数字放大器—3G无线基站的助推器

为了构筑第三代无线网络,人们需要对现有基础设施进行彻底改造,包括网络的发射基站。配置在无线基站中的新型数字控制功率放大器能够改善频谱利用率和功率效率,从而提高系统容量。PMC-Sierra公司的数字控制功率放大器采用了数字校正信号处理器(DCSP)以及自适应控制处理器和补偿估值器(ACPCE),该放大器可改善无线基础设施的可靠性,同时降低系统成本、规模及复杂性。     

试述“五四”时代特征与现代小说文体的建构

时代特征对文学样式、内容、风格等方面的嬗变有非常大的影响。五四时期,"重估一切价值"的理性精神促成小说观念的变更,"个性解放"与"新文化运动"推动小说内容的重新建构,西方文艺思潮的广泛宣传为现代小说提供了新的表现方式,创作群、读者群、传播媒介的渐趋成熟为现代小说文体的定型提供了保障。     

强化攀钢选钛工艺流程的探讨

在总结以往试验研究成果、设计经验、选钛厂历年有关生产资料和国内外有关技术资料的基础上 ,对强化攀钢选钛工艺流程提出个人的见解 ,以便于选钛厂遵循合理优化可靠的工艺流程进行改扩建     

First Principles Investigation of Local Distortions in Doped La2CuO4

We present the results of first-principles cluster calculations of local distortions in doped La₂CuO₄. Local deformations of the CuO₆ octahedra associated with the presence of an additional extrinsic hole were determined using the density-functional (DF) method on various cluster models. The results indicate that a localized hole induces a contraction of the CuO(apical) distance from 2.40 to 2.28 Å. The contracted distance is in very good agreement with the anomalous, short CuO(apical) distance of 2.3 Å, observed recently by polarized Cu K-edge extended x-ray absorption fine structure (EXAFS) in La_1.85Sr_0.15CuO₄ and associated with the hole-rich stripe region.     

基于IP的城域网流媒体服务系统设计

介绍了基于IP的城域网（MAN）流媒体服务系统的体系结构，指出未来的IP流媒体服务系统必然是集中和分布式相结合的服务平台；着重阐述了所涉及的几项关键技术及其可能的解决方案。     

纯钛粉放电等离子烧结致密化的动力学与组织演变行为

放电等离子烧结(spark plasma sintering, SPS)具有快速致密化的显著特点,然而目前对SPS快速致密化的动力学行为缺少深入理解与认识。考虑到纯钛的优异性质及广泛应用,本文以纯钛粉为典型材料,在压强20 MPa、温度为600~875℃条件下,进行纯钛粉的SPS烧结,获得了其在不同温度下的致密化过程与时间的函数关系,揭示了其快速致密化的动力学行为。并深入探讨烧结温度对其微观组织、孔隙度及力学性能的影响。结果表明：在低温阶段(600~725℃),致密化指数为1.5,扩散与高温蠕变共同作用实现样品的致密化;在温度较高时(800~875℃)致密化指数为2,此时主要为高温蠕变导致的致密,随温度升高,样品的维氏硬度增加,且温度越高增加速率越快,样品的力学性能提高。     

光电耦合器在带传输系统中的应用

介绍了光电耦合器在兰州在线同位素分离器终端上的带传输实验中的应用。它有效地消除了在实验中由于外部环境条件与系统对数据获取单元引起的强烈干扰。此方法有电路结构简单、稳定可靠、抗干扰能力强等特点。     

Managing and interpreting uncertainty for climate change risk

Climate change is a significant risk for the built environment because it implies not only warmer weather, but also more extreme weather events, such as storms, droughts and heat waves. Considerable uncertainty about the future also exists, partly because of the response of society's apparent reluctance to mitigate climate change by reducing fossil fuel consumption. An adaptive response to the challenge draws on the literature on climate change, the urban environment, natural hazards and risk analysis. Two concepts - life cycle costs and the avoidance of ruin - provide a useful framework for factoring the uncertainty associated with climate change into a risk analysis for the built environment. Monitoring, prediction, data management and communication are the unglamorous underpinnings of a successful urban risk-management strategy. For cities to develop a significantly improved response capacity, the active support of senior levels of government is essential because cities have neither the legal powers nor the resources to tackle climate change on their own. Ultimately, the biggest challenges are institutional and behavioural.     

基于多片DSP处理器结构的高速加密卡

根据加/解密数据处理的特点,提出了一种基于多片DSP处理器的高速加密卡结构,并对系统中几个重要器件和连接部分做了较详细的阐述。     

纳米多孔二氧化钛薄膜的制备及其亲水性能的研究

分别采用溶胶-凝胶法,水热合成法,热雾喷解法制备了纳米多孔TiO2薄膜。以X射线衍射,扫描电镜等方法分析了不同制备方法所得薄膜结构与形貌。通过比较不同方法制备的TiO2薄膜的亲水性能,得知溶胶—凝胶法制备的薄膜和玻璃载体结合最紧,而且表面平整。热雾喷解法制备的薄膜具有最大的比表面积,其亲水性能也最好。同时表明,纳米多孔TiO2薄膜在紫外光照射以后,具有比一般薄膜更持久的亲水型。