Robust guaranteed cost ILC with dynamic feedforward and disturbance compensation for accurate PMSM position control

This contribution presents a robust ILC control design based on guaranteed costs. By combining this ILC design with dynamic feedforward control and an observer-based disturbance compensation, the initial tracking errors in an early learning stage can be reduced. The benefits of the proposed design approach are pointed out at the example of a robust position control of a Permanent Magnet Synchronous Motor (PMSM), which is subject to uncertain model parameters. The paper is concluded with convincing experimental results from a dedicated test rig. Moreover, a comparison with a classical observer-based tracking control is provided.     

Computational study to understand the energy transfer pathways within amicyanin

Vibrational energy diffusivities between the residues present in Amicyanin copper protein are calculated and presented in form of communication map. From those results energy flow pathways from the copper metal ion to the inter protein residue Glu31 are identified. Our finding suggests many different pathways are possible and copper metal ion in oxidized and reduced state switches the pathways. Our finding also suggests the cooperative nature of surrounding residues and water molecules towards selecting the pathways. The major transport channels in the oxidised state are, Cu²⁺---> MET28---> LYS29---> TYR30---> GLU31 and Cu²⁺---> MET98---> TYR30--- > GLU31. And in the reduced state Cu⁺---> CYS9---> TYR30---> GLU31 and Cu⁺---> MET28---> LYS2---> TYR30---> GLU31. We studied further the interaction energies between the copper ion and neighbouring residues using B3LYP/QZVP method. Both the methods complement each other in predicting the energy flow pathways and the cooperative nature of residues.     

Using self-organizing maps to model turnover of sales agents in a call center

This paper proposes an approach for modeling employee turnover in a call center using the versatility of supervised self-organizing maps. Two main distinct problems exist for the modeling employee turnover: first, to predict the employee turnover at a given point in the sales agent's trial period, and second to analyze the turnover behavior under different performance scenarios by using psychometric information about the sales agents. Identifying subjects susceptible to not performing well early on, or identifying personality traits in an individual that does not fit with the work style is essential to the call center industry, particularly when this industry suffers from high employee turnover rates. Self-organizing maps can model non-linear relations between different attributes and ultimately find conditions between an individual's performance and personality attributes that make him more predisposed to not remain long in an organization. Unlike other models that only consider performance attributes, this work successfully uses psychometric information that describes a sales agent's personality, which enables a better performance in predicting turnover and analyzing potential personality profiles that can identify agents with better prospects of a successful career in a call center. The application of our model is illustrated and real data are analyzed from an outbound call center.     

A time-varying transfer function for balancing the exploration and exploitation ability of a binary PSO

Many real-world problems belong to the family of discrete optimization problems. Most of these problems are NP-hard and difficult to solve efficiently using classical linear and convex optimization methods. In addition, the computational difficulties of these optimization tasks increase rapidly with the increasing number of decision variables. A further difficulty can be also caused by the search space being intrinsically multimodal and non-convex. In such a case, it is more desirable to have an effective optimization method that can cope better with these problem characteristics. Binary particle swarm optimization (BPSO) is a simple and effective discrete optimization method. The original BPSO and its variants have been used to solve a number of classic discrete optimization problems. However, it is reported that the original BPSO and its variants are unable to provide satisfactory results due to the use of inappropriate transfer functions. More specifically, these transfer functions are unable to provide BPSO a good balance between exploration and exploitation in the search space, limiting their performances. To overcome this problem, this paper proposes to employ a time-varying transfer function in the BPSO, namely TV_T-BPSO. To understand the search behaviour of the TV_T-BPSO, we provide a systematic analysis of its exploration and exploitation capability. Our experimental results demonstrate that TV_T-BPSO outperforms existing BPSO variants on both low-dimensional and high-dimensional classical 0–1 knapsack problems, as well as a 200-member truss problem, suggesting that TV_T-BPSO is able to better scale to high dimensional combinatorial problems than the existing BPSO variants and other metaheuristic algorithms.     

