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1

Automated Student Model Improvement  

ERIC Educational Resources Information Center

Student modeling plays a critical role in developing and improving instruction and instructional technologies. We present a technique for automated improvement of student models that leverages the DataShop repository, crowd sourcing, and a version of the Learning Factors Analysis algorithm. We demonstrate this method on eleven educational…

Koedinger, Kenneth R.; McLaughlin, Elizabeth A.; Stamper, John C.

2012-01-01

2

Human-Machine Interface in Building Automation Systems  

E-print Network

problem between the non-computer knowledgeable operator and the computer based Building Automation System. One of the solutions to this problem is the design and implementation of a human machine interface which educates the operator to utilize the system...

Sobczak, N. L.

1981-01-01

3

Space station automation and robotics study. Operator-systems interface  

NASA Technical Reports Server (NTRS)

This is the final report of a Space Station Automation and Robotics Planning Study, which was a joint project of the Boeing Aerospace Company, Boeing Commercial Airplane Company, and Boeing Computer Services Company. The study is in support of the Advanced Technology Advisory Committee established by NASA in accordance with a mandate by the U.S. Congress. Boeing support complements that provided to the NASA Contractor study team by four aerospace contractors, the Stanford Research Institute (SRI), and the California Space Institute. This study identifies automation and robotics (A&R) technologies that can be advanced by requirements levied by the Space Station Program. The methodology used in the study is to establish functional requirements for the operator system interface (OSI), establish the technologies needed to meet these requirements, and to forecast the availability of these technologies. The OSI would perform path planning, tracking and control, object recognition, fault detection and correction, and plan modifications in connection with extravehicular (EV) robot operations.

1984-01-01

4

Automated visual imaging interface for the plant floor  

NASA Astrophysics Data System (ADS)

The paper will provide an overview of the challenges facing a user of automated visual imaging (" AVI" ) machines and the philosophies that should be employed in designing them. As manufacturing tools and equipment become more sophisticated it is increasingly difficult to maintain an efficient interaction between the operator and machine. The typical user of an AVI machine in a production environment is technically unsophisticated. Also operator and machine ergonomics are often a neglected or poorly addressed part of an efficient manufacturing process. This paper presents a number of man-machine interface design techniques and philosophies that effectively solve these problems.

Wutke, John R.

1991-03-01

5

Automated Modelling of LonWorks Building Automation Networks  

Microsoft Academic Search

Abstract: Developing building automation systems requires carefulplanning of the applications and the network topology.Editing a model with up to 32,000 nodes manually is verytime-consuming. In this paper an automated approachfor modeling LonWorks networks is presented. As a basisthe existing LNS Network Operating System which issuited for integration and management purposes is used.

M. Neugebauer; Joern Ploennigs; K. Kabitzsch

2004-01-01

6

Automation in teleoperation from a man-machine interface viewpoint  

NASA Technical Reports Server (NTRS)

Teleoperation can be defined as the use of robotic devices having mobility, manipulative and some sensing capabilities, and remotely controlled by a human operator. The purpose of this paper is to discuss and exemplify technology issues related to the use of robots as man-extension or teleoperator systems in space. The main thrust of the paper is focused at research and development in the area of sensing- and computer-based automation from the viewpoint of man-machine interface devices and techniques. The objective of this R and D effort is to render space teleoperation efficient and safe through the use of devices and techniques which will permit integrated and task-level ('intelligent') two-way control communication between human operator and teleoperator machine in earth orbit.

Bejczy, A. K.; Corker, K.

1984-01-01

7

Automated modeling of LonWorks building automation networks  

Microsoft Academic Search

Developing building automation systems requires careful planning of the applications and the network topology. Editing a model with up to 32,000 nodes manually is very time-consuming. In this paper, an automated approach for modeling LonWorks networks is presented. As a basis the existing LNS network operating system which is suited for integration and management purposes is used. It contains all

Mario Neugebauer; Jorn Plonnigs; Klaus Kabitzsch; Peter Buchholz

2004-01-01

8

The state of the art in automating usability evaluation of user interfaces  

Microsoft Academic Search

Usability evaluation is an increasingly important part of the user interface design process. However, usability evaluation can be expensive in terms of time and human resources, and automation is therefore a promising way to augment existing approaches. This article presents an extensive survey of usability evaluation methods, organized according to a new taxonomy that emphasizes the role of automation. The

Melody Y. Ivory; Marti A. Hearst

2001-01-01

9

Automated parking garage system model  

NASA Technical Reports Server (NTRS)

A one-twenty-fifth scale model of the key components of an automated parking garage system is described. The design of the model required transferring a vehicle from an entry level, vertically (+Z, -Z), to a storage location at any one of four storage positions (+X, -X, +Y, +Y, -Y) on the storage levels. There are three primary subsystems: (1) a screw jack to provide the vertical motion of the elevator, (2) a cam-driven track-switching device to provide X to Y motion, and (3) a transfer cart to provide horizontal travel and a small amount to vertical motion for transfer to the storage location. Motive power is provided by dc permanent magnet gear motors, one each for the elevator and track switching device and two for the transfer cart drive system (one driving the cart horizontally and the other providing the vertical transfer). The control system, through the use of a microprocessor, provides complete automation through a feedback system which utilizes sensing devices.

Collins, E. R., Jr.

1975-01-01

10

On Abstractions and Simplifications in the Design of Human-Automation Interfaces  

NASA Technical Reports Server (NTRS)

This report addresses the design of human-automation interaction from a formal perspective that focuses on the information content of the interface, rather than the design of the graphical user interface. It also addresses the issue of the information provided to the user (e.g., user-manuals, training material, and all other resources). In this report, we propose a formal procedure for generating interfaces and user-manuals. The procedure is guided by two criteria: First, the interface must be correct, that is, with the given interface the user will be able to perform the specified tasks correctly. Second, the interface should be succinct. The report discusses the underlying concepts and the formal methods for this approach. Two examples are used to illustrate the procedure. The algorithm for constructing interfaces can be automated, and a preliminary software system for its implementation has been developed.

Heymann, Michael; Degani, Asaf; Clancy, Daniel (Technical Monitor)

2002-01-01

11

Automated creation of a forms-based database query interface  

Microsoft Academic Search

Forms-based query interfaces are widely used to access databases today. The design of a forms-based interface is often a key step in the deployment of a database. Each form in such an interface is capable of expressing only a very limited range of queries. Ide- ally, the set of forms as a whole must be able to express all pos-

Magesh Jayapandian; H. V. Jagadish

2008-01-01

12

User interface design for an automated part recognition system  

E-print Network

5. 45 50 5 e o 4 Iu 3 t- TASK TYPE ~ Cahbration m Identification Menu- Mouse Menu- Button- Button- Keypad- UnMouse Touch Mouse UnMouse INTERFACE TYPE Figure 19. Means and standard deviations for Time. 51 50 40 rn g So IL 0 ir... the five interfaces. The interfaces investigated are described below. One interface utilized a menu command layout with a mouse for command selection (Menu ? Mouse interface) . In another, commands placed on screen buttons were selected using a touch...

Avitts, Tommie Annette

1991-01-01

13

SWISS-MODEL: an automated protein homology-modeling server  

Microsoft Academic Search

SWISS-MODEL (http:\\/\\/swissmodel.expasy.org) is a server for automated comparative modeling of three- dimensional (3D) protein structures. It pioneered the field of automated modeling starting in 1993 and is the most widely-used free web-based automated modeling facility today. In 2002 the server computed 120 000 user requests for 3D protein models. SWISS- MODEL provides several levels of user interaction through its World

Torsten Schwede; Jürgen Kopp; Nicolas Guex; Manuel C. Peitsch

2003-01-01

14

Model-Based Design of Air Traffic Controller-Automation Interaction  

NASA Technical Reports Server (NTRS)

A model of controller and automation activities was used to design the controller-automation interactions necessary to implement a new terminal area air traffic management concept. The model was then used to design a controller interface that provides the requisite information and functionality. Using data from a preliminary study, the Crew Activity Tracking System (CATS) was used to help validate the model as a computational tool for describing controller performance.

Romahn, Stephan; Callantine, Todd J.; Palmer, Everett A.; Null, Cynthia H. (Technical Monitor)

1998-01-01

15

Automated, Parametric Geometry Modeling and Grid Generation for Turbomachinery Applications  

NASA Technical Reports Server (NTRS)

The objective of this Phase I project is to develop a highly automated software system for rapid geometry modeling and grid generation for turbomachinery applications. The proposed system features a graphical user interface for interactive control, a direct interface to commercial CAD/PDM systems, support for IGES geometry output, and a scripting capability for obtaining a high level of automation and end-user customization of the tool. The developed system is fully parametric and highly automated, and, therefore, significantly reduces the turnaround time for 3D geometry modeling, grid generation and model setup. This facilitates design environments in which a large number of cases need to be generated, such as for parametric analysis and design optimization of turbomachinery equipment. In Phase I we have successfully demonstrated the feasibility of the approach. The system has been tested on a wide variety of turbomachinery geometries, including several impellers and a multi stage rotor-stator combination. In Phase II, we plan to integrate the developed system with turbomachinery design software and with commercial CAD/PDM software.

Harrand, Vincent J.; Uchitel, Vadim G.; Whitmire, John B.

2000-01-01

16

Cooperative control - The interface challenge for men and automated machines  

NASA Technical Reports Server (NTRS)

The research issues associated with the increasing autonomy and independence of machines and their evolving relationships to human beings are explored. The research, conducted by Langley Research Center (LaRC), will produce a new social work order in which the complementary attributes of robots and human beings, which include robots' greater strength and precision and humans' greater physical and intellectual dexterity, are necessary for systems of cooperation. Attention is given to the tools for performing the research, including the Intelligent Systems Research Laboratory (ISRL) and industrial manipulators, as well as to the research approaches taken by the Automation Technology Branch (ATB) of LaRC to achieve high automation levels. The ATB is focusing on artificial intelligence research through DAISIE, a system which tends to organize its environment into hierarchical controller/planner abstractions.

Hankins, W. W., III; Orlando, N. E.

1984-01-01

17

The State of the Art in Automating Usability Evaluation of User Interfaces  

E-print Network

The State of the Art in Automating Usability Evaluation of User Interfaces MELODY Y. IVORY fellowship, and Kaiser Permanente. Authors' addresses: M. Y. Ivory, Computer Science Division, University of California, Berkeley, Berkeley, CA 94720-1776; email: ivory@CS.Berkeley.edu; M. A. Hearst, School

Hearst, Marti

18

An Automated System for Converting App Inventor Apps to Java Interface For Creating and Managing Projects  

E-print Network

" [1]. The App Inventor project was started as a research project by Google, the principle comercial://googleblog.blogspot.com/ 2010/07/app-inventor-for-android.html [3] http://www.appinventor.mit.edu/ #12;An Automated System for Converting App Inventor Apps to Java Interface For Creating and Managing

Gray, Jeffrey G.

19

The interfacing technology of PC-based factory automation systems  

Microsoft Academic Search

The purpose of this paper is to use a 4 axis servo card to design a very friendly man-machine interface to set up a practical PC based industrial controller system. We also introduced a novel pulse generator ICPG9210 which is powerful in multi axis motion control of servo motors

Hung-Yuan Chung; Dar-Win Jang

1995-01-01

20

Automated EEG feature selection for brain computer interfaces  

Microsoft Academic Search

A brain computer interface (BCI) utilizes signals derived from electroencephalography (EEG) to establish a connection between a person's state of mind and a computer based signal processing system that interprets the EEG signals. The choice of suitable features of the available EEG signals is crucial for good BCI communication. The optimal set of features is strongly dependent on the subjects

Michael Schroder; Martin Bogdan; T. Hinterberger; N. Birbaumer

2003-01-01

21

Task-focused modeling in automated agriculture  

NASA Astrophysics Data System (ADS)

Machine vision systems analyze image data to carry out automation tasks. Our interest is in machine vision systems that rely on models to achieve their designed task. When the model is interrogated from an a priori menu of questions, the model need not be complete. Instead, the machine vision system can use a partial model that contains a large amount of information in regions of interest and less information elsewhere. We propose an adaptive modeling scheme for machine vision, called task-focused modeling, which constructs a model having just sufficient detail to carry out the specified task. The model is detailed in regions of interest to the task and is less detailed elsewhere. This focusing effect saves time and reduces the computational effort expended by the machine vision system. We illustrate task-focused modeling by an example involving real-time micropropagation of plants in automated agriculture.

Vriesenga, Mark R.; Peleg, K.; Sklansky, Jack

1993-01-01

22

Flexible software architecture for user-interface and machine control in laboratory automation.  

PubMed

We describe a modular, layered software architecture for automated laboratory instruments. The design consists of a sophisticated user interface, a machine controller and multiple individual hardware subsystems, each interacting through a client-server architecture built entirely on top of open Internet standards. In our implementation, the user-interface components are built as Java applets that are downloaded from a server integrated into the machine controller. The user-interface client can thereby provide laboratory personnel with a familiar environment for experiment design through a standard World Wide Web browser. Data management and security are seamlessly integrated at the machine-controller layer using QNX, a real-time operating system. This layer also controls hardware subsystems through a second client-server interface. This architecture has proven flexible and relatively easy to implement and allows users to operate laboratory automation instruments remotely through an Internet connection. The software architecture was implemented and demonstrated on the Acapella, an automated fluid-sample-processing system that is under development at the University of Washington. PMID:9793655

Arutunian, E B; Meldrum, D R; Friedman, N A; Moody, S E

1998-10-01

23

Trust Model for Security Automation Data 1.0 (TMSAD)  

E-print Network

Trust Model for Security Automation Data 1.0 (TMSAD) HaroldBooth AdamHalbardier NIST Interagency Report 7802 #12;NIST Interagency Report 7802 Trust Model for Security Automation Data 1.0 (TMSAD) Harold Interagency Report 7802 26 pages (September 2011) #12;TRUST MODEL FOR SECURITY AUTOMATION DATA 1.0 (TMSAD) iv

24

A Traffic Model for Networked Devices in the Building Automation  

Microsoft Academic Search

Traffic models play a decisive part in the performance evaluation and design of communications systems. But the growing diversification of devices in large networks asks for automated generated traffic models. In this paper we present a generic device model which is suited for automated generation in the domain of build- ing automation. The traffic is deduced successive for com- mon

Joern Ploennigs; Mario Neugebauer; Klaus Kabitzsch

2004-01-01

25

A traffic model for networked devices in the building automation  

Microsoft Academic Search

Traffic models play a decisive part in the performance evaluation and design of communications systems. However, the growing diversification of devices in large networks asks for automated generated traffic models. In this paper, we present a generic device model which is suited for automated generation in the domain of building automation. The traffic is deduced successive for common devices from

Jorn Plonnigs; Mario Neugebauer; Klaus Kabitzsch

2004-01-01

26

Design Through Manufacturing: The Solid Model - Finite Element Analysis Interface  

NASA Technical Reports Server (NTRS)

State-of-the-art computer aided design (CAD) presently affords engineers the opportunity to create solid models of machine parts which reflect every detail of the finished product. Ideally, these models should fulfill two very important functions: (1) they must provide numerical control information for automated manufacturing of precision parts, and (2) they must enable analysts to easily evaluate the stress levels (using finite element analysis - FEA) for all structurally significant parts used in space missions. Today's state-of-the-art CAD programs perform function (1) very well, providing an excellent model for precision manufacturing. But they do not provide a straightforward and simple means of automating the translation from CAD to FEA models, especially for aircraft-type structures. The research performed during the fellowship period investigated the transition process from the solid CAD model to the FEA stress analysis model with the final goal of creating an automatic interface between the two. During the period of the fellowship a detailed multi-year program for the development of such an interface was created. The ultimate goal of this program will be the development of a fully parameterized automatic ProE/FEA translator for parts and assemblies, with the incorporation of data base management into the solution, and ultimately including computational fluid dynamics and thermal modeling in the interface.

Rubin, Carol

2003-01-01

27

Automated two-dimensional interface for capillary gas chromatography  

DOEpatents

A multidimensional gas chromatograph (GC) system is disclosed which has wide bore capillary and narrow bore capillary GC columns in series and has a novel system interface. Heart cuts from a high flow rate sample, separated by a wide bore GC column, are collected and directed to a narrow bore GC column with carrier gas injected at a lower flow compatible with a mass spectrometer. A bimodal six-way valve is connected with the wide bore GC column outlet and a bimodal four-way valve is connected with the narrow bore GC column inlet. A trapping and retaining circuit with a cold trap is connected with the six-way valve and a transfer circuit interconnects the two valves. The six-way valve is manipulated between first and second mode positions to collect analyte, and the four-way valve is manipulated between third and fourth mode positions to allow carrier gas to sweep analyte from a deactivated cold trap, through the transfer circuit, and then to the narrow bore GC capillary column for separation and subsequent analysis by a mass spectrometer. Rotary valves have substantially the same bore width as their associated columns to minimize flow irregularities and resulting sample peak deterioration. The rotary valves are heated separately from the GC columns to avoid temperature lag and resulting sample deterioration. 3 figs.

Strunk, M.R.; Bechtold, W.E.

1996-02-20

28

Automated two-dimensional interface for capillary gas chromatography  

DOEpatents

A multidimensional gas chromatograph (GC) system having wide bore capillary and narrow bore capillary GC columns in series and having a novel system interface. Heart cuts from a high flow rate sample, separated by a wide bore GC column, are collected and directed to a narrow bore GC column with carrier gas injected at a lower flow compatible with a mass spectrometer. A bimodal six-way valve is connected with the wide bore GC column outlet and a bimodal four-way valve is connected with the narrow bore GC column inlet. A trapping and retaining circuit with a cold trap is connected with the six-way valve and a transfer circuit interconnects the two valves. The six-way valve is manipulated between first and second mode positions to collect analyte, and the four-way valve is manipulated between third and fourth mode positions to allow carrier gas to sweep analyte from a deactivated cold trap, through the transfer circuit, and then to the narrow bore GC capillary column for separation and subsequent analysis by a mass spectrometer. Rotary valves have substantially the same bore width as their associated columns to minimize flow irregularities and resulting sample peak deterioration. The rotary valves are heated separately from the GC columns to avoid temperature lag and resulting sample deterioration.

Strunk, Michael R. (Albuquerque, NM); Bechtold, William E. (Albuquerque, NM)

1996-02-20

29

RCrane: semi-automated RNA model building  

PubMed Central

RNA crystals typically diffract to much lower resolutions than protein crystals. This low-resolution diffraction results in unclear density maps, which cause considerable difficulties during the model-building process. These difficulties are exacerbated by the lack of computational tools for RNA modeling. Here, RCrane, a tool for the partially automated building of RNA into electron-density maps of low or intermediate resolution, is presented. This tool works within Coot, a common program for macromolecular model building. RCrane helps crystallographers to place phosphates and bases into electron density and then automatically predicts and builds the detailed all-atom structure of the traced nucleotides. RCrane then allows the crystallographer to review the newly built structure and select alternative backbone conformations where desired. This tool can also be used to automatically correct the backbone structure of previously built nucleotides. These automated corrections can fix incorrect sugar puckers, steric clashes and other structural problems. PMID:22868764

Keating, Kevin S.; Pyle, Anna Marie

2012-01-01

30

Building Project Model Support for Automated Labor Monitoring  

E-print Network

prone. Consequently, an automated model for monitoring labor inputs, based on automated data collection of project performance indicators, such as cost, schedule, labor productivity, materials consumption or wasteBuilding Project Model Support for Automated Labor Monitoring R. Sacks1 ; R. Navon2 ; and E

Sacks, Rafael

31

Automating risk analysis of software design models.  

PubMed

The growth of the internet and networked systems has exposed software to an increased amount of security threats. One of the responses from software developers to these threats is the introduction of security activities in the software development lifecycle. This paper describes an approach to reduce the need for costly human expertise to perform risk analysis in software, which is common in secure development methodologies, by automating threat modeling. Reducing the dependency on security experts aims at reducing the cost of secure development by allowing non-security-aware developers to apply secure development with little to no additional cost, making secure development more accessible. To automate threat modeling two data structures are introduced, identification trees and mitigation trees, to identify threats in software designs and advise mitigation techniques, while taking into account specification requirements and cost concerns. These are the components of our model for automated threat modeling, AutSEC. We validated AutSEC by implementing it in a tool based on data flow diagrams, from the Microsoft security development methodology, and applying it to VOMS, a grid middleware component, to evaluate our model's performance. PMID:25136688

Frydman, Maxime; Ruiz, Guifré; Heymann, Elisa; César, Eduardo; Miller, Barton P

2014-01-01

32

Automating Risk Analysis of Software Design Models  

PubMed Central

The growth of the internet and networked systems has exposed software to an increased amount of security threats. One of the responses from software developers to these threats is the introduction of security activities in the software development lifecycle. This paper describes an approach to reduce the need for costly human expertise to perform risk analysis in software, which is common in secure development methodologies, by automating threat modeling. Reducing the dependency on security experts aims at reducing the cost of secure development by allowing non-security-aware developers to apply secure development with little to no additional cost, making secure development more accessible. To automate threat modeling two data structures are introduced, identification trees and mitigation trees, to identify threats in software designs and advise mitigation techniques, while taking into account specification requirements and cost concerns. These are the components of our model for automated threat modeling, AutSEC. We validated AutSEC by implementing it in a tool based on data flow diagrams, from the Microsoft security development methodology, and applying it to VOMS, a grid middleware component, to evaluate our model's performance. PMID:25136688

Ruiz, Guifré; Heymann, Elisa; César, Eduardo; Miller, Barton P.

2014-01-01

33

CollageMachine: Model of ``Interface Ecology''  

E-print Network

CollageMachine: Model of ``Interface Ecology'' By Andruid Kerne dissertation submitted partial addresses browsing creatively, been co­developed with the metadisciplinary framework interface ecology, in addition inside them, open process without definite bounds. a metadiscipline, interface ecology brings

Mohri, Mehryar

34

A Generalized Timeline Representation, Services, and Interface for Automating Space Mission Operations  

NASA Technical Reports Server (NTRS)

Most use a timeline based representation for operations modeling. Most model a core set of state, resource types. Most provide similar capabilities on this modeling to enable (semi) automated schedule generation. In this paper we explore the commonality of : representation and services for these timelines. These commonalities offer potential to be harmonized to enable interoperability, re-use.

Chien, Steve; Johnston, Mark; Frank, Jeremy; Giuliano, Mark; Kavelaars, Alicia; Lenzen, Christoph; Policella, Nicola

2012-01-01

35

Automated dynamic analytical model improvement  

NASA Technical Reports Server (NTRS)

A method is developed and illustrated which finds minimum changes in analytical mass and stiffness matrices to make them consistent with a set of measured normal modes and natural frequencies. The corrected model is an improved base for studies of physical changes, changes in boundary conditions, and for prediction of forced responses. Features of the method are: efficient procedures not requiring solutions of the eigenproblem; the model may have more degrees of freedom than the test data; modal displacements at all the analytical degrees of freedom are obtained; the frequency dependence of the coordinate transformations are properly treated.

Berman, A.

1981-01-01

36

Graspable Interfaces as Tool for Cooperative Modelling  

Microsoft Academic Search

This article explains the concept of graspable interfaces and analyses their potential as tool for cooperative modelling. It examines positive effects of graspable models on social interaction and presents a model how these effects relate with prop- erties and key characteristics of graspable interfaces. My hypothesis is that these effects result from the key characteristics. Results from a video analysis

Eva Hornecker

37

Automating Model Transformations and Refactoring for Goal-Oriented Models  

E-print Network

Automating Model Transformations and Refactoring for Goal-Oriented Models Promoteur: Axel van Lamsweerde Louvain-la-Neuve Année académique 2009 ­ 2010 #12;#12;Acknowledgments Iam indebted to my supervisor, Axel as the long discussions we had, signi cantly improved the quality of this work. I thank Richard Jones for his

Bonaventure, Olivier

38

A diffuse interface model with immiscibility preservation  

SciTech Connect

A new, simple, and computationally efficient interface capturing scheme based on a diffuse interface approach is presented for simulation of compressible multiphase flows. Multi-fluid interfaces are represented using field variables (interface functions) with associated transport equations that are augmented, with respect to an established formulation, to enforce a selected interface thickness. The resulting interface region can be set just thick enough to be resolved by the underlying mesh and numerical method, yet thin enough to provide an efficient model for dynamics of well-resolved scales. A key advance in the present method is that the interface regularization is asymptotically compatible with the thermodynamic mixture laws of the mixture model upon which it is constructed. It incorporates first-order pressure and velocity non-equilibrium effects while preserving interface conditions for equilibrium flows, even within the thin diffused mixture region. We first quantify the improved convergence of this formulation in some widely used one-dimensional configurations, then show that it enables fundamentally better simulations of bubble dynamics. Demonstrations include both a spherical-bubble collapse, which is shown to maintain excellent symmetry despite the Cartesian mesh, and a jetting bubble collapse adjacent a wall. Comparisons show that without the new formulation the jet is suppressed by numerical diffusion leading to qualitatively incorrect results.

Tiwari, Arpit, E-mail: atiwari2@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)] [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Pantano, Carlos [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)] [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2013-11-01

39

Model compilation: An approach to automated model derivation  

NASA Technical Reports Server (NTRS)

An approach is introduced to automated model derivation for knowledge based systems. The approach, model compilation, involves procedurally generating the set of domain models used by a knowledge based system. With an implemented example, how this approach can be used to derive models of different precision and abstraction is illustrated, and models are tailored to different tasks, from a given set of base domain models. In particular, two implemented model compilers are described, each of which takes as input a base model that describes the structure and behavior of a simple electromechanical device, the Reaction Wheel Assembly of NASA's Hubble Space Telescope. The compilers transform this relatively general base model into simple task specific models for troubleshooting and redesign, respectively, by applying a sequence of model transformations. Each transformation in this sequence produces an increasingly more specialized model. The compilation approach lessens the burden of updating and maintaining consistency among models by enabling their automatic regeneration.

Keller, Richard M.; Baudin, Catherine; Iwasaki, Yumi; Nayak, Pandurang; Tanaka, Kazuo

1990-01-01

40

Automated model generation for performance engineering of building automation networks  

Microsoft Academic Search

Large technical systems need to be designed both reliable and efficient. Specialized design tools offer therefore a simplified,\\u000a abstract design and extend details autonomously in the background. Analytic and simulation based models could improve the\\u000a quality by testing and dimensioning the design before implementation, but setting up the necessary models is time-consuming\\u000a and expensive. Therefore many developers ask for analysis

Joern Ploennigs; Mario Neugebauer; Klaus Kabitzsch

2006-01-01

41

Modeling strategic behavior in human-automation interaction - Why an 'aid' can (and should) go unused  

NASA Technical Reports Server (NTRS)

Task-offload aids (e.g., an autopilot, an 'intelligent' assistant) can be selectively engaged by the human operator to dynamically delegate tasks to automation. Introducing such aids eliminates some task demands but creates new ones associated with programming, engaging, and disengaging the aiding device via an interface. The burdens associated with managing automation can sometimes outweigh the potential benefits of automation to improved system performance. Aid design parameters and features of the overall multitask context combine to determine whether or not a task-offload aid will effectively support the operator. A modeling and sensitivity analysis approach is presented that identifies effective strategies for human-automation interaction as a function of three task-context parameters and three aid design parameters. The analysis and modeling approaches provide resources for predicting how a well-adapted operator will use a given task-offload aid, and for specifying aid design features that ensure that automation will provide effective operator support in a multitask environment.

Kirlik, Alex

1993-01-01

42

Modeling strategic behavior in human-automation interaction: why an "aid" can (and should) go unused.  

PubMed

Task-offload aids (e.g., an autopilot, an "intelligent" assistant) can be selectively engaged by the human operator to dynamically delegate tasks to automation. Introducing such aids eliminates some task demands but creates new ones associated with programming, engaging, and disengaging the aiding device via an interface. The burdens associated with managing automation can sometimes outweigh the potential benefits of automation to improved system performance. Aid design parameters and features of the overall multitask context combine to determine whether or not a task-offload aid will effectively support the operator. A modeling and sensitivity analysis approach is presented that identifies effective strategies for human-automation interaction as a function of three task-context parameters and three aid design parameters. The analysis and modeling approaches provide resources for predicting how a well-adapted operator will use a given task-offload aid, and for specifying aid design features that ensure that automation will provide effective operator support in a multitask environment. PMID:8349287

Kirlik, A

1993-06-01

43

Modeling and Extracting Deep-Web Query Interfaces  

Microsoft Academic Search

Interface modeling & extraction is a fundamental step in building a uni- form query interface to a multitude of databases on the Web. Existing solutions are limited in that they assume interfaces are flat and thus ignore the inherent struc- ture of interfaces, which then seriously hampers the effectiveness of interface in- tegration. To address this limitation, in this chapter,

Wensheng Wu; AnHai Doan; Clement T. Yu; Weiyi Meng

2009-01-01

44

Statistical modeling of shock-interface interaction  

NASA Astrophysics Data System (ADS)

Direct simulations of shock-induced mixing of corrugated air-helium interfaces have been performed using EAD, a 2D Eulerian code with a mixed-cell treatment. The total amount of fluctuating kinetic energy produced before the shock ( M = 1.2-1.3 in air) leaves the interface can be expressed as a function of interface variance (rms amplitude) and is in qualitative agreement with a theoretical estimate. By reducing the 2D results into 1D profiles, we have also been able to favorably compare the mixing rates and intensities computed by EAD and those predicted by a turbulence transport model with some of its closures based on two-field expressions. The results of this study supply reasonable values for initialization of fully developed turbulence models, such as k - ? and its extensions, for problems involving shock-induced interfacial mixing.

Besnard, D. C.; Haas, J. F.; Rauenzahn, R. M.

1989-07-01

45

An interface tracking model for droplet electrocoalescence.  

SciTech Connect

This report describes an Early Career Laboratory Directed Research and Development (LDRD) project to develop an interface tracking model for droplet electrocoalescence. Many fluid-based technologies rely on electrical fields to control the motion of droplets, e.g. microfluidic devices for high-speed droplet sorting, solution separation for chemical detectors, and purification of biodiesel fuel. Precise control over droplets is crucial to these applications. However, electric fields can induce complex and unpredictable fluid dynamics. Recent experiments (Ristenpart et al. 2009) have demonstrated that oppositely charged droplets bounce rather than coalesce in the presence of strong electric fields. A transient aqueous bridge forms between approaching drops prior to pinch-off. This observation applies to many types of fluids, but neither theory nor experiments have been able to offer a satisfactory explanation. Analytic hydrodynamic approximations for interfaces become invalid near coalescence, and therefore detailed numerical simulations are necessary. This is a computationally challenging problem that involves tracking a moving interface and solving complex multi-physics and multi-scale dynamics, which are beyond the capabilities of most state-of-the-art simulations. An interface-tracking model for electro-coalescence can provide a new perspective to a variety of applications in which interfacial physics are coupled with electrodynamics, including electro-osmosis, fabrication of microelectronics, fuel atomization, oil dehydration, nuclear waste reprocessing and solution separation for chemical detectors. We present a conformal decomposition finite element (CDFEM) interface-tracking method for the electrohydrodynamics of two-phase flow to demonstrate electro-coalescence. CDFEM is a sharp interface method that decomposes elements along fluid-fluid boundaries and uses a level set function to represent the interface.

Erickson, Lindsay Crowl

2013-09-01

46

Designing for Flexible Interaction Between Humans and Automation: Delegation Interfaces for Supervisory Control  

Microsoft Academic Search

Objective: To develop a method enabling human-like, flexible supervisory control via delegation to automation. Background: Real-time supervisory relationships with automation are rarely as flexible as human task delegation to other humans. Flexibility in human-adaptable automation can provide important benefits, includ- ing improved situation awareness, more accurate automation usage, more balanced mental workload, increased user acceptance, and improved overall performance. Method:

Christopher A. Miller; Raja Parasuraman

2007-01-01

47

Automating a human factors evaluation of graphical user interfaces for NASA applications: An update on CHIMES  

NASA Technical Reports Server (NTRS)

Capturing human factors knowledge about the design of graphical user interfaces (GUI's) and applying this knowledge on-line are the primary objectives of the Computer-Human Interaction Models (CHIMES) project. The current CHIMES prototype is designed to check a GUI's compliance with industry-standard guidelines, general human factors guidelines, and human factors recommendations on color usage. Following the evaluation, CHIMES presents human factors feedback and advice to the GUI designer. The paper describes the approach to modeling human factors guidelines, the system architecture, a new method developed to convert quantitative RGB primaries into qualitative color representations, and the potential for integrating CHIMES with user interface management systems (UIMS). Both the conceptual approach and its implementation are discussed. This paper updates the presentation on CHIMES at the first International Symposium on Ground Data Systems for Spacecraft Control.

Jiang, Jian-Ping; Murphy, Elizabeth D.; Bailin, Sidney C.; Truszkowski, Walter F.

1993-01-01

48

The design of the computer-human interface of integrated resource management automation (IRMA)  

E-print Network

device, such as a mouse, for manipulation of objects on the terminal screen. 2 Direct manipulation systems have become the choice of interface styles for a number of designers. This is shown through Ledgard's (as presented by Whiteside et a1. 2... directly manipulate objects, would be easier to use than command systems, which require users to memorize command structure. This thesis is modeled after Computer. 2) An environment which incorporates familiar settings will be easier to learn than one...

Holtfrerich, David Russell

2012-06-07

49

Development and Design of a User Interface for a Computer Automated Heating, Ventilation, and Air Conditioning System  

SciTech Connect

A user interface is created to monitor and operate the heating, ventilation, and air conditioning system. The interface is networked to the system's programmable logic controller. The controller maintains automated control of the system. The user through the interface is able to see the status of the system and override or adjust the automatic control features. The interface is programmed to show digital readouts of system equipment as well as visual queues of system operational statuses. It also provides information for system design and component interaction. The interface is made easier to read by simple designs, color coordination, and graphics. Fermi National Accelerator Laboratory (Fermi lab) conducts high energy particle physics research. Part of this research involves collision experiments with protons, and anti-protons. These interactions are contained within one of two massive detectors along Fermilab's largest particle accelerator the Tevatron. The D-Zero Assembly Building houses one of these detectors. At this time detector systems are being upgraded for a second experiment run, titled Run II. Unlike the previous run, systems at D-Zero must be computer automated so operators do not have to continually monitor and adjust these systems during the run. Human intervention should only be necessary for system start up and shut down, and equipment failure. Part of this upgrade includes the heating, ventilation, and air conditioning system (HVAC system). The HVAC system is responsible for controlling two subsystems, the air temperatures of the D-Zero Assembly Building and associated collision hall, as well as six separate water systems used in the heating and cooling of the air and detector components. The BYAC system is automated by a programmable logic controller. In order to provide system monitoring and operator control a user interface is required. This paper will address methods and strategies used to design and implement an effective user interface. Background material pertinent to the BYAC system will cover the separate water and air subsystems and their purposes. In addition programming and system automation will also be covered.

Anderson, B.; /Fermilab

1999-10-08

50

Automation Marketplace 2010: New Models, Core Systems  

ERIC Educational Resources Information Center

In a year when a difficult economy presented fewer opportunities for immediate gains, the major industry players have defined their business strategies with fundamentally different concepts of library automation. This is no longer an industry where companies compete on the basis of the best or the most features in similar products but one where…

Breeding, Marshall

2010-01-01

51

Interface dynamics in planar neural field models  

PubMed Central

Neural field models describe the coarse-grained activity of populations of interacting neurons. Because of the laminar structure of real cortical tissue they are often studied in two spatial dimensions, where they are well known to generate rich patterns of spatiotemporal activity. Such patterns have been interpreted in a variety of contexts ranging from the understanding of visual hallucinations to the generation of electroencephalographic signals. Typical patterns include localized solutions in the form of traveling spots, as well as intricate labyrinthine structures. These patterns are naturally defined by the interface between low and high states of neural activity. Here we derive the equations of motion for such interfaces and show, for a Heaviside firing rate, that the normal velocity of an interface is given in terms of a non-local Biot-Savart type interaction over the boundaries of the high activity regions. This exact, but dimensionally reduced, system of equations is solved numerically and shown to be in excellent agreement with the full nonlinear integral equation defining the neural field. We develop a linear stability analysis for the interface dynamics that allows us to understand the mechanisms of pattern formation that arise from instabilities of spots, rings, stripes and fronts. We further show how to analyze neural field models with linear adaptation currents, and determine the conditions for the dynamic instability of spots that can give rise to breathers and traveling waves. PMID:22655970

2012-01-01

52

Variational Implicit Solvation with Solute Molecular Mechanics: From Diffuse-Interface to Sharp-Interface Models  

PubMed Central

Central in a variational implicit-solvent description of biomolecular solvation is an effective free-energy functional of the solute atomic positions and the solute-solvent interface (i.e., the dielectric boundary). The free-energy functional couples together the solute molecular mechanical interaction energy, the solute-solvent interfacial energy, the solute-solvent van der Waals interaction energy, and the electrostatic energy. In recent years, the sharp-interface version of the variational implicit-solvent model has been developed and used for numerical computations of molecular solvation. In this work, we propose a diffuse-interface version of the variational implicit-solvent model with solute molecular mechanics. We also analyze both the sharp-interface and diffuse-interface models. We prove the existence of free-energy minimizers and obtain their bounds. We also prove the convergence of the diffuse-interface model to the sharp-interface model in the sense of ?-convergence. We further discuss properties of sharp-interface free-energy minimizers, the boundary conditions and the coupling of the Poisson–Boltzmann equation in the diffuse-interface model, and the convergence of forces from diffuse-interface to sharp-interface descriptions. Our analysis relies on the previous works on the problem of minimizing surface areas and on our observations on the coupling between solute molecular mechanical interactions with the continuum solvent. Our studies justify rigorously the self consistency of the proposed diffuse-interface variational models of implicit solvation. PMID:24058213

Li, Bo; Zhao, Yanxiang

2013-01-01

53

Automated Segmentation of Multiple Sclerosis Lesions by Model Outlier Detection  

Microsoft Academic Search

This paper presents a fully automated algorithm for segmentation of multiple sclerosis (MS) lesions from multispec- tral magnetic resonance (MR) images. The method performs inten- sity-based tissue classification using a stochastic model for normal brain images and simultaneously detects MS lesions as outliers that are not well explained by the model. It corrects for MR field in- homogeneities, estimates tissue-specific

Koen Van Leemput; Frederik Maes; Dirk Vandermeulen; Alan C. F. Colchester; Paul Suetens

2001-01-01

54

A power line data communication interface using spread spectrum technology in home automation  

Microsoft Academic Search

Building automation technology is rapidly developing towards more reliable communication systems, devices that control electronic equipments. These equipment if controlled leads to efficient energy management, and savings on the monthly electricity bill. Power Line communication (PLC) has been one of the dreams of the electronics industry for decades, especially for building automation. It is the purpose of this paper to

M. H. Shwehdi; A. Z. Khan

1996-01-01

55

Modeling the user in intelligent user interfaces  

SciTech Connect

A methodology for explicitly defining a model of a program's users and for evaluating the effectiveness of the user interface is presented. The development of an explicit user model will reduce user costs by both reducing the cost of software development and increasing user productivity. The components of the methodology are described, and an example of using the methodology in the development of an expert consultant system is given. The methodology can be useful in preliminary design and testing of such interactive software as electronic mail, information retrieval systems, editors, and management information systems.

Stoddard, M.L.; Douglass, R.J.

1983-01-01

56

Modelling Safe Interface Interactions in Web Applications  

NASA Astrophysics Data System (ADS)

Current Web applications embed sophisticated user interfaces and business logic. The original interaction paradigm of the Web based on static content pages that are browsed by hyperlinks is, therefore, not valid anymore. In this paper, we advocate a paradigm shift for browsers and Web applications, that improves the management of user interaction and browsing history. Pages are replaced by States as basic navigation nodes, and Back/Forward navigation along the browsing history is replaced by a full-fledged interactive application paradigm, supporting transactions at the interface level and featuring Undo/Redo capabilities. This new paradigm offers a safer and more precise interaction model, protecting the user from unexpected behaviours of the applications and the browser.

Brambilla, Marco; Cabot, Jordi; Grossniklaus, Michael

57

A model for types and levels of human interaction with automation  

Microsoft Academic Search

We outline a model for types and levels of automation that provides a framework and an objective basis for deciding which system functions should be automated and to what extent. Appropriate selection is important because automation does not merely supplant but changes human activity and can impose new coordination demands on the human operator. We propose that automation can be

Raja Parasuraman; Thomas B. Sheridan; Christopher D. Wickens

2000-01-01

58

AUTOMATED GEOSPATIAL WATERSHED ASSESSMENT (AGWA): A GIS-BASED HYRDOLOGIC MODELING TOOL FOR WATERSHED ASSESSMENT AND ANALYSIS  

EPA Science Inventory

The Automated Geospatial Watershed Assessment tool (AGWA) is a GIS interface jointly developed by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the University of Wyoming to automate the parame...

59

AUTOMATED MODELING OF 3D BUILDING ROOFS USING IMAGE AND LIDAR DATA  

E-print Network

AUTOMATED MODELING OF 3D BUILDING ROOFS USING IMAGE AND LIDAR DATA N. Demir* , E. Baltsavias, Detection, 3D Modelling ABSTRACT: In this work, an automated approach for 3D building roof modelling of accurate and complete 3D building models with high degree of automation. Aerial images and LiDAR data

Schindler, Konrad

60

ASPOGAMO: Automated Sports Game Analysis Models Michael Beetz1  

E-print Network

system including its computer vision subsystem that realizes the idea of automated sport game models games. They create new opportunities in sport science to get insights into the process instead for actions. Surveys of computer aided sport analysis are given in (Wang & Parameswaran, 2004b; Yu & Farin

Cremers, Daniel

61

Automated Target Recognition Using Passive Radar and Coordinated Flight Models  

E-print Network

approach to ATR compares the Radar Cross Section (RCS) of targets detected by a passive radar systemAutomated Target Recognition Using Passive Radar and Coordinated Flight Models Lisa M. Ehrman and Aaron D. Lanterman Center for Signal and Image Processing School of Electrical and Computer Engineering

Lanterman, Aaron

62

Modeling of aerosol deposition with interface devices.  

PubMed

Various approaches can be used to mathematically model the performance of different masks, mouthpieces, and aerosol delivery devices. The sophistication of such models can vary widely, from the use of simple algebraic empirical correlations to advanced computational fluid dynamics simulations. Bench-top testing is also often used to model aspects of devices, since it is difficult to capture certain aspects of device behavior with mathematical models. These various approaches to modeling differ in their limitations. Empirical correlations exist for predicting the effects of varying mouthpiece diameter and mouth-throat dimensions on extrathoracic losses, but are restricted to stable, nonballistic aerosols in certain flow rate ranges. Computational fluid dynamics (CFD) simulations that solve the Reynolds-averaged Navier-Stokes (RANS) equations typically require near-wall turbulence corrections in order to adequately model mouth-throat deposition, while Large Eddy Simulation (LES) removes this deficiency. Bench-top models that use replicas of the extrathoracic airways vary in their accuracy and generality in replicating the filtering properties of these airways. Choosing and using these various modeling approaches for evaluating patient-device interfaces requires knowledge of their merits and pitfalls, a brief discussion of which is given here. PMID:17411402

Finlay, W H; Martin, A R

2007-01-01

63

Computational design of patterned interfaces using reduced order models.  

PubMed

Patterning is a familiar approach for imparting novel functionalities to free surfaces. We extend the patterning paradigm to interfaces between crystalline solids. Many interfaces have non-uniform internal structures comprised of misfit dislocations, which in turn govern interface properties. We develop and validate a computational strategy for designing interfaces with controlled misfit dislocation patterns by tailoring interface crystallography and composition. Our approach relies on a novel method for predicting the internal structure of interfaces: rather than obtaining it from resource-intensive atomistic simulations, we compute it using an efficient reduced order model based on anisotropic elasticity theory. Moreover, our strategy incorporates interface synthesis as a constraint on the design process. As an illustration, we apply our approach to the design of interfaces with rapid, 1-D point defect diffusion. Patterned interfaces may be integrated into the microstructure of composite materials, markedly improving performance. PMID:25169868

Vattré, A J; Abdolrahim, N; Kolluri, K; Demkowicz, M J

2014-01-01

64

Radiation budget measurement/model interface  

NASA Technical Reports Server (NTRS)

This final report includes research results from the period February, 1981 through November, 1982. Two new results combine to form the final portion of this work. They are the work by Hanna (1982) and Stevens to successfully test and demonstrate a low-order spectral climate model and the work by Ciesielski et al. (1983) to combine and test the new radiation budget results from NIMBUS-7 with earlier satellite measurements. Together, the two related activities set the stage for future research on radiation budget measurement/model interfacing. Such combination of results will lead to new applications of satellite data to climate problems. The objectives of this research under the present contract are therefore satisfied. Additional research reported herein includes the compilation and documentation of the radiation budget data set a Colorado State University and the definition of climate-related experiments suggested after lengthy analysis of the satellite radiation budget experiments.

Vonderhaar, T. H.; Ciesielski, P.; Randel, D.; Stevens, D.

1983-01-01

65

Beyond Hacking: a Model Based Approach to User Interface Design  

Microsoft Academic Search

This paper discusses the role of models in the design of user interfaces, with particular emphasis on integration across different modelling stages. We are concerned with bridging the gap between psychologically motivated mod- elling approaches to HCI and implementation oriented interaction models, to produce a task-informed user interface design process. An early version of a UIDE which provides support for

S. Wilson; P. Johnson; C. Kelly; J. Cunningham; P. Markopoulos

1993-01-01

66

Hexapods with fieldbus interfaces for automated manufacturing of opto-mechanical components  

NASA Astrophysics Data System (ADS)

The adjustment of opto-mechanical components in manufacturing processes often requires precise motion in all six degrees of freedom with nanometer range resolution and absence of hysteresis. Parallel kinematic systems are predestined for such tasks due to their compact design, low inertia and high stiffness resulting in rapid settling behavior. To achieve adequate system performance, specialized motion controllers are required to handle the complex kinematic models for the different types of Hexapods and the associated extensive calculations of inverse kinematics. These controllers often rely on proprietary command languages, a fact that demands a high level of familiarization. This paper describes how the integration of fieldbus interfaces into Hexapod controllers simplifies the communication while providing higher flexibility. By using standardized communication protocols with cycle times down to 12.5 ?s it is straightforward to control multiple Hexapods and other devices by superordinate PLCs of different manufacturers. The paper also illustrates how to simplify adjustment and alignment processes by combining scanning algorithms with user defined coordinate systems.

Schreiber, Steffen; Muellerleile, Christian; Frietsch, Markus; Gloess, Rainer

2013-09-01

67

Elevator model based on a tiny PLC for teaching automation  

NASA Astrophysics Data System (ADS)

The development of control related applications requires knowledge of different subject matters like mechanical components, control equipment and physics. To understand the behavior of these heterogeneous applications is not easy especially the students who begin to study the electronic engineering. In order to introduce to them the most common components and skills necessary to put together a functioning automated system, we have designed a simple elevator model controlled by a PLC which was designed based on a microcontroller.

Kim, Kee Hwan; Lee, Young Dae

2005-12-01

68

INTERFACING ACOUSTIC MODELS WITH NATURAL LANGUAGE PROCESSING SYSTEMS  

E-print Network

INTERFACING ACOUSTIC MODELS WITH NATURAL LANGUAGE PROCESSING SYSTEMS Michael T. Johnson, Mary P recognition systems with natural language processing systems. The effectiveness of various pruning meth- ods systems with language models [2, 8]. Many systems integrate stochastic language models directly

Johnson, Michael T.

69

Models for Automated Earthmoving Howard Cannon  

E-print Network

and the terrain. In a large set of experiments we have con- ducted, we find that these models are accurate to automatically plan digging motions for excavators [11],[12]. Digging actions are described by a compact set

Singh, Sanjiv

70

Models for Automated Earthmoving Howard Cannon  

E-print Network

and the terrain. In a large set of experiments we have con­ ducted, we find that these models are accurate to automatically plan digging motions for excavators [11],[12]. Digging actions are described by a compact set

Singh, Sanjiv

71

Automated Environment Generation for Software Model Checking  

NASA Technical Reports Server (NTRS)

A key problem in model checking open systems is environment modeling (i.e., representing the behavior of the execution context of the system under analysis). Software systems are fundamentally open since their behavior is dependent on patterns of invocation of system components and values defined outside the system but referenced within the system. Whether reasoning about the behavior of whole programs or about program components, an abstract model of the environment can be essential in enabling sufficiently precise yet tractable verification. In this paper, we describe an approach to generating environments of Java program fragments. This approach integrates formally specified assumptions about environment behavior with sound abstractions of environment implementations to form a model of the environment. The approach is implemented in the Bandera Environment Generator (BEG) which we describe along with our experience using BEG to reason about properties of several non-trivial concurrent Java programs.

Tkachuk, Oksana; Dwyer, Matthew B.; Pasareanu, Corina S.

