168 research outputs found
Modular switched reluctance machines to be used in automotive applications
In the last decades industry, including also that of electrical machines and drives, was pushed near to its limits by the high market demands and fierce competition. As a response to the demanding challenges, improvements were made both in the design and manufacturing of electrical machines and drives. One of the introduced advanced technological solutions was the modular construction. This approach enables on a hand easier and higher productivity manufacturing, and on the other hand fast repairing in exploitation. Switched reluctance machines (SRMs) are very well fitted for modular construction, since the magnetic insulation of the phases is a basic design requirement. The paper is a survey of the main achievements in the field of modular electrical machines, (especially SRMs), setting the focus on the machines designed to be used in automotive applications
Quality of life satisfaction among converted Kelantan Chinese Muslims
This article investigates the quality of life of the Kelantan Chinese Muslim community before and after conversion to Islam, focusing on their level of satisfaction in term of economic aspect. This research was carried out using the sequential explanatory mixed method design involving 75 respondents selected for quantitative and five respondents for qualitative. The sampling method adopted was convenience and snowball samplings. The research data was collected using questionnaires and semi-structured interviews. The results revealed that respondents were moderately satisfied before conversion and satisfied after conversion. Besides that, there is no significant difference of quality of life before and after conversion to Islam (F = 0.868, p = 0.355) and it was not influenced by the period of conversion to Islam (F = 0.832, p = 0.589). This analysis indicates numerous respondents are still moderately satisfied in their quality of life even though the average data shows they are satisfied after conversion
Comparative evaluation QoS of FTP over LEO and GEO Satellite Networks with diffserv architecture
This paper presents studies of the end-to-end QoS of IP over integrated terrestrial and NGSN (next generation satellite
network) for file transfer service using FTP. The authors compare between LEO and GEO satellites constellations for the QoS
parameters (i.e., delay, jitter, loss rate and throughput) of file transfer between one server in London and a client in Boston. The
authors model the file transfer with multiple connections and file size variation according to exponential and Pareto distributions
respectively. The authors create the scenario with error model to simulate transmission loss environment using the NS-2 simulation
software. A Diffserv (differentiated services) queue interface is placed in the server side to regulate the traffic flows across the
narrow bandwidth of the satellite links. The authors compare the empirical TCP throughput traces with analytical model for
validation. The results showed the performance evaluation and presented a good comparison of the QoS parameters involved in the
data transfer across LEO and GEO satellites systems
Pembangunan portal pendidikan teknik dan vokasional: satu kajian awal di kalangan Pelajar Sarjana PTV Jabatan Pendidikan Teknik dan Vokasional Fakulti Teknologi Kejuruteraan
Tujuan kajian ini adalah untuk mengkaji sejauh manakah keperJuan pelajar
terhadap portal Pendidikan Teknik dan Vokasional (PTV). Sebuah portal PTV
dibangunkan dalam kajian berasaskan produk ini. Sampel bagi kajian ini terdiri
daripada pelajar sarjana pendidikan teknik dan vokasional, semester 3. Dapatan kajian
ini dianalisis dengan menggunakan perisian SPSS versi 10. Pada peringkat awal projek
ini, keperluan pelajar terhadap portal PTV dikenal pasti. Selepas itu, ciri-ciri yang perlu
dibangunkan dalam portal PTV dikenal pasti dengan menggunakan kaedah borang soal
selidik. Satu portal PTV dibangunkan berdasarkan dapatan kajian tersebut. Pada
peringkat akhir projek ini, penilaian dilakukan ke atas portal PTV yang telah
dibangunkan. Tujuan penilaian ini adalah untuk mengenal pasti sejauh manakah portal
PTV ini memenuhi keperluan pelajar. Daripada dapatan kajian didapati portal PTV
amat diperlukan oleh pelajar. Selain daripada itu, daripada dapatan kajian, portal PTV
yang telah dibangunkan ini beryaya memenuhi keperluan pelajar. Cadangan untuk
memperbaiki portal PTV yang telah dibangunkan ini diberi oleh responden. Kajian
lanjutan patut dilakukan ke atas portal PTV yang telah dibangunkan bagi memperbaiki
serta memumikan konsep reka bentuk dan pengurusan maklumat
An evidence-based forensic taxonomy of windows phone dating apps
Advances in technologies including development of smartphone features have contributed to the growth of mobile applications, including dating apps. However, online dating services can be misused. To support law enforcement investigations, a forensic taxonomy that provides a systematic classification of forensic artifacts from Windows Phone 8 (WP8) dating apps is presented in this study. The taxonomy has three categories, namely: Apps Categories, Artifacts Categories, and Data Partition Categories. This taxonomy is built based on the findings from a case study of 28 mobile dating apps, using mobile forensic tools. The dating app taxonomy can be used to inform future studies of dating and related apps, such as those from Android and iOS platforms
Simulation analysis of ultrasonic testing in steel-based butt weld joint
Within this study, a simulation analysis based on Ultrasonic Testing (UT)
is made using Comsol Multiphysics. Comsol Multiphysics is a software that can
simplify many aspects of building UT method and also can be used to obtain a fast
understanding of the results of altering the fundamental parameters. The software
program has useful features which can help in technique development especially for
UT inspectors in Non- destructive Testing (NDT) field. The focus of this study is to
conduct a simulation analysis of internal weld defects by developing the model of
defects in a weld structure sample configured using the software. The model is
developed based on actual parameters and characterization of weld structure sample
