Ice Accretion and Performance Degradation Calculations with LEWICE/NS

The LEWICE ice accretion computer code has been extended to include the solution of the two-dimensional Navier-Stokes equations. The code is modular and contains separate stand-alone program elements that create a grid, calculate the flow field parameters, calculate the droplet trajectory paths, determine the amount of ice growth, calculate aeroperformance changes, and plot results. The new elements of the code are described. Calculated results are compared to experiment for several cases, including both ice shape and drag rise

Reality or illusion? The efficacy of nonmarket strategy in institutional risk reduction

Non-market strategy researchers have postulated that political and social strategies reduce the exposure of firms to risk, but those arguments have received little empirical attention. In this paper, we integrate social capital and institutional theories to examine the efficacy of managerial political ties (MPTs) and corporate social responsibility (CSR) in institutional risk reduction. Using survey data from 179 firms in Ghana we find that, whereas CSR reduces institutional risk exposure, MPTs do not. We also find that the effect of MPTs on risk exposure is moderated by public affairs functions. Contrary to extant literature, we do not find evidence of complementarity between MPTs and CSR. Altogether, the findings not only show that the proposed efficacy of MPTs in risk reduction is illusive, but they also signal the need for scrutinizing the harmony between non-market political and social strategies

Modelling framework for parallel SiC power MOSFETs chips in modules developed by planar technology

This paper presents a modelling framework to simulate transients and steady state performance for SiC power MOSFETs modules. The electro-thermal modelling is implemented using Simscape/MATLAB program based on the single chip characteristics provided in the datasheet. The method can easily incorporate multiple chips and module parasitic components providing a tool for module characterization and to support module design optimization. The simulated model is then experimentally validated at different voltage buses and junction temperatures for a novel SiC MOSFET Module design consists of two parallel chips per switch developed using wire-bond free planar technology

Real-time Measurement of Temperature Sensitive Electrical Parameters in SiC Power MOSFETs

This paper examines a number of techniques for junction temperature estimation of SiC MOSFETs devices based on the measurement of Temperature Sensitive Electrical Parameters (TSEPs) for use in online condition monitoring. Linearity, sensitivity to temperature and circuit design for practical implementation are discussed in detail. A demonstrator based on the measurement of the quasi-threshold voltage, the turn-on transient characteristic (di/dt), the on-state voltage and the gate current peak is designed and validated. It is shown that the threshold voltage, the estimation of the gate current peak and the on-state voltage have potentially good sensitivity to temperature variation and linearity over a wide operating range. Very low sensitivity to temperature is shown for (di/dt). The proposed method can provide a valuable tool for continuous health monitoring in emerging applications of SiC devices to high reliability applications

The Chaotic Properties of the Shift Map and His Conjugacy of Horseshoe Map

في هذا العمل, درسنا بعض الخصائص الفوضوية المختلفة لفضاء الضرب على دالة التزحيف. اوجدنا ترافقا تبولوجيا بين دالة التزحيف ودالة حدوة الحصان لنقل الخواص الفوضوية المدروسة على فضاء   .In our study, we prove some chaotic properties of the shift map  on the symbol space  and apply the topological conjugacy property of the shift map on the horseshoe map

Geospatial resources for supporting data standards, guidance and best practice in health informatics

<p>Abstract</p> <p>Background</p> <p>The 1980s marked the occasion when Geographical Information System (GIS) technology was broadly introduced into the geo-spatial community through the establishment of a strong GIS industry. This technology quickly disseminated across many countries, and has now become established as an important research, planning and commercial tool for a wider community that includes organisations in the public and private health sectors.</p> <p>The broad acceptance of GIS technology and the nature of its functionality have meant that numerous datasets have been created over the past three decades. Most of these datasets have been created independently, and without any structured documentation systems in place. However, search and retrieval systems can only work if there is a mechanism for datasets existence to be discovered and this is where proper metadata creation and management can greatly help.</p> <p>This situation must be addressed through support mechanisms such as Web-based portal technologies, metadata editor tools, automation, metadata standards and guidelines and collaborative efforts with relevant individuals and organisations. Engagement with data developers or administrators should also include a strategy of identifying the benefits associated with metadata creation and publication.</p> <p>Findings</p> <p>The establishment of numerous Spatial Data Infrastructures (SDIs), and other Internet resources, is a testament to the recognition of the importance of supporting good data management and sharing practices across the geographic information community. These resources extend to health informatics in support of research, public services and teaching and learning.</p> <p>This paper identifies many of these resources available to the UK academic health informatics community. It also reveals the reluctance of many spatial data creators across the wider UK academic community to use these resources to create and publish metadata, or deposit their data in repositories for sharing.</p> <p>The Go-Geo! service is introduced as an SDI developed to provide UK academia with the necessary resources to address the concerns surrounding metadata creation and data sharing. The Go-Geo! portal, Geodoc metadata editor tool, ShareGeo spatial data repository, and a range of other support resources, are described in detail.</p> <p>Conclusions</p> <p>This paper describes a variety of resources available for the health research and public health sector to use for managing and sharing their data. The Go-Geo! service is one resource which offers an SDI for the eclectic range of disciplines using GIS in UK academia, including health informatics.</p> <p>The benefits of data management and sharing are immense, and in these times of cost restraints, these resources can be seen as solutions to find cost savings which can be reinvested in more research.</p

Extended Kalman filter based sliding mode control of parallel-connected two five-phase PMSM drive system

This paper presents sliding mode control of sensor-less parallel-connected two five-phase permanent magnet synchronous machines (PMSMs) fed by a single five-leg inverter. For both machines, the rotor speeds and rotor positions as well as load torques are estimated by using Extended Kalman Filter (EKF) scheme. Fully decoupled control of both machines is possible via an appropriate phase transposition while connecting the stator windings parallel and employing proposed speed sensor-less method. In the resulting parallel-connected two-machine drive, the independent control of each machine in the group is achieved by controlling the stator currents and speed of each machine under vector control consideration. The effectiveness of the proposed Extended Kalman Filter in conjunction with the sliding mode control is confirmed through application of different load torques for wide speed range operation. Comparison between sliding mode control and PI control of the proposed two-motor drive is provided. The speed response shows a short rise time, an overshoot during reverse operation and settling times is 0.075 s when PI control is used. The speed response obtained by SMC is without overshoot and follows its reference and settling time is 0.028 s. Simulation results confirm that, in transient periods, sliding mode controller remarkably outperforms its counterpart PI controller. 2018 by the authors.Scopu