Direct limit analysis based topology optimization of foundations

Topology optimization of foundation structures is conducted using a direct limit analysis based optimization approach. Originally developed for plastic topology design of 2D superstructures and industrial structures, which are traditionally designed based on elasticity, the direct limit analysis based design method demonstrated strong intrinsic properties that make of it a promising alternative for topology design. Unlike existing methods the one proposed here is fundamentally conceived and developed in the framework of direct plastic limit analysis which is the natural and usual known framework for the analysis and design of geotechnical structures. The method is extended to handle foundation design by providing for the simultaneous presence of two materials: the soil and the reinforcement, governed by Coulomb failure law. Two types of designs are considered, namely, continuous and discrete. The first allows a range of graded densities of reinforcement that may in practice represent the types of mixtures used in soil improvement, such as cementation. In the discrete design the reinforcement consists exclusively of solid structural elements. A series of two dimensional example problems demonstrate the capabilities of the method to generate rational classical designs or uncommon but intuitively sound foundation configurations that could inspire designers to develop novel solutions.     

Analysis of a discrete time table polling system with MAP input and time‐limited service discipline

An iterative procedure based on the MAP/PH/1 and MAP/PH/1/K queues with vacation is presented for approximating the performance measures of a table polling system. Each queue has a time limit after which it relinquishes the server. This is formally known as the token holding time (THT) in IEEE 802.5 and IEEE 802.4 standards. The polling table can be tailored such that queues with limits on the cycle time are visited more frequently, thus, limiting the delays for real time applications. The visit period and vacation period distributions were obtained based on the properties of the discrete phase distribution. Several examples are presented and they show that the algorithm converges fairly fast and gives reasonable results. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and In Silico Docking of New Pyrazolo[4,3-e]pyrido[1,2-a]pyrimidine-based Cytotoxic Agents

To explore a new set of anticancer agents, a novel series of pyrazolo[4,3-e]pyrido[1,2-a]pyrimidine derivativeshave been designed and synthesized viacyclocondensation reactions of pyrazolo-enaminone with a series of arylidenemalononitriles; compound 5 was obtained from 5-amino-4-cyanopyrazole. The structures of the target compounds were investigated by spectral techniques and elemental analysis (IR, UV–Vis, ¹H NMR, ¹³C NMR and ESI-MS). All compounds were evaluated for their in vitro cytotoxicity employing a panel of different human tumor cell lines, A375, HT29, MCF7, A2780, FaDu as well as non-malignant NIH 3T3 and HEK293 cells. It has been found that the pyrazolo-pyrido-pyrimidine analog bearing a 4-Br-phenyl moiety was the most active toward many cell lines with EC₅₀ values ranging between 9.1 and 13.5 µM. Moreover, in silico docking studies of the latter with six anticancer drug targets, i.e., DHFR, VEGFR2, HER-2/neu, hCA-IX, CDK6 and LOX5, were also performed, in order to gain some insights into their putative mode of binding interaction and to estimate the free binding energy of this bioactive molecule.     

Alfa fiber/polypropylene composites: Influence of fiber extraction method and chemical treatments

Alfa fiber/polypropylene composites were manufactured using twin-screw extrusion. Fibers were extracted using alkaline and steam explosion methods. Three chemical treatments were also applied to the alkaline-extracted fibers: stearic acid (SA), and potassium permanganate dissolved in water (KW) and in acetone (KA). Finally, thermal annealing was applied to the composites. The results indicate that composites with steam-exploded fibers had a significantly higher melt flow index than composites with alkaline-extracted fibers. Moreover, the incorporation of fibers into the matrix increased the Young's modulus, where the optimum results were obtained utilizing the alkaline-extracted fibers. Both extraction methods also significantly decreased the water uptake, especially the steam explosion. The three chemical treatments increased the melt flow index and conversely decreased the tensile strength and Young's modulus. In addition, KW treatment decreased the water uptake. Finally, thermal annealing increased the tensile strength and Young's modulus of composites with SA-treated fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47392.     

Effect of mechanical activation on the structure and ferroelectric property of Na0.5K0.5NbO3

Mechanical activation synthesis of Na_0.5K_0.5NbO₃ (NKN) was studied in order to explore the effect of mechanochemical interaction on the crystal structure and microstructure of NKN powder and ceramic. A single phase, nanocrystalline perovskite NKN powder has been derived from a mixture of oxide/carbonates via a mechanical activation route with heating at an elevated temperature. With the increase in milling time, the distortion of orthorhombic structure for NKN was weakened and the cell volume of NKN powder slightly decreased. The relative density and remnant polarization of NKN ceramics were improved, and the grain became uniform and smaller for prolonged milling NKN. The developed method is well suited for the production of NKN nanocrystallite powders and refined grain NKN ceramics.     

