Resistive Electrical Circuits Research Articles

A mathematical model relating cortical oxygenated and deoxygenated hemoglobin flows and volumes to neural activity

Objective. To describe a toolkit of components for mathematical models of the relationship between cortical neural activity and space-resolved and time-resolved flows and volumes of oxygenated and deoxygenated hemoglobin motivated by optical intrinsic signal imaging (OISI). Approach. Both blood flow and blood volume and both oxygenated and deoxygenated hemoglobin and their interconversion are accounted for. Flow and volume are described by including analogies to both resistive and capacitive electrical circuit elements. Oxygenated and deoxygenated hemoglobin and their interconversion are described by generalization of Kirchhoff's laws based on well-mixed compartments. Main results. Mathematical models built from this toolkit are able to reproduce experimental single-stimulus OISI results that are described in papers from other research groups and are able to describe the response to multiple-stimuli experiments as a sublinear superposition of responses to the individual stimuli. Significance. The same assembly of tools from the toolkit but with different parameter values is able to describe effects that are considered distinctive, such as the presence or absence of an initial decrease in oxygenated hemoglobin concentration, indicating that the differences might be due to unique parameter values in a subject rather than different fundamental mechanisms.

Changing Students’ Epistemological Beliefs and Understanding of Basic Concepts on Electric Circuits

The encouragement of more mature epistemological beliefs is important to student achievement. This study is about epistemological beliefs of students who are enrolled in introductory electricity, magnetism and waves and their understanding of the basic concepts of electric circuits. The students were divided into two groups – one with orientation and one without orientation. To determine the epistemological beliefs of students, the author utilized the Maryland Physics Expectations Survey instrument or (MPEX). The author also utilized Determining and Interpreting Resistive Electric Circuit Concepts Test (DIRECT) to establish the conceptual understanding of students and their misconceptions. To find out the changes in the epistemological beliefs and understanding of students on basic concepts of electric circuits, the pretest-posttest method was employed in the study. Results showed that the level of understanding among students with orientation was more improved than the group without orientation. While the result showed a decline in students’ over-all epistemological beliefs, slight improvements in some dimensions were seen with different dimensions improved or became worse for the two groups. It further showed that repeatedly giving orientation of experts’ epistemological beliefs helped students develop more mature epistemological beliefs that may lead to better learning outcomes. Keywords: electricity, learning, magnetism, orientation, pretest-posttest

Some the Application of the Taylor Series for the Analysis of Processes in Non-Linear Resistive Circuits

The way of calculating the currents and voltages in nonlinear resistive electrical circuits , based on the use of power series (Taylor, Maclaurin) is considered . The advantage of this method lies in the fact that while it implementation it is not necessary to a system of nonlinear equations. To determine the numerical values ​​of the coefficients of the power series corresponding system of linear algebraic equations are solved. Nonlinear operations are limited to the calculation of the numerical values ​​of currents, voltages and their derivatives with respect to the pole equations of nonlinear elements.

Effectiveness ofTutorials for Introductory Physicsin Argentinean high schools

This longitudinal study reports the results of a replication of Tutorials in Introductory Physics in high schools of a Latin-American country. The main objective of this study was to examine the suitability of Tutorials for local science education reform. Conceptual learning of simple resistive electric circuits was determined by the application of the single-response multiple-choice test ``Determining and Interpreting Resistive Electric Circuits Concepts Test'' (DIRECT) to high school classes taught with Tutorials and traditional instruction. The study included state and privately run schools of different socioeconomic profiles, without formal laboratory space and equipment, in classes of mixed-gender and female-only students, taught by novice and experienced instructors. Results systematically show that student learning is significantly higher in the Tutorials classes compared with traditional teaching for all of the studied conditions. The results also show that long-term learning (one year after instruction) in the Tutorials classes is highly satisfactory, very similar to the performance of the samples of college students used to develop the test DIRECT. On the contrary, students following traditional instruction returned one year after instruction to the poor performance ($<20%$) shown before instruction, a result compatible with the very low level of conceptual knowledge of basic physics recently determined by a systematic study of first-year students attending seven universities in Spain and four Latin-American countries. Some replication and adaptation problems and difficulties of this experience are noted, as well as recommendations for successful use of Tutorials in high schools of similar educational systems.

К вопросу анализа процессов в нелинейных резистивных электрических цепях

К вопросу анализа процессов в нелинейных резистивных электрических цепях

The contribution of simulations to the practical work of Foundation Physics students at the University of Limpopo

PurposePractical work is regarded as an essential part of learning; hence most tertiary institutions have included a practical component in their physics courses. There is a concern about the effectiveness of the practical work in most universities. The purpose of this study is to assess the contributions of simulations on 20 Foundation Physics students' practical work at the University of Limpopo.Design/methodology/approachTwo tests, “Determining and interpreting resistive electric circuits concepts test” and the “Test of integrated science process skills” were used. A class test, observation sheet and worksheets for students' practical work were analyzed. Interviews with a selected group of students were also conducted.FindingsResults indicated that the simulations contributed positively on students' understanding of electric circuits. However, the study revealed that the students who did simulations do not differ from those who did not do the simulations with regards to the development of process skills.Originality/valueThe value of this research is the application of simulation in physics with specific testing methods. In addition, the research is unique in a South African context.

