Prototype

Distribution by Scientific Domains
Distribution within Engineering

Kinds of Prototype

  • new prototype

  • Terms modified by Prototype

  • prototype device
  • prototype implementation
  • prototype structure
  • prototype system

  • Selected Abstracts


    TOWARD CASE-BASED REASONING FOR DIABETES MANAGEMENT: A PRELIMINARY CLINICAL STUDY AND DECISION SUPPORT SYSTEM PROTOTYPE

    COMPUTATIONAL INTELLIGENCE, Issue 3 2009
    Cindy Marling
    This paper presents a case-based decision support system prototype to assist patients with Type 1 diabetes on insulin pump therapy. These patients must vigilantly maintain blood glucose levels within prescribed target ranges to prevent serious disease complications, including blindness, neuropathy, and heart failure. Case-based reasoning (CBR) was selected for this domain because (a) existing guidelines for managing diabetes are general and must be tailored to individual patient needs; (b) physical and lifestyle factors combine to influence blood glucose levels; and (c) CBR has been successfully applied to the management of other long-term medical conditions. An institutional review board (IRB) approved preliminary clinical study, involving 20 patients, was conducted to assess the feasibility of providing case-based decision support for these patients. Fifty cases were compiled in a case library, situation assessment routines were encoded to detect common problems in blood glucose control, and retrieval metrics were developed to find the most relevant past cases for solving current problems. Preliminary results encourage continued research and work toward development of a practical tool for patients. [source]


    Programming scientific and distributed workflow with Triana services

    CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 10 2006
    David Churches
    Abstract In this paper, we discuss a real-world application scenario that uses three distinct types of workflow within the Triana problem-solving environment: serial scientific workflow for the data processing of gravitational wave signals; job submission workflows that execute Triana services on a testbed; and monitoring workflows that examine and modify the behaviour of the executing application. We briefly describe the Triana distribution mechanisms and the underlying architectures that we can support. Our middleware independent abstraction layer, called the Grid Application Prototype (GAP), enables us to advertise, discover and communicate with Web and peer-to-peer (P2P) services. We show how gravitational wave search algorithms have been implemented to distribute both the search computation and data across the European GridLab testbed, using a combination of Web services, Globus interaction and P2P infrastructures. Copyright 2005 John Wiley & Sons, Ltd. [source]


    Treat Your Organization as a Prototype: The Essence of Evidence-Based Management

    DESIGN MANAGEMENT REVIEW, Issue 3 2006
    Jeffrey Pfeffer Professor
    First page of article [source]


    Redesigning Hospital Gowns to Enhance End Users' Satisfaction

    FAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 4 2006
    KyeongSook Cho
    The design considerations for hospital gowns were investigated through a review of previous research and interviews with licensed practical nurses and patients who had been hospitalized and wore hospital gowns during their hospitalization. Two designs of prototype hospital gowns, Prototypes A and B, were proposed and users' comfort perceptions per prototype were compared to a conventional gown to evaluate their satisfaction through wear trials with 12 female participants. Prototype A featured a front opening and a back-slit overlap. Prototype B was composed of openings on the upper chest area and on the side and cap sleeves. Back opening with ties and raglan sleeves were the main features of the conventional gowns. Prototype A was more acceptable to the participants than the conventional gown. On the basis of the findings of this study, guidelines are provided for a hospital gown design to enhance the users' satisfaction. [source]


    Towards Protein Field-Effect Transistors: Report and Model of a Prototype,

    ADVANCED MATERIALS, Issue 7 2005
    G. Maruccio
    A protein field-effect transistor (Pro-FET) based on the blue-copper protein azurins (see Figure) and operating at room temperature and ambient pressure is demonstrated. The transfer characteristics of the Pro-FET exhibit a pronounced resonance due to the switch from behaving as a n-metal oxide semiconductor FET (n-MOSFET) to a p-MOSFET. Carrier transport through the device is explained in terms of an equilibrium between the two possible oxidation states of the redox site (Cu1+ and Cu2+). [source]


    Results from the Wide Angle Search for Planets Prototype (WASP0) , III.

