无线网络的移动管理：数据的复制和应用

在无线通讯系统中，网络通过从数据库中查找用户信息来跟踪用户，这样就需要把用户信息事先存储在大量的数据库中。本书讨论了有关在数据库中复制用户信息并更新的若干问题。     

脑及其自我先天本能和后天驱动力的神经生物化学观念

这本专著总结了作者多年来最重要的研究成果。研究表明，人的大脑皮层具有获得驱动力的独特能力．正是这种能力创造了人类社会，并促使人类社会不断进化。作者认为，人类社会目前还处于反复实验的发展阶段，但其最终必将由现在的不可知状态逐渐过渡到理性指导的平衡状态。通过对获得性驱动力的特殊分析及以前曾认为不可知的脑机理的发现，作者对社会生活的发展及艺术、科学的起源给出了合理的生理学解释。本书的目的是要论证即使在脑及其自我的关系中，自然规律仍然是简单的，而不是不可知的。     

数字通信系统 第三版

本书全面介绍了数字通信系统的理论和实际应用方法，并且包含了在数字信号传输中需要运用的关于设计、实现和测试的最新方法和技术。此书介绍的基本技术有：纠错码、多路复用、数字调制、数字用户线路、电缆调制、移动无线网络、城域网和光纤网络。新的工业标准有：声音／视频编码、SONET/SDH、DWDM、ATM、宽带无线网、网络同步和网络管理。每一章节后都有评述和参考文献和大量习题（无答案）。     

各向异性的气体-颗粒介质内的二通量辐射传热模型

二通量模型是计算气体-颗粒平板内辐射热通量的简化方法. 在最初的二通量模型中, 辐射场被假设成在半球方向的各向同性. 但是对于燃烧领域的气体-颗粒混合介质, 颗粒的散射通常都是各向异性的, 这样, 原有的二通量模型就会由于忽略各向异性而产生严重的误差. 文中一个多层四通量模型被运用到包含气体-颗粒混合物的辐射热通量的计算. 给出了模型的解析求解过程, 定义了等价的平均交叉系数h和前向散射率z来描述整个平板散射的各向异性. 为了验证模型的准确性, 计算了一个无限大平板内的辐射传递过程, 并与解析结果进行了比较. 结果表明提出的模型能够得到准确的结果, 对原有的二通量模型具有较好的改进作用. 运用本模型计算含有飞灰/CO₂/H₂O的燃烧产物的辐射传递, 所得到的平板发射率与Goodwin的经典结果相吻合.     

MERGING OPTIMALITY CONDITIONS WITH GENETIC ALGORITHM OPERATORS TO SOLVE SINGLE MACHINE TOTAL WEIGHTED TARDINESS PROBLEM

1.Introduction Production sequencing and scheduling is one of the most important activities in production planning and control.Sequencing is defined as the order in which the jobs are processed through the machines.The allocation of machines over time to process a collection of jobs is defined as Scheduling.Several methods have been developed to solve the scheduling problem which can be classified as follows:1)efficient optimal methods,2)implicit and explicit,or complete enumerative methods,a…     

新型层状农药缓/控释材料—草甘膦插层双金属氢氧化物的超分子结构与缓释性能

以镁铝双金属氢氧化物(MgAl layered double hydroxide: MgAl-LDH)为主体, 以草甘膦(Glyphosate: GLY)为客体, 通过控制反应pH值, 由共沉淀法组装得到两种不同结构的GLY插层MgAl-LDH缓/控释材料. 考察了该缓/控释材料在Na₂CO₃溶液中的缓释性能, 其缓释历程为客体阴离子与介质中CO₃^2-的离子交换过程, 客体阴离子在插层化合物层间及晶粒间隙的扩散, 即粒内扩散过程为释放速率控制步. 低pH合成GLY插层产物较大的层间距、层间客体GLY阴离子单层垂直的定位方向及较高的堆积密度使其较高pH合成材料展示出更为显著的缓释能力, 其原因归结为超分子结构对释放速率控制步的影响. 该研究指出了层状双金属氢氧化物在农药缓/控释领域的应用潜力.     

