Particle Swarm Optimization inspired by starling flock behavior

Swarm intelligence is a meta-heuristic algorithm which is widely used nowadays for efficient solution of optimization problems. Particle Swarm Optimization (PSO) is one of the most popular types of swarm intelligence algorithm. This paper proposes a new Particle Swarm Optimization algorithm called Starling PSO based on the collective response of starlings. Although PSO performs well in many problems, algorithms in this category lack mechanisms which add diversity to exploration in the search process. Our proposed algorithm introduces a new mechanism into PSO to add diversity, a mechanism which is inspired by the collective response behavior of starlings. This mechanism consists of three major steps: initialization, which prepares alternative populations for the next steps; identifying seven nearest neighbors; and orientation change which adjusts velocity and position of particles based on those neighbors and selects the best alternative. Because of this collective response mechanism, the Starling PSO explores a wider area of the search space and thus avoids suboptimal solutions. We tested the algorithm with commonly used numerical benchmarking functions as well as applying it to a real world application involving data clustering. In these evaluations, we compared Starling PSO with a variety of state of the art algorithms. The results show that Starling PSO improves the performance of the original PSO and yields the optimal solution in many numerical benchmarking experiments. It also gives the best results in almost all clustering experiments.     

Semantics for consistent activation in context-oriented systems

ContextContext-oriented programming languages provide dedicated programming abstractions to define behavioral adaptations and means to combine those adaptations dynamically according to sensed context changes. Some of these languages feature programming abstractions to explicitly define interaction dependencies among contexts. However, the semantics of context activation and the meaning of dependency relations have been described only informally, which in some cases has led to incorrect specifications, faulty implementations and inconsistent system behavior.ObjectiveWith the aim of avoiding faulty implementations and inconsistencies during system execution, this paper proposes both a formal and run-time model of contexts, context activation and context interaction.MethodAs a formal and computational basis, we introduce context Petri nets, a model based on Petri nets, which we found to match closely the structure of contexts in context-oriented systems. The operational semantics of Petri nets permits the modeling of run-time context activations. Existing Petri net analyses allow us to reason about system properties. As validation, we carried out small and medium-sized case studies.ResultsIn the cases explored, context Petri nets served effectively as underlying run-time model to ensure that declared context interaction constraints remain consistent during context manipulation. Moreover, context Petri nets enabled us to analyze certain properties regarding the activation state of particular contexts.ConclusionContext Petri nets thus proved to be appropriate to encode and manage the semantics of context activation, both formally and computationally, so as to preserve the consistency of context-oriented systems.     

Nonlinear dynamic behaviors and control based on simulation of high-purity heat integrated air separation column

In this paper, the dynamic behaviors on the basis of simulation for high-purity heat integrated air separation column (HIASC) are studied. A nonlinear generic model control (GMC) scheme is proposed based on the nonlinear behavior analyses of a HIASC process, and an adaptive generic model control (AGMC) scheme is further presented to correct the model parameters online. Related internal model control (IMC) scheme and multi-loop PID (M-PID) scheme are also developed as the comparative base. The comparative researches are carried out among these linear and nonlinear control schemes in detail. The simulation research results show that the proposed AGMC schemes present advantages in both servo control and regulatory control for the high-purity HIASC.     

基于关联规则的网络行为分析

网络用户访问网站的过程中,产生了大量的用户浏览网页的相关记录,隐含着用户在上网过程中的行为习惯。但其中潜在的用户信息难以发现。因此,急需有效的方法提取这些数据中的信息,数据挖掘应用而生。其中,关联规则技术是应用广泛的技术之一。文中利用Apriori算法对Web结构数据进行关联规则挖掘,所得到的规则反映出页面之间的链接关系。分析挖掘结果可得到用户访问的行为规律,为相关网站的安全性和优化改进提供有效的决策依据。     

Design,analysis, and neural control of a bionic parallel mechanism

Frontiers of Mechanical Engineering - Although the torso plays an important role in the movement coordination and versatile locomotion of mammals, the structural design and neuromechanical control...     