2003-01-01

72

Automated refinement and inference of analytical models for metabolic networks  

PubMed Central

The reverse engineering of metabolic networks from experimental data is traditionally a labor-intensive task requiring a priori systems knowledge. Using a proven model as a test system, we demonstrate an automated method to simplify this process by modifying an existing or related model – suggesting nonlinear terms and structural modifications – or even constructing a new model that agrees with the system’s time-series observations. In certain cases, this method can identify the full dynamical model from scratch without prior knowledge or structural assumptions. The algorithm selects between multiple candidate models by designing experiments to make their predictions disagree. We performed computational experiments to analyze a nonlinear seven-dimensional model of yeast glycolytic oscillations. This approach corrected mistakes reliably in both approximated and overspecified models. The method performed well to high levels of noise for most states, could identify the correct model de novo, and make better predictions than ordinary parametric regression and neural network models. We identified an invariant quantity in the model, which accurately derived kinetics and the numerical sensitivity coefficients of the system. Finally, we compared the system to dynamic flux estimation and discussed the scaling and application of this methodology to automated experiment design and control in biological systems in real-time. PMID:21832805

Schmidt, Michael D; Vallabhajosyula, Ravishankar R; Jenkins, Jerry W; Hood, Jonathan E; Soni, Abhishek S; Wikswo, John P; Lipson, Hod

2013-01-01

73

Automated refinement and inference of analytical models for metabolic networks.  

PubMed

The reverse engineering of metabolic networks from experimental data is traditionally a labor-intensive task requiring a priori systems knowledge. Using a proven model as a test system, we demonstrate an automated method to simplify this process by modifying an existing or related model--suggesting nonlinear terms and structural modifications--or even constructing a new model that agrees with the system's time series observations. In certain cases, this method can identify the full dynamical model from scratch without prior knowledge or structural assumptions. The algorithm selects between multiple candidate models by designing experiments to make their predictions disagree. We performed computational experiments to analyze a nonlinear seven-dimensional model of yeast glycolytic oscillations. This approach corrected mistakes reliably in both approximated and overspecified models. The method performed well to high levels of noise for most states, could identify the correct model de novo, and make better predictions than ordinary parametric regression and neural network models. We identified an invariant quantity in the model, which accurately derived kinetics and the numerical sensitivity coefficients of the system. Finally, we compared the system to dynamic flux estimation and discussed the scaling and application of this methodology to automated experiment design and control in biological systems in real time. PMID:21832805

Schmidt, Michael D; Vallabhajosyula, Ravishankar R; Jenkins, Jerry W; Hood, Jonathan E; Soni, Abhishek S; Wikswo, John P; Lipson, Hod

2011-10-01

74

Model-based User Interface Design Hallvard Trtteberg  

E-print Network

interface design was initiated by practical experi- ences with Lisp-based development environments at Center are particularly important when combining user-centered design with a model-based approach. The designModel-based User Interface Design Hallvard Trætteberg Email: hal@idi.ntnu.no Information Systems

75

Rapid Automated Aircraft Simulation Model Updating from Flight Data  

NASA Technical Reports Server (NTRS)

Techniques to identify aircraft aerodynamic characteristics from flight measurements and compute corrections to an existing simulation model of a research aircraft were investigated. The purpose of the research was to develop a process enabling rapid automated updating of aircraft simulation models using flight data and apply this capability to all flight regimes, including flight envelope extremes. The process presented has the potential to improve the efficiency of envelope expansion flight testing, revision of control system properties, and the development of high-fidelity simulators for pilot training.

Brian, Geoff; Morelli, Eugene A.

2011-01-01

76

Towards first principles modeling of electrochemical electrode-electrolyte interfaces  

NASA Astrophysics Data System (ADS)

We present a mini-perspective on the development of first principles modeling of electrochemical interfaces. We show that none of the existing methods deal with all the thermodynamic constraints that the electrochemical environment imposes on the structure of the interface. We present two directions forward to make the description more realistic and correct.

Nielsen, Malte; Björketun, Mårten E.; Hansen, Martin H.; Rossmeisl, Jan

2015-01-01

77

Automated Physico-Chemical Cell Model Development through Information Theory  

SciTech Connect

The objective of this project was to develop predictive models of the chemical responses of microbial cells to variations in their surroundings. The application of these models is optimization of environmental remediation and energy-producing biotechnical processes.The principles on which our project is based are as follows: chemical thermodynamics and kinetics; automation of calibration through information theory; integration of multiplex data (e.g. cDNA microarrays, NMR, proteomics), cell modeling, and bifurcation theory to overcome cellular complexity; and the use of multiplex data and information theory to calibrate and run an incomplete model. In this report we review four papers summarizing key findings and a web-enabled, multiple module workflow we have implemented that consists of a set of interoperable systems biology computational modules.

Peter J. Ortoleva

2005-11-29

78

A PREDICTIVE MODEL OF FLIGHT CREW PERFORMANCE IN AUTOMATED AIR TRAFFIC CONTROL AND FLIGHT MANAGEMENT OPERATIONS  

Microsoft Academic Search

This paper describes Air-MIDAS, a model of pilot performance in interaction with varied levels of automation in flight management operations. The model was used to predict the performance of a two person flight crew responding to clearance information generated by the Center TRACON Automation System (CTAS). The model represents the information requirements, decision processes, communication processes, and motor performance required

Gregory M. Pisanich; Kevin M. Corker

79

Modelling interfaces in SDL with gate types  

Microsoft Academic Search

This paper proposes a type concept for gates. Its introduction is motivated by the concept of interfaces, which is extensively used for the specification and implementation of open and dis- tributed systems. In the first place a pure syntactic extension for the current SDL gates is pre- sented enabling the definition of gate types and type based gates. In a

Eckhardt Holz

1999-01-01

80

Interfacing BIM with Building Thermal and Daylighting Modeling  

E-print Network

the BIM authoring tools’ Application Programming Interface (API) to translate BIM into Object-Oriented Physical Models (in Modelica) for building thermal simulation, and input files of ray-tracing software (Radiance) for daylighting simulation. Based...

Yan, Wei; Clayton, Mark; Haberl, Jeff; WoonSeong, Jeong; Bun Kim, Jong; Sandeep, Kota; Bermudez, Jose; Dixit, Manish

81

Stable, reproducible, and automated capillary zone electrophoresis-tandem mass spectrometry system with an electrokinetically pumped sheath-flow nanospray interface.  

PubMed

A PrinCE autosampler was coupled to a Q-Exactive mass spectrometer by an electrokinetically pumped sheath-flow nanospray interface to perform automated capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry (CZE-ESI-MS/MS). 20ng aliquots of an Escherichia coli digest were injected to evaluate the system. Eight sequential injections over an 8-h period identified 1115±70 (relative standard deviation, RSD=6%) peptides and 270±8 (RSD=3%) proteins per run. The average RSDs of migration time, peak intensity, and peak area were 3%, 24% and 19%, respectively, for 340 peptides with high intensity. This is the first report of an automated CZE-ESI-MS/MS system using the electrokinetically pumped sheath-flow nanospray interface. The results demonstrate that this system is capable of reproducibly identifying over 1000 peptides from an E. coli tryptic digest in a 1-h analysis time. PMID:24439510

Zhu, Guijie; Sun, Liangliang; Yan, Xiaojing; Dovichi, Norman J

2014-01-31

82

Stable, reproducible, and automated capillary zone electrophoresis-tandem mass spectrometry system with an electrokinetically pumped sheath-flow nanospray interface  

PubMed Central

A PrinCE autosampler was coupled to a Q-Exactive mass spectrometer by an electrokinetically pumped sheath-flow nanospray interface to perform automated capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry (CZE-ESI-MS/MS). 20 ng aliquots of an E. coli digest were injected to evaluate the system. Eight sequential injections over an eight-hour period identified 1,115 ± 70 (relative standard deviation, RSD = 6%) peptides and 270 ± 8 (RSD = 3%) proteins per run. The average RSDs of migration time, peak intensity, and peak area were 3%, 24% and 19% respectively, for 340 peptides with high intensity. This is the first report of an automated CZE-ESI-MS/MS system using the electrokinetically pumped sheath-flow nanospray interface. The results demonstrate that this system is capable of reproducibly identifying over 1,000 peptides from an E.coli tryptic digest in a one-hour analysis time. PMID:24439510

Zhu, Guijie; Sun, Liangliang; Yan, Xiaojing; Dovichi, Norman J.

2014-01-01

83

Development of an automated core model for nuclear reactors  

SciTech Connect

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop an automated package of computer codes that can model the steady-state behavior of nuclear-reactor cores of various designs. As an added benefit, data produced for steady-state analysis also can be used as input to the TRAC transient-analysis code for subsequent safety analysis of the reactor at any point in its operating lifetime. The basic capability to perform steady-state reactor-core analysis already existed in the combination of the HELIOS lattice-physics code and the NESTLE advanced nodal code. In this project, the automated package was completed by (1) obtaining cross-section libraries for HELIOS, (2) validating HELIOS by comparing its predictions to results from critical experiments and from the MCNP Monte Carlo code, (3) validating NESTLE by comparing its predictions to results from numerical benchmarks and to measured data from operating reactors, and (4) developing a linkage code to transform HELIOS output into NESTLE input.

Mosteller, R.D.

1998-12-31

84

Back to the Future: A Non-Automated Method of Constructing Transfer Models  

ERIC Educational Resources Information Center

Representing domain knowledge is important for constructing educational software, and automated approaches have been proposed to construct and refine such models. In this paper, instead of applying automated and computationally intensive approaches, we simply start with existing hand-constructed transfer models at various levels of granularity and…

Feng, Mingyu; Beck, Joseph

2009-01-01

85

A Comparison Study: Sketch-Based Interfaces versus WIMP Interfaces in Three Dimensional Modeling Tasks  

Microsoft Academic Search

Sketch-Based Interfaces are becoming a popular interaction style for many applications. The interaction style tries to recreate the experience of sketching that is similar to real paper and pencil drawings.They are being used to accomplish tasks related to geometric modeling, animation, architecture, design, music, and learning, among others. In this work we evaluate and compare two interaction approaches, Sketch and

Tiago Lemos De Araujo Machado; Alex Sandro Gomes; Marcelo Walter

2009-01-01

86

Automated geo/ortho registered aerial imagery product generation using the mapping system interface card (MSIC)  

NASA Astrophysics Data System (ADS)

The development concept paper for the MSIC system was first introduced in August 2012 by these authors. This paper describes the final assembly, testing, and commercial availability of the Mapping System Interface Card (MSIC). The 2.3kg MSIC is a self-contained, compact variable configuration, low cost real-time precision metadata annotator with embedded INS/GPS designed specifically for use in small aircraft. The MSIC was specifically designed to convert commercial-off-the-shelf (COTS) digital cameras and imaging/non-imaging spectrometers with Camera Link standard data streams into mapping systems for airborne emergency response and scientific remote sensing applications. COTS digital cameras and imaging/non-imaging spectrometers covering the ultraviolet through long-wave infrared wavelengths are important tools now readily available and affordable for use by emergency responders and scientists. The MSIC will significantly enhance the capability of emergency responders and scientists by providing a direct transformation of these important COTS sensor tools into low-cost real-time aerial mapping systems.

Bratcher, Tim; Kroutil, Robert; Lanouette, André; Lewis, Paul E.; Miller, David; Shen, Sylvia; Thomas, Mark

2013-05-01

87

Can diffuse-interface models quantitatively describe moving contact lines?  

NASA Astrophysics Data System (ADS)

The three-phase contact line is a long-standing problem in the physics and hydrodynamics of interfaces. The traditional sharp-interface Navier-Stokes formulation encounters a non-integrable stress singularity, which is commonly avoided by introducing slip at the contact line. In recent years, diffuse-interface models have emerged as an alternative method. They are attractive in regularizing the singularity in a more rational manner, and in the meantime supplying a means for describing the interfacial motion on the large scale. Although a number of groups have carried out diffuse-interface computations of moving contact lines, a closer inspection shows that some fundamental questions remain to be answered. For example, how can a sharp-interface limit be realized to produce a solution that is independent of the interfacial thickness? How to determine model parameters so as to match a specific experiment? Finally, is it possible to make quantitatively accurate predictions of the moving contact line using diffuse-interface models? Using the Cahn-Hilliard model as an example, we describe these issues and suggest solutions.

Yue, P.; Feng, J. J.

2011-08-01

88

Flightdeck Automation Problems (FLAP) Model for Safety Technology Portfolio Assessment  

NASA Technical Reports Server (NTRS)

NASA's Aviation Safety Program (AvSP) develops and advances methodologies and technologies to improve air transportation safety. The Safety Analysis and Integration Team (SAIT) conducts a safety technology portfolio assessment (PA) to analyze the program content, to examine the benefits and risks of products with respect to program goals, and to support programmatic decision making. The PA process includes systematic identification of current and future safety risks as well as tracking several quantitative and qualitative metrics to ensure the program goals are addressing prominent safety risks accurately and effectively. One of the metrics within the PA process involves using quantitative aviation safety models to gauge the impact of the safety products. This paper demonstrates the role of aviation safety modeling by providing model outputs and evaluating a sample of portfolio elements using the Flightdeck Automation Problems (FLAP) model. The model enables not only ranking of the quantitative relative risk reduction impact of all portfolio elements, but also highlighting the areas with high potential impact via sensitivity and gap analyses in support of the program office. Although the model outputs are preliminary and products are notional, the process shown in this paper is essential to a comprehensive PA of NASA's safety products in the current program and future programs/projects.

Ancel, Ersin; Shih, Ann T.

2014-01-01

89

Numerical modeling of capillary electrophoresis - electrospray mass spectrometry interface design.  

PubMed

Capillary electrophoresis hyphenated with electrospray mass spectrometry (CE-ESI-MS) has emerged in the past decade as one of the most powerful bioanalytical techniques. As the sensitivity and efficiency of new CE-ESI-MS interface designs are continuously improving, numerical modeling can play important role during their development. In this review, different aspects of computer modeling and simulation of CE-ESI-MS interfaces are comprehensively discussed. Relevant essentials of hydrodynamics as well as state-of-the-art modeling techniques are critically evaluated. Sheath liquid-, sheathless-, and liquid-junction interfaces are reviewed from the viewpoint of multidisciplinary numerical modeling along with details of single and multiphase models together with electric field mediated flows, electrohydrodynamics, and free fluid-surface methods. Practical examples are given to help non-specialists to understand the basic principles and applications. Finally, alternative approaches like air amplifiers are also included. © 2014 Wiley Periodicals, Inc. Mass Spec Rev. PMID:24676884

Jarvas, Gabor; Guttman, Andras; Foret, Frantisek

2014-03-26

90

Diffuse interface model of diffusion-limited crystal growth  

Microsoft Academic Search

A general approach to diffusion-limited crystal growth is proposed. It consists of a modified (nonequilibrium) Cahn-Hilliard representation of the interface coupled to a diffusion equation. Arguments are given as to its superiority over previous models. These are illlustrated in a one-dimensional solution which shows how the system selects a unique interface velocity. The selection can be interpreted as the requirement

Joseph B. Collins; Herbert Levine

1985-01-01

91

Device model for electronic processes at organic/organic interfaces  

NASA Astrophysics Data System (ADS)

Interfaces between different organic materials can play a key role in determining organic semiconductor device characteristics. Here, we present a physics-based one-dimensional model with the goal of exploring critical processes at organic/organic interfaces. Specifically, we envision a simple bilayer structure consisting of an electron transport layer (ETL), a hole transport layer (HTL), and the interface between them. The model calculations focus on the following aspects: (1) the microscopic physical processes at the interface, such as exciton formation/dissociation, exciplex formation/dissociation, and geminate/nongeminate recombination; (2) the treatment of the interface parameters and the discretization method; and (3) the application of this model to different devices, such as organic light emitting diodes and photovoltaic cells. At the interface, an electron on an ETL molecule can interact with a hole on an adjacent HTL molecule and form an intermolecular excited state (exciplex). If either the electron or the hole transfers across the interface, an exciton can be formed. The exciton may subsequently diffuse into the relevant layer and relax to the ground state. A strong effective electric field at the interface can cause excitons or exciplexes to dissociate into electrons in the ETL and holes in the HTL. Geminate recombination may occur when the Coulomb interaction between the electron and the hole generated at the interface by exciton dissociation causes the formation of a correlated state that then relaxes to the ground state. The relative impacts of the different processes on measurable macroscopic device characteristics are explored in our calculations by varying the corresponding kinetic coefficients. As it is the aim of this work to investigate effects associated with the organic/organic interface, its treatment in the numerical calculations is of critical importance. We model the interface as a continuous but rather sharp transition from the ETL to the HTL. The model is applied to different devices where different microscopic processes dominate. We discuss the results for an organic light emitting device with exciton or exciplex emission and for a photovoltaic device with or without geminate recombination. In the examples, C60 and tetracene parameters are used for the ETL and HTL materials, respectively.

Liu, Feilong; Paul Ruden, P.; Campbell, Ian. H.; Smith, Darryl L.

2012-05-01

92

AUTOMATED GEOSPATIAL WATERSHED ASSESSMENT (AGWA): A GIS-BASED HYDROLOGIC MODELING TOOL FOR WATERSHED ASSESSMENT AND ANALYSIS  

EPA Science Inventory

The Automated Geospatial Watershed Assessment tool (AGWA) is a GIS interface jointly developed by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the University of Wyoming to automate the parameterization and execu...

93

AUTOMATED GEOSPATICAL WATERSHED ASSESSMENT (AGWA): A GIS-BASED HYDROLOICAL MODELING TOOL FOR WATERSHED ASSESSMENT AND ANALYSIS  

EPA Science Inventory

The Automated Geospatial Watershed Assessment tool (AGWA) is a GIS interface jointly developed by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the University of Wyoming to automate the parameterization and execut...

94

A new dynamic modeling method to fixed machined joint interface  

NASA Astrophysics Data System (ADS)

The concept of virtual material was developed for the first time when the flexible joint interface may be considered as a virtual material with the same cross area. The virtual material is rigidly connected with two components situated in both sides of flexible joint interface. By adding an element, a complex assembled part including a joint interface could be equaled as a simple component without any joint interface in order to simplify the complicated problem about flexible joint interface. The interaction between normal and tangential characteristics of fixed interface taken into account, a series of exact analytical solutions of elastic modulus, shear modulus, Poisson ratio and density were deduced from virtual material through Hertz contact theory and fractal theory. By using experimental results about a series of test specimens, the exact analytic expressions for virtual material's parameters were verified in terms of qualitative comparison principle of resembling vibration shapes and quantitative comparison principle of the natural frequencies. The virtual material model vibration shapes are in excellent agreement with the experimental results. The relative errors between the virtual material model natural frequencies and the experimental ones are between -3% and 10%.

Tian, Hongliang; Li, Bin; Mao, Kuanmin; Gu, Peihua

2013-07-01

95

Aviation Safety: Modeling and Analyzing Complex Interactions between Humans and Automated Systems  

NASA Technical Reports Server (NTRS)

The on-going transformation from the current US Air Traffic System (ATS) to the Next Generation Air Traffic System (NextGen) will force the introduction of new automated systems and most likely will cause automation to migrate from ground to air. This will yield new function allocations between humans and automation and therefore change the roles and responsibilities in the ATS. Yet, safety in NextGen is required to be at least as good as in the current system. We therefore need techniques to evaluate the safety of the interactions between humans and automation. We think that current human factor studies and simulation-based techniques will fall short in front of the ATS complexity, and that we need to add more automated techniques to simulations, such as model checking, which offers exhaustive coverage of the non-deterministic behaviors in nominal and off-nominal scenarios. In this work, we present a verification approach based both on simulations and on model checking for evaluating the roles and responsibilities of humans and automation. Models are created using Brahms (a multi-agent framework) and we show that the traditional Brahms simulations can be integrated with automated exploration techniques based on model checking, thus offering a complete exploration of the behavioral space of the scenario. Our formal analysis supports the notion of beliefs and probabilities to reason about human behavior. We demonstrate the technique with the Ueberligen accident since it exemplifies authority problems when receiving conflicting advices from human and automated systems.

Rungta, Neha; Brat, Guillaume; Clancey, William J.; Linde, Charlotte; Raimondi, Franco; Seah, Chin; Shafto, Michael

2013-01-01

96

ROBUST FINITE DIFFERENCE TIME DOMAIN MODELING INTERFACE  

Microsoft Academic Search

Three dimensional finite difference time domain modeling (FDTD) has been used for many years in engineering and Earth science applications. The earlier versions were fraught with problems and limitations, including an inability to be used for modeling a broad range of frequencies, difficulty modeling large physical property contrasts between grid cells, and no ability to vary the grid size within

Jeffrey J. Daniels; Robert Lee; YuChan Yi; Rubin Ortega; Kyle Shalek

97

Radiation budget measurement/model interface research  

NASA Technical Reports Server (NTRS)

The NIMBUS 6 data were analyzed to form an up to date climatology of the Earth radiation budget as a basis for numerical model definition studies. Global maps depicting infrared emitted flux, net flux and albedo from processed NIMBUS 6 data for July, 1977, are presented. Zonal averages of net radiation flux for April, May, and June and zonal mean emitted flux and net flux for the December to January period are also presented. The development of two models is reported. The first is a statistical dynamical model with vertical and horizontal resolution. The second model is a two level global linear balance model. The results of time integration of the model up to 120 days, to simulate the January circulation, are discussed. Average zonal wind, meridonal wind component, vertical velocity, and moisture budget are among the parameters addressed.

Vonderhaar, T. H.

1981-01-01

98

Improved Sharp Interface Models in Coastal Aquifers of Finite Dimensions  

NASA Astrophysics Data System (ADS)

Coastal aquifer management often involves aquifers of finite dimensions where optimal pumping rates must be calculated through a combined simulation-optimization procedure. Variable-density numerical models are considered more exact than sharp interface models as they better describe the governing flow and transport equations. However, such models are not always preferable in pumping optimization studies, due to their complexity and computational burden. On the other hand, sharp interface models are approximate and can lead to large errors if they are not applied properly, particularly when model boundaries are not treated correctly. The present paper proposes improved sharp interface models considering aquifer boundaries in a proper way. Two sharp interface models are investigated based on the single potential formulation and the Ghyben-Herzberg relation. The first model (Strack, 1976) is based on the assumption of a semi-infinite aquifer with a sea-boundary only. The second model (Mantoglou, 2003) is based on an analytical solution developed for coastal aquifers of finite size and accounts for inland and lateral aquifer boundaries. Next, both models are modified using an empirical correction factor (similar to Pool and Carrera, 2011) which accounts for mixing. A simple pumping optimization problem with a single well in a confined coastal aquifer of finite size with four boundaries (sea, inland and lateral impervious boundaries) is employed. The constraint prevents the toe of the interface to reach the well and the optimal pumping rates are calculated for different locations of the pumping well and different combinations of aquifer parameters. Then the results of the sharp interface models are compared to the 'true' results of the corresponding variable-density numerical model in order to evaluate the performance of the sharp interface models. The results indicate that when the location of the well is close to the sea-boundary, the semi-infinite and the finite sized models produce similar, underestimated optimal solutions. However, when the well is placed inland, or near the lateral boundaries, the semi-infinite model yields much higher pumping rates than the finite sized model which are not always realistic and sustainable. This unrealistic performance is further exacerbated when the correction factor is applied to this model. Furthermore, it is observed that the correction factor is sensitive to different combinations of aquifer parameters in the case of the semi-infinite model. On the other hand, the finite sized sharp interface model of Mantoglou (2003), improved using the correction factor, yields increased and sustainable pumping rates regardless of the well location. This is because this model considers inland and lateral boundaries and is better suited for finite sized aquifers whereas the unrealistic behavior of the semi-infinite model is expected since it neglects those boundaries. We conclude that the finite sized sharp interface model, improved with an appropriate correction factor is a better alternative when applied to aquifers of finite dimensions.

Christelis, Vasileios; Mantoglou, Aristotelis

2013-04-01

99

Interfaces in the XY Model and Conformal Invariance  

NASA Astrophysics Data System (ADS)

The one-dimensional XY model with n arbitrarily placed interfaces is investigated. The energy spectrum is shown to have a tower structure only for a commensurate configuration of the critical parameters. The interfacial critical exponents in such cases are determined from conformal invariance theory. The underlying algebra generating the conformal spectrum is the shifted SO(4c) Kac-Moody algebra, the central charge is 2c, which is exactly two times of that in the Ising model with the same structure of interfaces.

Zhang, De-gang; Chen, Zhong-jun; Li, Bo-zang

1999-01-01

100

Critical interfaces and duality in the Ashkin-Teller model  

SciTech Connect

We report on the numerical measures on different spin interfaces and Fortuin-Kasteleyn (FK) cluster boundaries in the Askhin-Teller (AT) model. For a general point on the AT critical line, we find that the fractal dimension of a generic spin cluster interface can take one of four different possible values. In particular we found spin interfaces whose fractal dimension is d{sub f}=3/2 all along the critical line. Furthermore, the fractal dimension of the boundaries of FK clusters was found to satisfy all along the AT critical line a duality relation with the fractal dimension of their outer boundaries. This result provides clear numerical evidence that such duality, which is well known in the case of the O(n) model, exists in an extended conformal field theory.

Picco, Marco [Laboratoire de Physique Theorique et Hautes Energies, CNRS, Universite Pierre et Marie Curie, UMR 7589, 4 Place Jussieu, F-75252 Paris Cedex 05 (France); Santachiara, Raoul [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS, Batiment 100, Universite Paris-Sud, UMR 8626, F-91405 Orsay (France)

2011-06-15

101

Automated model selection in covariance estimation and spatial whitening of MEG and EEG signals.  

PubMed

Magnetoencephalography and electroencephalography (M/EEG) measure non-invasively the weak electromagnetic fields induced by post-synaptic neural currents. The estimation of the spatial covariance of the signals recorded on M/EEG sensors is a building block of modern data analysis pipelines. Such covariance estimates are used in brain-computer interfaces (BCI) systems, in nearly all source localization methods for spatial whitening as well as for data covariance estimation in beamformers. The rationale for such models is that the signals can be modeled by a zero mean Gaussian distribution. While maximizing the Gaussian likelihood seems natural, it leads to a covariance estimate known as empirical covariance (EC). It turns out that the EC is a poor estimate of the true covariance when the number of samples is small. To address this issue the estimation needs to be regularized. The most common approach downweights off-diagonal coefficients, while more advanced regularization methods are based on shrinkage techniques or generative models with low rank assumptions: probabilistic PCA (PPCA) and factor analysis (FA). Using cross-validation all of these models can be tuned and compared based on Gaussian likelihood computed on unseen data. We investigated these models on simulations, one electroencephalography (EEG) dataset as well as magnetoencephalography (MEG) datasets from the most common MEG systems. First, our results demonstrate that different models can be the best, depending on the number of samples, heterogeneity of sensor types and noise properties. Second, we show that the models tuned by cross-validation are superior to models with hand-selected regularization. Hence, we propose an automated solution to the often overlooked problem of covariance estimation of M/EEG signals. The relevance of the procedure is demonstrated here for spatial whitening and source localization of MEG signals. PMID:25541187

Engemann, Denis A; Gramfort, Alexandre

2015-03-01

102

Industrial Automation Mechanic Model Curriculum Project. Final Report.  

ERIC Educational Resources Information Center

This document describes a demonstration program that developed secondary level competency-based instructional materials for industrial automation mechanics. Program activities included task list compilation, instructional materials research, learning activity packet (LAP) development, construction of lab elements, system implementation,…

Toledo Public Schools, OH.

103

Designers' models of the human-computer interface  

NASA Technical Reports Server (NTRS)

Understanding design models of the human-computer interface (HCI) may produce two types of benefits. First, interface development often requires input from two different types of experts: human factors specialists and software developers. Given the differences in their backgrounds and roles, human factors specialists and software developers may have different cognitive models of the HCI. Yet, they have to communicate about the interface as part of the design process. If they have different models, their interactions are likely to involve a certain amount of miscommunication. Second, the design process in general is likely to be guided by designers' cognitive models of the HCI, as well as by their knowledge of the user, tasks, and system. Designers do not start with a blank slate; rather they begin with a general model of the object they are designing. The author's approach to a design model of the HCI was to have three groups make judgments of categorical similarity about the components of an interface: human factors specialists with HCI design experience, software developers with HCI design experience, and a baseline group of computer users with no experience in HCI design. The components of the user interface included both display components such as windows, text, and graphics, and user interaction concepts, such as command language, editing, and help. The judgments of the three groups were analyzed using hierarchical cluster analysis and Pathfinder. These methods indicated, respectively, how the groups categorized the concepts, and network representations of the concepts for each group. The Pathfinder analysis provides greater information about local, pairwise relations among concepts, whereas the cluster analysis shows global, categorical relations to a greater extent.

Gillan, Douglas J.; Breedin, Sarah D.

1993-01-01

104

Monte Carlo Modeling of Phonons at Crystal Interfaces  

NASA Astrophysics Data System (ADS)

One of the strategies in the effort to directly detect dark matter particles is to measure the phonon and charge signals produced in an incidental collision of a weakly interacting massive particle with a nucleon in a crystalline detector. Proper calibration of the detected phonon energy relies on detailed models of phonon propagation through the crystal to the instrumented surface. Previous Detector Monte Carlo incorporate probabalistic anharmonic decay and mass defect scattering but neglect the mode dependent scattering at crystal boundaries. We calculate mode specific reflection and transmission at detector interfaces with a simple acoustic mismatch model. We find that mode preserving transmission is the most probable outcome at germanium-aluminum detector interfaces, but the probability of reflection is not negligible. The average phonon reflection probability at near normal angles of incidence at a Ge/Al interface is near 20 %, but grows dramatically for oblique incidence. We develop a code using Geant4, which should allow modeling extensions to all phonon mediated dark matter detection schemes. Our models are adaptable to other crystal materials and are generally useful in any phonon interface problem.

Page, W. A.; Brandt, D.; Msall, M. E.

2014-08-01

105

Modeling Software Applications and User Interfaces Using Metaphorical Entities  

Microsoft Academic Search

The power of metaphor has long been recognized in user interface design and more broadly in human interaction circles. More recently metaphor also found its way into the software development process. This paper aims to combine occurrences of metaphor in the two fields with ideas from the field of model driven architecture. We suggest that it is possible to create

Christian Nill; Vishal Sikka

106

Homogenization methods for interface modeling in damaged masonry  

E-print Network

Homogenization methods for interface modeling in damaged masonry A. Rekik1 , F. Lebon2 1 Institut study was to predict damage to masonry by com- bining structural analysis and homogenization methods. In the case of a masonry structure composed of bricks and mortar, a third material is as- sumed to exist

Paris-Sud XI, Université de

107

A Semantic Model for Graphical User Interfaces Neelakantan R. Krishnaswami  

E-print Network

A Semantic Model for Graphical User Interfaces Neelakantan R. Krishnaswami Microsoft Research microsoft.com> Nick Benton Microsoft Research microsoft.com> Abstract We give a denotational and readable. Categories and Subject Descriptors D.3.3 [Programming Lan- guages]: Language Constructs

Benton, Nick

108

User Interface Plasticity: Model Driven Engineering to the Limit!  

E-print Network

service composition, does not cover any of the HCI-centered concerns. Research in autonomic systems, user interface composition, dynamic service composition, model driven engineering (MDE), service-oriented architecture (SOA). ACM Classification Keywords D.2.2 [Software Engineering]: Design Tools and Techniques

109

Model-Based Control for Postal Automation and Baggage Handling  

Microsoft Academic Search

In this thesis we focus on two specific transportation systems, namely postal automation and baggage handling.\\u000a\\u000aPostal automation:\\u000aDuring the last decades the volume of magazines, catalogs, and other plastic wrapped mail items that have to be processed by post sorting centers has increased considerably. In order to be able to handle the large volumes of mail, state-of-the-art post sorting

A. N. Tarau

2010-01-01

110

NASA: Model development for human factors interfacing  

NASA Technical Reports Server (NTRS)

The results of an intensive literature review in the general topics of human error analysis, stress and job performance, and accident and safety analysis revealed no usable techniques or approaches for analyzing human error in ground or space operations tasks. A task review model is described and proposed to be developed in order to reduce the degree of labor intensiveness in ground and space operations tasks. An extensive number of annotated references are provided.

Smith, L. L.

1984-01-01

111

Automated Information Extraction to Support Biomedical Decision Model Construction: A Preliminary Design  

E-print Network

We propose an information extraction framework to support automated construction of decision models in biomedicine. Our proposed technique classifies text-based documents from a large biomedical literature repository, e.g., ...

Li, Xiaoli

112

Atomic Models of Strong Solids Interfaces Viewed as Composite Structures  

NASA Astrophysics Data System (ADS)

This paper looks back through the 1960s to the invention of carbon fibres and the theories of Strong Solids. In particular it focuses on the fracture mechanics paradox of strong composites containing weak interfaces. From Griffith theory, it is clear that three parameters must be considered in producing a high strength composite:- minimising defects; maximising the elastic modulus; and raising the fracture energy along the crack path. The interface then introduces two further factors:- elastic modulus mismatch causing crack stopping; and debonding along a brittle interface due to low interface fracture energy. Consequently, an understanding of the fracture energy of a composite interface is needed. Using an interface model based on atomic interaction forces, it is shown that a single layer of contaminant atoms between the matrix and the reinforcement can reduce the interface fracture energy by an order of magnitude, giving a large delamination effect. The paper also looks to a future in which cars will be made largely from composite materials. Radical improvements in automobile design are necessary because the number of cars worldwide is predicted to double. This paper predicts gains in fuel economy by suggesting a new theory of automobile fuel consumption using an adaptation of Coulomb's friction law. It is demonstrated both by experiment and by theoretical argument that the energy dissipated in standard vehicle tests depends only on weight. Consequently, moving from metal to fibre construction can give a factor 2 improved fuel economy performance, roughly the same as moving from a petrol combustion drive to hydrogen fuel cell propulsion. Using both options together can give a factor 4 improvement, as demonstrated by testing a composite car using the ECE15 protocol.

Staffell, I.; Shang, J. L.; Kendall, K.

2014-02-01

113

A general graphical user interface for automatic reliability modeling  

NASA Technical Reports Server (NTRS)

Reported here is a general Graphical User Interface (GUI) for automatic reliability modeling of Processor Memory Switch (PMS) structures using a Markov model. This GUI is based on a hierarchy of windows. One window has graphical editing capabilities for specifying the system's communication structure, hierarchy, reconfiguration capabilities, and requirements. Other windows have field texts, popup menus, and buttons for specifying parameters and selecting actions. An example application of the GUI is given.

Liceaga, Carlos A.; Siewiorek, Daniel P.

1991-01-01

114

EDITORIAL: Focus section on interface modelling Focus section on interface modelling  

NASA Astrophysics Data System (ADS)

Interfaces continue to provide an endless source of stimulating problems. With support from the DOE/BES supported Computational Materials Science Network (CMSN, www.phys.washington.edu/users/cmsn), a group of us studied various aspects of both solid-liquid and solid-solid interfaces. The papers in this focus section represent a variety of approaches and scales. Since understanding the sensitivity of properties to the choice of interatomic potential is an essential precursor to obtaining useful results with atomistic simulations, Becker and Kramer compared the properties of liquid aluminum predicted by molecular dynamics simulations with experimental measurements (including x-ray diffraction), demonstrating significant differences based only on the choice of interatomic potential. Mendelev et al studied the mobility of the solid-liquid interface, finding that this property correlates well with the diffusion coefficient when close to the melting point. Frolov and Mishin examined stresses in the solid close to the liquid-solid interface in copper and found that the stress is anisotropic. A more subtle behavior is pre-wetting, which Becker and Mishin studied in the intermetallic Ni3Al, again using Monte Carlo simulations; they find that the anti-phase boundary becomes a disordered gamma phase layer under certain conditions. Finally, turning to the mesoscopic scale and grain boundaries, as opposed to the liquid-solid interface, Rollett et al showed that hot spots in stress during plastic deformation are strongly associated with grain boundaries and particular orientations. This set of papers provides some sense of the wide range of problems and therefore time/length scales that must be considered in materials science in order to make progress. Finally, the Editor would like to acknowledge the many fruitful discussions and interactions with colleagues in the CMSN over the years. A D Rollett Guest Editor

2010-10-01

115

Automated MRI Segmentation for Individualized Modeling of Current Flow in the Human Head  

PubMed Central

Objective High-definition transcranial direct current stimulation (HD-tDCS) and high-density electroencephalography (HD-EEG) require accurate models of current flow for precise targeting and current source reconstruction. At a minimum, such modeling must capture the idiosyncratic anatomy of brain, cerebrospinal fluid (CSF) and skull for each individual subject. Currently, the process to build such high-resolution individualized models from structural magnetic resonance images (MRI) requires labor-intensive manual segmentation, even when leveraging available automated segmentation tools. Also, accurate placement of many high-density electrodes on individual scalp is a tedious procedure. The goal was to develop fully automated techniques to reduce the manual effort in such a modeling process. Approach A fully automated segmentation technique based on Statical Parametric Mapping 8 (SPM8), including an improved tissue probability map (TPM) and an automated correction routine for segmentation errors, was developed, along with an automated electrode placement tool for high-density arrays. The performance of these automated routines was evaluated against results from manual segmentation on 4 healthy subjects and 7 stroke patients. The criteria include segmentation accuracy, the difference of current flow distributions in resulting HD-tDCS models and the optimized current flow intensities on cortical targets. Main results The segmentation tool can segment out not just the brain but also provide accurate results for CSF, skull and other soft tissues with a field of view (FOV) extending to the neck. Compared to manual results, automated segmentation deviates by only 7% and 18% for normal and stroke subjects, respectively. The predicted electric fields in the brain deviate by 12% and 29% respectively, which is well within the variability observed for various modeling choices. Finally, optimized current flow intensities on cortical targets do not differ significantly. Significance Fully automated individualized modeling may now be feasible for large-sample EEG research studies and tDCS clinical trials. PMID:24099977

Huang, Yu; Dmochowski, Jacek P.; Su, Yuzhuo; Datta, Abhishek; Rorden, Christopher; Parra, Lucas C.

2013-01-01

116

Automated MRI segmentation for individualized modeling of current flow in the human head  

NASA Astrophysics Data System (ADS)

Objective. High-definition transcranial direct current stimulation (HD-tDCS) and high-density electroencephalography require accurate models of current flow for precise targeting and current source reconstruction. At a minimum, such modeling must capture the idiosyncratic anatomy of the brain, cerebrospinal fluid (CSF) and skull for each individual subject. Currently, the process to build such high-resolution individualized models from structural magnetic resonance images requires labor-intensive manual segmentation, even when utilizing available automated segmentation tools. Also, accurate placement of many high-density electrodes on an individual scalp is a tedious procedure. The goal was to develop fully automated techniques to reduce the manual effort in such a modeling process. Approach. A fully automated segmentation technique based on Statical Parametric Mapping 8, including an improved tissue probability map and an automated correction routine for segmentation errors, was developed, along with an automated electrode placement tool for high-density arrays. The performance of these automated routines was evaluated against results from manual segmentation on four healthy subjects and seven stroke patients. The criteria include segmentation accuracy, the difference of current flow distributions in resulting HD-tDCS models and the optimized current flow intensities on cortical targets.Main results. The segmentation tool can segment out not just the brain but also provide accurate results for CSF, skull and other soft tissues with a field of view extending to the neck. Compared to manual results, automated segmentation deviates by only 7% and 18% for normal and stroke subjects, respectively. The predicted electric fields in the brain deviate by 12% and 29% respectively, which is well within the variability observed for various modeling choices. Finally, optimized current flow intensities on cortical targets do not differ significantly.Significance. Fully automated individualized modeling may now be feasible for large-sample EEG research studies and tDCS clinical trials.

Huang, Yu; Dmochowski, Jacek P.; Su, Yuzhuo; Datta, Abhishek; Rorden, Christopher; Parra, Lucas C.

2013-12-01

117

Proceedings of the IEEE International Conference on Robotics and Automation, Nagoya, Japan, May 1995 System Design and Interfaces for  

E-print Network

- tor. The system is capable of performing object acqui- sition from a moving conveyor belt and carrying predictable, repeatable behavior of the workcell: feeders, xtures, specialized tooling and xed automation

118

A Multiple Agent Model of Human Performance in Automated Air Traffic Control and Flight Management Operations  

NASA Technical Reports Server (NTRS)

A predictive model of human operator performance (flight crew and air traffic control (ATC)) has been developed and applied in order to evaluate the impact of automation developments in flight management and air traffic control. The model is used to predict the performance of a two person flight crew and the ATC operators generating and responding to clearances aided by the Center TRACON Automation System (CTAS). The purpose of the modeling is to support evaluation and design of automated aids for flight management and airspace management and to predict required changes in procedure both air and ground in response to advancing automation in both domains. Additional information is contained in the original extended abstract.

Corker, Kevin; Pisanich, Gregory; Condon, Gregory W. (Technical Monitor)

1995-01-01

119

A DIS interface for the Joint Conflict Model simulation  

SciTech Connect

A Distributed Interactive Simulation (DIS) 2.0.3 compatible interface has been added to the Joint Conflict Model (JCM) simulation. JCM is a multi-player, multi-sided, joint, entity-based, stochastic, constructive simulation. A DIS interface allows JCM to engage itself, other constructive simulations, virtual simulators and/or real players in real-time training exercises. A real-time demonstration between multiple JCM simulations and Special Operations Forces Network (SOFNET) helicopter trainers was demonstrated 8 June 1994 at the 58th Special Operations Wing (SOW) at Kirtland AFB. This paper will examine issues of interest that were raised as a result of the JCM/SOFNET demonstration: munition modeling, terrain correlation, terrain clamping, coordinate conversion, transfer of entity modeling control, and mounting and dismounting entities.

Matone, J.; Pimper, J.; Uzelac, M.

1994-08-01

120

Developing A Laser Shockwave Model For Characterizing Diffusion Bonded Interfaces  

SciTech Connect

12. Other advances in QNDE and related topics: Preferred Session Laser-ultrasonics Developing A Laser Shockwave Model For Characterizing Diffusion Bonded Interfaces 41st Annual Review of Progress in Quantitative Nondestructive Evaluation Conference QNDE Conference July 20-25, 2014 Boise Centre 850 West Front Street Boise, Idaho 83702 James A. Smith, Jeffrey M. Lacy, Barry H. Rabin, Idaho National Laboratory, Idaho Falls, ID ABSTRACT: The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) which is assigned with reducing the worldwide use of high-enriched uranium (HEU). A salient component of that initiative is the conversion of research reactors from HEU to low enriched uranium (LEU) fuels. An innovative fuel is being developed to replace HEU. The new LEU fuel is based on a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to complete the fuel qualification process, the laser shock technique is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated fuel plates. The Laser Shockwave Technique (LST) is being investigated to characterize interface strength in fuel plates. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves to characterize interfaces in nuclear fuel plates. However the deposition of laser energy into the containment layer on specimen’s surface is intractably complex. The shock wave energy is inferred from the velocity on the backside and the depth of the impression left on the surface from the high pressure plasma pulse created by the shock laser. To help quantify the stresses and strengths at the interface, a finite element model is being developed and validated by comparing numerical and experimental results for back face velocities and front face depressions with experimental results. This paper will report on initial efforts to develop a finite element model for laser shock.

James A. Smith; Jeffrey M. Lacy; Barry H. Rabin

2014-07-01

121

Symmetric model of compressible granular mixtures with permeable interfaces  

NASA Astrophysics Data System (ADS)

Compressible granular materials are involved in many applications, some of them being related to energetic porous media. Gas permeation effects are important during their compaction stage, as well as their eventual chemical decomposition. Also, many situations involve porous media separated from pure fluids through two-phase interfaces. It is thus important to develop theoretical and numerical formulations to deal with granular materials in the presence of both two-phase interfaces and gas permeation effects. Similar topic was addressed for fluid mixtures and interfaces with the Discrete Equations Method (DEM) [R. Abgrall and R. Saurel, "Discrete equations for physical and numerical compressible multiphase mixtures," J. Comput. Phys. 186(2), 361-396 (2003)] but it seemed impossible to extend this approach to granular media as intergranular stress [K. K. Kuo, V. Yang, and B. B. Moore, "Intragranular stress, particle-wall friction and speed of sound in granular propellant beds," J. Ballist. 4(1), 697-730 (1980)] and associated configuration energy [J. B. Bdzil, R. Menikoff, S. F. Son, A. K. Kapila, and D. S. Stewart, "Two-phase modeling of deflagration-to-detonation transition in granular materials: A critical examination of modeling issues," Phys. Fluids 11, 378 (1999)] were present with significant effects. An approach to deal with fluid-porous media interfaces was derived in Saurel et al. ["Modelling dynamic and irreversible powder compaction," J. Fluid Mech. 664, 348-396 (2010)] but its validity was restricted to weak velocity disequilibrium only. Thanks to a deeper analysis, the DEM is successfully extended to granular media modelling in the present paper. It results in an enhanced version of the Baer and Nunziato ["A two-phase mixture theory for the deflagration-to-detonation transition (DDT) in reactive granular materials," Int. J. Multiphase Flow 12(6), 861-889 (1986)] model as symmetry of the formulation is now preserved. Several computational examples are shown to validate and illustrate method's capabilities.

Saurel, Richard; Le Martelot, Sébastien; Tosello, Robert; Lapébie, Emmanuel

2014-12-01

122

Modelling surface rheology of complex interfaces with extended irreversible thermodynamics  

NASA Astrophysics Data System (ADS)

The rheological properties of the interfaces in complex multiphase systems often play a crucial role in the dynamic behavior of these systems. For example, these properties affect the dynamics of emulsions, of dispersions of vesicles, of biological fluids, or of free surface flows. In the past three to four decades a vast amount of literature has been produced dealing with the rheological properties of interfaces stabilized by low molecular weight surfactants, proteins, (bio)polymers, lipids, colloidal particles, and various mixtures of these surface active components. The data of these surface rheological experiments are often analyzed with ad hoc generalizations of rheological models used for the analysis of rheological properties of bulk phases. The validity of these generalizations is in general not discussed. Here we show how the extended irreversible thermodynamics (EIT) formalism can be used to generate a wide range of thermodynamically admissible constitutive models for the surface stress tensor, which not only encompass currently used constitutive models, but also suggest several new ones, particularly useful for modelling the nonlinear response of interfaces.

Sagis, Leonard M. C.

2010-02-01

123

Analysis of polychlorinated biphenyls in transformer oils by automated on-line coupling reversed phase liquid chromatography-gas chromatography using the through oven transfer adsorption desorption (TOTAD) Interface  

Microsoft Academic Search

An automated method for the direct analysis of polychlorinated biphenyls (PCBs) in transformer oil is presented. The proposed method uses the TOTAD (through oven transfer adsorption desorption) interface for the on-line coupling of reversed phase liquid chromatography and gas chromatography (RPLC-GC). In this fully automated system, the oil is injected directly with no sample pre-treatment step other than dilution with

José Manuel Cortés; Juan C. Andini; Rosa M. Toledano; Carlos Quintero; Jesús Villén; Ana Vázquez

2012-01-01

124

a Deformable Template Model with Feature Tracking for Automated Ivus Segmentation  

NASA Astrophysics Data System (ADS)

Intravascular Ultrasound (IVUS) can be used to create a 3D vascular profile of arteries for preventative prediction of Coronary Heart Disease (CHD). Segmentation of individual B-scan frames is a crucial step for creating profiles. Manual segmentation is too labor intensive to be of routine use. Automated segmentation algorithms are not yet accurate enough. We present a method of tracking features across frames of ultrasound data to increase automated segmentation accuracy using a deformable template model.

Manandhar, Prakash; Hau Chen, Chi

2010-02-01

125

Automated Eukaryotic Gene Structure Annotation Using EVidenceModeler and the Program to Assemble Spliced Alignments  

SciTech Connect

EVidenceModeler (EVM) is presented as an automated eukaryotic gene structure annotation tool that reports eukaryotic gene structures as a weighted consensus of all available evidence. EVM, when combined with the Program to Assemble Spliced Alignments (PASA), yields a comprehensive, configurable annotation system that predicts protein-coding genes and alternatively spliced isoforms. Our experiments on both rice and human genome sequences demonstrate that EVM produces automated gene structure annotation approaching the quality of manual curation.

Haas, B J; Salzberg, S L; Zhu, W; Pertea, M; Allen, J E; Orvis, J; White, O; Buell, C R; Wortman, J R

2007-12-10

126

MODELING USER INTERFACES WITH THE XIS UML Carlos Martins  

E-print Network

MODELING USER INTERFACES WITH THE XIS UML PROFILE Carlos Martins Universidade da Madeira, Campus da Penteada, Funchal, Portugal carlos.martins@srs.pt Alberto Rodrigues da Silva INESC-ID & Instituto Superior S U A L B A S I C S I L K D E N I M AUIML X I M L U I M L XFORMS W I S D O M U X U M L i OVID U W E

da Silva, Alberto Rodrigues

127

A Feedback Model for Automated Real Estate Assessment  

Microsoft Academic Search

Pressing changes are needed in the administration of real estate taxation that will not only ensure that all properties be assessed accurately and equitably, but will enable taxpayers to perceive that they are being treated fairly. In this paper, we examine what properties an automated mass appraisal system should exhibit so as to meet efficacy, equity and public acceptability criteria.

