基于SVM-GA模型的城市天然气长期负荷预测

天然气长期负荷预测能够解决城市燃气供需不平衡的问题,为城市燃气公司的管理运行提供帮助。为了提高天然气长期负荷的预测精度,提出了基于SVM-GA(SupportVectorMachines-GeneticAlgorithm)的天然气长期负荷预测模型。分析确定影响天然气用气量的相关因素,应用遗传算法和交叉验证方法分别对支持向量机模型的惩罚因子c 及核函数参数g 进行优化,以期提高支持向量机模型的预测精度,将优化后的参数输入支持向量机模型中,进行天然气长期负荷预测。以某省实际的样本数据为例,将SVM-GA模型的预测结果与SVM 和交叉验证法结合模型及BP(BackPropagation)神经网络模型的预测结果进行比较分析。结果表明,SVM-GA 预测模型分别比SVM 和交叉验证法结合预测模型和BP神经网络模型在衡量预测精度的相对均方误差、归一化均方误差、归一化绝对平方误差、归一化均方根误差、最大绝对误差五个指标分别高0.58%、3.98%、2.99%、4.58%、8.64%和6.13%、26.28%、19.71%、21.09%、31.48%。因此支持向量机与遗传算法相结合的模型能够较准确地预测天然气长期负荷。     

一种基于占有率反馈的虚拟网络映射算法

网络虚拟化技术通过对物理资源的抽象,可以有效解决现有互联网架构中存在的网络结构僵化、可扩展性差等问题.虚拟网络映射问题是指将用户发送的所有虚网请求映射到底层物理网络中,同时还要满足虚网请求中对各个资源的限制要求(如节点计算能力、链路带宽等).从节点负载平衡的角度出发,在基于就近原则的虚网映射算法基础上,引入节点负载平衡的反馈机制,引导各个虚网请求更均匀地映射到底层物理网络中.另外,在k短路径算法机制中引入了当前链路资源占有率作为评价参考标准,这样可以尽可能均匀地分散链路压力.同时,在检验链路资源是否满足虚网请求的过程中,由于优先选中的链路资源占有率低,所以算法映射成功率高,映射耗时更短,虚拟网络映射效率得到了有效提高.     

优化兑炼重整油比例提高芳烃装置运行效益

重整油价格低廉,但未经工艺切割及加氢处理的重整油不能直接作为以环丁砜为溶剂的芳烃抽提原料。文章主要介绍芳烃装置如何根据自身负荷余量,尽最大比例兑炼富含重质芳烃、溴价、胶质等组成的重整油,拓宽芳烃原料来源,做大总量,提高装置运行效益,为同类芳烃组合工艺兑炼未经加氢重整油的生产提供实际生产操作经验及依据。     

含有联二萘结构手性负载催化剂用于不对称催化反应研究进展

不对称催化是获得单一光学活性化合物最好的方法之一,然而贵重的手性催化剂的分离与回收是一个难题,针对BINOL、BINAP这两类具有联二萘结构的手性负载催化剂近年的研究进行了总结,认为以结构可控的高分子为载体,发展从分子水平上设计高分子手性配体及催化剂的方法是可行的。     

料层减荷烧结支撑板支撑结构优化

通过在料层内安装支撑板,减轻下部料层荷重,改善料层尤其是燃烧带的透气性,达到提高生产率的目的.以利用系数、转鼓强度为考察对象,通过正交实验,研究了烧结混合料水分、支撑板高度、支撑面积对利用系数、烧结矿转鼓强度的影响,应用综合分析法确定了最佳支撑结构,即支撑板高度约为料层高度的1/2,支撑面积为所支撑烧结饼面积的1.0%～1.2%.最优方案与基准实验的对比表明,应用料层减荷烧结,烧结生产率最大提高28.05%,转鼓强度下降3.75%,料层收缩减小28 mm,还原性提高0.46%.     

半水煤气直冷塔的计算与设计

为降低合成氨装置压缩机一段入口的半水煤气温度,设计了填料式直接冷却塔,用水作为冷却剂。介绍了直冷塔的设计计算过程,包括塔的选型,气液比的确定,空速、塔径、填料高度的计算,填料层压降、喷淋密度的核算,以及塔附件的设计等。生产运行结果表明,出塔半水煤气温度由原来的42℃下降到30℃以下。     

Random effects mixture models for clustering electrical load series

For purposes such as rate setting and long‐term capacity planning, electrical utility companies are interested in dividing their customers into homogeneous groups or clusters in terms of the customers’ electricity demand profiles. Such demand profiles are typically represented by load series, long time series of daily or even hourly rates of energy consumption of individual customers. The high dimension and time series nature inherent in the load series render existing methods of clustering analysis ineffective. To handle the high dimension and to take advantage of the time‐series nature of load series, we introduce a class of mixture models for time series, the random effects mixture models, which are particularly useful for clustering the load series. The random effects mixture models are based on a hierarchical model for individual components. They employ highly flexible antedependence models to effectively capture the time‐series characteristics of the covariance of the load series. We present details on the construction of such mixture models and discuss a special Expectation‐maximization (EM) algorithm for their computation. We also apply these models to cluster the data set which had motivated this research, a set of 923 load series from BC Hydro, a crown utility company in British Columbia, Canada.     

基于光纤光栅的复合材料动态称重系统研究

本文利用光纤布拉格光栅(FBG)的智能感知特性研制开发一种复合材料结构,用以汽车的动态称重.采用轴荷称重的方法进行动态称重,其基本思想是将光栅布设在称体结构的承重梁上,利用光栅监测称体的变形,根据己知系统的动态特性和实测的动力响应,即称体的变形,反算出结构所受的动态激励,从而获得汽车载荷.首先,基于光纤传感器的原理和称重结构的力学特性,推导出载荷识别的算法.对称重系统进行动态实验,结果表明了以上算法的合理性,并对误差进行了分析.     

Tribocorrosion behaviour of TiCxOy thin films in bio-fluids

Decorative coatings require not only an attractive appearance for market applications, but also an ability to protect the surface underneath. Because of this, corrosion, wear and their combined effects (termed tribocorrosion) are particularly important for lifetime prediction. In this paper, the tribocorrosion behaviour of a range of single layered titanium oxycarbide, TiC_xO_y, coatings, produced by DC reactive magnetron sputtering, has been studied and reported as a function of electrode potential and applied load. The study was conducted in a reciprocating sliding tribo-system (Plint TE 67/E) in a bio-fluid (an artificial perspiration solution) at room temperature. During the wear tests, both the open-circuit potential and the corrosion current were monitored. The results showed that electrode potential and load have a significant influence on the total material loss. The variations in R_p (polarization resistance) and C_f (capacitance) before and after sliding, obtained by Electrochemical Impedance Spectroscopy (EIS) were evaluated in order to provide an understanding of the resistance of the film in such conditions. Tribocorrosion maps were generated, based on the results, indicating the change in mechanisms of the tribological and corrosion parameters for such coatings, as a function of load and applied potential.     

循环水替代7℃水在氯乙烯精馏装置中的应用研究

详细计算了PVC生产精馏系统换热设备的热负荷、循环水量及运行成本,认为通过调整系统的运行温度和压力,精馏装置使用循环水替代7℃水具有可行性,这将有利于突破能耗高的技术瓶颈,最大程度地发挥节能降耗、减污增效的潜能.