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005
    Planet hunting in the Draco field
    ABSTRACT The Wide Angle Search for Planets Prototype (WASP0) is a wide-field instrument used to search for extra-solar planets via the transit method. Here we present the results of a monitoring program which targeted a 9-degree field in Draco. WASP0 monitored 35 000 field stars for two consecutive months. Analysis of the light curves resulted in the detection of 11 multi-transit candidates and three single-transit candidates, two of which we recommend for further follow-up. Monte Carlo simulations matching the observing parameters estimate the expected number of transit candidates from this survey. A comparison of the expected number with the number of candidates detected is used to discuss limits on planetary companions to field stars. [source]


    Structure and Photoreaction of Photoactive Yellow Protein, a Structural Prototype of the PAS Domain Superfamily,

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2007
    Yasushi Imamoto
    Photoactive yellow protein (PYP) is a water-soluble photosensor protein found in purple photosynthetic bacteria. Unlike bacterial rhodopsins, photosensor proteins composed of seven transmembrane helices and a retinal chromophore in halophilic archaebacteria, PYP is a highly soluble globular protein. The ,/, fold structure of PYP is a structural prototype of the PAS domain superfamily, many members of which function as sensors for various kinds of stimuli. To absorb a photon in the visible region, PYP has a p -coumaric acid chromophore binding to the cysteine residue via a thioester bond. It exists in a deprotonated trans form in the dark. The primary photochemical event is photo-isomerization of the chromophore from trans to cis form. The twisted cis chromophore in early intermediates is relaxed and finally protonated. Consequently, the chromophore becomes electrostatically neutral and rearrangement of the hydrogen-bonding network triggers overall structural change of the protein moiety, in which local conformational change around the chromophore is propagated to the N-terminal region. Thus, it is an ideal model for protein conformational changes that result in functional change, responding to stimuli and expressing physiological activity. In this paper, recent progress in investigation of the photoresponse of PYP is reviewed. [source]


    ChemInform Abstract: Analogues and Derivatives of Ciproxifan, a Novel Prototype for Generating Potent Histamine H3 -Receptor Antagonists.

    CHEMINFORM, Issue 4 2001
    Holger Stark
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    Three-Dimensional Printing of Complex-Shaped Alumina/Glass Composites,

    ADVANCED ENGINEERING MATERIALS, Issue 12 2009
    Wei Zhang
    Abstract Alumina/glass composites were fabricated by three-dimensional printing (3DP) and pressureless infiltration of lanthanum-alumino-silicate glass into sintered porous alumina preforms. The preforms were printed using an alumina/dextrin powder blend as a precursor material. They were sintered at 1600,C for 2,h prior to glass infiltration at 1100,C for 2,h. The influence of layer thickness and sample orientation within the building chamber of the 3D-printer on microstructure, porosity, and mechanical properties of the preforms and final composites was investigated. The increase of the layer thickness from 90 to 150,m resulted in an increase of the total porosity from ,19 to ,39,vol% and thus, in a decrease of the mechanical properties of the sintered preforms. Bending strength and elastic modulus of sintered preforms were found to attain significantly higher values for samples orientated along the Y -axis of the 3D-printer compared to those orientated along the X - or the Z -axis, respectively. Fabricated Al2O3/glass composites exhibit improved fracture toughness, bending strength, Young's modulus, and Vickers hardness up to 3.6,MPa m1/2, 175,MPa, 228,GPa, and 12,GPa, respectively. Prototypes were fabricated on the basis of computer tomography data and computer aided design data to show geometric capability of the process. [source]


    Beyond resilients, undercontrollers, and overcontrollers? an extension of personality prototype research

