Modelling Bonded Shape Memory Alloy Vibration Attenuators Elements Using the Finite-Element Method

Shape memory alloys (SMAs) present the capability to develop large forces and displacements with low power consumption. Due their special characteristics, SMAs have been used in many different applications. Pseudoelastic hysteresis loop observed in austenitic SMAs is associated with energy dissipation. Therefore, pseudoelastic SMA elements can be used as vibration attenuators. Joining methods present some technological challenges for the use of these elements. Welding can strongly affect the properties of the alloy. Mechanical joints using rivets and screws are commonly used but promote stress concentration effects. The use of adhesives offers some benefits, being an alternative to be investigated. This work presents a numerical model based on the finite-element method and experimental procedures to study the behaviour of bonded vibration attenuators with SMA elements. The proposed model considers the pseudoelastic behaviour of SMA elements, and a cohesive zone model was used to study the union between absorber and an aluminium plate. Finally, several loading conditions were analysed with the proposed models to assess the capability of bonded pseudoelastic SMA elements to dissipate energy. The proposed geometry allows the elements to actuate as an efficient vibration attenuator, in particular when submitted to axial loading.     

Filter & hold: a mixed continuous‐/discrete‐time technique for time‐constant scaling

The work reported in this paper introduces a periodic switching technique applied to continuous‐time filters, whose outcome is an equivalent filter with scaled time‐constants. The principle behind the method is based on a procedure that extends the integration time by periodically interrupting the normal integration of the filter. The net result is an up scaling of the time constant, inversely proportional to the switching duty‐cycle. This is particularly suitable for reducing the area occupied by passive devices in integrated circuits, as well as to accurately calibrate the filter dynamics. Previous works have been following this concept in an entirely continuous‐time perspective, either focusing on specific circuits or using approximations to provide an extended analysis. This paper includes input/output sampling to derive a closed‐form representation for the scaling technique herein coined as ‘Filter & Hold’ (F&H). A detailed mathematical analysis is described, demonstrating that the F&H concept represents an exact filtering solution. Simulation results and experimental measurements are provided to further validate the theoretical analysis for an F&H vector‐filter prototype. Copyright © 2014 John Wiley & Sons, Ltd.     

A lightweight framework for dynamic GUI data verification based on scripts

Runtime verification (RV) provides essential mechanisms to enhance software robustness and prevent malfunction. However, RV often entails complex and formal processes that could be avoided in scenarios in which only invariants or simple safety properties are verified, for example, when verifying input data in Graphical User Interfaces (GUIs). This paper describes S‐DAVER, a lightweight framework aimed at supporting separate data verification in GUIs. All the verification processes are encapsulated in an independent layer and then transparently integrated into an application. The verification rules are specified in separate files and written in interpreted languages to be changed/reloaded at runtime without recompilation. Superimposed visual feedback is used to assist developers during the testing stage and to improve the experience of users during execution. S‐DAVER provides a lightweight, easy‐to‐integrate and dynamic verification framework for GUI data. It is an integral part of the development, testing and execution stages. An implementation of S‐DAVER was successfully integrated into existing open‐source applications, with promising results. Copyright © 2015 John Wiley & Sons, Ltd.     

Analytical model for predicting friction in line contacts

This paper presents the development of an analytical model for the prediction of the friction coefficient in line contacts under thermal elastohydrodynamic lubrication (TEHL). A new theoretical equation is deduced for determining the friction coefficient, taking into account the rheology of common lubricants under TEHL. This approach also considers the heat generated and its penetration into the bulk of the contacting solids. Therefore, the increase in temperature and ensuing variations in the operating conditions are determined. In order to illustrate the use of the new model and verify its accuracy, an experimental stage is performed in a tribological test rig. The predictions of the proposed model are compared with the results obtained in the test rig and other data reported in the literature for diverse lubricants, showing a good agreement in every case. © 2015 The Authors Lubrication Science published by John Wiley & Sons Ltd.     

Evolution of a Transition State: Role of Lys100 in the Active Site of Isocitrate Dehydrogenase

An active site lysine essential to catalysis in isocitrate dehydrogenase (IDH) is absent from related enzymes. As all family members catalyze the same oxidative β‐decarboxylation at the (2R)‐malate core common to their substrates, it seems odd that an amino acid essential to one is not found in all. Ordinarily, hydride transfer to a nicotinamide C4 neutralizes the positive charge at N1 directly. In IDH, the negatively charged C4‐carboxylate of isocitrate stabilizes the ground state positive charge on the adjacent nicotinamide N1, opposing hydride transfer. The critical lysine is poised to stabilize—and perhaps even protonate—an oxyanion formed on the nicotinamide 3‐carboxamide, thereby enabling the hydride to be transferred while the positive charge at N1 is maintained. IDH might catalyze the same overall reaction as other family members, but dehydrogenation proceeds through a distinct, though related, transition state. Partial activation of lysine mutants by K⁺ and NH₄⁺ represents a throwback to the primordial state of the first promiscuous substrate family member.     