Robert Carbone; Richard L. Longini

1977-01-01

128

Physical Parameters of Substorms from Automated Forward Modeling (AFM)  

NASA Astrophysics Data System (ADS)

Automated Forward Modeling (AFM) inverts magnetic data to give physical parameters for electric current flow in near-Earth space. On a meridian, it gives the total electric current crossing it, and latitudinal boundaries. AFM uses nonlinear optimization of parameters of a forward model. Characteristic behaviors of substorms are seen: the current strengthens rapidly at an onset, with electrojet boundary motion. The current rises for approximately 30 minutes, but poleward border expansion progresses slightly faster. Recovery is accompanied by a current decrease, but not poleward retreat of the auroral oval on up to a two- hour timescale. Average characteristics of the current closely follow those of the AL index, with large variation in individual events. Boundary motion is similar to that deduced for the electron aurora from satellite studies. AFM allows both the current strength and the borders to be determined from ground magnetic data alone, generally available on a continuous basis. In this study, 63 separate onsets in 1997 were characterized using AFM on the CANOPUS Churchill meridian. The provisional AL index was also obtained for the same events. The parametrization of Weimer (1993), JGR 99, 11005 was found to be extremely accurate for both AL and meridian current, which is I(MA) = c0 + c_1 te^{pt}, with c0 0.151 MA, c_1 1.63 MA/h, and p -1.98/h. This permits a current/AL relation of I(MA) = -0.0322 - 0.00165 * AL, where we stress that I and AL are averages. Further, on average the equatorward border of the electrojet does not change much at onset, while the poleward border's latitude in central dipole coordinates is well represented by 67.5+4.21*(1.0-e^{-5.47*t}), with t the postonset time in hours. These results agree very well with those of Frey et al. (2004), JGR 109, doi:10.1029/2004JA010607 for electron auroras observed using Image WIC near the onset meridian. AFM permits quantification of electrojet parameters, facilitating their interpretation and comparison to other quantities measured during substorms.

Connors, M.; McPherron, R. L.; Ponto, J.

2006-12-01

129

Wavelet transforms in a critical interface model for Barkhausen noise.  

PubMed

We discuss the application of wavelet transforms to a critical interface model which is known to provide a good description of Barkhausen noise in soft ferromagnets. The two-dimensional version of the model (one-dimensional interface) is considered, mainly in the adiabatic limit of very slow driving. On length scales shorter than a crossover length (which grows with the strength of the surface tension), the effective interface roughness exponent zeta is approximately 1.20 , close to the expected value for the universality class of the quenched Edwards-Wilkinson model. We find that the waiting times between avalanches are fully uncorrelated, as the wavelet transform of their autocorrelations scales as white noise. Similarly, detrended size-size correlations give a white-noise wavelet transform. Consideration of finite driving rates, still deep within the intermittent regime, shows the wavelet transform of correlations scaling as 1/f(1.5) for intermediate frequencies. This behavior is ascribed to intra-avalanche correlations. PMID:18352011

de Queiroz, S L A

2008-02-01

130

Bacterial Adhesion to Hexadecane (Model NAPL)-Water Interfaces  

NASA Astrophysics Data System (ADS)

The rates of biodegradation of NAPLs have been shown to be influenced by the adhesion of hydrocarbon- degrading microorganisms as well as their proximity to the NAPL-water interface. Several studies provide evidence for bacterial adhesion or biofilm formation at alkane- or crude oil-water interfaces, but there is a significant knowledge gap in our understanding of the processes that influence initial adhesion of bacteria on to NAPL-water interfaces. In this study bacterial adhesion to hexadecane, and a series of NAPLs comprised of hexadecane amended with toluene, and/or with asphaltenes and resins, which are the surface active fractions of crude oils, were examined using a Microbial Adhesion to Hydrocarbons (MATH) assay. The microorganisms employed were Mycobacterium kubicae, Pseudomonas aeruginosa and Pseudomonas putida, which are hydrocarbon degraders or soil microorganisms. MATH assays as well as electrophoretic mobility measurements of the bacterial cells and the NAPL droplet surfaces in aqueous solutions were conducted at three solution pHs (4, 6 and 7). Asphaltenes and resins were shown to generally decrease microbial adhesion. Results of the MATH assay were not in qualitative agreement with theoretical predictions of bacteria- hydrocarbon interactions based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) model of free energy of interaction between the cell and NAPL droplets. In this model the free energy of interaction between two colloidal particles is predicted based on electrical double layer, van der Waals and hydrophobic forces. It is likely that the steric repulsion between bacteria and NAPL surfaces, caused by biopolymers on bacterial surfaces and aphaltenes and resins at the NAPL-water interface contributed to the decreased adhesion compared to that predicted by the XDLVO model.

Ghoshal, S.; Zoueki, C. R.; Tufenkji, N.

2009-05-01

131

The model research of information automation system based on RFID in logistics business enterprise of warehouse  

Microsoft Academic Search

The paper begins with analyzing informationization demand of logistics business enterprise of warehouse, puts forward structure model of the network warehouse information platform which is based on the technology of RFID, and puts forward business process, data process of model application and the solutions of systematic data management. The model offers automation information platform for logistics business enterprise of warehouse

Minai He; Xinjun Wei

2009-01-01

132

A Model of Process-Based Automation: Cost and Quality Implications in the Medication Management Process  

ERIC Educational Resources Information Center

The objective of this research is to understand how a set of systems, as defined by the business process, creates value. The three studies contained in this work develop the model of process-based automation. The model states that complementarities among systems are specified by handoffs in the business process. The model also provides theory to…

Spaulding, Trent Joseph

2011-01-01

133

Language Model Applications to Spelling with Brain-Computer Interfaces  

PubMed Central

Within the Ambient Assisted Living (AAL) community, Brain-Computer Interfaces (BCIs) have raised great hopes as they provide alternative communication means for persons with disabilities bypassing the need for speech and other motor activities. Although significant advancements have been realized in the last decade, applications of language models (e.g., word prediction, completion) have only recently started to appear in BCI systems. The main goal of this article is to review the language model applications that supplement non-invasive BCI-based communication systems by discussing their potential and limitations, and to discern future trends. First, a brief overview of the most prominent BCI spelling systems is given, followed by an in-depth discussion of the language models applied to them. These language models are classified according to their functionality in the context of BCI-based spelling: the static/dynamic nature of the user interface, the use of error correction and predictive spelling, and the potential to improve their classification performance by using language models. To conclude, the review offers an overview of the advantages and challenges when implementing language models in BCI-based communication systems when implemented in conjunction with other AAL technologies. PMID:24675760

Mora-Cortes, Anderson; Manyakov, Nikolay V.; Chumerin, Nikolay; Van Hulle, Marc M.

2014-01-01

134

Modeling the Energy Use of a Connected and Automated Transportation System (Poster)  

SciTech Connect

Early research points to large potential impacts of connected and automated vehicles (CAVs) on transportation energy use - dramatic savings, increased use, or anything in between. Due to a lack of suitable data and integrated modeling tools to explore these complex future systems, analyses to date have relied on simple combinations of isolated effects. This poster proposes a framework for modeling the potential energy implications from increasing penetration of CAV technologies and for assessing technology and policy options to steer them toward favorable energy outcomes. Current CAV modeling challenges include estimating behavior change, understanding potential vehicle-to-vehicle interactions, and assessing traffic flow and vehicle use under different automation scenarios. To bridge these gaps and develop a picture of potential future automated systems, NREL is integrating existing modeling capabilities with additional tools and data inputs to create a more fully integrated CAV assessment toolkit.

Gonder, J.; Brown, A.

2014-07-01

135

TorX: Automated Model-Based Testing  

Microsoft Academic Search

Systematic testing is very important for assessing and improving the quality of software systems. Yet, testing turns out to be expensive, laborious, time-consuming and error-prone. The Dutch research and development project Côte de Resyste worked on methods, techniques and tools for automating specification based testing using formal methods. The main achievement of the project is a test tool, baptized TorX,

Jan Tretmans; Ed Brinksma; A. Hartman; K. Dussa-Ziegler

2003-01-01

136

Automated modeling and analysis of CSMA-type access schemes for building automation networks  

Microsoft Academic Search

During the design of large technical systems, the use of analytic and simulative models to test and dimension the system before implementation is of practical importance for an efficient and reliable design process. However, setting up the necessary models is time-consuming and therefore often too expensive in practice. Usually most information for modeling is already available in the design tool

Joern Ploennigs; Peter Buchholz; Mario Neugebauer; Klaus Kabitzsch

2006-01-01

137

A symbolic/subsymbolic interface protocol for cognitive modeling  

PubMed Central

Researchers studying complex cognition have grown increasingly interested in mapping symbolic cognitive architectures onto subsymbolic brain models. Such a mapping seems essential for understanding cognition under all but the most extreme viewpoints (namely, that cognition consists exclusively of digitally implemented rules; or instead, involves no rules whatsoever). Making this mapping reduces to specifying an interface between symbolic and subsymbolic descriptions of brain activity. To that end, we propose parameterization techniques for building cognitive models as programmable, structured, recurrent neural networks. Feedback strength in these models determines whether their components implement classically subsymbolic neural network functions (e.g., pattern recognition), or instead, logical rules and digital memory. These techniques support the implementation of limited production systems. Though inherently sequential and symbolic, these neural production systems can exploit principles of parallel, analog processing from decision-making models in psychology and neuroscience to explain the effects of brain damage on problem solving behavior. PMID:20711520

Simen, Patrick; Polk, Thad

2009-01-01

138

Towards automated 3D finite element modeling of direct fiber reinforced composite dental bridge  

Microsoft Academic Search

An automated 3D finite element (FE) modeling procedure for direct fiber rein- forced dental bridge is established on the basis of computer tomography (CT) scan data. The model presented herein represents a two-unit anterior cantilever bridge that includes a maxillary right incisor as an abutment and a maxillary left incisor as a cantilever pontic bonded by adhesive and reinforced fibers.

Wei Li; Michael V. Swain; Qing Li; Grant P. Steven

2005-01-01

139

A Binary Programming Approach to Automated Test Assembly for Cognitive Diagnosis Models  

ERIC Educational Resources Information Center

Automated test assembly (ATA) has been an area of prolific psychometric research. Although ATA methodology is well developed for unidimensional models, its application alongside cognitive diagnosis models (CDMs) is a burgeoning topic. Two suggested procedures for combining ATA and CDMs are to maximize the cognitive diagnostic index and to use a…

Finkelman, Matthew D.; Kim, Wonsuk; Roussos, Louis; Verschoor, Angela

2010-01-01

140

Modeling and Automated Containment of Worms Sarah Sellke, Ness B. Shroff, and Saurabh Bagchi  

E-print Network

Modeling and Automated Containment of Worms Sarah Sellke, Ness B. Shroff, and Saurabh Bagchi School Self-propagating codes, called worms, such as Code Red, Nimda, and Slammer, have drawn significant community in modeling the spread of worms and in providing adequate defense mecha- nisms against them

Bagchi, Saurabh

141

Optimisation model and exact algorithm for Autonomous Straddle Carrier Scheduling at automated container terminals  

Microsoft Academic Search

In this paper, an optimisation model based on Pickup and Delivery Problem with Time Windows (PDPTW), and an exact algorithm based on Branch-and-Bound with Column Generation (BBCG), are presented for Autonomous Straddle Carriers Scheduling (ASCS) problem at automated container terminals. The ASCS problem is firstly modeled into a PDPTW, which is formulated as a Binary Integer Programming (BIP) and then

Binghuang Cai; Shoudong Huang; Dikai Liu; Shuai Yuan; Gamini Dissanayake; Haye Lau; Daniel Pagac

2011-01-01

142

Optimisation model and exact algorithm for autonomous straddle carrier scheduling at automated container terminals  

Microsoft Academic Search

In this paper, an optimisation model based on Pickup and Delivery Problem with Time Windows (PDPTW), and an exact algorithm based on Branch-and-Bound with Column Generation (BBCG), are presented for Autonomous Straddle Carriers Scheduling (ASCS) problem at automated container terminals. The ASCS problem is firstly modeled into a PDPTW, which is formulated as a Binary Integer Programming (BIP) and then

Binghuang Cai; Shoudong Huang; Dikai Liu; Shuai Yuan; Gamini Dissanayake; Haye Lau; Daniel Pagac

2011-01-01

143

Towards an Improved Pilot-Vehicle Interface for Highly Automated Aircraft: Evaluation of the Haptic Flight Control System  

NASA Technical Reports Server (NTRS)

The control automation and interaction paradigm (e.g., manual, autopilot, flight management system) used on virtually all large highly automated aircraft has long been an exemplar of breakdowns in human factors and human-centered design. An alternative paradigm is the Haptic Flight Control System (HFCS) that is part of NASA Langley Research Center s Naturalistic Flight Deck Concept. The HFCS uses only stick and throttle for easily and intuitively controlling the actual flight of the aircraft without losing any of the efficiency and operational benefits of the current paradigm. Initial prototypes of the HFCS are being evaluated and this paper describes one such evaluation. In this evaluation we examined claims regarding improved situation awareness, appropriate workload, graceful degradation, and improved pilot acceptance. Twenty-four instrument-rated pilots were instructed to plan and fly four different flights in a fictitious airspace using a moderate fidelity desktop simulation. Three different flight control paradigms were tested: Manual control, Full Automation control, and a simplified version of the HFCS. Dependent variables included both subjective (questionnaire) and objective (SAGAT) measures of situation awareness, workload (NASA-TLX), secondary task performance, time to recognize automation failures, and pilot preference (questionnaire). The results showed a statistically significant advantage for the HFCS in a number of measures. Results that were not statistically significant still favored the HFCS. The results suggest that the HFCS does offer an attractive and viable alternative to the tactical components of today s FMS/autopilot control system. The paper describes further studies that are planned to continue to evaluate the HFCS.

Schutte, Paul; Goodrich, Kenneth; Williams, Ralph

2012-01-01

144

Automated Model Generation from Design Databases at the Example of Building Automation Networks  

Microsoft Academic Search

During the design of large technical systems it can fast re- munerate to use analytic and simulative models to test and dimension the system before implementation. However, setting up such predictive models is time-consuming and nobody intends to repeat work that has already been invested into a design tool used to develop such extensive systems. Therefore many developers are deterred

Joern Ploennigs; Mario Neugebauer; Klaus Kabitzsch

2004-01-01

145

Integrating Automated Range Registration with Multiview Geometry for the Photorealistic Modeling of Large-Scale Scenes  

Microsoft Academic Search

The photorealistic modeling of large-scale scenes, such as urban structures, requires a fusion of range sensing technology\\u000a and traditional digital photography. This paper presents a system that integrates automated 3D-to-3D and 2D-to-3D registration\\u000a techniques, with multiview geometry for the photorealistic modeling of urban scenes. The 3D range scans are registered using\\u000a our automated 3D-to-3D registration method that matches 3D features

Ioannis Stamos; Lingyun Liu; Chao Chen; George Wolberg; Gene Yu; Siavash Zokai

2008-01-01

146

STATECHART MODELING AND WEB-BASED SIMULATION OF HYBRID DYNAMIC SYSTEMS FOR E-AUTOMATION  

Microsoft Academic Search

Web-based simulation of hybrid automation systems as attracted much attention. However, most available modeling approaches usually result in unnatural and complex models as both discrete logic and continuous behavior are involved. Based on the multi-paradigm modeling concept, this paper extends the traditional discrete statechart to model the continuous dynamics in a hierarchical and natural way. Furthermore, a Java-based kernel is

Jin-Shyan Lee; Meng-Chu Zhou; Pau-Lo Hsu

2005-01-01

147

Hybrid Powertrain Optimization for Plug-In Microgrid Power Generation Automated Modeling Laboratory Slide 1 of 28  

E-print Network

Hybrid Powertrain Optimization for Plug-In Microgrid Power Generation Automated Modeling LaboratoryPlug--InIn MicrogridMicrogrid Power GenerationPower Generation Scott J. MouraScott J. Moura DongsukDongsuk KumKum Hosam Powertrain Optimization for Plug-In Microgrid Power Generation Automated Modeling Laboratory Slide 2 of 28

Krstic, Miroslav

148

Automation based on knowledge modeling theory and its applications in engine diagnostic systems using Space Shuttle Main Engine vibrational data  

Microsoft Academic Search

Humans can perform many complicated tasks without explicit rules. This inherent and advantageous capability becomes a hurdle when a task is to be automated. Modern computers and numerical calculations require explicit rules and discrete numerical values. In order to bridge the gap between human knowledge and automating tools, a knowledge model is proposed. Knowledge modeling techniques are discussed and utilized

Jonnathan H. Kim

1995-01-01

149

AUTOMATED GEOSPATIAL WATERSHED ASSESSMENT (AGWA): A GIS-BASED HYDROLOGICAL MODELING TOOL FOR WATERSHED MANAGEMENT AND LANDSCAPE ASSESSMENT  

EPA Science Inventory

The Automated Geospatial Watershed Assessment (http://www.epa.gov/nerlesd1/land-sci/agwa/introduction.htm and www.tucson.ars.ag.gov/agwa) tool is a GIS interface jointly developed by the U.S. Environmental Protection Agency, USDA-Agricultural Research Service, and the University ...

150

Nonlocal Kardar-Parisi-Zhang equation to model interface growth.  

PubMed

The dynamics of the growth of interfaces in the presence of noise and when the normal velocity is constant, in the weakly nonlinear limit, are described by the Kardar-Parisi-Zhang (KPZ) equation. In many applications, however, the growth is controlled by nonlocal transport, which is not contained in the original KPZ equation. For these problems we are proposing an extension of the KPZ model, where the nonlocal contribution is expressed through a Hilbert transform and can act to either stabilize or destabilize the interface. The model is illustrated with a specific example from reactive infiltration. The properties of the solution of the resulting equation are studied in one spatial dimension in the linear and the nonlinear limits, for both stable and unstable growth. We find that the early-time behavior has a power-law scaling similar to that of the KPZ equation. However, in the case of stable growth, the scaling of the saturation width is logarithmic, which differs from the power law in the KPZ equation. This dependence reflects the stabilizing effect of nonlocal transport. In the unstable case, we obtain results similar to those of Olami et al. [Phys. Rev. E 55, 2649 (1997)]. PMID:11461399

Kechagia, P; Yortsos, Y C; Lichtner, P

2001-07-01

151

Electroviscoelasticity of liquid/liquid interfaces: fractional-order model.  

PubMed

A number of theories that describe the behavior of liquid-liquid interfaces have been developed and applied to various dispersed systems, e.g., Stokes, Reiner-Rivelin, Ericksen, Einstein, Smoluchowski, and Kinch. A new theory of electroviscoelasticity describes the behavior of electrified liquid-liquid interfaces in fine dispersed systems and is based on a new constitutive model of liquids. According to this model liquid-liquid droplet or droplet-film structure (collective of particles) is considered as a macroscopic system with internal structure determined by the way the molecules (ions) are tuned (structured) into the primary components of a cluster configuration. How the tuning/structuring occurs depends on the physical fields involved, both potential (elastic forces) and nonpotential (resistance forces). All these microelements of the primary structure can be considered as electromechanical oscillators assembled into groups, so that excitation by an external physical field may cause oscillations at the resonant/characteristic frequency of the system itself (coupling at the characteristic frequency). Up to now, three possible mathematical formalisms have been discussed related to the theory of electroviscoelasticity. The first is the tension tensor model, where the normal and tangential forces are considered, only in mathematical formalism, regardless of their origin (mechanical and/or electrical). The second is the Van der Pol derivative model, presented by linear and nonlinear differential equations. Finally, the third model presents an effort to generalize the previous Van der Pol equation: the ordinary time derivative and integral are now replaced with the corresponding fractional-order time derivative and integral of order p<1. PMID:15576102

Spasic, Aleksandar M; Lazarevic, Mihailo P

2005-02-01

152

ORIGAMI -- The Oak Ridge Geometry Analysis and Modeling Interface  

SciTech Connect

A revised ``ray-tracing`` package which is a superset of the geometry specifications of the radiation transport codes MORSE, MASH (GIFT Versions 4 and 5), HETC, and TORT has been developed by ORNL. Two additional CAD-based formats are also included as part of the superset: the native format of the BRL-CAD system--MGED, and the solid constructive geometry subset of the IGES specification. As part of this upgrade effort, ORNL has designed an Xwindows-based utility (ORIGAMI) to facilitate the construction, manipulation, and display of the geometric models required by the MASH code. Since the primary design criterion for this effort was that the utility ``see`` the geometric model exactly as the radiation transport code does, ORIGAMI is designed to utilize the same ``ray-tracing`` package as the revised version of MASH. ORIGAMI incorporates the functionality of two previously developed graphical utilities, CGVIEW and ORGBUG, into a single consistent interface.

Burns, T.J.

1996-04-01

153

Intelligent User Interfaces for Information Analysis: A Cognitive Model  

SciTech Connect

Intelligent user interfaces (IUIs) for information analysis (IA) need to be designed with an intrinsic understanding of the analytical objectives and the dimensions of the information space. These analytical objectives are oriented around the requirement to provide decision makers with courses of action. Most tools available to support analysis barely skim the surface of the dimensions and categories of information used in analysis, and almost none are designed to address the ultimate requirement of decision support. This paper presents a high-level model of the cognitive framework of information analysts in the context of doing their jobs. It is intended that this model will enable the derivation of design requirements for advanced IUIs for IA.

Schwarting, Irene S.; Nelson, Rob A.; Cowell, Andrew J.

2006-01-29

154

The use of analytical models in human-computer interface design  

NASA Technical Reports Server (NTRS)

Some of the many analytical models in human-computer interface design that are currently being developed are described. The usefulness of analytical models for human-computer interface design is evaluated. Can the use of analytical models be recommended to interface designers? The answer, based on the empirical research summarized here, is: not at this time. There are too many unanswered questions concerning the validity of models and their ability to meet the practical needs of design organizations.

Gugerty, Leo

1991-01-01

155

Time-domain matched interface and boundary (MIB) modeling of Debye dispersive media with curved interfaces  

NASA Astrophysics Data System (ADS)

A new finite-difference time-domain (FDTD) method is introduced for solving transverse magnetic Maxwell's equations in Debye dispersive media with complex interfaces and discontinuous wave solutions. Based on the auxiliary differential equation approach, a hybrid Maxwell-Debye system is constructed, which couples the wave equation for the electric component with Maxwell's equations for the magnetic components. This hybrid formulation enables the calculation of the time dependent parts of the interface jump conditions, so that one can track the transient changes in the regularities of the electromagnetic fields across a dispersive interface. Effective matched interface and boundary (MIB) treatments are proposed to rigorously impose the physical jump conditions which are not only time dependent, but also couple both Cartesian directions and both magnetic field components. Based on a staggered Yee lattice, the proposed MIB scheme can deal with arbitrarily curved interfaces and nonsmooth interfaces with sharped edges. Second order convergences are numerically achieved in solving dispersive interface problems with constant curvatures, general curvatures, and nonsmooth corners.

Nguyen, Duc Duy; Zhao, Shan

2014-12-01

156

The Interface Between Theory and Data in Structural Equation Models  

USGS Publications Warehouse

Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite, for representing general concepts. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling general relationships of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially reduced form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influences of suites of variables are often of interest.

Grace, James B.; Bollen, Kenneth A.

2006-01-01

157

Mathematical modeling of dispersion in single interface flow analysis.  

PubMed

This work describes the optimization of the recently proposed fluid management methodology single interface flow analysis (SIFA) using chemometrics modelling. The influence of the most important physical and hydrodynamic flow parameters of SIFA systems on the axial dispersion coefficients estimated with the axially dispersed plug-flow model, was evaluated with chemometrics linear (multivariate linear regression) and non-linear (simple multiplicative and feed-forward neural networks) models. A D-optimal experimental design built with three reaction coil properties (length, configuration and internal diameter), flow-cell volume and flow rate, was adopted to generate the experimental data. Bromocresol green was used as the dye solution and the analytical signals were monitored by spectrophotometric detection at 614 nm. Results demonstrate that, independent of the model type, the statistically relevant parameters were the reactor coil length and internal diameter and the flow rate. The linear and non-linear multiplicative models were able to estimate the axial dispersion coefficient with validation r(2)=0.86. Artificial neural networks estimated the same parameter with an increased accuracy (r(2)=0.93), demonstrating that relations between the physical parameters and the dispersion phenomena are highly non-linear. The analysis of the response surface control charts simulated with the developed models allowed the interpretation of the relationships between the physical parameters and the dispersion processes. PMID:20206008

Rodrigues, S Sofia M; Marques, Karine L; Lopes, João A; Santos, João L M; Lima, José L F C

2010-03-24

158

Computational design of patterned interfaces using reduced order models  

E-print Network

Patterning is a familiar approach for imparting novel functionalities to free surfaces. We extend the patterning paradigm to interfaces between crystalline solids. Many interfaces have non-uniform internal structures ...

Vattre, Aurelien

159

WIZER: What-If Analyzer for Automated Social Model Space Exploration and Validation  

E-print Network

WIZER: What-If Analyzer for Automated Social Model Space Exploration and Validation Alex Yahja Acknowledgement: This research was supported, in part, by DARPA for work on Scalable Biosurveillance Systems are those of the authors and do not necessarily reflect the views of DARPA, the National Science Foundation

Sadeh, Norman M.

160

IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION, 1996. 1 Adaptive ModelBased Hybrid Control of  

E-print Network

algorithm for robot arms. This controller provides simultaneous po­ sition and force trajectory tracking of rigidly constrained rigid arms addressed in herein di#ers significantly from the prob­ lem of controlIEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION, 1996. 1 Adaptive Model­Based Hybrid Control

Whitcomb, Louis L.

161

MobiGUITAR A Tool for Automated Model-Based Testing of Mobile Apps  

E-print Network

MobiGUITAR ­ A Tool for Automated Model-Based Testing of Mobile Apps Domenico Amalfitano, Anna Rita that mobile platforms are largely adopted because of the apps they offer [1], [2]. The issue of app quality testing, one of the most frequently used QA techniques, even in the mobile app context. A relevant family

Memon, Atif M.

162

Automated Test Assembly for Cognitive Diagnosis Models Using a Genetic Algorithm  

ERIC Educational Resources Information Center

Much recent psychometric literature has focused on cognitive diagnosis models (CDMs), a promising class of instruments used to measure the strengths and weaknesses of examinees. This article introduces a genetic algorithm to perform automated test assembly alongside CDMs. The algorithm is flexible in that it can be applied whether the goal is to…

Finkelman, Matthew; Kim, Wonsuk; Roussos, Louis A.

2009-01-01

163

Modeling Multiple Human-Automation Distributed Systems using Network-form Games  

NASA Technical Reports Server (NTRS)

The paper describes at a high-level the network-form game framework (based on Bayes net and game theory), which can be used to model and analyze safety issues in large, distributed, mixed human-automation systems such as NextGen.

Brat, Guillaume

2012-01-01

164

LT Tyson Scofield, USCG and Dr. Alan Brown Manning and Automation Model for Naval Ship  

E-print Network

1 LT Tyson Scofield, USCG and Dr. Alan Brown Manning and Automation Model for Naval Ship Analysis and Optimization ABSTRACT The manning of a ship is a major driver of total ownership cost. The Government Accounting Office (GAO) states that "the cost of the ship's crew is the largest expense incurred over

Brown, Alan

165

Automating Prostate Capsule Contour Estimation for 3D Model Reconstruction Using Shape and Histological Features  

E-print Network

Automating Prostate Capsule Contour Estimation for 3D Model Reconstruction Using Shape to compare the efficiency of different form of cancerous prostate surgical removal. An accurate assessment of the percentage and depth of extra-capsular soft tissue removed with the prostate by the various surgical

McKenzie, Rick

166

Automated substrate resistance extraction in nanoscale VLSI by exploiting a geometry-based analytical model  

Microsoft Academic Search

In this work, a new automated method for determining the substrate resistance is presented. It exploits a geometric formulation of the current streamlines between coupled structures and builds an analytical model for the substrate resistance. Both simulation and measurement data are utilized in order to show the validity of the proposed scheme. The measurement data are obtained from a fabricated

Yiorgos I. Bontzios; Michael G. Dimopoulos; Alkis A. Hatzopoulos

2011-01-01

167

Evaluation of automated cell disruptor methods for oomycetous and ascomycetous model organisms  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two automated cell disruptor-based methods for RNA extraction; disruption of thawed cells submerged in TRIzol Reagent (method QP), and direct disruption of frozen cells on dry ice (method CP), were optimized for a model oomycete, Phytophthora capsici, and compared with grinding in a mortar and pestl...

168

Automated volumetric grid generation for finite element modeling of human hand joints  

SciTech Connect

We are developing techniques for finite element analysis of human joints. These techniques need to provide high quality results rapidly in order to be useful to a physician. The research presented here increases model quality and decreases user input time by automating the volumetric mesh generation step.

Hollerbach, K.; Underhill, K. [Lawrence Livermore National Lab., CA (United States); Rainsberger, R. [XYZ Scientific Applications, Inc., Livermore, CA (United States)

1995-02-01

169

The electrical behavior of GaAs-insulator interfaces - A discrete energy interface state model  

NASA Technical Reports Server (NTRS)

The relationship between the electrical behavior of GaAs Metal Insulator Semiconductor (MIS) structures and the high density discrete energy interface states (0.7 and 0.9 eV below the conduction band) was investigated utilizing photo- and thermal emission from the interface states in conjunction with capacitance measurements. It was found that all essential features of the anomalous behavior of GaAs MIS structures, such as the frequency dispersion and the C-V hysteresis, can be explained on the basis of nonequilibrium charging and discharging of the high density discrete energy interface states.

Kazior, T. E.; Lagowski, J.; Gatos, H. C.

1983-01-01

170

INCORPORATION OF A LANGUAGE MODEL INTO A BRAIN COMPUTER INTERFACE BASED SPELLER THROUGH HMMs  

E-print Network

INCORPORATION OF A LANGUAGE MODEL INTO A BRAIN COMPUTER INTERFACE BASED SPELLER THROUGH HMMs Ã?ada, 34956 Istanbul, Turkey ABSTRACT Brain computer interface (BCI) research deals with the problem control and may be unable to communicate. The idea of brain-computer interfaces (BCIs) involves

Yanikoglu, Berrin

171

Semi-Automated 3D City Modeling Using Stereo High-Resolution Satellite Images  

Microsoft Academic Search

This paper presents a methodology for generating semi-automated 3D models of urban area from stereo high-resolution satellite images. Prevalent adoption of the Rational Function Model (RFM) during recent years as a replacement for rigorous satellite orientation sensor model by most commercial imagery providers, makes 3D information extraction fast and reliable for most end-users. This paper presents an application of RFM

Pooya Sarabandi; Anne S. Kiremidjian; Ronald T. Eguchi

172

A continuously growing web-based interface structure databank  

NASA Astrophysics Data System (ADS)

The macroscopic properties of materials can be significantly influenced by the presence of microscopic interfaces. The complexity of these interfaces coupled with the vast configurational space in which they reside has been a long-standing obstacle to the advancement of true bottom-up material behavior predictions. In this vein, atomistic simulations have proven to be a valuable tool for investigating interface behavior. However, before atomistic simulations can be utilized to model interface behavior, meaningful interface atomic structures must be generated. The generation of structures has historically been carried out disjointly by individual research groups, and thus, has constituted an overlap in effort across the broad research community. To address this overlap and to lower the barrier for new researchers to explore interface modeling, we introduce a web-based interface structure databank (www.isdb.cee.cornell.edu) where users can search, download and share interface structures. The databank is intended to grow via two mechanisms: (1) interface structure donations from individual research groups and (2) an automated structure generation algorithm which continuously creates equilibrium interface structures. In this paper, we describe the databank, the automated interface generation algorithm, and compare a subset of the autonomously generated structures to structures currently available in the literature. To date, the automated generation algorithm has been directed toward aluminum grain boundary structures, which can be compared with experimentally measured population densities of aluminum polycrystals.

Erwin, N. A.; Wang, E. I.; Osysko, A.; Warner, D. H.

2012-07-01

173

Modeling Automated Highway Systems with VeriJ Universite Pierre & Marie Curie, CNRS-UMR7606 (LIP6/MoVe)  

E-print Network

Modeling Automated Highway Systems with VeriJ ZHANG Yan Universit´e Pierre & Marie Curie, CNRS of an automated highway system is used to present the basic constructs of the language. 1 Introduction Modeling to handle low level models or complex specification formalisms. The area of automated highway systems

Paris-Sud XI, Université de

174

Parallelization of a hydrological model using the message passing interface  

USGS Publications Warehouse

With the increasing knowledge about the natural processes, hydrological models such as the Soil and Water Assessment Tool (SWAT) are becoming larger and more complex with increasing computation time. Additionally, other procedures such as model calibration, which may require thousands of model iterations, can increase running time and thus further reduce rapid modeling and analysis. Using the widely-applied SWAT as an example, this study demonstrates how to parallelize a serial hydrological model in a Windows® environment using a parallel programing technology—Message Passing Interface (MPI). With a case study, we derived the optimal values for the two parameters (the number of processes and the corresponding percentage of work to be distributed to the master process) of the parallel SWAT (P-SWAT) on an ordinary personal computer and a work station. Our study indicates that model execution time can be reduced by 42%–70% (or a speedup of 1.74–3.36) using multiple processes (two to five) with a proper task-distribution scheme (between the master and slave processes). Although the computation time cost becomes lower with an increasing number of processes (from two to five), this enhancement becomes less due to the accompanied increase in demand for message passing procedures between the master and all slave processes. Our case study demonstrates that the P-SWAT with a five-process run may reach the maximum speedup, and the performance can be quite stable (fairly independent of a project size). Overall, the P-SWAT can help reduce the computation time substantially for an individual model run, manual and automatic calibration procedures, and optimization of best management practices. In particular, the parallelization method we used and the scheme for deriving the optimal parameters in this study can be valuable and easily applied to other hydrological or environmental models.

Wu, Yiping; Li, Tiejian; Sun, Liqun; Chen, Ji

2013-01-01

175

Automated NMR Fragment Based Screening Identified a Novel Interface Blocker to the LARG/RhoA Complex  

PubMed Central

The small GTPase cycles between the inactive GDP form and the activated GTP form, catalyzed by the upstream guanine exchange factors. The modulation of such process by small molecules has been proven to be a fruitful route for therapeutic intervention to prevent the over-activation of the small GTPase. The fragment based approach emerging in the past decade has demonstrated its paramount potential in the discovery of inhibitors targeting such novel and challenging protein-protein interactions. The details regarding the procedure of NMR fragment screening from scratch have been rarely disclosed comprehensively, thus restricts its wider applications. To achieve a consistent screening applicable to a number of targets, we developed a highly automated protocol to cover every aspect of NMR fragment screening as possible, including the construction of small but diverse libray, determination of the aqueous solubility by NMR, grouping compounds with mutual dispersity to a cocktail, and the automated processing and visualization of the ligand based screening spectra. We exemplified our streamlined screening in RhoA alone and the complex of the small GTPase RhoA and its upstream guanine exchange factor LARG. Two hits were confirmed from the primary screening in cocktail and secondary screening over individual hits for LARG/RhoA complex, while one of them was also identified from the screening for RhoA alone. HSQC titration of the two hits over RhoA and LARG alone, respectively, identified one compound binding to RhoA.GDP at a 0.11 mM affinity, and perturbed the residues at the switch II region of RhoA. This hit blocked the formation of the LARG/RhoA complex, validated by the native gel electrophoresis, and the titration of RhoA to 15N labeled LARG in the absence and presence the compound, respectively. It therefore provides us a starting point toward a more potent inhibitor to RhoA activation catalyzed by LARG. PMID:24505392

Gao, Jia; Ma, Rongsheng; Wang, Wei; Wang, Na; Sasaki, Ryan; Snyderman, David; Wu, Jihui; Ruan, Ke

2014-01-01

176

Automated Measurement and Statistical Modeling of Elastic Laminae in Arteries  

PubMed Central

Structural features of elastic laminae within arteries can provide vital information for both the mechanobiology and the biomechanics of the wall. In this paper, we propose, test, and illustrate a new computer-based scheme for automated analysis of regional distributions of elastic laminae thickness, inter-lamellar distances, and fragmentation (furcation points) from standard histological images. Our scheme eliminates potential artifacts produced by tissue cutting, automatically aligns tissue according to physiologic orientations, and performs cross-sectional measurements along radial directions. A statistical randomized complete block design (RCBD) and F-test were used to assess potential (non)-uniformity of lamellar thicknesses and separations along both radial and circumferential directions. Illustrative results for both normotensive and hypertensive thoracic porcine aorta revealed marked heterogeneity along the radial direction in nearly stress-free samples. Clearly, regional measurements can provide more detailed information about morphologic changes that cannot be gained by globally averaged evaluations alone. We also found that quantifying Furcation Point densities offers new information about potential elastin fragmentation, particularly in response to increased loading due to hypertension. PMID:20221934

Xu, Hai; Hu, Jin-Jia; Humphrey, Jay D.; Liu, Jyh-Charn

2010-01-01

177

Efficient Parallel Levenberg-Marquardt Model Fitting towards Real-Time Automated Parametric Imaging Microscopy  

PubMed Central

We present a fast, accurate and robust parallel Levenberg-Marquardt minimization optimizer, GPU-LMFit, which is implemented on graphics processing unit for high performance scalable parallel model fitting processing. GPU-LMFit can provide a dramatic speed-up in massive model fitting analyses to enable real-time automated pixel-wise parametric imaging microscopy. We demonstrate the performance of GPU-LMFit for the applications in superresolution localization microscopy and fluorescence lifetime imaging microscopy. PMID:24130785

Zhu, Xiang; Zhang, Dianwen

2013-01-01

178

Petri net-based modelling of human-automation conflicts in aviation.  

PubMed

Analyses of aviation safety reports reveal that human-machine conflicts induced by poor automation design are remarkable precursors of accidents. A review of different crew-automation conflicting scenarios shows that they have a common denominator: the autopilot behaviour interferes with the pilot's goal regarding the flight guidance via 'hidden' mode transitions. Considering both the human operator and the machine (i.e. the autopilot or the decision functions) as agents, we propose a Petri net model of those conflicting interactions, which allows them to be detected as deadlocks in the Petri net. In order to test our Petri net model, we designed an autoflight system that was formally analysed to detect conflicting situations. We identified three conflicting situations that were integrated in an experimental scenario in a flight simulator with 10 general aviation pilots. The results showed that the conflicts that we had a-priori identified as critical had impacted the pilots' performance. Indeed, the first conflict remained unnoticed by eight participants and led to a potential collision with another aircraft. The second conflict was detected by all the participants but three of them did not manage the situation correctly. The last conflict was also detected by all the participants but provoked typical automation surprise situation as only one declared that he had understood the autopilot behaviour. These behavioural results are discussed in terms of workload and number of fired 'hidden' transitions. Eventually, this study reveals that both formal and experimental approaches are complementary to identify and assess the criticality of human-automation conflicts. Practitioner Summary: We propose a Petri net model of human-automation conflicts. An experiment was conducted with general aviation pilots performing a scenario involving three conflicting situations to test the soundness of our formal approach. This study reveals that both formal and experimental approaches are complementary to identify and assess the criticality conflicts. PMID:24444329

Pizziol, Sergio; Tessier, Catherine; Dehais, Frédéric

2014-01-01

179

Automated dynamic analytical model improvement for damped structures  

NASA Technical Reports Server (NTRS)

A method is described to improve a linear nonproportionally damped analytical model of a structure. The procedure finds the smallest changes in the analytical model such that the improved model matches the measured modal parameters. Features of the method are: (1) ability to properly treat complex valued modal parameters of a damped system; (2) applicability to realistically large structural models; and (3) computationally efficiency without involving eigensolutions and inversion of a large matrix.

Fuh, J. S.; Berman, A.

1985-01-01

180

Graphical User Interface for Simulink Integrated Performance Analysis Model  

NASA Technical Reports Server (NTRS)

The J-2X Engine (built by Pratt & Whitney Rocketdyne,) in the Upper Stage of the Ares I Crew Launch Vehicle, will only start within a certain range of temperature and pressure for Liquid Hydrogen and Liquid Oxygen propellants. The purpose of the Simulink Integrated Performance Analysis Model is to verify that in all reasonable conditions the temperature and pressure of the propellants are within the required J-2X engine start boxes. In order to run the simulation, test variables must be entered at all reasonable values of parameters such as heat leak and mass flow rate. To make this testing process as efficient as possible in order to save the maximum amount of time and money, and to show that the J-2X engine will start when it is required to do so, a graphical user interface (GUI) was created to allow the input of values to be used as parameters in the Simulink Model, without opening or altering the contents of the model. The GUI must allow for test data to come from Microsoft Excel files, allow those values to be edited before testing, place those values into the Simulink Model, and get the output from the Simulink Model. The GUI was built using MATLAB, and will run the Simulink simulation when the Simulate option is activated. After running the simulation, the GUI will construct a new Microsoft Excel file, as well as a MATLAB matrix file, using the output values for each test of the simulation so that they may graphed and compared to other values.

Durham, R. Caitlyn

2009-01-01

181

MSG: A Computer System for Automated Modeling of Heat Transfer  

E-print Network

behavior. The models are sets of equations which may include algebraic equations, ordinary differen­ tial equations and partial differential equations. MSG uses the strong domain theory to guide model construction is a model, i.e. a set of mathematical equations, which may include algebraic, ordi­ nary differential

Steinberg, Louis

182

Continental hydrosystem modelling: the concept of nested stream-aquifer interfaces  

NASA Astrophysics Data System (ADS)

Recent developments in hydrological modelling are based on a view of the interface being a single continuum through which water flows. These coupled hydrological-hydrogeological models, emphasising the importance of the stream-aquifer interface, are more and more used in hydrological sciences for pluri-disciplinary studies aiming at investigating environmental issues. This notion of a single continuum, which is accepted by the hydrological modellers, originates in the historical modelling of hydrosystems based on the hypothesis of a homogeneous media that led to the Darcy law. There is then a need to first bridge the gap between hydrological and eco-hydrological views of the stream-aquifer interfaces, and, secondly, to rationalise the modelling of stream-aquifer interface within a consistent framework that fully takes into account the multi-dimensionality of the stream-aquifer interfaces. We first define the concept of nested stream-aquifer interfaces as a key transitional component of continental hydrosystem. Based on a literature review, we then demonstrate the usefulness of the concept for the multi-dimensional study of the stream-aquifer interface, with a special emphasis on the stream network, which is identified as the key component for scaling hydrological processes occurring at the interface. Finally we focus on the stream-aquifer interface modelling at different scales, with up-to-date methodologies and give some guidances for the multi-dimensional modelling of the interface using the innovative methodology MIM (Measurements-Interpolation-Modelling), which is graphically developed, scaling in space the three pools of methods needed to fully understand stream-aquifer interfaces at various scales. The outcome of MIM is the localisation in space of the stream-aquifer interface types that can be studied by a given approach. The efficiency of the method is demonstrated with two approaches from the local (~1 m) to the continental (<10 M km2) scale.

Flipo, N.; Mouhri, A.; Labarthe, B.; Biancamaria, S.

2014-01-01

183

A 2-D Interface Element for Coupled Analysis of Independently Modeled 3-D Finite Element Subdomains  

NASA Technical Reports Server (NTRS)

Over the past few years, the development of the interface technology has provided an analysis framework for embedding detailed finite element models within finite element models which are less refined. This development has enabled the use of cascading substructure domains without the constraint of coincident nodes along substructure boundaries. The approach used for the interface element is based on an alternate variational principle often used in deriving hybrid finite elements. The resulting system of equations exhibits a high degree of sparsity but gives rise to a non-positive definite system which causes difficulties with many of the equation solvers in general-purpose finite element codes. Hence the global system of equations is generally solved using, a decomposition procedure with pivoting. The research reported to-date for the interface element includes the one-dimensional line interface element and two-dimensional surface interface element. Several large-scale simulations, including geometrically nonlinear problems, have been reported using the one-dimensional interface element technology; however, only limited applications are available for the surface interface element. In the applications reported to-date, the geometry of the interfaced domains exactly match each other even though the spatial discretization within each domain may be different. As such, the spatial modeling of each domain, the interface elements and the assembled system is still laborious. The present research is focused on developing a rapid modeling procedure based on a parametric interface representation of independently defined subdomains which are also independently discretized.

Kandil, Osama A.

1998-01-01

184

A Voyage to Arcturus: A model for automated management of a WLCG Tier-2 facility  

NASA Astrophysics Data System (ADS)

With the current trend towards "On Demand Computing" in big data environments it is crucial that the deployment of services and resources becomes increasingly automated. Deployment based on cloud platforms is available for large scale data centre environments but these solutions can be too complex and heavyweight for smaller, resource constrained WLCG Tier-2 sites. Along with a greater desire for bespoke monitoring and collection of Grid related metrics, a more lightweight and modular approach is desired. In this paper we present a model for a lightweight automated framework which can be use to build WLCG grid sites, based on "off the shelf" software components. As part of the research into an automation framework the use of both IPMI and SNMP for physical device management will be included, as well as the use of SNMP as a monitoring/data sampling layer such that more comprehensive decision making can take place and potentially be automated. This could lead to reduced down times and better performance as services are recognised to be in a non-functional state by autonomous systems.

Roy, Gareth; Crooks, David; Mertens, Lena; Mitchell, Mark; Purdie, Stuart; Cadellin Skipsey, Samuel; Britton, David

2014-06-01

185

A bidirectional interface growth model for cranial interosseous suture morphogenesis  

PubMed Central

Interosseous sutures exhibit highly variable patterns of interdigitation and corrugation. Recent research has identified fundamental molecular mechanisms of suture formation, and computer models have been used to simulate suture morphogenesis. However, the role of bone strain in the development of complex sutures is largely unknown, and measuring suture morphologies beyond the evaluation of fractal dimensions remains a challenge. Here we propose a morphogenetic model of suture formation, which is based on the paradigm of Laplacian interface growth. Computer simulations of suture morphogenesis under various boundary conditions generate a wide variety of synthetic sutural forms. Their morphologies are quantified with a combination of Fourier analysis and principal components analysis, and compared with natural morphological variation in an ontogenetic sample of human interparietal suture lines. Morphometric analyses indicate that natural sutural shapes exhibit a complex distribution in morphospace. The distribution of synthetic sutures closely matches the natural distribution. In both natural and synthetic systems, sutural complexity increases during morphogenesis. Exploration of the parameter space of the simulation system indicates that variation in strain and/or morphogen sensitivity and viscosity of sutural tissue may be key factors in generating the large variability of natural suture complexity. PMID:21539540

Zollikofer, Christoph P E; Weissmann, John David

2011-01-01

186

Automated generation of compact models for fluidic microsystems  

NASA Astrophysics Data System (ADS)

Simulation and design of microfluidic systems requires various level models: high-fidelity models for design and optimization of particular elements and devices as well as system-level models allowing for VLSI-scale simulation of such systems. For the latter purpose, reduced or compact models are necessary to make such system simulations computationally feasible. In this paper, we present a design methodology and practical approach for generation of compact models of microfluidic elements. In this procedure we use high-fidelity 3D simulations of the microfluidic devices to extract their characteristics for compact models, and subsequently, to validate the compact model behavior in various regimes of operation. The compact models are generated automatically in the formats that can be directly used in SPICE or SABER. As an example of a nonlinear fluidic device, the generation of compact model for 'Tesla valve' is described in detail. Tesla valve is one of the no-moving- parts valves used in micropumps in MEMS. Its principle of operation is based on the rectification of the fluid, so it may be considered as a 'fluidic diode'.

Turowski, Marek; Chen, Zhijian; Przekwas, Andrzej J.

2000-04-01

187

Automated protein model building combined with iterative structure refinement  

Microsoft Academic Search

In protein crystallography, much time and effort are often required to trace an initial model from an interpretable electron density map and to refine it until it best agrees with the crystallographic data. Here, we present a method to build and refine a protein model automatically and without user intervention, starting from diffraction data extending to resolution higher than 2.3

Richard Morris; Victor S. Lamzin; Anastassis Perrakis

1999-01-01

188

TIM/WIM: A Set of Tools to Interface Modelling in Biology. Franois Valle  

E-print Network

TIM/WIM: A Set of Tools to Interface Modelling in Biology. François Vallée LaBRI - UMR 3800 for integrating heterogeneous data in a core interface. TIM (Tools to Input Models) is a tool which allows to put) experiments and used to simulate flux through metabolic networks. TIM is able to manage the widely used

Paris-Sud XI, Université de

189

Automated parametrical antenna modelling for ambient assisted living applications  

NASA Astrophysics Data System (ADS)

In this paper a parametric modeling technique for a fast polynomial extraction of the physically relevant parameters of inductively coupled RFID/NFC (radio frequency identification/near field communication) antennas is presented. The polynomial model equations are obtained by means of a three-step procedure: first, full Partial Element Equivalent Circuit (PEEC) antenna models are determined by means of a number of parametric simulations within the input parameter range of a certain antenna class. Based on these models, the RLC antenna parameters are extracted in a subsequent model reduction step. Employing these parameters, polynomial equations describing the antenna parameter with respect to (w.r.t.) the overall antenna input parameter range are extracted by means of polynomial interpolation and approximation of the change of the polynomials' coefficients. The described approach is compared to the results of a reference PEEC solver with regard to accuracy and computation effort.

