基于AX.25协议的PLC无线通信

提出一种PLC与无线通信模块的接口方案，实现了PLC之间的半双工无线通信，解决了收发切换和通信可靠性问题，给出了实际的接口电路和通信的帧格式。     

Symbol Grounding or the Emergence of Symbols? Vocabulary Growth in Children and a Connectionist Net

The Symbolic Grounding Problem is viewed as a by-product of the classical cognitivist approach to studying the mind. In contrast, an epigenetic interpretation of connectionist approaches to studying the mind is shown to offer an account of symbolic skills as an emergent, developmental phenomenon. We describe a connectionist model of concept formation and vocabulary growth that auto-associates image representations and their associated labels. The image representations consist of clusters of random dot figures, generated by distorting prototypes. Any given label is associated with a cluster of random dot figures. The network model is tested on its ability to reproduce image representations given input labels alone (comprehension) and to identify labels given input images alone (production). The model implements several well-documented findings in the literature on early semantic development; the occurrence of over- and under-extension errors; a vocabulary spurt; a comprehension/production asymmetry; and a prototype effect. It is shown how these apparently disparate findings can be attributed to the operation of a single underlying mechanism rather than by invoking separate explanations for each phenomenon. The model represents a first step in the direction of providing a formal explanation of the emergence of symbolic behaviour in young children.     

Ultrasonic characterization of porous silicon using a genetic algorithm to solve the inverse problem

This paper presents a method for ultrasonic characterization of porous silicon in which a genetic algorithm based optimization is used to solve the inverse problem. A one-dimensional model describing wave propagation through a water immersed sample is used in order to compute transmission spectra. Then, a water immersion wide bandwidth measurement is performed using an insertion/substitution method and the spectrum of signals transmitted through the sample is calculated using Fast Fourier Transform. In order to obtain parameters such as thickness, longitudinal wave velocity or density, a genetic algorithm based optimization is used.A validation of the method is performed using aluminium plates with two different thicknesses as references: a good agreement on acoustical parameters can be observed, even in the case where ultrasonic signals overlap.Finally, two samples, i.e. a bulk silicon wafer and a porous silicon layer etched on silicon wafer, are evaluated. A good agreement between retrieved values and theoretical ones is observed. Hypothesis to explain slight discrepancies is proposed.     

摩擦焊机液压、转速测控系统串行通信设计

介绍的摩擦焊机测控系统是以工业PC为主控机，液压，转速测控单元用2个单片机系统实现，文中讨论了工业PC机与2个单片机系统通信的硬件连接，通信原理及协议，并用VisualC^ 6.0实现了在Windows平台上的多机串行通信。     

充分发挥桥梁作用 促进锆铪事业发展——第2届全国锆铪纤业大会工作报告

介绍了2004年以来我国钛锆铪产业的发展概况，总结了2年来中国有色金属工业协会钛锆铪分会所作的主要工作。指出了2007年钛锆铪分会工作的重点是做好半年和全年的生产运行统计和调研工作，抓好分会的组织建设，办好钛锆铪分会的网站和会刊，为企业提供更专业更细致的服务。     

滨海电厂大型室外装置外覆镀锌板材表面防腐涂料选择及施工

针对电厂室外大型装置的外覆层镀锌板材,综合考虑有较高温度变化和滨海气候的侵蚀,选择CD-501,CD-502系列作为防腐涂料,并组织施工。     

Development of a FEM-model for the simulation of the transfer of surface structure in cold-rolling processes

In the temper rolling process the effect of transferring the roll-surface structure to the steel sheet is purposively used to adjust a defined sheet-surface structure required for further processing. The objective of the investigation presented in this paper is to analyze the transfer behaviour specific to the electron-beam texturing technique (EBT) and, in addition to that, to develop a model for the simulation of these transfer characteristics. For this purpose in the first part the results of a study on the basis of rolling tests on an industrial temper mill are presented. These results do not only point out the basic transfer mechanisms - penetration processes and reverse extrusion phenomena - but beyond that also lead to an explanation of the transfer behaviour specific to the rolling conditions by the application of similarity numbers (substitute profile model). On the basis of these results in the second part a model is developed to simulate the transfer characteristics by the application of the finite element method (FEM).     

Information model for the integration of inspection activity in a concurrent engineering framework

The basis of the integration of activities related to the product life cycle is, mainly, the creation of a unique and coherent information model along all the stages in the cycle. Up to date, dimensional inspection activities have not been deeply analysed, possibly due to the fact that, their work influences are smaller than others, such us numerical analysis, materials or numerical control. However, the integration of dimensional inspection is very important for several reasons: the need of specifying the design and planning of the inspection process from the conceptual part design; the increase of use of high speed coordinate measuring machine (CMM) in the production lines; and finally, for the interest of a feedback between data inspection and manufacturing processes. This paper is a detailed proposal of an information model for inspection based on operations for CMM, which represents a consistent structure of the necessary data in an integrated product setting.     

