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Analysis and Measurement of Anti-Reciprocal Systems By
ANALYSIS AND MEASUREMENT OF ANTI-RECIPROCAL SYSTEMS BY NOORI KIM DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering in the Graduate College of the University of Illinois at Urbana-Champaign, 2014 Urbana, Illinois Doctoral Committee: Associate Professor Jont B. Allen, Chair Professor Stephen Boppart Professor Steven Franke Associate Professor Michael Oelze ABSTRACT Loudspeakers, mastoid bone-drivers, hearing-aid receivers, hybrid cars, and more – these “anti-reciprocal” systems are commonly found in our daily lives. However, the depth of understanding about the systems has not been well addressed since McMillan in 1946. The goal of this study is to provide an intuitive and clear understanding of the systems, beginning from modeling one of the most popular hearing-aid receivers, a balanced armature receiver (BAR). Models for acoustic transducers are critical in many acoustic applications. This study analyzes a widely used commercial hearing-aid receiver, manufactured by Knowles Electron- ics, Inc (ED27045). Electromagnetic transducer modeling must consider two key elements: a semi-inductor and a gyrator. The semi-inductor accounts for electromagnetic eddy cur- rents, the “skin effect” of a conductor, while the gyrator accounts for the anti-reciprocity characteristic of Lenz’s law. Aside from the work of Hunt, to our knowledge no publications have included the gyrator element in their electromagnetic transducer models. The most prevalent method of transducer modeling evokes the mobility method, an ideal transformer alternative to a gyrator followed by the dual of the mechanical circuit. The mobility ap- proach greatly complicates the analysis. The present study proposes a novel, simplified, and rigorous receiver model. -
Causes of Poor Performance in West African School Certificate
Ogundele GA et al.; Sch. J. Arts. Humanit. Soc. Sci. 2014; 2(5B):670-676. Scholars Journal of Arts, Humanities and Social Sciences ISSN 2347-5374 (Online) Sch. J. Arts Humanit. Soc. Sci. 2014; 2(5B):670-676 ISSN 2347-9493 (Print) ©Scholars Academic and Scientific Publishers (SAS Publishers) (An International Publisher for Academic and Scientific Resources) Causes of Poor Performance in West African School Certificate Examination (WASCE) in Nigeria Ogundele, Gbenga Alexander1, Olanipekun, Shola Sunday2, Aina, Jacob Kola3 1Department of Metal Work, 2General Studies Education Department, 3Physics Education Department, College of Education (Tech.), Lafiagi, P.M.B. 001, Kwara State, Nigeria. *Corresponding Author: Aina, Jacob Kola Email: Abstract: This is a review paper that cantered on poor academic performance generally in the West Africa Senior School Certificate Examination which has become a great concern to various stakeholders in the educational sector, most especially in Nigeria. The paper argued that mass failure of students in public examinations could be traced to several factors that can be compartmentalized into the domains of parents, students, teachers, schools, the language of instruction, government and the society among others. In other words, the causes of mass failure of students in public examinations are multi-dimensional in nature. The paper concluded that mass failure of students in public examinations constitutes wastage on investment in secondary education. The paper recommended that since academic performance is a virile instrument to the national development of any nation; all concerned stakeholders must be responsive to their roles in order to restore hope to the current grotesque academic performance of students in WAEC in Nigeria. -
ELEC-E5650 Electroacoustics