and internal weld defects. The results of analysis show that each type of defects which
are incomplete penetration, slag inclusion and lack of fusion have different signal
pattern and signal amplitude which are depended on the characterizations of those
defects themselves
Flux switching machines using segmental rotors
Flux switching machines (FSM) employing a segmental rotor have field and armature systems on the stator and a presentation of an unexcited rotor with isolated segments. The single-tooth winding arrangement on the stator provides a potential for material and energy savings. The principle for producing bipolar flux in the armature stator teeth relies on the natural switching of the armature tooth flux, accomplished by the moving segments of the rotor. Three phase configurations have been studied, from conception and design to construction and testing, with field excitation provided by either a field winding or permanent magnets (PM). Flux switching machines have shown characteristics that are peculiar when employing a segmental rotor, significantly affecting the symmetry of the induced armature EMF waveform and parity of magnitudes of the positive and negative torques. For three phase operation, six topologies are feasible when employing a 12-tooth stator and two other topologies may be produced on a 24-tooth stator. An optimum topology on the 12/8-configuration and another proof-of-principle topology on the 12/5-configuration, using field-windings and permanent-magnets, have been designed and constructed, while applying modern practices and considerations for manufacture. The characteristics of FSMs employing a segmental rotor, initially predicted by finiteelement (FE) modelling, have been verified by measurements. The FSM employing a field-winding is found to have a specific torque output which is similar to the conventional switched reluctance motor and still substantially higher than that of the synchronous reluctance motor. Although the PM adaptation of the FSM produces specific torque output which is nearly twice that of the wound-field FSM and about 64% that of an equivalent permanent-magnet synchronous motor (PMSM) with surface or insert magnets, accounting for the usage of the magnets reflects its specific torque output to be about 1.48 times higher than the PMSM. Although the FSM is operated as an AC machine with sinusoidal three-phase currents, its dq-equivalent representation shows significant differences from that of the conventional AC machine. In the prediction of the performance, it is found, in both the wound-field and PM configurations, that the dq model is more dependable if the coupling dq inductance is taken into account.EThOS - Electronic Theses Online ServiceCommonwealth Scholarship Commission of UKGBUnited Kingdo
Three-dimensional soft material micropatterning via grayscale photolithography for improved hydrophobicity of Polydimethylsiloxane (PDMS)
: In this present work, we aim to improve the hydrophobicity of a polydimethylsiloxane
(PDMS) surface. Various heights of 3D PDMS micropillars were fabricated via grayscale photolithog�raphy, and improved wettability was investigated. Two approaches of PDMS replication were
demonstrated, both using a single master mold to obtain the micropillar arrays. The different heights
of fabricated PDMS micropillars were characterized by scanning electron microscopy (SEM) and a
surface profiler. The surface hydrophobicity was characterized by measuring the water contact angles.
The fabrication of PDMS micropillar arrays was shown to be effective in modifying the contact angles
of pure water droplets with the highest 157.3-degree water contact angle achieved by implementing a
single mask grayscale lithography technique
Linear Machines for Long Stroke Applications: a review
This document reviews the current state of the art in the linear machine technology. First,the recent advancements in linear induction, switched reluctance and permanent magnet machines arepresented. The ladder slit secondary configuration is identified as an interesting configuration for linearinduction machines. In the case of switched reluctance machines, the mutually-coupled configuration hasbeen found to equate the thrust capability of conventional permanent magnet machines. The capabilities ofthe so called linear primary permanent magnet, viz. switched-flux, flux-reversal, doubly-salient and verniermachines are presented afterwards. A guide of different options to enhance several characteristics of linearmachines is also listed. A qualitative comparison of the capabilities of linear primary permanent magnetmachines is given later, where linear vernier and switched-flux machines are identified as the most interestingconfigurations for long stroke applications. In order to demonstrate the validity of the presented comparison,three machines are selected from the literature, and their capabilities are compared under the same conditionsto a conventional linear permanent magnet machine. It is found that the flux-reversal machines suffer froma very poor power factor, whereas the thrust capability of both vernier and switched-flux machines isconfirmed. However, the overload capability of these machines is found to be substantially lower than theone from the conventional machine. Finally, some different research topics are identified and suggested foreach type of machine
SRM drives for electric traction
"GAECE" -- PortadaDescripció del recurs: 11 maig 2020GAECE (Grup d’accionaments elèctrics amb commutació electrònica). The group of electronically commutated electrical drives is a research team of Universitat Politècnica de Catalunya (UPC BARCELONATECH), which conducts investigation in four areas: electrical drives, power electronics, mechanics and energy and sustainability. Regarding electrical drives, research focuses on the development of new reluctance, permanent magnet and hybrid electrical drives. The main goal of those electrical drives is the integration of the power converter/controller and the mechanical transmission, being specially intended for the traction of light electric vehicles. That research is carried out by using the analysis of finite elements, taking into account eco-design criteria, considering new materials and new control strategies.First editio
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