engines. These engines will be used on missions where solar power is inefficient, especially in deep space. I work with Tim Regan and Ed Lewandowski who are currently developing and validating a mathematical model for the Stirling engines. This model incorporates all aspects of the system including, mechanical, electrical and thermodynamic components. Modeling is done through Simplorer, a program capable of running simulations of the model. Once created and then proven to be accurate, a model is used for developing new ideas for engine design. My largest specific project involves varying key parameters in the model and quantifying the results. This can all be done relatively trouble-free with the help of Simplorer. Once the model is complete, Simplorer will do all the necessary calculations. The more complicated part of this project is determining which parameters to vary. Finding key parameters depends on the potential for a value to be independently altered in the design. For example, a change in one dimension may lead to a proportional change to the rest of the model, and no real progress is made. Also, the ability for a changed value to have a substantial impact on the outputs of the system is important. Results will be condensed into graphs and tables with the purpose of better communication and understanding of the data. With the changing of these parameters, a more optimal design can be created without having to purchase or build any models. Also, hours and hours of results can be simulated in minutes. In the long run, using mathematical models can save time and money. Along with this project, I have many other smaller assignments throughout the summer. My main goal is to assist in the processes of model development, validation and testing.

Nakis, Christopher G.

2004-01-01

45

Graphical animation of behavior models  

Microsoft Academic Search

Graphical animation is a way of visualizing the behavior of design models. This visualization is of use in validating a design model against informally specified requirements and in interpreting the meaning and significance of analysis results in relation to the problem domain. In this paper we describe how behavior models specified by Labeled Transition Systems (LTS) can drive graphical animations.

Jeff Magee; Nat Pryce; Dimitra Giannakopoulou; Jeff Kramer

2000-01-01

46

Engine environmental effects on composite behavior  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

47

Hyperbranched Polymers - Engineering Materials and Degradation Behavior.  

National Technical Information Service (NTIS)

Hyperbranched polymers of unique compositions were studied for their mechanical properties and degradation behaviors. Highly branched polymeric architectures have been shown to exhibit properties that are unique to those of linear polymer materials. In th...

K. L. Wooley

2000-01-01

48

Statistical Models for Behavioral Observations.  

ERIC Educational Resources Information Center

Natural statistical models based on renewal processes for individuals' Behavior Stream are developed. For continuous observation, statistical and psychometric properties are obtained for empirical: (1) rates of behavior; (2) proportions of behavior type; (3) prevalence; and (4) event duration. Results provide a guide for design and analysis. (SLD)

Rogosa, David; Ghandour, Ghassan

1991-01-01

49

Modeling and control of gasoline direct injection stratified charge (DISC) engines  

Microsoft Academic Search

In this paper, we present a phenomenological nonlinear dynamic model for direct injection stratified charge (DISC) gasoline engines and discuss several key control problems for this advanced technology powertrain. The model is developed and validated using dynamometer engine mapping data obtained from a 4-cylinder DISC engine. It captures the static behavior of the key components of a DISC engine, such

Jing Sun; Ilya Kolmanovsky; Diana Brehob; Jeffrey A. Cook; Julie Buckland; MO Haghgooie

1999-01-01

50

Process Model Applicable to Software Engineering and Knowledge Engineering  

Microsoft Academic Search

Software engineering (SE) and knowledge engineering (KE) develop software systems usingdifferent construction process models. Because of the growing complexity of the problems to besolved by computers, the conventional systems (CS) and knowledge-based systems (KBS)software process is at present passing through a period of integration. In this paper, we propose asoftware process model applicable to both CS and KBS. The model

Silvia Teresita Acuña; Marta López; Natalia Juristo Juzgado; Ana María Moreno

1999-01-01

51

Model-Driven Useware Engineering  

NASA Astrophysics Data System (ADS)

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.

Meixner, Gerrit; Seissler, Marc; Breiner, Kai

52

AISI/DOE Advanced Process Control Program Vol. 3 of 6: MICROSTRUCTURAL ENGINEERING IN HOT-STRIP MILLS Part 2 of 2: Constitutive Behavior Modeling of Steels Under Hot-Rolling Conditions  

SciTech Connect

This report describes the development of models for predicting (1) constitutive behaviors and (2) mechanical properties of hot-rolled steels as functions of chemical composition, microstructural features, and processing variables. The study includes the following eight steels: A36, DQSK, HSLA-V, HSLA-Nb, HSLA-50/Ti-Nb, and two interstitial-free (IF) grades. These developed models have been integrated into the Hot-Strip Mill Model (HSMM), which simulates the hot strip rolling mills and predicts the mechanical properties of hot-rolled products. The HSMM model has been developed by the University of British Columbia-Canada as a part of project on the microstructural engineering in hot-strip mills.

Yi-Wen Cheng; Patrick Purtscher

1999-07-30

53

Modeling of knock in spark-ignition engines  

Microsoft Academic Search

The chemical kinetic modeling of end gas autoignition leading to knocking behavior in spark ignition engines is discussed. The demands placed upon kinetic models by the conditions of temperature and pressure are examined, and the construction of both highly detailed and of more global or reduce kinetic models is outlined. Methods for including the influences of such factors as fuel

C. K. Westbrook; W. J. Pitz

1990-01-01

54

Editor's Roundtable: Model behavior  

NSDL National Science Digital Library

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,

Liftig, Inez

2010-11-01

55

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

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

56

Modeling the internal combustion engine  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

57

Engine Structures Modeling Software System (ESMOSS)  

NASA Technical Reports Server (NTRS)

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.

1991-01-01

58

Behavior model for performance assessment.  

SciTech Connect

Every individual channels information differently based on their preference of the sensory modality or representational system (visual auditory or kinesthetic) we tend to favor most (our primary representational system (PRS)). Therefore, some of us access and store our information primarily visually first, some auditorily, and others kinesthetically (through feel and touch); which in turn establishes our information processing patterns and strategies and external to internal (and subsequently vice versa) experiential language representation. Because of the different ways we channel our information, each of us will respond differently to a task--the way we gather and process the external information (input), our response time (process), and the outcome (behavior). Traditional human models of decision making and response time focus on perception, cognitive and motor systems stimulated and influenced by the three sensory modalities, visual, auditory and kinesthetic. For us, these are the building blocks to knowing how someone is thinking. Being aware of what is taking place and how to ask questions is essential in assessing performance toward reducing human errors. Existing models give predications based on time values or response times for a particular event, and may be summed and averaged for a generalization of behavior(s). However, by our not establishing a basic understanding of the foundation of how the behavior was predicated through a decision making strategy process, predicative models are overall inefficient in their analysis of the means by which behavior was generated. What is seen is the end result.

Borwn-VanHoozer, S. A.

1999-07-23

59

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

60

Behavioral frontiers in choice modeling  

Microsoft Academic Search

We review the discussion at a workshop whose goal was to achieve a better integration among behavioral, economic, and statistical\\u000a approaches to choice modeling. The workshop explored how current approaches to the specification, estimation, and application\\u000a of choice models might be improved to better capture the diversity of processes that are postulated to explain how consumers\\u000a make choices. Some specific

Wiktor Adamowicz; David Bunch; Trudy Ann Cameron; Benedict G. C. Dellaert; Michael Hanneman; Michael Keane; Jordan Louviere; Robert Meyer; Thomas Steenburgh; Joffre Swait

2008-01-01

61

Box-Cox Mixed Logit Model for Travel Behavior Analysis  

Microsoft Academic Search

To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their

Alfonso Orro; Margarita Novales; Francisco G. Benitez

2010-01-01

62

Planar Biaxial Behavior of Fibrin-Based Tissue-Engineered Heart Valve Leaflets  

PubMed Central

To design more effective tissue-engineered heart valve replacements, the replacement tissue may need to mimic the biaxial stress–strain behavior of native heart valve tissue. This study characterized the planar biaxial properties of tissue-engineered valve leaflets and native aortic valve leaflets. Fibrin-based valve equivalent (VE) and porcine aortic valve (PAV) leaflets were subjected to incremental biaxial stress relaxation testing, during which fiber alignments were measured, over a range of strain ratios. Results showed that VE leaflets exhibited a modulus and fiber reorientation behavior that correlated with strain ratio. In contrast, PAV leaflets maintained their relaxed modulus and fiber alignment when exposed to nonequibiaxial strain, but exhibited changes in stress relaxation. In uniaxial and equi-biaxial tension, there were few observed differences in relaxation behavior between VE and PAV leaflets, despite differences in the modulus and fiber reorientation. Likewise, in both tissues there was similar relaxation response in the circumferential and radial directions in biaxial tension, despite different moduli in these two directions. This study presents some fundamental differences in the mechanical response to biaxial tension of fibrin-based tissue-engineered constructs and native valve tissue. It also highlights the importance of using a range of strain ratios when generating mechanical property data for valvular and engineered tissues. The data presented on the stress–strain, relaxation, and fiber reorientation of VE tissue will be useful in future efforts to mathematically model and improve fibrin-based tissue-engineered constructs.

Robinson, Paul S.

2009-01-01

63

Clinician Search Behaviors May Be Influenced by Search Engine Design  

PubMed Central

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.

Coiera, Enrico; Zrimec, Tatjana; Compton, Paul

2010-01-01

64

Parametric Model of an Aerospike Rocket Engine  

NASA Technical Reports Server (NTRS)

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.

Korte, J. J.

2000-01-01

65

Parametric Model of an Aerospike Rocket Engine  

NASA Technical Reports Server (NTRS)

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.

Korte, J. J.

2000-01-01

66

75 FR 68179 - Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines  

Federal Register 2010, 2011, 2012, 2013

...Directives; Austro Engine GmbH Model E4 Diesel Piston Engines AGENCY: Federal Aviation...applies to Austro Engine GmbH model E4 diesel piston engines. These engines are installed...Contact Austro Engine GmbH, Rudolf-Diesel- Strasse 11, A-2700 Weiner...

2010-11-05

67

Laser docking sensor engineering model  

NASA Astrophysics Data System (ADS)

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.

Dekome, Kent; Barr, Joseph M.

68

A moderation model of political behavior  

Microsoft Academic Search

The study tests a moderation model of political behavior. Specifically, we propose that an individual's perceptions of organizational politics (POPs) influence his or her own political behavior engagement, while the POPs-political behavior linkage varies across different individual political skill levels. For those politically skilled individuals, the POPs-political behavior relationship will be positively stronger. In the model we also specify the

Liu Jun; Yu Guang-tao; Liu Gang

2009-01-01

69

Modelling soot formation in a DISI engine  

Microsoft Academic Search

In this work, the formation of soot in a Direct Injection Spark Ignition (DISI) engine is simulated using the Stochastic Reactor Model (SRM) engine code. Volume change, convective heat transfer, turbulent mixing, direct injection and flame propagation are accounted for. In order to simulate flame propagation, the cylinder is divided into an unburned, entrained and burned zone, with the rate

Jonathan Etheridge; Sebastian Mosbach; Markus Kraft; Hao Wu; Nick Collings

2011-01-01

70

An EHF telecommunication system engineering model  

Microsoft Academic Search

An extremely high frequency telecommunication system engineering model (ETSEM) was developed as an aid in the design of line-of-sight (LOS) communication systems from 10 to 100 GHz. ETSEM provides tabulation of path geometry parameters and analyzes ray path and Fresnel zone clearances to help the engineer design the path. ETSEM also predicts the performance (availability) of both digital and analog

Kenneth C. Allen

1987-01-01

71

76 FR 56637 - Airworthiness Directives; Lycoming Engines Model IO-720-A1B Reciprocating Engines  

Federal Register 2010, 2011, 2012, 2013

...Airworthiness Directives; Lycoming Engines Model IO-720-A1B Reciprocating Engines AGENCY...airworthiness directive (AD) for certain model IO-720-A1B Lycoming Engines reciprocating...AD will affect two Lycoming Engines model IO- 720-A1B reciprocating engines,...

2011-09-14

72

Teaching Behavioral Modeling and Simulation Techniques for Power Electronics Courses  

ERIC Educational Resources Information Center

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,"…

Abramovitz, A.

2011-01-01

73

Thrust modeling for hypersonic engines  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

74

Memory models of adaptive behavior.  

PubMed

Adaptive response to varying environment is a common feature of biological organisms. Reproducing such features in electronic systems and circuits is of great importance for a variety of applications. We consider memory models inspired by an intriguing ability of slime molds to both memorize the period of temperature and humidity variations and anticipate the next variations to come, when appropriately trained. Effective circuit models of such behavior are designed using: 1) a set of LC contours with memristive damping and 2) a single memcapacitive system-based adaptive contour with memristive damping. We consider these two approaches in detail by comparing their results and predictions. Finally, possible biological experiments that would discriminate between the models are discussed. In this paper, we also introduce an effective description of certain memory circuit elements. PMID:24808580

Traversa, Fabio Lorenzo; Pershin, Yuriy V; Di Ventra, Massimiliano

2013-09-01

75

Outer planet probe engineering model structural tests  

NASA Technical Reports Server (NTRS)

A series of proof of concept structural tests was performed on an engineering model of the Outer Planets Atmospheric Entry Probe. The tests consisted of pyrotechnic shock, dynamic and static loadings. The tests partially verified the structural concept.

Smittkamp, J. A.; Gustin, W. H.; Griffin, M. W.

1977-01-01

76

Information Needs and Information-Gathering Behavior of Research Engineers.  

ERIC Educational Resources Information Center

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

Siess, Judith A.

77

Learning to Model in Engineering  

ERIC Educational Resources Information Center

Policymakers and education scholars recommend incorporating mathematical modeling into mathematics education. Limited implementation of modeling instruction in schools, however, has constrained research on how students learn to model, leaving unresolved debates about whether modeling should be reified and explicitly taught as a competence, whether…

Gainsburg, Julie

2013-01-01

78

Dynamic modeling of a lean NOx trap for lean burn engine control  

Microsoft Academic Search

A control oriented dynamic model of the lean NOx trap (LNT) behavior has been developed in SIMULINKTM. The model simulates the trapping and purging phenomena and includes the important parameters which affect the LNT behavior. These include the trap temperature, trapping and purging duration, air\\/fuel ratios and the mass flow rates of the exhaust gases. Engine dynamometer test data have

Yanying Wang; Shankar Raman; Jessy W. Grizzle

1999-01-01

79

The NASA Marshall engineering thermosphere model  

NASA Technical Reports Server (NTRS)

Described is the NASA Marshall Engineering Thermosphere (MET) Model, which is a modified version of the MFSC/J70 Orbital Atmospheric Density Model as currently used in the J70MM program at MSFC. The modifications to the MFSC/J70 model required for the MET model are described, graphical and numerical examples of the models are included, as is a listing of the MET model computer program. Major differences between the numerical output from the MET model and the MFSC/J70 model are discussed.

Hickey, Michael Philip

1988-01-01

80

Thermodynamic modeling of pseudoternary phase behavior  

SciTech Connect

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.

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

1982-12-01

81

Thermodynamic modeling of pseudoternary phase behavior  

SciTech Connect

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.

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

1982-12-01

82

Spontaneous and genetically engineered animal models  

Microsoft Academic Search

The preclinical development of anticancer drugs has been based primarily on the transplantation of murine or human cancers into mice. Alternatives to these transplantation models are animals that naturally develop cancers with features relevant to the human disease. The first group of these models arises in mice that are genetically engineered to develop cancer. The second group includes pet dogs

K Hansen; C Khanna

2004-01-01

83

Network Engineering for Agile Belief Network Models  

Microsoft Academic Search

The construction of a large, complex belief network model, like any major system development effort, requires a structured process to manage system design and development. This paper describes a belief network engineering process based on the spiral system lifecycle model. The problem of specifying numerical probability distributions for random variables in a belief network is best treated not in isolation,

Kathryn Blackmond Laskey; Suzanne M. Mahoney

2000-01-01

84

Reliability modeling of an engineered barrier system.  

National Technical Information Service (NTIS)

The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered...

M. M. A. Ananda A. K. Singh J. A. Flueck

1993-01-01

85

Model-Driven Engineering of Service Orchestrations  

Microsoft Academic Search

This paper presents a methodology for the Model Driven Engineering of complex, multi-actor business processes, mixing tasks executed by humans and by machines. The idea is to enrich business description languages with a few extra details on task assignment, semantics, and typed dataflows, so as to enable a two-step generative approach: first the Process Model is automatically transformed into an

Marco Brambilla; Matteo Dosmi; Piero Fraternali

2009-01-01

86

The role of technology and engineering models in transforming healthcare.  

PubMed

The healthcare system is in crisis due to challenges including escalating costs, the inconsistent provision of care, an aging population, and high burden of chronic disease related to health behaviors. Mitigating this crisis will require a major transformation of healthcare to be proactive, preventive, patient-centered, and evidence-based with a focus on improving quality-of-life. Information technology, networking, and biomedical engineering are likely to be essential in making this transformation possible with the help of advances, such as sensor technology, mobile computing, machine learning, etc. This paper has three themes: 1) motivation for a transformation of healthcare; 2) description of how information technology and engineering can support this transformation with the help of computational models; and 3) a technical overview of several research areas that illustrate the need for mathematical modeling approaches, ranging from sparse sampling to behavioral phenotyping and early detection. A key tenet of this paper concerns complementing prior work on patient-specific modeling and simulation by modeling neuropsychological, behavioral, and social phenomena. The resulting models, in combination with frequent or continuous measurements, are likely to be key components of health interventions to enhance health and wellbeing and the provision of healthcare. PMID:23549108

Pavel, Misha; Jimison, Holly Brugge; Wactlar, Howard D; Hayes, Tamara L; Barkis, Will; Skapik, Julia; Kaye, Jeffrey

2013-01-01

87

Software Engineering Tools for Scientific Models  

NASA Technical Reports Server (NTRS)

Software tools were constructed to address issues the NASA Fortran development community faces, and they were tested on real models currently in use at NASA. These proof-of-concept tools address the High-End Computing Program and the Modeling, Analysis, and Prediction Program. Two examples are the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5) atmospheric model in Cell Fortran on the Cell Broadband Engine, and the Goddard Institute for Space Studies (GISS) coupled atmosphere- ocean model called ModelE, written in fixed format Fortran.

Abrams, Marc; Saboo, Pallabi; Sonsini, Mike

2013-01-01

88

Models of vehicular traffic: An engineering perspective  

NASA Astrophysics Data System (ADS)

The aim of the paper is to present an engineer's viewpoint of traffic streams and their models both at the macroscopic and microscopic levels. The paper concentrates on two classes of macroscopic models (namely, stream description models and travel time estimation models). At the microscopic level the paper concentrates on car-following models and also presents a relatively recent idea on developing a comprehensive microscopic model of driver behaviour. Finally, the paper presents some properties which all microscopic models of traffic flow should possess and also tries to identify areas where research will bring about a qualitative jump in the understanding of how traffic flows.

Chakroborty, Partha

2006-12-01

89

Modeling student success in engineering education  

NASA Astrophysics Data System (ADS)

In order for the United States to maintain its global competitiveness, the long-term success of our engineering students in specific courses, programs, and colleges is now, more than ever, an extremely high priority. Numerous studies have focused on factors that impact student success, namely academic performance, retention, and/or graduation. However, there are only a limited number of works that have systematically developed models to investigate important factors and to predict student success in engineering. Therefore, this research presents three separate but highly connected investigations to address this gap. The first investigation involves explaining and predicting engineering students' success in Calculus I courses using statistical models. The participants were more than 4000 first-year engineering students (cohort years 2004 - 2008) who enrolled in Calculus I courses during the first semester in a large Midwestern university. Predictions from statistical models were proposed to be used to place engineering students into calculus courses. The success rates were improved by 12% in Calculus IA using predictions from models developed over traditional placement method. The results showed that these statistical models provided a more accurate calculus placement method than traditional placement methods and help improve success rates in those courses. In the second investigation, multi-outcome and single-outcome neural network models were designed to understand and to predict first-year retention and first-year GPA of engineering students. The participants were more than 3000 first year engineering students (cohort years 2004 - 2005) enrolled in a large Midwestern university. The independent variables include both high school academic performance factors and affective factors measured prior to entry. The prediction performances of the multi-outcome and single-outcome models were comparable. The ability to predict cumulative GPA at the end of an engineering student's first year of college was about a half of a grade point for both models. The predictors of retention and cumulative GPA while being similar differ in that high school academic metrics play a more important role in predicting cumulative GPA with the affective measures playing a more important role in predicting retention. In the last investigation, multi-outcome neural network models were used to understand and to predict engineering students' retention, GPA, and graduation from entry to departure. The participants were more than 4000 engineering students (cohort years 2004 - 2006) enrolled in a large Midwestern university. Different patterns of important predictors were identified for GPA, retention, and graduation. Overall, this research explores the feasibility of using modeling to enhance a student's educational experience in engineering. Student success modeling was used to identify the most important cognitive and affective predictors for a student's first calculus course retention, GPA, and graduation. The results suggest that the statistical modeling methods have great potential to assist decision making and help ensure student success in engineering education.

Jin, Qu

90

Thermal barrier coating life modeling in aircraft gas turbine engines  

NASA Technical Reports Server (NTRS)

Analytical models for predicting ceramic thermal barrier coating (TBC) spalling life in aircraft gas turbine engines are presented. Electron beam-physical vapor deposited (EB-PVD) and plasma sprayed TBC systems are discussed. An overview of the following TBC spalling mechanisms is presented: metal oxidation at the ceramic-metal interface, ceramic-metal interface stress singularities at edges and corners, ceramic-metal interface stresses caused by radius of curvature and interface roughness, material properties and mechanical behavior, temperature gradients, component design features and object impact damage. TBC spalling life analytical models are proposed based on observations of TBC spalling and plausible failure theories. TBC spalling was assumed to occur when the imposed stresses exceed the material strength (at or near the ceramic-metal interface). TBC failure knowledge gaps caused by lack of experimental evidence and analytical understanding are noted. The analytical models are considered initial engineering approaches that capture observed TBC failure trends.

Nissley, David M.

1995-01-01

91

AC 2007-889: ACCIDENTAL COMPETENCY FORMATION: AN INVESTIGATION OF BEHAVIORAL LEARNING IN ENGINEERING EDUCATION  

Microsoft Academic Search

Abstract This paper examines the fundamental,assumptions underlying the concept of outcomes-based education in engineering. Tensions between these assumptions that derive from theorigins of the theory in the field of behavioral psychology and current practices of curriculumdesign in engineering are discussed. These tensions are potentially impeding factorsin the successful implementation,of the concept of educational outcomes,in engineering education. Behavioral learning and its

Joachim Walther; David Radcliffe

2007-01-01

92

Statistical and engineering methods for model enhancement  

NASA Astrophysics Data System (ADS)

Models which describe the performance of physical process are essential for quality prediction, experimental planning, process control and optimization. Engineering models developed based on the underlying physics/mechanics of the process such as analytic models or finite element models are widely used to capture the deterministic trend of the process. However, there usually exists stochastic randomness in the system which may introduce the discrepancy between physics-based model predictions and observations in reality. Alternatively, statistical models can be used to develop models to obtain predictions purely based on the data generated from the process. However, such models tend to perform poorly when predictions are made away from the observed data points. This dissertation contributes to model enhancement research by integrating physics-based model and statistical model to mitigate the individual drawbacks and provide models with better accuracy by combining the strengths of both models. The proposed model enhancement methodologies including the following two streams: (1) data-driven enhancement approach and (2) engineering-driven enhancement approach. Through these efforts, more adequate models are obtained, which leads to better performance in system forecasting, process monitoring and decision optimization. Among different data-driven enhancement approaches, Gaussian Process (GP) model provides a powerful methodology for calibrating a physical model in the presence of model uncertainties. However, if the data contain systematic experimental errors, the GP model can lead to an unnecessarily complex adjustment of the physical model. In Chapter 2, we proposed a novel enhancement procedure, named as “Minimal Adjustment”, which brings the physical model closer to the data by making minimal changes to it. This is achieved by approximating the GP model by a linear regression model and then applying a simultaneous variable selection of the model and experimental bias terms. Two real examples and simulations are presented to demonstrate the advantages of the proposed approach. Different from enhancing the model based on data-driven perspective, an alternative approach is to focus on adjusting the model by incorporating the additional domain or engineering knowledge when available. This often leads to models that are very simple and easy to interpret. The concepts of engineering-driven enhancement are carried out through two applications to demonstrate the proposed methodologies. In the first application where polymer composite quality is focused, nanoparticle dispersion has been identified as a crucial factor affecting the mechanical properties. Transmission Electron Microscopy (TEM) images are commonly used to represent nanoparticle dispersion without further quantifications on its characteristics. In Chapter 3, we developed the engineering-driven nonhomogeneous Poisson random field modeling strategy to characterize nanoparticle dispersion status of nanocomposite polymer, which quantitatively represents the nanomaterial quality presented through image data. The model parameters are estimated through the Bayesian MCMC technique to overcome the challenge of limited amount of accessible data due to the time consuming sampling schemes. The second application is to calibrate the engineering-driven force models of laser-assisted micro milling (LAMM) process statistically, which facilitates a systematic understanding and optimization of targeted processes. In Chapter 4, the force prediction interval has been derived by incorporating the variability in the runout parameters as well as the variability in the measured cutting forces. The experimental results indicate that the model predicts the cutting force profile with good accuracy using a 95% confidence interval. To conclude, this dissertation is the research drawing attention to model enhancement, which has considerable impacts on modeling, design, and optimization of various processes and systems. The fundamental methodologies of model enhancement are developed and furth

Chang, Chia-Jung

93

A circumplex model for maternal behavior  

Microsoft Academic Search

The purpose  is to demonstrate the generality of a social interaction conceptualization of maternal behavior by ordering the intercorrelation matrices of three sets of data on maternal behavior. When ordered both with factor analysis and with Guttman's circumplex model, similar two-dimensional organizations of maternal behavior concepts were found for the three sets of data.\\

Earl S. Schaefer

1959-01-01

94

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

NASA Technical Reports Server (NTRS)

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.

Gupta, U. K.; Ali, M.

1988-01-01

95

76 FR 33660 - Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines  

Federal Register 2010, 2011, 2012, 2013

...Directives; Austro Engine GmbH Model E4 Diesel Piston Engines AGENCY: Federal Aviation...contact Austro Engine GmbH, Rudolf-Diesel-Strasse 11, A-2700 Weiner Neustadt...2010), for Austro Engine GmbH model E4 diesel [[Page 33661

2011-06-09

96

76 FR 54373 - Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines  

Federal Register 2010, 2011, 2012, 2013

...Directives; Austro Engine GmbH Model E4 Diesel Piston Engines AGENCY: Federal Aviation...contact Austro Engine GmbH, Rudolf-Diesel-Strasse 11, A-2700 Weiner Neustadt...this AD will affect about 32 model E4 diesel piston engines, installed on...

2011-09-01

97

Implicit test generation for behavioral VHDL models  

Microsoft Academic Search

This paper proposes a behavioral-level test patterngeneration algorithm for behavioral VHDL descriptions.The proposed approach is based on the comparison betweenthe implicit description of the fault-free behaviorand the faulty behavior, obtained through a new behavioralfault model. The paper will experimentally showthat the test patterns generated at the behavioral levelprovide a very high stuck-at fault coverage when appliedto different gate-level implementations of

Fabrizio Ferrandi; Franco Fummi; Donatella Sciuto

1998-01-01

98

Modeling and Dynamic Simulation of IC Engine Driven Permanent Magnet Generator Using Matlab\\/Simulink for Hybrid Tracked Vehicle  

Microsoft Academic Search

A simple dynamic model is needed to study the dynamic behavior of IC engine driven permanent magnet generator, which is used in hybrid tracked vehicle. The simple mathematical model for the typical engine is developed using look-up table obtained from actual test bed results and physical equations. Permanent magnet generator model is developed by dq equivalent circuit model approach for

U. Shanmuganathan; R. Govarthanan; A. Muthumailvaganan; A. Imayakumar

2006-01-01

99

SSME model, engine dynamic characteristics related to Pogo  

NASA Technical Reports Server (NTRS)

A linear model of the space shuttle main engine for use in Pogo studies was presented. A digital program is included from which engine transfer functions are determined relative to the engine operating level.

1973-01-01

100

Reverse engineering the structural and acoustic behavior of a stradivari violin  

NASA Astrophysics Data System (ADS)

There is a tremendous amount of mystery that surrounds the instruments of Antonio Stradivari. There have been many studies done in the past, but no one completely understands exactly how he made his instruments, or why they are still considered the best in the world. This project is designed to develop an engineering model of one of Stradivari's violins that will accurately simulate the structural and acoustic behavior of the instrument. It also hopes to shine some light on what makes the instruments of Stradivari unique when compared to other violins. It will focus on geometry and material properties, utilizing several modern engineering tools, including CT scanning, experimental modal analysis, finite element analysis, correlation techniques, and acoustic synthesis.

