计算机专业硬件实验自动评测系统设计与实现[1]

计算机专业硬件实验的自动测试与评分是一项对降低教师工作负担大有裨益且十分有挑战性的工作,借鉴黑盒测试的原理,采用待测部件接口规格化,测试用例标准化,测试过程自动化的方式,设计了基于Logisim平台的硬件虚拟仿真实验自动评测系统,大大提升了硬件实验测试与评价的准确性、科学性、高效性,可为学生提供更精细的指导和反馈,有效提高了学生实验效率,极大的降低了教师的工作强度。     

大数据下人工智能在通信技术网络中的应用

随着科学技术的发展,网络已经逐渐普及,各行各业的发展都离不开网络的应用。大数据已经逐步发展成为网络信息传输的重要手段,为了保证大数据下通信网络的有效运行,需要不断重视计算机技术的应用发展。文章首先阐述了大数据特点及人工智能的技术问题,然后研究了大数据时代下通信技术网络人工智能的应用,最后提出了人工智能在通信技术网络中发展的主要技术,以此来满足信息网络时代的实际需求。     

QFN器件焊接缺陷分析与工艺优化

QFN器件具有良好的电气性能,但器件回流焊接过程中极易产生底部热沉焊盘焊接空洞、器件引脚间锡珠、桥连等缺陷,当一个印制板焊接多个QFN器件时,缺陷发生率颇高。在高可靠性要求的航天产品焊接过程中,器件返修次数有限制,且返修会造成器件性能下降、组件可靠性降低等问题,因此亟需对QFN器件一次装配良率和焊接效果进行提升优化。为此,从原理上分析QFN器件热沉焊盘焊接空洞、器件引脚间锡珠缺陷产生机理,并从产品焊盘工艺性设计、钢网模板设计、焊接温度曲线设计等方面开展分析与优化。优化后,QFN器件一次装配良率提高,没有产生锡珠、虚焊等缺陷。     

Variable rate vector quantization for medical image compression

Three techniques for variable-rate vector quantizer design are applied to medical images. The first two are extensions of an algorithm for optimal pruning in tree-structured classification and regression due to Breiman et al. The code design algorithms find subtrees of a given tree-structured vector quantizer (TSVQ), each one optimal in that it has the lowest average distortion of all subtrees of the TSVQ with the same or lesser average rate. Since the resulting subtrees have variable depth, natural variable-rate coders result. The third technique is a joint optimization of a vector quantizer and a noiseless variable-rate code. This technique is relatively complex but it has the potential to yield the highest performance of all three techniques.     

Rearrangement of a mesylate tropane intermediate in nucleophilic substitution reactions. Synthesis of aza-bicyclo[3.2.1]octane and aza-bicyclo[3.2.2]nonane ethers,imides, and amines

Nucleophilic substitution of 2beta-mesyloxymethyl-N-methyl-3beta-p-tolyl-tropane intermediate with alkoxides, metal imides, or amines was found to lead not only to the expected bicyclo[3.2.1]octane (tropane) ether, imide, and amine derivatives but also to unexpected bicyclo[3.2.2]nonane derivatives. When alkoxides were used as nucleophile, only the rearranged bicyclo[3.2.2]nonane structure was obtained, whereas the use of amines or imides as nucleophile afforded a mixture of the two structures. The bicyclo[3.2.2]nonane structure was assigned by NMR analysis.     

A sunscreen-tanning compromise: 3D visualization of the actions of titanium dioxide particles and dihydroxyacetone on human epiderm

The self-tanning agent dihydroxyacetone (DHA) was applied to human skin samples, and its effect on light absorption was followed in time to study the DHA influence inside the different layers of skin. Application of DHA shows increased light absorption in the visible light region, as evidenced by skin tanning. The tanning effect is enhanced by UV irradiation and appears localized in the near-stratum corneum layer as revealed by depth analysis of the time signal. As a reference, application of an emulsion containing titanium dioxide particles shows clear surface stability and a screening of light penetration beyond the stratum corneum.