甜菜专用肥配制与施肥效果的研究

简要介绍了甜菜专用复合肥的主要组成、田间小区试验结果和生产对比试验结果,从营养生理作用等方面分析了甜菜专用复合肥增产增糖的原因,并对该肥的经济效益进行了具体的核算。     

Stress intensity factors for semi-elliptical surface cracks in plates and cylindrical pressure vessels using the hybrid boundary element method

At first, a hybrid boundary element method used for three-dimensional linear elastic fracture analysis is established on the basis of the first and the second kind of boundary integral equations. Then the concerned basic theories and numerical approaches including the discretization of boundary integral equations, the divisions of different boundary elements, and the procedures for the calculations of singular and hypersingular integrals are presented in detail. Finally, the stress intensity factors of surface cracks in finite thickness plates and cylindrical pressure vessels are computed by the proposed method. The numerical results show that the hybrid boundary element method has very high accuracy for the analysis of surface crack.     

Preparation and optimization of a low cost,high breakage resistance ceramic proppant special for the coal-bed methane

A kind of low cost, high breakage resistance ceramic proppant special for exploitation of the coal-bed methane is successfully produced. The producing conditions are optimized through orthogonal experimental design method. The breakage resistance results of the orthogonal analyses show the best condition of this kind of ceramic proppant is A₄B₃C₃D₂, which means sintering temperature of 1350 °C, manganese mineral powder content of 5 wt.%, weight ratio of 75/25 (second grade bauxite to mujie clay), and holding time of 3 h. The ceramic proppants under this very condition of A₄B₃C₃D₂ are then prepared and their phase structure and microstructure are characterized subsequently. X-ray diffraction pattern exhibits that mullite and corundum are the main crystallographic phases. Scanning electron microscopy illustrates the A₄B₃C₃D₂ sample is with non-porous morphology and small amount of corundum grains and liquid phase, which play the role of improving strength. It reveals the orthogonal experimental design is a feasible optimization method and the ceramic proppant made under the condition of A₄B₃C₃D₂ is a promising material for exploiting the coal-bed methane resources.     

新颖在线痕量钠离子分析仪的研制

作者研制的在线痕量钠离子分析仪,根据能斯特响应的原理,以新颖的化学分析流路系统为核心技术,摒弃了传统技术形成的连续流动和手工标定的工作方式,借助于单片机技术,实现了间歇式静态测量和全自动标定的方式.经现场运行考核证明,该仪器工作可靠,具有自动化程度高、维护量小、运行成本低等特点,具有广阔的应用前景.     

PLC控制简单显示电路的设计与应用

介绍一种在PLC控制系统中简单数字显示电路的设计方法,成功应用于交通灯模拟现场的PLC控制系统中进行时问显示。     

激光二极管群并联驱动电源的研制

介绍一种单片机控制的激光二极管群并联驱动电源，系统包括可调恒流源、过流保护电路、光功率采样与放大电路等部分，结合硬件及软件，实现了激光二极管群的可靠保护与光功率的稳定、准确输出，并且使这若干个激光管互不影响。     

YF40MnV钢制造磨床主关件的应用分析

本企业是磨床制造专业厂家，多年来生产的各种磨床其钢制主关件主要有主轴、丝杆、齿轮等几大类。它们在机床中分别起着极其重要的作用，根据它们的工作特性和工作环境，零件材料多选用中碳结构钢或中碳合金钢，热处理大都以高频感应表面加热及淬火，来达到最终所需要的硬度和强度等性能。因此热处理后的应力变化、变形情况和精度保证直接决定了主关件的质量，并有赖于原材料品质和预处理方法得当。     

The noise reduction of a DC motor using multi-body dynamics

The DC motor of a vehicle may cause noise and vibration due to high-speed revolution, which can make a driver feel uncomfortable There have been various studies attempting to solve these problems, mostly focusing on the causes of noise and vibration and a means of preventing them The CAE methodology is more efficient than a real test for the purpose of looking for various design parameters to reduce the noise and vibration of the DC motor In this study, a design process for reducing brush noise is presented with the use of a computer model, which is made by using a multi-body dynamics program (DADS) The design parameters to reduce the brush noise and vibration were proposed using a computer model They were used to reduce the noise and vibration of the DC motor and verified by the test tesults of the fan DC motor in the vehicle This method may be applicable to various DC motors     

燃气锅炉房烟囱保温对排烟性能的影响分析

根据北京市某燃气锅炉房的实际情况,对烟囱保温状况与排烟性能的关系进行了计算分析,结果表明:减小保温层厚度会使烟囱的排烟性能下降,尤其在保温层厚度较小时,这种影响更大。对于所研究对象,在设计排烟量的情况下,当烟囱保温层厚度小于15mm时,排烟系统的抽力计算值小于阻力计算值。当保温层厚度增加到20mm以后,对改善排烟性能的作用较小。