Pyrkosz, Michael

101

Microfluidic cell culture models for tissue engineering.  

PubMed

Microfluidic systems have emerged as revolutionary new platform technologies for a range of applications, from consumer products such as inkjet printer cartridges to lab-on-a-chip diagnostic systems. Recent developments have opened the door to a new set of opportunities for microfluidic systems, in the field of tissue and organ engineering. Advances in the design of physiologically relevant structures and networks, fabrication processes for biomaterials suitable for in vivo use, and techniques for scaling towards large, three-dimensional constructs, are converging towards therapeutic applications of microfluidic technologies in engineering complex tissues and organs. These advances herald a new generation of microfluidics-based approaches designed for specific tissue and organ applications, incorporating microvascular networks, structures for transport and filtration, and a three-dimensional microenvironment suitable for supporting phenotypic cell behavior, tissue function, and implantation and host integration. PMID:21723720

Inamdar, Niraj K; Borenstein, Jeffrey T

2011-10-01

102

Sharing Research Models: Using Software Engineering Practices for Facilitation.  

PubMed

Increasingly, researchers are turning to computational models to understand the interplay of important variables on systems' behaviors. Although researchers may develop models that meet the needs of their investigation, application limitations-such as nonintuitive user interface features and data input specifications-may limit the sharing of these tools with other research groups. By removing these barriers, other research groups that perform related work can leverage these work products to expedite their own investigations. The use of software engineering practices can enable managed application production and shared research artifacts among multiple research groups by promoting consistent models, reducing redundant effort, encouraging rigorous peer review, and facilitating research collaborations that are supported by a common toolset. This report discusses three established software engineering practices- the iterative software development process, object-oriented methodology, and Unified Modeling Language-and the applicability of these practices to computational model development. Our efforts to modify the MIDAS TranStat application to make it more user-friendly are presented as an example of how computational models that are based on research and developed using software engineering practices can benefit a broader audience of researchers. PMID:21687780

Bryant, Stephanie P; Solano, Eric; Cantor, Susanna; Cooley, Philip C; Wagener, Diane K

2011-03-01

103

Sharing Research Models: Using Software Engineering Practices for Facilitation  

PubMed Central

Increasingly, researchers are turning to computational models to understand the interplay of important variables on systems’ behaviors. Although researchers may develop models that meet the needs of their investigation, application limitations—such as nonintuitive user interface features and data input specifications—may limit the sharing of these tools with other research groups. By removing these barriers, other research groups that perform related work can leverage these work products to expedite their own investigations. The use of software engineering practices can enable managed application production and shared research artifacts among multiple research groups by promoting consistent models, reducing redundant effort, encouraging rigorous peer review, and facilitating research collaborations that are supported by a common toolset. This report discusses three established software engineering practices— the iterative software development process, object-oriented methodology, and Unified Modeling Language—and the applicability of these practices to computational model development. Our efforts to modify the MIDAS TranStat application to make it more user-friendly are presented as an example of how computational models that are based on research and developed using software engineering practices can benefit a broader audience of researchers.

Bryant, Stephanie P.; Solano, Eric; Cantor, Susanna; Cooley, Philip C.; Wagener, Diane K.

2011-01-01

104

Qualitative models for space system engineering  

NASA Technical Reports Server (NTRS)

The objectives of this project were: (1) to investigate the implications of qualitative modeling techniques for problems arising in the monitoring, diagnosis, and design of Space Station subsystems and procedures; (2) to identify the issues involved in using qualitative models to enhance and automate engineering functions. These issues include representing operational criteria, fault models, alternate ontologies, and modeling continuous signals at a functional level of description; and (3) to develop a prototype collection of qualitative models for fluid and thermal systems commonly found in Space Station subsystems. Potential applications of qualitative modeling to space-systems engineering, including the notion of intelligent computer-aided engineering are summarized. Emphasis is given to determining which systems of the proposed Space Station provide the most leverage for study, given the current state of the art. Progress on using qualitative models, including development of the molecular collection ontology for reasoning about fluids, the interaction of qualitative and quantitative knowledge in analyzing thermodynamic cycles, and an experiment on building a natural language interface to qualitative reasoning is reported. Finally, some recommendations are made for future research.

Forbus, Kenneth D.

1990-01-01

105

Modeling Driver Behavior in a Cognitive Architecture  

Microsoft Academic Search

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

Dario D. Salvucci

2006-01-01

106

Modelling Retail Customer Behavior at Merrill Lynch  

Microsoft Academic Search

A two state Markov chain model is used to describe and forecast the over time behavior of the best retail customers at Merrill Lynch. This model has 4 behaviorally meaningful parameters which capture the effect of recently being a prime customer, the differing average commissions generated across customers and the exiting of some of these customers from the Merrill Lynch

Donald G. Morrison; Richard D. H. Chen; Sandra L. Karpis; Kathryn E. A. Britney

1982-01-01

107

An Interactionist Model of Creative Behavior.  

ERIC Educational Resources Information Center

An interactionist model of creative behavior is proposed, combining elements of the personality, cognitive, and social psychology perspectives on creativity. The model considers the interplay of factors including antecedent conditions, creative behavior, consequences, the individual, cognitive style/ability, personality traits, contextual…

Woodman, Richard W.; Schoenfeldt, Lyle F.

1990-01-01

108

Modeling of individualities in driving through spectral analysis of behavioral signals  

Microsoft Academic Search

Driving behavior modeling using such driving signals as veloc- ity, following distance, and gas or brake pedal operations, has been investigated for accident prevention and vehicle design. Driving behaviors are different among drivers, and research on driver modeling has also been carried out from different points of view in cognitive and engineering approaches. In this paper, driver's characteristics in driving

Koji Ozawa; Toshihiro Wakita; Chiyomi Miyajima; Katsunobu Itou; Kazuya Takeda

2005-01-01

109

ESDDM: A Software Evolution Process Model Based on Evolution Behavior Interface  

NASA Astrophysics Data System (ADS)

According to "Software processes are software too" proposed by L.Osterweil, we assume a software process model with independent functions as a component. To fully describe the evolution behavior of process-based components, the concept of evolution behavior interface is introduced and a Petri net based ESDDM model is discussed. By applying on a realistic case, we conclude that ESDDM, a software evolution process model based on evolution behavior interface, is able to effectively support the concurrent engineering.

Zhao, Na; Wang, Jian; Li, Tong; Yu, Yong; Dai, Fei; Xie, Zhongwen

110

Space shuttle main engine plume radiation model  

NASA Technical Reports Server (NTRS)

The methods are described which are used in predicting the thermal radiation received by space shuttles, from the plumes of the main engines. Radiation to representative surface locations were predicted using the NASA gaseous plume radiation GASRAD program. The plume model is used with the radiative view factor (RAVFAC) program to predict sea level radiation at specified body points. The GASRAD program is described along with the predictions. The RAVFAC model is also discussed.

Reardon, J. E.; Lee, Y. C.

1978-01-01

111

Reliability modeling of an engineered barrier system  

SciTech Connect

The Weibull distribution is widely used in reliability literature as a distribution of time to failure, as it allows for both increasing failure rate (IFR) and decreasing failure rate (DFR) models. It has also been used to develop models for an engineered barrier system (EBS), which is known to be one of the key components in a deep geological repository for high level radioactive waste (HLW). The EBS failure time can more realistically be modelled by an IFR distribution, since the failure rate for the EBS is not expected to decrease with time. In this paper, an IFR distribution is used to develop a reliability model for the EBS.

Ananda, M.M.A.; Singh, A.K.; Flueck, J.A.

1993-04-01

112

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

NASA Technical Reports Server (NTRS)

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.

Binder, Michael

1993-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

114

Tools and Behavioral Abstraction: A Direction for Software Engineering  

NASA Astrophysics Data System (ADS)

As in other engineering professions, software engineers rely on tools. Such tools can analyze program texts and design specifications more automatically and in more detail than ever before. While many tools today are applied to find new defects in old code, I predict that more software-engineering tools of the future will be available to software authors at the time of authoring. If such analysis tools can be made to be fast enough and easy enough to use, they can help software engineers better produce and evolve programs.

Leino, K. Rustan M.

115

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

Microsoft Academic Search

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

Feng An; Frank Stodolsky

1995-01-01

116

Applying the Health Belief Model to college students' health behavior  

PubMed Central

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.

Kim, Hak-Seon; Ahn, Joo

2012-01-01

117

Surrogate Model Development for Fuels for Advanced Combustion Engines  

SciTech Connect

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the target fuel. The present study proposes surrogate models for the nine fuels for advanced combustion engines (FACE) that have been developed for studying low-emission, high-efficiency advanced diesel engine concepts. The surrogate compositions for the fuels are arrived at by simulating their distillation profiles to within a maximum absolute error of 4% using a discrete multi-component (DMC) fuel model that has been incorporated in the multi-dimensional computational fluid dynamics (CFD) code, KIVA-ERC-CHEMKIN. The simulated surrogate compositions cover the range and measured concentrations of the various hydrocarbon classes present in the fuels. The fidelity of the surrogate fuel models is judged on the basis of matching their specific gravity, lower heating value, hydrogen/carbon (H/C) ratio, cetane number, and cetane index with the measured data for all nine FACE fuels.

Anand, Krishnasamy [University of Wisconsin, Madison; Ra, youngchul [University of Wisconsin, Madison; Reitz, Rolf [University of Wisconsin; Bunting, Bruce G [ORNL

2011-01-01

118

Software-Engineering Process Simulation (SEPS) model  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

119

Testing Expectancy Theory Predictions Using Behaviorally Based Measures of Motivational Effort for Engineers  

ERIC Educational Resources Information Center

Expectancy theory predictions were tested using a sample of engineers who had been rated on dimensions of work motivation or effort (in contrast to performance) using the behaviorally based rating scales designed by Landy and Guion (1970). (Author)

Arvey, Richard D.; Neel, C. Warren

1974-01-01

120

Animal Models for Bone Tissue Engineering Purposes  

Microsoft Academic Search

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

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

121

A search engine for 3D models  

Microsoft Academic Search

As the number of 3D models available on the Web grows, there is an increasing need for a search engine to help people find them. Unfortunately, traditional text-based search techniques are not always effective for 3D data. In this article, we investigate new shape-based search methods. The key challenges are to develop query methods simple enough for novice users and

Thomas A. Funkhouser; Patrick Min; Michael M. Kazhdan; Joyce Chen; Alex Halderman; David P. Dobkin; David Pokrass Jacobs

2003-01-01

122

A Search Engine for 3D Models  

Microsoft Academic Search

As the number of 3D models available on the Web grows, there is an increasing need for a search engine to help people find them. Unfortunately, traditional text-based search techniques are not always effective for 3D data. In this paper, we investigate new shape-based search methods. The key challenges are to develop query methods simple enough for novice users and

Thomas Funkhouser; Patrick Min; Misha Kazhdan; Joyce Chen; Alex Halderman; David Dobkin; David Jacobs

2002-01-01

123

Damage Propagation Modeling for Aircraft Engine Prognostics  

NASA Technical Reports Server (NTRS)

This paper describes how damage propagation can be modeled within the modules of aircraft gas turbine engines. To that end, response surfaces of all sensors are generated via a thermo-dynamical simulation model for the engine as a function of variations of flow and efficiency of the modules of interest. An exponential rate of change for flow and efficiency loss was imposed for each data set, starting at a randomly chosen initial deterioration set point. The rate of change of the flow and efficiency denotes an otherwise unspecified fault with increasingly worsening effect. The rates of change of the faults were constrained to an upper threshold but were otherwise chosen randomly. Damage propagation was allowed to continue until a failure criterion was reached. A health index was defined as the minimum of several superimposed operational margins at any given time instant and the failure criterion is reached when health index reaches zero. Output of the model was the time series (cycles) of sensed measurements typically available from aircraft gas turbine engines. The data generated were used as challenge data for the Prognostics and Health Management (PHM) data competition at PHM 08.

Saxena, Abhinav; Goebel, Kai; Simon, Don; Eklund, Neil

2008-01-01

124

A Behavioral Model of Rational Choice  

Microsoft Academic Search

This article by Herbert Simon provided one of the leading alternatives to the traditional model of rational profit-maximizing behavior, bringing to the forefront of academic attention several of the key issues on which behavioral economics would eventually focus. Introduction by Lindsay McSweeney, Competition Policy International.

Herbert A. Simon; Lindsay McSweeney

2010-01-01

125

Modeling Off-Nominal Behavior in SysML  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

126

Beam-Riding Behavior of Lightcraft Engines with ? 1 ?s Pulsed TEA CO2 Laser  

Microsoft Academic Search

The beam-riding and angular impulse performance of four laser propulsion engine geometries were measured using a twin Lumonics K922M pulsed TEA CO2 laser system, with an Angular Impulse Measurement Device (AIMD). Airbreathing and solid ablative rocket (SAR) mode impulse data was collected to explore engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the engine axis

D. A. Kenoyer; I. I. Salvador; L. N. Myrabo

2011-01-01

127

SEISMIC MODELING ENGINES PHASE 1 FINAL REPORT  

SciTech Connect

Seismic modeling is a core component of petroleum exploration and production today. Potential applications include modeling the influence of dip on anisotropic migration; source/receiver placement in deviated-well three-dimensional surveys for vertical seismic profiling (VSP); and the generation of realistic data sets for testing contractor-supplied migration algorithms or for interpreting AVO (amplitude variation with offset) responses. This project was designed to extend the use of a finite-difference modeling package, developed at Lawrence Berkeley Laboratories, to the advanced applications needed by industry. The approach included a realistic, easy-to-use 2-D modeling package for the desktop of the practicing geophysicist. The feasibility of providing a wide-ranging set of seismic modeling engines was fully demonstrated in Phase I. The technical focus was on adding variable gridding in both the horizontal and vertical directions, incorporating attenuation, improving absorbing boundary conditions and adding the optional coefficient finite difference methods.

BRUCE P. MARION

2006-02-09

128

Protein engineering and the use of molecular modeling and simulation: the case of heterodimeric Fc engineering.  

PubMed

Computational and structure guided methods can make significant contributions to the development of solutions for difficult protein engineering problems, including the optimization of next generation of engineered antibodies. In this paper, we describe a contemporary industrial antibody engineering program, based on hypothesis-driven in silico protein optimization method. The foundational concepts and methods of computational protein engineering are discussed, and an example of a computational modeling and structure-guided protein engineering workflow is provided for the design of best-in-class heterodimeric Fc with high purity and favorable biophysical properties. We present the engineering rationale as well as structural and functional characterization data on these engineered designs. PMID:24211748

Spreter Von Kreudenstein, Thomas; Lario, Paula I; Dixit, Surjit B

2014-01-01

129

The future of computational modelling in reaction engineering.  

PubMed

In this paper, we outline the future of modelling in reaction engineering. Specifically, we use the example of particulate emission formation in internal combustion engines to demonstrate what modelling can achieve at present, and to illustrate the ultimately inevitable steps that need to be taken in order to create a new generation of engineering models. PMID:20603373

Kraft, Markus; Mosbach, Sebastian

2010-08-13

130

Modeling Human Behavior at a Large Scale.  

National Technical Information Service (NTIS)

Until recently, complex phenomena such as human behavior and disease epidemics have been modeled primarily at an aggregate level. Detailed studies have been limited to small domains encompassing only a few subjects, as scaling the methods involved poses c...

A. Sadilek

2012-01-01

131

A simplified dynamic model of the T700 turboshaft engine  

NASA Technical Reports Server (NTRS)

A simplified open-loop dynamic model of the T700 turboshaft engine, valid within the normal operating range of the engine, is developed. This model is obtained by linking linear state space models obtained at different engine operating points. Each linear model is developed from a detailed nonlinear engine simulation using a multivariable system identification and realization method. The simplified model may be used with a model-based real time diagnostic scheme for fault detection and diagnostics, as well as for open loop engine dynamics studies and closed loop control analysis utilizing a user generated control law.

Duyar, Ahmet; Gu, Zhen; Litt, Jonathan S.

1992-01-01

132

A maintenance model for clinical engineering.  

PubMed

The numbers presented here for an equipment maintenance model are derived from a mix of soft data and intuition based on experience. They relate best to university hospitals in the 250-400-bed range. They relate better to numbers of devices than number of beds. In summary, they are: 1. Ideal technician workload = 400 to 550 devices. 2. Average technician productivity or ;;hands-on'' maintenance time = 75%. 3. Average dollar value per device = $2,000. 4. Annual in-house maintenance ratio = 5% to 7% of value plus parts in excess of $200/item. 5. Effective rate per hour = $35 to $45/hr (depending upon region and labor costs in that region). 6. In-house maintenance costs should be less than outside costs. However, the in-house department should be aware of cost-effective outside options and employ them as appropriate. 7. Appropriate resources. 250 sq ft/technician, $20,000 capital equipment/technician, and $15 to $25/device in supplies. 8. Clinical engineers. One engineer to start the service and one engineer for each three additional technicians added. 9. Clerical support. One clerical FTE for a minimum 3 technician department, and one additional clerical FTE for each additional 1.5 FTE clinical engineers or each additional 5 FTE technicians. 10. Annual maintenance = 2.5 hr/device. (When clinical devices are distinguished from nonclinical devices, averages are 3 hr/clinical device and 2 hr/nonclinical device.) As clinical engineers, BMETs, and their departments gather experience to support or modify these numbers, I encourage them to share their findings in an experience pool available to all. PMID:19493765

Johnston, G I

1985-01-01

133

Hierarchical test generation for VHDL behavioral models  

Microsoft Academic Search

In this method, the VHDL model to be tested is represented by its process model graph (PMG). Test sets for individual processes of the model are precomputed and stored in the design library. The Hierarchical Behavioral Test Generator (HBTG) algorithm accepts the PMG and the precomputed tests as inputs, from which it hierarchically constructs a test sequence that tests the

Sanat R. Rao; Bi-Yu Pan; James R. Armstrong

1993-01-01

134

Energy Efficient Engine Exhaust Mixer Model Technology  

NASA Technical Reports Server (NTRS)

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.

Kozlowski, H.; Larkin, M.

1981-01-01

135

Approximate simulation model for analysis and optimization in engineering system design  

NASA Technical Reports Server (NTRS)

Computational support of the engineering design process routinely requires mathematical models of behavior to inform designers of the system response to external stimuli. However, designers also need to know the effect of the changes in design variable values on the system behavior. For large engineering systems, the conventional way of evaluating these effects by repetitive simulation of behavior for perturbed variables is impractical because of excessive cost and inadequate accuracy. An alternative is described based on recently developed system sensitivity analysis that is combined with extrapolation to form a model of design. This design model is complementary to the model of behavior and capable of direct simulation of the effects of design variable changes.

Sobieszczanski-Sobieski, Jaroslaw

1989-01-01

136

A Behavior Change Model for Internet Interventions  

PubMed Central

Background The Internet has become a major component to health care and has important implications for the future of the health care system. One of the most notable aspects of the Web is its ability to provide efficient, interactive, and tailored content to the user. Given the wide reach and extensive capabilities of the Internet, researchers in behavioral medicine have been using it to develop and deliver interactive and comprehensive treatment programs with the ultimate goal of impacting patient behavior and reducing unwanted symptoms. To date, however, many of these interventions have not been grounded in theory or developed from behavior change models, and no overarching model to explain behavior change in Internet interventions has yet been published. Purpose The purpose of this article is to propose a model to help guide future Internet intervention development and predict and explain behavior changes and symptom improvement produced by Internet interventions. Results The model purports that effective Internet interventions produce (and maintain) behavior change and symptom improvement via nine nonlinear steps: the user, influenced by environmental factors, affects website use and adherence, which is influenced by support and website characteristics. Website use leads to behavior change and symptom improvement through various mechanisms of change. The improvements are sustained via treatment maintenance. Conclusion By grounding Internet intervention research within a scientific framework, developers can plan feasible, informed, and testable Internet interventions, and this form of treatment will become more firmly established.

Thorndike, Frances P.; Cox, Daniel J.; Kovatchev, Boris P.; Gonder-Frederick, Linda A.

2010-01-01

137

Enhanced Core Noise Modeling for Turbofan Engines  

NASA Technical Reports Server (NTRS)

This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC) under Contract NAS3-00178, Task Order No. 15. MTCT previously developed a first-generation empirical model that correlates the core/combustion noise of four GE engines, the CF6, CF34, CFM56, and GE90 for General Electric (GE) under Contract No. 200-1X-14W53048, in support of GRC Contract NAS3-01135. MTCT has demonstrated in earlier noise modeling efforts that the improvement of predictive modeling is greatly enhanced by an iterative approach, so in support of NASA's Quiet Aircraft Technology Project, GRC sponsored this effort to improve the model. Since the noise data available for correlation are total engine noise spectra, it is total engine noise that must be predicted. Since the scope of this effort was not sufficient to explore fan and turbine noise, the most meaningful comparisons must be restricted to frequencies below the blade passage frequency. Below the blade passage frequency and at relatively high power settings jet noise is expected to be the dominant source, and comparisons are shown that demonstrate the accuracy of the jet noise model recently developed by MTCT for NASA under Contract NAS3-00178, Task Order No. 10. At lower power settings the core noise became most apparent, and these data corrected for the contribution of jet noise were then used to establish the characteristics of core noise. There is clearly more than one spectral range where core noise is evident, so the spectral approach developed by von Glahn and Krejsa in 1982 wherein four spectral regions overlap, was used in the GE effort. Further analysis indicates that the two higher frequency components, which are often somewhat masked by turbomachinery noise, can be treated as one component, and it is on that basis that the current model is formulated. The frequency scaling relationships are improved and are now based on combustor and core nozzle geometries. In conjunction with the Task Order No. 10 jet noise model, this core noise model is shown to provide statistical accuracy comparable to the jet noise model for frequencies below blade passage. This model is incorporated in the NASA FOOTPR code and a user s guide is provided.

Stone, James R.; Krejsa, Eugene A.; Clark, Bruce J.

2011-01-01

138

Parametric Model of an Aerospike Rocket Engine.  

National Technical Information Service (NTIS)

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 engi...

J. J. Korte

2000-01-01

139

Sponsored Search Engines in Competition: Advertisers Behavior and Engines Optimal Ranking Strategies  

Microsoft Academic Search

Search engines are essential actors for web browsing. We analyze here the economic competition between search engines earning money from adword auctions. We develop a two- level game where at the largest time scale search engines decide which allocation rule to implement, between revenue-based and bid-based; and at the lowest time-scale advertisers decide how to split their advertising budget between

Patrick Maille; Bruno Tuffin

2011-01-01

140

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

ERIC Educational Resources Information Center

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)

Leckie, Gloria J.; And Others

1996-01-01

141

Genetically Engineered Mouse Models in Cancer Research  

PubMed Central

Mouse models of human cancer have played a vital role in understanding tumorigenesis and answering experimental questions that other systems cannot address. Advances continue to be made that allow better understanding of the mechanisms of tumor development, and therefore the identification of better therapeutic and diagnostic strategies. We review major advances that have been made in modeling cancer in the mouse and specific areas of research that have been explored with mouse models. For example, although there are differences between mice and humans, new models are able to more accurately model sporadic human cancers by specifically controlling timing and location of mutations, even within single cells. As hypotheses are developed in human and cell culture systems, engineered mice provide the most tractable and accurate test of their validity in vivo. For example, largely through the use of these models, the microenvironment has been established to play a critical role in tumorigenesis, since tumor development and the interaction with surrounding stroma can be studied as both evolve. These mouse models have specifically fueled our understanding of cancer initiation, immune system roles, tumor angiogenesis, invasion, and metastasis, and the relevance of molecular diversity observed among human cancers. Currently, these models are being designed to facilitate in vivo imaging to track both primary and metastatic tumor development from much earlier stages than previously possible. Finally, the approaches developed in this field to achieve basic understanding are emerging as effective tools to guide much needed development of treatment strategies, diagnostic strategies, and patient stratification strategies in clinical research.

Walrath, Jessica C.; Hawes, Jessica J.; Van Dyke, Terry; Reilly, Karlyne M.

2012-01-01

142

Investigating the effects of behavior constructs on academic persistence in engineering, creativity and risk-taking  

NASA Astrophysics Data System (ADS)

Increasingly over the last decade, engineering colleges across this nation have conducted research to identify factors that will help them better predict students' academic persistence in engineering. While initial efforts were aimed at predicting those who would graduate, recent efforts have been directed toward predicting who will persist to the second year, as it has been found that a substantial percentage of those who leave engineering do so during their first year. Prior research investigated the predictability of academic persistence using academic credentials such as grade point averages and SAT scores. However, recent research on academic persistence in engineering has suggested differences in students' behavior and students' levels of dissonance-induced stress, rather than differences in academic credentials, may distinguish persisters from non-persisters. One aspect of an individual's behavior, compliance, and behavior-related stress, referred to as dissonance-induced stress, are proposed to have an effect on academic persistence. Research shows compliance (or conformity) is diametrically opposed to creativity, which is essential to leadership and innovation in engineering. A similar relationship is likely to exist between compliance and risk-taking. This research investigated whether behavior and dissonance-induced stress are good predictors of academic persistence in engineering. This research also investigated relationships between behavior, creativity, and risk-taking. Students who were enrolled in a first-year Fundamentals in Engineering course (ENGR 112) were the subjects in this research. The Style Analysis Instrument was used to collect data regarding students' behavioral orientations. The Style Analysis Instrument provides both natural and adapted measures in four dimensions of human behavior: dominance, influence, steadiness, and compliance. The Creativity and Risk-Taking Instrument was used to collect data regarding students' creativity and risk-taking tendencies. Results indicate compliance has a statistically significant effect on academic persistence in engineering among first-year engineering students. However, the hypothesis regarding the effect of behavioral dissonance-induced stress was not supported. Results regarding relationships between the behavior variables used in this research and creativity and risk-taking imply that risk-taking is more related to behavior variables than creativity.

Deanes, Viveca K.

143

Control Oriented Modeling of Combustion Phasing for an HCCI Engine  

Microsoft Academic Search

A promising method for reducing emissions and fuel consumption of internal combustion engines is the Homogeneous charge compression ignition (HCCI) engine. Control of ignition timing must be realized before the potential benefits of HCCI combustion can be implemented in production engines. A model suitable for real time implementation is developed and this model is able to predict ignition timing with

Mahdi Shahbakhti; Charles Robert Koch

2007-01-01

144

Microscopic models of hydrodynamic behavior  

Microsoft Academic Search

We review recent developments in the rigorous derivation of hydrodynamic-type macroscopic equations from simple microscopic models: continuous time stochastic cellular automata. The deterministic evolution of hydrodynamic variables emerges as the “law of large numbers,” which holds with probability one in the limit in which the ratio of the microscopic to the macroscopic spatial and temporal scales go to zero. We

Joel L. Lebowitz; Errico Presutti; Herbert Spohn

1988-01-01

145

Engineering Model of Future Motor Vehicles. Volume II. Data Book.  

National Technical Information Service (NTIS)

The Engineering Model of Future Motor Vehicles, previously reported in February 1977 in DOT-HS-802209 provided the safety engineer with a computerized data base including passenger car information such as configuration, geometric, weight, performance, and...

H. W. Grove

1978-01-01

146

Explaining clinical behaviors using multiple theoretical models  

PubMed Central

Background In the field of implementation research, there is an increased interest in use of theory when designing implementation research studies involving behavior change. In 2003, we initiated a series of five studies to establish a scientific rationale for interventions to translate research findings into clinical practice by exploring the performance of a number of different, commonly used, overlapping behavioral theories and models. We reflect on the strengths and weaknesses of the methods, the performance of the theories, and consider where these methods sit alongside the range of methods for studying healthcare professional behavior change. Methods These were five studies of the theory-based cognitions and clinical behaviors (taking dental radiographs, performing dental restorations, placing fissure sealants, managing upper respiratory tract infections without prescribing antibiotics, managing low back pain without ordering lumbar spine x-rays) of random samples of primary care dentists and physicians. Measures were derived for the explanatory theoretical constructs in the Theory of Planned Behavior (TPB), Social Cognitive Theory (SCT), and Illness Representations specified by the Common Sense Self Regulation Model (CSSRM). We constructed self-report measures of two constructs from Learning Theory (LT), a measure of Implementation Intentions (II), and the Precaution Adoption Process. We collected data on theory-based cognitions (explanatory measures) and two interim outcome measures (stated behavioral intention and simulated behavior) by postal questionnaire survey during the 12-month period to which objective measures of behavior (collected from routine administrative sources) were related. Planned analyses explored the predictive value of theories in explaining variance in intention, behavioral simulation and behavior. Results Response rates across the five surveys ranged from 21% to 48%; we achieved the target sample size for three of the five surveys. For the predictor variables, the mean construct scores were above the mid-point on the scale with median values across the five behaviors generally being above four out of seven and the range being from 1.53 to 6.01. Across all of the theories, the highest proportion of the variance explained was always for intention and the lowest was for behavior. The Knowledge-Attitudes-Behavior Model performed poorly across all behaviors and dependent variables; CSSRM also performed poorly. For TPB, SCT, II, and LT across the five behaviors, we predicted median R2 of 25% to 42.6% for intention, 6.2% to 16% for behavioral simulation, and 2.4% to 6.3% for behavior. Conclusions We operationalized multiple theories measuring across five behaviors. Continuing challenges that emerge from our work are: better specification of behaviors, better operationalization of theories; how best to appropriately extend the range of theories; further assessment of the value of theories in different settings and groups; exploring the implications of these methods for the management of chronic diseases; and moving to experimental designs to allow an understanding of behavior change.

