Outline-free floorplanning focuses on area and wirelength reductions, which are usually meaningless, since they can hardly satisfy modern design requirements. We concentrate on a more difficult and useful issue, fixed...
详细信息
Outline-free floorplanning focuses on area and wirelength reductions, which are usually meaningless, since they can hardly satisfy modern design requirements. We concentrate on a more difficult and useful issue, fixed-outline floorplanning. This issue imposes fixed-outline constraints on the outline-free floorplanning, making the physical design more interesting and challenging. The contributions of this paper are primarily twofold. First, a modifiedsimulatedannealing(MSA) algorithm is proposed. In the beginning of the evolutionary process, a new attenuation formula is used to decrease the temperature slowly, to enhance MSA's global searching capacity. After a period of time, the traditional attenuation formula is employed to decrease the temperature rapidly, to maintain MSA's local searching capacity. Second, an excessive area model is designed to guide MSA to find feasible solutions readily. This can save much time for refining feasible solutions. Additionally, B*-tree representation is known as a very useful method for characterizing floorplanning. Therefore, it is employed to perform a perturbing operation for MSA. Finally, six groups of benchmark instances with different dead spaces and aspect ratios—circuits n10, n30, n50, n100, n200, and n300—are chosen to demonstrate the efficiency of our proposed method on fixed-outline floorplanning. Compared to several existing methods, the proposed method is more efficient in obtaining desirable objective function values associated with the chip area, wirelength, and fixed-outline constraints.
This work proposes the use of the MSAA stochastic optimization technique to replace the optimality criterion used in the topology optimization method proposed by Andreassen. To evaluate and validate the MSAA performan...
详细信息
This work proposes the use of the MSAA stochastic optimization technique to replace the optimality criterion used in the topology optimization method proposed by Andreassen. To evaluate and validate the MSAA performance we studied three plane elasticity problems reported in the literature. Each problem was analyzed with three different finite element mesh types in order to compare the results obtained in terms of topology, strain energy value and average runtimes. It was established that the procedure involving the MSAA, yields lower computational times in problems with more refined meshes. Finally, the material distribution and the energy values obtained were similar to those reported in the work of Andreassen giving validity to the work presented here. (C) 2014 CIMNE (Universitat Politecnica de Catalunya). Published by Elsevier Espana, S.L.U.
Pulse compression techniques enable the radar designers to transmit long duration pulse to cater the need of high power at the transmitter and achieve the range resolution of short duration pulse at the radar receiver...
详细信息
Pulse compression techniques enable the radar designers to transmit long duration pulse to cater the need of high power at the transmitter and achieve the range resolution of short duration pulse at the radar receiver simultaneously. Due to easy generation and processing, binary codes are widely used as pulse compression codes in radars, sonars and spread-spectrum communication systems. But binary codes have high unwanted pulse compression sidelobes at the output of pulse compression receivers. In this paper, optimum binary codes reported in the literatures are overlaid on Discrete frequency sequences to reduce unwanted peaks sidelobes of optimum binary codes. The proposed approach not only reduced peak sidelobes of optimum binary codes but also increased the pulse compression ratio. In this paper, optimum discrete frequency sequences for overlaying with binary codes are optimized using the modified simulated annealing algorithm (MSAA). A Discrete Frequency Coded binary signal has a complex signal structure which will be difficult to detect and analyze by enemy Electronics Support Measures (ESM). In this paper, a unified adaptive radar model is also proposed to cater the needs of today's radar signal design requirements. The proposed model will help to improve range resolution, the detection capability of radar, reduce the peak sidelobes significantly, and also improve the ESM capability of radar systems.
Satellite cluster flight reconfiguration maneuver strategy based on modified simulated annealing algorithm is studied. Firstly, satellite cluster flight reconfiguration manuever missions are described. Then, a modifie...
详细信息
ISBN:
(纸本)9789881563804
Satellite cluster flight reconfiguration maneuver strategy based on modified simulated annealing algorithm is studied. Firstly, satellite cluster flight reconfiguration manuever missions are described. Then, a modified simulated annealing algorithm is proposed, which could increase the convergence speed, comparing with the traditional simulatedannealingalgorithm. Next, a satellite cluster flight reconfiguration maneuver strategy is designed, by combining satellite cluster flight reconfiguration manuever missions and the modified simulated annealing algorithm. Finally, the proposed cluster reconfiguration manuever strategy is applied to a cluster scatter and regather mission in numerical simulations, thereby the effectiveness and rapidity are verified.
A Hydraulic Variable Valve Actuation (HVVA) system is studied in this work, it can continuously adjust engine valve timing and lift at any engine speeds by using a hydraulic actuation system. A detailed co-simulation ...
详细信息
A Hydraulic Variable Valve Actuation (HVVA) system is studied in this work, it can continuously adjust engine valve timing and lift at any engine speeds by using a hydraulic actuation system. A detailed co-simulation model is built to reveal relationship between hydraulic pressure, engine valve lift and power consumption, it has taken flow rate, fluid property and pressure drop into consideration. Precision and accuracy of the simulation model are verified by a set of bench test. Coefficient of variation (COV) of engine lift shows that the experiment is repeatable and system robustness is verified through simulation. A modifiedsimulatedannealing optimization is conducted to search optimum operation parameters to reduce the HVVA system's power consumption and improve engine's volumetric efficiency (VE) as well as control engine valve seating speed. A pre-selecting criterion and a database retrieve process are added in the algorithm to improve the optimization's efficiency. Optimization shows that optimum pump speed and relief pressure vary from 440 rpm, 32 bar to 2200 rpm, 60 bar when engine speed increases from 500 to 3600 rpm. Corresponding system power consumption rises from 0.07 kW to 0.49 kW, valve lift has a relatively high time-area value (TAV) and an acceptable engine valve seating speed.