전류 모니터를 이용한 백열등 부하 전기설비에서 사고 징후 검출에 관한 연구

본 논문은 백열등 부하 전기설비에서 측정한 전류 파형으로 전기사고 징후를 조기에 검출하기 위한 것이다.BR 첫째, 저항성 회로에서 전류 모니터의 특성을 분석하였다. 둘째, 백열등을 부하로 하는 전기설비를 구축하고, 전기설비의 일부에서 KS C IEC(Korea Standard C International Electrostatic Commission) 60112에 따라 트래킹을 발생시켜 사고를 모의하였다. 전기사고 징후는 전류 모니터로 측정한 전류파형을 분석함으로써 검출되었다.BR 그 결과 부하의 수에 관계없이 사고의 최종 단계인 트래킹으로 진전되어 갈수록 전류 파형에는 점점 큰 전류 펄스가 보였고 출현빈도도 더욱 높아졌다.

Mental Models of Elementary and Middle School Students in Analyzing Simple Battery and Bulb Circuts

Written assessment items were developed to probe students’ understanding of a variety of direct current (DC) resistive electric circuit concepts. The items were used to explore the mental models that grade 3–8 students use in explaining the direction of electric current and how electric current is affected by different configurations of simple battery and bulb circuits. Consistency of applying mental models in different, but equivalent, circuits was also analyzed. Students analyses of current flow direction was categorized into one of two mental models: (1) bidirectional and (2) unidirectional. We found an increase in the consistency of current flow direction mental model use coinciding with grade 4 instruction of batteries and bulbs, however, the proportion of students using a bidirectional flow model was similar in grades 3–8.

Microfluidic circuits with tunable flow resistances

Microfluidic devices, due to their conveniently small size and the unique physicochemical behavior of fluids in microscale volumes, have become essential tools in many areas of science and technology. Fluid flow in microchannels, microvalves, and micropumps have many parallels with electrical current through wires, switches, and current sources of microelectronic circuits. The equivalent of a variable resistor, however, is still unavailable. Here the authors present addressable microarrays of deformable elements producing sixteen levels of flow resistance. Using a purely resistive electrical circuit analog, they predict the steady-state output of a three-inlet mixer.

The effectiveness of the learning‐cycle method on teaching DC circuits to prospective female and male science teachers

This study was undertaken to explore the effectiveness of the learning‐cycle method when teaching direct current (DC) circuits to university students. Four Physics II classes participated in the study, which lasted approximately two and a half weeks in the middle of the spring semester of 2003. Participants were 120 freshmen (55 females and 65 males) from four intact classes. The intact classes were randomly assigned into one of the two treatment groups. The experimental group (n1 = 61, female =30, male = 31) completed a DC circuit unit with the learning‐cycle method, while the control group (n2 = 59, female = 24, male = 35) completed a DC circuit unit with the traditional method. A pretest called Determining and Interpreting Resistive Electric Circuits Concepts Test (DIRECT) was administered to measure students’ pre‐understanding of DC circuit concepts. Then students in both groups completed instruction designed for the groups. All students received the DIRECT again as a post‐test. Finally, experimental group students completed a questionnaire about their perceptions of learning‐cycle method. ANOVA techniques were used to determine if pre‐DIRECT mean scores differed among the groups. The results revealed that the main effect due to treatment did not reach statistical significance, but there was significant difference between female and male students’ pre‐DIRECT mean scores, favoring males. The main effects of treatment and gender on post‐DIRECT mean scores were examined by using ANCOVA techniques with pre‐DIRECT scores used as a covariate. This analysis yielded a significant treatment effect and the effect of gender was eliminated. The learning‐cycle method led to the better understanding of the DC circuit concepts than did traditional method. This finding supports the view that pre‐knowledge mediate gender differences in learning about the DC circuits. The finding of this study suggests that the learning‐cycle method is likely to be effective for both females and males. The findings of the present and previous studies are compared, and the possible effects of the present study’s findings on teaching and learning are discussed.

Students’ understanding of direct current resistive electrical circuits

Both high school and university students’ reasoning regarding direct current resistive electric circuits often differ from the accepted explanations. At present, there are no standard diagnostic tests on electric circuits. Two versions of a diagnostic instrument were developed, each consisting of 29 questions. The information provided by this test can provide instructors with a way of evaluating the progress and conceptual difficulties of their students. The analysis indicates that students, especially females, tend to hold multiple misconceptions, even after instruction. During interviews, the idea that the battery is a constant source of current was used most often in answering the questions. Students tended to focus on the current in solving problems and to confuse terms, often assigning the properties of current to voltage and/or resistance.

On group inverses of M-matrices with uniform diagonal entries

In two recent works the condition of the diagonal entries of the group inverse of a singular and irreducible M-matrix being uniform (constant) has arisen: in resistive electrical circuits and in the effect upon the Perron root of certain diagonal perturbation of a nonnegative matrix. In this paper we first show a negative result that the group inverse of the Laplacian matrix of an undirected weighted graph G on n vertices with a cutpoint cannot have uniform diagonal. This includes the case when G is a tree. We characterize, however, all weighted n-cycles G whose Laplacian has a group inverse with a uniform diagonal. Finally, we consider the mean first passage matrix M of an ergodic Markov chain with a doubly stochastic transition matrix T. We show that if the group inverse of I− T has a uniform diagonal, then the group inverse of the M-matrix ρ( M) I− M is again an M-matrix.

APL and a Black-Box theory of electric circuits

The paper presents the rudiments of a theory of resistive electric circuits viewed as black boxes. The relevant mathematical model is a function mapping voltage vectors to current vectors and having two properties which can be regarded as analogous to Kirchhoff's laws. This treatment of electric circuit theory is unconventional and in fact appears to be new. The purpose of the paper is not to develop the theory itself but to show the convenience and precision of the APL notation in such a theory, and also to illustrate the need, even in a relatively simple application, for general arrays of functions and numbers, and for a notation for and a means of specifying user-defined operators.