Science.gov

Sample records for interface based model

  1. Systems Engineering Interfaces: A Model Based Approach

    NASA Technical Reports Server (NTRS)

    Fosse, Elyse; Delp, Christopher

    2013-01-01

    Currently: Ops Rev developed and maintains a framework that includes interface-specific language, patterns, and Viewpoints. Ops Rev implements the framework to design MOS 2.0 and its 5 Mission Services. Implementation de-couples interfaces and instances of interaction Future: A Mission MOSE implements the approach and uses the model based artifacts for reviews. The framework extends further into the ground data layers and provides a unified methodology.

  2. Systems Engineering Interfaces: A Model Based Approach

    NASA Technical Reports Server (NTRS)

    Fosse, Elyse; Delp, Christopher

    2013-01-01

    Currently: Ops Rev developed and maintains a framework that includes interface-specific language, patterns, and Viewpoints. Ops Rev implements the framework to design MOS 2.0 and its 5 Mission Services. Implementation de-couples interfaces and instances of interaction Future: A Mission MOSE implements the approach and uses the model based artifacts for reviews. The framework extends further into the ground data layers and provides a unified methodology.

  3. A model neural interface based on functional chemical stimulation.

    PubMed

    Mehenti, Neville Z; Fishman, Harvey A; Bent, Stacey F

    2007-08-01

    While functional electrical stimulation has been applied to treat a variety of neurological disorders, it cannot mimic function that is primarily achieved using neurochemical means. In this work, we present a neurotransmitter-based prosthetic interface in the form of a flexible microdevice that selectively releases chemical pulses through an aperture in a polymer membrane. The release profiles through the aperture are controlled by microfluidic switching in an underlying channel network. The profiles have been characterized using fluorescence microscopy as a function of pulse duration and frequency. Hippocampal neurons were cultured on the microdevices and cell stimulation via glutamate delivery was detected using calcium imaging. The release properties could be tuned to repeatedly elicit discrete action potentials in cells seeded proximate to the aperture, including single cell stimulation at 2 Hz. This model neural interface based on functional chemical stimulation may provide the biomimetic platform necessary to restore physiological pathways and function that electrical stimulation cannot fundamentally address.

  4. Interface Management for a NASA Flight Project Using Model-Based Systems Engineering (MBSE)

    NASA Technical Reports Server (NTRS)

    Vipavetz, Kevin; Shull, Thomas A.; Infeld, Samatha; Price, Jim

    2016-01-01

    The goal of interface management is to identify, define, control, and verify interfaces; ensure compatibility; provide an efficient system development; be on time and within budget; while meeting stakeholder requirements. This paper will present a successful seven-step approach to interface management used in several NASA flight projects. The seven-step approach using Model Based Systems Engineering will be illustrated by interface examples from the Materials International Space Station Experiment-X (MISSE-X) project. The MISSE-X was being developed as an International Space Station (ISS) external platform for space environmental studies, designed to advance the technology readiness of materials and devices critical for future space exploration. Emphasis will be given to best practices covering key areas such as interface definition, writing good interface requirements, utilizing interface working groups, developing and controlling interface documents, handling interface agreements, the use of shadow documents, the importance of interface requirement ownership, interface verification, and product transition.

  5. Model Based Control Design Using SLPS "Simulink PSpice Interface"

    NASA Astrophysics Data System (ADS)

    Moslehpour, Saeid; Kulcu, Ercan K.; Alnajjar, Hisham

    This paper elaborates on the new integration offered with the PSpice SLPS interface and the MATLAB simulink products. SLPS links the two widely used design products, PSpice and Mathwork's Simulink simulator. The SLPS simulation environment supports the substitution of an actual electronic block with an "ideal model", better known as the mathematical simulink model. Thus enabling the designer to identify and correct integration issues of electronics within a system. Moreover, stress audit can be performed by using the PSpice smoke analysis which helps to verify whether the components are working within the manufacturer's safe operating limits. It is invaluable since many companies design and test the electronics separately from the system level. Therefore, integrations usually are not discovered until the prototype level, causing critical time delays in getting a product to the market.

  6. Relating Interface Evolution to Interface Mechanics Based on Interface Properties

    NASA Astrophysics Data System (ADS)

    Verma, Devendra; Biswas, Sudipta; Prakash, Chandra; Tomar, Vikas

    2017-01-01

    The current article focuses on recent work done in understanding the role of processing techniques on interface evolution and connecting interface evolution to interface thickness-dependent properties. Special emphasis is placed on interface evolution during the sintering process of tungsten ( W). Sintering with additives such as nickel significantly changes grain boundary properties in W, leading to issues such as grain boundary embrittlement. When one has to mechanically describe properties of polycrystalline W with an account of the influence of grain boundary embrittlement, one must explicitly consider grain boundary properties. This issue is the focus of the present work on the mechanical properties of interfaces. Overall, a phase field modeling-based approach is shown to be an excellent computational tool for predicting the interface evolution. The influences of the interface thickness, chemistry, and orientation of phases around interfaces are analyzed using extended finite element simulations for polycrystalline W.

  7. A gradient-descent-based approach for transparent linguistic interface generation in fuzzy models.

    PubMed

    Chen, Long; Chen, C L Philip; Pedrycz, Witold

    2010-10-01

    Linguistic interface is a group of linguistic terms or fuzzy descriptions that describe variables in a system utilizing corresponding membership functions. Its transparency completely or partly decides the interpretability of fuzzy models. This paper proposes a GRadiEnt-descEnt-based Transparent lInguistic iNterface Generation (GREETING) approach to overcome the disadvantage of traditional linguistic interface generation methods where the consideration of the interpretability aspects of linguistic interface is limited. In GREETING, the widely used interpretability criteria of linguistic interface are considered and optimized. The numeric experiments on the data sets from University of California, Irvine (UCI) machine learning databases demonstrate the feasibility and superiority of the proposed GREETING method. The GREETING method is also applied to fuzzy decision tree generation. It is shown that GREETING generates better transparent fuzzy decision trees in terms of better classification rates and comparable tree sizes.

  8. A method of designing smartphone interface based on the extended user's mental model

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Li, Fengmin; Bian, Jiali; Pan, Juchen; Song, Song

    2017-01-01

    The user's mental model is the core guiding theory of product design, especially practical products. The essence of practical product is a tool which is used by users to meet their needs. Then, the most important feature of a tool is usability. The design method based on the user's mental model provides a series of practical and feasible theoretical guidance for improving the usability of the product according to the user's awareness of things. In this paper, we propose a method of designing smartphone interface based on the extended user's mental model according to further research on user groups. This approach achieves personalized customization of smartphone application interface and enhance application using efficiency.

  9. Approximation of skewed interfaces with tensor-based model reduction procedures: Application to the reduced basis hierarchical model reduction approach

    NASA Astrophysics Data System (ADS)

    Ohlberger, Mario; Smetana, Kathrin

    2016-09-01

    In this article we introduce a procedure, which allows to recover the potentially very good approximation properties of tensor-based model reduction procedures for the solution of partial differential equations in the presence of interfaces or strong gradients in the solution which are skewed with respect to the coordinate axes. The two key ideas are the location of the interface either by solving a lower-dimensional partial differential equation or by using data functions and the subsequent removal of the interface of the solution by choosing the determined interface as the lifting function of the Dirichlet boundary conditions. We demonstrate in numerical experiments for linear elliptic equations and the reduced basis-hierarchical model reduction approach that the proposed procedure locates the interface well and yields a significantly improved convergence behavior even in the case when we only consider an approximation of the interface.

  10. Interfacing Physiologically-Based Pharmacokinetic Modeling and Simulation Systems

    DTIC Science & Technology

    1992-01-01

    8217: a simulation of drug dispo- sition in the human body : applications in clinical pharmacokinctics. Br. J. Clin. Pharmacol. 10, 591--602. D’Souza, R.D...physiological processes which can model (tissues) and the anatomical struture of each tissue; affect the distribution and flux of a substance: transport 2... humans the investigator must rely on in vitro or animal properties of the substance (tissue partition coefficients). studies. The graphical user

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

    NASA Astrophysics Data System (ADS)

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

    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.

  12. A Theoretical Contact Mechanics Model of Machine Joint Interfaces Based on Fractal Theory

    NASA Astrophysics Data System (ADS)

    Liu, Wenwei; Wang, Yuanhang; Li, Xiaobing; Huang, Chuangmian; Yang, Jianfeng; Pan, GuangZe; Ding, Xiaojian

    2017-06-01

    To obtain more accurate contact mechanics model of joint interfaces theoretically, A theoretical contact mechanics model of joint interfaces based on fractal theory was proposed. An improved 3D WM fractal function was used to characterize the contact surface, contact load and contact area equations of asperities in elastoplastic deformation regime were established, solutions for the relationships of area-displacement and force-displacement in the elastoplastic deformation regime was done based on Hertz contact theory and fractal theory, and the present model was proven to be effective by comparing the present model to other four classical contact models and test data. Furthermore, simulations and numerical calculation results reveal nonlinear relation between the influence factors and the contact area.

  13. A prototype natural language interface to a large complex knowledge base, the Foundational Model of Anatomy.

    PubMed

    Distelhorst, Gregory; Srivastava, Vishrut; Rosse, Cornelius; Brinkley, James F

    2003-01-01

    We describe a constrained natural language interface to a large knowledge base, the Foundational Model of Anatomy (FMA). The interface, called GAPP, handles simple or nested questions that can be parsed to the form, subject-relation-object, where subject or object is unknown. With the aid of domain-specific dictionaries the parsed sentence is converted to queries in the StruQL graph-searching query language, then sent to a server we developed, called OQAFMA, that queries the FMA and returns output as XML. Preliminary evaluation shows that GAPP has the potential to be used in the evaluation of the FMA by domain experts in anatomy.

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

    NASA Astrophysics Data System (ADS)

    Cao, Y.; Ames, D. P.

    2011-12-01

    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

  15. Implementing a Multiple Criteria Model Base in Co-Op with a Graphical User Interface Generator

    DTIC Science & Technology

    1993-09-23

    Decision Support System (Co-op) for Windows. The algorithms and the graphical user interfaces for these modules are implemented using Microsoft Visual ... Basic under the Windows based environment operating in a IBM compatible microcomputer. Design of the MCDM programs interface is based on general interface design principles of user control, screen design, and layout.

  16. Interface design and human factors considerations for model-based tight glycemic control in critical care.

    PubMed

    Ward, Logan; Steel, James; Le Compte, Aaron; Evans, Alicia; Tan, Chia-Siong; Penning, Sophie; Shaw, Geoffrey M; Desaive, Thomas; Chase, J Geoffrey

    2012-01-01

    Tight glycemic control (TGC) has shown benefits but has been difficult to implement. Model-based methods and computerized protocols offer the opportunity to improve TGC quality and compliance. This research presents an interface design to maximize compliance, minimize real and perceived clinical effort, and minimize error based on simple human factors and end user input. The graphical user interface (GUI) design is presented by construction based on a series of simple, short design criteria based on fundamental human factors engineering and includes the use of user feedback and focus groups comprising nursing staff at Christchurch Hospital. The overall design maximizes ease of use and minimizes (unnecessary) interaction and use. It is coupled to a protocol that allows nurse staff to select measurement intervals and thus self-manage workload. The overall GUI design is presented and requires only one data entry point per intervention cycle. The design and main interface are heavily focused on the nurse end users who are the predominant users, while additional detailed and longitudinal data, which are of interest to doctors guiding overall patient care, are available via tabs. This dichotomy of needs and interests based on the end user's immediate focus and goals shows how interfaces must adapt to offer different information to multiple types of users. The interface is designed to minimize real and perceived clinical effort, and ongoing pilot trials have reported high levels of acceptance. The overall design principles, approach, and testing methods are based on fundamental human factors principles designed to reduce user effort and error and are readily generalizable. © 2012 Diabetes Technology Society.

  17. U-10Mo/Zr Interface Modeling using a Microstructure-Based FEM Approach

    SciTech Connect

    Soulami, Ayoub; Xu, Zhijie; Joshi, Vineet V.; Burkes, Douglas; Lavender, Curt A.; McGarrah, Eric J.

    2016-04-25

    The U-10Mo in low enrichments (LEU) has been identified as the most promising alternative to the current highly enriched uranium (HEU) used in the United States’ fleet of high performance research reactors (USHPRRs). The nominal configuration of the new LEU U-10Mo plate fuel comprises a U-10Mo fuel foil enriched to slightly less than 20% U-235 (0.08” to 0.02” thick), a thin Zr interlayer/diffusion barrier (25 m thick) and a relatively thick outer can of 6061 aluminum. Currently the Zr interlayer is clad by hot roll bonding. Previous studies and observations revealed a thinning of the zirconium (Zr) layer during this fuel fabrication process, which is not desirable from the fuel performance perspective. Coarse UMo grains, dendritic structures, Mo concentration segregation, carbides, and porosity are present in the as-cast material and can lead to a nonuniform UMo/Zr interface. The purpose of the current work is to investigate the effects of these microstructural parameters on the Zr coating variation. A microstructure-based finite-element method model was used in this work, and a study on the effect of homogenization on the interface between U-10Mo and Zr was conducted. The model uses actual backscattered electron–scanning electron microscopy microstructures, Mo concentrations, and mechanical properties to predict the behavior of a representative volume element under compressive loading during the rolling process. The model successfully predicted the experimentally observed thinning of the Zr layer in the as-cast material. The model also uses results from a homogenization model as an input, and a study on the effect of different levels of homogenization on the interface indicated that homogenization helps decrease this thinning. This model can be considered a predictive tool representing a first step for model integration and an input into a larger fuel fabrication performance model.

  18. Operating Comfort Prediction Model of Human-Machine Interface Layout for Cabin Based on GEP.

    PubMed

    Deng, Li; Wang, Guohua; Chen, Bo

    2015-01-01

    In view of the evaluation and decision-making problem of human-machine interface layout design for cabin, the operating comfort prediction model is proposed based on GEP (Gene Expression Programming), using operating comfort to evaluate layout scheme. Through joint angles to describe operating posture of upper limb, the joint angles are taken as independent variables to establish the comfort model of operating posture. Factor analysis is adopted to decrease the variable dimension; the model's input variables are reduced from 16 joint angles to 4 comfort impact factors, and the output variable is operating comfort score. The Chinese virtual human body model is built by CATIA software, which will be used to simulate and evaluate the operators' operating comfort. With 22 groups of evaluation data as training sample and validation sample, GEP algorithm is used to obtain the best fitting function between the joint angles and the operating comfort; then, operating comfort can be predicted quantitatively. The operating comfort prediction result of human-machine interface layout of driller control room shows that operating comfort prediction model based on GEP is fast and efficient, it has good prediction effect, and it can improve the design efficiency.

  19. Operating Comfort Prediction Model of Human-Machine Interface Layout for Cabin Based on GEP

    PubMed Central

    Deng, Li; Wang, Guohua; Chen, Bo

    2015-01-01

    In view of the evaluation and decision-making problem of human-machine interface layout design for cabin, the operating comfort prediction model is proposed based on GEP (Gene Expression Programming), using operating comfort to evaluate layout scheme. Through joint angles to describe operating posture of upper limb, the joint angles are taken as independent variables to establish the comfort model of operating posture. Factor analysis is adopted to decrease the variable dimension; the model's input variables are reduced from 16 joint angles to 4 comfort impact factors, and the output variable is operating comfort score. The Chinese virtual human body model is built by CATIA software, which will be used to simulate and evaluate the operators' operating comfort. With 22 groups of evaluation data as training sample and validation sample, GEP algorithm is used to obtain the best fitting function between the joint angles and the operating comfort; then, operating comfort can be predicted quantitatively. The operating comfort prediction result of human-machine interface layout of driller control room shows that operating comfort prediction model based on GEP is fast and efficient, it has good prediction effect, and it can improve the design efficiency. PMID:26448740

  20. Establishing a novel modeling tool: a python-based interface for a neuromorphic hardware system.

    PubMed

    Brüderle, Daniel; Müller, Eric; Davison, Andrew; Muller, Eilif; Schemmel, Johannes; Meier, Karlheinz

    2009-01-01

    Neuromorphic hardware systems provide new possibilities for the neuroscience modeling community. Due to the intrinsic parallelism of the micro-electronic emulation of neural computation, such models are highly scalable without a loss of speed. However, the communities of software simulator users and neuromorphic engineering in neuroscience are rather disjoint. We present a software concept that provides the possibility to establish such hardware devices as valuable modeling tools. It is based on the integration of the hardware interface into a simulator-independent language which allows for unified experiment descriptions that can be run on various simulation platforms without modification, implying experiment portability and a huge simplification of the quantitative comparison of hardware and simulator results. We introduce an accelerated neuromorphic hardware device and describe the implementation of the proposed concept for this system. An example setup and results acquired by utilizing both the hardware system and a software simulator are demonstrated.

  1. Establishing a Novel Modeling Tool: A Python-Based Interface for a Neuromorphic Hardware System

    PubMed Central

    Brüderle, Daniel; Müller, Eric; Davison, Andrew; Muller, Eilif; Schemmel, Johannes; Meier, Karlheinz

    2008-01-01

    Neuromorphic hardware systems provide new possibilities for the neuroscience modeling community. Due to the intrinsic parallelism of the micro-electronic emulation of neural computation, such models are highly scalable without a loss of speed. However, the communities of software simulator users and neuromorphic engineering in neuroscience are rather disjoint. We present a software concept that provides the possibility to establish such hardware devices as valuable modeling tools. It is based on the integration of the hardware interface into a simulator-independent language which allows for unified experiment descriptions that can be run on various simulation platforms without modification, implying experiment portability and a huge simplification of the quantitative comparison of hardware and simulator results. We introduce an accelerated neuromorphic hardware device and describe the implementation of the proposed concept for this system. An example setup and results acquired by utilizing both the hardware system and a software simulator are demonstrated. PMID:19562085

  2. Toward a model-based predictive controller design in brain-computer interfaces.

    PubMed

    Kamrunnahar, M; Dias, N S; Schiff, S J

    2011-05-01

    A first step in designing a robust and optimal model-based predictive controller (MPC) for brain-computer interface (BCI) applications is presented in this article. An MPC has the potential to achieve improved BCI performance compared to the performance achieved by current ad hoc, nonmodel-based filter applications. The parameters in designing the controller were extracted as model-based features from motor imagery task-related human scalp electroencephalography. Although the parameters can be generated from any model-linear or non-linear, we here adopted a simple autoregressive model that has well-established applications in BCI task discriminations. It was shown that the parameters generated for the controller design can as well be used for motor imagery task discriminations with performance (with 8-23% task discrimination errors) comparable to the discrimination performance of the commonly used features such as frequency specific band powers and the AR model parameters directly used. An optimal MPC has significant implications for high performance BCI applications.

  3. Toward a Model-Based Predictive Controller Design in Brain–Computer Interfaces

    PubMed Central

    Kamrunnahar, M.; Dias, N. S.; Schiff, S. J.

    2013-01-01

    A first step in designing a robust and optimal model-based predictive controller (MPC) for brain–computer interface (BCI) applications is presented in this article. An MPC has the potential to achieve improved BCI performance compared to the performance achieved by current ad hoc, nonmodel-based filter applications. The parameters in designing the controller were extracted as model-based features from motor imagery task-related human scalp electroencephalography. Although the parameters can be generated from any model-linear or non-linear, we here adopted a simple autoregressive model that has well-established applications in BCI task discriminations. It was shown that the parameters generated for the controller design can as well be used for motor imagery task discriminations with performance (with 8–23% task discrimination errors) comparable to the discrimination performance of the commonly used features such as frequency specific band powers and the AR model parameters directly used. An optimal MPC has significant implications for high performance BCI applications. PMID:21267657

  4. Sensorimotor rhythm-based brain computer interface (BCI): model order selection for autoregressive spectral analysis

    NASA Astrophysics Data System (ADS)

    McFarland, Dennis J.; Wolpaw, Jonathan R.

    2008-06-01

    People can learn to control EEG features consisting of sensorimotor rhythm amplitudes and can use this control to move a cursor in one or two dimensions to a target on a screen. Cursor movement depends on the estimate of the amplitudes of sensorimotor rhythms. Autoregressive models are often used to provide these estimates. The order of the autoregressive model has varied widely among studies. Through analyses of both simulated and actual EEG data, the present study examines the effects of model order on sensorimotor rhythm measurements and BCI performance. The results show that resolution of lower frequency signals requires higher model orders and that this requirement reflects the temporal span of the model coefficients. This is true for both simulated EEG data and actual EEG data during brain-computer interface (BCI) operation. Increasing model order, and decimating the signal were similarly effective in increasing spectral resolution. Furthermore, for BCI control of two-dimensional cursor movement, higher model orders produced better performance in each dimension and greater independence between horizontal and vertical movements. In sum, these results show that autoregressive model order selection is an important determinant of BCI performance and should be based on criteria that reflect system performance.

  5. Illustration interface of accident progression in PWR by quick inference based on multilevel flow models

    SciTech Connect

    Yoshikawa, H.; Ouyang, J.; Niwa, Y.

    2006-07-01

    In this paper, a new accident inference method is proposed by using a goal and function oriented modeling method called Multilevel Flow Model focusing on explaining the causal-consequence relations and the objective of automatic action in the accident of nuclear power plant. Users can easily grasp how the various plant parameters will behave and how the various safety facilities will be activated sequentially to cope with the accident until the nuclear power plants are settled into safety state, i.e., shutdown state. The applicability of the developed method was validated by the conduction of internet-based 'view' experiment to the voluntary respondents, and in the future, further elaboration of interface design and the further introduction of instruction contents will be developed to make it become the usable CAI system. (authors)

  6. Horizontal annular flow modelling using a compositional based interface capturing approach

    NASA Astrophysics Data System (ADS)

    Pavlidis, Dimitrios; Xie, Zhizhua; Percival, James; Gomes, Jefferson; Pain, Chris; Matar, Omar

    2014-11-01

    Progress on a consistent approach for interface-capturing in which each component represents a different phase/fluid is described. The aim is to develop a general multi-phase modelling approach based on fully-unstructured meshes that can exploit the latest mesh adaptivity methods, and in which each fluid phase may have a number of components. The method is compared against experimental results for a collapsing water column test case and a convergence study is performed. A number of numerical test cases are undertaken to demonstrate the method's ability to model arbitrary numbers of phases with arbitrary equations of state. The method is then used to simulate horizontal annular flows. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  7. Lyo code generator: A model-based code generator for the development of OSLC-compliant tool interfaces

    NASA Astrophysics Data System (ADS)

    El-khoury, Jad

    To promote the newly emerging OSLC (Open Services for Lifecycle Collaboration) tool interoperability standard, an open source code generator is developed that allows for the specification of OSLC-compliant tool interfaces, and from which almost complete Java code of the interface can be generated. The software takes a model-based development approach to tool interoperability, with the aim of providing modeling support for the complete development cycle of a tool interface. The software targets both OSLC developers, as well as the interoperability research community, with proven capabilities to be extended to support their corresponding needs.

  8. An optimization-based study of equivalent circuit models for representing recordings at the neuron-electrode interface.

    PubMed

    Thakore, V; Molnar, P; Hickman, J J

    2012-08-01

    Extracellular neuroelectronic interfacing is an emerging field with important applications in the fields of neural prosthetics, biological computation, and biosensors. Traditionally, neuron-electrode interfaces have been modeled as linear point or area contact equivalent circuits but it is now being increasingly realized that such models cannot explain the shapes and magnitudes of the observed extracellular signals. Here, results were compared and contrasted from an unprecedented optimization-based study of the point contact models for an extracellular "on-cell" neuron-patch electrode and a planar neuron-microelectrode interface. Concurrent electrophysiological recordings from a single neuron simultaneously interfaced to three distinct electrodes (intracellular, "on-cell" patch, and planar microelectrode) allowed novel insights into the mechanism of signal transduction at the neuron-electrode interface. After a systematic isolation of the nonlinear neuronal contribution to the extracellular signal, a consistent underestimation of the simulated suprathreshold extracellular signals compared to the experimentally recorded signals was observed. This conclusively demonstrated that the dynamics of the interfacial medium contribute nonlinearly to the process of signal transduction at the neuron-electrode interface. Further, an examination of the optimized model parameters for the experimental extracellular recordings from sub- and suprathreshold stimulations of the neuron-electrode junctions revealed that ionic transport at the "on-cell" neuron-patch electrode is dominated by diffusion whereas at the neuron-microelectrode interface the electric double layer (EDL) effects dominate. Based on this study, the limitations of the equivalent circuit models in their failure to account for the nonlinear EDL and ionic electrodiffusion effects occurring during signal transduction at the neuron-electrode interfaces are discussed.

  9. A microfluidics-based in vitro model of the gastrointestinal human–microbe interface

    PubMed Central

    Shah, Pranjul; Fritz, Joëlle V.; Glaab, Enrico; Desai, Mahesh S.; Greenhalgh, Kacy; Frachet, Audrey; Niegowska, Magdalena; Estes, Matthew; Jäger, Christian; Seguin-Devaux, Carole; Zenhausern, Frederic; Wilmes, Paul

    2016-01-01

    Changes in the human gastrointestinal microbiome are associated with several diseases. To infer causality, experiments in representative models are essential, but widely used animal models exhibit limitations. Here we present a modular, microfluidics-based model (HuMiX, human–microbial crosstalk), which allows co-culture of human and microbial cells under conditions representative of the gastrointestinal human–microbe interface. We demonstrate the ability of HuMiX to recapitulate in vivo transcriptional, metabolic and immunological responses in human intestinal epithelial cells following their co-culture with the commensal Lactobacillus rhamnosus GG (LGG) grown under anaerobic conditions. In addition, we show that the co-culture of human epithelial cells with the obligate anaerobe Bacteroides caccae and LGG results in a transcriptional response, which is distinct from that of a co-culture solely comprising LGG. HuMiX facilitates investigations of host–microbe molecular interactions and provides insights into a range of fundamental research questions linking the gastrointestinal microbiome to human health and disease. PMID:27168102

  10. A microfluidics-based in vitro model of the gastrointestinal human-microbe interface.

    PubMed

    Shah, Pranjul; Fritz, Joëlle V; Glaab, Enrico; Desai, Mahesh S; Greenhalgh, Kacy; Frachet, Audrey; Niegowska, Magdalena; Estes, Matthew; Jäger, Christian; Seguin-Devaux, Carole; Zenhausern, Frederic; Wilmes, Paul

    2016-05-11

    Changes in the human gastrointestinal microbiome are associated with several diseases. To infer causality, experiments in representative models are essential, but widely used animal models exhibit limitations. Here we present a modular, microfluidics-based model (HuMiX, human-microbial crosstalk), which allows co-culture of human and microbial cells under conditions representative of the gastrointestinal human-microbe interface. We demonstrate the ability of HuMiX to recapitulate in vivo transcriptional, metabolic and immunological responses in human intestinal epithelial cells following their co-culture with the commensal Lactobacillus rhamnosus GG (LGG) grown under anaerobic conditions. In addition, we show that the co-culture of human epithelial cells with the obligate anaerobe Bacteroides caccae and LGG results in a transcriptional response, which is distinct from that of a co-culture solely comprising LGG. HuMiX facilitates investigations of host-microbe molecular interactions and provides insights into a range of fundamental research questions linking the gastrointestinal microbiome to human health and disease.

  11. A generative model approach for decoding in the visual event-related potential-based brain-computer interface speller

    NASA Astrophysics Data System (ADS)

    Martens, S. M. M.; Leiva, J. M.

    2010-04-01

    There is a strong tendency towards discriminative approaches in brain-computer interface (BCI) research. We argue that generative model-based approaches are worth pursuing and propose a simple generative model for the visual ERP-based BCI speller which incorporates prior knowledge about the brain signals. We show that the proposed generative method needs less training data to reach a given letter prediction performance than the state of the art discriminative approaches.

  12. Downsizer - A Graphical User Interface-Based Application for Browsing, Acquiring, and Formatting Time-Series Data for Hydrologic Modeling

    USGS Publications Warehouse

    Ward-Garrison, Christian; Markstrom, Steven L.; Hay, Lauren E.

    2009-01-01

    The U.S. Geological Survey Downsizer is a computer application that selects, downloads, verifies, and formats station-based time-series data for environmental-resource models, particularly the Precipitation-Runoff Modeling System. Downsizer implements the client-server software architecture. The client presents a map-based, graphical user interface that is intuitive to modelers; the server provides streamflow and climate time-series data from over 40,000 measurement stations across the United States. This report is the Downsizer user's manual and provides (1) an overview of the software design, (2) installation instructions, (3) a description of the graphical user interface, (4) a description of selected output files, and (5) troubleshooting information.

  13. A chemical-structural model for coherent martensite/parent interface in Mn-based antiferromagnetic shape memory alloys.

    PubMed

    Shi, S; Wan, J F; Zuo, X W; Chen, N L; Zhang, J H; Rong, Y H

    2016-11-21

    The martensite/parent coherent interface of Mn-based shape memory alloys (SMAs) is a significant part in the research of their martensitic transformation, reversible shape memory effect and magnetic shape memory effect. In the present work, a chemical-structural model was proposed to calculate the martensite/parent coherent interfacial energy of Mn-X (X = Cu, Fe) alloys. In this model, the coherent heterophase interfacial energy consists of chemical and structural parts. Resulting from the formation process of the heterophase interface, the chemical interfacial energy is expressed as the incremental value of bond energy, while the structural part is obtained by calculating the interfacial strain energy. The results show that the structural interfacial energy plays the chief role in the total interfacial energy, and the total interfacial energy decreases as the temperature rises when the alloy composition is fixed. In addition, the preferred orientation has noteworthy influence on the total interfacial energy. Using the proposed model, interfacial energy, interfacial entropy, interfacial enthalpy and interfacial heat capacity are found to be correlated with temperature and interface preferred orientation. Furthermore, the influences of alloy composition, modulus softening, and the index of the habit plane on the results were discussed.

  14. A reference model based interface terminology for generic observations in Anatomic Pathology Structured Reports

    PubMed Central

    2014-01-01

    Background Current terminology systems for structured reporting in pathology are more or less focused on tumor pathology. They have not been compiled in a systematic approach, therefore they gather terms of very different granularity. Generic models for terminology development could help in establishing reference terminologies for all fields of anatomic pathology. The core principle of those models is the ontological structure of native speaking terminology. By analyzing the PathLex interface a generic terminology model will be derived. Methods For each element template of PathLex its possible generic nature and its value set was analyzed, looking for the uniqueness or multiplicity of the values in the value sets. The generic terms were mapped to SNOMED-CT terms using "ArtDecor". Results The 488 PathLex element templates for Anatomic Pathology (AP) observations can be reduced to 53 generic templates, leaving out only 17 templates very specific for organ and/or disease. Among those 53 templates 28 are describing UICC-TNM staging, ICD-O-classification, and grading. Further 15 templates describe the results from marker investigations. Almost all of the terms, used in those templates could be mapped to SNOMED CT. All of the generic elements have their "organ specific" counterparts by assigning them to one of 20 organs and invasive or noninvasive cancer, respectively. Studying the structure of generic and specific terms it becomes obvious that any AP observation - occurs always in a context - consists of three basic elements (target of observation, property of observation, additional qualifiers, added by value sets for coded data). Conclusions If a machine-readable terminology is aimed to preserve all the information of native speaking, then two principal solutions exist: - ystematic consideration of all the aspects mentioned above in each single term - ocusing on the generic elements of terms and combining this with the structure of communication, reflecting the non

  15. Improved modeling of side-chain--base interactions and plasticity in protein--DNA interface design.

    PubMed

    Thyme, Summer B; Baker, David; Bradley, Philip

    2012-06-08

    Combinatorial sequence optimization for protein design requires libraries of discrete side-chain conformations. The discreteness of these libraries is problematic, particularly for long, polar side chains, since favorable interactions can be missed. Previously, an approach to loop remodeling where protein backbone movement is directed by side-chain rotamers predicted to form interactions previously observed in native complexes (termed "motifs") was described. Here, we show how such motif libraries can be incorporated into combinatorial sequence optimization protocols and improve native complex recapitulation. Guided by the motif rotamer searches, we made improvements to the underlying energy function, increasing recapitulation of native interactions. To further test the methods, we carried out a comprehensive experimental scan of amino acid preferences in the I-AniI protein-DNA interface and found that many positions tolerated multiple amino acids. This sequence plasticity is not observed in the computational results because of the fixed-backbone approximation of the model. We improved modeling of this diversity by introducing DNA flexibility and reducing the convergence of the simulated annealing algorithm that drives the design process. In addition to serving as a benchmark, this extensive experimental data set provides insight into the types of interactions essential to maintain the function of this potential gene therapy reagent. Published by Elsevier Ltd.

  16. Improved Modeling of Side-Chain–Base Interactions and Plasticity in Protein–DNA Interface Design

    PubMed Central

    Thyme, Summer B.; Baker, David; Bradley, Philip

    2012-01-01

    Combinatorial sequence optimization for protein design requires libraries of discrete side-chain conformations. The discreteness of these libraries is problematic, particularly for long, polar side chains, since favorable interactions can be missed. Previously, an approach to loop remodeling where protein backbone movement is directed by side-chain rotamers predicted to form interactions previously observed in native complexes (termed “motifs”) was described. Here, we show how such motif libraries can be incorporated into combinatorial sequence optimization protocols and improve native complex recapitulation. Guided by the motif rotamer searches, we made improvements to the underlying energy function, increasing recapitulation of native interactions. To further test the methods, we carried out a comprehensive experimental scan of amino acid preferences in the I-AniI protein–DNA interface and found that many positions tolerated multiple amino acids. This sequence plasticity is not observed in the computational results because of the fixed-backbone approximation of the model. We improved modeling of this diversity by introducing DNA flexibility and reducing the convergence of the simulated annealing algorithm that drives the design process. In addition to serving as a benchmark, this extensive experimental data set provides insight into the types of interactions essential to maintain the function of this potential gene therapy reagent. PMID:22426128

  17. A Diffuse Interface Model with Immiscibility Preservation

    PubMed Central

    Tiwari, Arpit; Freund, Jonathan B.; Pantano, Carlos

    2013-01-01

    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. PMID:24058207

  18. A diffuse interface model with immiscibility preservation

    SciTech Connect

    Tiwari, Arpit; Freund, Jonathan B.; Pantano, Carlos

    2013-11-01

    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.

  19. A reference model based interface terminology for generic observations in Anatomic Pathology Structured Reports.

    PubMed

    Haroske, Gunter; Schrader, Thomas

    2014-01-01

    Current terminology systems for structured reporting in pathology are more or less focused on tumor pathology. They have not been compiled in a systematic approach, therefore they gather terms of very different granularity. Generic models for terminology development could help in establishing reference terminologies for all fields of anatomic pathology. For each element template of PathLex its possible generic nature and its value set was analyzed, looking for the uniqueness or multiplicity of the values in the value sets. The 488 PathLex element templates for Anatomic Pathology (AP) observations can be reduced to 53 generic templates, leaving out only 17 templates very specific for organ and/or disease. Among those 53 templates 28 are describing UICC-TNM staging, ICD-O-classification, and grading. Further 15 templates describe the results from marker investigations. Almost all of the terms, used in those templates could be mapped to SNOMED CT. All of the generic elements have their “organ specific” counterparts by assigning them to one of 20 organs and invasive or noninvasive cancer, respectively. Studying the structure of generic and specific terms it becomes obvious that any AP observation: - occurs always in a context; - consists of three basic elements (target of observation, property of observation, additional qualifiers, added by value sets for coded data). If a machine-readable terminology is aimed to preserve all the information of native speaking, then two principal solutions exist: - ystematic consideration of all the aspects mentioned above in each single term; - ocusing on the generic elements of terms and combining this with the structure of communication, reflecting the non-obvious elements of the terminology. The fastest way for establishing an interface terminology is the first approach, which lists all of the terms needed for e.g. a checklist in a comprehensive manner (precoordination).

  20. Interfacing materials models with fire field models

    SciTech Connect

    Nicolette, V.F.; Tieszen, S.R.; Moya, J.L.

    1995-12-01

    For flame spread over solid materials, there has traditionally been a large technology gap between fundamental combustion research and the somewhat simplistic approaches used for practical, real-world applications. Recent advances in computational hardware and computational fluid dynamics (CFD)-based software have led to the development of fire field models. These models, when used in conjunction with material burning models, have the potential to bridge the gap between research and application by implementing physics-based engineering models in a transient, multi-dimensional tool. This paper discusses the coupling that is necessary between fire field models and burning material models for the simulation of solid material fires. Fire field models are capable of providing detailed information about the local fire environment. This information serves as an input to the solid material combustion submodel, which subsequently calculates the impact of the fire environment on the material. The response of the solid material (in terms of thermal response, decomposition, charring, and off-gassing) is then fed back into the field model as a source of mass, momentum and energy. The critical parameters which must be passed between the field model and the material burning model have been identified. Many computational issues must be addressed when developing such an interface. Some examples include the ability to track multiple fuels and species, local ignition criteria, and the need to use local grid refinement over the burning material of interest.

  1. Alloy Interface Interdiffusion Modeled

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Garces, Jorge E.; Abel, Phillip B.

    2003-01-01

    With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion.

  2. Defining and predicting urban-wildland interface zones using a GIS-based model

    Treesearch

    Lawrence R. Gering; Angel V. Chun; Steve Anderson

    2000-01-01

    Resource managers are beginning to experience a deluge of management conflicts as urban population centers expand into formerly wildland settings. Fire suppression, recreational, watershed management, and traditional forest management practices are activities that have become contentious in many locales. A better understanding of the interface zone between these two...

  3. Rapid development of entity-based data models for bioinformatics with persistence object-oriented design and structured interfaces.

    PubMed

    Ezra Tsur, Elishai

    2017-01-01

    Databases are imperative for research in bioinformatics and computational biology. Current challenges in database design include data heterogeneity and context-dependent interconnections between data entities. These challenges drove the development of unified data interfaces and specialized databases. The curation of specialized databases is an ever-growing challenge due to the introduction of new data sources and the emergence of new relational connections between established datasets. Here, an open-source framework for the curation of specialized databases is proposed. The framework supports user-designed models of data encapsulation, objects persistency and structured interfaces to local and external data sources such as MalaCards, Biomodels and the National Centre for Biotechnology Information (NCBI) databases. The proposed framework was implemented using Java as the development environment, EclipseLink as the data persistency agent and Apache Derby as the database manager. Syntactic analysis was based on J3D, jsoup, Apache Commons and w3c.dom open libraries. Finally, a construction of a specialized database for aneurysms associated vascular diseases is demonstrated. This database contains 3-dimensional geometries of aneurysms, patient's clinical information, articles, biological models, related diseases and our recently published model of aneurysms' risk of rapture. Framework is available in: http://nbel-lab.com.

  4. Mechanics and hydraulics of unsaturated soils: what makes interfaces an indispensable part of a physically-based model

    NASA Astrophysics Data System (ADS)

    Nikooee, E.; Hassanizadeh, S. M.

    2014-12-01

    The foundations of the current theories for hydraulics and mechanics of unsaturated soils have been mainly based on the empirically introduced equations. There are various characteristics of unsaturated soils for which lots of different empirical equations have been proposed such as hydraulic conductivity, water retention curve, and effective stress parameter. One of the remarkable challenges which all current models face is hysteresis, i.e., for a certain matric suction, values of saturation, hydraulic conductivity and effective stress parameter in drying state and wetting are different. Conventional models of hydraulic and mechanical behaviour of unsaturated soils try to account for the hysteresis phenomenon by means of different empirical equations for each hydraulic path. Hassanizadeh and Gray (1993) claimed that the hysteresis in capillary pressure-saturation curves can be modelled through the inclusion of air-water interfaces as a new independent variable [1]. It has recently been stated that the same conjecture can be made for suction stress [2]. Therefore, it seems to better portray hydraulic and mechanical behaviour of unsaturated soils, interfaces are required as an indispensable part of the framework [3, 4]. This presentation aims at introducing the drawbacks of current theories of hydraulics and mechanics of unsaturated soils. For this purpose, the role of interfaces in the mechanics and hydraulics of unsaturated soils is explained and different possibilities to account for the contribution of interfaces are discussed. Finally, current challenges and future research directions are set forth. References[1] Hassanizadeh, S.M. & Gray, W.G.: Thermodynamic basis of capillary pressure in porous media. Water Resour.Res. 29(1993), 3389-3405.[2] Nikooee, E., Habibagahi, G., Hassanizadeh, S.M. & Ghahramani, A.: Effective Stress in unsaturated Soils: a thermodynamic approach based on the interfacial energy and hydromechanical coupling. Transport porous Med. 96

  5. Human-arm-and-hand-dynamic model with variability analyses for a stylus-based haptic interface.

    PubMed

    Fu, Michael J; Cavuşoğlu, M Cenk

    2012-12-01

    Haptic interface research benefits from accurate human arm models for control and system design. The literature contains many human arm dynamic models but lacks detailed variability analyses. Without accurate measurements, variability is modeled in a very conservative manner, leading to less than optimal controller and system designs. This paper not only presents models for human arm dynamics but also develops inter- and intrasubject variability models for a stylus-based haptic device. Data from 15 human subjects (nine male, six female, ages 20-32) were collected using a Phantom Premium 1.5a haptic device for system identification. In this paper, grip-force-dependent models were identified for 1-3-N grip forces in the three spatial axes. Also, variability due to human subjects and grip-force variation were modeled as both structured and unstructured uncertainties. For both forms of variability, the maximum variation, 95 %, and 67 % confidence interval limits were examined. All models were in the frequency domain with force as input and position as output. The identified models enable precise controllers targeted to a subset of possible human operator dynamics.

  6. Multi-gas interaction modeling on decorated semiconductor interfaces: A novel Fermi distribution-based response isotherm and the inverse hard/soft acid/base concept

    NASA Astrophysics Data System (ADS)

    Laminack, William; Gole, James

    2015-12-01

    A unique MEMS/NEMS approach is presented for the modeling of a detection platform for mixed gas interactions. Mixed gas analytes interact with nanostructured decorating metal oxide island sites supported on a microporous silicon substrate. The Inverse Hard/Soft acid/base (IHSAB) concept is used to assess a diversity of conductometric responses for mixed gas interactions as a function of these nanostructured metal oxides. The analyte conductometric responses are well represented using a combination diffusion/absorption-based model for multi-gas interactions where a newly developed response absorption isotherm, based on the Fermi distribution function is applied. A further coupling of this model with the IHSAB concept describes the considerations in modeling of multi-gas mixed analyte-interface, and analyte-analyte interactions. Taking into account the molecular electronic interaction of both the analytes with each other and an extrinsic semiconductor interface we demonstrate how the presence of one gas can enhance or diminish the reversible interaction of a second gas with the extrinsic semiconductor interface. These concepts demonstrate important considerations in the array-based formats for multi-gas sensing and its applications.

  7. A comprehensive physiologically based pharmacokinetic knowledgebase and web-based interface for rapid model ranking and querying

    EPA Science Inventory

    Published physiologically based pharmacokinetic (PBPK) models from peer-reviewed articles are often well-parameterized, thoroughly-vetted, and can be utilized as excellent resources for the construction of models pertaining to related chemicals. Specifically, chemical-specific pa...

  8. A comprehensive physiologically based pharmacokinetic knowledgebase and web-based interface for rapid model ranking and querying

    EPA Science Inventory

    Published physiologically based pharmacokinetic (PBPK) models from peer-reviewed articles are often well-parameterized, thoroughly-vetted, and can be utilized as excellent resources for the construction of models pertaining to related chemicals. Specifically, chemical-specific pa...

  9. A Diffuse Interface Model for solid-liquid-air dissolution problems based on a porous medium theory

    NASA Astrophysics Data System (ADS)

    Luo, H.; Quintard, M.; Debenest, G.; Laouafa, F.

    2011-12-01

    The underground cavities may be dissolved by the flows of groundwater where the dissolution mainly happens at the liquid-solid interface. In many real cases, the cavities are not occupied only by the water, but also the gas phase, e.g., air, or other gases. In this case, there are solid-liquid-gas three phases. Normally, the air does not participate the dissolution. However, it may influence the dissolution as the position of the solid-liquid interface may gradually lower down with the dissolution process. Simulating the dissolution problems with multi- moving interfaces is a difficult task but rather interesting to study the evolution of the underground cavities. In this paper, we propose a diffuse interface model (DIM) to simulate the three-phase dissolution problem, based on a porous medium theory and a volume averaging theory te{Whitaker1999,Golfier2002,Quintard1994}. The interface is regarded as a continuous layer where the phase indicator (mainly for solid-liquid interface) and phase saturation (mainly for liquid-gas interface) vary rapidly but smoothly. The DIM equations enable us to simulate the moving interface under a fixed mesh system, instead of a deformed or moving mesh. Suppose we have three phases, solid, liquid and gas. The solid phase contains only species A. The gas phase contains only the air. The volume averaging theory is used to upscale the balance equations. The final DIM equations are presented below. The balance equation of solid phase can be written as {partialrho_{s}(1-\\varepsilon_{f})}/{partial t}=-K_{sl} where \\varepsilonf represents the volume fraction of the fluids (liquid+gas) and Ksl refers to the mass exchange between the solid phase and the liquid phase. Ksl cam be expressed as K_{sl}=rho_{l}alpha(omega_{eq}-Omega_{Al}). The balance equations of liquid phase can be written as {partialrho_{l}\\varepsilon_{f}S_{l}}/{partial t}+nabla\\cdot(rho_{l}{V}_{l})= K_{sl}. The balance equation of liquid phase can be written as {partialrho

  10. Numerical algorithms based on Galerkin methods for the modeling of reactive interfaces in photoelectrochemical (PEC) solar cells

    NASA Astrophysics Data System (ADS)

    Harmon, Michael; Gamba, Irene M.; Ren, Kui

    2016-12-01

    This work concerns the numerical solution of a coupled system of self-consistent reaction-drift-diffusion-Poisson equations that describes the macroscopic dynamics of charge transport in photoelectrochemical (PEC) solar cells with reactive semiconductor and electrolyte interfaces. We present three numerical algorithms, mainly based on a mixed finite element and a local discontinuous Galerkin method for spatial discretization, with carefully chosen numerical fluxes, and implicit-explicit time stepping techniques, for solving the time-dependent nonlinear systems of partial differential equations. We perform computational simulations under various model parameters to demonstrate the performance of the proposed numerical algorithms as well as the impact of these parameters on the solution to the model.

  11. Interface transferring mechanism and error modification of FRP-OFBG strain sensor based on standard linear viscoelastic model

    NASA Astrophysics Data System (ADS)

    Li, Jilong; Zhou, Zhi; Ou, Jinping

    2006-03-01

    This paper presents the interface transferring mechanism and error modification of the Fiber Reinforced Polymer-Optical Fiber Bragg Grating (FRP-OFBG) sensing tendons, which including GFRP (Glass Fiber Reinforced Polymer) and CFRP (Carbon Fiber Reinforced Polymer), using standard linear viscoelastic model. The optical fiber is made up of glass, quartz or plastic, et al, which creep strain is very small at room temperature. So the tensile creep compliance of optical fiber is independent of time at room temperature. On the other hand, the FRP (GFRP or CFRP) is composed of a kind of polymeric matrix (epoxy resins or the others) with glass, carbon or aramid fibers, which shear creep strain is dependent of time at room temperature. Hence, the standard linear viscoelastic model is employed to describe the shear creep compliance of FRP along the fiber direction. The expression of interface strain transferring mechanism of FRP-OFBG sensors is derived based on the linear viscoelastic theory and the analytic solution of the error rate is given by the inverse Laplace transform. The effects of FRP viscoelasticity on the error rate of FRP-OFBG sensing tendons are included in the above expression. And the transient and steady-state error modified coefficient of FRP-OFBG sensors are obtained using initial value and final value theorems. Finally, a calculated example is given to explain the correct of theoretical prediction.

  12. A learning scheme for reach to grasp movements: on EMG-based interfaces using task specific motion decoding models.

    PubMed

    Liarokapis, Minas V; Artemiadis, Panagiotis K; Kyriakopoulos, Kostas J; Manolakos, Elias S

    2013-09-01

    A learning scheme based on random forests is used to discriminate between different reach to grasp movements in 3-D space, based on the myoelectric activity of human muscles of the upper-arm and the forearm. Task specificity for motion decoding is introduced in two different levels: Subspace to move toward and object to be grasped. The discrimination between the different reach to grasp strategies is accomplished with machine learning techniques for classification. The classification decision is then used in order to trigger an EMG-based task-specific motion decoding model. Task specific models manage to outperform "general" models providing better estimation accuracy. Thus, the proposed scheme takes advantage of a framework incorporating both a classifier and a regressor that cooperate advantageously in order to split the task space. The proposed learning scheme can be easily used to a series of EMG-based interfaces that must operate in real time, providing data-driven capabilities for multiclass problems, that occur in everyday life complex environments.

  13. Overview of the Graphical User Interface for the GERM Code (GCR Event-Based Risk Model

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee; Cucinotta, Francis A.

    2010-01-01

    The descriptions of biophysical events from heavy ions are of interest in radiobiology, cancer therapy, and space exploration. The biophysical description of the passage of heavy ions in tissue and shielding materials is best described by a stochastic approach that includes both ion track structure and nuclear interactions. A new computer model called the GCR Event-based Risk Model (GERM) code was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL). The GERM code calculates basic physical and biophysical quantities of high-energy protons and heavy ions that have been studied at NSRL for the purpose of simulating space radiobiological effects. For mono-energetic beams, the code evaluates the linear-energy transfer (LET), range (R), and absorption in tissue equivalent material for a given Charge (Z), Mass Number (A) and kinetic energy (E) of an ion. In addition, a set of biophysical properties are evaluated such as the Poisson distribution of ion or delta-ray hits for a specified cellular area, cell survival curves, and mutation and tumor probabilities. The GERM code also calculates the radiation transport of the beam line for either a fixed number of user-specified depths or at multiple positions along the Bragg curve of the particle. The contributions from primary ion and nuclear secondaries are evaluated. The GERM code accounts for the major nuclear interaction processes of importance for describing heavy ion beams, including nuclear fragmentation, elastic scattering, and knockout-cascade processes by using the quantum multiple scattering fragmentation (QMSFRG) model. The QMSFRG model has been shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections, and has been used by the GERM code for application to thick target experiments. The GERM code provides scientists participating in NSRL experiments with the data needed for the interpretation of their

  14. Overview of the Graphical User Interface for the GERMcode (GCR Event-Based Risk Model)

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.

    2010-01-01

    The descriptions of biophysical events from heavy ions are of interest in radiobiology, cancer therapy, and space exploration. The biophysical description of the passage of heavy ions in tissue and shielding materials is best described by a stochastic approach that includes both ion track structure and nuclear interactions. A new computer model called the GCR Event-based Risk Model (GERM) code was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL). The GERMcode calculates basic physical and biophysical quantities of high-energy protons and heavy ions that have been studied at NSRL for the purpose of simulating space radiobiological effects. For mono-energetic beams, the code evaluates the linear-energy transfer (LET), range (R), and absorption in tissue equivalent material for a given Charge (Z), Mass Number (A) and kinetic energy (E) of an ion. In addition, a set of biophysical properties are evaluated such as the Poisson distribution of ion or delta-ray hits for a specified cellular area, cell survival curves, and mutation and tumor probabilities. The GERMcode also calculates the radiation transport of the beam line for either a fixed number of user-specified depths or at multiple positions along the Bragg curve of the particle. The contributions from primary ion and nuclear secondaries are evaluated. The GERMcode accounts for the major nuclear interaction processes of importance for describing heavy ion beams, including nuclear fragmentation, elastic scattering, and knockout-cascade processes by using the quantum multiple scattering fragmentation (QMSFRG) model. The QMSFRG model has been shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections, and has been used by the GERMcode for application to thick target experiments. The GERMcode provides scientists participating in NSRL experiments with the data needed for the interpretation of their

  15. Overview of the Graphical User Interface for the GERMcode (GCR Event-Based Risk Model)

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.

    2010-01-01

    The descriptions of biophysical events from heavy ions are of interest in radiobiology, cancer therapy, and space exploration. The biophysical description of the passage of heavy ions in tissue and shielding materials is best described by a stochastic approach that includes both ion track structure and nuclear interactions. A new computer model called the GCR Event-based Risk Model (GERM) code was developed for the description of biophysical events from heavy ion beams at the NASA Space Radiation Laboratory (NSRL). The GERMcode calculates basic physical and biophysical quantities of high-energy protons and heavy ions that have been studied at NSRL for the purpose of simulating space radiobiological effects. For mono-energetic beams, the code evaluates the linear-energy transfer (LET), range (R), and absorption in tissue equivalent material for a given Charge (Z), Mass Number (A) and kinetic energy (E) of an ion. In addition, a set of biophysical properties are evaluated such as the Poisson distribution of ion or delta-ray hits for a specified cellular area, cell survival curves, and mutation and tumor probabilities. The GERMcode also calculates the radiation transport of the beam line for either a fixed number of user-specified depths or at multiple positions along the Bragg curve of the particle. The contributions from primary ion and nuclear secondaries are evaluated. The GERMcode accounts for the major nuclear interaction processes of importance for describing heavy ion beams, including nuclear fragmentation, elastic scattering, and knockout-cascade processes by using the quantum multiple scattering fragmentation (QMSFRG) model. The QMSFRG model has been shown to be in excellent agreement with available experimental data for nuclear fragmentation cross sections, and has been used by the GERMcode for application to thick target experiments. The GERMcode provides scientists participating in NSRL experiments with the data needed for the interpretation of their

  16. A Gaussian mixture model based adaptive classifier for fNIRS brain-computer interfaces and its testing via simulation

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Jiang, Yi-han; Duan, Lian; Zhu, Chao-zhe

    2017-08-01

    Objective. Functional near infra-red spectroscopy (fNIRS) is a promising brain imaging technology for brain-computer interfaces (BCI). Future clinical uses of fNIRS will likely require operation over long time spans, during which neural activation patterns may change. However, current decoders for fNIRS signals are not designed to handle changing activation patterns. The objective of this study is to test via simulations a new adaptive decoder for fNIRS signals, the Gaussian mixture model adaptive classifier (GMMAC). Approach. GMMAC can simultaneously classify and track activation pattern changes without the need for ground-truth labels. This adaptive classifier uses computationally efficient variational Bayesian inference to label new data points and update mixture model parameters, using the previous model parameters as priors. We test GMMAC in simulations in which neural activation patterns change over time and compare to static decoders and unsupervised adaptive linear discriminant analysis classifiers. Main results. Our simulation experiments show GMMAC can accurately decode under time-varying activation patterns: shifts of activation region, expansions of activation region, and combined contractions and shifts of activation region. Furthermore, the experiments show the proposed method can track the changing shape of the activation region. Compared to prior work, GMMAC performed significantly better than the other unsupervised adaptive classifiers on a difficult activation pattern change simulation: 99% versus  <54% in two-choice classification accuracy. Significance. We believe GMMAC will be useful for clinical fNIRS-based brain-computer interfaces, including neurofeedback training systems, where operation over long time spans is required.

  17. Reinventing the energy modelling-policy interface

    NASA Astrophysics Data System (ADS)

    Strachan, Neil; Fais, Birgit; Daly, Hannah

    2016-03-01

    Energy modelling has a crucial underpinning role for policy making, but the modelling-policy interface faces several limitations. A reinvention of this interface would better provide timely, targeted, tested, transparent and iterated insights from such complex multidisciplinary tools.

  18. Microprocessor-based interface for oceanography

    NASA Technical Reports Server (NTRS)

    Hansen, G. R.

    1979-01-01

    Ocean floor imaging system incorporates five identical microprocessor-based interface units each assigned to specific sonar instrument to simplify system. Central control module based on same microprocessor eliminates need for custom tailoring hardware interfaces for each instrument.

  19. Microprocessor-based interface for oceanography

    NASA Technical Reports Server (NTRS)

    Hansen, G. R.

    1979-01-01

    Ocean floor imaging system incorporates five identical microprocessor-based interface units each assigned to specific sonar instrument to simplify system. Central control module based on same microprocessor eliminates need for custom tailoring hardware interfaces for each instrument.

  20. A virtual reality interface for pre-planning of surgical operations based on a customized model of the patient

    NASA Astrophysics Data System (ADS)

    Witkowski, Marcin; Lenar, Janusz; Sitnik, Robert; Verdonschot, Nico

    2012-03-01

    We present a human-computer interface that enables the operator to plan a surgical procedure on the musculoskeletal (MS) model of the patient's lower limbs, send the modified model to the bio-mechanical analysis module, and export the scenario parameters to the surgical navigation system. The interface provides the operator with tools for: importing customized MS model of the patient, cutting bones and manipulating/removal of bony fragments, repositioning muscle insertion points, muscle removal and placing implants. After planning the operator exports the modified MS model for bio-mechanical analysis of the functional outcome. If the simulation result is satisfactory the exported scenario data may be directly used during the actual surgery. The advantages of the developed interface are the possibility of installing it in various hardware configurations and coherent operation regardless of the devices used. The hardware configurations proposed to be used with the interface are: (a) a standard computer keyboard and mouse, and a 2-D display, (b) a touch screen as a single device for both input and output, or (c) a 3-D display and a haptic device for natural manipulation of 3-D objects. The interface may be utilized in two main fields. Experienced surgeons may use it to simulate their intervention plans and prepare input data for a surgical navigation system while student or novice surgeons can use it for simulating results of their hypothetical procedure. The interface has been developed in the TLEMsafe project (www.tlemsafe.eu) funded by the European Commission FP7 program.

  1. An interface tracking model for droplet electrocoalescence.

    SciTech Connect

    Erickson, Lindsay Crowl

    2013-09-01

    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.

