Rolling Railgun: A Lab Activity for Introductory Electromagnetism

2020 ◽  
Vol 02 (04) ◽  
pp. 2050017
Author(s):  
James Overduin ◽  
Taylor Pettaway ◽  
Hannah Clark ◽  
Mark Edmonston
Keyword(s):  
The Other ◽  
Laboratory Exercise ◽  
Electricity And Magnetism ◽  
Comprehensive Comparison ◽  
Introductory Calculus ◽  
Theory And Experiment

We describe a laboratory exercise for an introductory calculus-based electricity and magnetism course in which students construct and study the performance of a “rolling railgun” formed by two small coin magnets connected by a ferromagnetic axle which carries current from one rail to the other. This exercise can be scaled up from a simple, mostly qualitative activity to a more comprehensive comparison between theory and experiment that will challenge students’ calculus skills. The required components are small and inexpensive enough to mail to students who are taking the course remotely. We report on our initial success in incorporating this lab into our curriculum at Towson University.

scholarly journals Neomillspaughia hondurensis (Polygonaceae), a new species from Central America

Phytotaxa ◽  
2013 ◽  
Vol 144 (2) ◽  
pp. 56
Author(s):  
JUAN JAVIER ORTIZ-DÍAZ ◽  
ITZIAR ARNELAS ◽  
JUAN TUN ◽  
JOSÉ SALVADOR FLORES
Keyword(s):  
New Species ◽  
Central America ◽  
The Other ◽  
Comprehensive Comparison ◽  
Species Being ◽  
A New Species

A new species Neomillspaughia hondurensis (Polygonaceae) from Honduras is described and illustrated. This species is morphologically and ecollogicaly different from the other two currently known Neomillspaughia species, being more related to N. emarginata than to N. paniculata. A comprehensive comparison and a key for the three species are provided. Se describe e ilustra la nueva especie Neomillspaughia hondurensis (Polygonaceae) de Honduras. Esta especie es morfológicamente y ecológicamente diferente de las dos únicas especies de Neomillspaughia, estando más relacionada con N. emarginata que con N. paniculata. Se proporciona información comparativa de la nueva especie con las especies relacionadas y una clave para la identificación de las mismas.

A Developed Structure for DC–DC Quasi-Z-Source Converter with High Voltage Gain and High Reliability

2018 ◽  
Vol 28 (01) ◽  
pp. 1950012 ◽  
Author(s):  
Ebrahim Babaei ◽  
Mohammad Shadnam Zarbil ◽  
Elias Shokati Asl
Keyword(s):  
Computer Aided Design ◽  
High Reliability ◽  
Stage Structure ◽  
The Other ◽  
Voltage Gain ◽  
Operating Modes ◽  
High Voltage Gain ◽  
Comprehensive Comparison ◽  
Simulation Results ◽  
Aided Design

In this paper, a developed structure for DC–DC quasi-Z-source (QZS) converters is proposed. First, the proposed two-stage structure is presented and analyzed. Then, the proposed structure is extended to [Formula: see text] stages and its relations are calculated. Compared with other conventional structures, the proposed structure has higher voltage gain and higher reliability. The proposed topology is suitable for high power applications. To have the correct performance of conventional QZS converter, all impedance network elements must be intact. In the case of small failure in one of the elements, the operation of the whole system is disrupted. The proposed structure has high reliability because when one stage fails, the fault management system separates that stage from the other stages and the remaining stages continue to transmit power. In this paper, in addition to analyzing the operation of the proposed converter in different operating modes, calculations of voltage gain, voltage stresses across capacitors and reliability analysis are also presented. Reliability is calculated according to well-known Markov model. Moreover, a comprehensive comparison in terms of voltage gain and reliability is made between the proposed converter and the other conventional structures. Also, the rating values of inductors and capacitors are designed. Finally, experimental and simulation results are presented by using power system computer-aided design (PSCAD) software to verify the theories.