ELEC-E5650ELECElectroacoustics-E5650 ElectroacousticsLecture 1: Overview, Electroacoustics introduction & Circuit Elements pt1 Lecture 2: SteadyRaimundo -GonzalezState Analysis / Dynamic Analogies Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering Raimundo2 2GonzalezFebruary 2018 Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering March 7, 2019 ELEC-E5650 Electroacoustics, Lecture 1 Raimundo Gonzalez 1 Aalto, Signal Processing & Acoustics ELEC-E5650 ElectroacousticsLecture 1: Overview, Electroacoustics introduction & Circuit Elements pt1 LectureRaimundo Gonzalez 2: Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering 22 February 2018 I. Steady State Analysis ELEC-E5650 Electroacoustics, Lecture 1 Raimundo Gonzalez 2 Aalto, Signal Processing & Acoustics Steady state sinusoidal response When designing Electroacoustics systems we are usually more interestedELEC in the-E5650 steady state behavior of the system. This will ElectroacousticsLecture 1: Overview, Electroacoustics introduction & Circuit Elements pt1 lead into Raimundomostly Gonzalez working in the frequency domain. Department of Signal Processing and Acoustics Aalto University School of Electrical Engineering 22 February 2018 ELEC-E5650 Electroacoustics, Lecture 1 Raimundo Gonzalez Aalto, Signal Processing & Acoustics 3 Phasors to represent sinusoidal signals ELEC-E5650 ElectroacousticsLecture 1: Overview, Electroacoustics introduction & Circuit Elements -
Aspectos De Relatividade Numérica Campos Escalares E Estrelas De Nêutrons
UNIVERSIDADE DE SÃO PAULO INSTITUTO DE FÍSICA Aspectos de Relatividade Numérica Campos escalares e estrelas de nêutrons Leonardo Rosa Werneck Orientador: Prof. Dr. Elcio Abdalla Uma tese apresentada ao Instituto de Física da Universidade de São Paulo como parte dos requisitos necessários para obter o título de doutor em Física. Banca examinadora: Prof. Dr. Elcio Abdalla (IF-USP) – Presidente da banca Prof. Dr. Arnaldo Gammal (IF-USP) Prof. Dr. Daniel A. Turolla Vanzela (IFSC-USP) Prof. Dr. Alberto V. Saa (IFGW-UNICAMP) Profa. Dra. Cecilia Bertoni Chirenti (UFABC/UMD/NASA) São Paulo 2020 FICHA CATALOGRÁFICA Preparada pelo Serviço de Biblioteca e Informação do Instituto de Física da Universidade de São Paulo Werneck, Leonardo Rosa Aspectos de relatividade numérica: campos escalares e estrelas de nêutrons / Aspects of Numerical Relativity: scalar fields and neutron stars. São Paulo, 2020. Tese (Doutorado) − Universidade de São Paulo. Instituto de Física. Depto. Física Geral. Orientador: Prof. Dr. Elcio Abdalla Área de Concentração: Relatividade e Gravitação Unitermos: 1. Relatividade numérica; 2. Campo escalar; 3. Fenômeno crítico; 4. Estrelas de nêutrons; 5. Equações diferenciais parciais. USP/IF/SBI-057/2020 UNIVERSITY OF SÃO PAULO INSTITUTE OF PHYSICS Aspects of Numerical Relativity Scalar fields and neutron stars Leonardo Rosa Werneck Advisor: Prof. Dr. Elcio Abdalla A thesis submitted to the Institute of Physics of the University of São Paulo in partial fulfillment of the requirements for the title of Doctor of Philosophy in Physics. Examination committee: Prof. Dr. Elcio Abdalla (IF-USP) – Committee president Prof. Dr. Arnaldo Gammal (IF-USP) Prof. Dr. Daniel A. Turolla Vanzela (IFSC-USP) Prof. -
Modeling of the Electroacoustic Coupling of Electrostatic Microphones Including the Preamplifier Circuit
Electroacoustics and Audio Engineering: Paper ICA2016-193 Modeling of the electroacoustic coupling of electrostatic microphones including the preamplifier circuit Bernardo Henrique Pereira Murta(a), Eric Brandão(b), Julio Cordioli(c), William D’A. Fonseca(d), Paulo H. Mareze(e) (a, b, d, e)Federal University of Santa Maria, Acoustical Engineering, Santa Maria, RS, Brazil, [email protected], [email protected] (c)Universidade Federal de Santa Catarina, Florianópolis, Brazil, [email protected] Abstract: This research aims to study tools to model and design electrostatic microphones coupled with its preamplifier circuits. The outcome is the access to their combined sensitivities curves, which allows the design of microphones with a wider and flat bandwidth. Analytical and numerical mod- eling techniques are explored and compared. On one hand, the lumped parameters approach is the basis of the analytical modeling of acoustic transducers. That is, this technique allows the engineer to design the transducer and its preamplifier circuit by predicting its sensitivity changes due to variations of model properties with low computational cost. On the other hand, numerical analysis is carried out using the Finite Element Method with a multiphysics approach, which is able to solve both the transducer model and the coupled electrical circuit. Two microphones with different complexities and constructive characteristics are studied. For validation of the proposed techniques, the behavior of a commercial measurement microphone model that has been well studied in the literature is considered. Once the validation of the modeling approach is satisfac- tory, one can use the same methodology to study a piezoelectric microphone for hearing aid applications, for instance. -