  2. A graphical interface based model for wind turbine drive train dynamics

    SciTech Connect

    Manwell, J.F.; McGowan, J.G.; Abdulwahid, U.; Rogers, A.; McNiff, B.

    1996-12-31

    This paper presents a summary of a wind turbine drive train dynamics code that has been under development at the University of Massachusetts, under National Renewable Energy Laboratory (NREL) support. The code is intended to be used to assist in the proper design and selection of drive train components. This work summarizes the development of the equations of motion for the model, and discusses the method of solution. In addition, a number of comparisons with analytical solutions and experimental field data are given. The summary includes conclusions and suggestions for future work on the model. 13 refs., 10 figs.

  3. MESO-Adaptation Based on Model Oriented Reengineering Process for Human-Computer Interface (MESOMORPH)

    DTIC Science & Technology

    2004-02-01

    best focus. We add visual color perception to the model to accommodate users who may be colorblind . Audio amplitude and frequency are determinants of...Visual accomodation None Range (diopters) Normal Visual color perception Colorblind red-green Colorblind other Normal Audio amplitude None

  4. The Research on Automatic Construction of Domain Model Based on Deep Web Query Interfaces

    NASA Astrophysics Data System (ADS)

    JianPing, Gu

    The integration of services is transparent, meaning that users no longer face the millions of Web services, do not care about the required data stored, but do not need to learn how to obtain these data. In this paper, we analyze the uncertainty of schema matching, and then propose a series of similarity measures. To reduce the cost of execution, we propose the type-based optimization method and schema matching pruning method of numeric data. Based on above analysis, we propose the uncertain schema matching method. The experiments prove the effectiveness and efficiency of our method.

  5. An interface energy density-based theory considering the coherent interface effect in nanomaterials

    NASA Astrophysics Data System (ADS)

    Yao, Yin; Chen, Shaohua; Fang, Daining

    2017-02-01

    To characterize the coherent interface effect conveniently and feasibly in nanomaterials, a continuum theory is proposed that is based on the concept of the interface free energy density, which is a dominant factor affecting the mechanical properties of the coherent interface in materials of all scales. The effect of the residual strain caused by self-relaxation and the lattice misfit of nanomaterials, as well as that due to the interface deformation induced by an external load on the interface free energy density is considered. In contrast to the existing theories, the stress discontinuity at the interface is characterized by the interface free energy density through an interface-induced traction. As a result, the interface elastic constant introduced in previous theories, which is not easy to determine precisely, is avoided in the present theory. Only the surface energy density of the bulk materials forming the interface, the relaxation parameter induced by surface relaxation, and the mismatch parameter for forming a coherent interface between the two surfaces are involved. All the related parameters are far easier to determine than the interface elastic constants. The effective bulk and shear moduli of a nanoparticle-reinforced nanocomposite are predicted using the proposed theory. Closed-form solutions are achieved, demonstrating the feasibility and convenience of the proposed model for predicting the interface effect in nanomaterials.

  6. Transport, Interfaces, and Modeling in Amorphous Silicon Based Solar Cells: Final Technical Report, 11 February 2002 - 30 September 2006

    SciTech Connect

    Schiff, E. A.

    2008-10-01

    Results for a-Si characteristics/modeling; photocarrier drift mobilities in a-Si;H, ..mu..c-Si:H, CIGS; hole-conducting polymers as p-layer for a-Si and c-Si; IR spectra of p/i and n/i interfaces in a-Si.

  7. DEVELOPMENT OF A CHEMICAL PROCESS MODELING ENVIRONMENT BASED ON CAPE-OPEN INTERFACE STANDARDS AND THE MICROSOFT .NET FRAMEWORK

    EPA Science Inventory

    Chemical process simulation has long been used as a design tool in the development of chemical plants, and has long been considered a means to evaluate different design options. With the advent of large scale computer networks and interface models for program components, it is po...

  8. DEVELOPMENT OF A CHEMICAL PROCESS MODELING ENVIRONMENT BASED ON CAPE-OPEN INTERFACE STANDARDS AND THE MICROSOFT .NET FRAMEWORK

    EPA Science Inventory

    Chemical process simulation has long been used as a design tool in the development of chemical plants, and has long been considered a means to evaluate different design options. With the advent of large scale computer networks and interface models for program components, it is po...

  9. A new interface element for connecting independently modeled substructures

    NASA Technical Reports Server (NTRS)

    Ransom, Jonathan B.; Mccleary, Susan L.; Aminpour, Mohammad A.

    1993-01-01

    A new interface element based on the hybrid variational formulation is presented and demonstrated. The element provides a means of connecting independently modeled substructures whose nodes along the common boundary need not be coincident. The interface element extends previous work to include connecting an arbitrary number of substructures, the use of closed and generally curved interfaces, and the use of multiple, possibly nested, interfaces. Several applications of the element are presented and aspects of the implementation are discussed.

  10. Musculoskeletal model-based control interface mimics physiologic hand dynamics during path tracing task

    NASA Astrophysics Data System (ADS)

    Crouch, Dustin L.; (Helen Huang, He

    2017-06-01

    Objective. We investigated the feasibility of a novel, customizable, simplified EMG-driven musculoskeletal model for estimating coordinated hand and wrist motions during a real-time path tracing task. Approach. A two-degree-of-freedom computational musculoskeletal model was implemented for real-time EMG-driven control of a stick figure hand displayed on a computer screen. After 5-10 minutes of undirected practice, subjects were given three attempts to trace 10 straight paths, one at a time, with the fingertip of the virtual hand. Able-bodied subjects completed the task on two separate test days. Main results. Across subjects and test days, there was a significant linear relationship between log-transformed measures of accuracy and speed (Pearson’s r  =  0.25, p  <  0.0001). The amputee subject could coordinate movement between the wrist and MCP joints, but favored metacarpophalangeal joint motion more highly than able-bodied subjects in 8 of 10 trials. For able-bodied subjects, tracing accuracy was lower at the extremes of the model’s range of motion, though there was no apparent relationship between tracing accuracy and fingertip location for the amputee. Our result suggests that, unlike able-bodied subjects, the amputee’s motor control patterns were not accustomed to the multi-joint dynamics of the wrist and hand, possibly as a result of post-amputation cortical plasticity, disuse, or sensory deficits. Significance. To our knowledge, our study is one of very few that have demonstrated the real-time simultaneous control of multi-joint movements, especially wrist and finger movements, using an EMG-driven musculoskeletal model, which differs from the many data-driven algorithms that dominate the literature on EMG-driven prosthesis control. Real-time control was achieved with very little training and simple, quick (~15 s) calibration. Thus, our model is potentially a practical and effective control platform for multifunctional myoelectric

  11. A Cross-Cultural Usability Study on the Internationalization of User Interfaces Based on an Empirical Five Factor Model

    ERIC Educational Resources Information Center

    Chakraborty, Joyram

    2009-01-01

    With the internationalization of e-commerce, it is no longer viable to design one user interface for all environments. Web-based applications and services can be accessed from all over the globe. To account for this globalization process, software developers need to understand that simply accounting for language translation of their websites for…

  12. A Cross-Cultural Usability Study on the Internationalization of User Interfaces Based on an Empirical Five Factor Model

    ERIC Educational Resources Information Center

    Chakraborty, Joyram

    2009-01-01

    With the internationalization of e-commerce, it is no longer viable to design one user interface for all environments. Web-based applications and services can be accessed from all over the globe. To account for this globalization process, software developers need to understand that simply accounting for language translation of their websites for…

  13. Computational design of patterned interfaces using reduced order models.

    PubMed

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

    2014-08-29

    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.

  14. Computational design of patterned interfaces using reduced order models

    PubMed Central

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

    2014-01-01

    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

  15. Geographic information system/watershed model interface

    USGS Publications Warehouse

    Fisher, Gary T.

    1989-01-01

    Geographic information systems allow for the interactive analysis of spatial data related to water-resources investigations. A conceptual design for an interface between a geographic information system and a watershed model includes functions for the estimation of model parameter values. Design criteria include ease of use, minimal equipment requirements, a generic data-base management system, and use of a macro language. An application is demonstrated for a 90.1-square-kilometer subbasin of the Patuxent River near Unity, Maryland, that performs automated derivation of watershed parameters for hydrologic modeling.

  16. Model study of protein unfolding by interfaces.

    PubMed

    Chakarova, S D; Carlsson, A E

    2004-02-01

    We study interface-induced protein unfolding on hydrophobic and polar interfaces by means of a two-dimensional lattice model and an exhaustive enumeration ground-state structure search, for a set of model proteins of length 20 residues. We compare the effects of the two types of interfaces, and search for criteria that influence the retention of a protein's native-state structure upon adsorption. We find that the unfolding proceeds by a large, sudden loss of native contacts. The unfolding at polar interfaces exhibits similar behavior to that at hydrophobic interfaces but with a much weaker interface coupling strength. Further, we find that the resistance of proteins to unfolding in our model is positively correlated with the magnitude of the folding energy in the native-state structure, the thermal stability (or energy gap) for that structure, and the interface energy for native-state adsorption. We find these factors to be of roughly equal importance.

  17. Model study of protein unfolding by interfaces

    NASA Astrophysics Data System (ADS)

    Chakarova, S. D.; Carlsson, A. E.

    2004-02-01

    We study interface-induced protein unfolding on hydrophobic and polar interfaces by means of a two-dimensional lattice model and an exhaustive enumeration ground-state structure search, for a set of model proteins of length 20 residues. We compare the effects of the two types of interfaces, and search for criteria that influence the retention of a protein’s native-state structure upon adsorption. We find that the unfolding proceeds by a large, sudden loss of native contacts. The unfolding at polar interfaces exhibits similar behavior to that at hydrophobic interfaces but with a much weaker interface coupling strength. Further, we find that the resistance of proteins to unfolding in our model is positively correlated with the magnitude of the folding energy in the native-state structure, the thermal stability (or energy gap) for that structure, and the interface energy for native-state adsorption. We find these factors to be of roughly equal importance.

  18. A diagnostic interface for the ICOsahedral Non-hydrostatic (ICON) modelling framework based on the Modular Earth Submodel System (MESSy v2.50)

    NASA Astrophysics Data System (ADS)

    Kern, Bastian; Jöckel, Patrick

    2016-10-01

    Numerical climate and weather models have advanced to finer scales, accompanied by large amounts of output data. The model systems hit the input and output (I/O) bottleneck of modern high-performance computing (HPC) systems. We aim to apply diagnostic methods online during the model simulation instead of applying them as a post-processing step to written output data, to reduce the amount of I/O. To include diagnostic tools into the model system, we implemented a standardised, easy-to-use interface based on the Modular Earth Submodel System (MESSy) into the ICOsahedral Non-hydrostatic (ICON) modelling framework. The integration of the diagnostic interface into the model system is briefly described. Furthermore, we present a prototype implementation of an advanced online diagnostic tool for the aggregation of model data onto a user-defined regular coarse grid. This diagnostic tool will be used to reduce the amount of model output in future simulations. Performance tests of the interface and of two different diagnostic tools show, that the interface itself introduces no overhead in form of additional runtime to the model system. The diagnostic tools, however, have significant impact on the model system's runtime. This overhead strongly depends on the characteristics and implementation of the diagnostic tool. A diagnostic tool with high inter-process communication introduces large overhead, whereas the additional runtime of a diagnostic tool without inter-process communication is low. We briefly describe our efforts to reduce the additional runtime from the diagnostic tools, and present a brief analysis of memory consumption. Future work will focus on optimisation of the memory footprint and the I/O operations of the diagnostic interface.

  19. EDITORIAL: Sensors based on interfaces

    NASA Astrophysics Data System (ADS)

    Camassel, Jean; Soukiassian, Patrick G.

    2007-12-01

    Sensors are specific analog devices that convert a physical quantity, like the temperature or external pressure or concentration of carbon monoxide in a confined atmosphere, into an electrical signal. Considered in this way, every sensor is then a part of the artificial interface, which connects the human world to the world of machines. The other side of the interface is represented by actuators. Most often, after processing the data they are used to convert the out-coming electrical power into counteracting physical action. In the last few years, thanks to inexpensive silicon technology, enormous capability for data processing has been developed and the world of machines has become increasingly invasive. The world of sensors has become increasingly complex too. Applications range from classical measurements of the temperature, vibrations, shocks and acceleration to more recent chemical and bio-sensing technologies. Chemical sensors are used to detect the presence of specific, generally toxic, chemical species. To measure their concentration, one uses some specific property, generally a physical one, like the intensity of infrared absorption bands. Bio-sensors are new, more complex, devices that combine a bio-receptor with a physical transducer. The bio-receptor is a molecule (for instance, an enzyme like glucose oxidase) that can recognize a specific target (glucose molecules in the case of glucose oxidase). The enzyme must be fixed on the transducer and, as a consequence of recognition, the transducer must convert the event into a measurable analytical signal. A common feature of many chemical and bio-sensors is that they require a large surface of interaction with the outside world. For that reason and in order to increase efficiency, either nanoparticles or pores or a combination of both, made from various materials including (but not limited to) porous silicon, are often used as the functional transducer interface. The reviews in this Cluster Issue of Journal

  20. Interface Design in Computer-Based Language Testing.

    ERIC Educational Resources Information Center

    Fulcher, Glenn

    2003-01-01

    Describes a three-phase process model for interface design, drawing on practices developed in the software industry and adapting them for computer-based languages tests. Describes good practice in initial design, emphasizes the importance of usability testing, and argues that only through following a principled approach to interface design can the…

  1. CAPRI (Computational Analysis PRogramming Interface): A Solid Modeling Based Infra-Structure for Engineering Analysis and Design Simulations

    NASA Technical Reports Server (NTRS)

    Haimes, Robert; Follen, Gregory J.

    1998-01-01

    CAPRI is a CAD-vendor neutral application programming interface designed for the construction of analysis and design systems. By allowing access to the geometry from within all modules (grid generators, solvers and post-processors) such tasks as meshing on the actual surfaces, node enrichment by solvers and defining which mesh faces are boundaries (for the solver and visualization system) become simpler. The overall reliance on file 'standards' is minimized. This 'Geometry Centric' approach makes multi-physics (multi-disciplinary) analysis codes much easier to build. By using the shared (coupled) surface as the foundation, CAPRI provides a single call to interpolate grid-node based data from the surface discretization in one volume to another. Finally, design systems are possible where the results can be brought back into the CAD system (and therefore manufactured) because all geometry construction and modification are performed using the CAD system's geometry kernel.

  2. Explicit continuous charge-based compact model for long channel heavily doped surrounding-gate MOSFETs incorporating interface traps and quantum effects

    NASA Astrophysics Data System (ADS)

    Hamzah, Afiq; Hamid, Fatimah A.; Ismail, Razali

    2016-12-01

    An explicit solution for long-channel surrounding-gate (SRG) MOSFETs is presented from intrinsic to heavily doped body including the effects of interface traps and fixed oxide charges. The solution is based on the core SRGMOSFETs model of the Unified Charge Control Model (UCCM) for heavily doped conditions. The UCCM model of highly doped SRGMOSFETs is derived to obtain the exact equivalent expression as in the undoped case. Taking advantage of the undoped explicit charge-based expression, the asymptotic limits for below threshold and above threshold have been redefined to include the effect of trap states for heavily doped cases. After solving the asymptotic limits, an explicit mobile charge expression is obtained which includes the trap state effects. The explicit mobile charge model shows very good agreement with respect to numerical simulation over practical terminal voltages, doping concentration, geometry effects, and trap state effects due to the fixed oxide charges and interface traps. Then, the drain current is obtained using the Pao-Sah's dual integral, which is expressed as a function of inversion charge densities at the source/drain ends. The drain current agreed well with the implicit solution and numerical simulation for all regions of operation without employing any empirical parameters. A comparison with previous explicit models has been conducted to verify the competency of the proposed model with the doping concentration of 1× {10}19 {{cm}}-3, as the proposed model has better advantages in terms of its simplicity and accuracy at a higher doping concentration.

  3. A Process Based Approach to Modeling Hydrogen Sulfide Emissions Across the Air-Surface Interface of Manure from Concentrated Animal Feeding Operations

    NASA Astrophysics Data System (ADS)

    Rumsey, I. C.; Aneja, V.

    2009-12-01

    Hydrogen sulfide (H2S) emissions from concentrated animal feeding operations (CAFOs) are an important concern due to their contribution to odor and their potential to form PMfine. CAFO manure surface emissions occur from barns floors, during waste storage and treatment, and following land application. There is a need for a process based model, which will provide a method for quantifying emissions in different production, management and environmental conditions. A process based air-surface interface mass transfer model with chemical reactions was developed based on theoretical principles and related published information on H2S emissions. Different approaches were used to calculate the three main components of the model: the dissociation constant, the Henry’s law constant, and the overall mass transport coefficient. The dissociation constant was calculated based on thermodynamic principles and was corrected for the ionic strength of the manure. Similarly, the Henry’s law constant was also calculated based on thermodynamic principles. The overall mass transfer coefficient was developed using a previously published air-surface interface mass transport model, which considered the most important properties affecting mass transport to be the diffusivity of H2S in air, the air viscosity, and the air density. These parameters were modeled using dimensional analysis, which identified the variables that needed to be measured to determine the relevant constant and exponents values. By using the previously published study’s model and their measured constant and exponent values, an appropriate overall mass transfer coefficient was developed. Sensitivity analysis of the process based air-surface interface mass transfer model showed predicted fluxes to be most dependent on manure sulfide concentration and manure pH, and to a smaller extent on wind speed and manure temperature. Model predicted fluxes were compared with measured H2S flux and meteorological and physiochemical

  4. Correlation-based model of artificially induced plasticity in motor cortex by a bidirectional brain-computer interface

    PubMed Central

    Lajoie, Guillaume; Kalaska, John F.; Fairhall, Adrienne L.; Fetz, Eberhard E.

    2017-01-01

    Experiments show that spike-triggered stimulation performed with Bidirectional Brain-Computer-Interfaces (BBCI) can artificially strengthen connections between separate neural sites in motor cortex (MC). When spikes from a neuron recorded at one MC site trigger stimuli at a second target site after a fixed delay, the connections between sites eventually strengthen. It was also found that effective spike-stimulus delays are consistent with experimentally derived spike-timing-dependent plasticity (STDP) rules, suggesting that STDP is key to drive these changes. However, the impact of STDP at the level of circuits, and the mechanisms governing its modification with neural implants remain poorly understood. The present work describes a recurrent neural network model with probabilistic spiking mechanisms and plastic synapses capable of capturing both neural and synaptic activity statistics relevant to BBCI conditioning protocols. Our model successfully reproduces key experimental results, both established and new, and offers mechanistic insights into spike-triggered conditioning. Using analytical calculations and numerical simulations, we derive optimal operational regimes for BBCIs, and formulate predictions concerning the efficacy of spike-triggered conditioning in different regimes of cortical activity. PMID:28151957

  5. Contact angle-based predictive model for slip at the solid-liquid interface of a transverse-shear mode acoustic wave device

    NASA Astrophysics Data System (ADS)

    Ellis, Jonathan S.; McHale, Glen; Hayward, Gordon L.; Thompson, Michael

    2003-11-01

    We have revisited the Blake-Tolstoi theory [Coll. Surf. 47, 135 (1990)] for molecular and hydrodynamic slip and applied it to the fundamental description of acoustic wave devices coupled to a liquid of finite thickness. The aim is to provide a framework for a predictive model for slip, based on surface-liquid interactions and contact angle. This theory provides a description of slip that links hydrodynamic boundary slip to a schematic, molecular description involving the wettability of the liquid-solid interface. We redevelop the model, using current acoustic sensors notation, then evaluate its qualitative behavior as a predictive model for slip length in the context of acoustic wave devices. Finally, we discuss the limitations of the model and consider the advantages of a predictive model for boundary slip.

  6. T:XML: A Tool Supporting User Interface Model Transformation

    NASA Astrophysics Data System (ADS)

    López-Jaquero, Víctor; Montero, Francisco; González, Pascual

    Model driven development of user interfaces is based on the transformation of an abstract specification into the final user interface the user will interact with. The design of transformation rules to carry out this transformation process is a key issue in any model-driven user interface development approach. In this paper, we introduce T:XML, an integrated development environment for managing, creating and previewing transformation rules. The tool supports the specification of transformation rules by using a graphical notation that works on the basis of the transformation of the input model into a graph-based representation. T:XML allows the design and execution of transformation rules in an integrated development environment. Furthermore, the designer can also preview how the generated user interface looks like after the transformations have been applied. These previewing capabilities can be used to quickly create prototypes to discuss with the users in user-centered design methods.

  7. Natural language interface for nuclear data bases

    SciTech Connect

    Heger, A.S.; Koen, B.V.

    1987-01-01

    A natural language interface has been developed for access to information from a data base, simulating a nuclear plant reliability data system (NPRDS), one of the several existing data bases serving the nuclear industry. In the last decade, the importance of information has been demonstrated by the impressive diffusion of data base management systems. The present methods that are employed to access data bases fall into two main categories of menu-driven systems and use of data base manipulation languages. Both of these methods are currently used by NPRDS. These methods have proven to be tedious, however, and require extensive training by the user for effective utilization of the data base. Artificial intelligence techniques have been used in the development of several intelligent front ends for data bases in nonnuclear domains. Lunar is a natural language program for interface to a data base describing moon rock samples brought back by Apollo. Intellect is one of the first data base question-answering systems that was commercially available in the financial area. Ladder is an intelligent data base interface that was developed as a management aid to Navy decision makers. A natural language interface for nuclear data bases that can be used by nonprogrammers with little or no training provides a means for achieving this goal for this industry.

  8. Ray tracing in discontinuous velocity model with implicit Interface

    NASA Astrophysics Data System (ADS)

    Zhang, Jianxing; Yang, Qin; Meng, Xianhai; Li, Jigang

    2016-07-01

    Ray tracing in the velocity model containing complex discontinuities is still facing many challenges. The main difficulty arises from the detection of the spatial relationship between the rays and the interfaces that are usually described in non-linear parametric forms. We propose a novel model representation method that can facilitate the implementation of classical shooting-ray methods. In the representation scheme, each interface is expressed as the zero contour of a signed distance field. A multi-copy strategy is adopted to describe the volumetric properties within blocks. The implicit description of the interface makes it easier to detect the ray-interface intersection. The direct calculation of the intersection point is converted into the problem of judging the signs of a ray segment's endpoints. More importantly, the normal to the interface at the intersection point can be easily acquired according to the signed distance field of the interface. The multiple storage of the velocity property in the proximity of the interface can provide accurate and unambiguous velocity information of the intersection point. Thus, the departing ray path can be determined easily and robustly. In addition, the new representation method can describe velocity models containing very complex geological structures, such as faults, salt domes, intrusions, and pinches, without any simplification. The examples on synthetic and real models validate the robustness and accuracy of the ray tracing based on the proposed model representation scheme.

  9. An Agent-Based Interface to Terrestrial Ecological Forecasting

    NASA Technical Reports Server (NTRS)

    Golden, Keith; Nemani, Ramakrishna; Pang, Wan-Lin; Votava, Petr; Etzioni, Oren

    2004-01-01

    This paper describes a flexible agent-based ecological forecasting system that combines multiple distributed data sources and models to provide near-real-time answers to questions about the state of the Earth system We build on novel techniques in automated constraint-based planning and natural language interfaces to automatically generate data products based on descriptions of the desired data products.

  10. Exact interface model for wetting in the planar Ising model

    NASA Astrophysics Data System (ADS)

    Upton, P. J.

    1999-10-01

    At the wetting transition in the two-dimensional Ising model the long contour (interface) gets depinned from the substrate. It is found that on sufficiently large length scales the statistics of the long contour are described by a unique probability measure corresponding to a continuous ``interface model'' with an interface binding ``potential'' given by a Dirac δ function supported on the substrate. A lattice solid-on-solid model is shown to give similar results.

  11. Exact interface model for wetting in the planar Ising model.

    PubMed

    Upton, P J

    1999-10-01

    At the wetting transition in the two-dimensional Ising model the long contour (interface) gets depinned from the substrate. It is found that on sufficiently large length scales the statistics of the long contour are described by a unique probability measure corresponding to a continuous "interface model" with an interface binding "potential" given by a Dirac delta function supported on the substrate. A lattice solid-on-solid model is shown to give similar results.

  12. Modeling Europa's Ice-Ocean Interface

    NASA Astrophysics Data System (ADS)

    Elsenousy, A.; Vance, S.; Bills, B. G.

    2014-12-01

    This work focuses on modeling the ice-ocean interface on Jupiter's Moon (Europa); mainly from the standpoint of heat and salt transfer relationship with emphasis on the basal ice growth rate and its implications to Europa's tidal response. Modeling the heat and salt flux at Europa's ice/ocean interface is necessary to understand the dynamics of Europa's ocean and its interaction with the upper ice shell as well as the history of active turbulence at this area. To achieve this goal, we used McPhee et al., 2008 parameterizations on Earth's ice/ocean interface that was developed to meet Europa's ocean dynamics. We varied one parameter at a time to test its influence on both; "h" the basal ice growth rate and on "R" the double diffusion tendency strength. The double diffusion tendency "R" was calculated as the ratio between the interface heat exchange coefficient αh to the interface salt exchange coefficient αs. Our preliminary results showed a strong double diffusion tendency R ~200 at Europa's ice-ocean interface for plausible changes in the heat flux due to onset or elimination of a hydrothermal activity, suggesting supercooling and a strong tendency for forming frazil ice.

  13. Implantable Graphene-based Neural Electrode Interfaces for Electrophysiology and Neurochemistry in In Vivo Hyperacute Stroke Model.

    PubMed

    Liu, Ta-Chung; Chuang, Min-Chieh; Chu, Chao-Yi; Huang, Wei-Chen; Lai, Hsin-Yi; Wang, Chao-Ting; Chu, Wei-Lin; Chen, San-Yuan; Chen, You-Yin

    2016-01-13

    Implantable microelectrode arrays have attracted considerable interest due to their high temporal and spatial resolution recording of neuronal activity in tissues. We herein presented an implantable multichannel neural probe with multiple real-time monitoring of neural-chemical and neural-electrical signals by a nonenzymatic neural-chemical interface, which was designed by creating the newly developed reduced graphene oxide-gold oxide (rGO/Au2O3) nanocomposite electrode. The modified electrode on the neural probe was prepared by a facile one-step cyclic voltammetry (CV) electrochemical method with simultaneous occurrence of gold oxidation and GOs reduction to induce the intimate attachment by electrostatic interaction using chloride ions (Cl(-)). The rGO/Au2O3-modified electrode at a low deposition scan rate of 10 mVs(-1) displayed significantly improved electrocatalytic activity due to large active areas and well-dispersive attached rGO sheets. The in vitro amperometric response to H2O2 demonstrated a fast response of less than 5 s and a very low detection limit of 0.63 μM. In in vivo hyperacute stroke model, the concentration of H2O2 was measured as 100.48 ± 4.52 μM for rGO/Au2O3 electrode within 1 h photothrombotic stroke, which was much higher than that (71.92 μM ± 2.52 μM) for noncoated electrode via in vitro calibration. Simultaneously, the somatosensory-evoked potentials (SSEPs) test provided reliable and precise validation for detecting functional changes of neuronal activities. This newly developed implantable probe with localized rGO/Au2O3 nanocomposite electrode can serve as a rapid and reliable sensing platform for practical H2O2 detection in the brain or for other neural-chemical molecules in vivo.

  14. Microcanonical model for interface formation

    SciTech Connect

    Rucklidge, A.; Zaleski, S.

    1988-04-01

    We describe a new cellular automaton model which allows us to simulate separation of phases. The model is an extension of existing cellular automata for the Ising model, such as Q2R. It conserves particle number and presents the qualitative features of spinodal decomposition. The dynamics is deterministic and does not require random number generators. The spins exchange energy with small local reservoirs or demons. The rate of relaxation to equilibrium is investigated, and the results are compared to the Lifshitz-Slyozov theory.

  15. Transistor-based interface circuitry

    DOEpatents

    Taubman, Matthew S.

    2007-02-13

    Among the embodiments of the present invention is an apparatus that includes a transistor, a servo device, and a current source. The servo device is operable to provide a common base mode of operation of the transistor by maintaining an approximately constant voltage level at the transistor base. The current source is operable to provide a bias current to the transistor. A first device provides an input signal to an electrical node positioned between the emitter of the transistor and the current source. A second device receives an output signal from the collector of the transistor.

  16. Transistor-based interface circuitry

    DOEpatents

    Taubman, Matthew S.

    2004-02-24

    Among the embodiments of the present invention is an apparatus that includes a transistor, a servo device, and a current source. The servo device is operable to provide a common base mode of operation of the transistor by maintaining an approximately constant voltage level at the transistor base. The current source is operable to provide a bias current to the transistor. A first device provides an input signal to an electrical node positioned between the emitter of the transistor and the current source. A second device receives an output signal from the collector of the transistor.

  17. Transistor-based interface circuitry

    DOEpatents

    Taubman, Matthew S [Richland, WA

    2007-02-13

    Among the embodiments of the present invention is an apparatus that includes a transistor, a servo device, and a current source. The servo device is operable to provide a common base mode of operation of the transistor by maintaining an approximately constant voltage level at the transistor base. The current source is operable to provide a bias current to the transistor. A first device provides an input signal to an electrical node positioned between the emitter of the transistor and the current source. A second device receives an output signal from the collector of the transistor.

  18. Computer modelling of metal - oxide interfaces

    NASA Astrophysics Data System (ADS)

    Purton, J.; Parker, S. C.; Bullett, D. W.

    1997-07-01

    We have used atomistic simulations to model oxide - metal interfaces. We have, for the first time, allowed the atoms on both sides of the interface to relax. The efficiency of the computational method means that calculations can be performed on complex interfaces containing several thousand atoms and do not require an arbitrary definition of the image plane to model the electrostatics across the dielectric discontinuity. We demonstrate the viability of the approach and the effect of relaxation on a range of MgO - Ag interfaces. Defective and faceted interfaces, as well as the ideal case, have been studied. The latter was chosen for comparison with previous theoretical calculations and experimental results. The wetting angle 0953-8984/9/27/004/img7 and work of adhesion 0953-8984/9/27/004/img8 for MgO{100} - Ag{100} are in reasonable agreement with experiment. As with ab initio electronic structure calculations the silver atoms have been shown to favour the position above the oxygen site.

  19. A Web Interface for Eco System Modeling

    NASA Astrophysics Data System (ADS)

    McHenry, K.; Kooper, R.; Serbin, S. P.; LeBauer, D. S.; Desai, A. R.; Dietze, M. C.

    2012-12-01

    We have developed the Predictive Ecosystem Analyzer (PEcAn) as an open-source scientific workflow system and ecoinformatics toolbox that manages the flow of information in and out of regional-scale terrestrial biosphere models, facilitates heterogeneous data assimilation, tracks data provenance, and enables more effective feedback between models and field research. The over-arching goal of PEcAn is to make otherwise complex analyses transparent, repeatable, and accessible to a diverse array of researchers, allowing both novice and expert users to focus on using the models to examine complex ecosystems rather than having to deal with complex computer system setup and configuration questions in order to run the models. Through the developed web interface we hide much of the data and model details and allow the user to simply select locations, ecosystem models, and desired data sources as inputs to the model. Novice users are guided by the web interface through setting up a model execution and plotting the results. At the same time expert users are given enough freedom to modify specific parameters before the model gets executed. This will become more important as more and more models are added to the PEcAn workflow as well as more and more data that will become available as NEON comes online. On the backend we support the execution of potentially computationally expensive models on different High Performance Computers (HPC) and/or clusters. The system can be configured with a single XML file that gives it the flexibility needed for configuring and running the different models on different systems using a combination of information stored in a database as well as pointers to files on the hard disk. While the web interface usually creates this configuration file, expert users can still directly edit it to fine tune the configuration.. Once a workflow is finished the web interface will allow for the easy creation of plots over result data while also allowing the user to

  20. Workload-Based Automated Interface Mode Selection

    DTIC Science & Technology

    2012-03-22

    and Automation Level Response Sim- ulator ( WALRuS ) testbed and automated experiments with cognitively modeled agents. Testing established a...63 Appendix A. Institutional Review Board Waiver Letter . . . . . . . . . . . 65 Appendix B. WALRuS Source Code Listing...37 9. WALRuS Full Operator Interface Screen. . . . . . . . . . . . . . . . 39 10. WALRuS System Monitoring Task Panel

  1. Molecular modeling of cracks at interfaces in nanoceramic composites

    NASA Astrophysics Data System (ADS)

    Pavia, F.; Curtin, W. A.

    2013-10-01

    Toughness in Ceramic Matrix Composites (CMCs) is achieved if crack deflection can occur at the fiber/matrix interface, preventing crack penetration into the fiber and enabling energy-dissipating fiber pullout. To investigate toughening in nanoscale CMCs, direct atomistic models are used to study how matrix cracks behave as a function of the degree of interfacial bonding/sliding, as controlled by the density of C interstitial atoms, at the interface between carbon nanotubes (CNTs) and a diamond matrix. Under all interface conditions studied, incident matrix cracks do not penetrate into the nanotube. Under increased loading, weaker interfaces fail in shear while stronger interfaces do not fail and, instead, the CNT fails once the stress on the CNT reaches its tensile strength. An analytic shear lag model captures all of the micromechanical details as a function of loading and material parameters. Interface deflection versus fiber penetration is found to depend on the relative bond strengths of the interface and the CNT, with CNT failure occurring well below the prediction of the toughness-based continuum He-Hutchinson model. The shear lag model, in contrast, predicts the CNT failure point and shows that the nanoscale embrittlement transition occurs at an interface shear strength scaling as τs~ɛσ rather than τs~σ typically prevailing for micron scale composites, where ɛ and σ are the CNT failure strain and stress, respectively. Interface bonding also lowers the effective fracture strength in SWCNTs, due to formation of defects, but does not play a role in DWCNTs having interwall coupling, which are weaker than SWCNTs but less prone to damage in the outerwall.

  2. Empirical Movement Models for Brain Computer Interfaces.

    PubMed

    Matlack, Charles; Chizeck, Howard; Moritz, Chet T

    2016-06-30

    For brain-computer interfaces (BCIs) which provide the user continuous position control, there is little standardization of performance metrics or evaluative tasks. One candidate metric is Fitts's law, which has been used to describe aimed movements across a range of computer interfaces, and has recently been applied to BCI tasks. Reviewing selected studies, we identify two basic problems with Fitts's law: its predictive performance is fragile, and the estimation of 'information transfer rate' from the model is unsupported. Our main contribution is the adaptation and validation of an alternative model to Fitts's law in the BCI context. We show that the Shannon-Welford model outperforms Fitts's law, showing robust predictive power when target distance and width have disproportionate effects on difficulty. Building on a prior study of the Shannon-Welford model, we show that identified model parameters offer a novel approach to quantitatively assess the role of controldisplay gain in speed/accuracy performance tradeoffs during brain control.

  3. Interface tension in the improved Blume-Capel model

    NASA Astrophysics Data System (ADS)

    Hasenbusch, Martin

    2017-09-01

    We study interfaces with periodic boundary conditions in the low-temperature phase of the improved Blume-Capel model on the simple cubic lattice. The interface free energy is defined by the difference of the free energy of a system with antiperiodic boundary conditions in one of the directions and that of a system with periodic boundary conditions in all directions. It is obtained by integration of differences of the corresponding internal energies over the inverse temperature. These differences can be computed efficiently by using a variance reduced estimator that is based on the exchange cluster algorithm. The interface tension is obtained from the interface free energy by using predictions based on effective interface models. By using our numerical results for the interface tension σ and the correlation length ξ obtained in previous work, we determine the universal amplitude ratios R2 nd ,+=σ0f2nd ,+ 2=0.3863 (6 ) , R2 nd ,-=σ0f2nd ,- 2=0.1028 (1 ) , and Rexp ,-=σ0fexp,- 2=0.1077 (3 ) . Our results are consistent with those obtained previously for the three-dimensional Ising model, confirming the universality hypothesis.

  4. Ontology-based interoperability service for HL7 interfaces implementation.

    PubMed

    González, Carolina; Blobel, Bernd; López, Diego M

    2010-01-01

    Sharing information and knowledge among heterogeneous health information systems requires semantic interoperability. Most integration projects address semantic interoperability by implementing HL7 version 3 standard interfaces. However, it is challenging to achieve computable semantic interoperability with HL7 because of i) the complexity of the standard, requiring HL7 experts in the interface implementation process ii) inconsistencies and overlapping of the different HL7 information models (RIM, D-MIMs, R-MIMs, C-METs), and iii) instability of the different HL7 version 3 models. In this paper, an ontology-based service for health systems semantic interoperability is proposed. This service includes three main components: i) the conceptual model formalization component, responsible to represent the conceptual information models of the applications to be integrated as formal application ontologies; ii) the ontology mapper component; responsible to realize the semantic mapping between the formal application ontologies using a domain ontology, therefore solving inconsistencies found in the source application ontologies; (iii) the automatic interface generator, responsible to create and to maintain HL7 version 3 interfaces. The service presented in this paper is primary focused on the implementation of HL7 interfaces to integrate legacy systems. However being supported in an ontology-based mapping of HL7 information models, it can also support semantic interoperability among healthcare services and applications.

  5. User interface for ground-water modeling: Arcview extension

    USGS Publications Warehouse

    Tsou, M.-S.; Whittemore, D.O.

    2001-01-01

    Numerical simulation for ground-water modeling often involves handling large input and output data sets. A geographic information system (GIS) provides an integrated platform to manage, analyze, and display disparate data and can greatly facilitate modeling efforts in data compilation, model calibration, and display of model parameters and results. Furthermore, GIS can be used to generate information for decision making through spatial overlay and processing of model results. Arc View is the most widely used Windows-based GIS software that provides a robust user-friendly interface to facilitate data handling and display. An extension is an add-on program to Arc View that provides additional specialized functions. An Arc View interface for the ground-water flow and transport models MODFLOW and MT3D was built as an extension for facilitating modeling. The extension includes preprocessing of spatially distributed (point, line, and polygon) data for model input and postprocessing of model output. An object database is used for linking user dialogs and model input files. The Arc View interface utilizes the capabilities of the 3D Analyst extension. Models can be automatically calibrated through the Arc View interface by external linking to such programs as PEST. The efficient pre- and postprocessing capabilities and calibration link were demonstrated for ground-water modeling in southwest Kansas.

  6. Monitoring and control interface based on virtual sensors.

    PubMed

    Escobar, Ricardo F; Adam-Medina, Manuel; García-Beltrán, Carlos D; Olivares-Peregrino, Víctor H; Juárez-Romero, David; Guerrero-Ramírez, Gerardo V

    2014-10-31

    In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors were designed from model-based high-gain observers. To develop the control task, different kinds of control laws were included in the monitoring and control interface. These control laws are PID, MPC and a non-linear model-based control law. The MCI helps to maintain the heat exchanger under operation, even if a temperature outlet sensor fault occurs; in the case of outlet temperature sensor failure, the MCI will display an alarm. The monitoring and control interface is used as a practical tool to support electronic engineering students with heat transfer and control concepts to be applied in a double-pipe heat exchanger pilot plant. The method aims to teach the students through the observation and manipulation of the main variables of the process and by the interaction with the monitoring and control interface (MCI) developed in LabVIEW©. The MCI provides the electronic engineering students with the knowledge of heat exchanger behavior, since the interface is provided with a thermodynamic model that approximates the temperatures and the physical properties of the fluid (density and heat capacity). An advantage of the interface is the easy manipulation of the actuator for an automatic or manual operation. Another advantage of the monitoring and control interface is that all algorithms can be manipulated and modified by the users.

  7. Monitoring and Control Interface Based on Virtual Sensors

    PubMed Central

    Escobar, Ricardo F.; Adam-Medina, Manuel; García-Beltrán, Carlos D.; Olivares-Peregrino, Víctor H.; Juárez-Romero, David; Guerrero-Ramírez, Gerardo V.

    2014-01-01

    In this article, a toolbox based on a monitoring and control interface (MCI) is presented and applied in a heat exchanger. The MCI was programed in order to realize sensor fault detection and isolation and fault tolerance using virtual sensors. The virtual sensors were designed from model-based high-gain observers. To develop the control task, different kinds of control laws were included in the monitoring and control interface. These control laws are PID, MPC and a non-linear model-based control law. The MCI helps to maintain the heat exchanger under operation, even if a temperature outlet sensor fault occurs; in the case of outlet temperature sensor failure, the MCI will display an alarm. The monitoring and control interface is used as a practical tool to support electronic engineering students with heat transfer and control concepts to be applied in a double-pipe heat exchanger pilot plant. The method aims to teach the students through the observation and manipulation of the main variables of the process and by the interaction with the monitoring and control interface (MCI) developed in LabVIEW©. The MCI provides the electronic engineering students with the knowledge of heat exchanger behavior, since the interface is provided with a thermodynamic model that approximates the temperatures and the physical properties of the fluid (density and heat capacity). An advantage of the interface is the easy manipulation of the actuator for an automatic or manual operation. Another advantage of the monitoring and control interface is that all algorithms can be manipulated and modified by the users. PMID:25365462

  8. Acorn: A grid computing system for constraint based modeling and visualization of the genome scale metabolic reaction networks via a web interface

    PubMed Central

    2011-01-01

    Background Constraint-based approaches facilitate the prediction of cellular metabolic capabilities, based, in turn on predictions of the repertoire of enzymes encoded in the genome. Recently, genome annotations have been used to reconstruct genome scale metabolic reaction networks for numerous species, including Homo sapiens, which allow simulations that provide valuable insights into topics, including predictions of gene essentiality of pathogens, interpretation of genetic polymorphism in metabolic disease syndromes and suggestions for novel approaches to microbial metabolic engineering. These constraint-based simulations are being integrated with the functional genomics portals, an activity that requires efficient implementation of the constraint-based simulations in the web-based environment. Results Here, we present Acorn, an open source (GNU GPL) grid computing system for constraint-based simulations of genome scale metabolic reaction networks within an interactive web environment. The grid-based architecture allows efficient execution of computationally intensive, iterative protocols such as Flux Variability Analysis, which can be readily scaled up as the numbers of models (and users) increase. The web interface uses AJAX, which facilitates efficient model browsing and other search functions, and intuitive implementation of appropriate simulation conditions. Research groups can install Acorn locally and create user accounts. Users can also import models in the familiar SBML format and link reaction formulas to major functional genomics portals of choice. Selected models and simulation results can be shared between different users and made publically available. Users can construct pathway map layouts and import them into the server using a desktop editor integrated within the system. Pathway maps are then used to visualise numerical results within the web environment. To illustrate these features we have deployed Acorn and created a web server allowing

  9. Internet-based interface for STRMDEPL08

    USGS Publications Warehouse

    Reeves, Howard W.; Asher, A. Jeremiah

    2010-01-01

    The core of the computer program STRMDEPL08 that estimates streamflow depletion by a pumping well with one of four analytical solutions was re-written in the Javascript software language and made available through an internet-based interface (web page). In the internet-based interface, the user enters data for one of the four analytical solutions, Glover and Balmer (1954), Hantush (1965), Hunt (1999), and Hunt (2003), and the solution is run for constant pumping for a desired number of simulation days. Results are returned in tabular form to the user. For intermittent pumping, the interface allows the user to request that the header information for an input file for the stand-alone executable STRMDEPL08 be created. The user would add the pumping information to this header information and run the STRMDEPL08 executable that is available for download through the U.S. Geological Survey. Results for the internet-based and stand-alone versions of STRMDEPL08 are shown to match.

  10. Ab initio diffuse-interface model for lithiated electrode interface evolution

    NASA Astrophysics Data System (ADS)

    Stournara, Maria E.; Kumar, Ravi; Qi, Yue; Sheldon, Brian W.

    2016-07-01

    The study of chemical segregation at interfaces, and in particular the ability to predict the thickness of segregated layers via analytical expressions or computational modeling, is a fundamentally challenging topic in the design of novel heterostructured materials. This issue is particularly relevant for the phase-field (PF) methodology, which has become a prominent tool for describing phase transitions. These models rely on phenomenological parameters that pertain to the interfacial energy and thickness, quantities that cannot be experimentally measured. Instead of back-calculating these parameters from experimental data, here we combine a set of analytical expressions based on the Cahn-Hilliard approach with ab initio calculations to compute the gradient energy parameter κ and the thickness λ of the segregated Li layer at the LixSi-Cu interface. With this bottom-up approach we calculate the thickness λ of the Li diffuse interface to be on the order of a few nm, in agreement with prior experimental secondary ion mass spectrometry observations. Our analysis indicates that Li segregation is primarily driven by solution thermodynamics, while the strain contribution in this system is relatively small. This combined scheme provides an essential first step in the systematic evaluation of the thermodynamic parameters of the PF methodology, and we believe that it can serve as a framework for the development of quantitative interface models in the field of Li-ion batteries.

  11. A Hybrid Tool for User Interface Modeling and Prototyping

    NASA Astrophysics Data System (ADS)

    Trætteberg, Hallvard

    Although many methods have been proposed, model-based development methods have only to some extent been adopted for UI design. In particular, they are not easy to combine with user-centered design methods. In this paper, we present a hybrid UI modeling and GUI prototyping tool, which is designed to fit better with IS development and UI design traditions. The tool includes a diagram editor for domain and UI models and an execution engine that integrates UI behavior, live UI components and sample data. Thus, both model-based user interface design and prototyping-based iterative design are supported

  12. Estimation of water consumption for ecosystems based on Vegetation Interfaces Processes Model: A case study of the Aksu River Basin, Northwest China.

    PubMed

    Yang, Peng; Xia, Jun; Zhan, Chesheng; Mo, Xingguo; Chen, Xuejuan; Hu, Shi; Chen, Jie

    2017-09-12

    Based on the Moderate Resolution Imaging Spectroradiometer (MODIS) - Normalized Difference Vegetation Index (NDVI), the Vegetation Interfaces Processes (VIP) model simulated the spatio-temporal patterns of actual evapotranspiration (ET) and the water consumption of different ecosystems in the Aksu River Basin, Northwest China between 2000 and 2015. The results revealed that: (1) the applicability of the VIP model was confirmed, with good agreement (R(2)=0.79, P<0.05) between the VIP-ET and water balance model (WB)-ET in the Aksu River Basin; (2)arable land showed the highest annual actual ET per unit pixel (362.4mm/pixel), followed by forest (159.6mm/pixel), and grass land (142.8mm/pixel); (3) water consumption for arable, forest, and grass land were determined as 19.45×10(8), 1.94×10(8), and 28×10(8)m(3)/a, respectively; and (4) there was a significant trend (P<0.05) of increasing water consumption of 0.379×10(8)m(3)/a in the artificial ecosystem, but there was no significant trend in the time series of the natural ecosystem. Overall, the study demonstrated that the VIP model is able to supply important information for water resource management at the catchment-scale. Copyright © 2017. Published by Elsevier B.V.

  13. A Modeling Pattern for Layered System Interfaces

    NASA Technical Reports Server (NTRS)

    Shames, Peter M.; Sarrel, Marc A.

    2015-01-01

    Communications between systems is often initially represented at a single, high level of abstraction, a link between components. During design evolution it is usually necessary to elaborate the interface model, defining it from several different, related viewpoints and levels of abstraction. This paper presents a pattern to model such multi-layered interface architectures simply and efficiently, in a way that supports expression of technical complexity, interfaces and behavior, and analysis of complexity. Each viewpoint and layer of abstraction has its own properties and behaviors. System elements are logically connected both horizontally along the communication path, and vertically across the different layers of protocols. The performance of upper layers depends on the performance of lower layers, yet the implementation of lower layers is intentionally opaque to upper layers. Upper layers are hidden from lower layers except as sources and sinks of data. The system elements may not be linked directly at each horizontal layer but only via a communication path, and end-to-end communications may depend on intermediate components that are hidden from them, but may need to be shown in certain views and analyzed for certain purposes. This architectural model pattern uses methods described in ISO 42010, Recommended Practice for Architectural Description of Software-intensive Systems and CCSDS 311.0-M-1, Reference Architecture for Space Data Systems (RASDS). A set of useful viewpoints and views are presented, along with the associated modeling representations, stakeholders and concerns. These viewpoints, views, and concerns then inform the modeling pattern. This pattern permits viewing the system from several different perspectives and at different layers of abstraction. An external viewpoint treats the systems of interest as black boxes and focuses on the applications view, another view exposes the details of the connections and other components between the black boxes

  14. A damage mechanics based general purpose interface/contact element

    NASA Astrophysics Data System (ADS)

    Yan, Chengyong

    Most of the microelectronics packaging structures consist of layered substrates connected with bonding materials, such as solder or epoxy. Predicting the thermomechanical behavior of these multilayered structures is a challenging task in electronic packaging engineering. In a layered structure the most complex part is always the interfaces between the strates. Simulating the thermo-mechanical behavior of such interfaces, is the main theme of this dissertation. The most commonly used solder material, Pb-Sn alloy, has a very low melting temperature 180sp°C, so that the material demonstrates a highly viscous behavior. And, creep usually dominates the failure mechanism. Hence, the theory of viscoplasticity is adapted to describe the constitutive behavior. In a multilayered assembly each layer has a different coefficient of thermal expansion. Under thermal cycling, due to heat dissipated from circuits, interfaces and interconnects experience low cycle fatigue. Presently, the state-of-the art damage mechanics model used for fatigue life predictions is based on Kachanov (1986) continuum damage model. This model uses plastic strain as a damage criterion. Since plastic strain is a stress path dependent value, the criterion does not yield unique damage values for the same state of stress. In this dissertation a new damage evolution equation based on the second law of thermodynamic is proposed. The new criterion is based on the entropy of the system and it yields unique damage values for all stress paths to the final state of stress. In the electronics industry, there is a strong desire to develop fatigue free interconnections. The proposed interface/contact element can also simulate the behavior of the fatigue free Z-direction thin film interconnections as well as traditional layered interconnects. The proposed interface element can simulate behavior of a bonded interface or unbonded sliding interface, also called contact element. The proposed element was verified against

  15. Modeling the Extreme-Pressure Lubricating Interface

    NASA Astrophysics Data System (ADS)

    Kaltchev, Matey; Gao, Feng; Lara-Romero, Javier; Tysoe, Wilfred

    2005-04-01

    Extreme-pressure lubricants are currently widely used in various areas of applications. However, despite of their common use, the fundamental aspects of the mechanism in which these lubricants reduce the friction coefficient are not clear yet. Earlier macrotribological experiments using chlorinated hydrocarbons have shown remarkable effectiveness. It has been proven that thin films that resemble those formed under tribological conditions can also be synthesized in ultrahigh vacuum when beams of chlorinated hydrocarbons are directed onto a clean iron surface. Here results obtained using X-ray photoelectron spectroscopy, temperature programmed desorption, atomic force microscopy and microtribological measurements of these films are presented. Substantial information about the fundamental properties and structure of this model lubricating interface is revealed. A mechanism of the formation of the interface under tribological conditions is also suggested.

  16. Modeling material interfaces with hybrid adhesion method

    DOE PAGES

    Brown, Nicholas Taylor; Qu, Jianmin; Martinez, Enrique

    2017-01-27

    A molecular dynamics simulation approach is presented to approximate layered material structures using discrete interatomic potentials through classical mechanics and the underlying principles of quantum mechanics. This method isolates the energetic contributions of the system into two pure material layers and an interfacial region used to simulate the adhesive properties of the diffused interface. The strength relationship of the adhesion contribution is calculated through small-scale separation calculations and applied to the molecular surfaces through an inter-layer bond criterion. By segregating the contributions into three regions and accounting for the interfacial excess energies through the adhesive surface bonds, it is possiblemore » to model each material with an independent potential while maintaining an acceptable level of accuracy in the calculation of mechanical properties. This method is intended for the atomistic study of the delamination mechanics, typically observed in thin-film applications. Therefore, the work presented in this paper focuses on mechanical tensile behaviors, with observations in the elastic modulus and the delamination failure mode. To introduce the hybrid adhesion method, we apply the approach to an ideal bulk copper sample, where an interface is created by disassociating the force potential in the middle of the structure. Various mechanical behaviors are compared to a standard EAM control model to demonstrate the adequacy of this approach in a simple setting. In addition, we demonstrate the robustness of this approach by applying it on (1) a Cu-Cu2O interface with interactions between two atom types, and (2) an Al-Cu interface with two dissimilar FCC lattices. These additional examples are verified against EAM and COMB control models to demonstrate the accurate simulation of failure through delamination, and the formation and propagation of dislocations under loads. Finally, the results conclude that by modeling the energy

  17. Modelling heterogeneous interfaces for solar water splitting

    NASA Astrophysics Data System (ADS)

    Pham, Tuan Anh; Ping, Yuan; Galli, Giulia

    2017-04-01

    The generation of hydrogen from water and sunlight offers a promising approach for producing scalable and sustainable carbon-free energy. The key of a successful solar-to-fuel technology is the design of efficient, long-lasting and low-cost photoelectrochemical cells, which are responsible for absorbing sunlight and driving water splitting reactions. To this end, a detailed understanding and control of heterogeneous interfaces between photoabsorbers, electrolytes and catalysts present in photoelectrochemical cells is essential. Here we review recent progress and open challenges in predicting physicochemical properties of heterogeneous interfaces for solar water splitting applications using first-principles-based approaches, and highlights the key role of these calculations in interpreting increasingly complex experiments.

  18. Modelling interfacial cracking with non-matching cohesive interface elements

    NASA Astrophysics Data System (ADS)

    Nguyen, Vinh Phu; Nguyen, Chi Thanh; Bordas, Stéphane; Heidarpour, Amin

    2016-11-01

    Interfacial cracking occurs in many engineering problems such as delamination in composite laminates, matrix/interface debonding in fibre reinforced composites etc. Computational modelling of these interfacial cracks usually employs compatible or matching cohesive interface elements. In this paper, incompatible or non-matching cohesive interface elements are proposed for interfacial fracture mechanics problems. They allow non-matching finite element discretisations of the opposite crack faces thus lifting the constraint on the compatible discretisation of the domains sharing the interface. The formulation is based on a discontinuous Galerkin method and works with both initially elastic and rigid cohesive laws. The proposed formulation has the following advantages compared to classical interface elements: (i) non-matching discretisations of the domains and (ii) no high dummy stiffness. Two and three dimensional quasi-static fracture simulations are conducted to demonstrate the method. Our method not only simplifies the meshing process but also it requires less computational demands, compared with standard interface elements, for problems that involve materials/solids having a large mismatch in stiffnesses.

  19. The Development of Quantitative Structure-Binding Affinity Relationship (QSBR) Models Based on Novel Geometrical Chemical Descriptors of the Protein-Ligand Interfaces

    PubMed Central

    Zhang, Shuxing; Golbraikh, Alexander; Tropsha, Alexander

    2009-01-01

    Novel geometrical chemical descriptors have been derived based on the computational geometry of protein-ligand interfaces and Pauling atomic electronegativities (EN). Delaunay tessellation has been applied to a diverse set of 517 X-ray characterized protein-ligand complexes yielding a unique collection of interfacial nearest neighbor atomic quadruplets for each complex. Each quadruplet composition was characterized by a single descriptor calculated as the sum of the EN values for the four participating atom types. We termed these simple descriptors generated from atomic EN values and derived with the Delaunay Tessellation the ENTess descriptors and used them in the variable selection k-Nearest Neighbor quantitative structure-binding affinity relationship (QSBR) studies of 264 diverse protein-ligand complexes with known binding constants. 24 complexes with chemically dissimilar ligands were set aside as an independent validation set, and the remaining dataset of 240 complexes was divided into multiple training and test sets. The best models were characterized by the leave-one-out cross-validated correlation coefficient q2 as high as 0.66 for the training set and the correlation coefficient R2 as high as 0.83 for the test set. High predictive power of these models was confirmed independently by applying them to the validation set of 24 complexes yielding R2 as high as 0.85. We conclude that QSBR models built with the ENTess descriptors can be instrumental for predicting the binding affinity of receptor-ligand complexes. PMID:16640331

  20. RSVP Keyboard: An EEG Based Typing Interface

    PubMed Central

    Orhan, Umut; Hild, Kenneth E.; Erdogmus, Deniz; Roark, Brian; Oken, Barry; Fried-Oken, Melanie

    2013-01-01

    Humans need communication. The desire to communicate remains one of the primary issues for people with locked-in syndrome (LIS). While many assistive and augmentative communication systems that use various physiological signals are available commercially, the need is not satisfactorily met. Brain interfaces, in particular, those that utilize event related potentials (ERP) in electroencephalography (EEG) to detect the intent of a person noninvasively, are emerging as a promising communication interface to meet this need where existing options are insufficient. Existing brain interfaces for typing use many repetitions of the visual stimuli in order to increase accuracy at the cost of speed. However, speed is also crucial and is an integral portion of peer-to-peer communication; a message that is not delivered timely often looses its importance. Consequently, we utilize rapid serial visual presentation (RSVP) in conjunction with language models in order to assist letter selection during the brain-typing process with the final goal of developing a system that achieves high accuracy and speed simultaneously. This paper presents initial results from the RSVP Keyboard system that is under development. These initial results on healthy and locked-in subjects show that single-trial or few-trial accurate letter selection may be possible with the RSVP Keyboard paradigm. PMID:24500542

  1. A general graphical user interface for automatic reliability modeling

    NASA Technical Reports Server (NTRS)

    Liceaga, Carlos A.; Siewiorek, Daniel P.

    1991-01-01

    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.

  2. The effect of interface properties on nickel base alloy composites

    NASA Technical Reports Server (NTRS)

    Groves, M.; Grossman, T.; Senemeier, M.; Wright, K.

