带式输送机驱动系统技术现状及发展趋势

近些年,带式输送机驱动系统技术发展迅速,其中驱动系统是带式输送机的核心系统.基于此,通过分析带式输送机驱动技术的现状,探究了带式输送机不同驱动系统技术的优缺点,介绍了永磁滚筒驱动技术的工作原理和优势,并分析了带式输送机驱动系统技术的发展趋势.     

基于物联网技术的工程机械监控系统设计

分析了基于物联网技术的工程机械监控系统基本功能,并提出了工程机械监控系统的技术方案.在此基础上,建立了工程机械监控系统的架构和体系结构,为基于物联网技术的工程机械监控系统的开发奠定了基础.     

基于特征识别的数控车床自动编程系统研究

开发了基于特征识别技术的数控车床自动编程系统。首先分析了数控车床自动编程系统的功能,以特征识别技术为基础,实现了AutoCAD二维工程图的特征提取,然后在此基础上进行了系统开发和设计,最后给出了实验结果。利用Unified Modeling Language(UML)对系统进行了分析和设计,给出了系统的用例图和类图。研究了系统实现的关键技术:特征识别技术;尺寸公差数据库技术;刀具路径生成技术。利用VC++和ObjectARX联合编程实现了系统的各项功能。     

基于LonWorks技术的化工企业能源管理系统的设计

本文描述了化工企业能源管理系统的技术路线,对该系统采用的LonWorks现场控制网络技术进行了描述,从现场设备层、通信网络层和系统应用层三个层次简要描述了系统的技术特征和应用,并又寸系统中采用的变频节能技术和网络通信方式进行了描述。     

网络化制造环境下ERP系统的研究

建立了网络化制造环境下ERP系统的体系结构,分析了系统所采用的动态建模技术、CORBA中间件技术、工作流管理技术等关键技术,介绍了网络化制造环境下ERP系统运行过程。     

CAD技术及系统研究概述

基于知识驱动的CAD技术代表当前CAD技术发展的方向。文中在分析CAD技术和CAD系统发展和研究状况的基础上,总结了CAD技术的发展趋势,指出了当前CAD系统中存在的不足以及CAD系统的发展方向。最后阐述了基于知识驱动的CAD系统构建的基本原则。     

基于J2EE技术网上采购系统的研究与实现

在研究电子商务与网上采购基本理论与技术的基础上,分析、设计并实现了可在Windows Server 2003环境下运行的网上采购系统.系统实现过程中应用了EJB技术、数据库技术、JSP技术、Servlet技术、Jboss技术等.系统介绍了网上采购系统的基本理论及关键技术,以及网上采购系统分析、设计与实现过程.     

压缩空气系统节能技术的研究进展

介绍了压缩空气系统的节能技术及其应用,探讨了压缩空气系统行业在节能技术方面的发展前景。压缩空气系统主要节能技术有空压机群系统优化、局部增压技术、管网设计、泄漏检测以及基于流量供给的气动节能理论等,从压缩空气的生产、输送到使用环节,提高系统的能源利用效率,为压缩空气系统节能技术提供有价值的发展方向。     

起重机快速定制设计系统研究

在分析现有起重机设计与管理的基础上,提出了起重机快速定制设计系统,研究了系统实现方法学与开发工具、系统功能模型与系统框架。该系统集信息化技术、数据库技术、CAD技术以及知识管理技术为一体,以多样化、差异化的客户需求为驱动,以快速响应为目标,为起重机的快速开发、成本降低与用户满意度的提高奠定了技术基础。     

基于LabVIEW的太阳能数据采集软件系统

结合虚拟仪器技术,设计了基于单片机的太阳能数据采集系统。文中介绍了系统的整体实现方案,重点阐述了在LabVIEW平台下,采用ActiveX技术,通知技术、事件驱动和ADO技术实现软件系统的方法。该系统具有数据采集、实时显示、数据存储及报表生成等功能,实现了对太阳能系统的监测,并为太阳能光伏发电系统输出特性的分析和研究提供数据依据。     

