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E-Learning Practical Teaching of Resonant AC Circuits
Viorel Popescu,Dan Lascu,Mircea Bbi??,Mihaela Lascu
Journal of Electrical and Electronics Engineering , 2009,
Abstract: The paper presents hardware and softwareaspects regarding an E-learning approach of resonantac converters. Built on LabVIEW and accompanied bya switching board interface, the setup allows acomprehensive study by remote controlling andperforming real measurements on converters. Thestudy is offered in a gradually manner, with theoreticalaspects and simulation first, in the end the realexperiments being investigated.
Remote Experiments in Resistor Measurement
Popescu Viorel,Bbi?? Mircea,Popovici Adrian,Lascu Dan
Journal of Electrical and Electronics Engineering , 2009,
Abstract: The paper describes blended learningapproach to teaching resistor measurement. It is basedon “Learning by Doing” paradigm: interacticesimulation, laboratory plants, real experimentsaccessed by Web Publishing Tools under LabVIEW.Studying and experimenting access is opened for 24hours a day, 7 days a week under Moodle bookingsystem.
LabVIEW-Based Control of a Switching Board for Distance E-Learning
Dan Lascu,Mircea Bbi??,Mihaela Lascu,Viorel Popescu
Journal of Electrical and Electronics Engineering , 2008,
Abstract: The paper presents hardware and softwareaspects regarding design and LabVIEW control of aswitching board interface used in distance learning.Finally a relay matrix is controlled according to a desired32-bit word sequence. This is intended in studying powerelectronics and the authors used it in practicalconfiguring and experimenting different types ofuncontrolled rectifiers.
Using the PIC16F84 Microcontroller in Intelligent Stepper Motor Control
Papazian Petru,Bbi?? Mircea,Popovici Adrian
Journal of Electrical and Electronics Engineering , 2008,
Abstract: For applications requiring critical rotorpositioning, usually stepper motors are the bestchoice. Stepper motors operate differently fromother motors; rather than voltage being appliedand the rotor spinning smoothly, stepper motorsturn on a series of electrical pulses to the motor'swindings. Each pulse rotates the rotor by an exactdegree and a series of pulses must be generated toperform a complete rotation. An intelligentcontrolling device was conceived and built basedon a PIC16F84 microcontroller and UFDC-1interface.
DC Motor Drive with PFC Rectifier
Bbi?? Mircea,Popescu Viorel,Popovici Adrian,Lascu Dan
Journal of Electrical and Electronics Engineering , 2008,
Abstract: The goal of this work is to study theperformances of a hybrid controller used to controlDC Motor drive with a single-phase power factorcorrection rectifier. This study is made usingcomputer simulation (Simulink). The first part isdevoted to the control system of the DC Motors. Inthe second part, the design of the hybrid controllerwill be presented. The third part is the design ofthe fast response single-phase boost power factorcorrection rectifier. The last parts are devoted tosimulation and experimental results.
ON THE EQUATIONS OF GEOMETRICALLY NONLINEAR ELASTIC PLATES WITH ROTATIONAL DEGREES OF FREEDOM
Mircea B?rsan,Patrizio Neff
Mathematics and its Applications : Annals of the Academy of Romanian Scientists , 2012,
Abstract: We consider the general model of 6-parametric elastic plates, inwhich the rotation tensor field is an independent kinematic field. Inthis context we show the existence of global minimizers to the minimization problem of the total potential energy.
Existence theorem for geometrically nonlinear Cosserat micropolar model under uniform convexity requirements
Patrizio Neff,Mircea B?rsan,Frank Osterbrink
Mathematics , 2014,
Abstract: We reconsider the geometrically nonlinear Cosserat model for a uniformly convex elastic energy and write the equilibrium problem as a minimization problem. Applying the direct methods of the calculus of variations we show the existence of minimizers. We present a clear proof based on the coercivity of the elastically stored energy density and on the weak lower semi-continuity of the total energy functional. Use is made of the dislocation density tensor $\bar{\boldsymbol{K}}=\bar{\boldsymbol{R}}^T\,\mathrm{Curl}\,\bar{\boldsymbol{R}}$ as a suitable Cosserat curvature measure.