Kazemzadeh, R.; John, W.; Mathis, W.

2012-09-01

190

Man power/cost estimation model: Automated planetary projects  

NASA Technical Reports Server (NTRS)

A manpower/cost estimation model is developed which is based on a detailed level of financial analysis of over 30 million raw data points which are then compacted by more than three orders of magnitude to the level at which the model is applicable. The major parameter of expenditure is manpower (specifically direct labor hours) for all spacecraft subsystem and technical support categories. The resultant model is able to provide a mean absolute error of less than fifteen percent for the eight programs comprising the model data base. The model includes cost saving inheritance factors, broken down in four levels, for estimating follow-on type programs where hardware and design inheritance are evident or expected.

Kitchen, L. D.

1975-01-01

191

Morphology Based Cohesive Zone Modeling of the Cement-Bone Interface from Postmortem Retrievals  

PubMed Central

In cemented total hip arthroplasty, the cement-bone interface can be considerably degenerated after less than one year in-vivo service; this makes the interface much weaker relative to the direct post-operative situation. It is, however, still unknown how these degenerated interfaces behave under mixed-mode loading and how this is related to the morphology of the interface. In this study, we used a finite element approach to analyze the mixed-mode response of the cement-bone interface taken from postmortem retrievals and we investigated whether it was feasible to generate a fully elastic and a failure cohesive model based on only morphological input parameters. Computed tomography-based finite element analysis models of the postmortem cement-bone interface were generated and the interface morphology was determined. The models were loaded until failure in multiple directions by allowing cracking of the bone and cement components and including periodic boundary conditions. The resulting stiffness was related to the interface morphology. A closed form mixed-mode cohesive model that included failure was determined and related to the interface morphology. The responses of the finite element simulations compare satisfactorily with experimental observations, albeit the magnitude of the strength and stiffness are somewhat overestimated. Surprisingly, the finite element simulations predict no failure under shear loading and a considerable normal compression is generated which prevents dilation of the interface. The obtained mixed-mode stiffness response could subsequently be related to the interface morphology and subsequently be formulated into an elastic cohesive zone model. Finally, the acquired data could be used as an input for a cohesive model that also includes interface failure. PMID:21783159

Waanders, Daan; Janssen, Dennis; Mann, Kenneth A.; Verdonschot, Nico

2011-01-01

192

Automation based on knowledge modeling theory and its applications in engine diagnostic systems using Space Shuttle Main Engine vibrational data  

NASA Astrophysics Data System (ADS)

Humans can perform many complicated tasks without explicit rules. This inherent and advantageous capability becomes a hurdle when a task is to be automated. Modern computers and numerical calculations require explicit rules and discrete numerical values. In order to bridge the gap between human knowledge and automating tools, a knowledge model is proposed. Knowledge modeling techniques are discussed and utilized to automate a labor and time intensive task of detecting anomalous bearing wear patterns in the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP).

Kim, Jonnathan H.

1995-04-01

193

An application of structural modeling and automated reasoning to real-time systems design  

Microsoft Academic Search

This paper presents an application of structural modeling and automated reasoning as a software development environment for real-time systems. This application satisfies two major requirements for such an environment: (1) to synthesize an absolutely correct program and, (2) to increase software productivity. The real-time systems, which consist of concurrent programs, are described by a Prolog based concurrent object-oriented language, called

Shinichi Honiden; Naoshi Uchihira; Kazunori Matsumoto; Kazuo Matsumura; Masahiko Arai

1990-01-01

194

Automated mask creation from a 3D model using Faethm.  

SciTech Connect

We have developed and implemented a method which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micro-machining. The masks produced by this design tool can be generic, process independent masks, or if given process constraints, specific for a target process. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology of the model.

Schiek, Richard Louis; Schmidt, Rodney Cannon

2007-11-01

195

Synopsis of the Model Making Automation Process Technology  

Microsoft Academic Search

This document provides a synopsis of the unique attributes of MMAP, emphasizing its utilityfor analysis purposes. A definition of the type of distributed system MMAP is best used with isdescribed next so that the model construction obstacles that MMAP overcomes can be highlightedin the following section. Then a description of MMAP is provided. The application of MMAP toanalyzing a Java

Curtis Hrischuk

196

Environment Modeling for Automated Testing of Cloud Applications  

E-print Network

}@microsoft.com, {xxm, lj}@nju.edu.cn Abstract: Recently, cloud computing platforms, such as Microsoft Azure-intensive computing. To ensure high quality of cloud applications under development, developer testing (also referred Cloud Computing, Software Testing, Dynamic Symbolic Execution, Cloud Environment Model Introduction

Xie, Tao

197

Automated model-based organ delineation for radiotherapy planning in prostatic region  

SciTech Connect

Purpose: Organ delineation is one of the most tedious and time-consuming parts of radiotherapy planning. It is usually performed by manual contouring in two-dimensional slices using simple drawing tools, and it may take several hours to delineate all structures of interest in a three-dimensional (3D) data set used for planning. In this paper, a 3D model-based approach to automated organ delineation is introduced that allows for a significant reduction of the time required for contouring. Methods and materials: The presented method is based on an adaptation of 3D deformable surface models to the boundaries of the anatomic structures of interest. The adaptation is based on a tradeoff between deformations of the model induced by its attraction to certain image features and the shape integrity of the model. To make the concept clinically feasible, interactive tools are introduced that allow quick correction in problematic areas in which the automated model adaptation may fail. A feasibility study with 40 clinical data sets was done for the male pelvic area, in which the risk organs (bladder, rectum, and femoral heads) were segmented by automatically adapting the corresponding organ models. Results: In several cases of the validation study, minor user interaction was required. Nevertheless, a statistically significant reduction in the time required compared with manual organ contouring was achieved. The results of the validation study showed that the presented model-based approach is accurate (1.0-1.7 mm mean error) for the tested anatomic structures. Conclusion: A framework for organ delineation in radiotherapy planning is presented, including automated 3D model-based segmentation, as well as tools for interactive corrections. We demonstrated that the proposed approach is significantly more efficient than manual contouring in two-dimensional slices.

Pekar, Vladimir [Philips Research Laboratories, Hamburg (Germany)]. E-mail: vladimir.pekar@philips.com; McNutt, Todd R. [Philips Medical Systems, Madison, WI (United States); Kaus, Michael R. [Philips Medical Systems, Madison, WI (United States)

2004-11-01

198

Automated volumetric breast density derived by shape and appearance modeling  

NASA Astrophysics Data System (ADS)

The image shape and texture (appearance) estimation designed for facial recognition is a novel and promising approach for application in breast imaging. The purpose of this study was to apply a shape and appearance model to automatically estimate percent breast fibroglandular volume (%FGV) using digital mammograms. We built a shape and appearance model using 2000 full-field digital mammograms from the San Francisco Mammography Registry with known %FGV measured by single energy absorptiometry method. An affine transformation was used to remove rotation, translation and scale. Principal Component Analysis (PCA) was applied to extract significant and uncorrelated components of %FGV. To build an appearance model, we transformed the breast images into the mean texture image by piecewise linear image transformation. Using PCA the image pixels grey-scale values were converted into a reduced set of the shape and texture features. The stepwise regression with forward selection and backward elimination was used to estimate the outcome %FGV with shape and appearance features and other system parameters. The shape and appearance scores were found to correlate moderately to breast %FGV, dense tissue volume and actual breast volume, body mass index (BMI) and age. The highest Pearson correlation coefficient was equal 0.77 for the first shape PCA component and actual breast volume. The stepwise regression method with ten-fold cross-validation to predict %FGV from shape and appearance variables and other system outcome parameters generated a model with a correlation of r2 = 0.8. In conclusion, a shape and appearance model demonstrated excellent feasibility to extract variables useful for automatic %FGV estimation. Further exploring and testing of this approach is warranted.

Malkov, Serghei; Kerlikowske, Karla; Shepherd, John

2014-03-01

199

Automated Volumetric Breast Density derived by Shape and Appearance Modeling.  

PubMed

The image shape and texture (appearance) estimation designed for facial recognition is a novel and promising approach for application in breast imaging. The purpose of this study was to apply a shape and appearance model to automatically estimate percent breast fibroglandular volume (%FGV) using digital mammograms. We built a shape and appearance model using 2000 full-field digital mammograms from the San Francisco Mammography Registry with known %FGV measured by single energy absorptiometry method. An affine transformation was used to remove rotation, translation and scale. Principal Component Analysis (PCA) was applied to extract significant and uncorrelated components of %FGV. To build an appearance model, we transformed the breast images into the mean texture image by piecewise linear image transformation. Using PCA the image pixels grey-scale values were converted into a reduced set of the shape and texture features. The stepwise regression with forward selection and backward elimination was used to estimate the outcome %FGV with shape and appearance features and other system parameters. The shape and appearance scores were found to correlate moderately to breast %FGV, dense tissue volume and actual breast volume, body mass index (BMI) and age. The highest Pearson correlation coefficient was equal 0.77 for the first shape PCA component and actual breast volume. The stepwise regression method with ten-fold cross-validation to predict %FGV from shape and appearance variables and other system outcome parameters generated a model with a correlation of r(2) = 0.8. In conclusion, a shape and appearance model demonstrated excellent feasibility to extract variables useful for automatic %FGV estimation. Further exploring and testing of this approach is warranted. PMID:25083119

Malkov, Serghei; Kerlikowske, Karla; Shepherd, John

2014-03-22

200

Interfaces in driven Ising models: shear enhances confinement  

E-print Network

We use a phase-separated driven two-dimensional Ising lattice gas to study fluid interfaces exposed to shear flow parallel to the interface. The interface is stabilized by two parallel walls with opposing surface fields and a driving field parallel to the walls is applied which (i) either acts locally at the walls or (ii) varies linearly with distance across the strip. Using computer simulations with Kawasaki dynamics, we find that the system reaches a steady state in which the magnetisation profile is the same as that in equilibrium, but with a rescaled length implying a reduction of the interfacial width. An analogous effect was recently observed in sheared phase-separated colloidal dispersions. Pair correlation functions along the interface decay more rapidly with distance under drive than in equilibrium and for cases of weak drive can be rescaled to the equilibrium result.

Thomas H. R. Smith; Oleg Vasilyev; Douglas B. Abraham; Anna Macio?ek; Matthias Schmidt

2008-02-26

201

Kestrel: An Interface from Modeling Systems to the NEOS Server  

E-print Network

may be solved more effectively, and new solver technologies may be disseminated more rapidly. .... The development of the Kestrel interface has also led ..... With AMPL, the only change is to set kestrel_options to provide the job number and ...

4er PowerMac G4

2002-09-30

202

Automated calibration of a stream solute transport model: Implications for interpretation of biogeochemical parameters  

USGS Publications Warehouse

The hydrologic processes of advection, dispersion, and transient storage are the primary physical mechanisms affecting solute transport in streams. The estimation of parameters for a conservative solute transport model is an essential step to characterize transient storage and other physical features that cannot be directly measured, and often is a preliminary step in the study of reactive solutes. Our study used inverse modeling to estimate parameters of the transient storage model OTIS (One dimensional Transport with Inflow and Storage). Observations from a tracer injection experiment performed on Uvas Creek, California, USA, are used to illustrate the application of automated solute transport model calibration to conservative and nonconservative stream solute transport. A computer code for universal inverse modeling (UCODE) is used for the calibrations. Results of this procedure are compared with a previous study that used a trial-and-error parameter estimation approach. The results demonstrated 1) importance of the proper estimation of discharge and lateral inflow within the stream system; 2) that although the fit of the observations is not much better when transient storage is invoked, a more randomly distributed set of residuals resulted (suggesting non-systematic error), indicating that transient storage is occurring; 3) that inclusion of transient storage for a reactive solute (Sr2+) provided a better fit to the observations, highlighting the importance of robust model parameterization; and 4) that applying an automated calibration inverse modeling estimation approach resulted in a comprehensive understanding of the model results and the limitation of input data.

Scott, D.T.; Gooseff, M.N.; Bencala, K.E.; Runkel, R.L.

2003-01-01

203

Sacks R. (1998), `Issues in the Development and Implementation of a Building Project Model for an Automated Building System', International Journal of Construction Information Technology, Salford University, Salford  

E-print Network

for an Automated Building System', International Journal of Construction Information Technology, Salford University FOR AN AUTOMATED BUILDING SYSTEM R. Sacks1 ABSTRACT: While other generalized building project models have been of an Automated, Computer Integrated Building Realization System is to automatically generate all

Sacks, Rafael

204

Automated Antenna Orientation For Wireless Data Transfer Using Bayesian Modeling  

NASA Astrophysics Data System (ADS)

The problem of attaining a usable wireless connection at an arbitrary location is one of great concern to mobile end users. The majority of antennae currently in use for mobile devices conducting two way communications are omnidirectional. The use of a directional antenna allows for increased effective coverage area without increasing power consumption. However, directional antennae must be oriented toward a wireless network access point in order for their benefits to be realized. This paper outlines a system for determining the optimal orientation of a directional antenna without the need for additional hardware. The response of the antenna is described by the use of a parameterized model corresponding to the sum of a set of cardioid functions. Signal strength is measured at several antenna orientations and is used by a Metropolis-Hastings search algorithm to estimate the model parameter values that best describe the antenna's response pattern. Using this model the antenna can be oriented to respond optimally to the wireless network access point's broadcast pattern.

Guttman, Rotem D.

2009-12-01

205

IDEF3 and IDEF4 automation system requirements document and system environment models  

NASA Technical Reports Server (NTRS)

The requirements specification is provided for the IDEF3 and IDEF4 tools that provide automated support for IDEF3 and IDEF4 modeling. The IDEF3 method is a scenario driven process flow description capture method intended to be used by domain experts to represent the knowledge about how a particular system or process works. The IDEF3 method provides modes to represent both (1) Process Flow Description to capture the relationships between actions within the context of a specific scenario, and (2) Object State Transition to capture the allowable transitions of an object in the domain. The IDEF4 method provides a method for capturing the (1) Class Submodel or object hierarchy, (2) Method Submodel or the procedures associated with each classes of objects, and (3) the Dispath Matching or the relationships between the objects and methods in the object oriented design. The requirements specified describe the capabilities that a fully functional IDEF3 or IDEF4 automated tool should support.

Blinn, Thomas M.

1989-01-01

206

Optical modeling of a-Si:H solar cells with rough interfaces: Effect of back contact and interface roughness  

NASA Astrophysics Data System (ADS)

An approach to study the optical behavior of hydrogenated amorphous silicon solar cells with rough interfaces using computer modeling is presented. In this approach the descriptive haze parameters of a light scattering interface are related to the root mean square roughness of the interface. Using this approach we investigated the effect of front window contact roughness and back contact material on the optical properties of a single junction a-Si:H superstrate solar cell. The simulation results for a-Si:H solar cells with SnO2:F as a front contact and ideal Ag, ZnO/Ag, and Al/Ag as a back contact are shown. For cells with an absorber layer thickness of 150-600 nm the simulations demonstrate that the gain in photogenerated current density due to the use of a textured superstrate is around 2.3 mA cm-2 in comparison to solar cells with flat interfaces. The effect of the front and back contact roughness on the external quantum efficiency (QE) of the solar cell for different parts of the light spectrum was determined. The choice of the back contact strongly influences the QE and the absorption in the nonactive layers for the wavelengths above 650 nm. A practical Ag back contact can be successfully simulated by introducing a thin buffer layer between the n-type a-Si:H and Ag back contact, which has optical properties similar to Al, indicating that the actual reflection at the n-type a-Si:H/Ag interface is smaller than what is expected from the respective bulk optical parameters. In comparison to the practical Ag contact the QE of the cell can be strongly improved by using a ZnO layer at the Ag back contact or an ideal Ag contact. The photogenerated current densities for a solar cell with a 450 nm thick intrinsic a-Si:H layer with ZnO/Ag and ideal Ag are 16.7 and 17.3 mA cm-2, respectively, compared to 14.4 mA cm-2 for the practical Ag back contact. The effect of increasing the roughness of the contact interfaces was investigated for both superstrate and substrate types of solar cells. Increasing the roughness of the carrier electrode, i.e., the rough electrode on which the silicon cell structure is deposited, up to 35 nm leads to a strong increase in the photogenerated current density; for higher values of the interface roughness the photogenerated current density tends to saturate.

Zeman, M.; van Swaaij, R. A. C. M. M.; Metselaar, J. W.; Schropp, R. E. I.

2000-12-01

207

Piloted Simulation of a Model-Predictive Automated Recovery System  

NASA Technical Reports Server (NTRS)

This presentation describes a model-predictive automatic recovery system for aircraft on the verge of a loss-of-control situation. The system determines when it must intervene to prevent an imminent accident, resulting from a poor approach. It estimates the altitude loss that would result from a go-around maneuver at the current flight condition. If the loss is projected to violate a minimum altitude threshold, the maneuver is automatically triggered. The system deactivates to allow landing once several criteria are met. Piloted flight simulator evaluation showed the system to provide effective envelope protection during extremely unsafe landing attempts. The results demonstrate how flight and propulsion control can be integrated to recover control of the vehicle automatically and prevent a potential catastrophe.

Liu, James (Yuan); Litt, Jonathan; Sowers, T. Shane; Owens, A. Karl; Guo, Ten-Huei

2014-01-01

208

INFORMATION INTERFACE TO THE SCHEDULING LEVEL OF A HARD REAL-TIME SYSTEM DESIGN MODEL  

Microsoft Academic Search

This report shows how a general information interface to thescheduling level of a design model of a hard real-time systemcan be derived. A scheduling approach independent interface isproposed by first determining what information is needed forfixed priority scheduling analysis and then comparing thisinformation with the information needed for static cyclicscheduling. The report also presents a way of handling interprocess relations

Jens Larsson

1997-01-01

209

Modeling the interface area aspect ratio of carbide grains in WCCo composites  

E-print Network

], and the fracture strength of tungsten carbide decreases as the length along the c-axis increases [3]. The aspectModeling the interface area aspect ratio of carbide grains in WC­Co composites Xiaokun Yuan a Keywords: Cemented carbide Electron backscattered diffraction Interface area aspect ratio Five parameter

Rohrer, Gregory S.

210

Inferring Intent in Eye-Based Interfaces: Tracing Eye Movements with Process Models  

E-print Network

Inferring Intent in Eye-Based Interfaces: Tracing Eye Movements with Process Models Dario D dario+@cs.cmu.edu ABSTRACT While current eye-based interfaces offer enormous potential for efficient human-computer interaction, they also manifest the difficulty of inferring intent from user eye

Salvucci, Dario D.

211

VRID: A Design Model and Methodology for Developing Virtual Reality Interfaces  

E-print Network

VRID: A Design Model and Methodology for Developing Virtual Reality Interfaces Vildan Tanriverdi 02155 {vildan | jacob} @eecs.tufts.edu ABSTRACT Compared to conventional interfaces, Virtual reality (VR Descriptors Realism-Virtual reality, Computing Methodologies General Terms Design, Theory Keywords: Virtual

Jacob, Robert J.K.

212

Uncued Brain-Computer Interfaces: a Variational Hidden Markov Model of Mental State Dynamics  

E-print Network

Uncued Brain-Computer Interfaces: a Variational Hidden Markov Model of Mental State Dynamics Cédric Brain- Computer Interfaces based on motor imagery. Our algorithm aims at ltering the continuous classier that the combination of our algorithm with a dynamic classier yields the best results. 1 Introduction Brain-Computer

Paris-Sud XI, Université de

213

Symbolic Conversation Modeling Used as Abstract Part of the User Interface  

Microsoft Academic Search

The art of conversation is a well-known interaction type between humans. Human-computer interfaces that follow this metaphor struggle with complex problems of speech understanding, speech generation and intelligent conversational behavior in general. This paper presents an approach that gives a simple, explicit symbolic model of conversation between human and computer to be used by interface designers as an abstract platform

Norbert Braun

2002-01-01

214

Accurate Modeling of Dispersive Material Interfaces in High-Order Finite-Difference Methods  

E-print Network

Accurate Modeling of Dispersive Material Interfaces in High-Order Finite-Difference Methods Roberto.sarris@utoronto.ca. Abstract-- When solving Maxwell's equations using high-order finite-difference methods in the presence not been explored before. Previously proposed methods to handle material interfaces in finite-difference

215

Automated Finite Element Modeling of Wing Structures for Shape Optimization  

NASA Technical Reports Server (NTRS)

The displacement formulation of the finite element method is the most general and most widely used technique for structural analysis of airplane configurations. Modem structural synthesis techniques based on the finite element method have reached a certain maturity in recent years, and large airplane structures can now be optimized with respect to sizing type design variables for many load cases subject to a rich variety of constraints including stress, buckling, frequency, stiffness and aeroelastic constraints (Refs. 1-3). These structural synthesis capabilities use gradient based nonlinear programming techniques to search for improved designs. For these techniques to be practical a major improvement was required in computational cost of finite element analyses (needed repeatedly in the optimization process). Thus, associated with the progress in structural optimization, a new perspective of structural analysis has emerged, namely, structural analysis specialized for design optimization application, or.what is known as "design oriented structural analysis" (Ref. 4). This discipline includes approximation concepts and methods for obtaining behavior sensitivity information (Ref. 1), all needed to make the optimization of large structural systems (modeled by thousands of degrees of freedom and thousands of design variables) practical and cost effective.

Harvey, Michael Stephen

1993-01-01

216

EST2uni: an open, parallel tool for automated EST analysis and database creation, with a data mining web interface and microarray expression data integration  

PubMed Central

Background Expressed sequence tag (EST) collections are composed of a high number of single-pass, redundant, partial sequences, which need to be processed, clustered, and annotated to remove low-quality and vector regions, eliminate redundancy and sequencing errors, and provide biologically relevant information. In order to provide a suitable way of performing the different steps in the analysis of the ESTs, flexible computation pipelines adapted to the local needs of specific EST projects have to be developed. Furthermore, EST collections must be stored in highly structured relational databases available to researchers through user-friendly interfaces which allow efficient and complex data mining, thus offering maximum capabilities for their full exploitation. Results We have created EST2uni, an integrated, highly-configurable EST analysis pipeline and data mining software package that automates the pre-processing, clustering, annotation, database creation, and data mining of EST collections. The pipeline uses standard EST analysis tools and the software has a modular design to facilitate the addition of new analytical methods and their configuration. Currently implemented analyses include functional and structural annotation, SNP and microsatellite discovery, integration of previously known genetic marker data and gene expression results, and assistance in cDNA microarray design. It can be run in parallel in a PC cluster in order to reduce the time necessary for the analysis. It also creates a web site linked to the database, showing collection statistics, with complex query capabilities and tools for data mining and retrieval. Conclusion The software package presented here provides an efficient and complete bioinformatics tool for the management of EST collections which is very easy to adapt to the local needs of different EST projects. The code is freely available under the GPL license and can be obtained at . This site also provides detailed instructions for installation and configuration of the software package. The code is under active development to incorporate new analyses, methods, and algorithms as they are released by the bioinformatics community. PMID:18179701

Forment, Javier; Gilabert, Francisco; Robles, Antonio; Conejero, Vicente; Nuez, Fernando; Blanca, Jose M

2008-01-01

217

Nonlinear phase-field model for electrode-electrolyte interface evolution  

NASA Astrophysics Data System (ADS)

A nonlinear phase-field model is proposed for modeling microstructure evolution during highly nonequilibrium processes. We consider electrochemical reactions at electrode-electrolyte interfaces leading to electroplating and electrode-electrolyte interface evolution. In contrast to all existing phase-field models, the rate of temporal phase-field evolution and thus the interface motion in the current model is considered nonlinear with respect to the thermodynamic driving force. It produces Butler-Volmer-type electrochemical kinetics for the dependence of interfacial velocity on the overpotential at the sharp-interface limit. At the low overpotential it recovers the conventional Allen-Cahn phase-field equation. This model is generally applicable to many other highly nonequilibrium processes where linear kinetics breaks down.

Liang, Linyun; Qi, Yue; Xue, Fei; Bhattacharya, Saswata; Harris, Stephen J.; Chen, Long-Qing

2012-11-01

218

Statistical modelling of networked human-automation performance using working memory capacity.  

PubMed

This study examines the challenging problem of modelling the interaction between individual attentional limitations and decision-making performance in networked human-automation system tasks. Analysis of real experimental data from a task involving networked supervision of multiple unmanned aerial vehicles by human participants shows that both task load and network message quality affect performance, but that these effects are modulated by individual differences in working memory (WM) capacity. These insights were used to assess three statistical approaches for modelling and making predictions with real experimental networked supervisory performance data: classical linear regression, non-parametric Gaussian processes and probabilistic Bayesian networks. It is shown that each of these approaches can help designers of networked human-automated systems cope with various uncertainties in order to accommodate future users by linking expected operating conditions and performance from real experimental data to observable cognitive traits like WM capacity. Practitioner Summary: Working memory (WM) capacity helps account for inter-individual variability in operator performance in networked unmanned aerial vehicle supervisory tasks. This is useful for reliable performance prediction near experimental conditions via linear models; robust statistical prediction beyond experimental conditions via Gaussian process models and probabilistic inference about unknown task conditions/WM capacities via Bayesian network models. PMID:24308716

Ahmed, Nisar; de Visser, Ewart; Shaw, Tyler; Mohamed-Ameen, Amira; Campbell, Mark; Parasuraman, Raja

2014-01-01

219

Interface-capturing lattice Boltzmann equation model for two-phase flows  

NASA Astrophysics Data System (ADS)

In this work, an interface-capturing lattice Boltzmann equation (LBE) model is proposed for two-phase flows. In the model, a Lax-Wendroff propagation scheme and a properly chosen equilibrium distribution function are employed. The Lax-Wendroff scheme is used to provide an adjustable Courant-Friedrichs-Lewy (CFL) number, and the equilibrium distribution is presented to remove the dependence of the relaxation time on the CFL number. As a result, the interface can be captured accurately by decreasing the CFL number. A theoretical expression is derived for the chemical potential gradient by solving the LBE directly for a two-phase system with a flat interface. The result shows that the gradient of the chemical potential is proportional to the square of the CFL number, which explains why the proposed model is able to capture the interface naturally with a small CFL number, and why large interface error exists in the standard LBE model. Numerical tests, including a one-dimensional flat interface problem, a two-dimensional circular droplet problem, and a three-dimensional spherical droplet problem, demonstrate that the proposed LBE model performs well and can capture a sharp interface with a suitable CFL number.

Lou, Qin; Guo, Zhaoli

2015-01-01

220

Using Model Checking to Debug Network Interface Firmware  

Microsoft Academic Search

Network interface rm ware is a piece of concurrent software that achieves high performance at the cost of software com- plexity. They contain subtle race conditions that make them dicult to debug using traditional debugging techniques. The problem is further compounded by the lack of debugging support on the devices. This is a serious problem because the device rm ware

Sanjeev Kumar; Kai Li

221

The enhanced Software Life Cyle Support Environment (ProSLCSE): Automation for enterprise and process modeling  

NASA Technical Reports Server (NTRS)

In this paper, we have introduced a comprehensive method for enterprise modeling that addresses the three important aspects of how an organization goes about its business. FirstEP includes infrastructure modeling, information modeling, and process modeling notations that are intended to be easy to learn and use. The notations stress the use of straightforward visual languages that are intuitive, syntactically simple, and semantically rich. ProSLCSE will be developed with automated tools and services to facilitate enterprise modeling and process enactment. In the spirit of FirstEP, ProSLCSE tools will also be seductively easy to use. Achieving fully managed, optimized software development and support processes will be long and arduous for most software organizations, and many serious problems will have to be solved along the way. ProSLCSE will provide the ability to document, communicate, and modify existing processes, which is the necessary first step.

Milligan, James R.; Dutton, James E.

1993-01-01

222

Intelligent sensor-model automated control of PMR-15 autoclave processing  

NASA Technical Reports Server (NTRS)

An intelligent sensor model system has been built and used for automated control of the PMR-15 cure process in the autoclave. The system uses frequency-dependent FM sensing (FDEMS), the Loos processing model, and the Air Force QPAL intelligent software shell. The Loos model is used to predict and optimize the cure process including the time-temperature dependence of the extent of reaction, flow, and part consolidation. The FDEMS sensing system in turn monitors, in situ, the removal of solvent, changes in the viscosity, reaction advancement and cure completion in the mold continuously throughout the processing cycle. The sensor information is compared with the optimum processing conditions from the model. The QPAL composite cure control system allows comparison of the sensor monitoring with the model predictions to be broken down into a series of discrete steps and provides a language for making decisions on what to do next regarding time-temperature and pressure.

Hart, S.; Kranbuehl, D.; Loos, A.; Hinds, B.; Koury, J.

1992-01-01

223

Effects of modeling errors on trajectory predictions in air traffic control automation  

NASA Technical Reports Server (NTRS)

Air traffic control automation synthesizes aircraft trajectories for the generation of advisories. Trajectory computation employs models of aircraft performances and weather conditions. In contrast, actual trajectories are flown in real aircraft under actual conditions. Since synthetic trajectories are used in landing scheduling and conflict probing, it is very important to understand the differences between computed trajectories and actual trajectories. This paper examines the effects of aircraft modeling errors on the accuracy of trajectory predictions in air traffic control automation. Three-dimensional point-mass aircraft equations of motion are assumed to be able to generate actual aircraft flight paths. Modeling errors are described as uncertain parameters or uncertain input functions. Pilot or autopilot feedback actions are expressed as equality constraints to satisfy control objectives. A typical trajectory is defined by a series of flight segments with different control objectives for each flight segment and conditions that define segment transitions. A constrained linearization approach is used to analyze trajectory differences caused by various modeling errors by developing a linear time varying system that describes the trajectory errors, with expressions to transfer the trajectory errors across moving segment transitions. A numerical example is presented for a complete commercial aircraft descent trajectory consisting of several flight segments.

Jackson, Michael R. C.; Zhao, Yiyuan; Slattery, Rhonda

1996-01-01

224

Sketch-based interfaces for modeling and users' needs: Redefining connections  

E-print Network

The goal of this paper is to reexamine assumptions about sketch-based interfaces for modeling in the context of designers' needs and practices. Research questions examine (a) the type of sketch support and (b) the timing ...

Elsen, Catherine

225

Design Through Manufacturing: The Solid Model-Finite Element Analysis Interface  

NASA Technical Reports Server (NTRS)

State-of-the-art computer aided design (CAD) presently affords engineers the opportunity to create solid models of machine parts reflecting every detail of the finished product. Ideally, in the aerospace industry, these models should fulfill two very important functions: (1) provide numerical. control information for automated manufacturing of precision parts, and (2) enable analysts to easily evaluate the stress levels (using finite element analysis - FEA) for all structurally significant parts used in aircraft and space vehicles. Today's state-of-the-art CAD programs perform function (1) very well, providing an excellent model for precision manufacturing. But they do not provide a straightforward and simple means of automating the translation from CAD to FEA models, especially for aircraft-type structures. Presently, the process of preparing CAD models for FEA consumes a great deal of the analyst's time.

Rubin, Carol

2002-01-01

226

An automated procedure for material parameter evaluation for viscoplastic constitutive models  

NASA Technical Reports Server (NTRS)

An automated procedure is presented for evaluating the material parameters in Walker's exponential viscoplastic constitutive model for metals at elevated temperature. Both physical and numerical approximations are utilized to compute the constants for Inconel 718 at 1100 F. When intermediate results are carefully scrutinized and engineering judgement applied, parameters may be computed which yield stress output histories that are in agreement with experimental results. A qualitative assessment of the theta-plot method for predicting the limiting value of stress is also presented. The procedure may also be used as a basis to develop evaluation schemes for other viscoplastic constitutive theories of this type.

Imbrie, P. K.; James, G. H.; Hill, P. S.; Allen, D. H.; Haisler, W. E.

1988-01-01

227

Modeling Speech Disfluency to Predict Conceptual Misalignment in Speech Survey Interfaces  

ERIC Educational Resources Information Center

Computer-based interviewing systems could use models of respondent disfluency behaviors to predict a need for clarification of terms in survey questions. This study compares simulated speech interfaces that use two such models--a generic model and a stereotyped model that distinguishes between the speech of younger and older speakers--to several…

Ehlen, Patrick; Schober, Michael F.; Conrad, Frederick G.

2007-01-01

228

Automated Optimization of Water–Water Interaction Parameters for a Coarse-Grained Model  

PubMed Central

We have developed an automated parameter optimization software framework (ParOpt) that implements the Nelder–Mead simplex algorithm and applied it to a coarse-grained polarizable water model. The model employs a tabulated, modified Morse potential with decoupled short- and long-range interactions incorporating four water molecules per interaction site. Polarizability is introduced by the addition of a harmonic angle term defined among three charged points within each bead. The target function for parameter optimization was based on the experimental density, surface tension, electric field permittivity, and diffusion coefficient. The model was validated by comparison of statistical quantities with experimental observation. We found very good performance of the optimization procedure and good agreement of the model with experiment. PMID:24460506

2015-01-01

229

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. PMID:23105914

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

2012-01-01

230

A conceptual model of the automated credibility assessment of the volunteered geographic information  

NASA Astrophysics Data System (ADS)

The use of Volunteered Geographic Information (VGI) in collecting, sharing and disseminating geospatially referenced information on the Web is increasingly common. The potentials of this localized and collective information have been seen to complement the maintenance process of authoritative mapping data sources and in realizing the development of Digital Earth. The main barrier to the use of this data in supporting this bottom up approach is the credibility (trust), completeness, accuracy, and quality of both the data input and outputs generated. The only feasible approach to assess these data is by relying on an automated process. This paper describes a conceptual model of indicators (parameters) and practical approaches to automated assess the credibility of information contributed through the VGI including map mashups, Geo Web and crowd - sourced based applications. There are two main components proposed to be assessed in the conceptual model - metadata and data. The metadata component comprises the indicator of the hosting (websites) and the sources of data / information. The data component comprises the indicators to assess absolute and relative data positioning, attribute, thematic, temporal and geometric correctness and consistency. This paper suggests approaches to assess the components. To assess the metadata component, automated text categorization using supervised machine learning is proposed. To assess the correctness and consistency in the data component, we suggest a matching validation approach using the current emerging technologies from Linked Data infrastructures and using third party reviews validation. This study contributes to the research domain that focuses on the credibility, trust and quality issues of data contributed by web citizen providers.

Idris, N. H.; Jackson, M. J.; Ishak, M. H. I.

2014-02-01

231

Automated reasoning system ITP  

SciTech Connect

This report describes a system designed to provide a portable environment for the study of automated reasoning. The system is built on the LMA automated reasoning subroutine package. This program is not part of LMA itself but illustrates the level of inference-based system that can be constructed from the LMA package of tools. It is a clause-based reasoning system supporting a wide variety of techniques which have proven valuable over the years in a long-running automated deduction research project. In addition, it is designed to present a convenient, interactive interface to its user.

Lusk, E.L.; Overbeek, R.A.

1984-04-01

232

An Analytical Model for Solute Segregation at Liquid Metal/Solid Substrate Interface  

NASA Astrophysics Data System (ADS)

In this paper, we present an analytical model for describing the equilibrium solute segregation at the interface between metallic liquid (an A-B solution, where A is solvent and B is solute) and a solid substrate (S) using approaches of thermodynamics and statistical mechanics. This analytical model suggests that the interfacial solute segregation is governed by the difference in interfacial energies between the pure B/S and pure A/S interfaces, the heat of mixing of the A-B solution and the difference in entropies of fusion between pure solute and solvent. The calculated solute segregations at the interface in the liquid Al-Ti/TiB2 and liquid Sn-Al/Al2O3 systems are in qualitative agreement with the experimental observations. It is demonstrated that the present analytical model can be used to predict the solute segregation at the liquid/substrate interface, at least qualitatively.

Men, Hua; Fan, Zhongyun

2014-11-01

233

Evaluation of state variable interface between the Activated Sludge Models and Anaerobic Digestion Model no 1.  

PubMed

For plant wide modelling of wastewater treatment, it is necessary to develop a suitable state variables interface for integrating state of the art models of ASM and ADM1. ADM1 currently describes such an interface, however, its suitability needs to be experimentally evaluated. In this study, we characterised activated sludge under aerobic and anaerobic conditions to obtain representative state variables for both models. ASM state variables of X(S), X(H) and X(I) (as obtained from aerobic tests) and ADM1 state variables of X(C) and X(I) (as obtained from anaerobic tests) were then correlated to assess the suitability of current interface. Based on the seven datasets of this study and seven datasets from literatures, it was found that in general ASM state variables were well correlated to the state variables of ADM1. The ADM1 state variable of X(C) could be correlated to the sum of state variables of X(S) and X(H), while X(I) in both the models showed direct correspondence. It was also observed that the degradation kinetics of X(C) under anaerobic condition could be better described by individual degradation kinetics of X(S) and X(H). Therefore, to establish a one to one correspondence between ASM and ADM1 state variables and better description of degradation kinetics in ADM1, replacing the composite variable of X(C) by the state variables of X(S) and X(H) is recommended. PMID:18413951

Yasui, H; Komatsu, K; Goel, R; Li, Y Y; Noike, T

2008-01-01

234

Automation, Control and Modeling of Compound Semiconductor Thin-Film Growth  

SciTech Connect

This report documents the results of a laboratory-directed research and development (LDRD) project on control and agile manufacturing in the critical metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) materials growth processes essential to high-speed microelectronics and optoelectronic components. This effort is founded on a modular and configurable process automation system that serves as a backbone allowing integration of process-specific models and sensors. We have developed and integrated MOCVD- and MBE-specific models in this system, and demonstrated the effectiveness of sensor-based feedback control in improving the accuracy and reproducibility of semiconductor heterostructures. In addition, within this framework we have constructed ''virtual reactor'' models for growth processes, with the goal of greatly shortening the epitaxial growth process development cycle.

Breiland, W.G.; Coltrin, M.E.; Drummond, T.J.; Horn, K.M.; Hou, H.Q.; Klem, J.F.; Tsao, J.Y.

1999-02-01

235

Pilot interaction with cockpit automation 2: An experimental study of pilots' model and awareness of the Flight Management System  

NASA Technical Reports Server (NTRS)

Technological developments have made it possible to automate more and more functions on the commercial aviation flight deck and in other dynamic high-consequence domains. This increase in the degrees of freedom in design has shifted questions away from narrow technological feasibility. Many concerned groups, from designers and operators to regulators and researchers, have begun to ask questions about how we should use the possibilities afforded by technology skillfully to support and expand human performance. In this article, we report on an experimental study that addressed these questions by examining pilot interaction with the current generation of flight deck automation. Previous results on pilot-automation interaction derived from pilot surveys, incident reports, and training observations have produced a corpus of features and contexts in which human-machine coordination is likely to break down (e.g., automation surprises). We used these data to design a simulated flight scenario that contained a variety of probes designed to reveal pilots' mental model of one major component of flight deck automation: the Flight Management System (FMS). The events within the scenario were also designed to probe pilots' ability to apply their knowledge and understanding in specific flight contexts and to examine their ability to track the status and behavior of the automated system (mode awareness). Although pilots were able to 'make the system work' in standard situations, the results reveal a variety of latent problems in pilot-FMS interaction that can affect pilot performance in nonnormal time critical situations.

Sarter, Nadine B.; Woods, David D.

1994-01-01

236

Aspects of automation mode confusion  

E-print Network

Complex systems such as commercial aircraft are difficult for operators to manage. Designers, intending to simplify the interface between the operator and the system, have introduced automation to assist the operator. In ...

Wheeler, Paul H. (Paul Harrison)

2007-01-01

237

Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter  

NASA Technical Reports Server (NTRS)

The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

Belknap, Shannon; Zhang, Michael

2013-01-01

238

A Wireless Sensor Network Communication Model for Automation of Electric Power Distribution  

Microsoft Academic Search

Automation of electric power distribution in a cost-efficient and reliable manner can be accomplished by complete automation of the load dispatch centers and substations on a large scale. For efficient load balancing among the feed lines, a continuous monitoring of parameters, such as voltage, current in the line, temperature, pressure, and oil level of the transformers is required. Currently, automation

M. Muthukumar; N. Sureshkumar

239

Developing Fire Behavior Fuel Models for the Wildland-Urban Interface in Anchorage, Alaska  

Microsoft Academic Search

Fire behavior modeling systems are playing an increasingly important role in identifying areas of the wildland- urban interface (WUI) that could support intense and fast-moving wildfires. The modeling systems also can be used to prioritize areas for fuels reduction treatments. We used forest inventory data to create custom fire behavior fuel models for the Anchorage, Alaska, WUI—an area strongly impacted

Daniel Cheyette; T. Scott Rupp; Sue Rodman

2008-01-01

240

The use of analytical models in human-computer interface design  

NASA Technical Reports Server (NTRS)

Recently, a large number of human-computer interface (HCI) researchers have investigated building analytical models of the user, which are often implemented as computer models. These models simulate the cognitive processes and task knowledge of the user in ways that allow a researcher or designer to estimate various aspects of an interface's usability, such as when user errors are likely to occur. This information can lead to design improvements. Analytical models can supplement design guidelines by providing designers rigorous ways of analyzing the information-processing requirements of specific tasks (i.e., task analysis). These models offer the potential of improving early designs and replacing some of the early phases of usability testing, thus reducing the cost of interface design. This paper describes some of the many analytical models that are currently being developed and evaluates the usefulness of analytical models for human-computer interface design. This paper will focus on computational, analytical models, such as the GOMS model, rather than less formal, verbal models, because the more exact predictions and task descriptions of computational models may be useful to designers. The paper also discusses some of the practical requirements for using analytical models in complex design organizations such as NASA.

Gugerty, Leo

1993-01-01

241

Aspects of self-organized criticality in a random driven interface model  

NASA Astrophysics Data System (ADS)

We introduce an external driven version of the solid-on-solid model of interface roughening in disordered media proposed by Leschhorn [H. Leschhorn, Physica A 195, 324 (1993)]. The properties of the avalanches triggered by the external driving field are studied numerically in the interface dimension D=1. It is found that just below the depinning transition the probability distributions of the characteristic quantities of the avalanches exhibit power-law behavior limited only by the system size. The exponents obtained for the probability distributions are discussed in the context of interface dynamics.

Jost, M.

1998-03-01

242

A computational comparison of the atomic models of the actomyosin interface.  

PubMed

Several atomic models of the actomyosin interface have been proposed based on the docking together of their component structures using electron microscopy and resonance energy-transfer measurements. Although these models are in approximate agreement in the location of the binding interfaces when myosin is tightly bound to actin, their relationships to molecular docking simulations based on computational free-energy calculations are investigated here. Both rigid-docking and flexible-docking conformational search strategies were used to identify free-energy minima at the interfaces between atomic models of myosin and actin. These results suggest that the docking model produced by resonance energy-transfer data is closer to a free-energy minimum at the interface than are the available atomic models based on electron microscopy. The conformational searches were performed using both scallop and chicken skeletal muscle myosins and identified similarly oriented actin-binding interfaces that serve to validate that these models are at the global minimum. These results indicate that the existing docking models are close to but not precisely at the lowest-energy initial contact site for strong binding between myosin and actin that should represent an initial contact between the two proteins; therefore, conformational changes are likely to be important during the transition to a strongly bound complex. PMID:12482134

Root, Douglas D

2002-01-01

243

Automation's Effect on Library Personnel.  

ERIC Educational Resources Information Center

Reports on survey studying the human-machine interface in Canadian university, public, and special libraries. Highlights include position category and educational background of 118 participants, participants' feelings toward automation, physical effects of automation, diffusion in decision making, interpersonal communication, future trends,…

Dakshinamurti, Ganga

1985-01-01

244

A multilayered sharp interface model of coupled freshwater and saltwater flow in coastal systems: model development and application  

USGS Publications Warehouse

The model allows for regional simulation of coastal groundwater conditions, including the effects of saltwater dynamics on the freshwater system. Vertically integrated freshwater and saltwater flow equations incorporating the interface boundary condition are solved within each aquifer. Leakage through confining layers is calculated by Darcy's law, accounting for density differences across the layer. The locations of the interface tip and toe, within grid blocks, are tracked by linearly extrapolating the position of the interface. The model has been verified using available analytical solutions and experimental results and applied to the Soquel-Aptos basin, Santa Cruz County, California. -from Author

Essaid, H.I.

1990-01-01

245

Modeling of soil–woven geotextile interface behavior from direct shear test results  

Microsoft Academic Search

Apart from other factors, the performance of geosynthetic reinforced soil structures depends also on the characteristics and behavior of the interface between soil and geosynthetic. Experiments were conducted in a direct shear test apparatus to study the shear force–displacement behavior at the soil–geotextile interface using two differently textured woven geotextiles. Analyzing the data so obtained a non-linear constitutive model has

Anubhav; P. K. Basudhar

2010-01-01

246

An Accuracy Assessment of Automated Photogrammetric Techniques for 3d Modeling of Complex Interiors  

NASA Astrophysics Data System (ADS)

This paper presents a comparison of automatic photogrammetric techniques to terrestrial laser scanning for 3D modelling of complex interior spaces. We try to evaluate the automated photogrammetric techniques not only in terms of their geometric quality compared to laser scanning but also in terms of cost in money, acquisition and computational time. To this purpose we chose as test site a modern building's stairway. APERO/MICMAC ( ©IGN )which is an Open Source photogrammetric software was used for the production of the 3D photogrammetric point cloud which was compared to the one acquired by a Leica Scanstation 2 laser scanner. After performing various qualitative and quantitative controls we present the advantages and disadvantages of each 3D modelling method applied in a complex interior of a modern building.

Georgantas, A.; Brédif, M.; Pierrot-Desseilligny, M.

2012-07-01

247

A predictive terrestrial clutter model for ground-to-ground automated target detection applications  

NASA Astrophysics Data System (ADS)

As computer processing hardware continues to advance there is increasing interest in the application of specialized Automated Target Detection (ATD) algorithms to process remotely sensed imagery for the purpose of object or target detection, in the military sensing domain. Historical approaches to modeling the performance of imaging systems for object identification have focused on the characteristics of the object to be identified, and have either not directly addressed the characteristics of the terrestrial clutter, or have focused on post-analysis scene complexity metrics as a way of addressing non-target areas of imagery. This research proposes a predictive model for ground-to-ground terrestrial clutter, using readily available satellite imagery, measures of site feature clustering, and scene infrared (IR) characteristics.

Feighny, Gene A.

248

CHANNEL MORPHOLOGY TOOL (CMT): A GIS-BASED AUTOMATED EXTRACTION MODEL FOR CHANNEL GEOMETRY  

SciTech Connect

This paper describes an automated Channel Morphology Tool (CMT) developed in ArcGIS 9.1 environment. The CMT creates cross-sections along a stream centerline and uses a digital elevation model (DEM) to create station points with elevations along each of the cross-sections. The generated cross-sections may then be exported into a hydraulic model. Along with the rapid cross-section generation the CMT also eliminates any cross-section overlaps that might occur due to the sinuosity of the channels using the Cross-section Overlap Correction Algorithm (COCoA). The CMT was tested by extracting cross-sections from a 5-m DEM for a 50-km channel length in Houston, Texas. The extracted cross-sections were compared directly with surveyed cross-sections in terms of the cross-section area. Results indicated that the CMT-generated cross-sections satisfactorily matched the surveyed data.

JUDI, DAVID [Los Alamos National Laboratory; KALYANAPU, ALFRED [Los Alamos National Laboratory; MCPHERSON, TIMOTHY [Los Alamos National Laboratory; BERSCHEID, ALAN [Los Alamos National Laboratory

2007-01-17

249

Analytic Element Modeling of Steady Interface Flow in Multilayer Aquifers Using AnAqSim.  