High-Stakes Standardized Testing in Nigeria and the Erosion of a Critical African Worldview
HIGH-STAKES STANDARDIZED TESTING IN NIGERIA AND THE EROSION OF A CRITICAL AFRICAN WORLDVIEW by Ijeoma Ekoh A thesis submitted in conformity with the requirements for the degree of Master of Arts Graduate Department of Humanities, Social Sciences and Social Justice Education Ontario Institute for Studies in Education University of Toronto © Copyright by Ijeoma Ekoh 2012 HIGH-STAKES STANDARDIZED TESTING IN NIGERIA AND THE EROSION OF A CRITICAL AFRICAN WORLDVIEW Masters of Arts 2012 Ijeoma Ekoh Graduate Department of Humanities, Social Sciences and Social Justice Education University of Toronto Abstract This thesis investigates the practice of high-stakes standardized testing in Nigeria. Examining its colonial histories, its philosophical incongruities with African indigenous education, and its neocolonial foundations, it argues that high-stakes testing in Nigeria facilitates the erosion of a critical African worldview. It demonstrates that through high- stakes testing’s reproduction of social and regional inequalities, the unethicality of its systems and practices as well as its exemplification of Freire’s concept of normative and non liberatory education as the “practice of domination”; high-stakes standardized testing in Nigeria seamlessly fits into the neo-colonial and neoliberal logic of education as a site of psychological colonization and the material exploitation of the people by the ruling elite. ii Acknowledgements Ajamu. You serve as a daily reminder that ideology must be lived, and that theorizing must be accompanied with concrete political action. Your conviction that there can, and must be, a better tomorrow for African peoples and your daily activism to make that possible inspires me. Ifunanya and Ikenna Ekoh. -
There Is No Special Condition Where a Velocity of a Light Wave Is Invariance in All Inertial Frames
There is no special condition where a velocity of a light wave is invariance in all inertial frames. Mahesh Gupta ( [email protected] ) Madurai Kamaraj University https://orcid.org/0000-0002-1772-8490 Prafful Acharya Amrita Vishwa Vidyapeetham University Rampravesh Yadav University of Mumbai Article Keywords: Frame of Reference, The Time, Newton’s Law of motion, Galilean Transformation, Linear Motion, Periodic Motion, Particle-Wave Duality of Light, Lorentz Transformation, Special Theory of Relativity Posted Date: January 15th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-143936/v2 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License There is no special condition where a velocity of a light wave is invariance in all inertial frames. Mahesh Gupta, Prafful Acharya & Rampravesh R. Yadav [email protected] Mumbai, Maharashtra, India Abstract: This study of the literature reveals that the concept such as the velocity of a light wave is invariance in all inertial frames is wrong. A velocity of any motion always depends upon its reference frame. There is no special condition present in nature where the velocity is invariance in all inertial frames. Galileo Galilei defined speed is the distance covered per unit of time. Sir Isaac Newton defined velocity is the speed with direction. In the same period, physicists introduced the concept such as wavelength and frequency for measuring the speed a wave. The wave motion in which cycles are repeating after the same interval of time with the same distance between them. In 1887, Albert A. Michelson and Edward W. -
Application Notes
