基于雷达回波极化特征的电力线识别方法

现有的雷达对电力线的探测能力严重不足,这严重威胁低空飞行器如直升机的飞行安全。研究表明,线状物体对雷达垂直极化和水平极化信号响应强弱具有明显差异性,我们利用回波信号的极化特性建立起多维特征空间,并在该空间内完成电力线目标的感知、分类。某在研直升机低空防撞雷达的实测飞行数据表明,在利用极化信息所构建的特征空间内可有效区分电力线目标和虚假目标,准确率达到91%以上。该方法将有利于推动电力线障碍物预警雷达走向实用化。     

基于支路暂态势能函数的失步解列研究

电力系统遭受故障导致发电机组失去同步后,必须及时地解列控制平息振荡,防止系统崩溃。如何快速寻找系统的失步模式是解列控制的关键步骤之一。本文提出了基于支路暂态势能函数的失步模式实时判别方法。该方法首先通过量测各支路的两端电压相角差和流过支路的有功功率,然后将这些量测数据进行综合分析得到发电机组是否失步以及判断失步模式。基于得到的失步模式和快速的解列面搜索方法确定系统合适的解列断面。本文所提方法具有可操作性、实时性强的特点。对IEEE118节点系统进行了失步模式仿真搜索,仿真算例验证了方法的有效性。     

浅谈物资采购的电子商务化

网上物资采购问世不久,便以巨大的生命力得到快速发展。以网络技术为基础的电子采购,将对企业传统购销活动带来重大冲击和挑战,进而引发企业购销模式的剧烈变革,电子商务将成为网络时代经济的核心商业模式已成定局。文章阐释了发展电子商务化物资采购的意义,探讨了其发展思路和方案选择,并就要解决的几个认识问题提出了自己的见解。     

室温熔盐在碳纳米管电化学电容器中的应用

将碳纳米管制成薄膜电极,以二(三氟甲基磺酸酰)亚胺锂(LiTFSI)-1,3-氮氧杂环戊-2-酮(OZO)室温熔盐为电解液,装配成模拟电容器。测试结果表明,比电容为20.5F/g,工作电压可达2.0V以上,循环充放电500次后容量损失小于5%。室温熔盐在碳纳米管电化学电容器中表现出良好的电化学兼容性,具有良好的热稳定性,是超级电容器非常有前景的新型电解液。     

一种星上资源动态分配的GSM网络扩展方案

在农村和偏远地区实现地面蜂窝网的覆盖成本高、代价大。iDirect Technologies提出通过卫星基于TDMA体制实现GSM网络的扩展,可以大大节省星上的带宽资源,为电信运营商对地面蜂窝网络的扩展提供了新的增长点。     

Power Saving Technology Based on Overtimer Moment of Timers

针对通信系统中各定时器和网络端时钟频繁产生中断使系统过早进入工作状态的问题,结合移动终端的特点,提出一种基于定时器超时时刻调整的低功耗技术,并且从理论和实践上进行验证,该技术能够使设备尽可能地处于睡眠状态,有效地降低了系统功耗,对推动移动通信产业的发展具有重大意义.     

一种基于极化圆周SAR图像的陆上桥梁提取方法

桥梁作为重要的人造目标,一直都是合成孔径雷达(SAR)图像解译的重要对象之一.目前针对桥梁检测问题已开展了较多研究,核心思想是:首先提取出河流水体,然后再根据河流与桥梁的位置关系检测桥梁.然而,已有的桥梁检测方法依赖于河流提取,很难实现陆上桥梁检测.因为陆上桥梁下方的背景不再是河流,而是陆地,其散射特性、形状分布与河流...     

Ultrafast Electrochemical Growth of Lithiophilic Nano-Flake Arrays for Stable Lithium Metal Anode

Lithium dendrites caused by nonuniform Li⁺ flux leads to the capacity fade and short-circuit hazard of lithium metal batteries. The solid electrolyte interface (SEI) is critical to the uniformity of Li⁺ flux. Here, an ultrafast preparation of uniform and vertical Cu₇S₄ nano-flake arrays (Cu₇S₄ NFAs) on the Cu substrate is reported. These arrays can largely improve the lithiophilicity of the anode and form Li₂S-enriched SEI due to the electrochemical reduction of Cu₇S₄ NFAs with lithium. A further statistical analysis suggests that the SEI, with a higher content of Li₂S, is more effective to inhibit the formation of lithium dendrites and yields less dead lithium. A quite stable coulombic efficiency of 98.6% can be maintained for 400 cycles at 1 mA cm^–2. Furthermore, at negative to positive electrode capacity ratio of 1.5 (N/P = 1.5), the full battery of Li@Cu₇S₄ NFAs||S shows 83% capacity retention after 100 cycles at 1 C, much higher than that of Li@Cu||S (33%). The findings demonstrate that high Li₂S content in the SEI is crucial for the dendrite inhibition to achieve better electrochemical performance.     

Bioinspired Intrinsic Versatile Hydrogel Fabricated by Amyloidal Toxin Simulant-Based Nanofibrous Assemblies for Accelerated Diabetic Wound Healing

Persistent microbial infection and decreased neovascularization are common issues associated with diabetic wound treatment. Hydrogel dressings that offer intrinsic antibacterial and angiogenesis-inducing may substantially avoid the use of antibiotics or angiogenic agents. Herein, a versatile hydrogel is fabricated using an amyloid-derived toxin simulant (Fmoc-LFKFFK-NH₂, FLN) as building blocks, inspired by the defense strategy of Staphylococcus aureus (S. aureus). The simulant assemblies of the hydrogel function as both matrix components and functional elements for diabetic wound treatment. The hydrogel undergoes quick assembly from random monomers to nanofibrils with abundant b-sheet driven by multiple non-covalent interactions. The developed hydrogel demonstrates excellent biocompatibility and accelerates angiogenesis via hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor A (VEGFA) signaling as a consequence of its amyloidal structure. The simulant-based nanofibrils endow the hydrogel with broad-spectrum antibacterial activity dominated by a membrane-disruption mechanism. In addition, the hydrogel exhibits excellent performance compared with the commercial hydrogel Prontosan in accelerating wound healing of diabetic mice infected with methicillin-resistant S. aureus (MRSA). This study highlights the fabrication of a single component and versatile hydrogel platform, thereby avoiding the drug-related side effects and complicated preparations and demonstrating its profound potential as a clinical dressing for the management of microbe-infected diabetic wounds.     

基于边信道原子的椭圆曲线标量乘算法

提出了一种能够抵抗简单能量分析攻击的边信道原子结构,减少了椭圆曲线密码体制中标量乘的倍点和点加运算次数,从而节省了运算时间,最后通过调用Crypto++库函数,对于NIST提供的160 bit素域上椭圆曲线编程实现算法,发现此算法的效率比Montgomery Ladder算法提高了37.6%。