III. On the conductivity of mercury and amalgams

1860 ◽  
Vol 10 ◽  
pp. 14-16
Keyword(s):  
The Other ◽  
Warm Water ◽  
The Real ◽  
The Law ◽  
Theory And Experiment ◽  
As If

The object of the researches described in this paper, was to carry out with reference to amalgams the investigations relative to alloys contained in a former paper. In comparing the results of theory and experiment in the manner followed in the former paper, the conducting power of mercury itself was a constant, which it was essential to know. The figure given in the former paper was mercury = 677, on the scale silver = 1000. On adopting in the first instance this value of the conducting power of mercury, the results obtained with alloys, which consisted mainly of mercury, appeared very anomalous; it seemed as if a very small per-centage of even the best conducting metals reduced immensely the conducting power of mercury. But it was suggested to the authors, that the apparently high conducting power of mercury obtained by their method, was probably due to the transference of heat by convection; that the real conducting power of mercury for heat was low, like its conducting power for electricity; that the other metal, contained in small quantity in the amalgam, acted by rendering the amalgam viscous, and thereby interfering with the transference of heat by convection, and that the low conducting power of mercury would show itself on merely inclining the vessel used in the experiment, so that the box containing the warm water should be higher than the other. Experiment confirmed this view. As the apparent conducting power of mercury was found continually to decrease with an increase in the inclination of the vessel, it was found necessary, in order to obtain correct results, to arrange so that the bar-shaped box containing the mercury or fluid amalgam was actually vertical in the experiment. In this way the authors obtained for mercury the figure 54, on the same scale as before. It is worthy of remark, that mercury comes out the worst conductor of all the metals tried, the figure for bismuth, which had previously been the lowest, being 61. This is in analogy with water, also a fluid, the conducting power of which is known to be excessively low. The conducting power of the more fluid amalgams determined by experiment with the box vertical, proved to be in all cases nearly the same as that of pure mercury, in conformity with the law mentioned by the authors in their former paper, that alloys in which there is an excess of the number of equivalents of the worse conducting metal, over the number of equivalents of the better conductor, do not sensibly differ in conducting power from the worse conductor alone. In the case of amalgams generally, the conducting power obtained by experiment was found to agree pretty closely with the number calculated from the per-centages and conducting powers of the component metals.

What may theoreticians and electron microscopists learn from each other about phase transformations?

1988 ◽  
Vol 46 ◽  
pp. 754-755
Author(s):  
K.C. Russell
Keyword(s):  
Phase Transformation ◽  
Common Ground ◽  
Particle Number ◽  
Particle Number Density ◽  
The Other ◽  
Nucleation Theory ◽  
Constant Number ◽  
Number Density ◽  
Solid State Phase Transformation ◽  
Theory And Experiment

Plenty! Unfortunately theoreticians and experimentalists generally live in separate worlds, if not universes, and are oftentimes happier that way. Dealing with the other party requires work, both to master unfamiliar concepts and to develop one's research in the direction and to the point that the other can understand and deal with it. More usually the theorists make predictions on what pleases them while the experimentalists measure the quantities which please them. The overlap between the two sets is often minimal, and sometimes nil.Real cooperation and learning occurs when each develops his research product to the point that it is useful to the other, and in addition can explain his needs to the other.Unfortunately, sometimes in spite of the best of efforts common ground cannot be found. I refer in particular to early attempts in solid state phase transformation studies to relate nucleation theory and experiment. The theorist typically views the progress of a phase transformation as starting with an incubation period after which steady state nucleation conditions are established and the particle number density increases linearly with time. Then nucleation ceases and the particles grow at constant number density. Finally coarsening occurs and the number density decreases with time while the remaining particles get bigger.

Modelling WSNs Using OMNeT++

2012 ◽  
pp. 319-340 ◽  
Author(s):  
Erwin Anggadjaja ◽  
Ian V. McLoughlin
Keyword(s):  
Wireless Sensor Networks ◽  
System Design ◽  
Failure Modes ◽  
The Other ◽  
Wireless Sensor ◽  
Trade Off ◽  
Sensing Systems ◽  
Trade Offs ◽  
Comprehensive Comparison ◽  
Potential Failure

