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101.
D. D. Coon A. G. U. Perera 《International Journal of Infrared and Millimeter Waves》1987,8(9):1037-1052
A new approach to focal plane processing based on silicon injection mode devices is suggested. These devices provide a natural basis for parallel asynchronous focal plane image preprocessing. The simplicity and novel properties of the devices would permit an independent analog processing channel to be dedicated to every pixel. A laminar architecture built from arrays of the devices would form a two-dimensional (2-D) array processor with a 2-D array of inputs located directly behind the focal plane detector array. A 2-D image data stream would propagate in neuronlike asynchronous pulse coded form through the laminar processor. No multiplexing, digitization or serial processing would occur in the preprocessing stage. High performance is expected because approximately linear pulse coding has already been observed for input currents ranging over six orders of magnitude down to one picoampere with noise referred to input of about 10 femtoamperes. Very low power requirements suggest utility in space and in conjunction with very large arrays. Multispectral processing is possible because of compatibility with the cryogenic environment of high performance infrared detectors. 相似文献
102.
Magnetic resonance imaging (MRI) can now provide maps of human brain function with high spatial and temporal resolution. This noninvasive technique can also map the coritical activation that occurs during focal seizures, as demonstrated here by the results obtained using a conventional 1.5 T clinical MRI system for the investigation of a 4-year-old boy suffering from frequent partial motor seizures of his right side. FLASH images (TE = 60 ms) were acquired every 10 s over a period of 25 min, and activation images derived by subtracting baseline images from images obtained during clinical seizures. Functional MRI revealed sequential activation associated with specific gyri within the left hemisphere with each of five consecutive clinical seizures, and also during a period that was not associated with a detectable clinical seizure. The activated regions included gyri that were structurally abnormal. These results demonstrate (a) that functional MRI can potentially provide new insights into the dynamic events that occur in the epileptic brain and their relationship to brain structure; and (b) that there is the possibility of obtaining similar information in the absence of clinical seizures, suggesting the potential for studies in patients with interictal electrical disturbances. 相似文献
103.
104.
根据Cosserat弹性杆的动力学普遍定理,讨论其守恒量问题. 因弹性杆的动力学方程是以截面为对象,并且是以弧坐标和时间为双自变量,其守恒量必定是以积分的形式给出,分别存在关于弧坐标或时间守恒的问题. 根据弹性杆的动量和动量矩方程,导出其动量守恒和动量矩守恒的存在条件及其表达,并讨论了关于沿中心线弧坐标的守恒问题;再分别根据弹性杆关于时间和弧坐标的能量方程导出了各自的关于时间和弧坐标的守恒量存在条件及其表达, 结果包括了弹性杆的机械能守恒以及平衡时的应变能积分;守恒问题给出了例子. 积分形式的守恒量对于弹性杆动力学的理论分析和数值计算都具有实际意义.关键词：守恒量Cosserat弹性杆动力学普遍定理双自变量 相似文献
105.
A new micromechanics constitutive model for pure dilatant transformation plasticity of structure ceramics is proposed in this
paper. Based on the thermodynamics, micromechanics and microscalet→m transformation mechanism analysis of the TZP and PSZ ZrO2-containing ceramics, an analytic expressions of the Helmholtz and complementary free energy of the constitutive element for
the case of pure dilatant transformation is derived for the first time in a self-consistent manner. By the analysis of energy
dissipation in the forward and reverse transformations, the micromechanics constitutive law is derived in the framework of
Hill-Rice's internal variable constitutive theory.
The project is supported by the National Natural Science Foundation of China. 相似文献
106.
We define a new model of interface roughening in one dimension which has the property that the minimum of interface height is conserved locally during the evolution. This model corresponds to the limit q of the q-color dimer deposition-evaporation model introduced by us earlier [Hari Menon and Dhar, J. Phys. A: Math. Gen.
28:6517 (1995)]. We present numerical evidence from Monte Carlo simulations and the exact diagonalization of the evolution operator on finite rings that growth of correlations in this model is subdiffusive with dynamical exponent z2.5. For periodic boundary conditions, the variation of the gap in the relaxation spectrum with system size appears to involve a logarithmic correction term. Some generalizations of the model are briefly discussed. 相似文献
107.
In contrast to an infinite family of explicit examples of two-dimensional p-harmonic functions obtained by G. Aronsson in the late 80s, there is very little known about the higher-dimensional case. In this paper, we show how to use isoparametric polynomials to produce diverse examples of p-harmonic and biharmonic functions. Remarkably, for some distinguished values of p and the ambient dimension n this yields first examples of rational and algebraic p-harmonic functions. Moreover, we show that there are no p-harmonic polynomials of the isoparametric type. This supports a negative answer to a question proposed in 1980 by J. Lewis. 相似文献
108.
We have demonstrated 384 × 288 pixels mid-wavelength infrared focal plane arrays (FPA) using type II InAs/GaSb superlattice (T2SL) photodetectors with pitch of 25 μm. Two p-i-n T2SL samples were grown by molecular beam epitaxy with both GaAs-like and InSb-like interface. The diode chips were realized by pixel isolation with both dry etching and wet etching method, and passivation with SiNx layer. The device one with 50% cutoff wavelength of 4.1 μm shows NETD ∼ 18 mK from 77 K to 100 K. The NETD of the other device with 50% cutoff wavelength at 5.6 μm is 10 mK at 77 K. Finally, the T2SL FPA shows high quality imaging capability at the temperature ranging from 80 K to 100 K which demonstrates the devices’ good temperature performance. 相似文献
109.
Begoña Cano Adolfo González‐Pachón 《Numerical Methods for Partial Differential Equations》2015,31(1):78-104
In this article, it is proved that explicit Lawson methods, when projected onto one of the invariants of nonlinear Schrödinger equation (norm) are also automatically projected onto another invariant (momentum) for many solutions. As this procedure is very cheap and geometric because two invariants are conserved, it offers an efficient tool to integrate some solutions of this equation till long times. On the other hand, we show a detailed study on the numerical performance of these methods against splitting ones, with fixed and variable stepsize implementation. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq31: 78–104, 2015 相似文献
110.
For locally acting drug products such as nasal aerosols and nasal sprays, the 2003 US Food and Drug Administration (FDA) draft guidance suggests that bioequivalence between generic and brand‐name products be established through in vitro tests. In addition, for non‐profile analyses based on spray content uniformity, droplet size distribution, spray pattern, priming, and re‐priming, the draft US FDA guidance recommends that the population bioequivalence (PBE) between generic and innovator's products be demonstrated. However, the linearized criterion recommended in the draft FDA guidance does not take into consideration the variations due to batches, samples, and life stages. Hence, under a two‐stage nested random effects model, we apply the methods of modified large‐sample (MLS) and generalized pivotal quantities (GPQs) to construct the upper 95% confidence limit for in vitro PBE criterion with consideration of variance components as the statistical testing procedures for establishing the in vitro BE. A simulation study was conducted to compare empirical size and empirical power among the three methods. A numerical example illustrates the proposed methods. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献