Project risk management methodology for small firms

We present a project management methodology designed for small businesses (SMEs), who need to run projects beyond their normal operations. These projects are critical to the survival of these organisations, such as the development of new products to adapt to the market or new legislation, management system implementations, etc. Very frequently, the managers of these projects are not project management professionals, so they need guidance to have autonomy, using minimal time and documentation resources. The risk management method outlined in this paper is based on extensive research with a large number (72) of Spanish companies. This new methodology considers the factors that are usually neglected by SMEs; i.e., project alignment with the company's strategy and results management. The methodology, based on project risk management, includes simple tools, templates and risk checklists with recommended actions and indicators. For validation it was tested in five different types of real projects (innovation, management systems and ICT implementation) of industrial and service companies with different characteristics.     

Systematic review: an analysis model for measuring the coopetitive performance in horizontal cooperation networks mapping the critical success factors and their variables

Several strategies have been developed for micro-enterprises and small enterprises in relation to their competitiveness enhancement. In recent years, one of the most widespread strategies has been the formation of horizontal cooperation networks (HCNs), based on the evolutionary development of coopetition. This study aimed to support and validates an analysis model developed by Petter (Modelo para análise da competitividade de redes de cooperação horizontais de empresas, Universidade Tecnológica Federal do Paraná, UTFPR, Ponta Grossa, 2012), in order to point out which are critical success factors (CSF), and their variables which influence the coopetition performance of a HCN under aspects of cooperation and competitiveness. A systematic review supported by Sampaio and Mancini (Revista Brasileira de Fisioterapia 11(1):83–89, 2007) was used to measure the status quo of published journals related to the subject, among several databases. A large informational gap was found concerning the development of methods and tools, as well as subsidies. Regarding the raise of publications found inside the scope, 18 CSF, 52 variables were mapped correlating them with 144 indicators, therefore, supporting and validating the proposed model of analysis.     

Spatial disparities in the European Union: an analysis of regional polarization

This paper examines the degree of polarization in the European Union regional per capita income distribution between 1977 and 1999 from several complementary perspectives. Specifically, we have combined a non-parametric analysis with the information provided by various polarization measures proposed by the literature on personal income distribution. The results reveal that the European regions tend to cluster into different per capita income classes during the study period. Nevertheless, the level of intra-distribution mobility is relatively low, especially in regions at the upper and lower ends of the distribution. In any event, regional polarization has decreased over time, as a consequence of various factors sometimes working in opposite directions. Additionally, the empirical evidence provided reveals that the geographical location of the various regions and the differences in their productivity levels, play a major role in explaining the polarization patterns observed in the European Union.     

鱼肌肉蛋白质组学分级过程的重现性研究

在比较蛋白质组学中,分级过程经常被用于去除高丰度蛋白质,从而提高低丰度蛋白质的浓度至检出限以上。作者为了证实在二维凝胶电泳分离流程中增加额外的分级过程将会减小对金头鲷宰前应激响应时间依赖检测中所引入的噪声和批次间的偏差,采用多维标度对结果数据进行了多参数分析。结果表明生物响应比分级引入的误差高出几个数量级,而批次间误差不小于不同IEF/SDS-PAGE运行所引入的偏差。     

Occurrence of the <Emphasis Type="Italic">cis</Emphasis>-4,7,10, <Emphasis Type="Italic">trans</Emphasis>-13-22:4 Fatty Acid in the Family Pectinidae (Mollusca: Bivalvia)

The present study aimed to elucidate the effective phylogenetic specificity of distribution of a cis-4,7,10, trans-13-22:4 (22:4(n-9)Δ13trans) among pectinids. For this purpose, we extended the analysis of membrane glycerophospholipids FA composition to 13 species of scallops, covering 11 genera and 7 tribes representatives of the three subfamilies Chlamydinae, Palliolinae and Pectininae and the subgroup Aequipecten. In species belonging to the subfamily Pectininae and the Aequipecten subgroup, 22:4(n-9)Δ13trans was found in substantial amounts, but it was absent in other species belonging to the subfamilies Chlamydinae and Palliolinae. Homologous non-methylene-interrupted (NMI) FA, also hypothesized to differ along phylogenetic lines in bivalves, were totally absent or present only in trace amounts in representatives of the Aequipecten subgroup but ranged from 0.3 to 4.5% of the total FA in Pectinidae, Chlamydinae, and Palliolinae subfamilies. The species-specific occurrence of NMI and 22:4(n-9)Δ13trans FA in membrane lipids of pectinids agrees with the most recent phylogenies based on shell morphology and molecular characteristics. We examined the potential timing of the appearance of 22:4(n-9)Δ13trans in pectinids on a geologic time scale.