Application Note Accurate Determination of Loudspeaker Parameters using Audio Analyzer Type 2012 and Laser Velocity Transducer Type 3544 by Søren Jønsson, Brüel & Kjær, Denmark A method to determine the parame- ters characterising low frequency, mid- range and high frequency loudspeaker units is presented. A laser velocity transducer is used to detect the veloc- ity of the diaphragm. All measure- ments are made with the loudspeaker in free air. The method uses an im- proved model of the loudspeaker and takes into account the frequency de- pendent behaviour of some of the ele- ments. It produces accurate results and is easy to implement compared with conventional methods. The proce- dure is fully automated using an au- tosequence program for the analyzer. The process of automation is discussed and results of a typical driver are in- cluded. 1. Introduction Over the last two decades, it has be- The method presented here is a ance. From these functions the loud- come almost an industrial standard compilation of the traditional method speaker parameters can be calculated. to measure the parameters of a loud- and the method introduced by Applying the post-processing capa- speaker by the method introduced by J. N. Moreno [6]. It uses an improved bilities of the analyzer to the meas- A.N. Thiele and Dr. Richard Small [1 model of the loudspeaker and takes ured data, it is shown how to correct & 2]. various non-linearities in frequency the loudspeaker parameters and ex- Since the method was introduced, into account. The method produces tract information about the frequency more research in loudspeaker model- accurate results regardless of the dependent behaviour of some of the ling has been made, (e.g., [3, 4 & 5], components in the equivalent circuit type of driver used. -
Analysis and Design of Piezoelectric Sonar Transducers. Rodrigo, Gerard Christopher
Analysis and design of Piezoelectric sonar transducers. Rodrigo, Gerard Christopher The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author For additional information about this publication click this link. http://qmro.qmul.ac.uk/jspui/handle/123456789/1712 Information about this research object was correct at the time of download; we occasionally make corrections to records, please therefore check the published record when citing. For more information contact [email protected] -1- ANALYSIS AND DESIGN OF PIEZOELECTRIC SONAR TRANSDUCERS Gerard Christopher Rodrigo Department of Electrical and Electronic Engineering, Queen Mary College, London E.l. Thesis presented for the Degree of Doctor of Philosophy of the University of London August 1970 -2- ABSTRACT In this study techniques are developed for the analysis and design of piezoelectric sonar transducers based on equivalent circuit representations. For the purposes of analysis, equivalent circuits capable of accurately representing every element of a transducer in the full operating frequency range, are developed. The most convenient fashion in which these equivalents could be derived is also discussed. For the purposes of design the accurate equivalents are approximated by L-C-R circuits. The limits of both representations are discussed in detail. The technique of analysis developed is capable of determining the frequency characteristics as well as the transient response to any electrical or acoustic input which can be specified analytically or numerically in the time domain. The design technique is based on the formulation of a ladder-type generalized circuit incorporating the essential components of any transducer. -
Special Relativity: a Reexamination of the Second Postulate and of Space Contraction and Time Dilation
Special Relativity: A Reexamination of the Second Postulate and of Space Contraction and Time Dilation Paul A. Klevgard, Ph.D. Sandia National Laboratory, Ret. [email protected] Abstract Pure entities consist of mass or energy without the presence of the other: the inertial rest mass is all mass and no kinetic energy (no velocity); the photon is all kinetic energy and no (rest) mass. Pure entities may be compared at the ontological level (for form, progression in a dimension, extension in a dimension and storage). From this analysis it is shown that Einstein’s second postulate of special relativity (constant speed of light) is actually derivative from a more fundamental attribute of all pure entities. Part two of this essay focuses on the space contraction and time dilation of moving physical objects. Arguments against attributing these changes to space and time itself (Minkowski) are offered. Instead, the roles of kinetic energy and of de Broglie wave effects are presented as a better explanation. Special relativity has been with us for over a century and its predictions have been confirmed by countless experiments. Nevertheless, its conceptual and ontological foundations are not completely satisfactory. This essay will offer a critical review of two main aspects of special relativity: 1) the desirability/validity of erecting a postulate for a single phenomenon, namely the constant speed of light, and 2) the challenge of explaining why different inertial observers measure space and time differently (space contraction, time dilation). But one cannot analyze special relativity without considering the photon and the nature of radiant energy. Hence this essay will also look at how radiation went from quantity to entity. -
