On computing the stabilizing solution of a class of discrete‐time periodic Riccati equations

This paper addresses the problem of solving a class of periodic discrete‐time Riccati equation with an indefinite sign of its quadratic term. Such an equation is closely related to the so‐called full‐information H _∞ control of discrete‐time periodic systems. A globally convergent iterative algorithm with a local quadratic convergence rate is proposed for this purpose. An application to the problem of H _∞ filtering of discrete‐time periodic systems is also developed and illustrated via a numerical example. Copyright © 2013 John Wiley & Sons, Ltd.     

Self‐oscillating mixer using six port power divider

A self‐oscillating mixer (SOM) that uses a six port microstrip power divider is presented in this article. The oscillation and mixing functions are executed using a pair of identical GaAs field effect transistors. The power division and combination of the RF and local oscillator (LO) signals involved in the operation are implemented using the six port network. The RF input port of the proposed SOM is totally isolated from the operation of the LO which is a desirable feature in many applications. The proposed structure can work as a stand‐alone oscillator with a frequency of 4.71 GHz and a power level of 16.1 dBm. When fed with a RF signal, the proposed structure becomes a fully functional SOM exhibiting a conversion gain of 5.2 dBm. The simulation and measurement results of the proposed SOM are presented to validate the design concept. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:269–276, 2015.     

Enhanced DHT-based P2P Architecture for Effective Resource Discovery and Management

Recently, Peer-to-Peer (P2P) has become a popular paradigm for building distributed systems, aiming to provide resource localization and sharing in large-scale networks. However, advanced searching for resources remains an open issue. The flooding technique used by some P2P systems is expensive in bandwidth usage, and shows a serious lack in scalability. Also, more efficient systems based on distributed hash tables (DHT) lack in query expressiveness and flexibility. This paper addresses this issue by discussing existing solutions, and proposing a novel approach to support advanced multi-keyword queries in the context of P2P systems. It extends the existing, and widely established DHT-based localization frameworks. This new approach provides an effective resource localization framework; it can substantially reduce bandwidth consumption and improve load balancing over the network. Moreover, various kinds of applications can be deployed on top of this generic framework. As a relevant use case, this paper describes a novel service discovery and management application.

Three-dimensional face recognition using shapes of facial curves

We study shapes of facial surfaces for the purpose of face recognition. The main idea is to 1) represent surfaces by unions of level curves, called facial curves, of the depth function and 2) compare shapes of surfaces implicitly using shapes of facial curves. The latter is performed using a differential geometric approach that computes geodesic lengths between closed curves on a shape manifold. These ideas are demonstrated using a nearest-neighbor classifier on two 3D face databases: Florida State University and Notre Dame, highlighting a good recognition performance     

An Iterative local-search framework for solving constraint satisfaction problem

In this article, we introduce a new solving framework based on using alternatively two local-search algorithms to solve constraint satisfaction and optimization problems. The technique presented is based on the integration of local-search algorithm as a mechanism to diversify the search instead of using a build on diversification mechanisms. Thus, we avoid tuning the multiple parameters to escape from a local optimum. This technique improves the existing methods: it is generic especially when the given problem can be expressed as a constraint satisfaction problem. We present the way the local-search algorithm can be used to diversify the search in order to solve real examination timetabling problems. We describe how the local-search algorithm can be used to assist any other specific local-search algorithm to escape from local optimality. We showed that such framework is efficient on real benchmarks for timetabling problems.     

Evaluation of hexahedral, prismatic and hybrid mesh styles for simulating respiratory aerosol dynamics

In simulating biofluid flow domains, structured hexahedral meshes are often associated with high quality solutions. However, extensive time and effort are required to generate these meshes for complex branching geometries. This study evaluates potential mesh configurations that may maintain the advantages of the structured hexahedral style while providing significant savings in grid construction time and complexity. Specifically, the objective of this study is to evaluate the performance of unstructured hexahedral, prismatic and hybrid meshes based on grid convergence and local particle deposition fractions in a bifurcating model of the respiratory tract. A grid convergence index (GCI) has been implemented to assess the mesh-independence of solutions in cases where true grid halving is not feasible. Localized and total deposition values have been evaluated for particles ranging from 1 through 10 μm in planar and out-of-plane geometries. Structured hexahedral, unstructured hexahedral and prismatic meshes were found to provide GCI values of approximately 5% and nearly identical velocity fields. In contrast, the hexahedral-tetrahedral hybrid model resulted in GCI values that were significantly higher in comparison to the other meshes. The resulting velocity field for the hybrid configuration differed from the hexahedral and prismatic solutions by up to an order of magnitude at some locations. Considering the deposition of 10 μm particles in the planar configuration, all meshes considered provided relatively close agreement (2-20% difference) with an available experimental study. For all particle sizes considered, local and total deposition results for the structured and unstructured hexahedral meshes were similar. In contrast, the prismatic and hybrid geometries resulted in significantly higher deposition rates when compared to the hexahedral meshes for particles less than 10 μm. As a result, only the unstructured hexahedral mesh was found to provide overall performance similar to the structured hexahedral configuration with the advantage of a significant savings in construction time. These results emphasize the importance of aligning control volume gridlines with the predominant flow direction in biofluid applications that involve long and thin internal flow domains. Future studies are needed to assess other forms of the hybrid configuration and the effects of other element styles.     