PubMed

This paper presents the analytic element modeling approach implemented in the software AnAqSim for simulating steady groundwater flow with a sharp fresh-salt interface in multilayer (three-dimensional) aquifer systems. Compared with numerical methods for variable-density interface modeling, this approach allows quick model construction and can yield useful guidance about the three-dimensional configuration of an interface even at a large scale. The approach employs subdomains and multiple layers as outlined by Fitts (2010) with the addition of discharge potentials for shallow interface flow (Strack 1989). The following simplifying assumptions are made: steady flow, a sharp interface between fresh- and salt water, static salt water, and no resistance to vertical flow and hydrostatic heads within each fresh water layer. A key component of this approach is a transition to a thin fixed minimum fresh water thickness mode when the fresh water thickness approaches zero. This allows the solution to converge and determine the steady interface position without a long transient simulation. The approach is checked against the widely used numerical codes SEAWAT and SWI/MODFLOW and a hypothetical application of the method to a coastal wellfield is presented. PMID:24942663

Fitts, Charles R; Godwin, Joshua; Feiner, Kathleen; McLane, Charles; Mullendore, Seth

2014-06-18

250

Efficient generation of low-energy folded states of a model protein. II. Automated histogram filtering  

NASA Astrophysics Data System (ADS)

A number of short, Monte Carlo simulated annealing runs are performed on a highly frustrated 69-mer off-lattice model protein, consisting of a chain of 69 beads that are either hydrophobic, hydrophilic, or neutral in nature, and which demonstrably folds into a six-stranded ?-barrel structure. We employ an iterative, consensus-based scheme to cluster the 725 nonbonded distances between the hydrophobic beads using, in tandem, Ward's method for hierarchical clustering and k-means partitional clustering. We also independently analyze the same data using computer-automated histogram filtering, a technology designed to cluster high-dimensional data, without the tedium and subjectivity required by our iterative implementation of the two classical clustering methods. The memberships of low-energy clusters obtained from both classical clustering and automated histogram filtering approaches are remarkably similar. Nonbonded distance constraints are derived from these clusters and from small sets of the original unclustered conformations obtained by simulated annealing. Employing a distance geometry approach, we efficiently generate novel, low-energy conformations from each set of distance constraints, including the apparent native structure, up to 40 times faster than by doing additional simulated annealing runs. Over 33 000 unique locally optimized conformations are generated in total, substantially augmenting the number of low-energy states located by the original simulated annealing runs.

Larrass, Stefan A.; Pegram, Laurel M.; Gordon, Heather L.; Rothstein, Stuart M.

2003-12-01

251

A methodology for model-based development and automated verification of software for aerospace systems  

NASA Astrophysics Data System (ADS)

Today's software for aerospace systems typically is very complex. This is due to the increasing number of features as well as the high demand for safety, reliability, and quality. This complexity also leads to significant higher software development costs. To handle the software complexity, a structured development process is necessary. Additionally, compliance with relevant standards for quality assurance is a mandatory concern. To assure high software quality, techniques for verification are necessary. Besides traditional techniques like testing, automated verification techniques like model checking become more popular. The latter examine the whole state space and, consequently, result in a full test coverage. Nevertheless, despite the obvious advantages, this technique is rarely yet used for the development of aerospace systems. In this paper, we propose a tool-supported methodology for the development and formal verification of safety-critical software in the aerospace domain. The methodology relies on the V-Model and defines a comprehensive work flow for model-based software development as well as automated verification in compliance to the European standard series ECSS-E-ST-40C. Furthermore, our methodology supports the generation and deployment of code. For tool support we use the tool SCADE Suite (Esterel Technology), an integrated design environment that covers all the requirements for our methodology. The SCADE Suite is well established in avionics and defense, rail transportation, energy and heavy equipment industries. For evaluation purposes, we apply our approach to an up-to-date case study of the TET-1 satellite bus. In particular, the attitude and orbit control software is considered. The behavioral models for the subsystem are developed, formally verified, and optimized.

Martin, L.; Schatalov, M.; Hagner, M.; Goltz, U.; Maibaum, O.

252

Toward automated model building from video in computer-assisted diagnoses in colonoscopy  

NASA Astrophysics Data System (ADS)

A 3D colon model is an essential component of a computer-aided diagnosis (CAD) system in colonoscopy to assist surgeons in visualization, and surgical planning and training. This research is thus aimed at developing the ability to construct a 3D colon model from endoscopic videos (or images). This paper summarizes our ongoing research in automated model building in colonoscopy. We have developed the mathematical formulations and algorithms for modeling static, localized 3D anatomic structures within a colon that can be rendered from multiple novel view points for close scrutiny and precise dimensioning. This ability is useful for the scenario when a surgeon notices some abnormal tissue growth and wants a close inspection and precise dimensioning. Our modeling system uses only video images and follows a well-established computer-vision paradigm for image-based modeling. We extract prominent features from images and establish their correspondences across multiple images by continuous tracking and discrete matching. We then use these feature correspondences to infer the camera's movement. The camera motion parameters allow us to rectify images into a standard stereo configuration and calculate pixel movements (disparity) in these images. The inferred disparity is then used to recover 3D surface depth. The inferred 3D depth, together with texture information recorded in images, allow us to construct a 3D model with both structure and appearance information that can be rendered from multiple novel view points.

Koppel, Dan; Chen, Chao-I.; Wang, Yuan-Fang; Lee, Hua; Gu, Jia; Poirson, Allen; Wolters, Rolf

2007-03-01

253

Interface characteristics of carbon nanotube reinforced polymer composites using an advanced pull-out model  

NASA Astrophysics Data System (ADS)

An advanced pull-out model is presented to obtain the interface characteristics of carbon nanotube (CNT) in polymer composite. Since, a part of the CNT/matrix interface near the crack tip is considered to be debonded, there must present adhesive van der Waals (vdW) interaction which is generally presented in the form of Lennard-Jones potential. A separate analytical model is also proposed to account normal cohesive stress caused by the vdW interaction along the debonded CNT/polymer interface. Analytical solutions for axial and interfacial shear stress components are derived in closed form. The analytical result shows that contribution of vdW interaction is very significant and also enhances stress transfer potential of CNT in polymer composite. Parametric studies are also conducted to obtain the influence of key composite factors on bonded and debonded interface. The result reveals that the parameter dependency of interfacial stress transfer is significantly higher in the perfectly bonded interface than that of the debonded interface.

Ahmed, Khondaker Sakil; Keng, Ang Kok

2014-02-01

254

Dynamic Distribution and Layouting of Model-Based User Interfaces in Smart Environments  

NASA Astrophysics Data System (ADS)

The developments in computer technology in the last decade change the ways of computer utilization. The emerging smart environments make it possible to build ubiquitous applications that assist users during their everyday life, at any time, in any context. But the variety of contexts-of-use (user, platform and environment) makes the development of such ubiquitous applications for smart environments and especially its user interfaces a challenging and time-consuming task. We propose a model-based approach, which allows adapting the user interface at runtime to numerous (also unknown) contexts-of-use. Based on a user interface modelling language, defining the fundamentals and constraints of the user interface, a runtime architecture exploits the description to adapt the user interface to the current context-of-use. The architecture provides automatic distribution and layout algorithms for adapting the applications also to contexts unforeseen at design time. Designers do not specify predefined adaptations for each specific situation, but adaptation constraints and guidelines. Furthermore, users are provided with a meta user interface to influence the adaptations according to their needs. A smart home energy management system serves as running example to illustrate the approach.

Roscher, Dirk; Lehmann, Grzegorz; Schwartze, Veit; Blumendorf, Marco; Albayrak, Sahin

255

Fullerene film on metal surface: Diffusion of metal atoms and interface model  

SciTech Connect

We try to understand the fact that fullerene film behaves as n-type semiconductor in electronic devices and establish a model describing the energy level alignment at fullerene/metal interfaces. The C{sub 60}/Ag(100) system was taken as a prototype and studied with photoemission measurements. The photoemission spectra revealed that the Ag atoms of the substrate diffused far into C{sub 60} film and donated electrons to the molecules. So the C{sub 60} film became n-type semiconductor with the Ag atoms acting as dopants. The C{sub 60}/Ag(100) interface should be understood as two sub-interfaces on both sides of the molecular layer directly contacting with the substrate. One sub-interface is Fermi level alignment, and the other is vacuum level alignment.

Li, Wen-jie; Li, Hai-Yang; Li, Hong-Nian, E-mail: Phylihn@mail.zju.edu.cn [Department of Physics, Zhejiang University, Hangzhou 310027 (China); Wang, Peng [Department of Applied Physics, Shandong University of Science and Technology, Qingdao 266590 (China); Wang, Xiao-Xiong [College of Science, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Jia-Ou; Wu, Rui; Qian, Hai-Jie; Ibrahim, Kurash [Laboratory of Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

2014-05-12

256

Rethinking Design Process: Using 3D Digital Models as an Interface in Collaborative Session  

ERIC Educational Resources Information Center

This paper describes a pilot study for an alternative design process by integrating a designer-user collaborative session with digital models. The collaborative session took place in a 3D AutoCAD class for a real world project. The 3D models served as an interface for designer-user collaboration during the design process. Students not only learned…

Ding, Suining

2008-01-01

257

Dosimetry Modeling for Predicting Radiolytic Production at the Spent Fuel - Water Interface  

SciTech Connect

Modeling of the alpha, beta, and gamma dose from spent fuel as a function of particle size and fuel to water ratio was examined. These doses will be combined with modeling of G values and interactions to determine the concentration of various species formed at the fuel water interface and their affect on dissolution rates.

Miller, William H.; Kline, Amanda J.; Hanson, Brady D.

2006-04-30

258

Modeling reach for use in user interface design Aaron P. Toney, Bruce H. Thomas  

E-print Network

anthropometric models. Designers of everyday objects like buildings, cars, and appliances regularly use anthropometric models to tailor their designs to their intended user population. Currently, creating user on the anthropometric tools currently used by other design communities to create user interfaces that are dynamically

Thomas, Bruce

259

A propagating interface model strategy for global trajectory planning among moving obstacles  

Microsoft Academic Search

A global trajectory planning method which employs a collision-trend index and a propagating interface model to perform mobile robot navigation is presented in this paper. To simplify the mathematical representation and geometrical approximation, all the objects in the workspace are modeled as ellipses. Using a series of geometrical transformations between the ellipses, which represent the mobile robot and obstacles, the

Kao-Shing Hwang; Ming-Yi Ju

2002-01-01

260

MATHEMATICAL MODELING OF CHANNEL POROUS LAYER INTERFACES IN PEM FUEL CELLS  

E-print Network

MATHEMATICAL MODELING OF CHANNEL ­ POROUS LAYER INTERFACES IN PEM FUEL CELLS M. EHRHARDT, J, Germany ABSTRACT In proton exchange membrane (PEM) fuel cells, the transport of the fuel to the active diffusion layers. In order to improve existing mathematical and numerical models of PEM fuel cells, a deeper

Ehrhardt, Matthias

261

Drawing interfaces : building geometric models with hand-drawn sketches  

E-print Network

Architects work on drawings and models, not buildings. Today, in many architectural practices, drawings and models are produced in digital format using Computer-aided Design (CAD) tools. Unquestionably, digital media have ...

Branda, Ewan E. (Ewan Edward), 1964-

1998-01-01

262

Automated Geospatial Watershed Assessment  

EPA Science Inventory

The Automated Geospatial Watershed Assessment (AGWA) tool is a Geographic Information Systems (GIS) interface jointly developed by the U.S. Environmental Protection Agency, the U.S. Department of Agriculture (USDA) Agricultural Research Service, and the University of Arizona to a...

263

[The ambulatory-stationary interface in medical health care: problems, model of explanation, and possible solutions].  

PubMed

Due to the strict separation between ambulatory and hospital care in Germany, there are problems in terms of communication between the different health-care sectors which can lead to discontinuity in care or to treatment errors. There are only very few studies in Germany so far dealing with the ambulatory-stationary interface from the clinicians' point of view. The quality of collaboration at the interface between ambulatory and hospital care is judged to be deficient by hospital physicians. Deficits in terms of communication and organization are common reasons for this problem which is also demonstrated in other foreign studies. Against the background of the model of interaction in the ambulatory-stationary interface, several solutions for a better communication between physicians in ambulatory and stationary sector are discussed: gate keeper model, standardized patient hospitalization report, electronic health cards or other strategies like the Danish model (general practioners as advisors and coordinators in hospitals) or transsectoral quality circles. PMID:17992483

Ommen, Oliver; Ullrich, Britta; Janssen, Christian; Pfaff, Holger

2007-11-15

264

Random Sample Consensus: A Paradigm for Model Fitting with Applicationsto Image Analysis and Automated Cartography  

Microsoft Academic Search

A new paradigm, Random Sample Consensus (RANSAC), for fitting a model\\u000d\\u000a\\u0009to experimental data is introduced. RANSAC is capable of interpreting\\/smoothing\\u000d\\u000a\\u0009data containing a significant percentage of gross errors, and is\\u000d\\u000a\\u0009thus ideally suited for applications in automated image analysis\\u000d\\u000a\\u0009where interpretation is based on the data provided by error-prone\\u000d\\u000a\\u0009feature detectors. A major portion of this paper describes the

Martin A. Fischler; Robert C. Bolles

1981-01-01

265

IEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 11, NO. 4, AUGUST 2006 381 Automated Onboard Modeling of Cartridge  

E-print Network

was presented in part at the 2005 IEEE/ASME Conference on Advanced Intelligent Mechatronics (AIM'05). S. LiuIEEE/ASME TRANSACTIONS ON MECHATRONICS, VOL. 11, NO. 4, AUGUST 2006 381 Automated Onboard Modeling is based on the pressure dynamics of the hydraulic cylinder with the consideration of effects of some un

Yao, Bin

266

RI: Small: Reasoning about Containers: Cognitive and Automated Models Ernest Davis and Gary Marcus, New York University  

E-print Network

1 RI: Small: Reasoning about Containers: Cognitive and Automated Models Ernest Davis and Gary notoriously poor at common sense reasoning, such as reasoning about every day physical objects. In computers of the system at a sequence of discrete time points. There is good reason, however, to think that human beings

Davis, Ernest

267

Smart Frameworks and Self-Describing Models: Model Metadata for Automated Coupling of Hydrologic Process Components (Invited)  

NASA Astrophysics Data System (ADS)

Model coupling frameworks like CSDMS (Community Surface Dynamics Modeling System) and ESMF (Earth System Modeling Framework) have developed mechanisms that allow heterogeneous sets of process models to be assembled in a plug-and-play manner to create composite "system models". These mechanisms facilitate code reuse, but must simultaneously satisfy many different design criteria. They must be able to mediate or compensate for differences between the process models, such as their different programming languages, computational grids, time-stepping schemes, variable names and variable units. However, they must achieve this interoperability in a way that: (1) is noninvasive, requiring only relatively small and isolated changes to the original source code, (2) does not significantly reduce performance, (3) is not time-consuming or confusing for a model developer to implement, (4) can very easily be updated to accommodate new versions of a given process model and (5) does not shift the burden of providing model interoperability to the model developers, e.g. by requiring them to provide their output in specific forms that meet the input requirements of other models. In tackling these design challenges, model framework developers have learned that the best solution is to provide each model with a simple, standardized interface, i.e. a set of standardized functions that make the model: (1) fully-controllable by a caller (e.g. a model framework) and (2) self-describing. Model control functions are separate functions that allow a caller to initialize the model, advance the model's state variables in time and finalize the model. Model description functions allow a caller to retrieve detailed information on the model's input and output variables, its computational grid and its timestepping scheme. If the caller is a modeling framework, it can compare the answers to these queries with similar answers from other process models in a collection and then automatically call framework service components as necessary to mediate the differences between the coupled models. This talk will first review two key products of the CSDMS project, namely a standardized model interface called the Basic Model Interface (BMI) and the CSDMS Standard Names. The standard names are used in conjunction with BMI to provide a semantic matching mechanism that allows output variables from one process model to be reliably used as input variables to other process models in a collection. They include not just a standardized naming scheme for model variables, but also a standardized set of terms for describing the attributes and assumptions of a given model. To illustrate the power of standardized model interfaces and metadata, a smart, light-weight modeling framework written in Python will be introduced that can automatically (without user intervention) couple a set of BMI-enabled hydrologic process components together to create a spatial hydrologic model. The same mechanisms could also be used to provide seamless integration (import/export) of data and models.

Peckham, S. D.

2013-12-01

268

Progress and challenges in the automated construction of Markov state models for full protein systems  

NASA Astrophysics Data System (ADS)

Markov state models (MSMs) are a powerful tool for modeling both the thermodynamics and kinetics of molecular systems. In addition, they provide a rigorous means to combine information from multiple sources into a single model and to direct future simulations/experiments to minimize uncertainties in the model. However, constructing MSMs is challenging because doing so requires decomposing the extremely high dimensional and rugged free energy landscape of a molecular system into long-lived states, also called metastable states. Thus, their application has generally required significant chemical intuition and hand-tuning. To address this limitation we have developed a toolkit for automating the construction of MSMs called MSMBUILDER (available at https://simtk.org/home/msmbuilder). In this work we demonstrate the application of MSMBUILDER to the villin headpiece (HP-35 NleNle), one of the smallest and fastest folding proteins. We show that the resulting MSM captures both the thermodynamics and kinetics of the original molecular dynamics of the system. As a first step toward experimental validation of our methodology we show that our model provides accurate structure prediction and that the longest timescale events correspond to folding.

Bowman, Gregory R.; Beauchamp, Kyle A.; Boxer, George; Pande, Vijay S.

2009-09-01

269

Tape-Drop Transient Model for In-Situ Automated Tape Placement of Thermoplastic Composites  

NASA Technical Reports Server (NTRS)

Composite parts of nonuniform thickness can be fabricated by in-situ automated tape placement (ATP) if the tape can be started and stopped at interior points of the part instead of always at its edges. This technique is termed start/stop-on-the-part, or, alternatively, tape-add/tape-drop. The resulting thermal transients need to be managed in order to achieve net shape and maintain uniform interlaminar weld strength and crystallinity. Starting-on-the-part has been treated previously. This paper continues the study with a thermal analysis of stopping-on-the-part. The thermal source is switched off when the trailing end of the tape enters the nip region of the laydown/consolidation head. The thermal transient is determined by a Fourier-Laplace transform solution of the two-dimensional, time-dependent thermal transport equation. This solution requires that the Peclet number Pe (the dimensionless ratio of inertial to diffusive heat transport) be independent of time and much greater than 1. Plotted isotherms show that the trailing tape-end cools more rapidly than the downstream portions of tape. This cooling can weaken the bond near the tape end; however the length of the affected region is found to be less than 2 mm. To achieve net shape, the consolidation head must continue to move after cut-off until the temperature on the weld interface decreases to the glass transition temperature. The time and elapsed distance for this condition to occur are computed for the Langley ATP robot applying PEEK/carbon fiber composite tape and for two upgrades in robot performance. The elapsed distance after cut-off ranges from about 1 mm for the present robot to about 1 cm for the second upgrade.

Costen, Robert C.; Marchello, Joseph M.

1998-01-01

270

Distribution automation applications of fiber optics  

NASA Technical Reports Server (NTRS)

Motivations for interest and research in distribution automation are discussed. The communication requirements of distribution automation are examined and shown to exceed the capabilities of power line carrier, radio, and telephone systems. A fiber optic based communication system is described that is co-located with the distribution system and that could satisfy the data rate and reliability requirements. A cost comparison shows that it could be constructed at a cost that is similar to that of a power line carrier system. The requirements for fiber optic sensors for distribution automation are discussed. The design of a data link suitable for optically-powered electronic sensing is presented. Empirical results are given. A modeling technique that was used to understand the reflections of guided light from a variety of surfaces is described. An optical position-indicator design is discussed. Systems aspects of distribution automation are discussed, in particular, the lack of interface, communications, and data standards. The economics of distribution automation are examined.

Kirkham, Harold; Johnston, A.; Friend, H.

1989-01-01

271

DAISY, an RER Model Based Interface for RDB to ILP  

Microsoft Academic Search

\\u000a In this paper, we propose an RER (Refined-Entity-Relationship) model, an extension of the ER (Entity-Relationship) model,\\u000a which has an added feature of each entity attribute as well as each relationship being one indicating whether it can be derived\\u000a from others or not. The purpose of an RER model is to apply ILP (Inductive Logic Programming), one of the most expressive

Keiko Shimazu; Atsuhito Momma; Koichi Furukawa

2003-01-01

272

A graphical user interface for numerical modeling of acclimation responses of vegetation to climate change  

NASA Astrophysics Data System (ADS)

Ecophysiological models that vertically resolve vegetation canopy states are becoming a powerful tool for studying the exchange of mass, energy, and momentum between the land surface and the atmosphere. A mechanistic multilayer canopy-soil-root system model (MLCan) developed by Drewry et al. (2010a) has been used to capture the emergent vegetation responses to elevated atmospheric CO2 for both C3 and C4 plants under various climate conditions. However, processing input data and setting up such a model can be time-consuming and error-prone. In this paper, a graphical user interface that has been developed for MLCan is presented. The design of this interface aims to provide visualization capabilities and interactive support for processing input meteorological forcing data and vegetation parameter values to facilitate the use of this model. In addition, the interface also provides graphical tools for analyzing the forcing data and simulated numerical results. The model and its interface are both written in the MATLAB programming language. Finally, an application of this model package for capturing the ecohydrological responses of three bioenergy crops (maize, miscanthus, and switchgrass) to local environmental drivers at two different sites in the Midwestern United States is presented.

Le, Phong V. V.; Kumar, Praveen; Drewry, Darren T.; Quijano, Juan C.

2012-12-01

273

Scale-coupling and interface-pinning effects in the phase-field-crystal model  

NASA Astrophysics Data System (ADS)

Effects of scale coupling between mesoscopic slowly varying envelopes of liquid-solid profile and the underlying microscopic crystalline structure are studied in the phase-field-crystal (PFC) model. Such scale coupling leads to nonadiabatic corrections to the PFC amplitude equations, the effect of which increases strongly with decreasing system temperature below the melting point. This nonadiabatic amplitude representation is further coarse-grained for the derivation of effective sharp-interface equations of motion in the limit of small but finite interface thickness. We identify a generalized form of the Gibbs-Thomson relation with the incorporation of coupling and pinning effects of the crystalline lattice structure. This generalized interface equation can be reduced to the form of a driven sine-Gordon equation with Kardar-Parisi-Zhang (KPZ) nonlinearity, and can be combined with two other dynamic equations in the sharp interface limit obeying the conservation condition of atomic number density in a liquid-solid system. A sample application to the study of crystal layer growth is given, and the corresponding analytic solutions showing lattice pinning and depinning effects and two distinct modes of continuous vs nucleated growth are presented. We also identify the universal scaling behaviors governing the properties of pinning strength, surface tension, interface kinetic coefficient, and activation energy of atomic layer growth, which accommodate all range of liquid-solid interface thicknesses and different material elastic moduli.

Huang, Zhi-Feng

2013-01-01

274

Scale-coupling and interface-pinning effects in the phase-field-crystal model.  

PubMed

Effects of scale coupling between mesoscopic slowly varying envelopes of liquid-solid profile and the underlying microscopic crystalline structure are studied in the phase-field-crystal (PFC) model. Such scale coupling leads to nonadiabatic corrections to the PFC amplitude equations, the effect of which increases strongly with decreasing system temperature below the melting point. This nonadiabatic amplitude representation is further coarse-grained for the derivation of effective sharp-interface equations of motion in the limit of small but finite interface thickness. We identify a generalized form of the Gibbs-Thomson relation with the incorporation of coupling and pinning effects of the crystalline lattice structure. This generalized interface equation can be reduced to the form of a driven sine-Gordon equation with Kardar-Parisi-Zhang (KPZ) nonlinearity, and can be combined with two other dynamic equations in the sharp interface limit obeying the conservation condition of atomic number density in a liquid-solid system. A sample application to the study of crystal layer growth is given, and the corresponding analytic solutions showing lattice pinning and depinning effects and two distinct modes of continuous vs nucleated growth are presented. We also identify the universal scaling behaviors governing the properties of pinning strength, surface tension, interface kinetic coefficient, and activation energy of atomic layer growth, which accommodate all range of liquid-solid interface thicknesses and different material elastic moduli. PMID:23410338

Huang, Zhi-Feng

2013-01-01

275

SENSPECTRA : an elastic, strain-aware physical modeling interface  

E-print Network

Senspectra is a computationally augmented physical modeling toolkit designed for sensing and visualization of structural strain. The system functions as a distributed sensor network consisting of nodes, embedded with ...

Leclerc, Vincent, S.M. Massachusetts Institute of Technology

2006-01-01

276

Atomistic Cohesive Zone Models for Interface Decohesion in Metals  

NASA Technical Reports Server (NTRS)

Using a statistical mechanics approach, a cohesive-zone law in the form of a traction-displacement constitutive relationship characterizing the load transfer across the plane of a growing edge crack is extracted from atomistic simulations for use within a continuum finite element model. The methodology for the atomistic derivation of a cohesive-zone law is presented. This procedure can be implemented to build cohesive-zone finite element models for simulating fracture in nanocrystalline or ultrafine grained materials.

Yamakov, Vesselin I.; Saether, Erik; Glaessgen, Edward H.

2009-01-01

277

Automated geography  

SciTech Connect

Analytical methods and computer technology for spatial analysis have advanced rapidly. Geographers can now consider a general form of automated geography which integrates all of the new techniques into an analytical whole. Computer cartography, computer graphics, digital remote sensing, geographic information systems, spatial statistics, and quantitative spatial modeling can be combined eclectically with traditional manual techniques to address geographic problems that are too large and complex for manual treatment alone. Small systems are widely available to facilitate small, less complex problems. Automation can assist in all forms of geography - scientific and humanistic, nomothetic and idiographic, basic and applied - but its adoption is likely to be highest among applied scientists. The immediate challenge is to prepare for a major shift toward computer instruction and automated geography in the late 1980s. Long term effects will include improved contributions by geographers to national and international policy analyses, a greater emphasis on team-work and sharing, stronger ties with other disciplines, and a generally more viable discipline. 27 references.

Dobson, J.E.

1983-05-01

278

Automated generation of high-quality training data for appearance-based object models  

NASA Astrophysics Data System (ADS)

Methods for automated person detection and person tracking are essential core components in modern security and surveillance systems. Most state-of-the-art person detectors follow a statistical approach, where prototypical appearances of persons are learned from training samples with known class labels. Selecting appropriate learning samples has a significant impact on the quality of the generated person detectors. For example, training a classifier on a rigid body model using training samples with strong pose variations is in general not effective, irrespective of the classifiers capabilities. Generation of high-quality training data is, apart from performance issues, a very time consuming process, comprising a significant amount of manual work. Furthermore, due to inevitable limitations of freely available training data, corresponding classifiers are not always transferable to a given sensor and are only applicable in a well-defined narrow variety of scenes and camera setups. Semi-supervised learning methods are a commonly used alternative to supervised training, in general requiring only few labeled samples. However, as a drawback semi-supervised methods always include a generative component, which is known to be difficult to learn. Therefore, automated processes for generating training data sets for supervised methods are needed. Such approaches could either help to better adjust classifiers to respective hardware, or serve as a complement to existing data sets. Towards this end, this paper provides some insights into the quality requirements of automatically generated training data for supervised learning methods. Assuming a static camera, labels are generated based on motion detection by background subtraction with respect to weak constraints on the enclosing bounding box of the motion blobs. Since this labeling method consists of standard components, we illustrate the effectiveness by adapting a person detector to cameras of a sensor network. While varying the training data and keeping the detection framework identical, we derive statements about the sample quality.

Becker, Stefan; Voelker, Arno; Kieritz, Hilke; Hübner, Wolfgang; Arens, Michael

2013-11-01

279

DisplayObjects: Prototyping Functional Physical Interfaces on 3D Styrofoam, Paper or Cardboard Models  

Microsoft Academic Search

This paper introduces DisplayObjects, a rapid prototyping workbench that allows functional interfaces to be projected onto real 3D physical prototypes. DisplayObjects uses a Vicon motion capture system to track the location of physical models. 3D software renditions of the 3D physical model are then texture-mapped with interactive behavior and projected back onto the physical model to allow real- time interactions

Eric Akaoka; Tim Ginn; Roel Vertegaal

2010-01-01

280

Diffuse interface models of locally inextensible vesicles in a viscous fluid.  

PubMed

We present a new diffuse interface model for the dynamics of inextensible vesicles in a viscous fluid with inertial forces. A new feature of this work is the implementation of the local inextensibility condition in the diffuse interface context. Local inextensibility is enforced by using a local Lagrange multiplier, which provides the necessary tension force at the interface. We introduce a new equation for the local Lagrange multiplier whose solution essentially provides a harmonic extension of the multiplier off the interface while maintaining the local inextensibility constraint near the interface. We also develop a local relaxation scheme that dynamically corrects local stretching/compression errors thereby preventing their accumulation. Asymptotic analysis is presented that shows that our new system converges to a relaxed version of the inextensible sharp interface model. This is also verified numerically. To solve the equations, we use an adaptive finite element method with implicit coupling between the Navier-Stokes and the diffuse interface inextensibility equations. Numerical simulations of a single vesicle in a shear flow at different Reynolds numbers demonstrate that errors in enforcing local inextensibility may accumulate and lead to large differences in the dynamics in the tumbling regime and smaller differences in the inclination angle of vesicles in the tank-treading regime. The local relaxation algorithm is shown to prevent the accumulation of stretching and compression errors very effectively. Simulations of two vesicles in an extensional flow show that local inextensibility plays an important role when vesicles are in close proximity by inhibiting fluid drainage in the near contact region. PMID:25246712

Aland, Sebastian; Egerer, Sabine; Lowengrub, John; Voigt, Axel

2014-11-15

281

Diffuse interface models of locally inextensible vesicles in a viscous fluid  

NASA Astrophysics Data System (ADS)

We present a new diffuse interface model for the dynamics of inextensible vesicles in a viscous fluid with inertial forces. A new feature of this work is the implementation of the local inextensibility condition in the diffuse interface context. Local inextensibility is enforced by using a local Lagrange multiplier, which provides the necessary tension force at the interface. We introduce a new equation for the local Lagrange multiplier whose solution essentially provides a harmonic extension of the multiplier off the interface while maintaining the local inextensibility constraint near the interface. We also develop a local relaxation scheme that dynamically corrects local stretching/compression errors thereby preventing their accumulation. Asymptotic analysis is presented that shows that our new system converges to a relaxed version of the inextensible sharp interface model. This is also verified numerically. To solve the equations, we use an adaptive finite element method with implicit coupling between the Navier-Stokes and the diffuse interface inextensibility equations. Numerical simulations of a single vesicle in a shear flow at different Reynolds numbers demonstrate that errors in enforcing local inextensibility may accumulate and lead to large differences in the dynamics in the tumbling regime and smaller differences in the inclination angle of vesicles in the tank-treading regime. The local relaxation algorithm is shown to prevent the accumulation of stretching and compression errors very effectively. Simulations of two vesicles in an extensional flow show that local inextensibility plays an important role when vesicles are in close proximity by inhibiting fluid drainage in the near contact region.

Aland, Sebastian; Egerer, Sabine; Lowengrub, John; Voigt, Axel

2014-11-01

282

Interface modeling to predict well casing damage for big hill strategic petroleum reserve.  

SciTech Connect

Oil leaks were found in well casings of Caverns 105 and 109 at the Big Hill Strategic Petroleum Reserve site. According to the field observations, two instances of casing damage occurred at the depth of the interface between the caprock and top of salt. This damage could be caused by interface movement induced by cavern volume closure due to salt creep. A three dimensional finite element model, which allows each cavern to be configured individually, was constructed to investigate shear and vertical displacements across each interface. The model contains interfaces between each lithology and a shear zone to examine the interface behavior in a realistic manner. This analysis results indicate that the casings of Caverns 105 and 109 failed by shear stress that exceeded shear strength due to the horizontal movement of the top of salt relative to the caprock, and tensile stress due to the downward movement of the top of salt from the caprock, respectively. The casings of Caverns 101, 110, 111 and 114, located at the far ends of the field, are predicted to be failed by shear stress in the near future. The casings of inmost Caverns 107 and 108 are predicted to be failed by tensile stress in the near future.

Ehgartner, Brian L.; Park, Byoung Yoon

2012-02-01

283

Context based mixture model for cell phase identification in automated fluorescence microscopy  

Microsoft Academic Search

Background: Automated identification of cell cycle phases of individual live cells in a large population captured via automated fluorescence microscopy technique is important for cancer drug discovery and cell cycle studies. Time-lapse fluorescence microscopy images provide an important method to study the cell cycle process under different conditions of perturbation. Existing methods are limited in dealing with such time-lapse data

Meng Wang; Xiaobo Zhou; Randy W. King; Stephen T. C. Wong

2007-01-01

284

Development and Implementation of an Extensible Interface-Based Spatiotemporal Geoprocessing and Modeling Toolbox  

NASA Astrophysics Data System (ADS)

This poster presents an object oriented and interface-based spatiotemporal data processing and modeling toolbox that can be extended by third parties to include complete suites of new tools through the implementation of simple interfaces. The resulting software implementation includes both a toolbox and workflow designer or "model builder" constructed using the underlying open source DotSpatial library and MapWindow desktop GIS. The unique contribution of this research and software development activity is in the creation and use of an extensibility architecture for both specific tools (through a so-called "ITool" interface) and batches of tools (through a so-called "IToolProvider" interface.) This concept is introduced to allow for seamless integration of geoprocessing tools from various sources (e.g. distinct libraries of spatiotemporal processing code) - including online sources - within a single user environment. In this way, the IToolProvider interface allows developers to wrap large existing collections of data analysis code without having to re-write it for interoperability. Additionally, developers do not need to design the user interfaces for loading, displaying or interacting with their specific tools, but rather can simply implement the provided interfaces and have their tools and tool collections appear in the toolbox alongside other tools. The demonstration software presented here is based on an implementation of the interfaces and sample tool libraries using the C# .NET programming language. This poster will include a summary of the interfaces as well as a demonstration of the system using the Whitebox Geospatial Analysis Tools (GAT) as an example case of a large number of existing tools that can be exposed to users through this new system. Vector analysis tools which are native in DotSpatial are linked to the Whitebox raster analysis tools in the model builder environment for ease of execution and consistent/repeatable use. We expect that this approach to development of spatiotemporal analysis and geoprocessing software can be extended to many areas including basic GIS analysis, hydrological and terrain analysis, or processing images and working with LiDAR data.

Cao, Y.; Ames, D. P.

2011-12-01

285

Microwave landing system modeling with application to air traffic control automation  

NASA Technical Reports Server (NTRS)

Compared to the current instrument landing system, the microwave landing system (MLS), which is in the advanced stage of implementation, can potentially provide significant fuel and time savings as well as more flexibility in approach and landing functions. However, the expanded coverage and increased accuracy requirements of the MLS make it more susceptible to the features of the site in which it is located. An analytical approach is presented for evaluating the multipath effects of scatterers that are commonly found in airport environments. The approach combines a multiplane model with a ray-tracing technique and a formulation for estimating the electromagnetic fields caused by the antenna array in the presence of scatterers. The model is applied to several airport scenarios. The reduced computational burden enables the scattering effects on MLS position information to be evaluated in near real time. Evaluation in near real time would permit the incorporation of the modeling scheme into air traffic control automation; it would adaptively delineate zones of reduced accuracy within the MLS coverage volume, and help establish safe approach and takeoff trajectories in the presence of uneven terrain and other scatterers.

Poulose, M. M.

1992-01-01

286

Automated Geometric Model Builder Using Range Image Sensor Data: Final Acquistion  

SciTech Connect

This report documents a data collection where we recorded redundant range image data from multiple views of a simple scene, and recorded accurate survey measurements of the same scene. Collecting these data was a focus of the research project Automated Geometric Model Builder Using Range Image Sensor Data (96-0384), supported by Sandia's Laboratory-Directed Research and Development (LDRD) Program during fiscal years 1996, 1997, and 1998. The data described here are available from the authors on CDROM, or electronically over the Internet. Included in this data distribution are Computer-Aided Design (CAD) models we constructed from the survey measurements. The CAD models are compatible with the SolidWorks 98 Plus system, the modern Computer-Aided Design software system that is central to Sandia's DeskTop Engineering Project (DTEP). Integration of our measurements (as built) with the constructive geometry process of the CAD system (as designed) delivers on a vision of the research project. This report on our final data collection will also serve as a final report on the project.

Diegert, C.; Sackos, J.

1999-02-01

287

A Sketching Interface for Freeform 3D Modeling  

NASA Astrophysics Data System (ADS)

This chapter introduces Teddy, a sketch-based modeling system to quickly and easily design freeform models such as stuffed animals and other rotund objects. The user draws several 2D freeform strokes interactively on the screen and the system automatically constructs plausible 3D polygonal surfaces. Our system supports several modeling operations, including the operation to construct a 3D polygonal surface from a 2D silhouette drawn by the user: it inflates the region surrounded by the silhouette making a wide area fat, and a narrow area thin. Teddy, our prototype system, is implemented as a Java program, and the mesh construction is done in real-time on a standard PC. Our informal user study showed that a first-time user masters the operations within 10 minutes, and can construct interesting 3D models within minutes. We also report the result of a case study where a high school teacher taught various 3D concepts in geography using the system.

Igarashi, Takeo

288

Automated segmentation of psoas major muscle in X-ray CT images by use of a shape model: preliminary study  

Microsoft Academic Search

Our motivation was to provide an automatic tool for radiologists and orthopedic surgeons for improving the quality of life\\u000a of an aging population. We propose a method for generating a shape model and a fully automated segmenting scheme for the psoas\\u000a major muscle in X-ray CT images by using the shape model. Our approach consists of two steps: (1) The

Naoki Kamiya; Xiangrong Zhou; Huayue Chen; Chisako Muramatsu; Takeshi Hara; Ryujiro Yokoyama; Masayuki Kanematsu; Hiroaki Hoshi; Hiroshi Fujita

289

Cu-Bi as a Model System For Liquid Phase Sintered Thermal Interface Management Materials  

E-print Network

Cu-Bi as a Model System For Liquid Phase Sintered Thermal Interface Management Materials P and respective thermal conductivity Heat Sink Si Device TIMHEAT HEAT Heat Sink Si Device TIM Heat Sink Si Device TIM 1) High thermal conductivity to conduct heat from silicon device to heat sink 2) High compliance

Collins, Gary S.

290

Interfaces in Driven Ising Models: Shear Enhances Confinement Thomas H. R. Smith,1  

E-print Network

Interfaces in Driven Ising Models: Shear Enhances Confinement Thomas H. R. Smith,1 Oleg Vasilyev,2 Douglas B. Abraham,2,3 Anna Maciolek,2,3,4 and Matthias Schmidt1 1 H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom 2 Max-Planck-Institut fu¨r

Schmidt, Matthias

291

The integrity of welded interfaces in ultra high molecular weight polyethylene: Part 1-Model.  

PubMed

The difficulty of eradicating memory of powder-particle interfaces in UHMWPE for bearing surfaces for hip and knee replacements is well-known, and 'fusion defects' have been implicated frequently in joint failures. During processing the polymer is formed into solid directly from the reactor powder, under pressure and at temperatures above the melting point, and two types of inter-particle defect occur: Type 1 (consolidation-deficient) and Type 2 (diffusion-deficient). To gain quantitative information on the extent of the problem, the formation of macroscopic butt welds in this material was studied, by (1) modelling the process and (2) measuring experimentally the resultant evolution of interface toughness. This paper reports on the model. A quantitative measure of interface structural integrity is defined, and related to the "maximum reptated molecular weight" introduced previously. The model assumes an idealised surface topography. It is used to calculate the evolution of interface integrity during welding, for given values of temperature, pressure, and parameters describing the surfaces, and a given molar mass distribution. Only four material properties are needed for the calculation; all of them available for polyethylene. The model shows that, for UHMWPE typically employed in knee transplants, the rate of eradication of Type 1 defects is highly sensitive to surface topography, process temperature and pressure. Also, even if Type 1 defects are prevented, Type 2 defects heal extremely slowly. They must be an intrinsic feature of UHMWPE for all reasonable forming conditions, and products and forming processes should be designed accordingly. PMID:16490249

Buckley, C Paul; Wu, Junjie; Haughie, David W

2006-06-01

292

MEASUREMENT AND MODELLING OF AMMONIA EMISSIONS AT WASTE TREATMENT LAGOON-ATMOSPHERIC INTERFACE  

E-print Network

MEASUREMENT AND MODELLING OF AMMONIA EMISSIONS AT WASTE TREATMENT LAGOON-ATMOSPHERIC INTERFACE of ammonia are approximately 75 Tg N/yr (1 Tg = 1012g). The major global source is excreta from domestic in North Carolina (NC). Proteins and nitrogen rich compounds in the lagoon are converted to ammonia

Aneja, Viney P.

293

Line tension at wetting: interface displacement model beyond the gradient-squared approximation  

Microsoft Academic Search

We study the transition zone or contact line between a thin film and bulk liquid, and calculate the line tension tau, employing an interface displacement model equivalent to Derjaguin's and de Gennes' approach. We investigate the behaviour of tau in the limit that the contact angle vartheta tends to zero, approaching a wetting phase transition. Previous results for wetting and

H. T. Dobbs; J. O. Indekeu

1993-01-01

294

The phase-field method in the sharp-interface limit: A comparison between model potentials  

SciTech Connect

The phase-field (PF) method for solidification phenomena is an open formulation based on a free-energy functional. Two common choices for the PF potential, here referred to briefly as the Caginalp and Kobayashi models, are compared with respect to their numeric results within the classical sharp-interface limit. Both qualitative and quantitative behavior are addressed, and an assessment of the computational effort required to approximate a sharp-interface problem is made. It is shown that the specific form of the free-energy potential does have a strong influence on the convergence of the PF results to their sharp-interface limit. Compliance of the PF solutions with the linear kinetic model for the interface temperature is also investigated. A simple one-dimensional solidification problem in the presence of kinetic undercooling is solved by the PF model and also by a deforming grid method. Our results support the view that, if care is exercised in formulating the phase-temperature coupling, there is a high degree of confidence in using the PF method for the numerical modeling of general solidification phenomena. 26 refs., 9 figs., 1 tab.

Fabbri, M. [Universidade Sao Francisco, Itatiba (Brazil)] [Universidade Sao Francisco, Itatiba (Brazil); Voller, V.R. [Univ. of Minnesota, Minneapolis, MN (United States)] [Univ. of Minnesota, Minneapolis, MN (United States)

1997-01-15

295

Support of surgical process modeling by using adaptable software user interfaces  

NASA Astrophysics Data System (ADS)

Surgical Process Modeling (SPM) is a powerful method for acquiring data about the evolution of surgical procedures. Surgical Process Models are used in a variety of use cases including evaluation studies, requirements analysis and procedure optimization, surgical education, and workflow management scheme design. This work proposes the use of adaptive, situation-aware user interfaces for observation support software for SPM. We developed a method to support the modeling of the observer by using an ontological knowledge base. This is used to drive the graphical user interface for the observer to restrict the search space of terminology depending on the current situation. In the evaluation study it is shown, that the workload of the observer was decreased significantly by using adaptive user interfaces. 54 SPM observation protocols were analyzed by using the NASA Task Load Index and it was shown that the use of the adaptive user interface disburdens the observer significantly in workload criteria effort, mental demand and temporal demand, helping him to concentrate on his essential task of modeling the Surgical Process.

Neumuth, T.; Kaschek, B.; Czygan, M.; Goldstein, D.; Strauß, G.; Meixensberger, J.; Burgert, O.

2010-03-01

296

Developing a TeraGrid Based Land Surface Hydrology and Weather Modeling Interface  

E-print Network

Developing a TeraGrid Based Land Surface Hydrology and Weather Modeling Interface Hsin-I Chang1 iclimate@purdue.edu -------------------- -------------------- 1 INTRODUCTION Real world hydrologic cyberinfrastructure (CI) has been articulated in many workshops and meetings of the environmental and hydrologic

Jiang, Wen

297

A Monthly Water-Balance Model Driven By a Graphical User Interface  

USGS Publications Warehouse

This report describes a monthly water-balance model driven by a graphical user interface, referred to as the Thornthwaite monthly water-balance program. Computations of monthly water-balance components of the hydrologic cycle are made for a specified location. The program can be used as a research tool, an assessment tool, and a tool for classroom instruction.

McCabe, Gregory J.; Markstrom, Steven L.

2007-01-01

298

Facial pressure zones of an oronasal interface for noninvasive ventilation: a computer model analysis* **  

PubMed Central

OBJECTIVE: To study the effects of an oronasal interface (OI) for noninvasive ventilation, using a three-dimensional (3D) computational model with the ability to simulate and evaluate the main pressure zones (PZs) of the OI on the human face. METHODS: We used a 3D digital model of the human face, based on a pre-established geometric model. The model simulated soft tissues, skull, and nasal cartilage. The geometric model was obtained by 3D laser scanning and post-processed for use in the model created, with the objective of separating the cushion from the frame. A computer simulation was performed to determine the pressure required in order to create the facial PZs. We obtained descriptive graphical images of the PZs and their intensity. RESULTS: For the graphical analyses of each face-OI model pair and their respective evaluations, we ran 21 simulations. The computer model identified several high-impact PZs in the nasal bridge and paranasal regions. The variation in soft tissue depth had a direct impact on the amount of pressure applied (438-724 cmH2O). CONCLUSIONS: The computer simulation results indicate that, in patients submitted to noninvasive ventilation with an OI, the probability of skin lesion is higher in the nasal bridge and paranasal regions. This methodology could increase the applicability of biomechanical research on noninvasive ventilation interfaces, providing the information needed in order to choose the interface that best minimizes the risk of skin lesion. PMID:25610506

Barros, Luana Souto; Talaia, Pedro; Drummond, Marta; Natal-Jorge, Renato

2014-01-01

299

An ASM/ADM model interface for dynamic plant-wide simulation.  

PubMed

Mathematical modelling has proven to be very useful in process design, operation and optimisation. A recent trend in WWTP modelling is to include the different subunits in so-called plant-wide models rather than focusing on parts of the entire process. One example of a typical plant-wide model is the coupling of an upstream activated sludge plant (including primary settler, and secondary clarifier) to an anaerobic digester for sludge digestion. One of the key challenges when coupling these processes has been the definition of an interface between the well accepted activated sludge model (ASM1) and anaerobic digestion model (ADM1). Current characterisation and interface models have key limitations, the most critical of which is the over-use of X(c) (or lumped complex) variable as a main input to the ADM1. Over-use of X(c) does not allow for variation of degradability, carbon oxidation state or nitrogen content. In addition, achieving a target influent pH through the proper definition of the ionic system can be difficult. In this paper, we define an interface and characterisation model that maps degradable components directly to carbohydrates, proteins and lipids (and their soluble analogues), as well as organic acids, rather than using X(c). While this interface has been designed for use with the Benchmark Simulation Model No. 2 (BSM2), it is widely applicable to ADM1 input characterisation in general. We have demonstrated the model both hypothetically (BSM2), and practically on a full-scale anaerobic digester treating sewage sludge. PMID:19232670

Nopens, Ingmar; Batstone, Damien J; Copp, John B; Jeppsson, Ulf; Volcke, Eveline; Alex, Jens; Vanrolleghem, Peter A

2009-04-01

300

A Laboratory Seismoelectric Measurement for the Permafrost Model with a Frozen-unfrozen Interface  

NASA Astrophysics Data System (ADS)

For the Qing-Cang railway line located in the permafrost region, the freeze-thaw cycling with the seasons and spring-thaw of the permafrost are main factors to weaken the railway bed. Therefore, the determination of the frozen-unfrozen interface depth below the railway bed is important for the railway operation, and moreover, it can contribute to the evaluation of the permafrost environment effected by the railway. Since the frozen-unfrozen interface is a contact of two media with various porosity and saturation, an electric double-layer can be formed at the interface by the absorption of electrical charge to it. When a seismic wave is incident at the interface, a relative motion of the charges in the electric double-layer would induce an electromagnetic (EM) wave, or a seismoeletric conversion signal that can be measured remotely, which is potential for determining the frost depth. A simple permafrost model with a frozen-unfrozen interface was built mainly by two parts: the upper part was a frozen sand block with a 7cm thickness and the lower one with the same material was in an unfrozen state saturated with water. And the contact of the two parts simulated the frozen-unfrozen interface. The interface model was placed in a freezer, while it was heated from the bottom with a heating sheet made by the electric heating wires laid under the unfrozen part. A P-wave source transducer with 48 kHz narrow band frequency was set on the top the frozen part and driven by a square electric pulse. The six electrodes with a 1 cm even interval were fixed inside the frozen part with 1 cm vertical distance to the interface. In the experiment, all the analog signals acquired from the temperature sensors, acoustic transducers, and electrodes were sent through preamplifiers and recorded digitally by computer-based virtual instruments (VIs). At the beginning of the experiment, the first arrivals of the seismoeletric signals observed from the six electrodes with minimum offset set to be 7cm were proportional to the distances between the acoustic sources to electrodes, and thus the EM signals are originated from the stationary electromagnetic field that moves along with the acoustic waves. After the eight hours, we recognized two new events of EM waves by their exactly identical arrive times from the six electrodes. The event A with identical arrival time being close to zero is the EM interference of the high-voltage pulse exciting the acoustic source transducer. The identical arrival time 23-25 microsecond of the event B roughly equates to that of the acoustic wave travel time from the source to the interface, and it is obviously the conversion EM signal originated from the electric double-layer in the interface. With a minimum 14cm offset, the event A arrived at the same time only with greatly reduced amplitude, and the event B had not able to be detected for its weak amplitude. Another event B' with an about 50 microsecond identical arriving time could, however, be recognized, and it should be a conversion EM wave from the interface exited by the second acoustic vibration cycle from the acoustic source wave with higher amplitude, as the arrival time just equates to that of the second cycle of the narrow band acoustic wave to travel to the interface. These measurements in the laboratory show that , the electric double-layer formed at the frozen-unfrozen interface can be polarized to generate EM waves by both an EM pulse and a vibration source, which imply that the frozen-unfrozen interface of the permafrost could be surveying by both EM, and seismoelectric methods. And the results also show that the electric double-layer needs several hours to be formed in a laboratory experiment under low tempreture.

