科创中国

k-median问题的近似算法研究一直是计算机科学工作者关注的焦点.基于均衡限制条件,利用反向贪心策略,给出求解该问题的随机近似算法.证明该算法以较大的概率满足其近似性能比的期望值为(3 +O(ln(ln(k)/a)).该算法的时间复杂度为O([k/aln(k)]2(n+m)),其中n和m分别代表设施集合以及客户点集的大小.最后,通过计算机实验验证了k-median问题的反向贪心算法的实际计算效果.

The existing researches of the evaluation method of ride comfort of vehicle mainly focus on the level of human feelings to vibration. The level of human feelings to vibration is influenced by many factors, however, the ride comfort according to the common principle of probability and statistics and simple binary logic is unable to reflect these uncertainties. The random fuzzy evaluation model from people subjective response to vibration is adopted in the paper, these uncertainties are analyzed from the angle of psychological physics. Discussing the traditional evaluation of ride comfort during vehicle vibration, a fuzzily random evaluation model on the basis of annoyance rate is proposed for the human body's subjective response to vibration, with relevant fuzzy membership function and probability distribution given. A half-car four degrees of freedom suspension vibration model is described, subject to irregular excitations from the road surface, with the aid of software Matlab/Simulink. A new kind of evaluation method for ride comfort of vehicles is proposed in the paper, i.e., the annoyance rate evaluation method. The genetic algorithm and neural network control theory are used to control the system. Simulation results are obtained, such as the comparison of comfort reaction to vibration environments between before and after control, relationship of annoyance rate to vibration frequency and weighted acceleration, based on ISO2631/1(1982), ISO 2631–1(1997) and annoyance rate evaluation method, respectively. Simulated assessment results indicate that the proposed active suspension systems prove to be effective in the vibration isolation of the suspension system, and the subjective response of human being can be promoted from very uncomfortable to a little uncomfortable. Furthermore, the novel evaluation method based on annoyance rate can further estimate quantitatively the number of passengers who feel discomfort due to vibration. A new analysis method of vehicle comfort is presented.

The idle time which is part of the order fulfillment time is decided by the number of items in the zone; therefore the item assignment method affects the picking efficiency. Whereas previous studies only focus on the balance of number of kinds of items between different zones but not the number of items and the idle time in each zone. In this paper, an idle factor is proposed to measure the idle time exactly. The idle factor is proven to obey the same vary trend with the idle time, so the object of this problem can be simplified from minimizing idle time to minimizing idle factor. Based on this, the model of item assignment problem in synchronized zone automated order picking system is built. The model is a form of relaxation of parallel machine scheduling problem which had been proven to be NP-complete. To solve the model, a taboo search algorithm is proposed. The main idea of the algorithm is minimizing the greatest idle factor of zones with the 2-exchange algorithm. Finally, the simulation which applies the data collected from a tobacco distribution center is conducted to evaluate the performance of the algorithm. The result verifies the model and shows the algorithm can do a steady work to reduce idle time and the idle time can be reduced by 45.63% on average. This research proposed an approach to measure the idle time in synchronized zone automated order picking system. The approach can improve the picking efficiency significantly and can be seen as theoretical basis when optimizing the synchronized automated order picking systems.

针对工业零件含噪图像边缘检测,根据Canny算法原理,提出了一些改进策略,形成了一种矩形透镜最大梯度模边缘检测算法.采用中值滤波完成图像平滑,有效抑制了图像噪声;采用5X5邻域一阶偏导有限差分计算图像的梯度幅值,提高了边缘定位的精度;采用最大类间方差法(OTSU)求解了最优区域分割阈值,实现了边缘的自动检测.以磁环和极片工业零件图像边缘检测为例进行了实验,结果表明,该算法具有较好的去噪和边缘检测效果.图4参13

针对无线射频CPU卡自身及其在射频识~IJ(RFID)的过程中存在的安全隐患问题,提出了一种将椭圆曲线加密算法(ECC)与高级加密标准(AES)相结合的混合加密算法.该方法用高密钥效率的ECC算法加密射频CPU卡中的重要信息,再用AES算法加密射频CPU卡与读写器之间的通讯信息,在通讯的过程中重要的信息经过了ECC和AES双重加密,攻击者即使得到射频卡或者截获信息,也不能很快就得到有用的信息.实验结果表明,该方法有效地提高了射频CPU卡自身及其在通信过程中的安全性及抵御攻击的可能性,充分发挥了混合加密算法的优势.

目的应用CONSORT 2010声明评价随机对照试验(RCT)论文的质量.方法组建并培训熟悉CON-SORT 2010声明和视觉模拟(VAS)评分的工作小组,针对论文"促性腺激素释放激素激动剂联合反向添加疗法治疗子宫内膜异位症的临床疗效研究",用CONSORT 2010声明清单的25个条目逐一对照和点评,并对各条目的报告质量给予VAS评分,经过统计学分析之后对论文的整体质量进行评价.结果被评价论文有15个条目提及了完整性和准确性程度不等的内容;对于全文25个条目的报告:VAS得分95分2条、90分4条、80分2条、75分2条、60分2条、45分2条、23分1条、0分10条;每个条目平均VAS评分为(43.7±40.0)分,其中VAS评分在80分以上的有8条,占32%;被评价论文有10个条目未报告,占40%.结论被评价论文报告的质量不高.建议我国RCT的报告仍需规范,报告质量有待提高,尤其是与试验设计原则有关的报告质量;撰稿人报告RCT与审稿人面对RCT论文时均应参照CONSORT声明;编辑部可酌情把CONSORT声明逐步引入稿约;建议用CONSORT声明对照撰写RCT.

通过梳理搜索算法中出现的各种特征因子,提出一种更全面的特征因子分类方法,按其自身特点将特征因子划分为6类,分别是文字内容特征、Web拓扑特征、主题分布特征、文档类型特征、统计特征和时效性特征,并描述各特征项对主题相关性的作用、综合运用各类特征的通用化链接优先级计算公式以及特征选取原则.

针对当前交叉口信号灯模糊控制器结构参数固定的缺陷,提出了一种新的分级模糊控制器用于交叉路口交通流的控制与优化,该控制器能有效地减少规则数,易于提取模糊规则,能够显著改善交叉路口的通行能力.仿真实验结果证明该模型是有效的.

Epidemic算法在某些场景中具有很高的传输成功率、很小的传输延迟,但其适应性较差,在另一些场景中性能会显著下降.分析了影响Epidemic算法性能的因素,认为挤出效应是导致算法性能下降的主要原因;提出了Adaptive机制,其使节点可以根据周围节点缓存的状况调整注入网络数据包的数量,主动地抑制挤出效应的发生,进而改善Epidemic算法性能.仿真结果表明,改进后算法的传输成功率显著提高,路由开销大幅度下降.