Maximizing for the sum of ratios of two convex functions over a convex set

This paper presents an algorithm for globally maximizing a sum of convex–convex ratios problem with a convex feasible region, which does not require involving all the functions to be differentiable and requires that their sub-gradients can be calculated efficiently. To our knowledge, little progress has been made for globally solving this problem so far. The algorithm uses a branch and bound scheme in which the main computational effort involves solving a sequence of linear programming subproblems. Because of these properties, the algorithm offers a potentially attractive means for globally solving the sum of convex–convex ratios problem over a convex feasible region. It has been proved that the algorithm possesses global convergence. Finally, the numerical experiments are given to show the feasibility of the proposed algorithm.     

从“高技术革命”到“高铁革命”的发展研究——1．从“0和博”到“协议共赢”

用虚拟-实体经济博弈、战略-经济对话实例来界定“0和博弈”与“协议共赢”。笔者以1985～86年在Stanford大学的研究实践说明：在标准-计量平台上的产业链创新，从高技术革命到高铁革命．非合作博弈的Nash均衡，是技术经济发展的趋势。     

拉萨市纳金大桥锚索索鞍抗滑抗摩阻试验过程分析与总结

针对拉萨纳金大桥斜拉索锚索索鞍抗滑抗摩阻试验方法和试验过程，提出环氧握裹式抗滑锚固装置加载试验原理，按照抗滑试验方案要求，对环氧握裹式抗滑锚固装置进行测试，检验矮塔斜拉桥拉索桥塔锚固构造的静载抗滑移力学性能，对试验结果进行总结和分析，从设计和施工方面对斜拉索锚索索鞍抗滑抗摩阻性能提出建议。     

PROBING HIDDEN POLYMERIC INTERFACES USINGIR–VISIBLE SUM-FREQUENCY GENERATION SPECTROSCOPY

Understanding the molecular-level processes underlying interfacial phenomena is important in the area of adhesion. We briefly introduce IR–visible sum-frequency generation spectroscopy (SFG) using a total-internal-reflection geometry for the study of polymer–air, polymer–solid, and polymer–polymer interfaces. The following examples, predominantly of work done in our lab, illustrating differences in molecular structure and dynamic properties at interfaces are presented: the air- and solid-interface structure of an amorphous polystyrene (PS) and a semicrystalline polymer with side-chain crystallinity, poly(octadecyl acrylate) (PA-18); structure of a polymer–polymer interface between thin films of a semicrystalline polymer with side-chain crystallinity, poly(vinyl-N-octadecylcarbamate- co-vinyl acetate), and an amorphous PS; thermal order-to-disorder transitions of the air and solid interface of PA-18, and the interface of this polymer with PS; and dynamic surface-relaxation studies of a rubbed PS film.     

Multi-focal image fusion using degree of focus and fuzzy logic

The continuous advancement in the field of imaging sensor necessitates the development of an efficient image fusion technique. The multi-focal image fusion extracts the in-focus information from the source images to construct a single composite image with increased depth-of-field. Traditionally, the information in multi-focal images is divided into two categories: in-focus and out-of-focus data. Instead of using a binary focus map, in this work we calculate the degree of focus for each source image using fuzzy logic. The fused image is then generated based on the weighted sum of this information. An initial focus tri-state map is built for each input image by using spatial frequency and a proposed focus measure named as alternate sum modified Laplacian. For the cases where these measures indicate different source images to contain focused pixel or have equal strength, another focus measure based on sum of gradient is employed to calculate the degree of focus in a fuzzy inference system. Finally, the fused image is computed from the weights determined by the degree of focus map of each image. The proposed algorithm is designed to fuse two source images, whereas fusion of multiple input images can be performed by fusing a source image with the fusion output of the previous input group. The comparison of the proposed method with several transform and pixel domain based techniques are conducted in terms of both subjective visual assessment and objective quantitative evaluation. Experimental results demonstrate that our method can be competitive with or even outperforms the methods in comparison.     