    1995-01-01

    This program was performed to assess the extent to which mechanical behavior models can predict the properties of sapphire fiber/nickel aluminide matrix composites and help guide their development by defining improved combinations of matrix and interface coating. The program consisted of four tasks: 1) selection of the matrices and interface coating constituents using a modeling-based approach; 2) fabrication of the selected materials; 3) testing and evaluation of the materials; and 4) evaluation of the behavior models to develop recommendations. Ni-50Al and Ni-20AI-30Fe (a/o) matrices were selected which gave brittle and ductile behavior, respectively, and an interface coating of PVD YSZ was selected which provided strong bonding to the sapphire fiber. Significant fiber damage and strength loss was observed in the composites which made straightforward comparison of properties with models difficult. Nevertheless, the models selected generally provided property predictions which agreed well with results when fiber degradation was incorporated. The presence of a strong interface bond was felt to be detrimental in the NiAI MMC system where low toughness and low strength were observed.

  3. Individual-Based Modeling of Tuberculosis in a User-Friendly Interface: Understanding the Epidemiological Role of Population Heterogeneity in a City

    PubMed Central

    Prats, Clara; Montañola-Sales, Cristina; Gilabert-Navarro, Joan F.; Valls, Joaquim; Casanovas-Garcia, Josep; Vilaplana, Cristina; Cardona, Pere-Joan; López, Daniel

    2016-01-01

    For millennia tuberculosis (TB) has shown a successful strategy to survive, making it one of the world’s deadliest infectious diseases. This resilient behavior is based not only on remaining hidden in most of the infected population, but also by showing slow evolution in most sick people. The course of the disease within a population is highly related to its heterogeneity. Thus, classic epidemiological approaches with a top-down perspective have not succeeded in understanding its dynamics. In the past decade a few individual-based models were built, but most of them preserved a top-down view that makes it difficult to study a heterogeneous population. We propose an individual-based model developed with a bottom-up approach to studying the dynamics of pulmonary TB in a certain population, considered constant. Individuals may belong to the following classes: healthy, infected, sick, under treatment, and treated with a probability of relapse. Several variables and parameters account for their age, origin (native or immigrant), immunodeficiency, diabetes, and other risk factors (smoking and alcoholism). The time within each infection state is controlled, and sick individuals may show a cavitated disease or not that conditions infectiousness. It was implemented in NetLogo because it allows non-modelers to perform virtual experiments with a user-friendly interface. The simulation was conducted with data from Ciutat Vella, a district of Barcelona with an incidence of 67 TB cases per 100,000 inhabitants in 2013. Several virtual experiments were performed to relate the disease dynamics with the structure of the infected subpopulation (e.g., the distribution of infected times). Moreover, the short-term effect of health control policies on modifying that structure was studied. Results show that the characteristics of the population are crucial for the local epidemiology of TB. The developed user-friendly tool is ready to test control strategies of disease in any city in the

  4. Transforming Collaborative Process Models into Interface Process Models by Applying an MDA Approach

    NASA Astrophysics Data System (ADS)

    Lazarte, Ivanna M.; Chiotti, Omar; Villarreal, Pablo D.

    Collaborative business models among enterprises require defining collaborative business processes. Enterprises implement B2B collaborations to execute these processes. In B2B collaborations the integration and interoperability of processes and systems of the enterprises are required to support the execution of collaborative processes. From a collaborative process model, which describes the global view of the enterprise interactions, each enterprise must define the interface process that represents the role it performs in the collaborative process in order to implement the process in a Business Process Management System. Hence, in this work we propose a method for the automatic generation of the interface process model of each enterprise from a collaborative process model. This method is based on a Model-Driven Architecture to transform collaborative process models into interface process models. By applying this method, interface processes are guaranteed to be interoperable and defined according to a collaborative process.

  5. The use of analytical models in human-computer interface design

    NASA Technical Reports Server (NTRS)

    Gugerty, Leo

    1991-01-01

    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.

  6. Attenuation of numerical artefacts in the modelling of fluid interfaces

    NASA Astrophysics Data System (ADS)

    Evrard, Fabien; van Wachem, Berend G. M.; Denner, Fabian

    2015-11-01

    Numerical artefacts in the modelling of fluid interfaces, such as parasitic currents or spurious capillary waves, present a considerable problem in two-phase flow modelling. Parasitic currents result from an imperfect evaluation of the interface curvature and can severely affect the flow, whereas spatially underresolved (spurious) capillary waves impose strict limits on the time-step and, hence, dictate the required computational resources for surface-tension-dominated flows. By applying an additional shear stress term at the fluid interface, thereby dissipating the surface energy associated with small wavelengths, we have been able to considerably reduce the adverse impact of parasitic currents and mitigate the time-step limit imposed by capillary waves. However, a careful choice of the applied interface viscosity is crucial, since an excess of additional dissipation compromises the accuracy of the solution. We present the derivation of the additional interfacial shear stress term, explain the underlying physical mechanism and discuss the impact on parasitic currents and interface instabilities based on a variety of numerical experiments. We acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) through Grant No. EP/M021556/1 and from PETROBRAS.

  7. ModelMate - A graphical user interface for model analysis

    USGS Publications Warehouse

    Banta, Edward R.

    2011-01-01

    ModelMate is a graphical user interface designed to facilitate use of model-analysis programs with models. This initial version of ModelMate supports one model-analysis program, UCODE_2005, and one model software program, MODFLOW-2005. ModelMate can be used to prepare input files for UCODE_2005, run UCODE_2005, and display analysis results. A link to the GW_Chart graphing program facilitates visual interpretation of results. ModelMate includes capabilities for organizing directories used with the parallel-processing capabilities of UCODE_2005 and for maintaining files in those directories to be identical to a set of files in a master directory. ModelMate can be used on its own or in conjunction with ModelMuse, a graphical user interface for MODFLOW-2005 and PHAST.

  8. Multimodal human-machine interface based on a brain-computer interface and an electrooculography interface.

    PubMed

    Iáñez, Eduardo; Ùbeda, Andrés; Azorín, José M

    2011-01-01

    This paper describes a multimodal interface that combines a Brain-Computer Interface (BCI) with an electrooculography (EOG) interface. The non-invasive spontaneous BCI registers the electrical brain activity through surface electrodes. The EOG interface detects the eye movements through electrodes placed on the face around the eyes. Both kind of signals are registered together and processed to obtain the mental task that the user is thinking and the eye movement performed by the user. Both commands (mental task and eye movement) are combined in order to move a dot in a graphic user interface (GUI). Several experimental tests have been made where the users perform a trajectory to get closer to some targets. To perform the trajectory the user moves the dot in a plane with the EOG interface and using the BCI the dot changes its height.

  9. Constructing a starting 3D shear velocity model with sharp interfaces for SEM-based upper mantle tomography in North America

    NASA Astrophysics Data System (ADS)

    Calo, M.; Bodin, T.; Yuan, H.; Romanowicz, B. A.; Larmat, C. S.; Maceira, M.

    2013-12-01

    this work we propose instead to directly tackle the non-linearity of the inverse problem by using stochastic methods to construct a 3D starting model with a good estimate of the depths of the main layering interfaces. We present preliminary results of the construction of such a starting 3D model based on: (1) Regionalizing the study area to define provinces within which lateral variations are smooth; (2) Applying trans-dimensional stochastic inversion (Bodin et al., 2012) to obtain accurate 1D models in each province as well as the corresponding error distribution, constrained by receiver function and surface wave dispersion data as well as the previously constructed 3D model (name), and (3) connecting these models laterally using data-driven smoothing operators to obtain a starting 3D model with errors. References Bodin, T.,et al. 2012, Transdimensional inversion of receiver functions and surface wave dispersion, J. Geophys. Res., 117, B02301, doi:10.1029/2011JB008560. Yuan and Romanowicz, 2013, in revison. Yuan, H., et al. 2011, 3-D shear wave radially and azimuthally anisotropic velocity model of the North American upper mantle. Geophysical Journal International, 184: 1237-1260. doi: 10.1111/j.1365-246X.2010.04901.x Yuan, H. & Romanowicz, B., 2010. Lithospheric layering in the North American Craton, Nature, 466, 1063-1068.

  10. Atomic Models of Strong Solids Interfaces Viewed as Composite Structures

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  11. Radiation budget measurement/model interface

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Rubin, Carol

    2003-01-01

    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.

  13. Predicting nucleic acid binding interfaces from structural models of proteins

    PubMed Central

    Dror, Iris; Shazman, Shula; Mukherjee, Srayanta; Zhang, Yang; Glaser, Fabian; Mandel-Gutfreund, Yael

    2011-01-01

    The function of DNA- and RNA-binding proteins can be inferred from the characterization and accurate prediction of their binding interfaces. However the main pitfall of various structure-based methods for predicting nucleic acid binding function is that they are all limited to a relatively small number of proteins for which high-resolution three dimensional structures are available. In this study, we developed a pipeline for extracting functional electrostatic patches from surfaces of protein structural models, obtained using the I-TASSER protein structure predictor. The largest positive patches are extracted from the protein surface using the patchfinder algorithm. We show that functional electrostatic patches extracted from an ensemble of structural models highly overlap the patches extracted from high-resolution structures. Furthermore, by testing our pipeline on a set of 55 known nucleic acid binding proteins for which I-TASSER produces high-quality models, we show that the method accurately identifies the nucleic acids binding interface on structural models of proteins. Employing a combined patch approach we show that patches extracted from an ensemble of models better predicts the real nucleic acid binding interfaces compared to patches extracted from independent models. Overall, these results suggest that combining information from a collection of low-resolution structural models could be a valuable approach for functional annotation. We suggest that our method will be further applicable for predicting other functional surfaces of proteins with unknown structure. PMID:22086767

  14. Predicting nucleic acid binding interfaces from structural models of proteins.

    PubMed

    Dror, Iris; Shazman, Shula; Mukherjee, Srayanta; Zhang, Yang; Glaser, Fabian; Mandel-Gutfreund, Yael

    2012-02-01

    The function of DNA- and RNA-binding proteins can be inferred from the characterization and accurate prediction of their binding interfaces. However, the main pitfall of various structure-based methods for predicting nucleic acid binding function is that they are all limited to a relatively small number of proteins for which high-resolution three-dimensional structures are available. In this study, we developed a pipeline for extracting functional electrostatic patches from surfaces of protein structural models, obtained using the I-TASSER protein structure predictor. The largest positive patches are extracted from the protein surface using the patchfinder algorithm. We show that functional electrostatic patches extracted from an ensemble of structural models highly overlap the patches extracted from high-resolution structures. Furthermore, by testing our pipeline on a set of 55 known nucleic acid binding proteins for which I-TASSER produces high-quality models, we show that the method accurately identifies the nucleic acids binding interface on structural models of proteins. Employing a combined patch approach we show that patches extracted from an ensemble of models better predicts the real nucleic acid binding interfaces compared with patches extracted from independent models. Overall, these results suggest that combining information from a collection of low-resolution structural models could be a valuable approach for functional annotation. We suggest that our method will be further applicable for predicting other functional surfaces of proteins with unknown structure. Copyright © 2011 Wiley Periodicals, Inc.

  15. The electric double layer at a rutile TiO₂ water interface modelled using density functional theory based molecular dynamics simulation.

    PubMed

    Cheng, J; Sprik, M

    2014-06-18

    A fully atomistic model of a compact electric double layer at the rutile TiO2(1 1 0)-water interface is constructed by adding protons to bridging oxygens or removing them from H2O molecules adsorbed on terminal metal cation sites. The surface charge is compensated by F(-) or Na(+) counter ions in outer as well as inner sphere coordination. For each of the protonation states the energy of the TiO2 conduction band minimum is determined relative to the standard hydrogen electrode by computing the free energy for the combined insertion of an electron in the solid and a proton in solution away from the double layer using density functional theory based molecular dynamics methods. Interpreted as electrode potentials, this gives an estimate of the capacitance which is compared to the capacitance obtained from the difference in the average electrostatic potentials in the solid and aqueous phase. When aligned at the point of zero charge these two methods lead to almost identical potential-charge profiles. We find that inner sphere complexes have a slightly larger capacitance (0.4 F m(-2)) compared to outer sphere complexes (0.3 F m(-2)).

  16. Multiscale modeling of droplet interface bilayer membrane networks

    PubMed Central

    Freeman, Eric C.; Farimani, Amir B.; Aluru, Narayana R.; Philen, Michael K.

    2015-01-01

    Droplet interface bilayer (DIB) networks are considered for the development of stimuli-responsive membrane-based materials inspired by cellular mechanics. These DIB networks are often modeled as combinations of electrical circuit analogues, creating complex networks of capacitors and resistors that mimic the biomolecular structures. These empirical models are capable of replicating data from electrophysiology experiments, but these models do not accurately capture the underlying physical phenomena and consequently do not allow for simulations of material functionalities beyond the voltage-clamp or current-clamp conditions. The work presented here provides a more robust description of DIB network behavior through the development of a hierarchical multiscale model, recognizing that the macroscopic network properties are functions of their underlying molecular structure. The result of this research is a modeling methodology based on controlled exchanges across the interfaces of neighboring droplets. This methodology is validated against experimental data, and an extension case is provided to demonstrate possible future applications of droplet interface bilayer networks. PMID:26594262

  17. Are Pretty Interfaces Worth the Time? The Effects of User Interface Types on Web-Based Instruction

    ERIC Educational Resources Information Center

    Cheon, Jongpil; Grant, Michael M.

    2009-01-01

    The purpose of this study was to examine the effectiveness of three different interface types on Web-based instruction: a text-based interface, a graphical interface and a metaphorical interface. In order to determine differences among three interface groups, we compared learning performance, cognitive load, usability, and appeal with various data…

  18. Are Pretty Interfaces Worth the Time? The Effects of User Interface Types on Web-Based Instruction

    ERIC Educational Resources Information Center

    Cheon, Jongpil; Grant, Michael M.

    2009-01-01

    The purpose of this study was to examine the effectiveness of three different interface types on Web-based instruction: a text-based interface, a graphical interface and a metaphorical interface. In order to determine differences among three interface groups, we compared learning performance, cognitive load, usability, and appeal with various data…

  19. Wave-based liquid-interface metamaterials

    PubMed Central

    Francois, N; Xia, H; Punzmann, H; Fontana, P W; Shats, M

    2017-01-01

    The control of matter motion at liquid–gas interfaces opens an opportunity to create two-dimensional materials with remotely tunable properties. In analogy with optical lattices used in ultra-cold atom physics, such materials can be created by a wave field capable of dynamically guiding matter into periodic spatial structures. Here we show experimentally that such structures can be realized at the macroscopic scale on a liquid surface by using rotating waves. The wave angular momentum is transferred to floating micro-particles, guiding them along closed trajectories. These orbits form stable spatially periodic patterns, the unit cells of a two-dimensional wave-based material. Such dynamic patterns, a mirror image of the concept of metamaterials, are scalable and biocompatible. They can be used in assembly applications, conversion of wave energy into mean two-dimensional flows and for organising motion of active swimmers. PMID:28181490

  20. Wave-based liquid-interface metamaterials

    NASA Astrophysics Data System (ADS)

    Francois, N.; Xia, H.; Punzmann, H.; Fontana, P. W.; Shats, M.

    2017-02-01

    The control of matter motion at liquid-gas interfaces opens an opportunity to create two-dimensional materials with remotely tunable properties. In analogy with optical lattices used in ultra-cold atom physics, such materials can be created by a wave field capable of dynamically guiding matter into periodic spatial structures. Here we show experimentally that such structures can be realized at the macroscopic scale on a liquid surface by using rotating waves. The wave angular momentum is transferred to floating micro-particles, guiding them along closed trajectories. These orbits form stable spatially periodic patterns, the unit cells of a two-dimensional wave-based material. Such dynamic patterns, a mirror image of the concept of metamaterials, are scalable and biocompatible. They can be used in assembly applications, conversion of wave energy into mean two-dimensional flows and for organising motion of active swimmers.

  1. UIVerify: A Web-Based Tool for Verification and Automatic Generation of User Interfaces

    NASA Technical Reports Server (NTRS)

    Shiffman, Smadar; Degani, Asaf; Heymann, Michael

    2004-01-01

    In this poster, we describe a web-based tool for verification and automatic generation of user interfaces. The verification component of the tool accepts as input a model of a machine and a model of its interface, and checks that the interface is adequate (correct). The generation component of the tool accepts a model of a given machine and the user's task, and then generates a correct and succinct interface. This write-up will demonstrate the usefulness of the tool by verifying the correctness of a user interface to a flight-control system. The poster will include two more examples of using the tool: verification of the interface to an espresso machine, and automatic generation of a succinct interface to a large hypothetical machine.

  2. UIVerify: A Web-Based Tool for Verification and Automatic Generation of User Interfaces

    NASA Technical Reports Server (NTRS)

    Shiffman, Smadar; Degani, Asaf; Heymann, Michael

    2004-01-01

    In this poster, we describe a web-based tool for verification and automatic generation of user interfaces. The verification component of the tool accepts as input a model of a machine and a model of its interface, and checks that the interface is adequate (correct). The generation component of the tool accepts a model of a given machine and the user's task, and then generates a correct and succinct interface. This write-up will demonstrate the usefulness of the tool by verifying the correctness of a user interface to a flight-control system. The poster will include two more examples of using the tool: verification of the interface to an espresso machine, and automatic generation of a succinct interface to a large hypothetical machine.

  3. Developing A Laser Shockwave Model For Characterizing Diffusion Bonded Interfaces

    SciTech Connect

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

    2014-07-01

    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

  4. Quantitative model studies for interfaces in organic electronic devices

    NASA Astrophysics Data System (ADS)

    Gottfried, J. Michael

    2016-11-01

    In organic light-emitting diodes and similar devices, organic semiconductors are typically contacted by metal electrodes. Because the resulting metal/organic interfaces have a large impact on the performance of these devices, their quantitative understanding is indispensable for the further rational development of organic electronics. A study by Kröger et al (2016 New J. Phys. 18 113022) of an important single-crystal based model interface provides detailed insight into its geometric and electronic structure and delivers valuable benchmark data for computational studies. In view of the differences between typical surface-science model systems and real devices, a ‘materials gap’ is identified that needs to be addressed by future research to make the knowledge obtained from fundamental studies even more beneficial for real-world applications.

  5. Building Subsurface Velocity Models with Sharp Interfaces Using Interface-Guided Seismic Full-Waveform Inversion

    NASA Astrophysics Data System (ADS)

    Lin, Youzuo; Huang, Lianjie

    2017-07-01

    Reverse-time migration has the potential to image complex subsurface structures, including steeply-dipping fault zones, but the method requires an accurate velocity model. Acoustic- and elastic-waveform inversion is a promising tool for high-resolution velocity model building. Because of the ill-posedness of acoustic- and elastic-waveform inversion, it is a great challenge to obtain accurate velocity models containing sharp interfaces. To improve velocity model building, we develop an acoustic- and elastic-waveform inversion method with an interface-guided modified total-variation regularization scheme to improve the inversion accuracy and robustness, particularly for models with sharp interfaces and steeply-dipping fault zones with widths much smaller than the seismic wavelength. The new regularization scheme incorporates interface information into seismic full-waveform inversion. The interface information of subsurface interfaces is obtained iteratively using migration imaging during waveform inversion. Seismic migration is robust for subsurface imaging. Our new acoustic- and elastic-waveform inversion takes advantage of the robustness of migration imaging to improve velocity estimation. We use synthetic seismic data for a complex model containing sharp interfaces and several steeply-dipping fault zones to validate the improved capability of our new acoustic- and elastic-waveform inversion method. Our inversion results are much better than those produced without using interface-guided regularization. Acoustic- and elastic-waveform inversion with an interface-guided modified total-variation regularization scheme has the potential to accurately build subsurface velocity models with sharp interfaces and/or steep fault zones.

  6. Language Model Applications to Spelling with Brain-Computer Interfaces

    PubMed Central

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

    2014-01-01

    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

  7. Physical models of hydrofracturing across material interfaces

    SciTech Connect

    Blair, S.C.; Thorpe, R.K.; Heuze, F.E.

    1988-10-01

    We have performed a series of laboratory tests to study the propagation of a hydrofracture into and through an interface between two rock-like materials. The aim of this research is to provide improved diagnostics for stimulating lenticular gas sand reservoirs by interpreting features of the injection pressure-time record caused by interaction of a hydrofracture with a geologic discontinuity. Results will also be used to validate conceptual models of hydrofracture behavior in discontinuous media, such as are embodied in the LLNL FEFFLAP code, a two-dimensional fracture propagation computer program. We prepared test specimens by embedding sandstone tablets (lenses) in blocks of gypsum cement. These blocks were hydrofractured under true triaxial loading conditions, at a constant injection rate. The injection path was designed so that we obtained a single-wing fracture, propagating in a plane perpendicular to the interface. The vertical extent of the fractures was controlled by means of wire mesh screen embedded in the blocks, perpendicular to the injection tube. Growth of the fractures was tracked via extension failure of fine tungsten wires embedded in the gypsum. After testing, we dissected the blocks and recorded the extent of fracturing and fluid penetration. Cross-sections of the fractures indicate that they were of constant height and propagated through the sandstone tablet. All the fractures showed step-crack behavior upon entering or exiting the sandstone tablet. Pressure-time and fracture tracking data were consistent for all tests. Distinct step increases on the pressure- time record were also noted in all tests, and are related to the interaction of the hydrofracture with the sandstone lens. 16 refs., 19 figs., 4 tabs.

  8. Asymptotics and numerical efficiency of the Allen-Cahn model for phase interfaces with low energy in solids

    NASA Astrophysics Data System (ADS)

    Alber, Hans-Dieter

    2017-05-01

    We study how the propagation speed of interfaces in the Allen-Cahn phase field model for phase transformations in solids consisting of the elasticity equations and the Allen-Cahn equation depends on two parameters of the model. The two parameters control the interface energy and the interface width, but change also the interface speed. To this end, we derive an asymptotic expansion of second order for the interface speed, called the kinetic relation, and prove that it is uniformly valid in both parameters. As a consequence, we show that the model error is proportional to the interface width divided by the interface energy. We conclude that simulations of interfaces with low interface energy based on this model require a very small interface width, implying a large numerical effort. Effective simulations thus need adaptive mesh refinement or other advanced techniques.

  9. Optimization of a Thermodynamic Model Using a Dakota Toolbox Interface

    NASA Astrophysics Data System (ADS)

    Cyrus, J.; Jafarov, E. E.; Schaefer, K. M.; Wang, K.; Clow, G. D.; Piper, M.; Overeem, I.

    2016-12-01

    Scientific modeling of the Earth physical processes is an important driver of modern science. The behavior of these scientific models is governed by a set of input parameters. It is crucial to choose accurate input parameters that will also preserve the corresponding physics being simulated in the model. In order to effectively simulate real world processes the models output data must be close to the observed measurements. To achieve this optimal simulation, input parameters are tuned until we have minimized the objective function, which is the error between the simulation model outputs and the observed measurements. We developed an auxiliary package, which serves as a python interface between the user and DAKOTA. The package makes it easy for the user to conduct parameter space explorations, parameter optimizations, as well as sensitivity analysis while tracking and storing results in a database. The ability to perform these analyses via a Python library also allows the users to combine analysis techniques, for example finding an approximate equilibrium with optimization then immediately explore the space around it. We used the interface to calibrate input parameters for the heat flow model, which is commonly used in permafrost science. We performed optimization on the first three layers of the permafrost model, each with two thermal conductivity coefficients input parameters. Results of parameter space explorations indicate that the objective function not always has a unique minimal value. We found that gradient-based optimization works the best for the objective functions with one minimum. Otherwise, we employ more advanced Dakota methods such as genetic optimization and mesh based convergence in order to find the optimal input parameters. We were able to recover 6 initially unknown thermal conductivity parameters within 2% accuracy of their known values. Our initial tests indicate that the developed interface for the Dakota toolbox could be used to perform

  10. Polymer based interfaces as bioinspired 'smart skins'.

    PubMed

    De Rossi, Danilo; Carpi, Federico; Scilingo, Enzo Pasquale

    2005-11-30

    This work reports on already achieved results and ongoing research on the development of complex interfaces between humans and external environment, based on organic synthetic materials and used as smart 'artificial skins'. They are conceived as wearable and flexible systems with multifunctional characteristics. Their features are designed to mimic or augment a broad-spectrum of properties shown by biological skins of humans and/or animals. The discussion is here limited to those properties whose mimicry/augmentation is achievable with currently available technologies based on polymers and oligomers. Such properties include tactile sensing, thermal sensing/regulation, environmental energy harvesting, chromatic mimetism, ultra-violet protection, adhesion and surface mediation of mobility. Accordingly, bioinspired devices and structures, proposed as suitable functional analogous of natural architectures, are analysed. They consist of organic piezoelectric sensors, thermoelectric and pyroelectric sensors and generators, photoelectric generators, thermal and ultra-violet protection systems, electro-, photo- and thermo-chromic devices, as well as structures for improved adhesion and reduced fluid-dynamic friction.

  11. Bacterial Adhesion to Hexadecane (Model NAPL)-Water Interfaces

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.

    1998-01-01

    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.

  13. ShowFlow: A practical interface for groundwater modeling

    SciTech Connect

    Tauxe, J.D.

    1990-12-01

    ShowFlow was created to provide a user-friendly, intuitive environment for researchers and students who use computer modeling software. What traditionally has been a workplace available only to those familiar with command-line based computer systems is now within reach of almost anyone interested in the subject of modeling. In the case of this edition of ShowFlow, the user can easily experiment with simulations using the steady state gaussian plume groundwater pollutant transport model SSGPLUME, though ShowFlow can be rewritten to provide a similar interface for any computer model. Included in this thesis is all the source code for both the ShowFlow application for Microsoft{reg sign} Windows{trademark} and the SSGPLUME model, a User's Guide, and a Developer's Guide for converting ShowFlow to run other model programs. 18 refs., 13 figs.

  14. Analytical and numerical modeling of non-collinear shear wave mixing at an imperfect interface

    NASA Astrophysics Data System (ADS)

    Zhang, Ziyin; Nagy, Peter B.; Hassan, Waled

    2016-02-01

    Non-collinear shear wave mixing at an imperfect interface between two solids can be exploited for nonlinear ultrasonic assessment of bond quality. In this study we developed two analytical models for nonlinear imperfect interfaces. The first model uses a finite nonlinear interfacial stiffness representation of an imperfect interface of vanishing thickness, while the second model relies on a thin nonlinear interphase layer to represent an imperfect interface region. The second model is actually a derivative of the first model obtained by calculating the equivalent interfacial stiffness of a thin isotropic nonlinear interphase layer in the quasi-static approximation. The predictions of both analytical models were numerically verified by comparison to COMSOL finite element simulations. These models can accurately predict the excess nonlinearity caused by interface imperfections based on the strength of the reflected and transmitted mixed longitudinal waves produced by them under non-collinear shear wave interrogation.

  15. A Rigorous Sharp Interface Limit of a Diffuse Interface Model Related to Tumor Growth

    NASA Astrophysics Data System (ADS)

    Rocca, Elisabetta; Scala, Riccardo

    2017-06-01

    In this paper, we study the rigorous sharp interface limit of a diffuse interface model related to the dynamics of tumor growth, when a parameter ɛ, representing the interface thickness between the tumorous and non-tumorous cells, tends to zero. More in particular, we analyze here a gradient-flow-type model arising from a modification of the recently introduced model for tumor growth dynamics in Hawkins-Daruud et al. (Int J Numer Math Biomed Eng 28:3-24, 2011) (cf. also Hilhorst et al. Math Models Methods Appl Sci 25:1011-1043, 2015). Exploiting the techniques related to both gradient flows and gamma convergence, we recover a condition on the interface Γ relating the chemical and double-well potentials, the mean curvature, and the normal velocity.

  16. A Rigorous Sharp Interface Limit of a Diffuse Interface Model Related to Tumor Growth

    NASA Astrophysics Data System (ADS)

    Rocca, Elisabetta; Scala, Riccardo

    2016-11-01

    In this paper, we study the rigorous sharp interface limit of a diffuse interface model related to the dynamics of tumor growth, when a parameter ɛ, representing the interface thickness between the tumorous and non-tumorous cells, tends to zero. More in particular, we analyze here a gradient-flow-type model arising from a modification of the recently introduced model for tumor growth dynamics in Hawkins-Daruud et al. (Int J Numer Math Biomed Eng 28:3-24, 2011) (cf. also Hilhorst et al. Math Models Methods Appl Sci 25:1011-1043, 2015). Exploiting the techniques related to both gradient flows and gamma convergence, we recover a condition on the interface Γ relating the chemical and double-well potentials, the mean curvature, and the normal velocity.

  17. Control Strategies for the DAB Based PV Interface System.

    PubMed

    El-Helw, Hadi M; Al-Hasheem, Mohamed; Marei, Mostafa I

    2016-01-01

    This paper presents an interface system based on the Dual Active Bridge (DAB) converter for Photovoltaic (PV) arrays. Two control strategies are proposed for the DAB converter to harvest the maximum power from the PV array. The first strategy is based on a simple PI controller to regulate the terminal PV voltage through the phase shift angle of the DAB converter. The Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) technique is utilized to set the reference of the PV terminal voltage. The second strategy presented in this paper employs the Artificial Neural Network (ANN) to directly set the phase shift angle of the DAB converter that results in harvesting maximum power. This feed-forward strategy overcomes the stability issues of the feedback strategy. The proposed PV interface systems are modeled and simulated using MATLAB/SIMULINK and the EMTDC/PSCAD software packages. The simulation results reveal accurate and fast response of the proposed systems. The dynamic performance of the proposed feed-forward strategy outdoes that of the feedback strategy in terms of accuracy and response time. Moreover, an experimental prototype is built to test and validate the proposed PV interface system.

  18. Control Strategies for the DAB Based PV Interface System

    PubMed Central

    El-Helw, Hadi M.; Al-Hasheem, Mohamed; Marei, Mostafa I.

    2016-01-01

    This paper presents an interface system based on the Dual Active Bridge (DAB) converter for Photovoltaic (PV) arrays. Two control strategies are proposed for the DAB converter to harvest the maximum power from the PV array. The first strategy is based on a simple PI controller to regulate the terminal PV voltage through the phase shift angle of the DAB converter. The Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) technique is utilized to set the reference of the PV terminal voltage. The second strategy presented in this paper employs the Artificial Neural Network (ANN) to directly set the phase shift angle of the DAB converter that results in harvesting maximum power. This feed-forward strategy overcomes the stability issues of the feedback strategy. The proposed PV interface systems are modeled and simulated using MATLAB/SIMULINK and the EMTDC/PSCAD software packages. The simulation results reveal accurate and fast response of the proposed systems. The dynamic performance of the proposed feed-forward strategy outdoes that of the feedback strategy in terms of accuracy and response time. Moreover, an experimental prototype is built to test and validate the proposed PV interface system. PMID:27560138

  19. Direct measurement of acid-base interaction energy at solid interfaces.

    PubMed

    Kurian, Anish; Prasad, Shishir; Dhinojwala, Ali

    2010-12-07

    We have studied acid-base interactions at solid-liquid and solid-solid interfaces using interface-sensitive sum frequency generation (SFG) spectroscopy. The shift of the sapphire hydroxyl peak in contact with several polar and nonpolar liquids and polymers was used to determine the interaction energy. The trend in the interaction energies cannot be explained by measuring only water contact angles. Molecular rearrangements at the sapphire interface, to maximize the interaction of the acid-base groups, play a dominant role, and these effects are not accounted for in the current theoretical models. These results provide important insights into understanding adhesion, friction, and wetting on solid interfaces.

  20. A conservative interface-interaction model with insoluble surfactant

    NASA Astrophysics Data System (ADS)

    Schranner, Felix S.; Adams, Nikolaus A.

    2016-12-01

    In this paper we extend the conservative interface-interaction method of Hu et al. (2006) [34], adapted for weakly-compressible flows by Luo et al. (2015) [37], to include the effects of viscous, capillary, and Marangoni stresses consistently as momentum-exchange terms at the sharp interface. The interface-interaction method is coupled with insoluble surfactant transport which employs the underlying sharp-interface representation. Unlike previous methods, we thus achieve discrete global conservation in terms of interface interactions and a consistently sharp interface representation. The interface is reconstructed locally, and a sub-cell correction of the interface curvature improves the evaluation of capillary stresses and surfactant diffusion in particular for marginal mesh resolutions. For a range of numerical test cases we demonstrate accuracy and robustness of the method. In particular, we show that the method is at least as accurate as previous diffuse-interface models while exhibiting throughout the considered test cases improved computational efficiency. We believe that the method is attractive for high-resolution level-set interface-tracking simulations as it straightforwardly incorporates the effects of variable surface tension into the underlying conservative interface-interaction approach.

  1. Behavior of asphaltene model compounds at w/o interfaces.

    PubMed

    Nordgård, Erland L; Sørland, Geir; Sjöblom, Johan

    2010-02-16

    Asphaltenes, present in significant amounts in heavy crude oil, contains subfractions capable of stabilizing water-in-oil emulsions. Still, the composition of these subfractions is not known in detail, and the actual mechanism behind emulsion stability is dependent on perceived interfacial concentrations and compositions. This study aims at utilizing polyaromatic surfactants which contains an acidic moiety as model compounds for the surface-active subfraction of asphaltenes. A modified pulse-field gradient (PFG) NMR method has been used to study droplet sizes and stability of emulsions prepared with asphaltene model compounds. The method has been compared to the standard microscopy droplet counting method. Arithmetic and volumetric mean droplet sizes as a function of surfactant concentration and water content clearly showed that the interfacial area was dependent on the available surfactant at the emulsion interface. Adsorption of the model compounds onto hydrophilic silica has been investigated by UV depletion, and minor differences in the chemical structure of the model compounds caused significant differences in the affinity toward this highly polar surface. The cross-sectional areas obtained have been compared to areas from the surface-to-volume ratio found by NMR and gave similar results for one of the two model compounds. The mean molecular area for this compound suggested a tilted geometry of the aromatic core with respect to the interface, which has also been proposed for real asphaltenic samples. The film behavior was further investigated using a liquid-liquid Langmuir trough supporting the ability to form stable interfacial films. This study supports that acidic, or strong hydrogen-bonding fractions, can promote stable water-in-oil emulsion. The use of model compounds opens up for studying emulsion behavior and demulsifier efficiency based on true interfacial concentrations rather than perceived interfaces.

  2. Metal oxide-graphene field-effect transistor: interface trap density extraction model

    PubMed Central

    Najam, Faraz; Lau, Kah Cheong; Lim, Cheng Siong; Yu, Yun Seop

    2016-01-01

    Summary A simple to implement model is presented to extract interface trap density of graphene field effect transistors. The presence of interface trap states detrimentally affects the device drain current–gate voltage relationship I ds–V gs. At the moment, there is no analytical method available to extract the interface trap distribution of metal-oxide-graphene field effect transistor (MOGFET) devices. The model presented here extracts the interface trap distribution of MOGFET devices making use of available experimental capacitance–gate voltage C tot–V gs data and a basic set of equations used to define the device physics of MOGFET devices. The model was used to extract the interface trap distribution of 2 experimental devices. Device parameters calculated using the extracted interface trap distribution from the model, including surface potential, interface trap charge and interface trap capacitance compared very well with their respective experimental counterparts. The model enables accurate calculation of the surface potential affected by trap charge. Other models ignore the effect of trap charge and only calculate the ideal surface potential. Such ideal surface potential when used in a surface potential based drain current model will result in an inaccurate prediction of the drain current. Accurate calculation of surface potential that can later be used in drain current model is highlighted as a major advantage of the model. PMID:27826511

  3. Metal oxide-graphene field-effect transistor: interface trap density extraction model.

    PubMed

    Najam, Faraz; Lau, Kah Cheong; Lim, Cheng Siong; Yu, Yun Seop; Tan, Michael Loong Peng

    2016-01-01

    A simple to implement model is presented to extract interface trap density of graphene field effect transistors. The presence of interface trap states detrimentally affects the device drain current-gate voltage relationship Ids-Vgs. At the moment, there is no analytical method available to extract the interface trap distribution of metal-oxide-graphene field effect transistor (MOGFET) devices. The model presented here extracts the interface trap distribution of MOGFET devices making use of available experimental capacitance-gate voltage Ctot-Vgs data and a basic set of equations used to define the device physics of MOGFET devices. The model was used to extract the interface trap distribution of 2 experimental devices. Device parameters calculated using the extracted interface trap distribution from the model, including surface potential, interface trap charge and interface trap capacitance compared very well with their respective experimental counterparts. The model enables accurate calculation of the surface potential affected by trap charge. Other models ignore the effect of trap charge and only calculate the ideal surface potential. Such ideal surface potential when used in a surface potential based drain current model will result in an inaccurate prediction of the drain current. Accurate calculation of surface potential that can later be used in drain current model is highlighted as a major advantage of the model.

  4. Multibody dynamics model building using graphical interfaces

    NASA Technical Reports Server (NTRS)

    Macala, Glenn A.

    1989-01-01

    In recent years, the extremely laborious task of manually deriving equations of motion for the simulation of multibody spacecraft dynamics has largely been eliminated. Instead, the dynamicist now works with commonly available general purpose dynamics simulation programs which generate the equations of motion either explicitly or implicitly via computer codes. The user interface to these programs has predominantly been via input data files, each with its own required format and peculiarities, causing errors and frustrations during program setup. Recent progress in a more natural method of data input for dynamics programs: the graphical interface, is described.

  5. XBI: a Java-based interface to FPGA hardware

    NASA Astrophysics Data System (ADS)

    Guccione, Steven A.; Levi, Delon

    1998-10-01

    XBI(tm), the Xilinx Bitstream Interface is a set of Java (tm) classes which provide an Application Program Interface (API) into the Xilinx FPGA bitstream. This interface operates on either bitstreams generated by Xilinx design tools, or on bitstreams read back from actual hardware. This provides the capability of designing, modifying and dynamically modifying circuits in Xilinx XC4000 (tm) series FPGA devices. The programming model used by XBI is a 2D array of Configurable Logic Blocks (CLBs). Each CLB is referenced by a row and column, and all configurable resources in the selected CLB may be set or probed. Additionally, control of all routing resources adjacent to the selected CLB are made available. Because the code is written in Java, compilation times are very fast, and because control is at the CLB level, bitstreams can typically be modified or generated in times on the order of one second or less. This API has been used to construct complete circuits and to modify existing circuits. In addition, the object oriented support in the Java programming language has permitted a small library of parameterizable, object oriented macro circuits or Cores to be implemented. Finally, this API may be used as a base to construct other tools. This includes traditional design tools for performing tasks such as circuit placement and routing, as well as application specific tools to perform more narrowly defined tasks.

  6. User's Manual for the Object User Interface (OUI): An Environmental Resource Modeling Framework

    USGS Publications Warehouse

    Markstrom, Steven L.; Koczot, Kathryn M.

    2008-01-01

    The Object User Interface is a computer application that provides a framework for coupling environmental-resource models and for managing associated temporal and spatial data. The Object User Interface is designed to be easily extensible to incorporate models and data interfaces defined by the user. Additionally, the Object User Interface is highly configurable through the use of a user-modifiable, text-based control file that is written in the eXtensible Markup Language. The Object User Interface user's manual provides (1) installation instructions, (2) an overview of the graphical user interface, (3) a description of the software tools, (4) a project example, and (5) specifications for user configuration and extension.

  7. Electrochemical Stability of Model Polymer Electrolyte/Electrode Interfaces

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel; Yang, Guang

    2015-03-01

    Polymer electrolytes are promising materials for high energy density rechargeable batteries. However, typical polymer electrolytes are not electrochemically stable at the charging voltage of advanced positive electrode materials. Although not yet reported in literature, decomposition is expected to adversely affect the performance and lifetime of polymer-electrolyte-based batteries. In an attempt to better understand polymer electrolyte oxidation and design stable polymer electrolyte/positive electrode interfaces, we are studying electron transfer across model interfaces comprising gold nanoparticles and organic protecting ligands assembled into monolayer films. Gold nanoparticles provide large interfacial surface area yielding a measurable electrochemical signal. They are inert and hence non-reactive with most polymer electrolytes and lithium salts. The surface can be easily modified with ligands of different chemistry and molecular weight. In our study, poly(ethylene oxide) (PEO) will serve as the polymer electrolyte and lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI) will be the lithium salt. The effect of ligand type and molecular weight on both optical and electrical properties of the gold nanoparticle film will be presented. Finally, the electrochemical stability of the electrode/electrolyte interface and its dependence on interfacial properties will be presented.

  8. Layering and wetting transitions for an interface model

    NASA Astrophysics Data System (ADS)

    Solé, Salvador Miracle

    2011-03-01

    We study the solid-on-solid interface model above a horizontal wall in three dimensional space, with an attractive interaction when the interface is in contact with the wall, at low temperatures. The system presents a sequence of layering transitions, whose levels increase with the temperature, before the complete wetting above a certain value of this quantity.

  9. Rapid Prototyping of Hydrologic Model Interfaces with IPython

    NASA Astrophysics Data System (ADS)

    Farthing, M. W.; Winters, K. D.; Ahmadia, A. J.; Hesser, T.; Howington, S. E.; Johnson, B. D.; Tate, J.; Kees, C. E.

    2014-12-01

    A significant gulf still exists between the state of practice and state of the art in hydrologic modeling. Part of this gulf is due to the lack of adequate pre- and post-processing tools for newly developed computational models. The development of user interfaces has traditionally lagged several years behind the development of a particular computational model or suite of models. As a result, models with mature interfaces often lack key advancements in model formulation, solution methods, and/or software design and technology. Part of the problem has been a focus on developing monolithic tools to provide comprehensive interfaces for the entire suite of model capabilities. Such efforts require expertise in software libraries and frameworks for creating user interfaces (e.g., Tcl/Tk, Qt, and MFC). These tools are complex and require significant investment in project resources (time and/or money) to use. Moreover, providing the required features for the entire range of possible applications and analyses creates a cumbersome interface. For a particular site or application, the modeling requirements may be simplified or at least narrowed, which can greatly reduce the number and complexity of options that need to be accessible to the user. However, monolithic tools usually are not adept at dynamically exposing specific workflows. Our approach is to deliver highly tailored interfaces to users. These interfaces may be site and/or process specific. As a result, we end up with many, customized interfaces rather than a single, general-use tool. For this approach to be successful, it must be efficient to create these tailored interfaces. We need technology for creating quality user interfaces that is accessible and has a low barrier for integration into model development efforts. Here, we present efforts to leverage IPython notebooks as tools for rapid prototyping of site and application-specific user interfaces. We provide specific examples from applications in near

  10. Microcomputer-Based User Interface for Library Online Catalogue.

    ERIC Educational Resources Information Center

    Cheng, Chin-Chuan

    A microcomputer-based user interface was developed and programmed for the library computer systems at the University of Illinois. Designed to provide user-friendly access to the two components of the online catalog on the library's IBM 3081 mainframe computer, the interface program resides on the IBM PC and queries the user in natural written…

  11. ORIGAMI -- The Oak Ridge Geometry Analysis and Modeling Interface

    SciTech Connect

    Burns, T.J.

    1996-04-01

    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.

  12. Developing Concept-Based User Interfaces for Scientific Computing

    SciTech Connect

    Chin, George; Stephan, Eric G.; Gracio, Deborah K.; Kuchar, Olga A.; Whitney, Paul D.; Schuchardt, Karen L.

    2006-09-01

    From our interactions with researchers from different scientific fields and disciplines, we have observed that scientists often describe and convey concepts, theories, processes, and results using basic graphs and diagrams. Semantic graphs such as these provide a universal language that all scientists may apply to document their scientific knowledge and to communicate this knowledge to others. Furthermore, studies have shown that the cognitive processing of complex subject matter is improved when the structure of ideas and concepts are made explicit [39] and that semantic graphs may serve as effective “scaffolds” for cognitive processing [29]. At Pacific Northwest National Laboratory, we are deploying semantic graphs within scientific computing systems as central user representations of scientific knowledge. These systems provide concept-based user interfaces that allow scientists to visually define and capture conceptual models of their scientific problems, hypotheses, theories, and processes. Once defined, the visual models then become interaction framework for accessing and applying scientific and computational resources and capabilities. In this paper, through the examination of three visual research systems, we illustrate different ways concept-based user interfaces and semantic graph knowledge representations may make scientific knowledge concrete, usable, shareable, and computable in scientific computing systems.

  13. Disturbed state model for sand-geosynthetic interfaces and application to pull-out tests

    NASA Astrophysics Data System (ADS)

    Pal, Surajit; Wije Wathugala, G.

    1999-12-01

    Successful numerical simulation of geosynthetic-reinforced earth structures depends on selecting proper constitutive models for soils, geosynthetics and soil-geosynthetic interfaces. Many constitutive models are available for modelling soils and geosynthetics. However, constitutive models for soil-geosynthetic interfaces which can capture most of the important characteristics of interface response are not readily available. In this paper, an elasto-plastic constitutive model based on the disturbed state concept (DSC) for geosynthetic-soil interfaces has been presented. The proposed model is capable of capturing most of the important characteristics of interface response, such as dilation, hardening and softening. The behaviour of interfaces under the direct shear test has been predicted by the model. The present model has been implemented in the finite element procedure in association with the thin-layer element. Five pull-out tests with two different geogrids have been simulated numerically using FEM. For the calibration of the constitutive models used in FEM, the standard laboratory tests used are: (1) triaxial tests for the sand, (2) direct shear tests for the interfaces and (3) axial tension tests for the geogrids. The results of the finite element simulations of pull-out tests agree well with the test data. The proposed model can be used for the stress-deformation study of geosynthetic-reinforced embankments through numerical simulation.

  14. Modeling organohalide perovskites for photovoltaic applications: From materials to interfaces

    NASA Astrophysics Data System (ADS)

    de Angelis, Filippo

    2015-03-01

    The field of hybrid/organic photovoltaics has been revolutionized in 2012 by the first reports of solid-state solar cells based on organohalide perovskites, now topping at 20% efficiency. First-principles modeling has been widely applied to the dye-sensitized solar cells field, and more recently to perovskite-based solar cells. The computational design and screening of new materials has played a major role in advancing the DSCs field. Suitable modeling strategies may also offer a view of the crucial heterointerfaces ruling the device operational mechanism. I will illustrate how simulation tools can be employed in the emerging field of perovskite solar cells. The performance of the proposed simulation toolbox along with the fundamental modeling strategies are presented using selected examples of relevant materials and interfaces. The main issue with hybrid perovskite modeling is to be able to accurately describe their structural, electronic and optical features. These materials show a degree of short range disorder, due to the presence of mobile organic cations embedded within the inorganic matrix, requiring to average their properties over a molecular dynamics trajectory. Due to the presence of heavy atoms (e.g. Sn and Pb) their electronic structure must take into account spin-orbit coupling (SOC) in an effective way, possibly including GW corrections. The proposed SOC-GW method constitutes the basis for tuning the materials electronic and optical properties, rationalizing experimental trends. Modeling charge generation in perovskite-sensitized TiO2 interfaces is then approached based on a SOC-DFT scheme, describing alignment of energy levels in a qualitatively correct fashion. The role of interfacial chemistry on the device performance is finally discussed. The research leading to these results has received funding from the European Union Seventh Framework Programme [FP7/2007 2013] under Grant Agreement No. 604032 of the MESO project.

  15. An IBM PC Based ARINC Interface

    DTIC Science & Technology

    1993-03-01

    permission. Copyright is the responsibility of the Director Publishing and Marketing, AGPS. Enquiries should be directed to the Manager, AGPS Press ...types; internal or external. An internal event is generated when the user presses the "p" key at the runtime stage. A message is sent to the interface...the user presses the carriage return key to move on. At this point the user is prompted to specify if all occurences of the selected labels are to be

  16. Diffuse Interface Methods for Modeling Drug-Eluting Stent Coatings.

    PubMed

    Saylor, David M; Forrey, Christopher; Kim, Chang-Soo; Warren, James A

    2016-02-01

    An overview of diffuse interface models specific to drug-eluting stent coatings is presented. Microscale heterogeneities, both in the coating and use environment, dictate the performance of these coatings. Using diffuse interface methods, these heterogeneities can be explicitly incorporated into the model equations with relative ease. This enables one to predict the complex microstructures that evolve during coating fabrication and subsequent impact on drug release. Examples are provided that illustrate the wide range of phenomena that can be addressed with diffuse interface models including: crystallization, constrained phase separation, hydrolytic degradation, and heterogeneous binding. Challenges associated with the lack of material property data and numerical solution of the model equations are also highlighted. Finally, in light of these potential drawbacks, the potential to utilize diffuse interface models to help guide product and process development is discussed.

  17. Knowledge-based control of an adaptive interface

    NASA Technical Reports Server (NTRS)

    Lachman, Roy

    1989-01-01

    The analysis, development strategy, and preliminary design for an intelligent, adaptive interface is reported. The design philosophy couples knowledge-based system technology with standard human factors approaches to interface development for computer workstations. An expert system has been designed to drive the interface for application software. The intelligent interface will be linked to application packages, one at a time, that are planned for multiple-application workstations aboard Space Station Freedom. Current requirements call for most Space Station activities to be conducted at the workstation consoles. One set of activities will consist of standard data management services (DMS). DMS software includes text processing, spreadsheets, data base management, etc. Text processing was selected for the first intelligent interface prototype because text-processing software can be developed initially as fully functional but limited with a small set of commands. The program's complexity then can be increased incrementally. The intelligent interface includes the operator's behavior and three types of instructions to the underlying application software are included in the rule base. A conventional expert-system inference engine searches the data base for antecedents to rules and sends the consequents of fired rules as commands to the underlying software. Plans for putting the expert system on top of a second application, a database management system, will be carried out following behavioral research on the first application. The intelligent interface design is suitable for use with ground-based workstations now common in government, industrial, and educational organizations.

  18. Optical Modeling Activities for NASA's James Webb Space Telescope (JWST). 4; Overview and Introduction of Matlab Based Toolkits used to Interface with Optical Design Software

    NASA Technical Reports Server (NTRS)

    Howard, Joseph

    2007-01-01

    This is part four of a series on the ongoing optical modeling activities for James Webb Space Telescope (JWST). The first two discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients. The third investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The work here introduces some of the math software tools used to perform the work of the previous three papers of this series. NASA has recently approved these in-house tools for public release as open source, so this presentation also serves as a quick tutorial on their use. The tools are collections of functions written in Matlab, which interface with optical design software (CodeV, OSLO, and Zemax) using either COM or DDE communication protocol. The functions are discussed, and examples are given.

  19. Optical Modeling Activities for NASA's James Webb Space Telescope (JWST). 4; Overview and Introduction of Matlab Based Toolkits used to Interface with Optical Design Software

    NASA Technical Reports Server (NTRS)

    Howard, Joseph

    2007-01-01

    This is part four of a series on the ongoing optical modeling activities for James Webb Space Telescope (JWST). The first two discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients. The third investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The work here introduces some of the math software tools used to perform the work of the previous three papers of this series. NASA has recently approved these in-house tools for public release as open source, so this presentation also serves as a quick tutorial on their use. The tools are collections of functions written in Matlab, which interface with optical design software (CodeV, OSLO, and Zemax) using either COM or DDE communication protocol. The functions are discussed, and examples are given.

  20. A brain computer interface-based explorer.

    PubMed

    Bai, Lijuan; Yu, Tianyou; Li, Yuanqing

    2015-04-15

    In recent years, various applications of brain computer interfaces (BCIs) have been studied. In this paper, we present a hybrid BCI combining P300 and motor imagery to operate an explorer. Our system is mainly composed of a BCI mouse, a BCI speller and an explorer. Through this system, the user can access his computer and manipulate (open, close, copy, paste, and delete) files such as documents, pictures, music, movies and so on. The system has been tested with five subjects, and the experimental results show that the explorer can be successfully operated according to subjects' intentions. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Acid-base chemistry of frustrated water at protein interfaces.

    PubMed

    Fernández, Ariel

    2016-01-01

    Water molecules at a protein interface are often frustrated in hydrogen-bonding opportunities due to subnanoscale confinement. As shown, this condition makes them behave as a general base that may titrate side-chain ammonium and guanidinium cations. Frustration-based chemistry is captured by a quantum mechanical treatment of proton transference and shown to remove same-charge uncompensated anticontacts at the interface found in the crystallographic record and in other spectroscopic information on the aqueous interface. Such observations are untenable within classical arguments, as hydronium is a stronger acid than ammonium or guanidinium. Frustration enables a directed Grotthuss mechanism for proton transference stabilizing same-charge anticontacts.

  2. Interface Superconductivity in Graphite- and CuCl-Based Heterostructures

    DTIC Science & Technology

    2015-01-22

    AFRL-OSR-VA-TR-2015-0062 Interface superconductivity in graphite- and CuCl-based heterostructures Yakov Kopelevich UNIVERSIDADE EEADUAL DE CAMPINAS...TITLE AND SUBTITLE "INTERFACE SUPERCONDUCTIVITY IN GRAPHITE AND CuCl-BASED HETEROSTRUCTURES" 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0056 5c...long-standing problem of possible high- temperature superconductivity in CuCl. The obtained experimental evidence indicates that the low resistance

  3. Bioinspired interface for nanobiodevices based on phospholipid polymer chemistry

    PubMed Central

    Ishihara, Kazuhiko; Takai, Madoka

    2009-01-01

    This review paper describes novel biointerfaces for nanobiodevices. Biocompatible and non-biofouling surfaces are designed largely based on cell membrane structure, and the preparation and functioning of the bioinspired interface are evaluated and compared between living and artificial systems. A molecular assembly of polymers with a phospholipid polar group has been developed as the platform of the interface. At the surface, protein adsorption is effectively reduced and the subsequent bioreactions are suppressed. Through this platform, biomolecules with a high affinity to the specific molecules are introduced under mild conditions. The activity of the biomolecules is retained even after immobilization. This bioinspired interface is adapted to construct bionanodevices, that is, microfluidic chips and nanoparticles for capturing target molecules and cells. The interface functions well and has a very high efficiency for biorecognition. This bioinspired interface is a promising universal platform that integrates various fields of science and has useful applications. PMID:19324688

  4. Physically based feature mapping concepts in bond interface evaluation

    NASA Astrophysics Data System (ADS)

    Jiao, D.; Rose, J.; Hodiwalla, N.

    Feature mapping in bond interface evaluation is explored to produce a number of physically based images of the interface state, drawing upon a number of different features in both time and frequency domain extracted from experimentally obtained bulk and guided wave test data. Gaussian filters are applied to the obtained RF signals, and F-maps of interface echoes are obtained to show the image variations as a function of frequency. Experiments on two specimens are conducted to inspect the bonding qualities by transverse wave oblique incidence, longitudinal wave normal incidence, as well as leaky Lamb wave techniques. Other features, such as skewness and kurtosis, can also provide information on the influence of the frequency and the interface properties of the interface layer.

  5. A new seismically constrained subduction interface model for Central America

    NASA Astrophysics Data System (ADS)

    Kyriakopoulos, C.; Newman, A. V.; Thomas, A. M.; Moore-Driskell, M.; Farmer, G. T.

    2015-08-01

    We provide a detailed, seismically defined three-dimensional model for the subducting plate interface along the Middle America Trench between northern Nicaragua and southern Costa Rica. The model uses data from a weighted catalog of about 30,000 earthquake hypocenters compiled from nine catalogs to constrain the interface through a process we term the "maximum seismicity method." The method determines the average position of the largest cluster of microseismicity beneath an a priori functional surface above the interface. This technique is applied to all seismicity above 40 km depth, the approximate intersection of the hanging wall Mohorovičić discontinuity, where seismicity likely lies along the plate interface. Below this depth, an envelope above 90% of seismicity approximates the slab surface. Because of station proximity to the interface, this model provides highest precision along the interface beneath the Nicoya Peninsula of Costa Rica, an area where marked geometric changes coincide with crustal transitions and topography observed seaward of the trench. The new interface is useful for a number of geophysical studies that aim to understand subduction zone earthquake behavior and geodynamic and tectonic development of convergent plate boundaries.

  6. A Robust Camera-Based Interface for Mobile Entertainment

    PubMed Central

    Roig-Maimó, Maria Francesca; Manresa-Yee, Cristina; Varona, Javier

    2016-01-01

    Camera-based interfaces in mobile devices are starting to be used in games and apps, but few works have evaluated them in terms of usability or user perception. Due to the changing nature of mobile contexts, this evaluation requires extensive studies to consider the full spectrum of potential users and contexts. However, previous works usually evaluate these interfaces in controlled environments such as laboratory conditions, therefore, the findings cannot be generalized to real users and real contexts. In this work, we present a robust camera-based interface for mobile entertainment. The interface detects and tracks the user’s head by processing the frames provided by the mobile device’s front camera, and its position is then used to interact with the mobile apps. First, we evaluate the interface as a pointing device to study its accuracy, and different factors to configure such as the gain or the device’s orientation, as well as the optimal target size for the interface. Second, we present an in the wild study to evaluate the usage and the user’s perception when playing a game controlled by head motion. Finally, the game is published in an application store to make it available to a large number of potential users and contexts and we register usage data. Results show the feasibility of using this robust camera-based interface for mobile entertainment in different contexts and by different people. PMID:26907288

  7. A Robust Camera-Based Interface for Mobile Entertainment.

    PubMed

    Roig-Maimó, Maria Francesca; Manresa-Yee, Cristina; Varona, Javier

    2016-02-19

    Camera-based interfaces in mobile devices are starting to be used in games and apps, but few works have evaluated them in terms of usability or user perception. Due to the changing nature of mobile contexts, this evaluation requires extensive studies to consider the full spectrum of potential users and contexts. However, previous works usually evaluate these interfaces in controlled environments such as laboratory conditions, therefore, the findings cannot be generalized to real users and real contexts. In this work, we present a robust camera-based interface for mobile entertainment. The interface detects and tracks the user's head by processing the frames provided by the mobile device's front camera, and its position is then used to interact with the mobile apps. First, we evaluate the interface as a pointing device to study its accuracy, and different factors to configure such as the gain or the device's orientation, as well as the optimal target size for the interface. Second, we present an in the wild study to evaluate the usage and the user's perception when playing a game controlled by head motion. Finally, the game is published in an application store to make it available to a large number of potential users and contexts and we register usage data. Results show the feasibility of using this robust camera-based interface for mobile entertainment in different contexts and by different people.