Liu, Z.

2007-12-01

301

Asymmetric hemisphere modeling in an offline brain-computer interface  

Microsoft Academic Search

Classification of the electroencephalogram (EEG) during motor imagery of the left or right hand can be performed using a classifier comprising two hidden Markov models (HMMs) describing the spatio-temporal patterns related to the imagination. Due to the known asymmetries during motor imagery of rightand left-hand movement, an HMM-based classifier allowing asymmetrical structures is introduced. The comparison between such a system

Bernhard Obermaier; Cristian Munteanu; Agostinho C. Rosa; Gert Pfurtscheller

2001-01-01

302

Modeling Nitrogen Cycle at the Surface-Subsurface Water Interface  

NASA Astrophysics Data System (ADS)

Anthropogenic activities, primarily food and energy production, have altered the global nitrogen cycle, increasing reactive dissolved inorganic nitrogen, Nr, chiefly ammonium NH4+ and nitrate NO3-, availability in many streams worldwide. Increased Nr promotes biological activity often with negative consequences such as water body eutrophication and emission of nitrous oxide gas, N2O, an important greenhouse gas as a by-product of denitrification. The hyporheic zone may play an important role in processing Nr and returning it to the atmosphere. Here, we present a process-based three-dimensional semi-analytical model, which couples hyporheic hydraulics with biogeochemical reactions and transport equations. Transport is solved by means of particle tracking with negligible local dispersion and biogeochemical reactions modeled by linearized Monod's kinetics with temperature dependant reaction rate coefficients. Comparison of measured and predicted N2O emissions from 7 natural stream shows a good match. We apply our model to gravel bed rivers with alternate bar morphology to investigate the role of hyporheic hydraulic, depth of alluvium, relative availability of stream concentration of NO3- and NH4+ and water temperature on nitrogen gradients within the sediment. Our model shows complex concentration dynamics, which depend on hyporheic residence time distribution and consequently on streambed morphology, within the hyporheic zone. Nitrogen gas emissions from the hyporheic zone increase with alluvium depth in large low-gradient streams but not in small steep streams. On the other hand, hyporheic water temperature influences nitrification/denitrification processes mainly in small-steep than large low-gradient streams, because of the long residence times, which offset the slow reaction rates induced by low temperatures in the latter stream. The overall conclusion of our analysis is that river morphology has a major impact on biogeochemical processes such as nitrification and denitrification with a direct impact on the stream nutrient removal and transport.

Marzadri, A.; Tonina, D.; Bellin, A.

2011-12-01

303

Coarse Grained Modeling of The Interface BetweenWater and Heterogeneous Surfaces  

SciTech Connect

Using coarse grained models we investigate the behavior of water adjacent to an extended hydrophobic surface peppered with various fractions of hydrophilic patches of different sizes. We study the spatial dependence of the mean interface height, the solvent density fluctuations related to drying the patchy substrate, and the spatial dependence of interfacial fluctuations. We find that adding small uniform attractive interactions between the substrate and solvent cause the mean position of the interface to be very close to the substrate. Nevertheless, the interfacial fluctuations are large and spatially heterogeneous in response to the underlying patchy substrate. We discuss the implications of these findings to the assembly of heterogeneous surfaces.

Willard, Adam; Chandler, David

2008-06-23

304

Efficient loads analyses of Shuttle-payloads using dynamic models with linear or nonlinear interfaces  

NASA Technical Reports Server (NTRS)

An efficient method for the load analysis of Shuttle-payload systems with linear or nonlinear attachment interfaces is presented which allows the kinematics of the interface degrees of freedom at a given time to be evaluated without calculating the combined system modal representation of the Space Shuttle and its payload. For the case of a nonlinear dynamic model, an iterative procedure is employed to converge the nonlinear terms of the equations of motion to reliable values. Results are presented for a Shuttle abort landing event.

Spanos, P. D.; Cao, T. T.; Hamilton, D. A.; Nelson, D. A. R.

1989-01-01

305

Dynamic lattice Monte Carlo simulation of a model protein at an oil/water interface  

NASA Astrophysics Data System (ADS)

Adsorption of a proteinlike heteropolymer is modeled at an oil/water interface by dynamic lattice Monte Carlo simulation. The heteropolymer is a designed sequence of 27 amino-acid-type lattice sites and has been used as a model for short (50-70) residue proteins. Oil is represented by a characteristic hydrophobic amino acid monomer, and water is represented by a characteristic hydrophilic amino acid monomer. The model protein is initially placed slightly away from the oil/water interface and is then allowed to undergo Verdier-Stockmeyer moves as amino acid sites interact with each other and with the oil and water. Local mixing of the oil and water is permitted over the length scale of the protein. Our lattice representation displays correct behavior in bulk water in that the model protein folds rapidly from an extended rod into a globular like state. In addition, there is a phase transition between the globular (folded) state and the denatured (unfolded) state at a particular temperature, Tm*. By examining the free-energy landscape at 0.94 Tm*, we identify four configurational states in the adsorbing system: unfolded in the bulk water, folded in the bulk water, unfolded at the interface, and folded at the interface. The most probable state of the four is the adsorbed unfolded state at the interface, with a large free-energy barrier to desorption. (˜20kBTm*). We find that it is the unfavorable interaction between the oil and the water that drives the protein to the interface. Adsorption of a single protein molecule reduces the oil and water energies by 175kBTm*. A typical conformation of the adsorbed, unfolded protein has the majority of protein segments remaining in the water but lying directly adjacent to the interface, with about 30% loops penetrating into the water phase and only a few segments (˜10%) penetrating into the oil. This work provides a picture of single-molecule protein adsorption at the oil/water interface in which the protein unfolds into an extended train structure and thereafter is essentially irreversibly bound.

Anderson, Rebeccah E.; Pande, Vijay S.; Radke, Clayton J.

2000-05-01

306

Automated choroidal segmentation of 1060 nm OCT in healthy and pathologic eyes using a statistical model  

PubMed Central

A two stage statistical model based on texture and shape for fully automatic choroidal segmentation of normal and pathologic eyes obtained by a 1060 nm optical coherence tomography (OCT) system is developed. A novel dynamic programming approach is implemented to determine location of the retinal pigment epithelium/ Bruch’s membrane /choriocapillaris (RBC) boundary. The choroid–sclera interface (CSI) is segmented using a statistical model. The algorithm is robust even in presence of speckle noise, low signal (thick choroid), retinal pigment epithelium (RPE) detachments and atrophy, drusen, shadowing and other artifacts. Evaluation against a set of 871 manually segmented cross-sectional scans from 12 eyes achieves an average error rate of 13%, computed per tomogram as a ratio of incorrectly classified pixels and the total layer surface. For the first time a fully automatic choroidal segmentation algorithm is successfully applied to a wide range of clinical volumetric OCT data. PMID:22254171

Kaji?, Vedran; Esmaeelpour, Marieh; Považay, Boris; Marshall, David; Rosin, Paul L.; Drexler, Wolfgang

2011-01-01

307

Automated fit quantification of tibial nail designs during the insertion using computer three-dimensional modelling.  

PubMed

Intramedullary nailing is the standard fixation method for displaced diaphyseal fractures of the tibia. An optimal nail design should both facilitate insertion and anatomically fit the bone geometry at its final position in order to reduce the risk of stress fractures and malalignments. Due to the nonexistence of suitable commercial software, we developed a software tool for the automated fit assessment of nail designs. Furthermore, we demonstrated that an optimised nail, which fits better at the final position, is also easier to insert. Three-dimensional models of two nail designs and 20 tibiae were used. The fitting was quantified in terms of surface area, maximum distance, sum of surface areas and sum of maximum distances by which the nail was protruding into the cortex. The software was programmed to insert the nail into the bone model and to quantify the fit at defined increment levels. On average, the misfit during the insertion in terms of the four fitting parameters was smaller for the Expert Tibial Nail Proximal bend (476.3?mm(2), 1.5?mm, 2029.8?mm(2), 6.5?mm) than the Expert Tibial Nail (736.7?mm(2), 2.2?mm, 2491.4?mm(2), 8.0?mm). The differences were statistically significant (p???0.05). The software could be used by nail implant manufacturers for the purpose of implant design validation. PMID:25515223

Amarathunga, Jayani P; Schuetz, Michael A; Yarlagadda, Prasad Kvd; Schmutz, Beat

2014-12-01

308

Numerical modeling of flow in a differential chamber of the gas-dynamic interface of a portable mass-spectrometer  

NASA Astrophysics Data System (ADS)

Mathematical modeling of flow in the differential chamber of the gas-dynamic interface of a portable mass-spectrometer was carried out to comprehensively study the flow structure and make recommendations for the optimization of the gas-dynamic interface. Modeling was performed using an OpenFOAM open computational platform. Conditions for an optimal operating mode of the differential chamber were determined.

Pivovarova, E. A.; Smirnovsky, A. A.; Schmidt, A. A.

2013-11-01

309

Modeling the interface of Li metal and Li solid electrolytes from first principles Nicholas Lepley, N. A. W. Holzwarth  

E-print Network

Modeling the interface of Li metal and Li solid electrolytes from first principles Nicholas Lepley battery electrolytes. Simplified theoretical models often fail to agree with experimental observations of the stability of electrode electrolyte interfaces. An example of this disagreement is the thiophosphate

Holzwarth, Natalie

310

Open boundary conditions for the Diffuse Interface Model in 1-D  

NASA Astrophysics Data System (ADS)

New techniques are developed for solving multi-phase flows in unbounded domains using the Diffuse Interface Model in 1-D. They extend two open boundary conditions originally designed for the Navier-Stokes equations. The non-dimensional formulation of the DIM generalizes the approach to any fluid. The equations support a steady state whose analytical approximation close to the critical point depends only on temperature. This feature enables the use of detectors at the boundaries switching between conventional boundary conditions in bulk phases and a multi-phase strategy in interfacial regions. Moreover, the latter takes advantage of the steady state approximation to minimize the interface-boundary interactions. The techniques are applied to fluids experiencing a phase transition and where the interface between the phases travels through one of the boundaries. When the interface crossing the boundary is fully developed, the technique greatly improves results relative to cases where conventional boundary conditions can be used. Limitations appear when the interface crossing the boundary is not a stable equilibrium between the two phases: the terms responsible for creating the true balance between the phases perturb the interior solution. Both boundary conditions present good numerical stability properties: the error remains bounded when the initial conditions or the far field values are perturbed. For the PML, the influence of its main parameters on the global error is investigated to make a compromise between computational costs and maximum error. The approach can be extended to multiple spatial dimensions.

Desmarais, J. L.; Kuerten, J. G. M.

2014-04-01

311

Nuclear Reactor/Hydrogen Process Interface Including the HyPEP Model  

SciTech Connect

The Nuclear Reactor/Hydrogen Plant interface is the intermediate heat transport loop that will connect a very high temperature gas-cooled nuclear reactor (VHTR) to a thermochemical, high-temperature electrolysis, or hybrid hydrogen production plant. A prototype plant called the Next Generation Nuclear Plant (NGNP) is planned for construction and operation at the Idaho National Laboratory in the 2018-2021 timeframe, and will involve a VHTR, a high-temperature interface, and a hydrogen production plant. The interface is responsible for transporting high-temperature thermal energy from the nuclear reactor to the hydrogen production plant while protecting the nuclear plant from operational disturbances at the hydrogen plant. Development of the interface is occurring under the DOE Nuclear Hydrogen Initiative (NHI) and involves the study, design, and development of high-temperature heat exchangers, heat transport systems, materials, safety, and integrated system models. Research and development work on the system interface began in 2004 and is expected to continue at least until the start of construction of an engineering-scale demonstration plant.

Steven R. Sherman

2007-05-01

312

Atomic scale model interfaces between high- k hafnium silicates and silicon  

NASA Astrophysics Data System (ADS)

Hafnium silicates (HfySi1-yO2) are being considered as high- k gate dielectrics in field-effect transistors as a compromise between high permittivity and thermal stability on silicon during complementary metal-oxide-semiconductor processing. Using hafnon (HfSiO4) as a prototypical hafnium silicate, we have explored model abrupt interfaces at the atomic scale, employing various hafnon surfaces on Si(100) and Si(110) via a silicon suboxide interfacial layer. Relative stabilities are computed using molecular dynamics and geometry optimization at the density-functional theory level. The immiscibility of HfO2 and SiO2 means that the interface is intrinsically metastable, so that we predict a poor-quality interface under oxygen-poor conditions. On the other hand, the interface is stabilized under oxidizing conditions, leading eventually to the growth of the interfacial layer into the Si substrate. We find evidence that Si(110) resists oxidation more than Si(100). Structural features such as Hf-O-Si and Si-O-Si bridges are found to be common to all defect-free interfaces under all conditions. 4Å is the minimum thickness of the defect-free suboxide interfacial layer.

Monaghan, S.; Greer, J. C.; Elliott, S. D.

2007-06-01

313

Mapping local laboratory interface terms to LOINC at a German university hospital using RELMA V.5: a semi-automated approach  

PubMed Central

Objective Logical Observation Identifiers Names and Codes (LOINC) mapping of laboratory data is often a question of the effort of mapping compared with the benefits of the structure achieved. The new LOINC mapping assistant RELMA (version 2011) has the potential to reduce the effort required for semi-automated mapping. We examined quality, time effort, and sustainability of such mapping. Methods To verify the mapping quality, two samples of 100 laboratory terms were extracted from the laboratory system of a German university hospital and processed in a semi-automated fashion with RELMA V.5 and LOINC V.2.34 German translation DIMDI to obtain LOINC codes. These codes were reviewed by two experts from each of two laboratories. Then all 2148 terms used in these two laboratories were processed in the same way. Results In the initial samples, 93 terms from one laboratory system and 92 terms from the other were correctly mapped. Of the total 2148 terms, 1660 could be mapped. An average of 500 terms per day or 60 terms per hour could be mapped. Of the laboratory terms used in 2010, 99% could be mapped. Discussion Semi-automated LOINC mapping of non-English laboratory terms has become promising in terms of effort and mapping quality using the new version RELMA V.5. The effort is probably lower than for previous manual mapping. The mapping quality equals that of manual mapping and is far better than that reported with previous automated mapping activities. Conclusion RELMA V.5 and LOINC V.2.34 offer the opportunity to start thinking again about LOINC mapping even in non-English languages, since mapping effort is acceptable and mapping results equal those of previous manual mapping reports. PMID:22802268

Bürkle, Thomas; Prokosch, Hans-Ulrich; Ganslandt, Thomas

2013-01-01

314

NURBS- and T-spline-based isogeometric cohesive zone modeling of interface debonding  

NASA Astrophysics Data System (ADS)

Cohesive zone (CZ) models have long been used by the scientific community to analyze the progressive damage of materials and interfaces. In these models, non-linear relationships between tractions and relative displacements are assumed, which dictate both the work of separation per unit fracture surface and the peak stress that has to be reached for the crack formation. This contribution deals with isogeometric CZ modeling of interface debonding. The interface is discretized with generalized contact elements which account for both contact and cohesive debonding within a unified framework. The formulation is suitable for non-matching discretizations of the interacting surfaces in presence of large deformations and large relative displacements. The isogeometric discretizations are based on non uniform rational B-splines as well as analysis-suitable T-splines enabling local refinement. Conventional Lagrange polynomial discretizations are also used for comparison purposes. Some numerical examples demonstrate that the proposed formulation based on isogeometric analysis is a computationally accurate and efficient technology to solve challenging interface debonding problems in 2D and 3D.

Dimitri, R.; De Lorenzis, L.; Wriggers, P.; Zavarise, G.

2014-08-01

315

The contact line behaviour of solid-liquid-gas diffuse-interface models  

NASA Astrophysics Data System (ADS)

A solid-liquid-gas moving contact line is considered through a diffuse-interface model with the classical boundary condition of no-slip at the solid surface. Examination of the asymptotic behaviour as the contact line is approached shows that the relaxation of the classical model of a sharp liquid-gas interface, whilst retaining the no-slip condition, resolves the stress, and pressure singularities associated with the moving contact line problem while the fluid velocity is well defined (not multi-valued). The moving contact line behaviour is analysed for a general problem relevant for any density dependent dynamic viscosity and volume viscosity, and for general microscopic contact angle and double well free-energy forms. Away from the contact line, analysis of the diffuse-interface model shows that the Navier-Stokes equations and classical interfacial boundary conditions are obtained at leading order in the sharp-interface limit, justifying the creeping flow problem imposed in an intermediate region in the seminal work of Seppecher [Int. J. Eng. Sci. 34, 977-992 (1996)]. Corrections to Seppecher's work are given, as an incorrect solution form was originally used.

Sibley, David N.; Nold, Andreas; Savva, Nikos; Kalliadasis, Serafim

2013-09-01

316

Ontology-Supported and Query Template-Based User Modeling Techniques for Interface Agents  

Microsoft Academic Search

In this paper, we report an Interface Agent with ontology-supported, query template-based user modeling techniques. It works as an assistant between the users and FAQ systems to retrieve FAQs on the domain of Personal Computers. We integrated several interesting techniques including user modeling, domain ontology, and template-based linguistic processing to effectively tackle the problems associated with traditional FAQ retrieval systems.

Sheng-Yuan Yang; Ying-Hao Chiu

2004-01-01

317

Incorporation of the electrode–electrolyte interface into finite-element models of metal microelectrodes  

Microsoft Academic Search

An accurate description of the electrode–electrolyte interfacial impedance is critical to the development of computational models of neural recording and stimulation that aim to improve understanding of neuro–electric interfaces and to expedite electrode design. This work examines the effect that the electrode–electrolyte interfacial impedance has upon the solutions generated from time-harmonic finite-element models of cone- and disk-shaped platinum microelectrodes submerged

Donald R Cantrell; Samsoon Inayat; Allen Taflove; Rodney S Ruoff; John B Troy

2008-01-01

318

Optimod – An automated approach for constructing and optimizing initial models for single-particle electron microscopy  

PubMed Central

Single-particle cryo-electron microscopy is now well established as a technique for the structural characterization of large macromolecules and macromolecular complexes. The raw data is very noisy and consists of two-dimensional projections, from which the 3D biological object must be reconstructed. The 3D object depends upon knowledge of proper angular orientations assigned to the 2D projection images. Numerous algorithms have been developed for determining relative angular orientations between 2D images, but the transition from 2D to 3D remains challenging and can result in erroneous and conflicting results. Here we describe a general, automated procedure, called OptiMod, for reconstructing and optimizing 3D models using common-lines methodologies. OptiMod approximates orientation angles and reconstructs independent maps from 2D class averages. It then iterates the procedure, while considering each map as a raw solution that needs to be compared with other possible outcomes. We incorporate procedures for 3D alignment, clustering, and refinement to optimize each map, as well as standard scoring metrics to facilitate the selection of the optimal model. We also show that small angle tilt-pair data can be included as one of the scoring metrics to improve the selection of the optimal initial model, and also to provide a validation check. The overall approach is demonstrated using two experimental cryo-EM data sets – the 80S ribosome that represents a relatively straightforward case for ab initio reconstruction, and the Tf–TfR complex that represents a challenging case in that it has previously been shown to provide multiple equally plausible solutions to the initial model problem. PMID:24161732

Lyumkis, Dmitry; Vinterbo, Staal; Potter, Clinton S.; Carragher, Bridget

2013-01-01

319

Design of a photoionization detector for high-performance liquid chromatography using an automated liquid-to-vapor phase interface and application to phenobarbital in an animal feed and to amantadine.  

PubMed

An automated liquid-to-vapor phase interface system forms the basis for a new high-performance liquid chromatography (HPLC)-photoionization detection (PID) system. The system incorporates a six-valve interface enabling peak trapping, solvent switching and thermal desorption of the solute of interest into a vapor phase PID. For reversed-phase HPLC, the eluted solute peak is isolated on a Tenax trap after dilution of the effluent with water; the water is then evaporated, following which the trapped solute is flash-evaporated into the PID system. For normal-phase HPLC, the column effluent is diluted with hexane, the solute peak is concentrated on a short column packed with a propyl-amino/cyano bonded phase and the solvent is evaporated. The solute is then eluted with water onto the Tenax trap, and the above procedure for reversed-phase HPLC followed. All operations are controlled with a microcomputer. The advantages of the new detector system include completely automated operation, fast sample preparation, high sensitivity, and inherent selectivity. The system was applied to phenobarbital, which was extracted with acetonitrile from spiked laboratory animal feed, and to amantadine. The phenobarbital assay used a normal-phase separation with hexane-methyl tert.-butyl ether-methanol eluent. The manual sample preparation time was 5 min and the limit of detection was 2 ng phenobarbital injected; a conventional HPLC assay with UV detection required a longer sample preparation time and had a detection limit of 700 ng. Amantadine was assayed using a reversed-phase HPLC system with a water-methanol-triethylamine-orthophosphoric acid mobile phase. The detection limit was 25 ng injected. PMID:2355063

Schmermund, J T; Locke, D C

1990-05-01

320

Micromechanical modeling of the cement-bone interface: the effect of friction, morphology and material properties on the micromechanical response  

PubMed Central

In order to gain insight into the micro-mechanical behavior of the cement-bone interface, the effect of parametric variations of frictional, morphological and material properties on the mechanical response of the cement-bone interface were analyzed using a finite element approach. Finite element models of a cement-bone interface specimen were created from micro-computed tomography data of a physical specimen that was sectioned from an in vitro cemented total hip arthroplasty. In five models the friction coefficient was varied (?= 0.0; 0.3; 0.7; 1.0 and 3.0), while in one model an ideally bonded interface was assumed. In two models cement interface gaps and an optimal cement penetration were simulated. Finally, the effect of bone cement stiffness variations was simulated (2.0 and 2.5 GPa, relative to the default 3.0 GPa). All models were loaded for a cycle of fully reversible tension-compression. From the simulated stress-displacement curves the interface deformation, stiffness and hysteresis were calculated. The results indicate that in the current model the mechanical properties of the cement-bone interface were caused by frictional phenomena at the shape-closed interlock rather than by adhesive properties of the cement. Our findings furthermore show that in our model maximizing cement penetration improved the micromechanical response of the cement-bone interface stiffness, while interface gaps had a detrimental effect. Relative to the frictional and morphological variations, variations in the cement stiffness had only a modest effect on the micromechanical behavior of the cement-bone interface. The current study provides information that may help to better understand the load transfer mechanisms taking place at the cement-bone interface. PMID:18848699

Janssen, Dennis; Mann, Kenneth A.; Verdonschot, Nico

2008-01-01

321

Models for the histologic study of the skin interface with percutaneous biomaterials  

PubMed Central

Percutaneous devices are critical for health care. Access to tissue, vessels, and internal organs afforded by these devices provides the means to treat and monitor many diseases. Unfortunately, such access is not restricted, and infection may compromise the usefulness of the device and even the life of the patient. New biomaterials offer the possibility of maintaining internal access while limiting microbial access, but understanding of the cutaneous/ biomaterial interface and models to study this area are limited. This review focuses on models useful for studying the morphology and biology of the intersection of skin and percutaneous biomaterials. An organ culture and a mouse model are described that offer promising possibilities for improved understanding of this critical interface. PMID:18708704

Fleckman, P; Olerud, JE

2009-01-01

322

CS 525: Advanced Database Organization Study of relational, semantic, and object-oriented data models and interfaces. Database management system  

E-print Network

CS 525: Advanced Database Organization Objectives Study of relational, semantic, and object-oriented data models and interfaces. Database management system techniques for query optimization, concurrency History of database management. Goals of database system development. Relational systems Data models

Heller, Barbara

323

3-D FEM Modeling of fiber/matrix interface debonding in UD composites including surface effects  

NASA Astrophysics Data System (ADS)

Fiber/matrix interface debond growth is one of the main mechanisms of damage evolution in unidirectional (UD) polymer composites. Because for polymer composites the fiber strain to failure is smaller than for the matrix multiple fiber breaks occur at random positions when high mechanical stress is applied to the composite. The energy released due to each fiber break is usually larger than necessary for the creation of a fiber break therefore a partial debonding of fiber/matrix interface is typically observed. Thus the stiffness reduction of UD composite is contributed both from the fiber breaks and from the interface debonds. The aim of this paper is to analyze the debond growth in carbon fiber/epoxy and glass fiber/epoxy UD composites using fracture mechanics principles by calculation of energy release rate GII. A 3-D FEM model is developed for calculation of energy release rate for fiber/matrix interface debonds at different locations in the composite including the composite surface region where the stress state differs from the one in the bulk composite. In the model individual partially debonded fiber is surrounded by matrix region and embedded in a homogenized composite.

Pupurs, A.; Varna, J.

2012-02-01

324

Integration Of Heat Transfer Coefficient In Glass Forming Modeling With Special Interface Element  

NASA Astrophysics Data System (ADS)

Numerical modeling of the glass forming processes requires the accurate knowledge of the heat exchange between the glass and the forming tools. A laboratory testing is developed to determine the evolution of the heat transfer coefficient in different glass/mould contact conditions (contact pressure, temperature, lubrication…). In this paper, trials are performed to determine heat transfer coefficient evolutions in experimental conditions close to the industrial blow-and-blow process conditions. In parallel of this work, a special interface element is implemented in a commercial Finite Element code in order to deal with heat transfer between glass and mould for non-meshing meshes and evolutive contact. This special interface element, implemented by using user subroutines, permits to introduce the previous heat transfer coefficient evolutions in the numerical modelings at the glass/mould interface in function of the local temperatures, contact pressures, contact time and kind of lubrication. The blow-and-blow forming simulation of a perfume bottle is finally performed to assess the special interface element performance.

Moreau, P.; César de Sá, J.; Grégoire, S.; Lochegnies, D.

2007-05-01

325

Integration Of Heat Transfer Coefficient In Glass Forming Modeling With Special Interface Element  

SciTech Connect

Numerical modeling of the glass forming processes requires the accurate knowledge of the heat exchange between the glass and the forming tools. A laboratory testing is developed to determine the evolution of the heat transfer coefficient in different glass/mould contact conditions (contact pressure, temperature, lubrication...). In this paper, trials are performed to determine heat transfer coefficient evolutions in experimental conditions close to the industrial blow-and-blow process conditions. In parallel of this work, a special interface element is implemented in a commercial Finite Element code in order to deal with heat transfer between glass and mould for non-meshing meshes and evolutive contact. This special interface element, implemented by using user subroutines, permits to introduce the previous heat transfer coefficient evolutions in the numerical modelings at the glass/mould interface in function of the local temperatures, contact pressures, contact time and kind of lubrication. The blow-and-blow forming simulation of a perfume bottle is finally performed to assess the special interface element performance.

Moreau, P.; Gregoire, S.; Lochegnies, D. [LAMIH UMR CNRS 8530, University of Valenciennes, Le Mont-Houy, 59313 Valenciennes Cedex 9 (France); Cesar de Sa, J. [DEMEGI, University of Porto, Rua Dr Roberto Frias, s/n 4200-465 Porto (Portugal)

2007-05-17

326

Towards an automated generation of device firmware components for intelligent field devices  

Microsoft Academic Search

This Paper introduces an approach to the automatic generation of parts of the firmware for intelligent field devices in distributed automation systems. For this purpose the modeling of information on communication interface and functionality of such a device using OWL ontologies is discussed. In a further step a concept for a system that generates an XMI-based UML notation of firmware

Christian Hahn; Andreas Gössling; Roman Frenzel; Martin Wollschlaeger

2009-01-01

327

A Hybrid Geometric–Statistical Deformable Model for Automated 3-D Segmentation in Brain MRI  

PubMed Central

We present a novel 3-D deformable model-based approach for accurate, robust, and automated tissue segmentation of brain MRI data of single as well as multiple magnetic resonance sequences. The main contribution of this study is that we employ an edge-based geodesic active contour for the segmentation task by integrating both image edge geometry and voxel statistical homogeneity into a novel hybrid geometric–statistical feature to regularize contour convergence and extract complex anatomical structures. We validate the accuracy of the segmentation results on simulated brain MRI scans of both single T1-weighted and multiple T1/T2/PD-weighted sequences. We also demonstrate the robustness of the proposed method when applied to clinical brain MRI scans. When compared to a current state-of-the-art region-based level-set segmentation formulation, our white matter and gray matter segmentation resulted in significantly higher accuracy levels with a mean improvement in Dice similarity indexes of 8.55% (p < 0.0001) and 10.18% (p < 0.0001), respectively. PMID:19336280

Abugharbieh, Rafeef; Tam, Roger

2010-01-01

328

Modeling and control of tissue compression and temperature for automation in robot-assisted surgery.  

PubMed

Robotic surgery is being used widely due to its various benefits that includes reduced patient trauma and increased dexterity and ergonomics for the operating surgeon. Making the whole or part of the surgical procedure autonomous increases patient safety and will enable the robotic surgery platform to be used in telesurgery. In this work, an Electrosurgery procedure that involves tissue compression and application of heat such as the coaptic vessel closure has been automated. A MIMO nonlinear model characterizing the tissue stiffness and conductance under compression was feedback linearized and tuned PID controllers were used to control the system to achieve both the displacement and temperature constraints. A reference input for both the constraints were chosen as a ramp and hold trajectory which reflect the real constraints that exist in an actual surgical procedure. Our simulations showed that the controllers successfully tracked the reference trajectories with minimal deviation and in finite time horizon. The MIMO system with controllers developed in this work can be used to drive a surgical robot autonomously and perform electrosurgical procedures such as coaptic vessel closures. PMID:25569973

Sinha, Utkarsh; Baichun Li; Sankaranarayanan, Ganesh

2014-08-01

329

Automated segmentation and geometrical modeling of the tricuspid aortic valve in 3D echocardiographic images  

PubMed Central

The aortic valve has been described with variable anatomical definitions, and the consistency of 2D manual measurement of valve dimensions in medical image data has been questionable. Given the importance of image-based morphological assessment in the diagnosis and surgical treatment of aortic valve disease, there is considerable need to develop a standardized framework for 3D valve segmentation and shape representation. Towards this goal, this work integrates template-based medial modeling and multi-atlas label fusion techniques to automatically delineate and quantitatively describe aortic leaflet geometry in 3D echocardiographic (3DE) images, a challenging task that has been explored only to a limited extent. The method makes use of expert knowledge of aortic leaflet image appearance, generates segmentations with consistent topology, and establishes a shape-based coordinate system on the aortic leaflets that enables standardized automated measurements. In this study, the algorithm is evaluated on 11 3DE images of normal human aortic leaflets acquired at mid systole. The clinical relevance of the method is its ability to capture leaflet geometry in 3DE image data with minimal user interaction while producing consistent measurements of 3D aortic leaflet geometry. PMID:24505702

Pouch, Alison M.; Wang, Hongzhi; Takabe, Manabu; Jackson, Benjamin M.; Sehgal, Chandra M.; Gorman, Joseph H.; Gorman, Robert C.; Yushkevich, Paul A.

2013-01-01

330

Automation based on knowledge modeling theory and its applications in engine diagnostic systems using Space Shuttle Main Engine vibrational data. M.S. Thesis  

NASA Technical Reports Server (NTRS)

Humans can perform many complicated tasks without explicit rules. This inherent and advantageous capability becomes a hurdle when a task is to be automated. Modern computers and numerical calculations require explicit rules and discrete numerical values. In order to bridge the gap between human knowledge and automating tools, a knowledge model is proposed. Knowledge modeling techniques are discussed and utilized to automate a labor and time intensive task of detecting anomalous bearing wear patterns in the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP).

Kim, Jonnathan H.

1995-01-01

331

Imaging Automation  

NASA Astrophysics Data System (ADS)

Multiple software programs, techniques, scripts, and related routines now exist to automate much of the work of taking, processing, analyzing, and extracting data from CCD Images. Five categories of such software programs are examined. The automation capability of Maxim DL and the ASCOM modules is demonstrated, together with specific examples of automation routines to control a telescope, take and process images.

Horne, J. D.

2007-05-01

332

Imaging Automation  

Microsoft Academic Search

Multiple software programs, techniques, scripts, and related routines now exist to automate much of the work of taking, processing, analyzing, and extracting data from CCD Images. Five categories of such software programs are examined. The automation capability of Maxim DL and the ASCOM modules is demonstrated, together with specific examples of automation routines to control a telescope, take and process

J. D. Horne

2007-01-01

333

Wall modeling for implicit large-eddy simulation and immersed-interface methods  

NASA Astrophysics Data System (ADS)

We propose and analyze a wall model based on the turbulent boundary layer equations (TBLE) for implicit large-eddy simulation (LES) of high Reynolds number wall-bounded flows in conjunction with a conservative immersed-interface method for mapping complex boundaries onto Cartesian meshes. Both implicit subgrid-scale model and immersed-interface treatment of boundaries offer high computational efficiency for complex flow configurations. The wall model operates directly on the Cartesian computational mesh without the need for a dual boundary-conforming mesh. The combination of wall model and implicit LES is investigated in detail for turbulent channel flow at friction Reynolds numbers from Re ? = 395 up to Re ? =100,000 on very coarse meshes. The TBLE wall model with implicit LES gives results of better quality than current explicit LES based on eddy viscosity subgrid-scale models with similar wall models. A straightforward formulation of the wall model performs well at moderately large Reynolds numbers. A logarithmic-layer mismatch, observed only at very large Reynolds numbers, is removed by introducing a new structure-based damping function. The performance of the overall approach is assessed for two generic configurations with flow separation: the backward-facing step at Re h = 5,000 and the periodic hill at Re H = 10,595 and Re H = 37,000 on very coarse meshes. The results confirm the observations made for the channel flow with respect to the good prediction quality and indicate that the combination of implicit LES, immersed-interface method, and TBLE-based wall modeling is a viable approach for simulating complex aerodynamic flows at high Reynolds numbers. They also reflect the limitations of TBLE-based wall models.

Chen, Zhen Li; Hickel, Stefan; Devesa, Antoine; Berland, Julien; Adams, Nikolaus A.

2014-02-01

334

Deterministic contact mechanics model applied to electrode interfaces in polymer electrolyte fuel cells and interfacial water accumulation  

NASA Astrophysics Data System (ADS)

An elastic deterministic contact mechanics model is applied to the compressed micro-porous (MPL) and catalyst layer (CL) interfaces in polymer electrolyte fuel cells (PEFCs) to elucidate the interfacial morphology. The model employs measured two-dimensional surface profiles and computes local surface deformation and interfacial gap, average contact resistance, and percent contact area as a function of compression pressure. Here, we apply the model to one interface having a MPL with cracks and one with a crack-free MPL. The void size distributions and water retention curves for the two sets of CL|MPL interfaces under compression are also computed. The CL|MPL interfaces with cracks are observed to have higher roughness, resulting in twice the interfacial average gap compared to the non-cracked interface at a given level of compression. The results indicate that the interfacial contact resistance is roughly the same for cracked or non-cracked interfaces due to cracks occupying low percentage of overall area. However, the cracked CL|MPL interface yields higher liquid saturation levels at all capillary pressures, resulting in an order of magnitude higher water storage capacity compared to the smooth interface. The van Genuchten water retention curve correlation for log-normal void size distributions is found to fit non-cracked CL|MPL interfaces well.

Zenyuk, I. V.; Kumbur, E. C.; Litster, S.

2013-11-01

335

Multiscale Modeling of Intergranular Fracture in Aluminum: Constitutive Relation For Interface Debonding  

NASA Technical Reports Server (NTRS)

Intergranular fracture is a dominant mode of failure in ultrafine grained materials. In the present study, the atomistic mechanisms of grain-boundary debonding during intergranular fracture in aluminum are modeled using a coupled molecular dynamics finite element simulation. Using a statistical mechanics approach, a cohesive-zone law in the form of a traction-displacement constitutive relationship, characterizing the load transfer across the plane of a growing edge crack, is extracted from atomistic simulations and then recast in a form suitable for inclusion within a continuum finite element model. The cohesive-zone law derived by the presented technique is free of finite size effects and is statistically representative for describing the interfacial debonding of a grain boundary (GB) interface examined at atomic length scales. By incorporating the cohesive-zone law in cohesive-zone finite elements, the debonding of a GB interface can be simulated in a coupled continuum-atomistic model, in which a crack starts in the continuum environment, smoothly penetrates the continuum-atomistic interface, and continues its propagation in the atomistic environment. This study is a step towards relating atomistically derived decohesion laws to macroscopic predictions of fracture and constructing multiscale models for nanocrystalline and ultrafine grained materials.

Yamakov, V.; Saether, E.; Glaessgen, E. H.

2008-01-01

336

Mixed-level optical-system simulation incorporating component-level modeling of interface elements  

NASA Astrophysics Data System (ADS)

While system-level simulation can allow designers to assess optical system performance via measures such as signal waveforms, spectra, eye diagrams, and BER calculations, component-level modeling can provide a more accurate description of coupling into and out of individual devices, as well as their detailed signal propagation characteristics. In particular, the system-level simulation of interface components used in optical systems, including splitters, combiners, grating couplers, waveguides, spot-size converters, and lens assemblies, can benefit from more detailed component-level modeling. Depending upon the nature of the device and the scale of the problem, simulation of optical transmission through these components can be carried out using either electromagnetic device-level simulation, such as the beampropagation method, or ray-based approaches. In either case, system-level simulation can interface to such componentlevel modeling via a suitable exchange of optical signal data. This paper presents the use of a mixed-level simulation flow in which both electromagnetic device-level and ray-based tools are integrated with a system-level simulation environment in order to model the use of various interface components in optical systems for a range of purposes, including, for example, coupling to and from optical transmission media such as single- and multimode optical fiber. This approach enables case studies on the impact of physical and geometric component variations on system performance, and the sensitivity of system behavior to misalignment between components.

Mena, Pablo V.; Stone, Bryan; Heller, Evan; Herrmann, Dan; Ghillino, Enrico; Scarmozzino, Rob

2014-03-01

337

Including nonequilibrium interface kinetics in a continuum model for melting nanoscaled particles  

NASA Astrophysics Data System (ADS)

The melting temperature of a nanoscaled particle is known to decrease as the curvature of the solid-melt interface increases. This relationship is most often modelled by a Gibbs-Thomson law, with the decrease in melting temperature proposed to be a product of the curvature of the solid-melt interface and the surface tension. Such a law must break down for sufficiently small particles, since the curvature becomes singular in the limit that the particle radius vanishes. Furthermore, the use of this law as a boundary condition for a Stefan-type continuum model is problematic because it leads to a physically unrealistic form of mathematical blow-up at a finite particle radius. By numerical simulation, we show that the inclusion of nonequilibrium interface kinetics in the Gibbs-Thomson law regularises the continuum model, so that the mathematical blow up is suppressed. As a result, the solution continues until complete melting, and the corresponding melting temperature remains finite for all time. The results of the adjusted model are consistent with experimental findings of abrupt melting of nanoscaled particles. This small-particle regime appears to be closely related to the problem of melting a superheated particle.

Back, Julian M.; McCue, Scott W.; Moroney, Timothy J.

2014-11-01

338

Including nonequilibrium interface kinetics in a continuum model for melting nanoscaled particles.  

PubMed

The melting temperature of a nanoscaled particle is known to decrease as the curvature of the solid-melt interface increases. This relationship is most often modelled by a Gibbs-Thomson law, with the decrease in melting temperature proposed to be a product of the curvature of the solid-melt interface and the surface tension. Such a law must break down for sufficiently small particles, since the curvature becomes singular in the limit that the particle radius vanishes. Furthermore, the use of this law as a boundary condition for a Stefan-type continuum model is problematic because it leads to a physically unrealistic form of mathematical blow-up at a finite particle radius. By numerical simulation, we show that the inclusion of nonequilibrium interface kinetics in the Gibbs-Thomson law regularises the continuum model, so that the mathematical blow up is suppressed. As a result, the solution continues until complete melting, and the corresponding melting temperature remains finite for all time. The results of the adjusted model are consistent with experimental findings of abrupt melting of nanoscaled particles. This small-particle regime appears to be closely related to the problem of melting a superheated particle. PMID:25399918

Back, Julian M; McCue, Scott W; Moroney, Timothy J

2014-01-01

339

A DIFFUSE-INTERFACE APPROACH FOR MODELING TRANSPORT, DIFFUSION AND ADSORPTION/DESORPTION OF MATERIAL QUANTITIES ON A DEFORMABLE INTERFACE*  

PubMed Central

A method is presented to solve two-phase problems involving a material quantity on an interface. The interface can be advected, stretched, and change topology, and material can be adsorbed to or desorbed from it. The method is based on the use of a diffuse interface framework, which allows a simple implementation using standard finite-difference or finite-element techniques. Here, finite-difference methods on a block-structured adaptive grid are used, and the resulting equations are solved using a non-linear multigrid method. Interfacial flow with soluble surfactants is used as an example of the application of the method, and several test cases are presented demonstrating its accuracy and convergence. PMID:21373370

Teigen, Knut Erik; Li, Xiangrong; Lowengrub, John; Wang, Fan; Voigt, Axel

2010-01-01

340

The DaveMLTranslator: An Interface for DAVE-ML Aerodynamic Models  

NASA Technical Reports Server (NTRS)

It can take weeks or months to incorporate a new aerodynamic model into a vehicle simulation and validate the performance of the model. The Dynamic Aerospace Vehicle Exchange Markup Language (DAVE-ML) has been proposed as a means to reduce the time required to accomplish this task by defining a standard format for typical components of a flight dynamic model. The purpose of this paper is to describe an object-oriented C++ implementation of a class that interfaces a vehicle subsystem model specified in DAVE-ML and a vehicle simulation. Using the DaveMLTranslator class, aerodynamic or other subsystem models can be automatically imported and verified at run-time, significantly reducing the elapsed time between receipt of a DAVE-ML model and its integration into a simulation environment. The translator performs variable initializations, data table lookups, and mathematical calculations for the aerodynamic build-up, and executes any embedded static check-cases for verification. The implementation is efficient, enabling real-time execution. Simple interface code for the model inputs and outputs is the only requirement to integrate the DaveMLTranslator as a vehicle aerodynamic model. The translator makes use of existing table-lookup utilities from the Langley Standard Real-Time Simulation in C++ (LaSRS++). The design and operation of the translator class is described and comparisons with existing, conventional, C++ aerodynamic models of the same vehicle are given.

Hill, Melissa A.; Jackson, E. Bruce

2007-01-01

341

Cockpit automation - In need of a philosophy  

NASA Technical Reports Server (NTRS)

Concern has been expressed over the rapid development and deployment of automatic devices in transport aircraft, due mainly to the human interface and particularly the role of automation in inducing human error. The paper discusses the need for coherent philosophies of automation, and proposes several approaches: (1) flight management by exception, which states that as long as a crew stays within the bounds of regulations, air traffic control and flight safety, it may fly as it sees fit; (2) exceptions by forecasting, where the use of forecasting models would predict boundary penetration, rather than waiting for it to happen; (3) goal-sharing, where a computer is informed of overall goals, and subsequently has the capability of checking inputs and aircraft position for consistency with the overall goal or intentions; and (4) artificial intelligence and expert systems, where intelligent machines could mimic human reason.

Wiener, E. L.

1985-01-01

342

Web Navigation Sequences Automation in Modern Websites  

NASA Astrophysics Data System (ADS)

Most today’s web sources are designed to be used by humans, but they do not provide suitable interfaces for software programs. That is why a growing interest has arisen in so-called web automation applications that are widely used for different purposes such as B2B integration, automated testing of web applications or technology and business watch. Previous proposals assume models for generating and reproducing navigation sequences that are not able to correctly deal with new websites using technologies such as AJAX: on one hand existing systems only allow recording simple navigation actions and, on the other hand, they are unable to detect the end of the effects caused by an user action. In this paper, we propose a set of new techniques to record and execute web navigation sequences able to deal with all the complexity existing in AJAX-based web sites. We also present an exhaustive evaluation of the proposed techniques that shows very promising results.

Montoto, Paula; Pan, Alberto; Raposo, Juan; Bellas, Fernando; López, Javier

343

Object-Based Integration of Photogrammetric and LiDAR Data for Automated Generation of Complex Polyhedral Building Models  

PubMed Central

This research is concerned with a methodology for automated generation of polyhedral building models for complex structures, whose rooftops are bounded by straight lines. The process starts by utilizing LiDAR data for building hypothesis generation and derivation of individual planar patches constituting building rooftops. Initial boundaries of these patches are then refined through the integration of LiDAR and photogrammetric data and hierarchical processing of the planar patches. Building models for complex structures are finally produced using the refined boundaries. The performance of the developed methodology is evaluated through qualitative and quantitative analysis of the generated building models from real data. PMID:22346722

Kim, Changjae; Habib, Ayman

2009-01-01

344

Automated quantification of carotid artery stenosis on contrast-enhanced MRA data using a deformable vascular tube model.  

PubMed

The purpose of this study was to develop and validate a method for automated segmentation of the carotid artery lumen from volumetric MR Angiographic (MRA) images using a deformable tubular 3D Non-Uniform Rational B-Splines (NURBS) model. A flexible 3D tubular NURBS model was designed to delineate the carotid arterial lumen. User interaction was allowed to guide the model by placement of forbidden areas. Contrast-enhanced MRA (CE-MRA) from 21 patients with carotid atherosclerotic disease were included in this study. The validation was performed against expert drawn contours on multi-planar reformatted image slices perpendicular to the artery. Excellent linear correlations were found on cross-sectional area measurement (r = 0.98, P < 0.05) and on luminal diameter (r = 0.98, P < 0.05). Strong match in terms of the Dice similarity indices were achieved: 0.95 ± 0.02 (common carotid artery), 0.90 ± 0.07 (internal carotid artery), 0.87 ± 0.07 (external carotid artery), 0.88 ± 0.09 (carotid bifurcation) and 0.75 ± 0.20 (stenosed segments). Slight overestimation of stenosis grading by the automated method was observed. The mean differences was 7.20% (SD = 21.00%) and 5.2% (SD = 21.96%) when validated against two observers. Reproducibility in stenosis grade calculation by the automated method was high; the mean difference between two repeated analyses was 1.9 ± 7.3%. In conclusion, the automated method shows high potential for clinical application in the analysis of CE-MRA of carotid arteries. PMID:22160666

Suinesiaputra, Avan; de Koning, Patrick J H; Zudilova-Seinstra, Elena; Reiber, Johan H C; van der Geest, Rob J

2012-08-01

345

Evaluation of automated statistical shape model based knee kinematics from biplane fluoroscopy  

PubMed Central

State-of-the-art fluoroscopic knee kinematic analysis methods require the patient-specific bone shapes segmented from CT or MRI. Substituting the patient-specific bone shapes with personalizable models, such as statistical shape models (SSM), could eliminate the CT/MRI acquisitions, and thereby decrease costs and radiation dose (when eliminating CT). SSM based kinematics, however, have not yet been evaluated on clinically relevant joint motion parameters. Therefore, in this work the applicability of SSM-s for computing knee kinematics from biplane fluoroscopic sequences was explored. Kinematic precision with an edge based automated bone tracking method using SSM-s was evaluated on 6 cadaver and 10 in-vivo fluoroscopic sequences. The SSMs of the femur and the tibia-fibula were created using 61 training datasets. Kinematic precision was determined for medial-lateral tibial shift, anterior-posterior tibial drawer, joint distraction-contraction, flexion, tibial rotation and adduction. The relationship between kinematic precision and bone shape accuracy was also investigated. The SSM based kinematics resulted in sub-millimeter (0.48–0.81 mm) and approximately one degree (0.69–0.99°) median precision on the cadaveric knees compared to bone-marker-based kinematics. The precision on the in-vivo datasets was comparable to the cadaveric sequences when evaluated with a semi-automatic reference method. These results are promising, though further work is necessary to reach the accuracy of CT-based kinematics. We also demonstrated that a better shape reconstruction accuracy does not automatically imply a better kinematic precision. This result suggests that the ability of accurately fitting the edges in the fluoroscopic sequences has a larger role in determining the kinematic precision than the overall 3D shape accuracy. PMID:24207131

Baka, Nora; Kaptein, Bart L.; Giphart, J. Erik; Staring, Marius; de Bruijne, Marleen; Lelieveldt, Boudewijn P.F.; Valstar, Edward

2014-01-01

346

Continental hydrosystem modelling: the concept of nested stream-aquifer interfaces  

NASA Astrophysics Data System (ADS)

Coupled hydrological-hydrogeological models, emphasising the importance of the stream-aquifer interface, are more and more used in hydrological sciences for pluri-disciplinary studies aiming at investigating environmental issues. Based on an extensive literature review, stream-aquifer interfaces are described at five different scales: local [10 cm-~10 m], intermediate [~10 m-~1 km], watershed [10 km2-~1000 km2], regional [10 000 km2-~1 M km2] and continental scales [>10 M km2]. This led us to develop the concept of nested stream-aquifer interfaces, which extends the well-known vision of nested groundwater pathways towards the surface, where the mixing of low frequency processes and high frequency processes coupled with the complexity of geomorphological features and heterogeneities creates hydrological spiralling. This conceptual framework allows the identification of a hierarchical order of the multi-scale control factors of stream-aquifer hydrological exchanges, from the larger scale to the finer scale. The hyporheic corridor, which couples the river to its 3-D hyporheic zone, is then identified as the key component for scaling hydrological processes occurring at the interface. The identification of the hyporheic corridor as the support of the hydrological processes scaling is an important step for the development of regional studies, which is one of the main concerns for water practitioners and resources managers. In a second part, the modelling of the stream-aquifer interface at various scales is investigated with the help of the conductance model. Although the usage of the temperature as a tracer of the flow is a robust method for the assessment of stream-aquifer exchanges at the local scale, there is a crucial need to develop innovative methodologies for assessing stream-aquifer exchanges at the regional scale. After formulating the conductance model at the regional and intermediate scales, we address this challenging issue with the development of an iterative modelling methodology, which ensures the consistency of stream-aquifer exchanges between the intermediate and regional scales. Finally, practical recommendations are provided for the study of the interface using the innovative methodology MIM (Measurements-Interpolation-Modelling), which is graphically developed, scaling in space the three pools of methods needed to fully understand stream-aquifer interfaces at various scales. In the MIM space, stream-aquifer interfaces that can be studied by a given approach are localised. The efficiency of the method is demonstrated with two examples. The first one proposes an upscaling framework, structured around river reaches of ~10-100 m, from the local to the watershed scale. The second example highlights the usefulness of space borne data to improve the assessment of stream-aquifer exchanges at the regional and continental scales. We conclude that further developments in modelling and field measurements have to be undertaken at the regional scale to enable a proper modelling of stream-aquifer exchanges from the local to the continental scale.