圆柱绕流气动噪声数值分析

为了快速预测刚性圆柱绕流的气动噪声,研究了一种将离散涡方法(DVM)和涡声理论结合起来计算低马赫数、高雷诺数流场气动噪声的方法。首先用Oseen粘性涡模型改进了离散涡方法并模拟了圆柱绕流,分析结果与实际情况相符。根据流场计算的结果,应用涡声理论进一步计算了远场的声压。测点的总声压级与实验值及其他数值计算结果都比较吻合。最后绘制了声场的指向性特性曲线,表明圆柱绕流声场明显的偶极子特性。     

基于CSSCI数据库的中国传统村落研究知识图谱分析

目的 随着研究者们对中国传统村落的深透研究,涌现出了大量的相关研究文献,为了能够更好地把握其发展动向。方法 以信息可视化软件Citespace为研究工具,将1998年至2017年间 CSSCI数据库中有关传统村落研究的253条文献作为研究对象,制作并分析近20年间我国传统村落文献共被引图谱、期刊共被引图谱、作者共被引图谱以及关键词&主题词共现图谱。使用Citespace绘制出的图谱可以很明显地看出我国传统村落的研究前沿、与研究相关的范畴和重要文献、该领域具有影响力的作者及其研究的热门要点。结论 研究表明：在研究的方法和视角上包含多个学科交叉的特点,研究对象由单一转为多元化,更深入地挖掘和剖析了研究内容;在CSSCI数据库中对Citespace软件分析出的前5位高被引作者,以“传统村落”、“古村落”、“传统聚落”和“历史文化名村”为关键词进行检索、整理和分析,挖掘文章的优势,对文章中的不足进行剖析;“古村落的保护发展与传承”、“历史文化遗产的多重价值与可持续发展路径”、“景观规划和活化机理”等成为热点研究领域,以传统村落综述研究的角度与手法,对以后的研究人员更好地了解传统村落领域的前景有一定的参照、借鉴意义。     

Comprehensive numerical modelling of the hot isostatic pressing of Ti-6Al-4V powder: From filling to consolidation

Hot Isostatic Pressing (HIP) is a manufacturing process for production of near-net-shape components, where models based on Finite Element Method (FEM) are generally used for reducing the expensive experimental trials for canister design. Researches up to date implement in the simulation a uniform powder relative density distribution prior HIPping. However, it has been experimentally observed that the powder distribution is inhomogeneous after filling, leading to a non-uniform tool shrinkage. In this study a comprehensive numerical model for HIPping of Ti-6Al-4V powder is developed to improve model prediction by simulating powder filling and pre-consolidation by means of a two-dimensional Discrete Element Method (DEM). Particles’ dimension has been scaled up in order to reduce the computational cost of the analysis. An analytical model has been developed to calculate the relative density distribution from powder particle distribution provided by DEM, which is then passed in information to a three-dimensional FEM implementing the Abouaf and co-workers model for simulating powder densification during HIPping. Results obtained implementing the initial relative density distribution calculated from DEM are compared with those obtained considering a uniform relative density distribution over the powder domain (classic approach) at the beginning of the analysis. Experimental work has been carried out for validating the DEM (filling) and FEM (HIP) model. Comparison between experimental and numerical results shows the ability of the DEM model to represent the powder flow during filling and pre-consolidation, providing also a reliable values of the relative density distribution. It also highlights that taking into account the non-uniform powder distribution inside the canister prior HIP is vital to improve numerical results and produce near-net-shape components.     

一种基于知识地图集的知识管理系统模型框架

在分析知识管理、知识管理系统(KMS)的含义和知识地图集技术的特点的基础上，提出了一种基于知识地图集的KMS模型框架，并且分析了该模型框架中知识地图集的组成及功能，讨论了KMS中知识地图集和知识存储之间的关系。依据该模型框架，组织易于构建知识管理系统，实现知识资源的共享与充分运用。最后，通过一个实例分析进一步说明了该模型框架的应用。     

Static and low-velocity impact behavior of sandwich beams with closed-cell aluminum-foam core in three-point bending

In this paper, the response and failure of sandwich beams with aluminum-foam core are investigated. Quasi-static and low-velocity impact bending tests are carried out for sandwich beams with aluminum-foam core. The deformation and failure behavior is explored. It is found that the failure mode and the load history predicted by a modified Gibson's model agree well with the quasi-static experimental data. The failure modes and crash processes of beams under impact loading are similar to those under quasi-static loading, but the force-displacement history is very different. Hence the quasi-static model can also predict the initial dynamic failure modes of sandwich beams when the impact velocity is lower than 5 m/s.     

一种非结构环境下多机器人构建地图的方法

提出了一种多移动机器人在非结构环境下构建地图的新方法.该方法让各机器人独立探索环境并对不同的局部栅格地图予以融合.在地图融合过程中,无需考虑机器人相对位置的先验信息,而是以栅格地图相似度为度量标准,利用距离变换和改进的遗传算法高效、快速地搜索各局部地图之间的最大重叠部分,进而予以融合.实验结果表明,与常规方法相比,该方法能够较为精确地实现非结构环境下多机器人地图构建,且限制条件少,更适合于实际应用中的各种复杂情况.