  8. Hydro-mechanical regimes of deforming subduction interface: modeling versus observations

    NASA Astrophysics Data System (ADS)

    Zheng, L.; Gerya, T.; May, D.

    2015-12-01

    A lot of evidence indicates that fluid flows exist in the subduction interface, including seismic observation, magnetotelluric imaging, heat flow modeling, etc. Fluid percolation should strongly modify rock deformation affected by fluid-induced weakening within the subduction interface. Hence, we study the fluid-rock interaction along the subduction interface using a visco-plastic hydro-mechanical model, in which rock deformation and fluid percolation are self-consistently coupled. Based on a series of 2D numerical experiments, we found two typical hydro-mechanical regimes of deforming subduction interface: (1) coupled and (2) decoupled. In the case of the coupled regime, the tectonic movement of the subduction interface is divided into blocks; newly generated faults are distributed uniformly , say fault band; fluid activity concentrates inside the faults. In the case of the decoupled regime, the upper layer of the subduction interface stops moving while the lower layer continues moving along with the subduction slab; a primary fault is generated at the centre of the subduction interface, or namely decoupled interface. Available observations suggests that both coupled and decoupled regimes can be observed in the nature at different scales. Systematic parameter study suggests that it is mainly the magnitude of the yield strength of subducted rocks depending on their cohesion and friction coefficient, which control the transition between the coupled and decoupled subduction interface regimes.

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

    PubMed

    Spasic, Aleksandar M; Lazarevic, Mihailo P

    2005-02-01

    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.

  10. Simulation of evaporation of a sessile drop using a diffuse interface model

    NASA Astrophysics Data System (ADS)

    Sefiane, Khellil; Ding, Hang; Sahu, Kirti; Matar, Omar

    2008-11-01

    We consider here the evaporation dynamics of a Newtonian liquid sessile drop using an improved diffuse interface model. The governing equations for the drop and surrounding vapour are both solved, and separated by the order parameter (i.e. volume fraction), based on the previous work of Ding et al. JCP 2007. The diffuse interface model has been shown to be successful in modelling the moving contact line problems (Jacqmin 2000; Ding and Spelt 2007, 2008). Here, a pinned contact line of the drop is assumed. The evaporative mass flux at the liquid-vapour interface is a function of local temperature constitutively and treated as a source term in the interface evolution equation, i.e. Cahn-Hilliard equation. The model is validated by comparing its predictions with data available in the literature. The evaporative dynamics are illustrated in terms of drop snapshots, and a quantitative comparison with the results using a free surface model are made.

  11. Computer-Based Tools for Evaluating Graphical User Interfaces

    NASA Technical Reports Server (NTRS)

    Moore, Loretta A.

    1997-01-01

    The user interface is the component of a software system that connects two very complex system: humans and computers. Each of these two systems impose certain requirements on the final product. The user is the judge of the usability and utility of the system; the computer software and hardware are the tools with which the interface is constructed. Mistakes are sometimes made in designing and developing user interfaces because the designers and developers have limited knowledge about human performance (e.g., problem solving, decision making, planning, and reasoning). Even those trained in user interface design make mistakes because they are unable to address all of the known requirements and constraints on design. Evaluation of the user inter-face is therefore a critical phase of the user interface development process. Evaluation should not be considered the final phase of design; but it should be part of an iterative design cycle with the output of evaluation being feed back into design. The goal of this research was to develop a set of computer-based tools for objectively evaluating graphical user interfaces. The research was organized into three phases. The first phase resulted in the development of an embedded evaluation tool which evaluates the usability of a graphical user interface based on a user's performance. An expert system to assist in the design and evaluation of user interfaces based upon rules and guidelines was developed during the second phase. During the final phase of the research an automatic layout tool to be used in the initial design of graphical inter- faces was developed. The research was coordinated with NASA Marshall Space Flight Center's Mission Operations Laboratory's efforts in developing onboard payload display specifications for the Space Station.

  12. Minimal model for charge transfer excitons at the dielectric interface

    NASA Astrophysics Data System (ADS)

    Ono, Shota; Ohno, Kaoru

    2016-03-01

    A theoretical description of the charge transfer (CT) exciton across the donor-acceptor interface without the use of a completely localized hole (or electron) is a challenge in the field of organic solar cells. We calculate the total wave function of the CT exciton by solving an effective two-particle Schrödinger equation for the inhomogeneous dielectric interface. We formulate the magnitude of the CT and construct a minimal model of the CT exciton under the breakdown of inversion symmetry. We demonstrate that both a light hole mass and a hole localization along the normal to the dielectric interface are crucial to yield the CT exciton.

  13. Anisotropic solid-liquid interface kinetics in silicon: an atomistically informed phase-field model

    NASA Astrophysics Data System (ADS)

    Bergmann, S.; Albe, K.; Flegel, E.; Barragan-Yani, D. A.; Wagner, B.

    2017-09-01

    We present an atomistically informed parametrization of a phase-field model for describing the anisotropic mobility of liquid-solid interfaces in silicon. The model is derived from a consistent set of atomistic data and thus allows to directly link molecular dynamics and phase field simulations. Expressions for the free energy density, the interfacial energy and the temperature and orientation dependent interface mobility are systematically fitted to data from molecular dynamics simulations based on the Stillinger-Weber interatomic potential. The temperature-dependent interface velocity follows a Vogel-Fulcher type behavior and allows to properly account for the dynamics in the undercooled melt.

  14. The Interface Between Theory and Data in Structural Equation Models

    USGS Publications Warehouse

    Grace, James B.; Bollen, Kenneth A.

    2006-01-01

    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.

  15. X window system based user interface in radiology.

    PubMed

    Heinilä, J; Yliaho, J; Ahonen, J; Viitanen, J; Kormano, M

    1994-05-01

    A teleradiology system was designed for image transfer between two hospitals. One of the main challenges of the work was the user interface, which was to be easy to operate and to learn, and was equipped with useful functions for image manipulation and diagnosing. The software tools used were the Unix operating system (HP-UX v.7.0), C programming language and the X Window System (or simply X). The graphical user interface (GUI) was based on OSF-Motif standard, and it was developed by using the HP-Interface Architect. Both OSF-Motif and HP-Interface Architect are based on X. The results of the development project were installed for clinical use in the Turku University Central Hospital. The work demonstrates, that the X Window System has useful and advantageous features for radiology department's computer network environment.

  16. Graphene-Based Interfaces Do Not Alter Target Nerve Cells.

    PubMed

    Fabbro, Alessandra; Scaini, Denis; León, Verónica; Vázquez, Ester; Cellot, Giada; Privitera, Giulia; Lombardi, Lucia; Torrisi, Felice; Tomarchio, Flavia; Bonaccorso, Francesco; Bosi, Susanna; Ferrari, Andrea C; Ballerini, Laura; Prato, Maurizio

    2016-01-26

    Neural-interfaces rely on the ability of electrodes to transduce stimuli into electrical patterns delivered to the brain. In addition to sensitivity to the stimuli, stability in the operating conditions and efficient charge transfer to neurons, the electrodes should not alter the physiological properties of the target tissue. Graphene is emerging as a promising material for neuro-interfacing applications, given its outstanding physico-chemical properties. Here, we use graphene-based substrates (GBSs) to interface neuronal growth. We test our GBSs on brain cell cultures by measuring functional and synaptic integrity of the emerging neuronal networks. We show that GBSs are permissive interfaces, even when uncoated by cell adhesion layers, retaining unaltered neuronal signaling properties, thus being suitable for carbon-based neural prosthetic devices.

  17. Electrode-electrolyte interface impedance: experiments and model.

    PubMed

    Bates, J B; Chu, Y T

    1992-01-01

    The impedance of the junction between a solid or aqueous electrolyte and a metal electrode at which no charge transfer processes occur (blocking contacts) follows closely the constant phase angle form, Z = A(j omega)-n, over a wide frequency range, where A is a constant, and the frequency exponent n is typically in the range of 0.7 to 0.95. Several models have been proposed in which the magnitude of the frequency exponent n is related by a simple expression to the fractal dimension d of the rough electrode surface. But experiments with aqueous H2SO4 and roughened platinum and silicon electrodes show that there is no simple relationship, if any at all, between n and d when d is determined from the analysis of one dimensional surface profiles. Moreover, n is not a simple function of the average roughness of the electrode. In order to gain some insight into the effect of electrode topography and the interface impedance, a model for the response of the interface to a constant voltage pulse was constructed. This model is based on the idea that, following a pulse, locally concentrated regions of ions accumulate rapidly at the tips of large protrusions on the electrode surface which screens deeper regions of the electrode from the field driven flux of mobile ions. After this rapid charging, ions are able to reach the deeper, screened regions of the electrode by diffusion, and it is this diffusive process that gives rise to the observed t1-n dependence of the charge collected. Computer simulations, similar to the diffusion limited aggregation model, using measured profiles as fixed (non-growing) clusters, gave exponents n in good agreement with experiment.

  18. Geometrical model for the energy of semicoherent interphase interfaces

    PubMed Central

    Ecob, Roger C.; Ralph, Brian

    1980-01-01

    The basis for the considerations given in this paper is the O-lattice description of crystalline interfaces of Bollmann. In the development of his approach presented here, all possible interfacial planes between two crystal phases having a defined orientation relationship are considered. The energies of these interfaces are then computed in terms of the energies of the primary intrinsic dislocations. A number of modeling interactions are incorporated into this approach, and a better agreement with experimental data is thus obtained. PMID:16592796

  19. Learning Machine, Vietnamese Based Human-Computer Interface.

    ERIC Educational Resources Information Center

    Northwest Regional Educational Lab., Portland, OR.

    The sixth session of IT@EDU98 consisted of seven papers on the topic of the learning machine--Vietnamese based human-computer interface, and was chaired by Phan Viet Hoang (Informatics College, Singapore). "Knowledge Based Approach for English Vietnamese Machine Translation" (Hoang Kiem, Dinh Dien) presents the knowledge base approach,…

  20. SN_GUI: a graphical user interface for snowpack modeling

    NASA Astrophysics Data System (ADS)

    Spreitzhofer, G.; Fierz, C.; Lehning, M.

    2004-10-01

    SNOWPACK is a physical snow cover model. The model not only serves as a valuable research tool, but also runs operationally on a network of high Alpine automatic weather and snow measurement sites. In order to facilitate the operation of SNOWPACK and the interpretation of the results obtained by this model, a user-friendly graphical user interface for snowpack modeling, named SN_GUI, was created. This Java-based and thus platform-independent tool can be operated in two modes, one designed to fulfill the requirements of avalanche warning services (e.g. by providing information about critical layers within the snowpack that are closely related to the avalanche activity), and the other one offering a variety of additional options satisfying the needs of researchers. The user of SN_GUI is graphically guided through the entire process of creating snow cover simulations. The starting point is the efficient creation of input parameter files for SNOWPACK, followed by the launching of SNOWPACK with a variety of parameter settings. Finally, after the successful termination of the run, a number of interactive display options may be used to visualize the model output. Among these are vertical profiles and time profiles for many parameters. Besides other features, SN_GUI allows the use of various color, time and coordinate scales, and the comparison of measured and observed parameters.

  1. Radiation budget measurement/model interface research

    SciTech Connect

    Vonderhaar, T.H.

    1981-10-01

    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.

  2. Monitoring of intratidal lung mechanics: a Graphical User Interface for a model-based decision support system for PEEP-titration in mechanical ventilation.

    PubMed

    Buehler, S; Lozano-Zahonero, S; Schumann, S; Guttmann, J

    2014-12-01

    In mechanical ventilation, a careful setting of the ventilation parameters in accordance with the current individual state of the lung is crucial to minimize ventilator induced lung injury. Positive end-expiratory pressure (PEEP) has to be set to prevent collapse of the alveoli, however at the same time overdistension should be avoided. Classic approaches of analyzing static respiratory system mechanics fail in particular if lung injury already prevails. A new approach of analyzing dynamic respiratory system mechanics to set PEEP uses the intratidal, volume-dependent compliance which is believed to stay relatively constant during one breath only if neither atelectasis nor overdistension occurs. To test the success of this dynamic approach systematically at bedside or in an animal study, automation of the computing steps is necessary. A decision support system for optimizing PEEP in form of a Graphical User Interface (GUI) was targeted. Respiratory system mechanics were analyzed using the gliding SLICE method. The resulting shapes of the intratidal compliance-volume curve were classified into one of six categories, each associated with a PEEP-suggestion. The GUI should include a graphical representation of the results as well as a quality check to judge the reliability of the suggestion. The implementation of a user-friendly GUI was successfully realized. The agreement between modelled and measured pressure data [expressed as root-mean-square (RMS)] tested during the implementation phase with real respiratory data from two patient studies was below 0.2 mbar for data taken in volume controlled mode and below 0.4 mbar for data taken in pressure controlled mode except for two cases with RMS < 0.6 mbar. Visual inspections showed, that good and medium quality data could be reliably identified. The new GUI allows visualization of intratidal compliance-volume curves on a breath-by-breath basis. The automatic categorisation of curve shape into one of six shape

  3. A Universal Intelligent System-on-Chip Based Sensor Interface

    PubMed Central

    Mattoli, Virgilio; Mondini, Alessio; Mazzolai, Barbara; Ferri, Gabriele; Dario, Paolo

    2010-01-01

    The need for real-time/reliable/low-maintenance distributed monitoring systems, e.g., wireless sensor networks, has been becoming more and more evident in many applications in the environmental, agro-alimentary, medical, and industrial fields. The growing interest in technologies related to sensors is an important indicator of these new needs. The design and the realization of complex and/or distributed monitoring systems is often difficult due to the multitude of different electronic interfaces presented by the sensors available on the market. To address these issues the authors propose the concept of a Universal Intelligent Sensor Interface (UISI), a new low-cost system based on a single commercial chip able to convert a generic transducer into an intelligent sensor with multiple standardized interfaces. The device presented offers a flexible analog and/or digital front-end, able to interface different transducer typologies (such as conditioned, unconditioned, resistive, current output, capacitive and digital transducers). The device also provides enhanced processing and storage capabilities, as well as a configurable multi-standard output interface (including plug-and-play interface based on IEEE 1451.3). In this work the general concept of UISI and the design of reconfigurable hardware are presented, together with experimental test results validating the proposed device. PMID:22163624

  4. A distributed data component for the open modeling interface

    USDA-ARS?s Scientific Manuscript database

    As the volume of collected data continues to increase in the environmental sciences, so does the need for effective means for accessing those data. We have developed an Open Modeling Interface (OpenMI) data component that retrieves input data for model components from environmental information syste...

  5. Integration of finite element modeling with solid modeling through a dynamic interface

    NASA Technical Reports Server (NTRS)

    Shephard, Mark S.

    1987-01-01

    Finite element modeling is dominated by geometric modeling type operations. Therefore, an effective interface to geometric modeling requires access to both the model and the modeling functionality used to create it. The use of a dynamic interface that addresses these needs through the use of boundary data structures and geometric operators is discussed.

  6. Streamflow forecasting using the modular modeling system and an object-user interface

    USGS Publications Warehouse

    Jeton, A.E.

    2001-01-01

    The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation (BOR), developed a computer program to provide a general framework needed to couple disparate environmental resource models and to manage the necessary data. The Object-User Interface (OUI) is a map-based interface for models and modeling data. It provides a common interface to run hydrologic models and acquire, browse, organize, and select spatial and temporal data. One application is to assist river managers in utilizing streamflow forecasts generated with the Precipitation-Runoff Modeling System running in the Modular Modeling System (MMS), a distributed-parameter watershed model, and the National Weather Service Extended Streamflow Prediction (ESP) methodology.

  7. Interface tension and interface entropy in the 2+1 flavor Nambu-Jona-Lasinio model

    NASA Astrophysics Data System (ADS)

    Ke, Wei-yao; Liu, Yu-xin

    2014-04-01

    We study the QCD phases and their transitions in the 2+1 flavor Nambu-Jona-Lasinio model, with a focus on the interface effects such as the interface tension, the interface entropy, and the critical bubble size in the coexistence region of the first-order phase transitions. Our results show that under the thin-wall approximation, the interface contribution to the total entropy density changes its discontinuity scale in the first-order phase transition. However, the entropy density of the dynamical chiral symmetry (DCS) phase is always greater than that of the dynamical chiral symmetry broken (DCSB) phase in both the heating and hadronization processes. To address this entropy puzzle, the thin-wall approximation is evaluated in the present work. We find that the puzzle can be attributed to an overestimate of the critical bubble size at low temperature in the hadronization process. With an improvement on the thin-wall approximation, the entropy puzzle is well solved with the total entropy density of the hadron-DCSB phase exceeding apparently that of the DCS-quark phase at low temperature.

  8. Interfaces in the XY Model and Conformal Invariance

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    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.

  9. Finite driving rates in interface models of Barkhausen noise.

    PubMed

    de Queiroz, S L; Bahiana, M

    2001-12-01

    We consider a single-interface model for the description of Barkhausen noise in soft ferromagnetic materials. Previously, the model was used only in the adiabatic regime of infinitely slow field ramping. We introduce finite driving rates and analyze the scaling of event sizes and durations for different regimes of the driving rate. Coexistence of intermittency, with nontrivial scaling laws, and finite-velocity interface motion is observed for high enough driving rates. Power spectra show a decay approximately omega(-t), with t<2 for finite driving rates, revealing the influence of the internal structure of avalanches.

  10. Modelling biological invasions: Individual to population scales at interfaces.

    PubMed

    Belmonte-Beitia, J; Woolley, T E; Scott, J G; Maini, P K; Gaffney, E A

    2013-10-07

    Extracting the population level behaviour of biological systems from that of the individual is critical in understanding dynamics across multiple scales and thus has been the subject of numerous investigations. Here, the influence of spatial heterogeneity in such contexts is explored for interfaces with a separation of the length scales characterising the individual and the interface, a situation that can arise in applications involving cellular modelling. As an illustrative example, we consider cell movement between white and grey matter in the brain which may be relevant in considering the invasive dynamics of glioma. We show that while one can safely neglect intrinsic noise, at least when considering glioma cell invasion, profound differences in population behaviours emerge in the presence of interfaces with only subtle alterations in the dynamics at the individual level. Transport driven by local cell sensing generates predictions of cell accumulations along interfaces where cell motility changes. This behaviour is not predicted with the commonly used Fickian diffusion transport model, but can be extracted from preliminary observations of specific cell lines in recent, novel, cryo-imaging. Consequently, these findings suggest a need to consider the impact of individual behaviour, spatial heterogeneity and especially interfaces in experimental and modelling frameworks of cellular dynamics, for instance in the characterisation of glioma cell motility. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Molecular Modeling of Water Interfaces: From Molecular Spectroscopy to Thermodynamics.

    PubMed

    Nagata, Yuki; Ohto, Tatsuhiko; Backus, Ellen H G; Bonn, Mischa

    2016-04-28

    Understanding aqueous interfaces at the molecular level is not only fundamentally important, but also highly relevant for a variety of disciplines. For instance, electrode-water interfaces are relevant for electrochemistry, as are mineral-water interfaces for geochemistry and air-water interfaces for environmental chemistry; water-lipid interfaces constitute the boundaries of the cell membrane, and are thus relevant for biochemistry. One of the major challenges in these fields is to link macroscopic properties such as interfacial reactivity, solubility, and permeability as well as macroscopic thermodynamic and spectroscopic observables to the structure, structural changes, and dynamics of molecules at these interfaces. Simulations, by themselves, or in conjunction with appropriate experiments, can provide such molecular-level insights into aqueous interfaces. In this contribution, we review the current state-of-the-art of three levels of molecular dynamics (MD) simulation: ab initio, force field, and coarse-grained. We discuss the advantages, the potential, and the limitations of each approach for studying aqueous interfaces, by assessing computations of the sum-frequency generation spectra and surface tension. The comparison of experimental and simulation data provides information on the challenges of future MD simulations, such as improving the force field models and the van der Waals corrections in ab initio MD simulations. Once good agreement between experimental observables and simulation can be established, the simulation can be used to provide insights into the processes at a level of detail that is generally inaccessible to experiments. As an example we discuss the mechanism of the evaporation of water. We finish by presenting an outlook outlining four future challenges for molecular dynamics simulations of aqueous interfacial systems.

  12. ITER plasma safety interface models and assessments

    SciTech Connect

    Uckan, N.A.; Bartels, H-W.; Honda, T.; Putvinski, S.; Amano, T.; Boucher, D.; Post, D.; Wesley, J.

    1996-12-31

    Physics models and requirements to be used as a basis for safety analysis studies are developed and physics results motivated by safety considerations are presented for the ITER design. Physics specifications are provided for enveloping plasma dynamic events for Category I (operational event), Category II (likely event), and Category III (unlikely event). A safety analysis code SAFALY has been developed to investigate plasma anomaly events. The plasma response to ex-vessel component failure and machine response to plasma transients are considered.

  13. NASA: Model development for human factors interfacing

    NASA Technical Reports Server (NTRS)

    Smith, L. L.

    1984-01-01

    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.

  14. Critical interfaces and duality in the Ashkin-Teller model

    SciTech Connect

    Picco, Marco; Santachiara, Raoul

    2011-06-15

    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.

  15. Kinetic model of membrane extraction with a sorbent interface.

    PubMed

    Yang, M J; Adams, M; Pawliszyn, J

    1996-09-01

    Membrane extraction with a sorbent interface (MESI) is an unique sample preparation alternative for trace organic analysis. The main features of MESI include its solvent-free nature, the rugged and simple design with no moving parts for long-term reliable performance, the fact that it is a single-step process which ensures good precision, its easy automation, and its feasibility for on-site operation. Among the available membrane extraction modules designed for the MESI system, the headspace configuration has continued to show its superior durability and versatility in membrane applications. The headspace membrane extraction configuration effectively eliminates the need for a sampling pump and flow metering and hence prevents the extraction system from plugging and greatly simplifies the extraction process. The module can be used for extraction of VOCs from gaseous, aqueous, or solid samples. A mathematical model has been developed for headspace membrane extraction of an aqueous sample, based on the assumption that the aqueous phase is perfectly stirred. The model is in good agreement with the experimental benzene extraction results obtained with an efficient agitation method such as high-speed magnetic stirring or sonication. The model has also been used to study the effects of various extraction parameters with respect to the sensitivity and response time of the MESI system. Sample agitation facilities analyte mass transport and hence improves both the system sensitivity and the response time. The sensitivity of the extraction method also increases with an increase of the extraction temperature.

  16. New Finite Difference Methods Based on IIM for Inextensible Interfaces in Incompressible Flows.

    PubMed

    Li, Zhilin; Lai, Ming-Chih

    2011-01-01

    In this paper, new finite difference methods based on the augmented immersed interface method (IIM) are proposed for simulating an inextensible moving interface in an incompressible two-dimensional flow. The mathematical models arise from studying the deformation of red blood cells in mathematical biology. The governing equations are incompressible Stokes or Navier-Stokes equations with an unknown surface tension, which should be determined in such a way that the surface divergence of the velocity is zero along the interface. Thus, the area enclosed by the interface and the total length of the interface should be conserved during the evolution process. Because of the nonlinear and coupling nature of the problem, direct discretization by applying the immersed boundary or immersed interface method yields complex nonlinear systems to be solved. In our new methods, we treat the unknown surface tension as an augmented variable so that the augmented IIM can be applied. Since finding the unknown surface tension is essentially an inverse problem that is sensitive to perturbations, our regularization strategy is to introduce a controlled tangential force along the interface, which leads to a least squares problem. For Stokes equations, the forward solver at one time level involves solving three Poisson equations with an interface. For Navier-Stokes equations, we propose a modified projection method that can enforce the pressure jump condition corresponding directly to the unknown surface tension. Several numerical experiments show good agreement with other results in the literature and reveal some interesting phenomena.

  17. New Finite Difference Methods Based on IIM for Inextensible Interfaces in Incompressible Flows

    PubMed Central

    Li, Zhilin; Lai, Ming-Chih

    2012-01-01

    In this paper, new finite difference methods based on the augmented immersed interface method (IIM) are proposed for simulating an inextensible moving interface in an incompressible two-dimensional flow. The mathematical models arise from studying the deformation of red blood cells in mathematical biology. The governing equations are incompressible Stokes or Navier-Stokes equations with an unknown surface tension, which should be determined in such a way that the surface divergence of the velocity is zero along the interface. Thus, the area enclosed by the interface and the total length of the interface should be conserved during the evolution process. Because of the nonlinear and coupling nature of the problem, direct discretization by applying the immersed boundary or immersed interface method yields complex nonlinear systems to be solved. In our new methods, we treat the unknown surface tension as an augmented variable so that the augmented IIM can be applied. Since finding the unknown surface tension is essentially an inverse problem that is sensitive to perturbations, our regularization strategy is to introduce a controlled tangential force along the interface, which leads to a least squares problem. For Stokes equations, the forward solver at one time level involves solving three Poisson equations with an interface. For Navier-Stokes equations, we propose a modified projection method that can enforce the pressure jump condition corresponding directly to the unknown surface tension. Several numerical experiments show good agreement with other results in the literature and reveal some interesting phenomena. PMID:23795308

  18. A hybrid brain-computer interface-based mail client.

    PubMed

    Yu, Tianyou; Li, Yuanqing; Long, Jinyi; Li, Feng

    2013-01-01

    Brain-computer interface-based communication plays an important role in brain-computer interface (BCI) applications; electronic mail is one of the most common communication tools. In this study, we propose a hybrid BCI-based mail client that implements electronic mail communication by means of real-time classification of multimodal features extracted from scalp electroencephalography (EEG). With this BCI mail client, users can receive, read, write, and attach files to their mail. Using a BCI mouse that utilizes hybrid brain signals, that is, motor imagery and P300 potential, the user can select and activate the function keys and links on the mail client graphical user interface (GUI). An adaptive P300 speller is employed for text input. The system has been tested with 6 subjects, and the experimental results validate the efficacy of the proposed method.

  19. A Hybrid Brain-Computer Interface-Based Mail Client

    PubMed Central

    Yu, Tianyou; Li, Yuanqing; Long, Jinyi; Li, Feng

    2013-01-01

    Brain-computer interface-based communication plays an important role in brain-computer interface (BCI) applications; electronic mail is one of the most common communication tools. In this study, we propose a hybrid BCI-based mail client that implements electronic mail communication by means of real-time classification of multimodal features extracted from scalp electroencephalography (EEG). With this BCI mail client, users can receive, read, write, and attach files to their mail. Using a BCI mouse that utilizes hybrid brain signals, that is, motor imagery and P300 potential, the user can select and activate the function keys and links on the mail client graphical user interface (GUI). An adaptive P300 speller is employed for text input. The system has been tested with 6 subjects, and the experimental results validate the efficacy of the proposed method. PMID:23690880

  20. SIF-based fracture criterion for interface cracks

    NASA Astrophysics Data System (ADS)

    Ji, Xing

    2016-06-01

    The complex stress intensity factor K governing the stress field of an interface crack tip may be split into two parts, i.e., hat{K} and s^{-iɛ}, so that K=hat{K}s^{-iɛ}, s is a characteristic length and ɛ is the oscillatory index. hat{K} has the same dimension as the classical stress intensity factor and characterizes the interface crack tip field. That means a criterion for interface cracks may be formulated directly with hat{K}, as Irwin (ASME J. Appl. Mech. 24:361-364, 1957) did in 1957 for the classical fracture mechanics. Then, for an interface crack, it is demonstrated that the quasi Mode I and Mode II tip fields can be defined and distinguished from the coupled mode tip fields. Built upon SIF-based fracture criteria for quasi Mode I and Mode II, the stress intensity factor (SIF)-based fracture criterion for mixed mode interface cracks is proposed and validated against existing experimental results.

  1. Effect of model design, cushion construction, and interface pressure mats on interface pressure and immersion.

    PubMed

    Pipkin, Leigh; Sprigle, Stephen

    2008-01-01

    Measuring interface pressure (IP) is one way to characterize cushion performance in the clinic and laboratory. This study explored how the presence of four commercially available IP mats affected IP on and immersion of two buttocks models. We loaded seven cushions with each buttocks model and captured pressure data using FSA sensors (Vista Medical Ltd; Winnipeg, Manitoba, Canada). Analysis was performed to compare pressure magnitude and immersion. Overall, both pressure magnitude and immersion changed after mat introduction. A significant interaction existed between cushion and mat condition and cushion and model for all variables. Introducing an IP mat to the model-cushion interface alters the loading on the cushion. The mats bridged the contours of the model, causing a change in IP at the locations studied. Although immersion was statistically different between mat conditions, the magnitude of the difference was less than 1 mm once we accounted for the thickness of the mats. The significance of the cushion-mat interaction indicates that the mat effect differed across cushion design. Clinical and research users of pressure mats should consider the effect of mat presence, the effect of model design, and mat and buttocks interactions with cushions for successful use.

  2. Using ADDIE To Design a Web-Based Training Interface.

    ERIC Educational Resources Information Center

    Lohr, Linda

    Modeling the functions of a teacher in a computer interface is not a new practice; most computer applications employ electronic performance support systems (EPSS) such as online help, wizards, coaches, and even some forms of artificial intelligence. This paper presents easy-to-implement strategies for increasing learner autonomy by embedding…

  3. Interface fracture and composite deformation of model laminates

    NASA Astrophysics Data System (ADS)

    Fox, Matthew R.

    Model laminates were studied to improve the understanding of composite mechanical behavior. NiAl/Mo and NiAl/Cr model laminates, with a series of interfaces, were bonded at 1100°C. Reaction layers were present in all laminates, varying in thickness with bonding conditions. Interface fracture strengths and resistances were determined under primarily mode II loading conditions using a novel technique, the asymmetrically-loaded shear (ALS) test, in which one layer of the laminate was loaded in compression, producing a stable interface crack. The NiAl/Mo interface was also fractured in four-point bending. A small amount of plasticity was found to play a role in crack initiation. During steady-state mode II interface fracture of NiAl/Mo model laminates, large-scale slip was observed near the crack tip in the NiAl adjacent to the interface. After testing, the local slope and curvature of the interface were characterized at intervals along the interface and at slip locations to qualitatively describe local stresses present at and just ahead of the crack tip. The greatest percentage of slip occurred where closing forces on the crack tip were below the maximum value and were decreasing with crack growth. A mechanism for crack propagation is presented describing the role of large-scale slip in crack propagation. The mechanical response of structural laminates in 3-D stress states, as would be present in a polycrystalline aggregate composed of lamellar grains, are lacking. In order to understand the response of laminates composed of hard and soft phases, Pb/Zn laminates were prepared and tested in compression with varying lamellar orientation relative to the loading axis. A model describing the mechanical response in a general state assuming elastic-perfectly plastic isotropic layers was developed. For the 90° laminate, a different approach was applied, using the friction hill concepts used in forging analyses. With increasing ratios of cross-sectional radius to layer

  4. Microfluidic neurotransmiter-based neural interfaces for retinal prosthesis.

    PubMed

    Iezzi, Raymond; Finlayson, Paul; Xu, Yong; Katragadda, Rakesh

    2009-01-01

    Natural inter-neuronal communication is mediated primarily via neurotransmitter-gated ion channels. While most of the methods for neural interfacing have been based upon electrical stimulation, neurotransmitter-based approaches for the spatially and temporally controlled delivery of neurotransmitters are relatively new. Methods of neurotransmitter stimulation retinal prosthesis may provide new ways to control neural excitation. Experimental results for retinal ganglion cell stimulation demonstrate the feasibility of a neurotransmitter-based retinal prosthesis.

  5. Guide to the Stand-Damage Model interface management system

    Treesearch

    George Racin; J. J. Colbert

    1995-01-01

    This programmer's support document describes the Gypsy Moth Stand-Damage Model interface management system. Management of stand-damage data made it necessary to define structures to store data and provide the mechanisms to manipulate these data. The software provides a user-friendly means to manipulate files, graph and manage outputs, and edit input data. The...

  6. Designers' models of the human-computer interface

    NASA Technical Reports Server (NTRS)

    Gillan, Douglas J.; Breedin, Sarah D.

    1993-01-01

    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.

  7. Critical Interfaces in the Random-Bond Potts Model

    NASA Astrophysics Data System (ADS)

    Jacobsen, Jesper L.; Le Doussal, Pierre; Picco, Marco; Santachiara, Raoul; Wiese, Kay Jörg

    2009-02-01

    We study geometrical properties of interfaces in the random-temperature q-states Potts model as an example of a conformal field theory weakly perturbed by quenched disorder. Using conformal perturbation theory in q-2 we compute the fractal dimension of Fortuin-Kasteleyn (FK) domain walls. We also compute it numerically both via the Wolff cluster algorithm for q=3 and via transfer-matrix evaluations. We also obtain numerical results for the fractal dimension of spin clusters interfaces for q=3. These are found numerically consistent with the duality κspinκFK=16 as expressed in putative SLE parameters.

  8. Critical interfaces in the random-bond Potts model.

    PubMed

    Jacobsen, Jesper L; Le Doussal, Pierre; Picco, Marco; Santachiara, Raoul; Wiese, Kay Jörg

    2009-02-20

    We study geometrical properties of interfaces in the random-temperature q-states Potts model as an example of a conformal field theory weakly perturbed by quenched disorder. Using conformal perturbation theory in q-2 we compute the fractal dimension of Fortuin-Kasteleyn (FK) domain walls. We also compute it numerically both via the Wolff cluster algorithm for q=3 and via transfer-matrix evaluations. We also obtain numerical results for the fractal dimension of spin clusters interfaces for q=3. These are found numerically consistent with the duality kappaspinkappaFK=16 as expressed in putative SLE parameters.

  9. Damage evolution of bi-body model composed of weakly cemented soft rock and coal considering different interface effect.

    PubMed

    Zhao, Zenghui; Lv, Xianzhou; Wang, Weiming; Tan, Yunliang

    2016-01-01

    Considering the structure effect of tunnel stability in western mining of China, three typical kinds of numerical model were respectively built as follows based on the strain softening constitutive model and linear elastic-perfectly plastic model for soft rock and interface: R-M, R-C(s)-M and R-C(w)-M. Calculation results revealed that the stress-strain relation and failure characteristics of the three models vary between each other. The combination model without interface or with a strong interface presented continuous failure, while weak interface exhibited 'cut off' effect. Thus, conceptual models of bi-material model and bi-body model were established. Then numerical experiments of tri-axial compression were carried out for the two models. The relationships between stress evolution, failure zone and deformation rate fluctuations as well as the displacement of interface were detailed analyzed. Results show that two breakaway points of deformation rate actually demonstrate the starting and penetration of the main rupture, respectively. It is distinguishable due to the large fluctuation. The bi-material model shows general continuous failure while bi-body model shows 'V' type shear zone in weak body and failure in strong body near the interface due to the interface effect. With the increasing of confining pressure, the 'cut off' effect of weak interface is not obvious. These conclusions lay the theoretical foundation for further development of constitutive model for soft rock-coal combination body.

  10. Emulating conventional operator interfaces on window based workstations

    SciTech Connect

    Carr, G.P.

    1989-01-01

    This paper explores an approach to initially support the LAMPF and PSR control system on VAX/VMS workstations using DECwindows and VI Corporation DataViews as the operator interface. The PSR control system was recently turned over to MP division and the two control system staffs were merged into one group. One of the goals of this new group is to develop a common work station based operator console and interface which can be used in a single control room controlling both the LINAC and Proton Storage Ring. The new console operator interface will need a high level graphics toolkit for its implementation. During the conversion to the new consoles it will also probably be necessary to write a package to emulate the current operator interfaces at the software level. This paper describes a project to evaluate the appropriateness of VI Corporation's DataViews graphics package for use in the LAMPF control system environment by using it to write an emulation of the LAMPF touch panel interface to a large LAMPF control system application program. A secondary objective of this project was to explore any productivity increases that might be realized by using an object oriented graphics package and graphics editor. 2 refs., 6 figs.

  11. Emulating conventional operator interfaces on window-based workstations

    NASA Astrophysics Data System (ADS)

    Carr, Gary P.

    1990-08-01

    This paper explores an approach to support the LAMPF and PSR control systems on VAX/VMS workstations using DECwindows and VI Corporation DataViews as the operator interface. The PSR control system was recently turned over to MP division and the two control-system staffs were merged into one group. One of the goals of this new group is to develop a common workstation-based operator console and interface which can be used in a single control room controlling both the linac and proton storage ring. The new console operator interface will need a high-level graphics toolkit for its implementation. During the conversion to the new consoles it will also probably be necessary to write a package to emulate the current operator interfaces at the software level. This paper describes a project to evaluate the appropriateness of VI Corporation's DataViews graphics package for use in the LAMPF control-system environment by using it to write an emulation of the LAMPF touch-panel interface to a large LAMPF control-system application program. A secondary objective of this project was to explore any productivity increases that might be realized by using an object-oriented graphics package and graphics editor.

  12. Spud and FLML: generalising and automating the user interfaces of scientific computer models

    NASA Astrophysics Data System (ADS)

    Ham, D. A.; Farrell, P. E.; Maddison, J. R.; Gorman, G. J.; Wilson, C. R.; Kramer, S. C.; Shipton, J.; Collins, G. S.; Cotter, C. J.; Piggott, M. D.

    2009-04-01

    The interfaces by which users specify the scenarios to be simulated by scientific computer models are frequently primitive, under-documented and ad-hoc text files which make using the model in question difficult and error-prone and significantly increase the development cost of the model. We present a model-independent system, Spud[1], which formalises the specification of model input formats in terms of formal grammars. This is combined with an automatically generated graphical user interface which guides users to create valid model inputs based on the grammar provided, and a generic options reading module which minimises the development cost of adding model options. We further present FLML, the Fluidity Markup Language. FLML applies Spud to the Imperial College Ocean Model (ICOM) resulting in a graphically driven system which radically improves the usability of ICOM. As well as a step forward for ICOM, FLML illustrates how the Spud system can be applied to an existing complex ocean model highlighting the potential of Spud as a user interface for other codes in the ocean modelling community. [1] Ham, D. A. et.al, Spud 1.0: generalising and automating the user interfaces of scientific computer models, Geosci. Model Dev. Discuss., 1, 125-146, 2008.

  13. An interface capturing scheme for modeling atomization in compressible flows

    NASA Astrophysics Data System (ADS)

    Garrick, Daniel P.; Hagen, Wyatt A.; Regele, Jonathan D.

    2017-09-01

    The study of atomization in supersonic flow is critical to ensuring reliable ignition of scramjet combustors under startup conditions. Numerical methods incorporating surface tension effects have largely focused on the incompressible regime as most atomization applications occur at low Mach numbers. Simulating surface tension effects in compressible flow requires robust numerical methods that can handle discontinuities caused by both shocks and material interfaces with high density ratios. In this work, a shock and interface capturing scheme is developed that uses the Harten-Lax-van Leer-Contact (HLLC) Riemann solver while a Tangent of Hyperbola for INterface Capturing (THINC) interface reconstruction scheme retains the fluid immiscibility condition in the volume fraction and phasic densities in the context of the five equation model. The approach includes the effects of compressibility, surface tension, and molecular viscosity. One and two-dimensional benchmark problems demonstrate the desirable interface sharpening and conservation properties of the approach. Simulations of secondary atomization of a cylindrical water column after its interaction with a shockwave show good qualitative agreement with experimentally observed behavior. Three-dimensional examples of primary atomization of a liquid jet in a Mach 2 crossflow demonstrate the robustness of the method.

  14. Influence of atmospheric stability on model wind turbine wake interface

    NASA Astrophysics Data System (ADS)

    Taylor, Amelia; Gomez, Virgilio; Novoa, Santiago; Pol, Suhas; Westergaard, Carsten; Castillo, Luciano

    2014-11-01

    Differences in wind turbine wake deficit recovery for various atmospheric stability conditions (stratification) have been attributed to turbulence intensity levels at different conditions. It is shown that buoyancy differences at the wind turbine wake interface should be considered in addition to varying turbulence intensity to describe the net momentum transport across the wake interface. Mixing, induced by tip and hub vortices or wake swirl, induces these buoyancy differences. The above hypothesis was tested using field measurements of the wake interface for a 1.17 m model turbine installed at 6.25 m hub height. Atmospheric conditions were characterized using a 10 m meteorological tower upstream of the turbine, while a vertical rake of sonic anemometers clustered around the hub height on a downstream tower measured the wake. Data was collected over the course of seven months, during varying stability conditions, and with five different turbine configurations - including a single turbine at three different positions, two turbines in a column, and three turbines in a column. Presented are results showing the behavior of the wake (particularly the wake interface), for unstable, stable, and neutral conditions. We observed that the swirl in the wake causes mixing of the inflow, leading to a constant density profile in the far wake that causes density jumps at the wake interfaces for stratified inflow.

  15. Interface-tracking electro-hydrodynamic model for droplet coalescence

    NASA Astrophysics Data System (ADS)

    Crowl Erickson, Lindsay; Noble, David

    2012-11-01

    Many fluid-based technologies rely on electrical fields to control the motion of droplets, e.g. micro-fluidic 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. Analytic hydrodynamic approximations for interfaces become invalid near coalescence, and therefore detailed numerical simulations are necessary. We present a conformal decomposition finite element (CDFEM) interface-tracking method for 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. The electro-hydrodynamic equations solved allow for convection of charge and charge accumulation at the interface, both of which may be important factors for the pinch-off dynamics in this parameter regime.

  16. Modeling of the water network at protein-RNA interfaces.

    PubMed

    Li, Yiyu; Sutch, Brian T; Bui, Huynh-Hoa; Gallaher, Timothy K; Haworth, Ian S

    2011-06-27

    Water plays an important role in the mediation of biomolecular interactions. Thus, accurate prediction and evaluation of water-mediated interactions is an important element in the computational design of interfaces involving proteins, RNA, and DNA. Here, we use an algorithm (WATGEN) to predict the locations of interfacial water molecules for a data set of 224 protein-RNA interfaces. The accuracy of the prediction is validated against water molecules present in the X-ray structures of 105 of these complexes. The complexity of the water networks is deconvoluted through definition of the characteristics of each water molecule based on its bridging properties between the protein and RNA and on its depth in the interface with respect to the bulk solvent. This approach has the potential for scoring the water network for incorporation into the computational design of protein-RNA complexes.

  17. Computer modelling of nanoscale diffusion phenomena at epitaxial interfaces

    NASA Astrophysics Data System (ADS)

    Michailov, M.; Ranguelov, B.

    2014-05-01

    The present study outlines an important area in the application of computer modelling to interface phenomena. Being relevant to the fundamental physical problem of competing atomic interactions in systems with reduced dimensionality, these phenomena attract special academic attention. On the other hand, from a technological point of view, detailed knowledge of the fine atomic structure of surfaces and interfaces correlates with a large number of practical problems in materials science. Typical examples are formation of nanoscale surface patterns, two-dimensional superlattices, atomic intermixing at an epitaxial interface, atomic transport phenomena, structure and stability of quantum wires on surfaces. We discuss here a variety of diffusion mechanisms that control surface-confined atomic exchange, formation of alloyed atomic stripes and islands, relaxation of pure and alloyed atomic terraces, diffusion of clusters and their stability in an external field. The computational model refines important details of diffusion of adatoms and clusters accounting for the energy barriers at specific atomic sites: smooth domains, terraces, steps and kinks. The diffusion kinetics, integrity and decomposition of atomic islands in an external field are considered in detail and assigned to specific energy regions depending on the cluster stability in mass transport processes. The presented ensemble of diffusion scenarios opens a way for nanoscale surface design towards regular atomic interface patterns with exotic physical features.

  18. Phase transformations at interfaces: Observations from atomistic modeling

    SciTech Connect

    Frolov, T.; Asta, M.; Mishin, Y.

    2016-10-01

    Here, we review the recent progress in theoretical understanding and atomistic computer simulations of phase transformations in materials interfaces, focusing on grain boundaries (GBs) in metallic systems. Recently developed simulation approaches enable the search and structural characterization of GB phases in single-component metals and binary alloys, calculation of thermodynamic properties of individual GB phases, and modeling of the effect of the GB phase transformations on GB kinetics. Atomistic simulations demonstrate that the GB transformations can be induced by varying the temperature, loading the GB with point defects, or varying the amount of solute segregation. The atomic-level understanding obtained from such simulations can provide input for further development of thermodynamics theories and continuous models of interface phase transformations while simultaneously serving as a testing ground for validation of theories and models. They can also help interpret and guide experimental work in this field.

  19. Phase transformations at interfaces: Observations from atomistic modeling

    DOE PAGES

    Frolov, T.; Asta, M.; Mishin, Y.

    2016-10-01

    Here, we review the recent progress in theoretical understanding and atomistic computer simulations of phase transformations in materials interfaces, focusing on grain boundaries (GBs) in metallic systems. Recently developed simulation approaches enable the search and structural characterization of GB phases in single-component metals and binary alloys, calculation of thermodynamic properties of individual GB phases, and modeling of the effect of the GB phase transformations on GB kinetics. Atomistic simulations demonstrate that the GB transformations can be induced by varying the temperature, loading the GB with point defects, or varying the amount of solute segregation. The atomic-level understanding obtained from suchmore » simulations can provide input for further development of thermodynamics theories and continuous models of interface phase transformations while simultaneously serving as a testing ground for validation of theories and models. They can also help interpret and guide experimental work in this field.« less

  20. Universality in Sandpiles, Interface Depinning, and Earthquake Models

    SciTech Connect

    Paczuski, M.; Boettcher, S. |

    1996-07-01

    Recent numerical results for a model describing dispersive transport in ricepiles are explained by mapping the model to the depinning transition of an elastic interface that is dragged at one end through a random medium. The average velocity of transport vanishes with system size {ital L} as {l_angle}{ital v}{r_angle}{approximately}{ital L}{sup 2{minus}{ital D}}{approximately}{ital L}{sup {minus}0.23}, and the avalanche size distribution exponent {tau}=2{minus}1/{ital D}{approx_equal}1.55, where {ital D}{approx_equal}2.23 from interface depinning. We conjecture that the purely deterministic Burridge-Knopoff {open_quote}{open_quote}train{close_quote}{close_quote} model for earthquakes is in the same universality class. {copyright} {ital 1996 The American Physical Society.}

  1. Analysis and Management of Large-Scale Activities Based on Interface

    NASA Astrophysics Data System (ADS)

    Yang, Shaofan; Ji, Jingwei; Lu, Ligang; Wang, Zhiyi

    Based on the concepts of system safety engineering, life-cycle and interface that comes from American system safety standard MIL-STD-882E, and apply them to the process of risk analysis and management of large-scale activities. Identify the involved personnel, departments, funds and other contents throughout the life cycle of large-scale activities. Recognize and classify the ultimate risk sources of people, objects and environment of large-scale activities from the perspective of interface. Put forward the accident cause analysis model according to the previous large-scale activities' accidents and combine with the analysis of the risk source interface. Analyze the risks of each interface and summary various types of risks the large-scale activities faced. Come up with the risk management consciousness, policies and regulations, risk control and supervision departments improvement ideas.

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

    PubMed

    Jarvas, Gabor; Guttman, Andras; Foret, Frantisek

    2015-01-01

    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 34: 558-569, 2015. © 2014 Wiley Periodicals, Inc.

  3. Broadening the interface bandwidth in simulation based training

    NASA Technical Reports Server (NTRS)

    Somers, Larry E.

    1989-01-01

    Currently most computer based simulations rely exclusively on computer generated graphics to create the simulation. When training is involved, the method almost exclusively used to display information to the learner is text displayed on the cathode ray tube. MICROEXPERT Systems is concentrating on broadening the communications bandwidth between the computer and user by employing a novel approach to video image storage combined with sound and voice output. An expert system is used to combine and control the presentation of analog video, sound, and voice output with computer based graphics and text. Researchers are currently involved in the development of several graphics based user interfaces for NASA, the U.S. Army, and the U.S. Navy. Here, the focus is on the human factors considerations, software modules, and hardware components being used to develop these interfaces.

  4. Symmetric model of compressible granular mixtures with permeable interfaces

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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

  5. Generalized model for solid-on-solid interface growth.

    PubMed

    Richele, M F; Atman, A P F

    2015-05-01

    We present a probabilistic cellular automaton (PCA) model to study solid-on-solid interface growth in which the transition rules depend on the local morphology of the profile obtained from the interface representation of the PCA. We show that the model is able to reproduce a wide range of patterns whose critical roughening exponents are associated to different universality classes, including random deposition, Edwards-Wilkinson, and Kardar-Parisi-Zhang. By means of the growth exponent method, we consider a particular set of the model parameters to build the two-dimensional phase diagram corresponding to a planar cut of the higher dimensional parameter space. A strong indication of phase transition between different universality classes can be observed, evincing different regimes of deposition, from layer-by-layer to Volmer-Weber and Stransk-Krastanov-like modes. We expect that this model can be useful to predict the morphological properties of interfaces obtained at different surface deposition problems, since it allows us to simulate several experimental situations by setting the values of the specific transition probabilities in a very simple and direct way.

  6. Role of melt behavior in modifying oxidation distribution using an interface incorporated model in selective laser melting of aluminum-based material

    SciTech Connect

    Gu, Dongdong Dai, Donghua

    2016-08-28

    A transient three dimensional model for describing the molten pool dynamics and the response of oxidation film evolution in the selective laser melting of aluminum-based material is proposed. The physical difference in both sides of the scan track, powder-solid transformation and temperature dependent physical properties are taken into account. It shows that the heat energy tends to accumulate in the powder material rather than in the as-fabricated part, leading to the formation of the asymmetrical patterns of the temperature contour and the attendant larger dimensions of the molten pool in the powder phase. As a higher volumetric energy density is applied (≥1300 J/mm{sup 3}), a severe evaporation is produced with the upward direction of velocity vector in the irradiated powder region while a restricted operating temperature is obtained in the as-fabricated part. The velocity vector continuously changes from upward direction to the downward one as the scan speed increases from 100 mm/s to 300 mm/s, promoting the generation of the debris of the oxidation films and the resultant homogeneous distribution state in the matrix. For the applied hatch spacing of 50 μm, a restricted remelting phenomenon of the as-fabricated part is produced with the upward direction of the convection flow, significantly reducing the turbulence of the thermal-capillary convection on the breaking of the oxidation films, and therefore, the connected oxidation films through the neighboring layers are typically formed. The morphology and distribution of the oxidation are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  7. Role of melt behavior in modifying oxidation distribution using an interface incorporated model in selective laser melting of aluminum-based material

    NASA Astrophysics Data System (ADS)

    Gu, Dongdong; Dai, Donghua

    2016-08-01

    A transient three dimensional model for describing the molten pool dynamics and the response of oxidation film evolution in the selective laser melting of aluminum-based material is proposed. The physical difference in both sides of the scan track, powder-solid transformation and temperature dependent physical properties are taken into account. It shows that the heat energy tends to accumulate in the powder material rather than in the as-fabricated part, leading to the formation of the asymmetrical patterns of the temperature contour and the attendant larger dimensions of the molten pool in the powder phase. As a higher volumetric energy density is applied (≥1300 J/mm3), a severe evaporation is produced with the upward direction of velocity vector in the irradiated powder region while a restricted operating temperature is obtained in the as-fabricated part. The velocity vector continuously changes from upward direction to the downward one as the scan speed increases from 100 mm/s to 300 mm/s, promoting the generation of the debris of the oxidation films and the resultant homogeneous distribution state in the matrix. For the applied hatch spacing of 50 μm, a restricted remelting phenomenon of the as-fabricated part is produced with the upward direction of the convection flow, significantly reducing the turbulence of the thermal-capillary convection on the breaking of the oxidation films, and therefore, the connected oxidation films through the neighboring layers are typically formed. The morphology and distribution of the oxidation are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  8. Water velocity at water-air interface is not zero: Comment on "Three-dimensional quantification of soil hydraulic properties using X-ray computed tomography and image-based modeling" by Saoirse R. Tracy et al.

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Fan, X. Y.; Li, Z. Y.

    2016-07-01

    Tracy et al. (2015, doi: 10.1002/2014WR016020) assumed in their recent paper that water velocity at the water-air interface is zero in their pore-scale simulations of water flow in 3-D soil images acquired using X-ray computed tomography. We comment that such a treatment is physically wrong, and explain that it is the water-velocity gradient in the direction normal to the water-air interface, rather than the water velocity, that should be assumed to be zero at the water-air interface if one needs to decouple the water flow and the air flow. We analyze the potential errors caused by incorrectly taking water velocity at the water-air interface zero based on two simple examples, and conclude that it is not physically sound to make such a presumption because its associated errors are unpredictable.

  9. Penalty-Based Finite Element Interface Technology for Analysis of Homogeneous and Composite Structures

    NASA Technical Reports Server (NTRS)

    Averill, Ronald C.

    2002-01-01

    An effective and robust interface element technology able to connect independently modeled finite element subdomains has been developed. This method is based on the use of penalty constraints and allows coupling of finite element models whose nodes do not coincide along their common interface. Additionally, the present formulation leads to a computational approach that is very efficient and completely compatible with existing commercial software. A significant effort has been directed toward identifying those model characteristics (element geometric properties, material properties, and loads) that most strongly affect the required penalty parameter, and subsequently to developing simple 'formulae' for automatically calculating the proper penalty parameter for each interface constraint. This task is especially critical in composite materials and structures, where adjacent sub-regions may be composed of significantly different materials or laminates. This approach has been validated by investigating a variety of two-dimensional problems, including composite laminates.

  10. Stability of finite difference models containing two boundaries or interfaces

    NASA Technical Reports Server (NTRS)

    Trefethen, L. N.

    1984-01-01

    The stability of finite difference models of hyperbolic initial boundary value problems is connected with the propagation and reflection of parasitic waves. Wave propagation ideas are applied to models containing two boundaires or interfaces, where repeated reflection of trapped wave packets is a potential new source of instability. Various known instability phenomena are accounted for in a unified way. Results show: (1) dissipativity does not ensure stability when three or more formulas are concatenated at a boundary or internal interface; (2) algebraic GKS instabilities can be converted by a second boundary to exponential instabilities only when an infinite numerical reflection coefficient is present; and (3) GKS-stability and P-stability can be established in certain problems by showing that all numerical reflection coefficients have modulus less than 1.

  11. Modelling compensated antiferromagnetic interfaces with MuMax3

    NASA Astrophysics Data System (ADS)

    De Clercq, Jonas; Leliaert, Jonathan; Van Waeyenberge, Bartel

    2017-10-01

    We show how compensated antiferromagnetic interfaces can be implemented in the micromagnetic simulation program MuMax3. We demonstrate that we can model spin flop coupling as a uniaxial anisotropy for small canting angles and how we can take into account the exact energy terms for strong coupling between a ferromagnet and a compensated antiferromagnet. We also investigate athermal training in biaxial antiferromagnets and reproduce the training effect in a polycrystalline IrMn/CoFe bilayer.

  12. Entropic interfaces in hard-core model amphiphilic mixtures.

    PubMed

    Brader, Joseph M; Schmidt, Matthias

    2005-01-15

    We investigate bulk and interfacial properties of a recently proposed hard-body model for a ternary mixture of amphiphilic particles, spheres and needles using density functional theory. The simple model amphiphiles are formed by bonding a vanishingly thin needle tail radially to a hard-sphere head group. Such particles provide a natural amphiphile when added to a binary mixture of spheres and needles. As all interactions are hard, we seek to find whether amphiphilic effects can be driven by entropy without the need to invoke attractive interactions. In order to assess the amphiphilic character of the model we first examine the spatial and orientational distribution of the amphiphiles at the free interface between demixed needle-rich and amphiphile-rich fluid phases of the binary amphiphile-needle subsystem. We then consider the free interface between sphere-rich and needle-rich phases upon adding amphiphiles with low concentration to the demixed system. In both cases the orientational distribution of the particles in the interface provides strong evidence that amphiphilic properties can arise purely from geometrical packing effects.

  13. Wavelet transforms in a critical interface model for Barkhausen noise.

    PubMed

    de Queiroz, S L A

    2008-02-01

    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.

  14. WATGEN: an algorithm for modeling water networks at protein-protein interfaces.

    PubMed

    Bui, Huynh-Hoa; Schiewe, Alexandra J; Haworth, Ian S

    2007-11-15

    Water molecules at protein-protein interfaces contribute to the close packing of atoms and ensure complementarity between the protein surfaces, as well as mediating polar interactions. Therefore, modeling of interface water is of importance in understanding the structural basis of biomolecular association. We present an algorithm, WATGEN, which predicts locations for water molecules at a protein-protein or protein-peptide interface, given the atomic coordinates of the protein and peptide. A key element of the WATGEN algorithm is the prediction of water sites that can form multiple hydrogen bonds that bridge the binding interface. Trial calculations were performed on water networks predicted by WATGEN at 126 protein-peptide interfaces (X-ray resolutions interfaces include 1264 experimentally determined bridging water sites, and the WATGEN algorithm predicts 72 and 88% of these sites within 1.5 and 2.0 A, respectively. The predicted number of water molecules at each interface was much higher than the number of water molecules identified experimentally. Therefore, random placement of the same number of water molecules as that predicted at each interface was performed as a control, and resulted in only 22 and 40% of water sites placed within 1.5 and 2.0 A of experimental sites, respectively. Based on these data, we conclude that WATGEN can accurately predict the location of water molecules at a protein-peptide interface, and this may be of value for understanding the energetics and specificity of biomolecular association. (c) 2007 Wiley Periodicals, Inc.