    EUROPEAN JOURNAL OF PERSONALITY, Issue 1 2006
    Philipp Yorck Herzberg
    Prototypes of personality were investigated in two studies. In study I, clusters of Big-Five-based prototypes were examined using a general population sample of 1908 German adults. Convergent evidence suggested the appropriateness of a five-cluster solution, which corresponds to previously identified temperament based prototypes. In study II, the five-cluster solution was cross-validated in a sample of 256 prisoners. Moreover, it was shown that a population-based approach (using discriminant functions derived from study I) was superior over the traditional sample-based cluster approach (using Ward followed by k -means). The authors argue that future typological research can be sufficiently grounded on a five-prototype conception rather than on a three-prototype conception, and suggest a new and flexible assignment procedure. Copyright 2006 John Wiley & Sons, Ltd. [source]


    Redesigning Hospital Gowns to Enhance End Users' Satisfaction

    FAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 4 2006
    KyeongSook Cho
    The design considerations for hospital gowns were investigated through a review of previous research and interviews with licensed practical nurses and patients who had been hospitalized and wore hospital gowns during their hospitalization. Two designs of prototype hospital gowns, Prototypes A and B, were proposed and users' comfort perceptions per prototype were compared to a conventional gown to evaluate their satisfaction through wear trials with 12 female participants. Prototype A featured a front opening and a back-slit overlap. Prototype B was composed of openings on the upper chest area and on the side and cap sleeves. Back opening with ties and raglan sleeves were the main features of the conventional gowns. Prototype A was more acceptable to the participants than the conventional gown. On the basis of the findings of this study, guidelines are provided for a hospital gown design to enhance the users' satisfaction. [source]


    Structural Prototypes from Seashells

    JOURNAL OF ARCHITECTURAL EDUCATION, Issue 3 2003
    JOSEPH LIM
    [source]


    Students' Drinker Prototypes and Alcohol Use in a Naturalistic Setting

    ALCOHOLISM, Issue 1 2010
    Renske Spijkerman
    Background:, Perceptions about the type of people who drink, also referred to as drinker prototypes, may strengthen young people's motivation to engage in alcohol use. Previous research has shown that drinker prototypes are related to alcohol consumption in both adolescents and young adults. However, the evidence for the strength of these relationships remains inconclusive. One of the caveats in former studies is that all insights about prototype relations are based on self-reported data from youngsters themselves, mostly gathered in a class situation, which may contain bias due to memory distortions and self-presentation concerns. Methods:, The present study examined the impact of drinker prototypes on young adults' drinking patterns by using a less obtrusive measure to assess alcohol consumption, i.e. ad lib drinking among friend groups in the naturalistic setting of a bar lab. Drinker prototypes, self-reported alcohol use in the past, and observed alcohol intake in the bar lab were assessed among 200 college students. Relations between participants' drinker prototypes and their self-reported and observed drinking behavior were examined by computing correlations and conducting multilevel analyses. Results:, Drinker prototypes were related to both self-reported and observed alcohol use. However, the drinking patterns of friend group members had a strong impact on participants' individual drinking rates in the bar lab. After these group effects had been controlled for, only heavy drinker prototypes showed relations with observed alcohol intake in the bar lab. Conclusions:, These findings further establish the value of drinker prototypes in predicting young adults' drinking behavior and suggest that people's motivation to drink alcohol in real-life drinking situations is related to their perceptions about heavy drinkers. [source]


    Mobile information retrieval with search results clustering: Prototypes and evaluations

    JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 5 2009
    Claudio Carpineto
    Web searches from mobile devices such as PDAs and cell phones are becoming increasingly popular. However, the traditional list-based search interface paradigm does not scale well to mobile devices due to their inherent limitations. In this article, we investigate the application of search results clustering, used with some success for desktop computer searches, to the mobile scenario. Building on CREDO (Conceptual Reorganization of Documents), a Web clustering engine based on concept lattices, we present its mobile versions Credino and SmartCREDO, for PDAs and cell phones, respectively. Next, we evaluate the retrieval performance of the three prototype systems. We measure the effectiveness of their clustered results compared to a ranked list of results on a subtopic retrieval task, by means of the device-independent notion of subtopic reach time together with a reusable test collection built from Wikipedia ambiguous entries. Then, we make a cross-comparison of methods (i.e., clustering and ranked list) and devices (i.e., desktop, PDA, and cell phone), using an interactive information-finding task performed by external participants. The main finding is that clustering engines are a viable complementary approach to plain search engines both for desktop and mobile searches especially, but not only, for multitopic informational queries. [source]


