Home About us Contact
|
Home About us Contact | ||
|
|
||
Mapping Algorithm (mapping + algorithm)
Selected AbstractsA Self-Consistent Bathymetric Mapping AlgorithmJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1-2 2007Chris Roman The achievable accuracy of bathymetric mapping in the deep ocean using robotic systems is most often limited by the available guidance or navigation information used to combine the measured sonar ranges during the map making process. This paper presents an algorithm designed to mitigate the affects of poor ground referenced navigation by applying the principles of map registration and pose filtering commonly used in simultaneous localization and mapping (SLAM) algorithms. The goal of the algorithm is to produce a self-consistent point cloud representation of the bottom terrain with errors that are on a scale similar to the sonar range resolution rather than any direct positioning measurement. The presented algorithm operates causally and utilizes sensor data that are common to instrumented underwater robotic vehicles used for mapping and scientific explorations. Real world results are shown for data taken on several expeditions with the JASON remotely operated vehicle (ROV). Comparisons are made between more standard mapping approaches and the proposed method is shown to significantly improve the map quality and reveal scene information that would have otherwise been obscured due to poor direct navigation information. © 2007 Wiley Periodicals, Inc. [source] Concurrent workload mapping for multicore security systemsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 10 2009Benfano Soewito Abstract Multicore based network processors are promising components to build real-time and scalable security systems to protect the networks and systems. The parallel nature of the processing system makes it challenging for application developers to concurrently program security systems for high performance. In this paper we present an automatic programming methodology that considers application complexity, traffic variation, and attack signatures update. In particular, our mapping algorithm concurrently takes advantage of parallelism in the level of tasks, applications, and packets to achieve optimal performance. We present results that show the effectiveness of the analysis, mapping, and the performance of the model methodology. Copyright © 2009 John Wiley & Sons, Ltd. [source] A static mapping heuristics to map parallel applications to heterogeneous computing systemsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 13 2005Ranieri Baraglia Abstract In order to minimize the execution time of a parallel application running on a heterogeneously distributed computing system, an appropriate mapping scheme is needed to allocate the application tasks to the processors. The general problem of mapping tasks to machines is a well-known NP-hard problem and several heuristics have been proposed to approximate its optimal solution. In this paper we propose a static graph-based mapping algorithm, called Heterogeneous Multi-phase Mapping (HMM), which permits suboptimal mapping of a parallel application onto a heterogeneous computing distributed system by using a local search technique together with a tabu search meta-heuristic. HMM allocates parallel tasks by exploiting the information embedded in the parallelism forms used to implement an application, and considering an affinity parameter, that identifies which machine in the heterogeneous computing system is most suitable to execute a task. We compare HMM with some leading techniques and with an exhaustive mapping algorithm. We also give an example of mapping of two real applications using HMM. Experimental results show that HMM performs well demonstrating the applicability of our approach. Copyright © 2005 John Wiley & Sons, Ltd. [source] The least-squares meshfree method for elasto-plasticity and its application to metal forming analysisINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2005Kie-Chan Kwon Abstract A new meshfree method for the analysis of elasto-plastic deformation is presented. The method is based on the proposed first-order least-squares formulation for elasto-plasticity and the moving least-squares approximation. The least-squares formulation for classical elasto-plasticity and its extension to an incrementally objective formulation for finite deformation are proposed. In the formulation, equilibrium equation and flow rule are enforced in least-squares sense, i.e. their squared residuals are minimized, and hardening law and loading/unloading condition are enforced pointwise at each integration point. The closest point projection method for the integration of rate-form constitutive equation is inherently involved in the formulation, and thus the radial-return mapping algorithm is not performed explicitly. The proposed formulation is a mixed-type method since the residuals are represented in a form of first-order differential system using displacement and stress components as nodal unknowns. Also the penalty schemes for the enforcement of boundary and frictional contact conditions are devised and the reshaping of nodal supports is introduced to avoid the difficulties due to the severe local deformation near contact interface. The proposed method does not employ structure of extrinsic cells for any purpose. Through some numerical examples of metal forming processes, the validity and effectiveness of the method are discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Simple modifications for stabilization of the finite point methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2005B. Boroomand Abstract A stabilized version of the finite point method (FPM) is presented. A source of instability due to the evaluation of the base function using a least square procedure is discussed. A suitable mapping is proposed and employed to eliminate the ill-conditioning effect due to directional arrangement of the points. A step by step algorithm is given for finding the local rotated axes and the dimensions of the cloud using local average spacing and inertia moments of the points distribution. It is shown that the conventional version of FPM may lead to wrong results when the proposed mapping algorithm is not used. It is shown that another source for instability and non-monotonic convergence rate in collocation methods lies in the treatment of Neumann boundary conditions. Unlike the conventional FPM, in this work the Neumann boundary conditions and the equilibrium equations appear simultaneously in a weight equation similar to that of weighted residual methods. The stabilization procedure may be considered as an interpretation of the finite calculus (FIC) method. The main difference between the two stabilization procedures lies in choosing the characteristic length in FIC and the weight of the boundary residual in the proposed method. The new approach also provides a unique definition for the sign of the stabilization terms. The reasons for using stabilization terms only at the boundaries is discussed and the two methods are compared. Several numerical examples are presented to demonstrate the performance and convergence of the proposed methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] Input mapping algorithm for parallel transistor structuresINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 7 2009Spiridon NikolaidisArticle first published online: 17 JUL 200 Abstract A new algorithm for mapping every possible input pattern of a parallel transistor structure to an equivalent set of normalized inputs (having the same starting and ending point) is introduced. This algorithm is based on the analysis of the operation of the transistor structure and can be used for the development of analytical timing models for CMOS circuits. Simulation results show a very good accuracy of the algorithm. Copyright © 2008 John Wiley & Sons, Ltd. [source] Health-related utility among adults with atopic dermatitis treated with 0·1% tacrolimus ointment as maintenance therapy over the long term: findings from the Protopic® CONTROL studyBRITISH JOURNAL OF DERMATOLOGY, Issue 6 2009C.D. Poole Summary Background, Long-term maintenance treatment with 0·1% tacrolimus ointment for the prevention of flares has been demonstrated to be well tolerated and effective in adults for the treatment of atopic dermatitis (AD) but its impact on health-related utility has not been reported. Objectives, The purpose of this study was to estimate utility changes associated with the use of tacrolimus ointment in the maintenance treatment of adults with AD. Methods, Data were collected from a clinical trial investigating long-term maintenance treatment with 0·1% tacrolimus ointment in adults with AD. All patients were treated with twice-daily tacrolimus ointment during an open-label period (OLP) of up to 6 weeks, with subsequent randomization to a double-blind disease-control period (DCP) of 12 months comparing tacrolimus ointment, used twice weekly as maintenance treatment, vs. the emollient vehicle as standard treatment. Health-related utility (EQ-5Dindex) was estimated by Monte Carlo simulation from SF-12 responses by application of a published response mapping algorithm and the U.K. tariff for EQ-5D responses and SF-6D responses, respectively. Results, Evaluable data were available for 257 patients stratified into mild, moderate or severe AD with a median age at screening of 28 years [interquartile range (IQR) 22,38] and 40% male. At screening the median EQ-5Dindex across the strata was 0·848 units (IQR 0·704,0·882) for mild cases, 0·796 (0·737,0·876) for moderate cases, and 0·760 (0·661,0·823, P < 0·001) for those with severe disease. At the end of the OLP, mean utility improvement across all strata was 0·027 [95% confidence interval (CI) ,0·011 to 0·065, P = 0·165] for mild cases, 0·046 (95% CI 0·015,0·064, P = 0·002) for moderate cases and 0·076 (95% CI 0·035,0·118, P < 0·001) for those with severe disease. At the end of the blinded DCP, repeated measures analysis showed an age- and sex-adjusted mean change of 0·045 units (P < 0·001) for subjects treated with tacrolimus ointment over those treated with emollient vehicle. Conclusions, Patients with AD of all severities showed considerable decrements in health-related utility. However, treatment with 0·1% tacrolimus ointment was associated with clinically significant improvement in health-related utility for patients with moderate and severe AD, which was sustained over a 12-month maintenance period compared with those using standard treatment with an emollient vehicle. [source] | ||||||||||