Satellite cluster flight reconfiguration maneuver strategy based on modified simulated annealing algorithm is ***,satellite cluster flight reconfiguration manuever missions are ***,a modifiedsimulatedannealing algor...
详细信息
Satellite cluster flight reconfiguration maneuver strategy based on modified simulated annealing algorithm is ***,satellite cluster flight reconfiguration manuever missions are ***,a modified simulated annealing algorithm is proposed,which could increase the convergence speed,comparing with the traditional simulatedannealing ***,a satellite cluster flight reconfiguration maneuver strategy is designed,by combining satellite cluster flight reconfiguration manuever missions and the modifiedsimulatedannealing ***,the proposed cluster reconfiguration manuever strategy is applied to a cluster scatter and regather mission in numerical simulations,thereby the effectiveness and rapidity are verified.
This study focuses on the design methods for uniform linear array (ULA) based directional antenna arrays by optimising the radiation characteristics of elements. To improve the performance of direction-of-arrival (DOA...
详细信息
This study focuses on the design methods for uniform linear array (ULA) based directional antenna arrays by optimising the radiation characteristics of elements. To improve the performance of direction-of-arrival (DOA) estimation in a predetermined objective spatial sector which includes all the potential directions of incidence, Cramer-Rao bound based optimisation models are established by utilising the least squares fitting technique. Besides, a modifiedsimulatedannealing (SA) algorithm with the iteration of parameters is proposed, aiming to solve the optimisation problems when the classic SA is invalid. Compared with the corresponding conventional ULA, an optimised array can obtain higher accuracy of DOA estimation in the objective spatial sector with little fluctuation. Additionally, the optimised design of radiation characteristics can also suppress the ambiguities, and remains effective for the arrays with different aperture. Simulation results verify the effectiveness of the proposed methods and the superiority of the optimised arrays.
Designing the last mile delivery system in a lean way has become an important part of serving customers efficiently and economically. However, in practice, the uncertainty in customer demand and travel times often mea...
详细信息
ISBN:
(纸本)9789811323843;9789811323836
Designing the last mile delivery system in a lean way has become an important part of serving customers efficiently and economically. However, in practice, the uncertainty in customer demand and travel times often means vehicles capacity may be exceeded along the planed route and vehicles miss theses time windows, increasing the cost, reducing efficiency and decreasing the customer satisfaction. Previous studies have lacked an uncertainty-based view, and few studies have discussed how to develop an uncertain model. To address this issue, the bi-level routing problem for the last mile delivery is formulated as a robust vehicle routing problem with uncertain customer demand and travel times. In addition, a modified simulated annealing algorithm is proposed and tested in computational experiments. The results show that the proposed model has good performance for uncertainty processing.
Global path planning for mobile robot using genetic algorithm and simulatedannealingalgorithm is investigated in this paper. In view of the slow convergence speed of the conventional simulatedannealingalgorithm, a...
详细信息
ISBN:
(纸本)9781605583266
Global path planning for mobile robot using genetic algorithm and simulatedannealingalgorithm is investigated in this paper. In view of the slow convergence speed of the conventional simulatedannealingalgorithm, a modified simulated annealing algorithm is presented, and a hybrid algorithm based on the modified simulated annealing algorithm and genetic algorithm is proposed. The proposed algorithm includes three steps: the MAKLINK graph theory is adopted to establish the free space model of mobile robots firstly, then Dijkstra algorithm is utilized for finding a feasible collision-free path and fixing on the sub-search-space where the global optimal path inside,. finally the global optimal path of mobile robots is obtained based on the hybrid algorithm of modified simulated annealing algorithm and genetic algorithm. Experimental results indicate that the proposed algorithm has better performance than simulatedannealingalgorithm and ant system algorithm in term of both solution quality and computational time, and thus it is a viable approach to mobile robot global path planning.
Selection of optimal measurement configurations for the kinematic parameter calibration is investigated in this paper. To minimise the effects of measurement and modelling errors on parameter estimation, a series of o...
详细信息
Selection of optimal measurement configurations for the kinematic parameter calibration is investigated in this paper. To minimise the effects of measurement and modelling errors on parameter estimation, a series of optimal calibration configurations is obtained with our modified simulated annealing algorithm. To accelerate the convergence rate, a suitable cooling schedule is designed. Independent and interactive effects of the parameters in the cooling schedule on algorithm performance are discussed. Two observability indices are optimised with the modified simulated annealing algorithm to obtain the optimal measurement configurations of the 5-DOF polishing robot. simulated calibration shows that these optimal configurations improve the calibration accuracy significantly. Experimental results, compared with those of random pose selection and a local search algorithm, are presented to demonstrate the feasibility of the proposed approach.
暂无评论