电厂启动备用变压器继电保护应用分析

针对电厂备用变压器分支较多这一特殊情况,从理论上对保护配置与整定上存在的问题进行了深入分析,提出了切实可行的保护配置和整定计算方法,具有较高的应用价值和推广意义。     

Optimal packing of transformer coil via dynamic programming

One of the transformer major design elements is its core design. The good performance of the transformer requires its coil core to be laminated and composed of different - widths stepped layers of specific steel packed together. For optimum design, the cross sectional shape of the core must be as circular as possible. So, an optimal packing can be attained by maximizing the steel core coverage. The number of different widths of steel plates n is selected to compose the packed core for a coil of diameter d. Then, an optimum sequence of decisions, for the n widths as well as the number of thin plates of each, is required. Dynamic programming (dp) is concerned with this optimum sequential decisions. An adequate forward recursive equation is formulated , because there isn't a standard dp model for all sequential decision making problems. To implement the recursive computations, a FORTRAN program is developed. Assuming that d is given the values 150, 200, 250, 300, 400 and 500 mm. while giving n the values from 2 to 15, the program is run at different combinations of n and d. It is found that maximum core coverage is sensitive to changing of n but it is slightly affected by changing of d.     

夹杂物问题应力场的数值计算

等效夹杂物方法是细观力学中的一种重要方法，文中编制的数值计算程序能在考虑多个夹杂物相互响应的情况下计算材料应力、应变场，并实现了计算结果的三维显示．计算结果与文献中的计算结果非常吻合．本文编制的数值计算程序不仅可以用于研究复合材料的损伤演化及失效，而且利用特殊构型的椭球空洞来模拟裂纹，可以计算裂纹群的应力、应变场。     

Incident Light Metering in Computer Graphics

Every rendering process consists of two steps. The first is the computing of luminance values by methods like ray tracing or radiosity, and the second step is the mapping of the computed values to values appropriate for displaying. In the last years, as alternative to simple linear scaling which maps the average value to the medium luminance, some new ways of mapping were introduced. These new methods are based on photography analogies and on human vision models. All existing methods follow, implicitly or explicitly, the reflected light metering principle. The method introduced in this paper is the first that follows the incident light metering used in professional photography and in the movie industry. Actually the irradiances are measured using a set of diffusors, which are placed automatically in the scene, and a linear scale factor based on these measurements is used to map the computed radiances to the display device. The diffusors act as half space integrators, they collect the light energy from all half space directions. The light comes from the primary light sources, or it is the result of various interreflections. The newly introduced method reproduces original colors faithfully even for scenes with very low or very high average reflectivity.     

DNA编码限制条件与编码策略

以评价DNA编码的基本限制条件之一——Hamming距离为出发点分析了DNA编码的三个参量：码字个数、码字长度与Watson-Crick Hamming距离,并得到它们之间的内在联系;讨论了Watson-Crick Hamming距离与DNA码字重量之间的关系;在此基础上得到了DNA编码的编码策略;提出了适合DNA编码的改进Watson-Crick Hamming距离及DNA编码模块化的定义,对DNA编码的优化做出了详细分析,为DNA计算的发展注入了活力。     

Identifying cell-to-cell variability in internalization using flow cytometry

Biological heterogeneity is a primary contributor to the variation observed in experiments that probe dynamical processes, such as the internalization of material by cells. Given that internalization is a critical process by which many therapeutics and viruses reach their intracellular site of action, quantifying cell-to-cell variability in internalization is of high biological interest. Yet, it is common for studies of internalization to neglect cell-to-cell variability. We develop a simple mathematical model of internalization that captures the dynamical behaviour, cell-to-cell variation, and extrinsic noise introduced by flow cytometry. We calibrate our model through a novel distribution-matching approximate Bayesian computation algorithm to flow cytometry data of internalization of anti-transferrin receptor antibody in a human B-cell lymphoblastoid cell line. This approach provides information relating to the region of the parameter space, and consequentially the nature of cell-to-cell variability, that produces model realizations consistent with the experimental data. Given that our approach is agnostic to sample size and signal-to-noise ratio, our modelling framework is broadly applicable to identify biological variability in single-cell data from internalization assays and similar experiments that probe cellular dynamical processes.     

矿山工业用转轮式除湿机的设计

以某型适合矿山地面生产部门用的工业转轮式除湿机为研究对象,讨论了除湿机的基本工作原理并进行理论分析计算。在结构设计时,充分考虑到除湿机的工作环境特点,对其结构进行了优化设计。通过实际测试,结果表明与设计计算值基本吻合。     

Early bankruptcy prediction using ENPC

Bankruptcy prediction has long time been an active research field in finance. One of the main approaches to this issue is dealing with it as a classification problem. Among the range of instruments available, we focus our attention on the Evolutionary Nearest Neighbor Classifier (ENPC). In this work we assess the performance of the ENPC comparing it to six alternatives. The results suggest that this algorithm might be considered a good choice.     

非精确计算中的实时数据库服务质量管理

传统的数据库已经不能满足仿真数据库对性能优化的要求。因此,提出了非精确计算中由反馈环节控制的实时调度算法。在这些研究的基础上对该方法提出了改进,提出了使其在各种负载条件下,通过在反馈控制中设定遗忘因子以及引入最大限度数据错误的平均值来减少系统的突变,增强了系统的稳定性,提高了实时系统服务质量。     

考虑流固耦合的混流式水轮机转轮模态分析

迄今为止 ,国内的许多进口和国产的大型水轮机组转轮叶片都出现了不同程度的裂纹破坏 ,严重影响了电站的安全生产和机组的稳定运行[1 ,2 ] 。大量的研究表明 ,导致裂纹产生的一个重要原因是水力激力引发的结构共振所产生的动载荷作用。特别是出现低频共振时 ,极易引起结构的严重破坏[2 ] 。随着机组单机容量的不断地增加 ,转轮的固有频率降低 ,发生共振的危险性也更大。因此 ,针对转轮在水介质中的模态特性的研究具有十分重要的现实意义。本文运用全流固耦合的三维有限元方法对某一混流式转轮在水介质中的模态特性进行了研究 ,得到了转轮在水中的自振频率和振型等振动特性。结果表明 ,转轮在水中的第 1阶固有频率与叶片旋转频率相近 ,额定工况下的卡门涡频率又接近于转轮的高阶固有频率 ,这极有可能引发结构的共振 ,导致裂纹的产生。