科技信息网网络安全策略

通过对目前科技信息网络存在的网站供电安全、机房运行环境安全、网站结构与访问安全、网络平台开发代码安全等各种网络安全运行瓶颈的分析，提出解决网络安全的网络架构与安全对策。     

带干扰的Erlang(2)风险模型罚金函数的期望

考虑了带干扰的Erlang(2)风险模型罚金函数的期望,利用建立的积分-微分方程,得出了期望的明确表达式.     

基于Tabu搜索和变区域遗传算法的组卷问题研究

针对目前大型题库中组卷算法效率低的问题，给出了多目标约束条件下的组卷问题数学模型，提出了基于Tabu搜索和变区域遗传算法的TS-CAGA算法。本算法用遗传算法作全局搜索，用禁忌搜索算法作局部搜索，给出了搜索区域动态变化的条件，通过种群规模自适应调整，可以加快收敛速度和避免局部最优化。实验结果表明，算法的组卷效率和选题质量有显著提高。     

完全匹配层吸收边界条件的研究

边界反射是数值模拟中的一个关键问题.构建完全匹配层(PML)吸收边界条件是消除边界反射的理想方法之一.此方法是在研究区域的边界上加入吸收层,使边界上传入吸收层的波随传播距离按指数规律衰减,不产生任何反射,达到消除边界反射的目的.首先给出了二维声波方程完全匹配层的公式,然后通过地面地震模型和井间地震模型数值算例与常规吸收边界条件进行了比较.结果表明,PML边界条件具有吸收更干净、相位对应关系好且能够吸收各种角度的边界反射等优点,从而验证了完全匹配层吸收效果的优越性.     

400Hz中频电源设计

以实际工程项目中要求的中频电源为研究对象，设计了一种基于SPWM技术的中频电源系统方案．系统以单片机和SPWM信号发生芯片为核心，利用频率和电压反馈实现了中频电源设计．分别给出了实现本设计方案的单片机89C51与信号发生器SA8282的接口电路、IGBT的驱动隔离电路、外围扩展芯片、SA8282内部结构和工作原理和软件设计流程图．     

Biochemical evidence of cannibalism at a prehistoric Puebloan site in southwestern Colorado

The existence of cannibalism is one of the most controversial issues in the archaeology of the American Southwest. Disarticulated, cut-marked and heat-altered human remains from non-burial contexts at prehistoric Puebloan (Anasazi) archaeological sites in the Four Corners region of the American Southwest have been interpreted by some scholars as evidence of cannibalism. Osteological studies indicate that many of the disarticulated bodies found at these sites were processed in a manner consistent with food preparation. Opponents of this interpretation point out that non-cannibalistic practices such as secondary interment, corpse mutilation and ritualized witch executions might account for the assemblages. Osteological evidence alone does not document the actual ingestion of human flesh. Here we show consumption of human flesh did occur as demonstrated in preserved human waste containing identifiable human tissue remains from a site with osteological evidence of cannibalism.     

Ordering and self-organization in nanocrystalline silicon

The spontaneous formation of organized nanocrystals in semiconductors has been observed during heteroepitaxial growth and chemical synthesis. The ability to fabricate size-controlled silicon nanocrystals encapsulated by insulating SiO2 would be of significant interest to the microelectronics industry. But reproducible manufacture of such crystals is hampered by the amorphous nature of SiO2 and the differing thermal expansion coefficients of the two materials. Previous attempts to fabricate Si nanocrystals failed to achieve control over their shape and crystallographic orientation, the latter property being important in systems such as Si quantum dots. Here we report the self-organization of Si nanocrystals larger than 80 A into brick-shaped crystallites oriented along the (111) crystallographic direction. The nanocrystals are formed by the solid-phase crystallization of nanometre-thick layers of amorphous Si confined between SiO2 layers. The shape and orientation of the crystallites results in relatively narrow photoluminescence, whereas isotropic particles produce qualitatively different, broad light emission. Our results should aid the development of maskless, reproducible Si nanofabrication techniques.     

温州中小企业的品牌战略

随着市场经济的深入发展,中小企业已经成为我国经济发展的重要支柱。企业间的竞争已由过去的质量、价格竞争转变为信誉、企业形象和服务水平等综合素质的竞争,进而发展为打造知名品牌的竞争。一切成功企业最终经营的并非"产品"而是"品牌"。温州的中小企业在历经多年的蓬勃发展之后,陷入了瓶颈期,而解决这一困境的方法就是利用品牌战略来实现突围,走创立品牌、注重品牌发展的道路。     

浅析ZPW-2000A型无绝缘轨道电路系统

通过分析ZPW-2000A型无绝缘轨道电路系统,阐述了该系统的原理、构成、特点、防雷等性能。同时分析了设备的应用及客运专线补偿电容的设置。     

Progress and challenges in translating the biology of atherosclerosis

Atherosclerosis is a chronic disease of the arterial wall, and a leading cause of death and loss of productive life years worldwide. Research into the disease has led to many compelling hypotheses about the pathophysiology of atherosclerotic lesion formation and of complications such as myocardial infarction and stroke. Yet, despite these advances, we still lack definitive evidence to show that processes such as lipoprotein oxidation, inflammation and immunity have a crucial involvement in human atherosclerosis. Experimental atherosclerosis in animals furnishes an important research tool, but extrapolation to humans requires care. Understanding how to combine experimental and clinical science will provide further insight into atherosclerosis and could lead to new clinical applications.