Wireless sensor networks (WSNs) have been used to observe and monitor many environments for specific purposes and in many ways over the past few years. A number of operational trade-offs are possible when planning a WSN, influencing coverage, bandwidth, redundancy, lifetime, expandability, and so on. However, for systems in potentially hazardous locations or those experiencing restricted access, system unreliability tends to be the greatest operational concern. In the process of creating reliable WSNs for hazardous locations, it is highly desirable to ensure both an accurate and a reliable system design prior to deployment, and with as little unnecessary trade-off as possible. Especially as sensing systems become larger and more complex, and potential failure modes increase, this becomes more difficult to achieve. In an attempt to answer the question of reliability assurance, the authors investigate WSNs in the context of accurate and fast modelling of such networks. A comprehensive comparison of three modelling tools (ns-2, OPNET, and OMNeT++) is explored in this chapter, concluding that OMNeT++ is worthy of study as an alternative to the other two more established tools. As an illustration of the use of OMNeT++, two modelling schemes are simulated and compared against the theory to determine both bit-level correctness, but also to demonstrate ease of modelling and analysis.

Vibration Control of a String Using Zero-Displacement Constraint at a Point Near One Boundary: Theory and Experiment

2012 ◽  
Author(s):  
Assaad AlSahlani ◽  
Frank B. Mathis ◽  
Ranjan Mukherjee
Keyword(s):  
Total Energy ◽  
Vibration Control ◽  
Vibration Suppression ◽  
Full Length ◽  
Experimental Results ◽  
The Other ◽  
Boundary Theory ◽  
Displacement Constraint ◽  
Simulation Results ◽  
Theory And Experiment

A new method for vibration control of a string is proposed in which a zero displacement constraint is sequentially applied and released at a point near one boundary. When the constraint is applied, the string is partitioned into two vibrating strings, one of them is much shorter in length than the other. The vibration in the shorter segment of the string decays out much faster than the longer segment due to higher frequency. After the vibration in the shorter segment has decayed, the constraint is removed and the string is allowed to vibrate in its full length. The total energy is now redistributed over the full length, and this provides the scope for application of the constraint again for further reduction of energy. Vibration suppression is achieved through sequential application and removal of the constraint and this is simulated using a linear damped model of the string. Experiments were conducted and the experimental results were found to match well with simulation results.

Determination of a Constitutive Relation for Passive Myocardium: I. A New Functional Form

1990 ◽  
Vol 112 (3) ◽  
pp. 333-339 ◽  
Author(s):  
J. D. Humphrey ◽  
R. K. Strumpf ◽  
F. C. P. Yin
Keyword(s):  
Constitutive Relation ◽  
Invariant Measures ◽  
Functional Form ◽  
Transversely Isotropic ◽  
The Other ◽  
Material Symmetry ◽  
Material Parameters ◽  
Experimental Protocols ◽  
Theory And Experiment

The specific aim of this study is to determine a constitutive relation for non-contracting myocardium in terms of a pseudostrain-energy function W whose form is guided by both theory and experiment. We assume that the material symmetry of myocardium is initially and locally transversely-isotropic, and seek a W which depends upon only two coordinate invariant measures of the finite deformation. The specific functional form of such a W is inferred directly from experimental protocols in which one invariant is held constant while the other is varied, and vice versa. On the basis of data from families of these “constant invariant” tests on thin slabs of myocardium taken from the mid-walls of six canine left ventricles, we propose a new polynomial form of W containing only five material parameters.

scholarly journals Preemption Games: Theory and Experiment

2010 ◽  
Vol 100 (4) ◽  
pp. 1778-1803 ◽  
Author(s):  
Steven T Anderson ◽  
Daniel Friedman ◽  
Ryan Oprea
Keyword(s):  
Brownian Motion ◽  
Nash Equilibrium ◽  
Laboratory Experiment ◽  
Geometric Brownian Motion ◽  
The Other ◽  
Investment Opportunity ◽  
Bayesian Nash Equilibrium ◽  
Games Theory ◽  
Investment Patterns ◽  
Theory And Experiment

Several impatient investors with private costs Ci face an indivisible irreversible investment opportunity whose value V is governed by geometric Brownian motion. The first investor i to seize the opportunity receives the entire payoff, V-Ci. We characterize the symmetric Bayesian Nash equilibrium for this game. A laboratory experiment confirms the model's main qualitative predictions: competition drastically lowers the value at which investment occurs; usually the lowest-cost investor preempts the other investors; observed investment patterns in competition (unlike monopoly) are quite insensitive to changes in the Brownian parameters. Support is more qualified for the prediction that markups decline with cost. (JEL C73, D44, D82, G31)

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