Flipo, N.; Mouhri, A.; Labarthe, B.; Biancamaria, S.; Rivière, A.; Weill, P.

2014-08-01

347

Modeling of ultrasound transmission through a solid-liquid interface comprising a network of gas pockets  

NASA Astrophysics Data System (ADS)

Ultrasonic inspection of sodium-cooled fast reactor requires a good acoustic coupling between the transducer and the liquid sodium. Ultrasonic transmission through a solid surface in contact with liquid sodium can be complex due to the presence of microscopic gas pockets entrapped by the surface roughness. Experiments are run using substrates with controlled roughness consisting of a network of holes and a modeling approach is then developed. In this model, a gas pocket stiffness at a partially solid-liquid interface is defined. This stiffness is then used to calculate the transmission coefficient of ultrasound at the entire interface. The gas pocket stiffness has a static, as well as an inertial component, which depends on the ultrasonic frequency and the radiative mass.

Paumel, K.; Moysan, J.; Chatain, D.; Corneloup, G.; Baqué, F.

2011-08-01

348

Modelling of the ultrasonic field by the angular spectrum method in presence of interface.  

PubMed

We present a numerical modelling of the harmonic sound in two isotropic media, one liquid and the other solid separated by a plane interface. This numerical modelling is carried out by the angular spectrum method. This latter is applied to calculate the displacement potential generated by a rectangular transducer with a Gaussian profile and with an uniform profile. The rigorous modelling of the field needed to find the optimal parameters of the decomposition according to the transducer aperture and the ultrasonic wave frequency. PMID:12159951

Belgroune, D; de Belleval, J F; Djelouah, H

2002-05-01

349

Ergonomic Models of Anthropometry, Human Biomechanics and Operator-Equipment Interfaces  

NASA Technical Reports Server (NTRS)

The Committee on Human Factors was established in October 1980 by the Commission on Behavioral and Social Sciences and Education of the National Research Council. The committee is sponsored by the Office of Naval Research, the Air Force Office of Scientific Research, the Army Research Institute for the Behavioral and Social Sciences, the National Aeronautics and Space Administration, and the National Science Foundation. The workshop discussed the following: anthropometric models; biomechanical models; human-machine interface models; and research recommendations. A 17-page bibliography is included.

Kroemer, Karl H. E. (editor); Snook, Stover H. (editor); Meadows, Susan K. (editor); Deutsch, Stanley (editor)

1988-01-01

350

Rigorous interpolation near tilted interfaces in 3-D finite-difference EM modelling  

NASA Astrophysics Data System (ADS)

We present a rigorous method for interpolation of electric and magnetic fields close to an interface with a conductivity contrast. The method takes into account not only a well-known discontinuity in the normal electric field, but also discontinuity in all the normal derivatives of electric and magnetic tangential fields. The proposed method is applied to marine 3-D controlled-source electromagnetic modelling (CSEM) where sources and receivers are located close to the seafloor separating conductive seawater and resistive formation. For the finite-difference scheme based on the Yee grid, the new interpolation is demonstrated to be much more accurate than alternative methods (interpolation using nodes on one side of the interface or interpolation using nodes on both sides, but ignoring the derivative jumps). The rigorous interpolation can handle arbitrary orientation of interface with respect to the grid, which is demonstrated on a marine CSEM example with a dipping seafloor. The interpolation coefficients are computed by minimizing a misfit between values at the nearest nodes and linear expansions of the continuous field components in the coordinate system aligned with the interface. The proposed interpolation operators can handle either uniform or non-uniform grids and can be applied to interpolation for both sources and receivers.

Shantsev, Daniil V.; Maaø, Frank A.

2015-02-01

351

A study of the ice-water interface using the TIP4P/2005 water model  

E-print Network

In this work we study the ice-water interface under coexistence conditions by means of molecular simulations using the TIP4P/2005 water model. Following the methodology proposed by Hoyt and co-workers [J. J. Hoyt, M. Asta and A. Karma, Phys. Rev. Lett., 86, 5530, (2001)] we measure the interfacial free energy of ice with liquid water by analysing the spectrum of capillary fluctuations of the interface. We get an orientationally averaged interfacial free energy of 27(2) mN/m, in good agreement with a recent estimate obtained from simulation data of the size of critical clusters [E. Sanz, C. Vega, J. R. Espinosa, R. Caballero-Bernal, J. L. F. Abascal and C. Valeriani, JACS, 135, 15008, (2013)]. We also estimate the interfacial free energy of different planes and obtain 27(2), 28(2)and 28(2) mN/m for the basal, the primary prismatic and the secondary prismatic planes respectively. Finally, we inspect the structure of the interface and find that its thickness is of approximately 4-5 molecular diameters. Moreover, we find that when the basal plane is exposed to the fluid the interface alternates regions of cubic ice with regions of hexagonal ice.

Jorge Benet; Luis G. MacDowell; Eduardo Sanz

2014-10-01

352

Diffuse interface model for compressible fluid - Compressible elastic-plastic solid interaction  

NASA Astrophysics Data System (ADS)

An Eulerian hyperbolic diffuse interface model for elastic-plastic solid-fluid interaction is constructed. The system of governing equations couples Euler equations of compressible fluids and a visco-plastic model of Maxwell type materials (the deviatoric part of the stress tensor decreases during plastic deformations) in the same manner as models of multicomponent fluids. In particular, the model is able to create interfaces which were not present initially. The model is thermodynamically compatible: it verifies the entropy inequality. However, a numerical treatment of the model is particularly challenging. Indeed, the model is non-conservative, so a special numerical splitting is proposed to overcome this difficulty. The numerical algorithm contains two relaxation procedures. One of them is physical and is related to the plastic relaxation mechanism (relaxation toward the yield surface). The second one is numerical. It consists in replacing the algebraic equation expressing a mechanical equilibrium between components by a partial differential equation with a short relaxation time. The numerical method was tested in 1D case (Wilkins' flying plate problem), 2D plane case (impact of a projectile on a plate) and axisymmetrical case (Taylor test problem, impact with penetration effects, etc.). Numerical examples show the ability of the model to deal with real physical phenomena.

Favrie, N.; Gavrilyuk, S. L.

2012-04-01

353

Degenerate Ising model for atomistic simulation of crystal-melt interfaces  

SciTech Connect

One of the simplest microscopic models for a thermally driven first-order phase transition is an Ising-type lattice system with nearest-neighbour interactions, an external field, and a degeneracy parameter. The underlying lattice and the interaction coupling constant control the anisotropic energy of the phase boundary, the field strength represents the bulk latent heat, and the degeneracy quantifies the difference in communal entropy between the two phases. We simulate the (stochastic) evolution of this minimal model by applying rejection-free canonical and microcanonical Monte Carlo algorithms, and we obtain caloric curves and heat capacity plots for square (2D) and face-centred cubic (3D) lattices with periodic boundary conditions. Since the model admits precise adjustment of bulk latent heat and communal entropy, neither of which affect the interface properties, we are able to tune the crystal nucleation barriers at a fixed degree of undercooling and verify a dimension-dependent scaling expected from classical nucleation theory. We also analyse the equilibrium crystal-melt coexistence in the microcanonical ensemble, where we detect negative heat capacities and find that this phenomenon is more pronounced when the interface is the dominant contributor to the total entropy. The negative branch of the heat capacity appears smooth only when the equilibrium interface-area-to-volume ratio is not constant but varies smoothly with the excitation energy. Finally, we simulate microcanonical crystal nucleation and subsequent relaxation to an equilibrium Wulff shape, demonstrating the model's utility in tracking crystal-melt interfaces at the atomistic level.

Schebarchov, D., E-mail: Dmitri.Schebarchov@gmail.com [University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Schulze, T. P., E-mail: schulze@math.utk.edu [Department of Mathematics, University of Tennessee, Knoxville, Tennessee 37996-1300 (United States); Hendy, S. C. [The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand) [The MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140 (New Zealand); Department of Physics, University of Auckland, Auckland 1010 (New Zealand)

2014-02-21

354

Degenerate Ising model for atomistic simulation of crystal-melt interfaces  

NASA Astrophysics Data System (ADS)

One of the simplest microscopic models for a thermally driven first-order phase transition is an Ising-type lattice system with nearest-neighbour interactions, an external field, and a degeneracy parameter. The underlying lattice and the interaction coupling constant control the anisotropic energy of the phase boundary, the field strength represents the bulk latent heat, and the degeneracy quantifies the difference in communal entropy between the two phases. We simulate the (stochastic) evolution of this minimal model by applying rejection-free canonical and microcanonical Monte Carlo algorithms, and we obtain caloric curves and heat capacity plots for square (2D) and face-centred cubic (3D) lattices with periodic boundary conditions. Since the model admits precise adjustment of bulk latent heat and communal entropy, neither of which affect the interface properties, we are able to tune the crystal nucleation barriers at a fixed degree of undercooling and verify a dimension-dependent scaling expected from classical nucleation theory. We also analyse the equilibrium crystal-melt coexistence in the microcanonical ensemble, where we detect negative heat capacities and find that this phenomenon is more pronounced when the interface is the dominant contributor to the total entropy. The negative branch of the heat capacity appears smooth only when the equilibrium interface-area-to-volume ratio is not constant but varies smoothly with the excitation energy. Finally, we simulate microcanonical crystal nucleation and subsequent relaxation to an equilibrium Wulff shape, demonstrating the model's utility in tracking crystal-melt interfaces at the atomistic level.

Schebarchov, D.; Schulze, T. P.; Hendy, S. C.

2014-02-01

355

Atomic scale model interfaces between high- k hafnium silicates and silicon  

Microsoft Academic Search

Hafnium silicates (HfySi1-yO2) are being considered as high- k gate dielectrics in field-effect transistors as a compromise between high permittivity and thermal stability on silicon during complementary metal-oxide-semiconductor processing. Using hafnon (HfSiO4) as a prototypical hafnium silicate, we have explored model abrupt interfaces at the atomic scale, employing various hafnon surfaces on Si(100) and Si(110) via a silicon suboxide interfacial

S. Monaghan; J. C. Greer; S. D. Elliott

2007-01-01

356

Reduction of nonlinear embedded boundary models for problems with evolving interfaces  

NASA Astrophysics Data System (ADS)

Embedded boundary methods alleviate many computational challenges, including those associated with meshing complex geometries and solving problems with evolving domains and interfaces. Developing model reduction methods for computational frameworks based on such methods seems however to be challenging. Indeed, most popular model reduction techniques are projection-based, and rely on basis functions obtained from the compression of simulation snapshots. In a traditional interface-fitted computational framework, the computation of such basis functions is straightforward, primarily because the computational domain does not contain in this case a fictitious region. This is not the case however for an embedded computational framework because the computational domain typically contains in this case both real and ghost regions whose definitions complicate the collection and compression of simulation snapshots. The problem is exacerbated when the interface separating both regions evolves in time. This paper addresses this issue by formulating the snapshot compression problem as a weighted low-rank approximation problem where the binary weighting identifies the evolving component of the individual simulation snapshots. The proposed approach is application independent and therefore comprehensive. It is successfully demonstrated for the model reduction of several two-dimensional, vortex-dominated, fluid-structure interaction problems.

Balajewicz, Maciej; Farhat, Charbel

2014-10-01

357

Automation for System Safety Analysis  

NASA Technical Reports Server (NTRS)

This presentation describes work to integrate a set of tools to support early model-based analysis of failures and hazards due to system-software interactions. The tools perform and assist analysts in the following tasks: 1) extract model parts from text for architecture and safety/hazard models; 2) combine the parts with library information to develop the models for visualization and analysis; 3) perform graph analysis and simulation to identify and evaluate possible paths from hazard sources to vulnerable entities and functions, in nominal and anomalous system-software configurations and scenarios; and 4) identify resulting candidate scenarios for software integration testing. There has been significant technical progress in model extraction from Orion program text sources, architecture model derivation (components and connections) and documentation of extraction sources. Models have been derived from Internal Interface Requirements Documents (IIRDs) and FMEA documents. Linguistic text processing is used to extract model parts and relationships, and the Aerospace Ontology also aids automated model development from the extracted information. Visualizations of these models assist analysts in requirements overview and in checking consistency and completeness.

Malin, Jane T.; Fleming, Land; Throop, David; Thronesbery, Carroll; Flores, Joshua; Bennett, Ted; Wennberg, Paul

2009-01-01

358

A novel automated behavioral test battery assessing cognitive rigidity in two genetic mouse models of autism  

PubMed Central

Repetitive behaviors are a key feature of many pervasive developmental disorders, such as autism. As a heterogeneous group of symptoms, repetitive behaviors are conceptualized into two main subgroups: sensory/motor (lower-order) and cognitive rigidity (higher-order). Although lower-order repetitive behaviors are measured in mouse models in several paradigms, so far there have been no high-throughput tests directly measuring cognitive rigidity. We describe a novel approach for monitoring repetitive behaviors during reversal learning in mice in the automated IntelliCage system. During the reward-motivated place preference reversal learning, designed to assess cognitive abilities of mice, visits to the previously rewarded places were recorded to measure cognitive flexibility. Thereafter, emotional flexibility was assessed by measuring conditioned fear extinction. Additionally, to look for neuronal correlates of cognitive impairments, we measured CA3-CA1 hippocampal long term potentiation (LTP). To standardize the designed tests we used C57BL/6 and BALB/c mice, representing two genetic backgrounds, for induction of autism by prenatal exposure to the sodium valproate. We found impairments of place learning related to perseveration and no LTP impairments in C57BL/6 valproate-treated mice. In contrast, BALB/c valproate-treated mice displayed severe deficits of place learning not associated with perseverative behaviors and accompanied by hippocampal LTP impairments. Alterations of cognitive flexibility observed in C57BL/6 valproate-treated mice were related to neither restricted exploration pattern nor to emotional flexibility. Altogether, we showed that the designed tests of cognitive performance and perseverative behaviors are efficient and highly replicable. Moreover, the results suggest that genetic background is crucial for the behavioral effects of prenatal valproate treatment. PMID:24808839

Pu?cian, Alicja; ??ski, Szymon; Górkiewicz, Tomasz; Meyza, Ksenia; Lipp, Hans-Peter; Knapska, Ewelina

2014-01-01

359

MIQuant – Semi-Automation of Infarct Size Assessment in Models of Cardiac Ischemic Injury  

PubMed Central

Background The cardiac regenerative potential of newly developed therapies is traditionally evaluated in rodent models of surgically induced myocardial ischemia. A generally accepted key parameter for determining the success of the applied therapy is the infarct size. Although regarded as a gold standard method for infarct size estimation in heart ischemia, histological planimetry is time-consuming and highly variable amongst studies. The purpose of this work is to contribute towards the standardization and simplification of infarct size assessment by providing free access to a novel semi-automated software tool. The acronym MIQuant was attributed to this application. Methodology/Principal Findings Mice were subject to permanent coronary artery ligation and the size of chronic infarcts was estimated by area and midline-length methods using manual planimetry and with MIQuant. Repeatability and reproducibility of MIQuant scores were verified. The validation showed high correlation (rmidline length?=?0.981; rarea?=?0.970 ) and agreement (Bland-Altman analysis), free from bias for midline length and negligible bias of 1.21% to 3.72% for area quantification. Further analysis demonstrated that MIQuant reduced by 4.5-fold the time spent on the analysis and, importantly, MIQuant effectiveness is independent of user proficiency. The results indicate that MIQuant can be regarded as a better alternative to manual measurement. Conclusions We conclude that MIQuant is a reliable and an easy-to-use software for infarct size quantification. The widespread use of MIQuant will contribute towards the standardization of infarct size assessment across studies and, therefore, to the systematization of the evaluation of cardiac regenerative potential of emerging therapies. PMID:21980376

Esteves, Tiago; de Pina, Maria de Fátima; Guedes, Joana G.; Freire, Ana; Quelhas, Pedro; Pinto-do-Ó, Perpétua

2011-01-01

360

ISMARA: automated modeling of genomic signals as a democracy of regulatory motifs  

PubMed Central

Accurate reconstruction of the regulatory networks that control gene expression is one of the key current challenges in molecular biology. Although gene expression and chromatin state dynamics are ultimately encoded by constellations of binding sites recognized by regulators such as transcriptions factors (TFs) and microRNAs (miRNAs), our understanding of this regulatory code and its context-dependent read-out remains very limited. Given that there are thousands of potential regulators in mammals, it is not practical to use direct experimentation to identify which of these play a key role for a particular system of interest. We developed a methodology that models gene expression or chromatin modifications in terms of genome-wide predictions of regulatory sites and completely automated it into a web-based tool called ISMARA (Integrated System for Motif Activity Response Analysis). Given only gene expression or chromatin state data across a set of samples as input, ISMARA identifies the key TFs and miRNAs driving expression/chromatin changes and makes detailed predictions regarding their regulatory roles. These include predicted activities of the regulators across the samples, their genome-wide targets, enriched gene categories among the targets, and direct interactions between the regulators. Applying ISMARA to data sets from well-studied systems, we show that it consistently identifies known key regulators ab initio. We also present a number of novel predictions including regulatory interactions in innate immunity, a master regulator of mucociliary differentiation, TFs consistently disregulated in cancer, and TFs that mediate specific chromatin modifications. PMID:24515121

Balwierz, Piotr J.; Pachkov, Mikhail; Arnold, Phil; Gruber, Andreas J.; Zavolan, Mihaela; van Nimwegen, Erik

2014-01-01

361

Interface Generation and Compositional Verification in JavaPathfinder  

NASA Technical Reports Server (NTRS)

We present a novel algorithm for interface generation of software components. Given a component, our algorithm uses learning techniques to compute a permissive interface representing legal usage of the component. Unlike our previous work, this algorithm does not require knowledge about the component s environment. Furthermore, in contrast to other related approaches, our algorithm computes permissive interfaces even in the presence of non-determinism in the component. Our algorithm is implemented in the JavaPathfinder model checking framework for UML statechart components. We have also added support for automated assume-guarantee style compositional verification in JavaPathfinder, using component interfaces. We report on the application of the presented approach to the generation of interfaces for flight software components.

Giannakopoulou, Dimitra; Pasareanu, Corina

2009-01-01

362

Using the ARTMO toolbox for automated retrieval of biophysical parameters through radiative transfer model inversion: Optimizing LUT-based inversion  

NASA Astrophysics Data System (ADS)

Radiative transfer (RT) modeling plays a key role for earth observation (EO) because it is needed to design EO instruments and to develop and test inversion algorithms. The inversion of a RT model is considered as a successful approach for the retrieval of biophysical parameters because of being physically-based and generally applicable. However, to the broader community this approach is considered as laborious because of its many processing steps and expert knowledge is required to realize precise model parameterization. We have recently developed a radiative transfer toolbox ARTMO (Automated Radiative Transfer Models Operator) with the purpose of providing in a graphical user interface (GUI) essential models and tools required for terrestrial EO applications such as model inversion. In short, the toolbox allows the user: i) to choose between various plant leaf and canopy RT models (e.g. models from the PROSPECT and SAIL family, FLIGHT), ii) to choose between spectral band settings of various air- and space-borne sensors or defining own sensor settings, iii) to simulate a massive amount of spectra based on a look up table (LUT) approach and storing it in a relational database, iv) to plot spectra of multiple models and compare them with measured spectra, and finally, v) to run model inversion against optical imagery given several cost options and accuracy estimates. In this work ARTMO was used to tackle some well-known problems related to model inversion. According to Hadamard conditions, mathematical models of physical phenomena are mathematically invertible if the solution of the inverse problem to be solved exists, is unique and depends continuously on data. This assumption is not always met because of the large number of unknowns and different strategies have been proposed to overcome this problem. Several of these strategies have been implemented in ARTMO and were here analyzed to optimize the inversion performance. Data came from the SPARC-2003 dataset, which was acquired on the agricultural test site Barrax, Spain. LUTs were created using the 4SAIL and FLIGHT models and were inverted against CHRIS data in order to retrieve maps of chlorophyll content (chl) and leaf area index (LAI). The following inversion steps have been optimized: 1. Cost function. The performances of about 50 different cost functions (i.e. minimum distance functions) were compared. Remarkably, in none of the studied cases the widely used root mean square error (RMSE) led to most accurate results. Depending on the retrieved parameter, more successful functions were: 'Sharma and Mittal', 'Shanno?s entropy', 'Hellinger distance', 'Pearso?s chi-square'. 2. Gaussian noise. Earth observation data typically encompass a certain degree of noise due to errors related to radiometric and geometric processing. In all cases, adding 5% Gaussian noise to the simulated spectra led to more accurate retrievals as compared to without noise. 3. Average of multiple best solutions. Because multiple parameter combinations may lead to the same spectra, a way to overcome this problem is not searching for the top best match but for a percentage of best matches. Optimized retrievals were encountered when including an average of 7% (Chl) to 10% (LAI) top best matches. 4. Integration of estimates. The option is provided to integrate estimates of biochemical contents at the canopy level (e.g., total chlorophyll: Chl × LAI, or water: Cw × LAI), which can lead to increased robustness and accuracy. 5. Class-based inversion. This option is probably ARTMÓs most powerful feature as it allows model parameterization depending on the imagés land cover classes (e.g. different soil or vegetation types). Class-based inversion can lead to considerably improved accuracies compared to one generic class. Results suggest that 4SAIL and FLIGHT performed alike for Chl but not for LAI. While both models rely on the leaf model PROSPECT for Chl retrieval, their different nature (e.g. numerical vs. ray tracing) may cause that retrieval of structural parameters such as LAI differ. Finally, i

Verrelst, J.; Rivera, J. P.; Leonenko, G.; Alonso, L.; Moreno, J.

2012-04-01

363

International Journal of Industrial Ergonomics 36 (2006) 511526 A dynamic model of interaction between reliance on automation and  

E-print Network

between reliance on automation and cooperation in multi-operator multi-automation situations Ji Gaoa of Iowa, S210 John Pappajohn Business Building, Iowa City, IA 52242, USA Available online 15 March 2006 elements of automation. The success of such multi-operator multi-automation systems depends not only

Lee, John D.

364

Evidence evaluation in fingerprint comparison and automated fingerprint identification systems--modelling within finger variability.  

PubMed

Recent challenges and errors in fingerprint identification have highlighted the need for assessing the information content of a papillary pattern in a systematic way. In particular, estimation of the statistical uncertainty associated with this type of evidence is more and more called upon. The approach used in the present study is based on the assessment of likelihood ratios (LRs). This evaluative tool weighs the likelihood of evidence given two mutually exclusive hypotheses. The computation of likelihood ratios on a database of marks of known sources (matching the unknown and non-matching the unknown mark) allows an estimation of the evidential contribution of fingerprint evidence. LRs are computed taking advantage of the scores obtained from an automated fingerprint identification system and hence are based exclusively on level II features (minutiae). The AFIS system attributes a score to any comparison (fingerprint to fingerprint, mark to mark and mark to fingerprint), used here as a proximity measure between the respective arrangements of minutiae. The numerator of the LR addresses the within finger variability and is obtained by comparing the same configurations of minutiae coming from the same source. Only comparisons where the same minutiae are visible both on the mark and on the print are therefore taken into account. The denominator of the LR is obtained by cross-comparison with a database of prints originating from non-matching sources. The estimation of the numerator of the LR is much more complex in terms of specific data requirements than the estimation of the denominator of the LR (that requires only a large database of prints from an non-associated population). Hence this paper addresses specific issues associated with the numerator or within finger variability. This study aims at answering the following questions: (1) how a database for modelling within finger variability should be acquired; (2) whether or not the visualisation technique or the choice of different minutiae arrangements may influence that modelling and (3) what is the magnitude of LRs that can be expected from such a model. Results show that within finger variability is affected by the visualisation technique used on the mark, the number of minutiae and the minutiae configuration. They also show that the rates of misleading evidence in the likelihood ratios obtained for one of the configurations examined are low. PMID:16914278

Egli, Nicole M; Champod, Christophe; Margot, Pierre

2007-04-11

365

Configuring a Graphical User Interface for Managing Local HYSPLIT Model Runs Through AWIPS  

NASA Technical Reports Server (NTRS)

Responding to incidents involving the release of harmful airborne pollutants is a continual challenge for Weather Forecast Offices in the National Weather Service. When such incidents occur, current protocol recommends forecaster-initiated requests of NOAA's Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model output through the National Centers of Environmental Prediction to obtain critical dispersion guidance. Individual requests are submitted manually through a secured web site, with desired multiple requests submitted in sequence, for the purpose of obtaining useful trajectory and concentration forecasts associated with the significant release of harmful chemical gases, radiation, wildfire smoke, etc., into local the atmosphere. To help manage the local HYSPLIT for both routine and emergency use, a graphical user interface was designed for operational efficiency. The interface allows forecasters to quickly determine the current HYSPLIT configuration for the list of predefined sites (e.g., fixed sites and floating sites), and to make any necessary adjustments to key parameters such as Input Model. Number of Forecast Hours, etc. When using the interface, forecasters will obtain desired output more confidently and without the danger of corrupting essential configuration files.

Wheeler, mark M.; Blottman, Peter F.; Sharp, David W.; Hoeth, Brian; VanSpeybroeck, Kurt M.

2009-01-01

366

Parametric links among Monte Carlo, phase-field, and sharp-interface models of interfacial motion  

NASA Astrophysics Data System (ADS)

Parametric links are made among three mesoscale simulation paradigms: phase-field, sharp-interface, and Monte Carlo. A two-dimensional, square lattice, 1/2 Ising model is considered for the Monte Carlo method, where an exact solution for the interfacial free energy is known. The Monte Carlo mobility is calibrated as a function of temperature using Glauber kinetics. A standard asymptotic analysis relates the phase-field and sharp-interface parameters, and this allows the phase-field and Monte Carlo parameters to be linked. The result is derived without bulk effects but is then applied to a set of simulations with the bulk driving force included. An error analysis identifies the domain over which the parametric relationships are accurate.

Liu, Pu; Lusk, Mark T.

2002-12-01

367

Work Practice Simulation of Complex Human-Automation Systems in Safety Critical Situations: The Brahms Generalized berlingen Model  

NASA Technical Reports Server (NTRS)

The transition from the current air traffic system to the next generation air traffic system will require the introduction of new automated systems, including transferring some functions from air traffic controllers to on­-board automation. This report describes a new design verification and validation (V&V) methodology for assessing aviation safety. The approach involves a detailed computer simulation of work practices that includes people interacting with flight-critical systems. The research is part of an effort to develop new modeling and verification methodologies that can assess the safety of flight-critical systems, system configurations, and operational concepts. The 2002 Ueberlingen mid-air collision was chosen for analysis and modeling because one of the main causes of the accident was one crew's response to a conflict between the instructions of the air traffic controller and the instructions of TCAS, an automated Traffic Alert and Collision Avoidance System on-board warning system. It thus furnishes an example of the problem of authority versus autonomy. It provides a starting point for exploring authority/autonomy conflict in the larger system of organization, tools, and practices in which the participants' moment-by-moment actions take place. We have developed a general air traffic system model (not a specific simulation of Überlingen events), called the Brahms Generalized Ueberlingen Model (Brahms-GUeM). Brahms is a multi-agent simulation system that models people, tools, facilities/vehicles, and geography to simulate the current air transportation system as a collection of distributed, interactive subsystems (e.g., airports, air-traffic control towers and personnel, aircraft, automated flight systems and air-traffic tools, instruments, crew). Brahms-GUeM can be configured in different ways, called scenarios, such that anomalous events that contributed to the Überlingen accident can be modeled as functioning according to requirements or in an anomalous condition, as occurred during the accident. Brahms-GUeM thus implicitly defines a class of scenarios, which include as an instance what occurred at Überlingen. Brahms-GUeM is a modeling framework enabling "what if" analysis of alternative work system configurations and thus facilitating design of alternative operations concepts. It enables subsequent adaption (reusing simulation components) for modeling and simulating NextGen scenarios. This project demonstrates that BRAHMS provides the capacity to model the complexity of air transportation systems, going beyond idealized and simple flights to include for example the interaction of pilots and ATCOs. The research shows clearly that verification and validation must include the entire work system, on the one hand to check that mechanisms exist to handle failures of communication and alerting subsystems and/or failures of people to notice, comprehend, or communicate problematic (unsafe) situations; but also to understand how people must use their own judgment in relating fallible systems like TCAS to other sources of information and thus to evaluate how the unreliability of automation affects system safety. The simulation shows in particular that distributed agents (people and automated systems) acting without knowledge of each others' actions can create a complex, dynamic system whose interactive behavior is unexpected and is changing too quickly to comprehend and control.

Clancey, William J.; Linde, Charlotte; Seah, Chin; Shafto, Michael

2013-01-01

368

A Cognitive System Model for Human/Automation Dynamics in Airspace Management  

NASA Technical Reports Server (NTRS)

NASA has initiated a significant thrust of research and development focused on providing the flight crew and air traffic managers automation aids to increase capacity in en route and terminal area operations through the use of flexible, more fuel-efficient routing, while improving the level of safety in commercial carrier operations. In that system development, definition of cognitive requirements for integrated multi-operator dynamic aiding systems is fundamental. In order to support that cognitive function definition, we have extended the Man Machine Integrated Design and Analysis System (MIDAS) to include representation of multiple cognitive agents (both human operators and intelligent aiding systems) operating aircraft, airline operations centers and air traffic control centers in the evolving airspace. The demands of this application require representation of many intelligent agents sharing world-models, and coordinating action/intention with cooperative scheduling of goals and actions in a potentially unpredictable world of operations. The MIDAS operator models have undergone significant development in order to understand the requirements for operator aiding and the impact of that aiding in the complex nondeterminate system of national airspace operations. The operator model's structure has been modified to include attention functions, action priority, and situation assessment. The cognitive function model has been expanded to include working memory operations including retrieval from long-term store, interference, visual-motor and verbal articulatory loop functions, and time-based losses. The operator's activity structures have been developed to include prioritization and interruption of multiple parallel activities among multiple operators, to provide for anticipation (knowledge of the intention and action of remote operators), and to respond to failures of the system and other operators in the system in situation-specific paradigms. The model's internal representation has been be modified so that multiple, autonomous sets of equipment will function in a scenario as the single equipment sets do now. In order to support the analysis requirements with multiple items of equipment, it is necessary for equipment to access the state of other equipment objects at initialization time (a radar object may need to access the position and speed of aircraft in its area, for example), and as a function of perception and sensor system interaction. The model has been improved to include multiple world-states as a function of equipment am operator interaction. The model has been used -1o predict the impact of warning and alert zones in aircraft operation, and, more critic-ally, the interaction of flight-deck based warning mechanisms and air traffic controller action in response to ground-based conflict prediction and alerting systems. In this operation, two operating systems provide alerting to two autonomous, but linked sets of operators, whose view of the system and whose dynamics in response are radically different. System stability and operator action was predicted using the MIDAS model.

Corker, Kevin M.; Pisanich, Gregory; Lebacqz, J. Victor (Technical Monitor)

1997-01-01

369

A knowledge- and model-based system for automated weaning from mechanical ventilation: technical description and first clinical application.  

PubMed

To describe the principles and the first clinical application of a novel prototype automated weaning system called Evita Weaning System (EWS). EWS allows an automated control of all ventilator settings in pressure controlled and pressure support mode with the aim of decreasing the respiratory load of mechanical ventilation. Respiratory load takes inspired fraction of oxygen, positive end-expiratory pressure, pressure amplitude and spontaneous breathing activity into account. Spontaneous breathing activity is assessed by the number of controlled breaths needed to maintain a predefined respiratory rate. EWS was implemented as a knowledge- and model-based system that autonomously and remotely controlled a mechanical ventilator (Evita 4, Dräger Medical, Lübeck, Germany). In a selected case study (n = 19 patients), ventilator settings chosen by the responsible physician were compared with the settings 10 min after the start of EWS and at the end of the study session. Neither unsafe ventilator settings nor failure of the system occurred. All patients were successfully transferred from controlled ventilation to assisted spontaneous breathing in a mean time of 37 ± 17 min (± SD). Early settings applied by the EWS did not significantly differ from the initial settings, except for the fraction of oxygen in inspired gas. During the later course, EWS significantly modified most of the ventilator settings and reduced the imposed respiratory load. A novel prototype automated weaning system was successfully developed. The first clinical application of EWS revealed that its operation was stable, safe ventilator settings were defined and the respiratory load of mechanical ventilation was decreased. PMID:23892513

Schädler, Dirk; Mersmann, Stefan; Frerichs, Inéz; Elke, Gunnar; Semmel-Griebeler, Thomas; Noll, Oliver; Pulletz, Sven; Zick, Günther; David, Matthias; Heinrichs, Wolfgang; Scholz, Jens; Weiler, Norbert

2014-10-01

370

Prediction of hot spots in protein interfaces using a random forest model with hybrid features.  

PubMed

Prediction of hot spots in protein interfaces provides crucial information for the research on protein-protein interaction and drug design. Existing machine learning methods generally judge whether a given residue is likely to be a hot spot by extracting features only from the target residue. However, hot spots usually form a small cluster of residues which are tightly packed together at the center of protein interface. With this in mind, we present a novel method to extract hybrid features which incorporate a wide range of information of the target residue and its spatially neighboring residues, i.e. the nearest contact residue in the other face (mirror-contact residue) and the nearest contact residue in the same face (intra-contact residue). We provide a novel random forest (RF) model to effectively integrate these hybrid features for predicting hot spots in protein interfaces. Our method can achieve accuracy (ACC) of 82.4% and Matthew's correlation coefficient (MCC) of 0.482 in Alanine Scanning Energetics Database, and ACC of 77.6% and MCC of 0.429 in Binding Interface Database. In a comparison study, performance of our RF model exceeds other existing methods, such as Robetta, FOLDEF, KFC, KFC2, MINERVA and HotPoint. Of our hybrid features, three physicochemical features of target residues (mass, polarizability and isoelectric point), the relative side-chain accessible surface area and the average depth index of mirror-contact residues are found to be the main discriminative features in hot spots prediction. We also confirm that hot spots tend to form large contact surface areas between two interacting proteins. Source data and code are available at: http://www.aporc.org/doc/wiki/HotSpot. PMID:22258275

Wang, Lin; Liu, Zhi-Ping; Zhang, Xiang-Sun; Chen, Luonan

2012-03-01

371

Fracture permeability and seismic wave scattering--Poroelastic linear-slip interface model for heterogeneous fractures  

SciTech Connect

Schoenberg's Linear-slip Interface (LSI) model for single, compliant, viscoelastic fractures has been extended to poroelastic fractures for predicting seismic wave scattering. However, this extended model results in no impact of the in-plane fracture permeability on the scattering. Recently, we proposed a variant of the LSI model considering the heterogeneity in the in-plane fracture properties. This modified model considers wave-induced, fracture-parallel fluid flow induced by passing seismic waves. The research discussed in this paper applies this new LSI model to heterogeneous fractures to examine when and how the permeability of a fracture is reflected in the scattering of seismic waves. From numerical simulations, we conclude that the heterogeneity in the fracture properties is essential for the scattering of seismic waves to be sensitive to the permeability of a fracture.

Nakagawa, S.; Myer, L.R.

2009-06-15

372

The Automated Logistics Element Planning System (ALEPS)  

NASA Technical Reports Server (NTRS)

The design and functions of ALEPS (Automated Logistics Element Planning System) is a computer system that will automate planning and decision support for Space Station Freedom Logistical Elements (LEs) resupply and return operations. ALEPS provides data management, planning, analysis, monitoring, interfacing, and flight certification for support of LE flight load planning activities. The prototype ALEPS algorithm development is described.

Schwaab, Douglas G.

1991-01-01

373

Interfacing comprehensive rotorcraft analysis with advanced aeromechanics and vortex wake models  

NASA Astrophysics Data System (ADS)

This dissertation describes three aspects of the comprehensive rotorcraft analysis. First, a physics-based methodology for the modeling of hydraulic devices within multibody-based comprehensive models of rotorcraft systems is developed. This newly proposed approach can predict the fully nonlinear behavior of hydraulic devices, and pressure levels in the hydraulic chambers are coupled with the dynamic response of the system. The proposed hydraulic device models are implemented in a multibody code and calibrated by comparing their predictions with test bench measurements for the UH-60 helicopter lead-lag damper. Predicted peak damping forces were found to be in good agreement with measurements, while the model did not predict the entire time history of damper force to the same level of accuracy. The proposed model evaluates relevant hydraulic quantities such as chamber pressures, orifice flow rates, and pressure relief valve displacements. This model could be used to design lead-lag dampers with desirable force and damping characteristics. The second part of this research is in the area of computational aeroelasticity, in which an interface between computational fluid dynamics (CFD) and computational structural dynamics (CSD) is established. This interface enables data exchange between CFD and CSD with the goal of achieving accurate airloads predictions. In this work, a loose coupling approach based on the delta-airloads method is developed in a finite-element method based multibody dynamics formulation, DYMORE. To validate this aerodynamic interface, a CFD code, OVERFLOW-2, is loosely coupled with a CSD program, DYMORE, to compute the airloads of different flight conditions for Sikorsky UH-60 aircraft. This loose coupling approach has good convergence characteristics. The predicted airloads are found to be in good agreement with the experimental data, although not for all flight conditions. In addition, the tight coupling interface between the CFD program, OVERFLOW-2, and the CSD program, DYMORE, is also established. The ability to accurately capture the wake structure around a helicopter rotor is crucial for rotorcraft performance analysis. In the third part of this thesis, a new representation of the wake vortex structure based on Non-Uniform Rational B-Spline (NURBS) curves and surfaces is proposed to develop an efficient model for prescribed and free wakes. NURBS curves and surfaces are able to represent complex shapes with remarkably little data. The proposed formulation has the potential to reduce the computational cost associated with the use of Helmholtz's law and the Biot-Savart law when calculating the induced flow field around the rotor. An efficient free-wake analysis will considerably decrease the computational cost of comprehensive rotorcraft analysis, making the approach more attractive to routine use in industrial settings.

Liu, Haiying

374

BOADICEA breast cancer risk prediction model: updates to cancer incidences, tumour pathology and web interface  

PubMed Central

Background: The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) is a risk prediction model that is used to compute probabilities of carrying mutations in the high-risk breast and ovarian cancer susceptibility genes BRCA1 and BRCA2, and to estimate the future risks of developing breast or ovarian cancer. In this paper, we describe updates to the BOADICEA model that extend its capabilities, make it easier to use in a clinical setting and yield more accurate predictions. Methods: We describe: (1) updates to the statistical model to include cancer incidences from multiple populations; (2) updates to the distributions of tumour pathology characteristics using new data on BRCA1 and BRCA2 mutation carriers and women with breast cancer from the general population; (3) improvements to the computational efficiency of the algorithm so that risk calculations now run substantially faster; and (4) updates to the model's web interface to accommodate these new features and to make it easier to use in a clinical setting. Results: We present results derived using the updated model, and demonstrate that the changes have a significant impact on risk predictions. Conclusion: All updates have been implemented in a new version of the BOADICEA web interface that is now available for general use: http://ccge.medschl.cam.ac.uk/boadicea/. PMID:24346285

Lee, A J; Cunningham, A P; Kuchenbaecker, K B; Mavaddat, N; Easton, D F; Antoniou, A C

2014-01-01

375

Simulating an Automated Approach to Discovery and Modeling of Open Source Software Development Processes  

E-print Network

Processes Chris Jensen and Walt Scacchi Institute for Software Research University of California, Irvine spaces of open source software development projects. In searching for an automated solution to the process discovery problem, we first have simulated it by having a human act as an "intelligent spider

Scacchi, Walt

376

AUTOMATED GIS WATERSHED ANALYSIS TOOLS FOR RUSLE/SEDMOD SOIL EROSION AND SEDIMENTATION MODELING  

EPA Science Inventory

A comprehensive procedure for computing soil erosion and sediment delivery metrics has been developed using a suite of automated Arc Macro Language (AML ) scripts and a pair of processing- intensive ANSI C++ executable programs operating on an ESRI ArcGIS 8.x Workstation platform...

377

The York Public Libraries Network: A Unique Model for Co-operative Automation.  

ERIC Educational Resources Information Center

Describes automated library network developed when five municipal library systems entered into an equal partnership to create single database and to jointly own a computerized circulation and MARC records system. Highlights include use of microcomputers, the shared circulation system, costs, benefits, governance, equality, stability and financial…

Horrocks, Jane; And Others

1986-01-01

378

A comparison between automated generated code tools using model based development  

Microsoft Academic Search

The use of automated generated code tools has been increasing in the last years mainly because it helps engineers to faster and better develop documented software in comparison with hand coded development. Nowadays, there are many tools available from different vendors. However, the most used tools for critical environments and real-time applications are the Rational Rose Real Time (RRRT) and

Guilherme Coelho da Silva Stanisce Correa; Adilson Marques da Cunha; Luiz Alberto Vieira Dias; Osamu Saotome

2011-01-01

379

A Newtonian rheological model for the interface of microbubble contrast agents.  

PubMed

A quantitative model of the dynamics of an encapsulated microbubble contrast agent will be a valuable tool in contrast ultrasound (US). Such a model must have predictive ability for widely varying frequencies and pressure amplitudes. We have developed a new model for contrast agents, and successfully investigated its applicability for a wide range of operating parameters. The encapsulation is modeled as a complex interface of an infinitesimal thickness. A Newtonian rheology with surface viscosities and interfacial tension is assumed for the interface, and a modified Rayleigh-Plesset equation is derived. The rheological parameters (surface tension and surface dilatational viscosity) for a number of contrast agents (Albunex, Optison and Quantison) are determined by matching the linearized model dynamics with experimentally obtained attenuation data. The model behavior for Optison (surface tension 0.9 N/m and surface dilatational viscosity 0.08 msP) was investigated in detail. Specifically, we have carried out a detailed interrogation of the model, fitted in the linear regime, for its nonlinear prediction. In contrast to existing models, the new model is found to capture the characteristic subharmonic emission of Optison observed by. A detailed parametric study of the bubble behavior was executed using the ratio of scattering to attenuation (STAR). It shows that the encapsulation drastically reduces the influence of resonance frequency on scattering cross-section, suggesting possible means of improvement in imaging at off-resonant frequencies. The predictive capability of the present model indicates that it can be used for characterizing different agents and designing new ones. PMID:14698342

Chatterjee, Dhiman; Sarkar, Kausik

2003-12-01

380

Automated Fault Diagnosis at Philips Medical Systems  

E-print Network

Automated Fault Diagnosis at Philips Medical Systems A Model-Based Approach Master's Thesis W.M. Lindhoud #12;#12;Automated Fault Diagnosis at Philips Medical Systems A Model-Based Approach THESIS-Ray System, © Philips #12;Automated Fault Diagnosis at Philips Medical Systems A Model-Based Approach Author

van Gemund, Arjan J.C.

381

ModelMuse - A Graphical User Interface for MODFLOW-2005 and PHAST  

USGS Publications Warehouse

ModelMuse is a graphical user interface (GUI) for the U.S. Geological Survey (USGS) models MODFLOW-2005 and PHAST. This software package provides a GUI for creating the flow and transport input file for PHAST and the input files for MODFLOW-2005. In ModelMuse, the spatial data for the model is independent of the grid, and the temporal data is independent of the stress periods. Being able to input these data independently allows the user to redefine the spatial and temporal discretization at will. This report describes the basic concepts required to work with ModelMuse. These basic concepts include the model grid, data sets, formulas, objects, the method used to assign values to data sets, and model features. The ModelMuse main window has a top, front, and side view of the model that can be used for editing the model, and a 3-D view of the model that can be used to display properties of the model. ModelMuse has tools to generate and edit the model grid. It also has a variety of interpolation methods and geographic functions that can be used to help define the spatial variability of the model. ModelMuse can be used to execute both MODFLOW-2005 and PHAST and can also display the results of MODFLOW-2005 models. An example of using ModelMuse with MODFLOW-2005 is included in this report. Several additional examples are described in the help system for ModelMuse, which can be accessed from the Help menu.

Winston, Richard B.

2009-01-01

382

Development of a semi-automated method for mitral valve modeling with medial axis representation using 3D ultrasound  

PubMed Central

Purpose: Precise 3D modeling of the mitral valve has the potential to improve our understanding of valve morphology, particularly in the setting of mitral regurgitation (MR). Toward this goal, the authors have developed a user-initialized algorithm for reconstructing valve geometry from transesophageal 3D ultrasound (3D US) image data. Methods: Semi-automated image analysis was performed on transesophageal 3D US images obtained from 14 subjects with MR ranging from trace to severe. Image analysis of the mitral valve at midsystole had two stages: user-initialized segmentation and 3D deformable modeling with continuous medial representation (cm-rep). Semi-automated segmentation began with user-identification of valve location in 2D projection images generated from 3D US data. The mitral leaflets were then automatically segmented in 3D using the level set method. Second, a bileaflet deformable medial model was fitted to the binary valve segmentation by Bayesian optimization. The resulting cm-rep provided a visual reconstruction of the mitral valve, from which localized measurements of valve morphology were automatically derived. The features extracted from the fitted cm-rep included annular area, annular circumference, annular height, intercommissural width, septolateral length, total tenting volume, and percent anterior tenting volume. These measurements were compared to those obtained by expert manual tracing. Regurgitant orifice area (ROA) measurements were compared to qualitative assessments of MR severity. The accuracy of valve shape representation with cm-rep was evaluated in terms of the Dice overlap between the fitted cm-rep and its target segmentation. Results: The morphological features and anatomic ROA derived from semi-automated image analysis were consistent with manual tracing of 3D US image data and with qualitative assessments of MR severity made on clinical radiology. The fitted cm-reps accurately captured valve shape and demonstrated patient-specific differences in valve morphology among subjects with varying degrees of MR severity. Minimal variation in the Dice overlap and morphological measurements was observed when different cm-rep templates were used to initialize model fitting. Conclusions: This study demonstrates the use of deformable medial modeling for semi-automated 3D reconstruction of mitral valve geometry using transesophageal 3D US. The proposed algorithm provides a parametric geometrical representation of the mitral leaflets, which can be used to evaluate valve morphology in clinical ultrasound images. PMID:22320803

M. Pouch, Alison; A. Yushkevich, Paul; M. Jackson, Benjamin; S. Jassar, Arminder; Vergnat, Mathieu; H. Gorman, Joseph; C. Gorman, Robert; M. Sehgal, Chandra

2012-01-01

383

MAMMOTH (Matching molecular models obtained from theory): An automated method for model comparison  

PubMed Central

Advances in structural genomics and protein structure prediction require the design of automatic, fast, objective, and well benchmarked methods capable of comparing and assessing the similarity of low-resolution three-dimensional structures, via experimental or theoretical approaches. Here, a new method for sequence-independent structural alignment is presented that allows comparison of an experimental protein structure with an arbitrary low-resolution protein tertiary model. The heuristic algorithm is given and then used to show that it can describe random structural alignments of proteins with different folds with good accuracy by an extreme value distribution. From this observation, a structural similarity score between two proteins or two different conformations of the same protein is derived from the likelihood of obtaining a given structural alignment by chance. The performance of the derived score is then compared with well established, consensus manual-based scores and data sets. We found that the new approach correlates better than other tools with the gold standard provided by a human evaluator. Timings indicate that the algorithm is fast enough for routine use with large databases of protein models. Overall, our results indicate that the new program (MAMMOTH) will be a good tool for protein structure comparisons in structural genomics applications. MAMMOTH is available from our web site at http://physbio.mssm.edu/?ortizg/. PMID:12381844

Ortiz, Angel R.; Strauss, Charlie E.M.; Olmea, Osvaldo

2002-01-01

384

BEM solution of delamination problems using an interface damage and plasticity model  

NASA Astrophysics Data System (ADS)

The problem of quasistatic and rate-independent evolution of elastic-plastic-brittle delamination at small strains is considered. Delamination processes for linear elastic bodies glued by an adhesive to each other or to a rigid outer surface are studied. The energy amounts dissipated in fracture Mode I (opening) and Mode II (shear) at an interface may be different. A concept of internal parameters is used here on the delaminating interfaces, involving a couple of scalar damage variable and a plastic tangential slip with kinematic-type hardening. The so-called energetic solution concept is employed. An inelastic process at an interface is devised in such a way that the dissipated energy depends only on the rates of internal parameters and therefore the model is associative. A fully implicit time discretization is combined with a spatial discretization of elastic bodies by the BEM to solve the delamination problem. The BEM is used in the solution of the respective boundary value problems, for each subdomain separately, to compute the corresponding total potential energy. Sample problems are analysed by a collocation BEM code to illustrate the capabilities of the numerical procedure developed.