Incentive edge caching in software‐defined internet of vehicles: A Stackelberg game approach

In this paper, we investigate an incentive edge caching mechanism for an internet of vehicles (IoV) system based on the paradigm of software‐defined networking (SDN). We start by proposing a distributed SDN‐based IoV architecture. Then, based on this architecture, we focus on the economic side of caching by considering competitive cache‐enablers market composed of one content provider (CP) and multiple mobile network operators (MNOs). Each MNO manages a set of cache‐enabled small base stations (SBS). The CP incites the MNOs to store its popular contents in cache‐enabled SBSs with highest access probability to enhance the satisfaction of its users. By leasing their cache‐enabled SBSs, the MNOs aim to make more monetary profit. We formulate the interaction between the CP and the MNOs, using a Stackelberg game, where the CP acts first as the leader by announcing the popular content quantity that it which to cache and fixing the caching popularity threshold, a minimum access probability under it a content cannot be cached. Then, MNOs act subsequently as followers responding by the content quantity they accept to cache and the corresponding caching price. A noncooperative subgame is formulated to model the competition between the followers on the CP's limited content quantity. We analyze the leader and the follower's optimization problems, and we prove the Stackelberg equilibrium (SE). Simulation results show that our game‐based incentive caching model achieves optimal utilities and outperforms other incentive caching mechanisms with monopoly cache‐enablers whilst enhancing 30% of the user's satisfaction and reducing the caching cost.     

Application of a Possibilitic-Based Approach to Mobile Robotics

Possibility theory offers a nice setting for information combination or data fusion. This attractiveness arises from the elastic constraints that govern the basic concepts pertaining to this theory. Consequently, many combination modes are available ranging from the conjunctive to the disjunctive passing through the compromise mode. Therefore the problem of what is the suitable combination mode for a given situation is still open. The adaptive rule proposed by Dubois and Prade contributes partly to this problem, and has been successfully employed in several applications like robotics. In this paper we apply the recently new combination rule referred to as progressive rule, which permits us to handle robustness with respect to shape modelling and takes account for a possible presence of erroneous information, to mobile robotics context. The rule explicitly accounts for the distance between each alternative and the consensus zone. The rule is then incorporated into a general scheme of fusion methodology, which allows a transformation of raw inputs into meaningful and homogeneous information that will be refined by the progressive rule. A robotics application corresponding to mobile robot localization in a structured environment is carried out. The feasibility of the possibilistic approach is demonstrated by a comparison with a standard method based on Kalman filter.     

A distributed detection and prevention scheme from malicious nodes in vehicular networks

Vehicular environments still remain vulnerable to various potential attacks because of continuous interactions and information exchange between vehicles despite the deployment of authentication techniques by communication standards. Therefore, an authenticated node with a certificate could initiate an attack while complying with implemented protocols. Some mechanisms were proposed to enhance communication technologies, but none of them was able to anticipate nodes' behavior. They also mismanage oscillating vehicles, because they evict them automatically after misbehaving. In this paper, we propose a preventive mechanism, namely, Intrusion Prevention and Detection System (IPDS), able to predict vehicles behavior. This mechanism is based on a Kalman filter to predict the future vehicles' behavior and classify them into three categories (white, gray, and black) based on their expected trustworthiness. The main concerns of this work are to prevent from various attacks, namely, DoS, false alert, and Sybil, and deal with oscillating vehicles. Therefore, IPDS treats these latter in a different way where they are introduced into a gray list and used for routing purposes until they persist in their attacks. Simulations performed using ns3 simulator highlight IPDS accuracy regarding the detection rate of malicious nodes and its good impact on the network applications performances. Copyright © 2016 John Wiley & Sons, Ltd.     

基于动态贝叶斯网络的听视觉融合情感识别

在多媒体领域的研究中,对听视觉情感识别,如何融合听视觉情感信息是关键问题.传统的融合方法采用状态同步多流隐马尔可夫模型(Syn_AVHMM),但忽略了音视频情感信息之间的异步关系,从而影响识别结果.为了对听视觉情感信息之间的关联和异步关系进行更准确的描述,提出了一种听视觉状态可以异步,加入异步程度可控的多流动态贝叶斯网络情感识别模型(Asy_DBN),并在 eNERFACE'05 听视觉情感数据库上进行了情感识别实验.实验结果表明,通过调整听视觉状态流之间的异步约束,Asy-DBN 模型可以得到最好的识别结果,六种情感的平均识别率比马尔可夫模型高出 9.88%,为实际应用提供了依据.