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2016 Draft Statement
No full textA Draft Statement presenting the findings of the recent evaluation by the Engineering Accreditation Commission of ABET
Dependence Structures in Politics and in Reliability
No full textThis article continues our studies on local dependence in political world and reliability. We assume and derive the joint distributions between components. Then we apply measures of dependence between random events to turn them into local dependence between random variables on a rectangle in the plain. General rule is described. The political models and reliability schemes appear just as illustrations of these rules. Graphical examples should confirm the beauty, simplicity and the utility of this approach
Magneto-optic Effects in Ferrofluids
No full textFerrofluids are stable colloidal suspensions of superparamagnetic nanoparticles in a carrier liquid. The ordering and phase transitions of these polarizable media under the effect of an externally applied dc magnetic field are accompanied by a number of magneto-optic effects. Light scattering, in particular, has been used in studies investigating the kinematics of the field-induced self-assembly of nanoparticles in chain-like structures. In previous reports we discussed the correlation between the time-dependent light-scattering patterns and the creation of such field-induced ordered structures of nanoparticles in the ferrofluid. This present work is the first reported systematic study of the morphing of the light scattering patterns with the thickness of the ferrofluid layer (0.1 mm to 10 mm) and with temperature, in ferrofluids consisting of water suspensions of dextran-coated iron oxide nanoparticles. In particular we discuss the origin and angular dependence of an elliptical pattern produced by light scattered through thin layers (\u3c;1 mm) of ferrofluids and contrast it with the patterns produced by longer light paths (10 mm) through the ferrofluid
Design and Mathematical Modeling of a Fiber-optic Displacement and Force Sensor
No full textWe report on the design, mathematical modeling and preliminary development work for a novel fiber optic force sensor for applications of force sensing and force-feedback in robotic surgery and in other systems where a small passive sensor immune to electromagnetic interference (EMI) may be needed. The proposed sensor uses a novel (patent pending) approach, not reported in the existing literature, based on a fiber collimator and a four-quadrant dichroic mirror. The sensor is small enough to fit at the distal end of typical surgical devices for laparoscopic surgery (d\u3c10 mm), can be assembled from glass/dielectric materials (EMI immune) and does not require active local powering and conditioning (filtering, amplification) of the signal it produces in response to an applied external force
Method of Lines Transpose: An Efficient Unconditionally Stable Solver for Wave Propagation
No full textBuilding upon recent results obtained in Causley and Christlieb (SIAM J Numer Anal 52(1):220–235, 2014), Causley et al. (Math Comput 83(290):2763–2786, 2014, Method of lines transpose: high order L-stable O(N) schemes for parabolic equations using successive convolution, 2015), we describe an efficient second-order, unconditionally stable scheme for solving the wave equation, based on the method of lines transpose (MOLTT), and the resulting semi-discrete (i.e. continuous in space) boundary value problem. In Causley and Christlieb (SIAM J Numer Anal 52(1):220–235, 2014), unconditionally stable schemes of high order were derived, and in Causley et al. (Method of lines transpose: high order L-stable O(N) schemes for parabolic equations using successive convolution, 2015) a high order, fast O(N)O(N) spatial solver was derived, which is matrix-free and is based on dimensional-splitting. In this work, are interested in building a wave solver, and our main concern is the development of boundary conditions. We demonstrate all desired boundary conditions for a wave solver, including outflow boundary conditions, in 1D and 2D. The scheme works in a logically Cartesian fashion, and the boundary points are embedded into the regular mesh, without incurring stability restrictions, so that boundary conditions are imposed without any reduction in the order of accuracy. We demonstrate how the embedded boundary approach works in the cases of Dirichlet and Neumann boundary conditions. Further, we develop outflow and periodic boundary conditions for the MOLTT formulation. Our solver is designed to couple with particle codes, and so special attention is also paid to the implementation of point sources, and soft sources which can be used to launch waves into waveguides
Current-density vs electric-field intensity characteristics of polypropylene filled with natural clay as nanomaterial
No full textIn this study, current-density vs electric-field intensity characteristics of polypropylene-based nanocomposite films are presented with concentrations of 0%, 2% and 6% nanosize natural clay by weight. Each nanocomposite sample is subjected to a 60-Hz, sinusoidal voltage waveform. During the experiments, applied rms voltage and current are recorded as the voltage increases across the test sample. The test was repeated with five samples with the same nanofiller content. The current-density vs electric-field intensity characteristics indicate a nonlinear behavior for each sample under consideration with some degree of saturation. From these characteristics, it was observed that the inception of saturation occurred at higher electric field intensities for the nanocomposites filled with natural clay than the unfilled polypropylene. The relative permittivity of of each sample was almost constant up to a critical electric field at which the saturation starts. Above that critical electric field, relative permittivity dramatically dropped
Vibration Characteristics of a Guitar Using Finite Element and Digital Image Correlation Techniques
No full textThe sound quality generated by a musical instrument depends on the vibration characteristics (i.e., natural frequencies and mode shapes) of the instrument. In this paper, a three-dimensional finite element model of a guitar was developed using quadratic shell and solid elements. An eigensolution was performed on the FE model to extract natural frequencies and mode shapes of the instrument. In order to validate the numerical results, a measurement was performed on the guitar using the digital image correlation technique. In this measurement, the guitar was placed in a free-free configuration and was excited using a broadband excitation generated by a sound source. The response of the guitar to the excitation was recorded using a pair of high-speed cameras. The recorded images were processed in a digital image correlation program to extract its natural frequencies and mode shape. The results show a strong correlation between the numerical model and experimental results
