基于机床螺纹加工技术的深析

文章结合笔者的实际情况主要阐述了介绍了一种变螺距精密螺纹套管加工的专用数控套车机床的工作原理、基本组成.重点分析了该机床数控径向切削进给的实现方法,以及多刀同时切削多头螺纹的技术实现,给出了工程应用实例.     

计算机技术在档案管理中的运用浅析

随着信息技术的快速发展,计算机技术在人们的日常生活与工作中发挥着越来越重要的作用,对于档案管理工作来言也是如此.本文首先分析了计算机技术在档案管理中运用的必要性,然后分析、总结了目前计算机技术在档案管理中的一些具体运用及其运用过程中存在的问题,并在文章最后提出了几点加强计算机技术在档案管理工作中运用的对策与建议.     

浅谈LED电子显示屏在幕墙系统中的应用

随着计算机技术、光学、电子技术、视频技术、传送技术的发展,各种电子屏幕设备的应用日益增多.在众多的影像设备中,LED电子显示屏是集光电子技术、视频技术、计算机技术和微电子技术为一体的科技产品.LED因其强大的功能在各行各业中得到了广泛的应用.     

Feature selection via sensitivity analysis of SVM probabilistic outputs

Feature selection is an important aspect of solving data-mining and machine-learning problems. This paper proposes a feature-selection method for the Support Vector Machine (SVM) learning. Like most feature-selection methods, the proposed method ranks all features in decreasing order of importance so that more relevant features can be identified. It uses a novel criterion based on the probabilistic outputs of SVM. This criterion, termed Feature-based Sensitivity of Posterior Probabilities (FSPP), evaluates the importance of a specific feature by computing the aggregate value, over the feature space, of the absolute difference of the probabilistic outputs of SVM with and without the feature. The exact form of this criterion is not easily computable and approximation is needed. Four approximations, FSPP1-FSPP4, are proposed for this purpose. The first two approximations evaluate the criterion by randomly permuting the values of the feature among samples of the training data. They differ in their choices of the mapping function from standard SVM output to its probabilistic output: FSPP1 uses a simple threshold function while FSPP2 uses a sigmoid function. The second two directly approximate the criterion but differ in the smoothness assumptions of criterion with respect to the features. The performance of these approximations, used in an overall feature-selection scheme, is then evaluated on various artificial problems and real-world problems, including datasets from the recent Neural Information Processing Systems (NIPS) feature selection competition. FSPP1-3 show good performance consistently with FSPP2 being the best overall by a slight margin. The performance of FSPP2 is competitive with some of the best performing feature-selection methods in the literature on the datasets that we have tested. Its associated computations are modest and hence it is suitable as a feature-selection method for SVM applications. Editor: Risto Miikkulainen.     

间接竞争ELISA方法用于脱落酸的检测

该文研制了植物激素脱落酸(ABA)间接竞争酶联免疫试剂盒,该试剂盒可对ABA进行快速检测.文中成功制备了脱落酸和牛血清蛋白的交联物(ABA-BSA),并对交联物的浓度、抗体稀释度、酶标二抗稀释度对实验的影响进行了考察.结果表明,该试剂盒具有高灵敏性,最低检出浓度为1.38 ng/mL,在10ns/mL～1 000 ng/mL之间,吸光度与浓度的对数呈良好的线性关系.样品添加回收率在95.98%～102.25%之间,平均回收率为100.18%,变异系数(CV)在1.27%～4.68%之间,平均变异系数为3.18%.     

A novel fault-tolerant execution model by using of mobile agents

The exponential expansion of the Internet and the widespread popularity of the World Wide Web give a challenge to experts on reliable and secure system design, e.g., e-economy applications. New paradigms are on demand and mobile agent technology is one of the features. In this paper, we propose a fault-tolerance execution model by using of mobile agents, for the purpose of consistent and correct performance with a required function under stated conditions for a specified period of time. Failures are classified into two classes based on their intrinsic different effects on mobile agents. For each kind of failure, a specified handling method is adopted. The introduction of exceptional handling method allows performance improvements during mobile agents’ execution. The behaviors of mobile agents are statistically analyzed through several key parameters, including the migration time from node to node, the life expectancy of mobile agents, and the population distribution of mobile agents, to evaluate the performance of our model. The analytical results give new theoretical insights to the fault-tolerant execution of mobile agents and show that our model outperforms the existing fault-tolerant models. Our model provides an effective way to improve the reliability of computer systems.     

曼彻斯特编码技术在测井数据传输中的应用研究

基于曼彻斯特码编码技术文章提出一种适用于石油测井下行数据传输链路的设计方案。采用Verilog HDL设计的曼彻斯特编、译码器,在ALTERA公司的QuartusⅡ6．0软件平台上完成了仿真,并在FPGA器件上实现了硬件测试．最后下行数据传输链路的发送端和接收端在6km的电缆模拟器上完成了系统测试。通过计算机仿真和工程实现验证了该设计方法的正确性和实用性。     

一种基于ENVI二次开发的遥感薄云去除方法的改进

近年来常用的同态滤波去云算法因其采用滤波器的局限性只能去除低频区域的云而无法去除高频区域的云。因此在分析传统的同态滤波去云算法的基础上,引入了空域滤波,采用中值滤波器对图像进行处理,旨在去除高频区域的云。而后在ENVI遥感图像处理软件平台中采用IDL语言实现了算法并对ENVI进行二次开发。经实验结果分析表明,该法是有效的,并且为遥感数据的后续应用提供了方便。     

基于FPGA的PCI总线接口设计与实现

文章提出了一种基于FPGA的PCI接口控制器的设计方案,重点叙述了PCI控制器核心的状态机的设计原理与结构,对时序设计进行了分析,并进行TN试仿真,经验证后速度和正确性均达到设计要求。