采用射流掺混增强的前可调面积涵道引射器数值模拟

为了提高风扇外涵和核心机驱动风扇级外涵流体的掺混效率，提出一种采用射流掺混增强的前可调面积引射器设计方案。通过数值模拟的手段对流量特性、流动掺混和总压损失等方面进行了研究，并同基准模型进行了对比分析，结果表明：采用波瓣混合器结构的前可调面积引射器设计，显著地增加了较高出口背压工况下风扇外涵的流通能力；新的设计方案不仅没有增加低出口背压工况下的总压损失，还减小了高背压出口工况下的流动损失；流向涡的特征尺度是提高掺混效率的关键，可以进一步优化波瓣混合器几何轮廓，以满足调节机构对结构设计的要求。     

社会计算实验动态仿真引擎的研究与实现

应对新形势下非常规突发事件的严峻挑战是各国政府亟待解决的问题,综合人工社会-计算实验-平行执行的ACP方法,是解决非常规突发事件应急管理问题的有效方法.本文引入ACP方法,阐述构建高性能社会计算实验动态仿真引擎的作用;按照层次化模块化思想设计动态仿真引擎D-PARSE的体系结构,详细描述各组成部分的具体功能,并基于并行...     

一种RetinaNet与SE融合的航空取证目标检测算法

针对在开展航空侦察取证时缺乏自动化、智能化取证手段的情况,提出了一种基于Reti-naNet与SE融合的航空取证目标检测算法,解决目标尺度变化大、数据集中类别不均衡的问题,并通过SE (squeeze-excitations)模块引入注意力机制进一步改进性能.该改进算法中的特征金字塔网络FPN可有效应对目标尺寸变化较大...     

一种基于移动基站的无线传感器网络数据收集方法

针对传统的无线传感器网络数据收集协议大多受制于发生在基站周围的热点问题,提出了一种使用移动基站的数据收集方法.将数据收集问题转化为支配集构造和旅行商问题,并提出了一种分布式的支配集构建算法,结合旅行商问题的近似算法生成基站的移动路线.仿真结果表明,所提出的方法减少了通信消耗,且能使负载均衡地分布.     

复杂网络社团发现算法研究新进展

社团结构是复杂网络普遍存在的拓扑特性之一,发现复杂网络中的社团结构是复杂网络研究的基础性问题.针对非重叠社团发现和重叠社团发现两类问题,全面综述了当前复杂网络社团发现算法研究的新进展,分析了每类社团发现算法的特点,指出该领域值得进一步探索的研究方向.     

Periodic review inventory management with contingent use of two freight modes with fixed costs

We study a stochastic inventory model of a firm that periodically orders a product from a make‐to‐order manufacturer. Orders can be shipped by a combination of two freight modes that differ in lead‐times and costs, although orders are not allowed to cross. Placing an order as well as each use of each freight mode has a fixed and a quantity proportional cost. The decision of how to allocate units between the two freight modes utilizes information about demand during the completion of manufacturing. We derive the optimal freight mode allocation policy, and show that the optimal policy for placing orders is not an (s,S) policy in general. We provide tight bounds for the optimal policy that can be calculated by solving single period problems. Our analysis enables insights into the structure of the optimal policy specifying the conditions under which it simplifies to an (s,S) policy. We characterize the best (s,S) policy for our model, and through extensive numerical investigation show that its performance is comparable with the optimal policy in most cases. Our numerical study also sheds light on the benefits of the dual freight model over the single freight models. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

基于聚类算法的多无人机系统任务分配

针对现有任务分配方法在任务点较多时不易解算,且计算量大的问题,提出了基于模糊C-均值聚类算法的多无人机系统任务分配方法.首先,利用模糊C-均值聚类算法得到的隶属度矩阵对任务点进行初始分配;其次,针对基于空间划分聚类可能造成各UAV任务不均衡的问题,设计任务的局部优化调整规则;最后,结合单旅行商问题,利用Tabu Sea...     

Optimal sample size allocation for tests with multiple levels of stress with extreme value regression

In this article, we discuss the optimal allocation problem in a multiple stress levels life‐testing experiment when an extreme value regression model is used for statistical analysis. We derive the maximum likelihood estimators, the Fisher information, and the asymptotic variance–covariance matrix of the maximum likelihood estimators. Three optimality criteria are defined and the optimal allocation of units for two‐ and k‐stress level situations are determined. We demonstrate the efficiency of the optimal allocation of units in a multiple stress levels life‐testing experiment by using real experimental situations discussed earlier by McCool and Nelson and Meeker. Monte Carlo simulations are used to show that the optimality results hold for small sample sizes as well. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Quantifying the performance effects of idle time utilization in multiserver systems

In many practical multiserver queueing systems, servers not only serve randomly arriving customers but also work on the secondary jobs with infinite backlog during their idle time. In this paper, we propose a c‐server model with a two‐threshold policy, denoted by (e d), to evaluate the performance of this class of systems. With such a policy, when the number of idle servers has reached d (<c), then e (<d) idle agents will process secondary jobs. These e servers keep working on the secondary jobs until they find waiting customers exist in the system at a secondary job completion instant. Using the matrix analytic method, we obtain the stationary performance measures for evaluating different (e, d) policies. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007.     

基于Multi-agent临床诊断支持系统的设计

根据临床诊断支持信息环境的特点,结合Agent技术,设计了一套基于Multi-agent的临床诊断支持系统(CDSS)。该系统具有异构性、分布性、并行性和可扩展性,能适应CDSS的要求,有效地提高CDSS的性能。