    Multiband meander antenna with a backed microstrip line

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007
    Jae H. Kim
    Abstract A novel multiband meander antenna with a backed microstrip line is proposed for GSM/DCS/ISM and WiMAX triple-band operations. We have used meandering technique and U-shaped line to produce the GSM and DCS bands, respectively, and a backed microstrip line technique to produce the ISM and WiMAX band. Prototypes of the multiband antennas have been successfully implemented and good radiation characteristics in the operating frequency bands have been achieved. The effect of the backed microstrip line geometry on the return loss was also studied. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1942,1946, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22582 [source]


    Novel switched sector beam planar UWB antenna

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2007
    Yuan Yao
    Abstract A planar Vivaldi array antenna that can achieve four sector radiation patterns in the azimuth plane is presented. Prototypes of the proposed antenna operating within 3.1,10.6 GHz for ultrawideband applications were designed and constructed. Measured and simulated results are used to demonstrate the performance of the antenna. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1185,1187, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22388 [source]


    Dual-band circularly polarized antenna with a QUAD-EMC structure

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
    The-Nan Chang
    Abstract In this paper, a method for obtaining a single-feed dual-band circularly polarized (CP) antenna with QUAD-EMC structure is presented. The proposed dual-band CP design was achieved by four small patches displayed on the upper surface of a first substrate, and fed electromagnetically by a large patch etched on the lower surface of the same substrate. A second FR4 and a third air substrate were added behind the first substrate to enhance the gain of the antenna. Then, by tuning the sizes of upper and lower patches and truncating patch corners respectively and properly, the proposed antenna can perform dual-band CP radiation using a single probe feed. Prototypes of the proposed antennas designed for RFID operations in the 915-MHz and 2.45-GHz bands are presented and experimentally demonstrated. 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 645,647, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22231 [source]


    Chlorin,Bacteriochlorin Energy-transfer Dyads as Prototypes for Near-infrared Molecular Imaging Probes: Controlling Charge-transfer and Fluorescence Properties in Polar Media

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009
    Hooi Ling Kee
    The photophysical properties of two energy-transfer dyads that are potential candidates for near-infrared (NIR) imaging probes are investigated as a function of solvent polarity. The dyads (FbC-FbB and ZnC-FbB) contain either a free base (Fb) or zinc (Zn) chlorin (C) as the energy donor and a free base bacteriochlorin (B) as the energy acceptor. The dyads were studied in toluene, chlorobenzene, 1,2-dichlorobenzene, acetone, acetonitrile and dimethylsulfoxide (DMSO). In both dyads, energy transfer from the chlorin to bacteriochlorin occurs with a rate constant of ,(5,10 ps),1 and a yield of >99% in nonpolar and polar media. In toluene, the fluorescence yields (,f = 0.19) and singlet excited-state lifetimes (,,5.5 ns) are comparable to those of the benchmark bacteriochlorin. The fluorescence yield and excited-state lifetime decrease as the solvent polarity increases, with quenching by intramolecular electron (or hole) transfer being greater for FbC-FbB than for ZnC-FbB in a given solvent. For example, the ,f and , values for FbC-FbB in acetone are 0.055 and 1.5 ns and in DMSO are 0.019 and 0.28 ns, whereas those for ZnC-FbB in acetone are 0.12 and 4.5 ns and in DMSO are 0.072 and 2.4 ns. The difference in fluorescence properties of the two dyads in a given polar solvent is due to the relative energies of the lowest energy charge-transfer states, as assessed by ground-state redox potentials and supported by molecular-orbital energies derived from density functional theory calculations. Controlling the extent of excited-state quenching in polar media will allow the favorable photophysical properties of the chlorin,bacteriochlorin dyads to be exploited in vivo. These properties include very large Stokes shifts (85 nm for FbC-FbB, 110 nm for ZnC-FbB) between the red-region absorption of the chlorin and the NIR fluorescence of the bacteriochlorin (,f = 760 nm), long bacteriochlorin excited-state lifetime (,5.5 ns), and narrow (,20 nm) absorption and fluorescence bands. The latter will facilitate selective excitation/detection and multiprobe applications using both intensity- and lifetime-imaging techniques. [source]