An Assessment Framework for Optimal FMS Effectiveness

Equipment failures in an FMS are significant to performance and can lead to costly, incorrect decisions. Fortunately, effectiveness measurement techniques can be mapped to clever modeling frameworks to help predict, track, and then improve upon the FMS performability or mission effectiveness, and improve maintenance. This article provides sources and guidelines for efficient and effective FMS modeling, a framework for applying the modeling to predict the impact on customers from their point of view, and a method for tying it all together for improving the FMS effectiveness. It is not enough to simply examine the working and failed states of an FMS or even to calculate common reliability metrics. It is necessary to consider the FMS as a whole, and that system includes the needs of the customer and the business. It is also necessary to be purposeful about the measures of performance selected and to support the measures of effectiveness.In this article, we present: a framework for considering customer needs in the measures of effectiveness for FMS; modeling approaches for solving for effectiveness measures; and an example to show how to apply it to an FMS, to improve it or plan for meeting specific customer needs.     

虚拟企业环境下制造合作伙伴选择决策方法研究

在虚拟企业环境下，为了实现敏捷制造低成本、高效率的运作，企业应该将产品进行适当分类，并以此作为选取制造合作伙伴的基本条件。从制造成本的经济性考虑，借助于映射集方法，依照特定的条件和规则，将种类繁多的待生产零件进行映射分类，建立了相应的模型。为解决供应链合作伙伴的选择问题，运用理想解类似度偏好顺序评估法建立了多目标决策的算法模型，并结合产品研发过程进行了实例分析计算，取得了理想合作伙伴的选择结果。该结果能客观反映实际情况，对企业进行敏捷制造实现优化的生产组织具有指导意义。     

石墨消解连续光源原子吸收法测定废气中重金属

采用DEENA石墨消解仪对采集的废气样品进行前处理,利用contrAA700连续光源原子吸收光谱仪测定样品中重金属铜、锌、镍、铅、镉、锰。本试验优化了消解液的组合,使样品消解更完全,且克服了传统火焰原子吸收法需要更换空心阴极灯的缺陷,提高了分析速度。各元素的检出限分别为铜0.0025mg/m~3,锌0.0012mg/m~3,镍0.0038mg/m~3,锰0.0025mg/m~3,铅0.0075mg/m~3,镉0.0025mg/m~3。各元素的回收率分别为铜94.2%,锌102.5%,镍95.6%,锰104.1%,铅97.3%,镉95.3%。本方法具有较高的准确度,相比传统的火焰原子吸收法有更高的工作效率,适用于废气中多种重金属的同时测定。     

Registration and Data Merging for Multiple Sets of Scan Data

It is generally necessary in 3D scanning to divide a wrap-around object into several regions, each of which is measured individually. A series of pre-processing procedures must be implemented to prepare the data for use for surface reconstruction. Registration is a procedure for unifying the coordinate systems for multiple sets of scan data. Three registration algorithms, 3 points to 3 points, 3 spheres to 3 spheres and 3 planes to 3 planes, are proposed to suit different applications. Data merging is a procedure for removing overlapping data for multiple sets of scan data and for merging them into one set. A data search algorithm, based on triangulation, is com-bined with a few merging rules to merge the data in terms of different needs. Several experimental results are presented to demonstrate the feasibility of the proposed algorithm.     

Aptamer based detection and separation platforms for ochratoxin A: A systematic review

Ochratoxin A (OTA), one of the most dangerous mycotoxins for human health, has been subjected to numerous studies for separation and detection in minimal amounts. Aptamers as novel recognition elements have been employed to fabricate ultrasensitive biosensors for the detection of OTA and designing delicate analytical tools. This review attempted to comprehensively examine all reported aptamer-based detection and separation platforms for ochratoxin. The most relevant databases were considered to discover all specific aptamers for dealing with OTA. Aptamer-based detection and separation devices specified for OTA were searched for, analyzed, discussed, and classified based on their specifications. The optical aptasensors have gathered a higher interest than electrochemical aptasensors, which can achieve a lower limit of detections. Moreover, some extraction platforms based on these aptamers were also found. However, aptamer-based devices seem to have some challenges in their application.     