Analysis and Measurement of Anti-Reciprocal Systems
University of Illinois, Urbana-Champaign Electrical and Computer Engineering Department The Doctoral Preliminary Examination Document Analysis and measurement of anti-reciprocal systems Committee: Associate Professor Jont B. Allen Author: (Advisor, Chair) Noori Kim Professor Stephen Boppart (UIN:677205530) Professor Steven Franke Associate Professor Michael Oelze October 12, 2014 1 Abstract 2 Loudspeakers, mastoid bone-drivers, hearing-aid receivers, hybrid cars, and more - these 3 “anti-reciprocal” systems are commonly found in our daily lives. However, the depth of un- 4 derstanding about the systems has not been well addressed since McMillan in 1946. The goal 5 of this study is to guide an intuitive and clear understanding of the systems, beginning from 6 modeling one of the most popular hearing-aid receivers, a balanced armature receiver (BAR). 7 Models for acoustic transducers are critical in many acoustic applications. This study ana- 8 lyzes a widely used commercial hearing-aid receiver ED series, manufactured by Knowles Elec- 9 tronics, Inc. Electromagnetic transducer modeling must consider two key elements: a semi- 10 inductor and a gyrator. The semi-inductor accounts for electromagnetic eddy-currents, the 11 “skin effect” of a conductor (Vanderkooy, 1989), while the gyrator (McMillan, 1946; Tellegen, 12 1948) accounts for the anti-reciprocity characteristic [Lenz’s law(Hunt, 1954, p. 113)]. Aside 13 from Hunt (1954), to our knowledge, no publications have included the gyrator element in their 14 electromagnetic transducer models. The most prevalent method of transducer modeling evokes 15 the mobility method, an ideal transformer alternative to a gyrator followed by the dual of the 16 mechanical circuit (Beranek, 1954). -
Modeling of MEMS Piezoelectric Energy Harvesters Using Electromagnetic and Power System Theories
Modeling of MEMS piezoelectric energy harvesters using electromagnetic and power system theories Mahmoud Al Ahmad1, Amro M. Elshurafa2, Khaled N. Salama2 and H. N. Alshareef1,* 1 Material Sciences and Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science & Technology (KAUST), Thuwal, Saudi Arabia, 23955-6900. 2 Electrical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science & Technology (KAUST), Thuwal, Saudi Arabia, 23955-6900. *Corresponding author: [email protected] Abstract This work proposes a novel methodology for estimating the power output of piezoelectric generators. An analytical model that estimates, for the first time, the loss ratio and output power of piezoelectric generators, based on the direct mechanical-to-electrical analogy, electromagnetic theory, and power system theory, is developed and takes into account the dimensions and material properties of the generator. The mechanical-to-electrical analogy and power system theory allow deriving an equivalent input impedance expression for the network. Further, electromagnetic theory allows deducing the equivalent electromechanical loss of the piezoelectric generator. By knowing the mechanical input power and the loss of the network, calculating the output power of the piezoelectric device becomes a straightforward procedure. Experimental results based on published data are also presented to validate the analytical solution. Moreover, and to fully benefit from the well established electromagnetic and electric circuit theories, further analysis efforts on the resonant frequency, bandwidth, and sensitivity are presented. Compared to conventional modeling methods currently being adopted in the literature, the proposed method provides, relatively easily, significant additional information that is crucial for enhanced device operation. Finally, and with the study provided in this paper, optimizing piezoelectric harvesters is simplified.