    Porous silicon-based potentiometric biosensor for triglycerides

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007
    S. Setzu
    Abstract In this paper we report on the fabrication and characterization of a potentiometric biosensor for the detection of triglycerides. This is constituted by a lipase immobilized on a mesoporous Si matrix. Prototypes, realized on 1 1 cm n+ -type silicon wafers, show a very high enzymatic activity. Moreover the properties of these biosensors have been shown to be stable in a several months time interval, clearly showing their advantages with respect to traditional triglycerides detection systems. The Michaelis Menten curve is obtained to demonstrate the absence of diffusion problems. Potentiometric measurements are also shown. ( 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Prototypes for building applications based on thermoplastic composites containing mixed waste plastics

    POLYMER COMPOSITES, Issue 2 2002
    M. Xanthos
    Automotive shredder residue (ASR) and a complex residue obtained as a by-product in the tertiary recycling of nylon-6 fibers from used carpets were evaluated as potential additives in thermoplastic composites to be used for building applications. Prototype blocks were prepared by the "intrusion" process using various ratios of the waste streams and low-density polyethylene (LDPE) in the absence of compatibilizers. Hence, product morphologies and corresponding properties were largely controlled through processing. They were evaluated for their short-term and longterm mechanical properties, flammability, thermal conductivity, and heavy-metal and total organic carbon leaching characteristics. Encapsulation of the waste feedstock by LDPE during molding in a single-screw extruder significantly reduced the leachable content. In an effort to further reduce the leachable content, the mixtures were processed in two stages by precompounding in adevolatilizing twin-screw extruder prior to molding. In comparison to the as-received wastes, improved homogenization decreased the leachable heavy-metal content by at least 98%. The carpet residue feedstock consisting of polypropylene, styrene-butadiene rubber and calcium carbonate appears to be an attractive low-cost, high-volume material with consistent properties and could be used as filler in thermoplastic composites. Comparison of their performance characteristics suggested that the carpet residue composites would be favored versus ASR composites as replacement of the wood thermal barrier components in a novel steel-based stud assembly. [source]


    Patterns, Fabrics, Prototypes, Tessellations

    ARCHITECTURAL DESIGN, Issue 6 2009
    Alejandro Zaera-Polo
    Abstract New technologies have enabled architects to develop sophisticated patterning techniques. This is epitomised by the expressive possibilities now available to the building envelope: smooth geometries, tessellation, material textures and layers, such as solar shading. For Alejandro Zaera-Polo of Foreign Office Architects, though, patterns have cultural and political possibilities far beyond mere decoration, enabling new practices to address in the urban context some of the crucial problems posed by globalisation: bridging the dichotomy between tabula rasa and contextualism, and the articulation between the local and global. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Design, Synthesis, and Pharmacological Investigation of Iodined Salicylimines, New Prototypes of Antimicrobial Drug Candidates

    ARCHIV DER PHARMAZIE, Issue 5 2010
    Suo-Ping Xu
    Abstract A series of 3,5-diiodo-salicylalidene Schiff bases (compounds 1,35) has been synthesized and tested for antimicrobial activity. The compounds were assayed for antibacterial activities by the MTT method. Some of the compounds inhibit the growth of a broad range of bacteria including the species of Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae. Among them, compounds 2-[(4-chloro-phenylimino)methyl]-4,6-diiodo-phenol 11 and 2,4-diiodo-6-[(2-morpholin-4-yl-ethylimino)methyl]phenol 19 showed the most potent antibacterial activity with MIC of 3.1, 12.9, 3.3, 6.5, 12.9, 3.3 and 3.2, 12.8, 3.2, 12.8, 12.8, 3.2 ,M against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. Coli, and E. cloacae, respectively. [source]


    ChemInform Abstract: A [2]Catenane and a [2]Rotaxane as Prototypes of Topologial and Euclidean Molecular "Rubber Gloves".

