一种新的涉密数据跨域传输机制

针对涉密数据在多个域之间传输的安全需求,介绍一种新的涉密数据跨域传输机制。该机制基于一种新的跨域认证与密钥建立协议,借助各域内的监督服务器完成双向认证,并结合签密法建立新的文件传输密钥。安全分析证明,该机制能保证不同安全等级域之间涉密数据传输的安全性和隐密性,并能抵御多种安全攻击。     

有物体群的多连通域有限差分网格自动生成

用有限差分方法解算了坐标变换偏微分方程式,创建了便于多连通域差分计算的非正交网格,列出了坐标变换的迭代计算差分方程式,计算了三个算例,绘制了各算例的网格图形和表明变换对应关系的图形边界坐标示意图,讨论了一些迭代计算技术问题。     

Simulated recruitment of riparian trees and shrubs under natural and regulated flow regimes on the Wisconsin River,USA

Models that link ecological responses to hydrologic changes are important for assessing the effects of flow regulation on aquatic and riparian ecosystems. Based on the Recruitment Box Model, a graphical model used to prescribe environmental flows for cottonwood (Populus spp.) recruitment, we designed a simulation model to represent the influence of river flow dynamics on seedling recruitment of riparian pioneer woody plants. The model simulates the influence of temporal patterns of river stage on dispersal, germination, initial recruitment and over‐winter survival of first‐year seedlings of riparian pioneer shrubs and trees. We used the model to simulate seedling recruitment patterns for five species (Acer saccharinum, Betula nigra, Populus deltoides, Salix nigra and Salix exigua) on the Wisconsin River (Wisconsin, USA) under three flow scenarios: historic (1935–2002), simulated natural (1915–1975) and simulated regulated flows (1915–1975). Simulation results agreed well with field‐observed relative differences among years (1997–2000) in seedling densities for the five focal species. Simulated successful recruitment years were highly synchronous among species, but species differed in their sensitivity to flows at different times during the growing season, consistent with among‐species differences in seed dispersal timing. Comparison of simulated natural and regulated flows for 1915–1975 showed that flow regulation decreased monthly flow variability, increased late summer to winter baseflow and reduced the magnitude of spring peaks. Simulated recruitment and over‐winter survival of tree seedlings of all species was enhanced under the regulated flow scenario, likely due to increased summer baseflow and reductions in peak flood magnitude. Our analyses show the utility of extending the Recruitment Box Model to include multiple species of riparian shrubs and trees, and the effects of post‐colonization flows on their recruitment success. However, some key functional relationships between flow patterns and woody seedling demography (e.g. shear stress thresholds for seedling mortality) have not been adequately quantified and merit further study. Copyright © 2006 John Wiley & Sons, Ltd.     

工程地质数据库设计与系统建设探讨

随着我国土木工程建设的蓬勃发展,工程地质数据量出现爆发式增长,如何实现工程地质数据的共享、海量存储和异地传输显得尤为重要。全面阐述了工程地质数据库的设计、内容、建设流程及其应用。实践表明,工程地质数据库的建立不仅可以提高地质勘察工作效率,还可以为地质勘察成果的整合共享提供重要的基础。      

2012伦敦奥林匹克公园的生态种植设计

介绍了詹姆斯·希契莫夫(James Hitehmough)和奈杰尔·邓内特(Nigel Dunnett)教授为2012年伦敦奥林匹克公园设计和营造草本植物群落景观的相关工作.伦敦奥林匹克公园可能是奥运会发展至今最具可持续发展观的,这一理念在250hm2的绿地景观中得到了充分展示.场地种植设计的亮点,是营建生态结构合理的植物群落以最大尺度的实现稳定可持续性.形态和季相色彩丰富的绿地景观不仅为奥运会期间的游人服务,之后大部分的景观会得以保留,进而成为伦敦东部的一个新的地区公园.描述和讨论了公园和自然式的种植设计在当前追求更加持续稳定的城市环境设计中的实践和理论哲学地位.     

大学英语阅读教学中的"图式建立"

依据图式理论及图式在阅读理解中的作用提出了“图式建立”的阅读教学。文中提出了教学中应建立的图式(结构图式、内容图式、文化图式)及“图式建立”的教学方法。“图式建立”的教学在于有效激活学生已有的相关图式,提供给学生所缺的相关图式,同时帮助构建起新的图式。“图式建立”以丰富学生在阅读理解时所需的各种背景知识为途径,达到促进学生阅读能力提高的教学目的。     

民用住宅建筑环保治污节能功能研究

现代社会的民用建筑作为人们学习、工作、娱乐、生活的空间产生着大量的固体垃圾，废气、污水，严重污染了环境，危害人们的健康，对自然生态的破坏与日俱增，建筑应有环保治污节能的功能，并建立民用建筑的环保立法，有效地引导和规范人们的环保意识和行为，做到污染的超前处理，将建筑污染减轻到最小程度，甚至为零，发展了环保产业，对整个环保事业起到积极的作用。     

无线传感器网络密钥建立协议的能耗分析

从密钥存储量负载、通信负载和节点能耗等方面,对三个具有代表性的密钥建立协议SPINS、Random Key Scheme和PeerSiz进行了能耗测试和分析,结果表明:尽管基于对称密码体制的密钥建立协议的能耗远小于基于公钥体制的协议,但是如果选择部署了合适的密码算法,如ECC-160,基于公钥体制的密钥建立协议也能够较好地适应无线传感器网络环境。     

PAACP: A portable privacy-preserving authentication and access control protocol in vehicular ad hoc networks

Recently, several studies addressed security and privacy issues in vehicular ad hoc networks (VANETs). Most of them focused on safety applications. As VANETs will be available widely, it is anticipated that Internet services could be accessed through VANETs in the near future. Thus, non-safety applications for VANETs would rise in popularity. This paper proposes a novel portable privacy-preserving authentication and access control protocol, named PAACP, for non-safety applications in VANETs. In addition to the essential support of authentication, key establishment, and privacy preservation, PAACP is developed to provide sophisticated differentiated service access control, which will facilitate the deployment of a variety of non-safety applications. Besides, the portability feature of PAACP can eliminate the backend communications with service providers. Therefore, better performance and scalability can be achieved in PAACP.     

高职工程测量课程研究

探讨了建筑工程测量课程改革的必要性，分析了建筑测量课程的职业目标和职业技能，提出了课程四个模块的构建方法，在教学中实行理论教学和实践教学一体化，采用实物教学、演示教学、现场教学等手段，实行教练交替的方式组织课堂，并介绍了围绕职业技能的课程评价方法。