网络通信技术的发展和趋势分析

【摘要】针对网络通信技术的发展和趋势分析的方向,介绍了网络通信技术的发展现状,其中有网络通信技术、无线网络通信新技术和网络通信技术与3G技术的发展,探讨了网络通信技术的发展趋势,主要是移动通信技术的发展趋势和卫星通信技术的发展,展望了网络通信技术在小康社会的建设中的发展趋势。     

高性能PAN基碳纤维国产化进展及发展趋势

总结归纳了国际PAN基碳纤维发展历史,对我国四十余年碳纤维发展历程进行了分析解读.研究表明,随着20世纪末以二甲基亚砜为溶剂的丙烯腈间歇溶液聚合、湿法纺丝制备碳纤维原丝关键技术的突破,确立了高性能PAN碳纤维国产化发展正确的技术方向,实现了国产高性能碳纤维制备技术的转型升级,奠定了十余年来碳纤维国产化高速发展的技术基础,支撑了碳纤维高性能化系列产品与技术的持续研发,由此形成了以二甲基亚砜原丝技术为主体、硫氰酸钠和二甲基乙酰胺等技术共同发展的国产碳纤维技术体系,建立起国产碳纤维产学研相结合的发展格局.详细阐述了国产碳纤维技术与产业化发展现状,分析了国产化技术与产业存在的问题,对国产高性能PAN碳纤维技术研发与产品体系建设发展提出了几点建议.     

建筑电气的技术与发展分析

随着建筑电气技术和建筑技术的发展,尤其是随着信息技术的发展,如计算机技术、控制技术、数字技术、显示技术、网络技术以及现代通信技术的发展,使建筑电气技术实现了飞跃性的发展。自从改革开放以来,国际上许多先进的新产品、新技术不断进入中国,使建筑电气行业得到了进一步的发展。     

谈无线通信技术特点及发展趋势

随着科学技术的发展,无线通信技术得到了迅速发展,但无线通信技术在发展的过程中也出现了一系列的问题,遇到了很多技术上的阻碍,目前我国正逐渐进入3G时代,无线通信技术在我国得到了快速的发展。本文分析了无线通信技术的各自特点,并对无线通信技术发展趋势做以探讨。     

基于自动化控制的电子测量技术发展

自动化控制技术的不断发展对电子测量技术的应用提出了更高的要求,为了能够更好地了解电子测量技术,本文展开了研究,首先分析了基于自动化控制的电子测量技术的发展概况,在此基础上,分析了基于自动化控制的电子测量技术发展的重要性,并对加强基于自动化控制电子测量技术的发展提出相关策略和措施,希望对电子测量技术发展有所启发。     

对我国工业自动化中无线技术的研究

无线技术起源于通信领域，但随着电子技术的发展，无线技术在工业自动化领域得到了发展和应用。无线技术的独特优势让它为工业发展开创了新的领域，为工业现代化发展提供了新的动力。本文对无线技术进行了梳理，对Zigbee和超宽带技术进行了分析，并对未来的无线技术和工业自动化结合作出了展望。     

人机工程学中界面技术的发展分析

随着现代科技的发展，人机工程学中的界面技术也在不断发展。界面技术大致经历了三个阶段：人—机界面技术，用户界面技术和组织—机器界面技术。章介绍了每个阶段的界面技术的情况及其特点，并分析了目前我国界面技术的发展状况。     

工业自动化节能减排技术领域及方向研究

工业自动化节能减排技术的发展方向必然会向着信息自动化方向、制造和材料自动化方向、高效能自动化技术、新能源自动化技术领域发展，逐步成为工业发展的重点内容和重要发展目标。本文分析了工业自动化节能减排技术的重要性，提出了工业自动化节能减排技术的发展方向，就工业自动化在节能减排技术领域的应用作出了新的探索。     

浅论测量技术的发展

本文主要从工程测量技术的历史发展动态入手，简要地阐述了工程测量技术中的仪器设备的更新换代、精密测量技术的产生和发展、数字化测图技术的产生和发展，同时结合目前的测量技术发展状况对在新形式新环境下的工程测量技术发展所面临的和挑战和机遇提出了建议。     

电力系统继电保护技术的发展方向

我国电力系统继电保护技术的发展经历了4个阶段。随着电力系统的高速发展和计算机技术、通信技术的进步,继电保护技术面临着进一步发展的趋势。其发展将出现原理突破和应用革命,由数字时代跨入信息化时代,发展到一个新的水平。本文展望了未来继电保护技术的发展方向和前景。     

Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol

Abstract

Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to different solid-state characterizations. The powders were sieved and 90–360?µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35–180?MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slip planes were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar, but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid?>?PRA-HCL?≈?PRA-OXA?>?BPY?>?PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.     

