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101.
Ian R. Chittick Joaquim R. R. A. Martins 《Structural and Multidisciplinary Optimization》2008,36(1):59-70
A new subspace optimization method for performing aero-structural design is introduced. The method relies on a semi-analytic
adjoint approach to the sensitivity analysis that includes post-optimality sensitivity information from the structural optimization
subproblem. The resulting coupled post-optimality sensitivity approach is used to guide a gradient-based optimization algorithm.
The new approach simplifies the system-level problem, thereby reducing the number of calls to a potentially costly aerodynamics
solver. The aero-structural optimization of an aircraft wing is performed using linear aerodynamic and structural analyses,
and a performance comparison is made between the new approach and the conventional multidisciplinary feasible method. The
new asymmetric suboptimization method is found to be the more efficient approach when it adequately reduces the number of
system evaluations or when there is a large enough discrepancy between disciplinary solution times. 相似文献
102.
A novel induction motor control scheme using IDA-PBC 总被引:3,自引:1,他引:2
Humberto GONZALEZ Manuel A. DUARTE-MERMOUD Ian PELISSIER Juan Carlos TRAVIESO-TORRES Romeo ORTEGA 《控制理论与应用(英文版)》2008,6(1):59-68
A new control scheme for induction motors is proposed in the present paper, applying the interconnection and damping assignment-passivity based control (IDA-PBC) method. The scheme is based exclusively on passivity based control, without restricting the input frequency as it is done in field oriented control (FOC). A port-controlled Hamiltonian (PCH) model of the induction motor is deduced to make the interconnection and damping of energy explicit on the scheme. The proposed controller is validated under computational simulations and experimental tests using an inverter prototype. 相似文献
103.
104.
105.
Ian Foster 《计算机科学技术学报》2006,21(4):513-520
The Globus Toolkit (GT) has been developed since the late 1990s to support the development of serviceoriented distributed computing applications and infrastructures. Core GT components address, within a common framework, fundamental issues relating to security, resource access, resource management, data movement, resource discovery, and so forth. These components enable a broader "Globus ecosystem" of tools and components that build on, or interoperate with, GT functionality to provide a wide range of useful application-level functions. These tools have in turn been used to develop a wide range of both "Grid" infrastructures and distributed applications. I summarize here the principal characteristics of the recent Web Services-based GT4 release, which provides significant improvements over previous releases in terms of robustness, performance,, usability, documentation, standards compliance, and functionality. I also introduce the new "dev.globus" community development process, which allows a larger community to contribute to the development of Globus software. 相似文献
106.
Chen M Botchen RP Hashim RR Weiskopf D Ertl T Thornton IM 《IEEE transactions on visualization and computer graphics》2006,12(5):1093-1100
Video visualization is a computation process that extracts meaningful information from original video data sets and conveys the extracted information to users in appropriate visual representations. This paper presents a broad treatment of the subject, following a typical research pipeline involving concept formulation, system development, a path-finding user study, and a field trial with real application data. In particular, we have conducted a fundamental study on the visualization of motion events in videos. We have, for the first time, deployed flow visualization techniques in video visualization. We have compared the effectiveness of different abstract visual representations of videos. We have conducted a user study to examine whether users are able to learn to recognize visual signatures of motions, and to assist in the evaluation of different visualization techniques. We have applied our understanding and the developed techniques to a set of application video clips. Our study has demonstrated that video visualization is both technically feasible and cost-effective. It has provided the first set of evidence confirming that ordinary users can be accustomed to the visual features depicted in video visualizations, and can learn to recognize visual signatures of a variety of motion events. 相似文献
107.
Summary The thermal cure of a monofunctional maleimide N-(4-phenoxy)-phenylmaleimid (1) was examined using differential scanning calorimetry (DSC). The analogous bis-maleimide bis-(4-maleimidophenyl)ether (2) was also analyzed in the same manner for comparison. Polymerization kinetics derived from scanning DSC measurements showed an order of reaction varying between n=1 and 2 for (1), compared to an order of reaction between n=2 and 3 (by multiple linear regression analysis) for (2). The overall enthalpy of polymerization (Ho) for N-(4-phenoxy)-phenylmaleimide (94kJ/mole) agrees well with that obtained for maleimide itself (89kJ/mole) using conventional calorimetric techniques indicating that polymerization appears complete within the timescale of the experiment. In contrast the analogous BMI displays a markedly lower overall polymerization enthalpy (ca. 66kJ/mole) indicating an apparent conversion of only 37%. 相似文献
108.
109.
Montesinos CA Tse ZT Chan YJ Elhawary H Rea M Hamed A Young I Lamperth M 《Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine》2012,226(1):49-54
The static magnetic field of a magnetic resonance imaging scanner can be distorted by the presence of materials, perturbing the spatial encoding process in magnetic resonance imaging and often resulting in image artifacts. The relationship between the image artifact size and magnetic susceptibility of the material specimen is of interest to engineers for the design of devices that are to be compatible with the imaging volume of the scanner. In this study, a finite-element method was used to simulate the distorted magnetic field of samples with different susceptibilities. With the knowledge of the external- and self- magnetic field interactions, a Lorentz correction was applied to compute the magnetic field deviation. The simulated results were then validated by the corresponding experimental magnetic resonance images. 相似文献
110.
Andrew J. Berry Jeremy Howitt Da-Wei Gu Ian Postlethwaite 《Journal of Intelligent and Robotic Systems》2012,66(4):477-494
As the complexity of an unmanned vehicle’s operational environment increases so does the need to consider the obstacle space
continually, and this is aided by splitting the motion planning functionality into distinct global and local layers. This
paper presents a new continuous local motion planning framework, where the output and control space elements of the traditional
receding horizon control problem are separated into distinct layers. This separation reduces the complexity of the local motion
trajectory optimisation, enabling faster design and increased horizon length. The focus of this paper is on the output space
component of this framework. Bezier polynomial functions are used to describe local motion trajectories which are constrained
to vehicle performance limits and optimised to track a global trajectory. Development and testing is in simulation, targeted
at a nonlinear model of a quadrotor unmanned air vehicle. The defined framework is used to provide situation-aware tracking of a global trajectory in the presence of static and dynamic obstacles, as well as realistic turbulence and gusts.
Also demonstrated is the immediate-term decentralised deconfliction of multiple unmanned vehicles, and multiple formations of unmanned vehicles. 相似文献