Panagiotopoulos, C. G.; Manti?, V.; Roubí?ek, T.

2013-04-01

385

Fundamental insights about environmental interface reactivity from DFT calculations of geochemical model systems  

NASA Astrophysics Data System (ADS)

The fact that essential chemical information about environmental interfaces is becoming accessible through density functional theory (DFT) studies provides researchers with a means to interpret experimental information, to predict properties that cannot be measured, and to develop conceptual, molecular-level understanding of structure-property relationships of these systems. Molecular studies of environmental interfaces require the use of structurally well-defined geochemical models, and in here we discuss the reactivity of mineral-water interfaces and aqueous aluminum hydroxide nanoparticles with ionic species. These adsorption processes are a major factor controlling pollutant transport and transformation. In the examples we highlight, DFT studies are used to extract new conceptual understanding of the underlying physical factors of the substrates that dictate reactivity. In particular, we review DFT studies used to rationalize an empirically determined reactivity trend of hydrated alumina and hematite towards Pb(II), and later review how DFT calculations of aqueous aluminum hydroxide nanoparticles along with experimental structural information helped to identify the electrostatic potential as a key factor in understanding particle reactivity towards cationic and anionic species.

Mason, Sara E.; Corum, Katie W.; Ramadugu, Sai Kumar

2015-01-01

386

A mesoscopic rheological model of immiscible blends with the interface covered with a surface active agent  

NASA Astrophysics Data System (ADS)

The Maffettone-Minale mesoscopic rheological model of immiscible blends is extended to blends that include a surface active agent. Its nonuniform distribution on the interface (assumed to be the surface of droplets) and the associated with it nonuniform distribution of the surface tension and the Marangoni stress are incorporated into the model. Instead of using one ellipsoid (one conformation tensor in the mathematical formulation) to characterize the shape of the droplet, we use a one parameter family of ellipsoids (a "necklace" of ellipsoids) to play this role. Both rheology and morphology (including large deviations form the ellipsoidal shape of droplets) are calculated and compared to predictions of microscopic models (i.e., models based on microhydrodynamics) and with results of experimental observations.

Gu, Jian Feng; Grmela, Miroslav; Bousmina, Mosto

2008-04-01

387

Modulation depth estimation and variable selection in state-space models for neural interfaces.  

PubMed

Rapid developments in neural interface technology are making it possible to record increasingly large signal sets of neural activity. Various factors such as asymmetrical information distribution and across-channel redundancy may, however, limit the benefit of high-dimensional signal sets, and the increased computational complexity may not yield corresponding improvement in system performance. High-dimensional system models may also lead to overfitting and lack of generalizability. To address these issues, we present a generalized modulation depth measure using the state-space framework that quantifies the tuning of a neural signal channel to relevant behavioral covariates. For a dynamical system, we develop computationally efficient procedures for estimating modulation depth from multivariate data. We show that this measure can be used to rank neural signals and select an optimal channel subset for inclusion in the neural decoding algorithm. We present a scheme for choosing the optimal subset based on model order selection criteria. We apply this method to neuronal ensemble spike-rate decoding in neural interfaces, using our framework to relate motor cortical activity with intended movement kinematics. With offline analysis of intracortical motor imagery data obtained from individuals with tetraplegia using the BrainGate neural interface, we demonstrate that our variable selection scheme is useful for identifying and ranking the most information-rich neural signals. We demonstrate that our approach offers several orders of magnitude lower complexity but virtually identical decoding performance compared to greedy search and other selection schemes. Our statistical analysis shows that the modulation depth of human motor cortical single-unit signals is well characterized by the generalized Pareto distribution. Our variable selection scheme has wide applicability in problems involving multisensor signal modeling and estimation in biomedical engineering systems. PMID:25265627

Malik, Wasim Q; Hochberg, Leigh R; Donoghue, John P; Brown, Emery N

2015-02-01

388

Intelligent interface design and evaluation  

NASA Technical Reports Server (NTRS)

Intelligent interface concepts and systematic approaches to assessing their functionality are discussed. Four general features of intelligent interfaces are described: interaction efficiency, subtask automation, context sensitivity, and use of an appropriate design metaphor. Three evaluation methods are discussed: Functional Analysis, Part-Task Evaluation, and Operational Testing. Design and evaluation concepts are illustrated with examples from a prototype expert system interface for environmental control and life support systems for manned space platforms.

Greitzer, Frank L.

1988-01-01

389

Molecules to modeling: Toxoplasma gondii oocysts at the human–animal–environment interface  

PubMed Central

Environmental transmission of extremely resistant Toxoplasma gondii oocysts has resulted in infection of diverse species around the world, leading to severe disease and deaths in human and animal populations. This review explores T. gondii oocyst shedding, survival, and transmission, emphasizing the importance of linking laboratory and landscape from molecular characterization of oocysts to watershed-level models of oocyst loading and transport in terrestrial and aquatic systems. Building on discipline-specific studies, a One Health approach incorporating tools and perspectives from diverse fields and stakeholders has contributed to an advanced understanding of T. gondii and is addressing transmission at the rapidly changing human–animal–environment interface. PMID:23218130

VanWormer, Elizabeth; Fritz, Heather; Shapiro, Karen; Mazet, Jonna A.K.; Conrad, Patricia A.

2013-01-01

390

A new graphical user interface for a 3D topological mesh modeler  

E-print Network

format with an extremely simple implementation that interfaces with rapid prototyping equipment such as 3D printers and fused deposition modelers (FDMs) is the Stereolithography, or STL, format [3]. Another common format used for displaying 3D meshes in a... web browser through a simple Java applet is the Mathematica LiveGraphics3D (*.m) file format [4]. Like OBJ files, STL and LiveGraphics3D files can be stored in a human readable ASCII format. As computing hardware and software has become cheaper during...

Morris, David Victor

2008-10-10

391

Modelling the Bioelectronic Interface in Engineered Tethered Membranes: From Biosensing to Electroporation.  

PubMed

This paper studies the construction and predictive models of three novel measurement platforms: (i) a Pore Formation Measurement Platform (PFMP) for detecting the presence of pore forming proteins and peptides, (ii) the Ion Channel Switch (ICS) biosensor for detecting the presence of analyte molecules in a fluid chamber, and (iii) an Electroporation Measurement Platform (EMP) that provides reliable measurements of the electroporation phenomenon. Common to all three measurement platforms is that they are comprised of an engineered tethered membrane that is formed via a rapid solvent exchange technique allowing the platform to have a lifetime of several months. The membrane is tethered to a gold electrode bioelectronic interface that includes an ionic reservoir separating the membrane and gold surface, allowing the membrane to mimic the physiological response of natural cell membranes. The electrical response of the PFMP, ICS, and EMP are predicted using continuum theories for electrodiffusive flow coupled with boundary conditions for modelling chemical reactions and electrical double layers present at the bioelectronic interface. Experimental measurements are used to validate the predictive accuracy of the dynamic models. These include using the PFMP for measuring the pore formation dynamics of the antimicrobial peptide PGLa and the protein toxin Staphylococcal ?-Hemolysin; the ICS biosensor for measuring nano-molar concentrations of streptavidin, ferritin, thyroid stimulating hormone (TSH), and human chorionic gonadotropin (pregnancy hormone hCG); and the EMP for measuring electroporation of membranes with different tethering densities, and membrane compositions. PMID:25373111

Hoiles, William; Krishnamurthy, Vikram; Cornell, Bruce

2014-10-31

392

Automated Filtering of Internet Postings.  

ERIC Educational Resources Information Center

Discussion of the use of dynamic data resources, such as Internet LISTSERVs or Usenet newsgroups, focuses on an experiment using an automated filtering system with Usenet newsgroups. Highlights include user satisfaction, based on retrieval size, data sources, and user interface and the need for some human mediation. (Contains two references.) (LRW)

Rosenfeld, Louis B.; Holland, Maurita P.

1994-01-01

393

Two graphical user interfaces for managing and analyzing MODFLOW groundwater-model scenarios  

USGS Publications Warehouse

Scenario Manager and Scenario Analyzer are graphical user interfaces that facilitate the use of calibrated, MODFLOW-based groundwater models for investigating possible responses to proposed stresses on a groundwater system. Scenario Manager allows a user, starting with a calibrated model, to design and run model scenarios by adding or modifying stresses simulated by the model. Scenario Analyzer facilitates the process of extracting data from model output and preparing such display elements as maps, charts, and tables. Both programs are designed for users who are familiar with the science on which groundwater modeling is based but who may not have a groundwater modeler’s expertise in building and calibrating a groundwater model from start to finish. With Scenario Manager, the user can manipulate model input to simulate withdrawal or injection wells, time-variant specified hydraulic heads, recharge, and such surface-water features as rivers and canals. Input for stresses to be simulated comes from user-provided geographic information system files and time-series data files. A Scenario Manager project can contain multiple scenarios and is self-documenting. Scenario Analyzer can be used to analyze output from any MODFLOW-based model; it is not limited to use with scenarios generated by Scenario Manager. Model-simulated values of hydraulic head, drawdown, solute concentration, and cell-by-cell flow rates can be presented in display elements. Map data can be represented as lines of equal value (contours) or as a gradated color fill. Charts and tables display time-series data obtained from output generated by a transient-state model run or from user-provided text files of time-series data. A display element can be based entirely on output of a single model run, or, to facilitate comparison of results of multiple scenarios, an element can be based on output from multiple model runs. Scenario Analyzer can export display elements and supporting metadata as a Portable Document Format file.

Banta, Edward R.

2014-01-01

394

Automation in organizations: Eternal conflict  

NASA Technical Reports Server (NTRS)

Some ideas on and insights into the problems associated with automation in organizations are presented with emphasis on the concept of automation, its relationship to the individual, and its impact on system performance. An analogy is drawn, based on an American folk hero, to emphasize the extent of the problems encountered when dealing with automation within an organization. A model is proposed to focus attention on a set of appropriate dimensions. The function allocation process becomes a prominent aspect of the model. The current state of automation research is mentioned in relation to the ideas introduced. Proposed directions for an improved understanding of automation's effect on the individual's efficiency are discussed. The importance of understanding the individual's perception of the system in terms of the degree of automation is highlighted.

Dieterly, D. L.

1981-01-01

395

An expanded binding model for Cys2His2 zinc finger protein-DNA interfaces  

NASA Astrophysics Data System (ADS)

Cys2His2 zinc finger (C2H2-ZF) proteins comprise the largest class of eukaryotic transcription factors. The 'canonical model' for C2H2-ZF protein-DNA interaction consists of only four amino acid-nucleotide contacts per zinc finger domain, and this model has been the basis for several efforts for computationally predicting and experimentally designing protein-DNA interfaces. Here, we perform a systematic analysis of structural and experimental binding data and find that, in addition to the canonical contacts, several other amino acid and base pair combinations frequently play a role in C2H2-ZF protein-DNA binding. We suggest an expansion of the canonical C2H2-ZF model to include one to three additional contacts, and show that computational approaches including these additional contacts improve predictions of DNA targets of zinc finger proteins.

Persikov, Anton V.; Singh, Mona

2011-06-01

396

Self-consistent quantum mechanical model for the description of excitation energy transfers in molecules at interfaces  

Microsoft Academic Search

In this paper we present a quantum mechanical model to study excitation energy transfers in molecular systems located in the vicinity of an interface. The model is based on an approximate solution of the time-dependent density functional theory equations and solvent effects are introduced in terms of the integral equation formalism version of the polarizable continuum model. A unique characteristic

Carles Curutchet; Roberto Cammi; Benedetta Mennucci; Stefano Corni

2006-01-01

397

Modeling and simulation of electronic structure, material interface and random doping in nano electronic devices  

PubMed Central

The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano scale. By optimization of the energy functional, we derive consistently-coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I-V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical convergence and model well-posedness are also investigated in the present work. PMID:20396650

Chen, Duan; Wei, Guo-Wei

2010-01-01

398

Stochastic modelling of a large subduction interface earthquake in Wellington, New Zealand  

NASA Astrophysics Data System (ADS)

The Wellington region, home of New Zealand's capital city, is cut by a number of major right-lateral strike slip faults, and is underlain by the currently locked west-dipping subduction interface between the down going Pacific Plate, and the over-riding Australian Plate. A potential cause of significant earthquake loss in the Wellington region is a large magnitude (perhaps 8+) "subduction earthquake" on the Australia-Pacific plate interface, which lies ~23 km beneath Wellington City. "It's Our Fault" is a project involving a comprehensive study of Wellington's earthquake risk. Its objective is to position Wellington city to become more resilient, through an encompassing study of the likelihood of large earthquakes, and the effects and impacts of these earthquakes on humans and the built environment. As part of the "It's Our Fault" project, we are working on estimating ground motions from potential large plate boundary earthquakes. We present the latest results on ground motion simulations in terms of response spectra and acceleration time histories. First we characterise the potential interface rupture area based on previous geodetically-derived estimates interface of slip deficit. Then, we entertain a suitable range of source parameters, including various rupture areas, moment magnitudes, stress drops, slip distributions and rupture propagation directions. Our comprehensive study also includes simulations from historical large world subduction events translated into the New Zealand subduction context, such as the 2003 M8.3 Tokachi-Oki Japan earthquake and the M8.8 2010 Chili earthquake. To model synthetic seismograms and the corresponding response spectra we employed the EXSIM code developed by Atkinson et al. (2009), with a regional attenuation model based on the 3D attenuation model for the lower North-Island which has been developed by Eberhart-Phillips et al. (2005). The resulting rupture scenarios all produce long duration shaking, and peak ground accelerations that, typically range between 0.2-0.7 g in Wellington city. Many of these scenarios also produce long period motions that are currently not captured by the current NZ design spectra.

Francois-Holden, C.; Zhao, J.

2012-12-01

399

An Analysis Technique/Automated Tool for Comparing and Tracking Analysis Modes of Different Finite Element Models  

NASA Technical Reports Server (NTRS)

An analysis technique was developed to compare and track mode shapes for different Finite Element Models. The technique may be applied to a variety of structural dynamics analyses, including model reduction validation (comparing unreduced and reduced models), mode tracking for various parametric analyses (e.g., launch vehicle model dispersion analysis to identify sensitivities to modal gain for Guidance, Navigation, and Control), comparing models of different mesh fidelity (e.g., a coarse model for a preliminary analysis compared to a higher-fidelity model for a detailed analysis) and mode tracking for a structure with properties that change over time (e.g., a launch vehicle from liftoff through end-of-burn, with propellant being expended during the flight). Mode shapes for different models are compared and tracked using several numerical indicators, including traditional Cross-Orthogonality and Modal Assurance Criteria approaches, as well as numerical indicators obtained by comparing modal strain energy and kinetic energy distributions. This analysis technique has been used to reliably identify correlated mode shapes for complex Finite Element Models that would otherwise be difficult to compare using traditional techniques. This improved approach also utilizes an adaptive mode tracking algorithm that allows for automated tracking when working with complex models and/or comparing a large group of models.

Towner, Robert L.; Band, Jonathan L.

2012-01-01

400

Modeling fire susceptibility to delineate wildland-urban interface for municipal-scale fire risk management.  

PubMed

The wildland-urban interface (WUI) is the region where development meets and intermingles with wildlands. The WUI has an elevated fire risk due to the proximity of development and residents to wildlands with natural wildfire regimes. Existing methods of delineating WUI are typically applied over a large region, use proxies for risk, and do not consider site-specific fire hazard drivers. While these models are appropriate for federal and provincial risk management, municipal managers require models intended for smaller regions. The model developed here uses the Burn-P3 fire behavior model to model WUI from local fire susceptibility (FS) in two study communities. Forest fuel code (FFC) maps for the study communities were modified using remote sensing data to produce detailed forest edges, including ladder fuels, update data currency, and add buildings and roads. The modified FFC maps used in Burn-P3 produced bimodal FS distributions for each community. The WUI in these communities was delineated as areas within community bounds where FS was greater than or equal to -1 SD from the mean FS value ([Formula: see text]), which fell in the trough of the bimodal distribution. The WUI so delineated conformed to the definition of WUI. This model extends WUI modeling for broader risk management initiatives for municipal management of risk, as it (a) considers site-specific drivers of fire behavior; (b) models risk, represented by WUI, specific to a community; and, (c) does not use proxies for risk. PMID:24036629

Whitman, Ellen; Rapaport, Eric; Sherren, Kate

2013-12-01

401

MIG version 0.0 model interface guidelines: Rules to accelerate installation of numerical models into any compliant parent code  

SciTech Connect

A set of model interface guidelines, called MIG, is presented as a means by which any compliant numerical material model can be rapidly installed into any parent code without having to modify the model subroutines. Here, {open_quotes}model{close_quotes} usually means a material model such as one that computes stress as a function of strain, though the term may be extended to any numerical operation. {open_quotes}Parent code{close_quotes} means a hydrocode, finite element code, etc. which uses the model and enforces, say, the fundamental laws of motion and thermodynamics. MIG requires the model developer (who creates the model package) to specify model needs in a standardized but flexible way. MIG includes a dictionary of technical terms that allows developers and parent code architects to share a common vocabulary when specifying field variables. For portability, database management is the responsibility of the parent code. Input/output occurs via structured calling arguments. As much model information as possible (such as the lists of required inputs, as well as lists of precharacterized material data and special needs) is supplied by the model developer in an ASCII text file. Every MIG-compliant model also has three required subroutines to check data, to request extra field variables, and to perform model physics. To date, the MIG scheme has proven flexible in beta installations of a simple yield model, plus a more complicated viscodamage yield model, three electromechanical models, and a complicated anisotropic microcrack constitutive model. The MIG yield model has been successfully installed using identical subroutines in three vectorized parent codes and one parallel C++ code, all predicting comparable results. By maintaining one model for many codes, MIG facilitates code-to-code comparisons and reduces duplication of effort, thereby reducing the cost of installing and sharing models in diverse new codes.

Brannon, R.M.; Wong, M.K.

1996-08-01

402

Automation or De-automation  

NASA Astrophysics Data System (ADS)

In the global automotive industry, for decades, vehicle manufacturers have continually increased the level of automation of production systems in order to be competitive. However, there is a new trend to decrease the level of automation, especially in final car assembly, for reasons of economy and flexibility. In this research, the final car assembly lines at three production sites of Volkswagen are analysed in order to determine the best level of automation for each, in terms of manufacturing costs, productivity, quality and flexibility. The case study is based on the methodology proposed by the Fraunhofer Institute. The results of the analysis indicate that fully automated assembly systems are not necessarily the best option in terms of cost, productivity and quality combined, which is attributed to high complexity of final car assembly systems; some de-automation is therefore recommended. On the other hand, the analysis shows that low automation can result in poor product quality due to reasons related to plant location, such as inadequate workers' skills, motivation, etc. Hence, the automation strategy should be formulated on the basis of analysis of all relevant aspects of the manufacturing process, such as costs, quality, productivity and flexibility in relation to the local context. A more balanced combination of automated and manual assembly operations provides better utilisation of equipment, reduces production costs and improves throughput.

Gorlach, Igor; Wessel, Oliver

2008-09-01

403

Adaptive and Adaptable Automation Design: A Critical Review of the Literature and Recommendations for Future Research  

NASA Technical Reports Server (NTRS)

This report presents a review of literature on approaches to adaptive and adaptable task/function allocation and adaptive interface technologies for effective human management of complex systems that are likely to be issues for the Next Generation Air Transportation System, and a focus of research under the Aviation Safety Program, Integrated Intelligent Flight Deck Project. Contemporary literature retrieved from an online database search is summarized and integrated. The major topics include the effects of delegation-type, adaptable automation on human performance, workload and situation awareness, the effectiveness of various automation invocation philosophies and strategies to function allocation in adaptive systems, and the role of user modeling in adaptive interface design and the performance implications of adaptive interface technology.

Prinzel, Lawrence J., III; Kaber, David B.

2006-01-01

404

Three-dimensional interface modelling with two-dimensional seismic data: the Alpine crust-mantle boundary  

USGS Publications Warehouse

We present a new approach to determine the 3-D topography and lateral continuity of seismic interfaces using 2-D-derived controlled-source seismic reflector data. The aim of the approach is to give the simplest possible structure consistent with all reflector data and error estimates. We define simplicity of seismic intrafaces by the degree of interface continuity (ie shortest length of offsets) and by the degree of interface roughness (least surface roughness). The method is applied to structural information of the crust-mantle boundary (Moho) obtained from over 250 controlled-source seismic reflection and refraction profiles in the greater Alpine region. The reflected and refracted phases from the Moho interface and their interpretation regarding crustal thickness are reviewed and their reliability weighted. Weights assigned to each reflector element are transformed to depth errors considering Fresnel volumes. The 2-D-derived reflector elements are relocated in space (3-D migration) and interpolation is performed between the observed reflector elements to obtain continuity of model parameters. Interface offsets are intoduced only where required according to the prinipal of simplicity. The resulting 3-D model of the ALpine crust-mantle boundary shows two offsets that eivide the interface into a European, an Adriatic and a Ligurian Moho, with the European Moho subducting below the Adriatic Moho, and with the Adriatic Moho underthrusting the Ligurian Moho. Each sub-interface depicts the smoothest possible (ie simplest) surface, fitting the reflector data within their assigned errors. The results are consistent with previous studies for those regions with dense and reliable controlled-source seismic data. The newly derived Alpine Moho interface, however, surpasses earlier studies by its lateral extent over an area of about 600km by 600km, by quantifying reliability estimates along the interface, and by obeying the priciple of being consistently as simple as possible.

Waldhauser, F.; Kissling, E.; Ansorge, J.; Mueller, St.

1998-01-01

405

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 10, NO. 3, MAY/JUNE 2004 445 Model-Based Optoelectronic Packaging Automation  

E-print Network

-Based Optoelectronic Packaging Automation Timothy P. Kurzweg, Member, IEEE, Allon Guez, and Shubham K. Bhat Abstract alignment and packaging through the use of intelligent control theory and system-level modeling. The control industries. The approach is to build an a priori knowledge model, specific to the assembled package's optical

Kurzweg, Timothy P.

406

Development of a non-linear finite element modelling of the below-knee prosthetic socket interface.  

PubMed

A non-linear finite element model has been established to predict the pressure and shear stress distribution at the limb-socket interface in below-knee amputees with consideration of the skin-liner interface friction and slip. In this model, the limb tissue and socket liner were respectively meshed into 954 and 450 three-dimensional eight-node isoparametric brick elements, based on measurements of an individual's amputated limb surface; the bone was meshed into three-dimensional six-node triangular prism elements, based on radiographic measurements of the individual's residual limb. The socket shell was assumed to be a rigid boundary. An important feature of this model is the use of 450 interface elements (ABAQUS INTER4) which mimic the interface friction condition. The results indicate that a maximum pressure of 226 kPa, shear stress of 53 kPa and less than 4 mm slip exist at the skin-liner interface when the full body weight of 800 N is applied to the limb. The results also show that the coefficient of friction is a very sensitive parameter in determining the interface pressures, shear stresses and slip. With the growth of coefficient of friction, the shear stresses will increase, while the pressure and slip will decrease. PMID:8564149

Zhang, M; Lord, M; Turner-Smith, A R; Roberts, V C

1995-12-01

407

Model Investigations on the Stability of the Steel-Slag Interface in Continuous-Casting Process  

NASA Astrophysics Data System (ADS)

In the continuous-casting mold, the mold powder in contact with the liquid steel surface forms a liquid slag layer. The flow along the steel-slag interface generates shear stress at the interface, waves, and leads to fingerlike protrusions of liquid slag into steel. Reaching a critical flow velocity and thereby shear stress, the protrusions can disintegrate into slag droplets following the flow in the liquid steel pool. These entrained droplets can form finally nonmetallic inclusions in steel material, cause defects in the final product, and therefore, should be avoided. In the current work, the stability of a liquid-liquid interface without mass transfer between phases was investigated in cold model study using a single-roller driven flow in oil-water systems with various oil properties. Applying the similarity theory, two dimensionless numbers were identified, viz. capillary number Ca and the ratio of kinematic viscosities ? 1/ ? 2, which are suitable to describe the force balance for the problem treated. The critical values of the dimensionless capillary number Ca* marking the start of lighter phase entrainment into the heavier fluid, are determined over a wide range of fluid properties. The dimensionless number ? 1/ ? 2 was defined as the ratio of kinematic viscosities of the lighter phase ? 1 and heavier phase ? 2. The ratios of kinematic viscosities of different steel-slag systems were calculated using measured thermophysical properties. With the knowledge of thermophysical properties of steel-slag systems, Ca* for slag entrainment as a function of v 1/ v 2 is derived. Assuming no reaction between the phases and no interfacial flow, slag entrainment should not occur under the usual casting conditions.

Hagemann, René; Schwarze, Rüdiger; Heller, Hans P.; Scheller, Piotr R.

2013-02-01

408

Thin interface analysis of a phase-field model for epitaxial growth with nucleation and Ehrlich-Schwoebel effects  

NASA Astrophysics Data System (ADS)

In this paper, we perform thin interface analysis of a quantitative phase field model for epitaxial growth where nucleation and the Ehrlich-Schwoebel barrier have been considered. Results show that once the nucleation term is introduced into the phase-field model, modification must be carried out to get rid of the extrinsic “kinetic nucleation effect”. While in the ES effect, the asymmetric diffusivity accounts for an irrational step motion that leads the model to deviate from the sharp-interface approximation, hence another modification for the attachment time should be carried. Attributed to these modifications, the phase-field model is more quantitative in describing step flow dynamics in the sharp-interface limit, as well as exhibiting the more convergence of the steady-state velocity with respect to the step width for larger scale simulations. Our analysis and modifications explore the quantitative linking between atom motions and step dynamics.

Dong, X. L.; Xing, H.; Chen, C. L.; Luo, B. C.; Chen, Z.; Zhang, R. L.; Jin, K. X.

2014-11-01

409

Performance of an Automated-Mixed-Traffic-Vehicle /AMTV/ System. [urban people mover  

NASA Technical Reports Server (NTRS)

This study analyzes the operation and evaluates the expected performance of a proposed automatic guideway transit system which uses low-speed Automated Mixed Traffic Vehicles (AMTV's). Vehicle scheduling and headway control policies are evaluated with a transit system simulation model. The effect of mixed-traffic interference on the average vehicle speed is examined with a vehicle-pedestrian interface model. Control parameters regulating vehicle speed are evaluated for safe stopping and passenger comfort.

Peng, T. K. C.; Chon, K.

1978-01-01

410

Fusion with language models improves spelling accuracy for ERP-based brain computer interface spellers.  

PubMed

Event related potentials (ERP) corresponding to a stimulus in electroencephalography (EEG) can be used to detect the intent of a person for brain computer interfaces (BCI). This paradigm is widely utilized to build letter-by-letter text input systems using BCI. Nevertheless using a BCI-typewriter depending only on EEG responses will not be sufficiently accurate for single-trial operation in general, and existing systems utilize many-trial schemes to achieve accuracy at the cost of speed. Hence incorporation of a language model based prior or additional evidence is vital to improve accuracy and speed. In this paper, we study the effects of Bayesian fusion of an n-gram language model with a regularized discriminant analysis ERP detector for EEG-based BCIs. The letter classification accuracies are rigorously evaluated for varying language model orders as well as number of ERP-inducing trials. The results demonstrate that the language models contribute significantly to letter classification accuracy. Specifically, we find that a BCI-speller supported by a 4-gram language model may achieve the same performance using 3-trial ERP classification for the initial letters of the words and using single trial ERP classification for the subsequent ones. Overall, fusion of evidence from EEG and language models yields a significant opportunity to increase the word rate of a BCI based typing system. PMID:22255652

Orhan, Umut; Erdogmus, Deniz; Roark, Brian; Purwar, Shalini; Hild, Kenneth E; Oken, Barry; Nezamfar, Hooman; Fried-Oken, Melanie

2011-01-01

411

Automated fault-management in a simulated spaceflight micro-world  

NASA Technical Reports Server (NTRS)

BACKGROUND: As human spaceflight missions extend in duration and distance from Earth, a self-sufficient crew will bear far greater onboard responsibility and authority for mission success. This will increase the need for automated fault management (FM). Human factors issues in the use of such systems include maintenance of cognitive skill, situational awareness (SA), trust in automation, and workload. This study examine the human performance consequences of operator use of intelligent FM support in interaction with an autonomous, space-related, atmospheric control system. METHODS: An expert system representing a model-base reasoning agent supported operators at a low level of automation (LOA) by a computerized fault finding guide, at a medium LOA by an automated diagnosis and recovery advisory, and at a high LOA by automate diagnosis and recovery implementation, subject to operator approval or veto. Ten percent of the experimental trials involved complete failure of FM support. RESULTS: Benefits of automation were reflected in more accurate diagnoses, shorter fault identification time, and reduced subjective operator workload. Unexpectedly, fault identification times deteriorated more at the medium than at the high LOA during automation failure. Analyses of information sampling behavior showed that offloading operators from recovery implementation during reliable automation enabled operators at high LOA to engage in fault assessment activities CONCLUSIONS: The potential threat to SA imposed by high-level automation, in which decision advisories are automatically generated, need not inevitably be counteracted by choosing a lower LOA. Instead, freeing operator cognitive resources by automatic implementation of recover plans at a higher LOA can promote better fault comprehension, so long as the automation interface is designed to support efficient information sampling.

Lorenz, Bernd; Di Nocera, Francesco; Rottger, Stefan; Parasuraman, Raja

2002-01-01

412

Accelerated lattice Boltzmann model for colloidal suspensions rheology and interface morphology  

NASA Astrophysics Data System (ADS)

Colloids are ubiquitous in the food, medical, cosmetic, polymer, water purification and pharmaceutical industries. Colloids thermal, mechanical and storage properties are highly dependent on their interface morphology and their rheological behavior. Numerical methods provide a cheap and reliable virtual laboratory for the study of colloids. However efficiency is a major concern to address when using numerical methods for practical applications. This work introduces the main building-blocks for an improved lattice Boltzmann-based numerical tool designed for the study of colloidal rheology and interface morphology. The efficiency of the proposed model is enhanced by using the recently developed and validated migrating multi-block algorithms for the lattice Boltzmann method (LBM). The migrating multi-block was used to simulate single component, multi-component, multiphase and single component multiphase flows. Results were validated by experimental, numerical and analytical solutions. The contamination of the fluid-fluid interface influences the colloids morphology. This issue was addressed by the introduction of the hybrid LBM for surfactant-covered droplets. The module was used for the simulation of surfactant-covered droplet deformation under shear and uniaxial extensional flows respectively and under buoyancy. Validation with experimental and theoretical results was provided. Colloids are non-Newtonian fluids which exhibit rich rheological behavior. The suppression of coalescence module is the part of the proposed model which facilitates the study of colloids rheology. The model results for the relative viscosity were in agreement with some theoretical results. Biological suspensions such as blood are macro-colloids by nature. The study of the blood flow in the microvasculature was heuristically approached by assuming the red blood cells as surfactant covered droplets. The effects of interfacial tension on the flow velocity and the droplet exclusion from the walls in parabolic flows were in qualitative agreement with some experimental and numerical results. The Fahraeus and the Fahraeus-Lindqvist effects were reproduced. The proposed LBM model provides a flexible numerical platform consisting of various modules which could be used separately or in combination for the study of a variety of colloids and biological suspensions flow deformation problems.

Farhat, Hassan

413

Enabling Data Fusion via a Common Data Model and Programming Interface  

NASA Astrophysics Data System (ADS)

Much progress has been made in scientific data interoperability, especially in the areas of metadata and discovery. However, while a data user may have improved techniques for finding data, there is often a large chasm to span when it comes to acquiring the desired subsets of various datasets and integrating them into a data processing environment. Some tools such as OPeNDAP servers and the Unidata Common Data Model (CDM) have introduced improved abstractions for accessing data via a common interface, but they alone do not go far enough to enable fusion of data from multidisciplinary sources. Although data from various scientific disciplines may represent semantically similar concepts (e.g. time series), the user may face widely varying structural representations of the data (e.g. row versus column oriented), not to mention radically different storage formats. It is not enough to convert data to a common format. The key to fusing scientific data is to represent each dataset with consistent sampling. This can best be done by using a data model that expresses the functional relationship that each dataset represents. The domain of those functions determines how the data can be combined. The Visualization for Algorithm Development (VisAD) Java API has provided a sophisticated data model for representing the functional nature of scientific datasets for well over a decade. Because VisAD is largely designed for its visualization capabilities, the data model can be cumbersome to use for numerical computation, especially for those not comfortable with Java. Although both VisAD and the implementation of the CDM are written in Java, neither defines a pure Java interface that others could implement and program to, further limiting potential for interoperability. In this talk, we will present a solution for data integration based on a simple discipline-agnostic scientific data model and programming interface that enables a dataset to be defined in terms of three variable types: Scalar (a), Tuple (a,b), and Function (a -> b). These basic building blocks can be combined and nested to represent any arbitrarily complex dataset. For example, a time series of surface temperature and pressure could be represented as: time -> ((lon,lat) -> (T,P)). Our data model is expressed in UML and can be implemented in numerous programming languages. We will demonstrate an implementation of our data model and interface using the Scala programming language. Given its functional programming constructs, sophisticated type system, and other language features, Scala enables us to construct complex data structures that can be manipulated using natural mathematical expressions while taking advantage of the language's ability to operate on collections in parallel. This API will be applied to the problem of assimilating various measurements of the solar spectrum and other proxies from multiple sources to construct a composite Lyman-alpha irradiance dataset.

Lindholm, D. M.; Wilson, A.

2011-12-01

414

FuRIA: A Novel Feature Extraction Algorithm for Brain-Computer Interfaces using Inverse Models and Fuzzy Regions of Interest  

E-print Network

FuRIA: A Novel Feature Extraction Algorithm for Brain-Computer Interfaces using Inverse Models propose a new feature extraction algorithm for Brain-Computer Interfaces (BCIs). This algo- rithm is based reached 84%. I. INTRODUCTION Brain-Computer Interfaces (BCIs) are communication sys- tems that enable

Paris-Sud XI, Université de

415

A high throughput MATLAB program for automated force-curve processing using the AdG polymer model.  

PubMed

Research in understanding biofilm formation is dependent on accurate and representative measurements of the steric forces related to brush on bacterial surfaces. A MATLAB program to analyze force curves from an AFM efficiently, accurately, and with minimal user bias has been developed. The analysis is based on a modified version of the Alexander and de Gennes (AdG) polymer model, which is a function of equilibrium polymer brush length, probe radius, temperature, separation distance, and a density variable. Automating the analysis reduces the amount of time required to process 100 force curves from several days to less than 2min. The use of this program to crop and fit force curves to the AdG model will allow researchers to ensure proper processing of large amounts of experimental data and reduce the time required for analysis and comparison of data, thereby enabling higher quality results in a shorter period of time. PMID:25448021

O'Connor, Samantha; Gaddis, Rebecca; Anderson, Evan; Camesano, Terri A; Burnham, Nancy A

2015-02-01

416

Statistics of circular interface fluctuations in an off-lattice Eden model  

NASA Astrophysics Data System (ADS)

Scale-invariant fluctuations of growing interfaces are studied for circular clusters of an off-lattice variant of the Eden model, which belongs to the (1 + 1)-dimensional Kardar-Parisi-Zhang (KPZ) universality class. Statistical properties of the height (radius) fluctuations are numerically determined and compared with recent theoretical developments as well as the author's experimental result on growing interfaces in turbulent liquid crystal (Takeuchi and Sano 2012 arXiv:1203.2530). We focus in particular on analytically unsolved properties such as the temporal correlation function and the persistence probability in space and time. Good agreement with the experiment is found in their characteristic quantities, which implies that the geometry-dependent universality of the KPZ class holds here as well, but a few dissimilarities are also found. Finite-time corrections in the cumulants of the distribution are also studied and shown to decay, for the mean, as t-2/3 within the time window of the simulations, instead of t-1/3 which arises as the typical leading term in the previously known cases.

Takeuchi, Kazumasa A.

2012-05-01

417

Automated Quantification and Sizing of Unbranched Filamentous Cyanobacteria by Model-Based Object-Oriented Image Analysis?  

PubMed Central

Quantification and sizing of filamentous cyanobacteria in environmental samples or cultures are time-consuming and are often performed by using manual or semiautomated microscopic analysis. Automation of conventional image analysis is difficult because filaments may exhibit great variations in length and patchy autofluorescence. Moreover, individual filaments frequently cross each other in microscopic preparations, as deduced by modeling. This paper describes a novel approach based on object-oriented image analysis to simultaneously determine (i) filament number, (ii) individual filament lengths, and (iii) the cumulative filament length of unbranched cyanobacterial morphotypes in fluorescent microscope images in a fully automated high-throughput manner. Special emphasis was placed on correct detection of overlapping objects by image analysis and on appropriate coverage of filament length distribution by using large composite images. The method was validated with a data set for Planktothrix rubescens from field samples and was compared with manual filament tracing, the line intercept method, and the Utermöhl counting approach. The computer program described allows batch processing of large images from any appropriate source and annotation of detected filaments. It requires no user interaction, is available free, and thus might be a useful tool for basic research and drinking water quality control. PMID:20048059

Zeder, Michael; Van den Wyngaert, Silke; Köster, Oliver; Felder, Kathrin M.; Pernthaler, Jakob

2010-01-01

418

SPATIALLY EXPLICIT MICRO-LEVEL MODELLING OF LAND USE CHANGE AT THE RURAL-URBAN INTERFACE. (R828012)  

EPA Science Inventory

This paper describes micro-economic models of land use change applicable to the rural–urban interface in the US. Use of a spatially explicit micro-level modelling approach permits the analysis of regional patterns of land use as the aggregate outcomes of many, disparate...

419

Power Modeling of Graphical User Interfaces on OLED Mian Dong Yung-Seok Kevin Choi Lin Zhong  

E-print Network

Power Modeling of Graphical User Interfaces on OLED Displays Mian Dong Yung-Seok Kevin Choi Lin1,lzhong}@rice.edu ABSTRACT Emerging organic light-emitting diode (OLED)-based displays obviate to their emissive nature. This creates a pressing need for OLED display power models for system energy management

Zhong, Lin

420

Bayesian calibration, validation, and uncertainty quantification of diffuse interface models of tumor growth.  

PubMed

The idea that one can possibly develop computational models that predict the emergence, growth, or decline of tumors in living tissue is enormously intriguing as such predictions could revolutionize medicine and bring a new paradigm into the treatment and prevention of a class of the deadliest maladies affecting humankind. But at the heart of this subject is the notion of predictability itself, the ambiguity involved in selecting and implementing effective models, and the acquisition of relevant data, all factors that contribute to the difficulty of predicting such complex events as tumor growth with quantifiable uncertainty. In this work, we attempt to lay out a framework, based on Bayesian probability, for systematically addressing the questions of Validation, the process of investigating the accuracy with which a mathematical model is able to reproduce particular physical events, and Uncertainty quantification, developing measures of the degree of confidence with which a computer model predicts particular quantities of interest. For illustrative purposes, we exercise the process using virtual data for models of tumor growth based on diffuse-interface theories of mixtures utilizing virtual data. PMID:23053536

Hawkins-Daarud, Andrea; Prudhomme, Serge; van der Zee, Kristoffer G; Oden, J Tinsley

2013-12-01

421

Brain-computer interface with language model-EEG fusion for locked-in syndrome  

PubMed Central

Background Some non-invasive brain computer interface (BCI) systems are currently available for locked-in syndrome (LIS) but none have incorporated a statistical language model during text generation. Objective To begin to address the communication needs of individuals with LIS using a non-invasive BCI that involves Rapid Serial Visual Presentation (RSVP) of symbols and a unique classifier with EEG and language model fusion. Methods The RSVP Keyboard™ was developed with several unique features. Individual letters are presented at 2.5 per sec. Computer classification of letters as targets or non-targets based on EEG is performed using machine learning that incorporates a language model for letter prediction via Bayesian fusion enabling targets to be presented only 1–4 times. Nine participants with LIS and nine healthy controls were enrolled. After screening, subjects first calibrated the system, and then completed a series of balanced word generation mastery tasks that were designed with five incremental levels of difficulty, that increased by selecting phrases for which the utility of the language model decreased naturally. Results Six participants with LIS and nine controls completed the experiment. All LIS participants successfully mastered spelling at level one and one subject achieved level five. Six of nine control participants achieved level five. Conclusions Individuals who have incomplete LIS may benefit from an EEG-based BCI system, which relies on EEG classification and a statistical language model. Steps to further improve the system are discussed. PMID:24370570

Oken, Barry S.; Orhan, Umut; Roark, Brian; Erdogmus, Deniz; Fowler, Andrew; Mooney, Aimee; Peters, Betts; Miller, Meghan; Fried-Oken, Melanie B.

2013-01-01

422

Conceptual model analysis of interaction at a concrete-Boom Clay interface  

NASA Astrophysics Data System (ADS)

In many concepts for deep disposal of high-level radioactive waste, cementitious materials are used in the engineered barriers. For example, in Belgium the engineered barrier system is based on a considerable amount of cementitious materials as buffer and backfill in the so-called supercontainer embedded in the hosting geological formation. A potential hosting formation is Boom Clay. Insight in the interaction between the high-pH pore water of the cementitious materials and neutral-pH Boom Clay pore water is required. Two problems are quite common for modeling of such a system. The first one is the computational cost due to the long timescale model assessments envisaged for the deep disposal system. Also a very fine grid (in sub-millimeter), especially at interfaces has to be used in order to accurately predict the evolution of the system. The second one is whether to use equilibrium or kinetic reaction models. The objectives of this paper are twofold. First, we develop an efficient coupled reactive transport code for this diffusion-dominated system by making full use of multi-processors/cores computers. Second, we investigate how sensitive the system is to chemical reaction models especially when pore clogging due to mineral precipitation is considered within the cementitious system. To do this, we selected two portlandite dissolution models, i.e., equilibrium (fastest) and diffusion-controlled model with precipitation of a calcite layer around portlandite particles (diffusion-controlled dissolution). The results show that with shrinking core model portlandite dissolution and calcite precipitation are much slower than with the equilibrium model. Also diffusion-controlled dissolution smooths out dissolution fronts compared to the equilibrium model. However, only a slight difference with respect to the clogging time can be found even though we use a very small diffusion coefficient (10-20 m2/s) in the precipitated calcite layer.

Liu, Sanheng; Jacques, Diederik; Govaerts, Joan; Wang, Lian

423

ModelOMatic: Fast and Automated Model Selection between RY, Nucleotide, Amino Acid, and Codon Substitution Models.  

PubMed

Molecular phylogenetics is a powerful tool for inferring both the process and pattern of evolution from genomic sequence data. Statistical approaches, such as maximum likelihood and Bayesian inference, are now established as the preferred methods of inference. The choice of models that a researcher uses for inference is of critical importance, and there are established methods for model selection conditioned on a particular type of data, such as nucleotides, amino acids, or codons. A major limitation of existing model selection approaches is that they can only compare models acting upon a single type of data. Here, we extend model selection to allow comparisons between models describing different types of data by introducing the idea of adapter functions, which project aggregated models onto the originally observed sequence data. These projections are implemented in the program ModelOMatic and used to perform model selection on 3722 families from the PANDIT database, 68 genes from an arthropod phylogenomic data set, and 248 genes from a vertebrate phylogenomic data set. For the PANDIT and arthropod data, we find that amino acid models are selected for the overwhelming majority of alignments; with progressively smaller numbers of alignments selecting codon and nucleotide models, and no families selecting RY-based models. In contrast, nearly all alignments from the vertebrate data set select codon-based models. The sequence divergence, the number of sequences, and the degree of selection acting upon the protein sequences may contribute to explaining this variation in model selection. Our ModelOMatic program is fast, with most families from PANDIT taking fewer than 150 s to complete, and should therefore be easily incorporated into existing phylogenetic pipelines. ModelOMatic is available at https://code.google.com/p/modelomatic/. PMID:25209223

Whelan, Simon; Allen, James E; Blackburne, Benjamin P; Talavera, David

2015-01-01

424

Pore-scale modelling of two-phase and three-phase fracture-matrix interface conditions  

NASA Astrophysics Data System (ADS)

A key assumption of multi-phase discrete fracture model simulations is that the capillary pressure is constant and continuous at nodes that are shared by the fracture as well as by the matrix. In this work, we study the fundamental flow physics at the fracture-matrix interface using a 3D pore-scale network model. The conceptual model represents the pores of the matrix and fracture for the situation where the fluid flow is perpendicular to the interface plane, hence mimicking counter-current imbibition. We could not validate the general assumption that the capillary pressure at the interface is continuous directly. Instead it was inferred from the study of the flow pattern across it. By determining the capillary pressure curves individually for the fracture and matrix individually and comparing it with the capillary pressure of the heterogeneous fracture-matrix interface, we were able to develop a qualitative understanding of the trapping behaviour and the residual phase saturations. In general, our simulations show how the wetting phase fills preferentially the smallest pores while the non-wetting phase fills the largest pores. However, the heterogeneity at the fracture-matrix interface gives rise to complex new capillary pressure curves that cannot be modeled by classical Brooks-Corey or van Genuchten curves. We observed that hysteresis effects increase with increasingly more heterogeneous the media. This implies that two different capillary pressure curves should be used for drainage and imbibition.

Abdev, J.; Geiger, S.; van Dijke, R.

2007-12-01

425

AUTOMATED FORCE FIELD PARAMETERIZATION FOR NON-POLARIZABLE AND POLARIZABLE ATOMIC MODELS BASED ON AB INITIO TARGET DATA  

PubMed Central

Classical molecular dynamics (MD) simulations based on atomistic models are increasingly used to study a wide range of biological systems. A prerequisite for meaningful results from such simulations is an accurate molecular mechanical force field. Most biomolecular simulations are currently based on the widely used AMBER and CHARMM force fields, which were parameterized and optimized to cover a small set of basic compounds corresponding to the natural amino acids and nucleic acid bases. Atomic models of additional compounds are commonly generated by analogy to the parameter set of a given force field. While this procedure yields models that are internally consistent, the accuracy of the resulting models can be limited. In this work, we propose a method, General Automated Atomic Model Parameterization (GAAMP), for generating automatically the parameters of atomic models of small molecules using the results from ab initio quantum mechanical (QM) calculations as target data. Force fields that were previously developed for a wide range of model compounds serve as initial guess, although any of the final parameter can be optimized. The electrostatic parameters (partial charges, polarizabilities and shielding) are optimized on the basis of QM electrostatic potential (ESP) and, if applicable, the interaction energies between the compound and water molecules. The soft dihedrals are automatically identified and parameterized by targeting QM dihedral scans as well as the energies of stable conformers. To validate the approach, the solvation free energy is calculated for more than 200 small molecules and MD simulations of 3 different proteins are carried out. PMID:24223528

Huang, Lei; Roux, Benoît

2013-01-01

426

Interfaces, strings, and a soft mode in the square lattice quantum dimer model  

NASA Astrophysics Data System (ADS)

The quantum dimer model on the square lattice is a U(1 ) gauge theory that addresses aspects of the physics of high-Tc superconductors. Using a quantum Monte Carlo method, we show that the theory exists in a confining columnar valence bond solid phase. The interfaces separating distinct columnar phases display plaquette order, which, however, is not realized as a bulk phase. Static "electric" charges are confined by flux tubes that consist of multiple strands, each carrying a fractionalized flux 1/4 . A soft pseudo-Goldstone mode (which becomes exactly massless at the Rokhsar-Kivelson point) extends deep into the columnar phase, with potential implications for high-Tc physics.

Banerjee, D.; Bögli, M.; Hofmann, C. P.; Jiang, F.-J.; Widmer, P.; Wiese, U.-J.

2014-12-01