一种基于自证明公钥的可公开验证的认证加密方案

针对现有的基于证书的认证加密方案通信量和计算量大的缺点,提出了基于自证明公钥的可公开验证的认证加密方案。详细阐述了方案的系统初始化、签名生成、消息恢复验证以及公开验证4个阶段,方案的安全性是基于求解离散对数的困难性(DLP)和强单向hash函数(OWFH)的不可逆。该方案在没有签名者的协作下,任何验证者都可验证签名者的诚实性,在验证签名的同时可认证签名者的公钥,因而减少了存储空间、通信量和计算量。     

基于Windows消息机制的人机交互的研究与应用

结合实例着重介绍了如何通过串行通讯利用Windows的消息机制来解决目前工业设备控制中人机交互的模拟问题,并对这两种技术进行了详细的论述.     

Minor planet short periodic perturbations: The indirect part of the disturbing function

Leverrier's development of the indirect part of the disturbing function has been extended to include terms up to degree 4 in eccentricity and inclination; the resulting series has been expressed with respect to a fixed plane, and in a computer readable form (a list of integers). Tests have been performed for the relative significance of the terms of degrees 2, 3 and 4, and estimates have been obtained for the accuracy of the short periodic perturbations of a minor planet, and of the corresponding mean orbital elements. It was found that: (i) even in extreme cases, the indirect part of the disturbing function gives rise to very small short periodic perturbations; (ii) bodies of very high eccentricity/inclination and those close to mean motion resonances are most significantly affected; (iii) indirect perturbations for minor planets can be computed up to the degree 2 terms only, without any significant loss of accuracy; and (iv) higher degree indirect perturbations appear to be important only for their contribution to the long periodic effects of higher order (with respect to the perturbing mass).     

The influence of macrophyte growth,typical of eutrophic conditions,on river flow velocities and turbulence production

The influence of emergent and submerged macrophytes on flow velocity and turbulence production is demonstrated in a 140 m reach of the River Blackwater in Farnborough, Hampshire, UK. Macrophyte growth occurs in patches and is dominated by Sparganium erectum and Sparganium emersum. In May 2001, patches of S. erectum were already established and occupied 18% of the channel area. The flow adjusted to these (predominantly lateral) patches by being channelled through a narrower cross‐section. The measured velocity profiles showed a logarithmic form, with deviations attributable to topographic control. The channel bed was the main source of turbulence. In September 2001, in‐stream macrophytes occupied 27% of the channel, and overhanging bank vegetation affected 32% of the area. Overall flow resistance, described by Manning's n, showed a threefold increase that could be attributed to the growth of S. emersum in the middle of the channel. Velocity profiles showed different characteristic forms depending on their position relative to plant stems and leaves. The overall velocity field had a three‐dimensional structure. Turbulence intensities were generally higher and turbulence profiles tended to mirror the velocity profiles. Evidence for the generation of coherent eddies was provided by ratios of the root mean square velocities. Spectral analysis identified deviations from the Kolmogorov ?5/3 power law and provided statistical evidence for a spectral short‐cut, indicative of additional turbulence production. This was most marked for the submerged vegetation and, in some instances, the overhanging bank vegetation. The long strap‐like leaves of S. emersum being aligned approximately parallel to the flow and the highly variable velocity field created by the patch arrangement of macrophytes suggest that the dominant mechanism for turbulence production is vortex shedding along shear zones. Wake production around individual stems of S. emersum close to the bed may also be important locally. Copyright © 2006 John Wiley & Sons, Ltd.     

船舶机舱自动集中监测报警系统结构与功能分析

船舶机舱集中监测与报警系统目前已在船舶设计制造中得以广泛应用。对其组成、工作流程及功能进行了较为系统的阐述 ,为船舶使用者提供借鉴     

A Study on Hydroelastic Response of Box-Type Very Large Floating Structures

The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long     

基于卫星短消息通信的大地测量信息传输技术

无线通信是大地测量内外业一体化生产中的瓶颈问题。首先介绍了大地测量信息传输系统的基本功能,给出了通信管理功能的基本结构,然后重点讨论了通信管理中的一些关键技术:用户终端与计算机控制程序之间的信息组织、利用CRC校验和多重确认进行误码控制、建立传输队列来防止信号失锁造成的信息拥塞。最后通过试验分析,验证了利用卫星短消息通信进行大地测量信息传输的可行性。     

Galileo开放服务导航电文特点分析

介绍了Galileo系统开放服务接口控制文件中导航信号及电文的概况,并在如何满足导航电文中各种不同参数数据的时效性、如何缩短用户接收机导航数据接收时间、如何支持多系统互操作等方面对其特点进行了分析介绍。     

基于GPS的短基线定向测量及精度分析

介绍了利用GPS载波相位测量技术进行短基线定向的基本方法,推导了估计GPS短基线定向的精度公式,得到了对于边长400～700 m的基线可以达到±(1"～2")的方位精度.     

基于消息通知机制的国省数据共享系统的设计与实现

为解决卫星广播传输缺陷及省级用户获取临省实时观测资料和实况分析产品等迫切的业务需求，设计并实现了基于消息通知机制的国省数据共享系统。系统基于RabbitMQ的消息机制进行业务和数据资源的整合及集成，采用多层体系架构，满足基于地面宽带的数据快速有序下载和卫星广播数据补调等国省数据共享需求，支持大容量多种数据的高速传输，支持HTTP、FTP、SFTP等多种数据传输协议。系统已经上线提供服务，实现智能网格、多源融合实况分析等25种气象资料的国省数据共享，月平均共享数据量达6.3 TB，且建立全流程监视，有效保障数据共享的时效性。