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Data was mined for the purpose of extracting data from an online source to compute and classify hydraulic geometry as well as providing additional data (channel stability, material, and evenness) for pattern discovery. Hydraulic geometry, the relationships between a stream's geometry (width and depth) and flow (velocity and discharge), is applicable to flood prediction, water resources management,...
The recent advances in thin-film thermoelectric (TE) materials have created opportunities for on-chip cooling and energy-harvesting with heat-fluxes >100W/cm2. However, it remains unclear how effective these materials are in the context of realistic microprocessor floorplan and workloads. Moreover, these TE materials suffer from contact parasitics that can significantly impact their performance...
This document details the design, implementation and analysis of a clamped-clamped capacitively-coupled beam resonator with a high Q-factor [>10000] in the VHF band [30-300MHz]. The document also draws a parallel between simulation results and theoretical results of key performance metrics of the design.
An exact solution is developed for the radial vibration characteristics of functionally graded piezoelectric cylindrical transducers. The material properties, such as mass density, elastic, piezoelectric and dielectric constants, are assumed to be the power-law functions of radial position. The material nonhomogeneity index of mass density can be different from that of elastic, piezoelectric and dielectric...
We study free vibrations of a circular AT-cut quartz resonator using the two-dimensional scalar differential equation by Tiersten and Smythe in conjunction with COMSOL. Resonant frequencies and mode shapes are obtained and compared with available experimental results as well as available analytical solutions of the scalar equation. The accuracy of various analytical solutions is examined.
SH wave propagation in a cylindrically layered magneto-electric-elastic composite consisting of a piezoelectric layer and a piezomagnetic central cylinder. Based on the spring-type relation, the imperfectly bonded interface is assumed to be damaged mechanically, magnetically and/or electrically. The magneto-electrically open and shorted conditions at the free surface are taken to solve the problem...
In this paper, we report on a dielectric study of a series of composite systems based upon a polystyrene matrix (έm ∼2.7) containing dispersed particles of lead zirconate titanate (PZT) and barium titanate (BaTiO3) (in both cases, έp ∼1000). These components were chosen to give a high dielectric contrast within the system and, because polystyrene is readily etched using permanganic reagents, the size...
This paper derives an explicit dispersion equation of SH waves propagating along the interface between a piezoelectric (PE) and a piezomagnetic (PM) half-space. It is assumed that the interface has a magneto-electro-elastic imperfect bonding. A general linear spring model, considering the spring constants of mechanical, electric and magnetic fields, simultaneously considering the coupled spring constants...
We study the horizontal shear (SH) wave problem propagating in a functionally graded piezoelectric material (FGPM) layered structure to compare the Wentzel-Kramers-Brillouin (WKB) method with the power series method. We establish coupled governing equations on the basis of elastodynamics theory. Both the WKB and power series methods are employed to solve the second-order variation coefficient equations...
In this paper, the distributions of electric field and electric displacement in a three-layer beam-like piezoelectric harvester are revisited from the accurate piezoelectricity theory. The electric displacement D3 is obtained from the Gauss theorem in electrostatics and found to be uniformly distributed along the thickness direction. The electric field is observed linearly dependent on x3. The efficiency...
Smoke environment is a common condition during the fire-fighting operation, and the change of lighting's illuminating effect in the smoke environment is the issue concerned by fire department and lighting manufacturer. According to this issue, a development on lighting's smoke penetrability performance test device was conducted, and by this device an illumination change test was made for three types...
A thermo chromic materials named Salicylaldehyde ethanolamine Schiff base was synthesized with ethanolamine and salicylaldehayde derivative in the medium of ethanol, and was characterized by means of UV-Vis absorption, GCMS. The reaction kinetics of Schiff base production was investigated through UV-Vis absorption spectra, and also the thermochromism of Schiff Base Condensed from ethanolamine and...
Firstly, the theoretical model of polystyrene external thermal insulation material fires under conditions of window fire was put forward, the equations that calculate the important characteristic parameters of these fires such as the spread height, spread rate and ignition time were derived, and the relevant analyses were preliminarily made. Secondly, on the basis of theoretical analyses, the medium...
This miniworkshop focuses on diagramming as a problem solving tool. Unfortunately, many students enter engineering without valuing the use of diagrams in model-based reasoning. Too often, they see diagramming as something which is superfluous and disconnected from "real problem solving." Students often come to their first engineering course with a well-practiced strategy that uses a rote...
This paper represent a design and simulation of a simple photovoltaic water pumping system that employs the maximum power point tracker(MPPT), a DC-DC boost converter and a DC pump motor. The main goal of this paper is to prove that fuzzy logic controller is the most effective to track the maximum power by comparing it to the most used MPPT algorithm Perturb & Observe (P&O).
In earlier work it was recommended that accelerated tests, using elevated currents, be used to evaluate the performance of contact designs using materials that may be susceptible to electro-migration. This is necessary since it was found in earlier work that the type of self-diffusion in some cases had a major impact on time to failure. Since the type of diffusion is generally not known in advance,...
A model is developed to determine the peak current required to weld large area closed contacts with ‘n’ points of contact when passing short duration, high fault currents. The model also predicts the threshold welding current for parallel contact structures used to carry large currents in high current switching devices. The model considers: (1) the total contact resistance of the closed contacts by...
The present paper describes the strategies used to compile and teach an Informatics course developed during last years at Tallinn University of Technology. The strategy is based on the main principles of blended learning and the analysis of the results of experiments with students from different faculties. Various tests were carried out to identify students' levels of knowledge and preferences in...
Compartmental models are widely used in in many fields of science including pharmacokinetics, epidemiology, bioengineering, complexity theory, and even economics and the social sciences. The reason of such a success lies in their ability to describe the way materials or energies are transmitted among the compartments. Often, it is assumed that these exchanges depend linearly on the compartments. However,...
A consistent thermoelectroelastic description of piezoelectric semiconductors with finite deformation is presented. By including both kinematic and constitutive nonlinearities as well as a proper treatment of the electrostatic conditions at free surfaces, the theory allows situations with large strains to be modeled more accurately. In addition, the theory is rotationally invariant unlike the linear...
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