黑河干流中游地区耗水量变化的历史分析

黑河流域水资源极其匮乏，加之地区上的配置不均衡和中游地区水土资源的过度开发，导致黑河下游出现了严重的生态环境问题，已影响到我国北方广大地区生态环境质量，受到国家的高度重视和全社会的广泛关注。黑河水资源开发利用主要集中在中游地区，该区是全国重要的商品粮、蔬菜和经济作物生产基地之一，耗水量占流域耗水量的85％以上，是黑河的主要耗水区和径流利用区。利用黑河上游控制站莺落峡站和中游控制站正义峡站水文资料，分析了黑河中游耗水量的变化，结果表明：20世纪80年代以前黑河中游耗水量在4．4亿m^3左右，比较稳定；进入20世纪80年代以后，耗水量明显增加，80年代耗水量比70年代以前增加了1．97亿－2.49亿m^3;90年代耗水量又比80年代增加了1.64亿m^3左右；80年代以来流域耗水量呈明显增加的趋势，这是以人类活动影响为主的结果。     

非晶Sm5Fe74.3Nb1.5Si11.7B4.5C2.5Cu0.5合金经预退火后的晶化动力学的DTA研究

研究了非晶Sm5Fe74.3Nb1.5Si11.7B4.5C2.5Cu0.5合金经400℃，保温10min预退火后的晶化动力学。结果表明；该合金的晶化相为α-Fe固溶体和Sm2Fe17Cx金属间化合物，两相的晶化表观激活能分别为557KJ/mol和514KJ/mol，当晶化体积分数为60%时，α-Fe相的晶化激活能达极大值；Sm2Fe17Cx相晶化激活能则随其晶化体积分数的增加而逐渐减小。     

A force modulation study on crystallization process in ferroelectric vinylidene fluoride and trifluoroethylene copolymer films

This paper introduces the Force Modulation technique to the study of crystallization process in ferroelectric vinylidene fluoride and trifluoroethylene copolymer films. Using this technique we have successfully visualized ferroelectric crystalline domains and observed that these ferroelectric domains grow out from amorphous phase, unite into strip-like structures, and finally congregate into a union. Force Modulation can weaken the influence of topography on imaging of ferroelectric domains, and reveal more details, which are difficult to be observed in topographical image.     

创建FTP服务器和设计磁盘配额的方法与实现

FTP是网络系统提供的基本服务之一．用户可以通过FTP上传和下载文件。本文介绍Linux系统的FTP服务器的原理以及建立FTP服务器和对FTP用户的磁盘配额进行设置。     

Apply geometric duality to energy-efficient non-local phenomenon awareness using sensor networks

A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network.     

LF6铝合金的超塑性／扩散连接组合工艺试验及理论研究EI

本文研究了ＬＦ６铝合金的超塑性／扩散连接组合工艺，用变形和再结晶的方法细化晶粒，成功地进行了ＳＰＦ／ＤＢ工艺试验，利用电子探针观察了扩散连接接头的界面微观区域，并从机理上分析了金属的超塑性／扩散连接两种工艺之间的内部联系及其金属学行为。     

冲击回波法检测隧洞混凝土衬砌厚度

冲击回波法是通过接收、分析在混凝土中传播的回波信号，判断结构混凝土厚度和内部质量的新型无损检测技术。室内试验和工程应用研究表明，该方法为隧洞混凝土衬砌厚度检测提供了一个有效的测试手段。     

德国大型设备的出口包装

一、前言德国作为全球几大工业国之一,是世界上有名的机械电子设备出口国。这些年来大量的德国大型设备和生产线成套设备漂洋过海出口到了中国,这些设备涉及到汽车、石油、化工、钢铁、机械、电子等行业。怎样保证这些大型设备和成套设备安全抵达中国或其它国家用户所在地,是摆在德国有关生产企业与运输包装企业面前的重要课题。本文结合作者在德国汉堡出口包装有限责任公司——塞库瑞塔斯公司(Securitas)看到的情况,介绍一下有关德国大型设备出口包装的方法。     

Power levels and packet lengths in random multiple access with multiple-packet reception capability

This paper extends our earlier results. We assume that the receiver has the capability of capturing multiple packets so long as the signal-to-interference-plus-noise ratio (SINR) of each packet is above a designed threshold T throughout its transmission period. We prove that, compared with a multiple-power-level system, the single-power-level system in which all nodes transmit at the maximum allowable power level achieves optimal throughput, under a condition that T exceeds the value 3.33. Given a minimum throughput requirement, under the same condition on T, the single-power-level system also achieves the maximum average packet capture probability as well as the optimum energy usage efficiency. If the multiple-power-level systems are constrained such that higher power levels always have shorter packet lengths, then the above results hold for T greater than 2.