Re-examining the potential effectiveness of interactive query expansion

Much attention has been paid to the relative effectiveness of interactive query expansion versus automatic query expansion. Although interactive query expansion has the potential to be an effective means of improving a search, in this paper we show that, on average, human searchers are less likely than systems to make good expansion decisions. To enable good expansion decisions, searchers must have adequate instructions on how to use interactive query expansion functionalities. We show that simple instructions on using interactive query expansion do not necessarily help searchers make good expansion decisions and discuss difficulties found in making query expansion decisions

Mondale-Ferraro Campaign Itinerary, July 31, 1984-August 2, 1984: Seventh Draft

Seventh draft: campaign itinerary for first events following 1984 convention. Details events in Minnesota, New York, Ohio, Mississippi, and Texas scheduled from July 31, 1984 to August 2, 1984.https://ir.lawnet.fordham.edu/vice_presidential_campaign_materials_1984/1006/thumbnail.jp

Thermal management of a high speed permanent magnet machine for an aeroengine

The paper describes the mechanical and thermal design of a high speed, high power density synchronous permanent magnet machine for an aero engine starter generator system with a power rating of 150 kW and maximum speed of 32,000 rpm. As both mechanical and thermal aspects have a direct impact on machine overall performance and weight reduction, a critical design optimisation was carried out. Intensive cooling is guaranteed by direct liquid oil-cooling of stationary components; a stator sleeve is also introduced into the airgap to prevent excessive windage. Thermal investigations were carried out by the means of Computational Fluid Dynamics (CFD) and Lumped Parameter Thermal Network (LPTN) analyses. Experimental validation also allowed the identification of most critical machine temperatures and the validation of the models developed. Finite Element Analysis(FEA) is used for the static structural analyses of the statorsleeve

Permanent magnet synchronous motor development on the base of induction motor with squirrel-cage rotor

Представлена методика расчета и выбора параметров синхронного двигателя с постоянными магнитами при известной геометрии статора базового асинхронного двигателя с короткозамкнутым ротором. Приведены результаты проектирования и математического моделирования синхронного двигателя с постоянными магнитами. Выполнен анализ энергетической эффективности разработанного двигателя.Permanent magnet synchronous motor calculation methodology and parameters choosing at the known geometry of the base induction motor with squirrel cage rotor stator is represented. Design and simulation results of the permanent magnet synchronous motor are shown. The analysis of power efficiency of the developed motor is done

Wykorzystanie analogii elektryczno-cieplnych w komercyjnych programach do analizy zjawisk cieplnych.

III Konferencja Naukowo- Techniczna "Problemy Cieplne w Elektrotechnice i Elektrotechnologie" 2015Obliczenia cieplne maszyn i urządzeń elektrycznych mogą być realizowane zarówno w sposób analityczny, jak i numeryczny. W praktyce obliczeniowej często wykorzystywana jest również metoda obwodowa bazująca na analogiach elektryczno-cieplnych. Metoda ta została również zaimplementowana w rozbudowanych programach komercyjnych, np. MotorCAD ® do obliczeń cieplnych 3D maszyn elektrycznych, czy Portunus® do analiz typu multiphysics

Trade-off analysis and design of a high power density PM machine for flooded industrial pump

This paper presents the trade-off analysis and design of a high power-density machine for industrial pump applications. The developed permanent magnet synchronous machine drives an electric, oil flooded pump. Different slot/pole combination and winding configuration have been investigated in order to identify the optimal combination that satisfies the electromagnetic and thermal constraint while keeping the losses as small as possible. Several strategies such as the use of the Cobalt iron material for the stator core lamination and the adoption of Halbach array have been investigated in this work to improve the performance capabilities of the designed machine. The electromagnetic performances have been evaluated by using a finite element method. Thermal behaviour has been determined using a lumped parameter network. The outcome of the thermal analysis helped to identify the optimal cooling configurations. The final results are presented highlighting the achieved design targets

NVH analysis and optimization of an electric powertrain

Because of its compact shape and high power density, the permanent magnet synchronous motor (PMSM) appears to be better as a drive motor for electric construction machines (ECMs). However, as compared to conventional construction machines, the motor-driven machine has exhibited a different noise profile as a result of the shift in noise excitation source. The dramatic increase in high-frequency noises is particularly noticeable in this scenario. Furthermore, some of these highfrequency noises are distributed in the frequency range that is sensitive to human hearing, causing operators to feel highly uneasy. Furthermore, gear whine noise emitted from the electric powertrain system could significantly affect driving comfort and has become an important NVH problem. The motor’s electromagnetic forces and the reducer’s gear-meshing forces could create structural vibration and whining noise with clear order characteristics. As a result, it’s critical to look into the NVH characteristics of PMSM and reducer for ECMs. Computer-aided engineering (CAE) based vibration and sound simulation is a key approach for studying and optimizing electric powertrain NVH behavior, especially in the early stages of design. To put it another way, being able to forecast the noise and vibration harshness (NVH) behavior of an electric drive used in ECMs without having to run experimental solutions can save a company a lot of time and money

