Construction of a control system for disturbance rejection using a dual observer

A well‐known control system which can reduce the adverse effects of disturbances is a disturbance observer. However, in many cases of mechanical systems, system disturbances which do not satisfy the matching condition may be imposed. Therefore, it may be difficult to reduce the adverse effects of the disturbances by the traditional disturbance observer. In this paper, a method of control system synthesis for disturbance rejection using a dual observer is proposed. This method is based on the zeroing induced by the disturbance localization problem. This problem may be solved by dividing the state space into observable subspace and unobservable subspace. As compared with an H_∞ controller based on perfect observation, the usefulness of the proposed control system for disturbance rejection is demonstrated by numerical simulations for a two‐mass spring system. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 50–60, 2002; DOI 10.1002/eej.1138     

On the design of multiple key hashing files for concurrent orthogonal range retrieval between two disks

This paper concerns the following problem: given a set of multi-attribute records, a fixed number of buckets and a two-disk system, arrange the records into the buckets and then store the buckets between the disks in such a way that, over all possible orthogonal range queries (ORQs), the disk access concurrency is maximized. We shall adopt the multiple key hashing (MKH) method for arranging records into buckets and use the disk modulo (DM) allocation method for storing buckets onto disks. Since the DM allocation method has been shown to be superior to any other allocation methods for allocating an MKH file onto a two-disk system for answering ORQs, the real issue is knowing how to determine an optimal way for organizing the records into buckets based upon the MKH concept.

A performance formula that can be used to evaluate the average response time, over all possible ORQs, of an MKH file in a two-disk system using the DM allocation method is first presented. Based upon this formula, it is shown that our design problem is related to a notoriously difficult problem, namely the Prime Number Problem. Then a performance lower bound and an efficient algorithm for designing optimal MKH files in certain cases are presented. It is pointed out that in some cases the optimal MKH file for ORQs in a two-disk system using the DM allocation method is identical to the optimal MKH file for ORQs in a single-disk system and the optimal average response time in a two-disk system is slightly greater than one half of that in a single-disk system.     

Lubricating behavior of iron rhenate and its relation to matching pairs

The iron rhenate was compounded by chemical method, which may be generated during wear process of Fe-Re alloys at elevated temperature. The friction coefficient of iron rhenate has been determined by a pin-on-disc device. The results show that iron rhenate plays role of lubricating at RT-600 °C. The lubricating behavior is related to the matching pairs. The hardness of the materials of matching pairs, compatibility of iron rhenate with materials of matching pairs and surface roughness of disc affect the lubricating behavior of iron rhenate mostly. The principle of matching pairs is proposed. Project supported by the National Natural Science Foundation of China Synopsis of the first author Xiong Dangsheng. associated professor, born in 1960. Current research fields include high-temperature self-lubricating alloys and tribological properties of material.     

化工搅拌器的参数优选

本文提出了确定化工用搅拌器搅拌时间的一种简单试验方法,并用正交表安排寻找最佳搅拌参数的试验和整理试验数据,得到了有实用价值的结果。     

明代茶诗与文人茶的艺术精 神简

文人茶是中国茶文化体系中具有独立品格与内涵的茶文化模式,也代表着中国茶文化的最高层次。明代中期以后,文人们推崇饮茶“天趣悉备”的自然美,许多文人更是全身心投入到茶事活动中,将茶事品茗作为表达志向与修身养性的主要方式,茶诗创作成果丰硕。茶诗的创作是一种文学现象,极大地丰富了茶文化的表现形态与内涵。明代茶诗体现出明代文人茶虚静空灵、天人合一以及本真自然、闲适清逸的艺术精神。     

《野草》与鲁迅心灵世界的悖论

鲁迅思想的矛盾性集中体现在他的《野草》中。这种矛盾并非简单的二元对立,而是充满着结构张力的逻辑两难,它们相互依存相互冲突,纷繁复杂的呈现在文本中,使得《野草》表现出多义特征。     

A portable stereo vision system for whole body surface imaging

This paper presents a whole body surface imaging system based on stereo vision technology. We have adopted a compact and economical configuration which involves only four stereo units to image the frontal and rear sides of the body. The success of the system depends on a stereo matching process that can effectively segment the body from the background in addition to recovering sufficient geometric details. For this purpose, we have developed a novel sub-pixel, dense stereo matching algorithm which includes two major phases. In the first phase, the foreground is accurately segmented with the help of a predefined virtual interface in the disparity space image, and a coarse disparity map is generated with block matching. In the second phase, local least squares matching is performed in combination with global optimization within a regularization framework, so as to ensure both accuracy and reliability. Our experimental results show that the system can realistically capture smooth and complete whole body shapes with high accuracy.     

Sparse shape functions for tetrahedral <Emphasis Type="Italic">p</Emphasis>-FEM using integrated Jacobi polynomials

Summary In this paper, we investigate the discretization of an elliptic boundary value problem in 3D by means of the hp-version of the finite element method using a mesh of tetrahedrons. We present several bases based on integrated Jacobi polynomials in which the element stiffness matrix has nonzero entries, where p denotes the polynomial degree. The proof of the sparsity requires the assistance of computer algebra software. Several numerical experiments show the efficiency of the proposed bases for higher polynomial degrees p.      

光存储材料CaS∶Eu,Sm的正交实验制备及表征

CaS∶Eu,Sm材料在光存储、光探测领域具有广阔应用前景,但制备过程中影响其发光性能的因素较多,彼此又有交互作用,不易获得最佳工艺参数。本文采用高温固相反应法,通过正交实验设计系统研究了灼烧温度、灼烧时间、稀土掺杂浓度、助溶剂用量对CaS：Eu,Sm发光性能影响的主次关系,经正交分析和验证实验确定了最佳工艺参数应为：Eu∶Sm∶Ca mol%=0.3∶0.3∶99.4%,1100℃灼烧0.5h,助熔剂LiF用量为7%。采用X射线粉末衍射仪、荧光分光光度计（耦合1064nm激光激励源）对样品的物相及发光性能进行了测试与表征。     

组合式空调系统设计中机组选型方法探讨

对目前组合式空调机组在选型设计及使用中出现的问题进行了分析，运用空气处理设备选型的有关理论和计算方法，对舒适性空调系统中机组选型的一些问题和数据进行了简化和近似处理，提出了能够满足工程设计的要求的简便实用的选型方法。