Background dominant colors extraction method based on color image quick fuzzy c-means clustering algorithm

A quick and accurate extraction of dominant colors of background images is the basis of adaptive camouflage design. This paper proposes a Color Image Quick Fuzzy C-Means (CIQFCM) clustering algorithm based on clustering spatial mapping. First, the clustering sample space was mapped from the image pixels to the quantized color space, and several methods were adopted to compress the amount of clustering samples. Then, an improved pedigree clustering algorithm was applied to obtain the initial class centers. Finally, CIQFCM clustering algorithm was used for quick extraction of dominant colors of background image. After theoretical analysis of the effect and efficiency of the CIQFCM algorithm, several experiments were carried out to discuss the selection of proper quantization intervals and to verify the effect and efficiency of the CIQFCM algorithm. The results indicated that the value of quantization intervals should be set to 4, and the proposed algorithm could improve the clustering efficiency while maintaining the clustering effect. In addition, as the image size increased from 128 × 128 to 1024 × 1024, the efficiency improvement of CIQFCM algorithm was increased from 6.44 times to 36.42 times, which demonstrated the significant advantage of CIQFCM algorithm in dominant colors extraction of large-size images.     

Fragment spatial distribution of prismatic casing under internal explosive loading

Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control. The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings. In this study, numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted. A new numerical method, which adds the Lagrangian marker points to the Eulerian grid, was proposed to track the multi-material interfaces and material dynamic fractures. Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship. Thereafter, the fragment spatial distributions of the prismatic casing with different fragment sizes, fragment shapes, and casing geometries were obtained using the numerical method. Moreover, fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes, and the experimental data were compared with the numerical results. The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data. Finally, a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.     

Spatial pricing and product allocation in online retailing

Spatial pricing means a retailer price discriminates its customers based on their geographic locations. In this article, we study how an online retailer should jointly allocate multiple products and facilitate spatial price discrimination to maximize profits. When deciding between a centralized product allocation ((i.e., different products are allocated to the same fulfillment center) and decentralized product allocation (ie, different products are allocated to different fulfillment centers), the retailer faces the tradeoff between shipment pooling (ie, shipping multiple products in one package), and demand localization (ie, stocking products to satisfy local demand) based on its understanding of customers' product valuations. In our basic model, we consider two widely used spatial pricing policies: free on board (FOB) pricing that charges each customer the exact amount of shipping cost, and uniform delivered (UD) pricing that provides free shipping. We propose a stylized model and find that centralized product allocation is preferred when demand localization effect is relatively low or shipment pooling benefit is relatively high under both spatial pricing policies. Moreover, centralized product allocation is more preferred under the FOB pricing which encourages the purchase of virtual bundles of multiple products. Furthermore, we respectively extend the UD and FOB pricing policies to flat rate shipping (ie, the firm charges a constant shipping fee for each purchase), and linear rate shipping (ie, the firm sets the shipping fee as a fixed proportion of firm's actual fulfillment costs). While similar observations from the basic model still hold, we find the firm can improve its profit by sharing the fulfillment cost with its customers via the flat rate or linear rate shipping fee structure.     

栅格地理数据并行格式转换引擎

如今大规模地理数据正在社会各个部门和组织中迅速积累,但是由于部门利益和历史沿袭等原因,大规模地理数据共享仍然极具挑战,相应共享技术需求仍然极其旺盛。作为地理数据共享的基础方式之一,传统单机地理数据格式转换技术,一方面受限于磁盘读写及带宽瓶颈,另一方面面对日趋庞大的数据规模,已很难满足实际应用需求。因此提出一种针对栅格地理数据的并行格式转换引擎,采用高性能计算集群环境支持大规模栅格地理数据转换共享,大幅降低了大规模栅格地理数据转换过程的时间成本。栅格地理数据并行格式转换引擎采用基于公共接口的设计理念,框架灵活、具有良好的扩展性,支持地理数据格式的读写自定义以及新数据格式添加,能够实现接入数据格式间的任意两两转换。为验证引擎框架及其处理效率,在Lustre并行集群环境下以格网数据交换格式(国家地理空间数据交换格式)向常见栅格地理格式的转换为示例进行了测试实验。结果表明,栅格地理数据并行格式转换引擎能够在8个节点Lustre集群中达到7.54的良好并行加速比。     

装备综合保障基础理论及技术的若干问题

从装备综合保障的定义分析入手,给出了更为合理的装备综合保障的定义,分析了装备综合保障定义的内涵,以及与装备综合保障相关的概念定义。阐述了美军装备综合保障的发展历程、现状,以及我国装备综合保障发展历程、现状和存在的主要问题。详细研究了装备综合保障的基本问题,提出了装备综合保障的基础理论框架、参数体系与模型体系框架、技术体系框架、基础技术体系框架、支撑技术体系与演示验证体系框架、应用技术体系框架。给出了加强装备综合保障基础理论与技术研究的有关建议。     

大椭圆航法及其导航参数计算

提出了基于地球椭球模型的大椭圆航法,采用解析几何中的空间向量分析,推导出了初始航向角、航程和偏航量的计算公式.算例分析表明,该公式可以解决航海中不同参考椭球下大椭圆航法的导航参数计算问题,航程计算精度高达10-3m.     

无衍射艾里光束的横向自加速特性

无衍射艾里光束的横向自加速特性使得光束在自由空间沿弯曲路径进行传输成为可能。利用一维傍轴波动方程对新型无衍射艾里光束的横向自加速特性进行了仿真研究。研究表明,当入射波长一定时,艾里光束的横向加速度大小与传播距离呈正比关系,而与任意横向尺度的大小呈反比关系。同时,利用波印廷矢量对艾里光束横向自加速的内在机理进行了研究。最后,利用通用型液晶空间光调制器对二维艾里光束的产生和横向自加速特性进行了实验研究,所得结果与仿真计算结果取得了较好的一致性。     

基于GIS的战场电磁环境可视化研究

针对当前战场电磁环境不可见特征,部队指挥员对其认知的模糊性,运用地理信息系统GIS(Graphic Information System)探索战场电磁环境可视化问题。提出用空间聚类分析模型解决分析处理电磁辐射源空间分布上的一种或几种特征问题,并对系统数据库设计、功能模板设计、逻辑结构设计进行详细阐述。得到可视化系统设计方案,将为指挥员进行电磁态势分析、指挥作战提供有效的辅助决策工具。     

空间信息支持高能激光武器应用研究*

依据空间信息支持现代作战的主要内容,介绍了五大类空间信息状况,分析了新概念武器高能激光的基本原理,并就其应用过程建立了UML模型。在此基础上,设计了空间信息支持高能激光武器应用系统的框架,并就高能激光武器对空间信息的需求进行了重点分析,而后以信息的转换与传递为主线,探讨了高能激光武器运用空间信息的流程。最后对该领域研究的趋势和发展前景做出了展望,并提出对其未来发展的要求。