大学的“我思故我在”

人因思想而成为人,还因善于思想而成为更聪明、更智慧、更高大的人。大学不仅由思想者来传递思想,而且要由思想者生产思想,进而传递思想,大学因思想而存在。大学是思想的摇篮,是思想家的摇篮,必定担负起生长和培育智慧的崇高使命。而要为智慧提供空间、为创造提供更大的可能,大学则需要自由。中国的大学尚需要更多的自由,自由的大学才是好的大学。大学确实需要明白“我思故我在”的深刻含义。     

Exact dynamic analysis of composite beams with partial interaction

The partial differential equations and general solutions for the deflection and internal actions and the pertaining consistent boundary conditions are presented for composite Euler-Bernoulli members with interlayer slip subjected to general dynamic loading. Both free and forced vibrations are treated. The solutions are shown to be unique and complete under certain conditions, and valid for all so-called restricted admissible boundary conditions. Specifically, the exact eigenmode length coefficients are derived for the four Euler BC. They differ from those valid for ordinary, fully composite (solid) beams, except for the pinned-pinned case. The maximum deviation for beams with the other three Euler BC is shown to be less than 2-6% with respect to the eigenmode length coefficient and 3-10% with respect to the eigenfrequency, respectively, depending on the two non-dimensional parameters, composite action or shear connector stiffness and relative bending stiffness parameters. However, these deviations occur in a rather narrow range of the determining parameters, so for most practical cases the eigenmode length coefficients given for solid (fully composite) beams can approximately be used also for partially composite beams. The procedures of analysing beam vibrations are applied to a specific case. These solutions illustrate the effect of interlayer connection on the peak velocity of the beam vibrations. The proposed analytical theory is verified by tests and finite element calculations.     

Development of an integrated wireless sensor network micro-environmental monitoring system

Wireless Sensor Network (WSN) is increasingly popular in the field of micro-environmental monitoring due to its promising capability. However, most systems using WSN for environmental monitoring reported in the literature are developed for specific applications without functions for exploiting user's data processing methods. In this paper, a new system is designed in detail to perform micro-environmental monitoring taking the advantages of the WSN. The application-oriented hardware working style is designed, and the system platform for data acquisition, validation, processing and visualization is systematically presented. Several strategies are proposed to guarantee the system capability in terms of extracting useful information, visualizing events to their authentic time are also described. Moreover, a web-based surveillance subsystem is presented for remote control and monitoring. In addition, the system is extensible for engineers to carry their own data analysis algorithms. Experimental results are to show the path reliability and real-time characteristics, and to display the feasibility and applicability of the developed system into practical deployment.     

Comparisons of optimality criteria for minimum-weight dual material structures

A criterion established by Prager for minimum-weight design of structures, using different materials for tension and compression members, referred to here as bi-material structures, appears to have been completely overlooked in the literature. Cantilever and simply supported beam designs are analyzed to compare the result of applying this criterion with the conditions established by Michell in his groundbreaking paper on structural optimization. Surprisingly, for statically determinate bi-material structures, Michell's original conditions for minimum volume, also ensure minimum weight. However, for statically indeterminate structures, Michell's criterion does not give least weight unless the ratio, of yield stress to density, is the same for tension and compression members. For statically indeterminate cantilever design cases analyzed in this paper, the weight differences between those satisfying Michell's and Prager's conditions are shown to be very small, even when the ratio of yield stress to density tension differs by a factor of 7 between the tension and compression members. This allows the selection of alternative structural layouts for other attributes than minimum weight.     

A PORTABLE TUNGSTEN COIL ATOMIC EMISSION SPECTROMETER WITH TWO COILS

Tungsten coils have been employed recently in instruments that may be used for field applications. Intense emission signals and μg/L limits of detection (LOD) have been observed for alkali metals, alkaline earth metals, and some lanthanides (such as Yb and Eu). However, for many transition elements, relatively high LODs are observed due to the insufficient excitation energy provided by the coil at high temperature. In this study, two tungsten coils are employed in an attempt to increase the emission signal and lower the LOD. A lower coil is heated to vaporize the sample, and then a second upper coil is heated at high temperature to excite the sample atoms. The emission signal is viewed above the upper coil. Six test elements (Co, Fe, Ag, Cu, Cr, and Yb) are used to compare the performance with one and two coils. Double tungsten coil atomic emission is reported for the first time for all six elements. Addition of the second coil improved the LOD by a factor of 70 for Cu and Ag; a factor of 40 for Co; a factor of 12 for Fe; and a factor of 2 for Cr and Yb. All six elements can be determined in one simple spectrum with the two-coil system. Cobalt, Fe, Cr, and Cu were determined in a certified polluted water reference sample to evaluate the accuracy of the system. Recoveries were in the range of 93–102% for all elements.