Characteristics of carbon microspheres and study on its adsorption isotherms

In this paper a great deal of carbon microspheres with high purity, uniform diameter and good features were synthesized by CVD method, while acetylene and toluene were used as carbon sources. The obtained carbon microspheres were almost amorphous. The products were treated by microwave plasma and temperature vacuum heat treatments respectively, then the samples were analyzed and characterized by FESEM, XRD and HRTEM. The results showed that carbon microspheres were well graphitized while their features were undestroyed. Based on their adsorption isotherms of nitrogen, pore structures of carbon spheres were found to be changed greatly after graphitized treatments.     

圆柱形金属橡胶结构的静态力学性能

对圆柱形金属橡胶结构做静态实验,运用最小二乘法对实验数据进行拟合,得到金属橡胶材料本构方程的各系数,将由实验得到的各系数代入本构方程式中,从而得到理论拟合迟滞回线,将理论拟合迟滞回线与试验迟滞数据进行对比,发现理论拟合迟滞回线与试验迟滞数据吻合较好,同时运用ANSYS有限元软件对金属橡胶结构进行有限元建模、定义边界条件及施加载荷,最后进行应力应变分析,得到应力应变分布图,发现分析结果与实验结果吻合。     

Analytical simulation of rib-web forging

The friction calibration curves were generalized using ALPID simulations of ring compression tests and were used to establish the friction factor associated in the workpiece-tool interface. ALPID simulations were carried out for different rib-web sections. The metal flow characteristics were closely watched and load requirements for these processes were established. The distribution of effective strain and strain rate and stress were established.     

Testing of explosive welding and welded joints. Wavy character of the process and joint quality

The basic defects occuring in explosive clad plates were properly systemized and the reasons of their formation were explained. Cases of cracks and delaminations in explosive clad plates were examined in this work. Various values of tensile stresses coming from loading and unloading waves were analysed, as they were the main reason of defects. The defects were connected with properties of welded materials in the joint area and beyond it. Some practical aspects of this process were shown as well.     

偶联改性纳米HAP/HDPE挤出复合生物材料的力学性能和微观结构

通过化学共沉淀-水热合成法制备纳米级羟基磷灰石(HAP),再用自制模具制备出偶联剂改性纳米HAP/高密度聚乙烯(HDPE)挤出复合材料.通过SEM观察以及力学性能测试,研究了偶联剂改性纳米HAP/HDPE复合材料的微观结构和力学性能.结果表明: 添加硅烷偶联剂后,HAP/HDPE复合材料的力学性能获得提高,偶联剂含量为2%(质量分数)时拉伸强度最高.而当HAP含量为20%(质量分数)时,复合材料的拉伸强度和抗弯强度最高.添加了偶联剂,HAP微粒表面与HDPE有较好的亲和性,断裂过程中应力诱发的塑性变形增加,裸露的HAP颗粒明显减少.通过口模挤出可以使得聚乙烯分子链在应力作用下伸直取向,大量平行于长轴且紧密排列的微纤维形成.     

有缺陷和无缺陷量子点内应变分布的比较与分析

阐述了量子点内能级结构与应变的关系,用ANSYS7．1计算了有缺陷和无缺陷两种情况下：InAs／GaAs量子点的应变分布,通过对计算结果的比较,讨论了两种情况下不同的应变分布对量子点电子结构影响的不同结果,指出有缺陷时量子点各能级的改变量都与无缺陷时不同,无缺陷时应变的作用只是使能级平行移动;有缺陷时,缺陷将使量子点内能级结构复杂化,有缺陷时发光波长和发光光谱都比无缺陷时复杂。     

应用在食品行业中的冷封胶薄膜

概述了冷封胶薄膜的结构种类、制备工艺以及优点,接着陈述了冷封薄膜在软包装中的应用以及局限性,指出了实际生产中遇到的问题并对问题进行分析,提出改进方法.最后探讨了冷封薄膜未来的发展方向.     

Growth and study of some gel grown group II single crystals of iodate

Single crystals of calcium iodate and barium iodate were grown by simple gel technique by single diffusion method. The optimum conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of the reactants etc. Crystals having different morphologies and habits were obtained. Prismatic, dendritic crystals of barium iodate and prismatic, needle shaped, hopper crystals of calcium iodate were obtained. Some of them were transparent, some transluscent, and few others were opaque. Both the crystals were studied using XRD, FT-IR, and thermal analysis. The crystals were doped by iron impurity. The effect of doping was studied using IR spectroscopy and thermal analysis.     

Influence of Raw Material and Processes of Gelatins upon Photographic Characteristics of Dichromated Gelatin

Carbon tissues prepared using types of gelatin differing in raw material and process were sensitized by dichromate and their photographic characteristics were investigated. Sensitivity and gamma were dominantly determined by the higher molecular weight components of the gelatin, sharpness and resolving power were dominantly determined by viscosity; these properties were little affected by its origin.