Search results for "electric [charge]"
showing 10 items of 729 documents
EXPERIMENTAL OBSERVATION OF THE INTERACTION BETWEEN A MICROSCOPIC CATHODE TIP AND ELECTRICAL ARC
2008
MICROSCOPIC AND MACROSCOPIC ASPECTS OF STUDENT KNOWLEDGE IN ELECTRIC CONDUCTION IN METALS
2010
This paper presents some preliminary results of a research aimed at portraying individual models of description/explanation of electrical conduction in metals shown by physics prospective teachers and at studying how a specifically designed pedagogical environment can support an adequate evolution of their knowledge and disciplinary competencies. A teaching/learning sequence (TLS) on the subject matter, making use of custom Information Technology tools, aimed at facilitating and scaffolding learning, is shortly described. Some relevant points of the research pilot phases, like the analysis of prospective teachers’ spontaneous models of electrical conduction, the identification of significan…
Active Electric Control of Emissions from Swirling Combustion
2007
Distribution of Ground Fault Current in Substations Fed by a Combined Overhead-Cable Line
2005
When a substation is fed by a combined overhead-cable transmission line, in case of a fault to ground within the substation a consistent part of the fault current flows through the cable sheaths toward the remote source and discharges into the earth at the transition station, where cables are connected to the overhead line. This phenomenon, named "fault application transfer", may result in high ground potentials at the transition station which may cause shocks and equipment damage. In this paper a simple but accurate method on modelling a combined overhead-cable line is presented, allowing the computation of the fault current transferred at the transition station. Numerical analysis shows t…
Comparison between 3-ph and 6-ph PMSM drives for the electric propulsion of unmanned aerial vehicles
2021
The full electric aircraft concept requires accurate design and suitable choice and integration of all the used components. Obviously, the electric propulsion drive is one of the most important on-board equipment. Both power converters and electric motors must have low weight, suitable overload capacity and high reliability. In this paper, two possible solutions of electric propulsion motor for unmanned aerial vehicle are investigated. Sizes, weight and some features of a three-phase PMSM motor are compared to those of a six-phase motor obtained by an appropriate rewinding of the armature, with fixed stator and rotor magnetic circuits. The losses obtained from the numerical analyzes are com…
A software for the evaluation of winding factor harmonic distribution in high efficiency electrical motors and generators
2013
In this paper a software developed for the determination of winding connections, the calculation of winding factors and the evaluation of their harmonic distribution of three and two phase windings is presented by using as input data simply the number of slots, pole pairs and phases. The software is implemented as a function in MATLAB environment. By means of some examples, covering the most relevant winding types, the capabilities of this software will be shown. Particularly, integer and fractional single and double layer winding can be treated. Some examples are presented and briefly discussed. The connections, the winding factor harmonic distribution, the electro-motive force (e.m.f) THD…
Electric relaxation and Mn3+/Mn4+ charge transfer in Fe-doped Bi12MnO20–BiMn2O5 structural self-composite
2016
Fe-doped Bi12MnO20–BiMn2O5 ceramics was sintered at 1130 K for 6 h in ambient air. Two centro-symmetric phases formed thermodynamically stable self-composite material that was deduced from X-ray pattern analysis. The lattice parameters were a = 10.147(8) Å—for the cubic I23 Bi12MnO20 phase; and a = 7.545(4) Å, b = 8.538(1) Å, c = 5.758(3) Å—for the orthorhombic Pbam BiMn2O5 phase. The 57Fe Mössbauer spectrum, recorded at room temperature, has shown pure electronic quadrupolar split. The major doublets reflected the occurrence of Fe3+ ions distributed in two sites, i.e., octahedral Fe4+O6 and square pyramidal Fe3+O5, with preferential occupation of the pyramidal sites, that was consistent wi…
Thermodynamics of electrokinetic processes—II. systems with different kinds of electrodes
1990
Abstract In this work Haase's Formulation of Electrokinetic Processes is applied to special systems: those working with two different electrodes and those where gaseous phases are formed. Phenomenological equations are always written in terms of directly observable variables. The extrinsic character of Haase's Formulation is clearly shown. Some special results on streaming current in dielectric liquids are explained.
New approaches for the effective valorization of papaya seeds: Extraction of proteins, phenolic compounds, carbohydrates, and isothiocyanates assiste…
2015
Abstract The study compares the efficiency of common aqueous extraction (CE) at different pH (2.5–11) and temperatures (20–60 °C) and extraction assisted by pulsed electric energy (pulsed electric fields, PEF or high voltage electrical discharges, HVED) of nutritionally valuable and antioxidant compounds from papaya seeds. The exponential decay pulses with initial electric field strengths of ≈ 13.3 kV/cm and ≈ 40 kV/cm for PEF and HVED treatments, respectively, were used. The number of pulses n was changed within 1–2000. The impacts of temperature and pH on extraction efficiency of different components (proteins, total phenolic compounds, carbohydrates, isothiocyanates) and antioxidant capa…
Electrolyte Flow and Temperature Calculations in Finite Cylinder Caused by Alternating Current
2006
The distribution of electromagnetic fields, forces and source term of temperature induced by an alternating axially-symmetric system of electric current in a cylinder of a finite length with 6 electrodes has been investigated and calculated in [2, 1].