    CHEMINFORM, Issue 6 2002
    Jean-Claude Chambron
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    Automated Negotiation from Declarative Contract Descriptions

    COMPUTATIONAL INTELLIGENCE, Issue 4 2002
    Daniel M. Reeves
    Our approach for automating the negotiation of business contracts proceeds in three broad steps. First, determine the structure of the negotiation process by applying general knowledge about auctions and domain,specific knowledge about the contract subject along with preferences from potential buyers and sellers. Second, translate the determined negotiation structure into an operational specification for an auction platform. Third, after the negotiation has completed, map the negotiation results to a final contract. We have implemented a prototype which supports these steps by employing a declarative specification (in courteous logic programs) of (1) high,level knowledge about alternative negotiation structures, (2) general,case rules about auction parameters, (3) rules to map the auction parameters to a specific auction platform, and (4) special,case rules for subject domains. We demonstrate the flexibility of this approach by automatically generating several alternative negotiation structures for the domain of travel shopping in a trading agent competition. [source]


    A social agent pedestrian model

    COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3-4 2008
    Andrew Park
    Abstract This paper presents a social agent pedestrian model based on experiments with human subjects. Research studies of criminology and environmental psychology show that certain features of the urban environment generate fear in people, causing them to take alternate routes. The Crime Prevention Through Environmental Design (CPTED) strategy has been implemented to reduce fear of crime and crime itself. Our initial prototype of a pedestrian model was developed based on these findings of criminology research. In the course of validating our model, we constructed a virtual environment (VE) that resembles a well-known fear-generating area where several decision points were set up. 60 human subjects were invited to navigate the VE and their choices of routes and comments during the post interviews were analyzed using statistical techniques and content analysis. Through our experimental results, we gained new insights into pedestrians' behavior and suggest a new enhanced and articulated agent model of a pedestrian. Our research not only provides a realistic pedestrian model, but also a new methodology for criminology research. Copyright 2008 John Wiley & Sons, Ltd. [source]


    Improving realism of a surgery simulator: linear anisotropic elasticity, complex interactions and force extrapolation

    COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2002
    Guillaume Picinbono
    Abstract In this article, we describe the latest developments of the minimally invasive hepatic surgery simulator prototype developed at INRIA. The goal of this simulator is to provide a realistic training test bed to perform laparoscopic procedures. Therefore, its main functionality is to simulate the action of virtual laparoscopic surgical instruments for deforming and cutting tridimensional anatomical models. Throughout this paper, we present the general features of this simulator including the implementation of several biomechanical models and the integration of two force-feedback devices in the simulation platform. More precisely, we describe three new important developments that improve the overall realism of our simulator. First, we have developed biomechanical models, based on linear elasticity and finite element theory, that include the notion of anisotropic deformation. Indeed, we have generalized the linear elastic behaviour of anatomical models to ,transversally isotropic' materials, i.e. materials having a different behaviour in a given direction. We have also added to the volumetric model an external elastic membrane representing the ,liver capsule', a rather stiff skin surrounding the liver, which creates a kind of ,surface anisotropy'. Second, we have developed new contact models between surgical instruments and soft tissue models. For instance, after detecting a contact with an instrument, we define specific boundary constraints on deformable models to represent various forms of interactions with a surgical tool, such as sliding, gripping, cutting or burning. In addition, we compute the reaction forces that should be felt by the user manipulating the force-feedback devices. The last improvement is related to the problem of haptic rendering. Currently, we are able to achieve a simulation frequency of 25,Hz (visual real time) with anatomical models of complex geometry and behaviour. But to achieve a good haptic feedback requires a frequency update of applied forces typically above 300,Hz (haptic real time). Thus, we propose a force extrapolation algorithm in order to reach haptic real time. Copyright 2002 John Wiley & Sons, Ltd. [source]