Absence of surface flaking in hierarchical glass-ceramic coating: High impact resistant ceramic tiles

The impact resistance method is a useful procedure to determine the tile resistance. While other works are focused on modifying the tile support to improve the impact resistance, in this work, a new glass-ceramic material was developed to used it as glaze coating in order to relax impact tensions. This material possesses a hierarchical nano-microstructure consisted of microcrystal surrounded by nanostructured regions having low glassy phase, which is considered responsible for tension relaxations. The resilience coefficient measured in conventional and glass-ceramic glazes presents little differences (0.85–0.88). However, impact damages on the surface is totally inhibited for glass-ceramic coating while the conventional one suffers great flaking. These damages were analyzed by Optical profilometry and FESEM to compare the impact resistance and to correlate it with its microstructure. The results confirm that the micro-nanostructured coating paves the way to improve impact resistance in ceramic materials where surface damage is a critical parameter.     

Does thermal control improve visual satisfaction? Interactions between occupants’ self-perceived control,visual, thermal,and overall satisfaction

Occupants’ satisfaction had been researched independently related to thermal and visual stimuli for many decades showing among others the influence of self-perceived control. Few studies revealed interactions between thermal and visual stimuli affecting occupant satisfaction. In addition, studies including interactions between thermal and visual stimuli are lacking different control scenarios. This study focused on the effects of thermal and visual factors, their interaction, seasonal influences, and the degree of self-perceived control on overall, thermal, and visual satisfaction. A repeated-measures laboratory study with 61 participants running over two years and a total of 986 participant sessions was conducted. Mixed model analyses with overall satisfaction as outcome variable revealed that thermal satisfaction and visual satisfaction are the most important predictors for overall satisfaction with the indoor environment. Self-perceived thermal control served as moderator between thermal satisfaction and overall satisfaction. Season had slight influence on overall satisfaction. Random effects explained the highest amount of variance, indicating that intra- and interindividual differences in the ratings of satisfaction are more prevalent than study condition. Future building design and operation plans aiming at a high level of occupant satisfaction should consider personal control opportunities and take into account the moderating effect of control opportunities in multimodal interactions.     

Preparation and the effects of ion irradiation on bulk SiOC ceramics

Bulk SiOC ceramics were prepared by spark plasma sintering of polymer-derived SiOC powders, and the effects of ion irradiation on their microstructures and properties were investigated in detail. High sintering temperature was conducive to low open porosity, high bulk density, nucleation and growth of β-SiC nanodomains, and graphitization of free carbon clusters in the SiOC ceramics. Ordering of the nanodomanins is beneficial for improving hardness and modulus of the ceramics. After 70 keV He ion irradiations, the β-SiC nanocrystals and graphitic clusters were partially amorphized, and their average grain size decreased by 13.6% and 50.9%, respectively. But no bubbling or peeling occurred on the irradiated sample surface, the hardness and modulus barely changed, indicating the SiOC ceramics are promising as radiation-tolerant materials.     

Reaction synthesis of spark plasma sintered MoSi2-B4C coatings for oxidation protection of Nb alloy

MoSi₂-B₄C coatings with different B₄C contents were prepared on Nb alloy by spark plasma sintering (SPS) process. Powder mixtures of Mo, Si and B₄C were used as the coating starting materials. Besides MoSi₂ and B₄C phases, small amounts of SiC and MoB are also found in the coatings because of the reactions of Mo, Si and B₄C powders during sintering. Compared with single MoSi₂ coating, the MoSi₂-B₄C coatings show better oxidation resistance at 1450?℃, and dense B₂O₃-SiO₂ oxide scales form after 100?h oxidation. The B₄C or MoB in the MoSi₂-B₄C coatings can serve as the B donor for the formation of B₂O₃. A slight degradation in the microstructure of the MoSi₂-B₄C coatings after oxidation is observed, which can be attributed to the presence of an NbB layer in the inter-diffusion zone of the coatings that retards the inward diffusion of Si from the coating into the substrate alloy. The microstructure development and oxidation behavior of the MoSi₂-B₄C coatings have been discussed.