基于激光扫描的盾构隧道断面提取与变形研究

将三维激光扫描技术应用于盾构隧道变形监测中,提出了一种盾构隧道断面连续提取以及变形分析的方法。首先对拼接完成的点云数据利用随机采样一致性算法提取隧道局部中轴线,基于中轴线对隧道姿态进行调整以截取隧道断面,然后通过聚类去噪算法,基于点到中轴线的距离和灰度值对断面点云进行去噪处理,最后对批量预处理后的点云数据采用椭圆拟合算法获取隧道相对变形信息,提取各断面收敛变形信息,同时基于断面各点变形值生成三维变形云图。采用徕卡Scanstation c10获取上海地铁10号线隧道点云数据,实验证明本文所提出的方法在隧道断面变形监测方面具有实践意义,变形监测精度满足工程需求。     

基于Winsock2 SPI的网络封包截获

基于Winsock2 SPI的网络封包截获,通过系统间加载自编写SPI程序进行中间处理,截获所有发向本机和本机发出的数据包进行分析.并监视每个与外界网络数据包传输的进程,通过合理控制管理规则,使得所有进出的数据包都按照规则处理,以此实现包过滤,达到系统安全监控的目的.     

网卡的工作原理解析及引起故障的原因

对网卡的基本结构进行了分析,详细了解这些组件的功能,进一步加深对网卡工作原理的认识,分析了引起网卡工作故障的主要因素,遇到网卡故障能够及时找出原因,解决故障。     

Simple parameterizations of the radiation budget of uniform broadleaved and coniferous canopies

Simulations of the different components of the spectral radiation budget of structurally simple leaf and shoot canopies with varying canopy leaf area index (LAI) were performed. The aims were (1) to test a proposed parameterization of the budget using two spectrally invariant canopy structural parameters (p and p_t) governing canopy absorption and transmittance, respectively, and (2) to incorporate the effect of within-shoot scattering in the parameterization for shoot canopies. Results showed that canopy spectral absorption and scattering were well described by a single parameter, the canopy p value or ‘recollision probability’, which was closely related to LAI. The relationship between p and LAI was however different in leaf and shoot canopy: e.g., at the same LAI the recollision probability was larger in the shoot canopy. It was shown that the p value of the shoot canopy could be decomposed into the p value of an individual shoot (p_sh) and the p value of the leaf canopy with the same effective LAI (LAI_e). The canopy p value allows calculation of canopy absorption and scattering at any given wavelength from the leaf (or needle) scattering coefficient at the same wavelength. To calculate canopy reflectance, separation of the downward and upward scattered parts is needed in addition. The proposed parameter p_t worked rather well in the leaf canopy at moderate values of LAI, but not in the coniferous shoot canopy nor at high values of LAI. However, the simulated fraction of upward scattered radiation increased in a straightforward manner with LAI, and was not particularly sensitive to the leaf (or needle) scattering coefficient. Judged by this ‘smooth’ behavior, the existence of another kind of simple parameterization for this separation remains an interesting possibility.     

Use of coupled canopy structure dynamic and radiative transfer models to estimate biophysical canopy characteristics

Leaf area index (LAI) is a key variable for the understanding of several eco-physiological processes within a vegetation canopy. The LAI could thus provide vital information for the management of the environment and agricultural practices when estimated continuously over time and space thanks to remote sensing sensors.This study proposed a method to estimate LAI spatial and temporal variation based on multi-temporal remote sensing observations processed using a simple semi-mechanistic canopy structure dynamic model (CSDM) coupled with a radiative transfer model (RTM). The CSDM described the temporal evolution of the LAI as function of the accumulated daily air temperature as measured from classical ground meteorological stations.The retrieval performances were evaluated for two different data sets: first, a data set simulated by the RTM but taking into account realistic measurement conditions and uncertainties resulting from different error sources; second, an experimental data set acquired over maize crops the Blue Earth City area (USA) in 1998. Results showed that the proposed approach improved significantly the retrieval performances for LAI mainly by smoothing the residual errors associated to each individual observation. In addition it provides a way to describe in a continuous manner the LAI time course from a limited number of observations during the growth cycle.     

野兽变美女

变形是影视制作中常用的一种特技手法，常见于动画和科幻影片中，而今天我们要使用的是“奇妙变脸秀3．0（FantaMorph）”这个软件（下载地址：http：／／www.abrosoft．com／doxvrdoad．htm）。只要在两张脸部照片上设置好相应的关键点，就可以创作出充满奇趣的图像变形特效影片。     

歼击机碰撞引导截击效能的影响因素分析

歼击机引导阶段的完成情况直接影响截击效能.本文以雷达发现目标的概率作为截击效能的一个指标,推导了对歼击机碰撞引导时雷达发现目标概率的数学模型,并给出了具体的算例.在此基础上,分析了影响歼击机雷达发现目标概率的主要因素,得出了改善歼击机雷达及导航设备性能可以提高截击效能的结论.     

Robust adaptive control for a class of cascaded nonlinear systems with applications to space interception

This paper proposes a robust H _∞ ‐based adaptive backstepping control scheme for the output stabilization of a special class of cascaded nonlinear systems. This kind of systems possess the feature that the first sub‐equation is a linear perturbed system, whereas the rest ones perform a general semi‐strict feedback form. Different from the conventional backstepping design approach, the special cascaded structure ensures to introduce the H _∞ technique to the backstepping procedure such that both the robust performance and the robust stability can be simultaneously guaranteed. Within the Lyapunov framework, the proposed control scheme is proved to guarantee (i) the uniformly ultimate boundedness of the system signals with a bound that can be made arbitrarily small by suitably choosing control parameters; (ii) asymptotic output stabilization as long as the uncertain nonlinearities and external disturbances vanish; and (iii) ‐performance of the closed‐loop system. A space interception scenario is utilized to demonstrate the effectiveness of the proposed control scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Integrated Game Based Guidance with Nonlinear Autopilot Design for Maneuvering Target Interception

The integrated game theory based guidance law with nonlinear autopilot (GGNA) system is presented in this paper. The guidance law is designed based on linear differential game theory while considering the motion of the target in 3‐D space such that the distance between the missile and the target is minimized faster than before. The autopilot system based on quaternion representation is developed using sliding mode control method to generate the attitude command. The stability of the integrated guidance and nonlinear autopilot system is analyzed with Lyapunov stability theory. In addition, this research assumes wingless missiles in our context in order to reduce the nonlinear effect from the aerodynamics. Furthermore, in order to extend the operation range of missiles from endo‐atmosphere to exo‐atmosphere, the missiles are equipped with Thrust Vector Control (TVC) mechanisms and Divert Control System (DCS). Finally, extensive simulations incorporating aerodynamic models are demonstrated to verify the validity of the proposed integrated guidance/autopilot systems. Moreover, the simulation results reveal that the mission of intercepting a maneuvering target is successfully accomplished.     

API函数截获关键技术研究

文中介绍了API函数截获技术的原理，重点讨论了所涉及到的若干关键技术，剖析了PE文件的引入函数表格式，给出了利用钩子打破进程边界的方法，并对截获过程中存在的不稳定、效率低等问题提出了自己的解决方法。应用文中所介绍的方法，作者在某矿务系统的软件改造项目中成功地实现了基于API截获技术的实时数据采集，完成了对已有软件系统的功能升级。实践证明，API截获技术及其思想具有很强的实用性，可以解决一些常规的方法不能解决的问题，能很好地使用在诸如实时数据采集等场合。