圆环面上纤维轨迹的计算机辅助设计

曲面上的曲线造型是计算机图形领域的一个新的研究热点,而且它们在纤维织物编织,三维服装裁剪以及复合材料的纤维缠绕轨迹设计等领域有十分广泛的应用,为了解决圆环面上纤维轨迹的计算机辅助设计问题,研究了圆环面上测地线的解析解以及拟测地线数值求解的具体算法并给出了其表达式,测地线是曲面上两点之间最短距离的曲线段,在一般曲面上没有解析解,但是在圆环面上却可求出其精确的解析解,但在曲面的边沿部分,测地线因不能实现自然的折返过渡,于是拟测地线就被引进到曲面上的曲线造型设计之中,在拟测地线分析研究基础上,给出了圆环面上拟测地线的方程及数值解法,通过其在一个实例中的应用结果证明,该方法可获得织物的纺织条纹以及缠绕物体的纤维轨迹。     

基于网络型中央控制器的多媒体教室远程管理

网络中控系统通过人性化的人机界面、开放式的可编程控制平台、交互式的控制结构,实现了设备的互连操作和集中控制,它集成了电源管理、视音频切换矩阵、红外遥控、VGA切换矩阵、全数码声音控制、可编程串行通讯、设备IP网络连接等功能,应用到多媒体教学中,不仅有效解决了对设备的管理与信息的切换,也使实现多媒体教室的远程管理成为可能。该文以创捷HT1800中控系统为例,就实现这一技术的原理和方法进行了阐述,便于大家更好地对网络中控系统有一个全面的认识。     

Mixture of KL subspaces for relevance feedback

Relevance feedback has recently emerged as a solution to the problem of improving the retrieval performance of an image retrieval system based on low-level information such as color, texture and shape features. Most of the relevance feedback approaches limit the utilization of the user’s feedback to a single search session, performing a short-term learning. In this paper we present a novel approach for short and long term learning, based on the definition of an adaptive similarity metric and of a high level representation of the images. For short-term learning, the relevant and non-relevant information given by the user during the feedback process is employed to create a positive and a negative subspace of the feature space. For long-term learning, the feedback history of all the users is exploited to create and update a representation of the images which is adopted for improving retrieval performance and progressively reducing the semantic gap between low-level features and high-level semantic concepts. The experimental results prove that the proposed method outperforms many other state of art methods in the short-term learning, and demonstrate the efficacy of the representation adopted for the long-term learning.

西门子S7系列PLC在成都地铁BAS系统中的应用

本系统以西门子S7-414H冗余控制器为主站,多台S7—200PLC和S7—300PLC为从站,通过光纤链路模块OLM组成冗余光纤环网,实现地铁设备监控系统的完美控制。文章重点介绍了控制工艺背景、主／从网络组成构架、硬件配置及软件编程．要点、系统中包含的PROFIBUS-DP、MODBUS、网络读写等通讯协议出现的问题及解决方法、调试后达到的效果及应用体会。     

操作参数对玻纤毡增强复合材料流动成型的影响

研究了玻纤毡增强热塑性复合材料(GMT)流动成型过程中模腔压力和材料流动方向对制品力学性能和纤维取向的影响。研究表明：随着压力提高，弯曲强度和模量同步增加；但压力超过18MPa后，性能变化不明显。随布料面积分数减小，单轴拉伸流动成型将导致沿流动方向和垂直流动方向强度及模量差异变大，纤维取向严重；但双轴拉伸流动成型得到的制品各方向性能较均匀，基本呈现各向同性。     

FORCES AND TEMPERATURES IN HARD TURNING

In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer).     

小洼槽长距离倒虹吸水头损失的数值计算

为了探索采用Fluent软件模拟研究长距离倒虹吸水头损失的准确性,利用计算流体力学软件Fluent的水气两相流VOF法,采用三维标准k-ε模型对长距离倒虹吸水头损失进行模拟计算。计算中考虑壁面粗糙程度,设置不同的粗糙度模拟小洼槽倒虹吸水头损失,从而得到玻璃钢管材粗糙度范围。对比较大流量下水头损失的模拟值与实测值,表明通过设置粗糙度模拟长距离倒虹吸水头损失的方法可行,但网格划分对结果的影响大小还需进一步研究。     

加捻对热致液晶聚芳酯初生纤维拉伸性能的影响

热致液晶聚芳酯（TLCP）的特殊化学结构使其具有高强度、高模量、低粘度、易加工等诸多优良特性,且TLCP纤维力学性能对其应用于纺织业具有举足轻重的作用。本论文主要研究加捻对TLCP纤维力学性能的影响,探究其影响机理。研究结果表明：加捻对其力学性能影响很大,TLCP纤维束的强力随着捻度的增加呈先增大后减小趋势。当TLCP纤维束的线密度为52.50 tex,捻度为130Tm时,最大强度为9.14 cN/dtex。未加捻TLCP单纤维的线密度为1.394 tex时,最大强度为11.3cN/dtex。     

长螺旋搅拌止水帷幕咬合桩及其施工工艺应用实例分析

介绍了一种新型的水泥土搅拌桩成桩方法及其应用,包括测量放线定位、长螺旋钻机就位、长螺旋钻机引孔,以确定桩准确位置,松动硬土层,并排除地下障碍物,然后利用长螺旋搅拌机具边钻进边泵送浆液搅拌至设计孔底标高,重复搅拌和喷浆成桩;在完成搅拌桩施工后,利用长螺旋钻具切割该搅拌桩成孔,压灌混凝土后插入钢筋笼施工护坡桩,形成整体帷幕,达到止水与支护合二为一的效果。     

基于RFID技术电子封条的设计与实现

针对物流监管等行业对于高速运输安全性和高信息化程度的需求,设计了一种新的电子封条产品,通过将RFID技术、红外传感器技术、光纤传感器技术等手段有效配合及联动的方法,杜绝了绝大部分入侵箱体检测的情况,极大地提高了集装箱的安全性,并通过更换了高损耗元件和调整改变电子封条射频信号收发的工作方式,使系统的功耗得到了很大的改善,对提高全球集装箱供应链的效率和效益具有重要意义。