  15. The JAVA-based DICOM query interface DicoSE.

    PubMed

    Prinz, Michael; Fischer, Georg; Schuster, Ernst

    2005-03-01

    DICOM 3 is a very elaborate standard for the communication between medical image devices. It is published in several parts by the National Electrical Manufacturers Association (NEMA). To adequately visualize the data structure defined in parts 3, 5 and 6 of the DICOM standard, we implemented the web based Dicom Search Engine (DicoSE). It allows for querying the DICOM standard data dictionary for defined data fields and visualizes the topology of the data which is inherently present in DICOM datasets. For the administration of the underlying data a web based administration interface is provided. The service is entirely based on freely available software.

  16. Particle self-assembly at ionic liquid-based interfaces.

    PubMed

    Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

    2014-04-01

    This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil

  17. Towards the virtual artery: a multiscale model for vascular physiology at the physics-chemistry-biology interface

    NASA Astrophysics Data System (ADS)

    Hoekstra, Alfons G.; Alowayyed, Saad; Lorenz, Eric; Melnikova, Natalia; Mountrakis, Lampros; van Rooij, Britt; Svitenkov, Andrew; Závodszky, Gábor; Zun, Pavel

    2016-11-01

    This discussion paper introduces the concept of the Virtual Artery as a multiscale model for arterial physiology and pathologies at the physics-chemistry-biology (PCB) interface. The cellular level is identified as the mesoscopic level, and we argue that by coupling cell-based models with other relevant models on the macro- and microscale, a versatile model of arterial health and disease can be composed. We review the necessary ingredients, both models of arteries at many different scales, as well as generic methods to compose multiscale models. Next, we discuss how this can be combined into the virtual artery. Finally, we argue that the concept of models at the PCB interface could or perhaps should become a powerful paradigm, not only as in our case for studying physiology, but also for many other systems that have such PCB interfaces. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  18. Towards the virtual artery: a multiscale model for vascular physiology at the physics-chemistry-biology interface.

    PubMed

    Hoekstra, Alfons G; Alowayyed, Saad; Lorenz, Eric; Melnikova, Natalia; Mountrakis, Lampros; van Rooij, Britt; Svitenkov, Andrew; Závodszky, Gábor; Zun, Pavel

    2016-11-13

    This discussion paper introduces the concept of the Virtual Artery as a multiscale model for arterial physiology and pathologies at the physics-chemistry-biology (PCB) interface. The cellular level is identified as the mesoscopic level, and we argue that by coupling cell-based models with other relevant models on the macro- and microscale, a versatile model of arterial health and disease can be composed. We review the necessary ingredients, both models of arteries at many different scales, as well as generic methods to compose multiscale models. Next, we discuss how this can be combined into the virtual artery. Finally, we argue that the concept of models at the PCB interface could or perhaps should become a powerful paradigm, not only as in our case for studying physiology, but also for many other systems that have such PCB interfaces.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. © 2016 The Authors.

  19. Blocking and Blending: Different Assembly Models of Cyclodextrin and Sodium Caseinate at the Oil/Water Interface.

    PubMed

    Xu, Hua-Neng; Liu, Huan-Huan; Zhang, Lianfu

    2015-08-25

    The stability of cyclodextrin (CD)-based emulsions is attributed to the formation of a solid film of oil-CD complexes at the oil/water interface. However, competitive interactions between CDs and other components at the interface still need to be understood. Here we develop two different routes that allow the incorporation of a model protein (sodium caseinate, SC) into emulsions based on β-CD. One route is the components adsorbed simultaneously from a mixed solution to the oil/water interface (route I), and the other is SC was added to a previously established CD-stabilized interface (route II). The adsorption mechanism of β-CD modified by SC at the oil/water interface is investigated by rheological and optical methods. Strong sensitivity of the rheological behavior to the routes is indicated by both steady-state and small-deformation oscillatory experiments. Possible β-CD/SC interaction models at the interface are proposed. In route I, the protein, due to its higher affinity for the interface, adsorbs strongly at the interface with blocking of the adsorption of β-CD and formation of oil-CD complexes. In route II, the protein penetrates and blends into the preadsorbed layer of oil-CD complexes already formed at the interface. The revelation of interfacial assembly is expected to help better understand CD-based emulsions in natural systems and improve their designs in engineering applications.

  20. Hypertext-based design of a user interface for scheduling

    NASA Technical Reports Server (NTRS)

    Woerner, Irene W.; Biefeld, Eric

    1993-01-01

    Operations Mission Planner (OMP) is an ongoing research project at JPL that utilizes AI techniques to create an intelligent, automated planning and scheduling system. The information space reflects the complexity and diversity of tasks necessary in most real-world scheduling problems. Thus the problem of the user interface is to present as much information as possible at a given moment and allow the user to quickly navigate through the various types of displays. This paper describes a design which applies the hypertext model to solve these user interface problems. The general paradigm is to provide maps and search queries to allow the user to quickly find an interesting conflict or problem, and then allow the user to navigate through the displays in a hypertext fashion.

  1. Hypertext-based design of a user interface for scheduling

    NASA Technical Reports Server (NTRS)

    Woerner, Irene W.; Biefeld, Eric

    1993-01-01

    Operations Mission Planner (OMP) is an ongoing research project at JPL that utilizes AI techniques to create an intelligent, automated planning and scheduling system. The information space reflects the complexity and diversity of tasks necessary in most real-world scheduling problems. Thus the problem of the user interface is to present as much information as possible at a given moment and allow the user to quickly navigate through the various types of displays. This paper describes a design which applies the hypertext model to solve these user interface problems. The general paradigm is to provide maps and search queries to allow the user to quickly find an interesting conflict or problem, and then allow the user to navigate through the displays in a hypertext fashion.

  2. Developing a laser shockwave model for characterizing diffusion bonded interfaces

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) with the goal of 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 in high-power research reactors. The new LEU fuel is a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to support the fuel qualification process, the Laser Shockwave Technique (LST) is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated 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, because the deposition of laser energy into the containment layer on a specimen's surface is intractably complex, the shock wave energy is inferred from the surface velocity measured on the backside of the fuel plate and the depth of the impression left on the surface by the high pressure plasma pulse created by the shock laser. To help quantify the stresses generated at the interfaces, a finite element method (FEM) model is being utilized. This paper will report on initial efforts to develop and validate the model by comparing numerical and experimental results for back surface velocities and front surface depressions in a single aluminum plate representative of the fuel cladding.

  3. Developing a laser shockwave model for characterizing diffusion bonded interfaces

    SciTech Connect

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

    2015-03-31

    The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) with the goal of 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 in high-power research reactors. The new LEU fuel is a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to support the fuel qualification process, the Laser Shockwave Technique (LST) is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated 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, because the deposition of laser energy into the containment layer on a specimen's surface is intractably complex, the shock wave energy is inferred from the surface velocity measured on the backside of the fuel plate and the depth of the impression left on the surface by the high pressure plasma pulse created by the shock laser. To help quantify the stresses generated at the interfaces, a finite element method (FEM) model is being utilized. This paper will report on initial efforts to develop and validate the model by comparing numerical and experimental results for back surface velocities and front surface depressions in a single aluminum plate representative of the fuel cladding.

  4. A diffuse interface model of grain boundary faceting

    NASA Astrophysics Data System (ADS)

    Abdeljawad, Fadi; Medlin, Douglas; Zimmerman, Jonathan; Hattar, Khalid; Foiles, Stephen

    Incorporating anisotropy into thermodynamic treatments of interfaces dates back to over a century ago. For a given orientation of two abutting grains in a pure metal, depressions in the grain boundary (GB) energy may exist as a function of GB inclination, defined by the plane normal. Therefore, an initially flat GB may facet resulting in a hill-and-valley structure. Herein, we present a diffuse interface model of GB faceting that is capable of capturing anisotropic GB energies and mobilities, and accounting for the excess energy due to facet junctions and their non-local interactions. The hallmark of our approach is the ability to independently examine the role of each of the interface properties on the faceting behavior. As a demonstration, we consider the Σ 5 < 001 > tilt GB in iron, where faceting along the { 310 } and { 210 } planes was experimentally observed. Linear stability analysis and numerical examples highlight the role of junction energy and associated non-local interactions on the resulting facet length scales. On the whole, our modeling approach provides a general framework to examine the spatio-temporal evolution of highly anisotropic GBs in polycrystalline metals. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  5. Design of electronic medical record user interfaces: a matrix-based method for improving usability.

    PubMed

    Kuqi, Kushtrim; Eveleigh, Tim; Holzer, Thomas; Sarkani, Shahryar; Levin, James E; Crowley, Rebecca S

    2013-01-01

    This study examines a new approach of using the Design Structure Matrix (DSM) modeling technique to improve the design of Electronic Medical Record (EMR) user interfaces. The usability of an EMR medication dosage calculator used for placing orders in an academic hospital setting was investigated. The proposed method captures and analyzes the interactions between user interface elements of the EMR system and groups elements based on information exchange, spatial adjacency, and similarity to improve screen density and time-on-task. Medication dose adjustment task time was recorded for the existing and new designs using a cognitive simulation model that predicts user performance. We estimate that the design improvement could reduce time-on-task by saving an average of 21 hours of hospital physicians' time over the course of a month. The study suggests that the application of DSM can improve the usability of an EMR user interface.

  6. Magnetic interface forward and inversion method based on Padé approximation

    NASA Astrophysics Data System (ADS)

    Zhang, Chong; Huang, Da-Nian; Zhang, Kai; Pu, Yi-Tao; Yu, Ping

    2016-12-01

    The magnetic interface forward and inversion method is realized using the Taylor series expansion to linearize the Fourier transform of the exponential function. With a large expansion step and unbounded neighborhood, the Taylor series is not convergent, and therefore, this paper presents the magnetic interface forward and inversion method based on Padé approximation instead of the Taylor series expansion. Compared with the Taylor series, Padé's expansion's convergence is more stable and its approximation more accurate. Model tests show the validity of the magnetic forward modeling and inversion of Padé approximation proposed in the paper, and when this inversion method is applied to the measured data of the Matagami area in Canada, a stable and reasonable distribution of underground interface is obtained.

  7. Switchable Thermal Interfaces Based on Discrete Liquid Droplets

    SciTech Connect

    Jia, YB; Cha, G; Ju, YS

    2012-01-06

    We present a switchable thermal interface based on an array of discrete liquid droplets initially confined on hydrophilic islands on a substrate. The droplets undergo reversible morphological transition into a continuous liquid film when they are mechanically compressed by an opposing substrate to create low-thermal resistance heat conduction path. We investigate a criterion for reversible switching in terms of hydrophilic pattern size and liquid volume. The dependence of the liquid morphology and rupture distance on the diameter and areal fraction of hydrophilic islands, liquid volumes, as well as loading pressure is also characterized both theoretically and experimentally. The thermal resistance in the on-state is experimentally characterized for ionic liquids, which are promising for practical applications due to their negligible vapor pressure. A life testing setup is constructed to evaluate the reliability of the interface under continued switching conditions at relatively high switching frequencies.

  8. An open source web interface for linking models to infrastructure system databases

    NASA Astrophysics Data System (ADS)

    Knox, S.; Mohamed, K.; Harou, J. J.; Rheinheimer, D. E.; Medellin-Azuara, J.; Meier, P.; Tilmant, A.; Rosenberg, D. E.

    2016-12-01

    Models of networked engineered resource systems such as water or energy systems are often built collaboratively with developers from different domains working at different locations. These models can be linked to large scale real world databases, and they are constantly being improved and extended. As the development and application of these models becomes more sophisticated, and the computing power required for simulations and/or optimisations increases, so has the need for online services and tools which enable the efficient development and deployment of these models. Hydra Platform is an open source, web-based data management system, which allows modellers of network-based models to remotely store network topology and associated data in a generalised manner, allowing it to serve multiple disciplines. Hydra Platform uses a web API using JSON to allow external programs (referred to as `Apps') to interact with its stored networks and perform actions such as importing data, running models, or exporting the networks to different formats. Hydra Platform supports multiple users accessing the same network and has a suite of functions for managing users and data. We present ongoing development in Hydra Platform, the Hydra Web User Interface, through which users can collaboratively manage network data and models in a web browser. The web interface allows multiple users to graphically access, edit and share their networks, run apps and view results. Through apps, which are located on the server, the web interface can give users access to external data sources and models without the need to install or configure any software. This also ensures model results can be reproduced by removing platform or version dependence. Managing data and deploying models via the web interface provides a way for multiple modellers to collaboratively manage data, deploy and monitor model runs and analyse results.

  9. Modelling and simulation of a moving interface problem: freeze drying of black tea extract

    NASA Astrophysics Data System (ADS)

    Aydin, Ebubekir Sıddık; Yucel, Ozgun; Sadikoglu, Hasan

    2017-01-01

    The moving interface separates the material that is subjected to the freeze drying process as dried and frozen. Therefore, the accurate modeling the moving interface reduces the process time and energy consumption by improving the heat and mass transfer predictions during the process. To describe the dynamic behavior of the drying stages of the freeze-drying, a case study of brewed black tea extract in storage trays including moving interface was modeled that the heat and mass transfer equations were solved using orthogonal collocation method based on Jacobian polynomial approximation. Transport parameters and physical properties describing the freeze drying of black tea extract were evaluated by fitting the experimental data using Levenberg-Marquardt algorithm. Experimental results showed good agreement with the theoretical predictions.

  10. Modelling and simulation of a moving interface problem: freeze drying of black tea extract

    NASA Astrophysics Data System (ADS)

    Aydin, Ebubekir Sıddık; Yucel, Ozgun; Sadikoglu, Hasan

    2017-06-01

    The moving interface separates the material that is subjected to the freeze drying process as dried and frozen. Therefore, the accurate modeling the moving interface reduces the process time and energy consumption by improving the heat and mass transfer predictions during the process. To describe the dynamic behavior of the drying stages of the freeze-drying, a case study of brewed black tea extract in storage trays including moving interface was modeled that the heat and mass transfer equations were solved using orthogonal collocation method based on Jacobian polynomial approximation. Transport parameters and physical properties describing the freeze drying of black tea extract were evaluated by fitting the experimental data using Levenberg-Marquardt algorithm. Experimental results showed good agreement with the theoretical predictions.

  11. Graphic user interface-based nuclear medicine reporting system.

    PubMed

    Sanger, J J

    1993-03-01

    A graphically based, computerized report generation program has been developed and deployed at a dozen nuclear medicine facilities. The system is based on the Macintosh graphical user interface (GUI) and has been designed to be easy to learn and use. The system allows the nuclear medicine practitioner to generate reports for any nuclear medicine or nuclear cardiology procedure without transcriptionist support, dramatically decreasing report turnaround time. The system includes a relational database engine that allows cost-effective storage and rapid retrieval of final reports and also supports facsimile transmission of reports directly to referring clinicians' offices.

  12. A Graph Based Interface for Representing Volume Visualization Results

    NASA Technical Reports Server (NTRS)

    Patten, James M.; Ma, Kwan-Liu

    1998-01-01

    This paper discusses a graph based user interface for representing the results of the volume visualization process. As images are rendered, they are connected to other images in a graph based on their rendering parameters. The user can take advantage of the information in this graph to understand how certain rendering parameter changes affect a dataset, making the visualization process more efficient. Because the graph contains more information than is contained in an unstructured history of images, the image graph is also helpful for collaborative visualization and animation.

  13. fNIRS-based brain-computer interfaces: a review.

    PubMed

    Naseer, Noman; Hong, Keum-Shik

    2015-01-01

    A brain-computer interface (BCI) is a communication system that allows the use of brain activity to control computers or other external devices. It can, by bypassing the peripheral nervous system, provide a means of communication for people suffering from severe motor disabilities or in a persistent vegetative state. In this paper, brain-signal generation tasks, noise removal methods, feature extraction/selection schemes, and classification techniques for fNIRS-based BCI are reviewed. The most common brain areas for fNIRS BCI are the primary motor cortex and the prefrontal cortex. In relation to the motor cortex, motor imagery tasks were preferred to motor execution tasks since possible proprioceptive feedback could be avoided. In relation to the prefrontal cortex, fNIRS showed a significant advantage due to no hair in detecting the cognitive tasks like mental arithmetic, music imagery, emotion induction, etc. In removing physiological noise in fNIRS data, band-pass filtering was mostly used. However, more advanced techniques like adaptive filtering, independent component analysis (ICA), multi optodes arrangement, etc. are being pursued to overcome the problem that a band-pass filter cannot be used when both brain and physiological signals occur within a close band. In extracting features related to the desired brain signal, the mean, variance, peak value, slope, skewness, and kurtosis of the noised-removed hemodynamic response were used. For classification, the linear discriminant analysis method provided simple but good performance among others: support vector machine (SVM), hidden Markov model (HMM), artificial neural network, etc. fNIRS will be more widely used to monitor the occurrence of neuro-plasticity after neuro-rehabilitation and neuro-stimulation. Technical breakthroughs in the future are expected via bundled-type probes, hybrid EEG-fNIRS BCI, and through the detection of initial dips.

  14. fNIRS-based brain-computer interfaces: a review

    PubMed Central

    Naseer, Noman; Hong, Keum-Shik

    2015-01-01

    A brain-computer interface (BCI) is a communication system that allows the use of brain activity to control computers or other external devices. It can, by bypassing the peripheral nervous system, provide a means of communication for people suffering from severe motor disabilities or in a persistent vegetative state. In this paper, brain-signal generation tasks, noise removal methods, feature extraction/selection schemes, and classification techniques for fNIRS-based BCI are reviewed. The most common brain areas for fNIRS BCI are the primary motor cortex and the prefrontal cortex. In relation to the motor cortex, motor imagery tasks were preferred to motor execution tasks since possible proprioceptive feedback could be avoided. In relation to the prefrontal cortex, fNIRS showed a significant advantage due to no hair in detecting the cognitive tasks like mental arithmetic, music imagery, emotion induction, etc. In removing physiological noise in fNIRS data, band-pass filtering was mostly used. However, more advanced techniques like adaptive filtering, independent component analysis (ICA), multi optodes arrangement, etc. are being pursued to overcome the problem that a band-pass filter cannot be used when both brain and physiological signals occur within a close band. In extracting features related to the desired brain signal, the mean, variance, peak value, slope, skewness, and kurtosis of the noised-removed hemodynamic response were used. For classification, the linear discriminant analysis method provided simple but good performance among others: support vector machine (SVM), hidden Markov model (HMM), artificial neural network, etc. fNIRS will be more widely used to monitor the occurrence of neuro-plasticity after neuro-rehabilitation and neuro-stimulation. Technical breakthroughs in the future are expected via bundled-type probes, hybrid EEG-fNIRS BCI, and through the detection of initial dips. PMID:25674060

  15. Breather trapping and breather transmission in a DNA model with an interface

    NASA Astrophysics Data System (ADS)

    Alvarez, A.; Romero, F. R.; Archilla, J. F. R.; Cuevas, J.; Larsen, P. V.

    2006-05-01

    We study the dynamics of moving discrete breathers in an interfaced piecewise DNA molecule. This is a DNA chain in which all the base pairs are identical and there exists an interface such that the base pairs dipole moments at each side are oriented in opposite directions. The Hamiltonian of the Peyrard-Bishop model is augmented with a term that includes the dipole-dipole coupling between base pairs. Numerical simulations show the existence of two dynamical regimes. If the translational kinetic energy of a moving breather launched towards the interface is below a critical value, it is trapped in a region around the interface collecting vibrational energy. For an energy larger than the critical value, the breather is transmitted and continues travelling along the double strand with lower velocity. Reflection phenomena never occur. The same study has been carried out when a single dipole is oriented in opposite direction to the other ones. When moving breathers collide with the single inverted dipole, the same effects appear. These results emphasize the importance of this simple type of local inhomogeneity as it creates a mechanism for the trapping of energy. Finally, the simulations show that, under favorable conditions, several launched moving breathers can be trapped successively at the interface region producing an accumulation of vibrational energy. Moreover, an additional colliding moving breather can produce a saturation of energy and a moving breather with all the accumulated energy is transmitted to the chain.

  16. Modeling Complex Cross-Systems Software Interfaces Using SysML

    NASA Technical Reports Server (NTRS)

    Mandutianu, Sanda; Morillo, Ron; Simpson, Kim; Liepack, Otfrid; Bonanne, Kevin

    2013-01-01

    The complex flight and ground systems for NASA human space exploration are designed, built, operated and managed as separate programs and projects. However, each system relies on one or more of the other systems in order to accomplish specific mission objectives, creating a complex, tightly coupled architecture. Thus, there is a fundamental need to understand how each system interacts with the other. To determine if a model-based system engineering approach could be utilized to assist with understanding the complex system interactions, the NASA Engineering and Safety Center (NESC) sponsored a task to develop an approach for performing cross-system behavior modeling. This paper presents the results of applying Model Based Systems Engineering (MBSE) principles using the System Modeling Language (SysML) to define cross-system behaviors and how they map to crosssystem software interfaces documented in system-level Interface Control Documents (ICDs).

  17. Modeling Complex Cross-Systems Software Interfaces Using SysML

    NASA Technical Reports Server (NTRS)

    Mandutianu, Sanda; Morillo, Ron; Simpson, Kim; Liepack, Otfrid; Bonanne, Kevin

    2013-01-01

    The complex flight and ground systems for NASA human space exploration are designed, built, operated and managed as separate programs and projects. However, each system relies on one or more of the other systems in order to accomplish specific mission objectives, creating a complex, tightly coupled architecture. Thus, there is a fundamental need to understand how each system interacts with the other. To determine if a model-based system engineering approach could be utilized to assist with understanding the complex system interactions, the NASA Engineering and Safety Center (NESC) sponsored a task to develop an approach for performing cross-system behavior modeling. This paper presents the results of applying Model Based Systems Engineering (MBSE) principles using the System Modeling Language (SysML) to define cross-system behaviors and how they map to crosssystem software interfaces documented in system-level Interface Control Documents (ICDs).

  18. Protein-protein interaction interface residue pair prediction based on deep learning architecture.

    PubMed

    Zhao, Zhenni; Gong, Xinqi

    2017-05-19

    Proteins usually fulfill their biological functions by interacting with other proteins. Although some methods have been developed to predict the binding sites of a monomer protein, these are not sufficient for prediction of the interaction between two monomer proteins. The correct prediction of interface residue pairs from two monomer proteins is still an open question and has great significance for practical experimental applications in the life sciences. We hope to build a method for the prediction of interface residue pairs that is suitable for those applications. Here, we developed a novel deep network architecture called the multi-layered Long-Short Term Memory networks (LSTMs) approach for the prediction of protein interface residue pairs. Firstly, we created three new descriptions and used other six worked characterizations to describe an amino acid, then we employed these features to discriminate between interface residue pairs and non-interface residue pairs. Secondly, we used two thresholds to select residue pairs that are more likely to be interface residue pairs. Furthermore, this step increases the proportion of interface residue pairs and reduces the influence of imbalanced data. Thirdly, we built deep network architectures based on Long-Short Term Memory networks algorithm to organize and refine the prediction of interface residue pairs by employing features mentioned above. We trained the deep networks on dimers in the unbound state in the international Protein-protein Docking Benchmark version 3.0. The updated data sets in the versions 4.0 and 5.0 were used as the validation set and test set respectively. For our best model, the accuracy rate was over 62% when we chose the top 0.2% pairs of every dimer in the test set as predictions, which will be very helpful for the understanding of protein-protein interaction mechanisms and for guidance in biological experiments.

  19. Physics-Based 3-D Simulation for Earthquake Generation Cycles at Plate Interfaces in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Hashimoto, Chihiro; Fukuyama, Eiichi; Matsu'ura, Mitsuhiro

    2014-08-01

    The generation of interplate earthquakes can be regarded as a process of tectonic stress accumulation and release, driven by relative plate motion. We completed a physics-based simulation system for earthquake generation cycles at plate interfaces in the Japan region, where the Pacific plate is descending beneath the North American and Philippine Sea plates, and the Philippine Sea plate is descending beneath the North American and Eurasian plates. The system is composed of a quasi-static tectonic loading model and a dynamic rupture propagation model, developed on a realistic 3-D plate interface model. The driving force of the system is relative plate motion. In the quasi-static tectonic loading model, mechanical interaction at plate interfaces is rationally represented by the increase of tangential displacement discontinuity (fault slip) across them on the basis of dislocation theory for an elastic surface layer overlying Maxwell-type viscoelastic half-space. In the dynamic rupture propagation model, stress changes due to fault slip motion on non-planar plate interfaces are evaluated with the boundary integral equation method. The progress of seismic (dynamic) or aseismic (quasi-static) fault slip on plate interfaces is governed by a slip- and time-dependent fault constitutive law. As an example, we numerically simulated earthquake generation cycles at the source region of the 1968 Tokachi-oki earthquake on the North American-Pacific plate interface. From the numerical simulation, we can see that postseismic stress relaxation in the asthenosphere accelerates stress accumulation in the source region. When the stress state of the source region is close to a critical level, dynamic rupture is rapidly accelerated and develops over the whole source region. When the stress state is much lower than the critical level, the rupture is not accelerated. This means that the stress state realized by interseismic tectonic loading essentially controls the subsequent dynamic

  20. Importance of interfaces in governing thermal transport in composite materials: modeling and experimental perspectives.

    PubMed

    Roy, Ajit K; Farmer, Barry L; Varshney, Vikas; Sihn, Sangwook; Lee, Jonghoon; Ganguli, Sabyasachi

    2012-02-01

    Thermal management in polymeric composite materials has become increasingly critical in the air-vehicle industry because of the increasing thermal load in small-scale composite devices extensively used in electronics and aerospace systems. The thermal transport phenomenon in these small-scale heterogeneous systems is essentially controlled by the interface thermal resistance because of the large surface-to-volume ratio. In this review article, several modeling strategies are discussed for different length scales, complemented by our experimental efforts to tailor the thermal transport properties of polymeric composite materials. Progress in the molecular modeling of thermal transport in thermosets is reviewed along with a discussion on the interface thermal resistance between functionalized carbon nanotube and epoxy resin systems. For the thermal transport in fiber-reinforced composites, various micromechanics-based analytical and numerical modeling schemes are reviewed in predicting the transverse thermal conductivity. Numerical schemes used to realize and scale the interface thermal resistance and the finite mean free path of the energy carrier in the mesoscale are discussed in the frame of the lattice Boltzmann-Peierls-Callaway equation. Finally, guided by modeling, complementary experimental efforts are discussed for exfoliated graphite and vertically aligned nanotubes based composites toward improving their effective thermal conductivity by tailoring interface thermal resistance.

  1. Organizing the public health-clinical health interface: theoretical bases.

    PubMed

    St-Pierre, Michèle; Reinharz, Daniel; Gauthier, Jacques-Bernard

    2006-01-01

    This article addresses the issue of the interface between public health and clinical health within the context of the search for networking approaches geared to a more integrated delivery of health services. The articulation of an operative interface is complicated by the fact that the definition of networking modalities involves complex intra- and interdisciplinary and intra- and interorganizational systems across which a new transversal dynamics of intervention practices and exchanges between service structures must be established. A better understanding of the situation is reached by shedding light on the rationale underlying the organizational methods that form the bases of the interface between these two sectors of activity. The Quebec experience demonstrates that neither the structural-functionalist approach, which emphasizes remodelling establishment structures and functions as determinants of integration, nor the structural-constructivist approach, which prioritizes distinct fields of practice in public health and clinical health, adequately serves the purpose of networking and integration. Consequently, a theoretical reframing is imperative. In this regard, structuration theory, which fosters the simultaneous study of methods of inter-structure coordination and inter-actor cooperation, paves the way for a better understanding of the situation and, in turn, to the emergence of new integration possibilities.

  2. Near infrared spectroscopy based brain-computer interface

    NASA Astrophysics Data System (ADS)

    Ranganatha, Sitaram; Hoshi, Yoko; Guan, Cuntai

    2005-04-01

    A brain-computer interface (BCI) provides users with an alternative output channel other than the normal output path of the brain. BCI is being given much attention recently as an alternate mode of communication and control for the disabled, such as patients suffering from Amyotrophic Lateral Sclerosis (ALS) or "locked-in". BCI may also find applications in military, education and entertainment. Most of the existing BCI systems which rely on the brain's electrical activity use scalp EEG signals. The scalp EEG is an inherently noisy and non-linear signal. The signal is detrimentally affected by various artifacts such as the EOG, EMG, ECG and so forth. EEG is cumbersome to use in practice, because of the need for applying conductive gel, and the need for the subject to be immobile. There is an urgent need for a more accessible interface that uses a more direct measure of cognitive function to control an output device. The optical response of Near Infrared Spectroscopy (NIRS) denoting brain activation can be used as an alternative to electrical signals, with the intention of developing a more practical and user-friendly BCI. In this paper, a new method of brain-computer interface (BCI) based on NIRS is proposed. Preliminary results of our experiments towards developing this system are reported.

  3. A biological model for controlling interface growth and morphology.

    SciTech Connect

    Hoyt, Jeffrey John; Holm, Elizabeth Ann

    2004-01-01

    Biological systems create proteins that perform tasks more efficiently and precisely than conventional chemicals. For example, many plants and animals produce proteins to control the freezing of water. Biological antifreeze proteins (AFPs) inhibit the solidification process, even below the freezing point. These molecules bond to specific sites at the ice/water interface and are theorized to suppress solidification chemically or geometrically. In this project, we investigated the theoretical and experimental data on AFPs and performed analyses to understand the unique physics of AFPs. The experimental literature was analyzed to determine chemical mechanisms and effects of protein bonding at ice surfaces, specifically thermodynamic freezing point depression, suppression of ice nucleation, decrease in dendrite growth kinetics, solute drag on the moving solid/liquid interface, and stearic pinning of the ice interface. Stearic pinning was found to be the most likely candidate to explain experimental results, including freezing point depression, growth morphologies, and thermal hysteresis. A new stearic pinning model was developed and applied to AFPs, with excellent quantitative results. Understanding biological antifreeze mechanisms could enable important medical and engineering applications, but considerable future work will be necessary.

  4. A diffuse interface model of grain boundary faceting

    NASA Astrophysics Data System (ADS)

    Abdeljawad, F.; Medlin, D. L.; Zimmerman, J. A.; Hattar, K.; Foiles, S. M.

    2016-06-01

    Interfaces, free or internal, greatly influence the physical properties and stability of materials microstructures. Of particular interest are the processes that occur due to anisotropic interfacial properties. In the case of grain boundaries (GBs) in metals, several experimental observations revealed that an initially flat GB may facet into hill-and-valley structures with well defined planes and corners/edges connecting them. Herein, we present a diffuse interface model that is capable of accounting for strongly anisotropic GB properties and capturing the formation of hill-and-valley morphologies. The hallmark of our approach is the ability to independently examine the various factors affecting GB faceting and subsequent facet coarsening. More specifically, our formulation incorporates higher order expansions to account for the excess energy due to facet junctions and their non-local interactions. As a demonstration of the modeling capability, we consider the Σ5 <001 > tilt GB in body-centered-cubic iron, where faceting along the {210} and {310} planes was experimentally observed. Atomistic calculations were utilized to determine the inclination-dependent GB energy, which was then used as an input in our model. Linear stability analysis and simulation results highlight the role of junction energy and associated non-local interactions on the resulting facet length scales. Broadly speaking, our modeling approach provides a general framework to examine the microstructural stability of polycrystalline systems with highly anisotropic GBs.

  5. A symbolic/subsymbolic interface protocol for cognitive modeling

    PubMed Central

    Simen, Patrick; Polk, Thad

    2009-01-01

    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

  6. A Strategy Based on Protein-Protein Interface Motifs May Help in Identifying Drug Off-Targets

    PubMed Central

    Engin, H. Billur; Keskin, Ozlem; Nussinov, Ruth; Gursoy, Attila

    2014-01-01

    Networks are increasingly used to study the impact of drugs at the systems level. From the algorithmic standpoint, a drug can ‘attack’ nodes or edges of a protein-protein interaction network. In this work, we propose a new network strategy, “The Interface Attack”, based on protein-protein interfaces. Similar interface architectures can occur between unrelated proteins. Consequently, in principle, a drug that binds to one has a certain probability of binding others. The interface attack strategy simultaneously removes from the network all interactions that consist of similar interface motifs. This strategy is inspired by network pharmacology and allows inferring potential off-targets. We introduce a network model which we call “Protein Interface and Interaction Network (P2IN)”, which is the integration of protein-protein interface structures and protein interaction networks. This interface-based network organization clarifies which protein pairs have structurally similar interfaces, and which proteins may compete to bind the same surface region. We built the P2IN of p53 signaling network and performed network robustness analysis. We show that (1) ‘hitting’ frequent interfaces (a set of edges distributed around the network) might be as destructive as eleminating high degree proteins (hub nodes); (2) frequent interfaces are not always topologically critical elements in the network; and (3) interface attack may reveal functional changes in the system better than attack of single proteins. In the off-target detection case study, we found that drugs blocking the interface between CDK6 and CDKN2D may also affect the interaction between CDK4 and CDKN2D. PMID:22817115

  7. A strategy based on protein-protein interface motifs may help in identifying drug off-targets.

    PubMed

    Engin, H Billur; Keskin, Ozlem; Nussinov, Ruth; Gursoy, Attila

    2012-08-27

    Networks are increasingly used to study the impact of drugs at the systems level. From the algorithmic standpoint, a drug can "attack" nodes or edges of a protein-protein interaction network. In this work, we propose a new network strategy, "The Interface Attack", based on protein-protein interfaces. Similar interface architectures can occur between unrelated proteins. Consequently, in principle, a drug that binds to one has a certain probability of binding to others. The interface attack strategy simultaneously removes from the network all interactions that consist of similar interface motifs. This strategy is inspired by network pharmacology and allows inferring potential off-targets. We introduce a network model that we call "Protein Interface and Interaction Network (P2IN)", which is the integration of protein-protein interface structures and protein interaction networks. This interface-based network organization clarifies which protein pairs have structurally similar interfaces and which proteins may compete to bind the same surface region. We built the P2IN with the p53 signaling network and performed network robustness analysis. We show that (1) "hitting" frequent interfaces (a set of edges distributed around the network) might be as destructive as eleminating high degree proteins (hub nodes), (2) frequent interfaces are not always topologically critical elements in the network, and (3) interface attack may reveal functional changes in the system better than the attack of single proteins. In the off-target detection case study, we found that drugs blocking the interface between CDK6 and CDKN2D may also affect the interaction between CDK4 and CDKN2D.

  8. Pen-based Interfaces for Engineering and Education

    NASA Astrophysics Data System (ADS)

    Stahovich, Thomas F.

    Sketches are an important problem-solving tool in many fields. This is particularly true of engineering design, where sketches facilitate creativity by providing an efficient medium for expressing ideas. However, despite the importance of sketches in engineering practice, current engineering software still relies on traditional mouse and keyboard interfaces, with little or no capabilities to handle free-form sketch input. With recent advances in machine-interpretation techniques, it is now becoming possible to create practical interpretation-based interfaces for such software. In this chapter, we report on our efforts to create interpretation techniques to enable pen-based engineering applications. We describe work on two fundamental sketch understanding problems. The first is sketch parsing, the task of clustering pen strokes or geometric primitives into individual symbols. The second is symbol recognition, the task of classifying symbols once they have been located by a parser. We have used the techniques that we have developed to construct several pen-based engineering analysis tools. These are used here as examples to illustrate our methods. We have also begun to use our techniques to create pen-based tutoring systems that scaffold students in solving problems in the same way they would ordinarily solve them with paper and pencil. The chapter concludes with a brief discussion of these systems.

  9. Czochralski growth of crystals - Simple models for growth rate and interface shape

    NASA Technical Reports Server (NTRS)

    Srivastava, R. K.; Ramachandran, P. A.; Dudukovic, M. P.

    1986-01-01

    A simple model for the crystal growth by the Czochralski (CZ) process has been proposed based on semiquantitative arguments. The model provides empirical relationships for the dependence of the pulling rate and the interface shape on the important process variables such as crystal radius, crucible temperature, height of the melt level, and the height of the exposed portion of the crucible wall. The parameters of the model can be evaluated by matching the results obtained from a detailed mathematical model of the CZ process or from extensive experimental data. The model has, therefore, the potential application for determining the best process conditions and for on-line control and optimization of the crystal puller to grow crystals with constant diameter and nearly planar interface.

  10. Characterization of domain-peptide interaction interface: prediction of SH3 domain-mediated protein-protein interaction network in yeast by generic structure-based models.

    PubMed

    Hou, Tingjun; Li, Nan; Li, Youyong; Wang, Wei

    2012-05-04

    Determination of the binding specificity of SH3 domain, a peptide recognition module (PRM), is important to understand their biological functions and reconstruct the SH3-mediated protein-protein interaction network. In the present study, the SH3-peptide interactions for both class I and II SH3 domains were characterized by the intermolecular residue-residue interaction network. We developed generic MIEC-SVM models to infer SH3 domain-peptide recognition specificity that achieved satisfactory prediction accuracy. By investigating the domain-peptide recognition mechanisms at the residue level, we found that the class-I and class-II binding peptides have different binding modes even though they occupy the same binding site of SH3. Furthermore, we predicted the potential binding partners of SH3 domains in the yeast proteome and constructed the SH3-mediated protein-protein interaction network. Comparison with the experimentally determined interactions confirmed the effectiveness of our approach. This study showed that our sophisticated computational approach not only provides a powerful platform to decipher protein recognition code at the molecular level but also allows identification of peptide-mediated protein interactions at a proteomic scale. We believe that such an approach is general to be applicable to other domain-peptide interactions.

  11. Characterization of Domain–Peptide Interaction Interface: Prediction of SH3 Domain-Mediated Protein–Protein Interaction Network in Yeast by Generic Structure-Based Models

    PubMed Central

    Hou, Tingjun; Li, Nan; Li, Youyong; Wang, Wei

    2012-01-01

    Determination of the binding specificity of SH3 domain, a peptide recognition module (PRM), is important to understand their biological functions and reconstruct the SH3-mediated protein–protein interaction network. In the present study, the SH3-peptide interactions for both class I and II SH3 domains were characterized by the intermolecular residue–residue interaction network. We developed generic MIEC-SVM models to infer SH3 domain-peptide recognition specificity that achieved satisfactory prediction accuracy. By investigating the domain–peptide recognition mechanisms at the residue level, we found that the class-I and class-II binding peptides have different binding modes even though they occupy the same binding site of SH3. Furthermore, we predicted the potential binding partners of SH3 domains in the yeast proteome and constructed the SH3-mediated protein–protein interaction network. Comparison with the experimentally determined interactions confirmed the effectiveness of our approach. This study showed that our sophisticated computational approach not only provides a powerful platform to decipher protein recognition code at the molecular level but also allows identification of peptide-mediated protein interactions at a proteomic scale. We believe that such an approach is general to be applicable to other domain–peptide interactions. PMID:22468754

  12. Spherical wave reflection in layered media with rough interfaces: Three-dimensional modeling.

    PubMed

    Pinson, Samuel; Cordioli, Julio; Guillon, Laurent

    2016-08-01

    In the context of sediment characterization, layer interface roughnesses may be responsible for sound-speed profile measurement uncertainties. To study the roughness influence, a three-dimensional (3D) modeling of a layered seafloor with rough interfaces is necessary. Although roughness scattering has an abundant literature, 3D modeling of spherical wave reflection on rough interfaces is generally limited to a single interface (using Kirchhoff-Helmholtz integral) or computationally expensive techniques (finite difference or finite element method). In this work, it is demonstrated that the wave reflection over a layered medium with irregular interfaces can be modeled as a sum of integrals over each interface. The main approximations of the method are the tangent-plane approximation, the Born approximation (multiple reflection between interfaces are neglected) and flat-interface approximation for the transmitted waves into the sediment. The integration over layer interfaces results in a method with reasonable computation cost.

  13. Flat interfaces in zinc oxide-based varistor ceramics

    SciTech Connect

    Sung, G.Y.; McKernan, S.; Carter, C.B. )

    1992-02-01

    Four types of structurally different, flat interfaces have been observed in ZnO-based varistor ceramics containing metal-oxides additives (Bi, Mn, and Ti) by bright-field and high-resolution imaging in a transmission electron microscope. Orientation relationships have been characterized by selected-area diffraction. The faceting of ZnO grains when in contact with {beta}--Bi{sub 2}O{sub 3} is discussed in relation to the anisotropic growth of the ZnO grains which leads to pronounced faceting parallel to (0001) planes.

  14. Non-Redundant Unique Interface Structures as Templates for Modeling Protein Interactions

    PubMed Central

    Cukuroglu, Engin; Gursoy, Attila; Nussinov, Ruth; Keskin, Ozlem

    2014-01-01

    Improvements in experimental techniques increasingly provide structural data relating to protein-protein interactions. Classification of structural details of protein-protein interactions can provide valuable insights for modeling and abstracting design principles. Here, we aim to cluster protein-protein interactions by their interface structures, and to exploit these clusters to obtain and study shared and distinct protein binding sites. We find that there are 22604 unique interface structures in the PDB. These unique interfaces, which provide a rich resource of structural data of protein-protein interactions, can be used for template-based docking. We test the specificity of these non-redundant unique interface structures by finding protein pairs which have multiple binding sites. We suggest that residues with more than 40% relative accessible surface area should be considered as surface residues in template-based docking studies. This comprehensive study of protein interface structures can serve as a resource for the community. The dataset can be accessed at http://prism.ccbb.ku.edu.tr/piface. PMID:24475173

  15. A numerical model and spreadsheet interface for pumping test analysis.

    PubMed

    Johnson, G S; Cosgrove, D M; Frederick, D B

    2001-01-01

    Curve-matching techniques have been the standard method of aquifer test analysis for several decades. A variety of techniques provide the capability of evaluating test data from confined, unconfined, leaky aquitard, and other conditions. Each technique, however, is accompanied by a set of assumptions, and evaluation of a combination of conditions can be complicated or impossible due to intractable mathematics or nonuniqueness of the solution. Numerical modeling of pumping tests provides two major advantages: (1) the user can choose which properties to calibrate and what assumptions to make; and (2) in the calibration process the user is gaining insights into the conceptual model of the flow system and uncertainties in the analysis. Routine numerical modeling of pumping tests is now practical due to computer hardware and software advances of the last decade. The RADFLOW model and spreadsheet interface presented in this paper is an easy-to-use numerical model for estimation of aquifer properties from pumping test data. Layered conceptual models and their properties are evaluated in a trial-and-error estimation procedure. The RADFLOW model can treat most combinations of confined, unconfined, leaky aquitard, partial penetration, and borehole storage conditions. RADFLOW is especially useful in stratified aquifer systems with no identifiable lateral boundaries. It has been verified to several analytical solutions and has been applied in the Snake River Plain Aquifer to develop and test conceptual models and provide estimates of aquifer properties. Because the model assumes axially symmetrical flow, it is limited to representing multiple aquifer layers that are laterally continuous.

  16. First principles modeling of the metal-electrolyte interface: A novel approach to the study of the electrochemical interface

    SciTech Connect

    Fernandez-Serra, Maria Victoria

    2016-09-12

    The research objective of this proposal is the computational modeling of the metal-electrolyte interface purely from first principles. The accurate calculation of the electrostatic potential at electrically biased metal-electrolyte interfaces is a current challenge for periodic “ab-initio” simulations. It is also an essential requisite for predicting the correspondence between the macroscopic voltage and the microscopic interfacial charge distribution in electrochemical fuel cells. This interfacial charge distribution is the result of the chemical bonding between solute and metal atoms, and therefore cannot be accurately calculated with the use of semi-empirical classical force fields. The project aims to study in detail the structure and dynamics of aqueous electrolytes at metallic interfaces taking into account the effect of the electrode potential. Another side of the project is to produce an accurate method to simulate the water/metal interface. While both experimental and theoretical surface scientists have made a lot of progress on the understanding and characterization of both atomistic structures and reactions at the solid/vacuum interface, the theoretical description of electrochemical interfaces is still lacking behind. A reason for this is that a complete and accurate first principles description of both the liquid and the metal interfaces is still computationally too expensive and complex, since their characteristics are governed by the explicit atomic and electronic structure built at the interface as a response to environmental conditions. This project will characterize in detail how different theoretical levels of modeling describer the metal/water interface. In particular the role of van der Waals interactions will be carefully analyzed and prescriptions to perform accurate simulations will be produced.

  17. Rule-based interface generation on mobile devices for structured documentation.

    PubMed

    Kock, Ann-Kristin; Andersen, Björn; Handels, Heinz; Ingenerf, Josef

    2014-01-01

    In many software systems to date, interactive graphical user interfaces (GUIs) are represented implicitly in the source code, together with the application logic. Hence, the re-use, development, and modification of these interfaces is often very laborious. Flexible adjustments of GUIs for various platforms and devices as well as individual user preferences are furthermore difficult to realize. These problems motivate a software-based separation of content and GUI models on the one hand, and application logic on the other. In this project, a software solution for structured reporting on mobile devices is developed. Clinical content archetypes developed in a previous project serve as the content model while the Android SDK provides the GUI model. The necessary bindings between the models are specified using the Jess Rule Language.

  18. A low cost human computer interface based on eye tracking.

    PubMed

    Hiley, Jonathan B; Redekopp, Andrew H; Fazel-Rezai, Reza

    2006-01-01

    This paper describes the implementation of a human computer interface based on eye tracking. Current commercially available systems exist, but have limited use due mainly to their large cost. The system described in this paper was designed to be a low cost and unobtrusive. The technique was video-oculography assisted by corneal reflections. An off-the shelf CCD webcam was used to capture images. The images were analyzed in software to extract key features of the eye. The users gaze point was then calculated based on the relative position of these features. The system is capable of calculating eye-gaze in real-time to provide a responsive interaction. A throughput of eight gaze points per second was achieved. The accuracy of the fixations based on the calculated eye-gazes were within 1 cm of the on-screen gaze location. By developing a low-cost system, this technology is made accessible to a wider range of applications.

  19. Numerical simulations of the moving contact line problem using a diffuse-interface model

    NASA Astrophysics Data System (ADS)

    Afzaal, Muhammad; Sibley, David; Duncan, Andrew; Yatsyshin, Petr; Duran-Olivencia, Miguel A.; Nold, Andreas; Savva, Nikos; Schmuck, Markus; Kalliadasis, Serafim

    2015-11-01

    Moving contact lines are a ubiquitous phenomenon both in nature and in many modern technologies. One prevalent way of numerically tackling the problem is with diffuse-interface (phase-field) models, where the classical sharp-interface model of continuum mechanics is relaxed to one with a finite thickness fluid-fluid interface, capturing physics from mesoscopic lengthscales. The present work is devoted to the study of the contact line between two fluids confined by two parallel plates, i.e. a dynamically moving meniscus. Our approach is based on a coupled Navier-Stokes/Cahn-Hilliard model. This system of partial differential equations allows a tractable numerical solution to be computed, capturing diffusive and advective effects in a prototypical case study in a finite-element framework. Particular attention is paid to the static and dynamic contact angle of the meniscus advancing or receding between the plates. The results obtained from our approach are compared to the classical sharp-interface model to elicit the importance of considering diffusion and associated effects. We acknowledge financial support from European Research Council via Advanced Grant No. 247031.

  20. Organic solar cells: a rigorous model of the donor-acceptor interface for various bulk heterojunction morphologies

    NASA Astrophysics Data System (ADS)

    Raba, Adam; Leroy, Yann; Cordan, Anne-Sophie

    2014-02-01

    Theoretical studies of organic solar cells are mostly based on one dimensional models. Despite their accuracy to reproduce most of the experimental trends, they intrinsically cannot correctly integrate the effects of morphology in cells based on a bulk heterojunction structure. Therefore, accounting for these effects requires the development of two dimensional models, in which donor and acceptor domains are explicitly distinct. In this context, we propose an analytical approach, which focuses on the description of the interface between the two domains. Assuming pinned charge transfer states, we rigorously derive the corresponding boundary conditions and explore the differences between this model and other existing models in the literature for various morphologies of the active layer. On one hand, all tested models are equivalent for an ideal interdigitated bulk heterojunction solar cell with a planar donor-acceptor interface, but divergences between the models rise for small sizes of the donor domain. On the other hand, we carried out a comparison on a less ideal case of cell, with a rough interface between the two domains. Simulations with such cells exhibit distinct behaviors for each model. We conclude that the boundary condition for the interface between the materials is of great importance for the study of solar cells with a non-planar interface. The model must account initially for the roughness of the interface.

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

    PubMed Central

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

    2014-01-01

    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

  2. Analysis of a diffuse interface model of multispecies tumor growth

    NASA Astrophysics Data System (ADS)

    Dai, Mimi; Feireisl, Eduard; Rocca, Elisabetta; Schimperna, Giulio; Schonbek, Maria E.

    2017-04-01

    We consider a diffuse interface model for tumor growth recently proposed in Chen et al (2014 Int. J. Numer. Methods Biomed. Eng. 30 726-54). In this new approach sharp interfaces are replaced by narrow transition layers arising due to adhesive forces among the cell species. Hence, a continuum thermodynamically consistent model is introduced. The resulting PDE system couples four different types of equations: a Cahn-Hilliard type equation for the tumor cells (which include proliferating and dead cells), a Darcy law for the tissue velocity field, whose divergence may be different from 0 and depend on the other variables, a transport equation for the proliferating (viable) tumor cells, and a quasi-static reaction diffusion equation for the nutrient concentration. We establish existence of weak solutions for the PDE system coupled with suitable initial and boundary conditions. In particular, the proliferation function at the boundary is supposed to be nonnegative on the set where the velocity \\mathbf{u} satisfies \\mathbf{u}\\centerdot ν >0 , where ν is the outer normal to the boundary of the domain.

  3. Diffuse-Interface Modelling of Flow in Porous Media

    NASA Astrophysics Data System (ADS)

    Addy, Doug; Pradas, Marc; Schmuck, Marcus; Kalliadasis, Serafim

    2016-11-01

    Multiphase flows are ubiquitous in a wide spectrum of scientific and engineering applications, and their computational modelling often poses many challenges associated with the presence of free boundaries and interfaces. Interfacial flows in porous media encounter additional challenges and complexities due to their inherently multiscale behaviour. Here we investigate the dynamics of interfaces in porous media using an effective convective Cahn-Hilliard (CH) equation recently developed in from a Stokes-CH equation for microscopic heterogeneous domains by means of a homogenization methodology, where the microscopic details are taken into account as effective tensor coefficients which are given by a Poisson equation. The equations are decoupled under appropriate assumptions and solved in series using a classic finite-element formulation with the open-source software FEniCS. We investigate the effects of different microscopic geometries, including periodic and non-periodic, at the bulk fluid flow, and find that our model is able to describe the effective macroscopic behaviour without the need to resolve the microscopic details.

  4. The wave-based substructuring approach for the efficient description of interface dynamics in substructuring

    NASA Astrophysics Data System (ADS)

    Donders, S.; Pluymers, B.; Ragnarsson, P.; Hadjit, R.; Desmet, W.

    2010-04-01

    In the vehicle design process, design decisions are more and more based on virtual prototypes. Due to competitive and regulatory pressure, vehicle manufacturers are forced to improve product quality, to reduce time-to-market and to launch an increasing number of design variants on the global market. To speed up the design iteration process, substructuring and component mode synthesis (CMS) methods are commonly used, involving the analysis of substructure models and the synthesis of the substructure analysis results. Substructuring and CMS enable efficient decentralized collaboration across departments and allow to benefit from the availability of parallel computing environments. However, traditional CMS methods become prohibitively inefficient when substructures are coupled along large interfaces, i.e. with a large number of degrees of freedom (DOFs) at the interface between substructures. The reason is that the analysis of substructures involves the calculation of a number of enrichment vectors, one for each interface degree of freedom (DOF). Since large interfaces are common in vehicles (e.g. the continuous line connections to connect the body with the windshield, roof or floor), this interface bottleneck poses a clear limitation in the vehicle noise, vibration and harshness (NVH) design process. Therefore there is a need to describe the interface dynamics more efficiently. This paper presents a wave-based substructuring (WBS) approach, which allows reducing the interface representation between substructures in an assembly by expressing the interface DOFs in terms of a limited set of basis functions ("waves"). As the number of basis functions can be much lower than the number of interface DOFs, this greatly facilitates the substructure analysis procedure and results in faster design predictions. The waves are calculated once from a full nominal assembly analysis, but these nominal waves can be re-used for the assembly of modified components. The WBS approach thus

  5. Modeling small-signal response of GaN-based metal-insulator-semiconductor high electron mobility transistor gate stack in spill-over regime: Effect of barrier resistance and interface states

    SciTech Connect

    Capriotti, M. E-mail: dionyz.pogany@tuwien.ac.at; Fleury, C.; Oposich, M.; Bethge, O.; Strasser, G.; Pogany, D. E-mail: dionyz.pogany@tuwien.ac.at; Lagger, P.; Ostermaier, C.

    2015-01-14

    We provide theoretical and simulation analysis of the small signal response of SiO{sub 2}/AlGaN/GaN metal insulator semiconductor (MIS) capacitors from depletion to spill over region, where the AlGaN/SiO{sub 2} interface is accumulated with free electrons. A lumped element model of the gate stack, including the response of traps at the III-N/dielectric interface, is proposed and represented in terms of equivalent parallel capacitance, C{sub p}, and conductance, G{sub p}. C{sub p} -voltage and G{sub p} -voltage dependences are modelled taking into account bias dependent AlGaN barrier dynamic resistance R{sub br} and the effective channel resistance. In particular, in the spill-over region, the drop of C{sub p} with the frequency increase can be explained even without taking into account the response of interface traps, solely by considering the intrinsic response of the gate stack (i.e., no trap effects) and the decrease of R{sub br} with the applied forward bias. Furthermore, we show the limitations of the conductance method for the evaluation of the density of interface traps, D{sub it}, from the G{sub p}/ω vs. angular frequency ω curves. A peak in G{sub p}/ω vs. ω occurs even without traps, merely due to the intrinsic frequency response of gate stack. Moreover, the amplitude of the G{sub p}/ω vs. ω peak saturates at high D{sub it}, which can lead to underestimation of D{sub it}. Understanding the complex interplay between the intrinsic gate stack response and the effect of interface traps is relevant for the development of normally on and normally off MIS high electron mobility transistors with stable threshold voltage.

  6. Reactive Transport Modeling and Changes in Porosity at Reactive Interfaces in a HLW repository in Clay

    NASA Astrophysics Data System (ADS)

    Samper, J.; Mon, A.; Montenegro, L.; Naves, A.; Fernández, J.

    2016-12-01

    High-level radioactive waste disposal in a deep geological repository is based on a multibarrier concept which combines natural barriers such as the geological formation and artificial barriers such as metallic containers, bentonite and concrete buffers and sealing materials. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyperalkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyperalkaline plume at the concrete-clay interface. Here we present a nonisothermal reactive transport model of the long-term interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. This problem involves large pH changes with a hyperalkaline high-pH plume, complex mineral dissolution/precipitation patterns, cation exchange reactions and proton surface complexation. These reactions lead to large changes in porosity which can even lead to pore clogging. Model results show that magnetite, the main corrosion product, precipitates and reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The zones affected by pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay interfaces at 1 Ma are equal to 10, 25 and 25 mm thick, respectively. The results of our simulations share many of the features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Narrow alteration zones; and 2) Pore clogging at the canister-bentonite, bentonite-concrete and concrete

  7. A library-based approach to portable, parallel, object-oriented programming: Interface, implementation, and application

    SciTech Connect

    Parkes, S.; Chandy, J.A.; Banerjee, P.

    1994-12-31

    The use of parallel platforms, despite increasing availability, remains largely restricted to well-structured, numeric applications. The authors address the issue of facilitating the use of parallel platforms on unstructured problems through object-oriented design techniques and the actor model of concurrent computation. They present a multi-level approach to expressing parallelism for unstructured applications: a high-level interface based on the actor model of concurrent object-oriented programming and a low-level interface which provides an object-oriented interface to system services across a wide range of parallel architectures. The high- and low-level interfaces are implemented as part of the ProperCAD II C++ class library which supports shared-memory, message-passing, and hybrid architectures. The authors demonstrate their approach through a detailed examination of the parallelization process for an existing unstructured serial application, a state-of-the-art VLSI computer-aided design application. They compare and contrast the library-based actor approach to other methods for expressing parallelism in C++ on a number of applications and kernels.

  8. Experimental study of the seismoelectric interface response in wedge and cavity models

    NASA Astrophysics Data System (ADS)

    Peng, Rong; Di, Bangrang; Wei, Jianxin; Ding, Pinbo; Zhao, Jianguo; Pan, Xiao; Liu, Zichun

    2017-09-01

    We have built an experimental device and performed seismoelectric physical modelling experiments on sandstone rock models with different geometries. Our aims are (1) to gain insight into the interface response behaviour of rock models with different geometry, (2) to illustrate the amplitude characteristics of the interface responses induced by incident waves and reflections of multiple interfaces and (3) to investigate the polarity reversal of the interface responses generated at different interfaces. For experimental preciseness, we conducted a series of control measurements on sandstone to confirm that we indeed measured the seismoelectric conversion, and gained insight on the influence of the surface wave coseismic signals and the P-wave coseismic signals. The seismoelectric results of wedge model verify that a thin layer structure can enhance the seismoelectric signal. The strength differences between the incident-wave-induced signals and the reflection-induced signals have significant effects on the interpretation of underground structures and interfaces. The incident-wave-induced signals at the lower interface may be neglected easily for its small amplitude, while the reflection-induced signals at the upper interface with a longer traveltime may be regarded as a new event of a lower interface for its large amplitude. Therefore, the depth of interfaces is likely to be misinterpreted. Our experiments show that the polarity reversal of interface responses is affected by receiver positions. For a given interface measured with electrodes at different depths in a borehole, seismoelectric interface responses recorded by electrodes on two sides of an interface have the opposite polarity. For multiple interfaces measured with one electrode, the polarity of the interface responses from the interfaces above the electrode reverses with that from the interfaces below the electrode. The variation characteristics of the polarity reversal can help to correct the polarity

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  11. Optics of an opal modeled with a stratified effective index and the effect of the interface

    NASA Astrophysics Data System (ADS)

    Maurin, Isabelle; Moufarej, Elias; Laliotis, Athanasios; Bloch, Daniel

    2015-08-01

    Reflection and transmission for an artificial opal are described through a model of stratified medium based upon a one-dimensional variation of an effective index. The model is notably applicable to a Langmuir-Blodgett type disordered opal. Light scattering is accounted for by a phenomenological absorption. The interface region between the opal and the substrate -or the vacuum- induces a periodicity break in the photonic crystal arrangement, which exhibits a prominent influence on the reflection, notably away from the Bragg reflection peak. Experimental results are compared to our model. The model is extendable to inverse opals, stacked cylinders, or irradiation by evanescent waves

  12. PyGSM: Python interface to the Global Sky Model

    NASA Astrophysics Data System (ADS)

    Price, Danny C.