2012-01-01

147

Modeling search engine effectiveness for federated search  

Microsoft Academic Search

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

Luo Si; Jamie Callan

2005-01-01

148

PARAMETRIC MODEL OF AN AEROSPIKE ROCKET ENGINE  

Microsoft Academic Search

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

J. J. Korte

2000-01-01

149

Hybrid rocket engine, theoretical model and experiment  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to build a theoretical model for the hybrid rocket engine/motor and to validate it using experimental results. The work approaches the main problems of the hybrid motor: the scalability, the stability/controllability of the operating parameters and the increasing of the solid fuel regression rate. At first, we focus on theoretical models for hybrid rocket motor and compare the results with already available experimental data from various research groups. A primary computation model is presented together with results from a numerical algorithm based on a computational model. We present theoretical predictions for several commercial hybrid rocket motors, having different scales and compare them with experimental measurements of those hybrid rocket motors. Next the paper focuses on tribrid rocket motor concept, which by supplementary liquid fuel injection can improve the thrust controllability. A complementary computation model is also presented to estimate regression rate increase of solid fuel doped with oxidizer. Finally, the stability of the hybrid rocket motor is investigated using Liapunov theory. Stability coefficients obtained are dependent on burning parameters while the stability and command matrixes are identified. The paper presents thoroughly the input data of the model, which ensures the reproducibility of the numerical results by independent researchers.

Chelaru, Teodor-Viorel; Mingireanu, Florin

2011-06-01

150

Stochastic combustion modeling of direct injection diesel engines  

Microsoft Academic Search

A comprehensive diesel engine combustion model has been developed. The model is an extension of similar thermodynamic multi-zone models for gasoline engines. In this model, the charge is divided into many distinct zones to express geometric information and to provide spatial resolution. Within each zone structure, mass, momentum and energy conservations are expressed as lumped formulations. This basic structure is

Xiao; Yun

1991-01-01

151

ZMOTTO- MODELING THE INTERNAL COMBUSTION ENGINE  

NASA Technical Reports Server (NTRS)

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.

Zeleznik, F. J.

1994-01-01

152

Computational modeling for eco engineering: Making the connections between engineering and ecology (Invited)  

NASA Astrophysics Data System (ADS)

Ecological engineering, or eco engineering, is an emerging field in the study of integrating ecology and engineering, concerned with the design, monitoring, and construction of ecosystems. According to Mitsch (1996) 'the design of sustainable ecosystems intends to integrate human society with its natural environment for the benefit of both'. Eco engineering emerged as a new idea in the early 1960s, and the concept has seen refinement since then. As a commonly practiced field of engineering it is relatively novel. Howard Odum (1963) and others first introduced it as 'utilizing natural energy sources as the predominant input to manipulate and control environmental systems'. Mtisch and Jorgensen (1989) were the first to define eco engineering, to provide eco engineering principles and conceptual eco engineering models. Later they refined the definition and increased the number of principles. They suggested that the goals of eco engineering are: a) the restoration of ecosystems that have been substantially disturbed by human activities such as environmental pollution or land disturbance, and b) the development of new sustainable ecosystems that have both human and ecological values. Here a more detailed overview of eco engineering is provided, particularly with regard to how engineers and ecologists are utilizing multi-dimensional computational models to link ecology and engineering, resulting in increasingly successful project implementation. Descriptions are provided pertaining to 1-, 2- and 3-dimensional hydrodynamic models and their use at small- and large-scale applications. A range of conceptual models that have been developed to aid the in the creation of linkages between ecology and engineering are discussed. Finally, several case studies that link ecology and engineering via computational modeling are provided. These studies include localized stream rehabilitation, spawning gravel enhancement on a large river system, and watershed-wide floodplain modeling of the Sacramento River Valley.

Bowles, C.

2013-12-01

153

Software Engineering Laboratory (SEL) cleanroom process model  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

154

Modeling Abstract Behavior: A Dynamic Logic Approach  

NASA Astrophysics Data System (ADS)

Modeling abstract behavior is essential for intelligent agents under incomplete and uncertain environments. In this paper, we extend Propositional Dynamic Logic (PDL) to Propositional Abstract Dynamic Logic (PADL) for modeling abstract behavior in two aspects. On the one hand, we treat the task of finding a plan to achieve a certain formula as an abstract action. On the other hand, we explicitly represent the subsumption relation between two actions as a formula in the language. We propose the semantics for the two operators and discuss some important related properties.

Zhou, Yi; Zhang, Yan

155

Adaptive human behavior in epidemiological models.  

PubMed

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

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

2011-04-12

156

Adaptive human behavior in epidemiological models  

PubMed Central

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.

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

157

Identifying clusters of user behavior in intranet search engine log files  

Microsoft Academic Search

When studying how ordinary Web users interact with Web search engines,researchers tend to either treat the users as a homogeneous group or group them accord- ing to search experience. Neither approach is sufficient, we argue,to capture the variety in behavior that is known to exist among searchers. By applying automatic cluster- ing technique based on self-organizing maps to search engine

Dick Stenmark

2008-01-01

158

Biomass Reburning: Modeling/Engineering Studies  

SciTech Connect

Reburning is a mature fuel staging NO{sub x} control technology which has been successfully demonstrated at full scale by Energy and Environmental Research Corporation (EER) and others on numerous occasions. Based on chemical kinetic modeling and experimental combustion studies, EER is currently developing novel concepts to improve the efficiency of the basic gas reburning process and to utilize various renewable and waste fuels for NO{sub x} control. 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. Basic and advanced biomass reburning have the potential to achieve 60-90+% NO{sub x} control in coal fired boilers at a significantly lower cost than SCR. The scope of work includes modeling studies (kinetic, CFD, and physical modeling), experimental evaluation of slagging and fouling associated with biomass reburning, and economic study of biomass handling requirements. Project participants include: EER, FETC R and D group, Niagara Mohawk Power Corporation and Antares, Inc. Most of the combustion experiments on development of biomass reburning technologies are being conducted in the scope of coordinated SBIR program funded by USDA. The first reporting period (October 1--December 31, 1997) included preparation of project management plan and organization of project kick-off meeting at DOE FETC. The quarterly report briefly describes the management plan and presents basic information about the kick-off meeting.

Vladimir M. Zamansky

1998-01-20

159

Hydrologic Behavior of Two Engineered Barriers Following Extreme Wetting  

SciTech Connect

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.

Porro, I.

2000-09-30

160

Compressor Modeling for Engine Control and Maintenance.  

National Technical Information Service (NTIS)

This work describes a method for dynamically updating the compressor map for an advanced turbofan engine. The implementation of the method is illustrated using data from a transport aircraft powered by four turbofan engines. The compressor map is generate...

C. Beckey M. Carpenter R. Hartfield

2011-01-01

161

Application of artificial neural networks in engine modelling  

Microsoft Academic Search

A study was conducted to develop an accurate simulation tool with a small computer resource footprint for engine design. The modelling approach uses artificial neural networks (ANNs) based on multilayer perceptrons (MLPs). The ANN is used to represent engine in-cylinder processes by training the ANN to approximate computational fluid dynamics (CFD) simulation results of the engine. The ANN approach was

Y He; C J Rutland

2004-01-01

162

Model-Based Engineering of Software: Three Productivity Perspectives  

Microsoft Academic Search

Evolving software products is a tricky business, especially when the domain is complex and changing rapidly. Like other fields of engineering, software engineering productivity advances have come about largely through abstraction, reuse, process, and automation (e.g., moving from assembly language to third generation languages offered increased productivity through better abstraction). For canonical or domain applications, model-based engineering (MBE) of software

Shawn A. Bohner; Sriram Mohan

2009-01-01

163

Environmental Modeling of Mars: Thermal Behavior  

NASA Astrophysics Data System (ADS)

There is increasing demand for modeling of the Martian physical environment both for scientific studies and for design and operation of Mars missions. A variety of resources are available to meet these needs; most are the products of individual research efforts, and one - Mars-GRAM - is a parameterization model specifically intended for engineering applications. There is often a gap of understanding between the scientists and engineers that must be carefully addressed in order to portray accuracy of data, reliability of models, and applicability. At JPL we are collecting the most relevant scientific results and providing them to engineering staff in order to carry out a variety of studies. Among these are estimation of minimum nighttime 1-m air temperatures at the Mars Exploration Rover landing sites, in order to predict thermal losses that could limit mission lifetime; evaluation of the thermal flux on MRO instruments and radiative coolers; bounding atmospheric dust opacities for balloon operations; and wind modeling for evaluation of landing risk at potential MER sites. For MER, we combined thermal models validated by MGS TES data with a 1-D boundary layer model developed for Mars Pathfinder meteorology data modeling, to produce temperatures at 1 meter at 0600 hrs near the mission endpoints, to estimate whether certain landing sites would produce excessive cooling, and thus battery drain. Low thermal inertias at the Sinus Meridiani site produce temperatures that are problematical for a small fraction of the original landing ellipse. Data have generously been provided by MGS TES and Odyssey THEMIS team members, as well as mesoscale and boundary layer modelers. This research was carried out by the Jet Propulsion Laboratory, California Institute of Technology.

Martin, T. Z.; Bridges, N. T.; Murphy, J. R.

2003-05-01

164

Constructing an Efficient Self-Tuning Aircraft Engine Model for Control and Health Management Applications.  

National Technical Information Service (NTIS)

Self-tuning aircraft engine models can be applied for control and health management applications. The self-tuning feature of these models minimizes the mismatch between any given engine and the underlying engineering model describing an engine family. Thi...

D. L. Simon J. B. Armstrong

2012-01-01

165

Modeling the flows of engineered nanomaterials during waste handling.  

PubMed

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

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

2013-01-01

166

Modeling the Dynamic Behavior of Hypermedia Applications  

Microsoft Academic Search

Hypermedia applications can be defined as collections of interactive and multimedia documents that are organized as a hypertext net. The development of hypermedia applications poses specific problems, such as the need for modeling sophisticated navigational structures, interactive behaviors, and harmonic presentations involving the synchronization of contents. Moreover, the increasing popularity of Internet based systems has put stress on the lack

Paloma Díaz; Ignacio Aedo; Fivos Panetsos

2001-01-01

167

Structural Equation Modeling in Behavioral Research  

Cancer.gov

April 27, 2012 10:00 AM - 11:00 AM + Add to Outlook Calendar Date and Time: Friday, April 27th, 10:00-11:00am, EPS/7107 Lecturer:  Natalia Frishman, MD PhD Candidate Iowa State University Print This Page Structural Equation Modeling in Behavioral Research News

168

Asymptotic behavior of a metapopulation model  

Microsoft Academic Search

We study the behavior of an infinite system of ordinary differential equations modeling the dynamics of a metapopulation, a set of (discrete) populations subject to local catastrophes and connected via migration under a mean field rule; the local population dynamics follow a generalized logistic law. We find a threshold below which all the solutions tend to total extinction of the

A. D. Barbour; A. Pugliese

2005-01-01

169

Systems Security Engineering Capability Maturity Model SSE-CMM Model Description Document.  

National Technical Information Service (NTIS)

The Systems Security Engineering Capability Maturity Model (SSE-CMM) describes the essential characteristics of an organization's security engineering process that must exist to ensure good security engineering. The SSE-CMM does not prescribe a particular...

1999-01-01

170

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

171

Neural Modeling and Control of Diesel Engine with Pollution Constraints  

Microsoft Academic Search

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

Mustapha Ouladsine; Gérard Bloch; Xavier Dovifaaz

2009-01-01

172

Combustion system CFD modeling at GE Aircraft Engines  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

173

Discrete time modelization of human pilot behavior  

NASA Technical Reports Server (NTRS)

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.

Cavalli, D.; Soulatges, D.

1975-01-01

174

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

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…

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

175

Combustion and emissions behavior for ethanol–gasoline blends in a single cylinder engine  

Microsoft Academic Search

This paper investigates the effect of using gasoline–ethanol mid-level blends (0–20% ethanol) on engine performance and exhausts emissions on a single cylinder engine by AVL model 5401, spark ignited and electronically controlled with DOHC. Engine tests were conducted for different lambda values, brake power and brake specific fuel consumption, while exhaust emissions were analyzed for carbon monoxide, unburned hydrocarbons and

I. Schifter; L. Diaz; R. Rodriguez; J. P. Gómez; U. Gonzalez

2011-01-01

176

Engineering of electrode structure for enhanced rate behavior  

NASA Astrophysics Data System (ADS)

Two primary concerns for electrochemical energy storage and conversion applications are the obtainable power and energy of the system. The advanced batteries currently being investigated for electric automobiles and consumer electronics have very good energy density but do not perform well under high power demands. The purpose of my work has been to engineer electrode structures such that high reaction rates, and therefore high powers, are possible without sacrificing the already high energy densities of the system. Amorphous vanadium pentoxide (V2O5) shows a high specific energy and a high capacity for Li intercalation. However, the rate of insertion is typically limited by lithium diffusion in the host and by its modest conductivity. This thesis demonstrates that high intercalation rates are possible if the host microstructure is modified to decrease the characteristic lithium diffusion distance and the characteristic conduction distance. Thin films of V2O5 aerogel were grown by preferential gelation on sintered nickel fibers via a sol-gel route. Electrochemical impedance measurements of the composite electrodes indicated that diffusion limitations in the host were successfully avoided. Impedance analysis in the redox capacity region revealed that the majority of the V2O5 aerogel was electrochemically accessible. Constant current cycling and cyclic voltammetry were also used to characterize the composites. Specific powers, based on mass of active material, of almost 6 MW/kg were observed.

Parent, Michael Joseph

177

Modeling of hybrid vehicle fuel economy and fuel engine efficiency  

NASA Astrophysics Data System (ADS)

"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.

Wu, Wei

178

Engineering Models Ease and Speed Prototyping  

NASA Technical Reports Server (NTRS)

NASA astronauts plan to return to the Moon as early as 2015 and establish a lunar base, from which 6-month flights to Mars would be launched by 2030. Essential to this plan is the Ares launch vehicle, NASA s next-generation spacecraft that will, in various iterations, be responsible for transporting all equipment and personnel to the Moon, Mars, and beyond for the foreseeable future. The Ares launch vehicle is powered by the J-2X propulsion system, with what will be the world s largest rocket nozzles. One of the conditions that engineers carefully consider in designing rocket nozzles particularly large ones is called separation phenomenon, which occurs when outside ambient air is sucked into the nozzle rim by the relatively low pressures of rapidly expanding exhaust gasses. This separation of exhaust gasses from the side-wall imparts large asymmetric transverse loads on the nozzle, deforming the shape and thus perturbing exhaust flow to cause even greater separation. The resulting interaction can potentially crack the nozzle or break actuator arms that control thrust direction. Side-wall loads are extremely difficult to measure directly, and, until now, techniques were not available for accurately predicting the magnitude and frequency of the loads. NASA researchers studied separation phenomenon in scale-model rocket nozzles, seeking to use measured vibration on these nozzle replicas to calculate the unknown force causing the vibrations. Key to this approach was the creation of a computer model accurately representing the nozzle as well as the test cell.

2008-01-01

179

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

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

180

Expectancy Theory Predictions and Behaviorally Anchored Scales of Motivation: An Empirical Test of Engineers  

ERIC Educational Resources Information Center

A behaviorally specific motivational effort rating scale was developed and tested. The organizational specific scale results were examined and compared to those generated from the Landy and Guion scale. It was found that the organizationally specific and engineer relevant scale is a better predictor of two types of expectancies. (Author)

Ivancevich, John M.

1976-01-01

181

A simplified dynamic model of the Space Shuttle main engine  

NASA Astrophysics Data System (ADS)

A simplified model is presented of the space shuttle main engine (SSME) dynamics valid within the range of operation of the engine. This model is obtained by linking the linearized point models obtained at 25 different operating points of SSME. The simplified model was developed for use with a model-based diagnostic scheme for failure detection and diagnostics studies, as well as control design purposes.

Duyar, Ahmet; Eldem, Vasfi; Merrill, Walter; Guo, Ten-Huei

182

Animal Models for the Evaluation of Tissue Engineering Constructs  

Microsoft Academic Search

\\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.

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

183

Modelling and Inverse-Modelling: Experiences with O.D.E. Linear Systems in Engineering Courses  

ERIC Educational Resources Information Center

In engineering careers courses, differential equations are widely used to solve problems concerned with modelling. In particular, ordinary differential equations (O.D.E.) linear systems appear regularly in Chemical Engineering, Food Technology Engineering and Environmental Engineering courses, due to the usefulness in modelling chemical kinetics,…

Martinez-Luaces, Victor

2009-01-01

184

Catastrophe-Theory Model for Simulating Behavioral Accidents.  

National Technical Information Service (NTIS)

Behavioral accidents are caused by inappropriate individual behaviors and faulty reactions. Catastrophe theory is a means for mathematically modeling the dynamic processes that underlie behavioral accidents. Based on a comprehensive data base of mining ac...

W. E. Souder

1986-01-01

185

Spray\\/wall interaction models for multidimensional engine simulation  

Microsoft Academic Search

Models were developed to describe the spray wall impingement processes that take place in internal combustion engines. In this report focus is placed on the model formulation and experiment assessment of the spray\\/wall interaction submodels. It is identified that the Leidenfrost phenomenon is very unlikely to occur in a spark ignition (SI) engine including stratified-charge operation in a direct injection

Z Han; Z Xu; N Trigui

2000-01-01

186

A technology empowerment model for engineering work  

Microsoft Academic Search

Seeking to enhance the use of information technology for problem solving\\/decision support efforts and innovation in engineering work, management has sought to empower engineers by investing in increasingly powerful software capabilities and peer support networks to facilitate an experiential process of working and learning. Based on the concept of psychological empowerment from the management literature, the researchers propose a technology

William J. Doll; Xiaodong Deng

2010-01-01

187

Experimental and modeling study of engine knock  

Microsoft Academic Search

Raman and emission spectroscopy, laser induced fluorescence, schlieren photography, and gas sampling have been used in a single cylinder, spark ignition engine to study preflame conditions and reactions that lead to knock. The intake manifold temperature and pressure were used to control the fraction of fuel autoigniting in a 5.1 compression ratio engine. N-butane, isobutane, and propane were studied, but

J. R. Smith; R. M. Green; C. K. Westbrook; W. J. Pitz

1984-01-01

188

Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior  

Microsoft Academic Search

Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the

B. Klem; D. Swann

2011-01-01

189

Engineering-Level Model Atmospheres for Titan and Neptune.  

National Technical Information Service (NTIS)

Engineering-level atmospheric models for Titan and Neptune have been developed for use in NASA's systems analysis studies of aerocapture applications in missions to the outer planets. Analogous to highly successful Global Reference Atmospheric Models for ...

A. Duvall C. G. Justus D. L. Johnson

2003-01-01

190

Engineering model 8-cm thruster subsystem  

NASA Technical Reports Server (NTRS)

An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package.

Herron, B. G.; Hyman, J.; Hopper, D. J.; Williamson, W. S.; Dulgeroff, C. R.; Collett, C. R.

1978-01-01

191

Human factors engineering program review model  

SciTech Connect

The staff of the Nuclear Regulatory Commission is performing nuclear power plant design certification reviews based on a design process plan that describes the human factors engineering (HFE) program elements that are necessary and sufficient to develop an acceptable detailed design specification and an acceptable implemented design. There are two principal reasons for this approach. First, the initial design certification applications submitted for staff review did not include detailed design information. Second, since human performance literature and industry experiences have shown that many significant human factors issues arise early in the design process, review of the design process activities and results is important to the evaluation of an overall design. However, current regulations and guidance documents do not address the criteria for design process review. Therefore, the HFE Program Review Model (HFE PRM) was developed as a basis for performing design certification reviews that include design process evaluations as well as review of the final design. A central tenet of the HFE PRM is that the HFE aspects of the plant should be developed, designed, and evaluated on the basis of a structured top-down system analysis using accepted HFE principles. The HFE PRM consists of ten component elements. Each element in divided into four sections: Background, Objective, Applicant Submittals, and Review Criteria. This report describes the development of the HFE PRM and gives a detailed description of each HFE review element.

Not Available

1994-07-01

192

A WEAR MODEL FOR DIESEL ENGINE EXHAUST VALVES  

SciTech Connect

The work summarized here comprises the concluding effort of a multi-year project, funded by the U.S. Department of Energy, Office of Vehicle Technologies. It supports the development of a better understanding of advanced diesel engine designs in which enhanced power density, energy efficiency, and emissions control place increasing demands upon the durability of engine materials. Many kinds of metallic alloys are used in engines depending on the operating stresses, temperatures, and chemical environments. Exhaust valves, for example, are subjected to high temperatures and repetitive surface contacts that place demands on durability and frictional characteristics of the materials. Valves must continue to seal the combustion chamber properly for thousands of hours of cyclic engine operation and under varying operating conditions. It was the focus of this effort to understand the wear processes in the valve-seat area and to develop a model for the surface deformation and wear of that important interface. An annotated bibliography is provided to illustrate efforts to understand valve wear and to investigate the factors of engine operation that affect its severity and physical manifestation. The project for which this modeling effort was the final task, involved construction of a high-temperature repetitive impact test system as well as basic tribology studies of the combined processes of mechanical wear plus oxidation at elevated temperatures. Several publications resulted from this work, and are cited in this report. The materials selected for the experimental work were high-performance alloys based on nickel and cobalt. In some cases, engine-tested exhaust valves were made available for wear analysis and to ensure that the modes of surface damage produced in experiments were simulative of service. New, production-grade exhaust valves were also used to prepare test specimens for experimental work along with the other alloy samples. Wear analysis of valves and seats run for hundreds of hours in heavy-duty diesels provided insights into the kinds of complexity that the contact conditions in engines can produce, and suggested the physical basis for the current approach to modeling. The model presented here involves four terms, two representing the valve response and two for its mating seat material. The model's structure assumes that wear that takes place under a complex combination of plastic deformation, tangential shear, and oxidation. Tribolayers form, are removed, and may reform. Layer formation affects the friction forces in the interface, and in turn, the energy available to do work on the materials to cause wear. To provide friction data for the model at various temperatures, sliding contact experiments were conducted from 22 to 850 C in a pin-on-disk apparatus at ORNL. In order to account for the behavior of different materials and engine designs, parameters in all four terms of the model can be adjusted to account for wear-in and incubation periods before the dominant wear processes evolve to their steady-state rates. For example, the deformation rate is assumed to be maximum during the early stages of operation, and then, due to material work-hardening and the increase in nominal contact area (which reduces the load per unit area), decreases to a lower rate at long times. Conversely, the rate of abrasion increases with time or number of cycles due to the build-up of oxides and tribo-layers between contact surfaces. The competition between deformation and abrasion results in complex, non-linear behavior of material loss per cycle of operation. Furthermore, these factors are affected by valve design features, such as the angle of incline of the valve seat. Several modeling scenarios are presented to demonstrate how the wear profile versus number of cycles changes in response to: (a) different relative abrasion rates of the seat and valve materials, (b) the friction coefficient as a function of temperature, (c) the relative deformation contribution of valve and seat materials, and (d) an interruption in the dominant we

Blau, Peter Julian [ORNL

2009-11-01

193

Towards Understanding and Modeling Individual Behavior and Group Dynamics  

Microsoft Academic Search

Understanding human behavior is a very complex task. In this paper we present our initial thoughts on modeling and automatic recognition of human activities. We argue that to successfully model human behavior, we need to consider both individual behavior and group dynamics. To demonstrate these theoretical approaches, we also introduce two experimental systems for collecting experimental data of complex behaviors.

Michele Bezzi; Robin Groenevelt

194

Engineering teacher training models and experiences  

NASA Astrophysics Data System (ADS)

Institutions and Organisations that take training seriously and devote time, effort and resources, etc, to their own teams are more likely to succeed, since both initial teacher training and continuous improvement, studies, hours of group discussion, works on innovation and educational research, talks and permanent meetings, etc, will all serve to enhance teaching and its quality. Teachers will be able to introduce new components from previously taught classes into their university teaching which will contribute to improving their work and developing a suitable academic environment to include shared objectives, teachers and students. Moreover, this training will serve to enhance pedagogic innovation, new teaching-learning methodologies and contribute to getting teaching staff involved in respect of the guidelines set out by the EHEA. Bearing in mind that training and motivation can be key factors in any teacher's "performance", their productivity and the quality of their teaching, Teacher Training for a specific post inside the University Organisation is standard practice of so-called Human Resources management and an integral part of a teacher's work; it is a way of professionalising the teaching of the different branches of Engineering. At Madrid Polytechnic University, in the Institute of Educational Sciences (ICE), since it was founded in 1972, we have been working hard with university teaching staff. But it was not until 1992 after carrying out various studies on training needs that we planned and programmed different training actions, offering a wide range of possibilities. Thus, we designed and taught an "Initial Teacher Training Course", as it was first called in 1992, a programme basically aimed to train young Engineering teachers just setting out on their teaching career. In 2006, the name was changed to "Advanced University Teacher Training Course". Subsequently, with the appearance of the Bologna Declaration and the creation of the European Higher Education Area, we renewed the programme, content and methodology, teaching the course under the name of "Initial Teacher Training Course within the framework of the European Higher Education Area". Continuous Training means learning throughout one's life as an Engineering teacher. They are actions designed to update and improve teaching staff, and are systematically offered on the current issues of: Teaching Strategies, training for research, training for personal development, classroom innovations, etc. They are activities aimed at conceptual change, changing the way of teaching and bringing teaching staff up-to-date. At the same time, the Institution is at the disposal of all teaching staff as a meeting point to discuss issues in common, attend conferences, department meetings, etc. In this Congress we present a justification of both training models and their design together with some results obtained on: training needs, participation, how it is developing and to what extent students are profiting from it.

González-Tirados, R. M.

2009-04-01

195

Box-Cox Mixed Logit Model for Travel Behavior Analysis  

NASA Astrophysics Data System (ADS)

To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their principal areas of application. In the transport field, they have mainly been applied to mode choice, but also to the selection of destination, route, and other important decisions such as the vehicle ownership. In usual practice, the most frequently employed discrete choice models implement a fixed coefficient utility function that is linear in the parameters. The principal aim of this paper is to present the viability of specifying utility functions with random coefficients that are nonlinear in the parameters, in applications of discrete choice models to transport. Nonlinear specifications in the parameters were present in discrete choice theory at its outset, although they have seldom been used in practice until recently. The specification of random coefficients, however, began with the probit and the hedonic models in the 1970s, and, after a period of apparent little practical interest, has burgeoned into a field of intense activity in recent years with the new generation of mixed logit models. In this communication, we present a Box-Cox mixed logit model, original of the authors. It includes the estimation of the Box-Cox exponents in addition to the parameters of the random coefficients distribution. Probability of choose an alternative is an integral that will be calculated by simulation. The estimation of the model is carried out by maximizing the simulated log-likelihood of a sample of observed individual choices between alternatives. The differences between the predictions yielded by models that are inconsistent with real behavior have been studied with simulation experiments.

Orro, Alfonso; Novales, Margarita; Benitez, Francisco G.

2010-09-01

196

Supercomputer modeling of hydrogen combustion in rocket engines  

NASA Astrophysics Data System (ADS)

Hydrogen being an ecological fuel is very attractive now for rocket engines designers. However, peculiarities of hydrogen combustion kinetics, the presence of zones of inverse dependence of reaction rate on pressure, etc. prevents from using hydrogen engines in all stages not being supported by other types of engines, which often brings the ecological gains back to zero from using hydrogen. Computer aided design of new effective and clean hydrogen engines needs mathematical tools for supercomputer modeling of hydrogen-oxygen components mixing and combustion in rocket engines. The paper presents the results of developing verification and validation of mathematical model making it possible to simulate unsteady processes of ignition and combustion in rocket engines.

Betelin, V. B.; Nikitin, V. F.; Altukhov, D. I.; Dushin, V. R.; Koo, Jaye

2013-08-01

197

Civil engineering: EDF needs for concrete modelling.  