A Modelica Library for Modelling of Electrified Powertrain Digital Twins

In this paper, a Modelica library of electrified powertrain components is presented and its applications discussed. This library is used to construct digital twins of electrified powertrains during product development. These digital twins provide value by reducing time and cost by up to 30% compared to state-of-the-art approaches. Once products are in-service these same digital twins provide value by improving condition monitoring (state-of-health) by up to 10%. The library includes a multi-fidelity and multi-scale battery and power electronics sub-library, an Electrical Drive Unit (EDU) sub-library modelling different types of electrical machines, and an electrified propulsion system sub-library of template models that leverage the battery, power electronics and EDU components found in the other sub-libraries. Finally, an example of applying the proposed library to electrified vehicle development is presented

Thermo magnetic {FEM} simulation of a {PM} synchronous motor with input data from telemetry driving cycles

Abstract Nowadays, the requirements to reduce greenhouse gas emissions and to provide a healthy and more habitable environment, has led to the development of several sustainable alternative for eco-mobility. Since the improvement of internal combustion engine has reached a steady state point in terms of overall efficiency, the increasingly stringent requirements imposed by international normative standards are leading automotive companies to find other alternatives to reduce pollution. Thanks to the exponentially growth of power electronics, the huge interest on research of high energy and power density batteries and the more integration of the embedded systems, the central role of the electric drive has taken over on most of vehicles applications. The wide use of permanent magnets synchronous motors for electric vehicles application has rapidly spread out, thanks to their capability to provide high torque and efficiency with low weight and size. Since the natural behaviour of permanent magnets to demagnetize under severe conditions, both coupled thermal and magnetics, the necessity to understand and predict the phenomena is mandatory. This paper carries out a performance analysis in duty cycle, given by real CAN and GPS readings in a studied pathway, with discussion of numerical and graphic technical evaluations. Finite element software has also been used for coupled electromagnetic and thermal calculation to set the magnets working point and establish the temperature distribution within the motor itself during the whole thermal transient. A particular overview is done on the dependence of material used and different cooling solutions adopted

High-power density electric motors for regional aircraft propulsion.

This Master's thesis project aims, firstly, to evaluate the current state of the art in aeronautical propulsion technology using electric machines. Once the state of the art has been studied, a tool for the design and calculation of electric motors with superconducting windings is developed in order to present a pre-design that meets the established objectives. The analysis carried out on the state of the art will provide information on the design guidelines that have been taken in recent years, as well as the different projects and studies that are planned for the medium-term future. Thanks to this framework, geometric and performance requirements of the motor are defined together with the objectives to be met. In order to achieve this goal, a superconducting motor design module is implemented in Matlab and FEMM, which helps to develop the selected motor efficiently, rapidly and accurately. The IPED electric machine design tool is described, and the different stages in the calculation of the motor are explained in detail. Finally, the conclusions drawn from the different chapters are summarised, which will serve as a guideline for the continuation of the HIVOMOT project, in which this Master's thesis is framed.El presente proyecto de fin de Máster trata, en primer lugar, de realizar una evaluación sobre el estado actual de la tecnología de la propulsión aeronáutica mediante máquinas eléctricas. Una vez estudiado el estado del arte, se desarrolla una herramienta de diseño y cálculo de motores eléctricos con devanados superconductores con el fin de presentar un prediseño que cumpla con los objetivos establecidos. El análisis realizado sobre el estado de la tecnología permitirá conocer las líneas de diseño que se han tomado en los últimos años, así como los diferentes proyectos y estudios que están previstos en un futuro a medio plazo. Gracias a este marco de trabajo se definen unos requerimientos geométricos y de prestaciones del motor junto con unos objetivos a cumplir. Para poder alcanzar esta meta se implementa un módulo de diseño de motores superconductores en Matlab y FEMM que ayuda a desarrollar el motor seleccionado de forma eficaz, rápida y precisa. Se describe la herramienta de diseño de máquinas eléctricas IPED, y se explica de forma detallada las diferentes etapas en el cálculo del motor. Por último, se resumen las conclusiones extrapoladas en los diferentes capítulos y que servirán como pauta de cara a la continuación del proyecto HIVOMOT, en el que se encuentra enmarcado este proyecto de Fin de Máster