In rare cases, the use of advanced mathematical calculators can give incorrect results. One such error occurs with graphing calculators because the screen is not continuous, but a rectangular array of pixels. On some ...
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In rare cases, the use of advanced mathematical calculators can give incorrect results. One such error occurs with graphing calculators because the screen is not continuous, but a rectangular array of pixels. On some frequently used calculators, the graph of sin 80x looks like sin x. We also study other related examples.
A novel birefringent transmitarray capable of local polarization conversion in infrared regime is presented. In particular an incident beam with linear polarization can be transformed into a radially or azimuthally po...
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ISBN:
(纸本)9781479978175
A novel birefringent transmitarray capable of local polarization conversion in infrared regime is presented. In particular an incident beam with linear polarization can be transformed into a radially or azimuthally polarized vector beam and in general a wide continuum of polarization states are realizable on the higher order Poincare spheres. The transmitarray is composed of a rectangular array of double-layer double split-ring slot nanoantennas. The double layer element, chosen here, enables high transmission coefficient amplitude, thus increases the efficiency of conversion to the vector vortex beams. The array element exhibits anisotropy with respect to the field polarization on the transmitarray plane, where the transmission coefficients for two orthogonal linear polarizations are almost equal in magnitude and have almost a 180¡ã phase difference. This transmission condition is crucial in the geometric phase control method employed here and it is satisfied in a certain frequency band. The local polarization transformation on the array is controlled through manipulating the angular orientation of the slot elements with respect to element centers. Locally the phase of circularly polarized transmitted waves are advanced or delayed with a phase equal to twice the rotation angle. This phase control method is purely geometrical and it is not frequency dependent. For a certain transmitarray, the generated beam's polarization map is also a function of incident beam polarization. We then study the interesting case of azimuthally E-polarized vortex beams which are a superposition of the Laguerre Gaussian (LG) beams carrying certain orbital angular momentum (OAM) states. Such beams have a strong longitudinally polarized magnetic field on the propagation axis of the beam where the total electric field vanishes. We demonstrate analytically and through numerical field calculations, the evolution of electric and magnetic fields as the beam propagates. These finding are- partic
We study the longitudinal permeability of a spatially periodic rectangular array of circular cylinders, when a Newtonian fluid is flowing at low Reynolds number along the cylinders. The longitudinal component of the v...
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We study the longitudinal permeability of a spatially periodic rectangular array of circular cylinders, when a Newtonian fluid is flowing at low Reynolds number along the cylinders. The longitudinal component of the velocity obeys a Poisson equation which is transformed into a functional equation. This equation can be solved by the method of successive approximations. The major advantage of this technique is that the permeability of the array can be expressed analytically in terms of the radius of the cylinders and of the aspect ratio of the unit cell.
We address the problem of estimating the parameter of a Bernoulli process. This arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli t...
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ISBN:
(纸本)9781538646595
We address the problem of estimating the parameter of a Bernoulli process. This arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. We introduce a framework within which to minimize the mean-squared error (MSE) subject to an upper bound on the mean number of trials. This optimization has several simple and intuitive properties when the Bernoulli parameter has a beta prior. In addition, by exploiting typical spatial correlation using total variation regularization, we extend the developed framework to a rectangular array of Bernoulli processes representing the pixels in a natural scene. In simulations inspired by realistic active imaging scenarios, we demonstrate a 4.26 dB reduction in MSE due to the adaptive acquisition, as an average over many independent experiments and invariant to a factor of 3.4 variation in trial budget.
A novel design of the frequency invariant beamformer based on a rectangular array is proposed. There are two unique features about this design: there is no taped delay-line (TDL) or any other temporal processing invol...
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ISBN:
(纸本)9781617388767
A novel design of the frequency invariant beamformer based on a rectangular array is proposed. There are two unique features about this design: there is no taped delay-line (TDL) or any other temporal processing involved and the resultant beamformer has a full 360° azimuth angle coverage. Two design examples are provided with a satisfactory frequency invariant property.
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