National Technical Information Service (NTIS)

Concrete structures which are encountered at EDF, like all civil engineering structures, age. In order to adapt the maintenance conditions of these structures, particularly to extend their service life, and also to prepare constructions of future structur...

O. Didry B. Gerard D. Bui

1997-01-01

198

Human Behavior Modeling Method Based on the Causality Between the Situation and the Behavior  

NASA Astrophysics Data System (ADS)

Various kinds of sophisticated systems are utilized in our daily life, therefore these systems must have the ability to work considering behaviors of humans around them. In order to realize such a system, a kind of human behavior modeling method is required. In this paper, we propose a new modeling method of human behaviors based on the causality between the situation around a person and the human behavior. In this method, we suppose that a person changes his behavior according to the change of the situation around him. In this paper, a human behavior is discribed by a discrete event and the situation around the person is described by multidimensional time series signal. The causality between the time series data of the situation and the discrete event of the human behavior is defined as behavior rule. In this rule, the multidimensional time series data is modeled by HMM(Hidden Markov Model) in order to consider its temporal and spatial redundancy. Various kinds of human behavior rules are acquired based on the combination between the situation around a person and his behavior. Therefore, a set of these human behavior rules is called as a human behavior model in this paper. In the experiment, the controller operation of a radio controlled vehicle is modeled by the proposed method. The usefulness of the proposed method is examined through some experimental results with the estimation system of the next human behavior based on the generated behavior model.

Hashimoto, Kohjiro; Doki, Kae; Doki, Shinji; Okuma, Shigeru; Torii, Akihiro

199

Concepts, Model and Framework of Cooperative Software Engineering  

Microsoft Academic Search

\\u000a Recently, the cooperation aspect of distributed teamwork in software engineering has become a hot research topic. This paper\\u000a first reviews the concepts of cooperative software engineering. Then, a process model for cooperative software engineering\\u000a is investigated, which forms the starting point for the analysis, structuring, management and synchronization of cooperative\\u000a software development tasks. Next, universal design principles for an environment

Yong Tang; Yan Pan; Lu Liang; Hui Ma; Na Tang

2004-01-01

200

ADVANCED FMEA USING META BEHAVIOR MODELING FOR CONCURRENT DESIGN OF PRODUCTS AND CONTROLS  

Microsoft Academic Search

This paper presents the use of Advanced Failure Modes and Effects Analysis (AFMEA) as a methodology for the concurrent design of electro-mecha nical products and their control systems. The past two years have seen the extension of AFMEA to simulate dynamic changes of device operations using meta-behavior modeling. This approach can help engineers identify failure modes associated with controls and

Steven Kmenta; Kosuke Ishii

1998-01-01

201

The Senior High School Students' Learning Behavioral Model of STEM in PBL  

ERIC Educational Resources Information Center

The purpose of the study was to explore a learning behavioral model of project-based learning (PBL) for senior high school students in the context of STEM (science, technology, engineering, and mathematics). Using "audio speakers" as the project theme, a series of tasks were designed to be solved using STEM knowledge via an online platform and…

Lou, Shi Jer; Liu, Yi Hui; Shih, Ru Chu; Tseng, Kuo Hung

2011-01-01

202

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

203

Multi-scale models for gene network engineering  

Microsoft Academic Search

With current advances in biological knowledge, the potential exists for engineering novel gene regulatory networks, which allow the timely control of protein expression. Genome projects identify the components of gene networks in biological organisms, gene after gene, and DNA microarray experiments discover the network connections. Yet, the static pictures these experiments give cannot provide insight on the dynamic behavior of

Yiannis N. Kaznessis

2006-01-01

204

MODAL TEST EXPERIENCES WITH A JET ENGINE FAN MODEL  

Microsoft Academic Search

High cycle fatigue in jet engine blades is caused by excessive vibration. Understanding the dynamic response of the bladed disk system is important in determining vibration levels. Modal testing is a useful tool in understanding the dynamic behavior of structures. However, modal tests are not conducted on bladed disks because of the difficulties involved. One problem is that the overall

J. J. Hollkamp; R. W. GORDON

2001-01-01

205

Genetically engineered humanized mouse models for preclinical antibody studies.  

PubMed

The use of genetic engineering has vastly improved our capabilities to create animal models relevant in preclinical research. With the recent advances in gene-editing technologies, it is now possible to very rapidly create highly tunable mouse models as needs arise. Here, we provide an overview of genetic engineering methods, as well as the development of humanized neonatal Fc receptor (FcRn) models and their use for monoclonal antibody in vivo studies. PMID:24150980

Proetzel, Gabriele; Wiles, Michael V; Roopenian, Derry C

2014-04-01

206

Component-specific modeling. [jet engine hot section components  

NASA Technical Reports Server (NTRS)

Accomplishments are described for a 3 year program to develop methodology for component-specific modeling of aircraft hot section components (turbine blades, turbine vanes, and burner liners). These accomplishments include: (1) engine thermodynamic and mission models, (2) geometry model generators, (3) remeshing, (4) specialty three-dimensional inelastic structural analysis, (5) computationally efficient solvers, (6) adaptive solution strategies, (7) engine performance parameters/component response variables decomposition and synthesis, (8) integrated software architecture and development, and (9) validation cases for software developed.

Mcknight, R. L.; Maffeo, R. J.; Tipton, M. T.; Weber, G.

1992-01-01

207

Application of CFD technique for modelling of the thermoacoustic engine  

NASA Astrophysics Data System (ADS)

The paper is concerned with an important issue from the field of thermoacoustics - the numerical modelling of the flow field in the thermoacoustic engine. The presented way of modelling is based on the solution to fundamental fluid mechanics equations that govern the flow of compressible, viscous, and heat-transferring gas. The paper presents the way of modelling the thermoacoustic engine, the way of conducting calculations and the results which illustrate the correctness of the selected computational technique.

Rulik, Sebastian; Remiorz, Leszek; Dykas, S?awomir

2011-12-01

208

Proper Powertrain Modeling for Engine-in-the-Loop Simulation  

Microsoft Academic Search

This paper presents a proper model of a High-Mobility Multi- purpose Wheeled Vehicle's (HMMWV) four-speed automatic transmission powertrain. The model is simultaneously accurate enough to capture key powertrain transients and fast enough to run in real time. The model's parameters are scaled to match a power- ful new diesel engine proposed for HMMWV propulsion. This enables real time hardware-in-the-loop engine

Hosam K. Fathy; Rahul Ahlawat; Jeffrey L. Stein

2005-01-01

209

Enabler 1 and 2 engine system design modeling and comparisons  

NASA Technical Reports Server (NTRS)

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.

Pelaccio, Dennis G.; Scheil, Christine M.

1993-01-01

210

Development and testing of diesel engine CFD models  

Microsoft Academic Search

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

R. D. Reitz; C. J. Rutland

1995-01-01

211

5. Historic photo of scale model of rocket engine test ...  

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

5. Historic photo of scale model of rocket engine test facility, June 18, 1957. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA GRC photo number C-45264. - Rocket Engine Testing Facility, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

212

Experimental Model for Stimulating Creative Problem Solving by Engineering Students.  

ERIC Educational Resources Information Center

A heuristic model designed to improve creative problem-solving by engineering students was studied. Ten students majoring in industrial engineering were pre-tested to establish the range and accuracy of their performance prior to training and to identify stereotyped thinking. The test was an adventure scenario with 50 embedded problems along with…

Hayes, Harold L.

213

Dynamics of macroautophagy: Modeling and oscillatory behavior  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

214

Iterative procedures for space shuttle main engine performance models  

NASA Technical Reports Server (NTRS)

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.

Santi, L. Michael

1989-01-01

215

Unified constitutive model for single crystal deformation behavior with applications  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

216

Engineering complex topological memories from simple Abelian models  

SciTech Connect

In three spatial dimensions, particles are limited to either bosonic or fermionic statistics. Two-dimensional systems, on the other hand, can support anyonic quasiparticles exhibiting richer statistical behaviors. An exciting proposal for quantum computation is to employ anyonic statistics to manipulate information. Since such statistical evolutions depend only on topological characteristics, the resulting computation is intrinsically resilient to errors. The so-called non-Abelian anyons are most promising for quantum computation, but their physical realization may prove to be complex. Abelian anyons, however, are easier to understand theoretically and realize experimentally. Here we show that complex topological memories inspired by non-Abelian anyons can be engineered in Abelian models. We explicitly demonstrate the control procedures for the encoding and manipulation of quantum information in specific lattice models that can be implemented in the laboratory. This bridges the gap between requirements for anyonic quantum computation and the potential of state-of-the-art technology. - Highlights: > A novel quantum memory using Abelian anyons is developed. > This uses an advanced encoding, inspired by non-Abelian anyons. > Errors are suppressed topologically, by means of single spin interactions. > An implementation with current Josephson junction technology is proposed.

Wootton, James R., E-mail: phyjrw@leeds.ac.uk [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Lahtinen, Ville [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Doucot, Benoit [Laboratoire de Physique Theorique et Hautes Energies, Universite Paris 6 et 7, Paris (France); Pachos, Jiannis K. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)

2011-09-15

217

Modeling crawling cell movement on soft engineered substrates.  

PubMed

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 generalize our recently developed 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. PMID:24651116

Löber, Jakob; Ziebert, Falko; Aranson, Igor S

2014-03-01

218

Dimensionality reduction for uncertainty quantification of nuclear engineering models  

Microsoft Academic Search

The task of uncertainty quantification consists of relating the available information on uncertainties in the model setup to the resulting variation in the outputs of the model. Uncertainty quantification plays an important role in complex simulation models of nuclear engineering, where better understanding of uncertainty results in greater confidence in the model and in the improved safety and efficiency of

O. Roderick; Z. Wang; M. Anitescu

2011-01-01

219

Mathematical modeling of the behavior of geothermal systems under exploitation  

SciTech Connect

Analytical and numerical methods have been used in this investigation to model the behavior of geothermal systems under exploitation. The work is divided into three parts: (1) development of a numerical code, (2) theoretical studies of geothermal systems, and (3) field applications. A new single-phase three-dimensional simulator, capable of solving heat and mass flow problems in a saturated, heterogeneous porous or fractured medium has been developed. The simulator uses the integrated finite difference method for formulating the governing equations and an efficient sparse solver for the solution of the linearized equations. In the theoretical studies, various reservoir engineering problems have been examined. These include (a) well-test analysis, (b) exploitation strategies, (c) injection into fractured rocks, and (d) fault-charged geothermal reservoirs.

Bodvarsson, G.S.

1982-01-01

220

Visualization of liquid fuel behavior in a spark ignition engine during starting and warm-up  

Microsoft Academic Search

The liquid fuel behavior in the intake port and the cylinder during starting and warm-up was visualized through visualization\\u000a windows using a high speed CCD camera. The videos were taken with the engine firing under cold conditions in the simulated\\u000a start up process, at 1.000 and 1.200 RPM and intake manifold pressure of 0.5 bar. The variables examined were the

Younggy Shin

1997-01-01

221

Analyzing critical process models through behavior model synthesis  

Microsoft Academic Search

Process models capture tasks performed by agents together with their control flow. Building and analyzing such models is important but difficult in certain areas such as safety-critical healthcare processes. Tool-supported techniques are needed to find and correct flaws in such processes. On another hand, event-based formalisms such as Labeled Transition Systems (LTS) prove effective for analyzing agent behaviors. The paper

Christophe Damas; Bernard Lambeau; Francois Roucoux; Axel Van Lamsweerde

2009-01-01

222

Model predicts crack growth and material behavior  

SciTech Connect

The crack-driving force in line-pipe steel material can be expected to increase as a consequence of cyclic load and hold-time effects. These effects are especially evident during hydrotesting. In addition, repeated hydrotesting can cause cracks to grow at pressures less than achieved in a prior test. These are only two of the major conclusions from full-scale tests of line pipe with patched through-wall flaws and part-through-wall flaws. These tests form the basis for judgments about the accuracy of flaw growth and failure-pressure predictions. For these tests, an engineering model of ductile flaw growth in line-pipe steels based on J-tearing theory was developed to assess flaw growth during hydrotesting. This paper presents the theory and discusses the tests conducted.

Leis, B.N.; Brust, F.W. (Battelle Columbus Division, Columbus, OH (US))

1990-02-01

223

Engine System Model Development for Nuclear Thermal Propulsion  

NASA Technical Reports Server (NTRS)

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.

Nelson, Karl W.; Simpson, Steven P.

2006-01-01

224

Communicating to Farmers about Skin Cancer: The Behavior Adaptation Model.  

ERIC Educational Resources Information Center

States health campaign messages designed to encourage behavior adaptation have greater likelihood of success than campaigns promoting avoidance of at-risk behaviors that cannot be avoided. Tests a model of health risk behavior using four different behaviors in a communication campaign aimed at reducing farmers' risk for skin cancer--questions…

Parrott, Roxanne; Monahan, Jennifer; Ainsworth, Stuart; Steiner, Carol

1998-01-01

225

Modeling Impact Behavior of Glass with Peridynamics  

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

226

Modeling chemical kinetic aspects of engine knock  

Microsoft Academic Search

A chemical kinetics oxidation mechanism for n-butane is employed to study hydrocarbon autoignition related to engine knock. A low temperature submechanism has been added to a previously developed high temperature mechanism in order to examine the importance of low temperature reaction paths in autoignition. A series of calculations follows reactions taking place in a sample of end-gas that is subjected

W. J. Pitz; C. K. Westbrook

1984-01-01

227

Modeling uncertainty in requirements engineering decision support  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

228

Electromagnetic scattering from simple jet engine models  

Microsoft Academic Search

The mode-matching (MM) technique is employed for the evaluation of the radar cross section (RCS) of structures that simulate a jet engine inlet. The geometry consists of a perfectly conducting cylindrical inlet terminated by an array of blades mounted on a cylindrical hub. Comparisons of numerical results with actual measurements are presented for the first time

H. T. Anastassiu; J. L. Volakis; D. C. Ross; D. Andersh

1996-01-01

229

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

NASA Technical Reports Server (NTRS)

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.

1928-01-01

230

Model-Based Simulations to Engineer Nanoporous Thin Films.  

National Technical Information Service (NTIS)

A model-based simulation (MBS) capability for tailoring the fabrication processes and the properties of wide band gap semiconductors thin films (TF) with engineered nanoscale porosity has been achieved in two ways: (1) By using molecular dynamics simulati...

F. Costanzo

2004-01-01

231

Thermal Barrier Coating Life Modeling in Aircraft Gas Turbine Engines.  

National Technical Information Service (NTIS)

Analytical models useful for predicting ceramic thermal barrier coating (TBC) spalling life in aircraft gas turbine engines are presented. Electron beam-physical vapor deposited (EB-PVD) and plasma sprayed TBC systems are discussed. TBC spalling was attri...

D. M. Nissley

1995-01-01

232

Micellization behavior of coarse grained surfactant models.  

PubMed

We use molecular dynamics simulations over microsecond time scales to study the micellization behavior of recently proposed continuum-space, coarse grained surfactant models. In particular, we focus on the MARTINI model by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] and a model by Shinoda et al. [Soft Matter 4, 2454 (2008)]. We obtain the critical micelle concentration (cmc) and equilibrium aggregate size distributions at low surfactant loadings. We present evidence justifying modest extrapolations for determining the cmc at low temperatures, where significant sampling difficulties remain. The replica exchange method provides only modest improvements of sampling efficiency for these systems. We find that the two coarse grained models significantly underpredict experimental cmc near room temperature for zwitterionic surfactants, but are closer to measured values for nonionic ones. The aggregation numbers for both zwitterionic and nonionic surfactants are near those observed experimentally, but the temperature dependence of the cmc is incorrect in both cases, because of the use of an unstructured solvent. Possible refinements to the models to bring them into quantitative agreement with experiment are discussed. PMID:20331315

Sanders, Samantha A; Panagiotopoulos, Athanassios Z

2010-03-21

233

Micellization behavior of coarse grained surfactant models  

NASA Astrophysics Data System (ADS)

We use molecular dynamics simulations over microsecond time scales to study the micellization behavior of recently proposed continuum-space, coarse grained surfactant models. In particular, we focus on the MARTINI model by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] and a model by Shinoda et al. [Soft Matter 4, 2454 (2008)]. We obtain the critical micelle concentration (cmc) and equilibrium aggregate size distributions at low surfactant loadings. We present evidence justifying modest extrapolations for determining the cmc at low temperatures, where significant sampling difficulties remain. The replica exchange method provides only modest improvements of sampling efficiency for these systems. We find that the two coarse grained models significantly underpredict experimental cmc near room temperature for zwitterionic surfactants, but are closer to measured values for nonionic ones. The aggregation numbers for both zwitterionic and nonionic surfactants are near those observed experimentally, but the temperature dependence of the cmc is incorrect in both cases, because of the use of an unstructured solvent. Possible refinements to the models to bring them into quantitative agreement with experiment are discussed.

Sanders, Samantha A.; Panagiotopoulos, Athanassios Z.

2010-03-01

234

Evaluation of the Munich Method for modeling rocket engine performance  

NASA Technical Reports Server (NTRS)

A new procedure, dubbed the Munich Method, has been proposed recently for the modeling of rocket engine performance. The author of the Munich Method claims it to be an extension and improvement of the thermodynamic procedures used to model rocket engines in the NASA-Lewis chemical equilibrium program. An examination of the Munich Method shows that it contains several flaws. If these defects are corrected then the Munich Method will produce results identical to those generated by the NASA-Lewis Code.

Zeleznik, Frank J.

1993-01-01

235

Hybrid Model Predictive Control of Direct Injection Stratified Charge Engines  

Microsoft Academic Search

This paper illustrates the application of hybrid modeling and model predictive control techniques to the management of air-to-fuel ratio and torque in advanced technology gasoline direct-injection stratified-charge (DISC) engines. A DISC engine is an example of a constrained hybrid dynamical system, because it can operate in two distinct modes (stratified and homogeneous) and because the mode-dependent constraints on the air-to-fuel

N. Giorgetti; G. Ripaccioli; A. Bemporad; I. V. Kolmanovsky; D. Hrovat

2006-01-01

236

GEO-ENGINEERING MODELING THROUGH INTERNET INFORMATICS (GEMINI)  

Microsoft Academic Search

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

W. Lynn Watney; John H. Doveton

2004-01-01

237

Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior  

NASA Astrophysics Data System (ADS)

Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection from both the sun and the underlying earth surface. The objects are modeled to be either tumbling or spin stabilized at key orientations in order to capture the complexity of the solar/earth incident illumination and the sensor viewing aspect conditions. Although these geometries and processes appear to be specialized and limited, they are sufficient to capture the principal observable features that are necessary for gaining insight into the complex issues of interpreting non-imaging sensor signals for monitoring the actual on-orbit spacecraft behavior changes. This talk has been prepared as a poster paper, to allow for engagement with conference participants on the presentation contents, and discussions for expansion of the material to include additional topical areas for future work, as appropriate. All discussions have been limited only to topics that could be discussed in the open format of the conference.

Klem, B.; Swann, D.

2011-09-01

238

Beam-Riding Behavior of Lightcraft Engines with ~ 1 ?s Pulsed TEA CO2 Laser  

NASA Astrophysics Data System (ADS)

The beam-riding and angular impulse performance of four laser propulsion engine geometries were measured using a twin Lumonics K922M pulsed TEA CO2 laser system, with an Angular Impulse Measurement Device (AIMD). Airbreathing and solid ablative rocket (SAR) mode impulse data was collected to explore engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the engine axis of symmetry; b) laser pulse duration (~ 50 ns spike with selectable 1.5 or 2.5 ?s tail--depending upon laser gas mixture) and c) engine geometry (Lightcraft Type No.150, No.200, No.250, and parabolic bell). Maximum airbreathing lateral momentum coupling coefficients (CM) up to 77 N-s/MJ were achieved with the K922M laser; this represents a vast improvement over previous PLVTS laser (~ 420 J, 18 ?s duration) results which reached only 15 N-s/MJ. Lateral CM performance of the No.200 SAR Lightcraft engine was measured experimentally for the first time, using Delrin® propellant inserts.

Kenoyer, D. A.; Salvador, I. I.; Myrabo, L. N.

2011-11-01

239

Review of aerospace engineering cost modelling: The genetic causal approach  

NASA Astrophysics Data System (ADS)

The primary intention of this paper is to review the current state of the art in engineering cost modelling as applied to aerospace. This is a topic of current interest and in addressing the literature, the presented work also sets out some of the recognised definitions of cost that relate to the engineering domain. The paper does not attempt to address the higher-level financial sector but rather focuses on the costing issues directly relevant to the engineering process, primarily those of design and manufacture. This is of more contemporary interest as there is now a shift towards the analysis of the influence of cost, as defined in more engineering related terms; in an attempt to link into integrated product and process development (IPPD) within a concurrent engineering environment. Consequently, the cost definitions are reviewed in the context of the nature of cost as applicable to the engineering process stages: from bidding through to design, to manufacture, to procurement and ultimately, to operation. The linkage and integration of design and manufacture is addressed in some detail. This leads naturally to the concept of engineers influencing and controlling cost within their own domain rather than trusting this to financers who have little control over the cause of cost. In terms of influence, the engineer creates the potential for cost and in a concurrent environment this requires models that integrate cost into the decision making process.

Curran, R.; Raghunathan, S.; Price, M.

2004-11-01

240

Statistical validation of engineering and scientific models : bounds, calibration, and extrapolation.  

SciTech Connect

Numerical models of complex phenomena often contain approximations due to our inability to fully model the underlying physics, the excessive computational resources required to fully resolve the physics, the need to calibrate constitutive models, or in some cases, our ability to only bound behavior. Here we illustrate the relationship between approximation, calibration, extrapolation, and model validation through a series of examples that use the linear transient convective/dispersion equation to represent the nonlinear behavior of Burgers equation. While the use of these models represents a simplification relative to the types of systems we normally address in engineering and science, the present examples do support the tutorial nature of this document without obscuring the basic issues presented with unnecessarily complex models.

Dowding, Kevin J.; Hills, Richard Guy (New Mexico State University, Las Cruces, NM)

2005-04-01

241

A Markov Chain Model of Temporal Behavior for Anomaly Detection  

Microsoft Academic Search

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

Nong Ye

2000-01-01

242

A Conceptual Model of Leisure-Time Choice Behavior.  

ERIC Educational Resources Information Center

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)

Bergier, Michel J.

1981-01-01

243

Expectancy Theory as a Predictive Model of Career Intent, Job Satisfaction, and Institution-Occupation Orientation among Air Force Officer Scientists and Engineers.  

National Technical Information Service (NTIS)

This research study examines career intent, job satisfaction, and institution-occupation orientation among members of the scientific and engineering career fields (26XX and 28XX, respectively) using a model of behavioral choice and motivation known as Exp...

L. M. Lewis

1978-01-01

244

Shuttle passenger couch. [design and performance of engineering model  

NASA Technical Reports Server (NTRS)

Conceptual design and fabrication of a full scale shuttle passenger couch engineering model are reported. The model was utilized to verify anthropometric dimensions, reach dimensions, ingress/egress, couch operation, storage space, restraint locations, and crew acceptability. These data were then incorported in the design of the passenger couch verification model that underwent performance tests.

Rosener, A. A.; Stephenson, M. L.

1974-01-01

245

Elementary external SGEMP model for system engineering design  

NASA Astrophysics Data System (ADS)

Elementary algebraic models for maximum external SGEMP response current are presented. Models predict body current on an isolated cylindrical object in partial atmosphere. Models have been validated by comparison to test data, and are useful for system engineering design studies to estimate external SGEMP response.

Schmidt, M. J.

1985-12-01

246

A Component Model Engineered with Components and Aspects  

Microsoft Academic Search

This paper presents AOKell, a framework for engineering component-based systems. This framework implements the Fractal model, a hierarchical and dynamic component model. The novelty of this paper lies in the presentation of AOKell, an implementation of the Fractal model with aspects. Two dimensions can be isolated with Fractal: the functional dimension, which is concerned with the definition of application components,

Lionel Seinturier; Nicolas Pessemier; Laurence Duchien; Thierry Coupaye

2006-01-01

247

Nonlinear Low Frequency Phenomenological Engine Modeling and Analysis  

Microsoft Academic Search

The paper contains a bibliography and discussion of recent activity in nonthermodynamic (low frequency) internal combustion engine model development where spark advance, fuel, throttle, and exhaust gas recirculation are the elected control variables. Modeling considerations are delineated and the modeling relationship to experimental verification is discussed. Examples with explicit methods of parameter determination and dynamic validation are presented.

B. K. Powell; J. A. Cook

1987-01-01

248

Engineering modelling. A contribution to the CommonKADS library.  

National Technical Information Service (NTIS)

Generic knowledge components and models for the task of in particular engineering modelling are presented.It is intended as a contribution to the CommonKADS library. In the first chapter an executive summary is provided. Next, the Conceptual Modelling Lan...

J. L. Top J. M. Akkermans

1993-01-01

249

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

NASA Technical Reports Server (NTRS)

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.

Smith, R. E.

1998-01-01

250

GAS TURBINE ENGINE PERFORMANCE MODEL APPLICATIONS USING AN OBJECT ORIENTED SIMULATION TOOL  

Microsoft Academic Search

Engine performance models are used throughout the life cycle of an engine from conceptual design to testing, certification and maintenance. The objective of this paper is to demonstrate the use and advantages of an engine performance model, developed using an object-oriented simulation tool, for the following applications: É Building an engine model from existing engine components and running steady state

A. Alexiou; K. Mathioudakis

2006-01-01

251

Selection, evolution of behavior and animal models in behavioral neuroscience  

Microsoft Academic Search

We investigated whether genetic differences in various forms of intraspecific aggression and anxiety in four different genetic lines of mice (i.e. wild, outbred Swiss-CD1, inbred DBA\\/2 and inbred C57\\/BL6N) may reflect modifications in behavioral strategy. Experiments 1 and 2 used ethologically based paradigms to analyze aggressive and anxiety responses both in social (i.e. aggression) and non-social (i.e. novel environment exploration)

Stefano Parmigiani; Paola Palanza; John Rodgersb; Piers Francesco Ferrari

1999-01-01

252

Thermodynamic and rheological modeling of coal ash behavior  

Microsoft Academic Search

This paper describes some recent results attained in modelling the behavior of coal ash and slags derived from it. This work is part of a larger effort which seeks to develop a unified model of ash behavior in combustion or gasification systems. A detailed description of the modelling effort has recently been published. Briefly, the focus of the model is

H. H. Schobert; B. J. Jung

1988-01-01

253

Animal models of restricted repetitive behavior in autism  

PubMed Central

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.

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

2013-01-01

254

Modeling of tritium behavior in the environment  

SciTech Connect

In view of the operation of fusion reactors the release of tritium may play a dominant role during normal operation as well as after accidents. Because of its physical and chemical properties which differ significantly form those of other radionuclides, the model UFOTRI for assessing the radiological consequences of accidental tritium releases has been developed. It describes the behavior of tritium in the biosphere and calculates the radiological impact on individuals and the population due to direct exposure and by the ingestion pathways. In this paper, processes like the conversion of tritium gas into HTO in the soil, re-emission after deposition and the conversion of HTO into organically bound tritium are considered. Probabilistic calculations with UFOTRI show a spectrum of the radiological impact together with its probability of occurrence.

Raskob, W. (Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Neutronenphysik und Reaktortechnik)

1992-03-01

255

Modeling Human Behavior to Anticipate Insider Attacks  

SciTech Connect

The insider threat ranks among the most pressing cybersecurity challenges that threaten government and industry information infrastructures. To date, no systematic methods have been developed that provide a complete and effective approach to prevent data leakage, espionage and sabotage. Current practice is forensic in nature, relegating to the analyst the bulk of the responsibility to monitor, analyze, and correlate an overwhelming amount of data. We describe a predictive modeling framework that integrates a diverse set of data sources from the cyber domain as well as inferred psychological/motivational factors that may underlie malicious insider exploits. This comprehensive threat assessment approach provides automated support for the detection of high-risk behavioral “triggers” to help focus the analyst’s attention and inform the analysis. Designed to be domain independent, the system may be applied to many different threat and warning analysis/sensemaking problems.

Greitzer, Frank L.; Hohimer, Ryan E.

2011-06-09

256

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

257

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

Microsoft Academic Search

Jet engine behavior can be described by four major engine parameters and by their temporal and qualitative relationships. These parameters are rotational speeds of the low and high pressure turbine assemblies referred to as N1 and N2 respectively, exhaust gas temperature EGT, and combustion temperature COMBT. Normally, these parameters show stable readings. Faulty conditions like fuel interruption or bearing loss

U. K. Gupta; Moonis Ali

1988-01-01

258

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.

