Experimental studies of cutting force variation in face milling

The purpose of this paper is to present a developed cutting force model for multi-toothed cutting processes, including a complete set of parameters influencing the cutting force variation that has been shown to occur in face milling, and to analyse to what extent these parameters influence the total cutting force variation for a selected tool geometry. The scope is to model and analyse the cutting forces for each individual tooth on the tool, to be able to draw conclusions about how the cutting action for an individual tooth is affected by its neighbours.A previously developed cutting force model for multi-toothed cutting processes is supplemented with three new parameters; eccentricity of the spindle, continuous cutting edge deterioration and load inflicted tool deflection influencing the cutting force variation. A previously developed milling force sensor is used to experimentally analyse the cutting force variation, and to give input to the cutting force simulation performed with the developed cutting force model.The experimental results from the case studied in this paper show that there are mainly three factors influencing the cutting force variation for a tool with new inserts. Radial and axial cutting edge position causes approximately 50% of the force variation for the case studied in this paper. Approximately 40% arises from eccentricity and the remaining 10% is the result of spindle deflection during machining. The experimental results presented in this paper show a new type of cutting force diagrams where the force variation for each individual tooth when two cutting edges are engaged in the workpiece at the same time. The wear studies performed shows a redistribution of the individual main cutting forces dependent on the wear propagation for each tooth.     

Variation in exon 10 of the ovine calpain 3 gene (CAPN3) and its association with meat yield in New Zealand Romney sheep

Variation in the ovine CAPN3 gene was analysed using PCR-single strand conformational polymorphism, and its effect on growth and carcass traits was assessed in 513 New Zealand Romney lambs produced by 17 unrelated rams. Among the four allelic variants detected, the presence of variant *02 was found to be associated with an increased proportion of shoulder yield (absent: 32.6 ± 0.01%; present: 33.4 ± 0.03%; P = 0.016), and tended to be associated with increased shoulder yield (lean meat yield of the shoulder expressed as a percentage of the hot carcass weight) (absent: 16.6 ± 0.06%; present: 17.02 ± 0.20%; P = 0.067). No association was detected with growth traits or other carcass traits.     

箱型约束变分不等式的微粒群算法

对箱型约束变分不等式的简单光滑价值函数,给出了求解箱型约束变分不等式的微粒群算法。该算 法具有计算简单、快速收敛到全局最优解和较高的计算精度等优点。数值计算结果表明,提出的算法可靠性高、有 效性强,在计算精度上,都优于阻尼牛顿法和正则半光滑牛顿法     

银山铅锌矿矿坑水质水量变化规律初探

本文引用银山铅锌矿连续六年 (1993年— 1998年 ) ,每旬一次对铅锌矿坑水水质水量的监测数据 ,并结合地质、气象、采矿等情况 ,分析了铅锌矿床井下开采后期矿坑水水质水量的变化规律。     

电容电压和电感电流跃变分析

本通过数学分析的方法给出了电容电压在冲激电流的作用下,电感电流在冲激电压作用下的跃变规律,并对其物理意义进行解释。     

随机建模技术在孤岛油田西区精细油藏描述中的应用

精细油藏描述关键在于建立能够定量描述和表征油藏储集层及流体的油藏地质模型。孤岛油田西区馆陶组油藏属于河流相沉积 ,砂体分布零散 ,横向变化大 ,建立准确地质模型难度较大。应用先进的随机地质建模技术 ,确定了孔隙度、渗透率、含油饱和度的三维变异函数 ,优选指数模拟为最佳建模方法 ,建立了该区储集层参数三维地质模型 ,较好反映了储集层参数空间变化的非均质性。通过研究 ,主要有以下认识 :①随机模拟的基础是求准变异函数 ,求准变异函数不但能直接评价储集层的非均质性 ,而且其准确程度直接影响模拟结果的精度 ;②强调地质约束 ,必须在充分认识地质规律的基础上 ,经过多种方法校验 ,选择合适的地质模型 ;③由于随机模拟方法本身的特殊性和地质条件的差异性 ,目前较成功的方法和实例往往只用于特定储集层 ,因此模拟难度较大 ,必须不断探索 ,总结经验 ;④只有把随机模拟技术应用到从勘探到开发的全过程中 ,并且与油藏数值模拟技术充分结合起来 ,其优越性才能充分发挥。图 2参 2 (孙国摘 )     

Loss-efficiency model of single and variable-speed compressors using neural networks

Compressor is the critical component to the performance of a vapor-compression refrigeration system. The loss-efficiency model including the volumetric efficiency and the isentropic efficiency is widely used for representing the compressor performance. A neural network loss-efficiency model is developed to simulate the performance of positive displacement compressors like the reciprocating, screw and scroll compressors. With one more input, frequency, it can be easily extended to the variable speed compressors. The three-layer polynomial perceptron network is developed because the polynomial transfer function is found very effective in training and free of over-learning. The selection of input parameters of neural networks is also found critical to the network prediction accuracy. The proposed neural networks give less than 0.4% standard deviations and ±1.3% maximum deviations against the manufacturer data.     

天然气中汞含量的变化规律及应用――兼述岩石和土壤中汞的含量

1953年日本熊本县水俣湾发生了历史上首次重金属――汞污染重大事件,国际上立即对汞污染问题给予了高度重视,此后相关领域关于汞研究的成果也不断涌现。文中介绍了天然气中汞含量的变化和气类型判识的应用,并概述了岩石和土壤汞的含量变化;由于汞的高电离势和高挥发性,汞极易形成化合物,也易于从化合物中再还原出来,所以汞在不同物质中含量不一样,甚至在同类物质中的含量也会有明显差别,例如汞在天然气中含量为2.8～3000000ng/m3,在陨石中的含量为0.004～38.94μg/g,在变质岩中含量为2～3900ng/g之间,在火成岩中含量为4.5～1600000ng/g之间,在沉积岩中含量为0.005～2000μg/g之间,在土壤中含量为1～290ng/g之间。还指出汞在沉积、迁移和聚集的过程中形态变化十分复杂,因此物质中汞含量的变化规律也会因为汞的地球化学特性、深大断裂、岩浆活动、岩性及地貌等因素的变化而改变;随着人们环保意识日益增强,技术手段改进、仪器精度提高和汞研究领域不断拓宽,对汞含量在天然气中的变化规律的认识也会更加客观。     

分离式温控热管实验研究

根据热能工程及化工领域中的某些实际需要,提出了一种新型分离式温控热管并进行了实验研究。该种热管能够在保持传热温度变化很小的情况下自动改变传热功率来适应负荷变化的需要。实验结果表明,当温控热管传热功率增加200％时,热管工作温度变化小于5％。     

青岛近代建筑原型的变异

青岛近代建筑主要受德国建筑的影响,但是在德国人建立青岛建筑原型的同时,建筑形式的变异也随之产生了,德据之后青岛近代建筑的发展多是这种原型变异的延续。该文着重从建筑细部、建筑形体等方面分析这种外来建筑文化原型在德据时期、日据时期、民国时期及今天的情况。