Electric Circuit (electric + circuit)

Distribution by Scientific Domains


Selected Abstracts


A direct circuit experiment system in non-immersive virtual environments for education and entertainment

COMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2005
Quang-Cherng Hsu
Abstract This article proposes to contribute to the goal of "The Popular Science Teaching Research Project" as well as to enhance the programming abilities of mechanical engineering students. Topics being included as example are in physical science, which include battery, lamp, and electric circuit. These materials are designed, based on virtual-reality technology that is suitable for students as early as fourth-grade students of primary school. It will help the students become familiar with new computer technology and provide an opportunity to study while playing virtual reality computer games. The benefits of the developed application software system of virtual reality are virtualization of teaching equipment, cost reduction of teaching materials, unlimited teaching style, and optimization of learning procedures. © 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 146,152, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20044 [source]


Low-frequency dielectric spectroscopy as a tool for studying the compatibility between pharmaceutical gels and mucous tissue

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2003
Helene HäGerström
Abstract This interdisciplinary work demonstrates how low-frequency dielectric spectroscopy, a technique that is frequently used within physics, can be used to assess the possibilities of intimate surface contact between a polymer gel and mucous tissue, which is generally considered to be the first step in the mucoadhesion process. The dielectric responses of five different gels, of freshly excised porcine nasal mucosa and of systems made by combining the two were measured. All spectra were modeled by a Randles electric circuit containing a diffusion element, a barrier resistance in parallel with a capacitance, and a high-frequency resistance. The results were used to create a measure of the compatibility between the gel and the mucus, which we have named the compatibility factor. Thus, the compatibility factor provides us with a measure of the ease with which a charged species passes the interface between a gel and the mucus layer. The compatibility factor is calculated from the high frequency (kHz region) response of the gel, of the mucosa, and of the combined system. The two highest compatibility factors in this study were obtained for gels based on crosslinked poly(acrylic acid) and chitosan, which was in agreement with the results from mucoadhesion measurements that were performed using a tensile strength method. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:1869,1881, 2003 [source]


Promoting fourth graders' conceptual change of their understanding of electric current via multiple analogies

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 4 2005
Mei-Hung Chiu
For the past two decades, a growing amount of research has shown that the use of analogies in science teaching and learning promotes meaningful understanding of complex scientific concepts (Gentner, 1983; Glynn, 1989; Harrison & Treagust, 1993; Wong, 1993). This article presents a study in which multiple analogies were used as scaffolding to link students' prior understanding of daily life events to knowledge of the scientific domain. The study was designed to investigate how multiple analogies influence student learning of a complex scientific concept: the electric circuit. We used several analogies in a set of learning materials to present the concepts of parallel and series circuits. Thirty-two fourth graders participated in this study and were randomly assigned to four groups. The four groups were named nonanalogy (control), single analogy, similar analogies, and complementary analogies, according to the materials they used in this study. The results demonstrated that using analogies not only promoted profound understanding of complex scientific concepts (such as electricity), but it also helped students overcome their misconceptions of these concepts. In particular, we found that the reason the students had difficulty understanding the concept of electricity was because of their ontological presupposition of the concept. Implications for teaching and learning are discussed. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 429,464, 2005 [source]


Investigation of the physical mechanisms in rolling bearings during the passage of electric current

LUBRICATION SCIENCE, Issue 4 2005
A. Jagenbrein
Abstract With the increasing use of frequency converters as control units for electric motors, bearing failures caused by the passage of electric current through the bearings are more common. This paper discusses the most relevant parasitic current loops in frequency converter-driven motors that can lead to damage of bearing raceways or deterioration of lubricants. Electrical stray capacitances, which are inevitably present in any electric motor, in combination with the high-frequency components of the drive voltages, have been identified as the source of electric discharge machining (EDM) currents. Based on an EDM equivalent electric circuit, the passage of electric current through the rolling contact of a bearing is simulated. A set-up is introduced to initiate EDM processes in bearings under well-controlled electrical and mechanical conditions. The effect of EDM currents on bearing elements in the presence of different lubricants is studied. Initial results are presented. [source]


In-line optical detection in the transient state of extrusion polymer blending and reactive processing,,