2008-08-06

259

Systems metabolic engineering: Genome-scale models and beyond  

PubMed Central

The advent of high throughput genome-scale bioinformatics has led to an exponential increase in available cellular system data. Systems metabolic engineering attempts to use data-driven approaches – based on the data collected with high throughput technologies – to identify gene targets and optimize phenotypical properties on a systems level. Current systems metabolic engineering tools are limited for predicting and defining complex phenotypes such as chemical tolerances and other global, multigenic traits. The most pragmatic systems-based tool for metabolic engineering to arise is the in silico genome-scale metabolic reconstruction. This tool has seen wide adoption for modeling cell growth and predicting beneficial gene knockouts, and we examine here how this approach can be expanded for novel organisms. This review will highlight advances of the systems metabolic engineering approach with a focus on de novo development and use of genome-scale metabolic reconstructions for metabolic engineering applications. We will then discuss the challenges and prospects for this emerging field to enable model-based metabolic engineering. Specifically, we argue that current state-of-the-art systems metabolic engineering techniques represent a viable first step for improving product yield that still must be followed by combinatorial techniques or random strain mutagenesis to achieve optimal cellular systems.

Blazeck, John; Alper, Hal

2010-01-01

260

Diesel engine exhaust emission: oxidative behavior and microstructure of black smoke soot particulate.  

PubMed

Soot particulate collected from a Euro III heavy duty diesel engine run under black smoke conditions was investigated using thermogravimetry, transmission electron microscopy, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy. The characterization results are compared with those of commercial carbon black. The onset temperature toward oxidation of the diesel engine soot in 5% O2 is 150 degrees C lower than that for carbon black. The burn out temperature for the diesel engine soot is 60 degrees C lower than that of the carbon black. The soot primary particles exhibit a core-shell structure. The shell of the soot particles consists of homogeneously stacked basic structure units. The commercial carbon lamp black is more graphitized than the diesel engine soot, whereas the diesel engine soot contains more carbon in aromatic nature than the carbon black and is highly surface-functionalized. Our findings reveal that technical carbon black is not a suitable model for the chemistry of the diesel engine soot. PMID:16572780

Müller, J O; Su, D S; Jentoft, R E; Wild, U; Schlögl, R

2006-02-15

261

Fusing Quantitative Requirements Analysis with Model-based Systems Engineering  

NASA Technical Reports Server (NTRS)

A vision is presented for fusing quantitative requirements analysis with model-based systems engineering. This vision draws upon and combines emergent themes in the engineering milieu. "Requirements engineering" provides means to explicitly represent requirements (both functional and non-functional) as constraints and preferences on acceptable solutions, and emphasizes early-lifecycle review, analysis and verification of design and development plans. "Design by shopping" emphasizes revealing the space of options available from which to choose (without presuming that all selection criteria have previously been elicited), and provides means to make understandable the range of choices and their ramifications. "Model-based engineering" emphasizes the goal of utilizing a formal representation of all aspects of system design, from development through operations, and provides powerful tool suites that support the practical application of these principles. A first step prototype towards this vision is described, embodying the key capabilities. Illustrations, implications, further challenges and opportunities are outlined.

Cornford, Steven L.; Feather, Martin S.; Heron, Vance A.; Jenkins, J. Steven

2006-01-01

262

Uranus Atmospheric Model for Engineering Application  

NASA Astrophysics Data System (ADS)

The poster/paper describes an atmospheric model for the planet Uranus constructed from published data based upon the Voyager-2 flyby of Uranus in 24 January 1986. This new model is designed for use in atmospheric probe trajectory simulation.

Allen, G. A.; Marley, M. A.; Agrawal, P.

2014-06-01

263

Mathematical Modeling by the Design Engineer.  

National Technical Information Service (NTIS)

The paper describes the type of model that is being developed for a hydraulic valve/actuator combination and discusses some fundamental characteristics of the dynamic operation of this type of hardware. Mathematical modeling presents the fluid power syste...

H. A. Price

1967-01-01

264

A dynamic context model of interactive behavior.  

PubMed

A dynamic context model of interactive behavior was developed to explain results from two experiments that tested the effects of interaction costs on encoding strategies, cognitive representations, and response selection processes in a decision-making and a judgment task. The model assumes that the dynamic context defined by the mixes of internal and external representations and processes are sensitive to the interaction cost imposed by the task environment. The model predicts that changes in the dynamic context may lead to systematic biases in cognitive representations and processes that eventually influence decision-making and judgment outcomes. Consistent with the predictions by the model, results from the experiments showed that as interaction costs increased, encoding strategies and cognitive representations shifted from perception-based to memory-based. Memory-based comparisons of the stimuli enhanced the similarity and dominance effects, and led to stronger systematic biases in response outcomes in a choice task. However, in a judgment task, memory-based representations enhanced only the dominance effects. Results suggested that systematic response biases in the dominance context were caused by biases in the cognitive representations of the stimuli, but response biases in the similarity context were caused by biases in the comparison process induced by the choice task. Results suggest that changes in interaction costs not only change whether information was assessed from the external world or from memory but also introduce systematic biases in the cognitive representation of the information, which act as biased inputs to the subsequent decision-making and judgment processes. Results are consistent with the idea of interactive cognition, which proposes that representations and processes are contingent on the dynamic context defined by the information flow between the external task environment and internal cognition. PMID:21736603

Fu, Wai-Tat

2011-07-01

265

Generic domain models in software engineering  

NASA Technical Reports Server (NTRS)

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.

Maiden, Neil

1992-01-01

266

Case Studies in Process Modeling (Engineering Statistics Handbook)  

NSDL National Science Digital Library

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.

Filliben, James; Heckert, Alan

2009-02-03

267

EHF (Extremely High Frequency) telecommunications system engineering model  

Microsoft Academic Search

An EHF Telecommunication System Engineering Model (ETSEM) has been developed as an aid in the design of line-of-sight (LOS) communication systems from 10 to 100 GHz. ETSEM provides tabulation of path geometry parameters and analyzes ray-path and Fresnel zone clearances to help the engineer design the path. ETSEM also predicts the performance (availability) of both digital and analog systems based

K. C. Allen

1986-01-01

268

Systems Model for Improving Standards and Retention In Engineering Education  

NSDL National Science Digital Library

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

Owusu, Yaw A. (Yaw Akyeaw-Brimpon)

2009-10-23

269

Research Study: Space Shuttle Main Engine Plume Flowfield Model  

NASA Technical Reports Server (NTRS)

The initial research effort was an in-depth analysis of the shuttle main engine plumes in an effort to improve the flowfield model and to enhance shuttle base heating equipment predictions during ascent. A prediction methodology code was developed incorporating the improved plume model into a predictive tool which could consider different trajectoreis and engine perfromance variables. Various plume flow model improvement studies were ongoing at the time of the 51-L accident. Since that time, base heating and plume methodology improvements have continued as part of the overall emphasis on Shuttle design assurance before resuming flight schedule.

Bender, Robert L.

1988-01-01

270

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

SciTech Connect

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)

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

2009-06-15

271

Artificial Intelligence Software Engineering (AISE) model  

NASA Technical Reports Server (NTRS)

The American Institute of Aeronautics and Astronautics has initiated a committee on standards for Artificial Intelligence. Presented are the initial efforts of one of the working groups of that committee. A candidate model is presented for the development life cycle of knowledge based systems (KBSs). The intent is for the model to be used by the aerospace community and eventually be evolved into a standard. The model is rooted in the evolutionary model, borrows from the spiral model, and is embedded in the standard Waterfall model for software development. Its intent is to satisfy the development of both stand-alone and embedded KBSs. The phases of the life cycle are shown and detailed as are the review points that constitute the key milestones throughout the development process. The applicability and strengths of the model are discussed along with areas needing further development and refinement by the aerospace community.

Kiss, Peter A.

1990-01-01

272

Human Modeling for Ground Processing Human Factors Engineering Analysis  

NASA Technical Reports Server (NTRS)

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

Stambolian, Damon B.; Lawrence, Brad A.; Stelges, Katrine S.; Steady, Marie-Jeanne O.; Ridgwell, Lora C.; Mills, Robert E.; Henderson, Gena; Tran, Donald; Barth, Tim

2011-01-01

273

Human Modeling For Ground Processing Human Factors Engineering Analysis  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

274

Teaching Geometry through Dynamic Modeling in Introductory Engineering Graphics.  

ERIC Educational Resources Information Center

Examines how constraint-based 3D modeling can be used as a vehicle for rethinking instructional approaches to engineering design graphics. Focuses on moving from a mode of instruction based on the crafting by students and assessment by instructors of static 2D drawings and 3D models. Suggests that the new approach is better aligned with…

Wiebe, Eric N.; Branoff, Ted J.; Hartman, Nathan W.

2003-01-01

275

Yucca Mountain engineered barrier system corrosion model (EBSCOM)  

Microsoft Academic Search

A revised engineered barrier system model has been developed by the Electric Power Research Institute to predict the time dependence of the failure of the drip shields and waste packages in the proposed Yucca Mountain repository. The revised model is based on new information on various corrosion processes developed by the US Department of Energy and others and for a

F. King; M. Kolar; J. H. Kessler; M. Apted

2008-01-01

276

A Team Building Model for Software Engineering Courses Term Projects  

ERIC Educational Resources Information Center

This paper proposes a new model for team building, which enables teachers to build coherent teams rapidly and fairly for the term projects of software engineering courses. Moreover, the model can also be used to build teams for any type of project, if the team member candidates are students, or if they are inexperienced on a certain subject. The…

Sahin, Yasar Guneri

2011-01-01

277

Modeling score distributions for combining the outputs of search engines  

Microsoft Academic Search

In this paper the score distributions of a number of text search engines are modeled. It is shown empirically that the score distributions on a per query basis may be fitted using an exponential distribution for the set of non-relevant documents and a normal distribution for the set of relevant documents. Experiments show that this model fits TREC-3 and TREC-4

R. Manmatha; Toni M. Rath; Fangfang Feng

2001-01-01

278

QUALITY ENSUREMENT SYSTEM FOR THE DISTANT ENGINEER STUDIES MODEL  

Microsoft Academic Search

In the article there is presented the model of distant education system SPrINT, as incorporated during the distant engineering studies within Warsaw Technical University, using the Internet. There are the basics of education shown as well as the basics of informatical structures incorporated within this model. There has been attention pointed towards the problem of providing the adequate quality for

Marek Zawadzki

279

Three and more dimensional modelling in geo-engineering  

Microsoft Academic Search

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

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

2006-01-01

280

Information modelling in the construction industry: The information engineering approach  

Microsoft Academic Search

Modelling of knowledge in the construction industry is a cumbersome task because of the large amount of data involved and the lack of automated information-modelling tools. Adoption of a method and an automated CASE (Computer-Aided Software Engineering) tool could eliminate many problems encountered in the development of information systems in the construction industry. In particular, this approach may help to

G. F. Aouad; J. A. Kirkhami; P. S. Brandon; F. E. Brown; G. S. Cooper; S. Ford; R. E. Oxman; M. Sarshar; B. Young

1993-01-01

281

Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

282

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

NASA Astrophysics Data System (ADS)

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.

Kisakurek, Sukru Ergin; Ozel, Ahmet

2014-04-01

283

A verification and validation process for model-driven engineering  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

284

A Meta-Analytic Review of Behavior Modeling Training  

Microsoft Academic Search

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.

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

2005-01-01

285

Modeling of the thermomechanical behavior of porous shape memory alloys  

Microsoft Academic Search

Two methods are used in this work to estimate the porous shape memory alloy (SMA) thermomechanical behavior. The porous SMA is assumed to be made of two components, the dense SMA matrix and the pores. An existing rate-independent type constitutive model is employed to describe the matrix behavior. Two contrasting strategies are used to estimate the overall thermomechanical behavior: (1)

Muhammad A. Qidwai; Pavlin B. Entchev; Dimitris C. Lagoudas; Virginia G. DeGiorgi

2001-01-01

286

[Transactional model of suicidal behavior in the elderly].  

PubMed

General theories of suicidology are insufficient to explain the overproportional rate of suicidal behaviour in the elderly. The proposed transactional model represents a bio-psycho-social foundation of suicidal behavior in the elderly. The reciprocal interactions of biological, somatic, psychological and social factors in old age which may enhance suicidal behavior as a mode of problem-solving behavior are discussed. PMID:18286323

Schaller, S

2008-02-01

287

The Garrison Model: An Effective Program for Managing the Behaviors of Students with Behavioral Disorders.  

ERIC Educational Resources Information Center

A description is provided of the Garrison Model, an educational therapeutic program for youth with severe behavior disorders which emphasizes a student's responsibility for choices that are made. The model was developed at the Garrison School, a public alternative day school in Illinois that serves students with severe behavioral disorders. The…

Carr, Valerie G.

288

Enhancing the Behavioral Fidelity of Synthetic Entities with Human Behavior Models.  

National Technical Information Service (NTIS)

Human-behavior models (HBMs) and artificial intelligence systems are called on to fill a wide variety of roles in military simulations. Each of the 'off the shelf' human behavior models available today focuses on a specific area of human cognition and beh...

B. G. Silverman K. O'Brien M. V. Lent P. Probst R. McAlinden

2004-01-01

289

Fatigue behavior of ULTIMETRTM alloy: Experiment and theoretical modeling  

NASA Astrophysics Data System (ADS)

ULTIMETRTM alloy is a commercial Co-26Cr-9Ni (weight percent) superalloy, which possesses excellent resistance to both wear and corrosion. In order to extend the structural applications of this alloy and improve the fundamental understanding of the fatigue damage mechanisms, stress- and strain-controlled fatigue tests were performed at various temperatures and in different environments. The stress- and strain-life data were developed for the structural design and engineering applications of this material. Fractographic studies characterized the crack-initiation and propagation behavior of the alloy. Microstructure evolution during fatigue was revealed by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Specifically, it was found that the metastable face-centered-cubic structure of this alloy in the as-received condition could be transformed into a hexagonal-close-packed structure either under the action of plastic deformation at room temperature, or due to the aging and cyclic deformation at intermediate temperatures. This interesting observation constructed a sound basis for the alloy development. The dominant mechanisms, which control the fatigue behavior of ULTIMET alloy, were characterized. High-speed, high-resolution infrared (IR) thermography, as a non-contact, full-field, and nondestructive technique, was used to characterize the damage during fatigue. The temperature variations during each fatigue cycle, which were due to the thermal-elastic-plastic effect, were observed and related to stress-strain analyses. The temperature evolution during fatigue manifested the cumulative fatigue damage process. A constitutive model was developed to predict thermal and mechanical responses of ULTIMET alloy subjected to cyclic deformation. The predicted cyclic stress-strain responses and temperature variations were found to be in good agreement with the experimental results. In addition, a fatigue life prediction model was developed based on the strain-energy consideration, and the measured temperature could be utilized as an index for fatigue-life prediction.

Jiang, Liang

290

Artificial Intelligence Software Engineering (AISE) Model.  

National Technical Information Service (NTIS)

The American Institute of Aeronautics and Astronautics has initiated a committee on standards for Artificial Intelligence. Presented are the initial efforts of one of the working groups of that committee. A candidate model is presented for the development...

P. A. Kiss

1990-01-01

291

Universal Behavior of a Cyclic Oxidation Model  

NASA Technical Reports Server (NTRS)

A mathematical model has been generated to represent the iterative, discrete growth and spallation processes associated with cyclic oxidation. Parabolic growth kinetics (k(sub p)) over and a constant spall area (F(sub A)) were assumed, with spalling occurring interfacially at the thickest regions of the scale. Although most models require numerical techniques, the regularity and simplicity of this progression permitted an approximation by algebraic expressions. Normalization could now be performed to reflect all parametric effects, and a universal cyclic oxidation response was generated: W(sub u) = 1/2 {3J(sub u)(sup 1/2)+ J(sub u)(sup 3/2)} where W, is weight change normalized by the maximum and J(sub u) is the cycle number normalized by the number to reach maximum. Similarly, the total amount of metal consumed was represented by a single normalized curve. The factor [(S(sub c)-l)(raised dot)sqrt(F(sub A)k(sub p)DELTAt)] was identified as a general figure of merit, where S(sub c) is the mass ratio of oxide to oxygen and DELTAt is the cycle duration. A cyclic oxidation failure map was constructed, in normalized k(sub p)-F(sub A) space, as defined by the locus of points corresponding to a critical amount of metal consumption in a given time. All three constructions describe behavior for every value of growth rate, spall fraction, and cycle duration by means of single curves, but with two branches corresponding to the times before and after steady state is achieved.

Smialek, James L.

2003-01-01

292

Models and metrics for software management and engineering  

NASA Technical Reports Server (NTRS)

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.

Basili, V. R.

1988-01-01

293

Mathematical Modeling in Wound Healing, Bone Regeneration and Tissue Engineering  

Microsoft Academic Search

The processes of wound healing and bone regeneration and problems in tissue engineering have been an active area for mathematical\\u000a modeling in the last decade. Here we review a selection of recent models which aim at deriving strategies for improved healing.\\u000a In wound healing, the models have particularly focused on the inflammatory response in order to improve the healing of

Liesbet Geris; Alf Gerisch; Richard C. Schugart

2010-01-01

294

Global Sensitivity Analysis of Predictor Models in Software Engineering  

Microsoft Academic Search

Predictor models are an important tool in software projects for quality and cost control as well as management. There are various models available that can help the software engineer in decision-making. However, such models are often difficult to apply in practice because of the amount of data needed. Sensitivity analysis offers provides means to rank the input factors w.r.t. their

Stefan Wagner

2007-01-01

295

Multifunctional Collaborative Modeling and Analysis Methods in Engineering Science  

NASA Technical Reports Server (NTRS)

Engineers are challenged to produce better designs in less time and for less cost. Hence, to investigate novel and revolutionary design concepts, accurate, high-fidelity results must be assimilated rapidly into the design, analysis, and simulation process. This assimilation should consider diverse mathematical modeling and multi-discipline interactions necessitated by concepts exploiting advanced materials and structures. Integrated high-fidelity methods with diverse engineering applications provide the enabling technologies to assimilate these high-fidelity, multi-disciplinary results rapidly at an early stage in the design. These integrated methods must be multifunctional, collaborative, and applicable to the general field of engineering science and mechanics. Multifunctional methodologies and analysis procedures are formulated for interfacing diverse subdomain idealizations including multi-fidelity modeling methods and multi-discipline analysis methods. These methods, based on the method of weighted residuals, ensure accurate compatibility of primary and secondary variables across the subdomain interfaces. Methods are developed using diverse mathematical modeling (i.e., finite difference and finite element methods) and multi-fidelity modeling among the subdomains. Several benchmark scalar-field and vector-field problems in engineering science are presented with extensions to multidisciplinary problems. Results for all problems presented are in overall good agreement with the exact analytical solution or the reference numerical solution. Based on the results, the integrated modeling approach using the finite element method for multi-fidelity discretization among the subdomains is identified as most robust. The multiple-method approach is advantageous when interfacing diverse disciplines in which each of the method's strengths are utilized. The multifunctional methodology presented provides an effective mechanism by which domains with diverse idealizations are interfaced. This capability rapidly provides the high-fidelity results needed in the early design phase. Moreover, the capability is applicable to the general field of engineering science and mechanics. Hence, it provides a collaborative capability that accounts for interactions among engineering analysis methods.

Ransom, Jonathan B.; Broduer, Steve (Technical Monitor)

2001-01-01

296

Structure modeling using genetically engineered crosslinking.  

PubMed

Class B G-protein-coupled receptors are exciting drug targets, yet the structure of a complete receptor bound to a peptide agonist has remained elusive. Coin et al. present a model of the receptor CRF1R bound to its native ligand based on partial structures and 44 spatial constraints revealed by new crosslinking approaches. PMID:24315089

Pal, Kuntal; Melcher, Karsten; Xu, H Eric

2013-12-01

297

A Maintenance Model for Clinical Engineering  

Microsoft Academic Search

The numbers presented here for an equipment maintenance model are derived from a mix of soft data and intuition based on experience. They relate best to university hospitals in the 250-400-bed range. They relate better to numbers of devices than number of beds. In summary, they are: 1. Ideal technician workload = 400 to 550 devices. 2. Average technician productivity

George I. Johnston

1985-01-01

298

The Mathematical Modeling of Structural Engineers  

ERIC Educational Resources Information Center

Math-education reformers encourage the incorporation of mathematical modeling activities into K-12 curricula. Many of the purported educational benefits derive from the authenticity of the activities-how well they reflect the everyday and occupational mathematical practices of adults. But a paucity in the literature of observational descriptions…

Gainsburg, Julie

2006-01-01

299

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

PubMed Central

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.

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

2012-01-01

300

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

PubMed

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

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

2012-11-01

301

Genetically engineered mouse models of pancreatic adenocarcinoma.  

PubMed

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of human cancer for which there are no effective therapies. Deep sequencing of PDAC tumors has revealed the presence of a high number of mutations (>50) that affect at least a dozen key signaling pathways. This scenario highlights the urgent need to develop experimental models that faithfully reproduce the natural history of these human tumors in order to understand their biology and to design therapeutic approaches that might effectively interfere with their multiple mutated pathways. Over the last decade, several models, primarily based on the genetic activation of resident KRas oncogenes knocked-in within the endogenous KRas locus have been generated. These models faithfully reproduce the histological lesions that characterize human pancreatic tumors. Decoration of these models with additional mutations, primarily involving tumor suppressor loci known to be also mutated in human PDAC tumors, results in accelerated tumor progression and in the induction of invasive and metastatic malignancies. Mouse PDACs also display a desmoplastic stroma and inflammatory responses that closely resemble those observed in human patients. Interestingly, adult mice appear to be resistant to PDAC development unless the animals undergo pancreatic damage, mainly in the form of acute, chronic or even temporary pancreatitis. In this review, we describe the most representative models available to date and how their detailed characterization is allowing us to understand their cellular origin as well as the events involved in tumor progression. Moreover, their molecular dissection is starting to unveil novel therapeutic strategies that could be translated to the clinic in the very near future. PMID:23506980

Guerra, Carmen; Barbacid, Mariano

2013-04-01

302

Autoignition chemistry in a motored engine: An experimental and kinetic modeling study  

SciTech Connect

Autoignition of isomers of pentane, hexane, and primary reference fuel mixture of n-heptane and iso-octane has been studied experimentally under motored engine conditions and computationally using a detailed chemical kinetic reaction mechanism. Computed and experimental results are compared and used to help understand the chemical factors leading to engine knock in spark-ignited engines. The kinetic model reproduces observed variations in critical compression ratio with fuel molecular size and structure, provides intermediate product species concentrations in good agreement with observations, and gives insights into the kinetic origins of fuel octane sensitivity. Sequential computed engine cycles were found to lead to stable, non-igniting behavior for conditions below a critical compression ratio; to unstable, oscillating but nonigniting behavior in a transition region; and eventually to ignition as the compression ratio is steadily increased. This transition is related to conditions where a negative temperature coefficient of reaction exists, which has a significant influence on octane number and fuel octane sensitivity.

Curran, H.J.; Pitz, W.J.; Westbrook, C.K. [Lawrence Livermore National Lab., CA (United States); Gaffuri, P. [Politecnico Milano, Milan (Italy). Chemical Engineerng Dept.; Leppard, W.R. [General Motors Research Lab., Warren, MI (United States)

1996-02-01

303

Numerical Modeling of Pulse Detonation Rocket Engine Gasdynamics and Performance  

NASA Technical Reports Server (NTRS)

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.

2003-01-01

304

A Simplified Analysis on a Pulse Detonation Engine Model  

NASA Astrophysics Data System (ADS)

The performance of pulse detonation engines was analytically estimated by using a simple model. A pulse detonation engine was modeled as a straight tube. One end of the tube was closed and the other was open, and a detonation wave was ignited at the closed end. One cycle of the pulse-detonation-engine operation was divided into three phases: combustion, exhaust, and filling phases. The combustion and exhaust phases were theoretically analyzed with some simplifications, using the Hugoniot relation for the Chapman-Jouguet detonation wave and flow relations for self-similar rarefaction waves. Based on the simplified theoretical analysis, useful formulas for impulse density per one-cycle operation and time-averaged thrust density were derived.

Endo, Takuma; Fujiwara, Toshi

305

On Behavior Fault Modeling for Combinational Digital Designs  

Microsoft Academic Search

A mechanism is presented to represent failures in complex combinational digital and VLSI designs at a high level, referred to as behavior fault models. The advantages of behavior fault modeling include early estimates of reliability of the design in the design process, reduced CPU time for fault simulation, and results that may be more comprehensive to the high-level architects. Digital

Tapan J. Chakraborty; Sumit Ghosh

1988-01-01

306

A Multivariant model for single crystal shape memory alloy behavior  

Microsoft Academic Search

A general 3-D multivariant model based on thermodynamics and micromechanics for single crystal shape memory alloy (SMA) behavior is presented. This model is based on the habit plane and transformation directions for the variants of martensite in a given material. From this information, the single crystal behavior of the material to temperature and mechanical loads is derived using the concept

Miinshiou Huang; L. C. Brinson

1998-01-01

307

Considerations for characterizing fuels as inputs for fire behavior models  

Microsoft Academic Search

Active crown fires affect forest ecosystem structure and function, and the livelihood of the surrounding human communities. Researchers and managers use simulation models to understand fire behavior and predict fire hazard. Accurate predictions depend on the capacity of simulation models to represent the processes that control fire behavior and on the quality of the data used. The data required to

Sonia A. Hall; Ingrid C. Burke

2006-01-01

308

A behavioral model of ethical and unethical decision making  

Microsoft Academic Search

A model is developed which identifies and describes various factors which affect ethical and unethical behavior in organizations, including a decision-maker's social, government and legal, work, professional and personal environments. The effect of individual decision maker attributes on the decision process is also discussed. The model links these influences with ethical and unethical behavior via the mediating structure of the

Michael Bommer; Clarence Gratto; Jerry Gravander; Mark Tuttle

1987-01-01

309

The Efficacy of a New Model to Explain Exercise Behavior.  

ERIC Educational Resources Information Center

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…

Noland, Melody Powers; And Others

310

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

NASA Astrophysics Data System (ADS)

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.

Casiano, Matthew J.

311

Can health promotion model constructs predict nutritional behavior among diabetic patients?  

PubMed Central

Since, the nutritional behavior is a complicated process in which various factors play the role, this study aimed at specifying the effective factors in nutritional behavior of diabetic patients based on Health Promotion Model. This paper reviews the published articles from 2000 to the beginning of 2012, using the various data banks and search engines such as PubMed, ProQuest, Scopus, Elsevier, and the key words" perceived benefits and barriers, perceived self-efficacy, social support, activity related affect, situational influences, commitment to plan of action, immediate competing demands and diabetes, self-caring and diabetes. Unfavorable self-care situation especially, inappropriate nutritional behavior is related to some effective modifiable factors. Perceived benefits and self-efficacy regarding behaviors play a major role in the nutritional behaviors. Social support especially, spouses’ support has a significant role in this regard. Moreover, there is a reverse relationship between perceived barriers and nutritional self-care. In addition, behavioral feelings, situational influences, commitment to plan of action and immediate competing demands and preferences can also impact and overshadow the nutritional self-care. Following the relationship between constructs of Health Promotion Model and nutritional behavior the constructs of this model can be utilized as the basis for educational intervention among diabetes.

Mohebi, Siamak; Sharifirad, Ghlamreza; Feizi, Avat; Botlani, Saeedeh; Hozori, Mohammad; Azadbakht, Leila

2013-01-01

312

Can health promotion model constructs predict nutritional behavior among diabetic patients?  

