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191.
We investigate in this note solution properties of semidefinite programming (SDP) relaxation for 0-1 quadratic knapsack problem (QKP). In particular, we focus on the issue of uniqueness of the optimal solution to the SDP relaxation for QKP. We first give a counterexample which shows that the optimal solution to the SDP relaxation for QKP could be non-unique. This is in contrast with the case of unconstrained 0-1 quadratic problems. A necessary and sufficient condition is then derived to ensure the uniqueness of the optimal solution to the SDP relaxation for QKP. 相似文献
192.
Yu-Jun Zheng Hai-Feng Ling 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2013,17(7):1301-1314
Emergency transportation is the most important part of disaster relief supply chain operations, and its planning problem always involves multiple objectives, complex constraints, and inherent uncertainty. Based on the analysis of several natural disaster that occurred in China since 2007, we propose a multi-objective fuzzy optimization problem of emergency transportation planning in disaster relief supply chains, which takes into consideration three transportation modes: air, rail, and road. To cope with the uncertainty, we employ three correlated fuzzy ranking criteria, and define the β dominance relation for evaluating the solutions of the problem. To efficiently solve the problem, we develop a cooperative optimization method that divides the integrated problem into a set of subcomponents, evolves the sub-solutions concurrently, and brings together the sub-solutions to construct complete solutions. The proposed method is effective, scalable, and robust, and thus contributes greatly to the performance of emergency transportation planning in disaster management. 相似文献
193.
194.
Solving a task scheduling problem is a key challenge for automatic test technology to improve throughput, reduce test time, and operate the necessary instruments at their maximum capacity. Therefore, this paper attempts to solve the automatic test task scheduling problem (TTSP) with the objectives of minimizing the maximal test completion time (makespan) and the mean workload of the instruments. In this paper, the formal formulation and the constraints of the TTSP are established to describe this problem. Then, a new encoding method called the integrated encoding scheme (IES) is proposed. This encoding scheme is able to transform a combinatorial optimization problem into a continuous optimization problem, thus improving the encoding efficiency and reducing the complexity of the genetic manipulations. More importantly, because the TTSP has many local optima, a chaotic non-dominated sorting genetic algorithm (CNSGA) is presented to avoid becoming trapped in local optima and to obtain high quality solutions. This approach introduces a chaotic initial population, a crossover operator, and a mutation operator into the non-dominated sorting genetic algorithm II (NSGA-II) to enhance the local searching ability. Both the logistic map and the cat map are used to design the chaotic operators, and their performances are compared. To identify a good approach for hybridizing NSGA-II and chaos, and indicate the effectiveness of IES, several experiments are performed based on the following: (1) a small-scale TTSP and a large-scale TTSP in real-world applications and (2) a TTSP used in other research. Computational simulations and comparisons show that CNSGA improves the local searching ability and is suitable for solving the TTSP. 相似文献
195.
Based on the quantum Zeno dynamics, we present an approach for deterministic preparation of arbitrary four-qubit decoherence-free state of superconducting quantum interference devices with respective to collective amplitude damping in a decoherence-free way, namely, not only the form of the target state is free of decoherence, but also the whole process for preparation. The operation is fast and convenient since we only need to manipulate three weak laser pulses sequentially. Other decoherence effects such as cavity decay and the spontaneous emission of qubits are also taken into account in virtue of master equation, and the strictly numerical simulation signifies the final fidelity is high corresponding to the current experimental technology. 相似文献
196.
Hong Peng Bin Hu Fang Zheng Dangping Fan Wen Zhao Xuebin Chen Yongxia Yang Qingcui Cai 《Personal and Ubiquitous Computing》2013,17(7):1341-1347
There are a lot of studies on chronic stress assessment applying psychology instruments or hormones analysis. However, there are only few studies using electroencephalogram (EEG), which is a non-invasive method providing objective inspection on brain functioning. In this paper, we analyzed overall complexity and spectrum power of certain EEG bands (theta, alpha and beta) collected from two groups of human subjects—high stress versus moderate stress at prefrontal sites (Fp1, Fp2 and Fpz). The results showed that the differences of nonlinear features (C0, LZC, D2, L1 and RE) and linear features (power and alpha asymmetry score) between two groups are significant. C0, LZC and D2 significantly increased in stress group at Fp1 and Fp2, while L1 and RE significantly decreased. And those with chronic stress have higher left prefrontal power. Finally, we suggest that it may be effective to discriminate the high-stress people from moderate-stress people by EEG. 相似文献
197.
数据存储器的广泛应用,对飞行器的的技术发展至关重要,因此提出了以FPGA为核心的数据存储器设计方法,探讨了一种RS-422的硬件接口电路,并对信号采用光耦隔离及施密特整形,保持了信号的准确性;同时分析了存储器的程序工作逻辑设计及FIFO的读取模式,保证了数据存储的完整性,最后阐述了一种FLASH存储模块的防护技术;试验表明了存储器可以完整记录飞行器发送的实时数据,证明了其应用的可行性,为飞行器的改进与维护提供了有效的依据。 相似文献
198.
199.
根据离焦模糊图像的特性,提出一种新的离焦模糊图像边缘检测算法,该算法通过定义一个新的边缘检测算子,利用新算子对图像各像素进行卷积,求得各像素的梯度和方向信息,根据梯度和方向信息进行阈值化处理,得到离焦模糊图像的边缘检测图像。实验结果表明,对于离焦模糊图像,利用新的边缘检测算子进行边缘检测,能够较好地检测被模糊而弱化的边缘,检测效果符合人眼视觉感受。 相似文献
200.
为了解决复杂环境下的虚拟人运动控制问题,提出一种基于人工势场的具有避障能力的虚拟人姿态优化算法.首先在虚拟环境中根据目标和障碍物建立人工势场,并对虚拟人运动链末端进行无碰撞路径规划;其次将规划后末端每个中间位姿的逆运动学计算问题表示为带位姿和无碰撞约束的舒适度函数优化问题,并进行求解;最后得到虚拟人运动过程中一系列连续的无碰撞姿态,实现自行避障的虚拟人运动控制.通过实例测试验证了文中算法的有效性,该算法可应用于复杂环境下的虚拟人动画和人机工程仿真. 相似文献