The influence of the air occluded in the deposition layer of flux during automatic welding: a technological aspect to consider in the quality of the bead

The submerged arc welding (SAW) process is widely used in Cuban industries and it is highly reliable. The flux and wire electrode feeds are carried out simultaneously during the SAW process. The flux forms a layer, and beneath it is the wire producing the electric arc. During the deposition of the flux, a certain amount of air (1.293 g/l and filling 48% of the total layer) stays hidden among interstices between the grains. The air is formed of approximately 21% oxygen and 77% nitrogen; these gases are undesirable during the SAW process. When the granulometric distribution and the grain shape of the flux are not known, an unexpected effect can occur on the mechanical properties of the weld bead. This effect has sometimes been imputed to other problems such as incorrect previous calcinations of the flux. The conjunction of the morphological characteristics of the grain and its granulometric distribution are aspects that have not been sufficiently studied, in relation to the air potentially occluded in the free spaces between the grains.     

对称比例方向阀控制非对称缸在矫直机辊缝自动调节上的应用

介绍一种采用液压比例阀控制辊缝的新型管材矫直机的液压控制系统,通过PLC控制比例阀来控制液压缸位置,达到辊缝的自动调节和偏差补偿。此新型管材矫直机采用8个阀控缸系统,实现辊缝自动调节,自动化程度高,辊缝调节简便。在8个阀控缸系统中,由于对称阀控制非对称缸难度较大,只针对其中的非对称缸系统采用DSHplus软件进行了建模和仿真分析。对对称阀控制非对称缸系统特性进行进一步的探讨,与对称阀控制对称缸系统进行比较,并针对对称阀控制非对称缸系统的两种常见补偿方法进行建模仿真,分析其补偿效果。     

当前我国社会分层与高等教育机会探析--对某所高校2000级学生的实证研究

当前，来自农村和城镇的考生以及父亲身份分别是农民、工人、干部的子女在高等教育的入学机会和专业入读上存在着明显的不均等。这些现象的存在既有其客观必然性，也与综合素质的差异和填报志愿选择有关，同时，还不能排除招生工作的社会腐败现象和不正之风。解决这些问题，一是要加速高等教育大众化步伐，扩大高等教育机会；二是注重综合素质教育，特别是加强农村中小学的综合素质教育；三是改革高考录取制度，减少填报志愿的盲目性；四是严肃高校招生纪律，减少或杜绝招生工作中的不良之风，同时应制定相关的政策，使社会学中的补偿原则和反向歧视理论在高校招生中得到一定体现，使农村考生获得更多的高等教育机会。     

Validation of a modified material model for use with shell elements to improve the predictive accuracy of the thickness distribution in superplastic forming of sheet metals

The automotive industry has recently begun using the superplastic forming (SPF) process to fabricate complex aluminum and magnesium alloy panels that cannot be formed at room temperature due to insufficient formability. One of the manufacturing problems encountered during SPF is excessive thinning in the form of a localized neck; which can lead to fracture. Localized necking can be predicted with the use of continuum elements in finite element analysis (FEA); however, the use of these elements in simulating SPF of large automotive panels is computationally intensive and often computationally prohibitive due to convergence issues. This paper examines the use of a modified material model (developed by engineers at Livermore Software Technology Corporation (LSTC) that can be used with conventional Belytschko-Tsay shell elements. This model considers normal stresses during SPF, which is needed to predict necking locations. The paper reports the results on investigating means for improving computational efficiency with this new formulation (i.e. element size, mass scaling, and adaptive meshing) and compares the performance of the normal stress element formulation with that of Belytschko-Tsay shell element in simulating the SPF process. The findings indicate that the newly developed formulation can be used for predicting localized thinning under SPF conditions.     

YJ231接装机后墙板铸铁件浇注系统当冒口的补缩和溢流排渣设计

YJ231接装机后墙板铸铁件,材质HT200,轮廓尺寸1102mm×962mm×34mm,重200kg,干砂型,表面质量要求高,6个面均需机加工。为获得无夹渣、夹砂、缩松、气孔等缺陷铸件,采用均衡凝固浇注系统当冒口,浇注和补缩一体化设计方法:1只直浇道φ40mm,双向横浇道截面梯形32mm×44mm×50mm,4只内浇道80mm×7mm搭接在铸件顶面,设2只溢流排渣冒口φ50mm×60mm,8只出气冒口φ20mm。墙板实际浇注时间28s,与计算值吻合。生产实践证明,运用均衡凝固浇注系统当冒口浇注、补缩和溢流排渣工艺稳定可靠。