POLYMER ENGINEERING & SCIENCE, Issue 1 2005
Tomás Jeferson A. Mélo
Using an opticaldetector we followed the transient state of blends and composites, including a reactive blending during extrusion. The detection system is composed of a slit-die with transparent windows fixed at the extruder exit, an optical arrangement with a W incandescent light microbulb with fixed luminescence, and a CdS photocell. As the tracer passes though the light path, it absorbs and backscatters part of the light, reducing the total transmitted light intensity. This is followed by changes in the voltage induced by the photocell to an electric circuit. We calibrated the response of the photocell at room temperature using a set of various films with a second phase dispersed, and obtained a logarithmic relationship. The tracers were particulate (phthalocyanine, TiO2) and polymeric (PS, PA6) phases that absorb and scatter light, producing a residence time distribution (RTD) curvelike trace. Measurements were taken from a twin-screw extruder Werner-Pfleiderer ZSK 30 equipped with K-Tron gravimetric feeders operating at various screw configurations and speeds, and feeding rates. The transient state of PP/PA6 blends can be easily detected optically and recorded using one of the components (either PP or PA6) added as a pulse in a steady-state flow of the other component. With the simultaneous addition of a compatibilizer (polypropylene grafted with acrylic acid (PP-g-AA)) with the PA6, the intensity of the detector signal is substantially increased as a result of the PA6/PP-g-AA reaction. Quantitative off-line infrared spectroscopy of the total amide group corroborated the in-line measurements. These observations suggest that an in-line optical detector may be a fast and simple way to study the flow behavior of blends and composites, including reactive processing. POLYM. ENG. SCI. 45:11,19, 2005. © 2004 Society of Plastics Engineers. [source]


An optical device to measure in-line residence time distribution curves during extrusion

POLYMER ENGINEERING & SCIENCE, Issue 1 2002
Tomás Jeferson A. Mélo
This paper proposes a setup for in-line measurement of residence time distribution (RTD) curves during extrusion. The detection system is composed of a slit die with transparent borosilicate glass windows fixed at the extruder exit, an optical arrangement with an incandescent light microbulb with fixed luminescence, and a Light Dependent Resistor (LDR) photocell of CdS. As the tracer passes through the light path, the reduction in the transmitted light intensity is followed by changes in the voltage induced by the photocell to an electric circuit. The signal is collected by an external interface and sent to a computer. Software acquires the data, does all calculations, and presents all curves and calculated variables to the monitor. The validation of the system was done by checking for data reproducibility and linearity with tracer concentration. The response of the LDR sensor with respect to the concentration of the tracer was calibrated using a set of slight dark film, obtaining a logarithmic relationship. Thus the signal enhances any disturbance, if present, particularly in the tail-region of the curves. Measurements were taken from a Werner-Pfleiderer ZSK 30 twin-screw extruder equipped with K-Tron gravimetric feeders operating with various screw speeds, feeding rates and screw configurations. In this last case, the presence of kneading elements was taken into account. [source]


Periodic noise analysis of electric circuits: Artifacts, singularities and a numerical method

INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 7 2010
Angelo Brambilla
Abstract In this paper it is shown that a numerical method largely adopted for the simulation of noise in autonomous circuits is affected by singularities that manifest when the frequency at which the noise analysis is carried out approaches a harmonic of the autonomous circuit. The resulting noise power spectral density (PSD) is thus characterized by spurious spikes. The presence of these singularities is for the first time justified from an analytical standpoint and their effects are shown by simulating some oscillators, employed as benchmarks. Furthermore, the presented approach justifies the 1/(fs,f)2 shape of the PSD of noise at the output when the fs frequency approaches the f fundamental of a stable oscillator and the 1/|fs,f|3 shape when the effects of flicker noise are manifest. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Simulation , a bridge between theory and reality: the case of electric circuits

JOURNAL OF COMPUTER ASSISTED LEARNING, Issue 1 2000
M. Ronen
Abstract This study aimed to examine the role of a simulation as a potential aid that may help students bridge the gap between theory and reality, in the case of electric circuits. Sixty-three pairs of students aged about 15 years were presented with two tasks involving real circuits. An open simulation environment was available as an optional aid for the experimental group. Significant differences were found between the achievements of the groups. The use of the simulation contributed to students' confidence and enhanced their motivation to stay on-task. The detailed analysis revealed the role of the simulation as a source of constructive feedback, helping students identify and correct their miscon-ceptions and cope with the common difficulties of relating formal representations to real circuits and vice versa. [source]


Factors mediating the effect of gender on ninth-grade Turkish students' misconceptions concerning electric circuits

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 6 2004
Selen Sencar
This study was designed to identify and analyze possible factors that mediate the effect of gender on ninth-grade Turkish students' misconceptions concerning electric circuits. A Simple Electric Circuit Concept Test (SECCT), including items with both practical and theoretical contexts, and an Interest-Experience Questionnaire about Electricity (IEQ) were administered to 1,678 ninth-grade students (764 male, 914 female) after the completion of a unit on electricity to assess students' misconceptions and interests-experiences about electricity. Results of the concept test indicated that general performances of the students were relatively low and that many students had misconceptions in interpreting electric circuits. When the data were analyzed using MANOVA and follow-up ANOVAs, a gender difference for males was observed on the dependent variable of total scores on the 10 practical items; however, there was no significant gender difference on the dependent variable of total scores on the six theoretical items. Moreover, when the same data were analyzed using MANCOVA and follow-up ANCOVAs, controlling students' age and interest-experience related to electricity, the observed gender difference was mediated on the total scores on the practical items. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 603,616, 2004 [source]