基于三分类支持向量机的船用逆变器故障诊断

针对电力推进船舶逆变器存在的开关器件开路故障诊断问题,提出一种基于三分类支持向量机的故障诊断方法。利用对称分量分析方法获得逆变器输出正序瞬时值分量,通过对信号进行小波包分解,得到不同开关元件故障下的小波能量,规范化后作为对应开关器件故障特征。根据开关器件位置和逆变器输出波形特点对开关器件进行分组,利用三分类支持向量机实现故障分类。仿真分析结果表明,该三分类支持向量机故障分类正确率94.29%,诊断方法有效。     

Multi-band spectrum auction framework based on location information in cognitive radio networks

Cognitive radio(CR) technology is considered to be an effective solution to allocate spectrum resources,whereas the primary users of a network do not fully utilize available frequency bands.Spectrum auction framework has been recognized as an effective way to achieve dynamic spectrum access.From the perspective of spectrum auction,multi-band multi-user auction provides a new challenge for spectrum management.This paper proposes an auction framework based on location information for multi-band multi-user spectrum allocation.The performance of the proposed framework is compared with that of traditional auction framework based on a binary interference model as a benchmark.Simulation results show that primary users will obtain more total system revenue by selling their idle frequency bands to secondary users and the spectrum utilization of the proposed framework is more effective and fairer.     

时空尺度差异下疫情严重程度的比较研究

 抗击新型冠状病毒肺炎疫情，是当下中国的紧急要务，也是全世界的防控重点。作为公共卫生事件的核心构成，评判“疫情是否严重”是社会各界所要面对的首要问题。以数据为基础，分析了新型冠状病毒感染肺炎病例的确诊人数、死亡人数、治愈人数、密切接触者及医学观察人数等信息，论述了疫情的影响范围和蔓延趋势。针对疫情的严重程度，采用比较分析法，从纵向时间和横向空间两个尺度衡量疫情在不同阶段、不同地区的接触率、感染率、确诊率、治愈率和病死率的差异。通过比较研究，论证说明不同时空尺度下疫情严重程度的差异，进一步提出多尺度评估疫情严重程度的要义和建议。     

一类捕食模型的持续生存条件

根据综合害虫管理,提出一类具有脉冲效应的捕食模型并进行分析,利用Floquet乘子理论,给出系统持续生存的条件.     

杜能模式的微观层面考察——基于山东省东老庄村的案例调查

自杜能模式提出以来,国内外许多学者对其进行了验证、修正与扩展,尽管取得了丰硕的成果,但未得到过杜能理论验证的地区还大量存在.为此,本文基于对山东省诸城市东老庄村的种植农户、养殖与种植农户、大棚蔬菜种植农户等案例的实地调研,在微观尺度下分析验证了杜能模式.农户经营行为尽管不同,但从劳动集约性上也能确认出杜能模式的构造.在考察不同尺度的土地利用模式时,由于各个区位因子不同,结果也会不同.即使具有相同的区位因子,在不同的尺度下,如果区位的贡献度具有差异的话,就有必要构建不同尺度的杜能模式.     

基于DoDAF的民机MBSE研制方法

针对传统的民机研制方法中面临的设计需求不完整、难以保证设计与需求一致性、设计方案难以更改等一系列问题, 结合美国国防部架构框架(Department of Defense Architecture Framework, DoDAF)的多个视角, 提出基于DoDAF的民机基于模型的系统工程研制方法。该方法参考DoDAF中不同的视点从多角度对民机研制要求进行分解与细化, 生成资源流动模型、活动模型以及系统接口模型等, 开发出信息更加立体的飞机能力模型, 指导民用飞机的设计, 证明了基于DoDAF的民机研制方法能够从多视角的角度完整、全面地分解飞机能力要求，并将其转化为具体的设计要求, 从而更好地指导民机研制, 提高民机研制效率。     

Information gain based sensor search scheduling for low-earth orbit constellation estimation

This paper addresses the problem of sensor search scheduling in the complicated space environment faced by the low-earth orbit constellation.Several search scheduling methods based on the commonly used information gain are compared via simulations first.Then a novel search scheduling method in the scenarios of uncertainty observation is proposed based on the global Shannon information gain and beta density based uncertainty model.Simulation results indicate that the beta density model serves a good option f...     

Exact penalty method for the nonlinear bilevel programming problem

In this paper, following the method of replacing the lower level problem with its Kuhn-Tucker optimality condition, we transform the nonlinear bilevel programming problem into a normal nonlinear programming problem with the complementary slackness constraint condition. Then, we get the penalized problem of the normal nonlinear programming problem by appending the complementary slackness condition to the upper level objective with a penalty. We prove that this penalty function is exact and the penalized problem and the nonlinear bilevel programming problem have the same global optimal solution set. Finally, we propose an algorithm for the nonlinear bilevel programming problem. The numerical results show that the algorithm is feasible and efficient.     

聚乙二醇对葛根黄豆苷元体外溶出的影响

以聚乙二醇为载体材料,制备了葛根黄豆苷元固体分散体,采用紫外分光光度法测定其体外溶出度,分别研究了聚乙二醇的相对分子质量、药物和载体的比例和固体分散体的制备方法对药物溶出的影响.实验结果发现:固体分散体中药物的溶出度均高于原料药;药物的溶出度随聚乙二醇相对分子质量的增大而增大、随载体用量提高而增大;不同的固体分散体制备方法对药物的溶出度影响不大.     

多级混沌保密通信系统方案的设计及其噪声干扰的研究

以Lyapunov稳定性理论为基础,针对一系列非扩散混沌系统,提出一种三个不同混沌系统之间的异结构同步方法.就混沌通信问题,提出了一种多级混沌保密通信系统的实现方法,在前两个同步的系统中加密后,利用后两个同步系统再一次加密.通过加入高斯白噪声干扰,对多级混沌保密通信系统进行噪声干扰的分析和计算,并用小波分析理论对加噪信号进行处理.仿真结果表明,有用信号的传输在噪声的干扰下发生畸变,经小波分析理论处理后, 有用信号可以无失真地恢复过来.