Numerical Treatment of a Geometrically Nonlinear Planar Cosserat Shell Model
Oliver Sander,Patrizio Neff,Mircea B?rsan
Mathematics , 2014,
Abstract: We present a new way to discretize a geometrically nonlinear elastic planar Cosserat shell. The kinematical model is similar to the general 6-parameter resultant shell model with drilling rotations. The discretization uses geodesic finite elements, which leads to an objective discrete model which naturally allows arbitrarily large rotations. Finite elements of any approximation order can be constructed. The resulting algebraic problem is a minimization problem posed on a nonlinear finite-dimensional Riemannian manifold. We solve this problem using a Riemannian trust-region method, which is a generalization of Newton's method that converges globally without intermediate loading steps. We present the continuous model and the discretization, discuss the properties of the discrete model, and show several numerical examples, including wrinkles of thin elastic sheets in shear.
Effects of replacement of soya bean meal by bambara nut sievate on the carcass and organ parameters of finisher broiler chicks  [PDF]
B. U. Ekenyem, B. I. Odo
Open Journal of Animal Sciences (OJAS) , 2011, DOI: 10.4236/ojas.2011.13012
Abstract: Eighty 4-weeks old broiler chicks (Anak 2000 strain) were used in a 28 days feeding trial to determine the effects of replacement of soya bean meal (SBM) by bambara nut sievate (BNS) on the carcass and organ characteristics of fin- isher broiler chicks. BNS replaced soya bean meal by weight for weight at levels 0%, 5%, 10% and 15% for treatments 1,2, 3 and 4; respectively which were replicated four times in a completely randomized design. Feed and potable water were supplied ad libitum to the birds. Also, ap- propriate medication, sanitation and other stan- dard management practices were strictly adopt- ed. At the 28th day, one bird was randomly picked from each replicate, starved of food for 24 hours and then slaughtered and eviscerated for carcass and organ evaluation. Weights were measured with digital weighing scale. Results of analysis of variance of carcass parameters showed significant (P < 0.05) difference in the final live weight, carcass weight and dressed weight. Birds on 10% BNS and 5% BNS were not statistically different (P > 0.05) in the values above but only varied with birds on 10% and 15% BNS. Other carcass parameters were simi- lar (P > 0.05) in value between treatments. The liver, heart, gizzard and intestine significantly varied (P < 0.05) between their treatments. How- ever, kidney values did not differ significantly. From the results, it appeared that 5% BNS in- clusion is optimal for carcass and organ char- acteristics of finisher broilers.
Hygroscopic growth and critical supersaturations for mixed aerosol particles of inorganic and organic compounds of atmospheric relevance
B. Svenningsson,J. Rissler,E. Swietlicki,M. Mircea
Atmospheric Chemistry and Physics Discussions , 2005,
Abstract: The organic fraction of atmospheric aerosols contains a multitude of compounds and usually only a small fraction can be identified and quantified. However, a limited number of representative organic compounds can be used to describe the water-soluble organic fraction. In this work, initiated within the EU 5FP project SMOCC, four mixtures containing various amounts of inorganic salts (ammonium sulfate, ammonium nitrate, and sodium chloride) and three model organic compounds (levoglucosan, succinic acid and fulvic acid) were studied. The interaction between water vapor and aerosol particles was studied at different relative humidities: at subsaturation using a hygroscopic tandem differential mobility analyzer (H-TDMA) and at supersaturation using a cloud condensation nuclei spectrometer (CCN spectrometer). Surface tensions as a function of carbon concentrations were measured using a bubble tensiometer. Parameterizations of water activity as a function of molality, based on hygroscopic growth, are given for the pure organic compounds and for the mixtures, indicating van't Hoff factors around 1 for the organics. The Zdanovskii-Stokes-Robinson (ZSR) mixing rule was tested on the hygroscopic growth of the mixtures and it was found to adequately explain the hygroscopic growth for 3 out of 4 mixtures, when the limited solubility of succinic acid is taken into account. One mixture containing sodium chloride was studied and showed a pronounced deviation from the ZSR mixing rule. Critical supersaturations calculated using the parameterizations of water activity and the measured surface tensions were compared with those determined experimentally.
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