    2016-03-01

    PyGSM is a Python interface for the Global Sky Model (GSM, ascl:1011.010). The GSM is a model of diffuse galactic radio emission, constructed from a variety of all-sky surveys spanning the radio band (e.g. Haslam and WMAP). PyGSM uses the GSM to generate all-sky maps in Healpix format of diffuse Galactic radio emission from 10 MHz to 94 GHz. The PyGSM module provides visualization utilities, file output in FITS format, and the ability to generate observed skies for a given location and date. PyGSM requires Healpy, PyEphem (ascl:1112.014), and AstroPy (ascl:1304.002).

  13. A possible model for understanding the personality--intelligence interface.

    PubMed

    Chamorro-Premuzic, Tomas; Furnham, Adrian

    2004-05-01

    Despite the recent increase in the number of studies examining empirical links between personality and intelligence (see Hofstee, 2001; Zeidner & Matthews, 2000), a theoretical integration of ability and nonability traits remains largely unaddressed. This paper presents a possible conceptual framework for understanding the personality-intelligence interface. In doing so, it conceptualizes three different levels of intelligence, namely, intellectual ability (which comprises both Gf and Gc), IQ test performance and subjectively assessed intelligence (a mediator between personality, intellectual ability and IQ test performance). Although the model draws heavily upon correlation evidence, each of its paths may be tested independently. The presented model may, therefore, be used to explore causation and further develop theoretical approaches to understanding the relation between ability and nonability traits underlying human performance.

  14. Interfacing MATLAB and Python Optimizers to Black-Box Environmental Simulation Models

    NASA Astrophysics Data System (ADS)

    Matott, L. S.; Leung, K.; Tolson, B.

    2009-12-01

    A common approach for utilizing environmental models in a management or policy-analysis context is to incorporate them into a simulation-optimization framework - where an underlying process-based environmental model is linked with an optimization search algorithm. The optimization search algorithm iteratively adjusts various model inputs (i.e. parameters or design variables) in order to minimize an application-specific objective function computed on the basis of model outputs (i.e. response variables). Numerous optimization algorithms have been applied to the simulation-optimization of environmental systems and this research investigated the use of optimization libraries and toolboxes that are readily available in MATLAB and Python - two popular high-level programming languages. Inspired by model-independent calibration codes (e.g. PEST and UCODE), a small piece of interface software (known as PIGEON) was developed. PIGEON allows users to interface Python and MATLAB optimizers with arbitrary black-box environmental models without writing any additional interface code. An initial set of benchmark tests (involving more than 20 MATLAB and Python optimization algorithms) were performed to validate the interface software - results highlight the need to carefully consider such issues as numerical precision in output files and enforcement (or not) of parameter limits. Additional benchmark testing considered the problem of fitting isotherm expressions to laboratory data - with an emphasis on dual-mode expressions combining non-linear isotherms with a linear partitioning component. With respect to the selected isotherm fitting problems, derivative-free search algorithms significantly outperformed gradient-based algorithms. Attempts to improve gradient-based performance, via parameter tuning and also via several alternative multi-start approaches, were largely unsuccessful.

  15. A computational model for stress reduction at the skin-implant interface of osseointegrated prostheses.

    PubMed

    Yerneni, Srinivasu; Dhaher, Yasin; Kuiken, Todd A

    2012-04-01

    Osseointegrated implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-implant interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-implant interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-implant interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-implant interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-implant interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.

  16. Voltage harmonic elimination with RLC based interface smoothing filter

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, K.; Ramachandaramurthy, V. K.

    2015-04-01

    A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.

  17. Interface localization in the 2D Ising model with a driven line

    NASA Astrophysics Data System (ADS)

    Cohen, O.; Mukamel, D.

    2016-04-01

    We study the effect of a one-dimensional driving field on the interface between two coexisting phases in a two dimensional model. This is done by considering an Ising model on a cylinder with Glauber dynamics in all sites and additional biased Kawasaki dynamics in the central ring. Based on the exact solution of the two-dimensional Ising model, we are able to compute the phase diagram of the driven model within a special limit of fast drive and slow spin flips in the central ring. The model is found to exhibit two phases where the interface is pinned to the central ring: one in which it fluctuates symmetrically around the central ring and another where it fluctuates asymmetrically. In addition, we find a phase where the interface is centered in the bulk of the system, either below or above the central ring of the cylinder. In the latter case, the symmetry breaking is ‘stronger’ than that found in equilibrium when considering a repulsive potential on the central ring. This equilibrium model is analyzed here by using a restricted solid-on-solid model.

  18. Brain-computer interface using water-based electrodes

    NASA Astrophysics Data System (ADS)

    Volosyak, Ivan; Valbuena, Diana; Malechka, Tatsiana; Peuscher, Jan; Gräser, Axel

    2010-12-01

    Current brain-computer interfaces (BCIs) that make use of EEG acquisition techniques require unpleasant electrode gel causing skin abrasion during the standard preparation procedure. Electrodes that require tap water instead of electrolytic electrode gel would make both daily setup and clean up much faster, easier and comfortable. This paper presents the results from ten subjects that controlled an SSVEP-based BCI speller system using two EEG sensor modalities: water-based and gel-based surface electrodes. Subjects performed in copy spelling mode using conventional gel-based electrodes and water-based electrodes with a mean information transfer rate (ITR) of 29.68 ± 14.088 bit min-1 and of 26.56 ± 9.224 bit min-1, respectively. A paired t-test failed to reveal significant differences in the information transfer rates and accuracies of using gel- or water-based electrodes for EEG acquisition. This promising result confirms the operational readiness of water-based electrodes for BCI applications.

  19. Modeling of tunneling current in ultrathin MOS structure with interface trap charge and fixed oxide charge

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Huang, Shi-Hua; Wu, Feng-Min

    2013-01-01

    A model based on analysis of the self-consistent Poisson—Schrodinger equation is proposed to investigate the tunneling current of electrons in the inversion layer of a p-type metal-oxide-semiconductor (MOS) structure. In this model, the influences of interface trap charge (ITC) at the Si—SiO2 interface and fixed oxide charge (FOC) in the oxide region are taken into account, and one-band effective mass approximation is used. The tunneling probability is obtained by employing the transfer matrix method. Further, the effects of in-plane momentum on the quantization in the electron motion perpendicular to the Si—SiO2 interface of a MOS device are investigated. Theoretical simulation results indicate that both ITC and FOC have great influence on the tunneling current through a MOS structure when their densities are larger than 1012 cm-2, which results from the great change of bound electrons near the Si—SiO2 interface and the oxide region. Therefore, for real ultrathin MOS structures with ITC and FOC, this model can give a more accurate description for the tunneling current in the inversion layer.

  20. Simple model for linear and nonlinear mixing at unstable fluid interfaces in spherical geometry

    SciTech Connect

    Ramshaw, J.D.

    1999-08-01

    A simple model was recently described for predicting linear and nonlinear mixing at an unstable planar fluid interface subjected to an arbitrary time-dependent variable acceleration history [J. D. Ramshaw, Phys. Rev. E {bold 58}, 5834 (1998)]. Here we present an analogous model for describing the mixing of two adjacent spherical fluid shells of different density resulting from an arbitrary time-dependent mean interface radius R(t). As in the planar case, the model is based on a heuristic expression for the kinetic energy of the system. This expression is based on that for the kinetic energy of a linearly perturbed interface, but with a dynamically renormalized effective wavelength which becomes proportional to the half-width a(t) of the mixing layer in the nonlinear regime. An equation of motion for s=R{sup 2}a is then derived from Lagrange{close_quote}s equations. This evolution equation properly reduces to Plesset{close_quote}s equation for small perturbations, and to the previous planar model in the limit of very large R. The conservation properties of the model are established, and a suitable numerical scheme which preserves these properties is proposed. {copyright} {ital 1999} {ital The American Physical Society}

  1. Mathematical modeling of dispersion in single interface flow analysis.

    PubMed

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

    2010-03-24

    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.

  2. Facilitating access to laboratory guidelines by modeling their contents and designing a computerized user interface.

    PubMed

    Yasini, Mobin; Duclos, Catherine; Lamy, Jean-Baptiste; Venot, Alain

    2011-01-01

    Laboratory tests are not always prescribed appropriately. Guidelines for some important laboratory tests have been developed by expert panels in the Parisian region to maximize the appropriateness of laboratory medicine. However; these recommendations are not frequently consulted by physicians and nurses. We developed a system facilitating consultation of these guidelines, to increase their usability. Elements of information contained in these documents were identified and included in recommendations of different categories. UML modeling was used to represent these categories and their relationships to each other in the guidelines. We used the generated model to implement a computerized interface. The prototype interface, based on web-based technology was found to be rapid and easy to use. By clicking on provided keywords, information about the subject sought is highlighted whilst retaining the entire text of the guideline on-screen.

  3. A model of blind zone for in situ monitoring the solid/liquid interface using ultrasonic wave.

    PubMed

    Peng, Song; Ouyang, Qi; Zhu, Z Z; Zhang, X L

    2015-07-01

    To in situ monitor a solid/liquid interface to control metal qualities, the paper analysis blind models of the ultrasonic propagation in the solidifying molten metal with a solid/liquid interface in the Bridgman type furnace, and a mathematical calculation model of blind zone with different source locations and surface concavities is built. The study points out that the blind zone I is caused by ray bending in the interface edge, and the blind zone II is caused by totally reflection which is related with initial ray angle, critical refraction angle of solid/liquid media. A serial of simulation experiments are operated on the base of the model, and numerical computation results coincide with model calculated results very well. Therefore, receiver should locate beyond these blind zones in the right boundary to obtain time of flight data which is used to reconstruct the solid/liquid interface.

  4. Bulk Expansion Effect of Gallium-Based Thermal Interface Material

    NASA Astrophysics Data System (ADS)

    Ding, Yujie; Deng, Zhongshan; Cai, Changli; Yang, Zejun; Yang, Yingbao; Lu, Jinrong; Gao, Yunxia; Liu, Jing

    2017-06-01

    The bulk expansion effect of gallium-based thermal interface materials (GBTIMs) was experimentally disclosed and clarified for the first time. GBTIMs were prepared under low (26 %) and high (96 %) relative humidity for a short (2 h) and long (5 h) time periods. An evident volume expansion phenomenon was observed with adequate humidity. Higher humidity resulted in bigger expansion rate and expansion coefficient. The expansion coefficient could reach surprisingly large value of 1.5 for GBTIMs under 96% relative humidity. Assuming that the volume change was related to chemical reactions in the mixture, SEM and XRD were adopted to determine the structure and phase components of the samples. The gases produced in the expansion process were detected with gas chromatography and a large amount of hydrogen was found. The results indicated that the hydrogen produced by the reaction between gallium oxide \\hbox {Ga}2\\hbox {O} and water in GBTIMs caused the expansion effect. The corroded GBTIMs were mainly composed of gallium oxide \\hbox {Ga}2\\hbox {O}3 and became loose and porous solids after expansion. Thermal conductivity decreased dramatically after the expansion process due to the composition and structure changes. From the view point of application, the ambient humidity and oxidation degree must be controlled during preparation of such thermal interface material to avoid its bulk expansion effect.

  5. Design of video interface conversion system based on FPGA

    NASA Astrophysics Data System (ADS)

    Zhao, Heng; Wang, Xiang-jun

    2014-11-01

    This paper presents a FPGA based video interface conversion system that enables the inter-conversion between digital and analog video. Cyclone IV series EP4CE22F17C chip from Altera Corporation is used as the main video processing chip, and single-chip is used as the information interaction control unit between FPGA and PC. The system is able to encode/decode messages from the PC. Technologies including video decoding/encoding circuits, bus communication protocol, data stream de-interleaving and de-interlacing, color space conversion and the Camera Link timing generator module of FPGA are introduced. The system converts Composite Video Broadcast Signal (CVBS) from the CCD camera into Low Voltage Differential Signaling (LVDS), which will be collected by the video processing unit with Camera Link interface. The processed video signals will then be inputted to system output board and displayed on the monitor.The current experiment shows that it can achieve high-quality video conversion with minimum board size.

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

    NASA Astrophysics Data System (ADS)

    Liu, Z.

    2007-12-01

    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

  7. A robust and flexible Geospatial Modeling Interface (GMI) for environmental model deployment and evaluation

    USDA-ARS?s Scientific Manuscript database

    This paper provides an overview of the GMI (Geospatial Modeling Interface) simulation framework for environmental model deployment and assessment. GMI currently provides access to multiple environmental models including AgroEcoSystem-Watershed (AgES-W), Nitrate Leaching and Economic Analysis 2 (NLEA...

  8. The significance of cognitive modeling in building healthcare interfaces.

    PubMed

    Johnson, Constance M; Turley, James P

    2006-02-01

    Although there are many reasons that widespread adoption of healthcare information systems has not transpired, one reason is a failure to take into account the cognitive needs of the users. To understand the cognitive needs of nurses and physicians and determine how these needs should influence the design of healthcare interfaces. A qualitative and quantitative study that compares how nurses and physicians comprehend patient information. Twenty-four registered nurses and twenty-four physicians working in the specialties of gastrointestinal or internal medicine. Each clinician reviewed two mock electronic medical records and summarized the cases using a think-aloud protocol. All verbalizations were coded for medical and conceptual information. The nurses included a larger mean proportion (p<0.001) of recalls than did the physicians. As compared to the nurses, the physicians included a statistically significant (p<0.001) larger mean proportion of inferences, conditional statements, and interventions. The nurses concentrated on functional problems, whereas the physicians focused on diagnosis, treatment, and management. The main cognitive differences between the physicians and the nurses are explained through the differences in their practice models. Therefore, healthcare IT must develop separate interfaces for each discipline to address their unique needs.

  9. Modeling and diagnosing interface mix in layered ICF implosions

    NASA Astrophysics Data System (ADS)

    Weber, C. R.; Berzak Hopkins, L. F.; Clark, D. S.; Haan, S. W.; Ho, D. D.; Meezan, N. B.; Milovich, J. L.; Robey, H. F.; Smalyuk, V. A.; Thomas, C. A.

    2015-11-01

    Mixing at the fuel-ablator interface of an inertial confinement fusion (ICF) implosion can arise from an unfavorable in-flight Atwood number between the cryogenic DT fuel and the ablator. High-Z dopant is typically added to the ablator to control the Atwood number, but recent high-density carbon (HDC) capsules have been shot at the National Ignition Facility (NIF) without this added dopant. Highly resolved post-shot modeling of these implosions shows that there was significant mixing of ablator material into the dense DT fuel. This mix lowers the fuel density and results in less overall compression, helping to explain the measured ratio of down scattered-to-primary neutrons. Future experimental designs will seek to improve this issue through adding dopant and changing the x-ray spectra with a different hohlraum wall material. To test these changes, we are designing an experimental platform to look at the growth of this mixing layer. This technique uses side-on radiography to measure the spatial extent of an embedded high-Z tracer layer near the interface. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  10. Growth/reflectance model interface for wheat and corresponding model

    NASA Technical Reports Server (NTRS)

    Suits, G. H.; Sieron, R.; Odenweller, J.

    1984-01-01

    The use of modeling to explore the possibility of discovering new and useful crop condition indicators which might be available from the Thematic Mapper and to connect these symptoms to the biological causes in the crop is discussed. A crop growth model was used to predict the day to day growth features of the crop as it responds biologically to the various environmental factors. A reflectance model was used to predict the character of the interaction of daylight with the predicted growth features. An atmospheric path radiance was added to the reflected daylight to simulate the radiance appearing at the sensor. Finally, the digitized data sent to a ground station were calculated. The crop under investigation is wheat.

  11. A Natural Language Interface Concordant with a Knowledge Base.

    PubMed

    Han, Yong-Jin; Park, Seong-Bae; Park, Se-Young

    2016-01-01

    The discordance between expressions interpretable by a natural language interface (NLI) system and those answerable by a knowledge base is a critical problem in the field of NLIs. In order to solve this discordance problem, this paper proposes a method to translate natural language questions into formal queries that can be generated from a graph-based knowledge base. The proposed method considers a subgraph of a knowledge base as a formal query. Thus, all formal queries corresponding to a concept or a predicate in the knowledge base can be generated prior to query time and all possible natural language expressions corresponding to each formal query can also be collected in advance. A natural language expression has a one-to-one mapping with a formal query. Hence, a natural language question is translated into a formal query by matching the question with the most appropriate natural language expression. If the confidence of this matching is not sufficiently high the proposed method rejects the question and does not answer it. Multipredicate queries are processed by regarding them as a set of collected expressions. The experimental results show that the proposed method thoroughly handles answerable questions from the knowledge base and rejects unanswerable ones effectively.

  12. A Natural Language Interface Concordant with a Knowledge Base

    PubMed Central

    Han, Yong-Jin; Park, Seong-Bae; Park, Se-Young

    2016-01-01

    The discordance between expressions interpretable by a natural language interface (NLI) system and those answerable by a knowledge base is a critical problem in the field of NLIs. In order to solve this discordance problem, this paper proposes a method to translate natural language questions into formal queries that can be generated from a graph-based knowledge base. The proposed method considers a subgraph of a knowledge base as a formal query. Thus, all formal queries corresponding to a concept or a predicate in the knowledge base can be generated prior to query time and all possible natural language expressions corresponding to each formal query can also be collected in advance. A natural language expression has a one-to-one mapping with a formal query. Hence, a natural language question is translated into a formal query by matching the question with the most appropriate natural language expression. If the confidence of this matching is not sufficiently high the proposed method rejects the question and does not answer it. Multipredicate queries are processed by regarding them as a set of collected expressions. The experimental results show that the proposed method thoroughly handles answerable questions from the knowledge base and rejects unanswerable ones effectively. PMID:26904105

  13. Towards the virtual artery: a multiscale model for vascular physiology at the physics–chemistry–biology interface

    PubMed Central

    Alowayyed, Saad; Lorenz, Eric; Melnikova, Natalia; Mountrakis, Lampros; van Rooij, Britt; Svitenkov, Andrew; Závodszky, Gábor; Zun, Pavel

    2016-01-01

    This discussion paper introduces the concept of the Virtual Artery as a multiscale model for arterial physiology and pathologies at the physics–chemistry–biology (PCB) interface. The cellular level is identified as the mesoscopic level, and we argue that by coupling cell-based models with other relevant models on the macro- and microscale, a versatile model of arterial health and disease can be composed. We review the necessary ingredients, both models of arteries at many different scales, as well as generic methods to compose multiscale models. Next, we discuss how this can be combined into the virtual artery. Finally, we argue that the concept of models at the PCB interface could or perhaps should become a powerful paradigm, not only as in our case for studying physiology, but also for many other systems that have such PCB interfaces. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’. PMID:27698036

  14. Detecting Nasal Vowels in Speech Interfaces Based on Surface Electromyography

    PubMed Central

    Freitas, João; Teixeira, António; Silva, Samuel; Oliveira, Catarina; Dias, Miguel Sales

    2015-01-01

    Nasality is a very important characteristic of several languages, European Portuguese being one of them. This paper addresses the challenge of nasality detection in surface electromyography (EMG) based speech interfaces. We explore the existence of useful information about the velum movement and also assess if muscles deeper down in the face and neck region can be measured using surface electrodes, and the best electrode location to do so. The procedure we adopted uses Real-Time Magnetic Resonance Imaging (RT-MRI), collected from a set of speakers, providing a method to interpret EMG data. By ensuring compatible data recording conditions, and proper time alignment between the EMG and the RT-MRI data, we are able to accurately estimate the time when the velum moves and the type of movement when a nasal vowel occurs. The combination of these two sources revealed interesting and distinct characteristics in the EMG signal when a nasal vowel is uttered, which motivated a classification experiment. Overall results of this experiment provide evidence that it is possible to detect velum movement using sensors positioned below the ear, between mastoid process and the mandible, in the upper neck region. In a frame-based classification scenario, error rates as low as 32.5% for all speakers and 23.4% for the best speaker have been achieved, for nasal vowel detection. This outcome stands as an encouraging result, fostering the grounds for deeper exploration of the proposed approach as a promising route to the development of an EMG-based speech interface for languages with strong nasal characteristics. PMID:26069968

  15. Detecting Nasal Vowels in Speech Interfaces Based on Surface Electromyography.

    PubMed

    Freitas, João; Teixeira, António; Silva, Samuel; Oliveira, Catarina; Dias, Miguel Sales

    2015-01-01

    Nasality is a very important characteristic of several languages, European Portuguese being one of them. This paper addresses the challenge of nasality detection in surface electromyography (EMG) based speech interfaces. We explore the existence of useful information about the velum movement and also assess if muscles deeper down in the face and neck region can be measured using surface electrodes, and the best electrode location to do so. The procedure we adopted uses Real-Time Magnetic Resonance Imaging (RT-MRI), collected from a set of speakers, providing a method to interpret EMG data. By ensuring compatible data recording conditions, and proper time alignment between the EMG and the RT-MRI data, we are able to accurately estimate the time when the velum moves and the type of movement when a nasal vowel occurs. The combination of these two sources revealed interesting and distinct characteristics in the EMG signal when a nasal vowel is uttered, which motivated a classification experiment. Overall results of this experiment provide evidence that it is possible to detect velum movement using sensors positioned below the ear, between mastoid process and the mandible, in the upper neck region. In a frame-based classification scenario, error rates as low as 32.5% for all speakers and 23.4% for the best speaker have been achieved, for nasal vowel detection. This outcome stands as an encouraging result, fostering the grounds for deeper exploration of the proposed approach as a promising route to the development of an EMG-based speech interface for languages with strong nasal characteristics.

  16. Modeling the Electrical Contact Resistance at Steel-Carbon Interfaces

    NASA Astrophysics Data System (ADS)

    Brimmo, Ayoola T.; Hassan, Mohamed I.

    2016-01-01

    In the aluminum smelting industry, electrical contact resistance at the stub-carbon (steel-carbon) interface has been recurrently reported to be of magnitudes that legitimately necessitate concern. Mitigating this via finite element modeling has been the focus of a number of investigations, with the pressure- and temperature-dependent contact resistance relation frequently cited as a factor that limits the accuracy of such models. In this study, pressure- and temperature-dependent relations are derived from the most extensively cited works that have experimentally characterized the electrical contact resistance at these contacts. These relations are applied in a validated thermo-electro-mechanical finite element model used to estimate the voltage drop across a steel-carbon laboratory setup. By comparing the models' estimate of the contact electrical resistance with experimental measurements, we deduce the applicability of the different relations over a range of temperatures. The ultimate goal of this study is to apply mathematical modeling in providing pressure- and temperature-dependent relations that best describe the steel-carbon electrical contact resistance and identify the best fit relation at specific thermodynamic conditions.

  17. Enhancement of galloping-based wind energy harvesting by synchronized switching interface circuits

    NASA Astrophysics Data System (ADS)

    Zhao, Liya; Liang, Junrui; Tang, Lihua; Yang, Yaowen; Liu, Haili

    2015-04-01

    Galloping phenomenon has attracted extensive research attention for small-scale wind energy harvesting. In the reported literature, the dynamics and harvested power of a galloping-based energy harvesting system are usually evaluated with a resistive AC load; these characteristics might shift when a practical harvesting interface circuit is connected for extracting useful DC power. In the family of piezoelectric energy harvesting interface circuits, synchronized switching harvesting on inductor (SSHI) has demonstrated its advantage for enhancing the harvested power from existing base vibrations. This paper investigates the harvesting capability of a galloping-based wind energy harvester using SSHI interfaces, with a focus on comparing the performances of Series SSHI (S-SSHI) and Parallel SSHI (P-SSHI) with that of a standard DC interface, in terms of power at various wind speeds. The prototyped galloping-based piezoelectric energy harvester (GPEH) comprises a piezoelectric cantilever attached with a square-sectioned bluff body made of foam. Equivalent circuit model (ECM) of the GPEH is established and system-level circuit simulations with SSHI and standard interfaces are performed and validated with wind tunnel tests. The benefits of SSHI compared to standard circuit become more significant when the wind speed gets higher; while SSHI circuits lose the benefits at small wind speeds. In both experiment and simulation, the superiority of P-SSHI is confirmed while S-SSHI demands further investigation. The power output is increased by 43.75% with P-SSHI compared to the standard circuit at a wind speed of 6m/s.

  18. Optimization-based interactive segmentation interface for multiregion problems.

    PubMed

    Baxter, John S H; Rajchl, Martin; Peters, Terry M; Chen, Elvis C S

    2016-04-01

    Interactive segmentation is becoming of increasing interest to the medical imaging community in that it combines the positive aspects of both manual and automated segmentation. However, general-purpose tools have been lacking in terms of segmenting multiple regions simultaneously with a high degree of coupling between groups of labels. Hierarchical max-flow segmentation has taken advantage of this coupling for individual applications, but until recently, these algorithms were constrained to a particular hierarchy and could not be considered general-purpose. In a generalized form, the hierarchy for any given segmentation problem is specified in run-time, allowing different hierarchies to be quickly explored. We present an interactive segmentation interface, which uses generalized hierarchical max-flow for optimization-based multiregion segmentation guided by user-defined seeds. Applications in cardiac and neonatal brain segmentation are given as example applications of its generality.

  19. Runwien: a text-based interface for the WIEN package

    NASA Astrophysics Data System (ADS)

    Otero de la Roza, A.; Luaña, Víctor

    2009-05-01

    A new text-based interface for WIEN2k, the full-potential linearized augmented plane-waves (FPLAPW) program, is presented. This code provides an easy to use, yet powerful way of generating arbitrarily large sets of calculations. Thus, properties over a potential energy surface and WIEN2k parameter exploration can be calculated using a simple input text file. This interface also provides new capabilities to the WIEN2k package, such as the calculation of elastic constants on hexagonal systems or the automatic gathering of relevant information. Additionally, runwien is modular, flexible and intuitive. Program summaryProgram title: runwien Catalogue identifier: AECM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AECM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL version 3 No. of lines in distributed program, including test data, etc.: 62 567 No. of bytes in distributed program, including test data, etc.: 610 973 Distribution format: tar.gz Programming language: gawk (with locale POSIX or similar) Computer: All running Unix, Linux Operating system: Unix, GNU/Linux Classification: 7.3 External routines: WIEN2k ( http://www.wien2k.at/), GAWK ( http://www.gnu.org/software/gawk/), rename by L. Wall, a Perl script which renames files, modified by R. Barker to check for the existence of target files, gnuplot ( http://www.gnuplot.info/) Subprograms used:Cat Id: ADSY_v1_0/AECB_v1_0, Title: GIBBS/CRITIC, Reference: CPC 158 (2004) 57/CPC 999 (2009) 999 Nature of problem: Creation of a text-based, batch-oriented interface for the WIEN2k package. Solution method: WIEN2k solves the Kohn-Sham equations of a solid using the FPLAPW formalism. Runwien interprets an input file containing the description of the geometry and structure of the solid and drives the execution of the WIEN2k programs. The input is simplified thanks to the default values of the WIEN2k parameters known to runwien. Additional

  20. Parallelization of a hydrological model using the message passing interface

    USGS Publications Warehouse

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

    2013-01-01

    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.

  1. Particles at fluid-fluid interfaces: A new Navier-Stokes-Cahn-Hilliard surface-phase-field-crystal model

    PubMed Central

    Aland, Sebastian; Lowengrub, John; Voigt, Axel

    2013-01-01

    Colloid particles that are partially wetted by two immiscible fluids can become confined to fluid-fluid interfaces. At sufficiently high volume fractions, the colloids may jam and the interface may crystallize. The fluids together with the interfacial colloids form an emulsion with interesting material properties and offer an important route to new soft materials. A promising approach to simulate these emulsions was presented in Aland et al. [Phys. Fluids 23, 062103 (2011)], where a Navier-Stokes-Cahn-Hilliard model for the macroscopic two-phase fluid system was combined with a surface phase-field-crystal model for the microscopic colloidal particles along the interface. Unfortunately this model leads to spurious velocities which require very fine spatial and temporal resolutions to accurately and stably simulate. In this paper we develop an improved Navier-Stokes-Cahn-Hilliard-surface phase-field-crystal model based on the principles of mass conservation and thermodynamic consistency. To validate our approach, we derive a sharp interface model and show agreement with the improved diffuse interface model. Using simple flow configurations, we show that the new model has much better properties and does not lead to spurious velocities. Finally, we demonstrate the solid-like behavior of the crystallized interface by simulating the fall of a solid ball through a colloid-laden multiphase fluid. PMID:23214691

  2. Particles at fluid-fluid interfaces: A new Navier-Stokes-Cahn-Hilliard surface- phase-field-crystal model.

    PubMed

    Aland, Sebastian; Lowengrub, John; Voigt, Axel

    2012-10-01

    Colloid particles that are partially wetted by two immiscible fluids can become confined to fluid-fluid interfaces. At sufficiently high volume fractions, the colloids may jam and the interface may crystallize. The fluids together with the interfacial colloids form an emulsion with interesting material properties and offer an important route to new soft materials. A promising approach to simulate these emulsions was presented in Aland et al. [Phys. Fluids 23, 062103 (2011)], where a Navier-Stokes-Cahn-Hilliard model for the macroscopic two-phase fluid system was combined with a surface phase-field-crystal model for the microscopic colloidal particles along the interface. Unfortunately this model leads to spurious velocities which require very fine spatial and temporal resolutions to accurately and stably simulate. In this paper we develop an improved Navier-Stokes-Cahn-Hilliard-surface phase-field-crystal model based on the principles of mass conservation and thermodynamic consistency. To validate our approach, we derive a sharp interface model and show agreement with the improved diffuse interface model. Using simple flow configurations, we show that the new model has much better properties and does not lead to spurious velocities. Finally, we demonstrate the solid-like behavior of the crystallized interface by simulating the fall of a solid ball through a colloid-laden multiphase fluid.

  3. Analytical model for Transient Current Technique (TCT) signal prediction and analysis for thin interface characterization

    NASA Astrophysics Data System (ADS)

    Bronuzzi, J.; Mapelli, A.; Sallese, J. M.

    2016-12-01

    A silicon wafer bonding technique has been recently proposed for the fabrication of monolithic silicon radiation detectors. This new process would enable direct bonding of a read-out electronic chip wafer on a highly resistive silicon substrate wafer. Therefore, monolithic silicon detectors could be fabricated in this way which would allow the free choice of electronic chips and high resistive silicon bulk, even from different providers. Moreover, a monolithic detector with a high resistive bulk would also be available. Electrical properties of the bonded interface are then critical for this application. Indeed, mobile charges generated by radiation inside the bonded bulk are expected to transit through the interface to be collected by the read-out electronics. In order to characterize this interface, the concept of Transient Current Technique (TCT) has been explored by means of numerical simulations combined with a physics based analytical model. In this work, the analytical model giving insight into the physics behind the TCT dependence upon interface traps is validated using both TCAD simulations and experimental measurements.

  4. Formulation of consumables management models: Mission planning processor payload interface definition

    NASA Technical Reports Server (NTRS)

    Torian, J. G.

    1977-01-01

    Consumables models required for the mission planning and scheduling function are formulated. The relation of the models to prelaunch, onboard, ground support, and postmission functions for the space transportation systems is established. Analytical models consisting of an orbiter planning processor with consumables data base is developed. A method of recognizing potential constraint violations in both the planning and flight operations functions, and a flight data file storage/retrieval of information over an extended period which interfaces with a flight operations processor for monitoring of the actual flights is presented.

  5. Characterizing and Modeling Brittle Bi-material Interfaces Subjected to Shear

    NASA Astrophysics Data System (ADS)

    Anyfantis, Konstantinos N.; Berggreen, Christian

    2014-12-01

    This work is based on the investigation, both experimentally and numerically, of the Mode II fracture process and bond strength of bondlines formed in co-cured composite/metal joints. To this end, GFRP-to-steel double strap joints were tested in tension, so that the bi-material interface was subjected to shear with debonding occurring under Mode II conditions. The study of the debonding process and thus failure of the joints was based both on stress and energy considerations. Analytical formulas were utilized for the derivation of the respective shear strength and fracture toughness measures which characterize the bi-material interface, by considering the joint's failure load, geometry and involved materials. The derived stress and toughness magnitudes were further utilized as the parameters of an extrinsic cohesive law, applied in connection with the modeling the bi-material interface in a finite element simulation environment. It was concluded that interfacial fracture in the considered joints was driven by the fracture toughness and not by strength considerations, and that LEFM is well suited to analyze the failure of the joint. Additionally, the double strap joint geometry was identified and utilized as a characterization test for measuring the Mode II fracture toughness of brittle bi-material interfaces.

  6. An MEG-based Brain-Computer Interface (BCI)

    PubMed Central

    Mellinger, Jürgen; Schalk, Gerwin; Braun, Christoph; Preissl, Hubert; Rosenstiel, Wolfgang; Birbaumer, Niels; Kübler, Andrea

    2007-01-01

    Brain-Computer Interfaces (BCIs) allow for communicating intentions by mere brain activity, not involving muscles. Thus, BCIs may offer patients who have lost all voluntary muscle control the only possible way to communicate. Many recent studies have demonstrated that BCIs based on electroencephalography (EEG) can allow healthy and severely paralyzed individuals to communicate. While this approach is safe and inexpensive, communication is slow. Magnetoencephalography (MEG) provides signals with higher spatiotemporal resolution than EEG, and could thus be used to explore whether these improved signal properties translate into increased BCI communication speed. In this study, we investigated the utility of an MEG-based BCI that uses voluntary amplitude modulation of sensorimotor μ and β rhythms. To increase the signal-to-noise ratio, we present a simple spatial filtering method that takes the geometric properties of signal propagation in MEG into account, and we present methods that can process artifacts specifically encountered in an MEG-based BCI. Exemplarily, six participants were successfully trained to communicate binary decisions by imagery of limb movements using a feedback paradigm. Participants achieved significant μ-rhythm self control within 32 minutes of feedback training. For a subgroup of three participants, we localized the origin of the amplitude modulated signal to the motor cortex. Our results suggest that an MEG-based BCI is feasible and efficient in terms of user training. PMID:17475511

  7. Study of interface barrier of SiNx/GaN interface for nitrogen-polar GaN based high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Nidhi, Rajan, Siddharth; Keller, Stacia; Wu, Feng; DenBaars, Steven P.; Speck, James S.; Mishra, Umesh K.

    2008-06-01

    The SiNx/GaN interface barrier height for N-polar GaN based metal-insulator-semiconductor high electron mobility transistors (MISHEMTs) was investigated. N-polar SiNx/GaN/AlGaN/GaN MISHEMT structures with different GaN cap thicknesses were grown by metal-organic chemical vapor deposition. The properties of the SiNx/GaN interface are of critical importance to device operation and modeling in these devices. An analytical expression for the pinch-off voltage of the HEMT was obtained, and capacitance-voltage (C-V) measurements with different Schottky metals were used to extract the barrier height. The Fermi level at the interface was found to be pinned at approximately 1 eV with respect to GaN conduction band edge, irrespective of the work function of the gate metal. Hall measurements of the two-dimensional electron gas density were found to corroborate the predicted interface barrier height. An approximate value for interface charge causing this pinning was calculated to be 4.5×1012 cm-2.

  8. JAIL: a structure-based interface library for macromolecules.

    PubMed

    Günther, Stefan; von Eichborn, Joachim; May, Patrick; Preissner, Robert

    2009-01-01

    The increasing number of solved macromolecules provides a solid number of 3D interfaces, if all types of molecular contacts are being considered. JAIL annotates three different kinds of macromolecular interfaces, those between interacting protein domains, interfaces of different protein chains and interfaces between proteins and nucleic acids. This results in a total number of about 184,000 database entries. All the interfaces can easily be identified by a detailed search form or by a hierarchical tree that describes the protein domain architectures classified by the SCOP database. Visual inspection of the interfaces is possible via an interactive protein viewer. Furthermore, large scale analyses are supported by an implemented sequential and by a structural clustering. Similar interfaces as well as non-redundant interfaces can be easily picked out. Additionally, the sequential conservation of binding sites was also included in the database and is retrievable via Jmol. A comprehensive download section allows the composition of representative data sets with user defined parameters. The huge data set in combination with various search options allow a comprehensive view on all interfaces between macromolecules included in the Protein Data Bank (PDB). The download of the data sets supports numerous further investigations in macromolecular recognition. JAIL is publicly available at http://bioinformatics.charite.de/jail.

  9. A user interface for the Kansas Geological Survey slug test model.

    PubMed

    Esling, Steven P; Keller, John E

    2009-01-01

    The Kansas Geological Survey (KGS) developed a semianalytical solution for slug tests that incorporates the effects of partial penetration, anisotropy, and the presence of variable conductivity well skins. The solution can simulate either confined or unconfined conditions. The original model, written in FORTRAN, has a text-based interface with rigid input requirements and limited output options. We re-created the main routine for the KGS model as a Visual Basic macro that runs in most versions of Microsoft Excel and built a simple-to-use Excel spreadsheet interface that automatically displays the graphical results of the test. A comparison of the output from the original FORTRAN code to that of the new Excel spreadsheet version for three cases produced identical results.

  10. Reduction of nonlinear embedded boundary models for problems with evolving interfaces

    NASA Astrophysics Data System (ADS)

    Balajewicz, Maciej; Farhat, Charbel

    2014-10-01

    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.

  11. Modeling and dynamic simulation of ultraviolet induced growing interfaces

    NASA Astrophysics Data System (ADS)

    Flicstein, J.; Guillonneau, E.; Pata, S.; Kee Chun, L. S.; Palmier, J. F.; Daguet, C.; Courant, J. L.

    1999-01-01

    A solid-on-solid (SOS) model to simulate SiN:H dynamic surface characteristics in ultraviolet chemical vapor deposition (CVD) onto indium phosphide is presented. It is recognized that the nucleation process occurs at an UV induced active charged center on the surface of the substrate. Photolysis rates are determined using bond dissociation energies for molecular processes to generate active adsorbed species. The microscopic activation energy in elementary processes depends on the configuration of neighbouring atoms. Monte Carlo-Metropolis method using microscopic activation energy barriers is taken into account in molecular processes by a three-dimensional algorithm. The model includes lattice coordination and atom-atom interactions out to third-nearest neighbours. The molecular events are chosen with a probability of occurrence that depends on the kinetic rates at each atomic site. Stable incorporation of main species is enabled. Three-dimensional simulation of a growing interface indicates validation of a thermally activated rough-smooth transition for submicronic thick layers in the Kardar-Parisi-Zhang model.

  12. GRAPHICAL USER INTERFACE WITH APPLICATIONS IN SUSCEPTIBLE-INFECTIOUS-SUSCEPTIBLE MODELS.

    PubMed

    Ilea, M; Turnea, M; Arotăriţei, D; Rotariu, Mariana; Popescu, Marilena

    2015-01-01

    Practical significance of understanding the dynamics and evolution of infectious diseases increases continuously in contemporary world. The mathematical study of the dynamics of infectious diseases has a long history. By incorporating statistical methods and computer-based simulations in dynamic epidemiological models, it could be possible for modeling methods and theoretical analyses to be more realistic and reliable, allowing a more detailed understanding of the rules governing epidemic spreading. To provide the basis for a disease transmission, the population of a region is often divided into various compartments, and the model governing their relation is called the compartmental model. To present all of the information available, a graphical user interface provides icons and visual indicators. The graphical interface shown in this paper is performed using the MATLAB software ver. 7.6.0. MATLAB software offers a wide range of techniques by which data can be displayed graphically. The process of data viewing involves a series of operations. To achieve it, I had to make three separate files, one for defining the mathematical model and two for the interface itself. Considering a fixed population, it is observed that the number of susceptible individuals diminishes along with an increase in the number of infectious individuals so that in about ten days the number of individuals infected and susceptible, respectively, has the same value. If the epidemic is not controlled, it will continue for an indefinite period of time. By changing the global parameters specific of the SIS model, a more rapid increase of infectious individuals is noted. Using the graphical user interface shown in this paper helps achieving a much easier interaction with the computer, simplifying the structure of complex instructions by using icons and menus, and, in particular, programs and files are much easier to organize. Some numerical simulations have been presented to illustrate theoretical

  13. Electrode-electrolyte interface model of tripolar concentric ring electrode and electrode paste.

    PubMed

    Nasrollaholhosseini, Seyed Hadi; Steele, Preston; Besio, Walter G

    2016-08-01

    Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper we develop a model for the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

  14. An SPH model for multiphase flows with complex interfaces and large density differences

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Zong, Z.; Liu, M. B.; Zou, L.; Li, H. T.; Shu, C.

    2015-02-01

    In this paper, an improved SPH model for multiphase flows with complex interfaces and large density differences is developed. The multiphase SPH model is based on the assumption of pressure continuity over the interfaces and avoids directly using the information of neighboring particles' densities or masses in solving governing equations. In order to improve computational accuracy and to obtain smooth pressure fields, a corrected density re-initialization is applied. A coupled dynamic solid boundary treatment (SBT) is implemented both to reduce numerical oscillations and to prevent unphysical particle penetration in the boundary area. The density correction and coupled dynamics SBT algorithms are modified to adapt to the density discontinuity on fluid interfaces in multiphase simulation. A cut-off value of the particle density is set to avoid negative pressure, which can lead to severe numerical difficulties and may even terminate the simulations. Three representative numerical examples, including a Rayleigh-Taylor instability test, a non-Boussinesq problem and a dam breaking simulation, are presented and compared with analytical results or experimental data. It is demonstrated that the present SPH model is capable of modeling complex multiphase flows with large interfacial deformations and density ratios.

  15. Graphical User Interface for Simulink Integrated Performance Analysis Model

    NASA Technical Reports Server (NTRS)

    Durham, R. Caitlyn

    2009-01-01

    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.

  16. Does screw-bone interface modelling matter in finite element analyses?

    PubMed

    MacLeod, Alisdair R; Pankaj, Pankaj; Simpson, A Hamish R W

    2012-06-01

    The effect of screw-bone interface modelling strategies was evaluated in the setting of a tibial mid-shaft fracture stabilised using locking plates. Three interface models were examined: fully bonded interface; screw with sliding contact with bone; and screw with sliding contact with bone in an undersized pilot hole. For the simulation of the last interface condition we used a novel thermal expansion approach to generate the pre-stress that the bone would be exposed to during screw insertion. The study finds that the global load-deformation response is not influenced by the interface modelling approach employed; the deformation varied by less than 1% between different interaction models. However, interface modelling is found to have a considerable impact on the local stress-strain environment within the bone in the vicinity of the screws. Frictional and tied representations did not have significantly different peak strain values (<5% difference); the frictional interface had higher peak compressive strains while the tied interface had higher tensile strains. The undersized pilot hole simulation produced the largest strains. The peak minimum principal strains for the frictional interface were 26% of those for the undersized pilot hole simulation at a load of 770 N. It is concluded that the commonly used tie constraint can be used effectively when the only interest is the global load-deformation behaviour. Different contact interface models, however, alter the mechanical response around screw holes leading to different predictions for screw loosening, bone damage and stress shielding.

  17. Haptic Interfaces: Getting in Touch with Web-based Learning.

    ERIC Educational Resources Information Center

    Bussell, Linda

    2001-01-01

    Explains haptic computer interfaces for Web sites that relay touch-sensory feedback to the user. Discusses the importance of touch to cognition and learning; whether haptics can improve performance and learning; haptic interfaces for accessibility for blind and physically impaired users; comparisons of haptic devices; barriers to implementation;…

  18. Challenges in Modeling of the Plasma-Material Interface

    NASA Astrophysics Data System (ADS)

    Krstic, Predrag; Meyer, Fred; Allain, Jean Paul

    2013-09-01

    Plasma-Material Interface mixes materials of the two worlds, creating a new entity, a dynamical surface, which communicates between the two and represent one of the most challenging areas of multidisciplinary science, with many fundamental processes and synergies. How to build an integrated theoretical-experimental approach? Without mutual validation of experiment and theory chances very slim to have believable results? The outreach of the PMI science modeling at the fusion plasma facilities is illustrated by the significant step forward in understanding achieved recently by the quantum-classical modeling of the lithiated carbon surfaces irradiated by deuterium, showing surprisingly large role of oxygen in the deuterium retention and erosion chemistry. The plasma-facing walls of the next-generation fusion reactors will be exposed to high fluxes of neutrons and plasma-particles and will operate at high temperatures for thermodynamic efficiency. To this end we have been studying the evolution dynamics of vacancies and interstitials to the saturated dpa doses of tungsten surfaces bombarded by self-atoms, as well as the plasma-surface interactions of the damaged surfaces (erosion, hydrogen and helium uptake and fuzz formation). PSK and FWM acknowledge support of the ORNL LDRD program.

  19. Driven Interfaces: From Flow to Creep Through Model Reduction

    NASA Astrophysics Data System (ADS)

    Agoritsas, Elisabeth; García-García, Reinaldo; Lecomte, Vivien; Truskinovsky, Lev; Vandembroucq, Damien

    2016-09-01

    The response of spatially extended systems to a force leading their steady state out of equilibrium is strongly affected by the presence of disorder. We focus on the mean velocity induced by a constant force applied on one-dimensional interfaces. In the absence of disorder, the velocity is linear in the force. In the presence of disorder, it is widely admitted, as well as experimentally and numerically verified, that the velocity presents a stretched exponential dependence in the force (the so-called `creep law'), which is out of reach of linear response, or more generically of direct perturbative expansions at small force. In dimension one, there is no exact analytical derivation of such a law, even from a theoretical physical point of view. We propose an effective model with two degrees of freedom, constructed from the full spatially extended model, that captures many aspects of the creep phenomenology. It provides a justification of the creep law form of the velocity-force characteristics, in a quasistatic approximation. It allows, moreover, to capture the non-trivial effects of short-range correlations in the disorder, which govern the low-temperature asymptotics. It enables us to establish a phase diagram where the creep law manifests itself in the vicinity of the origin in the force-system-size-temperature coordinates. Conjointly, we characterise the crossover between the creep regime and a linear-response regime that arises due to finite system size.

  20. Designing and application of SAN extension interface based on CWDM

    NASA Astrophysics Data System (ADS)

    Qin, Leihua; Yu, Shengsheng; Zhou, Jingli

    2005-11-01

    As Fibre Channel (FC) becomes the protocol of choice within corporate data centers, enterprises are increasingly deploying SANs in their data central. In order to mitigate the risk of losing data and improve the availability of data, more and more enterprises are increasingly adopting storage extension technologies to replicate their business critical data to a secondary site. Transmitting this information over distance requires a carrier grade environment with zero data loss, scalable throughput, low jitter, high security and ability to travel long distance. To address this business requirements, there are three basic architectures for storage extension, they are Storage over Internet Protocol, Storage over Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Storage over Dense Wavelength Division Multiplexing (DWDM). Each approach varies in functionality, complexity, cost, scalability, security, availability , predictable behavior (bandwidth, jitter, latency) and multiple carrier limitations. Compared with these connectiviy technologies,Coarse Wavelength Division Multiplexing (CWDM) is a Simplified, Low Cost and High Performance connectivity solutions for enterprises to deploy their storage extension. In this paper, we design a storage extension connectivity over CWDM and test it's electrical characteristic and random read and write performance of disk array through the CWDM connectivity, testing result show us that the performance of the connectivity over CWDM is acceptable. Furthermore, we propose three kinds of network architecture of SAN extension based on CWDM interface. Finally the credit-Based flow control mechanism of FC, and the relationship between credits and extension distance is analyzed.

  1. Modeling Geometry and Progressive Failure of Material Interfaces in Plain Weave Composites

    NASA Technical Reports Server (NTRS)

    Hsu, Su-Yuen; Cheng, Ron-Bin

    2010-01-01

    A procedure combining a geometrically nonlinear, explicit-dynamics contact analysis, computer aided design techniques, and elasticity-based mesh adjustment is proposed to efficiently generate realistic finite element models for meso-mechanical analysis of progressive failure in textile composites. In the procedure, the geometry of fiber tows is obtained by imposing a fictitious expansion on the tows. Meshes resulting from the procedure are conformal with the computed tow-tow and tow-matrix interfaces but are incongruent at the interfaces. The mesh interfaces are treated as cohesive contact surfaces not only to resolve the incongruence but also to simulate progressive failure. The method is employed to simulate debonding at the material interfaces in a ceramic-matrix plain weave composite with matrix porosity and in a polymeric matrix plain weave composite without matrix porosity, both subject to uniaxial cyclic loading. The numerical results indicate progression of the interfacial damage during every loading and reverse loading event in a constant strain amplitude cyclic process. However, the composites show different patterns of damage advancement.

  2. Interfacing Cultured Neurons to Microtransducers Arrays: A Review of the Neuro-Electronic Junction Models.

    PubMed

    Massobrio, Paolo; Massobrio, Giuseppe; Martinoia, Sergio

    2016-01-01

    Microtransducer arrays, both metal microelectrodes and silicon-based devices, are widely used as neural interfaces to measure, extracellularly, the electrophysiological activity of excitable cells. Starting from the pioneering works at the beginning of the 70's, improvements in manufacture methods, materials, and geometrical shape have been made. Nowadays, these devices are routinely used in different experimental conditions (both in vivo and in vitro), and for several applications ranging from basic research in neuroscience to more biomedical oriented applications. However, the use of these micro-devices deeply depends on the nature of the interface (coupling) between the cell membrane and the sensitive active surface of the microtransducer. Thus, many efforts have been oriented to improve coupling conditions. Particularly, in the latest years, two innovations related to the use of carbon nanotubes as interface material and to the development of micro-structures which can be engulfed by the cell membrane have been proposed. In this work, we review what can be simulated by using simple circuital models and what happens at the interface between the sensitive active surface of the microtransducer and the neuronal membrane of in vitro neurons. We finally focus our attention on these two novel technological solutions capable to improve the coupling between neuron and micro-nano transducer.

  3. Interfacing Cultured Neurons to Microtransducers Arrays: A Review of the Neuro-Electronic Junction Models

    PubMed Central

    Massobrio, Paolo; Massobrio, Giuseppe; Martinoia, Sergio

    2016-01-01

    Microtransducer arrays, both metal microelectrodes and silicon-based devices, are widely used as neural interfaces to measure, extracellularly, the electrophysiological activity of excitable cells. Starting from the pioneering works at the beginning of the 70's, improvements in manufacture methods, materials, and geometrical shape have been made. Nowadays, these devices are routinely used in different experimental conditions (both in vivo and in vitro), and for several applications ranging from basic research in neuroscience to more biomedical oriented applications. However, the use of these micro-devices deeply depends on the nature of the interface (coupling) between the cell membrane and the sensitive active surface of the microtransducer. Thus, many efforts have been oriented to improve coupling conditions. Particularly, in the latest years, two innovations related to the use of carbon nanotubes as interface material and to the development of micro-structures which can be engulfed by the cell membrane have been proposed. In this work, we review what can be simulated by using simple circuital models and what happens at the interface between the sensitive active surface of the microtransducer and the neuronal membrane of in vitro neurons. We finally focus our attention on these two novel technological solutions capable to improve the coupling between neuron and micro-nano transducer. PMID:27445657

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

    PubMed Central

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

    2010-01-01

    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

  5. Modelling the inhomogeneous SiC Schottky interface

    NASA Astrophysics Data System (ADS)

    Gammon, P. M.; Pérez-Tomás, A.; Shah, V. A.; Vavasour, O.; Donchev, E.; Pang, J. S.; Myronov, M.; Fisher, C. A.; Jennings, M. R.; Leadley, D. R.; Mawby, P. A.

    2013-12-01

    For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n < 1.01) that suggest that these diodes may be homogeneous. However, at cryogenic temperatures, excessively high (n > 8), voltage dependent ideality factors and evidence of the so-called "thermionic field emission effect" within a T0-plot, suggest significant inhomogeneity. Two models are used, each derived from Tung's original interactive parallel conduction treatment of barrier height inhomogeneity that can reproduce these commonly seen effects in single temperature I-V traces. The first model incorporates patch pinch-off effects and produces accurate and reliable fits above around 150 K, and at current densities lower than 10-5 A cm-2. Outside this region, we show that resistive effects within a given patch are responsible for the excessive ideality factors, and a second simplified model incorporating these resistive effects as well as pinch-off accurately reproduces the entire temperature range. Analysis of these fitting parameters reduces confidence in those fits above 230 K, and questions are raised about the physical interpretation of the fitting parameters. Despite this, both methods used are shown to be useful tools for accurately reproducing I-V-T data over a large temperature range.

  6. Interfacing comprehensive rotorcraft analysis with advanced aeromechanics and vortex wake models

    NASA Astrophysics Data System (ADS)

    Liu, Haiying

    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

  7. Interfacing MHD Single Fluid and Kinetic Exospheric Solar Wind Models and Comparing Their Energetics

    NASA Astrophysics Data System (ADS)

    Moschou, Sofia-Paraskevi; Pierrard, Viviane; Keppens, Rony; Pomoell, Jens

    2017-09-01

    An exospheric kinetic solar wind model is interfaced with an observation-driven single-fluid magnetohydrodynamic (MHD) model. Initially, a photospheric magnetogram serves as observational input in the fluid approach to extrapolate the heliospheric magnetic field. Then semi-empirical coronal models are used for estimating the plasma characteristics up to a heliocentric distance of 0.1 AU. From there on, a full MHD model that computes the three-dimensional time-dependent evolution of the solar wind macroscopic variables up to the orbit of Earth is used. After interfacing the density and velocity at the inner MHD boundary, we compare our results with those of a kinetic exospheric solar wind model based on the assumption of Maxwell and Kappa velocity distribution functions for protons and electrons, respectively, as well as with in situ observations at 1 AU. This provides insight into more physically detailed processes, such as coronal heating and solar wind acceleration, which naturally arise from including suprathermal electrons in the model. We are interested in the profile of the solar wind speed and density at 1 AU, in characterizing the slow and fast source regions of the wind, and in comparing MHD with exospheric models in similar conditions. We calculate the energetics of both models from low to high heliocentric distances.

  8. Modeling growth, coalescence, and stability of helium precipitates on patterned interfaces

    NASA Astrophysics Data System (ADS)

    Yuryev, D. V.; Demkowicz, M. J.

    2017-01-01

    We develop a phase field simulation to model morphology evolution of helium (He) precipitates on solid-state interfaces. Our approach accounts for differences in precipitate contact angles arising from location-dependent interface energies and is capable of describing precipitate growth, coalescence, and de-wetting from the interface. We demonstrate our approach for interfaces with linear chains of wettable patches and find that different wetting energies and patch spacings give rise to four distinct classes of helium precipitate morphologies. Our method may be adapted to other scenarios involving fluids precipitating on non-uniform solid-state interfaces as well as to precipitation on patterned surfaces.

  9. An alternative accident prediction model for highway-rail interfaces.

    PubMed

    Austin, Ross D; Carson, Jodi L

    2002-01-01

    Safety levels at highway/rail interfaces continue to be of major concern despite an ever-increasing focus on improved design and appurtenance application practices. Despite the encouraging trend towards improved safety, accident frequencies remain high, many of which result in fatalities. More than half of these accidents occur at public crossings, where active warning devices (i.e. gates, lights, bells, etc.) are in place and functioning properly. This phenomenon speaks directly to the need to re-examine both safety evaluation (i.e. accident prediction) methods and design practices at highway-rail crossings. With respect to earlier developed accident prediction methods, the Peabody Dimmick Formula, the New Hampshire Index and the National Cooperative Highway Research Program (NCHRP) Hazard Index, all lack descriptive capabilities due to their limited number of explanatory variables. Further, each has unique limitations that are detailed in this paper. The US Department of Transportation's (USDOT) Accident Prediction Formula, which is most widely, also has limitations related to the complexity of the three-stage formula and its decline in accident prediction model accuracy over time. This investigation resulted in the development of an alternate highway-rail crossing accident prediction model, using negative binomial regression that shows great promise. The benefit to be gained through the application of this alternate model is (1) a greatly simplified, one-step estimation process; (2) comparable supporting data requirements and (3) interpretation of both the magnitude and direction of the effect of the factors found to significantly influence highway-rail crossing accident frequencies.