PubMed

Since, the nutritional behavior is a complicated process in which various factors play the role, this study aimed at specifying the effective factors in nutritional behavior of diabetic patients based on Health Promotion Model. This paper reviews the published articles from 2000 to the beginning of 2012, using the various data banks and search engines such as PubMed, ProQuest, Scopus, Elsevier, and the key words" perceived benefits and barriers, perceived self-efficacy, social support, activity related affect, situational influences, commitment to plan of action, immediate competing demands and diabetes, self-caring and diabetes. Unfavorable self-care situation especially, inappropriate nutritional behavior is related to some effective modifiable factors. Perceived benefits and self-efficacy regarding behaviors play a major role in the nutritional behaviors. Social support especially, spouses' support has a significant role in this regard. Moreover, there is a reverse relationship between perceived barriers and nutritional self-care. In addition, behavioral feelings, situational influences, commitment to plan of action and immediate competing demands and preferences can also impact and overshadow the nutritional self-care. Following the relationship between constructs of Health Promotion Model and nutritional behavior the constructs of this model can be utilized as the basis for educational intervention among diabetes. PMID:24124436

Mohebi, Siamak; Sharifirad, Ghlamreza; Feizi, Avat; Botlani, Saeedeh; Hozori, Mohammad; Azadbakht, Leila

2013-04-01

313

Engineered Barrier System Degradation, Flow, and Transport Process Model Report  

SciTech Connect

The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

E.L. Hardin

2000-07-17

314

THE KNOWLEDGE MODELLING PARADIGM IN KNOWLEDGE ENGINEERING  

Microsoft Academic Search

models of problem solvingThe mining approach, as exemplified by Mycin [17], a system which diagnosespulmonary infections, considers expert knowledge and rule-based representation asessentially equivalent knowledge acquisition is an interactive transfer of if-thenassociations. This uniform approach to representation was criticised by Clancey[20], who showed that, at least in the case of the Mycins knowledge base, it fails tocapture important conceptual distinctions

ENRICO MOTTA

315

Genetically engineered mouse models and human osteosarcoma  

PubMed Central

Osteosarcoma is the most common form of bone cancer. Pivotal insight into the genes involved in human osteosarcoma has been provided by the study of rare familial cancer predisposition syndromes. Three kindreds stand out as predisposing to the development of osteosarcoma: Li-Fraumeni syndrome, familial retinoblastoma and RecQ helicase disorders, which include Rothmund-Thomson Syndrome in particular. These disorders have highlighted the important roles of P53 and RB respectively, in the development of osteosarcoma. The association of OS with RECQL4 mutations is apparent but the relevance of this to OS is uncertain as mutations in RECQL4 are not found in sporadic OS. Application of the knowledge or mutations of P53 and RB in familial and sporadic OS has enabled the development of tractable, highly penetrant murine models of OS. These models share many of the cardinal features associated with human osteosarcoma including, importantly, a high incidence of spontaneous metastasis. The recent development of these models has been a significant advance for efforts to improve our understanding of the genetics of human OS and, more critically, to provide a high-throughput genetically modifiable platform for preclinical evaluation of new therapeutics.

2012-01-01

316

Modified thermomechanical modeling approach for shape memory alloy behavior  

NASA Astrophysics Data System (ADS)

The Brinson-Lammering constitutive model is modified to account for the nonlinear shape memory alloy behavior. The model is divided into three modules by keeping each of the three parameters of stress, strain and temperature constant. Experiments were conducted with a NiTiCu material to obtain the model constants. The constants were then incorporated in the model and the behavior predicted. A good correlation is obtained between the theory and experiments.

Kamath, G. M.; Dayananda, G. N.; Senthilpriya, R.

2003-10-01

317

GTP-based integral real-3D spatial model for engineering excavation GIS  

Microsoft Academic Search

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

Wu Lixin; Shi Wenzhong

2004-01-01

318

Monitoring and measuring electrochemical behavior of engineering alloys by optical interferometry  

Microsoft Academic Search

In a previous study, an optical corrosion meter was built based on a mathematical model relating to surface and bulk behaviors of metals in aqueous solution. The optical corrosion meter was established based on principles of holographic interferometry for measuring microsurface dissolution, i.e., mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e., corrosion current. The

K. Habib; F. Al-Sabti

2002-01-01

319

Emerging Conceptual Models of Excessive Behaviors  

Microsoft Academic Search

The clinical assessment of a common behavior that disrupts a person’s life only when it becomes excessive is controversial.\\u000a The inclusion of pathological gambling in the Diagnostic and Statistical Manual, Third Edition (DSM-III) in 1980 was one of\\u000a the initial formal attempts to develop diagnostic criteria for this type of behavior. The diagnostic criteria for pathological\\u000a gambling were based on

James Westphal

2007-01-01

320

Lean backstepping design for a jet engine compressor model  

Microsoft Academic Search

Backstepping offers flexibilities not present in other nonlinear design procedures. One of them is the possibility to avoid cancellation of useful nonlinearities. Such cancellations, which are common in feedback linearization designs, require large control effort and cause nonrobustness. As an illustration of a design that avoids cancellations we develop controllers for the Moore-Greitzer model of a jet engine compressor system.

M. Krstic; P. V. Kokotovic

1995-01-01

321

Bayesian Analysis of Empirical Software Engineering Cost Models  

Microsoft Academic Search

1. Abstract To date many software engineering cost models have been developed to predict the cost, schedule and quality of the software under development. But, the rapidly changing nature of software development ha s made it extremely difficult to develop empirical mo dels that continue to yield high prediction accurac ies. Software development costs continue to increase and practitioners continually

Sunita Chulani; Barry W. Boehm; Bert Steece

1999-01-01

322

A combustion kinetic model for estimating diesel engine NOx emissions  

Microsoft Academic Search

A phenomenological combustion model, which considers the space and time evolutions of a reacting diesel fuel jet, has been developed in order to estimate the instantaneous NOx concentration in a diesel engine cylinder from the start of the injection until the exhaust valve opening. The total injected fuel mass has been divided into different fuel packages, through the fuel injection

J. J. Hernandez; M. Lapuerta; J. Perez-Collado

2006-01-01

323

How the Kano model contributes to Kansei engineering in services  

Microsoft Academic Search

Recent studies show that products and services hold great appeal if they are attractively designed to elicit emotional feelings from customers. Kansei engineering (KE) has good potential to provide a competitive advantage to those able to read and translate customer affect and emotion in actual product and services. This study introduces an integrative framework of the Kano model and KE,

Markus Hartono; Tan Kay Chuan

2011-01-01

324

Ignition of Hydrogen Balloons by Model-Rocket-Engine Igniters  

NASA Astrophysics Data System (ADS)

An alternative method for initiating the explosion of hydrogen-filled balloons is presented. Inexpensive model-rocket-engine igniters connected to a battery provide a safe method for the remote ignition of these balloons. The demonstration provides a novel alternative to using a wick on a pole as the source of ignition and is particularly applicable to chemistry "magic shows".

Hartman, Nicholas T.

2003-07-01

325

COLDSTART ENGINE COMBUSTION MODELLING TO CONTROL HYDROCARBON EMISSIONS  

Microsoft Academic Search

Due to the large contribution of the coldstart process to unburned hydrocarbon emissions of an internal combustion engine during FTP cycle tests, we take a new look at the production of hydrocarbons inside the combustion chamber during coldstart. To this end a model is developed which predicts the exhaust port hydrocarbon concentration, exhaust gas temperature and equivalence ratio based on

Byron T. Shaw II; J. Karl Hedrick

326

A comprehensive combustion model for biodiesel-fueled engine simulations  

NASA Astrophysics Data System (ADS)

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.

Brakora, Jessica L.

327

Detailed Chemical Kinetic Modeling of Surrogate Fuels for Gasoline and Application to an HCCI Engine  

SciTech Connect

Gasoline consists of many different classes of hydrocarbons, such as paraffins, olefins, aromatics, and cycloalkanes. In this study, a surrogate gasoline reaction mechanism is developed, and it has one representative fuel constituent from each of these classes. These selected constituents are iso-octane, n-heptane, 1-pentene, toluene, and methyl-cyclohexane. The mechanism was developed in a step-wise fashion, adding submechanisms to treat each fuel component. Reactions important for low temperature oxidation (<1000K) and cross-reactions among different fuels are incorporated into the mechanism. The mechanism consists of 1214 species and 5401 reactions. A single-zone engine model is used to evaluate how well the mechanism captures autoignition behavior for conditions corresponding to homogeneous charge compression ignition (HCCI) engine operation. Experimental data are available for both how the combustion phasing changes with fueling at a constant intake temperature, and also how the intake temperature has to be changed with pressure in order to maintain combustion phasing for a fixed equivalence ratio. Three different surrogate fuel mixtures are used for the modeling. Predictions are in reasonably good agreement with the engine data. In addition, the heat release rate is calculated and compared to the data from experiments. The model predicts less low-temperature heat release than that measured. It is found that the low temperature heat-release rate depends strongly on engine speed, reactions of RO{sub 2}+HO{sub 2}, fuel composition, and pressure boost.

Naik, C V; Pitz, W J; Sj?berg, M; Dec, J E; Orme, J; Curran, H J; Simmie, J M; Westbrook, C K

2005-01-07

328

Modeling Spitsbergen fjords by hydrodynamic MIKE engine.  

NASA Astrophysics Data System (ADS)

Two Svalbard's fjords - Hornsund (on the western side of the most southern part of Spitsbergen island) and Kongsfjorden (also on the western side of Spitsbergen island, but in the northern part) are quite different - the first one is "cold" and second one is "warm". It is obvious that both of them are under influence of West Spitsbergen Current (WSC), which curry out warm Atlantic water and cold East Spitsbergen Current detaches Hornsund. But there is also freshwater stored in Spitsbergen glaciers that have strong influence on local hydrology and physical fjord conditions. Both, local and shelf conditions have impact on state of the fjord and there is no answer which one is the most important in each fjord. Modeling could help to solve this problem - MIKE 3D model has been implemented for both fjords. Mesh-grid of the each fjord has been extended for covering shelf area. External forces like tides, velocities at the boundary and atmospheric forces together with sources of cold and dens fresh water in the fjords will give reliable representation of physical conditions in Hornsund and Kongsfjorden. Calculations of balances between cold fresh water and warm and salt will provide additional information that could help to answer the main question of the GAME (Growing of the Arctic Marine Ecosystem) project - what is the reaction of physically controlled Arctic marine ecosystem to temperature rise.

Kosecki, Szymon; Przyborska, Anna; Jakacki, Jaromir

2013-04-01

329

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

SciTech Connect

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.

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

2011-01-20

330

Requirements engineering for cross-sectional information chain models  

PubMed Central

Despite the wealth of literature on requirements engineering, little is known about engineering very generic, innovative and emerging requirements, such as those for cross-sectional information chains. The IKM health project aims at building information chain reference models for the care of patients with chronic wounds, cancer-related pain and back pain. Our question therefore was how to appropriately capture information and process requirements that are both generally applicable and practically useful. To this end, we started with recommendations from clinical guidelines and put them up for discussion in Delphi surveys and expert interviews. Despite the heterogeneity we encountered in all three methods, it was possible to obtain requirements suitable for building reference models. We evaluated three modelling languages and then chose to write the models in UML (class and activity diagrams). On the basis of the current project results, the pros and cons of our approach are discussed.

Hubner, U; Cruel, E; Gok, M; Garthaus, M; Zimansky, M; Remmers, H; Rienhoff, O

2012-01-01

331

Creep-Rupture Behavior of Candidate Stirling Engine Iron Superalloys in High-Pressure Hydrogen. Volume II. Hydrogen Creep-Rupture Behavior.  

National Technical Information Service (NTIS)

The creep-rupture behavior of nine iron-base and one cobalt-base candidate Stirling engine alloys was evaluated at 650 to 925 exp 0 C in 15 MPa H sub 2 and air. The test alloys included six wrought alloys for tube application (CG-27, N-155, 19-9DL, 12 RN7...

S. Bhattacharyya W. Peterman C. Hales

1984-01-01

332

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

333

Prioritization of engineering support requests and advanced technology projects using decision support and industrial engineering models  

NASA Technical Reports Server (NTRS)

The evaluation and prioritization of Engineering Support Requests (ESR's) is a particularly difficult task at the Kennedy Space Center (KSC) -- Shuttle Project Engineering Office. This difficulty is due to the complexities inherent in the evaluation process and the lack of structured information. The evaluation process must consider a multitude of relevant pieces of information concerning Safety, Supportability, O&M Cost Savings, Process Enhancement, Reliability, and Implementation. Various analytical and normative models developed over the past have helped decision makers at KSC utilize large volumes of information in the evaluation of ESR's. The purpose of this project is to build on the existing methodologies and develop a multiple criteria decision support system that captures the decision maker's beliefs through a series of sequential, rational, and analytical processes. The model utilizes the Analytic Hierarchy Process (AHP), subjective probabilities, the entropy concept, and Maximize Agreement Heuristic (MAH) to enhance the decision maker's intuition in evaluating a set of ESR's.

Tavana, Madjid

1995-01-01

334

TVC actuator model. [for the space shuttle main engine  

NASA Technical Reports Server (NTRS)

A prototype Space Shuttle Main Engine (SSME) Thrust Vector Control (TVC) Actuator analog model was successfully completed. The prototype, mounted on five printed circuit (PC) boards, was delivered to NASA, checked out and tested using a modular replacement technique on an analog computer. In all cases, the prototype model performed within the recording techniques of the analog computer which is well within the tolerances of the specifications.

Baslock, R. W.

1977-01-01

335

Turbulent entrainment model for spark-ignition engine combustion  

Microsoft Academic Search

A turbulent entrainment model for the turbulent combustion process in spark-ignition engines is described. The model uses the basic quantities of turbulent flow, i.e., the integral length scale, micro length scale, and turbulent intensity. The characteristic reaction time for a large eddy tau was calculated using the characteristic reaction time tau\\/sub c\\/ for the microscale, lambda\\/S\\/sub l\\/, where S\\/sub l\\/

R. J. Tabaczynski; C. R. Ferguson; K. Radhakrishnan

1977-01-01

336

Modeling Business Strategy in E-Business Systems Requirements Engineering  

Microsoft Academic Search

This paper proposes a conceptual modeling approach for require- ments engineering for e-business systems that enables alignment of systems re- quirements with business strategy. Jackson problem diagrams and goal model- ing are employed to capture business strategy. As a means of linking abstract, high-level business requirements to low-level system requirements, we leverage the paradigm of projection in both problem diagrams

Steven J. Bleistein; Karl Cox; June M. Verner

2004-01-01

337

Soot Emission Modelization of a Diesel Engine from Experimental Data  

Microsoft Academic Search

\\u000a In recent years particulate diesel engines emission analysis has become crucial. Indeed the particulate modelling and experimental\\u000a analysis has been modest, mostly because the lack of adequate measurement instruments and the greater focus on the efficiency.\\u000a Today many instruments can measure accurately the soot emissions and numerous models are in developing. This paper shows the\\u000a experimental results of a soot

Enrico Bocci; Lorenzo Rambaldi

338

Calibrating Bayesian Network Representations of Social-Behavioral Models  

SciTech Connect

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.

Whitney, Paul D.; Walsh, Stephen J.

2010-04-08

339

A risk analysis model in concurrent engineering product development.  

PubMed

Concurrent engineering has been widely accepted as a viable strategy for companies to reduce time to market and achieve overall cost savings. This article analyzes various risks and challenges in product development under the concurrent engineering environment. A three-dimensional early warning approach for product development risk management is proposed by integrating graphical evaluation and review technique (GERT) and failure modes and effects analysis (FMEA). Simulation models are created to solve our proposed concurrent engineering product development risk management model. Solutions lead to identification of key risk controlling points. This article demonstrates the value of our approach to risk analysis as a means to monitor various risks typical in the manufacturing sector. This article has three main contributions. First, we establish a conceptual framework to classify various risks in concurrent engineering (CE) product development (PD). Second, we propose use of existing quantitative approaches for PD risk analysis purposes: GERT, FMEA, and product database management (PDM). Based on quantitative tools, we create our approach for risk management of CE PD and discuss solutions of the models. Third, we demonstrate the value of applying our approach using data from a typical Chinese motor company. PMID:20840492

Wu, Desheng Dash; Kefan, Xie; Gang, Chen; Ping, Gui

2010-09-01

340

A behavioral model of infant sleep disturbance.  

PubMed Central

Chronic sleep disturbance, such as bed refusal, sleep-onset delay, and night waking with crying, affects 15% to 35% of preschool children. Biological factors, particularly arousals associated with recurrent episodes of rapid-eye-movement sleep, render infants vulnerable to repeated awakenings. Parental failure to establish appropriate stimulus control of sleep-related behaviors and parent-mediated contingencies of reinforcement for sleep-incompatible behaviors may shape and maintain infant sleep disturbance. Treatment and prevention strategies are discussed, and research needs are identified.

Blampied, N M; France, K G

1993-01-01

341

Creep-rupture behavior of six candidate Stirling engine superalloys tested in air  

SciTech Connect

The creep-rupture behavior of six candidate Stirling engine iron-base superalloys was determined in air. The alloys included four wrought alloys (A-286, Alloy 800H, N-155, and 19-9DL) and two cast alloys (CRM-6D and XF-818). The specimens were tested to rupture for times up to 3000 h at 650 to 925 C. Rupture life, t(r) minimum creep rate, and time to 1-percent creep strain t(0.01) were statistically analyzed as a function of stress and temperature. Estimated stress levels at different temperatures to obtain 3500 h t(r) and t(0.01) lives were determined. These data will be compared with similar data being obtained under 15 MPa hydrogen. 19 references.

Bhattacharyya, S.

1984-01-01

342

Creep-rupture behavior of six candidate Stirling engine superalloys tested in air  

NASA Technical Reports Server (NTRS)

The creep-rupture behavior of six candidate Stirling engine iron-base superalloys was determined in air. The alloys included four wrought alloys (A-286, Alloy 800H, N-155, and 19-9DL) and two cast alloys (CRM-6D and XF-818). The specimens were tested to rupture for times up to 3000 h at 650 to 925 C. Rupture life, t(r) minimum creep rate, and time to 1-percent creep strain t(0.01) were statistically analyzed as a function of stress and temperature. Estimated stress levels at different temperatures to obtain 3500 h t(r) and t(0.01) lives were determined. These data will be compared with similar data being obtained under 15 MPa hydrogen.

Bhattacharyya, S.

1984-01-01

343

Modeling Driver Behavior as Sequential Risk-Taking Task  

Microsoft Academic Search

Acceleration models are at the core of operational driving behaviors and include car-following models that capture interactions between a lead and following vehicles. The main assumption in these models is that the behavior of the following vehicle (e.g., change in acceleration) is related directly to a stimulus observed or perceived by the driver, defined relative to the lead vehicle (e.g.,

Samer H. Hamdar; Martin Treiber; Hani S. Mahmassani; Arne Kesting

2008-01-01

344

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

PubMed Central

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.

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

2014-01-01

345

A data-driven approach to reverse engineering customer engagement models: towards functional constructs.  

PubMed

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

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

2014-01-01

346

Kinetic Modeling of Gasoline Surrogate Components and Mixtures under Engine Conditions  

SciTech Connect

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.

Mehl, M; Pitz, W J; Westbrook, C K; Curran, H J

2010-01-11

347

Monopropellant hydrazine resistoject: Engineering model fabrication and test task  

NASA Technical Reports Server (NTRS)

The monopropellant hydrazine resistojet, termed the electrothermal hydrazine thruster (EHT) by TRW systems, thermally decomposes anhydrous hydrazine propellant to produce a high-temperature, low-molecular-weight gas for expulsion through a propulsive nozzle. The EHT developed for this program required about 3-5 watts of electrical power and produced 0.020 to 0.070 pound of thrust over the inlet pressure range of 100 to 400 psia. The thruster was designed for both pulsed and steady state operation. A summary of the GSFC original requirements and GSFC modified requirements, and the performance of the engineering model EHT is given. The experimental program leading to the engineering model EHT design, modifications necessary to achieve the required thruster life capability, and the results of the life test prgram. Other facets of the program, including analyses, preliminary design, specifications, data correlation, and recommendations for a flight model are discussed.

Murch, C. K.

1973-01-01

348

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

PubMed

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

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

2011-10-01

349

Towards a Model of Collaborative Information Behavior  

Microsoft Academic Search

The research area of Collaborative Information Behavior (CIB) has received increased interest in recent years. Various studies conducted within organizational as well as non-organizational settings have provided us with many key insights about CIB. However, the research area is still relatively young and is at a pre- paradigmatic stage. Although there are a growing number of CIB-related studies, we still

Arvind Karunakaran; Patricia Ruma Spence; Madhu C. Reddy

350

Modeling potentiometric titration behavior of glauconite  

Microsoft Academic Search

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

Weiping Lu; Edward H. Smith

1996-01-01

351

Steel Shear Walls, Behavior, Modeling and Design  

Microsoft Academic Search

In recent years steel shear walls have become one of the more efficient lateral load resisting systems in tall buildings. The basic steel shear wall system consists of a steel plate welded to boundary steel columns and boundary steel beams. In some cases the boundary columns have been concrete-filled steel tubes. Seismic behavior of steel shear wall systems during actual

Abolhassan Astaneh-Asl; Abolhassan

2008-01-01

352

Quantum four-stroke heat engine: thermodynamic observables in a model with intrinsic friction.  

PubMed

The fundamentals of a quantum heat engine are derived from first principles. The study is based on the equation of motion of a minimum set of operators, which is then used to define the state of the system. The relation between the quantum framework and the thermodynamical observables is examined. A four-stroke heat engine model with a coupled two-level system as a working fluid is used to explore the fundamental relations. In the model used, the internal Hamiltonian does not commute with the external control field, which defines the two adiabatic branches. Heat is transferred to the working fluid by coupling to hot and cold reservoirs under constant field values. Explicit quantum equations of motion for the relevant observables are derived on all branches. The dynamics on the heat transfer constant field branches is solved in closed form. On the adiabats, a general numerical solution is used and compared with a particular analytic solution. These solutions are combined to construct the cycle of operation. The engine is then analyzed in terms of the frequency-entropy and entropy-temperature graphs. The irreversible nature of the engine is the result of finite heat transfer rates and frictionlike behavior due to noncommutability of the internal and external Hamiltonians. PMID:12935194

Feldmann, Tova; Kosloff, Ronnie

2003-07-01

353

Intelligent Computing for the Management of Changes in Industrial Engineering Modeling Processes  

Microsoft Academic Search

Advancements in engineering modeling have changed work of engineers during the last two decades. Sophisticated descriptions store information about shape oriented engineering objects and their relationships. Boundary representations of form features constitute shape models. Rules and checks have replaced simple data form of shape model entity attributes. This change of modeling facilitates a next step towards application of computer intelligence

László Horváth; Imre J. Rudas; János F. Bitó; Gerhard P. Hancke

2005-01-01

354

Human Performance Models of Pilot Behavior  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

355

Applying the Language of Behavioral Models to Teaching Acts.  

ERIC Educational Resources Information Center

This paper illustrates how behavioral models which embody a critical language can be used to describe and predict some categories of classroom events. It defines teaching-learning as a set of events which are mediated primarily by a person, the consequence of which is change in behavior of a second person. A language for describing this phenomenon…

McDonald, F. J.

356

Generative modelling of regulated dynamical behavior in cultured neuronal networks  

Microsoft Academic Search

The spontaneous activity of cultured in vitro neuronal networks exhibits rich dynamical behavior. Despite the artificial manner of their construction, the networks’ activity includes features which seemingly reflect the action of underlying regulating mechanism rather than arbitrary causes and effects. Here, we study the cultured networks dynamical behavior utilizing a generative modelling approach. The idea is to include the minimal

Vladislav Volman; Itay Baruchi; Erez Persi; Eshel Ben-Jacob

2004-01-01

357

Internet Users Behavior Model: A Structural Equation Approach  

Microsoft Academic Search

The study highlights the factors that encourage Internet users' behavior of 105 Bruneian business managers by using survey methodology. The study modifies the existing Technology Acceptance Model to describe the usage behavior. Perceived Usefulness was modified with perceived near term usefulness and perceived long-term usefulness and was hypothesized with experience with the Internet and facilitating condition at the organizational level.

Afzaal H. Seyala; Mohd Noah; A. Rahmana

358

Impulsivity and Modeling in Normal and Behavior Disordered Adolescents.  

ERIC Educational Resources Information Center

To ascertain whether impulsive responding in behavior disordered adolescents is amenable to change, 15-year-old normal and "acting-out" behavior disordered adolescents participated in an experiment designed to alter Kagan's Matching Familiar Figures Test (MFF) scores through a modeling psychoeducational procedure. No significant differences…

Brown, Ronald T.; Quay, Lorene C.

359

Behavior modeling and forensics for multimedia social networks  

Microsoft Academic Search

Factors influencing human behavior have seldom appeared in signal processing disciplines. Therefore, the goals of the article are to illustrate why human factors are important, identify emerging issues strongly related to signal processing, and to demonstrate that signal processing can be effectively used to model, analyze, and perform behavior forensics for multimedia social networks. Since media security and content protection

H. Vicky Zhao; W. Sabrina Lin; K. J. Ray Liu

2009-01-01

360

Optimization of data access in behavioral modelling of computer animation  

Microsoft Academic Search

Behavioral modelling encompasses a number of processing requirements. These include the processing of any mental attributes, the perceived environment and the actions to be performed. These increase the load of any processor running the simulation. If there are many such behavioral modules in an animation, the playback of the scene becomes non-interactive. A simple way to improve playback speed is

Kee Ping Ho; Eng Chong Tan; Kok Cheong Wong

2001-01-01

361

Engineering-Level Model Atmospheres for Titan & Neptune  

NASA Technical Reports Server (NTRS)

Engineering-level atmospheric models for Titan and Neptune have been developed for use in NASA s systems analysis studies of aerocapture applications in missions to the outer planets. Analogous to highly successful Global Reference Atmospheric Models for Earth (GRAM, Justus et al., 2000) and Mars (Mars-GRAM, Justus and Johnson, 2001, Justus et al., 2002) the new models are called Titan-GRAM and Neptune-GRAM. Like GRAM and Mars-GRAM, an important feature of Titan-GRAM and Neptune-GRAM is their ability to simulate quasi-random perturbations for Monte- Carlo analyses in developing guidance, navigation and control algorithms, and for thermal systems design.

Justus, C. G.; Johnson, D. L.

2003-01-01

362

Numerical Modeling of Drying Residual RP-1 in Rocket Engines  

NASA Technical Reports Server (NTRS)

When a Rocket Engine shuts down under a fuel rich environment, a significant amount of unburned RP-1 is trapped In the engine. It is necessary to clean the residual RP-1 prior to subsequent firing to avoid any explosion due to detonation. The conventional method is to dry RP-1 with inert gas such as Nitrogen or Helium. It is difficult to estimate the drying time unless the engine is adequately equipped with instruments to measure the trace of RP-1 during the drying process. Such instrumentation in flight hardware is often impractical and costly. On the other hand numerical modeling of the drying process can provide a good insight for a satisfactory operation of the process. A numerical model can provide answer to questions such as a) how long it takes to dry, b) which fluid is a better dryer for RP-1, c) how to reduce drying time etc. The purpose of the present paper is to describe a numerical model of drying RP-1 trapped in a cavity with flowing nitrogen or helium. The numerical model assumes one dimensional flow of drying fluid in contact with liquid pool of RP-1. An evaporative mass transfer takes place across the contact surface.

Majumdar, Alok; Polsgrove, Robert; Tiller, Bruce; Rodriquez, Pete (Technical Monitor)

2000-01-01

363

Tissue engineering of bone: an ectopic rat model.  

PubMed

Tissue engineering is attempting to recreate the complexity of living tissues. In order to test a variety of scaffolds or cells that are constantly being developed, we describe here a model where tissue engineering of bone in a non-osseous environment at subcutaneous thoracic site of DA rats generates. In this model, cell - matix interactions can mimic the normal cascade of bone development into a well organized ossicle like structure including newly formed bone marrow, during 3-4 weeks. Histogenesis of cartilage, bone and bone marrow is closely related to changes in molecular expression of essential early transcriptional regulators of osteoblast differentiation. We tested different organic, anorganic and polymeric scaffolds and their interaction with mesenchymal stem cells present in fresh bone marrow. In another series of experiments we tested mesenchymal populations separated from cultures of calvaria and periosteum for their ability to form bone in the same rat model. It is concluded that this in vivo model is very potent in studying cell-scaffold interactions affecting the temporal and spatial tissue engineering of bone. PMID:21196357

Binderman, Itzhak; Yaffe, Avinoam; Zohar, Ron; Benayahu, Dafna; Bahar, Hila

2011-01-01

364

Long Term Oxidation of Model and Engineering TiAl Alloys  

SciTech Connect

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.

Locci, IE

2001-08-24

365

Modeling power diode by combining the behavioral and the physical model  

Microsoft Academic Search

This paper presents an approach of implementing the dynamic multi-resolution power diode model in the virtual test bed (VTB), a platform for complex system simulation and prototyping. The new model is a combination of the behavioral model and the physical model. The behavioral model is based upon the widely used Shockley equation; its advantages are simplicity and fast simulation speed,

Haigang Wu; Roger Dougal; Chunlian Jin

2005-01-01

366

Process modelling and model reduction for chemical engineering applications  

Microsoft Academic Search

Process systems & models have structural and behavioural features, which can be exploited for model reduction. A reduction approach is introduced addressing both features, while systematically going through the usual model development steps. Thus, the reduction is not applied only at mathematical and numerical level, but at physical and systemic level as well. The benefit is that the model reduction

Bogdan Dorneanu; Johan Grievink; Costin S. Bildea

2011-01-01

367

Adaptive human behavior in epidemiological models  

Microsoft Academic Search

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.

