矩形截面深梁的一个新理论及其应用

综合考虑梁截面转动、相邻截面剪切变形和横向压力等影响推导出弯曲矩形截面深梁的新理论。作为算例,应用虚拟功的互等法具体求解了在均布载荷作用下两端简支深梁的弯曲问题,给出了这种情况的数值计算结果,与ANSYS有限元结果进行了对照,验证了该新理论的正确性。     

Carburization of ferrochromium metals in chromium ore fines containing coal during voluminal reduction by microwave heating

Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O):n(C) (molar ratio) as 1.00:0.84 and n(SiO₂):n(CaO) as 1.00:0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0–10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio. Foundation item: Project(50474083) supported by the National Natural Science Foundation of China; Project supported by the Baoshan Iron & Steel Co. Ltd. of China     

中药丸微波干燥灭菌机原理设计

主要对中药丸微波烘干灭菌系统的工作原理进行了设计．论文给出了采用微波进行中药丸干燥灭菌的优点．系统主要由微波加热设备、物料输送系统、控制与检测系统、排湿系统等部分组成．详细介绍了微波对中药丸进行干燥灭菌的工作流程．     

二维和三维Gauss随机粗糙面的Monte Carlo仿真

通过二维Gauss随机粗糙面的相关函数及其表面谱密度函数,应用Monte Carlo方法,建立了二维Gauss随机粗糙面模型,并采用均方根高度和相关长度对随机粗糙表面的高度起伏影响进行了特性分析,将二维的推导方法扩展到三维,建丑了三维Gauss随机粗糙面模型。     

微波辐射提取桔皮中橙皮苷的研究

以乙醇溶液为提取溶剂,采用微波辐射提取桔皮中的橙皮苷,考察了溶剂浓度、微波功率、微波辐射时间、液料比等因素对橙皮苷提取量的影响.正交试验优化显示：溶剂体积浓度55%、微波提取功率400 W、辐射时间70 s和液料之比15∶1（质量比）时,橙皮苷的提取率为41.05%,比无微波辐射提取提高了14.21%.     

电路板雕刻机的运动控制系统设计

介绍了电路板雕刻机的运动控制系统的特点和规律,系统以3关节直角坐标型机器人为外部结构,基于Visval C＋＋的操做环境,控制核心采用DSP,同时与上位PC机通讯进行控制．对电路板雕刻机中的步进电机实现电气控制,以完成电路板的雕刻过程．     

水平矩形管内气液两相流界面波特性

<正>气液两相流中界面波的存在对传热、传质、阻力特性及稳定性都有很大影响。前人有关界面波的研究大多偏重于两相流中界面波的类型及其转变,而对其特征参数变化规律(如振幅、波长、频率和速度等)的研究则很少。但界面波对气液两相流流动阻力和流动结构影响机理的深入研究必须以了解界面波的各特性参数为前提,同时界面波有关特性参数的深入研究也可为气液两相流的数学理论化提供实验基础。 本文以气、水为工质,系统研究了水平矩形管内气液两相流的界面波特性。根据界面波在时域、幅域内的不同特征区别出了各种类型的波并给出了相应的波形和流型图。着重研究了界面波各特征量随气液两相流量变化的变化规律。     

多孔介质微波加热厚度的确定

简述了微波加热的机理，以湿木材为研究对象，通过理论计算确定了微波在木材中的穿透深度。计算表明：随着木材含水率和微波工作频率的增加，微波在木材中的穿透深度减小；当用频率为915MHz和2450MHz的微波加热或干燥具有高含水率的多孔介质时，多孔介质的最大厚度应分别控制在16cm和6cm以内。     

A free space frequency‐time‐domain technique for electromagnetic characterization of materials using reflection‐based measurement

In this report, a free space frequency‐time‐domain technique is presented for characterizing the electrical properties and thickness of the sample using multiple reflections and fabry‐perot resonance phenomenon. The retrieval of constitutive electromagnetic parameters of the sample has been carried out by comparing the measured reflection coefficient data from the sample at two different incident angles. The relative permittivity as well as relative permeability along with the thickness of different samples viz., beryllia, silicon, and plexiglass have been evaluated with high accuracy in the frequency range 1 to 15 GHz. The method is also experimentally validated by successfully reconstructing the unknown material properties of two different samples. The unique advantage of this method lies in non‐requirement of any prior knowledge of the sample's thickness for measuring the complex relative dielectric constant as well as relative permeability of the sample. To determine the electromagnetic properties of the sample, the sole knowledge of reflection coefficient data are needed. Moreover, the method does not involve any additional measurement for the reference calibration. The simple, cost‐effective proposed scheme is quite useful in many applications like accurate determination of signal strength in indoor wireless communication, through wall imaging, food industry, and so on.     

矩形断面明渠中恒定均匀流的机械能损失

明渠流中机械能损失的确定是水力学乃至工程流体力学中的重要内容.以构建的明渠恒定流新的总流能量方程及矩形断面明渠三维层流运动的理论解为基础,通过理论分析与三维数值计算,就矩形断面明渠中恒定均匀流的机械能损失系数随雷诺数及宽深比的变化进行了深化研究,得到如下成果:1)在层流条件下,机械能损失系数一般均与雷诺数和宽深比有关,只有对宽深比大于6.5的宽浅明渠,其相应流动的机械能损失系数才仅与雷诺数有关,且在雷诺数相同的条件下,一般矩形断面明渠流的机械能损失系数要大于宽浅明渠流的机械能损失系数;2)在紊流条件下,机械能损失系数也一般均随雷诺数与宽深比而变,但对给定的宽深比,存在相应的特征雷诺数,当流动的实际雷诺数大于该特征雷诺数后,机械能损失系数则不再随宽深比而变化,且在宽深比一定的条件下,雷诺数越小,其机械能损失系数的修正值越大.