数控短电弧机床运动控制器硬件设计与实现

从设计一个用来进行机理研究的短电弧机床数控系统角度出发,研制开发了基于高性能DSP芯片的数控系统运动控制器,用于位置进给控制和加工电参数设定与检测,并结合USB通讯技术实现了运动控制器核心处理DSP芯片与USB接口的数据传输,为短电弧机床机理研究和其他关键技术研究打下良好的基础.     

浅析水利工程项目成本管理中存在的问题与对策分析

成本管理对水利施工单位的未来和发展都非常重要,成本管理水平的提高,对于提高水利工程项目管理,实现持续、快速、健康发展有着非常巨大的作用。     

利用土壤传递函数估算土壤水力学特性研究进展

Characterization of soil hydraulic properties is important to environment management; however, it is well recognized that it is laborious, time-consuming and expensive to directly measure soil hydraulic properties. This paper reviews the development of pedotransfer functions (PTFs) used as an alternative tool to estimate soil hydraulic properties during the last two decades. Modern soil survey techniques like satellite imagery/remote sensing has been used in developing PTFs. Compared to mechanistic approaches, empirical relationships between physical properties and hydraulic properties have received wide preference for predicting soil hydraulic properties. Many PTFs based on different parametric functions can be found in the literature. A number of researchers have pursued a universal function that can describe water retention characteristics of all types of soils, but no single function can be termed generic though van Genuchten (VG) function has been the most widely adopted. Most of the reported parametric PTFs focus on estimation of VG parameters to obtain water retention curve (WRC). A number of physical, morphological and chemical properties have been used as predictor variables in PTFs. Conventionally, regression algorithms/techniques (statistical/neural regression) have been used for calibrating PTFs. However, there are reports of utilizing data mining techniques, e.g., pattern recognition and genetic algorithm. It is inferred that it is critical to refine the data used for calibration to improve the accuracy and reliability of the PTFs. Many statistical indices, including root mean square error (RMSE), index of agreement (d), maximum absolute error (ME), mean absolute error (MAE), coefficient of determination (r²) and correlation coefficient (r), have been used by different researchers to evaluate and validate PTFs. It is argued that being location specific, research interest in PTFs will continue till generic PTFs are developed and validated. In future studies, improved methods will be required to extract information from the existing database.     

切削刀具几何角度计算与测量方法的研究

 介绍了坐标变换法、三棱柱模型法和矢量法等3种计算和测量切削刀具几何角度的方法,并与利用虚拟技术建立三维参数模型来确定刀具几何角度的方法进行分析比较,结果表明利用虚拟设计技术将是今后最快确定刀具几何角度的主要方法之一。     

关于大功率拖拉机合理配套农具的几点建议

大功率拖拉机及配套农具的应用大大提高了农机作业质量水平、劳动生产率和农业生产的经济效益,但大功率拖拉机在合理配套农具方面还存在不少突出问题,影响了大功率拖拉机功效的充分发挥。本文结合新疆生产建设兵团基层团场生产实际的使用经验,就大功率拖拉机合理配套农具提出几点建议。     

香蕉生产全程机械化探讨

分析我国香蕉生产的机械化现状．探讨我国需要解决的香蕉生产机械化技术问题。针对我国香蕉生产的种植模式和劳动力状况．提出我国香蕉生产应尽快研发的机具。     

硬质合金刀具干式切削淬硬钢的切削性能试验研究

在数控车床上进行了干式硬态切削淬硬钢,优选刀具材料和切削条件,研究了切削性能和刀具磨损情况。研究表明:采用添加少量的TaC新型硬质合金材料刀具,能阻止WC晶粒在烧结过程中的长大,是合理的刀具材料;改善表面粗糙度应重点从进给量考虑和切削深度考虑,切削速度的影响是比较小;刀具的磨损形态主要特征为月牙洼磨损,刀具的破损主要形式为刀片表层剥落、切削刃的微崩刃。     

数控机床车削加工中的刀具选择

在实际数控机床加工过程中,所采用的车削刀具的类型将直接的关系到机床车削加工的加工水平。针对这样的情况,文章将具体的进行对数控机床加工过程进行分析探讨,并对数控机床车削加工过程中所有各方面因素进行分析探讨研究,力求选择出合适的数控机床车削加工刀具,促进数控机床车削加工生产效率的提升。     

PDCA循环对优化饲料企业供应链的研究探讨

我国饲料产量保持高度增长,已连续九年稳居世界第一,饲料企业也从无到有、从弱到强并以供应链的形式逐渐发展起来.近年来,饲料企业供应链在组织管理、信息共享、物流成本等方面依然存在问题,在一定程度上影响饲料企业供应链的整体绩效.PDCA循环是一种具有普遍适用性、反复优化和持续改进特点的质量管理方法,本研究尝试将PDCA循环原...     

提高数控机床精度方法

我国很多单位从国外引进了很多中高档数控机床,有的服役期满,有的不能正常工作,处于闲置,造成巨大资源浪费.文章基于此在论述了数控机床改造特点的基础上对于常见的提高数控机床改造精度的措施进行了较详细的阐述.