Sketching asynchronous data streams over sliding windows

We study the problem of maintaining a sketch of recent elements of a data stream. Motivated by applications involving network data, we consider streams that are asynchronous, in which the observed order of data is not the same as the time order in which the data was generated. The notion of recent elements of a stream is modeled by the sliding timestamp window, which is the set of elements with timestamps that are close to the current time. We design algorithms for maintaining sketches of all elements within the sliding timestamp window that can give provably accurate estimates of two basic aggregates, the sum and the median, of a stream of numbers. The space taken by the sketches, the time needed for querying the sketch, and the time for inserting new elements into the sketch are all polylogarithmic with respect to the maximum window size. Our sketches can be easily combined in a lossless and compact way, making them useful for distributed computations over data streams. Previous works on sketching recent elements of a data stream have all considered the more restrictive scenario of synchronous streams, where the observed order of data is the same as the time order in which the data was generated. Our notion of recency of elements is more general than that studied in previous work, and thus our sketches are more robust to network delays and asynchrony. The work of the authors was supported in part through NSF grants CNS 0520102 and CNS 0520009. A preliminary version of this paper appeared in Proceedings of the ACM Symposium on Principles of Distributed Computing (PODC) 2006, pages 82–91. Work done while the third author was at Rensselaer Polytechnic Institute. Authors are listed in reverse alphabetical order.     

节能量计算方法探讨

目前,计算节能量的方法主要有两种:基准单耗对比法和累积和法。国内多采用基准单耗对比法计算节能量。此方法简单、方便,但是在技术措施实施前后产品产量有较大变化时,此方法的计算值存在误差,不能如实监测技术措施的实施效果。与基准单耗对比法相比,累积和法能更真实地计算出企业节能技术措施所带来的节能量,反映出能源消耗的趋势性变化,监测节能技术措施是否、以及具体何时发挥了作用。分析了累积和法在计算节能量时较基准单耗对比法更为真实的原因,并介绍如何使用累积和法监测节能技术措施的实施效果。以某化肥企业为例,结合该企业2009年的能源审计工作,运用累积和法,对该企业的节能量进行计算,分析该企业节能技术措施的实施效果,并发现能源审计期间一些引起企业能耗变化的因素,实例验证了累积和法节能量计算的准确性和有效性。     

支持媒体处理的子字绝对值单元设计与实现

子字并行结构的计算单元是提高多媒体应用程序性能的有效方式.研究和实现了支持子字并行的32位绝对值单元,并优化了该单元的关键路径.从时序,面积等方面对三种设计方案进行了分析比较.结果表明经过优化的子字并行绝对值单元在保证面积大小的同时,减小了整个单元的延时.     

On the conservativeness of fuzzy and fuzzy-polynomial control of nonlinear systems

A fairly general class of nonlinear plants can be modeled as fuzzy systems, i.e., as a time-varying convex combination of “vertex” linear systems. As many linear LMI control results naturally generalize to such fuzzy systems, LMI formulations for fuzzy control became the tool of choice in the 1990s. Important results have since been obtained in the fuzzy arena, although significant sources of conservativeness remain. This paper reviews some of the sources of conservativeness of fuzzy control designs based on the linear vertex models instead of the original nonlinear equations. Then, ideas that may overcome some of the conservativeness issues (but increasing computational requirements) are discussed. Recently, the sum of squares paradigm extended some linear results to polynomial systems; this idea can be used for the so-called fuzzy polynomial systems that are also discussed in this work.     

Study of self-assembled triethoxysilane thin films made by casting neat reagents in ambient atmosphere

We studied four trialkoxysilane thin films, fabricated via self-assembly by casting neat silane reagents onto hydrophilic SiO_x/Si substrates in the ambient. This drop-casting method is simple, yet rarely studied for the production of silane self-assembled monolayers (SAMs). Various ex-situ techniques were utilized to systematically characterize the growth process: Ellipsometry measurements can monitor the evolution of film thickness with silanization time; water droplet contact angle measurements reveal the wettability; the change of surface morphology was followed by Atomic Force Microscopy; the chemical identity of the films was verified by Infrared-Visible Sum Frequency Generation spectroscopy. We show that the shorter carbon chain (propyl-) or branched (2-(diphenylphosphino)ethyl-) silane SAMs exhibit poor ordering. In contrast, longer carbon chain (octadecyl and decyl) silanes form relatively ordered monolayers. The growth of the latter two cases shows Langmuir-like kinetics and a transition process from lying-down to standing-up geometry with increasing coverage.