127 articles for “Modulation”

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Research ArticleOpen accessIn the abstractEffects of Low Frequencies on Three Phase Induction Motor Performance Operating in Close Proximity to Rated SpeedQazem Jaber, Qais Naman, Mahdi ShamaseenVariable speed drives (VSD) are adhered to induction motors in most of the present industrial applications. And since the world has become more conscientious to energy saving, inverters established them selves in domestic buildings and industry. Square wave inverters generate dominant harmonics of the 5th, 7th, 11th and 13th order. Inverters based on PWM strategy produce much higher harmonic order … …American Journal of Applied Sciences, Vol. 4, Issue 5 · 31 May 2007 · 7,516 accessesView PDF Cite

Research ArticleOpen accessIn the abstractImproving Mechanical Characteristics of Inverter-induction Motor Drive SystemHussein Sarhan, Rateb IssaAn inverter-three-phase squirrel-cage induction motor drive system with improved mechanical characteristics is presented. The proposed system provides mechanical characteristics with constant maximum torque or increased maximum torque and reduced slip speed at frequencies below the nominal frequency. The control algorithm is based on the constant volts per hertz principle using two improvement techniques: keeping maximum torque constant or keeping magnetic … …American Journal of Applied Sciences, Vol. 3, Issue 8 · 31 Aug 2006 · 7,659 accessesView PDF Cite

Research ArticleOpen accessIn the abstractNew Proposed Second-Order ASDM Using OTAsFarouq M. Al TaweelIn this work, we present a new proposal for the second-order Adaptive Sigma Delta Modulation (ASDM). The new proposed Adaptation scheme is based on using Operational Transconductance Amplifier (OTAs) as an Integrator and as an Amplifier to adapt the quantizer step-size to control the voltage gain by feedback the quantizer output through adaptation scheme. The step-size is changing up or … …American Journal of Applied Sciences, Vol. 3, Issue 2 · 28 Feb 2006 · 6,950 accessesView PDF Cite

Research ArticleOpen accessIn the abstractFault Detection of 3-Phase VSI using Wavelet-Fuzzy AlgorithmM. Rozailan Mamat, M. Rizon, M. S. KhannicheThe good knowledge and information about the fault mode behaviour of the PWM voltage source inverter is important to improve system design, protection and fault tolerant control. This paper develops a real-time condition-monitoring algorithm for 3-phase Pulse Width Modulation (PWM) inverter in fuzzy speed controlled induction machine. It is designed to detect and identify the transistor open-circuit fault and an … …American Journal of Applied Sciences, Vol. 3, Issue 1 · 31 Jan 2006 · 7,956 accessesView PDF Cite

Research ArticleOpen accessIn the abstractTowards Identifying Immunogenic Targets in Visceral Leishmaniasis: Role of 17kDa and 63kDa PhosphoproteinsShubhankar K Singh, Sanjiva Bimal, Diwakar S. Dinesh et al.We observed predominant phosphorylation at Protein Kinase C (PKC-α) residue in seven immunoreactive proteins of virulent Leishmania donovani parasites. These phosphoproteins were tested for their ability to stimulate T-cells for secretion of Macrophage Migration Inhibition Factor (MIF) in comparision to crude soluble antigen in Visceral Leishmaniasis (VL) patients. Two of these phosphorylated L. donovani antigens led Leishmania to present these … …American Journal of Immunology, Vol. 1, Issue 3 · 30 Sep 2005 · 6,756 accessesView PDF Cite

Research ArticleOpen accessIn the abstractFiber Laser Beam Welding Between Niobium and TitaniumRafael Humberto de Mota Siqueira, Isabela Atilio, Caroline Cristine de Andrade Ferreira et al.Niobium and titanium are difficult to weld because of many factors, such as their tendency to oxidize and burn and the relatively high melting temperatures. Here, fiber laser beam welding has been proposed to weld Nb and Ti sheets in overlap geometry. In the current research, one millimeter thick CP-Ti was placed at the top and a 3 mm pure … …Journal of Aircraft and Spacecraft Technology, Vol. 4, Issue 1 · 9 Mar 2020 · 7,715 accessesView PDF Cite

Research ArticleOpen accessIn the abstractDynamics of Coherent Structures in the Coupled Complex Ginzburg-Landau EquationsTat-Leung YeeProblem statement: In this study, we study the analytical construction of some exact solutions of a system of coupled physical differential equations, namely, the Complex Ginzburg-Landau Equations (CGLEs). CGLEs are intensively studied models of pattern formation in nonlinear dissipative media, with applications to biology, hydrodynamics, nonlinear optics, plasma physics, reaction-diffusion systems and many other fields. Approach: A system of two … …Journal of Mathematics and Statistics, Vol. 8, Issue 3 · 6 Nov 2012 · 6,990 accessesView PDF Cite