  10. Comparison of Joint Modeling Approaches Including Eulerian Sliding Interfaces

    SciTech Connect

    Lomov, I; Antoun, T; Vorobiev, O

    2009-12-16

    Accurate representation of discontinuities such as joints and faults is a key ingredient for high fidelity modeling of shock propagation in geologic media. The following study was done to improve treatment of discontinuities (joints) in the Eulerian hydrocode GEODYN (Lomov and Liu 2005). Lagrangian methods with conforming meshes and explicit inclusion of joints in the geologic model are well suited for such an analysis. Unfortunately, current meshing tools are unable to automatically generate adequate hexahedral meshes for large numbers of irregular polyhedra. Another concern is that joint stiffness in such explicit computations requires significantly reduced time steps, with negative implications for both the efficiency and quality of the numerical solution. An alternative approach is to use non-conforming meshes and embed joint information into regular computational elements. However, once slip displacement on the joints become comparable to the zone size, Lagrangian (even non-conforming) meshes could suffer from tangling and decreased time step problems. The use of non-conforming meshes in an Eulerian solver may alleviate these difficulties and provide a viable numerical approach for modeling the effects of faults on the dynamic response of geologic materials. We studied shock propagation in jointed/faulted media using a Lagrangian and two Eulerian approaches. To investigate the accuracy of this joint treatment the GEODYN calculations have been compared with results from the Lagrangian code GEODYN-L which uses an explicit treatment of joints via common plane contact. We explore two approaches to joint treatment in the code, one for joints with finite thickness and the other for tight joints. In all cases the sliding interfaces are tracked explicitly without homogenization or blending the joint and block response into an average response. In general, rock joints will introduce an increase in normal compliance in addition to a reduction in shear strength. In the

  11. Adaptively deformed mesh based interface method for elliptic equations with discontinuous coefficients

    PubMed Central

    Xia, Kelin; Zhan, Meng; Wan, Decheng; Wei, Guo-Wei

    2011-01-01

    Mesh deformation methods are a versatile strategy for solving partial differential equations (PDEs) with a vast variety of practical applications. However, these methods break down for elliptic PDEs with discontinuous coefficients, namely, elliptic interface problems. For this class of problems, the additional interface jump conditions are required to maintain the well-posedness of the governing equation. Consequently, in order to achieve high accuracy and high order convergence, additional numerical algorithms are required to enforce the interface jump conditions in solving elliptic interface problems. The present work introduces an interface technique based adaptively deformed mesh strategy for resolving elliptic interface problems. We take the advantages of the high accuracy, flexibility and robustness of the matched interface and boundary (MIB) method to construct an adaptively deformed mesh based interface method for elliptic equations with discontinuous coefficients. The proposed method generates deformed meshes in the physical domain and solves the transformed governed equations in the computational domain, which maintains regular Cartesian meshes. The mesh deformation is realized by a mesh transformation PDE, which controls the mesh redistribution by a source term. The source term consists of a monitor function, which builds in mesh contraction rules. Both interface geometry based deformed meshes and solution gradient based deformed meshes are constructed to reduce the L∞ and L2 errors in solving elliptic interface problems. The proposed adaptively deformed mesh based interface method is extensively validated by many numerical experiments. Numerical results indicate that the adaptively deformed mesh based interface method outperforms the original MIB method for dealing with elliptic interface problems. PMID:22586356

  12. A Wireless sEMG-Based Body-Machine Interface for Assistive Technology Devices.

    PubMed

    Fall, Cheikh Latyr; Gagnon-Turcotte, Gabriel; Dube, J F; Gagne, Jean Simon; Delisle, Yanick; Campeau-Lecours, Alexandre; Gosselin, Clement; Gosselin, Benoit

    2016-12-21

    Assistive Technology (AT) tools and appliances are being more and more widely used and developed worldwide to improve the autonomy of people living with disabilities and ease the interaction with their environments. This paper describes an intuitive and wireless surface electromyography (sEMG) based body-machine interface for AT tools. Spinal cord injuries (SCIs) at C5-C8 levels affect patients' arms, forearms, hands and fingers control. Thus, using classical AT control interfaces (keypads, joysticks, etc.) is often difficult or impossible. The proposed system reads the AT users' Residual Functional Capacities (RFCs) through their sEMG activity, and converts them into appropriate commands using a threshold-based control algorithm. It has proven to be suitable as a control alternative for assistive devices and has been tested with the JACO arm, an articulated assistive device of which the vocation is to help people living with upper-body disabilities in their daily life activities. The wireless prototype, the architecture of which is based on a 3-channel sEMG measurement system and a 915-MHz wireless transceiver built around a low-power microcontroller, uses low-cost off-the-shelf commercial components. The embedded controller is compared with JACO's regular joystick-based interface, using combinations of forearm, pectoral, masseter and trapeze muscles. The measured index of performance values are 0.88, 0.51 and 0.41 bits/s respectively, for correlation coefficients with the Fitt's model of 0.75, 0.85 and 0.67. These results demonstrate that the proposed controller offers an attractive alternative to conventional interfaces, such as joystick devices, for upper-body disabled people using assistive technologies such as JACO.

  13. Interface controlled plastic flow modelled by strain gradient plasticity theory

    NASA Astrophysics Data System (ADS)

    Pardoen, Thomas; Massart, Thierry J.

    The resistance to plastic flow in metals is often dominated by the presence of interfaces which interfere with dislocation nucleation and motion. Interfaces can be static such as grain and phase boundaries or dynamic such as new boundaries resulting from a phase transformation. The interface can be hard and fully impenetrable to dislocations, or soft and partly or fully transparent. The interactions between dislocations and interfaces constitute the main mechanism controlling the strength and strain hardening capacity of many metallic systems especially in very fine microstructures with a high density of interfaces. A phenomenological strain gradient plasticity theory is used to introduce, within a continuum framework, higher order boundary conditions which empirically represent the effect of interfaces on plastic flow. The strength of the interfaces can evolve during the loading in order to enrich the description of their response. The behaviour of single and dual phase steels, with possible TRIP effect, accounting for the interactions with static and dynamic boundaries, is addressed, with a specific focus on the size dependent strength and ductility balance. The size dependent response of weak precipitate free zones surrounding grain boundaries is treated as an example involving more than one microstructural length scale.

  14. Recent Findings Based on Airborne Measurements at the Interface of Coastal California Clouds and Clear Air

    NASA Astrophysics Data System (ADS)

    Sorooshian, A.; Crosbie, E.; Wang, Z.; Chuang, P. Y.; Craven, J. S.; Coggon, M. M.; Brunke, M.; Zeng, X.; Jonsson, H.; Woods, R. K.; Flagan, R. C.; Seinfeld, J.

    2015-12-01

    Recent aircraft field experiments with the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter have targeted interfaces between clear and cloudy areas along the California coast. These campaigns, based out of Marina, California in the July-August time frame, include the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE, 2011), Nucleation in California Experiment (NiCE, 2013), and the Biological Ocean Atmospheric Study (BOAS, 2015). Results will be presented related to (i) aqueous processing of natural and anthropogenic emissions, (ii) vertical re-distribution of ocean micronutrients, and (iii) stratocumulus cloud clearings and notable thermodynamic and aerosol contrasts across the clear-cloudy interface. The results have implications for modeling and observational studies of marine boundary layer clouds, especially in relation to aerosol-cloud interactions.

  15. Prediction of interface residue based on the features of residue interaction network.

    PubMed

    Jiao, Xiong; Ranganathan, Shoba

    2017-11-07

    Protein-protein interaction plays a crucial role in the cellular biological processes. Interface prediction can improve our understanding of the molecular mechanisms of the related processes and functions. In this work, we propose a classification method to recognize the interface residue based on the features of a weighted residue interaction network. The random forest algorithm is used for the prediction and 16 network parameters and the B-factor are acting as the element of the input feature vector. Compared with other similar work, the method is feasible and effective. The relative importance of these features also be analyzed to identify the key feature for the prediction. Some biological meaning of the important feature is explained. The results of this work can be used for the related work about the structure-function relationship analysis via a residue interaction network model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Knowledge-based graphical interfaces for presenting technical information

    NASA Technical Reports Server (NTRS)

    Feiner, Steven

    1988-01-01

    Designing effective presentations of technical information is extremely difficult and time-consuming. Moreover, the combination of increasing task complexity and declining job skills makes the need for high-quality technical presentations especially urgent. We believe that this need can ultimately be met through the development of knowledge-based graphical interfaces that can design and present technical information. Since much material is most naturally communicated through pictures, our work has stressed the importance of well-designed graphics, concentrating on generating pictures and laying out displays containing them. We describe APEX, a testbed picture generation system that creates sequences of pictures that depict the performance of simple actions in a world of 3D objects. Our system supports rules for determining automatically the objects to be shown in a picture, the style and level of detail with which they should be rendered, the method by which the action itself should be indicated, and the picture's camera specification. We then describe work on GRIDS, an experimental display layout system that addresses some of the problems in designing displays containing these pictures, determining the position and size of the material to be presented.

  17. Pyroelectric energy harvesting using liquid-based switchable thermal interfaces

    SciTech Connect

    Cha, G; Ju, YS

    2013-01-15

    The pyroelectric effect offers an intriguing solid-state approach for harvesting ambient thermal energy to power distributed networks of sensors and actuators that are remotely located or otherwise difficult to access. There have been, however, few device-level demonstrations due to challenges in converting spatial temperature gradients into temporal temperature oscillations necessary for pyroelectric energy harvesting. We demonstrate the feasibility of a device concept that uses liquid-based thermal interfaces for rapid switching of the thermal conductance between a pyroelectric material and a heat source/sink and can thereby deliver high output power density. Using a thin film of a pyroelectric co-polymer together with a macroscale mechanical actuator, we operate pyroelectric thermal energy harvesting cycles at frequencies close to 1 Hz. Film-level power densities as high as 110 mW/cm(3) were achieved, limited by slow heat diffusion across a glass substrate. When combined with a laterally interdigitated electrode array and a MEMS actuator, the present design offers an attractive option for compact high-power density thermal energy harvesters. (C) 2012 Elsevier B.V. All rights reserved.

  18. Triboelectrification based motion sensor for human-machine interfacing.

    PubMed

    Yang, Weiqing; Chen, Jun; Wen, Xiaonan; Jing, Qingshen; Yang, Jin; Su, Yuanjie; Zhu, Guang; Wu, Wenzuo; Wang, Zhong Lin

    2014-05-28

    We present triboelectrification based, flexible, reusable, and skin-friendly dry biopotential electrode arrays as motion sensors for tracking muscle motion and human-machine interfacing (HMI). The independently addressable, self-powered sensor arrays have been utilized to record the electric output signals as a mapping figure to accurately identify the degrees of freedom as well as directions and magnitude of muscle motions. A fast Fourier transform (FFT) technique was employed to analyse the frequency spectra of the obtained electric signals and thus to determine the motion angular velocities. Moreover, the motion sensor arrays produced a short-circuit current density up to 10.71 mA/m(2), and an open-circuit voltage as high as 42.6 V with a remarkable signal-to-noise ratio up to 1000, which enables the devices as sensors to accurately record and transform the motions of the human joints, such as elbow, knee, heel, and even fingers, and thus renders it a superior and unique invention in the field of HMI.

  19. Towards a Communication Brain Computer Interface Based on Semantic Relations

    PubMed Central

    Geuze, Jeroen; Farquhar, Jason; Desain, Peter

    2014-01-01

    This article investigates a possible Brain Computer Interface (BCI) based on semantic relations. The BCI determines which prime word a subject has in mind by presenting probe words using an intelligent algorithm. Subjects indicate when a presented probe word is related to the prime word by a single finger tap. The detection of the neural signal associated with this movement is used by the BCI to decode the prime word. The movement detector combined both the evoked (ERP) and induced (ERD) responses elicited with the movement. Single trial movement detection had an average accuracy of 67%. The decoding of the prime word had an average accuracy of 38% when using 100 probes and 150 possible targets, and 41% after applying a dynamic stopping criterium, reducing the average number of probes to 47. The article shows that the intelligent algorithm used to present the probe words has a significantly higher performance than a random selection of probes. Simulations demonstrate that the BCI also works with larger vocabulary sizes, and the performance scales logarithmically with vocabulary size. PMID:24516552

  20. Film rupture in the diffuse interface model coupled to hydrodynamics.

    PubMed

    Thiele, U; Velarde, M G; Neuffer, K; Pomeau, Y

    2001-09-01

    The process of dewetting of a thin liquid film is usually described using a long-wave approximation yielding a single evolution equation for the film thickness. This equation incorporates an additional pressure term-the disjoining pressure-accounting for the molecular forces. Recently a disjoining pressure was derived coupling hydrodynamics to the diffuse interface model [L. M. Pismen and Y. Pomeau, Phys. Rev. E 62, 2480 (2000)]. Using the resulting evolution equation as a generic example for the evolution of unstable thin films, we examine the thickness ranges for linear instability and metastability for flat films, the families of stationary periodic and localized solutions, and their linear stability. The results are compared to simulations of the nonlinear time evolution. From this we conclude that, within the linearly unstable thickness range, there exists a well defined subrange where finite perturbations are crucial for the time evolution and the resulting structures. In the remainder of the linearly unstable thickness range the resulting structures are controlled by the fastest flat film mode assumed up to now for the entire linearly unstable thickness range. Finally, the implications for other forms of disjoining pressure in dewetting and for spinodal decomposition are discussed.

  1. Web Interface for Modeling Fog Oil Dispersion During Training

    NASA Astrophysics Data System (ADS)

    Lozar, Robert C.

    2002-08-01

    Predicting the dispersion of military camouflage training materials-Smokes and Obscurants (SO)-is a rapidly improving science. The Defense Threat Reduction Agency (DTRA) developed the Hazard Prediction and Assessment Capability (HPAC), a software package that allows the modeling of the dispersion of several potentially detrimental materials. ERDC/CERL characterized the most commonly used SO material, fog oil in HPAC terminology, to predict the SO dispersion characteristics in various training scenarios that might have an effect on Threatened and Endangered Species (TES) at DoD installations. To make the configuration more user friendly, the researchers implemented an initial web-interface version of HPAC with a modifiable fog-oil component that can be applied at any installation in the world. By this method, an installation SO trainer can plan the location and time of fog oil training activities and is able to predict the degree to which various areas will be effected, particularly important in ensuring the appropriate management of TES on a DoD installation.

  2. Scale separation for multi-scale modeling of free-surface and two-phase flows with the conservative sharp interface method

    SciTech Connect

    Han, L.H. Hu, X.Y. Adams, N.A.

    2015-01-01

    In this paper we present a scale separation approach for multi-scale modeling of free-surface and two-phase flows with complex interface evolution. By performing a stimulus-response operation on the level-set function representing the interface, separation of resolvable and non-resolvable interface scales is achieved efficiently. Uniform positive and negative shifts of the level-set function are used to determine non-resolvable interface structures. Non-resolved interface structures are separated from the resolved ones and can be treated by a mixing model or a Lagrangian-particle model in order to preserve mass. Resolved interface structures are treated by the conservative sharp-interface model. Since the proposed scale separation approach does not rely on topological information, unlike in previous work, it can be implemented in a straightforward fashion into a given level set based interface model. A number of two- and three-dimensional numerical tests demonstrate that the proposed method is able to cope with complex interface variations accurately and significantly increases robustness against underresolved interface structures.

  3. Microchannel-based regenerative scaffold for chronic peripheral nerve interfacing in amputees.

    PubMed

    Srinivasan, Akhil; Tahilramani, Mayank; Bentley, John T; Gore, Russell K; Millard, Daniel C; Mukhatyar, Vivek J; Joseph, Anish; Haque, Adel S; Stanley, Garrett B; English, Arthur W; Bellamkonda, Ravi V

    2015-02-01

    Neurally controlled prosthetics that cosmetically and functionally mimic amputated limbs remain a clinical need because state of the art neural prosthetics only provide a fraction of a natural limb's functionality. Here, we report on the fabrication and capability of polydimethylsiloxane (PDMS) and epoxy-based SU-8 photoresist microchannel scaffolds to serve as viable constructs for peripheral nerve interfacing through in vitro and in vivo studies in a sciatic nerve amputee model where the nerve lacks distal reinnervation targets. These studies showed microchannels with 100 μm × 100 μm cross-sectional areas support and direct the regeneration/migration of axons, Schwann cells, and fibroblasts through the microchannels with space available for future maturation of the axons. Investigation of the nerve in the distal segment, past the scaffold, showed a high degree of organization, adoption of the microchannel architecture forming 'microchannel fascicles', reformation of endoneurial tubes and axon myelination, and a lack of aberrant and unorganized growth that might be characteristic of neuroma formation. Separate chronic terminal in vivo electrophysiology studies utilizing the microchannel scaffolds with permanently integrated microwire electrodes were conducted to evaluate interfacing capabilities. In all devices a variety of spontaneous, sensory evoked and electrically evoked single and multi-unit action potentials were recorded after five months of implantation. Together, these findings suggest that microchannel scaffolds are well suited for chronic implantation and peripheral nerve interfacing to promote organized nerve regeneration that lends itself well to stable interfaces. Thus this study establishes the basis for the advanced fabrication of large-electrode count, wireless microchannel devices that are an important step towards highly functional, bi-directional peripheral nerve interfaces.

  4. Microchannel-based regenerative scaffold for chronic peripheral nerve interfacing in amputees

    PubMed Central

    Srinivasan, Akhil; Tahilramani, Mayank; Bentley, John T.; Gore, Russell K.; Millard, Daniel; Mukhatyar, Vivek J.; Joseph, Anish; Haque, Adel; Stanley, Garrett B.; English, Arthur W.; Bellamkonda, Ravi V.

    2015-01-01

    Neurally controlled prosthetics that cosmetically and functionally mimic amputated limbs remain a clinical need because state of the art neural prosthetics only provide a fraction of a natural limb’s functionality. Here, we report on the fabrication and capability of polydimethylsiloxane (PDMS) and epoxy-based SU-8 photoresist microchannel scaffolds to serve as viable constructs for peripheral nerve interfacing though in vitro and in vivo studies in a sciatic nerve amputee model where the nerve lacks distal reinnervation targets. These studies showed microchannels with 100 μm × 100 μm cross-sectional areas support and direct the regeneration/migration of axons, Schwann cells, and fibroblasts through the microchannels with space available for future maturation of the axons. Investigation of the nerve in the distal segment, past the scaffold, showed a high degree of organization, adoption of the microchannel architecture forming ‘microchannel fascicles’, reformation of endoneurial tubes and axon myelination, and a lack of aberrant and unorganized growth that might be characteristic of neuroma formation. Separate chronic terminal in vivo electrophysiology studies utilizing the microchannel scaffolds with permanently integrated microwire electrodes were conducted to evaluate interfacing capabilities. In all devices a variety of spontaneous, sensory evoked and electrically evoked single and multi-unit action potentials were recorded after five months of implantation. Together, these findings suggest that microchannel scaffolds are well suited for chronic implantation and peripheral nerve interfacing to promote organized nerve regeneration that lends itself well to stable interfaces. Thus this study establishes the basis for the advanced fabrication of large-electrode count, wireless microchannel devices that are an important step towards highly functional, bi-directional peripheral nerve interfaces. PMID:25522974

  5. Quantifying effects of humans and climate on groundwater resources of Hawaii through sharp-interface modeling

    NASA Astrophysics Data System (ADS)

    Rotzoll, K.; Izuka, S. K.; Nishikawa, T.; Fienen, M. N.; El-Kadi, A. I.

    2016-12-01

    Some of the volcanic-rock aquifers of the islands of Hawaii are substantially developed, leading to concerns related to the effects of groundwater withdrawals on saltwater intrusion and stream base-flow reduction. A numerical modeling analysis using recent available information (e.g., recharge, withdrawals, hydrogeologic framework, and conceptual models of groundwater flow) advances current understanding of groundwater flow and provides insight into the effects of human activity and climate change on Hawaii's water resources. Three island-wide groundwater-flow models (Kauai, Oahu, and Maui) were constructed using MODFLOW 2005 coupled with the Seawater-Intrusion Package (SWI2), which simulates the transition between saltwater and freshwater in the aquifer as a sharp interface. This approach allowed coarse vertical discretization (maximum of two layers) without ignoring the freshwater-saltwater system at the regional scale. Model construction (FloPy3), parameter estimation (PEST), and analysis of results were streamlined using Python scripts. Model simulations included pre-development (1870) and recent (average of 2001-10) scenarios for each island. Additionally, scenarios for future withdrawals and climate change were simulated for Oahu. We present our streamlined approach and results showing estimated effects of human activity on the groundwater resource by quantifying decline in water levels, rise of the freshwater-saltwater interface, and reduction in stream base flow. Water-resource managers can use this information to evaluate consequences of groundwater development that can constrain future groundwater availability.

  6. Mathematical modeling of the head-disk interface (abstract)

    NASA Astrophysics Data System (ADS)

    Crone, Robert M.; Jhon, Myung S.

    1993-05-01

    State-of-the-art theoretical and numerical techniques required to simulate the head-disk interface (HDI) of future magnetic storage devices is presented. The severity of operating conditions (i.e., attempts to achieve flying heights as low as 40 nm) pose several challenges. Large transient pressure gradients can be established within air bearing leading to numerical oscillations as well as to increased program execution times. Enhanced gaseous rarefaction effects must also be incorporated into the analysis. In the present study, accurate nonoscillatory air bearing pressure distributions were obtained using a high resolution finite element algorithm to solve the generalized Reynolds equation. Higher order gaseous rarefaction effects are incorporated into generalized Reynolds equations using the total mass flow rate coefficient predicted from the linearized Boltzmann equation. The form of the generalized Reynolds equation that is presented in this paper is an improved version of the continued fraction approximation previously proposed by Crone et al.1 A simple scaling analysis, which is based upon the results of the linearized Boltzmann equation, will also be presented to study the effect of slider miniaturization, as well as to obtain a novel interpretation of accelerated wear and accelerated flyability test results.

  7. DPSM technique for ultrasonic field modelling near fluid-solid interface.

    PubMed

    Banerjee, Sourav; Kundu, Tribikram; Alnuaimi, Nasser A

    2007-06-01

    Distributed point source method (DPSM) is gradually gaining popularity in the field of non-destructive evaluation (NDE). DPSM is a semi-analytical technique that can be used to calculate the ultrasonic fields produced by transducers of finite dimension placed in homogeneous or non-homogeneous media. This technique has been already used to model ultrasonic fields in homogeneous and multi-layered fluid structures. In this paper the method is extended to model the ultrasonic fields generated in both fluid and solid media near a fluid-solid interface when the transducer is placed in the fluid half-space near the interface. Most results in this paper are generated by the newly developed DPSM technique that requires matrix inversion. This technique is identified as the matrix inversion based DPSM technique. Some of these results are compared with the results produced by the Rayleigh-Sommerfield integral based DPSM technique. Theory behind both matrix inversion based and Rayleigh-Sommerfield integral based DPSM techniques is presented in this paper. The matrix inversion based DPSM technique is found to be very efficient for computing the ultrasonic field in non-homogeneous materials. One objective of this study is to model ultrasonic fields in both solids and fluids generated by the leaky Rayleigh wave when finite size transducers are inclined at Rayleigh critical angles. This phenomenon has been correctly modelled by the technique. It should be mentioned here that techniques based on paraxial assumptions fail to model the critical reflection phenomenon. Other advantages of the DPSM technique compared to the currently available techniques for transducer radiation modelling are discussed in the paper under Introduction.

  8. Establishing a fiber-optic-based optical neural interface.

    PubMed

    Adamantidis, Antoine R; Zhang, Feng; de Lecea, Luis; Deisseroth, Karl

    2014-08-01

    Selective expression of opsins in genetically defined neurons makes it possible to control a subset of neurons without affecting nearby cells and processes in the intact brain, but light must still be delivered to the target brain structure. Light scattering limits the delivery of light from the surface of the brain. For this reason, we have developed a fiber-optic-based optical neural interface (ONI), which allows optical access to any brain structure in freely moving mammals. The ONI system is constructed by modifying the small animal cannula system from PlasticsOne. The system for bilateral stimulation consists of a bilateral cannula guide that has been stereotactically implanted over the target brain region, a screw cap for securing the optical fiber to the animal's head, a fiber guard modified from the internal cannula adapter, and a bare fiber whose length is customized based on the depth of the target region. For unilateral stimulation, a single-fiber system can be constructed using unilateral cannula parts from PlasticsOne. We describe here the preparation of the bilateral ONI system and its use in optical stimulation of the mouse or rat brain. Delivery of opsin-expressing virus and implantation of the ONI may be conducted in the same surgical session; alternatively, with a transgenic animal no opsin virus is delivered during the surgery. Similar procedures are useful for deep or superficial injections (even for neocortical targets, although in some cases surface light-emitting diodes or cortex-apposed fibers can be used for the most superficial cortical targets).

  9. Interfaces in driven Ising models: shear enhances confinement.

    PubMed

    Smith, Thomas H R; Vasilyev, Oleg; Abraham, Douglas B; Maciołek, Anna; Schmidt, Matthias

    2008-08-08

    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 magnetization 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.

  10. Introducing a new open source GIS user interface for the SWAT model

    USDA-ARS?s Scientific Manuscript database

    The Soil and Water Assessment Tool (SWAT) model is a robust watershed modelling tool. It typically uses the ArcSWAT interface to create its inputs. ArcSWAT is public domain software which works in the licensed ArcGIS environment. The aim of this paper was to develop an open source user interface ...

  11. Comparing Text-based and Graphic User Interfaces for novice and expert users.

    PubMed

    Chen, Jung-Wei; Zhang, Jiajie

    2007-10-11

    Graphic User Interface (GUI) is commonly considered to be superior to Text-based User Interface (TUI). This study compares GUI and TUI in an electronic dental record system. Several usability analysis techniques compared the relative effectiveness of a GUI and a TUI. Expert users and novice users were evaluated in time required and steps needed to complete the task. A within-subject design was used to evaluate if the experience with either interface will affect task performance. The results show that the GUI interface was not better than the TUI for expert users. GUI interface was better for novice users. For novice users there was a learning transfer effect from TUI to GUI. This means a user interface is user-friendly or not depending on the mapping between the user interface and tasks. GUI by itself may or may not be better than TUI.

  12. Comparing Text-based and Graphic User Interfaces for Novice and Expert Users

    PubMed Central

    Chen, Jung-Wei; Zhang, Jiajie

    2007-01-01

    Graphic User Interface (GUI) is commonly considered to be superior to Text-based User Interface (TUI). This study compares GUI and TUI in an electronic dental record system. Several usability analysis techniques compared the relative effectiveness of a GUI and a TUI. Expert users and novice users were evaluated in time required and steps needed to complete the task. A within-subject design was used to evaluate if the experience with either interface will affect task performance. The results show that the GUI interface was not better than the TUI for expert users. GUI interface was better for novice users. For novice users there was a learning transfer effect from TUI to GUI. This means a user interface is user-friendly or not depending on the mapping between the user interface and tasks. GUI by itself may or may not be better than TUI. PMID:18693811

  13. Modeling the Charge Transport in Graphene Nano Ribbon Interfaces for Nano Scale Electronic Devices

    NASA Astrophysics Data System (ADS)

    Kumar, Ravinder; Engles, Derick

    2015-05-01

    In this research work we have modeled, simulated and compared the electronic charge transport for Metal-Semiconductor-Metal interfaces of Graphene Nano Ribbons (GNR) with different geometries using First-Principle calculations and Non-Equilibrium Green's Function (NEGF) method. We modeled junctions of Armchair GNR strip sandwiched between two Zigzag strips with (Z-A-Z) and Zigzag GNR strip sandwiched between two Armchair strips with (A-Z-A) using semi-empirical Extended Huckle Theory (EHT) within the framework of Non-Equilibrium Green Function (NEGF). I-V characteristics of the interfaces were visualized for various transport parameters. The distinct changes in conductance and I-V curves reported as the Width across layers, Channel length (Central part) was varied at different bias voltages from -1V to 1 V with steps of 0.25 V. From the simulated results we observed that the conductance through A-Z-A graphene junction is in the range of 10-13 Siemens whereas the conductance through Z-A-Z graphene junction is in the range of 10-5 Siemens. These suggested conductance controlled mechanisms for the charge transport in the graphene interfaces with different geometries is important for the design of graphene based nano scale electronic devices like Graphene FETs, Sensors.

  14. Hole-trapping/hydrogen transport (HT) sup 2 model for interface-trap buildup in MOS devices

    SciTech Connect

    Shaneyfelt, M.R.; Schwank, J.R.; Fleetwood, D.M.; Winokur, P.S.

    1990-01-01

    The electric field dependence of radiation-induced interface-trap formation has been reported to be different for metal-gate capacitors and polysilicon-gate capacitors and transistors. For metal-gate capacitors, interface-trap formation steadily increases with increasing positive field. On the other hand, for polysilicon-gate capacitors and transistors, interface-trap buildup peaks near fields of 1 MV/cm to 2 MV/cm and decreases with an approximate E{sup {minus}1/2} dependence at higher fields. The previously reported field dependence for interface-trap generation for Al-gate capacitors is consistent at all fields with McLean's physical explanation of the two-stage process, which depends on hydrogen ion (H {sup +}) release in the bulk of the oxide as radiation-induced holes transport to either interface via polaron hopping. Above 1 MV/cm, the field dependence of interface-trap buildup for polysilicon-gate devices is inconsistent with this model. Instead, it is similar to the field dependence for hole-trapping in SiO{sub 2}, suggesting that hole trapping may play a key role in interface-trap generation in Si-gate devices. However, recent studies of the time-dependence of interface-trap buildup have known that hole trapping cannot be the rate-limiting step in interface-trap buildup in polysilicon gate devices. Consistent with McLean's physical explanation of the two-stage process, the rate-limiting step in interface-trap formation appears to be H{sup +} transport to the Si/SiO{sub 2} interface. We will show that the electric field dependence of radiation-induced oxide- and interface-trap charge buildup for both polysilicon and metal-gate transistors follows an approximate E{sup {minus}1/2} field dependence over a wide range of electric fields when electron-hole recombination effects are included. Based on these results a hole trapping/hydrogen transport (HT){sup 2} model for interface-trap buildup is proposed.

  15. An Energy Approach to a Micromechanics Model Accounting for Nonlinear Interface Debonding.

    SciTech Connect

    Tan, H.; Huang, Y.; Geubelle, P. H.; Liu, C.; Breitenfeld, M. S.

    2005-01-01

    We developed a micromechanics model to study the effect of nonlinear interface debonding on the constitutive behavior of composite materials. While implementing this micromechanics model into a large simulation code on solid rockets, we are challenged by problems such as tension/shear coupling and the nonuniform distribution of displacement jump at the particle/matrix interfaces. We therefore propose an energy approach to solve these problems. This energy approach calculates the potential energy of the representative volume element, including the contribution from the interface debonding. By minimizing the potential energy with respect to the variation of the interface displacement jump, the traction balanced interface debonding can be found and the macroscopic constitutive relations established. This energy approach has the ability to treat different load conditions in a unified way, and the interface cohesive law can be in any arbitrary forms. In this paper, the energy approach is verified to give the same constitutive behaviors as reported before.

  16. Do Europa's Mountains Have Roots? Modeling Flow Along the Ice-Water Interface

    NASA Astrophysics Data System (ADS)

    Cutler, B. B.; Goodman, J. C.

    2016-12-01

    Are topographic features on the surface of Europa and other icy worlds isostatically compensated by variations in shell thickness (Airy isostasy)? This is only possible if variations in shell thickness can remain stable over geologic time. In this work we demonstrate that local shell thickness perturbations will relax due to viscous flow in centuries. We present a model of Europa's ice crust which includes thermal conduction, viscous flow of ice, and a mobile ice/water interface: the topography along the ice-water interface varies in response to melting, freezing, and ice flow. Temperature-dependent viscosity, conductivity, and density lead to glacier-like flow along the base of the ice shell, as well as solid-state convection in its interior. We considered both small scale processes, such as an isostatically-compensated ridge or lenticula, or heat flux from a hydrothermal plume; and a larger model focusing on melting and flow on the global scale. Our local model shows that ice-basal topographic features 5 kilometers deep and 4 kilometers wide can be filled in by glacial flow in about 200 years; even very large cavities can be infilled in 1000 years. "Hills" (locally thick areas) are removed faster than "holes". If a strong local heat flux (10x global average) is applied to the base of the ice, local melting will be prevented by rapid inflow of ice from nearby. On the large scale, global ice flow from the thick cool pole to the warmer and thinner equator removes global-scale topography in about 1 Ma; melting and freezing from this process may lead to a coupled feedback with the ocean flow. We find that glacial flow at the base of the ice shell is so rapid that Europa's ice-water interface is likely to be very flat. Local surface topography probably cannot be isostatically compensated by thickness variations: Europa's mountains may have no roots.

  17. Investigation of the Interfaces between Cu(111)-based Electrodes and Water Using Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Chang, Jin Hyun

    This thesis presents a fundamental study of the interface between Cu(111)-based electrodes and water. Density functional theory is used to investigate the interaction between water and Cu(111) both in the absence and presence of an external electric field. To analyze the water-electrode interaction in depth, a monomeric adsorption of water is studied and compared with other similar types of molecules. The orientation of the adsorbed molecules is found to be influenced by the energy gap between the Fermi level of Cu(111) and the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the molecules. A simple relationship is observed where a stronger dipole moment of the molecule and a lower adsorption energy lead to an interface which responds more sensitively to the external electric field. The dipole moment is a more critical parameter. The behaviour of a water overlayer is then investigated on Cu(111). A differential capacitance of the Cu(111)/water interface remains constant when the molecular movements of water is ignored. The change in the orientations of the water molecules causes the differential capacitance of the interface to be potential dependent. A sharp increase in the differential capacitance is found when the water layer undergoes a structural transition. A new method, namely a "constant field" method is devised to determine the potential of the electrode at a given external electric field. The impact of coating Cu(111) with a layer of graphene is also studied. A quantum capacitance, an intrinsic capacitive property of graphene, is found to influence the differential capacitance of the graphene-coated Cu(111). However, it was found that the electronic interaction between graphene and Cu(111) alters the differential capacitance of the interface at certain electrode potentials. The change in the differential capacitance cannot be predicted by the standard modelling approaches and thus, ab initio modelling of the electrified

  18. A COMSOL-GEMS interface for modeling coupled reactive-transport geochemical processes

    NASA Astrophysics Data System (ADS)

    Azad, Vahid Jafari; Li, Chang; Verba, Circe; Ideker, Jason H.; Isgor, O. Burkan

    2016-07-01

    An interface was developed between COMSOL MultiphysicsTM finite element analysis software and (geo)chemical modeling platform, GEMS, for the reactive-transport modeling of (geo)chemical processes in variably saturated porous media. The two standalone software packages are managed from the interface that uses a non-iterative operator splitting technique to couple the transport (COMSOL) and reaction (GEMS) processes. The interface allows modeling media with complex chemistry (e.g. cement) using GEMS thermodynamic database formats. Benchmark comparisons show that the developed interface can be used to predict a variety of reactive-transport processes accurately. The full functionality of the interface was demonstrated to model transport processes, governed by extended Nernst-Plank equation, in Class H Portland cement samples in high pressure and temperature autoclaves simulating systems that are used to store captured carbon dioxide (CO2) in geological reservoirs.

  19. Development of a graphical user interface in GIS raster format for the finite difference ground-water model code, MODFLOW

    SciTech Connect

    Heinzer, T.; Hansen, D.T.; Greer, W.; Sebhat, M.

    1996-12-31

    A geographic information system (GIS) was used in developing a graphical user interface (GUI) for use with the US Geological Survey`s finite difference ground-water flow model, MODFLOW. The GUI permits the construction of a MODFLOW based ground-water flow model from scratch in a GIS environment. The model grid, input data and output are stored as separate raster data sets which may be viewed, edited, and manipulated in a graphic environment. Other GIS data sets can be displayed with the model data sets for reference and evaluation. The GUI sets up a directory structure for storage of the files associated with the ground-water model and the raster data sets created by the interface. The GUI stores model coefficients and model output as raster values. Values stored by these raster data sets are formatted for use with the ground-water flow model code.

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

    USGS Publications Warehouse

    Banta, Edward R.

    2014-01-01

    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

  1. A Generic Approach for Pen-Based User Interface Development

    NASA Astrophysics Data System (ADS)

    Macé, Sébastien; Anquetil, Éric

    Pen-based interaction is an intuitive way to realize hand drawn structured documents, but few applications take advantage of it. Indeed, the interpretation of the user hand drawn strokes in the context of document is a complex problem. In this paper, we propose a new generic approach to develop such systems based on three independent components. The first one is a set of graphical and editing functions adapted to pen interaction. The second one is a rule-based formalism that models structured document composition and the corresponding interpretation process. The last one is a hand drawn stroke analyzer that is able to interpret strokes progressively, directly while the user is drawing. We highlight in particular the human-computer interaction induced from this progressive interpretation process. Thanks to this generic approach, three pen-based system prototypes have already been developed, for musical score editing, for graph editing, and for UML class diagram editing

  2. Modeling single molecule junction mechanics as a probe of interface bonding

    DOE PAGES

    Hybertsen, Mark S.

    2017-03-07

    Using the atomic force microscope based break junction approach, applicable to metal point contacts and single molecule junctions, measurements can be repeated thousands of times resulting in rich data sets characterizing the properties of an ensemble of nanoscale junction structures. This paper focuses on the relationship between the measured force extension characteristics including bond rupture and the properties of the interface bonds in the junction. We analyzed a set of exemplary model junction structures using density functional theory based calculations to simulate the adiabatic potential surface that governs the junction elongation. The junction structures include representative molecules that bond tomore » the electrodes through amine, methylsulfide, and pyridine links. The force extension characteristics are shown to be most effectively analyzed in a scaled form with maximum sustainable force and the distance between the force zero and force maximum as scale factors. Widely used, two parameter models for chemical bond potential energy versus bond length are found to be nearly identical in scaled form. Furthermore, they fit well to the present calculations of N–Au and S–Au donor-acceptor bonds, provided no other degrees of freedom are allowed to relax. Examination of the reduced problem of a single interface, but including relaxation of atoms proximal to the interface bond, shows that a single-bond potential form renormalized by an effective harmonic potential in series fits well to the calculated results. This, then, allows relatively accurate extraction of the interface bond energy. Analysis of full junction models shows cooperative effects that go beyond the mechanical series inclusion of the second bond in the junction, the spectator bond that does not rupture. Calculations for a series of diaminoalkanes as a function of molecule length indicate that the most important cooperative effect is due to the interactions between the dipoles induced by

  3. Modeling single molecule junction mechanics as a probe of interface bonding

    NASA Astrophysics Data System (ADS)

    Hybertsen, Mark S.

    2017-03-01

    Using the atomic force microscope based break junction approach, applicable to metal point contacts and single molecule junctions, measurements can be repeated thousands of times resulting in rich data sets characterizing the properties of an ensemble of nanoscale junction structures. This paper focuses on the relationship between the measured force extension characteristics including bond rupture and the properties of the interface bonds in the junction. A set of exemplary model junction structures has been analyzed using density functional theory based calculations to simulate the adiabatic potential surface that governs the junction elongation. The junction structures include representative molecules that bond to the electrodes through amine, methylsulfide, and pyridine links. The force extension characteristics are shown to be most effectively analyzed in a scaled form with maximum sustainable force and the distance between the force zero and force maximum as scale factors. Widely used, two parameter models for chemical bond potential energy versus bond length are found to be nearly identical in scaled form. Furthermore, they fit well to the present calculations of N-Au and S-Au donor-acceptor bonds, provided no other degrees of freedom are allowed to relax. Examination of the reduced problem of a single interface, but including relaxation of atoms proximal to the interface bond, shows that a single-bond potential form renormalized by an effective harmonic potential in series fits well to the calculated results. This allows relatively accurate extraction of the interface bond energy. Analysis of full junction models shows cooperative effects that go beyond the mechanical series inclusion of the second bond in the junction, the spectator bond that does not rupture. Calculations for a series of diaminoalkanes as a function of molecule length indicate that the most important cooperative effect is due to the interactions between the dipoles induced by the donor

  4. Layout Design of Human-Machine Interaction Interface of Cabin Based on Cognitive Ergonomics and GA-ACA.

    PubMed

    Deng, Li; Wang, Guohua; Yu, Suihuai

    2016-01-01

    In order to consider the psychological cognitive characteristics affecting operating comfort and realize the automatic layout design, cognitive ergonomics and GA-ACA (genetic algorithm and ant colony algorithm) were introduced into the layout design of human-machine interaction interface. First, from the perspective of cognitive psychology, according to the information processing process, the cognitive model of human-machine interaction interface was established. Then, the human cognitive characteristics were analyzed, and the layout principles of human-machine interaction interface were summarized as the constraints in layout design. Again, the expression form of fitness function, pheromone, and heuristic information for the layout optimization of cabin was studied. The layout design model of human-machine interaction interface was established based on GA-ACA. At last, a layout design system was developed based on this model. For validation, the human-machine interaction interface layout design of drilling rig control room was taken as an example, and the optimization result showed the feasibility and effectiveness of the proposed method.

  5. Layout Design of Human-Machine Interaction Interface of Cabin Based on Cognitive Ergonomics and GA-ACA

    PubMed Central

    Deng, Li; Wang, Guohua; Yu, Suihuai

    2016-01-01

    In order to consider the psychological cognitive characteristics affecting operating comfort and realize the automatic layout design, cognitive ergonomics and GA-ACA (genetic algorithm and ant colony algorithm) were introduced into the layout design of human-machine interaction interface. First, from the perspective of cognitive psychology, according to the information processing process, the cognitive model of human-machine interaction interface was established. Then, the human cognitive characteristics were analyzed, and the layout principles of human-machine interaction interface were summarized as the constraints in layout design. Again, the expression form of fitness function, pheromone, and heuristic information for the layout optimization of cabin was studied. The layout design model of human-machine interaction interface was established based on GA-ACA. At last, a layout design system was developed based on this model. For validation, the human-machine interaction interface layout design of drilling rig control room was taken as an example, and the optimization result showed the feasibility and effectiveness of the proposed method. PMID:26884745

  6. Modelling of transient heat conduction with diffuse interface methods

    NASA Astrophysics Data System (ADS)

    Ettrich, J.; Choudhury, A.; Tschukin, O.; Schoof, E.; August, A.; Nestler, B.

    2014-12-01

    We present a survey on different numerical interpolation schemes used for two-phase transient heat conduction problems in the context of interface capturing phase-field methods. Examples are general transport problems in the context of diffuse interface methods with a non-equal heat conductivity in normal and tangential directions to the interface. We extend the tonsorial approach recently published by Nicoli M et al (2011 Phys. Rev. E 84 1-6) to the general three-dimensional (3D) transient evolution equations. Validations for one-dimensional, two-dimensional and 3D transient test cases are provided, and the results are in good agreement with analytical and numerical reference solutions.

  7. Modeling the flow in diffuse interface methods of solidification

    NASA Astrophysics Data System (ADS)

    Subhedar, A.; Steinbach, I.; Varnik, F.

    2015-08-01

    Fluid dynamical equations in the presence of a diffuse solid-liquid interface are investigated via a volume averaging approach. The resulting equations exhibit the same structure as the standard Navier-Stokes equation for a Newtonian fluid with a constant viscosity, the effect of the solid phase fraction appearing in the drag force only. This considerably simplifies the use of the lattice Boltzmann method as a fluid dynamics solver in solidification simulations. Galilean invariance is also satisfied within this approach. Further, we investigate deviations between the diffuse and sharp interface flow profiles via both quasiexact numerical integration and lattice Boltzmann simulations. It emerges from these studies that the freedom in choosing the solid-liquid coupling parameter h provides a flexible way of optimizing the diffuse interface-flow simulations. Once h is adapted for a given spatial resolution, the simulated flow profiles reach an accuracy comparable to quasiexact numerical simulations.

  8. Discontinuous model with semi analytical sheath interface for radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Miyashita, Masaru

    2016-09-01

    Sumitomo Heavy Industries, Ltd. provide many products utilizing plasma. In this study, we focus on the Radio Frequency (RF) plasma source by interior antenna. The plasma source is expected to be high density and low metal contamination. However, the sputtering the antenna cover by high energy ion from sheath voltage still have been problematic. We have developed the new model which can calculate sheath voltage wave form in the RF plasma source for realistic calculation time. This model is discontinuous that electronic fluid equation in plasma connect to usual passion equation in antenna cover and chamber with semi analytical sheath interface. We estimate the sputtering distribution based on calculated sheath voltage waveform by this model, sputtering yield and ion energy distribution function (IEDF) model. The estimated sputtering distribution reproduce the tendency of experimental results.

  9. Development and implementation of (Q)SAR modeling within the CHARMMing web-user interface.

    PubMed

    Weidlich, Iwona E; Pevzner, Yuri; Miller, Benjamin T; Filippov, Igor V; Woodcock, H Lee; Brooks, Bernard R

    2015-01-05

    Recent availability of large publicly accessible databases of chemical compounds and their biological activities (PubChem, ChEMBL) has inspired us to develop a web-based tool for structure activity relationship and quantitative structure activity relationship modeling to add to the services provided by CHARMMing (www.charmming.org). This new module implements some of the most recent advances in modern machine learning algorithms-Random Forest, Support Vector Machine, Stochastic Gradient Descent, Gradient Tree Boosting, so forth. A user can import training data from Pubchem Bioassay data collections directly from our interface or upload his or her own SD files which contain structures and activity information to create new models (either categorical or numerical). A user can then track the model generation process and run models on new data to predict activity. © 2014 Wiley Periodicals, Inc.

  10. Development and implementation of (Q)SAR modeling within the CHARMMing Web-user interface

    PubMed Central

    Weidlich, Iwona E.; Pevzner, Yuri; Miller, Benjamin T.; Filippov, Igor V.; Woodcock, H. Lee; Brooks, Bernard R.

    2014-01-01

    Recent availability of large publicly accessible databases of chemical compounds and their biological activities (PubChem, ChEMBL) has inspired us to develop a Web-based tool for SAR and QSAR modeling to add to the services provided by CHARMMing (www.charmming.org). This new module implements some of the most recent advances in modern machine learning algorithms – Random Forest, Support Vector Machine (SVM), Stochastic Gradient Descent, Gradient Tree Boosting etc. A user can import training data from Pubchem Bioassay data collections directly from our interface or upload his or her own SD files which contain structures and activity information to create new models (either categorical or numerical). A user can then track the model generation process and run models on new data to predict activity. PMID:25362883

  11. Integrated droplet analysis system with electrospray ionization-mass spectrometry using a hydrophilic tongue-based droplet extraction interface.

    PubMed

    Zhu, Ying; Fang, Qun

    2010-10-01

    This paper describes a simple, robust, and integrated microchip-based system for droplet analysis with electrospray ionization-mass spectrometry (ESI-MS) detection. The microchip integrated multiple modules including a droplet generator, a droplet extraction interface, and a monolithic ESI emitter. The novel droplet extraction interface based on hydrophilic tongue structure was developed. The interface could transfer droplets from segmented phase to aqueous phase with high reliability and high controllability by coupling with a back pressure regulator. The flow injection mode was adopted to introduce the transferred droplets to the ESI emitter for minimizing the cross-contamination between droplets and achieving droplet matrix modification. The system performance was evaluated using angiotensin as a model sample, and high sensitivity (<1 μM) and a good reproducibility of 5.2% RSD (n = 7) were obtained. The present device was further applied in the online monitoring of droplet-based microreaction for alkylation of peptide.

  12. Electronic Structure at Electrode/Electrolyte Interfaces in Magnesium based Batteries

    NASA Astrophysics Data System (ADS)

    Balachandran, Janakiraman; Siegel, Donald

    2015-03-01

    Magnesium is a promising multivalent element for use in next generation electrochemical energy storage systems. However, a wide range of challenges such as low coulombic efficiency, low/varying capacity and cyclability need to be resolved in order to realize Mg based batteries. Many of these issues can be related to interfacial phenomena between the Mg anode and common electrolytes. Ab-initio based computational models of these interfaces can provide insights on the interfacial interactions that can be difficult to probe experimentally. In this work we present ab-initio computations of common electrolyte solvents (THF, DME) in contact with two model electrode surfaces namely -- (i) an ``SEI-free'' electrode based on Mg metal and, (ii) a ``passivated'' electrode consisting of MgO. We perform GW calculations to predict the reorganization of the molecular orbitals (HOMO/LUMO) upon contact with the these surfaces and their alignment with respect to the Fermi energy of the electrodes. These computations are in turn compared with more efficient GGA (PBE) & Hybrid (HSE) functional calculations. The results obtained from these computations enable us to qualitatively describe the stability of these solvent molecules at electrode-electrolyte interfaces

  13. Multi-scale diffuse interface modeling of multi-component two-phase flow with partial miscibility

    SciTech Connect

    Kou, Jisheng; Sun, Shuyu

    2016-08-01

    In this paper, we introduce a diffuse interface model to simulate multi-component two-phase flow with partial miscibility based on a realistic equation of state (e.g. Peng–Robinson equation of state). Because of partial miscibility, thermodynamic relations are used to model not only interfacial properties but also bulk properties, including density, composition, pressure, and realistic viscosity. As far as we know, this effort is the first time to use diffuse interface modeling based on equation of state for modeling of multi-component two-phase flow with partial miscibility. In numerical simulation, the key issue is to resolve the high contrast of scales from the microscopic interface composition to macroscale bulk fluid motion since the interface has a nanoscale thickness only. To efficiently solve this challenging problem, we develop a multi-scale simulation method. At the microscopic scale, we deduce a reduced interfacial equation under reasonable assumptions, and then we propose a formulation of capillary pressure, which is consistent with macroscale flow equations. Moreover, we show that Young–Laplace equation is an approximation of this capillarity formulation, and this formulation is also consistent with the concept of Tolman length, which is a correction of Young–Laplace equation. At the macroscopical scale, the interfaces are treated as discontinuous surfaces separating two phases of fluids. Our approach differs from conventional sharp-interface two-phase flow model in that we use the capillary pressure directly instead of a combination of surface tension and Young–Laplace equation because capillarity can be calculated from our proposed capillarity formulation. A compatible condition is also derived for the pressure in flow equations. Furthermore, based on the proposed capillarity formulation, we design an efficient numerical method for directly computing the capillary pressure between two fluids composed of multiple components. Finally, numerical

  14. Multi-scale diffuse interface modeling of multi-component two-phase flow with partial miscibility

    NASA Astrophysics Data System (ADS)

    Kou, Jisheng; Sun, Shuyu

    2016-08-01

    In this paper, we introduce a diffuse interface model to simulate multi-component two-phase flow with partial miscibility based on a realistic equation of state (e.g. Peng-Robinson equation of state). Because of partial miscibility, thermodynamic relations are used to model not only interfacial properties but also bulk properties, including density, composition, pressure, and realistic viscosity. As far as we know, this effort is the first time to use diffuse interface modeling based on equation of state for modeling of multi-component two-phase flow with partial miscibility. In numerical simulation, the key issue is to resolve the high contrast of scales from the microscopic interface composition to macroscale bulk fluid motion since the interface has a nanoscale thickness only. To efficiently solve this challenging problem, we develop a multi-scale simulation method. At the microscopic scale, we deduce a reduced interfacial equation under reasonable assumptions, and then we propose a formulation of capillary pressure, which is consistent with macroscale flow equations. Moreover, we show that Young-Laplace equation is an approximation of this capillarity formulation, and this formulation is also consistent with the concept of Tolman length, which is a correction of Young-Laplace equation. At the macroscopical scale, the interfaces are treated as discontinuous surfaces separating two phases of fluids. Our approach differs from conventional sharp-interface two-phase flow model in that we use the capillary pressure directly instead of a combination of surface tension and Young-Laplace equation because capillarity can be calculated from our proposed capillarity formulation. A compatible condition is also derived for the pressure in flow equations. Furthermore, based on the proposed capillarity formulation, we design an efficient numerical method for directly computing the capillary pressure between two fluids composed of multiple components. Finally, numerical tests

  15. Modeling of the cometary nucleus-coma interface region

    NASA Technical Reports Server (NTRS)

    Gombosi, T. I.; Korosmezey, A.

    1989-01-01

    A well-developed dusty cometary atmosphere extends to distances over 4 orders of magnitude larger than the size of the nucleus. Pre-encounter models of the inner coma were based on the assumption that a spherically symmetric description was adequate to describe the dust-gas interaction region. Recent observational evidence together with a new generation of multidimensional theoretical models demonstrate that the inner cometary environment is far from spherical symmetry and a number of unexpected phenomena (dust jet broadening, subsolar dust spike formation, etc.) might play a significant role in this region.

  16. Investigation of piezoelectric impedance-based health monitoring of structure interface debonding

    NASA Astrophysics Data System (ADS)

    Xiao, Li; Chen, Guofeng; Chen, Xiaoming; Qu, Wenzhong

    2016-04-01

    Various damages might occur during the solid rocket motor (SRM) manufacturing/operational phase, and the debonding of propellant/insulator/composite case interfaces is one of damage types which determine the life of a motor. The detection of such interface debonding damage will be beneficial for developing techniques for reliable nondestructive evaluation (NDE) and structural health monitoring (SHM). Piezoelectric sensors are widely used for structural health monitoring technique. In particular, electromechanical impedance (EMI) techniques give simple and low-cost solutions for detecting damage in various structures. In this work, piezoelectric EMI structural health monitoring technique is applied to identify the debonding condition of propellant/insulator interface structure using finite element method and experimental investigation. A three-dimensional coupled field finite element model is developed using the software ANSYS and the harmonic analysis is conducted for high-frequency impedance analysis procedure. In the experimental study, the impedance signals were measured from PZT and MFC sensors outside attached to composite case monitoring the different debonding conditions between the propellant and insulator. Root mean square deviation (RMSD) based damage index is conducted to quantify the changes i n impedance for different de bonding conditions and frequency range. Simulation and experimental results confirmed that the EMI technique can be used effectively for detecting the debonding damage in SRM and is expected to be useful for future application of real SRM's SHM.

  17. Penalty-Based Interface Technology for Prediction of Delamination Growth in Laminated Structures

    NASA Technical Reports Server (NTRS)

    Averill, Ronald C.

    2004-01-01

    An effective interface element technology has been developed for connecting and simulating crack growth between independently modeled finite element subdomains (e.g., composite plies). This method has been developed using penalty constraints and allows coupling of finite element models whose nodes do not necessarily coincide along their common interface. Additionally, the present formulation leads to a computational approach that is very efficient and completely compatible with existing commercial software. The present interface element has been implemented in the commercial finite element code ABAQUS as a User Element Subroutine (UEL), making it easy to test the approach for a wide range of problems. The interface element technology has been formulated to simulate delamination growth in composite laminates. Thanks to its special features, the interface element approach makes it possible to release portions of the interface surface whose length is smaller than that of the finite elements. In addition, the penalty parameter can vary within the interface element, allowing the damage model to be applied to a desired fraction of the interface between the two meshes. Results for double cantilever beam DCB, end-loaded split (ELS) and fixed-ratio mixed mode (FRMM) specimens are presented. These results are compared to measured data to assess the ability of the present damage model to simulate crack growth.

  18. Ceria-based model catalysts: fundamental studies on the importance of the metal–ceria interface in CO oxidation, the water–gas shift, CO 2 hydrogenation, and methane and alcohol reforming

    DOE PAGES

    Rodriguez, José A.; Grinter, David C.; Liu, Zongyuan; ...

    2017-02-17

    Model metal/ceria and ceria/metal catalysts have been shown to be excellent systems for studying fundamental phenomena linked to the operation of technical catalysts. In the last fifteen years, many combinations of well-defined systems involving different kinds of metals and ceria have been prepared and characterized using the modern techniques of surface science. So far most of the catalytic studies have been centered on a few reactions: CO oxidation, the hydrogenation of CO2, and the production of hydrogen through the water–gas shift reaction and the reforming of methane or alcohols. By using model catalysts it is been possible to examine inmore » detail correlations between the structural, electronic and catalytic properties of ceria–metal interfaces. In situ techniques (X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, infrared spectroscopy, scanning tunneling microscopy) have been combined to study the morphological changes under reaction conditions and investigate the evolution of active phases involved in the cleavage of C–O, C–H and C–C bonds. Several studies with model ceria catalysts have shown the importance of strong metal–support interactions. Generally, a substantial body of knowledge has been acquired and concepts have been developed for a more rational approach to the design of novel technical catalysts containing ceria.« less

  19. Ceria-based model catalysts: fundamental studies on the importance of the metal-ceria interface in CO oxidation, the water-gas shift, CO2 hydrogenation, and methane and alcohol reforming.

    PubMed

    Rodriguez, José A; Grinter, David C; Liu, Zongyuan; Palomino, Robert M; Senanayake, Sanjaya D

    2017-04-03

    Model metal/ceria and ceria/metal catalysts have been shown to be excellent systems for studying fundamental phenomena linked to the operation of technical catalysts. In the last fifteen years, many combinations of well-defined systems involving different kinds of metals and ceria have been prepared and characterized using the modern techniques of surface science. So far most of the catalytic studies have been centered on a few reactions: CO oxidation, the hydrogenation of CO2, and the production of hydrogen through the water-gas shift reaction and the reforming of methane or alcohols. Using model catalysts it has been possible to examine in detail correlations between the structural, electronic and catalytic properties of ceria-metal interfaces. In situ techniques (X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, infrared spectroscopy, scanning tunneling microscopy) have been combined to study the morphological changes under reaction conditions and investigate the evolution of active phases involved in the cleavage of C-O, C-H and C-C bonds. Several studies with model ceria catalysts have shown the importance of strong metal-support interactions. In general, a substantial body of knowledge has been acquired and concepts have been developed for a more rational approach to the design of novel technical catalysts containing ceria.

