数控机床的故障诊断

针对数控机床的故障特点，主要介绍了数控机床机械类故障和电气类故障的诊断程序和诊断方法。     

A botanical importance rating system for estuaries

In many semi-arid areas, estuaries are threatened because of freshwater impoundment. Estuaries are important sites for ecological diversity and, increasingly, for recreation. A system has been developed which rates estuaries according to their botanical importance. A formula allows a single numerical importance score to be calculated. The area cover of each estuarine plant community type (i.e. intertidal salt marsh, submerged macrophytes, reed/sedge swamps and supratidal salt marsh) and its importance in the estuary forms the basis of the score. The ‘ecological condition’ of the plant community and the community richness within the estuary are incorporated into the formula. The formula is effective in determining the botanical importance of estuaries. Further methods to determine the zoological, physical and socio-economic importance of estuaries need to be developed to allow the overall importance of estuaries to be determined.     

确定滤袋室内喇叭安装个数和位置的新方法

初步建立 了滤袋 室内声压 分布 的数 学 模型 ，并 利用 实 测结 果对 此 数学 模型 进 行了 检验 ，证明所建 立的模 型是合理 的。可以 利用此模 型计算 滤袋室内 的声 压分 布，并 确定 喇叭 的安 装个 数和安装位 置     

Familial orofaciodigital syndrome type I revealed by ultrasound prenatal diagnosis of porencephaly

Porencephaly is a rare central nervous system (CNS) abnormality that can be caused by an intraparenchymal destructive process or a developmental defect. Here we report on a prenatal ultrasound diagnosis of complex CNS abnormalities including agenesis of the corpus callosum, agenesis of the cerebellar vermis, bilateral hydrocephaly, and bilateral porencephaly in fetus at 33 weeks' gestation. The diagnosis of familial orofaciodigital syndrome type I (OFD I) was raised after fetal autopsy, clinical examination of the family, and the X-linked dominant inheritance pattern. This is the fourth report of porencephaly in association with OFD I. We discuss the difficulties in genetic counselling since OFD I shows variable expressivity of the phenotypic features. Furthermore, we emphasize the importance of a detailed ultrasound examination after a prenatal diagnosis of porencephaly. Copyright © 2001 John Wiley & Sons, Ltd.     

腈纶装置烘燥机自燃的原因及预防措施

分析了上海石化腈纶事业部金阳装置二步法纺丝后处理使用的第二烘燥机在高温高热状态下运行,设备内部经常发生自燃现象的原因和预防措施。     

某活塞式航空发动机汽缸断裂分析

分析了某活塞式航空发动机汽缸缸体断裂的原因。宏观和微观观察表明,缸体的断裂性质为疲劳断裂,疲劳起源于缸体与缸头连接螺纹的起始处,晶间腐蚀是导致疲劳断裂的直接原因。能谱分析表明疲劳源区的腐蚀元素是氧,属于大气腐蚀。分析认为腐蚀发生于发动机长期存放过程中。     

羧酸及其衍生物急性毒性的QSAR研究

基于定量结构-活性相关性(QSAR)原理,研究了27种羧酸及其衍生化合物结构与其急性毒性LC50之间的内在定量关系。应用遗传算法从大量结构参数中优化筛选出与LC50最为密切相关的五个参数作为分子描述符,得出影响羧酸及其衍生物急性毒性的主要结构特征为分子的大小及其空间效应等。分别采用支持向量机(SVM)方法和多元线性回归(MLR)方法建立了相应的QSAR预测模型,并对所建模型分别进行了内部验证和外部验证。结果表明,两种模型均具有较高的稳定性、预测能力及泛化性能。其中,支持向量机模型对训练集和预测集样本的预测平均绝对误差分别为0.149和0.211,优于多元线性回归方法所得结果。     

Response of runoff and soil loss to reforestation and rainfall type in red soil region of southern China

To evaluate the long-term effects of reforestation types on soil erosion on degraded land, vegetation and soil properties under conventional sloping farmland (CSF) and three different reforestation types including a Pinus massoniana secondary forest (PSF), an Eucommia ulmoides artificial economic forest (EEF) and a natural succession type forest (NST), were investigated at runoff plot scale over a six-year period in a red soil region of southern China. One hundred and thirty erosive rainfall events generating runoff in plots were grouped into four rainfall types by means of K-mean clustering method. Erosive rainfall type I is the dominant rainfall type. The amount of runoff and the soil loss under erosive rainfall type III were the most, followed by rain-fall type II, IV and I. Compared with CSF treatment, reforestation treatments decreased the average annual runoff depth and the soil loss by 25.5%–61.8% and 93.9%– 96.2% during the study period respectively. Meanwhile, runoff depth at PSF and EEF treatments was significantly lower than that in NST treatment, but no significant difference existed in soil erosion modulus among the three reforestation treatments. This is mainly due to the improved vegetation properties (i.e., vegetation coverage, biomass of above- and below-ground and litter-fall mass) and soil properties (i.e., bulk density, total porosity, infiltration rate and organic carbon content) in the three reforestation treatments compared to CSF treatment. The PSF and EEF are recommended as the preferred reforestation types to control runoff and soil erosion in the red soil region of southern China, with the NST potentially being used as an important supplement.     

气箱式脉冲喷吹袋式除尘器清灰系统主要技术参数的确定

为了揭示气箱式脉冲袋式除尘器的清灰机理,应用压缩气体流动能量方程,推导出滤袋表面的反向清灰风速教学表达式;根据袋式除尘器实验模型测定的数据,得出了剥离力与粉尘剥离率之问的关系式,并在此基础上提出了清灰系统设计方法;应用气体射流理论得到了脉冲喷吹质量流量、喷吹口直径、空压机供气压力和供气量的计算公式.结果表明,在粉尘负荷一定的条件下,给定预期的剥离率,可以得到所必需的反向清灰风速和喷吹气体流量,据此可以确定清灰系统的主要技术参数.     

报废显像管的适用处置方法

指出了报废显像管的处理是报废电视机处理的关键步骤,分析了显像管屏、锥玻璃的结构组成,概述了报废显像管环保处理的几种方法,介绍了适用于报废显像管玻璃环保处理、再生利用的实用工艺过程。