The IETF has recently advanced the IPsec protocols to draft standard status. These protocols include mechanisms for the establishment of a secure channel, via cryptographic key exchange, over an insecure medium. Such ...
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The IETF has recently advanced the IPsec protocols to draft standard status. These protocols include mechanisms for the establishment of a secure channel, via cryptographic key exchange, over an insecure medium. Such a channel can then be used for ensuring the confidentiality, authentication, and/or integrity of the communications between two parties. In this article we explain the algorithms and protocols of IPsec's Internet Key Exchange and discuss the types of security that the various IKE modes provide.
As model checking becomes increasingly used in industry, there is a big need for efficient new methods to deal with the large real-size designs. The author presents a novel method for improving the performance of mode...
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As model checking becomes increasingly used in industry, there is a big need for efficient new methods to deal with the large real-size designs. The author presents a novel method for improving the performance of model checking using parallelisation techniques. The model checking is performed on a distributed-memory environment consisting of a network of machines. The important two keys to focus on are the memory balance and communication reduction. A new algorithm for partitioning the large state space modelling industrial designs with hundreds of millions of states and transitions is proposed. The state space is supposed to be represented by a weighted Kripke structure (this is an extension of the Kripke structure where weights are associated with the states and with the transitions). This algorithm partitions the weighted Kripke structure by performing a combination of abstraction-partition-refinement on this structure. The CTL model checking algorithm is distributed on processes located on different network machines. Each one owns a partition and executes the algorithm on it. The algorithm for CTL model checking is designed to reduce the communication overhead between the processes. The experimental results on large real designs show that this method improves the quality of partitions, the communication overhead and then the overall performance of the model checking.
This paper proposes an adaptive boundary control to an axially moving string system, which couples with a mass-damper-spring (MDS) controller at its right-hand-side (RHS) boundary. Unknown parameters appearing in the ...
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This paper proposes an adaptive boundary control to an axially moving string system, which couples with a mass-damper-spring (MDS) controller at its right-hand-side (RHS) boundary. Unknown parameters appearing in the system equation are assumed constant and estimated on-line by using adaptation laws. The adaptive computed-torque control algorithm applied to robot manipulators of lumped systems is extended to design the adaptive boundary controller for the coupling system. It is found that the control force and update laws depend only on the displacement, velocity and slope of the string at the RHS boundary. Lyapunov stability guarantees the convergence of the tracking error to zero. Finally, the performance of the proposed controller is demonstrated by numerical simulations.
The current trends in development and deployment of advanced micro- and miniscale electromechanical systems (MEMS) have facilitated the unified fundamental, applied, and experimental research activities in the analysi...
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The current trends in development and deployment of advanced micro- and miniscale electromechanical systems (MEMS) have facilitated the unified fundamental, applied, and experimental research activities in the analysis and design of state-of-the-art motion devices (rotational and translational electromechanical motion devices), integrated circuits (ICs), and controllers. The objectives of this paper are to design, develop, and compare different control algorithms for high-performance MEMS with permanent-magnet rotational servo-motors controlled by ICs (VLSI driver-controller is fabricated using CMOS technology). The problems to be solved are very challenging because a number of long-standing issues in design, hardware integration, control, nonlinear analysis, and robustness have to be solved. The major emphases of this paper are the analysis and design of robust servo-systems, as well as the comparison of the dynamic performance of closed-loop MEMS with different control algorithms. We. synthesize, verify, and test proportional-integral, integral with state feedback extension, relay, and sliding mode controllers. It is illustrated that the sliding mode control laws drive the states and tracking error to the switching surface and maintain (keep) the states and tracking error within this nonlinear switching surface in spite of different references, disturbances, parameter variations, and uncertainties. That is, robust tracking, desired accuracy, and disturbance attenuation are achieved. We report the experimental setup which was built to perform the advanced studies of high-performance MEMS. The testbed was built to integrate permanent-magnet microscale servo-motor and ICs (driver-controller). (C) 2002 Published by Elsevier Science Ltd.
We have designed and implemented a system for real-time detection of 2-D image features on a reconfigurable computer based on Field Programmable Gate Arrays (FPGA's). We envision this device as the front-end of a ...
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We have designed and implemented a system for real-time detection of 2-D image features on a reconfigurable computer based on Field Programmable Gate Arrays (FPGA's). We envision this device as the front-end of a system able to track image features in real-time vision applications like autonomous vehicle navigation and "structure from motion". The algorithm employed to select good features is inspired by the method of Tomasi and Kanade. Compared to the original method, the algorithm that we have devised does not require any floating point or transcendental operations, and maps efficiently into a highly pipelined architecture, well suited to be implemented in FPGA technology. We have implemented the algorithm on a low-cost reconfigurable computer equipped with video decoder and encoder interfaces. Reliable operation has been observed on an image stream generated by a standard NTSC commercial video camera at 30 Hz on different scenes and under different light conditions. This result compares favorably to the implementation of the same algorithm on a system based on the TI C80 DSP, able to process at most 5 frames/second.
Delta/hexagonal phase shifting transformer (PST) represents both magnetically coupled and electrically connected circuits, which makes it unique in design and construction from a standard transformer. Conventionally, ...
