Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine
- Authors: Ogunjuyigbe, A. S. O. , Jimoh, A. A. , Nicolae, Dan-Valentin , Obe, E. S.
- Date: 2010
- Subjects: Capacitance meters , Synchronous machinery , Torque
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/18633 , uj:16024 , ISSN:1827-6660 , Citation: Ogunjuyigbe, A.S.O. et al. 2010. Performance analysis of capacitance compensated dual stator winding synchronous reluctance machine. International Review of Electrical Engineering,5(2), April 2010:437-446
- Description: Abstract: Synchronous reluctance machine with simple salient rotor are known to have poor power factor because they have a low effective reactance ratio. This paper used a 3 phase auxiliary winding and balanced capacitance compensation to ifluence the effective reactance ratio of a synchronous reluctance machine with simple salient rotor structure, such that its power factor and torque/ampere performance is improved. A mathematical model and dq equivalent circuit suitable for dynamic and steady state analysis was developed and used to study the synchronous operation of this machine.Analytical as well as experimental results for a 4-pole, 36 slots simple salient rotor reluctance machine showed that the effective reactance ration increased with the capacitance size, and the machine operated at a maximum power factor of 0.969 without altering the geometry of the rotor. the torque per ampere of the machine also improved with the size of capacitor attached to the auxilary winding.
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Normative isokinetic torque values for rehabilitation in South Africa
- Authors: Lategan, Leon
- Date: 2012-03-14
- Subjects: Isokinetic exercise , Torque , Rehabilitation
- Type: Thesis
- Identifier: uj:2165 , http://hdl.handle.net/10210/4538
- Description: D.Phil. , The goal of effective rehabilitation should always be to restore "normal" function if possible. What is "normal" function? Although many subjective definitions may describe what is "normal", it is the search for objective criteria of what constitutes "normality" that inspires exercise scientists worldwide! The primary aim of this study was to establish normative isokinetic torque values in young males, for rehabilitation purposes in South Africa. Four hundred and forty four (444) healthy male subjects participated in the study. A Cybex 340 isokinetic dynamometer was used to measure peak torque, using a quantitative experimental design. No correction was made for the effects of gravity. The following movement patterns were included: ankle plantar/dorsiflexion, knee flexion/extension, shoulder external/internal rotation, shoulder horizontal abduction/adduction, shoulder flexion/extension, elbow flexion/extension (using two different grip positions), and forearm pronation/supination. Descriptive statistics together with percentile scaling were used to develop normative values for the movement patterns studied. Normative values were presented in relative terms and expressed as a percentage in terms of Nm torque per kg body mass (% BM). In addition to the relative isokinetic torque values, the agonisUantagonist ratios were also ~xpressed as a percentage. The percentile scales were also included to be used by clinicians involved in talent identification programmes and the screening of elite athletes. To conclude, normative isokinetic values were de'leloped for young South African males. To enable subjects with large variations in body weight to utilize these norms, they were expressed in relative terms (% BM) instead of absolute terms (Nm). The possible benefit of the study was that population-specific and objective normative values were established for rehabilitation purposes and for use in sport science programs.
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Fault-tolerance of five-phase induction machines with mixed stator winding layouts : torque ripple analysis
- Authors: Muteba, M. , Nicolae, Dan-Valentin
- Date: 2015
- Subjects: Induction heating , Torque
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/16827 , uj:15812 , Citation: Muteba, M. & Nicolae, D.V. Fault-tolerance of five-phase induction machines with mixed stator winding layouts: torque ripple analysis, the 2015 IEEE International electric machines and drives conference (IEMDC), paper 0308-df-005908, May 2015, U.S.A.
- Description: Abstract The mixed winding layouts proposed in this paper are obtained by combining double and triple layer (DTL) windings in stator slots. Previous work has touched upon on the ability of three-and five-phase induction machines (IMs) with mixed winding layouts to produce torque with less ripple contents. However, their advantage when operating under open-circuited faults is yet to be comprehensively reported. This paper presents the fault-tolerant ability of Fivephase Induction Machines (FPIMs) with mixed winding layouts to produce torque with less ripple contents. The windings are designed as 2-pole and chorded with one slot, thereafter referred to as “DTL-14/15” and when chorded with two slots, thereafter referred to as “DTL-13/15. The magnetic conditions in the FPIMs are analyzed using Finite Element Method (FEM). The results evidenced that the FPIMs with the proposed DTL-14/15 and DTL-13/15 chorded coils reduced the torque ripple by a margin of about 60 % while operating with open-circuited faults respect to FPIMs with conventional double layer (DL) winding of the same coil span and operating under the same conditions. The results also prove that there is a great correlation between FEM (simulation) and experimental results.
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Force feedback analysis: friction stir welding of aluminium metal matrix composite
- Authors: Abegunde, Olayinka O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
- Date: 2016
- Subjects: Force feedback , Friction stir welding , Heat input , Torque
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93400 , uj:20342 , Citation: Abegunde, O.O., Akinlabi, E.T. & Madyira, D.M. 2016. Force feedback analysis: friction stir welding of aluminium metal matrix composite.
- Description: Abstract: This paper presents the output response parameters (forces feedback, torque and heat input) during friction stir welding of aluminium. The welding was performed on an Intelligent Stir Welding for Industry and Research (ISTIR) Process Development System (PDS) using different rotational and transverse speeds while other input parameters like tool geometry, tilt angle and workpieces configuration were kept constant. The I-STIR FSW platform is capable of recording the force feedback and torque during the welding process and the heat input was calculated using a mathematical relationship. The study reveals the influence of the rotational and transverse speed on the pattern of the output feedback. The reinforcement ceramic particles added to the weld seam during welding also affected the output feedback.
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Torque effects on thread integrity of a plug bolt and parent plate
- Authors: Noor Mohamed, Mumtaaz Begum
- Date: 2020
- Subjects: Fasteners , Bolts and nuts , Torque
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/479603 , uj:43388
- Description: Abstract: Air-cooled heat exchangers (ACHE’s) that use plug-type header boxes need to be sealed from the plug sheet. During installation it is possible that the internal threads of the header box or the external threads of the plug bolt are stripped thus, compromising the ACHE. The study conducted analysed the behaviour of the internal and external threads of a plug bolt and parent plate manufactured to conform to 1.125 – 12 UN – Class 2A and 2B to ANSI B1.1. The connections were deemed reusable and a torque of 400 Nm was applied to ten lubricated plug bolts, each analysed on a new threaded hole for each plug bolt. It was concluded that the threads deform in an unpredictable manner and may deviate from the standard 60º by either increasing or decreasing from the standard during any tightening. The finite element analysis (FEA) results indicate that the threaded regions are not subjected to stresses that exceed the yield strength of either material and therefore, thread stripping will not occur. The experimental results agree, in this regard, to the FEA results. , M.Ing. (Mechanical Engineering Science)
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