A new approach for sequential experimental design for model discrimination

Model discrimination procedures are useful tools for selection of the best mathematical models to be used to represent a specific chemical process. The present paper presents and discusses a new sequential discrimination procedure, which makes use of model probabilities and concentrates the efforts on models with higher probabilities. Model probabilities are determined based on simple statistical arguments. Four numerical examples illustrate the application of the proposed discrimination procedure. The obtained results indicate that the new procedure is able to discriminate kinetic models with fewer experiments when compared to other procedures and also indicates when model discrimination is not possible and, thus, when the sequential design must be halted. Furthermore, the speed of the proposed discrimination procedure can be controlled by tuning a design parameter which reflects the analyst's mood (confidence) towards the discrimination problem and allows for increase or decrease of the number of experiments required for model discrimination during the sequential procedure.     

Ozone Contribution in Food Industry in Japan

Ozone has the strongest oxidization effect after fluorine, and this property has been used in sterilization for food and processing plants in Japan. Moreover, there is no fear of toxic residues as with chlorine-based sterilizers and no hazardous trihalomethanes are formed. Based on these advantages, ozone has been used in water and air treatment for food products food materials and food processing plants. Use in the food processing is now increasing in Japan. This paper describes ozone sterilization, introducing sterilization systems and equipment applied to food in Japan.     

稳定剂及加工工艺条件对PVC／MBS光学性能的影响

本文就稳定剂和加工工艺条件对ＰＶＣ／ＭＢＳ共混物的透光率的影响进行了探讨，发现稳定剂种类、用量、加工温度和时间对ＰＶＣ／ＭＢＳ共混物制品的光学性能有较大的影响。在用量相同的情况下，ＴＭ－１８１ＦＳ的持久热稳定效果要比京锡８８３１好，而耐初期着色性则相差不大，ＴＭ－１８１ＦＳ的用量以１．５～２．５份为宜。环氧大豆油与有机锡组成的复合稳定体系具有协同性，稳定效果较好。随着塑化时间的延长，ＰＶＣ／ＭＢＳ的透光率下降。混炼时间较短时，随温度的升高，共混物的透光率变化不大；当混炼时间较长时，加工温度越高，ＰＶＣ／ＭＢＳ共混物的透光率越低     

管材冲切加工的研究进展

系统地探讨了管材切断、管端冲裁与管壁冲孔这3种管材冲切加工工艺的相关理论、应用及其最新研究进展;分析了管材冲切加工中存在的主要问题;讨论了怎样将数值模拟方法应用到管材冲切加工中,从而更有效地提高管材冲切加工的成形质量。     

本钢五号高炉铜冷却壁破损原因分析及处理技术的研究

炼铁厂五号高炉铜冷却壁的冷却水管因炉壳和冷却壁之间的压力灌浆及高炉炉体钢甲膨胀的影响导致高炉铜冷却壁的冷却水管被剪裂、剪断漏水,使高炉的生产稳定顺行受到了严重影响。通过上述冷却壁水管破损原因的分析,采用了用氦气进行对高炉铜冷却壁氩弧焊冷焊接。达到预期的效果,从而保证了高炉的安全生产和稳定顺行。     

修井作业中油管长度的检测

环形防喷器是在带压作业中实现高温高压的关键部件。油管上提或下降时,需对管箍位置进行检测。针对油田修井作业所需,设计了一种光栅检测的连续油管长度在线测量系统。系统采用光栅作为油管长度测量的传感器,用51单片机构成测量控制系统核心,根据实际需要设计了硬件电路并编写了软件程序,准确测量下井油管的单根长度和总体长度,此技术可延长环形防喷器寿命,节约成本,为修井作业时管箍及油管位置的判断及井口数据提供依据。     

水润滑扇形瓦推力轴承润滑性能的边界元分析

用边界元法分析水润滑扇形瓦推力轴承的润滑性能,将雷诺方程转化为类似泊松方程的形式,采用边界元法求解该方程,研制了一套C++计算程序,得到多组轴瓦参数下的水膜厚度、压力分布和相关润滑性能,可以显著降低代数方程组的阶数,从而减少计算所需时间,并可提高计算精度。研究表明瓦块张角和瓦块倾角对最小水膜厚度、最大水膜压力、摩擦功耗、压力中心位置和进水口流量有不同程度的影响,该研究将有助于合理的设计水润滑扇形瓦推力轴承的轴瓦参数。     

磁流变材料在现代加工设备中的应用

磁流变(MR)材料是一种新型的智能材料,是由载液、表面活性剂、可磁化分散粒子等组成的一种流体。在外加磁场的控制下磁流变装置能够产生连续可控的阻尼力,从而对振动系统的振动性能进行实时控制。它的特性及应用都处于研究和探索阶段,但从初步实验成果来看磁流变材料有着广阔的应用前景,尤其是在减振降噪方面。简要介绍了磁流变材料的特性,归纳了磁流变材料在现代加工设备中的应用现状,展望了磁流变材料在现代加工设备中的应用前景。     

State feedback integral control for a rotary direct drive servo valve using a Lyapunov function approach

This paper concerns a state feedback integral control using a Lyapunov function approach for a rotary direct drive servo valve (RDDV) while considering parameter uncertainties. Modeling of this RDDV servovalve reveals that its mechanical performance is deeply influenced by friction torques and flow torques; however, these torques are uncertain and mutable due to the nature of fluid flow. To eliminate load resistance and to achieve satisfactory position responses, this paper develops a state feedback control that integrates an integral action and a Lyapunov function. The integral action is introduced to address the nonzero steady-state error; in particular, the Lyapunov function is employed to improve control robustness by adjusting the varying parameters within their value ranges. This new controller also has the advantages of simple structure and ease of implementation. Simulation and experimental results demonstrate that the proposed controller can achieve higher control accuracy and stronger robustness.     

基于UG与Vericut的复杂曲面加工仿真

现代制造过程中,复杂曲面产品增多,加工工序复杂,加工周期变长,数控程序的好坏直接影响数控加工的质量与效率。为了对计算机辅助编程生成的数控程序进行适合特定机床的验证和优化,不仅需要对刀路进行模拟,还需要对机床的运动进行仿真。本次研究以一件自由曲面工艺品的模具为例,首先在UG数控加工模块中对模具进行编程,然后利用UG和Vericut建立机床模型并导入模型G代码进行验证,最后根据机床和刀具参数对G代码进行优化。实例和结果表明,将UG加工编程与Vericut机床仿真相结合,能减少废品率,大幅度的提高加工效率。