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51.
Bong Ban S. Baker Curtis L. Long Dale D. 《IEEE transactions on bio-medical engineering》1976,(1):75-77
A stimulator circuit is presented which is capable of generating pulse train waveforms suitable for neurophysiological experiments are available, as well as special test conditions such as dishabituation. Digital and linear integrated circuits are used to provide precise control over the stimulus parameters. 相似文献
52.
Precise lattice parameter measurements on dislocation-free gallium arsenide were described in Part I (preceding paper).2 Detailed chemical and electrical analyses of the same samples are described here. The predictions of simple chemical models are developed in the light of the analytical results. The significant observed increase in lattice parameter due to silicon doping, in contrast to the predicted decrease, is discussed. 相似文献
53.
54.
A sensing technique using a voltage-mode architecture, noise-shaping modulator, and digital filter (a counter) is presented for use with cross-point MRAM arrays and magnetic tunnel junction memory cells. The presented technique eliminates the need for precision components, the use of calibrations, and reduces the effects of power supply noise. To obviate the effects of cell-to-cell variations in the array, a digital self-referencing scheme using the counter is presented. Measured experimental results in a 180-nm CMOS process indicate an RMS sensing noise of 20 /spl mu/V for a 5-/spl mu/s sense time. Further increases in sense time are shown to increase the signal-to-noise ratio. The current used by the sense amplifier and counter was measured as 10 /spl mu/A when running at 100 MHz or 10 mA when 1000 sense amplifiers are used with a memory subarray having 1000 bitlines. 相似文献
55.
F. Collin R. Chambon R. Charlier 《International journal for numerical methods in engineering》2006,65(11):1749-1772
In this paper, a new finite element method is described and applied. It is based on a theory developed to model poromechanical problems where the mechanical part is obeying a second gradient theory. The aim of such a work is to properly model the post localized behaviour of soils and rocks saturated with a pore fluid. Beside the development of this new coupled theory, a corresponding finite element method has been developed. The elements used are based on a weak form of the relation between the deformation gradient and the second gradient, using a field of Lagrange multipliers. The global problem is solved by a system of equations where the kinematic variables are fully coupled with the pore pressure. Some numerical experiments showing the effectiveness of the method ends the paper. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
56.
57.
Nonlinear Mohr Envelopes Based on Triaxial Data 总被引:3,自引:0,他引:3
R. Baker 《Canadian Metallurgical Quarterly》2004,130(5):498-506
A substantial amount of experimental evidence suggests that Mohr envelopes of many soils are not linear, particularly in the range of small normal stresses. This departure from linearity is significant for slope stability calculations since for a wide range of practical stability problems, critical slip surfaces are shallow and normal stresses acting on such surfaces are small. The present work presents a procedure for estimating parameters of the Mohr form of Hoek and Brown empirical failure criterion, based on triaxial data. This nonlinear Mohr envelope provides significantly better representation of experimental information than the Mohr–Coulomb criterion in cases when the data set includes tests at small enough normal stress. Application of the estimation procedure to published data sets shows that effective cohesive strength of most soils is close to zero, and Mohr envelopes are continuous at the tensile strength limit. 相似文献
58.
Collin E Defoort M Lulla K Moutonet T Heron JS Bourgeois O Bunkov YM Godfrin H 《The Review of scientific instruments》2012,83(4):045005
We report on experiments performed in vacuum and at cryogenic temperatures on a tri-port nano-electro-mechanical (NEMS) device. One port is a very nonlinear capacitive actuation, while the two others implement the magnetomotive scheme with a linear input force port and a (quasi-linear) output velocity port. We present an experimental method enabling a full characterization of the nanomechanical device harmonic response: the nonlinear capacitance function C(x) is derived, and the normal parameters k and m (spring constant and mass) of the mode under study are measured through a careful definition of the motion (in meters) and of the applied forces (in Newtons). These results are obtained with a series of purely electric measurements performed without disconnecting/reconnecting the device, and rely only on known dc properties of the circuit, making use of a thermometric property of the oscillator itself: we use the Young modulus of the coating metal as a thermometer, and the resistivity for Joule heating. The setup requires only three connecting lines without any particular matching, enabling the preservation of a high impedance NEMS environment even at MHz frequencies. The experimental data are fit to a detailed electrical and thermal model of the NEMS device, demonstrating a complete understanding of its dynamics. These methods are quite general and can be adapted (as a whole, or in parts) to a large variety of electromechanical devices. 相似文献
59.
Dislocations in the spinodal alloy Fe(30)Ni(20)Mn(25)Al(25), which is composed of alternating BCC and B2 (ordered BCC) phases, have been investigated using weak-beam transmission electron microscopy (TEM). The alloy was compressed at room temperature in an as-hot-extruded state to strains of approximately 3% for post-mortem dislocation analysis. Dislocations with a/2<111> Burgers vectors were found to glide in pairs on both {110} and {112} slip planes. TEM in situ straining experiments were also performed on both the as-extruded alloy and an arc-melted alloy. The in situ straining observations confirmed that dislocations were able to pass between both spinodal phases. Partial dislocation separations were relatively wide in the BCC phase and narrow in the B2 phase. Dislocation glide, as opposed to twinning (both of which have been observed in other BCC-based spinodals), was also found to be the only room temperature deformation mechanism. 相似文献
60.
A Database and Evaluation Methodology for Optical Flow 总被引:4,自引:0,他引:4
Simon Baker Daniel Scharstein J. P. Lewis Stefan Roth Michael J. Black Richard Szeliski 《International Journal of Computer Vision》2011,92(1):1-31
The quantitative evaluation of optical flow algorithms by Barron et al. (1994) led to significant advances in performance. The challenges for optical flow algorithms today go beyond the datasets and
evaluation methods proposed in that paper. Instead, they center on problems associated with complex natural scenes, including
nonrigid motion, real sensor noise, and motion discontinuities. We propose a new set of benchmarks and evaluation methods
for the next generation of optical flow algorithms. To that end, we contribute four types of data to test different aspects
of optical flow algorithms: (1) sequences with nonrigid motion where the ground-truth flow is determined by tracking hidden
fluorescent texture, (2) realistic synthetic sequences, (3) high frame-rate video used to study interpolation error, and (4) modified
stereo sequences of static scenes. In addition to the average angular error used by Barron et al., we compute the absolute
flow endpoint error, measures for frame interpolation error, improved statistics, and results at motion discontinuities and
in textureless regions. In October 2007, we published the performance of several well-known methods on a preliminary version
of our data to establish the current state of the art. We also made the data freely available on the web at . Subsequently a number of researchers have uploaded their results to our website and published papers using the data. A significant
improvement in performance has already been achieved. In this paper we analyze the results obtained to date and draw a large
number of conclusions from them. 相似文献