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

2011-01-01

368

The New NASA Orbital Debris Engineering Model ORDEM2000  

NASA Technical Reports Server (NTRS)

The NASA Orbital Debris Program Office at Johnson Space Center has developed a new computer-based orbital debris engineering model, ORDEM2000, which describes the orbital debris environment in the low Earth orbit region between 200 and 2000 km altitude. The model is appropriate for those engineering solutions requiring knowledge and estimates of the orbital debris environment (debris spatial density, flux, etc.). ORDEM2000 can also be used as a benchmark for ground-based debris measurements and observations. We incorporated a large set of observational data, covering the object size range from 10 mm to 10 m, into the ORDEM2000 debris database, utilizing a maximum likelihood estimator to convert observations into debris population probability distribution functions. These functions then form the basis of debris populations. We developed a finite element model to process the debris populations to form the debris environment. A more capable input and output structure and a user-friendly graphical user interface are also implemented in the model. ORDEM2000 has been subjected to a significant verification and validation effort. This document describes ORDEM2000, which supersedes the previous model, ORDEM96. The availability of new sensor and in situ data, as well as new analytical techniques, has enabled the construction of this new model. Section 1 describes the general requirements and scope of an engineering model. Data analyses and the theoretical formulation of the model are described in Sections 2 and 3. Section 4 describes the verification and validation effort and the sensitivity and uncertainty analyses. Finally, Section 5 describes the graphical user interface, software installation, and test cases for the user.

Liou, Jer-Chyi; Matney, Mark J.; Anz-Meador, Phillip D.; Kessler, Donald; Jansen, Mark; Theall, Jeffery R.

2002-01-01

369

Advanced modeling of active control of fan noise for ultra high bypass turbofan engines  

NASA Astrophysics Data System (ADS)

An advanced model of active control of fan noise for ultra high bypass turbofan engines has been developed. This model is based on a boundary integral equation method and simulates the propagation, radiation and control of the noise generated by an engine fan surrounded by a duct of finite length and cylindrical shape, placed in a uniform flow. Control sources, modeled by point monopoles placed along the wall of the engine inlet or outlet duct, inject anti-noise into the duct to destructively interfere with the sound field generated by the fan. The duct inner wall can be lined or rigid. Unlike current methods, reflection from the duct openings is taken into account, as well as the presence of the evanescent modes. Forward, as well as backward (i.e., from the rear of the engine), external radiation is computed. The development of analytical expressions for the sound field resulting from both the fan loading noise and the control sources is presented. Two fan models are described. The first model uses spinning line sources with radially distributed strength to model the loading force that the fan blades exert on the medium. The second model uses radial arrays of spinning point dipoles to simulate the generation of fan modes of specific modal amplitudes. It is shown that these fan models can provide a reasonable approximation of actual engine fan noise in the instance when the modal amplitude of the propagating modes or the loading force distribution on the fan blades, is known. Sample cases of active noise control are performed to demonstrate the feasibility of the model. The results from these tests indicate that this model (1)is conducive to more realistic studies of active control of fan noise on ultra high bypass turbofan engines because it accounts for the presence of evanescent modes and for interference between inlet and outlet radiation, which were shown to have some impact on the performance of the active control system; (2)is very useful because it allows monitoring of any region of the acoustic field; (3)is computationally fast, and therefore suitable to conduct parametric studies. Finally, the potential that active noise control techniques have for reducing fan noise on an ultra high bypass turbofan engine is investigated. Feedforward control algorithms are simulated. Pure active control techniques, as well as hybrid (active/passive) control techniques, are studied. It is demonstrated that active noise control has the potential to reduce substantially, and over a relatively large far field sector, the fan noise radiated by an ultra high bypass turbofan engine. It is also shown that a hybrid control system can achieve significantly better levels of noise reduction than a pure passive or pure active control system, and that its optimum solution is more robust than the one achieved with a pure active control system. The model has shown to realistically predict engine acoustic behavior and is thus likely to be a very useful tool for designing active noise control systems for ultra high bypass turbofan engines.

Hutcheson, Florence Vanel

1999-11-01

370

Behavior Change Support Systems: A Research Model and Agenda  

NASA Astrophysics Data System (ADS)

This article introduces the concept of a behavior change support system and suggests it as a key construct for research on persuasive systems design, technologies, and applications. Key concepts for behavior change support systems are defined and a research agenda for them is outlined. The article suggests that a change in complying, a behavior change, and an attitude change (C-, B- or A-Change) constitute the archetypes of a behavioral change. Change in itself is either of a forming, altering or reinforcing outcome (F-, A- or R-Outcome). This research model will become helpful in researching and designing persuasive technology.

Oinas-Kukkonen, Harri

371

Validation Methodology for Human Behavior Representation Models.  

National Technical Information Service (NTIS)

The Department of Defense relies Heavily on mathematical models and computer simulations to analyze and acquire new weapon systems. Models and simulations help decision-makers understand the differences between systems and provide insights into the implic...

S. R. Goerger M. L. McGinnis R. P. Darken

2005-01-01

372

A catastrophe-theory model for simulating behavioral accidents  

SciTech Connect

Behavioral accidents are a particular type of accident. They are caused by inappropriate individual behaviors and faulty reactions. Catastrophe theory is a means for mathematically modeling the dynamic processes that underlie behavioral accidents. Based on a comprehensive data base of mining accidents, a computerized catastrophe model has been developed by the Bureau of Mines. This model systematically links individual psychological, group behavioral, and mine environmental variables with other accident causing factors. It answers several longstanding questions about why some normally safe behaving persons may spontaneously engage in unsafe acts that have high risks of serious injury. Field tests with the model indicate that it has three imnportant uses: it can be used as a effective training aid for increasing employee safety consciousness; it can be used as a management laboratory for testing decision alternatives and policies; and it can be used to help design the most effective work teams.

Souder, W.E.

1988-01-01

373

A simple generative model of collective online behavior.  

PubMed

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

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

2014-07-22

374

Aspect-Oriented Model-Driven Software Product Line Engineering  

NASA Astrophysics Data System (ADS)

Software product line engineering aims to reduce development time, effort, cost, and complexity by taking advantage of the commonality within a portfolio of similar products. The effectiveness of a software product line approach directly depends on how well feature variability within the portfolio is implemented and managed throughout the development lifecycle, from early analysis through maintenance and evolution. This article presents an approach that facilitates variability implementation, management, and tracing by integrating model-driven and aspect-oriented software development. Features are separated in models and composed of aspect-oriented composition techniques on model level. Model transformations support the transition from problem to solution space models. Aspect-oriented techniques enable the explicit expression and modularization of variability on model, template, and code level. The presented concepts are illustrated with a case study of a home automation system.

Groher, Iris; Voelter, Markus

375

Organization of kerosene combustion in a model hypersonic ramjet engine  

Microsoft Academic Search

We present the results of experiments on the organization of kerosene combustion in a two-dimensional model of a hypersonic ramjet engine in conditions of external blow-out by a flow with parameters M8=6, p8*=(53–55)·105 Pa, T8*=1500 K. We studied the operation of some variants of a rectangular combustion chamber with different kerosine injectors and stabilizing elements when hydrogen is used as

V. A. Vinogradov; S. A. Kobyzhskii; M. D. Petrov

1992-01-01

376

Engineering model testing for SGLI IRS especially TIR radiometric data  

NASA Astrophysics Data System (ADS)

The Second-generation Global Imager (SGLI) on the Global Change Observation Mission (GCOM) is a multi-band optical imaging radiometer in the wavelength range from near-UV to thermal infrared. SGLI will provide high accuracy measurements of Ocean, Atmosphere, Land and Cryosphere. SGLI project is in the last phase of Engineering Model (EM) test to verify the overall sensor system performances. This paper presents outline of SGLI and EM test results, especially about IRS.

Hosokawa, Tamiki; Tanaka, Kazuhiro; Okamura, Yoshihiko; Amano, Takahiro; Hiramatsu, Masaru

2012-11-01

377

Thermal barrier coating life modeling in aircraft gas turbine engines  

Microsoft Academic Search

Analytical models for predicting ceramic thermal barrier coating (TBC) spalling life in aircraft gas tur-bine engines are presented. Electron beam\\/physical vapor-deposited and plasma-sprayed TBC systems are discussed. An overview of the following TBC spalling mechanisms is presented: (1) metal oxidation at the ceramic\\/metal interface, (2) ceramic\\/metal interface stresses caused by radius of curvature and inter-face roughness, (3) material properties and

D. M. Nissley

1997-01-01

378

Using a Phenomenological Computer Model to Investigate Advanced Combustion Trajectories in a CIDI Engine  

SciTech Connect

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.

Gao, Zhiming [ORNL; Wagner, Robert M [ORNL; Sluder, Scott [ORNL; Daw, C Stuart [ORNL; Green Jr, Johney Boyd [ORNL

2011-01-01

379

Visualization observation of onset and damping behaviors in a traveling-wave thermoacoustic engine by infrared imaging  

Microsoft Academic Search

To explore the effects of Gedeon streaming on the onset and damping behaviors, infrared imaging is applied for the first time in a traveling-wave thermoacoustic engine to observe the temperature evolution of the regenerator. Under conditions of with and without Gedeon streaming, the temperature distribution differences of the regenerator in the onset and damping processes are compared and analyzed. Based

Bo Wang; Limin Qiu; Daming Sun; Kai Wang; Weijuan Yang; Junhu Zhou

2011-01-01

380

Workflow Mining Application to Ambient Intelligence Behavior Modeling  

Microsoft Academic Search

The handmade human behavior modeling requires too many human resources and for too long a time. In addition, the final result\\u000a does probably not reflect the current status of the person due to the influence of time. The use on Workflow Mining techniques\\u000a to infer human behavior models from past executions of actions can be a solution to this problem.

Carlos Fernández; Juan Pablo Lázaro; José-miguel Benedí

2009-01-01

381

A Material Model for the Cyclic Behavior of Nitinol  

Microsoft Academic Search

The uniaxial behavior of Nitinol in different forms and at different temperatures has been well documented in the literature.\\u000a Mathematical models for the three-dimensional behavior of this class of materials, covering superelasticity, plasticity, and\\u000a shape memory effects have been previously developed. Phenomenological models embedded in FEA analysis are part of common practice\\u000a today in the development of devices made out

Nuno Rebelo; Achim Zipse; Martin Schlun; Gael Dreher

2011-01-01

382

Modeling Life-Like Behaviors of An Animated Virtual Tutor  

Microsoft Academic Search

The aim of this study is to understand and model the coordinated verbal and nonverbal behaviors that occur during one-on-one tutoring of students by expert reading tutors, and to develop learning tools in which a virtual tutor-a lifelike 3-D computer character-models these coordinated behaviors, and thus behaves more like an effective and sensitive human tutor. We hypothesize, and test the

Jie Yan

2009-01-01

383

Advances in engineering turbulence modeling. [computational fluid dynamics  

NASA Technical Reports Server (NTRS)

Some new developments in two equation models and second order closure models are presented. In this paper, modified two equation models are proposed to remove shortcomings such as computing flows over complex geometries and the ad hoc treatment near the separation and reattachment points. The calculations using various two equation models are compared with direct numerical solutions of channel flows and flat plate boundary layers. Development of second order closure models will also be discussed with emphasis on the modeling of pressure related correlation terms and dissipation rates in the second moment equations. All existing models poorly predict the normal stresses near the wall and fail to predict the three dimensional effect of mean flow on the turbulence. The newly developed second order near-wall turbulence model to be described in this paper is capable of capturing the near-wall behavior of turbulence as well as the effect of three dimension mean flow on the turbulence.

Shih, T.-H.

1992-01-01

384

Mathematical Models and the Experimental Analysis of Behavior  

ERIC Educational Resources Information Center

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…

Mazur, James E.

2006-01-01

385

The behavioral approach to silicon carbide power components modeling  

NASA Astrophysics Data System (ADS)

The behavioral and circuit equivalent models applied to silicon carbide semiconductor power devices have been presented. The MOSFET and Merged PiN Schottky diode (MPS) including dynamic electro-thermal modeling have been described in details. The authors also show the problems of the active power estimation for dynamic SiC MPS diode and unrealistic results for manufacturer-provided models.

Zubert, Mariusz; Napieralski, Andrzej; Napieralska, Ma?gorzata; Jab?o?ski, Grzegorz; Starzak, ?ukasz; Janicki, Marcin

2013-07-01

386

Triad model of education (II) and instructional engineering.  

PubMed

Despite the money and sweat that go into new instructional technologies, they do not produce the overall high level of student performances that societies seek. More effective teaching calls for a profound solution. It requires a coordinate triad of factors: a proper science, the correct organizational structure, and an engineering instructional technology. This second of a series of articles on the Triad Model of Education concentrates on instructional engineering. The instructional engineering drawn from the science is contingency-based. Contingency-based instructional systems always handle the inevitable two components of instruction: the repertoires of students and the setups that shape those repertoires. The setup component features five elements: subject matter, objectives, quality control, presentation modes, and logistics. The repertoire component consists of the governance of repertoires-event and lingual governed, the type of repertoire-knowing, solving, and creating, and the variability of the repertoire--convergent and divergent. These elements, and their required engineering, reveal an instructional task more complex than previously considered. Progress with such complexity occurs only when all components of the triad are in place. PMID:17992958

Vargas, E A

2007-11-01

387

Relevance of behavioral and social models to the study of consumer energy decision making and behavior  

SciTech Connect

This report reviews social and behavioral science models and techniques for their possible use in understanding and predicting consumer energy decision making and behaviors. A number of models and techniques have been developed that address different aspects of the decision process, use different theoretical bases and approaches, and have been aimed at different audiences. Three major areas of discussion were selected: (1) models of adaptation to social change, (2) decision making and choice, and (3) diffusion of innovation. Within these three areas, the contributions of psychologists, sociologists, economists, marketing researchers, and others were reviewed. Five primary components of the models were identified and compared. The components are: (1) situational characteristics, (2) product characteristics, (3) individual characteristics, (4) social influences, and (5) the interaction or decision rules. The explicit use of behavioral and social science models in energy decision-making and behavior studies has been limited. Examples are given of a small number of energy studies which applied and tested existing models in studying the adoption of energy conservation behaviors and technologies, and solar technology.

Burns, B.A.

1980-11-01

388

Towards a characterization of behavior-disease models.  

PubMed

The last decade saw the advent of increasingly realistic epidemic models that leverage on the availability of highly detailed census and human mobility data. Data-driven models aim at a granularity down to the level of households or single individuals. However, relatively little systematic work has been done to provide coupled behavior-disease models able to close the feedback loop between behavioral changes triggered in the population by an individual's perception of the disease spread and the actual disease spread itself. While models lacking this coupling can be extremely successful in mild epidemics, they obviously will be of limited use in situations where social disruption or behavioral alterations are induced in the population by knowledge of the disease. Here we propose a characterization of a set of prototypical mechanisms for self-initiated social distancing induced by local and non-local prevalence-based information available to individuals in the population. We characterize the effects of these mechanisms in the framework of a compartmental scheme that enlarges the basic SIR model by considering separate behavioral classes within the population. The transition of individuals in/out of behavioral classes is coupled with the spreading of the disease and provides a rich phase space with multiple epidemic peaks and tipping points. The class of models presented here can be used in the case of data-driven computational approaches to analyze scenarios of social adaptation and behavioral change. PMID:21826228

Perra, Nicola; Balcan, Duygu; Gonçalves, Bruno; Vespignani, Alessandro

2011-01-01

389

Modeling and simulating human teamwork behaviors using intelligent agents  

NASA Astrophysics Data System (ADS)

Among researchers in multi-agent systems there has been growing interest in using intelligent agents to model and simulate human teamwork behaviors. Teamwork modeling is important for training humans in gaining collaborative skills, for supporting humans in making critical decisions by proactively gathering, fusing, and sharing information, and for building coherent teams with both humans and agents working effectively on intelligence-intensive problems. Teamwork modeling is also challenging because the research has spanned diverse disciplines from business management to cognitive science, human discourse, and distributed artificial intelligence. This article presents an extensive, but not exhaustive, list of work in the field, where the taxonomy is organized along two main dimensions: team social structure and social behaviors. Along the dimension of social structure, we consider agent-only teams and mixed human-agent teams. Along the dimension of social behaviors, we consider collaborative behaviors, communicative behaviors, helping behaviors, and the underpinning of effective teamwork-shared mental models. The contribution of this article is that it presents an organizational framework for analyzing a variety of teamwork simulation systems and for further studying simulated teamwork behaviors.

Fan, Xiaocong; Yen, John

2004-12-01

390

Reverse Engineering Boolean Networks: From Bernoulli Mixture Models to Rule Based Systems  

PubMed Central

A Boolean network is a graphical model for representing and analyzing the behavior of gene regulatory networks (GRN). In this context, the accurate and efficient reconstruction of a Boolean network is essential for understanding the gene regulation mechanism and the complex relations that exist therein. In this paper we introduce an elegant and efficient algorithm for the reverse engineering of Boolean networks from a time series of multivariate binary data corresponding to gene expression data. We call our method ReBMM, i.e., reverse engineering based on Bernoulli mixture models. The time complexity of most of the existing reverse engineering techniques is quite high and depends upon the indegree of a node in the network. Due to the high complexity of these methods, they can only be applied to sparsely connected networks of small sizes. ReBMM has a time complexity factor, which is independent of the indegree of a node and is quadratic in the number of nodes in the network, a big improvement over other techniques and yet there is little or no compromise in accuracy. We have tested ReBMM on a number of artificial datasets along with simulated data derived from a plant signaling network. We also used this method to reconstruct a network from real experimental observations of microarray data of the yeast cell cycle. Our method provides a natural framework for generating rules from a probabilistic model. It is simple, intuitive and illustrates excellent empirical results.

Saeed, Mehreen; Ijaz, Maliha; Javed, Kashif; Babri, Haroon Atique

2012-01-01

391

Systems Security Engineering Capability Maturity Model (SSECMM), Model Description, Version 1.1.  

National Technical Information Service (NTIS)

This document is designed to acquaint the reader with the SSE-CMM Project as a whole and present the project's major work product - the Systems Security Engineering Capability Maturity Model (SSE- CMM). This document contains five chapters plus appendices...

1997-01-01

392

The method of solid rocket motors firings environmental engineering model  

NASA Astrophysics Data System (ADS)

The solid rocket motors firings is one main source of space debris, the solid rocket motors firings model is a part of space debris engineering model. In this paper, researching the NASA and ESA model to achieve an appropriate firing model, using the discrete method to model the solid rocket motors firings; application of the long-term approximation orbit evolution algorithm to calculate the evolution of firings generated by a single solid rocket motors ignition event in space; finally, application of space debris environment space debris density algorithm to calculate the distribution of firings generated by a single solid rocket motors ignition event in space, analysing the influence on the space environment and spacecraft.

Pang, Baojun; Xu, Ke; Peng, Keke; Mi, Yaoqi

393

BioModel engineering for multiscale Systems Biology.  

PubMed

We discuss some motivational challenges arising from the need to model and analyse complex biological systems at multiple scales (spatial and temporal), and present a biomodel engineering framework to address some of these issues within the context of multiscale Systems Biology. Our methodology is based on a structured family of Petri net classes which enables the investigation of a given system using various modelling abstractions: qualitative, stochastic, continuous and hybrid, optionally in a spatial context. We illustrate our approach with case studies demonstrating hierarchical flattening, treatment of space, and hierarchical organisation of space. PMID:23067820

Heiner, Monika; Gilbert, David

2013-04-01

394

Use of transport models for wildfire behavior simulations  

SciTech Connect

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.

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

1998-01-01

395

Modeling of the fracture behavior of spot welds using advanced micro-mechanical damage models  

NASA Astrophysics Data System (ADS)

This paper presents the modeling of deformation and fracture behavior of resistance spot welded joints in DP600 steel sheets. Spot welding is still the most commonly used joining technique in automotive engineering. In overloading situations like crash joints are often the weakest link in a structure. For those reasons, crash simulations need reliable and applicable tools to predict the load bearing capacity of spot welded components. Two series of component tests with different spot weld diameters have shown that the diameter of the weld nugget is the main influencing factor affecting fracture mode (interfacial or pull-out fracture), load bearing capacity and energy absorption. In order to find a correlation between nugget diameter, load bearing capacity and fracture mode, the spot welds are simulated with detailed finite element models containing base metal, heat affected zone and weld metal in lap-shear loading conditions. The change in fracture mode from interfacial to pull-out or peel-out fracture with growing nugget diameter under lap-shear loading was successfully modeled using the Gologanu-Leblond model in combination with the fracture criteria of Thomason and Embury. A small nugget diameter is identified to be the main cause for interfacial fracture. In good agreement with experimental observations, the calculated pull-out fracture initiates in the base metal at the boundary to the heat affected zone.

Sommer, Silke

2010-06-01

396

Measurement and structural models for children's problem behaviors.  

PubMed

This article considers an analytic strategy for measuring and modeling child and adolescent problem behaviors. The strategy embeds an item response model within a hierarchical model to define an interval scale for the outcomes, to assess dimensionality, and to study how individual and contextual factors relate to multiple dimensions of problem behaviors. To illustrate, the authors analyze data from the primary caregiver ratings of 2,177 children aged 9-15 in 79 urban neighborhoods on externalizing behavior problems using the Child Behavior Checklist 4-18 (T. M. Achenbach, 1991a). Two subscales, Aggression and Delinquency, are highly correlated, and yet unidimensionality must be rejected because these subscales have different associations with key theoretically related covariates. PMID:11194209

Cheong, Y F; Raudenbush, S W

2000-12-01

397

Modeling synchronized calling behavior of Japanese tree frogs  

NASA Astrophysics Data System (ADS)

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.

Aihara, Ikkyu

2009-07-01

398

A Topological Model of Bilingual Intercalation Behavior.  

ERIC Educational Resources Information Center

This paper reviews issues and analyses in bilingual switching, or intercalation, and offers a topological model to represent the activity of code switching, sometimes under the same environmental conditions and with the same interlocutors. The topological notion of catastrophe is proposed as a means to model the various factors that influence code…

Attinasi, John; And Others

399

Engineering model for prediction of in-situ oil-shale retort blasting  

SciTech Connect

The in-situ extraction of oil from most oil shale beds is highly dependent upon explosive fracturing and rubbing of rock in a controlled and predictable manner. In blasting, it is necessary not only to fracture the rock, but also to move the broken rubble in a predictable manner. Most in-situ extraction techniques require rubblization to take place in a confined region where rock motion is a predominate factor in creating a permeable broken bed. In this paper, an engineering model is presented which describes the large rubble motion during blasting. This model is intended to provide the blast designer with a tool for evaluation and further refinement of blasting patterns and timing sequences. In this model the rock medium is represented by a discrete series of circular regions of fractured material. These regions are set in motion by pressure loads from the explosive. The motion of the regions is calculated using a step-wise, explicit, numerical time integration method. Interaction of adjacent regions is based on inelastic impact of spherical bodies. The derivation of this model is presented along with the background for selecting loading pressure based on explosive behavior. Three typical examples are discussed which illustrate the use of this model to predict rubble motion. This engineering representation appears to provide a practical model for use in predicting rubble motion and a tool for design evaluation of blasting in confined geometries. 16 figures, 1 table.

Schamaun, J.T.

1983-01-01

400

Hybrid Neural Network Based Model for Predicting the Performance of a Two Stroke Spark Ignition Engine  

Microsoft Academic Search

This paper describes a hybrid neural network based model for predicting the performance of a single cylinder two stroke cycle spark ignition engine. The engine was run in the carburetor mode and engine mapping was done by collecting the engine performance data in terms of power and brake specific fuel consumption for various combinations of speed, load and air-fuel ratio.

Mohmad Marouf Wani; M. Arif Wani

2007-01-01

401

Transtheoretical Model of Health Behavior Change Applied to Voice Therapy  

PubMed Central

Summary Studies of patient adherence to health behavior programs, such as physical exercise, smoking cessation, and diet, have resulted in the formulation and validation of the Transtheoretical Model (TTM) of behavior change. Although widely accepted as a guide for the development of health behavior interventions, this model has not been applied to vocal rehabilitation. Because resolution of vocal difficulties frequently depends on a patient’s ability to make changes in vocal and health behaviors, the TTM may be a useful way to conceptualize voice behavior change processes, including the patient’s readiness for change. The purpose of this paper is to apply the TTM to the voice therapy process to: (1) provide an organizing framework for understanding of behavior change in voice therapy, (2) explain how treatment adherence problems can arise, and (3) provide broad strategies to improve treatment adherence. Given the significant role of treatment adherence in treatment outcome, considering readiness for behavior change should be taken into account when planning treatment. Principles of health behavior change can aid speech pathologists in such understanding and estimating readiness for voice therapy.

van Leer, Eva; Hapner, Edie R.; Connor, Nadine P.

2010-01-01

402

40 CFR 1068.360 - What restrictions apply to assigning a model year to imported engines and equipment?  

Code of Federal Regulations, 2013 CFR

... What restrictions apply to assigning a model year to imported engines and equipment... What restrictions apply to assigning a model year to imported engines and equipment...section includes limitations on assigning a model year to engines and equipment that...

2013-07-01

403

Digital computer program for generating dynamic turbofan engine models (DIGTEM)  

NASA Technical Reports Server (NTRS)

This report describes DIGTEM, a digital computer program that simulates two spool, two-stream turbofan engines. The turbofan engine model in DIGTEM contains steady-state performance maps for all of the components and has control volumes where continuity and energy balances are maintained. Rotor dynamics and duct momentum dynamics are also included. Altogether there are 16 state variables and state equations. DIGTEM features a backward-differnce integration scheme for integrating stiff systems. It trims the model equations to match a prescribed design point by calculating correction coefficients that balance out the dynamic equations. It uses the same coefficients at off-design points and iterates to a balanced engine condition. Transients can also be run. They are generated by defining controls as a function of time (open-loop control) in a user-written subroutine (TMRSP). DIGTEM has run on the IBM 370/3033 computer using implicit integration with time steps ranging from 1.0 msec to 1.0 sec. DIGTEM is generalized in the aerothermodynamic treatment of components.

Daniele, C. J.; Krosel, S. M.; Szuch, J. R.; Westerkamp, E. J.

1983-01-01

404

Controlling reactive behavior with consistent world modeling and reasoning  

NASA Astrophysics Data System (ADS)

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.

Bou-Ghannam, Akram A.

1992-03-01

405

Exploratory behavior, trap models, and glass transitions.  

PubMed

A random walk is performed on a disordered landscape composed of N sites randomly and uniformly distributed inside a d-dimensional hypercube. The walker hops from one site to another with probability proportional to exp[-betaE(D)], where beta=1/T is the inverse of a formal temperature and E(D) is an arbitrary cost function which depends on the hop distance D. Analytic results indicate that, if E(D)=D(d) and N--> infinity, there exists a glass transition at beta(d)=pi(d/2)/[(d/2)Gamma(d/2)]. Below T(d), the average trapping time diverges and the system falls into an out-of-equilibrium regime with aging phenomena. A Lévy flight scenario and applications of exploratory behavior are considered. PMID:14995752

Martinez, Alexandre S; Kinouchi, Osame; Risau-Gusman, Sebastian

2004-01-01

406

Nuclear Graphite - Fracture Behavior and Modeling  

SciTech Connect

Evidence for the graphite fracture mechanism is reviewed and discussed. The roles of certain microstructural features in the graphite fracture process are reported. The Burchell fracture model is described and its derivation reported. The successful application of the fracture model to uniaxial tensile data from several graphites with widely ranging structure and texture is reported. The extension of the model to multiaxial loading scenarios using two criteria is discussed. Initially, multiaxial strength data for H-451 graphite were modeled using the fracture model and the Principle of Independent Action. The predicted 4th stress quadrant failure envelope was satisfactory but the 1st quadrant predictions were not conservative and thus were unsatisfactory. Multiaxial strength data from the 1st and 4th stress quadrant for NBG-18 graphite are reported. To improve the conservatism of the predicted 1st quadrant failure envelope for NBG-18 the Shetty criterion has been applied to obtain the equivalent critical stress intensity factor, KIc (Equi), for each applied biaxial stress ratio. The equivalent KIc value is used in the Burchell fracture model to predict the failure envelope. The predicted 1st stress quadrant failure envelope is conservative and thus more satisfactory than achieved previously using the fracture model combined with the Principle of Independent Action.