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Delta/hexagonal phase shifting transformer (PST) represents both magnetically coupled and electrically connected circuits, which makes it unique in design and construction from a standard transformer. Conventionally, differential protection serves as a main protection element of PST and offers distinguished features such as speed and selectivity. On the contrary, it is prone to various new challenges in addition to well-recognised traditional ones when applied to delta/hexagonal PST. New challenges include non-standard phase shift between two ends, saturation of the series winding, dependence of differential/ restraining currents on tap changer position and turn-turn fault detection. This study exploits the unique design of PST and explores the suitability of applying electromagnetic equations by presenting a new algorithm for the protection of PST. In addition to the internal/external fault detection and discrimination capability, unlike differential protection, the proposed algorithm remains stable during magnetisation inrush current, current transformer saturation and saturation of the series winding. Even though the implementation of the proposed algorithm requires currents, voltages and tracking of the tap-changer position, capabilities of the algorithm make it a distinguished and unique protection solution. Performance of the algorithm is tested and analysed for various fault and non-faulted power system conditions using power systems computer aided design/electromagnetic transient including DC (PSCAD/EMTDC) software.
作者：
Chaudhary, AnkitRaheja, J. L.BITS
Dept Comp Sci Comp Vis Res Grp Pilani Rajasthan India CSIR
Cent Elect Engn Res Inst Digital Syst Grp Machine Vis Lab Pilani Rajasthan India
The shape of human hand is such that it can perform many tedious tasks easily. It can reach narrow places and can perform difficult operations. It can bend its fingers at different angles to pick or hold different obj...
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The shape of human hand is such that it can perform many tedious tasks easily. It can reach narrow places and can perform difficult operations. It can bend its fingers at different angles to pick or hold different objects and apply force via fingers or palm area. It is very helpful in many difficult applications. However, there is risk of injury to the human hand, or even life in dangerous operations. It is not advisable to gamble of human body parts for applications like land mine removal. Hence, there is a need of a robotic hand which can perform the same operation as a human hand does in real time. This paper discusses a vision-based technique of controlling a robotic hand which has human hand like joints in fingers. The user has to show a gesture to the system with bare hand without any limitation on hand direction and the robotic hand would mimic that gesture. The positions of human hand fingers were calculated using supervised Artificial Neural Network. The preprocessing made the whole algorithm faster by cropping the region of interest from input image frame. The gesture was extracted from the input image and fingertips, centre of palm were detected. The animated simulation of robotic hand is done in Blender software. (C) 2012 Elsevier Ltd. All rights reserved.
V-variable fractals and superfractals have recently been introduced by Barnsley [Barnsley Michael, Hutchinson John, Stenflo Orjan. A fractal valued random iteration algorithm and fractal hierarchy. Fractals 2005;13(2)...
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V-variable fractals and superfractals have recently been introduced by Barnsley [Barnsley Michael, Hutchinson John, Stenflo Orjan. A fractal valued random iteration algorithm and fractal hierarchy. Fractals 2005;13(2):111-46 [MR2151094 (2006b:28014)]] to the world of mathematics and computer graphics. In this paper, we introduce superior iterates to study the role of contractive and non-contractive operators in relation to superfractals. A modified algorithm along with details of computer implementation is also provided to compute V-variable fractals. A brief discussion about the various aspects of the computed figures indicates usefulness of the study. (C) 2009 Elsevier Ltd. All rights reserved.
This paper proposes an innovative simultaneous localization and mapping (SLAM) algorithm which combines a strong tracking filter (STF), an unscented Kalman filter (UKF), and a particle filter (PF) to deal with the low...
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This paper proposes an innovative simultaneous localization and mapping (SLAM) algorithm which combines a strong tracking filter (STF), an unscented Kalman filter (UKF), and a particle filter (PF) to deal with the low accuracy of unscented FastSLAM (UFastSLAM). UFastSLAM lacks the capacity for online self-adaptive adjustment, and it is easily influenced by uncertain noise. The new algorithm updates each Sigma point in UFastSLAM by an adaptive algorithm and obtains optimized filter gain by the STF adjustment factor. It restrains the influence of uncertain noise and initial selection. Therefore, the state estimation would converge to the true value rapidly and the accuracy of system state estimation would be improved eventually. The results of simulations and practical tests show that strong tracking unscented FastSLAM (STUFastSLAM) has a significant improvement in accuracy and robustness.
This paper describes a modified particle swarm optimization (MPSO) for the synthesis of the low sidelobe concentric ring arrays. The MPSO has been utilized to optimize the element placement in a concentric ring array ...
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This paper describes a modified particle swarm optimization (MPSO) for the synthesis of the low sidelobe concentric ring arrays. The MPSO has been utilized to optimize the element placement in a concentric ring array to obtain the lowest peak sidelobe level (PSLL). And here the multiple optimization constraints include the array aperture, the minimum ring spacing and the element spacing in each ring. Unlike standard PSO using fixed corresponding relationship between the optimal variables and their coding, the MPSO utilized the coding resetting of optimal variables to avoid infeasible solution during the optimization process. Also, the proposed approach has reduced the size of the searching area of the PSO by means of indirect description of individual. The simulated results confirming the great efficiency and robustness of this algorithm are provided in this paper.
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