    Reinterpretable Imager: Towards Variable Post-Capture Space, Angle and Time Resolution in Photography

    COMPUTER GRAPHICS FORUM, Issue 2 2010
    Amit Agrawal
    Abstract We describe a novel multiplexing approach to achieve tradeoffs in space, angle and time resolution in photography. We explore the problem of mapping useful subsets of time-varying 4D lightfields in a single snapshot. Our design is based on using a dynamic mask in the aperture and a static mask close to the sensor. The key idea is to exploit scene-specific redundancy along spatial, angular and temporal dimensions and to provide a programmable or variable resolution tradeoff among these dimensions. This allows a user to reinterpret the single captured photo as either a high spatial resolution image, a refocusable image stack or a video for different parts of the scene in post-processing. A lightfield camera or a video camera forces a-priori choice in space-angle-time resolution. We demonstrate a single prototype which provides flexible post-capture abilities not possible using either a single-shot lightfield camera or a multi-frame video camera. We show several novel results including digital refocusing on objects moving in depth and capturing multiple facial expressions in a single photo. [source]


    A Hierarchical Topology-Based Model for Handling Complex Indoor Scenes

    COMPUTER GRAPHICS FORUM, Issue 2 2006
    D. Fradin
    Abstract This paper presents a topology-based representation dedicated to complex indoor scenes. It accounts for memory management and performances during modelling, visualization and lighting simulation. We propose to enlarge a topological model (called generalized maps) with multipartition and hierarchy. Multipartition allows the user to group objects together according to semantics. Hierarchy provides a coarse-to-fine description of the environment. The topological model we propose has been used for devising a modeller prototype and generating efficient data structure in the context of visualization, global illumination and 1 GHz wave propagation simulation. We presently handle buildings composed of up to one billion triangles. [source]


    Toward a Trust-Based Construction Management

    COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2010
    Annie Guerriero
    Moreover, the uncertainty linked to the environment of the construction activity makes way for the notion of trust. The coordinator can make use of multiple tools/views for accomplishing his mission. This research work suggests analyzing data coming from these different views to consolidate trust indicators informing the coordinator about "trust in the correct progression of the construction activity." The approach suggested in this article distinguishes between four aspects of the activity determining the global trust level: task progress, actor's performance, documents required to perform the task, and building elements resulting from the task. The proposal suggests introducing these trust indicators in a dashboard, included in a multiview interface, thus allowing the coordinator to identify the tasks with a low trust level and to understand the nature of dysfunctions. A prototype has been developed and integrated in a service-based IT infrastructure. Results of an experiment stage are finally discussed to validate the approach. [source]


    Case,Based Reasoning for Assessing Intelligent Transportation Systems Benefits

    COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2003
    Adel Sadek
    Existing transportation planning modeling tools have critical limitations with respect to assessing the benefits of intelligent transportation systems (ITS) deployment. In this article, we present a novel framework for developing modeling tools for quantifying ITS deployments benefits. This approach is based on using case,based reasoning (CBR), an artificial intelligence paradigm, to capture and organize the insights gained from running a dynamic traffic assignment (DTA) model. To demonstrate the feasibility of the approach, the study develops a prototype system for evaluating the benefits of diverting traffic away from incident locations using variable message signs. A real,world network from the Hartford area in Connecticut is used in developing the system. The performance of the prototype is evaluated by comparing its predictions to those obtained using a detailed DTA model. The prototype system is shown to yield solutions comparable to those obtained from the DTA model, thus demonstrating the feasibility of the approach. [source]