A Model for Minimizing Active Processor Time

We introduce the following elementary scheduling problem. We are given a collection of n jobs, where each job J _i has an integer length ? _i as well as a set T _i of time intervals in which it can be feasibly scheduled. Given a parameter B, the processor can schedule up to B jobs at a timeslot t so long as it is “active” at t. The goal is to schedule all the jobs in the fewest number of active timeslots. The machine consumes a fixed amount of energy per active timeslot, regardless of the number of jobs scheduled in that slot (as long as the number of jobs is non-zero). In other words, subject to ? _i units of each job i being scheduled in its feasible region and at each slot at most B jobs being scheduled, we are interested in minimizing the total time during which the machine is active. We present a linear time algorithm for the case where jobs are unit length and each T _i is a single interval, assuming that jobs are given in sorted order. For general T _i , we show that the problem is NP-complete even for B=3. However when B=2, we show that it can be efficiently solved. In addition, we consider a version of the problem where jobs have arbitrary lengths and can be preempted at any point in time. For general B, the problem can be solved by linear programming. For B=2, the problem amounts to finding a triangle-free 2-matching on a special graph. We extend the algorithm of Babenko et al. (Proceedings of the 16th Annual International Conference on Computing and Combinatorics, pp. 120–129, 2010) to handle our variant, and also to handle non-unit length jobs. This yields an \(O(\sqrt{L} m)\) time algorithm to solve the preemptive scheduling problem for B=2, where L=∑ _i ? _i . We also show that for B=2 and unit length jobs, the optimal non-preemptive schedule has active time at most 4/3 times that of the optimal preemptive schedule; this bound extends to several versions of the problem when jobs have arbitrary length.     

IIR内胎 第1部分 配方设计

ＩＲ内胎第１部分配方设计埃克森化工公司ＳａｍｉｒＭａｊｕｍｄａｒ著涂学忠摘译ＩＩＲ的历史可以追溯到１９世纪７０年代，当时Ｇｏｒｉａｎｏｖ和Ｂｕｔｌｅｒｏｖ以及后来的Ｏｔｏ（１９２７年）在存在三氟化硼和硫酸的室温条件下聚合异丁烯，得到了低相对分子质量的...     

Synthesis,characterization, and antimicrobial activity of acrylic copolymers

2,4‐Dichlorophenyl methacrylate (2,4‐DMA) and vinyl acetate (VAc) were copolymerized with different feed ratios using dimethyl formamide (DMF) as a solvent and 2,2′‐azobisisobutyronitrile (AIBN) as an initiator at 70°C. The copolymers were characterized by infrared (IR) spectroscopy. Copolymer compositions were determined by ultraviolet (UV) spectroscopy. The monomer reactivity ratios were evaluated by the Fineman–Ross method. Average molecular weight and polydispersity index were determined by gel permeation chromatography (GPC), and the intrinsic viscosities of polymers were also discussed. Thermogravimetric analyses of polymers were carried out under a nitrogen atmosphere. The homo‐ and copolymers were tested for their antimicrobial activity against selected microorganisms. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 895–900, 2003     

Conducting polymer gel: formation of a novel semi-IPN from polyaniline and crosslinked poly(2-acrylamido-2-methyl propanesulphonicacid)

In the present article, a simple two-step technique for synthesis of electrically conducting hydrogel is described. The synthesized hydrogel is originally a semi-interpenetrating polymer network (IPN) in which conducting polyaniline (linear) is entrapped within a crosslinked polyelectrolyte gel viz. poly(2-acrylamido-2-methyl propane sulphonic acid) (PAMPS). A conventional photo-polymerization technique was followed for synthesis of the PAMPS gel while aniline is in situ polymerized within the gel, giving rise to the desired semi-IPN. For comparison, a neutral gel based semi-IPN PAn-PAAm (polyaniline-polyacrylamide) was also prepared following the similar route. PAn imparts appreciable electrical conductivity to both PAMPS and PAAm based gels without hampering their existing properties that indicates the success of the work. Synthesis of the gel was studied in detail and different experimental conditions were optimized. Different physical properties of the gel viz. its degree of swelling, electrical conductivity, mechanical strength, etc were also studied. The resultant semi-IPN or the composite hydrogel was found to possess appreciable electrical conductivity, good swellability and mechanical strength. The electro-driven volume contraction of the composite gel was found to occur at sufficiently lower voltage compared to the pure PAMPS gel, which indicates its promising application aspect in fabrication of chemomechanical devices.