Burchell, Timothy D [ORNL; Battiste, Rick [ORNL; Strizak, Joe P [ORNL

2011-01-01

407

Drive Rig Mufflers for Model Scale Engine Acoustic Testing  

NASA Technical Reports Server (NTRS)

Testing of air breathing propulsion systems in the 9x15 foot wind tunnel at NASA Glenn Research Center depends on compressed air turbines for power. The drive rig turbines exhaust directly to the wind tunnel test section, and have been found to produce significant unwanted noise that reduces the quality of the acoustic measurements of the model being tested. In order to mitigate this acoustic contamination, a muffler can be attached downstream of the drive rig turbine. The modern engine designs currently being tested produce much less noise than traditional engines, and consequently a lower noise floor is required of the facility. An acoustic test of a muffler designed to mitigate this extraneous noise is presented, and a noise reduction of 8 dB between 700 Hz and 20 kHz was documented, significantly improving the quality of acoustic measurements in the facility.

Stephens, David

2010-01-01

408

LOX/Methane Main Engine Igniter Tests and Modeling  

NASA Technical Reports Server (NTRS)

The LOX/methane propellant combination is being considered for the Lunar Surface Access Module ascent main engine propulsion system. The proposed switch from the hypergolic propellants used in the Apollo lunar ascent engine to LOX/methane propellants requires the development of igniters capable of highly reliable performance in a lunar surface environment. An ignition test program was conducted that used an in-house designed LOX/methane spark torch igniter. The testing occurred in Cell 21 of the Research Combustion Laboratory to utilize its altitude capability to simulate a space vacuum environment. Approximately 750 ignition test were performed to evaluate the effects of methane purity, igniter body temperature, spark energy level and frequency, mixture ratio, flowrate, and igniter geometry on the ability to obtain successful ignitions. Ignitions were obtained down to an igniter body temperature of approximately 260 R with a 10 torr back-pressure. The data obtained is also being used to anchor a CFD based igniter model.

Breisacher, Kevin J.; Ajmani, Kumund

2008-01-01

409

User interface derivation from business processes: a model-driven approach for organizational engineering  

Microsoft Academic Search

This paper defines a model-driven approach for organizational engineering in which user interfaces of information systems are derived from business processes. This approach consists of four steps: business process modeling in the context of organizational engineering, task model derivation from the business process model, task refinement, and user interface model derivation from the task model. Each step contributes to specify

Kênia Soares Sousa; Hildeberto Mendonça Filho; Jean Vanderdonckt; Els Rogier; Joannes Vandermeulen

2008-01-01

410

A Behavioral Model of Labor Force Migration.  

National Technical Information Service (NTIS)

A model of inter-state out migration based upon the theoretical constructs of the human capital literature is empirically tested to ascertain the motivations for labor force migration. It is established that occupational mobility and geographic mobility a...

S. R. Nilsen

1976-01-01

411

Mathematical Model for the Behavior of Wildfires  

NASA Astrophysics Data System (ADS)

Wildfires have been a long-standing problem in today's society. In this paper, we derive and solve a fluid dynamics model to study a specific type of wildfire, namely, a two dimensional flow around a concentrated line of fire, resulting in a narrow plume of hot gas rising and entraining the surrounding air. The model assumes that the surrounding air is constant density and irrotational, and uses an unsteady plume model to describe the evolution of the mass, momentum and energy inside the plume, with sources derived to model mixing in the style of Morton, Taylor, and Turner (Proc. Roy. Soc. London, A 234, 1-23, 1956). The sources to the dynamical processes in the plume couple to the motion through the surrounding air through a Biot-Savart integral formulation to solve the equations of motion with a line of singularities along the plume. The singularities model a vortex sheet in the same manner as Alben and Shelley (Phys. Rev. Letters, 100, 074301, 2008), except that we include a sink term in the Biot-Savart integral to couple the entrainment. The results show that this model is capable of capturing a complicated interaction of the plume with the surrounding air.

Delbene, Kevin; Drew, Donald

2009-11-01

412

Formal modeling of robot behavior with learning.  

PubMed

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

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

2013-11-01

413

A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation  

Microsoft Academic Search

A mixing controlled direct chemistry (MCDC) combustion model with sub-grid scale (SGS) mixing effects and chemical kinetics has been evaluated for Large Eddy Simulation (LES) of diesel engine combustion. The mixing effect is modelled by a mixing timescale based on mixture fraction variance and sub-grid scalar dissipation rate. The SGS scalar dissipation rate is modelled using a similarity term and

Yuxin Zhang; Christopher J. Rutland

2011-01-01

414

A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation  

Microsoft Academic Search

A mixing controlled direct chemistry (MCDC) combustion model with sub-grid scale (SGS) mixing effects and chemical kinetics has been evaluated for Large Eddy Simulation (LES) of diesel engine combustion. The mixing effect is modelled by a mixing timescale based on mixture fraction variance and sub-grid scalar dissipation rate. The SGS scalar dissipation rate is modelled using a similarity term and

Yuxin Zhang; Christopher J. Rutland

2012-01-01

415

Model Order Reduction for Large Scale Engineering Models Developed in ANSYS  

Microsoft Academic Search

The software mor4ansys that allows engineers employ the modern model reduction technique to the finite element models developed in ANSYS is presented. We focus on how one extracts the required information from ANSYS and makes the model reduction implementation not dependent on a particular sparse solver in C++. We discuss the computational cost and give examples related to structural mechanics

Evgenii B. Rudnyi; Jan G. Korvink

2004-01-01

416

Efficiencies and coefficients of performance of heat engines, refrigerators, and heat pumps with friction: a universal limiting behavior.  

PubMed

For work-producing heat engines, or work-consuming refrigerators and heat pumps, the percentage decrease caused by friction in their efficiencies, or coefficients of performance (COP's), is approximately given by the ratio W(fric)/W between the work spent against friction forces and the work performed by, or delivered to, the working fluid. This universal scaling, which applies in the limit of small friction (W(fric)/W engine's figures of merit (FOM's, either efficiencies or COP's) do not come too close to unity (no higher than, say, 0.5 in the case of heat-engine efficiencies), allows a simple and quick estimate of the impact that friction losses can have on the FOM's of thermal engines and plants, or of the level of those losses from the observed and predicted FOM's. In the case of refrigerators and heat pumps, if W(fric)/W engines), the COP percentage decrease due to friction approaches asymptotically (W(fric)/W)/(1+W(fric)/W) instead of W(fric)/W. Estimates for the level of frictional losses using the Carnot (or, for heat engines and power plants only, the Curzon-Ahlborn) predictions and observed FOM's of real power plants, heat engines, refrigerators, and heat pumps show that they usually operate in domains where these behaviors are valid. PMID:23214740

Bizarro, João P S; Rodrigues, Paulo

2012-11-01

417

Model based document and report generation for systems engineering  

NASA Astrophysics Data System (ADS)

As Model Based Systems Engineering (MBSE) practices gain adoption, various approaches have been developed in order to simplify and automate the process of generating documents from models. Essentially, all of these techniques can be unified around the concept of producing different views of the model according to the needs of the intended audience. In this paper, we will describe a technique developed at JPL of applying SysML Viewpoints and Views to generate documents and reports. An architecture of model-based view and document generation will be presented, and the necessary extensions to SysML with associated rationale will be explained. A survey of examples will highlight a variety of views that can be generated, and will provide some insight into how collaboration and integration is enabled. We will also describe the basic architecture for the enterprise applications that support this approach.

Delp, C.; Lam, D.; Fosse, E.; Lee, Cin-Young

418

Engine structures modeling software system: Computer code. User's manual  

NASA Technical Reports Server (NTRS)

ESMOSS is 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 software architecture of ESMOSS is designed in modular form with a central executive module through which the user controls and directs the development of the analytical model. Modules consist of a geometric shape generator, a library of discretization procedures, interfacing modules to join both geometric and discrete models, a deck generator to produce input for NASTRAN and a 'recipe' processor which generates geometric models from parametric definitions. ESMOSS can be executed both in interactive and batch modes. Interactive mode is considered to be the default mode and that mode will be assumed in the discussion in this document unless stated otherwise.

1992-01-01

419

Systems Engineering Model and Training Application for Desktop Environment  

NASA Technical Reports Server (NTRS)

Provide a graphical user interface based simulator for desktop training, operations and procedure development and system reference. This simulator allows for engineers to train and further understand the dynamics of their system from their local desktops. It allows the users to train and evaluate their system at a pace and skill level based on the user's competency and from a perspective based on the user's need. The simulator will not require any special resources to execute and should generally be available for use. The interface is based on a concept of presenting the model of the system in ways that best suits the user's application or training needs. The three levels of views are Component View, the System View (overall system), and the Console View (monitor). These views are portals into a single model, so changing the model from one view or from a model manager Graphical User Interface will be reflected on all other views.

May, Jeffrey T.

2010-01-01

420

The Ram as a Model for Behavioral Neuroendocrinology  

PubMed Central

The sheep offers a unique model to study male sexual behavior and sexual partner preference. Rams are seasonal breeders and show the greatest libido during short days coincident with the resumption of ovarian cyclicity in the ewe. Threshold concentrations of testosterone are required for the acquisition and display of adult sexual behavior. In addition, estrogens produced from circulating testosterone by cytochrome P450 aromatase in the preoptic area are critical for the maintenance of sexual behaviors in rams. Sex differences in adult reproductive behaviors and hormone responsiveness are the result of permanent organizational effects exerted by testosterone and its metabolites on brain development. Early exposure to ewes enhances ram sexual performance, but cannot prevent some rams from exhibiting male-oriented sexual partner preferences. Neurochemical and neuroanatomical studies suggest that male-oriented ram behavior may be a consequence of individual variations in brain sexual differentiation.

Perkins, Anne; Roselli, Charles E.

2007-01-01

421

Modeling of wormhole behavior in carbonate acidizing  

SciTech Connect

A mathematical model that describes the growth and competition of wormholes during an acidizing treatment in a carbonate formation is developed. The purpose of the treatment is to remove any near wellbore permeability damage created by drilling or completion fluids so that the production of reservoir fluids is stimulated. Hydrochloric acid is commonly used for this purpose. Since the acid solution tends to flow into the less resistant areas, large pores on the rock surface receive most acid fluid. Pores are enlarged due to the reaction between acid solution and carbonates. The growth of large pores in the formation is referred to as wormholing. Results from the model show that wormholes are formed due to the heterogeneity of carbonate rock and the reaction kinetics between acid and carbonates. Formation of a dominant wormhole is controlled by fluid diffusivity and fluid loss. Model results have good agreement with the results from published papers.

Hung, K.M.

1987-01-01

422

Molecular-level engineering of protein physical hydrogels for predictive sol-gel phase behavior  

PubMed Central

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.

Mulyasasmita, Widya; Lee, Ji Seok; Heilshorn, Sarah C.

2011-01-01

423

Behavior of engineered nanoparticles in aqueous solutions and porous media: Connecting experimentation to probabilistic analysis  

NASA Astrophysics Data System (ADS)

Engineered nanoparticles have enhanced products and services in the fields of medicine, energy, engineering, communications, personal care, environmental treatment, and many others. The increased use of engineered nanoparticles in consumer products will lead to these materials in natural systems, inevitably becoming a potential source of pollution. The study of the stability and mobility of these materials is fundamental to understand their behavior in natural systems and predict possible health and environmental implications. In addition, the use of probabilistic methods such as sensitivity analysis applied to the parameters controlling their behavior is useful in providing support in performing a risk assessment. This research investigated the stability and mobility of two types of metal oxide nanoparticles (aluminum oxide and titanium dioxide). The stability studies tested the effect of sand, pH 4, 7, and 10, and the NaCl in concentrations of 10mM, 25mM, 50mM, and 75mM. The mobility was tested using saturated quartz sand columns and nanoparticles suspension at pH 4 and 7 and in the presence of NaCl and CaCl2 in concentrations of 0.1mM, 1mM, and 10mM. Additionally, this work performed a sensitivity analysis of physical parameters used in mobility experiment performed for titanium dioxide and in mobility experiments taken from the literature for zero valent iron nanoparticles and fluorescent colloids to determine their effect on the value C/Co of by applying qualitative and quantitative methods. The results from the stability studies showed that titanium dioxide nanoparticles (TiO2) could remain suspended in solution for up to seven days at pH 10 and pH 7 even after settling of the sand; while for pH 4 solutions titanium settled along with the sand and after seven days no particles were observed in suspension. Other stability studies showed that nanoparticle aluminum oxide (Al2O3) and titanium dioxide (TiO2) size increased with increasing ionic strength (10 to 75 mM NaCl). The results from the mobility experiments showed that ionic strength has more effect on aluminum oxide nanoparticles mobility than on titanium oxide nanoparticles mobility. For Al2O3 25% of the initial concentration was obtained in the effluent whereas for TiO2 less than the 10% of the initial concentration was observed. In general, when the ionic strength was increased the effluent of nanoparticles decreased. Collision efficiencies calculated base on the colloid filtration theory were consistent with the mobility experiments. Results from sensitivity analysis showed that for zero valent iron nanoparticles and fluorescent colloids porous medium diameter and porosity were the parameters that most influenced the variability of C/Co whereas for titanium dioxide nanoparticles C/Co was more sensitive to column length and pore water velocity.

Contreras, Carolina

424

BEHAVIORAL INHIBITION AND GLUCOCORTICOID DYNAMICS IN A RODENT MODEL  

PubMed Central

Behavioral inhibition (i.e. avoidance of unfamiliar) has been linked to significant differences in stress physiology and health. Developing an animal model of this common temperament provides a means to experimentally study the development and physiology of this trait as it relates to stress-related health processes. To elaborate such an animal model, we studied individual rat responses to two novel situations that mimic behavioral inhibition tests for humans (one non-social and one social). We measured individual consistency of behavioral responses across tests and time, and examined the relationship between behavior and glucocorticoid levels in outbred Sprague-Dawley male rats. Individuals were consistent in their behavioral responses to the same novel environment over time, but not in their responses across two different environments (i.e. non-social vs. social). A third of males were slow to approach novelty in both arenas (INHIBITED) and another third were fast to approach in both arenas (NON-INHIBITED). Behavioral inhibition was relatively stable across time and was associated with increased glucocorticoid production at baseline and in response to novelty but not during a post-novelty recovery period. Glucocorticoid levels were more closely related to their responses to the social novel arena than the non-social arena. Thus, behavioral inhibition is associated with acute and basal glucocorticoid over production and social inhibition is a more important predictor of adrenal activity than non-social inhibition. These preliminary observations provide strong support for an animal model of human behavioral inhibition and identify specific aspect of glucocorticoid production dynamics to examine in behaviorally inhibited children.

Cavigelli, Sonia A.; Stine, Michele M.; Kovacsics, Colleen; Jefferson, Akilah; Diep, Mai N.; Barrett, Catherine E.

2007-01-01

425

A neurobehavioral model of flexible spatial language behaviors.  

PubMed

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

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

2012-11-01

426

Modeling and simulating human teamwork behaviors using intelligent agents  

Microsoft Academic Search

Among researchers in multi-agent systems there has been growing interest in using intelligent agents to model and simulate human teamwork behaviors. Teamwork modeling is important for training humans in gaining collaborative skills, for supporting humans in making critical decisions by proactively gathering, fusing, and sharing information, and for building coherent teams with both humans and agents working effectively on intelligence-intensive

Xiaocong Fan; John Yen

2004-01-01

427

Behavior-based modeling and its application to Email analysis  

Microsoft Academic Search

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

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

2006-01-01

428

Uniaxial Electromechanical Behavior of a Soft PZT: Experiments and Modeling  

Microsoft Academic Search

The aim of this work is to collect a database from uniaxial experiments and model the material behavior. A soft PZT is tested in compression; the influence of stress rate seems to be negligible and the material accommodates to cyclic mechanical loadings. These responses are simulated by means of a phenomenological model taking into account the coupling between remnant strain

Olivier Guillon; Patrick Delobelle; Frédéric Thiébaud; Vincent Walter; Dominique Perreux

2004-01-01

429

MULTISCALE MODELING OF THE THERMOVISCOPLASTIC BEHAVIOR OF METAL MATRIX COMPOSITES  

Microsoft Academic Search

Summary. This paper deals with the thermoviscoplastic behavior of metal matrix com- posites. A constitutive model, based on Dvorak's Transformation Field Analysis, is im- plemented to investigate the response of an Al\\/Al203 composite under an anisothermal, cyclic loading. The experimental validation of the model and its implementation in the finite element code ABAQUS through a user defined material (UMAT) subroutine

Benoit Berini; Myriam Bourgeois; Djaar Boussaa; Pierre Suquet; Jean-Jacques Thomas

430

Effects of Video Modeling on Treatment Integrity of Behavioral Interventions  

ERIC Educational Resources Information Center

We examined the effects of individualized video modeling on the accurate implementation of behavioral interventions using a multiple baseline design across 3 teachers. During video modeling, treatment integrity improved above baseline levels; however, teacher performance remained variable. The addition of verbal performance feedback increased…

DiGennaro-Reed, Florence D.; Codding, Robin; Catania, Cynthia N.; Maguire, Helena

2010-01-01

431

Thermodynamic and rheological modeling of coal ash behavior  

Microsoft Academic Search

This paper describes some recent results attained in modeling the behavior of coal ash and slags derived from it. The focus of the model is on the effects of increasing temperature on coal ash and the recognition that ash will undergo a series of transformations which are specified by the composition and temperature of the ash but which may be

H. H. Schobert; Bongjin Jung

1988-01-01

432

Multidomain behavior during Thellier paleointensity experiments: a phenomenological model  

Microsoft Academic Search

The most commonly used method for paleointensity determination, the Thellier method, requires the absence of multidomain magnetic behavior. The influence of multidomain remanence on paleointensity determination and its recognition during the experiment are, however, only partially understood. Here, we present a phenomenological model of TRM acquisition and its application to the Thellier experiment. This model is an extension of the

R. Leonhardt; D. Krása; R. S. Coe

2004-01-01

433

A Neurobehavioral Model of Flexible Spatial Language Behaviors  

ERIC Educational Resources Information Center

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…

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

2012-01-01

434

A conceptual model for cognitive-behavior therapy with children  

Microsoft Academic Search

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

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

1985-01-01

435

Methods for model selection in applied science and engineering.  

SciTech Connect

Mathematical models are developed and used to study the properties of complex systems and/or modify these systems to satisfy some performance requirements in just about every area of applied science and engineering. A particular reason for developing a model, e.g., performance assessment or design, is referred to as the model use. Our objective is the development of a methodology for selecting a model that is sufficiently accurate for an intended use. Information on the system being modeled is, in general, incomplete, so that there may be two or more models consistent with the available information. The collection of these models is called the class of candidate models. Methods are developed for selecting the optimal member from a class of candidate models for the system. The optimal model depends on the available information, the selected class of candidate models, and the model use. Classical methods for model selection, including the method of maximum likelihood and Bayesian methods, as well as a method employing a decision-theoretic approach, are formulated to select the optimal model for numerous applications. There is no requirement that the candidate models be random. Classical methods for model selection ignore model use and require data to be available. Examples are used to show that these methods can be unreliable when data is limited. The decision-theoretic approach to model selection does not have these limitations, and model use is included through an appropriate utility function. This is especially important when modeling high risk systems, where the consequences of using an inappropriate model for the system can be disastrous. The decision-theoretic method for model selection is developed and applied for a series of complex and diverse applications. These include the selection of the: (1) optimal order of the polynomial chaos approximation for non-Gaussian random variables and stationary stochastic processes, (2) optimal pressure load model to be applied to a spacecraft during atmospheric re-entry, and (3) optimal design of a distributed sensor network for the purpose of vehicle tracking and identification.

Field, Richard V., Jr.

2004-10-01

436

Methods for model selection in applied science and engineering  

NASA Astrophysics Data System (ADS)

Mathematical models are developed and used to study the properties of complex systems and/or modify these systems to satisfy some performance requirements in just about every area of applied science and engineering. A particular reason for developing a model, e.g., performance assessment or design, is referred to as the model use. Our objective is the development of a, methodology for selecting a model that is sufficiently accurate for an intended use. Information on the system being modeled is, in general, incomplete, so that there may be two or more models consistent with the available information. The collection of these models is called the class of candidate models. Methods are developed for selecting the optimal member from a class of candidate models for the system. The optimal model depends on the available information, the selected class of candidate models, and the model use. Classical methods for model selection, including the method of maximum likelihood and Bayesian methods, as well as a method employing a decision-theoretic approach, are formulated to select the optimal model for numerous applications. There is no requirement that the candidate models be random. Classical methods for model selection ignore model use and require data to be available. Examples are used to show that these methods can be unreliable when data is limited. The decision-theoretic approach to model selection does not have these limitations, and model use is included through an appropriate utility function. This is especially important when modeling high risk systems, where the consequences of using an inappropriate model for the system can be disastrous. The decision-theoretic method for model selection is developed and applied for a series of complex and diverse applications. These include the selection of the: (1) optimal order of the polynomial chaos approximation for non-Gaussian random variables and stationary stochastic processes, (2) optimal pressure load model to be applied to a spacecraft during atmospheric re-entry, and (3) optimal design of a distributed sensor network for the purpose of vehicle tracking and identification.

Field, Richard Van Deventer, Jr.

437

Pipeline design model addresses COâ's challenging behavior  

Microsoft Academic Search

The nature of carbon dioxide (COâ) makes designing COâ pipeline systems more difficult than designing systems for natural gas. A rigorous pipeline design model, however, satisfies the unique COâ transportation requirement for complete energy as well as momentum balance. Demand for COâ has been increasing principally because of its use in enhanced oil recovery (EOR) projects. But since COâ is

Hein

1986-01-01

438

Accelerating Cancer Modeling with RNAi and Nongermline Genetically Engineered Mouse Models  

PubMed Central

For more than two decades, genetically engineered mouse models have been key to our mechanistic understanding of tumorigenesis and cancer progression. Recently, the massive quantity of data emerging from cancer genomics studies has demanded a corresponding increase in the efficiency and throughput of in vivo models for functional testing of putative cancer genes. Already a mainstay of cancer research, recent innovations in RNA interference (RNAi) technology have extended its utility for studying gene function and genetic interactions, enabling tissue-specific, inducible and reversible gene silencing in vivo. Concurrent advances in embryonic stem cell (ESC) culture and genome engineering have accelerated several steps of genetically engineered mouse model production and have facilitated the incorporation of RNAi technology into these models. Here, we review the current state of these technologies and examine how their integration has the potential to dramatically enhance the throughput and capabilities of animal models for cancer.

Livshits, Geulah; Lowe, Scott W.

2014-01-01

439

Study of ATES thermal behavior using a steady flow model  

NASA Astrophysics Data System (ADS)

The thermal behavior of a single well aquifer thermal energy storage system in which buoyancy flow is neglected is studied. A dimensionless formulation of the energy transport equations for the aquifer system is presented, and the key dimensionless parameters are discussed. A simple numerical model is used to generate graphs showing the thermal behavior of the system as a function of these parameters. Some comparisons with field experiments are given to illustrate the use of the dimensionless groups and graphs.

Doughty, C.; Hellstroem, G.; Tsang, C. F.; Claesson, J.

1981-01-01

440

ISO 9000 and/or Systems Engineering Capability Maturity Model?  

NASA Technical Reports Server (NTRS)

For businesses and organizations to remain competitive today they must have processes and systems in place that will allow them to first identify customer needs and then develop products/processes that will meet or exceed the customers needs and expectations. Customer needs, once identified, are normally stated as requirements. Designers can then develop products/processes that will meet these requirements. Several functions, such as quality management and systems engineering management are used to assist product development teams in the development process. Both functions exist in all organizations and both have a similar objective, which is to ensure that developed processes will meet customer requirements. Are efforts in these organizations being duplicated? Are both functions needed by organizations? What are the similarities and differences between the functions listed above? ISO 9000 is an international standard of goods and services. It sets broad requirements for the assurance of quality and for management's involvement. It requires organizations to document the processes and to follow these documented processes. ISO 9000 gives customers assurance that the suppliers have control of the process for product development. Systems engineering can broadly be defined as a discipline that seeks to ensure that all requirements for a system are satisfied throughout the life of the system by preserving their interrelationship. The key activities of systems engineering include requirements analysis, functional analysis/allocation, design synthesis and verification, and system analysis and control. The systems engineering process, when followed properly, will lead to higher quality products, lower cost products, and shorter development cycles. The System Engineering Capability Maturity Model (SE-CMM) will allow companies to measure their system engineering capability and continuously improve those capabilities. ISO 9000 and SE-CMM seem to have a similar objective, which is to document the organization's processes and certify to potential customers the capability of a supplier to control the processes that determine the quality of the product or services being produced. The remaining sections of this report examine the differences and similarities between ISO 9000 and SE-CMM and make recommendations for implementation.

Gholston, Sampson E.

2002-01-01

441

Behavioral phenotyping of mouse models of Parkinson's Disease  

PubMed Central

Parkinson's disease (PD) is a common neurodegenerative movement disorder afflicting millions of people in the United States. The advent of transgenic technologies has contributed to the development of several new mouse models, many of which recapitulate some aspects of the disease; however, no model has been demonstrated to faithfully reproduce the full constellation of symptoms seen in human PD. This may be due in part to the narrow focus on the dopamine-mediated motor deficits. As current research continues to unmask PD as a multi-system disorder, animal models should similarly evolve to include the non-motor features of the disease. This requires that typically cited behavioral test batteries be expanded. The major non-motor symptoms observed in PD patients include hyposmia, sleep disturbances, gastrointestinal dysfunction, autonomic dysfunction, anxiety, depression, and cognitive decline. Mouse behavioral tests exist for all of these symptoms and while some models have begun to be reassessed for the prevalence of this broader behavioral phenotype, the majority has not. Moreover, all behavioral paradigms should be tested for their responsiveness to L-DOPA so these data can be compared to patient response and help elucidate which symptoms are likely not dopamine-mediated. Here, we suggest an extensive, yet feasible, battery of behavioral tests for mouse models of PD aimed to better assess both non-motor and motor deficits associated with the disease.

Taylor, Tonya N.; Greene, James G.; Miller, Gary W.

2010-01-01

442

Quantitative model of the phase behavior of recombinant pH-responsive elastin-like polypeptides.  

PubMed

Quantitative models are required to engineer biomaterials with environmentally responsive properties. With this goal in mind, we developed a model that describes the pH-dependent phase behavior of a class of stimulus responsive elastin-like polypeptides (ELPs) that undergo reversible phase separation in response to their solution environment. Under isothermal conditions, charged ELPs can undergo phase separation when their charge is neutralized. Optimization of this behavior has been challenging because the pH at which they phase separate, pHt, depends on their composition, molecular weight, concentration, and temperature. To address this problem, we developed a quantitative model to describe the phase behavior of charged ELPs that uses the Henderson-Hasselbalch relationship to describe the effect of side-chain ionization on the phase-transition temperature of an ELP. The model was validated with pH-responsive ELPs that contained either acidic (Glu) or basic (His) residues. The phase separation of both ELPs fit this model across a range of pH. These results have important implications for applications of pH-responsive ELPs because they provide a quantitative model for the rational design of pH-responsive polypeptides whose transition can be triggered at a specified pH. PMID:20925333

Mackay, J Andrew; Callahan, Daniel J; Fitzgerald, Kelly N; Chilkoti, Ashutosh

2010-11-01

443

A mathematical model for jet engine combustor pollutant emissions  

NASA Technical Reports Server (NTRS)

Mathematical modeling for the description of the origin and disposition of combustion-generated pollutants in gas turbines is presented. A unified model in modular form is proposed which includes kinetics, recirculation, turbulent mixing, multiphase flow effects, swirl and secondary air injection. Subelements of the overall model were applied to data relevant to laboratory reactors and practical combustor configurations. Comparisons between the theory and available data show excellent agreement for basic CO/H2/Air chemical systems. For hydrocarbons the trends are predicted well including higher-than-equilibrium NO levels within the fuel rich regime. Although the need for improved accuracy in fuel rich combustion is indicated, comparisons with actual jet engine data in terms of the effect of combustor-inlet temperature is excellent. In addition, excellent agreement with data is obtained regarding reduced NO emissions with water droplet and steam injection.

Boccio, J. L.; Weilerstein, G.; Edelman, R. B.

1973-01-01

444

Optimization of Combustion Chamber for Diesel Engine Using Kriging Model  

NASA Astrophysics Data System (ADS)

Diesel engine combustion chamber which reduces exhaust emission has been designed using CFD analysis and optimization techniques. In order to save computational time for design, the Kriging model, one of the response surface models, is adopted here. For a robust exploration, both the estimated function value of the model and its uncertainty are considered at the same time. In the present problem, the k-means method is used to limit the number of additional sample points to a reasonable level. Among the additional sample points, two combustion chamber shapes dominate the baseline configuration in terms of all objective functions. Compared with the previous optimization with the evolutionary algorithm, its computational time for design was cut by 95%. The results indicate that the present method is a practical approach for real-world applications.

Jeong, Shinkyu; Minemura, Youichi; Obayashi, Shigeru