  20. Characteristic-based and interface-sharpening algorithm for high-order simulations of immiscible compressible multi-material flows

    NASA Astrophysics Data System (ADS)

    He, Zhiwei; Tian, Baolin; Zhang, Yousheng; Gao, Fujie

    2017-03-01

    The present work focuses on the simulation of immiscible compressible multi-material flows with the Mie-Grüneisen-type equation of state governed by the non-conservative five-equation model [1]. Although low-order single fluid schemes have already been adopted to provide some feasible results, the application of high-order schemes (introducing relatively small numerical dissipation) to these flows may lead to results with severe numerical oscillations. Consequently, attempts to apply any interface-sharpening techniques to stop the progressively more severe smearing interfaces for a longer simulation time may result in an overshoot increase and in some cases convergence to a non-physical solution occurs. This study proposes a characteristic-based interface-sharpening algorithm for performing high-order simulations of such flows by deriving a pressure-equilibrium-consistent intermediate state (augmented with approximations of pressure derivatives) for local characteristic variable reconstruction and constructing a general framework for interface sharpening. First, by imposing a weak form of the jump condition for the non-conservative five-equation model, we analytically derive an intermediate state with pressure derivatives treated as additional parameters of the linearization procedure. Based on this intermediate state, any well-established high-order reconstruction technique can be employed to provide the state at each cell edge. Second, by designing another state with only different reconstructed values of the interface function at each cell edge, the advection term in the equation of the interface function is discretized twice using any common algorithm. The difference between the two discretizations is employed consistently for interface compression, yielding a general framework for interface sharpening. Coupled with the fifth-order improved accurate monotonicity-preserving scheme [2] for local characteristic variable reconstruction and the tangent of hyperbola

  1. Swimming of a model ciliate near an air-liquid interface

    NASA Astrophysics Data System (ADS)

    Wang, S.; Ardekani, A. M.

    2013-06-01

    In this work, the role of the hydrodynamic forces on a swimming microorganism near an air-liquid interface is studied. The lubrication theory is utilized to analyze hydrodynamic effects within the narrow gap between a flat interface and a small swimmer. By using an archetypal low-Reynolds-number swimming model called “squirmer,” we find that the magnitude of the vertical swimming velocity is on the order of O(ɛlnɛ), where ɛ is the ratio of the gap width to the swimmer's body size. The reduced swimming velocity near an interface can explain experimental observations of the aggregation of microorganisms near a liquid interface.

  2. Swimming of a model ciliate near an air-liquid interface.

    PubMed

    Wang, S; Ardekani, A M

    2013-06-01

    In this work, the role of the hydrodynamic forces on a swimming microorganism near an air-liquid interface is studied. The lubrication theory is utilized to analyze hydrodynamic effects within the narrow gap between a flat interface and a small swimmer. By using an archetypal low-Reynolds-number swimming model called "squirmer," we find that the magnitude of the vertical swimming velocity is on the order of O(εlnε), where ε is the ratio of the gap width to the swimmer's body size. The reduced swimming velocity near an interface can explain experimental observations of the aggregation of microorganisms near a liquid interface.

  3. Intuitive user interface for mobile devices based on visual motion detection

    NASA Astrophysics Data System (ADS)

    Winkler, Stefan; Rangaswamy, Karthik; Zhou, ZhiYing

    2007-02-01

    The small form factor and unergonomic keys of mobile phones call for new and more natural approaches in user interface (UI) design. In this paper, we propose intuitive motion-based UI controls for mobile devices with built-in cameras based on the visual detection of the device's self-motion. We developed a car-racing game to test our new interface, and we conducted a user study to evaluate the accuracy, sensitivity, responsiveness and usability of our proposed system. Results show that our motion-based interface is well received by the users and clearly preferred over traditional button-based controls.

  4. Integrated surface and groundwater modelling in the Thames Basin, UK using the Open Modelling Interface

    NASA Astrophysics Data System (ADS)

    Mackay, Jonathan; Abesser, Corinna; Hughes, Andrew; Jackson, Chris; Kingdon, Andrew; Mansour, Majdi; Pachocka, Magdalena; Wang, Lei; Williams, Ann

    2013-04-01

    The River Thames catchment is situated in the south-east of England. It covers approximately 16,000 km2 and is the most heavily populated river basin in the UK. It is also one of the driest and has experienced severe drought events in the recent past. With the onset of climate change and human exploitation of our environment, there are now serious concerns over the sustainability of water resources in this basin with 6 million m3 consumed every day for public water supply alone. Groundwater in the Thames basin is extremely important, providing 40% of water for public supply. The principal aquifer is the Chalk, a dual permeability limestone, which has been extensively studied to understand its hydraulic properties. The fractured Jurassic limestone in the upper catchment also forms an important aquifer, supporting baseflow downstream during periods of drought. These aquifers are unconnected other than through the River Thames and its tributaries, which provide two-thirds of London's drinking water. Therefore, to manage these water resources sustainably and to make robust projections into the future, surface and groundwater processes must be considered in combination. This necessitates the simulation of the feedbacks and complex interactions between different parts of the water cycle, and the development of integrated environmental models. The Open Modelling Interface (OpenMI) standard provides a method through which environmental models of varying complexity and structure can be linked, allowing them to run simultaneously and exchange data at each timestep. This architecture has allowed us to represent the surface and subsurface flow processes within the Thames basin at an appropriate level of complexity based on our understanding of particular hydrological processes and features. We have developed a hydrological model in OpenMI which integrates a process-driven, gridded finite difference groundwater model of the Chalk with a more simplistic, semi

  5. Modeling Interfacial Thermal Boundary Conductance of Engineered Interfaces

    DTIC Science & Technology

    2014-08-31

    Interfaces Award Number: FA9550-09-1-0245 Program Manager: Dr. Jason Marshall / Dr. John Luginsland RTB-5, Plasma and Electroenergetic Physics Air Force...thermal boundary resistance at GaN/substrate interface”, Electronics Letters 40, 81–83 (2004). 22A. Sarua, H. Ji, K. P. Hilton, D. J. Wallis , M. J

  6. A Contextual Model for Identity Management (IdM) Interfaces

    ERIC Educational Resources Information Center

    Fuller, Nathaniel J.

    2014-01-01

    The usability of Identity Management (IdM) systems is highly dependent upon design that simplifies the processes of identification, authentication, and authorization. Recent findings reveal two critical problems that degrade IdM usability: (1) unfeasible techniques for managing various digital identifiers, and (2) ambiguous security interfaces.…

  7. A Contextual Model for Identity Management (IdM) Interfaces

    ERIC Educational Resources Information Center

    Fuller, Nathaniel J.

    2014-01-01

    The usability of Identity Management (IdM) systems is highly dependent upon design that simplifies the processes of identification, authentication, and authorization. Recent findings reveal two critical problems that degrade IdM usability: (1) unfeasible techniques for managing various digital identifiers, and (2) ambiguous security interfaces.…

  8. Modeling Auditory-Haptic Interface Cues from an Analog Multi-line Telephone

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Anderson, Mark R.; Bittner, Rachael M.

    2012-01-01

    The Western Electric Company produced a multi-line telephone during the 1940s-1970s using a six-button interface design that provided robust tactile, haptic and auditory cues regarding the "state" of the communication system. This multi-line telephone was used as a model for a trade study comparison of two interfaces: a touchscreen interface (iPad)) versus a pressure-sensitive strain gauge button interface (Phidget USB interface controllers). The experiment and its results are detailed in the authors' AES 133rd convention paper " Multimodal Information Management: Evaluation of Auditory and Haptic Cues for NextGen Communication Dispays". This Engineering Brief describes how the interface logic, visual indications, and auditory cues of the original telephone were synthesized using MAX/MSP, including the logic for line selection, line hold, and priority line activation.

  9. Neural bases of syntax-semantics interface processing.

    PubMed

    Malaia, Evguenia; Newman, Sharlene

    2015-06-01

    The binding problem-question of how information between the modules of the linguistic system is integrated during language processing-is as yet unresolved. The remarkable speed of language processing and comprehension (Pulvermüller et al. 2009) suggests that at least coarse semantic information (e.g. noun animacy) and syntactically-relevant information (e.g. verbal template) are integrated rapidly to allow for coarse comprehension. This EEG study investigated syntax-semantics interface processing during word-by-word sentence reading. As alpha-band neural activity serves as an inhibition mechanism for local networks, we used topographical distribution of alpha power to help identify the timecourse of the binding process. We manipulated the syntactic parameter of verbal event structure, and semantic parameter of noun animacy in reduced relative clauses (RRCs, e.g. "The witness/mansion seized/protected by the agent was in danger"), to investigate the neural bases of interaction between syntactic and semantic networks during sentence processing. The word-by-word stimulus presentation method in the present experiment required manipulation of both syntactic structure and semantic features in the working memory. The results demonstrated a gradient distribution of early components (biphasic posterior P1-N2 and anterior N1-P2) over function words "by" and "the", and the verb, corresponding to facilitation or conflict resulting from the syntactic (telicity) and semantic (animacy) cues in the preceding portion of the sentence. This was followed by assimilation of power distribution in the α band at the second noun. The flattened distribution of α power during the mental manipulation with high demand on working memory-thematic role re-assignment-demonstrates a state of α equilibrium with strong functional coupling between posterior and anterior regions. These results demonstrate that the processing of semantic and syntactic features during sentence comprehension proceeds

  10. A Comprehension Based Analysis of Autoflight System Interfaces

    NASA Technical Reports Server (NTRS)

    Palmer, Everett (Technical Monitor); Polson, Peter G.

    2003-01-01

    This cooperative agreement supported Dr. Peter Polson's participation in two interrelated research programs. The first was the development of the Situation-Goal-Behavior (SGB) Model that is both a formal description of an avionics system's logic and behavior and a representation of a system that can be understood by avionics designers, pilots, and training developers. The second was the development of a usability inspection method based on an approximate model, RAFIV, of pilot interactions with the Flight Management System (FMS). The main purpose of this report is to integrate the two models and provide a context in order to better characterize the accomplishments of this research program. A major focus of both the previous and this Cooperative Agreement was the development of usability evaluation methods that can be effectively utilized during all phases of the design, development, and certification process of modern avionics systems. The current efforts to validate these methods have involved showing that they generate useful analyses of known operational and training problems with the current generation of avionics systems in modern commercial airliners. This report is organized into seven sections. Following the overview, the second section describes the Goal-Situation-Behavior model and its applications. The next section summarizes the foundations of the RAFIV model and describes the model in some detail. The contents of both these sections are derived from previous reports referenced in footnotes. The fourth section integrates these two models into a complete design evaluation and training development framework. The fifth section contains conclusions and possible future directions for research. References are in Section 6. Section 7 contains the titles and abstracts of the papers paper describing in more detail the results of this research program.

  11. A New Tool for Inundation Modeling: Community Modeling Interface for Tsunamis (ComMIT)

    NASA Astrophysics Data System (ADS)

    Titov, V. V.; Moore, C. W.; Greenslade, D. J. M.; Pattiaratchi, C.; Badal, R.; Synolakis, C. E.; Kânoğlu, U.

    2011-11-01

    Almost 5 years after the 26 December 2004 Indian Ocean tragedy, the 10 August 2009 Andaman tsunami demonstrated that accurate forecasting is possible using the tsunami community modeling tool Community Model Interface for Tsunamis (ComMIT). ComMIT is designed for ease of use, and allows dissemination of results to the community while addressing concerns associated with proprietary issues of bathymetry and topography. It uses initial conditions from a precomputed propagation database, has an easy-to-interpret graphical interface, and requires only portable hardware. ComMIT was initially developed for Indian Ocean countries with support from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United States Agency for International Development (USAID), and the National Oceanic and Atmospheric Administration (NOAA). To date, more than 60 scientists from 17 countries in the Indian Ocean have been trained and are using it in operational inundation mapping.

  12. Sketch-based geologic modeling

    NASA Astrophysics Data System (ADS)

    Rood, M. P.; Jackson, M.; Hampson, G.; Brazil, E. V.; de Carvalho, F.; Coda, C.; Sousa, M. C.; Zhang, Z.; Geiger, S.

    2015-12-01

    Two-dimensional (2D) maps and cross-sections, and 3D conceptual models, are fundamental tools for understanding, communicating and modeling geology. Yet geologists lack dedicated and intuitive tools that allow rapid creation of such figures and models. Standard drawing packages produce only 2D figures that are not suitable for quantitative analysis. Geologic modeling packages can produce 3D models and are widely used in the groundwater and petroleum communities, but are often slow and non-intuitive to use, requiring the creation of a grid early in the modeling workflow and the use of geostatistical methods to populate the grid blocks with geologic information. We present an alternative approach to rapidly create figures and models using sketch-based interface and modelling (SBIM). We leverage methods widely adopted in other industries to prototype complex geometries and designs. The SBIM tool contains built-in geologic rules that constrain how sketched lines and surfaces interact. These rules are based on the logic of superposition and cross-cutting relationships that follow from rock-forming processes, including deposition, deformation, intrusion and modification by diagenesis or metamorphism. The approach allows rapid creation of multiple, geologically realistic, figures and models in 2D and 3D using a simple, intuitive interface. The user can sketch in plan- or cross-section view. Geologic rules are used to extrapolate sketched lines in real time to create 3D surfaces. Quantitative analysis can be carried our directly on the models. Alternatively, they can be output as simple figures or imported directly into other modeling tools. The software runs on a tablet PC and can be used in a variety of settings including the office, classroom and field. The speed and ease of use of SBIM enables multiple interpretations to be developed from limited data, uncertainty to be readily appraised, and figures and models to be rapidly updated to incorporate new data or concepts.

  13. A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

    DOE PAGES

    Zeng, Y.; Hunter, A.; Beyerlein, I. J.; ...

    2015-09-14

    In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τcrit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τcrit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results show that themore » value of τcrit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τcrit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τcrit values.« less

  14. A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

    SciTech Connect

    Zeng, Y.; Hunter, A.; Beyerlein, I. J.; Koslowski, M.

    2015-09-14

    In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τcrit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τcrit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results show that the value of τcrit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τcrit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τcrit values.

  15. Interface Design Concepts in the Development of a Web-Based Information Retrieval System.

    ERIC Educational Resources Information Center

    Denning, Rebecca; Shuttleworth, Marie; Smith, Phil

    1998-01-01

    Presents six principles for building and evaluating Web-based information retrieval interfaces: help the user develop an understanding of the interface and search process, judge the value of continuing search paths, and refine search queries or search topics; avoid complex navigation; make system actions explicit; and provide verbal labels…

  16. A Study of Learning and Retention with a Web-Based IR Interface

    ERIC Educational Resources Information Center

    Ahmed, S. M. Zabed; McKnight, Cliff; Oppenheim, Charles

    2005-01-01

    This article reports on an empirical study on novices' learning and retention with the Web-based interface to the Web of Science. The aim was to evaluate the performance of novice searchers in initially learning to use the search interface and in later use. Their performance in both sessions was measured in terms of time taken to perform tasks,…

  17. From Fulcher to PLEVALEX: Issues in Interface Design, Validity and Reliability in Internet Based Language Testing

    ERIC Educational Resources Information Center

    Garcia Laborda, Jesus

    2007-01-01

    Interface design and ergonomics, while already studied in much of educational theory, have not until recently been considered in language testing (Fulcher, 2003). In this paper, we revise the design principles of PLEVALEX, a fully operational prototype Internet based language testing platform. Our focus here is to show PLEVALEX's interfaces and…

  18. Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures

    PubMed Central

    Zhan, Yijian

    2017-01-01

    The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense. PMID:28773130

  19. Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

    PubMed

    Zhan, Yijian; Meschke, Günther

    2017-07-08

    The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

  20. Building Interfaces: Mechanisms, fabrication, and applications at the biotic/abiotic interface for silk fibroin based bioelectronic and biooptical devices

    NASA Astrophysics Data System (ADS)

    Brenckle, Mark

    Recent efforts in bioelectronics and biooptics have led to a shift in the materials and form factors used to make medical devices, including high performance, implantable, and wearable sensors. In this context, biopolymer-based devices must be processed to interface the soft, curvilinear biological world with the rigid, inorganic world of traditional electronics and optics. This poses new material-specific fabrication challenges in designing such devices, which in turn requires further understanding of the fundamental physical behaviors of the materials in question. As a biopolymer, silk fibroin protein has remarkable promise in this space, due to its bioresorbability, mechanical strength, optical clarity, ability to be reshaped on the micro- and nano-scale, and ability to stabilize labile compounds. Application of this material to devices at the biotic/abiotic interface will require the development of fabrication techniques for nano-patterning, lithography, multilayer adhesion, and transfer printing in silk materials. In this work, we address this need through fundamental study of the thermal and diffusional properties of silk protein as it relates to these fabrication strategies. We then leverage these properties to fabricate devices well suited to the biotic/abiotic interface in three areas: shelf-ready sensing, implantable transient electronics, and wearable biosensing. These example devices will illustrate the advantages of silk in this class of bioelectronic and biooptical devices, from fundamentals through application, and contribute to a silk platform for the development of future devices that combine biology with high technology.

  1. Parallelization of the TRIGRS model for rainfall-induced landslides using the message passing interface

    USGS Publications Warehouse

    Alvioli, M.; Baum, R.L.

    2016-01-01

    We describe a parallel implementation of TRIGRS, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model for the timing and distribution of rainfall-induced shallow landslides. We have parallelized the four time-demanding execution modes of TRIGRS, namely both the saturated and unsaturated model with finite and infinite soil depth options, within the Message Passing Interface framework. In addition to new features of the code, we outline details of the parallel implementation and show the performance gain with respect to the serial code. Results are obtained both on commercial hardware and on a high-performance multi-node machine, showing the different limits of applicability of the new code. We also discuss the implications for the application of the model on large-scale areas and as a tool for real-time landslide hazard monitoring.

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

    NASA Astrophysics Data System (ADS)

    Persikov, Anton V.; Singh, Mona

    2011-06-01

    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.

  3. Cross-Correlation based relocation of deep interface seismicity of the 2010 Chile Earthquake

    NASA Astrophysics Data System (ADS)

    Methe, P.; Tilmann, F. J.; Lange, D.

    2011-12-01

    The Chile earthquake of 27 February 2010 nucleated just north of the city of Concépcion, and ruptured to the north and to the south along 350-400 km, with most slip (up to 15 m) accumulating in the northern patch. With a magnitude of 8.8, it is the sixth-strongest earthquake since the beginning of the instrumental record; rapid response teams from Chile, the US, Germany and the UK installed a dense network for monitoring aftershocks along the whole rupture zone. We analysed a subset of this network (in total 139 stations) and detected over 100000 aftershocks following the main earthquake in the period from March to September 2010 alone, using automatic detection and grid-search based phase association algorithms (binder and CMM). Picks are refined by an auto-picking algorithm (MPX) and events are relocated in a minimum-1D model. About 20000 events are designated as very well located with at least 16 high quality automatic picks and a residual rms no larger than 0.2 s. Besides crustal seismicity, the aftershock sequence is dominated by intense plate interface seismicity near and immediately downdip of the most intense coseismic rupture. We also observe a second separate band of deeper aftershocks below the downdip end of the seismogenic zone at a depth of 40-50 km and a distance to the trench of 130-180 km, with a gap of 20-30 km to the main plate interface seismicity. In this presentation we concentrate on the analysis of this deep seismic band. The seismicity in this band is not truly continuous along the rupture zone but it is present along the whole rupture zone and forms clusters elongated along strike. Focal mechanisms derived from first motion polarities show that these events tend to be thrust type events, well aligned with the plate interface. A second deep separate group of plate interface aftershocks is not known from other subduction zone aftershock sequences. To get a better idea about the distribution of these 6000 deep aftershocks (30 to 50 km), a

  4. Head-mounted computer interface based on eye tracking

    NASA Astrophysics Data System (ADS)

    Schroeder, William E.

    1993-10-01

    A head-mounted computer interface using eye-tracking as a `pointer' was demonstrated at the Third Annual Weapons Technology Review and Training Exposition at San Diego in January 1992, and is under further development for military and civilian applications. in this interface, the computer interprets eye gaze direction just as it would input from a mouse or trackball. This technology makes possible computer-human interaction with many ideal aspects: complete portability, hands-free operation, silent, secure operation anywhere and any time. Commercial systems using control inputs from the tracked eye are available and effective within their limits, but size, weight, and cost have been barriers to wider use. This paper describes the latest head-mounted eye tracking display (HETD) development prototype. We are exploring the technological limits of current and near-term lighting, detector, and lens technology to project the feasibility of this device.

  5. Human multimedia display interface based on human activity recognition

    NASA Astrophysics Data System (ADS)

    Shang, Yiting; Lee, Eung-Joo

    2011-06-01

    In this paper, we will propose a Human Multimedia Display Interface. The interface uses the tracking of human hand movements to control the IP-TV. This paper presents an improved CAMSHIFT algorithm to control an IP-TV system. The CAMSHIFT algorithm (Continuously Adaptive MeanShift) is a method of using color information[1]. It can do tracking with a specific color of the target. In some typical environmental constraints, it can obtain good tracking performance. However, as the question of noise, large area similar to the color interference and so on, only by CAM-SHIFT algorithm it is not competent. Against these issues we propose an improved CAMSHIFT algorithm[2].

  6. Task discrimination from myoelectric activity: a learning scheme for EMG-based interfaces.

    PubMed

    Liarokapis, Minas V; Artemiadis, Panagiotis K; Kyriakopoulos, Kostas J

    2013-06-01

    A learning scheme based on Random Forests is used to discriminate the task to be executed using only myoelectric activity from the upper limb. Three different task features can be discriminated: subspace to move towards, object to be grasped and task to be executed (with the object). The discrimination between the different reach to grasp movements is accomplished with a random forests classifier, which is able to perform efficient features selection, helping us to reduce the number of EMG channels required for task discrimination. The proposed scheme can take advantage of both a classifier and a regressor that cooperate advantageously to split the task space, providing better estimation accuracy with task-specific EMG-based motion decoding models, as reported in [1] and [2]. The whole learning scheme can be used by a series of EMG-based interfaces, that can be found in rehabilitation cases and neural prostheses.

  7. Properties of the In{sub 2}O{sub 3}-Si interface: An ab initio study of a model geometry

    SciTech Connect

    Höffling, Benjamin; Bechstedt, Friedhelm

    2014-05-15

    The In{sub 2}O{sub 3}(001)-Si(001) heterojunction is studied by means of the ab initio density functional theory, quasiparticle corrections, and the supercell method. We construct a model interface based on the idea of a coincidence lattice, only Si-O interface bonds and biaxially strained In{sub 2}O{sub 3}. The properties of the interface and their consequences for the junction are mainly described in terms of electronic band levels and charge redistribution. The results indicate a type II heterostructure caused by interface dipole alteration due to electron rearrangements.

  8. Coherent description of transport across the water interface: From nanodroplets to climate models

    NASA Astrophysics Data System (ADS)

    Wilhelmsen, Øivind; Trinh, Thuat T.; Lervik, Anders; Badam, Vijay Kumar; Kjelstrup, Signe; Bedeaux, Dick

    2016-03-01

    Transport of mass and energy across the vapor-liquid interface of water is of central importance in a variety of contexts such as climate models, weather forecasts, and power plants. We provide a complete description of the transport properties of the vapor-liquid interface of water with the framework of nonequilibrium thermodynamics. Transport across the planar interface is then described by 3 interface transfer coefficients where 9 more coefficients extend the description to curved interfaces. We obtain all coefficients in the range 260-560 K by taking advantage of water evaporation experiments at low temperatures, nonequilibrium molecular dynamics with the TIP4P/2005 rigid-water-molecule model at high temperatures, and square gradient theory to represent the whole range. Square gradient theory is used to link the region where experiments are possible (low vapor pressures) to the region where nonequilibrium molecular dynamics can be done (high vapor pressures). This enables a description of transport across the planar water interface, interfaces of bubbles, and droplets, as well as interfaces of water structures with complex geometries. The results are likely to improve the description of evaporation and condensation of water at widely different scales; they open a route to improve the understanding of nanodroplets on a small scale and the precision of climate models on a large scale.

  9. Simulation of drag reduction in superhydrophobic microchannels based on parabolic gas-liquid interfaces

    NASA Astrophysics Data System (ADS)

    Li, Chunxi; Zhang, Shuo; Xue, Quanxi; Ye, Xuemin

    2016-10-01

    Based on the given parabolic gas-liquid interfaces, a two-dimensional fluid flow in superhydrophobic microchannels is numerically simulated with the steady volume of fluid model in the laminar regime. The influence of several crucial parameters on drag reduction effect is discussed. The results indicate that the superhydrophobic microchannel containing rectangular cavities displays significant drag reduction effect. With increasing inlet velocity, the pressure drop reduction decreases slightly. Augments in the pressure drop reduction tend to be large with the increase of the cavity fraction or the decrease of the channel height. The results also reveal that the variation of the normalized slip length with the cavity fraction tends to be more dramatic when the channel height is smaller. As the parabolic height of the gas-liquid interface is enlarged, both the pressure drop reduction and the normalized slip length decrease linearly, while fRe increases linearly. The impact of the cavity depth on the normalized slip length, fRe, and the pressure drop reduction is minimal supposing the depth of the cavity is greater than 40% of its width. The drag reduction effect corresponding to the dovetail cavity model is the best, and the consequence of the rectangular, trapezoidal, and triangular cavity models sequentially worsens.

  10. Discrete Kalman Filter based Sensor Fusion for Robust Accessibility Interfaces

    NASA Astrophysics Data System (ADS)

    Ghersi, I.; Mariño, M.; Miralles, M. T.

    2016-04-01

    Human-machine interfaces have evolved, benefiting from the growing access to devices with superior, embedded signal-processing capabilities, as well as through new sensors that allow the estimation of movements and gestures, resulting in increasingly intuitive interfaces. In this context, sensor fusion for the estimation of the spatial orientation of body segments allows to achieve more robust solutions, overcoming specific disadvantages derived from the use of isolated sensors, such as the sensitivity of magnetic-field sensors to external influences, when used in uncontrolled environments. In this work, a method for the combination of image-processing data and angular-velocity registers from a 3D MEMS gyroscope, through a Discrete-time Kalman Filter, is proposed and deployed as an alternate user interface for mobile devices, in which an on-screen pointer is controlled with head movements. Results concerning general performance of the method are presented, as well as a comparative analysis, under a dedicated test application, with results from a previous version of this system, in which the relative-orientation information was acquired directly from MEMS sensors (3D magnetometer-accelerometer). These results show an improved response for this new version of the pointer, both in terms of precision and response time, while keeping many of the benefits that were highlighted for its predecessor, giving place to a complementary method for signal acquisition that can be used as an alternative-input device, as well as for accessibility solutions.

  11. First-principles based calculation of the macroscopic α/β interface in titanium

    SciTech Connect

    Li, Dongdong; Zhu, Lvqi; Shao, Shouqi; Jiang, Yong

    2016-06-14

    The macroscopic α/β interface in titanium and titanium alloys consists of a ledge interface (112){sub β}/(01-10){sub α} and a side interface (11-1){sub β}/(2-1-10){sub α} in a zig-zag arrangement. Here, we report a first-principles study for predicting the atomic structure and the formation energy of the α/β-Ti interface. Both component interfaces were calculated using supercell models within a restrictive relaxation approach, with various staking sequences and high-symmetry parallel translations being considered. The ledge interface energy was predicted as 0.098 J/m{sup 2} and the side interface energy as 0.811 J/m{sup 2}. By projecting the zig-zag interface area onto the macroscopic broad face, the macroscopic α/β interface energy was estimated to be as low as ∼0.12 J/m{sup 2}, which, however, is almost double the ad hoc value used in previous phase-field simulations.

  12. Pig dorsum model for examining impaired wound healing at the skin-implant interface of percutaneous devices

    PubMed Central

    Holt, Brian Mueller; Betz, Daniel Holod; Ford, Taylor Ann; Beck, James Peter; Bloebaum, Roy Drake; Jeyapalina, Sujee

    2013-01-01

    Percutaneous medical devices are indispensable in contemporary clinical practice, but the associated incidence of low to moderate mortality infections represents a significant economic and personal cost to patients and healthcare providers. Percutaneous osseointegrated prosthetics also suffer from a similar risk of infection, limiting their clinical acceptance and usage in patients with limb loss. We hypothesized that transepidermal water loss management (TEWL) at the skin-implant interface may improve and maintain a stable skin-to-implant interface. In this study, skin reactions in a 3-month, pig dorsum model were assessed using standard histology, immunohistochemistry, and quantitative image analysis. Immunohistochemical analysis of peri-implant tissue explants showed evidence of: continuous healing (cytokeratin 6+), hypergranulation tissue (procollagen+), hyper-vascularity (Collagen 4+), and the presence of fibrocytes (CD45+ and procollagen type 1+). Importantly, the gross skin response was correlated to a previous load-bearing percutaneous osseointegrated prosthetic sheep study conducted in our lab. The skin responses of the two models indicated a potentially shared mechanism of wound healing behavior at the skin-implant interface. Although TEWL management did not reduce skin migration at the skin-implant interface, the correlation of qualitative and quantitative measures validated the pig dorsum model as a high-throughput platform for translational science based percutaneous interface investigations in the future. PMID:23832453

  13. A numerical model study of the effect of interface shape on particle pushing

    NASA Astrophysics Data System (ADS)

    Agaliotis, Eliana M.; Schvezov, Carlos E.; Rosenberger, Mario R.; Ares, Alicia E.

    2012-09-01

    A numerical model using an axisymmetric approximation is developed to study particle pushing during solidification. The model is applied to determine the effect of different parameters on the predicted critical velocity for engulfment of the particle by the solidifying interface. The main parameters considered are particle radius, interface velocity and interface shape as obtained for different thermal conductivities between matrix and particle. The relative thermal conductivity is very important in the pushing/capture process in increasing or decreasing the critical velocity for pushing one order of magnitude, with respect to the critical velocity for a flat interface, depending on whether the interface is concave or convex. Moreover, the predicted critical velocities cover the span of measured values in agreement with the tendency given by the thermal conductivities and particle radius.

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

    NASA Astrophysics Data System (ADS)

    Lou, Qin; Guo, Zhaoli

    2015-01-01

    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.

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

    PubMed

    Lou, Qin; Guo, Zhaoli

    2015-01-01

    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.

  16. A Sketching Interface for Freeform 3D Modeling

    NASA Astrophysics Data System (ADS)

    Igarashi, Takeo

    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.

  17. Modulation Depth Estimation and Variable Selection in State-Space Models for Neural Interfaces

    PubMed Central

    Hochberg, Leigh R.; Donoghue, John P.; Brown, Emery N.

    2015-01-01

    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

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

    PubMed

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

    2015-02-01

    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.

  19. Interface Modeling for Electro-Osmosis in Subgrade Structures

    DTIC Science & Technology

    2004-12-01

    aggregate and different clays ( kaolinite , montmorillonite , limestone and quartz sands) created to simulate below grade structures. A direct current 30...Quartz Sand 100 Sieve Ca Montmorillonite Na Montmorillonite Kaolinite The test setup used a 0.45 water to cement ratio concrete cylinder... Kaolinite cell Figure 4. Measured pH for Concrete and Na Montmorillonite cell 4 Scaling occurred at the interface between the anode

  20. Brain-Computer Interface application: auditory serial interface to control a two-class motor-imagery-based wheelchair.

    PubMed

    Ron-Angevin, Ricardo; Velasco-Álvarez, Francisco; Fernández-Rodríguez, Álvaro; Díaz-Estrella, Antonio; Blanca-Mena, María José; Vizcaíno-Martín, Francisco Javier

    2017-05-30

    Certain diseases affect brain areas that control the movements of the patients' body, thereby limiting their autonomy and communication capacity. Research in the field of Brain-Computer Interfaces aims to provide patients with an alternative communication channel not based on muscular activity, but on the processing of brain signals. Through these systems, subjects can control external devices such as spellers to communicate, robotic prostheses to restore limb movements, or domotic systems. The present work focus on the non-muscular control of a robotic wheelchair. A proposal to control a wheelchair through a Brain-Computer Interface based on the discrimination of only two mental tasks is presented in this study. The wheelchair displacement is performed with discrete movements. The control signals used are sensorimotor rhythms modulated through a right-hand motor imagery task or mental idle state. The peculiarity of the control system is that it is based on a serial auditory interface that provides the user with four navigation commands. The use of two mental tasks to select commands may facilitate control and reduce error rates compared to other endogenous control systems for wheelchairs. Seventeen subjects initially participated in the study; nine of them completed the three sessions of the proposed protocol. After the first calibration session, seven subjects were discarded due to a low control of their electroencephalographic signals; nine out of ten subjects controlled a virtual wheelchair during the second session; these same nine subjects achieved a medium accuracy level above 0.83 on the real wheelchair control session. The results suggest that more extensive training with the proposed control system can be an effective and safe option that will allow the displacement of a wheelchair in a controlled environment for potential users suffering from some types of motor neuron diseases.

  1. Ab-initio molecular modeling of interfaces in tantalum-carbon system

    SciTech Connect

    Balani, Kantesh; Mungole, Tarang; Bakshi, Srinivasa Rao; Agarwal, Arvind

    2012-03-15

    Processing of ultrahigh temperature TaC ceramic material with sintering additives of B{sub 4}C and reinforcement of carbon nanotubes (CNTs) gives rise to possible formation of several interfaces (Ta{sub 2}C-TaC, TaC-CNT, Ta{sub 2}C-CNT, TaB{sub 2}-TaC, and TaB{sub 2}-CNT) that could influence the resultant properties. Current work focuses on interfaces developed during spark plasma sintering of TaC-system and performing ab initio molecular modeling of the interfaces generated during processing of TaC-B{sub 4}C and TaC-CNT composites. The energy of the various interfaces has been evaluated and compared with TaC-Ta{sub 2}C interface. The iso-surface electronic contours are extracted from the calculations eliciting the enhanced stability of TaC-CNT interface by 72.2%. CNTs form stable interfaces with Ta{sub 2}C and TaB{sub 2} phases with a reduction in the energy by 35.8% and 40.4%, respectively. The computed Ta-C-B interfaces are also compared with experimentally observed interfaces in high resolution TEM images.

  2. Structure and dynamics of the aqueous liquid-vapor interface: a comprehensive particle-based simulation study.

    PubMed

    Kuo, I-F Will; Mundy, Christopher J; Eggimann, Becky L; McGrath, Matthew J; Siepmann, J Ilja; Chen, Bin; Vieceli, John; Tobias, Douglas J

    2006-03-02

    This research addresses a comprehensive particle-based simulation study of the structural, dynamic, and electronic properties of the liquid-vapor interface of water utilizing both ab initio (based on density functional theory) and empirical (fixed charge and polarizable) models. Numerous properties such as interfacial width, hydrogen bond populations, dipole moments, and correlation times will be characterized with identical schemes to draw useful conclusions on the strengths and weakness of the proposed models for interfacial water. Our findings indicate that all models considered in this study yield similar results for the radial distribution functions, hydrogen bond populations, and orientational relaxation times. Significant differences in the models appear when examining both the dipole moments and surface relaxation near the aqueous liquid-vapor interface. Here, the ab initio interaction potential predicts a significant decrease in the molecular dipole moment and expansion in the oxygen-oxygen distance as one approaches the interface in accordance with recent experiments. All classical polarizable interaction potentials show a less dramatic drop in the molecular dipole moment, and all empirical interaction potentials studied yield an oxygen-oxygen contraction as the interface is approached.

  3. Stochastic modelling of a large subduction interface earthquake in Wellington, New Zealand

    NASA Astrophysics Data System (ADS)

    Francois-Holden, C.; Zhao, J.

    2012-12-01

    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

  4. Toward efficient fiber-based quantum interface (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Soshenko, Vladimir; Vorobyov, Vadim V.; Bolshedvorsky, Stepan; Lebedev, Nikolay; Akimov, Alexey V.; Sorokin, Vadim; Smolyaninov, Andrey

    2016-04-01

    NV center in diamond is attracting a lot of attention in quantum information processing community [1]. Been spin system in clean and well-controlled environment of diamond it shows outstanding performance as quantum memory even at room temperature, spin control with single shot optical readout and possibility to build up quantum registers even on single NV center. Moreover, NV centers could be used as high-resolution sensitive elements of detectors of magnetic or electric field, temperature, tension, force or rotation. For all of these applications collection of the light emitted by NV center is crucial point. There were number of approaches suggested to address this issue, proposing use of surface plasmoms [2], manufacturing structures in diamond [3] etc. One of the key feature of any practically important interface is compatibility with the fiber technology. Several groups attacking this problem using various approaches. One of them is placing of nanodiamonds in the holes of photonic crystal fiber [4], another is utilization of AFM to pick and place nanodiamond on the tapered fiber[5]. We have developed a novel technique of placing a nanodiamond with single NV center on the tapered fiber by controlled transfer of a nanodiamond from one "donor" tapered fiber to the "target" clean tapered fiber. We verify our ability to transfer only single color centers by means of measurement of second order correlation function. With this technique, we were able to double collection efficiency of confocal microscope. The majority of the factors limiting the collection of photons via optical fiber are technical and may be removed allowing order of magnitude improved in collection. We also discuss number of extensions of this technique to all fiber excitation and integration with nanostructures. References: [1] Marcus W. Doherty, Neil B. Manson, Paul Delaney, Fedor Jelezko, Jörg Wrachtrup, Lloyd C.L. Hollenberg , " The nitrogen-vacancy colour centre in diamond," Physics Reports

  5. Planelike Interfaces in Long-Range Ising Models and Connections with Nonlocal Minimal Surfaces

    NASA Astrophysics Data System (ADS)

    Cozzi, Matteo; Dipierro, Serena; Valdinoci, Enrico

    2017-06-01

    This paper contains three types of results: the construction of ground state solutions for a long-range Ising model whose interfaces stay at a bounded distance from any given hyperplane,

  6. A phase-field point-particle model for particle-laden interfaces

    NASA Astrophysics Data System (ADS)

    Gu, Chuan; Botto, Lorenzo

    2014-11-01

    The irreversible attachment of solid particles to fluid interfaces is exploited in a variety of applications, such as froth flotation and Pickering emulsions. Critical in these applications is to predict particle transport in and near the interface, and the two-way coupling between the particles and the interface. While it is now possible to carry out particle-resolved simulations of these systems, simulating relatively large systems with many particles remains challenging. We present validation studies and preliminary results for a hybrid Eulerian-Lagrangian simulation method, in which the dynamics of the interface is fully-resolved by a phase-field approach, while the particles are treated in the ``point-particle'' approximation. With this method, which represents a compromise between the competing needs of resolving particle and interface scale phenomena, we are able to simulate the adsorption of a large number of particles in the interface of drops, and particle-interface interactions during the spinodal coarsening of a multiphase system. While this method models the adsorption phenomenon efficiently and with reasonable accuracy, it still requires understanding subtle issues related to the modelling of hydrodynamic and capillary forces for particles in contact with interface.

  7. A coupled damage-plasticity model for the cyclic behavior of shear-loaded interfaces

    NASA Astrophysics Data System (ADS)

    Carrara, P.; De Lorenzis, L.

    2015-12-01

    The present work proposes a novel thermodynamically consistent model for the behavior of interfaces under shear (i.e. mode-II) cyclic loading conditions. The interface behavior is defined coupling damage and plasticity. The admissible states' domain is formulated restricting the tangential interface stress to non-negative values, which makes the model suitable e.g. for interfaces with thin adherends. Linear softening is assumed so as to reproduce, under monotonic conditions, a bilinear mode-II interface law. Two damage variables govern respectively the loss of strength and of stiffness of the interface. The proposed model needs the evaluation of only four independent parameters, i.e. three defining the monotonic mode-II interface law, and one ruling the fatigue behavior. This limited number of parameters and their clear physical meaning facilitate experimental calibration. Model predictions are compared with experimental results on fiber reinforced polymer sheets externally bonded to concrete involving different load histories, and an excellent agreement is obtained.

  8. Modeling interface roughness scattering in a layered seabed for normal-incident chirp sonar signals.

    PubMed

    Tang, Dajun; Hefner, Brian T

    2012-04-01

    Downward looking sonar, such as the chirp sonar, is widely used as a sediment survey tool in shallow water environments. Inversion of geo-acoustic parameters from such sonar data precedes the availability of forward models. An exact numerical model is developed to initiate the simulation of the acoustic field produced by such a sonar in the presence of multiple rough interfaces. The sediment layers are assumed to be fluid layers with non-intercepting rough interfaces.

  9. A prototype interface unit for microprocessor-based loran-C receiver

    NASA Technical Reports Server (NTRS)

    Novacki, S. M., III

    1981-01-01

    An inexpensive data/command entry and display system is documented. This system is designed to operate in place of a separate ASC2 terminal. The software to interface this unit to the 6502 based navigation receiver is also described.

  10. A DSP based power electronics interface for alternative /renewable energy system.

    SciTech Connect

    1999-09-28

    This report is an update on the research project involving the implementation of a DSP-based power electronics interface for alternate/renewable energy systems, that was funded by the Department of Energy under the Inventions and Innovations program.

  11. Modeling Nitrogen Cycle at the Surface-Subsurface Water Interface

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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

  12. User interface support

    NASA Technical Reports Server (NTRS)

    Lewis, Clayton; Wilde, Nick

    1989-01-01

    Space construction will require heavy investment in the development of a wide variety of user interfaces for the computer-based tools that will be involved at every stage of construction operations. Using today's technology, user interface development is very expensive for two reasons: (1) specialized and scarce programming skills are required to implement the necessary graphical representations and complex control regimes for high-quality interfaces; (2) iteration on prototypes is required to meet user and task requirements, since these are difficult to anticipate with current (and foreseeable) design knowledge. We are attacking this problem by building a user interface development tool based on extensions to the spreadsheet model of computation. The tool provides high-level support for graphical user interfaces and permits dynamic modification of interfaces, without requiring conventional programming concepts and skills.

  13. Diffusion-controlled interface kinetics-inclusive system-theoretic propagation models for molecular communication systems

    NASA Astrophysics Data System (ADS)

    Chude-Okonkwo, Uche A. K.; Malekian, Reza; Maharaj, B. T.

    2015-12-01

    Inspired by biological systems, molecular communication has been proposed as a new communication paradigm that uses biochemical signals to transfer information from one nano device to another over a short distance. The biochemical nature of the information transfer process implies that for molecular communication purposes, the development of molecular channel models should take into consideration diffusion phenomenon as well as the physical/biochemical kinetic possibilities of the process. The physical and biochemical kinetics arise at the interfaces between the diffusion channel and the transmitter/receiver units. These interfaces are herein termed molecular antennas. In this paper, we present the deterministic propagation model of the molecular communication between an immobilized nanotransmitter and nanoreceiver, where the emission and reception kinetics are taken into consideration. Specifically, we derived closed-form system-theoretic models and expressions for configurations that represent different communication systems based on the type of molecular antennas used. The antennas considered are the nanopores at the transmitter and the surface receptor proteins/enzymes at the receiver. The developed models are simulated to show the influence of parameters such as the receiver radius, surface receptor protein/enzyme concentration, and various reaction rate constants. Results show that the effective receiver surface area and the rate constants are important to the system's output performance. Assuming high rate of catalysis, the analysis of the frequency behavior of the developed propagation channels in the form of transfer functions shows significant difference introduce by the inclusion of the molecular antennas into the diffusion-only model. It is also shown that for t > > 0 and with the information molecules' concentration greater than the Michaelis-Menten kinetic constant of the systems, the inclusion of surface receptors proteins and enzymes in the models

  14. Optical simulation of photovoltaic modules with multiple textured interfaces using the matrix-based formalism OPTOS.

    PubMed

    Tucher, Nico; Eisenlohr, Johannes; Gebrewold, Habtamu; Kiefel, Peter; Höhn, Oliver; Hauser, Hubert; Goldschmidt, Jan Christoph; Bläsi, Benedikt

    2016-07-11

    The OPTOS formalism is a matrix-based approach to determine the optical properties of textured optical sheets. It is extended within this work to enable the modelling of systems with an arbitrary number of textured, plane-parallel interfaces. A matrix-based system description is derived that accounts for the optical reflection and transmission interaction between all textured interfaces. Using OPTOS, we calculate reflectance and absorptance of complete photovoltaic module stacks, which consist of encapsulated silicon solar cells featuring textures that operate in different optical regimes. As exemplary systems, solar cells with and without module encapsulation are shown to exhibit a considerable absorptance gain if the random pyramid front side texture is combined with a diffractive rear side grating. A variation of the sunlight's angle of incidence reveals that the grating gain is almost not affected for incoming polar angles up to 60°. Considering as well the good agreement with alternative simulation techniques, OPTOS is demonstrated to be a versatile and efficient method for the optical analysis of photovoltaic modules.

  15. General atomistic approach for modeling metal-semiconductor interfaces using density functional theory and nonequilibrium Green's function

    NASA Astrophysics Data System (ADS)

    Stradi, Daniele; Martinez, Umberto; Blom, Anders; Brandbyge, Mads; Stokbro, Kurt

    2016-04-01

    Metal-semiconductor contacts are a pillar of modern semiconductor technology. Historically, their microscopic understanding has been hampered by the inability of traditional analytical and numerical methods to fully capture the complex physics governing their operating principles. Here we introduce an atomistic approach based on density functional theory and nonequilibrium Green's function, which includes all the relevant ingredients required to model realistic metal-semiconductor interfaces and allows for a direct comparison between theory and experiments via I -Vbias curve simulations. We apply this method to characterize an Ag/Si interface relevant for photovoltaic applications and study the rectifying-to-Ohmic transition as a function of the semiconductor doping. We also demonstrate that the standard "activation energy" method for the analysis of I -Vbias data might be inaccurate for nonideal interfaces as it neglects electron tunneling, and that finite-size atomistic models have problems in describing these interfaces in the presence of doping due to a poor representation of space-charge effects. Conversely, the present method deals effectively with both issues, thus representing a valid alternative to conventional procedures for the accurate characterization of metal-semiconductor interfaces.

  16. A model for electromigration-induced degradation mechanisms in dual-inlaid copper interconnects: Effect of interface bonding strength

    NASA Astrophysics Data System (ADS)

    Sukharev, Valeriy; Zschech, Ehrenfried

    2004-12-01

    A physical model and a simulation algorithm are used to predict an electromigration-(EM-) induced void nucleation and growth in dual-inlaid copper interconnect. Incorporation of all important atom migration driving forces into the mass balance equation and its solution together with solution of the coupled electromagnetics, heat transfer, and elasticity problems allows to simulate EM-induced degradation in a variety of dual-inlaid copper interconnect segments characterized by different dominant channels for mass transport. The interface bonding strengths, significantly influencing the interface diffusivity and consequently the mass transport along interfaces, result in completely different degradation and failure pictures for the weak and strengthened copper/capping layer interfaces. Strengthening of the top interface of inlaid copper interconnect metal line is a promising way to prolong the EM lifetime. The results of the numerical simulation have been proven experimentally by the EM degradation studies on the fully embedded dual-inlaid copper interconnect test structures. EM-induced void formation, movement, and growth in a copper interconnect were continuously monitored in an in situ scanning electron microscopy experiment. The correspondence between simulation results and experimental data indicates the applicability of the developed model for optimization of the physical and electrical design rules. Simulation-based optimization of the interconnect architecture, segment geometry, material properties, and some of the process parameters can generate on-chip interconnect systems with a high immunity to EM-induced failures.

  17. Predicting the pKa and stability of organic acids and bases at an oil-water interface.

    PubMed

    Andersson, M P; Olsson, M H M; Stipp, S L S

    2014-06-10

    We have used density functional theory and the implicit solvent model, COSMO-RS, to investigate how the acidity constant, pKa, of organic acids and bases adsorbed at the organic compound-aqueous solution interface changes, compared to its value in the aqueous phase. The pKa determine the surface charge density of the molecules that accumulate at the fluid-fluid interface. We have estimated the pKa by comparing the stability of the protonated and unprotonated forms of a series of molecules in the bulk aqueous solution and at an interface where parts of each molecule reside in the hydrophobic phase and the rest remains in the hydrophilic phase. We found that the pKa for acids is shifted by ∼1 pH unit to higher values compared to the bulk water pKa, whereas they are shifted to lower values by a similar amount for bases. Because this pKa shift is similar in magnitude for each of the molecules studied, we propose that the pKa for molecules at a water-organic compound interface can easily be predicted by adding a small shift to the aqueous pKa. This shift is general and correlates with the functional group. We also found that the relative composition of molecules at the fluid-fluid interface is not the same as in the bulk. For example, species such as carboxylic acids are enriched at the interface, where they can dominate surface properties, even when they are a modest component in the bulk fluid. For high surface concentrations of carboxylic acid groups at an interface, such as a self-assembled monolayer, we have demonstrated that the pKa depends on the degree of deprotonation through direct hydrogen bonding between protonated and deprotonated acidic headgroups.

  18. Modeling the diffusion/absorption response of a nanopore coated microporous silicon interface

    NASA Astrophysics Data System (ADS)

    Baker, C.; Laminack, W.; Gole, J. L.

    2016-03-01

    We outline a modeling study of an extrinsic semiconductor interface formed from the interaction of nanostructured metal oxide decorated porous silicon and used for sensing gas phase analytes. We consider simple conductometric sensors that operate at room temperature and atmospheric pressure. Nanostructured metal oxide deposition provides a matrix of responses to various analytes, facilitating the extraction of ambient gas concentrations from sensor responses. The sensors are simulated in four stages with an emphasis to the continual improvement of the modeling effort. Stage 1 focuses solely on the diffusion mechanics of an analyte gas into and out of a micro/nanoporous interface and the observed linear response at low concentrations. Stage 2 focuses on the non-linearity resulting primarily from the quenching of sensor response at higher concentrations and introduces an absorption response mechanism. Here, stage 3 demonstrates how the consideration of charge carrier density leads to the development of a new Fermi-distribution based response mechanism. Stage 4 establishes a combined absorption-Fermi-distribution response mechanism.

  19. Implementation of Language Interoperability Interfaces for NTCC transport models as part of FMCFM project

    NASA Astrophysics Data System (ADS)

    Vadlamani, Srinath; Pankin, A. Y.; Kruger, S.; Pletzer, A.; Carlsson, J.; Cary, J.

    2007-11-01

    A new generalized interface to the transport modules and libraries from the National Transport Code Collaboration (NTCC) module library [1] is presented. The interface is created as a part of the Framework for Modernization and Componentization of Fusion Modules (FMCFM) project. The interface utilizes the technologies of encapsulation and polymorphism available in Fortran-95 that replace the COMMON BLOCK approach typical for Fortran legacy codes and allows us to create a generalized interface to the reduced transport modules. The new interface facilitates access to the transport models from integrated modeling codes and allows interlanguage interfaces using a new library of C++/Fortran-95 wrappers. This library also includes a collection of subroutines for data access from C/C++ to the Fortran 90 derived data structures. The new interface to transport modules has been applied to the the GLF23 and MMM95 transport models. The functionality is demonstrated in Framework Application for Core-Edge Transport Simulations (FACETS) project. [1] A. H. Kritz et al. Comp. Phys. Communications 164 (2004) 108.

  20. Interface capturing using a compressive advection method and a compositional modelling approach: Applications

    NASA Astrophysics Data System (ADS)

    Pavlidis, Dimitrios; Xie, Zhihua; Percival, James; Gomes, Jefferson; Pain, Christopher; Matar, Omar

    2013-11-01

    Progress on a consistent approach for interface-capturing in which each component represents a different phase/fluid is described. The aim is to develop a general multiphase modelling approach based on fully-unstructured meshes that can exploit the latest mesh adaptivity methods, and in which each fluid phase may have a number of components. The method is based on the P1DG-P2 finite element pair, in which the velocity has a linear discontinuous variation and the pressure has a quadratic continuous variation. The method is compared against experimental results for a collapsing water column test case and a convergence study is performed. The method is then used to simulate horizontal slug flow. EPSRC Programme Grant EP/K003976/1.

  1. High level modelling and design of asynchronous interface logic

    NASA Astrophysics Data System (ADS)

    Yakovlev, A. V.; Koelmans, A. M.; Lavagno, L.

    1993-11-01

    The authors propose a new methodology to design asynchronous circuits that is divided in two stages: abstract synthesis and logic synthesis. The first state is carried out by refining an abstract model, based on logic predicates describing the correct input-output behavior of the circuit, into a labelled Petri net and then into a formalization of timing diagrams (the Signal Transition Graph). This refinement involves hierarchical decomposition of the initial implementation until its size can be handled by automated logic synthesis tools, as well as replacing symbolic events occurring on the input-output ports of the labelled Petri net with up and down transitions occurring on the input-output wires of a circuit implementation.

  2. The GIS weasel - An interface for the development of spatial information in modeling

    USGS Publications Warehouse

    Viger, R.J.; Markstrom, S.M.; Leavesley, G.H.; ,

    2005-01-01

    The GIS Weasel is a map and Graphical User Interface (GUI) driven tool that has been developed as an aid to modelers in the delineation, characterization of geographic features, and their parameterization for use in distributed or lumped parameter physical process models. The interface does not require user expertise in geographic information systems (GIS). The user does need knowledge of how the model will use the output from the GIS Weasel. The GIS Weasel uses Workstation ArcInfo and its the Grid extension. The GIS Weasel will run on all platforms that Workstation ArcInfo runs (i.e. numerous flavors of Unix and Microsoft Windows).The GIS Weasel requires an input ArcInfo grid of some topographical description of the Area of Interest (AOI). This is normally a digital elevation model, but can be the surface of a ground water table or any other data that flow direction can be resolved from. The user may define the AOI as a custom drainage area based on an interactively specified watershed outlet point, or use a previously created map. The user is then able to use any combination of the GIS Weasel's tool set to create one or more maps for depicting different kinds of geographic features. Once the spatial feature maps have been prepared, then the GIS Weasel s many parameterization routines can be used to create descriptions of each element in each of the user s created maps. Over 200 parameterization routines currently exist, generating information about shape, area, and topological association with other features of the same or different maps, as well many types of information based on ancillary data layers such as soil and vegetation properties. These tools easily integrate other similarly formatted data sets.

  3. Goal-recognition-based adaptive brain-computer interface for navigating immersive robotic systems

    NASA Astrophysics Data System (ADS)

    Abu-Alqumsan, Mohammad; Ebert, Felix; Peer, Angelika

    2017-06-01

    Objective. This work proposes principled strategies for self-adaptations in EEG-based Brain-computer interfaces (BCIs) as a way out of the bandwidth bottleneck resulting from the considerable mismatch between the low-bandwidth interface and the bandwidth-hungry application, and a way to enable fluent and intuitive interaction in embodiment systems. The main focus is laid upon inferring the hidden target goals of users while navigating in a remote environment as a basis for possible adaptations. Approach. To reason about possible user goals, a general user-agnostic Bayesian update rule is devised to be recursively applied upon the arrival of evidences, i.e. user input and user gaze. Experiments were conducted with healthy subjects within robotic embodiment settings to evaluate the proposed method. These experiments varied along three factors: the type of the robot/environment (simulated and physical), the type of the interface (keyboard or BCI), and the way goal recognition (GR) is used to guide a simple shared control (SC) driving scheme. Main results. Our results show that the proposed GR algorithm is able to track and infer the hidden user goals with relatively high precision and recall. Further, the realized SC driving scheme benefits from the output of the GR system and is able to reduce the user effort needed to accomplish the assigned tasks. Despite the fact that the BCI requires higher effort compared to the keyboard conditions, most subjects were able to complete the assigned tasks, and the proposed GR system is additionally shown able to handle the uncertainty in user input during SSVEP-based interaction. The SC application of the belief vector indicates that the benefits of the GR module are more pronounced for BCIs, compared to the keyboard interface. Significance. Being based on intuitive heuristics that model the behavior of the general population during the execution of navigation tasks, the proposed GR method can be used without prior tuning for the

  4. Goal-recognition-based adaptive brain-computer interface for navigating immersive robotic systems.

    PubMed

    Abu-Alqumsan, Mohammad; Ebert, Felix; Peer, Angelika

    2017-06-01

    This work proposes principled strategies for self-adaptations in EEG-based Brain-computer interfaces (BCIs) as a way out of the bandwidth bottleneck resulting from the considerable mismatch between the low-bandwidth interface and the bandwidth-hungry application, and a way to enable fluent and intuitive interaction in embodiment systems. The main focus is laid upon inferring the hidden target goals of users while navigating in a remote environment as a basis for possible adaptations. To reason about possible user goals, a general user-agnostic Bayesian update rule is devised to be recursively applied upon the arrival of evidences, i.e. user input and user gaze. Experiments were conducted with healthy subjects within robotic embodiment settings to evaluate the proposed method. These experiments varied along three factors: the type of the robot/environment (simulated and physical), the type of the interface (keyboard or BCI), and the way goal recognition (GR) is used to guide a simple shared control (SC) driving scheme. Our results show that the proposed GR algorithm is able to track and infer the hidden user goals with relatively high precision and recall. Further, the realized SC driving scheme benefits from the output of the GR system and is able to reduce the user effort needed to accomplish the assigned tasks. Despite the fact that the BCI requires higher effort compared to the keyboard conditions, most subjects were able to complete the assigned tasks, and the proposed GR system is additionally shown able to handle the uncertainty in user input during SSVEP-based interaction. The SC application of the belief vector indicates that the benefits of the GR module are more pronounced for BCIs, compared to the keyboard interface. Being based on intuitive heuristics that model the behavior of the general population during the execution of navigation tasks, the proposed GR method can be used without prior tuning for the individual users. The proposed methods can be

  5. A Mediator-Based Approach to Resolving Interface Heterogeneity of Web Services

    NASA Astrophysics Data System (ADS)

    Leitner, Philipp; Rosenberg, Florian; Michlmayr, Anton; Huber, Andreas; Dustdar, Schahram

    In theory, service-oriented architectures are based on the idea of increasing flexibility in the selection of internal and external business partners using loosely-coupled services. However, in practice this flexibility is limited by the fact that partners need not only to provide the same service, but to do so via virtually the same interface in order to actually be interchangeable easily. Invocation-level mediation may be used to overcome this issue — by using mediation interface differences can be resolved transparently at runtime. In this chapter we discuss the basic ideas of mediation, with a focus on interface-level mediation. We show how interface mediation is integrated into our dynamic Web service invocation framework DAIOS, and present three different mediation strategies, one based on structural message similarity, one based on semantically annotated WSDL, and one which is embedded into the VRESCo SOA runtime, a larger research project with explicit support for service mediation.

  6. Novel protocols for P300-based brain-computer interfaces.