用于确定双吸离心泵Suter曲线的三维内特性法研究

水泵Suter曲线是泵站水锤分析的必备条件之一。现有用于获取双吸离心泵Suter曲线的实测法具有难度大、成本高的特点,而间接插值估算法的精度又比较低,本文提出了一种通过水泵流场三维数值计算确定双吸离心泵Suter曲线的新方法,简称三维内特性法。该方法采用计算流体力学(CFD)技术,对双吸离心泵的水力模型进行三维造型、工况离散、流场计算及结果转化,以快速、准确地获取双吸离心泵Suter曲线,在正水泵工况、正水轮机工况、反水轮机工况、反水泵工况等工况下,计算出相应流量、转速、扬程和转矩关系。定量分析表明,相比于间接插值估算法,采用三维内特性法获得的Suter曲线中,Wh(x)的计算精度平均提高了39.2%,Wb(x)的计算精度平均提高了26.3%;在将采用该方法获得的双吸离心泵Suter曲线用于事故停泵工况水锤分析时,计算得到的系统最大压力降低了15.0%,管线发生汽化压力的范围缩减了81.4%,双吸离心泵的最大倒流量增大了11.9%,最大倒转速降低了6.1%,与实际测试结果更为接近。该方法为提高双吸离心泵站水锤分析精度提供了一种新技术途径。     

The design of experiments,training and implementation of nonlinear controllers based on neural networks

In the area of nonlinear predictive control, several control schemes using artificial neural networks have been proposed. In this work, the issues relating to the information contents of the data used to train the neural network components of these nonlinear predictive control schemes are considered. This raises questions about the design of experiments. A class of feedback-feedforward nonlinear controller based on the model predictive structure (also known as Internal Model Control, IMC, structure) is investigated. The implementation and performance of these neural network based controllers, together with comparisons to other nonlinear and linear controllers, are illustrated on two nonlinear continuous-stirred-tank-reactor simulations.     

硼矿制硼酸母液中硼含量的测定方法探讨

报道了笔者用水相直接显色型比色法测定硼酸母液中硼含量的实验和结果。     

N－氰基乙亚胺酸乙酯含量的气相色谱分析

采用GC-900气相色谱仪、3%PEG-12000/Chromosorb880AWDMCS填充柱和FID检测器,以水杨酸甲酯为内标物测定N-氰基乙亚胺酸乙酯含量,回收率在98.5%—101.8%之间,标准偏差为0.27%,变异系数为0.27%。     

Coordination between strategic forest management and tactical logistic and production planning in the forestry supply chain

In this paper, we study the coordination mechanism in the forestry supply chain between strategic forest management and tactical production planning. We first formulate an integrated model to establish a theoretical benchmark for performance of the entire supply chain. It is a mixed integer programming model that involves harvesting, bucking, transportation, production, and sales decisions for both tactical and strategic planning levels. We then present two sequential approaches S‐A and S‐B where the coordination is done through internal pricing. S‐A is the approach currently used in practice where harvesting in the forest is the main driver of the supply chain activities and internal pricing is introduced to control bucking decision in a separate stage. In contrast, S‐B takes downstream demand information into consideration and internal pricing directly influences harvesting decision in the first stage. In order to find the appropriate setting of internal pricing that leads to the system optimum, we suggest two heuristics H‐I and H‐II. The internal pricing in H‐I is based on dual values and in H‐II, it is derived from a Lagrangian decomposition. A real‐life case study in the Chilean forestry industry is used to compare the results of different approaches. It is shown that the new sequential approach S‐B generates as good feasible solution as that obtained from the integrated approach but in much less time. Both heuristics H‐I and H‐II bring about near‐optimal feasible solutions. H‐II also provides optimistic bound of the optimal objective function value, which can be used as a measure of the solution quality.     

基于GA-SVM逆系统的机械臂内模控制

六自由度机械臂系统具有强耦合、多输入多输出、非线性的特性,且难以求解精确的动力学模型。针对上述问题,提出了一种基于GA-SVM逆系统的六自由度机械臂内模控制方法。将逆系统方法用于六自由度机械臂的解耦可以有效简化控制器的设计,为了避免逆系统方法复杂的解析过程,采用基于支持向量机(SVM)辨识逆系统模型以实现解耦,并用遗传算法(GA)优化SVM系统参数以提高模型的准确性。同时,为了弥补SVM辨识逆系统的误差以及抑制系统存在的扰动,设计内模控制器以保证系统的鲁棒性和稳定性。实验结果表明,该方法不需要知道六自由度机械臂的数学模型和内部结构,也能实现各关节位置的快速精确定位控制,且具有良好的鲁棒性,结构简单,需要调节的参数少,易于工程实现。     

阀门内漏单声波传感器监测方法研究

针对阀门内漏模拟和阀门内漏监测问题，提出了阀门内漏模拟和阀门内漏非介入式单声波传感器监测方法。设计了由法兰、薄纸片和带孔铝片组成的虚拟阀门，可真实地模拟阀门内漏瞬态过程，克服了传统阀门内漏模拟方法中存在的各种缺点。分析、比较了不同条件下阀门上下游声波传感器输出信号的频域特征，验证了阀门上游声波传感器设置的冗余性和基于单声波传感器实现阀门内漏监测的可行性。分析、比较了不同条件下单声波传感器输出信号的时频域特征，提出了基于峰值系数和小波包能量分率的阀门内漏时频域特征提取方法，并以阀门密封良好状态下的声波信号为样本，建立了基于SVDD的阀门内漏诊断模型。测试结果表明：本文提出的单声波传感器阀门内漏监测方法可行、模型诊断准确，且具有较强的抗干扰能力和较高的阀门内漏检测灵敏度。     

内构件存在时提升管内流动及颗粒混合行为研究

he hydrodynamics and solids mixing behavior in a riser with blunt internals are studied. A uniform radial distribution for solids fraction and particle velocity achieves near the internals. The turbulent velocity of particles near the wall increases with the addition of the internals, with the lateral solids mixing enhanced significantly. Probability density distribution of particle velocity is bimodal in the riser with internals, which is similar to that in the conventional riser, indicating that no significant difference in the micro flow structure exists between the riser with internals and the conventional riser. At the same time, the axial solids mixing behavior changes insignificantly with the addition of internals. These results indicate that the micro flow structure in the riser is very stable, which changes insignificantly with the change of the bed structure.     

ANSYS在整体式排水圆管分析中的应用

基于ANSYS APDL参数化设计语言编写程序,利用程序对整体式排水圆管进行数值计算.模型中考虑了不同荷载的施工方法,并利用路径映射技术实现了各截面的内力输出,从而合理地揭示了在土压力、外水压力和自重的共同作用下整体式排水圆管的位移、应力和内力分布规律.最后通过工程实例,验证了程序的可靠性.     

高等院校内部财务控制方式的研究

高校财务管理是高校各项管理的重要组成部分。针对我国高等院校目前财务管理中财务控制面临的主要问题,从建立全面的内部预算控制管理系统、建立费用绩效控制核算体系、建立财务风险防范体制等三个方面入手,指出建立高校全方位内部财务控制的方向,使高校能在完善现有财务管理工作的基础上,把有限的学校资金合理有效地分配到教学、科研、学校建设发展等各个方面,让高校的内部财务控制真正能适应高校新的发展环境变化及高校自身财务管理的实际要求。