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为适应新时期社会发展及企业对人才高素质的需求,基于创新能力的培养,本文对课程《塑料成型工艺与模具设计》从教材的选择与实践教学的优化、教学手段的改革、项目教学法的应用、考核制度的改革以及模具兴趣小组课外教学等方面进行了一系列的教学改革与研究。 相似文献
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一、塑料的工艺性能塑料的工艺性能与模具设计的关系十分密切,但有些工装设计人员往往忽视这个问题,因此所设计的模具造成塑件尺寸精度达不到要求,塑件产生气泡、缩孔、翘曲、裂纹等缺陷,有时塑件不能完全成型。 (一) 收缩率塑件从热的模具中取出并冷却到室温后,其尺寸发生变化的特性称为收缩性。收 相似文献
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近年来,塑料在电子工业中的应用范围日益扩大,以塑代钢、以塑代木的发展趋势越来越明显。尤其是塑料在收音机、录音机,电视机等电子产品及电风扇、洗衣机、电冰箱等轻工产品中的应用已占据相当重要的地位。模具是塑料成型的主要工艺装备,也是产品更新换代的重要生产手段为了提高塑料产品结构设计人员、塑压工艺人员、工装设计人员、模具制造工艺人员以及有关生产管理人员的生产技术水平,培养塑料模具设计与制造的业务能力,本刊将举办《塑料模具设计与制造》技术讲座,系统而扼要地介绍有关塑料、成型设备、模具设计,制造工艺等方面的基本知识、设计及制造方法。这个讲座共计七讲,将分十四期连载。 相似文献
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一、概述 (一)挤塑模的特点挤塑模是热固性塑料模塑成型的一种常用模具。这种模具设有单独位于模具上的外加料室,加料及成型前首先合模,然后将塑料加入外加料室内预热,并在压柱的作用下使熔融塑料通过加料室底部的注口和模具的浇注系统,以高速挤入闭合着的型腔,最后硬化成型。挤塑模的基本结构如图5—1所示,模具配有外加料室2及压柱1。开模时利用卸模架沿两个水平分型面分开,同时卸模架顶杆顶动推板使塑件脱出型芯5。 相似文献
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Cox R.V. Haskell B.G. LeCun Y. Shahraray B. Rabiner L. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1998,86(5):755-824
The challenge of multimedia processing is to provide services that seamlessly integrate text, sound, image, and video information and to do it in a way that preserves the ease of use and interactivity of conventional plain old telephone service (POTS) telephony. To achieve this goal, there are a number of technological problems that must be considered, including: compression and coding of multimedia signals, including algorithmic issues, standards issues, and transmission issues; synthesis and recognition of multimedia signals, including speech, images, handwriting, and text; organization, storage, and retrieval of multimedia signals, including the appropriate method and speed of delivery, resolution, and quality of service; access methods to the multimedia signal, including spoken natural language interfaces, agent interfaces, and media conversion tools; searching by text, speech, and image queries; browsing by accessing the text, by voice, or by indexed images. In each of these areas, a great deal of progress has been made in the past few years, driven in part by the relentless growth in multimedia personal computers and in part by the promise of broad-band access from the home and from wireless connections. Standards have also played a key role in driving new multimedia services, both on the POTS network and on the Internet. It is the purpose of this paper to review the status of the technology in each of the areas listed above and to illustrate current capabilities by describing several multimedia applications that have been implemented at AT&T Labs over the past several years 相似文献
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综合语义与颜色特征的图像检索技术研究 总被引:2,自引:2,他引:0
针对多媒体搜索引擎系统中的图像检索技术,本文提出了应用图像的高层语义特征和底层颜色特征作为图像检索的综合指标,将图像文本和视觉信息融合起来,给出了一种综合语义和颜色特征的图像检索系统的体系架构.以填补多媒体底层特征和高层语义之间的差异,并在此基础上提出了相关算法,使图像检索能够满足用户的需求.提高图像检索的效率和精度。 相似文献
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基于图像修复的图像编码技术 总被引:2,自引:2,他引:0
数字图像修复技术是图像恢复领域的一个重要分支,它的目的是根据图像现有的信息来自动恢复丢失的信息,它可以用于旧照片中丢失信息的恢复、视频文字去除以及视频错误隐藏等。结合数字修复技术的图像压缩编码技术是基于对象的第二代图像编码中的研究热点之一。这里首先介绍了图像修复技术的概念,然后分类说明了几种常见的修复技术,在此基础上,得到了基于图像修复的压缩编码技术的基本处理流程,最后以具体算法为例说明了基于图像修复的压缩编码技术的压缩过程。 相似文献
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The mold array process plastic ball grid array continues to demonstrate progress as a cost-effective, medium to high performance electronics package. Highly manufacturable and reliable solutions to the challenges of molding up to several hundred packages at one time as well as subsequent singulation of the packages have been found. JEDEC moisture performance at up to Level 1 with 220°C reflow temperatures has been qualified for production. Thermal performance remains critically dependent on die size, package size, and motherboard construction. 相似文献
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杨志义 《微电子学与计算机》1998,15(6):24-26
本文首先介绍了传输视频、音频、图象、图形、文本、动画等媒体信息对网络的要求。然后讨论了ATM中分组交换、面向连接技术以及ATM对多媒体通信的支持,充分证实ATM传输网络技术是目前多媒体通信中最理想的网络技术。 相似文献
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H. Blume H.-M. Blüthgen C. Henning P. Osterloh T.G. Noll 《The Journal of VLSI Signal Processing》2002,31(2):117-126
The computational power required in many multimedia applications is well beyond the capabilities of today's multimedia systems. Therefore, the embedding of additional high-performance accelerator multimedia components into these systems is most decisive. This paper presents the embedding of multimedia components into computer systems using reconfigurable coprocessor boards. The goal of those reconfigurable platforms which can be adapted to several applications and which include programmable digital signal processors, control and memory devices as well as dedicated multimedia ASICs is worked out. On the way to such a platform four ASICs for image and text processing are presented. The embedding of these components into a computing system using a CardBus-based coprocessor board is shown. Such a reconfigurable coprocessor board is an important intermediate stage on the way to future hybrid reconfigurable systems on chip. 相似文献
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扇出型封装在塑封过程中会出现芯片偏移及翘曲等缺陷,详细了解环氧塑封材料(EMC)的特性能够准确预测封装材料、结构、塑封工艺对塑封效果的影响。针对用于扇出型封装的EMC材料采用动态机械分析仪、差示扫描量热仪、流变仪测试其动态力学性能、固化动力学性能、流变学性能和热容,并建立可用于有限元分析的材料特性数学模型。结果表明,EMC在150℃等温固化60 min后具有最少残余固化;100℃环境下黏度随温度增加速率最快;时温等效原理可预测实验频率以外的力学行为。模型曲线与实验数据的拟合优度均大于0.982,材料表征模型满足准确性与适用性的要求。 相似文献