不同降水强度4种草地群落土壤呼吸通量变化特征

利用静态暗箱法, 对内蒙古锡林河流域沿降水梯度4种半干旱草地类型进行了连续2年的野外定位试验, 对比研究了沿降水梯度4种不同草地类型土壤呼吸通量的变化特征, 统计分析了水热因子对草地土壤呼吸通量特征的可能影响, 并建立了土壤呼吸通量与水热因子间的数值关系模式, 同时利用野外连续完整的观测数据对不同草地类型土壤CO₂年排放量分别进行了估算. 结果表明: 土壤呼吸通量存在明显的季节变化规律, 沿降水梯度各草地类型土壤呼吸通量的季节变化型式基本相同, 各草地群落土壤呼吸均以春末和夏季较高, 秋冬季排放量较低, 不同草地类型冬季均观测到土壤呼吸的负通量, 对其机制的进一步研究有利于对土壤年呼吸总量的准确估算; 沿降水梯度4种草地类型土壤年(或生长季)呼吸量均沿降水梯度递减, 表现为贝加尔针茅草原>羊草草原>大针茅草原>克氏针茅草原; 不同草地类型土壤呼吸通量在植物生长季与0~10 cm以及10~20 cm土壤含水量均呈不同程度的正相关, 而与气温和表层土壤温度的相关性较弱, 4种草地类型生长季内土壤表层含水量的变化通常能解释土壤呼吸通量变异的70.2%~94.7%, 而在植物非生长季, 土壤呼吸通量更多地受气温及土壤表层地温的限制, 温度条件的变化能解释土壤呼吸通量变化的70%以上.     

Nanoengineering of amino - functionalized mesoporous silica nanospheres as nanoreactors

Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs. Herein, we have combined “surface-protected etching strategy” and “cationic surfactant assisted etching strategy” to prepare functionalized MSNs with externally attached amino groups. The externally attached NH2 groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane and benzaldehyde. In addition, those NH2-MSNs can also be used to support gold nanoparticles, which display very good catalytic performance for reduction of 4-nitrophenol. It can be envisioned that the synthesis protocol developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors design.     

Effect of cold rolling process on microstructure and mechanical properties of high strength β titanium alloy thin sheets

The microstructure and mechanical properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength titanium alloy sheets prepared by unidirectional cold rolling and two-step cross cold rolling were investigated. Results showed that the β phase grains were refined significantly by cold rolling followed by solution treatment for a short time.Compared to unidirectional cold rolling, the short time solution treatment after two-step cross rolling could significantly reduce the non-uniformity of the microstructure of the alloy sheets. After aging treatment at 550 ℃,the anisotropy of the mechanical properties still existed in the unidirectional rolled sheets, and the tensile strength was highest along the rolling direction. After solution and aging treatment, the anisotropy of the mechanical properties of the two-step cross rolling process sheet was not obvious than unidirectional cold rolling,and alloy had good strength and plasticity matching.     

Enhanced performance of nano-sized SiC reinforced Al metal matrix nanocomposites synthesized through microwave sintering and hot extrusion techniques

In the present study, nano-sized SiC (0, 0.3, 0.5, 1.0 and 1.5 vol%) reinforced aluminum (Al) metal matrix composites were fabricated by microwave sintering and hot extrusion techniques. The structural (XRD, SEM), mechanical (nanoindentation, compression, tensile) and thermal properties (co-efficient of thermal expansion- CTE) of the developed Al-SiC nanocomposites were studied. The SEM/EDS mapping images show a homogeneous distribution of SiC nanoparticles into the Al matrix. A significant increase in the strength (compressive and tensile) of the Al-SiC nanocomposites with the addition of SiC content is observed. However, it is noticed that the ductility of Al-SiC nanocomposites decreases with increasing volume fraction of SiC. The thermal analysis indicates that CTE of Al-SiC nanocomposites decreases with the progressive addition of hard SiC nanoparticles. Overall, hot extruded Al 1.5 vol% SiC nanocomposites exhibited the best mechanical and thermal performance as compared to the other developed Al-SiC nanocomposites.